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Sample records for plasma-sprayed femoral components

  1. Vacuum Plasma Spray (VPS) Material Applications for Thruster Components

    Science.gov (United States)

    Elam, Sandra; Holmes, Richard; Hickman, Robert

    2006-01-01

    A variety of vacuum plasma spray (VPS) material systems have been successfully applied to injector and thrust chamber components. VPS offers a versatile fabrication process with relatively low costs to produce near net shape parts. The materials available with VPS increase operating margins and improve component life by providing superior thermal and oxidation protection in specific engine environments. Functional gradient materials (FGM) formed with VPS allow thrust chamber liners to be fabricated with GRCop-84 (an alloy of copper, chrome, and niobium) and a protective layer of NiCrAlY on the hot wall. A variety of thrust chamber liner designs have been fabricated to demonstrate the versatility of the process. Hot-fire test results have confined the improved durability and high temperature performance of the material systems for thrust chamber liners. Similar FGM s have been applied to provide superior thermal protection on injector faceplates with NiCrAlY and zirconia coatings. The durability of the applied materials has been demonstrated with hot-fire cycle testing on injector faceplates in high temperature environments. The material systems can benefit the components used in booster and main engine propulsion systems. More recent VPS efforts are focused on producing rhenium based material systems for high temperature applications to benefit in-space engines like reaction control system (RCS) thrusters.

  2. Fabrication and electrochemical performance of solid oxide fuel cell components by atmospheric and suspension plasma spray

    Institute of Scientific and Technical Information of China (English)

    XIA Wei-sheng; YANG Yun-zhen; ZHANG Hai-ou; WANG Gui-lan

    2009-01-01

    The theory of functionally graded material (FGM) was applied in the fabrication process of PEN (Positive- Electrolyte-Negative),the core component of solid oxide fuel cell (SOFC).To enhance its electrochemical performance,the functionally graded PEN of planar SOFC was prepared by atmospheric plasma spray (APS).The cross-sectional SEM micrograph and element energy spectrum of the resultant PEN were analyzed.Its interface resistance was also compared with that without the graded layers to investigate the electrochemical performance enhanced by the functionally graded layers.Moreover,a new process,suspension plasma spray (SPS) was applied to preparing the SOFC electrolyte.Higher densification of the coating by SPS,1.61%,is observed,which is helpful to effectively improve its electrical conductivity.The grain size of the electrolyte coating fabricated by SPS is also smaller than that by APS,which is more favourable to obtain the dense electrolyte coatings.To sum up,all mentioned above can prove that the hybrid process of APS and SPS could be a better approach to fabricate the PEN of SOFC stacks,in which APS is for porous electrodes and SPS for dense electrolyte.

  3. Plasma Sprayed Pour Tubes and Other Melt Handling Components for Use in Gas Atomization

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, David; Rieken, Joel; Heidloff, Andy; Besser, Matthew; Anderson, Iver

    2011-04-01

    Ames Laboratory has successfully used plasma sprayed ceramic components made from yttria stabilized zirconia as melt pouring tubes for gas atomization for many years. These tubes have proven to be strong, thermal shock resistant and versatile. Various configurations are possible both internally and externally. Accurate dimensions are achieved internally with a machined fugitive graphite mandrel and externally by diamond grinding. The previous study of the effect of spray parameters on density was extended to determine the effect of the resulting density on the thermal shock characteristics on down-quenching and up-quenching. Encouraging results also prompted investigation of the use of plasma spraying as a method to construct a melt pour exit stopper that is mechanically robust, thermal shock resistant, and not susceptible to attack by reactive melt additions. The Ames Laboratory operates two close-coupled high pressure gas atomizers. These two atomizers are designed to produce fine and coarse spherical metal powders (5{mu} to 500{mu} diameter) of many different metals and alloys. The systems vary in size, but generally the smaller atomizer can produce up to 5 kg of powder whereas the larger can produce up to 25 kg depending on the charge form and density. In order to make powders of such varying compositions, it is necessary to have melt systems capable of heating and containing the liquid charge to the desired superheat temperature prior to pouring through the atomization nozzle. For some metals and alloys this is not a problem; however for some more reactive and/or high melting materials this can pose unique challenges. Figure 1 is a schematic that illustrates the atomization system and its components.

  4. Plasma Sprayed Pour Tubes and Other Melt Handling Components for Use in Gas Atomization

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, David; Rieken, Joel; Heidloff, Andy; Besser, Matthew; Anderson, Iver

    2011-04-01

    Ames Laboratory has successfully used plasma sprayed ceramic components made from yttria stabilized zirconia as melt pouring tubes for gas atomization for many years. These tubes have proven to be strong, thermal shock resistant and versatile. Various configurations are possible both internally and externally. Accurate dimensions are achieved internally with a machined fugitive graphite mandrel and externally by diamond grinding. The previous study of the effect of spray parameters on density was extended to determine the effect of the resulting density on the thermal shock characteristics on down-quenching and up-quenching. Encouraging results also prompted investigation of the use of plasma spraying as a method to construct a melt pour exit stopper that is mechanically robust, thermal shock resistant, and not susceptible to attack by reactive melt additions. The Ames Laboratory operates two close-coupled high pressure gas atomizers. These two atomizers are designed to produce fine and coarse spherical metal powders (5{mu} to 500{mu} diameter) of many different metals and alloys. The systems vary in size, but generally the smaller atomizer can produce up to 5 kg of powder whereas the larger can produce up to 25 kg depending on the charge form and density. In order to make powders of such varying compositions, it is necessary to have melt systems capable of heating and containing the liquid charge to the desired superheat temperature prior to pouring through the atomization nozzle. For some metals and alloys this is not a problem; however for some more reactive and/or high melting materials this can pose unique challenges. Figure 1 is a schematic that illustrates the atomization system and its components.

  5. Preparation of artificial canine femoral stem with HA-Ti ladder-type coating on plasma-sprayed pure Ti substrate and its performance evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Zeng Xianlin, E-mail: zxlxhh@163.com [Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China); Li Jingfeng; Yang Shuhua; Zheng Qixin; Zou Zhenwei [Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China)

    2012-03-01

    An ideal, biological-type, artificial femoral stem prosthesis has good stability and improved bone-prosthesis bonding capacity. In the current study, pure hydroxyapatite (HA)-coated, cementless, artificial femoral stems were prepared by adopting different plasma spray powers and distances and were tested in terms of shear strength. The pure titanium (Ti) substrates, HA coatings, and composite Ti-HA ladder-type coatings prepared under vacuum and atmospheric conditions were examined to compare the shear strengths, microscopic constitutions, and structures of the coatings. The coating was fabricated and the bond strength was improved by adopting 35 kW of spray power and an 80 mm spray distance. The comparisons show that the shear strength of the Ti coating prepared under vacuum conditions was higher than that of the coating prepared under atmospheric conditions (P < 0.05). Moreover, the pressure-shear strength of the Ti + HAG + Ti + V group coating was statistically significantly different from those of the HA + Ti + V and HA + Ti + A groups (P < 0.05). The coatings were compared using scanning electron microscopy, X-ray diffraction, and infrared spectrum analysis. The composite HA-Ti ladder-type coating group, where pure Ti substrate was sprayed onto the Ti alloy under vacuum conditions, had a successive laminate structure. In addition, the intergranular bond in the HA surface layer on the gradient coating was compact and highly crystallized. Under vacuum conditions, the plasma-sprayed layer was characterized by higher tightness, moderate porosity, higher bonding strength to HA, and higher HA crystallinity. The proposed coating can be used in new, cementless, artificial femoral stems with improved bone-prosthesis bonding capacity and stability.

  6. Plasma Spray Forming

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In the course of plasma spray, the plasma jet is comprehensively functioned by such effects as thermal pinch, magnetic pinch and mechanical compression and the flow is jetting at a high speed, the energy is concentrated and its center temperature is so high as to reach upwards of 15 000 ℃ which is capable of melting various kinds of materials inclusive of ceramic, it has a broad applied prospects in the fields of automobile, electronics, telecommunications, medical treatment, air navigation & space navigati...

  7. Vacuum plasma spray coating

    Science.gov (United States)

    Holmes, Richard R.; Mckechnie, Timothy N.

    1989-01-01

    Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.

  8. A study on the fusion reactor - Development of electrical insulation coating processes for vacuum vessel components of KT-2 tokamak by plasma spray techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sang Hee; Choi, Byung Yong; Ahn, Hyun; Ju, Won Tae; Eom, You Sub [Seoul National University, Seoul (Korea, Republic of)

    1995-08-01

    For the fabrication of insulation coatings with good vacuum tightness, mechanical and electrical properties needed for voltage breaker and plasma facing components of tokamak vacuum vessel, a plasma spraying system equipped= with an improved power supply and a precision powder feeder is employed for the development of the optimum processes for ceramic insulation coatings. The material properties of the ceramic coatings for tokamak vacuum vessel components are evaluated by material tests and analyses to determine optimum processing parameters for insulation coatings. As a result of material evaluation for Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-TiO{sub 2} ceramic insulation coatings fabricated, Al{sub 2}O{sub 3}-3%TiO{sub 2} ceramic turn out to be the best insulation coating for tokamak use in respect of electrical and mechanical properties. Al{sub 2}O{sub 3} coating with dielectric strength values of more than 26 kV/mm can also be applicable to tokamak vacuum vessel components for electric insulation by improving its low adhesive strength. 23 refs., 9 tabs., 14 figs. (author)

  9. Furnace Cyclic Behavior of Plasma-Sprayed Zirconia-Yttria and Multi-Component Rare Earth Oxide Doped Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Nesbitt, James A.; McCue, Terry R.; Barrett, Charles A.; Miller, Robert A.

    2002-01-01

    Ceramic thermal barrier coatings will play an increasingly important role in advanced gas turbine engines because of their ability to enable further increases in engine temperatures. However, the coating performance and durability become a major concern under the increasingly harsh thermal cycling conditions. Advanced zirconia- and hafnia-based cluster oxide thermal barrier coatings with lower thermal conductivity and improved thermal stability are being developed using a high-heat-flux laser-rig based test approach. Although the new composition coatings were not yet optimized for cyclic durability, an initial durability screening of numerous candidate coating materials was carried out using conventional furnace cyclic tests. In this paper, furnace thermal cyclic behavior of the advanced plasma-sprayed zirconia-yttria-based thermal barrier coatings that were co-doped with multi-component rare earth oxides was investigated at 1163 C using 45 min hot cycles. The ceramic coating failure mechanisms were studied by using scanning electron microscopy combined with X-ray diffraction phase analysis after the furnace tests. The coating cyclic lifetime will be discussed in relation to coating phase structures, total dopant concentrations, and other properties.

  10. Femoral component loosening after hip resurfacing arthroplasty

    Energy Technology Data Exchange (ETDEWEB)

    Zustin, Jozef; Sauter, Guido [University Medical Centre Hamburg-Eppendorf, Institute of Pathology, Hamburg (Germany); Hahn, Michael [University Medical Centre Hamburg-Eppendorf, Center for Biomechanics and Skeletal Biology, Hamburg (Germany); Morlock, Michael M. [TUHH Hamburg University of Technology, Biomechanics Section, Hamburg (Germany); Ruether, Wolfgang [University Medical Centre Hamburg-Eppendorf, Department of Orthopaedics, Hamburg (Germany); Amling, Michael [University Medical Centre Hamburg-Eppendorf, Center for Biomechanics and Skeletal Biology, Hamburg (Germany); University Medical Centre Hamburg-Eppendorf, Department of Trauma, Hand and Reconstructive Surgery, Hamburg (Germany)

    2010-08-15

    Before the re-introduction of the current generation of total hip resurfacing arthroplasty, component loosening and osteolysis were of great concern to the orthopaedic community. Early, mid- and long-term clinical results are encouraging, but component loosening still exists. Macroscopic, contact radiographic and histopathological analyses after undecalcified preparation of bone tissue specimens were performed. To investigate the frequency and morphological patterns of the loosening of the femoral component, we analysed a series of 190 retrieved femoral remnants that were revised for aseptic failures. Thirty-five (18.4%) hips were revised for clinical and/or radiographic loosening of the femoral component. Pseudoarthrosis (n = 17; median in situ time: 16 weeks, interquartile range [IQR]: 9 to 34), collapsed osteonecrosis (n = 5; median in situ time: 79 weeks, IQR: 63 to 97), cement-socket debonding (n = 3; median in situ time: 89 weeks, IQR: 54 to 97) and at later follow-up bone-cement loosening (n = 10; median in situ time: 175 weeks; IQR 112 to 198; p =0.005) were distinct patterns of the femoral remnant-implant loosening. Fibrocartilaginous metaplasia of interface bone trabeculae (n = 38; median in situ time: 61 weeks, IQR: 32 to 138) was strongly associated with femoral component loosening (p = 0.009). Both the trabecular hyperosteoidosis (n = 32; median in situ time: 71 weeks, IQR 50 to 129) and excessive intraosseous lymphocyte infiltration (n = 12; median in situ time: 75 weeks, IQR 51 to 98) at the bone-cement interface correlated strongly with fibrocartilaginous metaplasia (p = 0.001 and p = 0.016 respectively) and all three lesions were associated with the female gender (p = 0.021, p = 0.009, and p = 0.051). Femoral component loosening at early follow-up was mostly caused by pathological changes of the femoral remnant bone tissue: pseudoarthrosis and collapsed osteonecrosis. Fibrocartilaginous metaplasia was frequently observed in hips with femoral

  11. Ultrasonic Plasma Spray--A New Plasma Spray Process

    Institute of Scientific and Technical Information of China (English)

    LU Zhi-qing; ZHANG Hua-tang; WEN Xiong-wei; LI Lu-ming

    2004-01-01

    The method of arc- ultrasonic is introduced into plasma spray process. The process of spray ZrO2-NiCoCr AlY thermal barrier coatings (TBCs) using air plasma spray (APS) process is studied. A exciting source which can be adjusted from audio frequency to several hundred thousand Hertz is designed successfully. The ultrasonic exciting source is coupled with conventional DC spraying power supply. A few ultrasonic frequencies are selected in the testing. Several parts of the coatings with the coupling arc- ultrasonic are compared with the coatings without it. The results show: with 50 kHz and 80 kHz ultrasound, the coating qualities are improved, whereas 30 kHz has an opposite effect.

  12. Good performance of a titanium femoral component in cementless hip arthroplasty in younger patients: 97 arthroplasties followed for 5-11 years

    DEFF Research Database (Denmark)

    Jacobsen, Steffen; Jensen, Frank Krieger; Poulsen, Klaus

    2003-01-01

    We performed 97 uncemented primary total hip arthroplasties in 80 patients having an average age of 50 years. The femoral implant was a titanium stem with a proximal circumferential plasma spray-coating. Three different acetabular components were used: a threaded and partly porous-coated design...... osteolysis associated with a deep infection, but no signs of proximal loosening. 3 femora had areas of minor proximal osteolysis. 16 acetabular components (14 threaded) had been revised in 13 patients. The average Harris hip score was 91 points at the latest follow-up. We conclude that the uncemented...... titanium femoral component with a circumferential porous coating performed well in these patients, most of whom were young. As reported previously, aseptic loosening of threaded acetabular components was common....

  13. Good performance of a titanium femoral component in cementless hip arthroplasty in younger patients: 97 arthroplasties followed for 5-11 years

    DEFF Research Database (Denmark)

    Jacobsen, Steffen; Jensen, Frank Krieger; Poulsen, Klaus

    2003-01-01

    We performed 97 uncemented primary total hip arthroplasties in 80 patients having an average age of 50 years. The femoral implant was a titanium stem with a proximal circumferential plasma spray-coating. Three different acetabular components were used: a threaded and partly porous-coated design...... osteolysis associated with a deep infection, but no signs of proximal loosening. 3 femora had areas of minor proximal osteolysis. 16 acetabular components (14 threaded) had been revised in 13 patients. The average Harris hip score was 91 points at the latest follow-up. We conclude that the uncemented...... titanium femoral component with a circumferential porous coating performed well in these patients, most of whom were young. As reported previously, aseptic loosening of threaded acetabular components was common....

  14. Numerical Study of Suspension Plasma Spraying

    CERN Document Server

    Farrokhpanah, Amirsaman; Mostaghimi, Javad

    2016-01-01

    A numerical study of suspension plasma spraying (SPS) is presented in the current work. The liquid suspension jet is replaced with a train of droplets containing the suspension particles injected into the plasma flow. Atomization, evaporation, and melting of different components are considered for particles as they travel towards the substrate. Effect of different parameters on particle conditions during flight and upon impact on the substrate are investigated. Initially, influence of the torch operating conditions such as inlet flow rate and power are studied. Additionally, effect of injector parameters like injection location, flow rate, and angle are examined. The model used in current study takes high temperature gradients and non-continuum effects into account. Moreover, the important effect of change in physical properties of suspension droplets as a result of evaporation is included in the model. These mainly include variations in heat transfer properties and viscosity. Utilizing this improved model, s...

  15. Extensively Coated Cementless Femoral Components in Revision Hip Arthroplasty.

    Science.gov (United States)

    Greidanus, Nelson; Antoniou, John; Paprosky, Wayne

    2000-10-01

    A septic loosening and osteolysis can compromise the available host bone in patients requiring revision hip arthroplasty. Secure fixation of revision femoral components may not be possible if reliant only on proximal femoral bone for biologic fixation or cement interdigitation. The challenge for the revision arthroplasty surgeon is to find the best method to secure the implant in a femur with deficient bone proximally that will provide stability for load bearing and motion. In addition to providing stability, the implant must be durable and maintain long-term fixation. With over 16 years of experience with fully porous coated femoral revision implants, we have found that maximizing prosthetic-bone fit in the proximal femoral diaphyseal bone provides reliable long-term fixation in the majority of femoral revision cases.

  16. Femoral revision with impaction allografting and an uncemented femoral component

    DEFF Research Database (Denmark)

    Nickelsen, T N; Erenbjerg, M; Retpen, J B

    2008-01-01

    implants 88% had no pain, 10% had slight pain and only 2% had severe pain. Thirty-eight patients had radiographic signs of remodelling of the graft and/or cortical repair. In cases with a successful outcome, the results have been encouraging in relation to clinical performance, regeneration of bone...... component revision for aseptic loosening was performed on 100 hips. In 14 cases (14%) an intraoperative fracture occurred and 7 patients (7%) had other postoperative complications. Seventeen patients (17%) required further revision, 10 because of aseptic loosening. Of 50 surviving patients with retained...

  17. Plasma spraying system with distributed controlling

    Institute of Scientific and Technical Information of China (English)

    李春旭; 陈克选; 张成

    2003-01-01

    A distributed control system is designed for plasma spraying equipment and the configurations of system software and hardware is discussed. Through founding an expert database, the spraying process parameters are worked out and the initialization and control of spraying process are realized. The plasma spraying system with this control configuration can simplify the spraying operation, improve automation level of spray process, and approach the experience criterion as soon as possible.

  18. Vacuum plasma spray applications on liquid fuel rocket engines

    Science.gov (United States)

    Mckechnie, T. N.; Zimmerman, F. R.; Bryant, M. A.

    1992-01-01

    The vacuum plasma spray process (VPS) has been developed by NASA and Rocketdyne for a variety of applications on liquid fuel rocket engines, including the Space Shuttle Main Engine. These applications encompass thermal barrier coatings which are thermal shock resistant for turbopump blades and nozzles; bond coatings for cryogenic titanium components; wear resistant coatings and materials; high conductivity copper, NaRloy-Z, combustion chamber liners, and structural nickel base material, Inconel 718, for nozzle and combustion chamber support jackets.

  19. Numerical Study of Suspension Plasma Spraying

    Science.gov (United States)

    Farrokhpanah, Amirsaman; Coyle, Thomas W.; Mostaghimi, Javad

    2017-01-01

    A numerical study of suspension plasma spraying is presented in the current work. The liquid suspension jet is replaced with a train of droplets containing the suspension particles injected into the plasma flow. Atomization, evaporation, and melting of different components are considered for droplets and particles as they travel toward the substrate. Effect of different parameters on particle conditions during flight and upon impact on the substrate is investigated. Initially, influence of the torch operating conditions such as inlet flow rate and power is studied. Additionally, effect of injector parameters like injection location, flow rate, and angle is examined. The model used in the current study takes high-temperature gradients and non-continuum effects into account. Moreover, the important effect of change in physical properties of suspension droplets as a result of evaporation is included in the model. These mainly include variations in heat transfer properties and viscosity. Utilizing this improved model, several test cases have been considered to better evaluate the effect of different parameters on the quality of particles during flight and upon impact on the substrate.

  20. Plasma-Spray Metal Coating On Foam

    Science.gov (United States)

    Cranston, J.

    1994-01-01

    Molds, forms, and other substrates made of foams coated with metals by plasma spraying. Foam might be ceramic, carbon, metallic, organic, or inorganic. After coat applied by plasma spraying, foam left intact or removed by acid leaching, conventional machining, water-jet cutting, or another suitable technique. Cores or vessels made of various foam materials plasma-coated with metals according to method useful as thermally insulating containers for foods, liquids, or gases, or as mandrels for making composite-material (matrix/fiber) parts, or making thermally insulating firewalls in automobiles.

  1. Early micromovement of the Articular Surface Replacement (ASR) femoral component

    DEFF Research Database (Denmark)

    Penny, J O; Ding, M; Varmarken, J E;

    2012-01-01

    Radiostereometric analysis (RSA) can detect early micromovement in unstable implant designs which are likely subsequently to have a high failure rate. In 2010, the Articular Surface Replacement (ASR) was withdrawn because of a high failure rate. In 19 ASR femoral components, the mean micromovemen...

  2. Analysis of Femoral Components of Cemented Total Hip- Arthroplasty

    CERN Document Server

    Singh, Shantanu

    2014-01-01

    In cemented Total Hip Arthroplasty (THA), material chosen for femoral stem and cross section of stem itself, proved to be critical parameters for, stress distribution in the femoral components, interfacial stresses and micro movements. Titanium alloy (Ti6Al4V), when used as a material for femoral stem, recorded large displacement as compared to Chromium alloy (CoCrMo) stems. This large displacement in case of Ti6Al4V caused the stem to bend inside the cement mantle, thus destroying it. Thus, CoCrMo proved to be a better in cemented THA. Failure in THA may occur at cement-stem or cement-bone interface, thus interfacial stresses and micro movements were analysed in the present study. Comparison between trapezium and circular cross section showed that, femoral stem with trapezium cross section underwent lesser amount of sliding and debonding, at both interfaces, as compared to circular cross section. Moreover, trapezium cross section also generated lower peak stresses in femoral stem and cortical femur. The pres...

  3. Laser treatment of plasma sprayed HA coatings

    NARCIS (Netherlands)

    Khor, KA; Vreeling, A; Dong, ZL; Cheang, P

    1999-01-01

    Laser treatment was conducted on plasma sprayed hydroxyapatite (HA) coatings using a Nd-YAG pulse laser. Various laser parameters were investigated. The results showed that the HA surface melted when an energy level of greater than or equal to 2 J and a spot size of 2 mm was employed during continuo

  4. Laser treatment of plasma sprayed HA coatings

    NARCIS (Netherlands)

    Khor, KA; Vreeling, A; Dong, ZL; Cheang, P

    1999-01-01

    Laser treatment was conducted on plasma sprayed hydroxyapatite (HA) coatings using a Nd-YAG pulse laser. Various laser parameters were investigated. The results showed that the HA surface melted when an energy level of greater than or equal to 2 J and a spot size of 2 mm was employed during continuo

  5. Postmortem retrieved canine THR: femoral and acetabular component interaction.

    Science.gov (United States)

    Skurla, Carolyn P; James, Susan P

    2004-01-01

    Dogs are the preferred animal model for testing of human total hip replacements (THRs). A postmortem retrieval program for clinical, cemented, canine THR was established to analyze the long-term performance of THRs in dogs and to compare that performance to postmortem retrievals of human THRs. The purpose of the present study was to analyze the interaction between the femoral and acetabular components. Thirty-eight postmortem retrievals from 29 dogs were donated and analyzed. The acetabular components (ACs) were measured for volumetric wear and graded for articulating surface damage. Femoral and acetabular components were mechanically tested for implant stability. Digital image analysis was performed on contact radiographs of transverse femoral slices. Of 14 cases with a firmly implanted femoral component (FC). 6 articulated against loose ACs. Of 24 cases with a loose FC, 16 articulated against loose ACs. Only 4 specimens had both components firmly implanted, and 14 specimens had both components loose. There was a significant positive correlation between AC volumetric wear and FC loosening; however, there was no evidence of osteolysis or wear debris induced osteolysis as seen in human postmortem retrieval studies. There was a significant but weak negative correlation between FC loosening at the cement/bone interface and AC scores reflecting damage to the rim and creep across the entire AC. Although implant-on-implant damage to the AC was expected to positively correlate with FC loosening, this was not found. Researchers need to look at interactions between AC and FC to understand how the failure of one component affects performance of the other.

  6. Plasma Spray Forming of Nanostructured Composite Coatings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The nanostructure composite coating is obtained via plasma spraying of Al2O3-13 wt pct TiO2 powder. Brittle and hard lamella results from melted nanostructured powder. Ductile nanostructured matrix forms from unmelted nanostructured particles. Through the adjustment of constituent and nanostructure, hardness/strength and toughness/ductility are balanced and overall properties of the structure composite are achieved.

  7. Effect of surgeon experience on femoral component size selection during total knee arthroplasty.

    Science.gov (United States)

    Nandi, Sumon; Bono, James V; Froimson, Mark; Jones, Morgan; Bershadsky, Boris

    2013-01-01

    Femoral component size selection during total knee arthroplasty should not vary from surgeon to surgeon for patients with the same bone size. This study explored if systematic variations in femoral component size selection exist. Thirteen surgeons' choices of femoral component size (Duracon, n = 1388; Triathlon, n = 740) were analyzed using a generalized linear model with femoral component size as the dependent variable and surgeon identification, years in practice, and adult reconstruction fellowship training as the independent variables. The model adjusted for differences in bone size. It was found that more experienced surgeons implant larger femoral components. New instruments and training protocols may be necessary to adjust for surgeon experience.

  8. The effect of femoral neck osteotomy on femoral component position of a primary cementless total hip arthroplasty.

    Science.gov (United States)

    Dimitriou, Dimitris; Tsai, Tsung-Yuan; Kwon, Young-Min

    2015-12-01

    The aim of this study was to quantify the femoral canal diameter and version at different femoral neck osteotomy locations, and to investigate the effect of the osteotomy plane on femoral component position in total hip arthroplasty (THA). Preoperative and postoperative three-dimensional models were reconstructed in 15 patients (19 hips) who underwent primary cementless THA with tapered non-anatomical femoral stem. On the pre-operative models, the osteotomy plane was simulated at different levels (-5, 0, 5, and 10 mm from the femoral saddle [piriformis fossa]) and angles (30, 40, 50, and 60° from the femoral anatomical axis). Medullary canal version and mediolateral diameter were measured on the osteotomy surfaces. On the postoperative models, the femoral neck osteotomy plane, stem anteversion and alignment were measured. The average canal diameter ranged from 22.8 to 26.3 mm at different osteotomy levels and from 20.8 to 29.0 mm at different osteotomy angles. The average canal version ranged from 11.4 to 23.2° at different resection levels and from 12.8 to 21° at different resection angles. The femoral stem anteversion was correlated with neck osteotomy angle (R = 0.72), whereas stem alignment in frontal plane (varus/valgus) was correlated with neck osteotomy level (R = 0.87). The femoral neck osteotomy plane in THA affects the postoperative stem position due to the complex morphology of the proximal femoral medullary canal, suggesting that both femoral neck resection level and angle should be considered in optimizing femoral component alignment in THA patients.

  9. Structure and property evaluation of a vacuum plasma sprayed nanostructured tungsten-hafnium carbide bulk composite

    NARCIS (Netherlands)

    Rea, K. E.; Viswanathan, V.; Kruize, A.; De Hosson, J. Th. M.; O'Dell, S.; McKechnie, T.; Rajagopalan, S.; Vaidyanathan, R.; Seal, S.; O’Dell, S.

    2008-01-01

    Vacuum plasma spray (VPS) forming of tungsten-based metal matrix nanocomposites (MMCs) has shown to be a cost effective and time saving method for the formation of bulk monolithic nanostructured then no-mechanical components. Spray drying of powder feedstock appears to have a significant effect on

  10. Numerical Simulation of Residual Stress Distributions in Plasma-Sprayed Coating on Thick Wall Component%基于Nastran等离子喷涂厚壁零件涂层中残余应力分析

    Institute of Scientific and Technical Information of China (English)

    牛丽萍; 张延安; 史冠勇; 赫冀成

    2012-01-01

    The residual stress distributions in the plasma sprayed coatings on thick wall component were modeled and numerically simulated in finite element method, based on the software package Nastran. The impacts of the coating conditions, including the species of the coating and substrate, I. E. Ceramic or metal, on the residual stress were evaluated. The simulated results show that the strongest stress distribution exists at the coating/substrate interface, increasing in the radial direction and peaking at the edges; and that the normal stress in the central area of the substrate decreases with an increase in substrate depth, and linearly distributes in the coating. Various key factors, including the dimensionless equation of radial stress, shear stress, maximum stain and immersion depth of the residual stress in the coating, were determined . The results, calculated with the dimensionless equation, agree fairly well with the simulated ones in all the coating/ substrate systems of interest. The influence of various factors, such as the thickness and elastic modulus of the coating, and the radius and modulus of the substrates, on the variations in the residual stress distributions was also tentatively discussed.%基于有限元数值分析对等离子喷涂不同的基体上的喷涂陶瓷涂层和金属涂层中残余应力进行了分析,结果表明:涂层与基体体系的最大应力分布在接触界面附近,由中心线向外依次递增,在边缘处达到最大值.在体系中心区域正应力沿厚度方向逐渐减小,而在涂层中应力分布则趋于线性;建立了涂层中各残余应力分量的准数方程式,准数方程式与数值计算结果显示了较好的吻合,而且对于不同基体-涂层体系均是适用的.无因次最大径向应变、无因次剪应力侵入深度和无因次最大径向应力的大小均取决于涂层厚度与弹性模量的积和基体半径与基体弹性模量积之间比值,而影响无因次径向最大剪应

  11. Plasma sprayed coatings on crankshaft used steels

    Science.gov (United States)

    Mahu, G.; Munteanu, C.; Istrate, B.; Benchea, M.

    2017-08-01

    Plasma spray coatings may be an alternative to conventional heat treatment of main journals and crankpins of the crankshaft. The applications of plasma coatings are various and present multiple advantages compared to electric arc wire spraying or flame spraying. The study examines the layers sprayed with the following powders: Cr3C2- 25(Ni 20Cr), Al2O3- 13TiO2, Cr2O3-SiO2- TiO2 on the surface of steels used in the construction of a crankshaft (C45). The plasma spray coatings were made with the Spray wizard 9MCE facility at atmospheric pressure. The samples were analyzed in terms of micro and morphological using optical microscopy, scanning electron microscopy and X-ray diffraction. Wear tests on samples that have undergone simulates extreme working conditions of the crankshafts. In order to emphasize adherence to the base material sprayed layer, were carried out tests of microscratches and micro-indentation. Results have showed a relatively compact morphological aspect given by the successive coatings with splat-like specific structures. Following the microscratch analysis it can be concluded that Al2O3-13TiO2 coating has a higher purpose in terms of hardness compared to Cr3C2-(Ni 20Cr) and Cr2O3-SiO2- TiO2 powders. Thermal coatings of the deposited powders have increased the mechanical properties of the material. The results stand to confirm that plasma sprayed Al2O3-13TiO2 powder is in fact a efficient solution for preventing mechanical wear, even with a faulty lubrication system.

  12. Study of Multi-Function Micro-Plasma Spraying Technology

    Institute of Scientific and Technical Information of China (English)

    WANG Liuying; WANG Hangong; HUA Shaochun; CAO Xiaoping

    2007-01-01

    A multi-functional micro-arc plasma spraying system was developed according to aerodynamics and plasma spray theory. The soft switch IGBT (Insulated Gate Bipolar Transistor) invert technique, micro-computer control technique, convergent-divergent nozzle structure and axial powder feeding techniques have been adopted in the design of the micro-arc plasma spraying system. It is not only characterized by a small volume, a light weight, highly accurate control, high deposition efficiency and high reliability, but also has multi-functions in plasma spraying, welding and quenching. The experimental results showed that the system can produce a supersonic flame at a low power, spray Al2O3 particles at an average speed up to 430 m/s, and make nanostructured AT13 coatings with an average bonding strength of 42.7 MPa. Compared to conventional 9M plasma spraying with a higher power, the coatings with almost the same properties as those by conventional plasma spray can be deposited by multi-functional micro-arc plasma spraying with a lower power plasma arc due to an improved power supply design, spray gun structure and powder feeding method. Moreover, this system is suitable for working with thin parts and undertaking on site repairs, and as a result, the application of plasma spraying will be greatly extended.

  13. Radio Frequencv Induction Plasma Spraying of Molybdenum

    Institute of Scientific and Technical Information of China (English)

    Jiang Xianliang(蒋显亮); Maher Boulos

    2003-01-01

    Radio frequency (RF) induction plasma was used to make free-standing depositionof molybdenum (Mo). The phenomena of particle melting, flattening, and stacking were inves-tigated. The effect of process parameters such as plasma power, chamber pressure, and spraydistance on the phenomena mentioned above was studied. Scanning electron microscopy (SEM)was used to analyze the plasma-processed powder, splats formed, and deposits obtained. Exper-imental results show that less Mo particles are spheroidized when compared to the number ofspheroidized tungsten (W) particles at the same powder feed rate under the same plasma spraycondition. Molten Mo particles can be sufficiently flattened on substrate. The influence of theprocess parameters on the flattening behavior is not significant. Mo deposit is not as dense as Wdeposit, due to the splash and low impact of molten Mo particles. Oxidation of the Mo powderwith a large particle size is not evident under the low pressure plasma spray.

  14. Development of Expert Controller for Plasma Spraying Process

    Institute of Scientific and Technical Information of China (English)

    LIChun-xu; CHENKe-xuan; LIHe-qi; LIDe-wu

    2004-01-01

    Aiming at the plasma spraying process control, the control system model is developed on the basis of analyzing control parameters and coating properties and their correlation, and the corresponding control method and regulations are also given. With the developed expert controller for plasma spraying process, stable spraying can be realized using ordinary spraying powder and the coating of compaction, homogeneity and high bonding strength can be obtained.

  15. Characteristics of Plasma Spraying Torch with a Hollow Cathode

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A kind of plasma spraying torch with a hollow cathode is described in this paper.The plasma torch can be used for axial powder injection in plasma spray studies. The arc characteristics of the plasma torch with various gas flowrates, different gas media, are presented. The mathematical modeling and computational method are developed for predicting the temperature and velocity field inside the plasma torch.

  16. Plasma Processes : Plasma sprayed alumina coatings for radiation detector development

    Indian Academy of Sciences (India)

    Mary Alex; V Balagi; K R Prasad; K P Sreekumar; P V Ananthapadmanabhan

    2000-11-01

    Conventional design of radiation detectors uses sintered ceramic insulating modules. The major drawback of these ceramic components is their inherent brittleness. Ion chambers, in which these ceramic spacers are replaced by metallic components with plasma spray coated alumina, have been developed in our Research Centre. These components act as thin spacers that have good mechanical strength as well as high electrical insulation and replace alumina insulators with the same dimensions. As a result, the design of the beam loss monitor ion chamber for CAT could be simplified by coating the outer surface of the HT electrode with alumina. One of the chambers developed for isotope calibrator for brachytherapy gamma sources has its outer aluminium electrode (60 mm dia × 220 mm long) coated with 250 thick alumina (97%) + titania (3%). In view of potential applications in neutron-sensitive ion chambers used in reactor control instrumentation, studies were carried out on alumina 100 to 500 thick coatings on copper, aluminium and SS components. The electrical insulation varied from 108 ohms to 1012 ohms for coating thicknesses above 200 . The porosity in the coating resulted in some fall in electrical insulation due to moisture absorption. An improvement could be achieved by providing the ceramic surface with moisture-repellent silicone oil coating. Irradiation at Apsara reactor core location showed that the coating on aluminium was found to be unaffected after exposure to 1017 nvt fluence.

  17. Topographical analysis of the femoral components of ex vivo total knee replacements.

    Science.gov (United States)

    Scholes, Susan C; Kennard, Emma; Gangadharan, Rajkumar; Weir, David; Holland, Jim; Deehan, David; Joyce, Thomas J

    2013-02-01

    With greater numbers of primary knee replacements now performed in younger patients there is a demand for improved performance. Surface roughness of the femoral component has been proposed as a causative mechanism for premature prosthesis failure. Nineteen retrieved total knee replacements were analysed using a non-contacting profilometer to measure the femoral component surface roughness. The Hood technique was used to analyse the wear and surface damage of the matching ultra-high molecular weight polyethylene (UHMWPE) tibial components. All femoral components were shown to be up to 11× rougher after their time in vivo while 95 % showed a change in skewness, further indicating wear. This increase in roughness occurred relatively soon after implantation (within 1 year) and remained unchanged thereafter. Mostly, this roughness was more apparent on the lateral condyle than the medial. This increased femoral surface roughness likely led to damage of the UHMWPE tibial component and increased Hood scores.

  18. Thermomechanical processing of plasma sprayed intermetallic sheets

    Energy Technology Data Exchange (ETDEWEB)

    Hajaligol, Mohammad R. (Midlothian, VA); Scorey, Clive (Cheshire, CT); Sikka, Vinod K. (Oak Ridge, TN); Deevi, Seetharama C. (Midlothian, VA); Fleischhauer, Grier (Midlothian, VA); Lilly, Jr., A. Clifton (Chesterfield, VA); German, Randall M. (State College, PA)

    2001-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  19. Thermal Expansion of Vacuum Plasma Sprayed Coatings

    Science.gov (United States)

    Raj, S V.; Palczer, A. R.

    2010-01-01

    Metallic Cu-8%Cr, Cu-26%Cr, Cu-8%Cr-1%Al, NiAl and NiCrAlY monolithic coatings were fabricated by vacuum plasma spray deposition processes for thermal expansion property measurements between 293 and 1223 K. The corrected thermal expansion, (DL/L(sub 0) varies with the absolute temperature, T, as (DL/L(sub 0) = A(T - 293)(sup 3) + BIT - 293)(sup 2) + C(T - 293) + D, where, A, B, C and D are thermal, regression constants. Excellent reproducibility was observed for all of the coatings except for data obtained on the Cu-8%Cr and Cu-26%Cr coatings in the first heat-up cycle, which deviated from those determined in the subsequent cycles. This deviation is attributed to the presence of residual stresses developed during the spraying of the coatings, which are relieved after the first heat-up cycle. In the cases of Cu-8%Cr and NiAl, the thermal expansion data were observed to be reproducible for three specimens. The linear expansion data for Cu-8% Cr and Cu-26%Cr agree extremely well with rule of mixture (ROM) predictions. Comparison of the data for the Cu-8%Cr coating with literature data for Cr and Cu revealed that the thermal expansion behavior of this alloy is determined by the Cu-rich matrix. The data for NiAl and NiCrAlY are in excellent agreement with published results irrespective of composition and the methods used for processing the materials. The implications of these results on coating GRCop-84 copper alloy combustor liners for reusable launch vehicles are discussed.

  20. Influence of a secondary downsizing of the femoral component on the extension gap: a cadaveric study.

    Science.gov (United States)

    Sriphirom, Pornpavit; Raungthong, Nathee; Chutchawan, Pirapon; Thiranon, Chaiyot; Sukandhavesa, Nantawit

    2012-10-01

    The purpose of this study was to evaluate the effect of a secondary reduction of the femoral component size on flexion and extension gaps intraoperatively in posterior-stabilized total knee arthroplasty (PS-TKA) monitored by computer-assisted surgery. The authors hypothesized that cutting additional bone on the posterior femoral condyle may increase the extension gap due to the posterior capsule and soft tissue loosening. Reduction of the femoral component size was performed by additional 4-in-1 cuts after the PS-TKA on 15 cadaveric knees using a ligamentous tension device with the aid of computer-assisted surgery. Measurements of the medial and lateral flexion gaps, as well as the medial and lateral extension gaps, were recorded before and after reducing the femoral component size. Trial components were used from a mobile-bearing total knee system.After reducing the femoral component size, the medial and lateral flexion and extension gaps measured larger than their initial size. The mean increases of the medial extension and flexion gaps and the lateral extension and flexion gaps were 1.3 ± 0.9, 1.0 ± 1.2, 1.1 ± 1.2, and 1.3 ± 1.3 mm, respectively; all 4 differences were significant (P ≤ .05). Surgeons should be aware of the effect of downsizing components intraoperatively because it might lead to an extension laxity. Thus, a downsizing of the femoral component may compromise the postoperative stability of TKA.

  1. Plasma spray deposition of graded metal-ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Musil, J. (Inst. of Tech. and Reliability of Structures, Czechoslovak Academy of Sciences, Plzen (Czechoslovakia)); Fiala, J. (Central Research Inst., Plzen (Czechoslovakia))

    1992-05-20

    Plasma spraying of graded coatings is described and the metal-ceramic interface of the graded intermediate zone is analysed in terms of a simple physical model. Special attention is devoted to the dominant deposition parameters, powder characteristics and the injector configuration for powder feeding, which play a fundamental role in graded coating deposition with controlled formation of a metal-ceramic intermediate zone. On the basis of a knowledge of these parameters, a new and original formula for the coefficient of homogeneity for simultaneous deposition of metal and ceramic particles at the same spot on the substrate is derived. Furthermore, very interesting topotactical relations are described for the metal-ceramic interface of the graded zone. Various techniques of structural analysis (X-ray diffraction, scanning electron microscopy, optical microscopy) and simple thermodynamic calculations allow a new interpretation to be given of the bonding between the metal and ceramic components. The cohesion of graded metal-ceramic coatings is predicted to be higher than that of ceramic coatings with a metallic bond layer. The results are illustrated by a NiCr-ZrO{sub 2}(MgO) graded coating. (orig.).

  2. Plasma spray for forming nanostructured thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    LIN; Feng; JIANG; Xian-liang; YU; Yue-guang; ZENG; Ke-li; REN; Xian-jing

    2005-01-01

    Nanocrystalline powders of yttrium partially stabilized zirconia (YPSZ) are reprocessed into agglomerated feedstocks for plasma spraying thermal barrier coatings (TBCs), using the methods of ball milling, slurry dispersion, spray drying, and heat treatment. Atmospheric plasma is used to spray the agglomerated nanocrystalline particle feedstocks and coatings were deposited on the substrate of Ni-based superalloy. Scanning electron microscopy (SEM) is used to examine the morphology and cross-section of the agglomerated feedstocks and the free-section and cross-section of the nanostructured TBCs. Experimental results show that the agglomerated nanocrystalline particles are spherical and dense. Unlike conventional plasma-sprayed coatings, the micron/nano/micron sandwich structure can be found in the nanostructured YPSZ coatings deposited by atmospheric plasma spraying.

  3. Gas Permeability of Porous Plasma-Sprayed Coatings

    Science.gov (United States)

    Wittmann-Ténèze, K.; Caron, N.; Alexandre, S.

    2008-12-01

    For different applications, such as solid oxide fuel cells, there is an interest in understanding the relationship between the microstructure and the gas permeability of plasma-sprayed coatings. Nevertheless, plasma spraying processes allow to elaborate coatings with singular microstructures, depending strongly on the initial material and plasma operating conditions. And so, the evolution of permeability is not directly linked to the porosity. In this work, coatings were manufactured using different initial feedstock and spray parameters to obtain various microporous structures. Measurements of their permeation with the pressure drop method and their open porosity just as the observation of the morphology and the structure by optical microscopy were achieved. The different data show that the evolution of the gas permeability with the open porosity follows the Kozeny-Carman equation. This result correlated with the microstructural observation highlights the relationship between the permeability and the physical properties of porous plasma-sprayed layers.

  4. Femoral component rotation and arthrofibrosis following mobile-bearing total knee arthroplasty.

    Science.gov (United States)

    Boldt, J G; Stiehl, J B; Hodler, J; Zanetti, M; Munzinger, U

    2006-10-01

    The purpose of this study was to evaluate the femoral component rotation in a small subset of patients who had developed arthrofibrosis after mobile-bearing total knee arthroplasty (TKA). Arthrofibrosis was defined as flexion less than 90 degrees or a flexion contracture greater than 10 degrees following TKA. From a consecutive cohort of 3,058 mobile-bearing TKAs, 49 (1.6%) patients were diagnosed as having arthrofibrosis, of which 38 (86%) could be recruited for clinical assessment. Femoral rotation of a control group of 38 asymptomatic TKA patients matched for age, gender, and body mass index was also evaluated. The surgical epicondylar axis was compared with the posterior condylar axis for the femoral prosthesis. Femoral components in the arthrofibrosis group were significantly internally rotated by a mean of 4.7 degrees (SD 2.2 degrees , range 10 degrees internal to 1 degrees external). In the control group, the femoral component had a mean 0.3 degrees internal rotation (SD 2.3 degrees , range 4 degrees internal to 6 degrees external). Following mobile-bearing TKA, there is a significant correlation between internal femoral component rotation and chronic arthrofibrosis.

  5. Coupling failure between stem and femoral component in a constrained revision total knee arthroplasty.

    LENUS (Irish Health Repository)

    Butt, Ahsan Javed

    2013-02-01

    Knee revision using constrained implants is associated with greater stresses on the implant and interface surfaces. The present report describes a case of failure of the screw coupling between the stem and the femoral component. The cause of the failure is surmised with outline of the treatment in this case with extensive femoral bone loss. Revision implant stability was augmented with the use of a cemented femoral stem, screw fixation and the metaphyseal sleeve of an S-ROM modular hip system (DePuy international Ltd).

  6. Research of Plasma Spraying Process on Aluminum-Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Patricija Kavaliauskaitė

    2016-04-01

    Full Text Available The article examines plasma sprayed 95Ni-5Al coatings on alu-minum-magnesium (Mg ≈ 2,6‒3,6 % alloy substrate. Alumi-num-magnesium samples prior spraying were prepared with mechanical treatment (blasting with Al2O3. 95Ni-5Al coatings on aluminum-magnesium alloys were sprayed with different parameters of process and coating‘s thickness, porosity, micro-hardness and microstructure were evaluated. Also numerical simulations in electric and magnetic phenomena of plasma spray-ing were carried out.

  7. Microstructure and Properties of Plasma Spraying Boron Carbide Coating

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Microstructure of plasma spray boron carbide coating was studied by SEM and TEM. Its physical,mechanical and electrical properties were measured. The results showed that high microhardness,modulus and Iow porosity of B4C coating were manufactured by plasma spray. It was lamellar packing and dense. The B4C coating examined here contained two principal structures and two impurity phase besides major phase. The relatively small value of Young′s modulus, comparing with that of the bulk materials, is explained by porosity. The Fe impurity phase could account for the relatively high electrical conductivity of boron carbide coating by comparing with the general boron carbide materials.

  8. Metallurgy and properties of plasma spray formed materials

    Science.gov (United States)

    Mckechnie, T. N.; Liaw, Y. K.; Zimmerman, F. R.; Poorman, R. M.

    1992-01-01

    Understanding the fundamental metallurgy of vacuum plasma spray formed materials is the key to enhancing and developing full material properties. Investigations have shown that the microstructure of plasma sprayed materials must evolve from a powder splat morphology to a recrystallized grain structure to assure high strength and ductility. A fully, or near fully, dense material that exhibits a powder splat morphology will perform as a brittle material compared to a recrystallized grain structure for the same amount of porosity. Metallurgy and material properties of nickel, iron, and copper base alloys will be presented and correlated to microstructure.

  9. Plasma sprayed and electrospark deposited zirconium metal diffusion barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Hollis, Kendall J [Los Alamos National Laboratory; Pena, Maria I [Los Alamos National Laboratory

    2010-01-01

    Zirconium metal coatings applied by plasma spraying and electrospark deposition (ESD) have been investigated for use as diffusion barrier coatings on low enrichment uranium fuel for research nuclear reactors. The coatings have been applied to both stainless steel as a surrogate and to simulated nuclear fuel uranium-molybdenum alloy substrates. Deposition parameter development accompanied by coating characterization has been performed. The structure of the plasma sprayed coating was shown to vary with transferred arc current during deposition. The structure of ESD coatings was shown to vary with the capacitance of the deposition equipment.

  10. Preparation of thermal barrier coatings by ultrasonic plasma spraying

    Institute of Scientific and Technical Information of China (English)

    WEN Xiong-wei; LI Lu-ming; ZHANG Hua-tang; HAO Hong-wei; LU Zhi-qing

    2004-01-01

    Modulated plasma arc not only can heat the powder, but also can excite ultrasonic of different frequencies and different powers. The principles and characters of the plasma arc-excited ultrasonic were described, and the ultrasonic plasma spraying was compared with normal plasma spraying. Zirconia thermal barrier coatings (TBCs) were fabricated with two kinds of method. The TBCs were studied by the optical microscope observation, SEM observation and bonding strength experiment. The results show that suitable ultrasonic changes the performance and microstructure of TBCs in evidence. And the mechanism of ultrasonic influencing the TBCs was also discussed.

  11. Computer navigation experience in hip resurfacing improves femoral component alignment using a conventional jig

    Directory of Open Access Journals (Sweden)

    Zachary Morison

    2013-01-01

    Full Text Available Background:The use of computer navigation has been shown to improve the accuracy of femoral component placement compared to conventional instrumentation in hip resurfacing. Whether exposure to computer navigation improves accuracy when the procedure is subsequently performed with conventional instrumentation without navigation has not been explored. We examined whether femoral component alignment utilizing a conventional jig improves following experience with the use of imageless computer navigation for hip resurfacing. Materials and Methods:Between December 2004 and December 2008, 213 consecutive hip resurfacings were performed by a single surgeon. The first 17 (Cohort 1 and the last 9 (Cohort 2 hip resurfacings were performed using a conventional guidewire alignment jig. In 187 cases, the femoral component was implanted using the imageless computer navigation. Cohorts 1 and 2 were compared for femoral component alignment accuracy. Results:All components in Cohort 2 achieved the position determined by the preoperative plan. The mean deviation of the stem-shaft angle (SSA from the preoperatively planned target position was 2.2° in Cohort 2 and 5.6° in Cohort 1 ( P = 0.01. Four implants in Cohort 1 were positioned at least 10° varus compared to the target SSA position and another four were retroverted. Conclusions: Femoral component placement utilizing conventional instrumentation may be more accurate following experience using imageless computer navigation.

  12. External rotation of the femoral component decreases patellofemoral contact stress in total knee arthroplasty.

    Science.gov (United States)

    Terashima, Takashi; Onodera, Tomohiro; Sawaguchi, Naohiro; Kasahara, Yasuhiko; Majima, Tokifumi

    2015-11-01

    The purpose of this study was to investigate the relationship between patellofemoral (PF) contact stress in vivo and the alignment of the femoral component in patients after total knee arthroplasty (TKA). Thirty knees with medial compartment osteoarthritis that underwent mobile-bearing TKA with modified gap technique were evaluated. Surgery was performed using a subvastus approach to eliminate the effect of the approach to muscle balance, with a computed tomography-based navigation system (Vector Vision 1.61; Brain Lab, Heimstetten, Germany). PF contact stress was measured by a Flexiforce pressure sensor (Nitta Co., Ltd., Osaka, Japan) intraoperatively, and the results were compared with the alignment of the femoral component after TKA. The PF contact stress was not correlated with sagittal and coronal alignment of the femoral component and patellar tracking, whereas rotational alignment of the femoral component was negatively correlated with PF contact stress (r = -0.718, p correlated with PF contact stress. PF contact stress decreased more as the femoral component rotated more externally. Case control study, Level III.

  13. Alignment Fixtures For Vacuum-Plasma-Spray Gun

    Science.gov (United States)

    Woodford, William H.; Mckechnie, Timothy N.; Power, Christopher A.; Daniel, Ronald L., Jr.

    1993-01-01

    Fixtures for alignment of vacuum-plasma-spray guns built. Each fixture designed to fit specific gun and holds small, battery-powered laser on centerline of gun. Laser beam projects small red dot where centerline intersects surface of workpiece to be sprayed. After laser beam positioned on surface of workpiece, fixture removed from gun and spraying proceeds.

  14. Preventing Clogging In A Vacuum Plasma Spray Gun

    Science.gov (United States)

    Krotz, Phillip D.; Daniel, Ronald L., Jr.; Davis, William M.

    1994-01-01

    Modification of powder-injection ports enables lengthy, high-temperature deposition operations. Graphite inserts prevent clogging of ports through which copper powder injected into vacuum plasma spray (VPS) gun. Graphite liners eliminate need to spend production time refurbishing VPS gun, reducing cost of production and increasing productivity. Concept also applied to other material systems used for net-shape fabrication via VPS.

  15. Modelling the Plasma Jet in Multi-Arc Plasma Spraying

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Schein, J.; Zimmermann, S.; Möhwald, K.; Lummer, C.

    2016-08-01

    Particle in-flight characteristics in atmospheric plasma spraying process are determined by impulse and heat energy transferred between the plasma jet and injected powder particles. One of the important factors for the quality of the plasma-sprayed coatings is thus the distribution of plasma gas temperatures and velocities in plasma jet. Plasma jets generated by conventional single-arc plasma spraying systems and their interaction with powder particles were subject matter of intensive research. However, this does not apply to plasma jets generated by means of multi-arc plasma spraying systems yet. In this study, a numerical model has been developed which is designated to dealing with the flow characteristics of the plasma jet generated by means of a three-cathode spraying system. The upstream flow conditions, which were calculated using a priori conducted plasma generator simulations, have been coupled to the plasma jet simulations. The significances of the relevant numerical assumptions and aspects of the models are analyzed. The focus is placed on to the turbulence and diffusion/demixing modelling. A critical evaluation of the prediction power of the models is conducted by comparing the numerical results to the experimental results determined by means of emission spectroscopic computed tomography. It is evident that the numerical models exhibit a good accuracy for their intended use.

  16. Reliability of plasma-sprayed coatings: monitoring the plasma spray process and improving the quality of coatings

    Science.gov (United States)

    Fauchais, P.; Vardelle, M.; Vardelle, A.

    2013-06-01

    As for every coating technology, the reliability and reproducibility of coatings are essential for the development of the plasma spraying technology in industrial manufacturing. They mainly depend on the process reliability, equipment and spray booth maintenance, operator training and certification, implementation and use of consistent production practices and standardization of coating testing. This paper deals with the first issue, that is the monitoring and control of the plasma spray process; it does not tackle the coating characterization and testing methods. It begins with a short history of coating quality improvement under plasma spray conditions over the last few decades, details the plasma spray torches used in the industry, the development of the measurements of in-flight and impacting particle parameters and then of sensors. It concludes with the process maps that describe the interrelations between the operating parameters of the spray process, in-flight particle characteristics and coating properties and with the potential of in situ monitoring of the process by artificial neural networks and fuzzy logic methods.

  17. The influence of malrotation and femoral component material on patellofemoral wear during gait.

    Science.gov (United States)

    Vanbiervliet, J; Bellemans, J; Verlinden, C; Luyckx, J P; Labey, L; Innocenti, B; Vandenneucker, H

    2011-10-01

    Complications involving the patellofemoral joint, caused by malrotation of the femoral component during total knee replacement, are an important cause of persistent pain and failure leading to revision surgery. The aim of this study was to determine and quantify the influence of femoral component malrotation on patellofemoral wear, and to determine whether or not there is a difference in the rate of wear of the patellar component when articulated against oxidised zirconium (OxZr) and cobalt-chrome (CoCr) components. An in vitro method was used to simulate patellar maltracking for both materials. Both rates of wear and changes in height on the patellar articular surface were measured. The mean rates of wear measured were very small compared to standard tibiofemoral wear rates. When data for each femoral component material were pooled, the mean rate of wear was 0.19 mm3/Mcycle (sd 0.21) for OxZr and 0.34 mm3/Mcycle (sd 0.335) for CoCr. The largest change in height on each patella varied from -0.05 mm to -0.33 mm over the different configurations. The results suggest that patellar maltracking due to an internally rotated femoral component leads to an increased mean patellar wear. Although not statistically significant, the mean wear production may be lower for OxZr than for CoCr components.

  18. Structure and property evaluation of a vacuum plasma sprayed nanostructured tungsten-hafnium carbide bulk composite

    Energy Technology Data Exchange (ETDEWEB)

    Rea, K.E.; Viswanathan, V.; Kruize, A. [Surface Engineering and Nanotechnology Facility (SNF), University of Central Florida, Eng. 381, 4000 Central Florida Blvd., Orlando, FL 32816 (United States); AMPAC, Department of Mechanical, Materials, and Aerospace Engineering (MMAE), Nanoscience and Technology Center, University of Central Florida, Eng. 381, 4000 Central Florida Blvd., Orlando, FL 32816 (United States); Hosson, J.Th.M. de [Department of Applied Physics, University of Groningen, Nijenborgh 4, NL-9747 AG (Netherlands); O' Dell, S.; McKechnie, T. [Plasma Processes, Inc., 4914 Moores Mill Road, Huntsville, AL 35811 (United States); Rajagopalan, S.; Vaidyanathan, R. [AMPAC, Department of Mechanical, Materials, and Aerospace Engineering (MMAE), Nanoscience and Technology Center, University of Central Florida, Eng. 381, 4000 Central Florida Blvd., Orlando, FL 32816 (United States); Seal, S. [Surface Engineering and Nanotechnology Facility (SNF), University of Central Florida, Eng. 381, 4000 Central Florida Blvd., Orlando, FL 32816 (United States); AMPAC, Department of Mechanical, Materials, and Aerospace Engineering (MMAE), Nanoscience and Technology Center, University of Central Florida, Eng. 381, 4000 Central Florida Blvd., Orlando, FL 32816 (United States)], E-mail: sseal@mail.ucf.edu

    2008-03-25

    Vacuum plasma spray (VPS) forming of tungsten-based metal matrix nanocomposites (MMCs) has shown to be a cost effective and time saving method for the formation of bulk monolithic nanostructured thermo-mechanical components. Spray drying of powder feedstock appears to have a significant effect on the improved mechanical properties of the bulk nanocomposite. The reported elastic modulus of the nanocomposite nearly doubles due to the presence of HfC nano particulates in the W matrix. High resolution transmission electron microscopy (HRTEM) revealed the retention of nanostructures at the select process conditions and is correlated with the enhanced mechanical properties of the nanocomposite.

  19. The relationship between the microstructure and thermal diffusivity of plasma-sprayed tungsten coatings

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, C. [National Research Council Canada, Boucherville, Quebec (Canada); Boire-Lavigne, S.; Saint-Jacques, R.G. [INRS-Energie et Materiaux, Varennes, Quebec (Canada)

    1994-12-31

    Tungsten and tungsten alloy coatings are candidate materials for plasma facing components of divertor plates in future fusion reactors. In normal operation, the sprayed coatings will be submitted to intense heat fluxes and particle bombardment. This work intends to investigate the relationship between the microstructure of plasma-sprayed tungsten coatings and their thermal diffusivity as determined by the laser flash method. The microstructural investigation was carried out on copper-infiltrated coatings. Such a preparation technique permitted the measurement of the total real contact area between the lamellae within the tungsten coatings. The spraying atmosphere was found to strongly influence the interfacial contact between lamellae and coating thermal diffusivity.

  20. THE EFFECT OF LASER GLAZING PROCESS ON MICROSTRUCTURE OF PLASMA SPRAYED THERMAL BARRIER COATINGS

    Directory of Open Access Journals (Sweden)

    Seyid Fehmi DİLTEMİZ

    2011-12-01

    Full Text Available Thermal barrier coatings (TBCs are widely used by aero and land based gas turbines to protect hot section parts from oxidation and reducing component temperature thereby increase life. TBCs aregenerally a combination of multiple layers of coating (usually two with each layer having a specific function [Aktaa et al., 2005]. In this study air plasma sprayed TBCs were deposited on 304 stainlesssteel substrates then ceramic surfaces were glazed using Nd-YAG laser. Both glazed and as-coated samples were subjected to metallographic examination to investigate microstructural changes inglazed ceramic layer. Laser glazing provides a remelting and subsequent solidification of the surface, resulting on new top layer microstructure.

  1. Improved femoral component rotation in TKA using patient-specific instrumentation.

    Science.gov (United States)

    Heyse, Thomas J; Tibesku, Carsten O

    2014-01-01

    Patient-specific instrumentation (PSI) was introduced in an attempt to reduce positional outliers of components in total knee arthroplasty (TKA). It was hypothesized that PSI could help with the positioning of femoral components in optimal rotational alignment. A magnetic resonance imaging (MRI) analysis of 94 patients following TKA was conducted. Of these, 46 operations were performed using PSI and 48 using conventional instrumentation. The rotation of the femoral components was determined in the MRI and deviations>3° were considered outliers. Data were analyzed for positional outliers, observer reliability, and a variance comparison between implant groups. There was excellent inter- and intraobserver reliability with low standard deviations for the determination of femoral component rotation. There were significantly more outliers in the conventional (22.9%) group than in the PSI group (2.2%, p=0.003). In this setup, PSI was effective in significantly reducing outliers of optimal rotational femoral component alignment during TKA. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Characterization of plasma sprayed beryllium ITER first wall mockups

    Energy Technology Data Exchange (ETDEWEB)

    Castro, R.G.; Vaidya, R.U.; Hollis, K.J. [Los Alamos National Lab., NM (United States). Material Science and Technology Div.

    1998-01-01

    ITER first wall beryllium mockups, which were fabricated by vacuum plasma spraying the beryllium armor, have survived 3000 thermal fatigue cycles at 1 MW/m{sup 2} without damage during high heat flux testing at the Plasma Materials Test Facility at Sandia National Laboratory in New Mexico. The thermal and mechanical properties of the plasma sprayed beryllium armor have been characterized. Results are reported on the chemical composition of the beryllium armor in the as-deposited condition, the through thickness and normal to the through thickness thermal conductivity and thermal expansion, the four-point bend flexure strength and edge-notch fracture toughness of the beryllium armor, the bond strength between the beryllium armor and the underlying heat sink material, and ultrasonic C-scans of the Be/heat sink interface. (author)

  3. Nanostructured yttria stabilized zirconia coatings deposited by air plasma spraying

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hong; LI Fei; HE Bo; WANG Jun; SUN Bao-de

    2007-01-01

    Nanostructured yttria partially stabilized zirconia coatings were deposited by air plasma spraying with reconstituted nanosized powder. The microstructures and phase compositions of the powder and the as-sprayed nanostructured coatings were characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results demonstrate that the microstructure of as-sprayed nanostructured zirconia coating exhibits a unique tri-modal distribution including the initial nanostructure of the powder, equiaxed grains and columnar grains. Air plasma sprayed nanostructured zirconia coatings consist of only the nontransformable tetragonal phase, though the reconstituted nanostructured powder shows the presence of the monoclinic, the tetragonal and the cubic phases. The mean grain size of the coating is about 42 nm.

  4. Nanostructured Sulfide Composite Coating Prepared by Atmospheric Plasma Spraying

    Institute of Scientific and Technical Information of China (English)

    关耀辉

    2006-01-01

    Nanostructured FeS-SiC coating was deposited by atmospheric plasma spraying (APS). The microstructure and phase composition of the coating were characterized with SEM and XRD, respectively. In addition, the size distribution of the reconstituted powders and the porosity of the coating have been measured. It was found that the reconstitiuted powers with sizes in the range of 20 to 80 μm had excellent flowability and were suitable for plasma spraying process. The assprayed FeS-SiC composite coating exhibited a bimodal distribution with small grains (30~80nm) and large grains (100~200nm). The coating was mainly composed of FeS and SiC, a small quantity of Fe1-x S and oxide were also found. The porosity of the coating was approximately 19 %.

  5. Plasma-sprayed ceramic coatings for molten metal environments.

    Energy Technology Data Exchange (ETDEWEB)

    Hollis, K. J. (Kendall J.); Peters, M. I. (Maria I.); Bartram, B. D. (Brian D.)

    2002-01-01

    Coating porosity is an important parameter to optimize for plasma-sprayed ceramics which are intended for service in molten metal environments. Too much porosity and the coatings may be infiltrated by the molten metal causing corrosive attack of the substrate or destruction of the coating upon solidification of the metal. Too little porosity and the coating may fail due to its inability to absorb thermal strains. This study describes the testing and analysis of tungsten rods coated with aluminum oxide, yttria-stabilized zirconia, yttrium oxide, and erbium oxide deposited by atmospheric plasma spraying. The samples were immersed in molten aluminum and analyzed after immersion. One of the ceramic materials used, yttrium oxide, was heat treated at 1000 C and 2000 C and analyzed by X-ray diffractography and mercury intrusion porosimetry. Slight changes in crysl nl structure and significant changes in porosity were observed after heat treatments.

  6. Plasma spray forming of tungsten coatings on copper electrodes

    Institute of Scientific and Technical Information of China (English)

    JIANG Xian-liang(蒋显亮); F.Gitzhofer; M.I.Boulos

    2004-01-01

    Both direct current dc plasma and radio frequency induction plasma were used to deposit tungsten coatings on copper electrodes. Fine tungsten powder with mean particle size of 5μm and coarse tungsten powder with particle size in the range from 45 μm to 75 μm were used as plasma spray feedstock. It is found that dc plasma is only applicable to spray the fine tungsten powder and induction plasma can be used to spray both the coarse powder and the fine powder. The tungsten coating deposited by the induction plasma spraying of the coarse powder is extremely dense. Such a coating with an interlocking structure and an integral interface with the copper substrate demonstrates high cohesion strength and adhesion strength.

  7. Fluctuation Phenomenon Analysis of an Arc Plasma Spraying Jet

    Institute of Scientific and Technical Information of China (English)

    赵文华; 田阔; 刘笛; 张冠忠

    2001-01-01

    The effects of three factors, including the power supply, the arc behaviour in the arc channel and the fluid dynamic process of the jet, on a plasma spraying jet have been experimentally detected by means of spectroscopic diagnostic techniques. The fast Fourier transform method has been applied to the analysis of the arc voltage and spectral line intensity of the jet. The three factors have been studied and distinguished from each other.

  8. Corrosion behavior of magnetic ferrite coating prepared by plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi; Wei, Shicheng, E-mail: wsc33333@163.com; Tong, Hui; Tian, Haoliang; Liu, Ming; Xu, Binshi

    2014-12-15

    Graphical abstract: The saturation magnetization (M{sub s}) of the ferrite coating is 34.417 emu/g while the M{sub s} value of the ferrite powder is 71.916 emu/g. It can be seen that plasma spray process causes deterioration of the room temperature soft magnetic properties. - Highlights: • Spinel ferrite coatings have been prepared by plasma spraying. • The coating consists of nanocrystalline grains. • The saturation magnetization of the ferrite coating is 34.417 emu/g. • Corrosion behavior of the ferrite coating was examined in NaCl solution. - Abstract: In this study, spray dried spinel ferrite powders were deposited on the surface of mild steel substrate through plasma spraying. The structure and morphological studies on the ferrite coatings were carried out using X-ray diffraction, scanning electron microscope and Raman spectroscopy. It was showed that spray dried process was an effective method to prepare thermal spraying powders. The coating showed spinel structure with a second phase of LaFeO{sub 3}. The magnetic property of the ferrite samples were measured by vibrating sample magnetometer. The saturation magnetization (M{sub s}) of the ferrite coating was 34.417 emu/g. The corrosion behavior of coating samples was examined by electrochemical impedance spectroscopy. EIS diagrams showed three corrosion processes as the coating immersed in 3.5 wt.% NaCl solution. The results suggested that plasma spraying was a promising technology for the production of magnetic ferrite coatings.

  9. Influence of Different Interfacial Conditions on Bond Strength of Plasma - Sprayed Tungsten Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Song, S.X. [Research Center on Fusion Materials (RCFM), University of Science and Technology Beijing (USTB), 10008 3 Beijing (China); Zhou, Z.; Ge, C. [Lab. of Special Ceramic and P/M, University of Science and Technology, 100083 Beijing (China)

    2007-07-01

    Full text of publication follows: How to improve the interfacial performance and obtain high bond strength is a common problem in plasma-sprayed W coatings onto Cu substrates as plasma-facing components (PFC). This phenomenon results from the high interfacial residual stress state created by different thermal expansion coefficients, melting points and elastic modulus between W and Cu during the spraying processes. In this paper, tungsten coatings were deposited onto the oxygen free copper by plasma spraying. Various interlayers were designed to relieve the residual stress between W coatings and Cu substrates. These interlayers included NiCrAl, NiAl, NiCrAlY, W(50 %) Cu (50%) and functionally graded bonding coatings NiCrAl/AlCu, W/Cu and so on. SEM, EDS and XRD were employed to investigate the microstructure, photographs and compositions of the interfacial layers. Finite element coupled heat transfer and elastic-plastic thermal stress analysis using finite element analysis (FEA) were utilized to simulate the residual stress generation during the depositing process. The residual stresses were also calculated using this method to explain the variations of the interfacial characteristics with the various interlayers. In addition, tensile tests in conjunction with finite element analysis (FEA) were also performed to better understand the influence of both material selection and component distribution on bonding strength between the coatings and the substrates. As a result, a predicted coating system with the possibility of reducing the residual stress level was also proposed. (authors)

  10. Microstructure of Suspension Plasma Spray and Air Plasma Spray Al2O3-ZrO2 Composite Coatings

    Science.gov (United States)

    Chen, Dianying; Jordan, Eric H.; Gell, Maurice

    2009-09-01

    Al2O3-ZrO2 coatings were deposited by the suspension plasma spray (SPS) molecularly mixed amorphous powder and the conventional air plasma spray (APS) Al2O3-ZrO2 crystalline powder. The amorphous powder was produced by heat treatment of molecularly mixed chemical solution precursors below their crystallization temperatures. Phase composition and microstructure of the as-synthesized and heat-treated SPS and APS coatings were characterized by XRD and SEM. XRD analysis shows that the as-sprayed SPS coating is composed of α-Al2O3 and tetragonal ZrO2 phases, while the as-sprayed APS coating consists of tetragonal ZrO2, α-Al2O3, and γ-Al2O3 phases. Microstructure characterization revealed that the Al2O3 and ZrO2 phase distribution in SPS coatings is much more homogeneous than that of APS coatings.

  11. Do Rerevision Rates Differ After First-time Revision of Primary THA With a Cemented and Cementless Femoral Component?

    DEFF Research Database (Denmark)

    Gromov, Kirill; Pedersen, Alma B; Overgaard, Søren

    2015-01-01

    the results of future revision procedures; however, this has not been documented. The purpose of this study was to compare (1) the risk for rerevision of first revision THA; (2) the patterns of femoral bone loss at the time of first revision of primary THA; (3) the reasons for first revision of primary THA......; and (4) the time to first revision of primary THA between primary cementless and cemented femoral components. Primary THAs with cemented (n = 1791) and uncemented (n = 805) femoral components that subsequently sustained first revision of the femoral component were identified from the Danish Hip...... Arthroplasty Registry (DHR). As of 2012, 120,988 primary THAs and 19,282 revisions were registered in the DHR with completeness of 97% and 90% for primary and revision THA, respectively. Median followup for revisions of primary THA with cemented and cementless femoral component was 4 years (range, 0-17 years...

  12. Accuracy of methods to measure femoral head penetration within metal-backed acetabular components.

    Science.gov (United States)

    Callary, Stuart A; Solomon, Lucian B; Holubowycz, Oksana T; Campbell, David G; Howie, Donald W

    2016-06-30

    A number of different software programs are used to investigate the in vivo wear of polyethylene bearings in total hip arthroplasty. With wear rates below 0.1 mm/year now commonly being reported for highly cross-linked polyethylene (XLPE) components, it is important to identify the accuracy of the methods used to measure such small movements. The aims of this study were to compare the accuracy of current software programs used to measure two-dimensional (2D) femoral head penetration (FHP) and to determine whether the accuracy is influenced by larger femoral heads or by different methods of representing the acetabular component within radiostereometric analysis (RSA). A hip phantom was used to compare known movements of the femoral head within a metal-backed acetabular component to FHP measured radiographically using RSA, Hip Analysis Suite (HAS), PolyWare, Ein Bild Roentgen Analyse (EBRA), and Roentgen Monographic Analysis Tool (ROMAN). RSA was significantly more accurate than the HAS, PolyWare, and ROMAN methods when measuring 2D FHP with a 28 mm femoral head. Femoral head size influenced the accuracy of HAS and ROMAN 2D FHP measurements, EBRA proximal measurements, and RSA measurements in the proximal and anterior direction. The use of different acetabular reference segments did not influence accuracy of RSA measurements. The superior accuracy and reduced variability of RSA wear measurements allow much smaller cohorts to be used in RSA clinical wear studies than those utilizing other software programs. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

  13. The effect of thermal aging on the thermal conductivity of plasma sprayed and EB-PVD thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Dinwiddie, R.B.; Beecher, S.C.; Porter, W.D. [Oak Ridge National Lab., TN (United States); Nagaraj, B.A. [General Electric Co., Cincinnati, OH (United States). Aircraft Engine Group

    1996-05-01

    Thermal barrier coatings (TBCs) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBCs is of primary importance. Electron beam-physical vapor deposition (EV-PVD) and air plasma spraying (APS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The density of the APS coatings was controlled by varying the spray parameters. The low density APS yttria-partially stabilized zirconia (yttria-PSZ) coatings yielded a thermal conductivity that is lower than both the high density APS coatings and the EB-PVD coatings. The thermal aging of both fully and partially stabilized zirconia are compared. The thermal conductivity of the coatings permanently increases upon exposure to high temperatures. These increases are attributed to microstructural changes within the coatings. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the EB-PVD coatings are less susceptible to thermal aging effects, results suggest that they typically have a higher thermal conductivity than APS coatings before thermal aging. The increases in thermal conductivity due to thermal aging for plasma sprayed partially stabilized zirconia have been found to be less than for plasma sprayed fully stabilized zirconia coatings.

  14. Tailoring the heat transfer on the injection moulding cavity by plasma sprayed ceramic coatings

    Science.gov (United States)

    Bobzin, K.; Hopmann, Ch; Öte, M.; Knoch, M. A.; Alkhasli, I.; Dornebusch, H.; Schmitz, M.

    2017-03-01

    Inhomogeneous material shrinkage in injection moulding can cause warpage in thermoplastic components. To minimise the deformations of the injection moulding parts, the heat transfer during the cooling phase can be adjusted according to the local cooling demand on the surface of the mould cavity by means of plasma sprayed coatings with locally variable thermal resistance over the surface of the mould. Thermal resistance is a function of thermal conductivity and thickness of the coatings, where thermal conductivity of thermal barrier coatings can be adjusted by altering the chemical composition and the microstructure, which is depending on the thickness. This work evaluates the application of plasma sprayed coatings with variable thickness as thermal barrier coatings in the mould cavity. The thermal resistance of the coating and thereby the heat transfer from the melt into the mould will be influenced locally by varying the coating thickness over the cavity area according to the local cooling demand. Using the laser flash method, the thermal conduction of coatings with different thicknesses will be determined. On the basis of the experimentally determined thermal conduction, the effect of the coatings on the temperature field of the mould cavity will be numerically calculated and the required thickness distribution of the coating for an optimal temperature gradient will be determined.

  15. Thermal Conductivity Analysis and Lifetime Testing of Suspension Plasma-Sprayed Thermal Barrier Coatings

    Directory of Open Access Journals (Sweden)

    Nicholas Curry

    2014-08-01

    Full Text Available Suspension plasma spraying (SPS has become an interesting method for the production of thermal barrier coatings for gas turbine components. The development of the SPS process has led to structures with segmented vertical cracks or column-like structures that can imitate strain-tolerant air plasma spraying (APS or electron beam physical vapor deposition (EB-PVD coatings. Additionally, SPS coatings can have lower thermal conductivity than EB-PVD coatings, while also being easier to produce. The combination of similar or improved properties with a potential for lower production costs makes SPS of great interest to the gas turbine industry. This study compares a number of SPS thermal barrier coatings (TBCs with vertical cracks or column-like structures with the reference of segmented APS coatings. The primary focus has been on lifetime testing of these new coating systems. Samples were tested in thermo-cyclic fatigue at temperatures of 1100 °C for 1 h cycles. Additional testing was performed to assess thermal shock performance and erosion resistance. Thermal conductivity was also assessed for samples in their as-sprayed state, and the microstructures were investigated using SEM.

  16. Residual stress in plasma sprayed ceramic turbine tip and gas path seal specimens

    Science.gov (United States)

    Hendricks, R. C.; Mcdonald, G.; Mullen, R. L.

    1983-01-01

    The residual stresses in a ceramic sheet material used for turbine blade tip gas path seals, were estimated. These stresses result from the plasma spraying process which leaves the surface of the sheet in tension. To determine the properties of plasma sprayed ZrO2-Y2O3 sheet material, its load deflection characteristics were measured. Estimates of the mechanical properties for sheet materials were found to differ from those reported for plasma sprayed bulk materials.

  17. Reduced UHMWPE wear using magnesia-stabilized zirconia instead of CoCr femoral components in a knee simulator.

    Science.gov (United States)

    Roy, Marcel E; Whiteside, Leo A; Tilden, David S; Noel, Oscar F

    2015-03-01

    Magnesia-stabilized zirconia (Mg-PSZ) is stable and maintains a scratch-resistant surface in hip replacement, but is untested in knees. We assessed whether using Mg-PSZ instead of cobalt-chromium (CoCr) femoral components resulted in less tibial insert wear, and evaluated changes in topography and roughness of the femoral components. Inserts bearing against CoCr or Mg-PSZ were tested using standard (9 Mc) and aggressive (6 Mc) waveforms. Femoral component surface topography and roughness were evaluated before and after testing by optical profilometry. When bearing against Mg-PSZ, UHMWPE wear rate decreased by 73% (standard) and by 59% (aggressive conditions). After 15 Mc, CoCr components featured deep scratches, and roughness increased five-fold, while Mg-PSZ components were unchanged. Mg-PSZ femoral components may be indicated for high-demand patients and those with metal sensitivity.

  18. Pain syndrome in patient after hip replacement with a dual-modular femoral component (case report

    Directory of Open Access Journals (Sweden)

    R. M. Tikhilov

    2014-01-01

    Full Text Available Total hip replacements with dualmodular femoral components (stemneck interface allow optimization of hip joint biomechanics via selective restoration of femoral anteversion, offset, and limb length theoretically improving muscle function and stability. Potential disadvantages are the additional stemneck interface and the possible generation of metal ions and debris by fretting and crevice corrosion. The authors reported a case of patient with dualmodular stem presenting with pain and decreased function. Earlyonset adverse inflammatory tissue reactions developed as a result of corrosion at the stemneck interface of a dualmodular implant, requiring subsequent revision of wellfixed components with an extended trochanteric osteotomy. Additional examinations excluded infection. We consider that patients with a modular stem and neck junction and presenting with pain should be suspected on corrosion at the stemneck interface and adverse inflammatory tissue reaction after infection exclusion.

  19. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    Science.gov (United States)

    Cai, Yuxuan; Coyle, Thomas W.; Azimi, Gisele; Mostaghimi, Javad

    2016-04-01

    This work presents a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature, chemical inertness, high temperature stability, and good mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The effects of various spraying conditions including standoff distance, torch power, number of torch passes, types of solvent and plasma velocity were investigated. The as-sprayed coating demonstrated a hierarchically structured surface topography, which closely resembles superhydrophobic surfaces found in nature. The water contact angle on the SPPS superhydrophobic coating was up to 65% higher than on smooth REO surfaces.

  20. Monoclinic zirconia distributions in plasma-sprayed thermal barrier coatings

    Science.gov (United States)

    Lance, M. J.; Haynes, J. A.; Ferber, M. K.; Cannon, W. R.

    2000-03-01

    Phase composition in an air plasma-sprayed Y2O3-stabilized ZrO2 (YSZ) top coating of a thermal barrier coating (TBC) system was characterized. Both the bulk phase content and localized pockets of monoclinic zirconia were measured with Raman spectroscopy. The starting powder consisted of ˜15 vol.% monoclinic zirconia, which decreased to ˜2 vol.% in the as-sprayed coating. Monoclinic zirconia was concentrated in porous pockets that were evenly distributed throughout the TBC. The pockets resulted from the presence of unmelted granules in the starting powder. The potential effect of the distributed monoclinic pockets on TBC performance is discussed.

  1. Plasma sprayed Fe(76)Nd(16)B(8) permanent magnets

    Science.gov (United States)

    Overfelt, R. A.; Anderson, C. D.; Flanagan, W. F.

    1986-01-01

    Thin coatings (0.16 mm) and thick coatings (0.50 mm) of Fe(76)Nd(16)B(8) were deposited on stainless-steel substrates by low pressure plasma spraying. Microscopic examination of the coatings in a light microscope revealed excessive porosity, but good bonding to the substrate. Fracture cross sections examined in a scanning electron microscope showed the grains to be equiaxed and approximately 1 micron or less in diameter in the as-sprayed condition. The intrinsic coercivities of the as-sprayed coatings varied from 5.8 to 10.9 kOe. The effects of postspray heat treatments on the intrinsic coercivity are also given.

  2. Plasma spray forming of functionally graded materials mould

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zi-yu; FANG Jian-cheng; LI Hong-you

    2005-01-01

    A new technology of functionally graded materials(FGM) mould fabricated by plasma spraying and arc spraying was developed. According to applied characteristic of plastic mould, the reasonable coatings of FGM were designed and their microstructures were analyzed. At the same time, some key problems were solved including spray mould fabricating, FGM forming and demoulding, etc. The results show that the service performance of the FGM mould is much more excellent than the one composed of the traditional materials, and the life span can also be greatly increased. The technology will have a significant influence on materials development in mould industry.

  3. Suspension plasma sprayed composite coating using amorphous powder feedstock

    Science.gov (United States)

    Chen, Dianying; Jordan, Eric H.; Gell, Maurice

    2009-03-01

    Al 2O 3-ZrO 2 composite coatings were deposited by the suspension plasma spray process using molecularly mixed amorphous powders. X-ray diffraction (XRD) analysis shows that the as-sprayed coating is composed of α-Al 2O 3 and tetragonal ZrO 2 phases with grain sizes of 26 nm and 18 nm, respectively. The as-sprayed coating has 93% density with a hardness of 9.9 GPa. Heat treatment of the as-sprayed coating reveals that the Al 2O 3 and ZrO 2 phases are homogeneously distributed in the composite coating.

  4. Laser Remelting of Plasma Sprayed Thermal Barrier Coatings

    Institute of Scientific and Technical Information of China (English)

    Gang ZHANG; Yong LIANG; Yingna WU; Zhongchao FENG; Bingchun ZHANG; Fangjun LIU

    2001-01-01

    A CO2 continuous wave laser with defocused beam was used for remelting the surface of plasma sprayed ZrO2-8 wt pct Y2O3 (8YSZ)/Ni22Cr10AlY thermal barrier coatings (TBCs) on GH536 superalloy substrate. Two main laser processing parameters, power and travel speed, were adopted to produce a completely remelted layer, and their effects on remelted appearance,remelting depth, density and diameter of depression, space of segment crack and remelted microstructure were evaluated. With energy of 4.0 to 8.0 J.mm-2, an appropriate laser processing for applicable remelted layer was suggested.

  5. Comparison of W–TiC composite coatings fabricated by atmospheric plasma spraying and supersonic atmospheric plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Qing Yu, E-mail: qingyuhou@hotmail.com [School of Material Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Anhui Key Laboratory of Metal Materials and Processing, Maanshan, Anhui 243002 (China); Luo, Lai Ma [School of Material Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Huang, Zhen Yi; Wang, Ping; Ding, Ting Ting [Anhui Key Laboratory of Metal Materials and Processing, Maanshan, Anhui 243002 (China); Wu, Yu Cheng, E-mail: ycwu@hfut.edu.cn [School of Material Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China)

    2016-04-15

    Highlights: • W–TiC composite coatings were fabricated by APS and SAPS technologies. • TiC had filling effect on pores and coating/fixing effect on un-melted particles. • Porosity and oxygen content in SAPS coating were lower than that in APS coating. • Thermal conductivity of SAPS coating was higher than that of APS coating. • SAPS coating has better ability to resist to elastic fracture than APS coating does. - Abstract: Tungsten coatings with 1.5 wt.% TiC (W/TiC) were fabricated by atmospheric plasma spraying (APS) and supersonic atmospheric plasma spraying (SAPS) techniques, respectively. The results showed that the typical lamellar structure of plasma spraying and columnar crystalline grains formed in the coatings. Pores located mainly at lamellar gaps in association with oxidation were also observed. TiC phase, distributed at lamellar gaps filled the gaps; and that distributed around un-melted tungsten particles and splashed debris coated the particles or debris that were linked with the TiC at lamellar gaps. The coating and linking of the retained TiC phase prevented the tungsten particles to come off from the coatings. The porosity and the oxygen content of the SAPS-W/TiC were lower than those of the APS-W/TiC coating. The mechanical response of the coatings was strongly dependent on the H/E* ratio (H and E* are the hardness and effective Young’s modulus, respectively). The SAPS-W/TiC coating with a higher H/E* ratio had a better ability to resist to elastic fracture and better fracture toughness as compared with the APS-W/TiC coating with a smaller H/E* ratio. The thermal conductivity of the SAPS-W/TiC coating was greater than that of the APS-W/TiC coating.

  6. Development of plasma spray coating using coal ash

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, S.C.; Sarkar, P.C.; Mishra, P.C.; Sreekumar, K.P.; Padmanabhan, P.V.A. [Regional Engineering College, Rourkela (India)

    2000-07-01

    In India about 70 million tonnes of fly ash is generated annually and the figure is growing at a faster rate due to industrial and urban demand. Worldwide, fly ash is being used to generate value added products. In India about 10% of fly ash generated is utilised and if feverish activity is not initiated the percent utilisation can go down. The present piece of work has been undertaken to use the fly ash and graphite (from the rejected electrodes of arc furnaces) for developing plasma spray composite coating on metal substrates. Fly ash and graphite powder (at 10% and 20% wt) mix was plasma sprayed at various operating conditions of the plasma torch on different metal substrate, viz. copper and stainless steel. The coating thus formed was characterised by X-ray diffraction analysis, electron microscopy, microhardness measurement and measurement of interface adhesion strength. A maximum coating thickness of {approximately} 220 micron is obtained with fly ash +20% graphite. The adherence strength is found to vary between 10-35 MNm{sup 2} and is maximum in case of copper substrates. 8 refs., 4 figs., 1 tab.

  7. Plasma-Sprayed Titanium Patterns for Enhancing Early Cell Responses

    Science.gov (United States)

    Shi, Yunqi; Xie, Youtao; Pan, Houhua; Zheng, Xuebin; Huang, Liping; Ji, Fang; Li, Kai

    2016-06-01

    Titanium coating has been widely used as a biocompatible metal in biomedical applications. However, the early cell responses and long-term fixation of titanium implants are not satisfied. To obviate these defects, in this paper, micro-post arrays with various widths (150-1000 μm) and intervals (100-300 μm) were fabricated on the titanium substrate by template-assisted plasma spraying technology. In vitro cell culture experiments showed that MC3T3-E1 cells exhibited significantly higher osteogenic differentiation as well as slightly improved adhesion and proliferation on the micro-patterned coatings compared with the traditional one. The cell number on the pattern with 1000 µm width reached 130% after 6 days of incubation, and the expressions of osteopontin (OPN) as well as osteocalcin (OC) were doubled. No obvious difference was found in cell adhesion on various size patterns. The present micro-patterned coatings proposed a new modification method for the traditional plasma spraying technology to enhance the early cell responses and convenience for the bone in-growth.

  8. Anisotropic resistivity in plasma-sprayed silicon thick films

    Science.gov (United States)

    Kharas, Boris Dave; Sampath, Sanjay; Gambino, Richard J.

    2005-05-01

    Silicon thick films deposited by thermal plasma spray are of interest as inexpensive electronic materials for conformal meso-scale electronics applications. In addition they also serve as a model system for the investigation of electrical properties of coatings with layered anisotropy. In this study impedance spectroscopy was used to measure the complex resistivity of free-standing 64μm-thick polycrystalline silicon films deposited by thermal plasma spraying in an atmospheric ambient. Impedance spectroscopy measurements were taken in the through-thickness (across-splat) and edge-to-edge (in-splat) directions and revealed a resistivity difference of approximately 7.5±0.23 between the two directions. The complex resistivity results are explained on the basis of a brick-layer type model, associated with the layered splat microstructure obtained from cross-sectional transmission electron microscope imaging of the films. In addition a circuit-based model made up of parallel, resistor-capacitor elements in series, and Cole-Cole and Davidson-Cole impedance functions were used to fit the impedance data to extract material parameters and contributions from the grains and splat boundaries. Furthermore, thermal processing and phosphorus doping is shown to lead to higher and lower resistivity, respectively, in the films.

  9. Superior Thermal Barrier Coatings Using Solution Precursor Plasma Spray

    Science.gov (United States)

    Jordan, E. H.; Xie, L.; Gell, M.; Padture, N. P.; Cetegen, B.; Ozturk, A.; Ma, X.; Roth, J.; Xiao, T. D.; Bryant, P. E. C.

    2004-03-01

    A novel process, solution precursor plasma spray (SPPS), is presented for depositing thermal barrier coatings (TBCs), in which aqueous chemical precursors are injected into a standard direct current plasma spray system. The resulting coatings microstructure has three unique features: (1) ultra fine splats (1 µm), (2) nanometer and micron-sized interconnected porosity, and (3) closely spaced, through-thickness cracks. Coatings over 3 mm thick can be readily deposited using the SPPS process. Coating durability is excellent, with SPPS coatings showing, in furnace cycling tests, 2.5 times the spallation life of air plasma coatings (APS) and 1.5 times the life of electron beam physical vapor deposited (EB-PVD) coatings. The conductivity of SPPS coatings is lower than EB-PVD coatings and higher than the best APS coatings. Manufacturing cost is expected to be similar to APS coatings and much lower than EB-PVD coatings. The SPPS deposition process includes droplet break-up and material arriving at the deposition surface in various physical states ranging from aqueous solution, gel phase, to fully-molten ceramic. The relation between the arrival state of the material and the microstructure is described.

  10. The technology of Plasma Spray Physical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    M. Góral

    2012-12-01

    Full Text Available Purpose: The deposition of thermal barrier coatings is currently the most effective means of protecting the surface of aircraft engine turbine blades from the impact of aggressive environment of combustion gases. The new technologies of TBC depositions are required.Design/methodology/approach: The essential properties of the PS-PVD process have been outlined, as well as recent literature references. In addition, the influence of a set process condition on the properties of the deposited coatings has been described.Findings: The new plasma-spraying PS-PVD method is a promising technology for the deposition of modern thermal barrier coatings on aircraft engine turbine blades.Research limitations/implications: The constant progress of engine operating temperatures and increasing pollution restrictions determine the intensive development of heat-resistant coatings, which is directed to new deposition technologies and coating materials.Practical implications: The article presents a new technology of thermal barrier coating deposition - LPPS Thin Film and Plasma Spray - Physical Vapour Deposition.Originality/value: The completely new technologies was described in article.

  11. CMAS Interactions with Advanced Environmental Barrier Coatings Deposited via Plasma Spray- Physical Vapor Deposition

    Science.gov (United States)

    Harder, B. J.; Wiesner, V. L.; Zhu, D.; Johnson, N. S.

    2017-01-01

    Materials for advanced turbine engines are expected to have temperature capabilities in the range of 1370-1500C. At these temperatures the ingestion of sand and dust particulate can result in the formation of corrosive glass deposits referred to as CMAS. The presence of this glass can both thermomechanically and thermochemically significantly degrade protective coatings on metallic and ceramic components. Plasma Spray- Physical Vapor Deposition (PS-PVD) was used to deposit advanced environmental barrier coating (EBC) systems for investigation on their interaction with CMAS compositions. Coatings were exposed to CMAS and furnace tested in air from 1 to 50 hours at temperatures ranging from 1200-1500C. Coating composition and crystal structure were tracked with X-ray diffraction and microstructure with electron microscopy.

  12. Plasma-sprayed thermal barrier coatings: numerical study on damage localization and evolution

    Directory of Open Access Journals (Sweden)

    K. Slámečka

    2016-01-01

    Full Text Available Thermal barrier coatings (TBCs are advanced material systems used to enhance performance and in-service life of components operated at high temperatures in gas turbines and other power-generation devices. Because of complexity, numerical methods became important tools both for design of these coatings and for in-service life estimations and optimization. In this contribution, two main features that affect the TBCs’ performance, namely the roughness of the bond coat and the microstructure of the ceramic top coat, are discussed based on Finite Element Method (FEM and Finite Element Microstructure MEshfree (FEMME simulations that were used to calculate stresses and assess damage within the coating. Roughness data obtained from plasma-sprayed CoNiCrAlY + YSZ coated samples are supplemented to discuss assumptions and results of employed numerical models.

  13. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    Science.gov (United States)

    Cai, Yuxuan

    Superhydrophobic surfaces exhibit superior water repellent properties, and they have remarkable potential to improve current energy infrastructure. Substantial research has been performed on the production of superhydrophobic coatings. However, superhydrophobic coatings have not yet been adopted in many industries where potential applications exist due to the limited durability of the coating materials and the complex and costly fabrication processes. Here presented a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature and strong mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The as-sprayed coating demonstrated a hierarchically structured coating topography, which closely resembles superhydrophobic surfaces in nature. Compared to smooth REO surfaces, the SPPS superhydrophobic coating improved the water contact angle by as much as 65° after vacuum treatment at 1 Pa for 48 hours.

  14. Numerical Simulation of Basic Parameters in Plasma Spray

    Institute of Scientific and Technical Information of China (English)

    范群波; 王鲁; 王富耻

    2004-01-01

    On the basis of energy balance in the plasma gas, a new, simplified but effective mathematical model is developed to predict the temperature, velocity and ionization degrees of different species at the torch exit, which can be directly calculated just by inputting the general spraying parameters, such as current, voltage, flow rates of gases, etc. Based on this method, the effects of plasma current and the flow rate of Ar on the basic parameters at the torch exit are discussed. The results show that the temperature, velocity and ionization degrees of gas species will increase with increasing the plasma current; while increasing Ar flow rate can increase the velocity at the exit but decrease the temperature and ionization degrees of plasma species. The method would be helpful to predict the temperature and velocity fields in a plasma jet in future, and direct the practical plasma spray operations.

  15. Caracterisation of Titanium Nitride Layers Deposited by Reactive Plasma Spraying

    Science.gov (United States)

    Roşu, Radu Alexandru; Şerban, Viorel-Aurel; Bucur, Alexandra Ioana; Popescu, Mihaela; Uţu, Dragoş

    2011-01-01

    Forming and cutting tools are subjected to the intense wear solicitations. Usually, they are either subject to superficial heat treatments or are covered with various materials with high mechanical properties. In recent years, thermal spraying is used increasingly in engineering area because of the large range of materials that can be used for the coatings. Titanium nitride is a ceramic material with high hardness which is used to cover the cutting tools increasing their lifetime. The paper presents the results obtained after deposition of titanium nitride layers by reactive plasma spraying (RPS). As deposition material was used titanium powder and as substratum was used titanium alloy (Ti6Al4V). Macroscopic and microscopic (scanning electron microscopy) images of the deposited layers and the X ray diffraction of the coatings are presented. Demonstration program with layers deposited with thickness between 68,5 and 81,4 μm has been achieved and presented.

  16. Elastic behaviour of plasma sprayed thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Steinbrech, R.W.; Frahm, J.; Herzog, R.; Schubert, F. [Inst. for Materials and Processes in Energy Systems, Forschungszentrum Juelich GmbH, Juelich (Germany)

    2002-07-01

    The elastic behaviour of air plasma sprayed (APS) thermal barrier coatings (TBCs) of 8 wt.% yttria stabilised zirconia was studied using various mechanical tests with global and local resolution. Results are presented, which reveal the complex relationship between lamellar APS-microstructure and stiffness and illustrate scaling aspects. Also the influence of residual stresses is addressed. The obtained stiffness values for as-sprayed TBCs show a systematic variation between 10 and 100 GPa. Typically results from bending tests of free-standing TBCs are at the low end, whereas results from depth sensitive indentation tests with TBCs bonded to a substrate are found at the high end. When heat treated above 950 C the TBCs exhibit a rapid increase in stiffness which can be attributed to defect healing within the spraying lamellae. Discussion of the results focuses on the implications of a non-uniform stiffness modulus for the mechanical characterisation of thermal barrier systems. (orig.)

  17. Blanching resistant Cu-Cr coating by vacuum plasma spray

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, K.T. [Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.; Krotz, P.D. [Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.; Yuen, J.L. [Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.

    1995-11-01

    Copper alloy rocket engine combustion chamber linings have been found to deteriorate when exposed to cyclic reducing oxidizing (redox) environments, which are a consequence of the combustion process. The deterioration, known as blanching, can be characterized by increased roughness and burn-through sites in the wall of the combustion chamber lining and can seriously reduce the operational lifetime of the combustion chamber. A Cu-30 vol.%Cr coating produced by vacuum plasma spraying was effective in protecting the copper alloy substrate against blanching. The coating properties were characterized after cyclic oxidation exposure to 650 C in air followed by high pressure hydrogen charging. When exposed to an oxidizing environment at high temperatures, the coating formed a protective chromia scale that was substantially unreduced by high pressure hydrogen. (orig.)

  18. Suspension plasma sprayed composite coating using amorphous powder feedstock

    Energy Technology Data Exchange (ETDEWEB)

    Chen Dianying [Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, 97 N Eagleville Rd U-3136, Storrs, CT 06269 (United States)], E-mail: chendy@ims.uconn.edu; Jordan, Eric H. [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269 (United States); Gell, Maurice [Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, 97 N Eagleville Rd U-3136, Storrs, CT 06269 (United States)

    2009-03-15

    Al{sub 2}O{sub 3}-ZrO{sub 2} composite coatings were deposited by the suspension plasma spray process using molecularly mixed amorphous powders. X-ray diffraction (XRD) analysis shows that the as-sprayed coating is composed of {alpha}-Al{sub 2}O{sub 3} and tetragonal ZrO{sub 2} phases with grain sizes of 26 nm and 18 nm, respectively. The as-sprayed coating has 93% density with a hardness of 9.9 GPa. Heat treatment of the as-sprayed coating reveals that the Al{sub 2}O{sub 3} and ZrO{sub 2} phases are homogeneously distributed in the composite coating.

  19. Identification of Desirable Precursor Properties for Solution Precursor Plasma Spray

    Science.gov (United States)

    Muoto, Chigozie K.; Jordan, Eric H.; Gell, Maurice; Aindow, Mark

    2011-06-01

    In solution precursor plasma spray chemical precursor solutions are injected into a standard plasma torch and the final material is formed and deposited in a single step. This process has several attractive features, including the ability to rapidly explore new compositions and to form amorphous and metastable phases from molecularly mixed precursors. Challenges include: (a) moderate deposition rates due to the need to evaporate the precursor solvent, (b) dealing on a case by case basis with precursor characteristics that influence the spray process (viscosity, endothermic and exothermic reactions, the sequence of physical states through which the precursor passes before attaining the final state, etc.). Desirable precursor properties were identified by comparing an effective precursor for yttria-stabilized zirconia with four less effective candidate precursors for MgO:Y2O3. The critical parameters identified were a lack of major endothermic events during precursor decomposition and highly dense resultant particles.

  20. Plasma-sprayed ceramic coatings for protection against molten metal.

    Energy Technology Data Exchange (ETDEWEB)

    Hollis, K. J. (Kendall J.); Peters, M. I. (Maria I.); Bartram, B. D. (Brian D.)

    2002-01-01

    Molten metal environments pose a special demand on materials due to the high temperature corrosion effects and thermal expansion mismatch induced stress effects. A solution that has been successfully employed is the use of a base material for the mechanical strength and a coating material for the chemical compatibility with the molten metal. The work described here used such an approach coating tungsten rods with aluminum oxide, yttria-stabilized zirconia, yttrium oxide, and erbium oxide deposited by atmospheric plasma spraying. The ceramic materials were deposited under varying conditions to produce different structures. Measurement of particle characteristics was performed to correlate to material properties. The coatings were tested in a thermal cycling environment to simulate the metal melting cycle expected in service. Results of the testing indicate the effect of material composition and spray conditions on the thermal cycle crack resistance of the coatings.

  1. Sea water corrosion behavior of plasma sprayed abradable coatings

    Science.gov (United States)

    Parida, M.; Nanda, S. P.; Mishra, S. C.

    2017-02-01

    Aluminum based abradable coating is used for sealing purpose in compressor casing of aero engines to withstand up to a service temperature of 450°C. Al-BNSiO2 composite coating is deposited using thermal plasma spray technique. Coating thickness measured and porosity of the coating is evaluated.Coating morphology is observed and EDSanalysis is done with SEM (Jeol make). The effect of time on the sea water corrosion behavior of the coating is evaluated. It is observed that, there is a sharp increase in weight gain of the coating up to six weeks of immersion. This behavior is attributed to the adsorption/deposition of other elements/reactions taking place during interaction with sea water.

  2. Long-term implant-bone fixation of the femoral component in total knee replacement.

    Science.gov (United States)

    Cristofolini, L; Affatato, S; Erani, P; Leardini, W; Tigani, D; Viceconti, M

    2008-04-01

    Success of total knee replacement (TKR) depends on the prosthetic design. Aseptic loosening of the femoral component is a significant failure mode that has received little attention. Despite the clinical relevance of failures, no protocol is available to test long-term implant-bone fixation of TKR in vitro. The scope of this work was to develop and validate a protocol to assess pre-clinically the fixation of TKR femoral components. An in vitro protocol was designed to apply a simplified but relevant loading profile using a 6-degrees-of-freedom knee simulator for 1,000000 cycles. Implant-bone inducible micromotions and permanent migrations were measured at three locations throughout the test. After test completion, fatigue damage in the cement was quantified. The developed protocol was successfully applied to a commercial TKR. Additional tests were performed to exclude artefacts due to swelling or creep of the composite femur models. The components migrated distally; they tilted towards valgus in the frontal plane and in extension in the sagittal plane. The migration patterns were consistent with clinical roentgen-stereophotogrammetric recordings with TKR. Additional indicators were proposed that could quantify the tendency to loosen/stabilize. The type and amount of damage found in the cement, as well as the migration patterns, were consistent with clinical experience with the specific TKR investigated. The proposed pre-clinical test yielded repeatable results, which were consistent with the clinical literature. Therefore, its relevance and reliability was proved.

  3. Deposition of titanium nitride layers by electric arc - Reactive plasma spraying method

    Energy Technology Data Exchange (ETDEWEB)

    Serban, Viorel-Aurel [University ' Politehnica' of Timisoara, Faculty of Mechanical Engineering, No. 1 Mihai Viteazu Boulevard, 300222 Timisoara (Romania); Rosu, Radu Alexandru, E-mail: raduniz@gmail.com [University ' Politehnica' of Timisoara, Faculty of Mechanical Engineering, No. 1 Mihai Viteazu Boulevard, 300222 Timisoara (Romania); Bucur, Alexandra Ioana [National Institute for Research and Development in Electrochemistry and Condensed Matter Timisoara, Analysis and Characterization Department, No. 1 P Andronescu Street, Timisoara 300224 (Romania); Pascu, Doru Romulus [Romania National Research and Development Institute for Welding and Material Testing Timisoara, No. 30 Mihai Viteazu Boulevard, 300222 Timisoara (Romania)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Titanium nitride layers deposited by electric arc - reactive plasma spraying method. Black-Right-Pointing-Pointer Deposition of titanium nitride layers on C45 steel at different spraying distances. Black-Right-Pointing-Pointer Characterization of the coatings hardness as function of the spraying distances. Black-Right-Pointing-Pointer Determination of the corrosion behavior of titanium nitride layers obtained. - Abstract: Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments. The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments. X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti{sub 2}N) and small amounts of Ti{sub 3}O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

  4. Tissue response to the components of a hydroxyapatite-coated composite femoral implant.

    Science.gov (United States)

    Hacking, S A; Pauyo, T; Lim, L; Legoux, J G; Bureau, M N

    2010-09-01

    Bone loss around femoral implants used for THA is a persistent clinical concern. It may be caused by stress shielding, generally attributed to a mismatch in stiffness between the implants and host bone. In this regard, a fatigue resistant, carbon fiber (CF) composite femoral implant with bone-matching stiffness has been developed. This study evaluated the tissue response to the three material components of this implant in normal and textured (blasted with 24 grit alumina) surfaces: the hydroxyapatite (HA) coating, the CF composite and the intermediate crystalline HA particulate composite layer to bond to the HA coating (blended). Sprague-Dawley rats underwent bilateral femoral implantation each receiving two rod-like implants. Bone apposition to the HA (37%) and textured Ti (41%) implants was not significantly different. Bone apposition to the untextured CF (14%) and blended (19%) implants and polished Ti (8%) implants was significantly lower. Bone apposition to the textured CF (9%) and blended (11%) implants was lower (but not statistically from the as received or untextured counterparts). Nearly all sections from femurs containing CF implants presented CF debris. There was no evidence of localized bone loss or any strong immune response associated with any of the implant materials. All materials were well tolerated with minimal inflammation despite the presence of particulate debris. The high degree of bone apposition to the HA-coated composite implants and the lack of short-term inflammation and adverse tissue response to the three material implant component support continued evaluation of this composite technology for use in THA.

  5. Squatting-Related Tibiofemoral Shear Reaction Forces and a Biomechanical Rationale for Femoral Component Loosening

    Directory of Open Access Journals (Sweden)

    Ashvin Thambyah

    2014-01-01

    Full Text Available Previous gait studies on squatting have described a rapid reversal in the direction of the tibiofemoral joint shear reaction force when going into a full weight-bearing deep knee flexion squat. The effects of such a shear reversal have not been considered with regard to the loading demand on knee implants in patients whose activities of daily living require frequent squatting. In this paper, the shear reversal effect is discussed and simulated in a finite element knee implant-bone model, to evaluate the possible biomechanical significance of this effect on femoral component loosening of high flexion implants as reported in the literature. The analysis shows that one of the effects of the shear reversal was a switch between large compressive and large tensile principal strains, from knee extension to flexion, respectively, in the region of the anterior flange of the femoral component. Together with the known material limits of cement and bone, this large mismatch in strains as a function of knee position provides new insight into how and why knee implants may fail in patients who perform frequent squatting.

  6. The effect of femoral component rotation on the kinematics of the tibiofemoral and patellofemoral joints after total knee arthroplasty.

    Science.gov (United States)

    Merican, A M; Ghosh, K M; Iranpour, F; Deehan, D J; Amis, Andrew A

    2011-09-01

    Complications after total knee arthroplasty (TKA) often involve the patellofemoral joint, and problems with patellar maltracking or lateral instability have sometimes been addressed by external rotation of the femoral component. This work sought to measure the changes of knee kinematics caused by TKA and then to optimise the restoration of both the patellofemoral and tibiofemoral joint kinematics, by variation of femoral component internal-external rotation. The kinematics of the patella and tibia were measured in eight cadaveric knees during active extension motion. This was repeated with the knee intact, with a Genesis II TKA in the standard position (3° of external rotation) and with the femoral component at ±5° rotation from there. Both patellar and tibial motions were significantly different from normal with the standard TKA rotation, with 3° tibial abduction at 90° flexion and reversal of the screw-home from 5° external rotation to 6° internal rotation. The patella was shifted medially 6 mm in flexion and tilted 7° more laterally near extension. Femoral rotation to address one abnormality caused increased abnormality in other degrees of freedom. Internal and then external rotation of 5° caused tibial abduction and then adduction of 5° at 90° flexion. These femoral rotations also caused increased patellar lateral tilt of 4° with femoral external rotation and decreased tilt by 4° with internal rotation. Thus, correction of tibial abduction in flexion, by external rotation of the femoral component, worsened the patellar lateral tilt near extension. It was concluded that femoral rotation alone could not restore all aspects of both patellar and tibial kinematics to normal with this specific implant. The clinical relevance of this is that it appears to be inadvisable to reposition the femoral component, in an attempt to improve patellar tracking, if that repositioning may then cause abnormal tibiofemoral kinematics. Further, the pattern of patellar

  7. Residual stress in plasma-sprayed ceramic turbine tip and gas-path seal specimens

    Science.gov (United States)

    Hendricks, R. C.; Mcdonald, G.; Mullen, R. L.

    1983-01-01

    The residual stresses in a ceramic sheet material used for turbine blade tip gas path seals, were estimated. These stresses result from the plasma spraying process which leaves the surface of the sheet in tension. To determine the properties of plasma sprayed ZrO2-Y2O3 sheet material, its load deflection characteristics were measured. Estimates of the mechanical properties for sheet materials were found to differ from those reported for plasma sprayed bulk materials. Previously announced in STAR as N83-28380

  8. Mechanical, In Vitro Antimicrobial and Biological Properties of Plasma Sprayed Silver-Doped Hydroxyapatite Coating

    OpenAIRE

    Roy, Mangal; Fielding, Gary A.; BEYENAL, Haluk; Bandyopadhyay, Amit; Bose, Susmita

    2012-01-01

    Implant related infection is one of the key concerns in total joint hip arthroplasties. In order to reduce bacterial adhesion, silver (Ag) / silver oxide (Ag2O) doping was used in plasma sprayed hydroxyapatite (HA) coating on titanium substrate. HA powder was doped with 2.0, 4.0 and 6.0 wt% Ag, heat treated at 800 °C and used for plasma spray coating using a 30 kW plasma spray system, equipped with supersonic nozzle. Application of supersonic plasma nozzle significantly reduced phase decompos...

  9. Clinical Results of Oxidized Zirconium Femoral Component in TKA. A Review of Long-Term Survival: Review Article.

    Science.gov (United States)

    Civinini, Roberto; Matassi, Fabrizio; Carulli, Christian; Sirleo, Luigi; Lepri, Andrea Cozzi; Innocenti, Massimo

    2017-02-01

    Oxidized zirconium (OxZr) femoral component for total knee arthroplasty (TKA) have been introduced in an attempt to reduce polyethylene wear and secondary osteolysis and improve longevity of implants. We reviewed clinical studies in literature evaluating OxZr femoral component for TKA. The aim of this review was to evaluate the clinical outcome and survival rate of TKA with an OxZr femoral component. A review of the existing literature was undertaken to collect data on the OxZr femoral component in order to provide a better understanding of its performance. Of 34 studies published in the literature, 8 met the eligibility criteria and were included in the final analysis. Findings indicated that the mean Knee Society knee score improved in all series from preoperative to postoperative evaluation. The postoperative Knee Society knee score reported range from 84 to 95 and mean postoperative Knee Society functional score range from 74 to 90. The revision rate with this implant is low with up to 12.6 years of follow-up, with three revisions in total. The survival rate ranged from 100-98.7% at 5-7 years to 97.8% at 10 years. Excellent clinical outcome and high survival rate has been demonstrated for OxZr femoral component in TKA. No adverse reaction has been described for this new material.

  10. Combined use of extensively porous coated femoral components with onlay cortical strut allografts in revision of Vancouver B2 and B3 periprosthetic femoral fractures

    Institute of Scientific and Technical Information of China (English)

    WU Hao-bo; YAN Shi-gui; WU Li-dong; HE Rong-xin; WANG Xiang-hua; DAI Xue-song

    2009-01-01

    Background Periprosthetic femoral fractures following total hip arthroplasty are getting more prevalent.The aim of this study was to evaluate the clinical results of combined use of uncemented extensively porous coated femoral components with onlay cortical strut allografts in revision of Vancouver type B2 and B3 periprosthetic femoral fractures.Methods Thirteen hips after total hip arthroplasty in 13 patients who suffered a Vancouver B2 or B3 periprosthetic fracture were treated with an uncemented extensively porous coated femoral component combined with onlay cortical strut allografts.Each patient was assigned a Harris hip score,and a visual analog scale(VAS)score for pain and satisfaction.Radiographs were examined for component stability,fracture site and allograft-host union and allograft reconstruction.Results At an average of 5.3-year follow-up,no patient required repeat revision.The average Harris hip score was(71.8±6.3)points,the pain VAS score was(16.6±4.3)points,and the patient satisfaction VAS score was(81.5±5.7)points.Radiographic examination showed no detectable loosening of the prostheses,and 12 cases were presented fixation by osseointegration and the other one was stable fibrous ingrown fixation.All fractures united for(5.2±1.4)months in average.And all onlay strut allografts united to host bone for about(11.5±2.6)months.Conclusions Combined use of uncemented,long stemmed,extensively porous coated implant with cortical onlay strut allografts can achieve good clinic results and high rate of union for both fracture site and allograft-host bone junction.This technique could be used routinely to augment fixation and healing of Vancouver B2 and B3 periprosthetic fractures.

  11. Clinical and radiographic evaluation of long-stem femoral components following revision total hip arthroplasty.

    Science.gov (United States)

    Meding, J B; Ritter, M A; Keating, E M; Faris, P M

    1994-08-01

    Fifty-four consecutive, long-stem revision hip arthroplasties were performed in 53 patients. In order to evaluate periprosthetic femoral changes, all cases utilizing cement, requiring bone-grafts for prosthetic stability, or with a follow-up period of less than 2 years were omitted. Thus, 32 long-stem revision hip arthroplasties in 32 patients were reviewed. Twenty-three Porous Coated Anatomic (Howmedica, Rutherford, NJ) and nine Bi-Metric (Biomet, Warsaw, IN) stems were implanted, with an average follow-up period of 3.6 years (range, 2-6 years). Prosthetic canal fill averaged 94% proximally and 80% distally. Intraoperative complications included three femoral shaft fractures. Harris hip scores averaged 47.8 points, before surgery and 87.6 points at the final follow-up evaluation, with 81% of patients the pain-free. Only three cases of subsidence and one case of osteolysis were noted. By 1 year, proximal osteopenia (off-load) (P = .005), bony condensation about the porous surface (spot weld) (P = .01), and pedestal formation (P = .004) were observed. The presence of distal cortical hypertrophy, (P = .02) spot weld (P = .001), and pedestal formation (P = .05) correlated significantly with off-load. Pedestal formation and distal cortical hypertrophy were commonly found together (P = .001). Despite significant periprosthetic remodeling, adequate fixation and satisfactory early clinical scores were achieved in this setting. Contrary to similar reviews using extensive bone-grafts, acceptable pain-free clinical results were obtained with these components.

  12. Effect of femoral component design on patellofemoral crepitance and patella clunk syndrome after posterior-stabilized total knee arthroplasty.

    Science.gov (United States)

    Frye, Benjamin M; Floyd, Mark W; Pham, Dahn C; Feldman, John J; Hamlin, Brian R

    2012-06-01

    The purpose of this study was to determine if recent changes to the femoral component of a particular posterior-stabilized total knee prosthesis would affect the incidence of postoperative patellofemoral crepitance and patella clunk syndrome. One hundred eight total knee arthroplasties were performed with the conventional design; 136 were performed after the femoral component was changed. Complications were compared between the groups with an average follow-up of 17.7 months and 12.4 months, respectively. Thirteen knees with the conventional design (12%) were found to have patellofemoral complications; no complications were noted with the new design (P < .0001). Femoral components with a deep trochlear groove and smooth transition of the intercondylar box appear to better accommodate any peripatellar fibrous nodule that may form after total knee arthroplasty.

  13. Plasma sprayed rutile titania-nanosilver antibacterial coatings

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jinjin [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhao, Chengjian [National Key Laboratory of Human Factors Engineering, Department of ECLSS, China Astronaut Researching and Training Center, Beijing, 100094 (China); Zhou, Jingfang [Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, SA, 5095 (Australia); Li, Chunxia [National Key Laboratory of Human Factors Engineering, Department of ECLSS, China Astronaut Researching and Training Center, Beijing, 100094 (China); Shao, Yiran; Shi, Chao [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhu, Yingchun, E-mail: yzhu@mail.sic.ac.cn [Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2015-11-15

    Graphical abstract: - Highlights: • TiO{sub 2}/Ag feedstock powders containing 1–10,000 ppm silver nanoparticles were double sintered and deposited by plasma spray. • TiO{sub 2}/Ag coatings were composed of pure rutile phase and homogeneously-distributed metallic silver. • TiO{sub 2}/Ag coatings with more than 10 ppm silver nanoparticles exhibited strong antibacterial activity against E. coli and S. aureus. - Abstract: Rutile titania (TiO{sub 2}) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO{sub 2} coatings. In the study, titania-nanosilver (TiO{sub 2}/Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO{sub 2} powders containing 1–10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO{sub 2}/Ag powders and coatings. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO{sub 2}/Ag coatings and no crystalline changed happened in the TiO{sub 2} structure. The reduction ratios on the TiO{sub 2}/Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus, respectively, and the TiO{sub 2}/Ag coatings with 100–1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO{sub 2}/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the

  14. [Effect of rotation of the femoral and tibial components on patellofemoral malalignment in knee arthroplasty].

    Science.gov (United States)

    Kienapfel, H; Springorum, H-P; Ziegler, A; Klose, K-J; Georg, C; Griss, P

    2003-04-01

    Patellofemoral complications are among the most common causes for revision surgery in total knee arthroplasty. So far no quantitative assessment has been made of the femoral and tibial malalignment or the positioning of the patellar component and the type of patellofemoral complication or failure. In particular, no comparative studies are available that include patients with and without patellofemoral failure in respect to the above-mentioned parameters when implant material, implant design, and fixation technique were identical. Between 1985 and 1992, 171 MG I total knee arthroplasties were performed. Since 1999, 20% of all the implanted MG I knee arthroplasties (all with metal-backed patellar component) had to be revised. Of those 34 patients, 18 were pair matched with 18 control patients based on the criteria of sex, body mass index, and age. The only difference in the control group was that they did not suffer any malfunction of the patellofemoral mechanism. To assess the patella component localization, conventional AP radiographs, patellar merchant view radiographs in 30 degrees, and CT scans were performed. This study has demonstrated a significant difference for the thickness of the patellar component and a trend regarding the rotational malalignment of the tibial component. Potential causes for the malrotation and guidelines to prevent rotational malalignment are discussed.

  15. Bonelike apatite coatings on plasma-sprayed porous titanium by biomimetic processing

    Institute of Scientific and Technical Information of China (English)

    SHI Jian-min; DING Chuan-xian

    2001-01-01

    @@ INTRODUCTION Hydroxyapatite (HA) has many biological benefits, such as direct bonding to bone and enhances new bone formation around it. It has been demonstrated that dental and orthopaedic implants coated with HA show superior histological results to the uncoated ones. Various methods as well as plasma spraying, which is commonly used, have been developed to coat HA on metals. However, Plasma-sprayed HA coatings are limited by specific drawbacks such as low crystallinity, weak bond strength to the substrate.

  16. Residual stresses determination in textured substrates for plasma sprayed coatings

    Science.gov (United States)

    Capek, J.; Pala, Z.; Kovarik, O.

    2015-04-01

    In this contribution, we have striven to respond to the desire of obtaining the residual stress tensor in the both cold-rolled and hot-rolled substrates designated for deposition of thermal coatings by plasma spraying. Residual stresses play an important role in the coating adhesion to the substrate and, as such, it is a good practice to analyse them. Prior to spraying, the substrate is often being grit blasted. Residual stresses and texture were quantitatively assessed in both virgin and grit blasted sample employing three attitudes. Firstly without taking preferred orientation into account, secondly from measurements of interplanar lattice spacings of planes with high Miller indices using MoKα radiation. And eventually, by calculating anisotropic elastic constants as a weighted average between single-crystal and X-ray elastic constants with weighting being done according to the amount of textured and isotropic material in the irradiated volume. In the ensuing verification analyses, it was established that the latter approach is suitable for materials with either very strong or very weak presence of texture.

  17. Monitoring and Improving the Reliability of Plasma Spray Processes

    Science.gov (United States)

    Mauer, Georg; Rauwald, Karl-Heinz; Mücke, Robert; Vaßen, Robert

    2017-06-01

    Monitoring and improving of process reliability are prevalent issues in thermal spray technology. They are intended to accomplish specific quality characteristics by controlling the process. For this, implicit approaches are in demand to rapidly conclude on relevant coating properties, i.e., they are not directly measured, but it is assumed that the monitored variables are in fact suggestive for them. Such monitoring can be performed in situ (during the running process) instead of measuring coating characteristics explicitly (directly) and ex situ (after the process). Implicit approaches can be based on extrinsic variables (set from outside) as well as on intrinsic parameters (internal, not directly adjustable) having specific advantages and disadvantages, each. In this work, the effects of atmospheric plasma spray process variables are systemized in process schemes. On this basis, different approaches to contribute to improved process reliability are described and assessed paying particular attention to in-flight particle diagnostics. Finally, a new test applying spray bead analysis is introduced and first results are presented.

  18. Young's Moduli of Cold and Vacuum Plasma Sprayed Metallic Coatings

    Science.gov (United States)

    Raj, S. V.; Pawlik, R.; Loewenthal, W.

    2009-01-01

    Monolithic metallic copper alloy and NiCrAlY coatings were fabricated by either the cold spray (CS) or the vacuum plasma spray (VPS) deposition processes. Dynamic elastic modulus property measurements were conducted on these monolithic coating specimens between 300 K and 1273 K using the impulse excitation technique. The Young's moduli decreased almost linearly with increasing temperature at all temperatures except in the case of the CS Cu-23%Cr-5%Al and VPS NiCrAlY, where deviations from linearity were observed above a critical temperature. It was observed that the Young's moduli for VPS Cu-8%Cr were larger than literature data compiled for Cu. The addition of 1%Al to Cu- 8%Cr significantly increased its Young's modulus by 12 to 17% presumably due to a solid solution effect. Comparisons of the Young s moduli data between two different measurements on the same CS Cu- 23%Cr-5%Al specimen revealed that the values measured in the first run were about 10% higher than those in the second run. It is suggested that this observation is due to annealing of the initial cold work microstructure resulting form the cold spray deposition process.

  19. Recent developments in plasma spray processes for applications in energy technology

    Science.gov (United States)

    Mauer, G.; Jarligo, M. O.; Marcano, D.; Rezanka, S.; Zhou, D.; Vaßen, R.

    2017-03-01

    This work focuses on recent developments of plasma spray processes with respect to specific demands in energy technology. High Velocity Atmospheric Plasma Spraying (HV-APS) is a novel variant of plasma spraying devoted to materials which are prone to oxidation or decomposition. It is shown how this process can be used for metallic bondcoats in thermal barrier coating systems. Furthermore, Suspension Plasma Spraying (SPS) is a new method to process submicron-sized feedstock powders which are not sufficiently flowable to feed them in dry state. SPS is presently promoted by the development of novel torch concepts with axial feedstock injection. An example for a columnar structured double layer thermal barrier coating is given. Finally, Plasma Spray-Physical Vapor Deposition (PS-PVD) is a novel technology operating in controlled atmosphere at low pressure and high plasma power. At such condition, vaporization even of high-melting oxide ceramics is possible enabling the formation of columnar structured, strain tolerant coatings with low thermal conductivity. Applying different conditions, the deposition is still dominated by liquid splats. Such process is termed Low Pressure Plasma Spraying-Thin Film (LPPS-TF). Two examples of applications are gas-tight and highly ionic and electronic conductive electrolyte and membrane layers which were deposited on porous metallic substrates.

  20. Multicriteria Decision Analysis in Improving Quality of Design in Femoral Component of Knee Prostheses: Influence of Interface Geometry and Material

    Directory of Open Access Journals (Sweden)

    Ali Jahan

    2015-01-01

    Full Text Available Knee prostheses as medical products require careful application of quality and design tool to ensure the best performance. Therefore, quality function deployment (QFD was proposed as a quality tool to systematically integrate consumer’s expectation to perceived needs by medical and design team and to explicitly address the translation of customer needs into engineering characteristics. In this study, full factorial design of experiment (DOE method was accompanied by finite element analysis (FEA to evaluate the effect of inner contours of femoral component on mechanical stability of the implant and biomechanical stresses within the implant components and adjacent bone areas with preservation of the outer contours for standard Co-Cr alloy and a promising functionally graded material (FGM. The ANOVA revealed that the inner shape of femoral component influenced the performance measures in which the angle between the distal and anterior cuts and the angle between the distal and posterior cuts were greatly influential. In the final ranking of alternatives, using multicriteria decision analysis (MCDA, the designs with FGM was ranked first over the Co-Cr femoral component, but the original design with Co-Cr material was not the best choice femoral component, among the top ranked design with the same material.

  1. Orientation and depth estimation for femoral components using image sensor, magnetometer and inertial sensors in THR surgeries.

    Science.gov (United States)

    Jiyang Gao; Shaojie Su; Hong Chen; Zhihua Wang

    2015-08-01

    Malposition of the acetabular and femoral component has long been recognized as an important cause of dislocation after total hip replacement (THR) surgeries. In order to help surgeons improve the positioning accuracy of the components, a visual-aided system for THR surgeries that could estimate orientation and depth of femoral component is proposed. The sensors are fixed inside the femoral prosthesis trial and checkerboard patterns are printed on the internal surface of the acetabular prosthesis trial. An extended Kalman filter is designed to fuse the data from inertial sensors and the magnetometer orientation estimation. A novel image processing algorithm for depth estimation is developed. The algorithms have been evaluated under the simulation with rotation quaternion and translation vector and the experimental results shows that the root mean square error (RMSE) of the orientation estimation is less then 0.05 degree and the RMSE for depth estimation is 1mm. Finally, the femoral head is displayed in 3D graphics in real time to help surgeons with the component positioning.

  2. Alignment of the femoral component in a mobile-bearing unicompartmental knee arthroplasty : A study in 10 cadaver femora

    NARCIS (Netherlands)

    Kort, N. P.; van Raay, J. J. A. M.; Thomassen, B. J. W.

    2007-01-01

    Use of an intramedullary rod is advised for the alignment of the femoral component of an Oxford phase-III prosthesis. There are users moving toward extramedullary alignment, which is merely an indicator of frustration with accuracy of intramedullary alignment. The results of our study with 10 cadave

  3. Effect of Sulfur Acid Corrosion on the Luminescent Intensity of Plasma-Sprayed YAG:Ce Coatings

    Science.gov (United States)

    Wang, Weize; Zeng, Peng; Wang, Hehui; Yu, Jingye; Wu, Liangmin

    2016-12-01

    In order to monitor the corrosion condition of components, plasma-sprayed YAG:Ce coating was prepared for the detection, which could develop the application of plasma spraying. The effect of sulfuric acid corrosion on the microstructure, phase composition and luminescence intensity of coatings was studied. The powder was synthesized by the high-temperature solid-state method. Microstructure and phases were characterized through using SEM and XRD, respectively. Effect of immersion time in the acid was studied on the luminescence intensity. It was found that the phase composition of the powder was dominated by YAG (Y3Al5O12). More pores could be observed in coatings with the increase in immersion time. Sprayed coatings mainly included phases of YAG and YAP (YAlO3). The position of the XRD peaks of coatings was changing during the immersion. The luminescence intensity showed the fluctuation tendency with the immersion time, which related to the coating porosity, phase composition and the migration of the diffract peak.

  4. Improved femoral component rotation in advanced genu valgum deformity using computer-assisted measured resection total knee arthroplasty.

    Science.gov (United States)

    Lin, Shih-Jie; Lee, Chien-Ying; Huang, Kuo-Chin; Peng, Kuo-Ti; Huang, Tsan-Wen; Lee, Mel S; Hsu, Robert Wen-Wei; Shen, Wun-Jer

    2015-09-02

    Accurate femoral rotational alignment is of vital importance for successful total knee arthroplasty (TKA). The value of computer-assisted surgery TKA (CAS-TKA) in increasing the accuracy of femoral rotational alignment remains controversial. We hypothesize that outcomes are related to the severity of preoperative varus and valgus deformity and that CAS-TKA may be beneficial under certain circumstances. Between January 2007 and December 2013, patients with osteoarthritis and varus angulation in the mechanical axis (MA) ≥ 15° and valgus angulation in the MA ≥ 10° (based on hip-to-ankle standing radiography) who underwent TKA were divided into four groups. CAS-TKA and conventional TKA outcomes were compared in patients who had preoperative advanced genu varum and advanced genu valgum deformities. The accuracy of component alignment and postoperative limb alignment was determined using radiographic parameters and computed tomography (CT). One hundred and eight patients (144 knees) were included in the analysis. For patients with preoperative advanced genu varum deformity, a significant difference was detected in the sagittal femoral angle (p genu valgum deformity, a significant difference was found in the sagittal femoral angle (p = 0.034). The femoral rotational angle was significantly closer to the proper position in the CAS-TKA group (p genu valgum deformity (p = 0.011). Our data demonstrate that CAS-TKA is beneficial in obtaining proper femoral rotational alignment in patients with advanced genu valgum deformity (preoperative MA ≥ 10° valgus). In patients with advanced genu varum deformity (preoperative MA ≥ 15° varus), CAS-TKA did not improve the femoral rotational alignment.

  5. Plasma sprayed rutile titania-nanosilver antibacterial coatings

    Science.gov (United States)

    Gao, Jinjin; Zhao, Chengjian; Zhou, Jingfang; Li, Chunxia; Shao, Yiran; Shi, Chao; Zhu, Yingchun

    2015-11-01

    Rutile titania (TiO2) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO2 coatings. In the study, titania-nanosilver (TiO2/Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO2 powders containing 1-10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO2/Ag powders and coatings. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO2/Ag coatings and no crystalline changed happened in the TiO2 structure. The reduction ratios on the TiO2/Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus, respectively, and the TiO2/Ag coatings with 100-1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO2/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the antibacterial properties of TiO2/Ag coatings were discussed with grain size and the content of silver as well as the microstructure of the coatings.

  6. PLASMA SPRAYED Ni-Al COATINGS FOR SAFE ENDING HEAT EXCHANGER TUBES

    Energy Technology Data Exchange (ETDEWEB)

    ALLAN,M.L.; OTTERSON,D.; BERNDT,C.C.

    1998-11-01

    Brookhaven National Laboratory (BNL) has developed thermally conductive composite liners for corrosion and scale protection in heat exchanger tubes exposed to geothermal brine. The liners cannot withstand roller expansion to connect the tubes to the tubesheet. It is not possible to line the ends of the tubes with the same material after roller expansion due to the nature of the current liner application process. It was requested that BNL evaluate plasma sprayed Ni-Al coatings for safe ending heat exchanger tubes exposed to geothermal brine. The tubes of interest had an internal diameter of 0.875 inches. It is not typical to thermal spray small diameter components or use such small standoff distances. In this project a nozzle extension was developed by Zatorski Coating Company to spray the tube ends as well as flat coupons for testing. Four different Ni-Al coatings were investigated. One of these was a ductilized Ni-AIB material developed at Oak Ridge National Laboratory. The coatings were examined by optical and scanning electron microscopy. In addition, the coatings were analyzed by X-ray diffraction and subjected to corrosion, tensile adhesion, microhardness and field tests in a volcanic pool in New Zealand. It was determined that the Ni-Al coatings could be applied to a depth of two inches on the tube ends. When sprayed on flat coupons the coatings exhibited relatively high adhesion strength and microhardness. Polarization curves showed that the coating performance was variable. Measured corrosion potentials indicated that the Ni-Al coatings are active towards steel coated with thermally conductive polymers, thereby suggesting preferential corrosion. Corrosion also occurred on the coated coupons tested in the volcanic pool. This may have been exacerbated by the difficulty in applying a uniform coating to the coupon edges. The Ni-Al coatings applied to the tubes had significant porosity and did not provide adequate corrosion protection. This is associated with

  7. Evaluation of anterior knee pain in a PS total knee arthroplasty: the role of patella-friendly femoral component and patellar size.

    Science.gov (United States)

    Atzori, F; Sabatini, L; Deledda, D; Schirò, M; Lo Baido, R; Baido, R L; Massè, A

    2015-04-01

    Total knee arthroplasty gives excellent objective results. Nevertheless, the subjective findings do not match the normal knee perception: Often, it depends on patellar pain onset. In this study, we analyzed clinical and radiological items that can affect resurfaced patellar tracking, and role of a patella-friendly femoral component and patellar size on patellar pain onset. Thirty consecutive patients were implanted using the same-cemented posterior-stabilized TKA associated with patella resurfacing. Fifteen patients were implanted using a classical femoral component, while another 15 patients were implanted using a patella-friendly femoral component. The statistical analysis was set to detect a significant difference (p patella-friendly femoral model) reached a higher percentage of 100 points in the clinical and functional KSS, but there was no statistical difference. Also, no statistical differences for Burnett Questionnaire results were recorded. We had one case of patellar clunk syndrome in the standard femoral component group and one poor result in the second group. Postoperative radiographic measurements evidenced no statistical differences in both groups. In group 1 (classical femoral component), better significant result (p patella-friendly" femoral components. With the particular type of implant design utilized in this study, when the classical femoral component is used, bigger patellar implant sizes (38 and 41 mm) showed superior clinical outcome.

  8. Deposition of titanium nitride layers by electric arc - Reactive plasma spraying method

    Science.gov (United States)

    Şerban, Viorel-Aurel; Roşu, Radu Alexandru; Bucur, Alexandra Ioana; Pascu, Doru Romulus

    2013-01-01

    Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments. The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments. X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti2N) and small amounts of Ti3O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

  9. Plasma Sprayed Ni-Al Coatings for Safe Ending Heat Exchanger Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Allen, M.L.; Berndt, C.C.; Otterson, D.

    1998-11-01

    Brookhaven National Laboratory (BNL) has developed thermally conductive composite liners for corrosion and scale protection in heat exchanger tubes exposed to geothermal brine. The liners cannot withstand roller expansion to connect the tubes to the tubesheet. It is not possible to line the ends of the tubes with the same material after roller expansion due to the nature of the current liner application process. It was requested that BNL evaluate plasma sprayed Ni-Al coatings for safe ending heat exchanger tubes exposed to geothermal brine. The tubes of interest had an internal diameter of 0.875 inches. It is not typical to thermal spray small diameter components or use such small standoff distances. In this project a nozzle extension was developed by Zatorski Coating Company to spray the tube ends as well as flat coupons for testing. Four different Ni-Al coatings were investigated. One of these was a ductilized Ni-AlB material developed at Oak Ridge National Laboratory. The coatings were examined by optical and scanning electron microscopy. In addition, the coatings were analyzed by X-ray diffraction and subjected to corrosion, tensile adhesion, microhardness and field tests in a volcanic pool in New Zealand.

  10. Experimental investigation on erosive wear behaviour of plasma spray coated stainless steel

    Science.gov (United States)

    Girisha, K. G.; Sreenivas Rao, K. V.; Anil, K. C.; Sanman, S.

    2017-04-01

    Slurry erosion is an implicit problem in many engineering industrial components such as ore carrying pipelines, slurry pumps and extruders. Even the water turbine blades are subjected to erosive wear when the water contains considerable amount of silt. In the present study, Al2O3-40%TiO2 powder particles of average particle size of 50 micrometer were deposited on EN56B martenistic stainless steel by atmospheric plasma spray technique. Ni/Cr was pre coated to work as bond coat for good adhesion between coating and the substrate material. A coating thickness of 200 micrometer was achieved. Coated and un-coated substrates were subjected to slurry erosion test as per ASTM G-119 standard. Slurry erosion test rig was used to evaluate the erosion properties at room temperature condition by varying the spindle speed. Scanning electron microphotographs were taken before and after the slurry erosion test. Microstructures reveal uniform distribution of coating materials. Eroded surface shows lip, groove, and crater formation and dense coating resulting in less porosity. Micro hardness test was evaluated and reported. EDX analysis confirms the presence of Al, Ti and O2 particles. It was observed that, Al2O3-40%TiO2 coated substrates exhibit superior erosion resistance as compared to un-coated substrates due to higher hardness and less coating porosity.

  11. Process-Property Relationship for Air Plasma-Sprayed Gadolinium Zirconate Coatings

    Science.gov (United States)

    Dwivedi, Gopal; Tan, Yang; Viswanathan, Vaishak; Sampath, Sanjay

    2015-02-01

    The continuous need of elevating operating temperature of gas turbine engines has introduced several challenges with the current state-of-the-art yttria-stabilized zirconia (YSZ)-based thermal barrier coatings (TBCs), requiring examination of new TBC material with high temperature phase stability, lower thermal conductivity, and resistance to environmental ash particles. Gadolinium zirconate (Gd2Zr2O7) (GDZ) has been shown to meet many of these requirements, and has, in fact, been successfully implemented in to engine components. However, several fundamental issues related to the process-ability, toughness, and microstructural differences for GDZ when compared to equivalent YSZ coating. This study seeks to critically address the process-structure-property correlations for plasma-sprayed GDZ coating subjected to controlled parametric exploration. Use of in-flight diagnostics coupled with in situ and ex situ coating property monitoring allows examination and comparison of the process-property interplay and the resultant differences between the two TBC compositions. The results indicate that it is feasible to retain material chemistry and fabricate relevant microstructures of interest with GDZ with concomitant performance advantages such as low conductivity, mechanical compliance, sintering resistance, and suppression of environmentally induced damage from ash particles. This study provides a framework for optimal design and manufacturing of emergent multi-layer and multi-material TBCs.

  12. Effect of substrate preheating temperature and coating thickness on residual stress in plasma sprayed hydroxyapatite coating

    Science.gov (United States)

    Tang, Dapei

    2015-07-01

    A thermal-mechanical coupling model was developed based on thermal-elastic- plastic theory according the special process of plasma spraying Hydroxyapatite (HA) coating upon Ti-6Al-4V substrate. On the one hand, the classical Fourier transient heat conduction equation was modified by introducing the effect item of deformation on temperature, on the other hand, the Johnson-Cook model, suitable for high temperature and high strain rate conditions, was used as constitutive equation after considering temperature softening effect, strain hardening effect and strain rate reinforcement effect. Based on the above coupling model, the residual stress field within the HA coating was simulated by using finite element method (FEM). Meanwhile, the substrate preheating temperature and coating thickness on the influence of residual stress components were calculated, respectively. The failure modes of coating were also preliminary analyzed. In addition, in order to verify the reliability of calculation, the material removal measurement technique was applied to determine the residual stress of HA coating near the interface. Some important conclusions are obtained.

  13. Electrochemical Evaluation of Thin-Film Li-Si Anodes Prepared by Plasma Spraying

    Energy Technology Data Exchange (ETDEWEB)

    GUIDOTTI,RONALD A.; REINHARDT,FREDERICK W.; SCHARRER,GREGORY L.

    1999-09-08

    Thin-film electrodes of a plasma-sprayed Li-Si alloy were evaluated for use as anodes in high-temperature thermally activated (thermal) batteries. These anodes were prepared using 44% Li/56% Si (w/w) material as feed material in a special plasma-spray apparatus under helium or hydrogen, to protect this air- and moisture-sensitive material during deposition. Anodes were tested in single cells using conventional pressed-powder separators and lithiated pyrite cathodes at temperatures of 400 to 550 C at several different current densities. A limited number of 5-cell battery tests were also conducted. The data for the plasma-sprayed anodes was compared to that for conventional pressed-powder anodes. The performance of the plasma-sprayed anodes was inferior to that of conventional pressed-powder anodes, in that the cell emfs were lower (due to the lack of formation of the desired alloy phases) and the small porosity of these materials severely limited their rate capability. Consequently, plasma-sprayed Li-Si anodes would not be practical for use in thermal batteries.

  14. Oxidation Control of Atmospheric Plasma Sprayed FeAl Intermetallic Coatings Using Dry-Ice Blasting

    Science.gov (United States)

    Song, Bo; Dong, Shujuan; Coddet, Pierre; Hansz, Bernard; Grosdidier, Thierry; Liao, Hanlin; Coddet, Christian

    2013-03-01

    The performance of atmospheric plasma sprayed FeAl coatings has been remarkably limited because of oxidation and phase transformation during the high-temperature process of preparation. In the present work, FeAl intermetallic coatings were prepared by atmospheric plasma spraying combined with dry-ice blasting. The microstructure, oxidation, porosity, and surface roughness of FeAl intermetallic coatings were investigated. The results show that a denser FeAl coating with a lower content of oxide and lower degree of phase transformation can be achieved because of the cryogenic, the cleaning, and the mechanical effects of dry-ice blasting. The surface roughness value decreased, and the adhesive strength of FeAl coating increased after the application of dry-ice blasting during the atmospheric plasma spraying process. Moreover, the microhardness of the FeAl coating increased by 72%, due to the lower porosity and higher dislocation density.

  15. Research on the Plasma Spray Process Applying the Finite Element Method

    Directory of Open Access Journals (Sweden)

    Raimonda Lukauskaitė

    2015-03-01

    Full Text Available The article investigates the physical processes of plasma spraying. The application of the finite element method has assisted in establishing the distribution of the voltage of the plasma arc and current density in the plasma stream during numerical simulation. With reference to the results of experimental data, the real location of an anode spot of the electric arc in the plasma spray process has been evaluated. The paper has calculated the values of electromagnetic Lorentz forces and established their influence on plasma flow. With the help of the two-layer model for the semi-molten nickel particle, contact between the particle and substrate during plasma spraying has been simulated.

  16. Bioactive Glass-Ceramic Coatings Synthesized by the Liquid Precursor Plasma Spraying Process

    Science.gov (United States)

    Xiao, Yanfeng; Song, Lei; Liu, Xiaoguang; Huang, Yi; Huang, Tao; Chen, Jiyong; Wu, Yao; Wu, Fang

    2011-03-01

    In this study, the liquid precursor plasma spraying process was used to manufacture P2O5-Na2O-CaO-SiO2 bioactive glass-ceramic coatings (BGCCs), where sol and suspension were used as feedstocks for plasma spraying. The effect of precursor and spray parameters on the formation and crystallinity of BGCCs was systematically studied. The results indicated that coatings with higher crystallinity were obtained using the sol precursor, while nanostructured coatings predominantly consisting of amorphous phase were synthesized using the suspension precursor. For coatings manufactured from suspension, the fraction of the amorphous phase increased with the increase in plasma power and the decrease in liquid precursor feed rate. The coatings synthesized from the suspension plasma spray process also showed a good in vitro bioactivity, as suggested by the fast apatite formation when soaking into SBF.

  17. Preparation and Characterization of Plasma-Sprayed Ultrafine Chromium Oxide Coatings

    Institute of Scientific and Technical Information of China (English)

    LIN Feng; JIANG Xianliang; YU Yueguang; ZENG Keli; REN Xianjing; LI Zhenduo

    2007-01-01

    Ultrafine chromium oxide coatings were prepared by plasma spraying with ultrafine feedstock. Processing parameters of plasma spraying were optimized. Optical microscope (OM) was used to observe the microstructure of the ultrafine chromium oxide coatings. Scanning electron microscopy (SEM) was used to observe the morphology and particle size of ultrafine powder feedstock as well as to examine the microstructure of the chromium oxide coating. In addition, hardness and bonding strength of the ultrafine chromium oxide coatings were measured.The results showed that the optimized plasma spraying parameters were suitable for ultrafine chromium oxide coating and the properties and microstructure of the optimized ultrafine chromium oxide coating were superior compared to conventional chromium oxide wear resistant coatings.

  18. Characterisation of the TiO2 coatings deposited by plasma spraying

    Science.gov (United States)

    Benea, M. L.; Benea, L. P.

    2016-02-01

    Plasma spraying of materials such as ceramics and non-metals, which have high melting points, has become a well-established commercial process. Such coatings are increasingly used in aerospace, automobile, textile, medical, printing and electrical industries to impart proprieties such as corrosion resistance, thermal resistance, wear resistance, etc. One of the most important characteristics of thermal barrier coatings is the ability to undergo fast temperature changes without failing, the so called thermal shock resistance. The formation of residual stresses in plasma sprayed ceramic and metallic coatings is a very complex process. Several factors, such as substrate material, substrate thickness, physical properties of both the substrate and the coating material, deposition rate, relative velocity of the plasma torch, etc. determine the final residual stress state of the coating at room temperature. Our objective is to characterize the titanium oxide and aluminium oxide coatings deposited by plasma spraying in structural terms, the resistance to thermal shock and residual stresses.

  19. Wear and corrosion resistance of laser remelted and plasma sprayed Ni and Cr coatings on copper

    Institute of Scientific and Technical Information of China (English)

    梁工英; 黄俊达; 安耿

    2004-01-01

    Nickel and chromium coatings were produced on the copper sheet using plasma spraying and laser remelting. The sliding wear test was achieved on a block-on-ring tester and the corrosion test was carried out in an acidic atmosphere. The corrosive behaviors of both coatings and original copper samples were investigated by using an impedance comparison method. The experimental results show that the nickel and chromium coatings display better wear resistance and corrosion resistance relative to the original pure copper sample. The wear resistance of the coatings is 8 - 12 times as large as original samples, and the wear resistance of laser remelted samples is better than that of plasma sprayed ones. The corrosion resistance of laser remelted nickel and chromium samples is better than that of plasma sprayed samples respectively. The corrosion rate of chromium coatings is less than that of nickel coatings, and the laser remelted Cr coating exhibits the least corrosion rate.

  20. Wear resistance of laser cladding and plasma spray welding layer on stainless steel surface

    Institute of Scientific and Technical Information of China (English)

    Xinlin Wang(王新林); Shihong Shi(石世宏); Qiguang Zheng(郑启光)

    2004-01-01

    The effect of coatings, which are formed with laser cladding and plasma spray welding on 1Cr18Ni9Ti base metal, on wear resistance is studied, A 5-kW transverse flowing CO2 laser is used for cladding Co base alloy powder pre-placed on the substrate. Comparing with the plasma spray coatings, the spoiled rate of products with laser clad layers was lower and the rate of finished products was higher. Their microstructure is extremely fine. They have close texture and small size grain. Their dilution resulting from the compositions of the base metal and thermal effect on base metal are less. The hardness, toughness,and strength of the laser cladding layers are higher. Wear tests show that the laser layers have higher properties of anti-friction, anti-scour and high-temperature sliding strike. The wear resistance of laser clad layers are about one time higher than that of plasma spray welding layer.

  1. Research on fabricating Fe base amorphous alloy by bar plasma spraying

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Since amorphous alloys have wider application, they can not be fabricated using the conventional cooling velocity. The bar material plasma spraying is adopted to fabricate Fe base amorphous alloy in this investigation. The crystallization degree, microstructure, micro-hardness, composition, crystallization temperature of the amorphous alloy and the flying rules of the atomized particles in the process of the plasma spray are tested. The results show that the alloy prepared has the high amorphous degree and homogeneous microstructure, micro-hardness and the crystallization temperature can reach 1187HV and 531℃ respectively. The atomization is very well during the process of plasma spraying; and there is high thermal gradient, the cooling velocity reaches 6.07×107K/s.

  2. Determination of elastic modulus and residual stress of plasma-sprayed tungsten coating on steel substrate

    Energy Technology Data Exchange (ETDEWEB)

    You, J.H. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmann Street 2, 85748 Garching (Germany)]. E-mail: jeong-ha.you@ipp.mpg.de; Hoeschen, T. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmann Street 2, 85748 Garching (Germany); Lindig, S. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Boltzmann Street 2, 85748 Garching (Germany)

    2006-01-01

    Plasma-sprayed tungsten, which is a candidate material for the first wall armour, shows a porous, heterogeneous microstructure. Due to its characteristic morphology, the properties are significantly different from those of its dense bulk material. Measurements of the elastic modulus of this coating have not been reported in the literature. In this work Young's modulus of highly porous plasma-sprayed tungsten coatings deposited on steel (F82H) substrates was measured. For the fabrication of the coating system the vacuum plasma-spray process was applied. Measurements were performed by means of three-point and four-point bending tests. The obtained modulus values ranged from 53 to 57 GPa. These values could be confirmed by the test result of a detached coating strip, which was 54 GPa. The applied methods produced consistent results regardless of testing configurations and specimen sizes. The errors were less than 1%. Residual stress of the coating was also estimated.

  3. Determination of elastic modulus and residual stress of plasma-sprayed tungsten coating on steel substrate

    Science.gov (United States)

    You, J. H.; Höschen, T.; Lindig, S.

    2006-01-01

    Plasma-sprayed tungsten, which is a candidate material for the first wall armour, shows a porous, heterogeneous microstructure. Due to its characteristic morphology, the properties are significantly different from those of its dense bulk material. Measurements of the elastic modulus of this coating have not been reported in the literature. In this work Young's modulus of highly porous plasma-sprayed tungsten coatings deposited on steel (F82H) substrates was measured. For the fabrication of the coating system the vacuum plasma-spray process was applied. Measurements were performed by means of three-point and four-point bending tests. The obtained modulus values ranged from 53 to 57 GPa. These values could be confirmed by the test result of a detached coating strip, which was 54 GPa. The applied methods produced consistent results regardless of testing configurations and specimen sizes. The errors were less than 1%. Residual stress of the coating was also estimated.

  4. Characterization of plaque components with intravascular ultrasound elastography in human femoral and coronary arteries in vitro

    NARCIS (Netherlands)

    C.L. de Korte (Chris); G. Pasterkamp (Gerard); H.A. Woutman; N. Bom (Klaas); A.F.W. van der Steen (Ton)

    2000-01-01

    textabstractBACKGROUND: The composition of plaque is a major determinant of coronary-related clinical syndromes. Intravascular ultrasound (IVUS) elastography has proven to be a technique capable of reflecting the mechanical properties of phantom material and the femoral arterial

  5. Probability of mechanical loosening of the femoral component in high flexion total knee arthroplasty can be reduced by rather simple surgical techniques

    NARCIS (Netherlands)

    van de Groes, S.A.W.; De Waal Malefijt, M.C.; Verdonschot, Nicolaas Jacobus Joseph

    2014-01-01

    Background: Some follow-up studies of highflexion total knee arthoplasties report disturbingly high incidences of femoral component loosening. Femoral implantfixation is dependant on two interfaces: the cement–implant and the cement–bone interface. The present finite-element model (FEM) is the first

  6. Probability of mechanical loosening of the femoral component in high flexion total knee arthroplasty can be reduced by rather simple surgical techniques

    NARCIS (Netherlands)

    Groes, S.A.W. van de; Waal Malefijt, M.C. de; Verdonschot, N.J.J.

    2014-01-01

    BACKGROUND: Some follow-up studies of high flexion total knee arthoplasties report disturbingly high incidences of femoral component loosening. Femoral implant fixation is dependant on two interfaces: the cement-implant and the cement-bone interface. The present finite-element model (FEM) is the

  7. Direct morphological comparison of vacuum plasma sprayed and detonation gun sprayed hydroxyapatite coatings for orthopaedic applications.

    Science.gov (United States)

    Gledhill, H C; Turner, I G; Doyle, C

    1999-02-01

    Hydroxyapatite coatings on titanium substrates were produced using two thermal spray techniques vacuum plasma spraying and detonation gun spraying. X-ray diffraction was used to compare crystallinity and residual stresses in the coatings. Porosity was measured using optical microscopy in conjunction with an image analysis system. Scanning electron microscopy and surface roughness measurements were used to characterise the surface morphologies of the coatings. The vacuum plasma sprayed coatings were found to have a lower residual stress, a higher crystallinity and a higher level of porosity than the detonation gun coatings. It is concluded that consideration needs to be given to the significance of such variations within the clinical context.

  8. Atmosphere corrosion behavior of plasma sprayed and laser remelted coatings on copper

    Institute of Scientific and Technical Information of China (English)

    Gongying Liang; T. T. Wong; Geng An; J. M. K. MacAlpine

    2006-01-01

    Nickel and chromium coatings were produced using plasma spraying and laser remelting on the copper sheet. The corrosion test was carried out in an acidic atmosphere, and the corrosive behaviors of both coatings and original copper samples were investigated by using an impedance comparison method. Experimental results show that nickel and chromium coatings display better corrosion resistance properties relative to the original pure copper sample. The corrosion rate of chromium coating is less than that of nickel coating, and corrosion resistances of laser remelted nickel and chromium samples are better thanthose of plasma sprayed samples. The corrosion deposit film of copper is loose compared with nickel and chromium.

  9. Arthroscopic observation was useful to detect loosening of the femoral component of unicompartmental knee arthroplasty in a recurrent hemoarthrosis

    Directory of Open Access Journals (Sweden)

    Yamakado Kotaro

    2012-02-01

    Full Text Available Abstract A case of recurrent hemarthrosis of the knee after a mobile-bearing unicompartmental knee arthroplasty (UKA; Oxford UKA is described. A 58-year-old man met with a road traffic accident 10 months after UKA. He developed anteromedial pain and hemarthrosis of the knee joint 1 month after the accident, which required multiple aspirations. Physical examination showed no instability. Plain radiograph revealed no signs of loosening. All laboratory data, including bleeding and coagulation times, were within normal limits. Diagnostic arthroscopy demonstrated loosening of the femoral component. Any intraarticular pathology other than nonspecific synovitis was ruled out. The loose femoral component and polyethylene meniscal bearing were revised. Since then, hemarthrosis has not recurred.

  10. Fatigue testing of plasma-sprayed thermal barrier coatings, volume 2

    Science.gov (United States)

    Cruse, T. A.; Nagy, A.; Popelar, C. F.

    1990-01-01

    A plasma sprayed thermal barrier coating for diesel engines were fatigue tested. Candidate thermal barrier coating materials were fatigue screened and a data base was generated for the selected candidate material. Specimen configurations are given for the bend fatigue tests, along with test setup, specimen preparation, test matrix and procedure, and data analysis.

  11. Fatigue testing of plasma-sprayed thermal barrier coatings, Volume 2. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Cruse, T.A.; Nagy, A.; Popelar, C.F.

    1990-07-01

    A plasma sprayed thermal barrier coating for diesel engines were fatigue tested. Candidate thermal barrier coating materials were fatigue screened and a data base was generated for the selected candidate material. Specimen configurations are given for the bend fatigue tests, along with test setup, specimen preparation, test matrix and procedure, and data analysis.

  12. Preparation and properties of HA coating hydrothermally synthesized from plasma sprayed CaHPO4 coating

    Institute of Scientific and Technical Information of China (English)

    FU Tao; HAN Yong; ZHANG Yu-mei; XU Ke-wei

    2001-01-01

    @@ INTRODUCTION Hydroxyapatite (HA) biocoatings can form osseointegration at a shorter time than metallic implants, and plasma sprayed (PS) HA coating has received the widest studies and is now used clinically. However, due to the high temperature of plasma flame, soluble impurity phases and amorphous calcium phosphate were contained which declined the bonding strength of the coating, and spoiled the excellent biological properties of HA.

  13. Deformation Behavior of Nanostructured Ceramic Coatings Deposited by Thermal Plasma Spray

    Institute of Scientific and Technical Information of China (English)

    Xianliang JIANG; Eric Jordan; Leon Shaw; Maurice Gell

    2004-01-01

    Al2O3-13 wt pct TiO2 coating deposited by direct current plasma spray consists of nanostructured region and microlamellae. Bend test shows that the ceramic coating can sustain some deformation without sudden failure. The deformation is achieved through the movement of nano-particles in the nanostructured region under tensile stress.

  14. A new application field of plasma spraying technique to environmental depollution

    Institute of Scientific and Technical Information of China (English)

    YE Fu-xing; A.Ohmori

    2004-01-01

    To expand the application of plasma spraying technique, TiO2 coatings were prepared using agglomerated anatase TiO2 powder to solve the environmental problems. The composition and photocatalytic activity of plasma sprayed TiO2 coatings were investigated systematically. The content of anatase TiO2 in the sprayed coatings was approximate to 7%- 15%, which was influenced by the melting state of TiO2 powder in plasma spraying process. The surface of sprayed coating was very rough and the arithmetical mean deviation of the surface profiles (Ra) was in the range of 5.7 - 8.8 μm. Under lower arc current, the surface of the coating became rougher. The anatase to rutile phase transformation temperature of agglomerated anatase TiO2 powder was approximate to 1 173 K. The TiO2 coating sprayed under the arc current of 400 A had good photocatalytic activity for the relative high content of anatase phase in it. It is concluded that the application of plasma spraying technique to environmental field has been developed.

  15. Modeling Plasma-Particle Interaction in Multi-Arc Plasma Spraying

    Science.gov (United States)

    Bobzin, K.; Öte, M.

    2017-01-01

    The properties of plasma-sprayed coatings are controlled by the heat, momentum, and mass transfer between individual particles and the plasma jet. The particle behavior in conventional single-arc plasma spraying has been the subject of intensive numerical research, whereas multi-arc plasma spraying has not yet received the same attention. We propose herein a numerical model to serve as a scientific tool to investigate particle behavior in multi-arc plasma spraying. In the Lagrangian description of particles in the model, the mathematical formulations describing the heat, momentum, and mass transfer are of great importance for good predictive power, so such formulations proposed by different authors were compared critically, revealing that different mathematical formulations lead to significantly different results. The accuracy of the different formulations was evaluated based on theoretical considerations, and those found to be more accurate were implemented in the final model. Furthermore, a mathematical formulation is proposed to enable simplified calculation of partial particle melting and resolidification.

  16. THE POTENTIAL VALUE OF PHOTOTHERMAL IMAGING FOR THE TESTING OF PLASMA SPRAYED COATINGS

    OpenAIRE

    Almond, D.; Patel, P; Reiter, H.

    1983-01-01

    Measurements are presented which show that the photothermal technique may be used to evaluate plasma sprayed coatings. A photothermal image of a coating adhesion defect is shown and changes in photothermal signal with coating thickness are demonstrated. These measurements are compared directly with ultrasonic measurements of the same sample.

  17. Prospective five-year subsidence analysis of a cementless fully hydroxyapatite-coated femoral hip arthroplasty component.

    Science.gov (United States)

    Clauss, Martin; Van Der Straeten, Catherine; Goossens, Marc

    2014-01-01

    Early subsidence >1.5 mm is considered to be a predictive factor for later aseptic loosening of the femoral component following total hip arthroplasty (THA). The aim of this study was to assess five-year subsidence rates of the cementless hydroxyapatite-coated twinSys stem (Mathys Ltd., Bettlach, Switzerland).This prospective single-surgeon series examined consecutive patients receiving a twinSys stem at Maria Middelares Hospital, Belgium. Patients aged >85 years or unable to come to follow-up were excluded. Subsidence was assessed using Ein Bild Roentgen Analyse--Femoral Component Analysis (EBRA-FCA). Additional clinical and radiographic assessments were performed. Follow-ups were prospectively scheduled at two, five, 12, 24, and 60 months.In total, 218 THA (211 patients) were included. At five years, mean subsidence was 0.66 mm (95% CI: 0.43-0.90). Of the 211 patients, 95.2% had an excellent or good Harris Hip Score. There were few radiological changes. Kaplan-Meier analysis indicated five-year stem survival to be 98.4% (95% CI: 97.6-100%).Subsidence levels of the twinSys femoral stem throughout the five years of follow-up were substantially lower than the 1.5 mm level predictive of aseptic loosening. This was reflected in the high five-year survival rate.

  18. Prevalence and clinical significance of chondromalacia isolated to the anterior margin of the lateral femoral condyle as a component of patellofemoral disease: observations at MR imaging.

    LENUS (Irish Health Repository)

    Chan, V O

    2013-08-01

    To determine the prevalence of chondromalacia isolated to the anterior margin of the lateral femoral condyle as a component of patellofemoral disease in patients with anterior knee pain and to correlate it with patient demographics, patellar shape, and patellofemoral alignment.

  19. Modeling of evaporation and oxidation phenomena in plasma spraying of metal powders

    Science.gov (United States)

    Zhang, Hanwei

    Plasma spraying of metals in air is usually accompanied by evaporation and oxidation of the sprayed material. Optimization of the spraying process must ensure that the particles are fully molten during their short residence time in the plasma jet and prior to hitting the substrate, but not overheated to minimize evaporation losses. In atmospheric plasma spraying (ASP), it is also clearly desirable to be able to control the extent of oxide formation. The objective of this work to develop an overall mathematical model of the oxidization and volatilization phenomena involved in the plasma-spraying of metallic particles in air atmosphere. Four models were developed to simulate the following aspects of the atmospheric plasma spraying (APS) process: (a) the particle trajectories and the velocity and temperature profiles in an Ar-H 2 plasma jet, (b) the heat and mass transfer between particles and plasma jet, (c) the interaction between the evaporation and oxidation phenomena, and (d) the oxidation of liquid metal droplets. The resulting overall model was generated by adapting the computational fluid dynamics code FIDAP and was validated by experimental measurements carried out at the collaborating plasma laboratory of the University of Limoges. The thesis also examined the environmental implications of the oxidization and volatilization phenomena in the plasma spraying of metals. The modeling results showed that the combination of the standard k-s model of turbulence and the Boussinesq eddy-viscosity model provided a more accurate prediction of plasma gas behavior. The estimated NOx generation levels from APS were lower than the U.S.E.P.A. emission standard. Either enhanced evaporation or oxidation can occur on the surface of the metal particles and the relative extent is determined by the process parameters. Comparatively, the particle size has the greatest impact on both evaporation and oxidation. The extent of particle oxidation depends principally on gas

  20. Effects of Atomization Injection on Nanoparticle Processing in Suspension Plasma Spray

    Directory of Open Access Journals (Sweden)

    Hong-bing Xiong

    2016-05-01

    Full Text Available Liquid atomization is applied in nanostructure dense coating technology to inject suspended nano-size powder materials into a suspension plasma spray (SPS torch. This paper presents the effects of the atomization parameters on the nanoparticle processing. A numerical model was developed to simulate the dynamic behaviors of the suspension droplets, the solid nanoparticles or agglomerates, as well as the interactions between them and the plasma gas. The plasma gas was calculated as compressible, multi-component, turbulent jet flow in Eulerian scheme. The droplets and the solid particles were calculated as discrete Lagrangian entities, being tracked through the spray process. The motion and thermal histories of the particles were given in this paper and their release and melting status were observed. The key parameters of atomization, including droplet size, injection angle and velocity were also analyzed. The study revealed that the nanoparticle processing in SPS preferred small droplets with better atomization and less aggregation from suspension preparation. The injection angle and velocity influenced the nanoparticle release percentage. Small angle and low initial velocity might have more nanoparticles released. Besides, the melting percentage of nanoparticles and agglomerates were studied, and the critical droplet diameter to ensure solid melting was drawn. Results showed that most released nanoparticles were well melted, but the agglomerates might be totally melted, partially melted, or even not melted at all, mainly depending on the agglomerate size. For better coating quality, the suspension droplet size should be limited to a critical droplet diameter, which was inversely proportional to the cubic root of weight content, for given critical agglomerate diameter of being totally melted.

  1. Microstructural evolution and growth kinetics of thermally grown oxides in plasma sprayed thermal barrier coatings

    Directory of Open Access Journals (Sweden)

    Xiaoju Liu

    2016-02-01

    Full Text Available The formation of thermally grown oxide (TGO during high temperature is a key factor to the degradation of thermal barrier coatings (TBCs applied on hot section components. In the present study both the CoNiCrAlY bond coat and ZrO2-8 wt.% Y2O3 (8YSZ ceramic coat of TBCs were prepared by air plasma spraying (APS. The composition and microstructure of TGO in TBCs were investigated using scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS and X-ray diffraction (XRD analysis. The growth rate of TGO for TBC and pure BC were gained after isothermal oxidation at 1100 °C for various times. The results showed that as-sprayed bond coat consisted of β and γ/γ′phases, β phase reducesd as the oxidation time increased. The TGO comprised α-Al2O3 formed in the first 2 h. CoO, NiO, Cr2O3 and spinel oxides appeared after 20 h of oxidation. Contents of CoO and NiO reduced while that of Cr2O3 and spinel oxides increased in the later oxidation stage. The TGO eventually consisted of a sub-Al2O3 layer with columnar microstructure and the upper porous CS clusters. The TGO growth kinetics for two kinds of samples followed parabolic laws, with oxidation rate constant of 0.344 μm/h0.5 for TBCs and 0.354 μm/h0.5 for pure BCs.

  2. Microstructural evolution and growth kinetics of thermally grown oxides in plasma sprayed thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    Xiaoju Liu; Teng Wang; Caicai Li; Zhenhuan Zheng; Qiang Li

    2016-01-01

    The formation of thermally grown oxide (TGO) during high temperature is a key factor to the degradation of thermal barrier coatings (TBCs) applied on hot section components. In the present study both the CoNiCrAlY bond coat and ZrO2-8 wt.% Y2O3 (8YSZ) ceramic coat of TBCs were prepared by air plasma spraying (APS). The composition and microstructure of TGO in TBCs were investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis. The growth rate of TGO for TBC and pure BC were gained after isothermal oxidation at 1100 °C for various times. The results showed that as-sprayed bond coat consisted of β and γ/γ'phases,β phase reducesd as the oxidation time increased. The TGO comprised α-Al2O3 formed in the first 2 h. CoO, NiO, Cr2O3 and spinel oxides appeared after 20 h of oxidation. Contents of CoO and NiO reduced while that of Cr2O3 and spinel oxides increased in the later oxidation stage. The TGO eventually consisted of a sub-Al2O3 layer with columnar microstructure and the upper porous CS clusters. The TGO growth kinetics for two kinds of samples followed parabolic laws, with oxidation rate constant of 0.344 μm/h0.5 for TBCs and 0.354 μm/h0.5 for pure BCs.

  3. Bone-femoral component interface gap after sagittal mechanical axis alignment is filled with new bone after cementless total knee arthroplasty.

    Science.gov (United States)

    Kuriyama, Shinichi; Hyakuna, Katsufumi; Inoue, Satoshi; Kawai, Yasutsugu; Tamaki, Yasuyuki; Ito, Hiromu; Matsuda, Shuichi

    2017-02-14

    This study retrospectively evaluated the fate of mismatch between an uncemented femoral component and each femoral cut surface (i.e., wedge-shaped gap) relative to sagittal mechanical alignment in total knee arthroplasty (TKA). Primary TKA was performed on 99 consecutive knees. The femoral components were aligned to the sagittal mechanical axis with CT-based navigation. All patients were assessed with postoperative true lateral radiographs. Bone-side surfaces of the uncemented femoral component were divided into five zones: anterior flange, anterior chamfer, posterior chamfer, posterior part, and distal part, which were defined as zones 1 to 5, respectively. Bone filling of wedge-shaped gaps in each zone was evaluated after 1 year. Femoral anterior notching did not occur. However, wedge-shaped gaps were observed in at least one zone in 23 of 99 knees (23%), most frequently in zone 5 (18%). There were 9 and 7 gaps in zones 1 and 2, respectively. The femoral component showed malpositioning of approximately 3° of flexion in cases with wedge-shaped gaps in zones 2 and/or 5. After one year, 67% (6/9) of zone 1, 100% (7/7) of zone 2, and 94% (17/18) of zone 5 wedge-shaped gaps were filled in with new bone. Femoral alignment relative to sagittal mechanical axis caused wedge-shaped gaps due to unstable anterior bone cutting through hard bone, but the small gaps were not clinically significant and filled in within one year. Sagittal setting of the femoral component should aim for the anatomical axis rather than the mechanical axis. IV.

  4. Characterization of NbSi2-Al2O3 nanocomposite coatings prepared with plasma spraying mechanically alloyed powders

    Science.gov (United States)

    Yazdani, Zohreh; Karimzadeh, Fathallah; Abbasi, Mohammad-Hasan; Amini, Abbas

    2015-07-01

    The present study characterized NbSi2-Al2O3 nanocomposite powders plasma-sprayed on Ti-6Al-4V substrates. The powders were agglomerated to obtain suitable particle sizes for spraying. The agglomerated powders were then plasma-sprayed using atmospheric plasma spraying. The structural transformations of the powders along with the morphological and mechanical changes of the coatings were examined by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, and hardness testing. The results showed that after plasma spraying, the grain size increased, and the lattice strain decreased. However, the grain size of this compound after spraying was still in the nanometer range. The coating was uniform and exhibited good adhesion to the substrate. The microhardness and fracture toughness of the nanocomposite coating were higher than those of a nanostructured NbSi2 coating.

  5. Plasma Spraying of Copper by Hybrid Water-Gas DC Arc Plasma Torch

    Science.gov (United States)

    Kavka, T.; Matějíček, J.; Ctibor, P.; Mašláni, A.; Hrabovský, M.

    2011-06-01

    Water-stabilized DC arc plasma torches offer a good alternative to common plasma sources used for plasma spraying applications. Unique properties of the generated plasma are determined by a specific plasma torch construction. This article is focused on a study of the plasma spraying process performed by a hybrid torch WSP500®-H, which combines two principles of arc stabilization—water vortex and gas flow. Spraying tests with copper powder have been carried out in a wide range of plasma torch parameters. First, analyses of particle in-flight behavior for various spraying conditions were done. After, particles were collected in liquid nitrogen, which enabled analyses of the particle in-flight oxidation. A series of spraying tests were carried out and coatings were analyzed for their microstructure, porosity, oxide content, mechanical, and thermal properties.

  6. The History, Technical Specifications and Efficacy of Plasma Spray Coatings Applied to Joint Replacement Prostheses

    Directory of Open Access Journals (Sweden)

    Andrew McCabe

    2016-12-01

    Full Text Available Thermal plasma sprayed coatings are designed to improve both the biocompatibility and durability of implantable medical devices, and include pure titanium, cobalt/chrome alloy and hydroxyapatite.  Coated joint replacements have now been in continuous clinical use for thirty years and are applied to products manufactured or used in Europe, North America, South America, Africa, Asia and Australasia. Prostheses incorporating such coatings have been successfully implanted into several million of patients worldwide and to date there have been very few reports of any failure of an implant which could be attributed to problems with, or failure of, the coating. This paper summarises the early history of cementless prostheses and subsequent development, specification, validation, regulatory requirements and clinical performance of thermal plasma spray coatings provided by Accentus Medical.

  7. Comprehensive microstructural characterization and predictive property modeling of plasma-sprayed zirconia coatings

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, A.; Wang, Z.; Nakamura, T.; Sampath, S.; Goland, A.; Herman, H.; Allen, J.; Ilavsky, J.; Long, G.; Frahm, J.; Steinbrech, R.W

    2003-05-23

    Quantitative microstructure characterization to better understand processing-microstructure-property correlations is of considerable interest in plasma sprayed coating research. This paper quantifies, by means of small-angle neutron scattering (SANS) data, microstructure (porosity, opening dimensions, orientation and morphologies) in plasma sprayed partially-stabilized zirconia (PSZ) coatings, primarily used as thermal barrier coatings. We report on the investigation of the influence of feedstock characteristics on microstructure and establish its influence on the resultant thermal and mechanical properties. The microstructural parameters determined by SANS studies are then assembled into a preliminary model to develop a predictive capability for estimating the properties of these coatings. Thermal conductivity and elastic modulus were predicted using finite element analysis and ultimately compared to experimental values.

  8. PHOTOCATALYTIC PERFORMANCE OF PLASMA SPRAYED TiO2-ZnFe2O4 COATINGS

    Institute of Scientific and Technical Information of China (English)

    Y. Zeng; J.T. Liu; W.J. Qian; J.H. Gao

    2005-01-01

    A novel TiO2-ZnFe2O4 coating is prepared by plasma spraying. The effects of spraying parameters and the composition of powders on the microstructure, surface morphology and photo-absorption of plasma sprayed coatings are studied. The photocatalytic efficiency of the as-sprayed coatings is evaluated through the photo mineralization of methylene blue. It was found that TiO2 coatings can decompose methylene blue under the illumination of ultraviolet rays, and the degrading efficiency is improved with an increase in the content of FeTiO3 in the coatings. However, the presence of large amount of ZnFe2O4 compound will substantially lower the photocatalytic efficiency of the TiO2-ZnFe2O4 coatings for the unfavorable photo-excited electron-hole transfer process.

  9. Morphology, Structure and Biodegradability of Hollow HA Microspheres Obtained by Plasma Spraying

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The spraying-dried HA (ASD) was employed. ASD was plasma-sprayed onto ice to obtain hollow HA microspheres. The particle size of the sample was determined with a particle size analyzer. The morphology and structure of the samples were measured by scanning electron microscope and X-ray powder diffraction.The in vitro biodegradability of samples was evaluated by immersion tests in Ringer' s solution (RS) and simulated body fluid ( SBF). The samples were immersed respectively in RS and SBF for a period. The Ca2+ ion concentration in the solutions was determined by Atomic Adsorption Spectrum. By plasma spraying hollow HA microspheres were obtained. The hollow microspheres consisted mainly of low crystalline and amorphous HA, and had better biodegradability.

  10. The structure, properties and performance of plasma-sprayed beryllium for fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Castro, R.G.; Stanek, P.W.; Elliott, K.E. [and others

    1995-09-01

    Plasma-spray technology is under investigation as a method for producing high thermal conductivity beryllium coatings for use in magnetic fusion applications. Recent investigations have focused on optimizing the plasma-spray process for depositing beryllium coatings on damaged beryllium surfaces. Of particular interest has been optimizing the processing parameters to maximize the through-thickness thermal conductivity of the beryllium coatings. Experimental results will be reported on the use of secondary H{sub 2} gas additions to improve the melting of the beryllium powder and transferred-arc cleaning to improve the bonding between the beryllium coatings and the underlying surface. Information will also be presented on thermal fatigue tests which were done on beryllium coated ISX-B beryllium limiter tiles using 10 sec cycle times with 60 sec cooldowns and an International Thermonuclear Experimental Reactor (ITER) relevant divertor heat flux slightly in excess of 5 MW/m{sup 2}.

  11. Fabrication of Nanosized Lanthanum Zirconate Powder and Deposition of Thermal Barrier Coating by Plasma Spray Process

    Science.gov (United States)

    Mishra, S. K.; Jagdeesh, N.; Pathak, L. C.

    2016-07-01

    The present manuscript discusses our findings on fabrication of nanosized lanthanum zirconate powder for thermal barrier coating application and its coating by plasma spray on nickel-based superalloy substrate. Single-phase La2Zr2O7 coating of thickness of the order of 45 µm on the Ni-Cr-Al bond coat coated Ni-based superalloy substrate was deposited by plasma spray process. The layers at the interface did not show spallation and inter diffusion was very less. The microstructure, interface, porosity, and mechanical properties of different layers are investigated. The lanthanum zirconate hardness and modulus were 10.5 and 277 GPa, respectively. The load depth curve for lanthanum zirconate showed good elastic recovery around 74%.

  12. Fracture of the femoral component after a lightning strike injury: A case report.

    Science.gov (United States)

    Lizano-Díez, Xavier; Alentorn-Geli, Eduard; León-García, Alfonso; Marqués-López, Fernando

    2017-01-01

    A fracture of the stem in a total hip arthroplasty (THA) is an uncommon complication. We report a case of femoral stem fracture in a 55-year-old male patient after a lightning strike. A revision was conducted using a Wagner osteotomy and a revision prosthesis. Dall-Milles cerclages were used to close the osteotomy. The postoperative evolution was satisfactory, with an immediate partial weight bearing, consolidation of the osteotomy after three months and return to daily activity without pain. Copyright © 2016 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

  13. Solid oxide fuel cell electrolytes produced via very low pressure suspension plasma spray and electrophoretic deposition

    OpenAIRE

    Fleetwood, James D

    2014-01-01

    Solid oxide fuel cells (SOFCs) are a promising element of comprehensive energy policies due to their direct mechanism for converting the oxidization of fuel, such as hydrogen, into electrical energy. Both very low pressure plasma spray and electrophoretic deposition allow working with high melting temperature SOFC suspension based feedstock on complex surfaces, such as in non-planar SOFC designs. Dense, thin electrolytes of ideal composition for SOFCs can be fabricated with each of these proc...

  14. Monitoring Delamination of Plasma-Sprayed Thermal Barrier Coatings by Reflectance-Enhanced Luminescence

    Science.gov (United States)

    Eldridge, Jeffrey I.; Bencic, Timothy J.

    2006-01-01

    Highly scattering plasma-sprayed thermal barrier coatings (TBCs) present a challenge for optical diagnostic methods to monitor TBC delamination because scattering attenuates light transmitted through the TBC and usually degrades contrast between attached and delaminated regions of the TBC. This paper presents a new approach where reflectance-enhanced luminescence from a luminescent sublayer incorporated along the bottom of the TBC is used to identify regions of TBC delamination. Because of the higher survival rate of luminescence reflecting off the back surface of a delaminated TBC, the strong scattering exhibited by plasma-sprayed TBCs actually accentuates contrast between attached and delaminated regions by making it more likely that multiple reflections of luminescence off the back surface occur before exiting the top surface of the TBC. A freestanding coating containing sections designed to model an attached or delaminated TBC was prepared by depositing a luminescent Eu-doped or Er-doped yttria-stabilized zirconia (YSZ) luminescent layer below a plasma-sprayed undoped YSZ layer and utilizing a NiCr backing layer to represent an attached substrate. For specimens with a Eu-doped YSZ luminescent sublayer, luminescence intensity maps showed excellent contrast between unbacked and NiCr-backed sections even at a plasma-sprayed overlayer thickness of 300 m. Discernable contrast between unbacked and NiCr-backed sections was not observed for specimens with a Er-doped YSZ luminescent sublayer because luminescence from Er impurities in the undoped YSZ layer overwhelmed luminescence originating form the Er-doped YSZ sublayer.

  15. An Investigation on the Microstructure of Multi-phase Composite Coatings Synthesized by Plasma Spraying Self-reaction Composite Powders

    Institute of Scientific and Technical Information of China (English)

    DONGYan-chun; YANDian-ran; HeJi-ning; LiXiang-zhi; ZHANGJian-xin; NIUEr-wu

    2004-01-01

    Multi-phase self-reacLion composite (denoted as MPc) coatings containing ceramic and metal multi-phases were fabricated by plasma spraying Fe2O3-Al composite powders. This technology successfully combines self-propagating high-temperature synthesis with plasma spraying. The morphology of the composite powders was examined by scanning electron microscope (SEM). The phase composition and microstructure of the composite coating are studied.

  16. Thermal barrier ZrO2 - Y2O3 obtained by plasma spraying method and laser melting

    OpenAIRE

    2006-01-01

    Purpose: The aim of the paper is to determine the influence of laser melting upon the selected physical properties of ZrO2 - Y2O3 ceramic coatings deposited by APS (Air Plasma Spraying) method on super-alloys which function as TBC (Thermal Barriers Coatings).Design/methodology/approach: Laser melting which helps eliminate pores and other structural defects of coatings deposited by plasma spraying method should contribute to the improvement of their density and durability as thermal barriers. ...

  17. An Investigation on the Microstructure of Multi-phase Composite Coatings Synthesized by Plasma Spraying Self-reaction Composite Powders

    Institute of Scientific and Technical Information of China (English)

    DONG Yan-chun; YAN Dian-ran; HE Ji-ning; LI Xiang-zhi; ZHANG Jian-xin; NIU Er-wu

    2004-01-01

    Multi-phase self-reaction composite (denoted as MPc) coatings containing ceramic and metal multi-phases were fabricated by plasma spraying Fe2O3-Al composite powders. This technology successfully combines self-propagating high-temperature synthesis with plasma spraying. The morphology of the composite powders was examined by scanning electron microscope (SEM). The phase composition and microstructure of the composite coating are studied.

  18. Latest Researches Advances of Plasma Spraying: From Splat to Coating Formation

    Science.gov (United States)

    Fauchais, P.; Vardelle, M.; Goutier, S.

    2016-12-01

    The plasma spray process with solid feedstock, mainly ceramics powders, studied since the sixties is now a mature technology. The plasma jet and particle in-flight characterizations are now well established. The use of computer-aided robot trajectory allows spraying on industrial parts with complex geometries. Works about splat formation have shown the importance of: the substrate preheating over the transition temperature to get rid of adsorbates and condensates, substrate chemistry, crystal structure and substrate temperature during the whole coating process. These studies showed that coating properties strongly depend on the splat formation and layering. The first part of this work deals with a summary of conventional plasma spraying key points. The second part presents the current knowledge in plasma spraying with liquid feedstock, technology developed for about two decades with suspensions of particles below micrometers or solutions of precursors that form particles a few micrometers sized through precipitation. Coatings are finely structured and even nanostructured with properties arousing the interest of researchers. However, the technology is by far more complex than the conventional ones. The main conclusions are that models should be developed further, plasma torches and injection setups adapted, and new measuring techniques to reliably characterize these small particles must be designed.

  19. Plasma-spraying synthesis of high-performance photocatalytic TiO2 coatings

    Science.gov (United States)

    Takahashi, Yasuo; Shibata, Yoshitaka; Maeda, Masakatsu; Miyano, Yasuyuki; Murai, Kensuke; Ohmori, Akira

    2014-08-01

    Anatase (A-) TiO2 is a photocatalytic material that can decompose air-pollutants, acetaldehyde, bacteria, and so on. In this study, three kinds of powder (A-TiO2 without HAp, TiO2 + 10mass%HAp, and TiO2+30mass%HAp, where HAp is hydroxyapatite and PBS is polybutylene succinate) were plasma sprayed on biodegradable PBS substrates. HAp powder was mixed with A-TiO2 powder by spray granulation in order to facilitate adsorption of acetaldehyde and bacteria. The crystal structure was almost completely maintained during the plasma spray process. HAp enhanced the decomposition of acetaldehyde and bacteria by promoting adsorption. A 10mass% HAp content was the most effective for decomposing acetaldehyde when plasma preheating of the PBS was not carried out before the plasma spraying. The plasma preheating of PBS increased the yield rate of the spray process and facilitated the decomposition of acetaldehyde by A-TiO2 coatings without HAp. HAp addition improved photocatalytic sterilization when plasma preheating of the PBS was performed.

  20. Latest Researches Advances of Plasma Spraying: From Splat to Coating Formation

    Science.gov (United States)

    Fauchais, P.; Vardelle, M.; Goutier, S.

    2016-08-01

    The plasma spray process with solid feedstock, mainly ceramics powders, studied since the sixties is now a mature technology. The plasma jet and particle in-flight characterizations are now well established. The use of computer-aided robot trajectory allows spraying on industrial parts with complex geometries. Works about splat formation have shown the importance of: the substrate preheating over the transition temperature to get rid of adsorbates and condensates, substrate chemistry, crystal structure and substrate temperature during the whole coating process. These studies showed that coating properties strongly depend on the splat formation and layering. The first part of this work deals with a summary of conventional plasma spraying key points. The second part presents the current knowledge in plasma spraying with liquid feedstock, technology developed for about two decades with suspensions of particles below micrometers or solutions of precursors that form particles a few micrometers sized through precipitation. Coatings are finely structured and even nanostructured with properties arousing the interest of researchers. However, the technology is by far more complex than the conventional ones. The main conclusions are that models should be developed further, plasma torches and injection setups adapted, and new measuring techniques to reliably characterize these small particles must be designed.

  1. D. C. Plasma-Sprayed Coatings of Nanostructured Alumina-Titania-Silica

    Institute of Scientific and Technical Information of China (English)

    蒋显亮; 刘敏

    2002-01-01

    Nanocrystalline powders of w(Al2O3) = 95%, w(TiO2) = 3%, and w(SiO2) = 2%,were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps ofball milling, slurry forming, spray drying, and heat treatment. D. C. plasma was used to spraythe agglomerated nanocrystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Exper-imental results show that the agglomerated nanocrystalline particles are spherical, with a size from (10~90)μm. The flow ability of the nanocrystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nanostructure. Un-like conventional plasma-sprayed coatings, no laminar layer could be found in the nanostructured coatings. Although the nanostructured coatings have a lower microhardness than conventional microstructured coatings, the toughness of the nanostructured ceramic coatings is significantly improved.

  2. Residual stress analysis of the thermal barrier coating system by considering the plasma spraying process

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myung Jae; Lee, Byung Chai [KAIST, Daejeon (Korea, Republic of); Lim, Jang Gyun; Kim, Moon Ki [Sungkyunkwan University, Suwon (Korea, Republic of)

    2014-06-15

    The residual stress is the key factor causing the reliability problem of thermal barrier coating (TBC). The failure of plasma spray coatings due to residual stresses is a serious and recurring problem of TBC. The difference of thermal expansion coefficient between the substrate and each coating combined with temperature evolution and temperature gradients during deposition process determine the residual stress for the whole TBC system. The magnitudes and distributions of the residual stresses are affected by deposition process and deposition characteristics. Most of FEA (finite element analysis) has been performed under the assumption that the multilayer coating system is stacked at once without considering the deposition process during plasma spraying. In this research, FEA for a coupled heat transfer and elastic-plastic thermal stress was performed to obtain the more detailed and reliable result of residual stress of the TBC system using the element activation/deactivation technique. The residual stress variation from the start of plasma spraying to cooling stage with room temperature was obtained systematically considering the deposition process. It can be used as reference data to improve the performance of TBC. In addition, the relationship between residual stress and coating conditions such as cooling rate and time is also examined thoroughly.

  3. Wear behavior of gas tunnel type plasma sprayed Zr-based metallic glass composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Yugeswaran, S., E-mail: yugeswaran@gmail.com [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kobayashi, A., E-mail: kobayasi@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Suresh, K., E-mail: ksureshphy@gmail.com [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region (China); Rao, K.P., E-mail: mekprao@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region (China); Subramanian, B., E-mail: subramanianb3@gmail.com [CSIR - Central Electrochemical Research Institute, Karaikudi 630 006 (India)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Zr-based metallic glass composite coatings are prepared by gas tunnel plasma torch. Black-Right-Pointing-Pointer Increasing plasma current increases crystallinity amount and hardness of coatings. Black-Right-Pointing-Pointer Coating produced at 300 A plasma current gives minimum sliding wear rate. Black-Right-Pointing-Pointer Coating produced at higher plasma current gives lower erosive wear rate. - Abstract: Gas tunnel type plasma spraying is a prospective method to produce metallic glass composite coatings with high quality due to its noteworthy feature of process controllability. In this study, Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} metallic glass composite coatings were produced by gas tunnel type plasma spraying torch under optimum spraying conditions with selected plasma currents. The formation mechanism, sliding, and erosive wear behaviors of the coatings with respect to plasma current was examined. The phase and thermal analyses as well as microstructure of the plasma sprayed coatings produced at different plasma currents were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) techniques. The sliding and erosive wear behaviors of the coatings were studied using a pin-on-disc and a specially designed erosive wear tester, respectively. The results showed that an increase in plasma current increased the crystalline content in the metallic glass composite coatings, which enhanced the hardness and wear resistance of the coatings.

  4. The Solution Precursor Plasma Spray (SPPS) Process: A Review with Energy Considerations

    Science.gov (United States)

    Jordan, Eric H.; Jiang, Chen; Gell, Maurice

    2015-10-01

    Solution precursor plasma spray (SPPS) is a coating deposition process that uses conventional plasma spray equipment, and solution precursors, rather than ceramic or metal powders, as starting materials. Because the process is exposed to oxygen at high temperatures, nearly all coatings, to date, are oxide ceramics. In this review, both the advantages and the disadvantages of the SPPS process and some comparisons made to the suspension plasma spray (SPS) process will be discussed. The advantages of the SPPS process include rapid exploration of compositions and fabrication of advanced coatings with unique microstructural features. Examples presented span densities from porous thermal barrier coatings (TBCs) to dense TiO2 coatings. Two TBCs are in an advanced development stage: (1) a low thermal conductivity YSZ TBC and (2) a high-temperature yttrium aluminum garnet TBC. As for disadvantages, there are (1) the additional development work for each new precursor and (2) a lower standoff distance and deposition rate than the APS process, related to the evaporation of the solvent. The SPS process shares the same disadvantages. In developing new coatings, a number of factors should be considered and understood, which would help to shorten future development efforts. Future directions of the SPPS process will also be discussed.

  5. Recent Trends in Newly Developed Plasma-Sprayed and Sintered Coatings for Implant Applications

    Science.gov (United States)

    Bsat, Suzan; Speirs, Andrew; Huang, Xiao

    2016-08-01

    The current paper aims to review recent trends (2011 to 2015) in newly developed plasma-sprayed and sintered coatings for implant applications. Recent developments in plasma-sprayed and sintered coatings have focused on improving biological performance, bacterial growth resistance, and mechanical properties, predominantly of HA and glass ceramics. The majority of these improvements are attributed to the addition of dopants. To improve biological performance, trace elements, such as Zn and Mg, both of which are found in bone, were added to replicate the functions they provide for the skeletal system. Though bacterial growth resistance is traditionally improved by Ag dopant, the addition of new dopants such as CeO2 and Zn were explored as well. Great effort has also been made to improve coating adherence and reduce stresses by minimizing coefficient of thermal expansion mismatch between the coating and substrate through the addition of elements such as Zn and Mg or the inclusion of a buffer layer. For sintering process in particular, there was an emphasis on reducing sintering temperature through modification of 45S5 Bioglass. New plasma spray and sintering technologies aimed at reducing high-temperature exposure are briefly introduced as well. These include microplasma spray and spark plasma sintering.

  6. Liquid Feedstock Plasma Spraying: An Emerging Process for Advanced Thermal Barrier Coatings

    Science.gov (United States)

    Markocsan, Nicolaie; Gupta, Mohit; Joshi, Shrikant; Nylén, Per; Li, Xin-Hai; Wigren, Jan

    2017-08-01

    Liquid feedstock plasma spraying (LFPS) involves deposition of ultrafine droplets of suspensions or solution precursors (typically ranging from nano- to submicron size) and permits production of coatings with unique microstructures that are promising for advanced thermal barrier coating (TBC) applications. This paper reviews the recent progress arising from efforts devoted to development of high-performance TBCs using the LFPS approach. Advancements in both suspension plasma spraying and solution precursor plasma spraying, which constitute the two main variants of LFPS, are presented. Results illustrating the different types of the microstructures that can be realized in LFPS through appropriate process parameter control, model-assisted assessment of influence of coating defects on thermo-mechanical properties and the complex interplay between pore coarsening, sintering and crystallite growth in governing thermal conductivity are summarized. The enhancement in functional performances/lifetime possible in LFPS TBCs with multilayered architectures and by incorporating new pyrochlore chemistries such as gadolinium zirconate, besides the conventional single 8 wt.% yttria-stabilized zirconia insulating ceramic layer, is specifically highlighted.

  7. In vitro antibacterial and osteogenic properties of plasma sprayed silver-containing hydroxyapatite coating

    Institute of Scientific and Technical Information of China (English)

    RUAN HongJiang; FAN CunYi; ZHENG XueBin; ZHANG Yan; CHEN YiKai

    2009-01-01

    The objective of the present investigation was to characterize the antibacterial and osteogenic proper-ties of plasma sprayed silver-containing hydroxyapatite (HA/Ag) coating in vitro. HA/Ag coating was deposited via vacuum plasma spraying. The concentration of silver ions released from HA/Ag coating, the efficacy of the HA/Ag coating against bacterial biofilm development, the effect of the HA/Ag coating on early adhesion and ossification of osteoblast cells in vitro was measured. The silver ion concentra-tion released from the HA/Ag coating was between the minimum inhibitory concentration to bacteria and the cytotoxic concentration. Bacterial biofiim inhibition studies indicated an antibacterial activity on the HA/Ag coating surface when compared with hydroxyapatite (HA) coating alone. Moreover, it was demonstrated that osteoblast cell adhesion and mineralization occurred on the HA/Ag coating surface during the testing period. We conclude that the vacuum plasma sprayed HA/Ag coating possesses good antibacterial capability and osteogenic properties in vitro and represents a promising candidate for coating orthopedic implants.

  8. Ceramic Top Coats of Plasma-Sprayed Thermal Barrier Coatings: Materials, Processes, and Properties

    Science.gov (United States)

    Bakan, Emine; Vaßen, Robert

    2017-08-01

    The ceramic top coat has a major influence on the performance of the thermal barrier coating systems (TBCs). Yttria-partially-stabilized zirconia (YSZ) is the top coat material frequently used, and the major deposition processes of the YSZ top coat are atmospheric plasma spraying and electron beam physical vapor deposition. Recently, also new thermal spray processes such as suspension plasma spraying or plasma spray-physical vapor deposition have been intensively investigated for TBC top coat deposition. These new processes and particularly the different coating microstructures that can be deposited with them will be reviewed in this article. Furthermore, the properties and the intrinsic-extrinsic degradation mechanisms of the YSZ will be discussed. Following the TBC deposition processes and standard YSZ material, alternative ceramic materials such as perovskites and hexaaluminates will be summarized, while properties of pyrochlores with regard to their crystal structure will be discussed more in detail. The merits of the pyrochlores such as good CMAS resistance as well as their weaknesses, e.g., low fracture toughness, processability issues, will be outlined.

  9. D. C. plasma-sprayed coatings of nano-structured alumina-titania-silica

    CERN Document Server

    Jiang Xian Liang

    2002-01-01

    nano-crystalline powders of omega(Al sub 2 O sub 3) = 95%, omega(TiO sub 2) = 3%, and omega(SiO sub 2) = 2%, were reprocessed into agglomerated particles for plasma spraying, by using consecutive steps of ball milling, slurry forming, spray drying, and heat treatment. D.C. plasma was used to spray the agglomerated nano-crystalline powders, and resultant coatings were deposited on the substrate of stainless steel. Scanning electron microscopy (SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings. Experimental results show that the agglomerated nano-crystalline particles are spherical, with a size from (10-90) mu m. The flow ability of the nano-crystalline powders is greatly improved after the reprocessing. The coatings deposited by the plasma spraying are mainly of nano-structure. Unlike conventional plasma-sprayed coatings, no laminar layer could be found in the nano-structured coatings. Although the nano-structured coatings have a lo...

  10. Effect of Samarium Oxide on the Electrical Conductivity of Plasma-Sprayed SOFC Anodes

    Science.gov (United States)

    Panahi, S. N.; Samadi, H.; Nemati, A.

    2016-10-01

    Solid oxide fuel cells (SOFCs) are rapidly becoming recognized as a new alternative to traditional energy conversion systems because of their high energy efficiency. From an ecological perspective, this environmentally friendly technology, which produces clean energy, is likely to be implemented more frequently in the future. However, the current SOFC technology still cannot meet the demands of commercial applications due to temperature constraints and high cost. To develop a marketable SOFC, suppliers have tended to reduce the operating temperatures by a few hundred degrees. The overall trend for SOFC materials is to reduce their service temperature of electrolyte. Meanwhile, it is important that the other components perform at the same temperature. Currently, the anodes of SOFCs are being studied in depth. Research has indicated that anodes based on a perovskite structure are a more promising candidate in SOFCs than the traditional system because they possess more favorable electrical properties. Among the perovskite-type oxides, SrTiO3 is one of the most promising compositions, with studies demonstrating that SrTiO3 exhibits particularly favorable electrical properties in contrast with other perovskite-type oxides. The main purpose of this article is to describe our study of the effect of rare-earth dopants with a perovskite structure on the electrical behavior of anodes in SOFCs. Sm2O3-doped SrTiO3 synthesized by a solid-state reaction was coated on substrate by atmospheric plasma spray. To compare the effect of the dopant on the electrical conductivity of strontium titanate, different concentrations of Sm2O3 were used. The samples were then investigated by x-ray diffraction, four-point probe at various temperatures (to determine the electrical conductivity), and a scanning electron microscope. The study showed that at room temperature, nondoped samples have a higher electrical resistance than doped samples. As the temperature was increased, the electrical

  11. Potent effect of zinc acexamate on bone components in the femoral-metaphyseal tissues of elderly female rats.

    Science.gov (United States)

    Yamaguchi, M; Gao, Y H

    1998-03-01

    1. The effect of zinc compounds on bone components in the femoral-metaphyseal tissues from elderly female rats (50 weeks old) was investigated in vitro. Bone tissues were cultured for 24 hr in Dulbecco's modified Eagle medium containing either vehicle or zinc compounds (10[-7] to 10[-5] M). 2. Zinc content, alkaline phosphatase activity, deoxyribonucleic acid (DNA) and calcium contents in the metaphyseal tissues were significantly increased by the presence of zinc sulfate (10[-6] and 10[-5] M), beta-alanyl-L-histidinato zinc (AHZ; 10[-6] and 10[-5] M) and zinc acexamate (10[-7] to 10[-5] M). At 10[-5] M, the effect of zinc acexamate on the increase of bone components was more potent than that of zinc sulfate or AHZ. 3. The effect of zinc acexamate (10[-5] M) on the increase of alkaline phosphatase activity in the metaphyseal tissues was remarkable as compared with that of insulin (10[-8] M), estrogen (10[-9] M), insulin-like growth factor-I (10[-8] M), transforming growth factor-beta (10[-10] M), sodium fluoride (10[-3] M), dexamethasone (10[-7] M) and vitamin K2 (menaquinone-4; 10[-5] M) with an effective concentration. 4. The stimulatory effect of zinc acexamate (10[-5] M) on alkaline phosphatase activity and calcium content in the metaphyseal tissues was completely blocked by the presence of dipicolinate (10[-3] M), a chelator of zinc ion, and of cycloheximide (10[-6] M), an inhibitor of protein synthesis. 5. The present study demonstrates that zinc acexamate has a potent anabolic effect on bone components in the femoral-metaphyseal tissues from female elderly rats in vitro. The effect of zinc acexamate may be based in part on protein synthesis related to zinc ion in bone cells.

  12. Analysis of Plasma-Sprayed Thermal Barrier Coatings With Homogeneous and Heterogeneous Bond Coats Under Spatially Uniform Cyclic Thermal Loading

    Science.gov (United States)

    Arnold, Steven M.; Pindera, Marek-Jerzy; Aboudi, Jacob

    2003-01-01

    This report summarizes the results of a numerical investigation into the spallation mechanism in plasma-sprayed thermal barrier coatings observed under spatially-uniform cyclic thermal loading. The analysis focuses on the evolution of local stress and inelastic strain fields in the vicinity of the rough top/bond coat interface during thermal cycling, and how these fields are influenced by the presence of an oxide film and spatially uniform and graded distributions of alumina particles in the metallic bond coat aimed at reducing the top/bond coat thermal expansion mismatch. The impact of these factors on the potential growth of a local horizontal delamination at the rough interface's crest is included. The analysis is conducted using the Higher-Order Theory for Functionally Graded Materials with creep/relaxation constituent modeling capabilities. For two-phase bond coat microstructures, both the actual and homogenized properties are employed in the analysis. The results reveal the important contributions of both the normal and shear stress components to the delamination growth potential in the presence of an oxide film, and suggest mixed-mode crack propagation. The use of bond coats with uniform or graded microstructures is shown to increase the potential for delamination growth by increasing the magnitude of the crack-tip shear stress component.

  13. Microstructural Characteristics of Y2O3-MgO Composite Coatings Deposited by Suspension Plasma Spray

    Science.gov (United States)

    Muoto, Chigozie K.; Jordan, Eric H.; Gell, Maurice; Aindow, Mark

    2012-12-01

    Dense composite Y2O3-MgO coatings have been deposited by suspension plasma spray. Ethanol-based suspensions of powders synthesized by thermal decomposition of precursor solutions containing yttrium nitrate (Y[n]) and magnesium nitrate (Mg[n]) or magnesium acetate (Mg[a]) were selected as the feedstock; this gave powders with both phases in each particle, to inhibit phase segregation during solvent evaporation. The influence of powder characteristics on the microstructures of the coatings was investigated. The Y[n]Mg[a] suspension was more stable, with a better dispersion of the component phases than the Y[n]Mg[n] suspension. The coatings deposited using each suspension type exhibited lamellar structures comprising Y2O3 and MgO phases in wavy alternating streaks, with unmelted/semi-melted particles entrapped in the lamellae; this indicates that phase segregation still occurred in the molten state. Eutectic structures were formed in the coating generated using the Y[n]Mg[a] suspension, resulting from improved mixing of the component phases in the suspension powder.

  14. Solid particle erosion of plasma sprayed ceramic coatings

    Directory of Open Access Journals (Sweden)

    Branco José Roberto Tavares

    2004-01-01

    Full Text Available Thermal spraying allows the production of overlay protective coatings of a great variety of materials, almost without limitations as to its components, phases and constituents on a range of substrates. Wear and corrosion resistant coatings account for significant utilization of thermal spray processes. Besides being a means to evaluate the coating tribological performance, erosion testing allows also an assessment of the coating toughness and adhesion. Nevertheless, the relationship between the erosion behavior of thermal sprayed coatings and its microstructural features is not satisfactorily understood yet. This paper examines room temperature solid particle erosion of zirconia and alumina-based ceramic coatings, with different levels of porosity and varying microstrucutre and mechanical properties. The erosion tests were carried out by a stream of alumina particles with an average size of 50 µm at 70 m/s, carried by an air jet with impingement angle 90°. The results indicate that current erosion models based on hardness alone cannot account for experimental results, and, that there is a strong relationship between the erosion rate and the porosity.

  15. [EFFECTIVENESS OF ANATOMIC FEMORAL COMPONENT PROSTHESIS FOR SEVERE DEVELOPMENTAL DYSPLASIA OF THE HIP IN TOTAL HIP ARTHROPLASTY].

    Science.gov (United States)

    An, Xiao; Dong, Jiyuan; Gong, Ke; Zhang, Qi; Li, Xiang; Song, Wei

    2015-04-01

    To evaluate the effectiveness of anatomic femoral component prosthesis for severe development dysplasia of the hip (DDH) in total hip arthroplasty (THA). Between September 2009 and September 2013, 48 patients (51 hips) with severe DDH underwent THA with cementless anatomic femoral component prosthesis. There were 5 males (5 hips) and 43 females (46 hips) with an average age of 51 years (range, 28-67 years). The left hip was involved in 25 cases, the right hip in 20 cases, and bilateral hips in 3 cases. There were 39 cases (44 hips) of Crowe type III and 9 cases (7 hips) of Crowe type IV. The visual analogue scale (VAS) score was 5.72 +/- 1.84, and Harris score was 41.66 +/- 4.87 at preoperation. All patients had leg discrepancy with a length difference of (4.31 +/- 0.84) cm. The duration of surgery was 59-110 minutes (mean, 78.6 minutes), and the hospitalization days were 6-20 days (mean, 12.3 days). All patients obtained primary healing of incision without wound related complications of swelling, effusion, and infection. Two patients were found to have intramuscular venous thrombosis. All patients were followed up 10-54 months (mean, 29 months). Limp was observed at the early stage after operation in 9 patients and disappeared after 1 year, the other patients had normal gait. The VAS score 1.46?0.47, Harris score 88.66 +/- 3.48, and the leg length difference (1.15 +/- 0.33) cm at last follow-up all showed significant differences when compared with the preoperative values (Phip joint function and limb discrepancy. Short-term effectiveness was satisfactory, but the long-term effectiveness should still be observed in future.

  16. DEVELOPMENT OF COMPLEX EQUIPMENT FOR PLASMA SPRAY CERAMIC COATINGS

    Directory of Open Access Journals (Sweden)

    V. V. Okovity

    2017-01-01

    Full Text Available Develop a set equipment for plasma forming ceramic coatings. The article presents characteristics and parameters of the developed complex equipment for formation of plasma ceramic coatings as well as results of its testing. Methods of research is based on studies of structural elements composite plasma coatings system ZrO2 – Y2O3  obtained  using  developed complex equipment. One of the most effective ways to protect the components from high temperature corrosion and oxidation is formation on the surface of plasma thermal barrier coatings. For thermal barrier coating has very strict requirements: сharacterized by a smooth change of physico-mechanical properties (porosity, microhardness, elastic modulus in the cross section of the metal substrate to the outer ceramic layer; to withstand multiple cycles of thermal cycling from room temperature to the operating temperature; to maintain gastightness under operating conditions and thus ensure a sufficiently high level of adhesive strength. For realization of new technological schemes applying thermal barrier coatings with high operational characteristics was developed, patented and manufactured a range of new equipment. The experiments show that authors developed PBG-1 plasmatron and powder feeder PPBG-04 have at least 2–3 times the service life during the deposition of ceramic materials compared to the standard equipment of the company "Plasma-Technik", by changing the structure of the cathode-anode plasma torch assembly and construction of the delivery unit of the feeder to facilitate the uniform supply of the powder into the plasma jet and the best of his penetration. The result is better plasma coatings with improved operational characteristics: adhesion strength is increased to 1.3–2 times, material utilization in 1.5–1.6 times microhardness 1.2–1.4 times the porosity is reduced by 2–2.5 times.

  17. Topography of the femoral nerve in relation to components of the iliopsoas muscle in human fetuses.

    Science.gov (United States)

    Jakubowicz, M

    1991-01-01

    Studies were performed on 60 human fetuses of both sexes of 35 to 365 mm C.-R. length (9-40 weeks). The psoas minor muscle was found in 25.8% of cases independently of sex and body side. In 6.45% of cases the muscle continued into psoas major muscle by short, weakly developed tendon. In 97.5% of studied fetuses junctions between tendons of psoas major and iliacus muscles was observed. In 2.5% of cases an independent, short tendon was found in the half of length of the iliacus muscle. In 7.5% of cases connection between the psoas major and iliacus muscles was found. In all cases femoral nerve originated from the lumbar plexus between two layers of the psoas major muscle and it ran in the groove between the psoas major and iliacus muscles towards the muscular lacuna. In 5.0% of cases the nerve divided into crura. In 2.5% of cases the crura embraced anteriorly and posteriorly bundles of the psoas major muscle as well as in 2.5% of cases bundles of the iliacus muscle.

  18. Mathematical analysis of thermoelastic characteristics in plasma-sprayed thermal barrier coatings.

    Science.gov (United States)

    Go, Jaegwi; Jungo, Yeon-Gil; Kim, Seokchan; Ali, Md Afsar; Paik, Ungyu

    2012-02-01

    The thermoelastic characteristics of plasma-sprayed thermal barrier coatings (TBCs) have been analyzed using mathematical modeling. Two types of TBC model, cylinder and circular disk which are commercial plasma-sprayed TBCs, subjecting to symmetric temperature distribution to the radial and longitudinal directions, respectively, were taken into consideration. Based on the thermoelastic theories, a second order ordinary differential equation was derived for the cylinder model and a pair of partial differential equations were set up for the circular disk model. The analytic solution was obtained from the ordinary differential equation, while a finite volume method was developed for numerical solutions to the pair of partial differential equations due to the complexity of governing equations. The thermoelastic characteristics of TBC models, such as temperature distributions, displacements, and stresses, were displayed according to the obtained solutions. The rate of heat conduction in the section of the top coat is relatively slow in comparison with the substrate, and no profound difference appears in the temperature distribution between two TBC models. The highest longitudinal tensile stress is expressed at the bond coat of both models, and the substrate is under the compressive stresses to the circumferential direction. While the cylinder expands to the positive longitudinal direction only, the expansion in the circular disk occurs to both the positive and negative longitudinal directions. Relatively large displacement and stresses exhibit in the cylinder as compared with the circular disk. In the circular disk, the stresses to the radial direction undulate at each section, and the displacement profile displays that the width of the circular disk is slightly narrowed. The results demonstrate that the mechanical and thermal properties of the top and bond coats are the crucial factors to be considered in controlling the thermoelastic characteristics of plasma-sprayed

  19. Corrosion performance of atmospheric plasma sprayed alumina coatings on AZ31B magnesium alloy under immersion environment

    Directory of Open Access Journals (Sweden)

    D. Thirumalaikumarasamy

    2014-12-01

    Full Text Available Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. The alumina powders were plasma sprayed on AZ31B magnesium alloy with three different plasma spraying parameters. In the present work, the influence of plasma spray parameters on the corrosion behavior of the coatings was investigated. The corrosion behavior of the coated samples was evaluated by immersion corrosion test in 3.5 wt% NaCl solution. Empirical relationship was established to predict the corrosion rate of plasma sprayed alumina coatings by incorporating process parameters. The experiments were conducted based on a three factor, five-level, central composite rotatable design matrix. The developed relationship can be effectively used to predict the corrosion rate of alumina coatings at 95% confidence level. The results indicate that the input power has the greatest influence on corrosion rate, followed by stand-off distance and powder feed rate.

  20. Microstructure and Oxidation Resistance of Laser Remelted Plasma Sprayed Nicraly Coating

    Directory of Open Access Journals (Sweden)

    Niemiec D.

    2016-06-01

    Full Text Available The article presents results of research relating to the impact of laser treatment done to the surface of plasma sprayed coatings NiCrAlY. Analysis consisted microstructure and oxidation resistance of coatings subjected to two different laser melting surfaces. The test were performed at a temperature 1000°C the samples were removed from the furnace after 25, 300, 500, 750 and 1000 hours. The investigations range included analysis of top surface of coatings by XRD characterization oxides formed types and microscopic investigations of coatings morphology

  1. Plasma-spray synthesis and characterization of ti-based nitride and oxide nanogranules

    Energy Technology Data Exchange (ETDEWEB)

    Antipas, Georgios S.E., E-mail: gantipas@metal.ntua.gr [School of Mining Engineering and Metallurgy, National Technical University of Athens, Athens (Greece)

    2014-09-15

    The synthesis of nanosized Ti-based nanogranules via plasma spraying is reported. The synthesis route involved use of both nitrogen and oxygen gases with varying results. In the case of nitrogen, a mixture of titanium nitrides were produced, yielding both the Ti2N and the sub-stoichiometric TiN0.61 compounds. In the case of oxygen, both the stoichiometric rutile and TiO ceramic phases were indexed. Based on EDS analysis, even fractional oxygen concentrations caused tungsten impurities which originated from the cathode electrode. The method yielded particle mass median sizes of the order of 15nm and the smallest particles detected were 5nm. (author)

  2. Morphology and Phase Compositions of Hydroxyapatite Powder Particles Plasma-sprayed into Water

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Hydroxyapatite powder particles were plasma sprayed into water, their inner structures and phase compositions were studied by using scanning electron microscope(SEM) and X-ray difiractometer. The results show that the molten HA particles have a central hollow morphology and high crystallinity. The hollow morphology was caused by sublimated P2O5 and H2O, which will have an efiect on surface morphology, cohesive and adhesive strength as well as dissolution and degradation of coating. The high crystallinity is attributed to lower cooling speed in water.

  3. The change of NiCrBSi alloys’ phase composition after plasma spraying

    Directory of Open Access Journals (Sweden)

    A. Dudek

    2008-08-01

    Full Text Available Material for investigations was NiCrBSi powder for components’ coatings which improve their corrosion resistance as well as resistance to friction wear and erosion. Plasma spraying method was used to produce a coating with thickness of 300 μm on low-alloy steel which was then remelted with the base material. Using X-ray quality analysis, phase composition was determined for: NiCrBSi powder, obtained coating and the alloyed surface layer. Crystallinity degree was also calculated for NiCrBSi layer sprayed on the base material.

  4. Physical, mechanical, and tribological properties of quasicrystalline Al-Cu-Fe coatings prepared by plasma spraying

    Science.gov (United States)

    Lepeshev, A. A.; Rozhkova, E. A.; Karpov, I. V.; Ushakov, A. V.; Fedorov, L. Yu.

    2013-12-01

    The physical, mechanical, and tribological properties of quasicrystalline coatings based on the Al65Cu23Fe12 alloy prepared by plasma spraying have been investigated. The specific features of the phase formation due to the competitive interactions of the icosahedral ψ and cubic β phases have been elucidated. A correlation between the microhardness and the content of the icosahedral phase in the coating has been determined. The decisive role of the quasicrystalline phase in the formation of high tribological characteristics of the coatings has been revealed and tested.

  5. The application of plasma-sprayed ceramic coatings on lift roller in float glass

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Oxide ceramic was sprayed via high-energy plasma spray using MCrAlY manufactured with special technique as bond coating and oxide ceramic as top coating in this article. Investigation showed that the dense and highly adhesive coating could be obtained with optimized technique. After grinding and polishing, coating roughness was lower than 0. 2μm, which could meet the requirements of lift roller. After one year serv ice, molten Tin could not adhere to the ceramic coating,well it greatly alleviated its corrosion to the roller , kept the surface of oxide ceramic coating smooth and the improve the quality of glass due to the strengthened lift roll.

  6. The use of uncemented extensively porous-coated femoral components in the management of Vancouver B2 and B3 periprosthetic femoral fractures.

    Science.gov (United States)

    O'Shea, K; Quinlan, J F; Kutty, S; Mulcahy, D; Brady, O H

    2005-12-01

    We assessed the outcome of patients with Vancouver type B2 and B3 periprosthetic fractures treated with femoral revision using an uncemented extensively porous-coated implant. A retrospective clinical and radiographic assessment of 22 patients with a mean follow-up of 33.7 months was performed. The mean time from the index procedure to fracture was 10.8 years. There were 17 patients with a satisfactory result. Complications in four patients included subsidence in two, deep sepsis in one, and delayed union in one. Concomitant acetabular revision was required in 19 patients. Uncemented extensively porous-coated femoral stems incorporate distally allowing stable fixation. We found good early survival rates and a low incidence of nonunion using this implant.

  7. A randomised controlled trial of cemented and cementless femoral components for metal-on-metal hip resurfacing: a bone mineral density study.

    Science.gov (United States)

    Tice, A; Kim, P; Dinh, L; Ryu, J J; Beaulé, P E

    2015-12-01

    The primary purpose of this study of metal-on-metal (MoM) hip resurfacing was to compare the effect of using a cementless or cemented femoral component on the subsequent bone mineral density (BMD) of the femoral neck. This was a single-centre, prospective, double-blinded control trial which randomised 120 patients (105 men and 15 women) with a mean age of 49.4 years (21 to 68) to receive either a cemented or cementless femoral component. Follow-up was to two years. Outcome measures included total and six-point region-of-interest BMD of the femoral neck, radiological measurements of acetabular inclination, neck-shaft and stem-shaft angles, and functional outcome scores including the Harris hip score, the Western Ontario and McMaster Universities Osteoarthritis Index and the University of California at Los Angeles activity scale. In total, 17 patients were lost to follow-up leaving 103 patients at two years. There were no revisions in the cementless group and three revisions (5%) in the cemented group (two because of hip pain and one for pseudotumour). The total BMD was significantly higher in the cementless group at six months (p < 0.001) and one year (p = 0.01) than in the cemented group, although there was a loss of statistical significance in the difference at two years (p = 0.155). All patient outcomes improved significantly: there were no significant differences between the two groups. The results show better preservation of femoral neck BMD with a cementless femoral component after two years of follow-up. Further investigation is needed to establish whether this translates into improved survivorship.

  8. Fast plasma sintering delivers functional graded materials components with macroporous structures and osseointegration properties.

    Science.gov (United States)

    Godoy, R F; Coathup, M J; Blunn, G W; Alves, A L; Robotti, P; Goodship, A E

    2016-04-13

    We explored the osseointegration potential of two macroporous titanium surfaces obtained using fast plasma sintering (FPS): Ti macroporous structures with 400-600 µmØ pores (TiMac400) and 850-1000 µmØ pores (TiMac850). They were compared against two surfaces currently in clinical use: Ti-Growth® and air plasma spray (Ti-Y367). Each surface was tested, once placed over a Ti-alloy and once onto a CoCr bulk substrate. Implants were placed in medial femoral condyles in 24 sheep. Samples were explanted at four and eight weeks after surgery. Push-out loads were measured using a material-testing system. Bone contact and ingrowth were assessed by histomorphometry and SEM and EDX analyses. Histology showed early osseointegration for all the surfaces tested. At 8 weeks, TiMac400, TiMac850 and Ti-Growth® showed deep bone ingrowth and extended colonisation with newly formed bone. The mechanical push-out force was equal in all tested surfaces. Plasma spray surfaces showed greater bone-implant contact and higher level of pores colonisation with new bone than FPS produced surfaces. However, the void pore area in FPS specimens was significantly higher, yet the FPS porous surfaces allowed a deeper osseointegration of bone to implant. FPS manufactured specimens showed similar osseointegration potential to the plasma spray surfaces for orthopaedic implants. FPS is a useful technology for manufacturing macroporous titanium surfaces. Furthermore, its capability to combine two implantable materials, using bulk CoCr with macroporous titanium surfaces, could be of interest as it enables designers to conceive and manufacture innovative components. FPS delivers functional graded materials components with macroporous structures optimised for osseointegration.

  9. Total hip arthroplasty with cement and use of a collared matte-finish femoral component: nineteen to twenty-year follow-up.

    Science.gov (United States)

    Callaghan, John J; Liu, Steve S; Firestone, Daniel E; Yehyawi, Tameem M; Goetz, Devon D; Sullivan, Jason; Vittetoe, David A; O'Rourke, Michael R; Johnston, Richard C

    2008-02-01

    In the mid- to late 1970s, on the basis of laboratory and finite element data, many surgeons in the United States began using collared matte-finish femoral components and metal-backed acetabular components in their total hip arthroplasties. The purpose of this study was to evaluate the long-term results of the use of one such construct in arthroplasties performed by a single surgeon in a consecutive nonselected patient cohort. Between January 1984 and December 1985, 273 patients underwent a total of 304 consecutive nonselected total hip arthroplasties with cement and use of the Iowa femoral component (which is collared, has a proximal cobra shape, and has a matte finish) and a metal-backed TiBac acetabular component performed by a single surgeon. At nineteen to twenty years postoperatively, only two patients (two hips) were lost to follow-up. For clinical evaluation, we attempted to interview all living patients and the families of the patients who had died to verify the status of the hip prosthesis or any revisions. Radiographic evaluation consisted of analysis for loosening and osteolysis as well as wear of the acetabular component. At the time of the nineteen to twenty-year follow-up, the rate of revision of the arthroplasty for any reason was 10.5% (thirty-two hips) for all patients and 25% (twenty-three hips) for living patients. The rate of revision due to aseptic femoral loosening was 2.6% (eight hips). There was radiographic evidence of loosening of the femoral component in fifteen hips (4.9%), including those that were revised, and femoral osteolysis was seen distal to the trochanters in twenty-two hips (7.2%). The rate of revision due to aseptic loosening of the acetabular component was 7.9% (twenty-four hips), and there was radiographic evidence of acetabular loosening in forty-two hips (13.8%), including those that were revised. This study demonstrates the durability of a cemented matte-finish collared femoral component at twenty years postoperatively

  10. Risk factors for post-operative periprosthetic fractures following primary total hip arthroplasty with a proximally coated double-tapered cementless femoral component

    DEFF Research Database (Denmark)

    Gromov, K; Bersang, A; Nielsen, C S

    2017-01-01

    periprosthetic fractures (3.0%) were identified during the follow-up and median time until fracture was 16 days, (interquartile range 10 to 31.5). Patients with femoral Dorr type C had a 5.2 times increased risk of post-operative periprosthetic fracture compared with type B, while female patients had a near...... significant two times increased risk over time for post-operative fracture. CONCLUSION: Dorr type C is an independent risk factor for early periprosthetic fracture, following THA using a double tapered cementless stem such as the Bi-Metric. Surgeons should take bone morphology into consideration when planning......AIMS: The aim of this study was to identify patient- and surgery-related risk factors for sustaining an early periprosthetic fracture following primary total hip arthroplasty (THA) performed using a double-tapered cementless femoral component (Bi-Metric femoral stem; Biomet Inc., Warsaw, Indiana...

  11. Plasma-Sprayed Hydroxylapatite-Based Coatings: Chemical, Mechanical, Microstructural, and Biomedical Properties

    Science.gov (United States)

    Heimann, Robert B.

    2016-06-01

    This contribution discusses salient properties and functions of hydroxylapatite (HA)-based plasma-sprayed coatings, including the effect on biomedical efficacy of coating thickness, phase composition and distribution, amorphicity and crystallinity, porosity and surface roughness, cohesion and adhesion, micro- and nano-structured surface morphology, and residual coating stresses. In addition, it will provide details of the thermal alteration that HA particles undergo in the extremely hot plasma jet that leads to dehydroxylated phases such as oxyhydroxylapatite (OHA) and oxyapatite (OA) as well as thermal decomposition products such as tri-(TCP) and tetracalcium phosphates (TTCP), and quenched phases such as amorphous calcium phosphate (ACP). The contribution will further explain the role of ACP during the in vitro interaction of the as-deposited coatings with simulated body fluid resembling the composition of extracellular fluid (ECF) as well as the in vivo responses of coatings to the ECF and the host tissue, respectively. Finally, it will briefly describe performance profiles required to fulfill biological functions of osteoconductive bioceramic coatings designed to improve osseointegration of hip endoprostheses and dental root implants. In large parts, the content of this contribution is a targeted review of work done by the author and his students and coworkers over the last two decades. In addition, it is considered a stepping stone toward a standard operation procedure aimed at depositing plasma-sprayed bioceramic implant coatings with optimum properties.

  12. Better Quality Control: Stochastic Approaches to Optimize Properties and Performance of Plasma-Sprayed Coatings

    Science.gov (United States)

    Heimann, Robert B.

    2010-06-01

    Statistical design of experiment (SDE) methodology applied to design and performance testing of plasma-sprayed coatings follows an evolutionary path, usually starting with classic multiparameter screening designs (Plackett-Burman), and progressing through factorial (Taguchi) to limited response surface designs (Box-Behnken). Modern designs of higher dimensionality, such as central composite and D-optimal designs, will provide results with higher predictive power. Complex theoretical models relying on evolutionary algorithms, and application of artificial neuronal networks (ANNs) and fuzzy logic control (FLC) allow estimating the behavior of the complex plasma spray environment through validation either by key experiments or first-principle calculations. In this review, paper general principles of SDE will be discussed and examples be given that underscore the different powers of prediction of individual statistical designs. Basic rules of ANN and FLC will be briefly touched on, and their potential for increased reliability of coating performance through stringent quality control measures assessed. Salient features will be reviewed of studies performed to optimize thermal coating properties and processes reported in the pertinent literature between 2000 and the present.

  13. Isothermal Oxidation Behavior of Supersonic Atmospheric Plasma-Sprayed Thermal Barrier Coating System

    Science.gov (United States)

    Bai, Yu; Ding, Chunhua; Li, Hongqiang; Han, Zhihai; Ding, Bingjun; Wang, Tiejun; Yu, Lie

    2013-10-01

    In this work, Y2O3 stabilized zirconia-based thermal barrier coatings (TBCs) were deposited by conventional atmospheric plasma spraying (APS) and high efficiency supersonic atmospheric plasma spraying (SAPS), respectively. The effect of Al2O3 layer stability on the isothermal growth behavior of thermally grown oxides (TGOs) was studied. The results revealed that the Al2O3 layer experienced a three-stage change process, i.e., (1) instantaneous growth stage, (2) steady-state growth stage, and (3) depletion stage. The thickness of Al2O3 scale was proved to be an important factor for the growth rate of TGOs. The SAPS-TBCs exhibited a higher Al2O3 stability and better oxidation resistance as compared with the APS-TBCs. Additionally, it was found that inner oxides, especially nucleated on the top of the crest, continually grew and swallowed the previously formed Al2O3 layer, leading to the granulation and disappearance of continuous Al2O3 scale, which was finally replaced by the mixed oxides and spinel.

  14. Flow characteristic of in-flight particles in supersonic plasma spraying process

    Science.gov (United States)

    Wei, Pei; Wei, Zhengying; Zhao, Guangxi; Du, Jun; Bai, Y.

    2016-09-01

    In this paper, a computational model based on supersonic plasma spraying (SAPS) is developed to describe the plasma jet coupled with the injection of carrier gas and particles for SAPS. Based on a high-efficiency supersonic spraying gun, the 3D computational model of spraying gun was built to study the features of plasma jet and its interactions with the sprayed particles. Further the velocity and temperature of in-flight particles were measured by Spray Watch 2i, the shape of in-flight particles was observed by scanning electron microscope. Numerical results were compared with the experimental measurements and a good agreement has been achieved. The flight process of particles in plasma jet consists of three stages: accelerated stage, constant speed stage and decelerated stage. Numerical and experimental indicates that the H2 volume fraction in mixture gas of Ar + H2 should keep in the range of 23-26 %, and the distance of 100 mm is the optimal spraying distance in Supersonic atmosphere plasma spraying. Particles were melted and broken into small child particles by plasma jet and the diameters of most child particles were less than 30 μm. In general, increasing the particles impacting velocity and surface temperature can decrease the coating porosity.

  15. Effect of Solid Shield on Coating Properties in Atmospheric Plasma Spray Process

    Science.gov (United States)

    Liu, Ting; Zheng, Lili; Zhang, Hui

    2016-12-01

    This paper investigates the impact of shrouded shield structure on plasma spray processes and the selection of optimal shield structure. Response of plasma flame characteristics to solid shield structures is studied first, and experimental investigations are then performed for both atmospheric (APS) and shrouded (SPS) plasma spray processes. It is found that the usage of conical shield (divergence angle 5.5°) with 90 mm in length is effective to form a low-oxygen (3000 K) region in the plasma flame and this region can cover the majority area for particles passing by. The average particle temperature is higher in SPS than in APS with the given conditions, and such behavior is intensified as solid shield length increases. Using the SPS process, more disk-shaped splats are obtained, and the oxygen concentration in coating is significantly reduced. The degree of the oxidation in the coatings is further reduced as the length of the solid shield increases from 50 to 90 mm. Applying solid shield will lead to high flame temperature and low oxidation; however, the substrate overheating and velocity reduction may occur. For the cases studied, the optimal shield length is around 90 mm.

  16. Low friction stainless steel coatings graphite doped elaborated by air plasma sprayed

    Science.gov (United States)

    Harir, A.; Ageorges, H.; Grimaud, A.; Fauchais, P.; Platon, F.

    2004-10-01

    A new process has been developed to incorporate graphite particles into a stainless steel coating during its formation. Four means have been tested to inject the graphite particles outside the plasma jet and its plume: graphite suspension, a graphite rod rubbed on the rotating sample, powder injection close to the substrate with an injector, or a specially designed guide. The last process has been shown to be the most versatile and the most easily controllable. It allows the incorporation of between 2 and 12 vol.% of graphite particles (2 15 µm) within the plasma sprayed stainless steel coatings. A volume fraction of 2% seems to give the best results with a slight decrease (6%) of the coating hardness. This volume fraction also gave the best results in dry friction on the pin-on-disk apparatus. Depending on the sliding velocity (0.1 0.5 m/s) and loads (3.7 28 N), the dry friction coefficient against a 100C6 pin is reduced by between 1.5 and 4 compared with that obtained with plasma sprayed stainless steel.

  17. Microstructure and Tribological Properties of Plasma-sprayed Nanostructured Sulfide Coating

    Institute of Scientific and Technical Information of China (English)

    Yang XU; Yaohui GUAN; Zhongyu ZHENG; Xiaohui TONG

    2006-01-01

    The friction and wear properties of plasma-sprayed nanostructured FeS coating were investigated on an MHK-500 friction and wear tester under both oil lubrication and dry friction condition. The microstructure, worn surface morphology and phase composition of the coating were characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD). It was found that the coating was mainly composed of FeS, a small quantity of Fe1-xS and oxide were also found. The coating was formed by small particles of 50~100 nm in size. The thickness of the coating is approximately 150μm. The friction-reduction and wear-resistance properties of plasma-sprayed nanostructured FeS coating were superior to that of GCr15 steel substrate.Especially under oil lubrication condition, the friction coefficient of nanostructured FeS coating was 50% of that of GCr15 steel, the wear scar widths of the coating were also reduced to nearly 50% of that of GCr15 steel under high load. The failure of the coating was mainly attributed to plastic deformation under both oil lubrication and dry friction condition.

  18. Nano Structured Plasma Spray Coating for Wear and High Temperature Corrosion Resistance Applications

    Science.gov (United States)

    Ghosh, D.; Shukla, A. K.; Roy, H.

    2014-04-01

    The nano structured coating is a major challenge today to improve the different mechanical properties, wear and high temperature corrosion resistance behaviour of different industrial alloys. This paper is a review on synthesis of nano powder, plasma spraying methods, techniques of nano structured coating by plasma spray method, mechanical properties, tribological properties and high temperature corrosion behaviour of nano structured coating. Nano structured coatings of ceramic powders/composites are being developed for wide variety of applications like boiler, turbine and aerospace industries, which requires the resistance against wear, corrosion, erosion etc. The nano sized powders are subjected to agglomeration by spray drying, after which nano structured coating can be successfully applied over the substrate. Nano structured coating shows improved mechanical wear resistance and high temperature corrosion resistance. The significant improvement of wear and corrosion resistance is mainly attributed to formation of semi molten nano zones in case of nano structured coatings. The future scope of application of nano structured coating has also been highlighted in this paper.

  19. Factors affecting the microstructural stability and durability of thermal barrier coatings fabricated by air plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Helminiak, M.A.; Yanar, N.M.; Pettit, F.S.; Meier, G.H. [National Energy Technology Laboratory, Pittsburgh, PA 15236 (United States); Department of Mechanical Engineering and Materials Science, University of Pittsburgh, 636 Benedum Hall, 3700 O& #x27; Hara Street, Pittsburgh, PA 15261 (United States); Taylor, T.A. [Praxair Surface Technologies, Inc., 1400 Polco Street, Indianapolis, IN 46224 (United States)

    2012-10-15

    The high-temperature behavior of high-purity, low-density (HP-LD) air plasma sprayed (APS) thermal barrier coatings (TBCs) with NiCoCrAlY bond coats deposited by argon-shrouded plasma spraying is described. The high purity yttria-stabilized zirconia resulted in top coats which are highly resistant to sintering and transformation from the metastable tetragonal phase to the equilibrium mixture of monoclinic and cubic phases. The thermal conductivity of the as-processed TBC is low but increases during high temperature exposure even before densification occurs. The porous topcoat microstructure also resulted in good spallation resistance during thermal cycling. The actual failure mechanisms of the APS coatings were found to depend on topcoat thickness, topcoat density, and the thermal cycle frequency. The failure mechanisms are described and the durability of the HP-LD coatings is compared with that of state-of-the-art electron beam physical vapor deposition TBCs. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Characterization of Microstructure and Thermal Properties of YSZ Coatings Obtained by Axial Suspension Plasma Spraying (ASPS)

    Science.gov (United States)

    Ganvir, Ashish; Curry, Nicholas; Björklund, Stefan; Markocsan, Nicolaie; Nylén, Per

    2015-10-01

    The paper aims at demonstrating various microstructures which can be obtained using the suspension spraying technique and their respective significance in enhancing the thermal insulation property of a thermal barrier coating. Three different types of coating microstructures are discussed which were produced by the Axial Suspension Plasma Spraying. Detailed characterization of coatings was then performed. Optical and scanning electron microscopy were utilized for microstructure evaluations; x-ray diffraction for phase analysis; water impregnation, image analysis, and mercury intrusion porosimetry for porosity analysis, and laser flash analysis for thermal diffusivity measurements were used. The results showed that Axial Suspension Plasma Spraying can generate vertically cracked, porous, and feathery columnar-type microstructures. Pore size distribution was found in micron, submicron, and nanometer range. Higher overall porosity, the lower density of vertical cracks or inter-column spacing, and higher inter-pass porosity favored thermal insulation property of the coating. Significant increase in thermal diffusivity and conductivity was found at higher temperature, which is believed to be due to the pore rearrangement (sintering and pore coarsening). Thermal conductivity values for these coatings were also compared with electron beam physical vapor deposition (EBPVD) thermal barrier coatings from the literature and found to be much lower.

  1. Thickness measurement approach for plasma sprayed coatings using ultrasonic testing technique

    Institute of Scientific and Technical Information of China (English)

    LIN Li; LI Xi-meng; XU Zhi-hui; LEI Ming-kai

    2004-01-01

    The special ultrasonic testing system has been developed for thickness measurement of plasma sprayed coatings. The ultrasonic immersion method was used to obtain stable coupling condition and avoid other disadvantages of contact method. Spherical acoustic lens were designed to focus ultrasonic beam so as to improve beam directivity and concentrate ultrasonic energy. To increase testing precision and avoid mussy wave signals, moderate pulse width and frequency of the transducer has been selected. The displacement of transducer in X-Y-Z directions was precisely manipulated by step-controlled system to insure the accuracy of focus length and repetition of measurement. Optimized testing conditions (with the transducer of center frequency of 10 MHz and crystal diameter of 8 mm, focus length of 9.5 mm, diameter of focal column of 0. 1 mm and length of focal column of 0.27 mm) were selected to determine the thickness between 285 -414 μm of ZrO2 coatings plasma sprayed on the nickel based superalloy. The frequency interval of the periodic extremums in ultrasonic power spectra decreases with increasing coating thickness. The ultrasonic results accord with those of metallographical method.

  2. Temperature Measurement Challenges and Limitations for In-Flight Particles in Suspension Plasma Spraying

    Science.gov (United States)

    Aziz, Bishoy; Gougeon, Patrick; Moreau, Christian

    2017-03-01

    Suspension plasma spraying (SPS) acquires a significant interest from the industry. The deposited coatings using this technique were proved to have unique microstructural features compared to those built by conventional plasma spraying techniques. In order to optimize this process, in-flight particle diagnostics is considered a very useful tool that helps to control various spraying parameters and permits better coating reproducibility. In that context, the temperature of in-flight particles is one of the most important key elements that helps to optimize and control the SPS process. However, the limitations and challenges associated with this process have a significant effect on the accuracy of two-color pyrometric techniques used to measure the in-flight particle temperature. In this work, the influence of several nonthermal radiation sources on the particle temperature measurement is studied. The plasma radiation scattered by in-flight particles was found to have no significant influence on temperature measurement. Moreover, the detection of the two-color signals at two different locations was found to induce a significant error on temperature measurement. Finally, the plasma radiation surrounding the in-flight particles was identified as the main source of error on the temperature measurement of in-flight particles.

  3. Comparison of thermal shock behaviors between plasma-sprayed nanostructured and conventional zirconia thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    LIU Chun-bo; ZHANG Zhi-min; JIANG Xian-liang; LIU Min; ZHU Zhao-hui

    2009-01-01

    NiCoCrAlTaY bond coat was deposited on pure nickel substrate by low pressure plasma spraying(LPPS), and ZrO2-8%Y2O3 (mass fraction) nanostructured and ZrO2-7%Y2O3 (mass fraction) conventional thermal barrier coatings(TBCs) were deposited by air plasma spraying(APS). The thermal shock behaviors of the nanostructured and conventional TBCs were investigated by quenching the coating samples in cold water from 1 150, 1 200 and 1 250 ℃, respectively. Scanning electron microscopy(SEM) was used to examine the microstructures of the samples after thermal shock testing. Energy dispersive analysis of X-ray(EDAX) was used to analyze the interface diffusion behavior of the bond coat elements. X-ray diffractometry(XRD) was used to analyze the constituent phases of the samples. Experimental results indicate that the nanostructured TBC is superior to the conventional TBC in thermal shock performance. Both the nanostructured and conventional TBCs fail along the bond coat/substrate interface. The constituent phase of the as-sprayed conventional TBC is diffusionless-transformed tetragonal(t′). However, the constituent phase of the as-sprayed nanostructured TBC is cubic(c). There is a difference in the crystal size at the spalled surfaces of the nanostructured and conventional TBCs. The constituent phases of the spalled surfaces are mainly composed of Ni2.88Cr1.12 and oxides of bond coat elements.

  4. Performance Testing of Suspension Plasma Sprayed Thermal Barrier Coatings Produced with Varied Suspension Parameters

    Directory of Open Access Journals (Sweden)

    Nicholas Curry

    2015-07-01

    Full Text Available Suspension plasma spraying has become an emerging technology for the production of thermal barrier coatings for the gas turbine industry. Presently, though commercial systems for coating production are available, coatings remain in the development stage. Suitable suspension parameters for coating production remain an outstanding question and the influence of suspension properties on the final coatings is not well known. For this study, a number of suspensions were produced with varied solid loadings, powder size distributions and solvents. Suspensions were sprayed onto superalloy substrates coated with high velocity air fuel (HVAF -sprayed bond coats. Plasma spray parameters were selected to generate columnar structures based on previous experiments and were maintained at constant to discover the influence of the suspension behavior on coating microstructures. Testing of the produced thermal barrier coating (TBC systems has included thermal cyclic fatigue testing and thermal conductivity analysis. Pore size distribution has been characterized by mercury infiltration porosimetry. Results show a strong influence of suspension viscosity and surface tension on the microstructure of the produced coatings.

  5. Stress Analysis and Failure Mechanisms of Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Yang, Jiasheng; Wang, Liang; Li, Dachuan; Zhong, Xinghua; Zhao, Huayu; Tao, Shunyan

    2017-06-01

    Yttria-stabilized zirconia coatings were deposited by plasma spraying and heat-treated at 1100 °C for 50, 100, 150, and 200 h in air, respectively. Mechanical properties including microhardness and Young's modulus were evaluated using the nanoindentation test. Residual stresses in the ceramic topcoat and the thermally grown oxide (TGO) layer were measured using Raman spectroscopy and photoluminescence piezo-spectroscopy (PLPS) techniques, respectively. The results showed that both the modulus and hardness increased with the thermal exposure time up to 100 h and then gradually decreased. The accumulated tensile stress in the as-sprayed topcoat changed to compressive stress after thermal exposure, and the compressive stress in the topcoat increased with an increase of thermal exposure time up to 150 h. The average compressive stresses in the TGO layer were higher than that of the cross-sectional topcoat, and the measured in-plane compressive stress increased firstly and then gradually decreased with increasing exposure time. The local interface geometry strongly affect the nature and evolution of hydrostatic stresses in the TGO. Finally, the crack initiation and propagation at the topcoat/TGO/bondcoat interface has been discussed with respect to the residual stresses in the plasma-sprayed TBC system.

  6. Indentations on Air Plasma Sprayed Thermal Barrier Coatings Prepared by Different Starting Granules

    Directory of Open Access Journals (Sweden)

    Yong Suk Heo

    2015-01-01

    Full Text Available The effect of starting granules on the indentation properties of air plasma sprayed thermal barrier coatings (TBCs is investigated in this paper. Various kinds of spray-dried granules are prepared from different processing conditions, especially varying solvent and dispersant, showing a deformed hollow-typed and a filled spherical-typed granule. The similar coating thicknesses are prepared by adjusting process parameters during air plasma spray. All XRD peaks in phase analysis are tetragonal and cubic phases without any monoclinic phase after the starting granules were heat-treated. A relatively porous microstructure of the coating layer could be obtained from the monodisperse granules, while a relatively dense microstructure resulted from the hollow-typed granules. The morphology and distribution of the granules crucially affect the microstructure of thermal barrier coatings and thus have influences on indentation properties such as indentation stress-strain curves, contact damage, and hardness. The implication concerning microstructure design of TBCs for gas turbine applications is considered.

  7. Piezospectroscopic measurements capturing the evolution of plasma spray-coating stresses with substrate loads.

    Science.gov (United States)

    Freihofer, Gregory; Fugon-Dessources, Daniela; Ergin, Emrecan; Van Newkirk, Amy; Gupta, Ankur; Seal, Sudipta; Schülzgen, Axel; Raghavan, Seetha

    2014-02-12

    Plasma-spray coatings have a unique microstructure composed of various types of microcracks and weakly bonded interfaces which dictate their nonlinear mechanical properties. The intrinsic photo-luminescence (PL) characteristics of alpha-alumina (α-Al2O3) within these coatings offer a diagnostic functionality, enabling these properties to be probed experimentally at the microscale, under substrate loading. The piezospectroscopic (PS) measurements from the coatings are capable of revealing microstructural stress at high spatial resolution. Here, for the first time, the evolution of stresses within air plasma spray (APS) coatings under increasing substrate loads were captured using piezospectroscopy. With mechanical cycling of the substrate, the PS properties revealed anelastic and inelastic behavior and a relaxation of residual tensile stress within the APS coatings. With decreasing substrate thickness, the coating was observed to sustain more stress, as the substrate's influence on the mechanical behavior decreased. The findings provide an insight into the microstructural response that can serve as the basis for model validation and subsequently drive the design process for these coatings.

  8. Plasma Spray-Physical Vapor Deposition (PS-PVD) of Ceramics for Protective Coatings

    Science.gov (United States)

    Harder, Bryan J.; Zhu, Dongming

    2011-01-01

    In order to generate advanced multilayer thermal and environmental protection systems, a new deposition process is needed to bridge the gap between conventional plasma spray, which produces relatively thick coatings on the order of 125-250 microns, and conventional vapor phase processes such as electron beam physical vapor deposition (EB-PVD) which are limited by relatively slow deposition rates, high investment costs, and coating material vapor pressure requirements. The use of Plasma Spray - Physical Vapor Deposition (PS-PVD) processing fills this gap and allows thin (coatings of less than 100 microns to be generated with the flexibility to tailor microstructures by changing processing conditions. Coatings of yttria-stabilized zirconia (YSZ) were applied to NiCrAlY bond coated superalloy substrates using the PS-PVD coater at NASA Glenn Research Center. A design-of-experiments was used to examine the effects of process variables (Ar/He plasma gas ratio, the total plasma gas flow, and the torch current) on chamber pressure and torch power. Coating thickness, phase and microstructure were evaluated for each set of deposition conditions. Low chamber pressures and high power were shown to increase coating thickness and create columnar-like structures. Likewise, high chamber pressures and low power had lower growth rates, but resulted in flatter, more homogeneous layers

  9. Oxidation Behavior of Titanium Carbonitride Coating Deposited by Atmospheric Plasma Spray Synthesis

    Science.gov (United States)

    Zhu, Lin; He, Jining; Yan, Dianran; Liao, Hanlin; Zhang, Nannan

    2017-08-01

    Abstract: As a high-hardness and anti-frictional material, titanium carbonitride (TiCN) thick coatings or thin films are increasingly being used in many industrial fields. In the present study, TiCN coatings were obtained by atmospheric plasma spray synthesis or reactive plasma spray. In order to promote the reaction between the Ti particles and reactive gases, a home-made gas tunnel was mounted on a conventional plasma gun to perform the spray process. The oxidation behavior of the TiCN coatings under different temperatures in static air was carefully investigated. As a result, when the temperature was over 700 °C, the coatings suffered from serious oxidation, and finally they were entirely oxidized to the TiO2 phase at 1100 °C. The principal oxidation mechanism was clarified, indicating that the oxygen can permeate into the defects and react with TiCN at high temperatures. In addition, concerning the use of a TiCN coating in high-temperature conditions, the microhardness of the oxidized coatings at different treatment temperatures was also evaluated.

  10. Electrochemical Impedance Studies on Tribocorrosion Behavior of Plasma-Sprayed Al2O3 Coatings

    Science.gov (United States)

    Liu, Zhe; Chu, Zhenhua; Chen, Xueguang; Dong, Yanchun; Yang, Yong; Li, Yingzhen; Yan, Dianran

    2015-06-01

    In this paper, the tribocorrosion of plasma-sprayed Al2O3 coatings in simulated seawater was investigated by electrochemical impedance spectroscopy (EIS) technique, complemented by scanning electron microscopy to observe the morphology of the tribocorrosion attack. Base on EIS of plasma-sprayed Al2O3 coatings undergoing long-time immersion in simulated seawater, the corrosion process of Al2O3 coatings can be divided into the earlier stage of immersion (up to 20 h) and the later stage (beyond 20 h). Then, the wear tests were carried out on the surface of Al2O3 coating undergoing different times of immersion to investigate the influence of wear on corrosion at different stages. The coexistence of wear and corrosion condition had been created by a boron nitride grinding head rotating on the surface of coatings corroded in simulated seawater. The measured EIS and the values of the fitting circuit elements showed that wear accelerated corrosion at the later stage, meanwhile, corrosion accelerated wear with the immersion time increasing.

  11. PEEK-OPTIMA(™) as an alternative to cobalt chrome in the femoral component of total knee replacement: A preliminary study.

    Science.gov (United States)

    Cowie, Raelene M; Briscoe, Adam; Fisher, John; Jennings, Louise M

    2016-11-01

    PEEK-OPTIMA(™) (Invibio Ltd, UK) has been considered as an alternative joint arthroplasty bearing material due to its favourable mechanical properties and the biocompatibility of its wear debris. In this study, the potential to use injection moulded PEEK-OPTIMA(™) as an alternative to cobalt chrome in the femoral component of a total knee replacement was investigated in terms of its wear performance. Experimental wear simulation of three cobalt chrome and three PEEK-OPTIMA(™) femoral components articulating against all-polyethylene tibial components was carried out under two kinematic conditions: 3 million cycles under intermediate kinematics (maximum anterior-posterior displacement of 5 mm) followed by 3 million cycles under high kinematic conditions (anterior-posterior displacement 10 mm). The wear of the GUR1020 ultra-high-molecular-weight polyethylene tibial components was assessed by gravimetric analysis; for both material combinations under each kinematic condition, the mean wear rates were low, that is, below 5 mm(3)/million cycles. Specifically, under intermediate kinematic conditions, the wear rate of the ultra-high-molecular-weight polyethylene tibial components was 0.96 ± 2.26 mm(3)/million cycles and 2.44 ± 0.78 mm(3)/million cycle against cobalt chrome and PEEK-OPTIMA(™) implants, respectively (p = 0.06); under high kinematic conditions, the wear rates were 2.23 ± 1.85 mm(3)/million cycles and 4.44 ± 2.35 mm(3)/million cycles, respectively (p = 0.03). Following wear simulation, scratches were apparent on the surface of the PEEK-OPTIMA(™) femoral components. The surface topography of the femoral components was assessed using contacting profilometry and showed a statistically significant increase in measured surface roughness of the PEEK-OPTIMA(™) femoral components compared to the cobalt chrome implants. However, this did not appear to influence the wear rate, which remained linear over the

  12. Reactive Plasma-Sprayed Aluminum Nitride-Based Coating Thermal Conductivity

    Science.gov (United States)

    Shahien, Mohammed; Yamada, Motohiro; Fukumoto, Masahiro; Egota, Kazumi; Okamoto, Kenji

    2015-12-01

    Recently, thick aluminum nitride/alumina (AlN/Al2O3) composite coatings were successfully fabricated through the reactive plasma spraying of fine Al2O3/AlN mixture in the N2/H2 atmospheric plasma. The coatings consist of AlN, Al5O6N, γ-Al2O3, and α-Al2O3 phases. This study will evaluate the thermal conductivity of these complicated plasma-sprayed coatings and optimize the controlling aspects. Furthermore, the influence of the process parameters on the coatings thermal conductivity will be investigated. The fabricated coatings showed very low thermal conductivity (2.43 W/m K) compared to the AlN sintered compacts. It is attributed to the phase composition of the fabricated coatings, oxide content, and porosity. The presence of Al2O3, Al5O6N and the high coating porosity decreased its thermal conductivity. The presence of oxygen in the AlN lattice creates Al vacancies which lead to phonon scattering and therefore suppressed the thermal conductivity. The formation of γ-Al2O3 phase in the coating leads to further decrease in its conductivity, due to its lower density compared to the α-phase. Moreover, the high porosity of the coating strongly suppressed the conductivity. This is due to the complicated microstructure of plasma spray coatings (splats, porosity, and interfaces, particularly in case of reactive spray process), which obviously lowered the conductivity. Furthermore, the measured coating density was lower than the AlN value and suppressed the coating conductivity. In addition, the spraying parameter showed a varied effect on the coating phase composition, porosity, density, and therefore on its conductivity. Although the N2 gas flow improved the nitride content, it suppressed the thermal conductivity gradually. It is attributed to the further increase in the porosity and further decrease in the density of the coatings with the N2 gas. Furthermore, increasing the arc did not show a significant change on the coating thermal conductivity. On the other hand

  13. The migration of femoral components after total hip replacement surgery: accuracy and precision of software-aided measurements

    Energy Technology Data Exchange (ETDEWEB)

    Decking, J. [Dept. of Orthopaedic Surgery, Univ. of Mainz School of Medicine, Mainz (Germany); Schuetz, U.; Decking, R.; Puhl, W. [Orthopaedic Dept., Univ. of Ulm, School of Medicine (Germany)

    2003-09-01

    Objective: To assess the accuracy and precision of a software-aided system to measure migration of femoral components after total hip replacement (THR) on digitised radiographs. Design and patients: Subsidence and varus-valgus tilt of THR stems within the femur were measured on digitised anteroposterior pelvic radiographs. The measuring software (UMA, GEMED, Germany) relies on bony landmarks and comparability parameters of two consecutive radiographs. Its accuracy and precision were calculated by comparing it with the gold standard in migration measurements, radiostereometric analysis (RSA). Radiographs and corresponding RSA measurements were performed in 60 patients (38-69 years) following cementless THR surgery. Results and conclusions: The UMA software measured the subsidence of the stems with an accuracy of {+-}2.5 mm and varus-valgus tilt with an accuracy of {+-}1.8 (95% confidence interval). A good interobserver and intraobserver reliability was calculated with Cronbach's alpha ranging from 0.86 to 0.97. Measuring the subsidence of THR stems within the femur is an important parameter in the diagnosis of implant loosening. Software systems such as UMA improve the accuracy of migration measurements and are easy to use on routinely performed radiographs of operated hip joints. (orig.)

  14. Solid oxide fuel cell electrolytes produced via very low pressure suspension plasma spray and electrophoretic deposition

    Science.gov (United States)

    Fleetwood, James D.

    Solid oxide fuel cells (SOFCs) are a promising element of comprehensive energy policies due to their direct mechanism for converting the oxidization of fuel, such as hydrogen, into electrical energy. Both very low pressure plasma spray and electrophoretic deposition allow working with high melting temperature SOFC suspension based feedstock on complex surfaces, such as in non-planar SOFC designs. Dense, thin electrolytes of ideal composition for SOFCs can be fabricated with each of these processes, while compositional control is achieved with dissolved dopant compounds that are incorporated into the coating during deposition. In the work reported, sub-micron 8 mole % Y2O3-ZrO2 (YSZ) and gadolinia-doped ceria (GDC), powders, including those in suspension with scandium-nitrate dopants, were deposited on NiO-YSZ anodes, via very low pressure suspension plasma spray (VLPSPS) at Sandia National Laboratories' Thermal Spray Research Laboratory and electrophoretic deposition (EPD) at Purdue University. Plasma spray was carried out in a chamber held at 320 - 1300 Pa, with the plasma composed of argon, hydrogen, and helium. EPD was characterized utilizing constant current deposition at 10 mm electrode separation, with deposits sintered from 1300 -- 1500 °C for 2 hours. The role of suspension constituents in EPD was analyzed based on a parametric study of powder loading, powder specific surface area, polyvinyl butyral (PVB) content, polyethyleneimine (PEI) content, and acetic acid content. Increasing PVB content and reduction of particle specific surface area were found to eliminate the formation of cracks when drying. PEI and acetic acid content were used to control suspension stability and the adhesion of deposits. Additionally, EPD was used to fabricate YSZ/GDC bilayer electrolyte systems. The resultant YSZ electrolytes were 2-27 microns thick and up to 97% dense. Electrolyte performance as part of a SOFC system with screen printed LSCF cathodes was evaluated with peak

  15. Effect of the thickness on properties of Al{sub 2}O{sub 3} coatings deposited by plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Yin Zhijian [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Tao Shunyan, E-mail: shunyantao@mail.sic.ac.cn [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhou Xiaming [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2011-01-15

    Al{sub 2}O{sub 3} coatings with different thicknesses (160, 320, 480 and 640 {mu}m) were deposited on stainless steel substrate by plasma spraying. The variation in microstructural characteristics and properties of coatings with various thicknesses was investigated. Powders morphology and the microstructure of as-sprayed coatings were characterized by scanning electron microscopy and optical microscopy. The microhardness was measured using a Vickers' indentor. The corrosion behaviour of plasma-sprayed Al{sub 2}O{sub 3} coatings in 1 N H{sub 2}SO{sub 4} solution at a temperature of 25 deg. C was evaluated by electrochemistry method. Experimental results indicated that surface roughness showed no obvious dependence on the coating thickness. However, the porosity of Al{sub 2}O{sub 3} coating was increased with increased thickness. The enhanced coating thickness also resulted in decreasing microhardness and reduced corrosion resistance. In this study, the Al{sub 2}O{sub 3} coating with thickness of 160 {mu}m possesses the lowest porosity, the highest hardness and superior corrosion resistance. Research Highlights: {yields} Increase of coating thickness shows no obvious effect on phase composition and surface roughness of plasma sprayed Al{sub 2}O{sub 3} coatings. {yields} Variation of porosity and microhardness presents dependence on coating thickness parameter. {yields} Increasing coating thickness leads to reduced corrosion resistance of plasma sprayed Al{sub 2}O{sub 3} coating.

  16. Improvement in the properties of plasma-sprayed metallic, alloy and ceramic coatings using dry-ice blasting

    Science.gov (United States)

    Dong, Shujuan; Song, Bo; Hansz, Bernard; Liao, Hanlin; Coddet, Christian

    2011-10-01

    Dry-ice blasting, as an environmental-friendly method, was introduced into atmospheric plasma spraying for improving properties of metallic, alloy and ceramic coatings. The deposited coatings were then compared with coatings plasma-sprayed using conventional air cooling in terms of microstructure, temperature, oxidation, porosity, residual stress and adhesion. It was found that a denser steel or CoNiCrAlY alloy coating with a lower content of oxide can be achieved with the application of dry-ice blasting during the plasma spraying. In addition, the adhesive strength of Al 2O 3 coating deposited with dry-ice blasting exceeded 60 MPa, which was nearly increased by 30% compared with that of the coating deposited with conventional air cooling. The improvement in properties of plasma-sprayed metallic, alloy and ceramic coatings caused by dry-ice blasting was attributed to the decrease of annulus-ringed disk like splats, the better cooling efficiency of dry-ice pellets and even the mechanical effect of dry-ice impact.

  17. Hydroxyapatite coatings deposited by liquid precursor plasma spraying: controlled dense and porous microstructures and osteoblastic cell responses

    Energy Technology Data Exchange (ETDEWEB)

    Huang Yi; Song Lei; Liu Xiaoguang; Xiao Yanfeng; Wu Yao; Chen Jiyong; Wu Fang; Gu Zhongwei, E-mail: fangwu0808@yahoo.co, E-mail: fwu@scu.edu.c [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064 (China)

    2010-12-15

    Hydroxyapatite coatings were deposited on Ti-6Al-4V substrates by a novel plasma spraying process, the liquid precursor plasma spraying (LPPS) process. X-ray diffraction results showed that the coatings obtained by the LPPS process were mainly composed of hydroxyapatite. The LPPS process also showed excellent control on the coating microstructure, and both nearly fully dense and highly porous hydroxyapatite coatings were obtained by simply adjusting the solid content of the hydroxyapatite liquid precursor. Scanning electron microscope observations indicated that the porous hydroxyapatite coatings had pore size in the range of 10-200 {mu}m and an average porosity of 48.26 {+-} 0.10%. The osteoblastic cell responses to the dense and porous hydroxyapatite coatings were evaluated with human osteoblastic cell MG-63, in respect of the cell morphology, proliferation and differentiation, with the hydroxyapatite coatings deposited by the atmospheric plasma spraying (APS) process as control. The cell experiment results indicated that the heat-treated LPPS coatings with a porous structure showed the best cell proliferation and differentiation among all the hydroxyapatite coatings. Our results suggest that the LPPS process is a promising plasma spraying technique for fabricating hydroxyapatite coatings with a controllable microstructure, which has great potential in bone repair and replacement applications.

  18. Anisotropic Mechanical Properties of Plasma-Sprayed Thermal Barrier Coatings at High Temperature Determined by Ultrasonic Method

    Science.gov (United States)

    Wei, Qin; Zhu, Jianguo; Chen, Wei

    2016-02-01

    The mechanical properties of plasma-sprayed thermal barrier coatings (TBC) are of great scientific and technological significance for the design and fabrication of TBC systems. The ultrasonic method combined with a sing-around method for mechanical properties measurement of TBC is deduced and the elastic modulus can be determined in the spray, or longitudinal, direction, and the transverse direction. Tested specimens of plasma-sprayed TBC are detached from the substrate and treated with thermal exposure at 1400 °C. The elastic moduli along the longitudinal and transverse directions of the TBCs are measured by different types of ultrasonic waves combined with a sing-around method, while the Poisson's ratio is also obtained simultaneously. The experimental results indicate that the magnitude of longitudinal elastic modulus is larger than that of the transverse one, and thus the plasma-sprayed TBC has an anisotropic mechanical property. Moreover, the elastic moduli along both longitudinal and transverse directions change with high-temperature exposure time, which consists of a rapid increasing stage followed by a slow decreasing stage. In addition, the magnitude of Poisson's ratio increases slightly from 0.05 to 0.2 with the high-temperature exposure time. Generally, the microstructures in the plasma-sprayed coatings and their evolution in a high-temperature environment are the main causes of the varying anisotropic mechanical properties.

  19. A systematic review on the long-term success of calcium phosphate plasma-spray-coated dental implants

    NARCIS (Netherlands)

    Oirschot, B.A.J.A. van; Bronkhorst, E.M.; Beucken, J.J.J.P van den; Meijer, G.J.; Jansen, J.A.; Junker, R.

    2016-01-01

    The objectives of the current review were (1) to systematically appraise, and (2) to evaluate long-term success data of calcium phosphate (CaP) plasma-spray-coated dental implants in clinical trials with at least 5 years of follow-up. To describe the long-term efficacy of functional implants, the

  20. Reactive Plasma Sprayed TiN Coating and Its Thermal Stability

    Institute of Scientific and Technical Information of China (English)

    ZOU Dong-li; YAN Dian-ran; HE Ji-ning; LI Xiang-zhi; DONG Yan-chun; ZHANG Jian-xin

    2007-01-01

    TiN coating was prepared by reactive plasma spraying in the Ar and N2 containing plasma jet. The results of XRD show that the TiN coating consists of TiN and Ti3O, neither Ti2N nor TiO2 phases. The toughening mechanism was characterized by analyzing the SEM morphologies of the TiN coating's indentation of microhardness and fracture surfaces. The results indicate that the coating possesses a high toughness. The adhesion strength among the TiN layers is 25.88 MPa, which is slightly lower than that of the Ni/Al bonding coating. The oxidation process of the RPS TiN coating is TiN→Ti3O→TiO2.

  1. Friction of tungsten carbide-cobalt coatings obtained by means of plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Cartier, M. (Hydromecanique et Frottement, Centre de Recherches, 42 - Andreziux-Boutheon (France)); McDonnell, L.; Cashell, E.M. (CRTC, Cork (Ireland))

    1991-11-29

    A study of the frictional properties of WC-Co-type coatings obtained by plasma spraying was carried out, the influence of the majority of the parameters involved in atmospheric spraying being analysed. This study of the correlations between the tribological behaviour and the compositionl of the coatings shows that friction is mainly determined by the method and degree of decomposition of the carbides. These in turn are linked to the effects of heat and/or oxidation, factors which can change considerably, not only as a function of the method used (plasma power, nature and flow rate of the plasma gases etc.) but also as a function of the coating process and the composition of the original powders. It has been possible to correlate the improvement in the frictional properties (resistance to seizure, reduction in the coefficient of friction) with the presence of free carbon in the coatings, associated with the carbide decomposition process. (orig.).

  2. Preparation and Properties of Plasma Spraying Cu-Al2O3 Gradient Coatings

    Institute of Scientific and Technical Information of China (English)

    Ali LEI; Nan DONG; Lajun FENG

    2007-01-01

    In order to overcome the limitations of low adhesion strength and poor thermal-shock resistance of pure ceramic coatings, Cu-Al2O3 gradient coatings were fabricated by plasma spraying. The microstructure and distribution of Cu-Al2O3 gradient coatings were analyzed. The adhesion strength, thermal-shock resistance and porosity of the coatings were tested. The results show that the composition of the gradient coatings has a gradient distribution along the thickness of coatings. As copper has a relatively low melting point and the molten copper has good wettability on the surface of Al2O3, it can be melted sufficiently and could fill the interstices and pores among the spraying particles effectively, thus improves the adhesion strength, thermal shock resistance and reduces the porosity. The adhesion strength of the gradient coating is 15.2 MPa which is two times of that of the double-layer structure coating.

  3. Mechanical Properties of Air Plasma Sprayed Environmental Barrier Coating (EBC) Materials

    Science.gov (United States)

    Richards, Bradley; Zhu, Dongming; Ghosn, Louis; Wadley, Haydn

    2015-01-01

    Development work in Environmental Barrier Coatings (EBCs) for Ceramic Matrix Composites (CMCs) has focused considerably on the identification of materials systems and coating architectures to meet application needs. The evolution of these systems has occurred so quickly that modeling efforts and requisite data for modeling lag considerably behind development. Materials property data exists for many systems in the bulk form, but the effects of deposition on the critical properties of strength and fracture behavior are not well studied. We have plasma sprayed bulk samples of baseline EBC materials (silicon, ytterbium disilicate) and tested the mechanical properties of these materials to elicit differences in strength and toughness. We have also endeavored to assess the mixed-mode fracture resistance, Gc, of silicon in a baseline EBC applied to SiCSiC CMC via four point bend test. These results are compared to previously determined properties of the comparable bulk material.

  4. Deposition of titanium nitride and hydroxyapatite-based biocompatible composite by reactive plasma spraying

    Science.gov (United States)

    Roşu, Radu Alexandru; Şerban, Viorel-Aurel; Bucur, Alexandra Ioana; Dragoş, Uţu

    2012-02-01

    Titanium nitride is a bioceramic material successfully used for covering medical implants due to the high hardness meaning good wear resistance. Hydroxyapatite is a bioactive ceramic that contributes to the restoration of bone tissue, which together with titanium nitride may contribute to obtaining a superior composite in terms of mechanical and bone tissue interaction matters. The paper presents the experimental results in obtaining composite layers of titanium nitride and hydroxyapatite by reactive plasma spraying in ambient atmosphere. X-ray diffraction analysis shows that in both cases of powders mixtures used (10% HA + 90% Ti; 25% HA + 75% Ti), hydroxyapatite decomposition occurred; in variant 1 the decomposition is higher compared with the second variant. Microstructure of the deposited layers was investigated using scanning electron microscope, the surfaces presenting a lamellar morphology without defects such as cracks or microcracks. Surface roughness values obtained vary as function of the spraying distance, presenting higher values at lower thermal spraying distances.

  5. Behavior of Plasma-Sprayed Hydroxyapatite Coatings onto Carbon/carbon Composites in Simulated Body Fluid

    Science.gov (United States)

    Sui, Jin-Ling; Bo, Wu; Hai, Zhou; Cao, Ning; Li, Mu-Sen

    Two types of hydroxyapatite (HA) coatings onto carbon/carbon composite (C/C composites) substrates, deposited by plasma spraying technique, were immersed in a simulated body fluid (SBF) in order to determine their behavior in conditions similar to the human blood plasma. Calcium ion concentration, pH value, microstructure, and phase compositions were analyzed. Results demonstrated that both the crystal Ca-P phases or the amorphous HA do dissolve slightly, and the dissolution of CaO phases in SBF was evident after 1 day of soaking. The calcium-ion concentration was decreased and the pH value of SBF was increased with the increasing of the immersing time. The precipitation was mainly composed of HA, which was verified by X-ray diffraction (XRD) and electron-probe microanalyzer.

  6. Investigation on in-flight particle velocity in supersonic plasma spraying

    Institute of Scientific and Technical Information of China (English)

    Li Changqing; Ma Shining; Ye Xionglin

    2005-01-01

    In-flight particle velocity and flux distribution were measured using CCD thermal spray monitor system during supersonic plasma spray processing with nano-structured Al203-TiO2 feed stocks. According to the results of particle flux measurement, the largest radian of the divergent particle stream is about 0. 2. Within the measuring range, top speed of inflight particles reached 800 m/s. Particle acceleration was accomplished within 4 cm down stream of the nozzle. Average particle velocity ( about 450 m/s) exceeded local sound speed (340 m/s) even at a mean standoff distance of 17 cm. With increasing mean standoff distance, average velocity of in-flight particle decreased according to a parabolic rule approximately.Image diagnosis showed that the result of in-flight particle velocity measurement is credible.

  7. The Main Issues to Address in Modeling Plasma Spray Torch Operation

    Science.gov (United States)

    Chazelas, C.; Trelles, J. P.; Vardelle, A.

    2017-01-01

    The modeling of plasma torch operation has advanced greatly in the last 15 years due to a better understanding of the underlying physics, development of commercial, open-source computational fluid dynamics softwares, and access to high performance and cloud computing. However, the operation mode of the electric arc in plasma torches is controlled by dynamic, thermal, electromagnetic, acoustic and chemical phenomena that take place at different scales and whose interactions are not completely understood yet. Even though no single model of plasma torch operation fully addresses these phenomena, most of these models are useful tools for parametric studies, if their use is reinforced by knowledge of torch operation and the model predictions are validated against experimental data. To increase the level of predictability of the current models, several further steps are needed. This study examines the issues remaining to be addressed in the modeling of plasma spray torch operation and the current critical aspects of these.

  8. Understanding plasma spraying process and characteristics of DC-arc plasma gun (PJ-100

    Directory of Open Access Journals (Sweden)

    Jovana Ružić

    2012-12-01

    Full Text Available The thermal spray processes are a group of coating processes used to apply metallic or non-metallic coatings. In these processes energy sources are used to heat the coating material (in the form of powder, wire, or rod form to a molten or semi-molten state and accelerated towards a prepared surface by either carrier gases or atomization jets. In plasma spraying process, the spraying material is generally in the form of powder and requires a carrier gas to feed the powder into the plasma jet, which is passing between the hot cathode and the cylindrical nozzle-shaped anode. The design of DC plasma gun (PJ - 100 is designed and manufactured in Serbia. Plasma spaying process, the powder injection with the heat, momentum and mass transfers between particles and plasma jet, and the latest developments related to the production of DC plasma gun are described in this article.

  9. Nanocomposite Lanthanum Zirconate Thermal Barrier Coating Deposited by Suspension Plasma Spray Process

    Science.gov (United States)

    Wang, Chaohui; Wang, You; Wang, Liang; Hao, Guangzhao; Sun, Xiaoguang; Shan, Fan; Zou, Zhiwei

    2014-10-01

    This work seeks to develop an innovative nanocomposite thermal barrier coating (TBC) exhibiting low thermal conductivity and high durability compared with that of current TBCs. To achieve this objective, nanosized lanthanum zirconate particles were selected for the topcoat of the TBC system, and a new process—suspension plasma spray—was employed to produce desirable microstructural features: the nanocomposite lanthanum zirconate TBC contains ultrafine splats and high volume porosity, for lower thermal conductivity, and better durability. The parameters of plasma spray experiment included two main variables: (i) spray distance varying from 40 to 80 mm and (ii) the concentration of suspension 20, 25, and 30 wt.%, respectively. The microstructure of obtained coatings was characterized with scanning electron microscope and x-ray diffraction. The porosity of coatings is in the range of 6-10%, and the single phase in the as-sprayed coatings was pyrochlore lanthanum zirconate.

  10. Post-treatment of Plasma-Sprayed Amorphous Ceramic Coatings by Spark Plasma Sintering

    Science.gov (United States)

    Chraska, T.; Pala, Z.; Mušálek, R.; Medřický, J.; Vilémová, M.

    2015-04-01

    Alumina-zirconia ceramic material has been plasma sprayed using a water-stabilized plasma torch to produce free standing coatings. The as-sprayed coatings have very low porosity and are mostly amorphous. The amorphous material crystallizes at temperatures above 900 °C. A spark plasma sintering apparatus has been used to heat the as-sprayed samples to temperatures above 900 °C to induce crystallization, while at the same time, a uniaxial pressure of 80 MPa has been applied to their surface. After such post-treatment, the ceramic samples are crystalline and have very low open porosity. The post-treated material exhibits high hardness and significantly increased flexural strength. The post-treated samples have a microstructure that is best described as nanocomposite with the very small crystallites embedded in an amorphous matrix.

  11. Characteristics of Plasma-Sprayed Ceramic Coatings and Their Engineering Application

    Institute of Scientific and Technical Information of China (English)

    DENG Hua-ling; ZHANG Zhong-wen; WU Jun

    2004-01-01

    The microstructure, porosity, microhardness and adhesive strength of three plasma- sprayed ceramic coatings (Al2 O3, Cr2 O3 and Cr3 C2 + NiCr) were tested. The wear resistance of the coatings was characterized through sand blasting test. The results showed that the erosion resistance of Cr2 O3 coating was better than Al2 O3 and Cr3 C2 + NiCr coatings'.Through depositing the coating on the surface of boiler overheater tubes and on the surface of baffle- wall of carrying- coal grain blower to test its anti- erosion performance after a period of running, it was confirmed that the coatings present excellent wear resistance. Accordingly, it also demonstrates that ceramic coating has a promising prospects in surface protection in thermal power stations.

  12. Impacts of friction stir processing on irradiation effects in vacuum-plasma-spray coated tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, Kazumi, E-mail: ozawa.kazumi@jaea.go.jp [Fusion Research and Development Directorate, Japan Atomic Energy Agency, 2-166 Obuchi-Omotedate, Rokkasho, Aomori 039-3212 (Japan); Tanigawa, Hiroyasu [Fusion Research and Development Directorate, Japan Atomic Energy Agency, 2-166 Obuchi-Omotedate, Rokkasho, Aomori 039-3212 (Japan); Morisada, Yoshiaki; Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2015-10-15

    In order to examine the impacts of friction stir processing (FSP) on irradiation effects in vacuum-plasma-spray (VPS) coated tungsten (W), nano indentation hardness was evaluated of three kinds of W materials after self-ion-irradiation to 5.0–5.4 dpa at 500 and 800 °C. The VPS-FSP clearly got grains refined and isotropic compared to bulk-W and the as-VPS-W. Nano indentation hardness remains unchanged for the as-VPS-W and VPS-FSP × 2-W irradiated to 5.4 dpa at 500 °C and it decreased from 1 dpa at 800 °C, while typical irradiation induced hardening was observed for the bulk-W irradiated at 500 °C.

  13. Determination of the Mechanical Properties of Plasma-Sprayed Hydroxyapatite Coatings Using the Knoop Indentation Technique

    Science.gov (United States)

    Hasan, Md. Fahad; Wang, James; Berndt, Christopher

    2015-06-01

    The microhardness and elastic modulus of plasma-sprayed hydroxyapatite coatings were evaluated using Knoop indentation on the cross section and on the top surface. The effects of indentation angle, testing direction, measurement location and applied load on the microhardness and elastic modulus were investigated. The variability and distribution of the microhardness and elastic modulus data were statistically analysed using the Weibull modulus distribution. The results indicate that the dependence of microhardness and elastic modulus on the indentation angle exhibits a parabolic shape. Dependence of the microhardness values on the indentation angle follows Pythagoras's theorem. The microhardness, Weibull modulus of microhardness and Weibull modulus of elastic modulus reach their maximum at the central position (175 µm) on the cross section of the coatings. The Weibull modulus of microhardness revealed similar values throughout the thickness, and the Weibull modulus of elastic modulus shows higher values on the top surface compared to the cross section.

  14. The Structure and Behavior of Vacuum Plasma Sprayed Overlay Coatings on Nickel Based Superalloys.

    Science.gov (United States)

    1983-06-01

    the oxide -1c the coating. SEA, 85 deg. tilt, 5000X B.30 Dee etched NiCrAl with La which shows no . . 45 uicfc-peg formation. S2, 85 deg. tilt, 50001...34 - ’. . - - .. ., - . . - . - ., . - " - ’ .. . ’ . . - - - . . - . 3:11. IIIULU. An ID PL SM2 ,I- 10 iINSOLIZS .U ainUSUL! ’,’ a. Vendor "IN The structures of both the NiCrAl and CcCrAl type...surface and loose particles exhibited by a pl~asma sprayed NiCrAl cocit.ng. * SEE, 1000X Figure B.13 Plasma s Frayed coating by Vendor "B" with low ir

  15. Investigation of Plasma Spray Coatings as an Alternative to Hard Chrome Plating on Internal Surfaces

    Science.gov (United States)

    2006-09-14

    alloy Ni-988 Praxair WC-Co self fluxing 50%(WC 12Co) 50%(33Ni 9Cr 3.5Fe 2Si 2B 0.5C) SM 5803 Sulzer Metco (WC 12Co) 25(Ni-Based Superalloy ) SM...Micro Hardness [HV0.3] Cracks 10012402-1 SM 5803 (WC 12Co) 25(Ni-Based Superalloy ) Ar/He/H2 5.3 82.2 671 Micro cracks 10012502-1 D2002 (WC...o n V o lu m e L o ss ( m m 3 ) Figure 4-28. Abrasion resistance of EHC and plasma spray coatings. Ring Coated (block) disc Figure

  16. Titanium carbonitride thick coating prepared by plasma spray synthesis and its tribological properties

    Institute of Scientific and Technical Information of China (English)

    ZHU Lin; HE JiNing; YAN DianRan; XIAO LiSong; DONG YanChun; XUE DingChuan; MENG DeLiang

    2007-01-01

    TiCN coating,owing to its superior wear-resistance,has been frequently applied in many fields. TiCN thick coating was first prepared by reactive plasma spraying. The phase composition,microstructure and tribological properties of the TiCN coating were investigated in this research. Experimental results show that the microstructure of the TiCN coating was quite dense,and there was also a little amount of titanium oxides within the coating. By XPS analysis,Ti-C and Ti-N bonds were detected in the coating. The TiCN coating exhibited superior wear-resistance. The failure mechanism was attributed to the adhesive wear,the grinding of TiCN hard-grain,as well as the coating failure by oxidation. There were more Fe,Cr,O,etc. in the failure zone,suggesting that the corrosion propagated gradually from surface to interior.

  17. Preparation and characterization of molybdenum disilicide coating on molybdenum substrate by air plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Wang, Dezhi, E-mail: dzwang68@163.com [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Yan, Jianhui [Advanced Materials Synthesis and Application Technology Laboratory, Hunan University of Science and Technology, Xiangtan 411201 (China); Sun, Aokui [Key Laboratory of Ministry of Education for Non-ferrous Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Hunan Province for Metallurgy and Material Processing of Rare Metals, Central South University, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Changsha 410083 (China)

    2013-11-01

    MoSi{sub 2} oxidation protective coatings on molybdenum substrate were prepared by air plasma spraying technique (APS). Microstructure, phase composition, porosity, microhardness and bonding strength of the coatings were investigated and determined. Oxidation behavior of the coating at high temperature was also examined. Results show that composition of the coatings is constituted with MoSi{sub 2} and Mo{sub 5}Si{sub 3}, the surface morphology is described as flattened lamellar features, insufficiently flattened protuberance with some degree of surface roughness, a certain quantity of spherical particles, microcracks and pores. Testing results reveal that microhardness and bonding strength of the coatings increase, and porosity decreases with increasing power or decreasing Ar gas flow rate. Moreover, with decreasing the porosity, the microhardness of the coatings increases. The bonding strength of the coatings also increases with increasing spray distance. The MoSi{sub 2} coated Mo substrate exhibited a good oxidation resistance at 1200 °C.

  18. Repulsive Interaction of Sulfide Layers on Compressor Impeller Blades Remanufactured Through Plasma Spray Welding

    Science.gov (United States)

    Chang, Y.; Zhou, D.; Wang, Y. L.; Huang, H. H.

    2016-12-01

    This study investigated the repulsive interaction of sulfide layers on compressor impeller blades remanufactured through plasma spray welding (PSW). Sulfide layers on the blades made of FV(520)B steel were prepared through multifarious corrosion experiments, and PSW was utilized to remanufacture blade specimens. The specimens were evaluated through optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, 3D surface topography, x-ray diffraction, ImageJ software analysis, Vicker's micro-hardness test and tensile tests. Results showed a large number of sulfide inclusions in the fusion zone generated by sulfide layers embodied into the molten pool during PSW. These sulfide inclusions seriously degraded the mechanical performance of the blades remanufactured through PSW.

  19. Comparative Evaluation of Osseointegration of Dental Endodontic Implants with and without Plasma- Sprayed Hydroxy apatite Coating

    Directory of Open Access Journals (Sweden)

    Moosavi SB

    2001-05-01

    Full Text Available Bone osseointegration around dental implant can cause earlier stabilization and fixation of implant and reduce healing time. Hydroxyapatite coating can affect bone osseointegration and enhance its rates. The aim of this study was comparison of osseointegration between plasma sprayed hydroxyapatite coated and uncoated dental implants in cats. Four endodontic implants including, vitallium and two stainless steel with and without hydroxyapatite coating were prepared and placed in mandibular canines of 20 cats after completion of root canal treatment and osseous preparation. After a healing period of 4 months, investigation by scanning electron microscopy showed significant difference in ossointegration between coated and uncoated dental implants and average bone osseointegration of coated implants was more than uncoated implants.

  20. Tungsten carbide coatings with different binders prepared by low power plasma spray system

    Institute of Scientific and Technical Information of China (English)

    GAO Yang; M.F.Morks; FU Ying-qing

    2004-01-01

    Thermal spraying of cermet coatings is widely used for protection of machining parts against wear and corrosion. These coatings consist of WC particles in metal binders such as Co, Cr and Ni. Three kinds of WC powders with different metal binders (Co, NiCr and CoCr) were sprayed by low power plasma spray system on Al-Si-Cu alloy substrate. Fundamental aspects of sprayed cermet coatings, including (i) the effects of binder type on the coating structure, (ii) the hardness and (iii) the microstructure, were investigated. All cermet coatings have the same phase structure such as WC and W2 C. However, the intensities of these phases are different in each coating, mainly due to the difference in solidification rate in each case. Moreover, the hardness measurements are found to be different in each coating. The results show that, binder type has a significant effect on the physical and mechanical properties of the sprayed coatings.

  1. Life Prediction of Atmospheric Plasma-Sprayed Thermal Barrier Coatings Using Temperature-Dependent Model Parameters

    Science.gov (United States)

    Zhang, B.; Chen, Kuiying; Baddour, N.; Patnaik, P. C.

    2017-06-01

    The failure analysis and life prediction of atmospheric plasma-sprayed thermal barrier coatings (APS-TBCs) were carried out for a thermal cyclic process. A residual stress model for the top coat of APS-TBC was proposed and then applied to life prediction. This residual stress model shows an inversion characteristic versus thickness of thermally grown oxide. The capability of the life model was demonstrated using temperature-dependent model parameters. Using existing life data, a comparison of fitting approaches of life model parameters was performed. A larger discrepancy was found for the life predicted using linearized fitting parameters versus temperature compared to those using non-linear fitting parameters. A method for integrating the residual stress was proposed by using the critical time of stress inversion. The role of the residual stresses distributed at each individual coating layer was explored and their interplay on the coating's delamination was analyzed.

  2. Corrosion at the head-neck interface of current designs of modular femoral components: essential questions and answers relating to corrosion in modular head-neck junctions.

    Science.gov (United States)

    Osman, K; Panagiotidou, A P; Khan, M; Blunn, G; Haddad, F S

    2016-05-01

    There is increasing global awareness of adverse reactions to metal debris and elevated serum metal ion concentrations following the use of second generation metal-on-metal total hip arthroplasties. The high incidence of these complications can be largely attributed to corrosion at the head-neck interface. Severe corrosion of the taper is identified most commonly in association with larger diameter femoral heads. However, there is emerging evidence of varying levels of corrosion observed in retrieved components with smaller diameter femoral heads. This same mechanism of galvanic and mechanically-assisted crevice corrosion has been observed in metal-on-polyethylene and ceramic components, suggesting an inherent biomechanical problem with current designs of the head-neck interface. We provide a review of the fundamental questions and answers clinicians and researchers must understand regarding corrosion of the taper, and its relevance to current orthopaedic practice. Cite this article: Bone Joint J 2016;98-B:579-84.

  3. Study of the characteristics of plasma spray sealing aluminum silicon-polyester coatings

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2012-07-01

    Full Text Available This study shows the homologation of the plasma spray parameters of soft abrasive AlSi - Polyester seals so that they can be applied on the TV2 - 117A compressor engines. The research has aimed at substituting existing sealants with a new class of materials in order to increase the sealing effect under the highest levels of pressure and to provide the air flow temperature of 100-125°C through the compressor. The Metco 601NS material and plasma spray technology were applied on the air labyrinth ring as a part of the TV2-117A turbojet engine compressor in order to obtain soft sealing. The deposit parameters were carefully selected in order to obtain coatings with the best characteristics depending on their application.The flow of helium was taken as a basic parameter in the parameter selection procedure. The coating with the best mechanical and structural properties was deposited on the air labyrinth ring to examine the effect of the coating application in an assembly. The microstructures of deposited layers were estimated with a light microscope and a (SEM Scanning Electron Microscope. The microstructural analysis of deposited layers was performed according to the Pratt - Whitney standard. The assessment of the mechanical properties of the coatings was done by examining the macrohardness of the sealing layers with the HR15Y method. The coating bond strength was tested by tensile testing. The effect of the air labyrinth ring sealing was tested inside the TV2-117A engine compressor on the test station for a period of 42 hour.

  4. Nanostructured bioactive glass-ceramic coatings deposited by the liquid precursor plasma spraying process

    Science.gov (United States)

    Xiao, Yanfeng; Song, Lei; Liu, Xiaoguang; Huang, Yi; Huang, Tao; Wu, Yao; Chen, Jiyong; Wu, Fang

    2011-01-01

    Bioactive glass-ceramic coatings have great potential in dental and orthopedic medical implant applications, due to its excellent bioactivity, biocompatibility and osteoinductivity. However, most of the coating preparation techniques either produce only thin thickness coatings or require tedious preparation steps. In this study, a new attempt was made to deposit bioactive glass-ceramic coatings on titanium substrates by the liquid precursor plasma spraying (LPPS) process. Tetraethyl orthosilicate, triethyl phosphate, calcium nitrate and sodium nitrate solutions were mixed together to form a suspension after hydrolysis, and the liquid suspension was used as the feedstock for plasma spraying of P 2O 5-Na 2O-CaO-SiO 2 bioactive glass-ceramic coatings. The in vitro bioactivities of the as-deposited coatings were evaluated by soaking the samples in simulated body fluid (SBF) for 4 h, 1, 2, 4, 7, 14, and 21 days, respectively. The as-deposited coating and its microstructure evolution behavior under SBF soaking were systematically analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma (ICP), and Fourier transform infrared (FTIR) spectroscopy. The results showed that P 2O 5-Na 2O-CaO-SiO 2 bioactive glass-ceramic coatings with nanostructure had been successfully synthesized by the LPPS technique and the synthesized coatings showed quick formation of a nanostructured HCA layer after being soaked in SBF. Overall, our results indicate that the LPPS process is an effective and simple method to synthesize nanostructured bioactive glass-ceramic coatings with good in vitro bioactivity.

  5. Effect of steam treatment during plasma spraying on the microstructure of hydroxyapatite splats and coatings

    Science.gov (United States)

    Li, H.; Khor, K. A.; Cheang, P.

    2006-12-01

    The major problems with plasma sprayed hydroxyapatite (HA) coatings for hard tissue replacement are severe HA decomposition and insufficient mechanical properties of the coatings. Loss of crystalline HA after the high-temperature spraying is due mainly to the loss of OH- in terms of water. The current study used steam to treat HA droplets and coatings during both in-flight and flattening stages during plasma spraying. The microstructure of the HA coatings and splats was characterized using scanning electron microscope, Raman spectroscopy, Fourier transform IR spectroscopy, and x-ray diffraction. Results showed that a significant increase in crystallinity of the HA coating was achieved through the steam treatment (e.g., from 58 to 79%). In addition, the effects were dependent on particle sizes of the HA feedstock, more increase in crystallinity of the coatings made from smaller powders was revealed. The Raman spectroscopy analyses on the individual splats and coatings indicate that the mechanism involves entrapping of water molecules by the individual HA droplets upon their impingement. It further suggests that the HA decomposition has already taken place before the impingement of the droplets on precoating or substrate. The improvement in crystallinity and phases, for example, from tricalcium phosphate and amorphous calcium phosphate to HA, was achieved by reversing the HA decomposition through providing extra OH-. Furthermore, the steam treatment during the spraying also accounts for remarkably increased adhesion strength from 9.09 to 23.13 MPa. The in vitro testing through immersing the HA coatings in simulated body fluid gives further evidence that the economic and simple steam treatment is promising in improving HA coating structure.

  6. Effect of Processing Conditions on the Anelastic Behavior of Plasma Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Viswanathan, Vaishak

    2011-12-01

    Plasma sprayed ceramic materials contain an assortment of micro-structural defects, including pores, cracks, and interfaces arising from the droplet based assemblage of the spray deposition technique. The defective architecture of the deposits introduces a novel "anelastic" response in the coatings comprising of their non-linear and hysteretic stress-strain relationship under mechanical loading. It has been established that this anelasticity can be attributed to the relative movement of the embedded defects under varying stresses. While the non-linear response of the coatings arises from the opening/closure of defects, hysteresis is produced by the frictional sliding among defect surfaces. Recent studies have indicated that anelastic behavior of coatings can be a unique descriptor of their mechanical behavior and related to the defect configuration. In this dissertation, a multi-variable study employing systematic processing strategies was conducted to augment the understanding on various aspects of the reported anelastic behavior. A bi-layer curvature measurement technique was adapted to measure the anelastic properties of plasma sprayed ceramic. The quantification of anelastic parameters was done using a non-linear model proposed by Nakamura et.al. An error analysis was conducted on the technique to know the available margins for both experimental as well as computational errors. The error analysis was extended to evaluate its sensitivity towards different coating microstructure. For this purpose, three coatings with significantly different microstructures were fabricated via tuning of process parameters. Later the three coatings were also subjected to different strain ranges systematically, in order to understand the origin and evolution of anelasticity on different microstructures. The last segment of this thesis attempts to capture the intricacies on the processing front and tries to evaluate and establish a correlation between them and the anelastic

  7. Comparative study of material loss at the taper interface in retrieved metal-on-polyethylene and metal-on-metal femoral components from a single manufacturer.

    Science.gov (United States)

    Bills, Paul; Racasan, Radu; Bhattacharya, Saugatta; Blunt, Liam; Isaac, Graham

    2017-04-01

    There have been a number of reports on the occurrence of taper corrosion and/or fretting and some have speculated on a link to the occurrence of adverse local tissue reaction specifically in relation to total hip replacement which have a metal-on-metal bearing. As such a study was carried out to compare the magnitude of material loss at the taper in a series of retrieved femoral heads used in metal-on-polyethylene bearings with that in a series of retrieved heads used in metal-on-metal bearings. A total of 36 metal-on-polyethylene and 21 metal-on-metal femoral components were included in the study all of which were received from a customer complaint database. Furthermore, a total of nine as-manufactured femoral components were included to provide a baseline for characterisation. All taper surfaces were assessed using an established corrosion scoring method and measurements were taken of the female taper surface using a contact profilometry. In the case of metal-on-metal components, the bearing wear was also assessed using coordinate metrology to determine whether or not there was a relationship between bearing and taper material loss in these cases. The study found that in this cohort the median value of metal-on-polyethylene taper loss was 1.25 mm(3) with the consequent median value for metal-on-metal taper loss being 1.75 mm(3). This study also suggests that manufacturing form can result in an apparent loss of material from the taper surface determined to have a median value of 0.59 mm(3). Therefore, it is clear that form variability is a significant confounding factor in the measurement of material loss from the tapers of femoral heads retrieved following revision surgery.

  8. Assessment of plasma sprayed coatings to modify surface friction for railroad applications

    Science.gov (United States)

    Davis, Heidi Lynn

    For the past hundred years, railroads have been an important means of transportation for passengers and freight. Over the years train traffic, speeds, and loads have increased steadily leading to a more severe wheel/rail environment that exceeds the design limits of the steels thus causing increased wear, decreased rail life, and higher maintenance costs. The cost of controlling friction and the resulting damage is an area of ever-increasing concern. One potential method of modifying friction is by changing the surface properties of the rail. The work reported herein was carried out as part of a larger effort to modify surface friction of rails. The original focus of this research was to use high velocity air plasma spraying to develop friction enhancing coatings for the rail surface. Using the methodology developed at the Oregon Graduate Institute, the plasma spray parameters were optimized and the coatings were tested on the Amsler machine under rolling/sliding wear conditions to determine viability prior to full scale testing. Stainless steel and composite 1080 steel were investigated as potential materials for increasing friction. Poor results with these coatings shifted the research focus to understanding the durability of the coatings and to failure analysis of initial 1080 steel full scale samples tested by the Facility for Accelerated Service Testing that had failed prematurely. After re-optimization of parameters and preparation methodologies further full scale samples (1080 steel/nylon) were tested and failure analysis was performed. Optical and scanning electron microscopy were used to evaluate the microstructure of coatings from the tested samples. The laboratory scale Amsler test did not appear to be a good indicator of the performance of the coating in full scale tests, because variations in microstructure were caused by differences in sample size, geometry and spraying methods when scaling up from a small Amsler roller to a large rail sample. The

  9. Simulation on change of generic satellite radar cross section via artificially created plasma sprays

    Science.gov (United States)

    Chung, Shen Shou Max; Chuang, Yu-Chou

    2016-06-01

    Recent advancements in antisatellite missile technologies have proven the effectiveness of such attacks, and the vulnerability of satellites in such exercises inspires a new paradigm in RF Stealth techniques suitable for satellites. In this paper we examine the possibility of using artificially created plasma sprays on the surface of the satellite’s main body to alter its radar cross section (RCS). First, we briefly review past research related to RF Stealth using plasma. Next, we discuss the physics between electromagnetic waves and plasma, and the RCS number game in RF Stealth design. A comparison of RCS in a generic satellite and a more complicated model is made to illustrate the effect of the RCS number game, and its meaning for a simulation model. We also run a comparison between finite-difference-time-domain (FDTD) and multilevel fast multipole method (MLFMM) codes, and find the RCS results are very close. We then compare the RCS of the generic satellite and the plasma-covered satellite. The incident radar wave is a differentiated Gaussian monopulse, with 3 dB bandwidth between 1.2 GHz and 4 GHz, and we simulate three kinds of plasma density, with a characteristic plasma frequency ω P  =  0.1, 1, and 10 GHz. The electron-neutral collision frequency ν en is set at 0.01 GHz. We found the RCS of plasma-covered satellite is not necessarily smaller than the originally satellite. When ω P is 0.1 GHz, the plasma spray behaves like a dielectric, and there is minor reduction in the RCS. When ω P is 1 GHz, the X-Y cut RCS increases. When ω P is 10 GHz, the plasma behaves more like a metal to the radar wave, and stronger RCS dependency to frequency appears. Therefore, to use plasma as an RCS adjustment tool requires careful fine-tuning of plasma density and shape, in order to achieve the so-called plasma stealth effect.

  10. On the Anelastic Behavior of Plasma Sprayed Ceramic Coatings: Observations, Characterizations and Applications

    Science.gov (United States)

    Dwivedi, Gopal

    Plasma sprayed ceramic materials contain an assortment of microstructural defects, including pores, cracks, and interfaces arising from the droplet based assemblage of the spray deposition technique. The defective architecture of the deposits introduces a novel "anelastic" response in the coatings comprising of their non-linear and hysteretic stress-strain relationship under mechanical loading. It has been established that this anelasticity can be attributed to the relative movement of the embedded defects under varying stresses; while the non-linear response of the coatings arises from the opening/closure of defects, hysteresis is produced by the frictional sliding among defect surfaces. Recent studies have indicated that anelastic behavior of coatings can be a unique descriptor of their mechanical behavior and related to the defect configuration. In this dissertation, a multi-variable study employing systematic processing strategies was conducted to augment the understanding on various aspects of the reported anelastic behavior. Enhancements to bi-layer curvature measurement technique allowed for reliable and repeatable quantification of the anelastic response, enabling extraction of three anelastic parameters; elastic modulus, non-linear degree and hysteresis degree. This allowed for further exploration of the process space enabling controlled introduction of anelasticity in thermal sprayed ceramic coatings. This dissertation reports on these findings by first describing the experimental advancements in bilayer curvature measurements via thermal cycling of a coated beam. This experimental development allowed assessment of sensitivity and repeatability of the obtained anelastic parameters to varying microstructures imposed by processing excursions. Subsequently, controlled modification of anelasticity was achieved through material and process parameters as well as through extrinsic modification of the defects within the microstructure. The results suggest that

  11. Initial phase hot corrosion mechanism of gas tunnel type plasma sprayed thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Yugeswaran, S. [Joining and Welding Research Institute, Osaka University, Osaka 567-0047 (Japan); Kobayashi, A., E-mail: kobayasi@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, Osaka 567-0047 (Japan); Ananthapadmanabhan, P.V. [L and PT Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2012-04-25

    Highlights: Black-Right-Pointing-Pointer Free standing TBC specimens were prepared by gas tunnel type plasma spraying with thickness of around 300-400 {mu}m. Black-Right-Pointing-Pointer 50%8YSZ + 50%La{sub 2}Zr{sub 2}O{sub 7} composite coating shows superior hot corrosion resistance. Black-Right-Pointing-Pointer Corrosive crystals structure and phase transformation was well controlled in this coating. - Abstract: The hot corrosion resistance of the top layer in TBC is one of the main constructive factors which determines the lifetime of the coatings under critical operating environments. In the present study, 8 wt% yttria stabilized zirconia (8YSZ), lanthanum zirconate (La{sub 2}Zr{sub 2}O{sub 7}) and equal weight percentage of its composite (50%8YSZ + 50% La{sub 2}Zr{sub 2}O{sub 7}) coatings were prepared by using gas tunnel type plasma spray torch at optimum spraying conditions. The hot corrosion performances of the above thermal barrier coatings were examined against 40 wt%V{sub 2}O{sub 5}-60 wt%Na{sub 2}SO{sub 4} corrosive ash at 1173 K for 5 h in open air atmosphere. After hot-corrosion testing, the coating surface was studied using a scanning electron microscope to observe the microstructure and X-ray diffraction techniques were used to identify the phase compositions. The results showed that LaVO{sub 4} and YVO{sub 4} are the main hot corrosion products along with the ZrO{sub 2} phase transformation from tetragonal to monoclinic phases in La{sub 2}Zr{sub 2}O{sub 7} and 8YSZ coatings respectively. The microstructure and phase formation mechanism of the hot corrosion products varied with each coating and among these, composition of 50%8YSZ + 50%La{sub 2}Zr{sub 2}O{sub 7} coating exhibited least degradation against V{sub 2}O{sub 5}-Na{sub 2}SO{sub 4} corrosive environment compared to the other coatings.

  12. Femoral bowing plane adaptation to femoral anteversion

    Directory of Open Access Journals (Sweden)

    Alp Akman

    2017-01-01

    Full Text Available Background: Femoral bowing plane (FBP is the unattended subject in the literature. More over the femoral shaft with its bowing is neglected in established anteversion determination methods. There is limited information about the relationship between FBP and anteversion. Thus we focused on this subject and hypothesized that there could be an adaptation of FBP to anteversion. Materials and Methods: FBP is determined on three-dimensional solid models derived from the left femoral computerized tomography data of 47 patients which were taken before for another reason and comparatively evaluated with anteversion. There were 20 women and 27 men. The mean age of patients was 56 years (range 21-84 years. Results: The anteversion values were found as the angle between a distal condylar axis (DCA and femoral neck anteversion axis (FNAA along an imaginary longitudinal femoral axis (LFA in the true cranio-caudal view. The FBP was determined as a plane that passes through the centre-points of three pre-determinated sections on the femoral shaft. The angles between DCA, FNAA and FBP were comparatively evaluated. The independent samples t-test was used for statistical analysis. At the end, it was found that FBP lies nearly perpendicular to the anteversion axis for the mean of our sample which is around 89° in females and 93° in males (range 78-102°. On the other hand, FBP does not lie close to the sagittal femoral plane (SFP; instead, there is an average 12.5° external rotation relative to the SFP. FBP is correlated well with anteversion in terms of FBP inclination from SFP and femoral torsion (i.e., angle between FBP and femoral neck anteversion axis (P0 < 0.001; r = 0.680 and r = −0.682, respectively. Combined correlation is perfect (R[2] = 1 as the FBP, SFP, and posterior femoral plane forms a triangle in the cranio-caudal view. Conclusions: We found that FBP adapts to anteversion. As FBP lies close to perpendicularity for the mean, femoral component

  13. Femoral bowing plane adaptation to femoral anteversion

    Science.gov (United States)

    Akman, Alp; Demirkan, Fahir; Sabir, Nuran; Oto, Murat; Yorukoglu, Cagdas; Kiter, Esat

    2017-01-01

    Background: Femoral bowing plane (FBP) is the unattended subject in the literature. More over the femoral shaft with its bowing is neglected in established anteversion determination methods. There is limited information about the relationship between FBP and anteversion. Thus we focused on this subject and hypothesized that there could be an adaptation of FBP to anteversion. Materials and Methods: FBP is determined on three-dimensional solid models derived from the left femoral computerized tomography data of 47 patients which were taken before for another reason and comparatively evaluated with anteversion. There were 20 women and 27 men. The mean age of patients was 56 years (range 21–84 years). Results: The anteversion values were found as the angle between a distal condylar axis (DCA) and femoral neck anteversion axis (FNAA) along an imaginary longitudinal femoral axis (LFA) in the true cranio-caudal view. The FBP was determined as a plane that passes through the centre-points of three pre-determinated sections on the femoral shaft. The angles between DCA, FNAA and FBP were comparatively evaluated. The independent samples t-test was used for statistical analysis. At the end, it was found that FBP lies nearly perpendicular to the anteversion axis for the mean of our sample which is around 89° in females and 93° in males (range 78–102°). On the other hand, FBP does not lie close to the sagittal femoral plane (SFP); instead, there is an average 12.5° external rotation relative to the SFP. FBP is correlated well with anteversion in terms of FBP inclination from SFP and femoral torsion (i.e., angle between FBP and femoral neck anteversion axis (P < 0.001; r = 0.680 and r = −0.682, respectively). Combined correlation is perfect (R2 = 1) as the FBP, SFP, and posterior femoral plane forms a triangle in the cranio-caudal view. Conclusions: We found that FBP adapts to anteversion. As FBP lies close to perpendicularity for the mean, femoral component positioning

  14. The influences of heat treatments and interdiffusion on the adhesion of plasma-sprayed NiCrAlY coatings

    Energy Technology Data Exchange (ETDEWEB)

    Richard, C.S. [Universite de Technologie de Compiegne (France). Departement de Genie Mecanique; Beranger, G. [Universite de Technologie de Compiegne (France). Departement de Genie Mecanique; Lu, J. [Universite de Technologie de Troyes, Departement de Genie des Systemes Mecaniques, 10000, Troyes (France); Flavenot, J.F. [Centre Technique des Industries Mecaniques (CETIM), Departement Materiaux, 60306 Senlis (France)

    1996-07-01

    Most coatings are applied with a specific aim in mind, such as improving the base material resistance to corrosion or wear, or providing a barrier against high temperatures. These aims can obviously only be achieved if the coating is properly bonded to the substrate. This study is focused on a NiCrAlY metallic bonding layer and its adhesion on to nickel-based superalloy substrate. It also looks at the influence of different spraying methods (atmospheric plasma spraying and vacuum plasma spraying) and the influence of a post-heat treatment on adhesion of the coatings. In order to determine adherence, a Vickers indentation test was performed at the substrate/coating interface. In each case, the residual stresses were evaluated by a step-by-step hole drilling method and these were taken into account in assessing the adhesion parameters. The results were supplemented by a microstructural study of the interface. (orig.)

  15. An Assessment of the Residual Stresses in Low Pressure Plasma Sprayed Coatings on an Advanced Copper Alloy

    Science.gov (United States)

    Raj, S. V.; Ghosn, L. J.; Agarwal, A.; Lachtrupp, T. P.

    2002-01-01

    Modeling studies were conducted on low pressure plasma sprayed (LPPS) NiAl top coat applied to an advanced Cu-8(at.%)Cr-4%Nb alloy (GRCop-84) substrate using Ni as a bond coat. A thermal analysis suggested that the NiAl and Ni top and bond coats, respectively, would provide adequate thermal protection to the GRCop-84 substrate in a rocket engine operating under high heat flux conditions. Residual stress measurements were conducted at different depths from the free surface on coated and uncoated GRCop-84 specimens by x-ray diffraction. These data are compared with theoretically estimated values assessed by a finite element analysis simulating the development of these stresses as the coated substrate cools down from the plasma spraying temperature to room temperature.

  16. Chemical Phase and Valence Studies of Plasma Sprayed Coatings: EDXRD and X-ray Absorption Spectroscopy (XAS) Results

    Science.gov (United States)

    2010-06-01

    powder α-Al2O3 anatase -TiO2 EDXRD –structure nano-alumina/titania feed powder α-Al2O3 anatase -TiO2 cubic-CeO2 cubic-ZrO2 EDXRD –structure ε ε ε ε ε e...Ar, N2 Plasma spray deposition (oxidizing agent) O2 α-Al2O3 anatase -TiO2 Ce3+-O !!! cubic-ZrO2 cubic-Ce4+O2 Inert gas Ar, N2 Plasma spray deposition...H2 (reducing agent) (oxidizing agent) O2 α-Al2O3 anatase -TiO2 Ce3+-O ok? cubic-ZrO2 cubic-Ce4+O2 t2g eg L3 p →d ε continuum d DOS e.g. octahedral

  17. Low Thermal Conductivity Yttria-Stabilized Zirconia Thermal Barrier Coatings Using the Solution Precursor Plasma Spray Process

    Science.gov (United States)

    Jordan, Eric H.; Jiang, Chen; Roth, Jeffrey; Gell, Maurice

    2014-06-01

    The primary function of thermal barrier coatings (TBCs) is to insulate the underlying metal from high temperature gases in gas turbine engines. As a consequence, low thermal conductivity and high durability are the primary properties of interest. In this work, the solution precursor plasma spray (SPPS) process was used to create layered porosity, called inter-pass boundaries, in yttria-stabilized zirconia (YSZ) TBCs. IPBs have been shown to be effective in reducing thermal conductivity. Optimization of the IPB microstructure by the SPPS process produced YSZ TBCs with a thermal conductivity of 0.6 W/mK, an approximately 50% reduction compared to standard air plasma sprayed (APS) coatings. In preliminary tests, SPPS YSZ with IPBs exhibited equal or greater furnace thermal cycles and erosion resistance compared to regular SPPS and commercially made APS YSZ TBCs.

  18. Bulge Testing and Interface Fracture Characterization of Plasma-Sprayed and HIP Bonded Zr Coatings on U-Mo

    Science.gov (United States)

    Hollis, K.; Liu, C.; Leckie, R.; Lovato, M.

    2015-01-01

    Bulge testing using a pressurized fluid to fracture the interface between bonded material layers along with three-dimensional digital image correlation to measure the sample distortion caused by pressurized fluid was applied to plasma-sprayed coatings. The initiation fracture toughness associated with the bonded materials was measured during the testing. The bulge testing of the uranium-molybdenum alloy plasma sprayed with zirconium and clad in aluminum is presented. The initiation fracture toughness was observed to increase with the increasing cathodic arc-cleaning current and the use of alternating polarity transferred arc current. This dependence was linked to the interface composition of oxide and mixed metal phases along with the interface temperature during spray deposition.

  19. High-temperature thermo-mechanical behavior of functionally graded materials produced by plasma sprayed coating: Experimental and modeling results

    Science.gov (United States)

    Choi, Kang Hyun; Kim, Hyun-Su; Park, Chang Hyun; Kim, Gon-Ho; Baik, Kyoung Ho; Lee, Sung Ho; Kim, Taehyung; Kim, Hyoung Seop

    2016-09-01

    Thermal barrier coatings are widely used in aerospace industries to protect exterior surfaces from harsh environments. In this study, functionally graded materials (FGMs) were investigated with the aim to optimize their high temperature resistance and strength characteristics. NiCrAlY bond coats were deposited on Inconel-617 superalloy substrate specimens by the low vacuum plasma spraying technique. Functionally graded Ni-yttria-stabilized zirconia (YSZ) coatings with gradually varying amounts of YSZ (20%-100%) were fabricated from composite powders by vacuum plasma spraying. Heat shield performance tests were conducted using a high- temperature plasma torch. The temperature distributions were measured using thermocouples at the interfaces of the FGM layers during the tests. A model for predicting the temperature at the bond coating-substrate interface was established. The temperature distributions simulated using the finite element method agreed well with the experimental results.

  20. The properties and fracture behavior of ion plasma sprayed TiN coating on stainless steel substrate

    Science.gov (United States)

    Orlova, Dina V.; Goncharenko, Igor M.; Danilov, Vladimir I.; Lobach, Maxim I.; Danilova, Lidiya V.; Shlyakhova, Galina V.

    2015-10-01

    The wear resistance and fracture behavior of ion plasma sprayed TiN coating were studied; the results are presented. The coating was applied to the stainless steel substrate using a vacuum arc method. The samples were tested by active loading. With varying coating thickness, its characteristics were found to change. Multiple cracking would occur in the deformed sample, with fragment borders aligned normal to the extension axis.

  1. Formation and Characterization of Plasma Sprayed Photocatalytic TiO2- ZnO Nano- Compounded Coatings

    Institute of Scientific and Technical Information of China (English)

    Lee Soo Wohn; Aum Ho Sung; Hur Bo Young; Chen Huang

    2004-01-01

    Two kinds of TiO2-ZnO nano-compounded powders aggregated by spray-drying process and evaporation method were used to deposit photocatalytic coatings by atmospheric plasma spraying technique. The phase compositions, morphologies of the agglomerated TiO2-ZnO powders and the as-sprayed coating were characterized using X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) respectively. Furthermore, roughness measurements were carried out on their surfaces of the plasma sprayed TiO2-ZnO nano-comPounded coatings. Compared with the TiO2ZnO nano-compounded coating deposited from the spray-dried powder, it was found that the TiO2-ZnO nano-compounded coating deposited from the evaporated powder possesses higher anatase phase. It is ascribed to the existing of partially melted or non-melted microstructure in the TiO2-ZnO coating deposited from the evaporated powder. The partially-meltedor non-melted microstructure was retained from the starting agglomerated powder. This microstructure is beneficial to improve the photocatalytic properties of plasma sprayed TiO2-ZnO nano-compounded coatings.

  2. Improving Erosion Resistance of Plasma-Sprayed Ceramic Coatings by Elevating the Deposition Temperature Based on the Critical Bonding Temperature

    Science.gov (United States)

    Yao, Shu-Wei; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2017-09-01

    Interlamellar bonding within plasma-sprayed coatings is one of the most important factors dominating the properties and performance of coatings. The interface bonding between lamellae significantly influences the erosion behavior of plasma-sprayed ceramic coatings. In this study, TiO2 and Al2O3 coatings with different microstructures were deposited at different deposition temperatures based on the critical bonding temperature concept. The erosion behavior of ceramic coatings was investigated. It was revealed that the coatings prepared at room temperature exhibit a typical lamellar structure with numerous unbonded interfaces, whereas the coatings deposited at the temperature above the critical bonding temperature present a dense structure with well-bonded interfaces. The erosion rate decreases sharply with the improvement of interlamellar bonding when the deposition temperature increases to the critical bonding temperature. In addition, the erosion mechanisms of ceramic coatings were examined. The unbonded interfaces in the conventional coatings act as pre-cracks accelerating the erosion of coatings. Thus, controlling interlamellar bonding formation based on the critical bonding temperature is an effective approach to improve the erosion resistance of plasma-sprayed ceramic coatings.

  3. Preparation of Aluminum Coatings by Atmospheric Plasma Spraying and Dry-Ice Blasting and Their Corrosion Behavior

    Science.gov (United States)

    Dong, Shu-Juan; Song, Bo; Zhou, Gen-Shu; Li, Chang-Jiu; Hansz, Bernard; Liao, Han-Lin; Coddet, Christian

    2013-10-01

    Aluminum coating, as an example of spray coating material with low hardness, was deposited by atmospheric plasma spraying while dry-ice blasting was applied during the deposition process. The deposited coatings were characterized in terms of microstructure, porosity, phase composition, and the valence states. The results show that the APS aluminum coatings with dry-ice blasting present a porosity of 0.35 ± 0.02%, which is comparable to the bulk material formed by the mechanical compaction. In addition, no evident oxide has been detected, except for the very thin and impervious oxide layer at the outermost layer. Compared to plasma-sprayed Al coatings without dry-ice blasting, the adhesion increased by 52% for Al substrate using dry-ice blasting, while 25% for steel substrate. Corrosion behavior of coated samples was evaluated in 3.5 wt.% NaCl aqueous using electrochemistry measurements. The electrochemical results indicated that APS Al coating with dry-ice blasting was more resistant to pitting corrosion than the conventional plasma-sprayed Al coating.

  4. Microstructure and mechanical properties of nickel-chrome-bor-silicon layers produced by the atmospheric plasma spray process

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2012-01-01

    Full Text Available This paper analyzes the influence of plasma spray parameters on the microstructure and mechanical properties of NiCrBSi coatings deposited by the atmospheric plasma spray (APS process. The microstructure and mechanical properties of plasma spray coatings are determined by the interaction of plasma ions with powder particles when the rate and temperature of plasma particles are transferred to powder particles. The interaction effect directly depends on the time the powder particles spend in plasma, and that time is defined by the deposition distance for each type of powder, depending on the grain size, melting temperature and specific mass. In order to obtain homogeneous and dense coatings, three distances (70,120 and 170 mm from the substrate were used in the research. The coating of the best structural and mechanical characteristics was remelted and fused to the base in order to obtain a better structure. Self - fluxing NiCrBSi alloys are widely used because of the good resistance of boride, carbide and silicide solid phases to wear and corrosion. The morphology of powder particles was examined in the SEM (Scanning Electron Microscope, while the microstructure of the layers was assessed using a light microscope. The microstructural analysis of the deposited layers was performed in accordance with the Pratt-Whitney standard. The mechanical properties of the layers were assessed by applying the HV0.3 method for microhardness testing and tensile testing was applied to test bond strength.

  5. Research Into Ni-Cr-Si-B Coating Sprayed Onto Aluminium Substrate Using the Method of Plasma Spray

    Directory of Open Access Journals (Sweden)

    Raimonda Lukauskaitė

    2012-12-01

    Full Text Available The article deals with Ni base coatings deposited on aluminium substrate applying the method of plasma spray. The purpose of the conducted research is to improve the physical and mechanical properties of coatings on the surface of aluminium alloy work pieces. Spraying on aluminium alloys encounters serious problems, and therefore this work analyses the ways to make the situation more favourable. Before spraying, the surfaces of substrates were modified employing chemical and mechanical pre-treatment methods. The aim of pre-treating aluminium alloys was to remove oxide layers from the aluminium surface. Coating microstructures and porosity were characterised applying optical microscopy. Differences in the roughness of pre-treated surfaces have been determined referring to profilometry. The paper investigates the influence of the adhesion of plasma spray coatings on aluminium surface pretreatment. Microhardness technique was applied for measuring the hardness of coatings. The study also describes and compares the mechanical properties of Ni base coatings deposited on different pre-treated aluminium substrates using plasma spray.Article in Lithuanian

  6. Research Into Ni-Cr-Si-B Coating Sprayed Onto Aluminium Substrate Using the Method of Plasma Spray

    Directory of Open Access Journals (Sweden)

    Raimonda Lukauskaitė

    2013-02-01

    Full Text Available The article deals with Ni base coatings deposited on aluminium substrate applying the method of plasma spray. The purpose of the conducted research is to improve the physical and mechanical properties of coatings on the surface of aluminium alloy work pieces. Spraying on aluminium alloys encounters serious problems, and therefore this work analyses the ways to make the situation more favourable. Before spraying, the surfaces of substrates were modified employing chemical and mechanical pre-treatment methods. The aim of pre-treating aluminium alloys was to remove oxide layers from the aluminium surface. Coating microstructures and porosity were characterised applying optical microscopy. Differences in the roughness of pre-treated surfaces have been determined referring to profilometry. The paper investigates the influence of the adhesion of plasma spray coatings on aluminium surface pretreatment. Microhardness technique was applied for measuring the hardness of coatings. The study also describes and compares the mechanical properties of Ni base coatings deposited on different pre-treated aluminium substrates using plasma spray.Article in Lithuanian

  7. Characterization of Nanostructured NbSi2 Intermetallic Coatings Obtained by Plasma Spraying of Mechanically Alloyed Powders

    Science.gov (United States)

    Yazdani, Zohreh; Karimzadeh, Fathallah; Abbasi, Mohammad-Hasan

    2015-08-01

    Nanostructured NbSi2 powders plasma sprayed on to Ti-6Al-4V substrates were characterized in this research. After preparation of the nanostructured NbSi2 powders by mechanical alloying of an Nb-Si powder mixture, agglomeration was performed to obtain a particle size suitable for spraying. The agglomerated powders were then sprayed by atmospheric plasma spraying. Structural transformation of the powders and morphological and mechanical changes of the coatings were examined by use of x-ray diffraction analysis, scanning electron microscopy, energy dispersive spectroscopy, and microhardness testing. During milling, NbSi2 intermetallic with a grain size of approximately 15 nm was gradually formed. After plasma spraying, a coating of hardness 550 ± 8 HV with a uniform nanocrystalline structure, low oxide content, low porosity, and a good adhesion to the substrate was obtained. No phase change occurred after spraying and the NbSi2 compound remained nanostructured with a grain size of approximately 82 nm.

  8. Plasma Sprayed Dense MgO-Y2O3 Nanocomposite Coatings Using Sol-Gel Combustion Synthesized Powder

    Science.gov (United States)

    Wang, Jiwen; Jordan, Eric H.; Gell, Maurice

    2010-09-01

    MgO-Y2O3 nanostructured composite powder (volume ratio of 50:50) was synthesized by a sol-gel combustion process which generated crystal sizes in the 10-20 nm range. The MgO-Y2O3 nanopowder was plasma sprayed using a conventional, DC arc plasma spray system. X-ray diffraction analysis shows that the as-sprayed MgO-Y2O3 coating is composed of cubic MgO and Y2O3 phases and has ~95% density. Microstructure characterization by SEM reveals that the as-sprayed coating has fine grain sizes of 100-300 nm as a result of rapid solidification. The hardness of the coating, 7.5 ± 0.6 GPa, is higher than that of coarse-grained, dense MgO, and Y2O3 ceramics. This approach demonstrates the potential of plasma spray processes for making thick, dense MgO-Y2O3 nanocomposite performs for applications as durable, infrared windows.

  9. Understanding the Formation of Limited Interlamellar Bonding in Plasma Sprayed Ceramic Coatings Based on the Concept of Intrinsic Bonding Temperature

    Science.gov (United States)

    Yao, Shu-Wei; Tian, Jia-Jia; Li, Chang-Jiu; Yang, Guan-Jun; Li, Cheng-Xin

    2016-12-01

    Interlamellar bonding is an important factor controlling the mechanical, thermal and electrical properties of plasma sprayed ceramic coatings. In order to understand the formation of limited interlamellar bonding, a theoretical model is proposed based on the concept of the intrinsic bonding temperature. The numerical simulation of the interface temperature between a molten splat and underlying splats was performed for splats with uniform and non-uniform thickness, in order to reveal the conditions for the interlamellar bonding formation. The interlamellar bonding ratio was theoretically estimated based on the bonding forming conditions. The features of interlamellar bonding revealed by the simulation agree well with the experimental observations. The bonding ratio of plasma sprayed coatings is significantly influenced by the distribution of splat thickness. According to the distribution of Al2O3 splat thickness in the coating, the theoretical estimation of bonding ratio yielded a value of 0.41 for the plasma sprayed Al2O3 coating at the ambient atmosphere conditions, which is reasonably consistent with the observation value. Therefore, the limited interlamellar bonding can be reasonably explained based on the sufficient condition that the maximum interface temperature between a molten splat and underlying splats is larger than the intrinsic bonding temperature.

  10. Supersonic Plasma Spray Deposition of CoNiCrAlY Coatings on Ti-6Al-4V Alloy

    Science.gov (United States)

    Caliari, F. R.; Miranda, F. S.; Reis, D. A. P.; Essiptchouk, A. M.; Filho, G. P.

    2017-06-01

    Plasma spray is a versatile technology used for production of environmental and thermal barrier coatings, mainly in the aerospace, gas turbine, and automotive industries, with potential application in the renewable energy industry. New plasma spray technologies have been developed recently to produce high-quality coatings as an alternative to the costly low-pressure plasma-spray process. In this work, we studied the properties of as-sprayed CoNiCrAlY coatings deposited on Ti-6Al-4V substrate with smooth surface ( R a = 0.8 μm) by means of a plasma torch operating in supersonic regime at atmospheric pressure. The CoNiCrAlY coatings were evaluated in terms of their surface roughness, microstructure, instrumented indentation, and phase content. Static and dynamic depositions were investigated to examine their effect on coating characteristics. Results show that the substrate surface velocity has a major influence on the coating properties. The sprayed CoNiCrAlY coatings exhibit low roughness ( R a of 5.7 μm), low porosity (0.8%), excellent mechanical properties ( H it = 6.1 GPa, E it = 155 GPa), and elevated interface toughness (2.4 MPa m1/2).

  11. Ablation Resistance of C/C Composites with Atmospheric Plasma-Sprayed W Coating

    Science.gov (United States)

    Zhou, Zhe; Wang, Yuan; Gong, Jieming; Ge, Yicheng; Peng, Ke; Ran, Liping; Yi, Maozhong

    2016-12-01

    To improve the ablation resistance of carbon/carbon (C/C) composites, tungsten (W) coating with thickness of 1.2 mm was applied by atmospheric plasma spraying. The antiablation property of the coated composites was evaluated by oxyacetylene flame ablation experiments. The phase composition of the coating was investigated by a combination of x-ray diffraction analysis and scanning electron microscopy with energy-dispersive x-ray spectroscopy analysis. The ablation resistance of the coated C/C substrates was compared with that of uncoated C/C composites and C/C-CuZr composites after ablation for 30 s. The properties of the coated C/C composites after ablation time of 10, 30, 60, 90, 120, and 180 s were further studied. The results indicated that the mass and linear ablation rates of the W-coated C/C composites were lower than those of uncoated C/C or C/C-CuZr composites after ablation for 30 s. The coating exhibited heat stability after 120 s of ablation, with mass loss and linear ablation rates of 7.39 × 10-3 g/s and 3.50 × 10-3 mm/s, respectively. However, the W coating became ineffective and failed after ablation for 180 s. Three ablation regions could be identified, in which the ablation mechanism of the coating changed from thermochemical to thermophysical erosion to mechanical scouring with increasing ablation time.

  12. Preparation of SrZrO3 Thermal Barrier Coating by Solution Precursor Plasma Spray

    Science.gov (United States)

    Li, Xinhui; Ma, Wen; Wen, Jing; Bai, Yu; Sun, Li; Chen, Baodong; Dong, Hongying; Shuang, Yingchai

    2017-02-01

    The solution precursor plasma spray (SPPS) process is capable of depositing highly durable thermal barrier coatings (TBCs). In this study, an aqueous chemical precursor feedstock was injected into the plasma jet to deposit SrZrO3 thermal barrier coating on metal substrate. Taguchi design of experiments was employed to optimize the SPPS process. The thermal characteristics and phase evolution of the SrZrO3 precursor, as well as the influence of various spray parameters on the coating deposition rate, microhardness, microstructure, and phase stability, were investigated. The experimental results showed that, at given spray distance, feedstock flow rate, and atomization pressure, the optimized spray parameters were arc current of 600 A, argon flow rate of 40 L/min, and hydrogen flow rate of 10 L/min. The SrZrO3 coating prepared using the optimized spray parameters had single-pass thickness of 6.0 μm, porosity of 18%, and microhardness of 6.8 ± 0.1 GPa. Phase stability studies indicated that the as-sprayed SrZrO3 coating had good phase stability in the temperature range from room temperature to 1400 °C, gradually exhibiting a phase transition from t'-ZrO2 to m-ZrO2 in the SrZrO3 coating at 1450 °C with increasing time, while the SrZrO3 phase did not change.

  13. Processing of AlCoCrFeNiTi high entropy alloy by atmospheric plasma spraying

    Science.gov (United States)

    Löbel, M.; Lindner, T.; Kohrt, C.; Lampke, T.

    2017-03-01

    High Entropy Alloys (HEA) are gaining increasing interest due to their unique combination of properties. Especially the combination of high mechanical strength and hardness with distinct ductility makes them attractive for numerous applications. One interesting alloy system that exhibits excellent properties in bulk state is AlCoCrFeNiTi. A high strength, wear resistance and high-temperature resistance are the necessary requirements for the application in surface engineering. The suitability of blended, mechanically ball milled and inert gas atomized feedstock powders for the development of atmospheric plasma sprayed (APS) coatings is investigated in this study. The ball milled and inert gas atomized powders were characterized regarding their particle morphology, phase composition, chemical composition and powder size distribution. The microstructure and phase composition of the thermal spray coatings produced with different feedstock materials was investigated and compared with the feedstock material. Furthermore, the Vickers hardness (HV) was measured and the wear behavior under different tribological conditions was tested in ball-on-disk, oscillating wear and scratch tests. The results show that all produced feedstock materials and coatings exhibit a multiphase composition. The coatings produced with inert gas atomized feedstock material provide the best wear resistance and the highest degree of homogeneity.

  14. Porosity and surface roughness simulation of nickel-aluminum coating in plasma spray forming

    Institute of Scientific and Technical Information of China (English)

    ZENG Hao-ping; FANG Jian-cheng; XU Wen-ji; ZHAO Zi-yu; WANG Li

    2006-01-01

    As the important evaluation parameters concerning the spray qualities, the porosity and surface roughness of the coatings obtained by thermal spray forming have great influence on their forming accuracy, mechanical properties and service lifetime. But it is difficult to predict or control the two parameters for such a highly nonlinear process. A two-dimensional simulation of coating porosity and surface roughness of nickel-aluminum alloy (Ni-5%Al) in plasma spray forming was presented, which was based on the multi-dimensional statistical behaviors of the droplets as well as the simplification and digitization of the typical splat cross sections. Further analysis involving the influence of the droplet diameters and the scanning velocities of the spray gun on the two parameters was conducted. The simulation and analysis results indicate that the porosity and surface roughness are more influenced by the droplet diameters, but less influenced by the spray gun velocities. The results will provide basis for the prediction or control of coating mechanical properties by depositing parameters.

  15. Material fundamentals and clinical performance of plasma-sprayed hydroxyapatite coatings: a review.

    Science.gov (United States)

    Sun, L; Berndt, C C; Gross, K A; Kucuk, A

    2001-01-01

    The clinical use of plasma-sprayed hydroxyapatite (HA) coatings on metal implants has aroused as many controversies as interests over the last decade. Although faster and stronger fixation and more bone growth have been revealed, the performance of HA-coated implants has been doubted. This article will initially address the fundamentals of the material selection, design, and processing of the HA coating and show how the coating microstructure and properties can be a good predictor of the expected behavior in the body. Further discussion will clarify the major concerns with the clinical use of HA coatings and introduce a comprehensive review concerning the outcomes experienced with respect to clinical practice over the past 5 years. A reflection on the results indicates that HA coatings can promote earlier and stronger fixation but exhibit a durability that can be related to the coating quality. Specific relationships between coating quality and clinical performance are being established as characterization methods disclose more information about the coating.

  16. CHARACTERIZATION OF YTTRIA AND MAGNESIA PARTIALLY STABILIZED ZIRCONIA BIOCOMPATIBLE COATINGS DEPOSITED BY PLASMA SPRAYING

    Directory of Open Access Journals (Sweden)

    Roşu R. A.

    2013-09-01

    Full Text Available Zirconia (ZrO2 is a biocompatible ceramic material which is successfully used in medicine to cover the metallic implants by various methods. In order to avoid the inconvenients related to structural changes which may appear because of the temperature treatment while depositing the zirconia layer over the metallic implant, certain oxides are added, the most used being Y2O3, MgO and CaO. This paper presents the experimental results regarding the deposition of yttria (Y2O3 and magnesia (MgO partially stabilized zirconia layers onto titanium alloy substrate by plasma spraying method. X ray diffraction investigations carried out both on the initial powders and the coatings evidenced the fact that during the thermal spraying process the structure has not been significantly modified, consisting primarily of zirconium oxide with tetragonal structure. Electronic microscopy analyses show that the coatings are dense, uniform and cracks-free. Adherence tests performed on samples whose thickness ranges between 160 and 220 μm showed that the highest value (23.5 MPa was obtained for the coating of ZrO2 - 8 wt. % Y2O3 with 160 μm thickness. The roughness values present an increasing tendency with increasing the coatings thickness.

  17. Surface characterization and cytotoxicity analysis of plasma sprayed coatings on titanium alloys.

    Science.gov (United States)

    Rahman, Zia Ur; Shabib, Ishraq; Haider, Waseem

    2016-10-01

    In the realm of biomaterials, metallic materials are widely used for load bearing joints due to their superior mechanical properties. Despite the necessity for long term metallic implants, there are limitations to their prolonged use. Naturally, oxides of titanium have low solubilities and form passive oxide film spontaneously. However, some inclusion and discontinuity spots in oxide film make implant to adopt the decisive nature. These defects heighten the dissolution of metal ions from the implant surface, which results in diminishing bio-integration of titanium implant. To increase the long-term metallic implant stability, surface modifications of titanium alloys are being carried out. In the present study, biomimetic coatings of plasma sprayed hydroxyapatite and titanium were applied to the surface of commercially pure titanium and Ti6Al4V. Surface morphology and surface chemistry were studied using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Cyclic potentiodynamic polarization and electrochemical impedance spectroscopy were carried out in order to study their electrochemical behavior. Moreover, cytotoxicity analysis was conducted for osteoblast cells by performing MTS assay. It is concluded that both hydroxyapatite and titanium coatings enhance corrosion resistance and improve cytocompatibility.

  18. Cytotoxicity study of plasma-sprayed hydroxyapatite coating on high nitrogen austenitic stainless steels.

    Science.gov (United States)

    Ossa, C P O; Rogero, S O; Tschiptschin, A P

    2006-11-01

    Stainless steel has been frequently used for temporary implants but its use as permanent implants is restricted due to its low pitting corrosion resistance. Nitrogen additions to these steels improve both mechanical properties and corrosion resistance, particularly the pitting and crevice corrosion resistance. Many reports concerning allergic reactions caused by nickel led to the development of nickel free stainless steel; it has excellent mechanical properties and very high corrosion resistance. On the other hand, stainless steels are biologically tolerated and no chemical bonds are formed between the steel and the bone tissue. Hydroxyapatite coatings deposited on stainless steels improve osseointegration, due their capacity to form chemical bonds (bioactive fixation) with the bone tissue. In this work hydroxyapatite coatings were plasma-sprayed on three austenitic stainless steels: ASTM-F138, ASTM-F1586 and the nickel-free Böhler-P558. The coatings were analyzed by SEM and XDR. The cytotoxicity of the coatings/steels was studied using the neutral red uptake method by quantitative evaluation of cell viability. The three uncoated stainless steels and the hydroxyapatite coated Böhler-P558 did not have any toxic effect on the cell culture. The hydroxyapatite coated ASTM-F138 and ASTM-F1586 stainless steels presented cytotoxicity indexes (IC50%) lower than 50% and high nickel contents in the extracts.

  19. Studies on Nanocrystalline TiN Coatings Prepared by Reactive Plasma Spraying

    Directory of Open Access Journals (Sweden)

    Dong Yanchun

    2008-01-01

    Full Text Available Titanium nitride (TiN coatings with nanostructure were prepared on the surface of 45 steel (Fe-0.45%C via reactive plasma spraying (denoted as RPS Ti powders using spraying gun with self-made reactive chamber. The microstructural characterization, phases constitute, grain size, microhardness, and wear resistance of TiN coatings were systematically investigated. The grain size was obtained through calculation using the Scherrer formula and observed by TEM. The results of X-ray diffraction and electron diffraction indicated that the TiN is main phase of the TiN coating. The forming mechanism of the nano-TiN was characterized by analyzing the SEM morphologies of surface of TiN coating and TiN drops sprayed on the surface of glass, and observing the temperature and velocity of plasma jet using Spray Watch. The tribological properties of the coating under nonlubricated condition were tested and compared with those of the AISI M2 high-speed steel and Al2O3 coating. The results have shown that the RPS TiN coating presents better wear resistance than the M2 high-speed steel and Al2O3 coating under nonlubricated condition. The microhardness of the cross-section and longitudinal section of the TiN coating was tested. The highest hardness of the cross-section of TiN coating is 1735.43HV100 g.

  20. A simplified analytical model for dc plasma spray torch: influence of gas properties and experimental conditions

    Science.gov (United States)

    Rat, V.; Coudert, J. F.

    2006-11-01

    A simplified analytical model is proposed to evaluate some characteristics of the arc jet generated with a dc plasma torch, in the restricted area of atmospheric plasma spraying conditions. The plasma inside the anode nozzle is considered as stationary and is divided into the arc column and a surrounding cold layer which electrically insulates the plasma from the nozzle wall. Radiation and processes related to the arc attachment at the electrodes are not explicitly taken into account. Heat conduction is evaluated by using Kirchoff's potential, which is described, as it is done also for the electrical conductivity, as a function of the gas specific enthalpy instead of temperature. The model is used to calculate the specific enthalpy radial distribution. From that, and by introducing a mean isentropic coefficient, it is possible to calculate the axial velocity of the plasma jet at the nozzle exit and to evaluate the different pressure contributions. The comparison between predicted and previously measured plasma jet velocities shows good agreement for various experimental conditions.

  1. Suspension Plasma Spray Fabrication of Nanocrystalline Titania Hollow Microspheres for Photocatalytic Applications

    Science.gov (United States)

    Ren, Kun; Liu, Yi; He, Xiaoyan; Li, Hua

    2015-10-01

    Hollow inorganic microspheres with controlled internal pores in close-cell configuration are usually constructed by submicron-sized particles. Fast and efficient large-scale production of the microspheres with tunable sizes yet remains challenging. Here, we report a suspension plasma spray route for making hollow microspheres from nano titania particles. The processing permits most nano particles to retain their physiochemical properties in the as-sprayed microspheres. The microspheres have controllable interior cavities and mesoporous shell of 1-3 μm in thickness. Spray parameters and organic content in the starting suspension play the key role in regulating the efficiency of accomplishing the hollow sphere structure. For the ease of collecting the spheres for recycling use, ferriferous oxide particles were used as additives to make Fe3O4-TiO2 hollow magnetic microspheres. The spheres can be easily recycled through external magnetic field collection after each time use. Photocatalytic anti-bacterial activities of the hollow spheres were assessed by examining their capability of degrading methylene blue and sterilizing Escherichia coli bacteria. Excellent photocatalytic performances were revealed for the hollow spheres, giving insight into their potential versatile applications.

  2. Microstructures and Tribological Properties of Fe-Based Amorphous Metallic Coatings Deposited via Supersonic Plasma Spraying

    Science.gov (United States)

    Zhou, Yang-yang; Ma, Guo-zheng; Wang, Hai-dou; Li, Guo-lu; Chen, Shu-ying; Fu, Bin-guo

    2017-08-01

    The effects of the Ar flow rate and spraying power of a supersonic plasma spraying process on the microstructures and amorphous phase contents of Fe48Cr15Mo14C15B6Y2 amorphous coatings were systematically investigated. The tribological properties of the coatings were evaluated in pin-on-disk mode using a sliding tribometer. The results show that the amorphous phase content and microhardness initially increase with the Ar flow rate and then gradually decrease. However, the amorphous phase content and microhardness increase with the power. In particular, the amorphous phase content of the coating reaches 96.78% with a spraying power of 62 kW and a 110 L min-1 Ar flow rate. Tribological testing demonstrates that the coatings exhibit similar steady-state coefficients of friction (0.75-0.82) with a total test time of 20 min and an applied load of 20 N. However, the wear rates vary with the spraying parameters. In particular, the relative wear rate of the coating can be enhanced up to sixfold under optimal spraying conditions, resulting in excellent wear resistance. Detailed analysis of the coating wear surfaces indicates that the dominant wear mechanisms are abrasive and oxidative wear. Moreover, delamination may occur during the wear process.

  3. Microstructural design of functionally graded coatings composed of suspension plasma sprayed hydroxyapatite and bioactive glass.

    Science.gov (United States)

    Cattini, Andrea; Bellucci, Devis; Sola, Antonella; Pawłowski, Lech; Cannillo, Valeria

    2014-04-01

    Various bioactive glass/hydroxyapatite (HA) functional coatings were designed by the suspension plasma spraying (SPS) technique. Their microstructure, scratch resistance, and apatite-forming ability in a simulated body fluid (SBF) were compared. The functional coatings design included: (i) composite coating, that is, randomly distributed constituent phases; (ii) duplex coating with glass top layer onto HA layer; and (iii) graded coating with a gradual changing composition starting from pure HA at the interface with the metal substrate up to pure glass on the surface. The SPS was a suitable coating technique to produce all the coating designs. The SBF tests revealed that the presence of a pure glass layer on the working surface significantly improved the reactivity of the duplex and graded coatings, but the duplex coating suffered a relatively low scratch resistance because of residual stresses. The graded coating therefore provided the best compromise between mechanical reliability and apatite-forming ability in SBF. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 551-560, 2014.

  4. Characterization of functionally graded hydroxyapatite/titanium composite coatings plasma-sprayed on Ti alloys.

    Science.gov (United States)

    Chen, Chun-Cheng; Huang, Tsui-Hsien; Kao, Chia-Tze; Ding, Shinn-Jyh

    2006-07-01

    Bioceramic coatings like hydroxyapatite (HA) have shown promising bioactive properties in load-bearing implant applications. The aim of this work is to deposit functionally graded HA/Ti layers consisting of an underlying Ti bond coat, the alternating layer, and an HA top-layer on Ti6Al4V substrates using plasma spray to improve the coating-substrate interface properties. The alternating layers were created by means of changing the feeding rate and input power of Ti and HA powders, which gradually decrease Ti content with increasing depth from the Ti bond-coat. The major consideration is to examine the stability of the graded coatings. Experimental results indicated that surface chemistry and morphology of the graded coatings were similar to those of monolithic HA coatings. The bond strength values of the as-sprayed graded coatings were much superior to those of monolithic HA coatings. The cyclic fatigue did have a statistically significant effect on bond strength of monolithic HA coatings, with a decrease of 23%. However, the graded coatings were able to survive 1 million cycles of loading in air without significantly reduced bond strength. The in vitro electrochemical measurement results also indicated that the graded coatings had a more beneficial and desired behavior than monolithic HA coatings after fatigue.

  5. Evaluation and Characterization of Plasma Sprayed Cu Slag-Al Composite Coatings on Metal Substrates

    Directory of Open Access Journals (Sweden)

    S. Mantry

    2013-01-01

    Full Text Available Copper slag is a waste product obtained during matte smelting and refining of copper. The present work explores the coating potential of copper slag by plasma spraying. This work shows that copper slag is eminently coatable. An attempt has been made in the present investigation to use the composites coatings of copper slag and Al powder in suitable combination on aluminium and mild steel substrates in order to improve the surface properties of these ductile metal-alloy substrates. When premixed with Al powder, the coating exhibits higher interfacial adhesion as compared to pure copper slag coatings. Maximum adhesion strengths of about 23 MPa and 21 MPa are recorded for the coatings of copper slag with 15 wt% of Al on aluminium and mild steel substrates, respectively. The input power to the plasma torch is found to affect the coating deposition efficiency and morphology of the coatings. It also suggests value addition of an industrial waste.

  6. Plasma-Powder Feedstock Interaction During Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Hongbo; Zhang, Baopeng

    2017-02-01

    Plasma spray-physical vapor deposition is a new process developed to produce coatings from the vapor phase. To achieve deposition from the vapor phase, the plasma-feedstock interaction inside the plasma torch, i.e., from the powder injection point to the nozzle exit, is critical. In this work, the plasma characteristics and the momentum and heat transfer between the plasma and powder feedstock at different torch input power levels were investigated theoretically to optimize the net plasma torch power, among other important factors such as the plasma gas composition, powder feed rate, and carrier gas. The plasma characteristics were calculated using the CEA2 code, and the plasma-feedstock interaction was studied inside the torch nozzle at low-pressure (20-25 kPa) conditions. A particle dynamics model was introduced to compute the particle velocity, coupled with Xi Chen's drag model for nonevaporating particles. The results show that the energy transferred to the particles and the coating morphology are greatly influenced by the plasma gas characteristics and the particle dynamics inside the nozzle. The heat transfer between the plasma gas and feedstock material increased with the net torch power up to an optimum at 64 kW, at which a maximum of 3.4% of the available plasma energy was absorbed by the feedstock powder. Experimental results using agglomerated 7-8 wt.% yttria-stabilized zirconia (YSZ) powder as feedstock material confirmed the theoretical predictions.

  7. Novel Prospects for Plasma Spray-Physical Vapor Deposition of Columnar Thermal Barrier Coatings

    Science.gov (United States)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Qian; Zhang, Baopeng; Guo, Hongbo

    2017-09-01

    Plasma spray-physical vapor deposition (PS-PVD) is an emerging coating technique that can produce columnar thermal barrier coatings from vapor phase. Feedstock treatment at the start of its trajectory in the plasma torch nozzle is important for such vapor-phase deposition. This study describes the effects of the plasma composition (Ar/He) on the plasma characteristics, plasma-particle interaction, and particle dynamics at different points spatially distributed inside the plasma torch nozzle. The results of calculations show that increasing the fraction of argon in the plasma gas mixture enhances the momentum and heat flow between the plasma and injected feedstock. For the plasma gas combination of 45Ar/45He, the total enthalpy transferred to a representative powder particle inside the plasma torch nozzle is highest ( 9828 kJ/kg). Moreover, due to the properties of the plasma, the contribution of the cylindrical throat, i.e., from the feed injection point (FIP) to the start of divergence (SOD), to the total transferred energy is 69%. The carrier gas flow for different plasma gas mixtures was also investigated by optical emission spectroscopy (OES) measurements of zirconium emissions. Yttria-stabilized zirconia (YSZ) coating microstructures were produced when using selected plasma gas compositions and corresponding carrier gas flows; structural morphologies were found to be in good agreement with OES and theoretical predictions. Quasicolumnar microstructure was obtained with porosity of 15% when applying the plasma composition of 45Ar/45He.

  8. Sliding Wear Behavior of Plasma Sprayed Zirconia Coating on Cast Aluminum against Silicon Carbide Ceramic

    Institute of Scientific and Technical Information of China (English)

    Thuong-Hien LE; Young-Hun CHAE; Seock-Sam KIM

    2005-01-01

    The sliding wear behaviors of ZrO2-22 wt pct MgO (MZ) and ZrO2-8 wt pct Y2O3 (YZ) coatings deposited on a cast aluminum alloy with bond layer (NiCrCoAlY) by plasma spray were investigated under dry test conditions at room temperature. Under all load conditions, the wear mechanisms of the MZ and YZ coatings were almost the same.The material transfer and pullout were involved in the wear process of the studied coatings under the test conditions.The wear rate of the MZ coating was less than that of the YZ coating. While increasing the normal load, the wear rates of the MZ and YZ coatings increased. SEM was used to examine the worn surfaces and to elucidate likely wear mechanisms. Energy dispersive X-ray spectroscopy (EDX) analysis of the worn surfaces indicated that material transfer occurred in the direction from the SiC ball to the disk. Fracture toughness had a significant influence on the wear performance of the coatings. It was suggested that the material transfer played an important role in the wear behavior.

  9. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    Science.gov (United States)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-08-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  10. Suspensions Plasma Spraying of Ceramics with Hybrid Water-Stabilized Plasma Technology

    Science.gov (United States)

    Musalek, Radek; Medricky, Jan; Tesar, Tomas; Kotlan, Jiri; Pala, Zdenek; Lukac, Frantisek; Chraska, Tomas; Curry, Nicholas

    2016-12-01

    Technology of water-stabilized plasma torch was recently substantially updated through introduction of a so-called hybrid concept that combines benefits of water stabilization and gas stabilization principles. The high-enthalpy plasma provided by the WSP-H ("hybrid") torch may be used for thermal spraying of powders as well as liquid feedstocks with high feed rates. In this study, results from three selected experiments with suspension plasma spraying with WSP-H technology are presented. Possibility of deposition of coatings with controlled microstructures was demonstrated for three different ceramics (YSZ—yttria-stabilized zirconia, YAG—yttrium aluminum garnet and Al2O3) introduced into ethanol-based suspensions. Shadowgraphy was used for optimization of suspension injection and visualization of the liquid fragmentation in the plasma jet. Coatings were deposited onto substrates attached to the rotating carousel with integrated temperature monitoring and air cooling, which provided an excellent reproducibility of the deposition process. Deposition of columnar-like YSZ and dense YAG and Al2O3 coatings was successfully achieved. Deposition efficiency reached more than 50%, as evaluated according to EN ISO 17 836 standard.

  11. Plasma-Powder Feedstock Interaction During Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Hongbo; Zhang, Baopeng

    2017-01-01

    Plasma spray-physical vapor deposition is a new process developed to produce coatings from the vapor phase. To achieve deposition from the vapor phase, the plasma-feedstock interaction inside the plasma torch, i.e., from the powder injection point to the nozzle exit, is critical. In this work, the plasma characteristics and the momentum and heat transfer between the plasma and powder feedstock at different torch input power levels were investigated theoretically to optimize the net plasma torch power, among other important factors such as the plasma gas composition, powder feed rate, and carrier gas. The plasma characteristics were calculated using the CEA2 code, and the plasma-feedstock interaction was studied inside the torch nozzle at low-pressure (20-25 kPa) conditions. A particle dynamics model was introduced to compute the particle velocity, coupled with Xi Chen's drag model for nonevaporating particles. The results show that the energy transferred to the particles and the coating morphology are greatly influenced by the plasma gas characteristics and the particle dynamics inside the nozzle. The heat transfer between the plasma gas and feedstock material increased with the net torch power up to an optimum at 64 kW, at which a maximum of 3.4% of the available plasma energy was absorbed by the feedstock powder. Experimental results using agglomerated 7-8 wt.% yttria-stabilized zirconia (YSZ) powder as feedstock material confirmed the theoretical predictions.

  12. Heat load behaviors of plasma sprayed tungsten coatings on copper alloys with different compliant layers

    Energy Technology Data Exchange (ETDEWEB)

    Chong, F.L. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)], E-mail: flch@ipp.ac.cn; Chen, J.L.; Li, J.G. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Hu, D.Y.; Zheng, X.B. [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200051 (China)

    2008-04-15

    Plasma sprayed tungsten (PS-W) coatings with the compliant layers of titanium (Ti), nickel-chromium-aluminum (NiCrAl) alloys and W/Cu mixtures were fabricated on copper alloys, and their properties of the porosity, oxygen content, thermal conductivity and bonding strength were measured. High heat flux tests of actively cooled W coatings were performed by means of an electron beam facility. The results indicated that APS-W coating showed a poorer heat transfer capability and thermo-mechanical properties than VPS-W coating, and the compliant layers improved W coating performance under the heat flux load. Among three compliant layers, W/Cu was the preferable because of its better effects on heat removal and stress alleviating. The optimization of W/Cu compliant layer found that 0.1 mm and 25 vol.%W was optimum compliant layer structure for 1 mm W coating, which induced a 23% reduction of the maximum stress compared to the sharp interface, and the plastic strain was reduced to 0.01% from 1.55%.

  13. Heat load behaviors of plasma sprayed tungsten coatings on copper alloys with different compliant layers

    Science.gov (United States)

    Chong, F. L.; Chen, J. L.; Li, J. G.; Hu, D. Y.; Zheng, X. B.

    2008-04-01

    Plasma sprayed tungsten (PS-W) coatings with the compliant layers of titanium (Ti), nickel-chromium-aluminum (NiCrAl) alloys and W/Cu mixtures were fabricated on copper alloys, and their properties of the porosity, oxygen content, thermal conductivity and bonding strength were measured. High heat flux tests of actively cooled W coatings were performed by means of an electron beam facility. The results indicated that APS-W coating showed a poorer heat transfer capability and thermo-mechanical properties than VPS-W coating, and the compliant layers improved W coating performance under the heat flux load. Among three compliant layers, W/Cu was the preferable because of its better effects on heat removal and stress alleviating. The optimization of W/Cu compliant layer found that 0.1 mm and 25 vol.%W was optimum compliant layer structure for 1 mm W coating, which induced a 23% reduction of the maximum stress compared to the sharp interface, and the plastic strain was reduced to 0.01% from 1.55%.

  14. Rapid Deposition of Titanium Oxide and Zinc Oxide Films by Solution Precursor Plasma Spray

    Science.gov (United States)

    Ando, Yasutaka

    In order to develop a high rate atmospheric film deposition process for functional films, as a basic study, deposition of titanium oxide film and zinc oxide film by solution precursor plasma spray (SPPS) was conducted in open air. Consequently, in the case of titanium oxide film deposition, anantase film and amorphous film as well as rutile film could be deposited by varying the deposition distance. In the case of anatase dominant film, photo-catalytic properties of the films could be confirmed by wettability test. In addition, the dye sensitized sollar cell (DSC) using the TiO2 film deposited by this SPPS technique as photo voltaic device generates 49mV in OCV. On the other hand, in the case of zinc oxide film deposition, it was proved that well crystallized ZnO films with photo catalytic properties could be deposited. From these results, this process was found to have high potential for high rate functional film deposition process conducted in the air.

  15. Thermal Barrier Coatings Made by the Solution Precursor Plasma Spray Process

    Science.gov (United States)

    Gell, Maurice; Jordan, Eric H.; Teicholz, Matthew; Cetegen, Baki M.; Padture, Nitin P.; Xie, Liangde; Chen, Dianying; Ma, Xinqing; Roth, Jeffrey

    2008-03-01

    The solution precursor plasma spray (SPPS) process is a relatively new and flexible thermal spray process that can produce a wide variety of novel materials, including some with superior properties. The SPPS process involves injecting atomized droplets of a precursor solution into the plasma. The properties of resultant deposits depend on the time-temperature history of the droplets in the plasma, ranging from ultra-fine splats to unmelted crystalline particles to unpyrolized particles. By controlling the volume fraction of these three different constituents, a variety of coatings can be produced, all with a nanograin size. In this article, we will be reviewing research related to thermal barrier coatings, emphasizing the processing conditions necessary to obtain a range of microstructures and associated properties. The SPPS process produces a unique strain-tolerant, low-thermal conductivity microstructure consisting of (i) three-dimensional micrometer and nanometer pores, (ii) through-coating thickness (vertical) cracks, (iii) ultra-fine splats, and (iv) inter-pass boundaries. Both thin (0.12 mm) and thick (4 mm) coatings have been fabricated. The volume fraction of porosity can be varied from 10% to 40% while retaining the characteristic microstructure of vertical cracks and ultra-fine splats. The mechanism of vertical crack formation will be described.

  16. Investigation on plasma-sprayed ZrO2 thermal barrier coating on nickel alloy substrate

    Institute of Scientific and Technical Information of China (English)

    卢安贤; 常鹰; 蔡小梅

    2002-01-01

    The thermal barrier coatings with NiCrAlY alloy bonding layer, NiCrAlY-Y2O3 stabilized ZrO2 transition layer and Y2O3 stabilized ZrO2 ceramic layer are prepared on nickel alloy substrates using the plasma spray technique. The relationship among the composition, structure and property of the coatings are investiga-ted by means of optical microscope, scanning electronic microscope and the experiments of thermal shock resistance cycling and high temperature oxidation resistance. The results show that the structure design of introdu-cing a transition layer between Ni alloy substrate and ZrO2 ceramic coating guarantees the high quality and properties of the coatings; ZrO2 coatings doped with a little SiO2 possesses better thermal shock resistance and more excellent hot corrosion resistance as compared with ZrO2 coating materials without SiO2 ;the improvement in performance of ZrO2 coating doped with SiO2 is due to forming more dense coating structure by self- closing effects of the flaws and pores in the ZrO2 coatings.

  17. Investigations on the Nature of Ceramic Deposits in Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    He, W.; Mauer, G.; Gindrat, M.; Wäger, R.; Vaßen, R.

    2017-01-01

    In Plasma Spray-Physical Vapor Deposition (PS-PVD) process, major fractions of the feedstock powder can be evaporated so that coatings are deposited mainly from the vapor phase. In this work, Computational Fluid Dynamics (CFD) results indicate that such evaporation occurs significantly in the plasma torch nozzle and even nucleation and condensation of zirconia is highly possible there. Experimental work has been performed to investigate the nature of the deposits in the PS-PVD process, in particular coatings from condensate vapor and nano-sized clusters produced at two spraying distances of 1000 mm and 400 mm. At long spraying distance, columns in the coatings have pyramidal tops and very sharp faceted microstructures. When the spraying distance is reduced to 400 mm, the tops of columns become relatively flat and a faceted structure is not recognizable. XRD patterns show obvious preferred orientations of (110) and (002) in the coatings sprayed at 400 mm but only limited texture in the coatings sprayed at 1000 mm. Meanwhile, a non-line of sight coating was also investigated, which gives an example for pure vapor deposition. Based on these analyses, a vapor and cluster depositions are suggested to further explain the formation mechanisms of high-quality columnar-structured PS-PVD thermal barrier coatings which have already shown excellent performance in cyclic lifetime test.

  18. Highly Segmented Thermal Barrier Coatings Deposited by Suspension Plasma Spray: Effects of Spray Process on Microstructure

    Science.gov (United States)

    Chen, Xiaolong; Honda, Hiroshi; Kuroda, Seiji; Araki, Hiroshi; Murakami, Hideyuki; Watanabe, Makoto; Sakka, Yoshio

    2016-12-01

    Effects of the ceramic powder size used for suspension as well as several processing parameters in suspension plasma spraying of YSZ were investigated experimentally, aiming to fabricate highly segmented microstructures for thermal barrier coating (TBC) applications. Particle image velocimetry (PIV) was used to observe the atomization process and the velocity distribution of atomized droplets and ceramic particles travelling toward the substrates. The tested parameters included the secondary plasma gas (He versus H2), suspension injection flow rate, and substrate surface roughness. Results indicated that a plasma jet with a relatively higher content of He or H2 as the secondary plasma gas was critical to produce highly segmented YSZ TBCs with a crack density up to 12 cracks/mm. The optimized suspension flow rate played an important role to realize coatings with a reduced porosity level and improved adhesion. An increased powder size and higher operation power level were beneficial for the formation of highly segmented coatings onto substrates with a wider range of surface roughness.

  19. Atmospheric Plasma Spraying of Single Phase Lanthanum Zirconate Thermal Barrier Coatings with Optimized Porosity

    Directory of Open Access Journals (Sweden)

    Georg Mauer

    2016-10-01

    Full Text Available The shortcomings at elevated operation temperatures of the standard material yttria-stabilized zirconia (YSZ for thermal barrier coatings (TBCs have initiated many research activities seeking alternatives. One candidate is the pyrochlore lanthanum zirconate La2Zr2O7 (LZ, which is phase-stable to its melting point. At the same time, it shows a lower thermal conductivity and a lower sintering tendency when compared to YSZ. Because of its low thermal expansion coefficient and poor toughness, it is applied in combination with YSZ in double layer TBC systems. It is the current state of knowledge that LZ is prone to lanthanum depletion if processed by plasma spraying. The process conditions have to be selected carefully to avoid this. Furthermore, the amount and morphology of the coating porosity is essential for a good thermo-mechanical performance. In this work, the development and testing of LZ/YSZ double layer TBC systems is described. Initially, suitable basic parameters (torch, plasma gas composition, and power were tested with respect to coating stoichiometry. Then, microstructures were optimized by adjusting feed rate, spray distance, and by selecting a more appropriate feedstock. Powder particles and coatings were characterized by digital image analysis.

  20. Phase Composition, Microstructure, and Tribological Property of Plasma-Sprayed TiC-BASED Coating

    Science.gov (United States)

    Sun, Shibin; Zou, Zengda; Liu, Xuemei; Shi, Hanchao

    TiC-based wear resistant coating was prepared by plasma spraying using reconstituted composite powders doped with ultra-fine carbide. Phase composition and microstructure of as-sprayed coating were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) utilizing backscattered imaging mode (BSE), and electron probe micro-analysis. Wear test was performed by using a ring-on-block tester under dry sliding condition. Results show that the coating adheres well to the substrate and no delamination appears. TiC content underwent pronounced reduction because of oxidation, reaction, and physical loss. Reactions between TiC and Mo and probably between dissociated C and Mo lead to the formation of Mo2C. Wear resistance of NiCrMo-TiC coating is about 4-8 times higher than that of substrate under different applied force. This work shed light on the reconstitution of spraying powder doped with ultra-fine reinforce phase particles, and the present results are important for the preparation of nano-doped TiC-based coatings.

  1. Determination of residual stresses within plasma spray coating using Moiré interferometry method

    Science.gov (United States)

    Yi, Jiang; Bin-shi, Xu; Hai-dou, Wang; Ming, Liu; Yao-hui, Lu

    2011-01-01

    In this paper, residual stresses of the Ni-Cr-B-Si coatings prepared by supersonic plasma spray processing were measured by moiré interferometry and X-ray diffraction method. Moiré interferometry method was used in measuring the distribution of residual stresses of the Ni-Cr-B-Si coatings alongside the specimen thickness direction, then the distribution of residual stresses both in the substrate and the coating was also analyzed. Experimental results showed that residual stresses in the coating and the substrate are tensile and compressive separately; residual stresses of the coating are diminished with the increase of the distance from the coating surface and almost zero at the coating-substrate interface; the maximum of compressive residual stresses of the substrate are present to the vicinity of the coating-substrate interface. It could be concluded that residual stresses in the specimen would result from the dismatch of thermophysical properties between the coating and substrate during the spray process, and the distribution of residual stresses of the substrate would be influenced by the sandblasting prior to spraying.

  2. Surface laser-glazing of plasma-sprayed thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Batista, C. [University of Minho, Physics Department, Campus de Gualtar, 4710-057 Braga (Portugal); Portinha, A. [University of Minho, Physics Department, Campus de Gualtar, 4710-057 Braga (Portugal); Ribeiro, R.M. [University of Minho, Physics Department, Campus de Gualtar, 4710-057 Braga (Portugal)]. E-mail: ricardo@fisica.uminho.pt; Teixeira, V. [University of Minho, Physics Department, Campus de Gualtar, 4710-057 Braga (Portugal); Costa, M.F. [University of Minho, Physics Department, Campus de Gualtar, 4710-057 Braga (Portugal); Oliveira, C.R. [Instituto de Desenvolvimentoe Inovacao Tecnologica (IDIT), 4520-102 Santa Maria da Feira (Portugal); University Lusiada, 4760-108 Vila Nova de Famalicao (Portugal)

    2005-07-15

    Atmospheric plasma-sprayed (APS) ZrO{sub 2}-8%WtY{sub 2}O{sub 3} thermal barrier coatings (TBCs) were subjected to a CO{sub 2} continuous wave laser-glazing process in order to generate an external dense layer produced by different processing parameters. For that purpose, different beam scanning speeds and track overlapping were chosen. Surface roughness has been reduced significantly after laser-glazing. Despite the surface crack network, all laser-glazed specimens presented a fully dense and porous free external layer with a columnar microstructure. Surface cracks along the densified layer were found to have tendency to be oriented in two perpendicular directions, one in the direction of the laser beam travel, the other perpendicular to it. Moreover, the cracks parallel to the beam moving direction are found to be on the overlapping zone, coinciding with the edge of the subsequent track. The cracks along the densified layer are vertical and tend to branch and deviate from the vertical direction within the porous PS coating. The largest overlapping allied to the smallest amount of irradiated energy generated the most uniform layer with the shortest crack branches within the PS coating. For the as-sprayed coating, the XRD results revealed mainly t' non-transformable tetragonal zirconia with a small percentage of residual monoclinic zirconia. All glazed coatings presented only t' non-transformable tetragonal zirconia with some variations on preferable crystal orientation.

  3. High-Temperature Solid Lubricant Coating by Plasma Spraying Using Metal-Metal Clad Powders

    Science.gov (United States)

    Zhang, Tiantian; Lan, Hao; Yu, Shouquan; Huang, Chuanbing; Du, Lingzhong; Zhang, Weigang

    2017-08-01

    NiCr/Ag-Mo composite coating was fabricated by atmospheric plasma spray technology using clad powders as the feedstock. Its tribological properties at variable temperature were evaluated using a ball-on-disk high-temperature tribometer in air. The results showed that compared with NiCr, the NiCr/Ag-Mo composite coating exhibited better lubrication effect and higher wear resistance at all test temperatures, especially above 600 °C. At 800 °C, NiCr/Ag-Mo composite coating showed the lowest friction coefficient of about 0.2 and its corresponding wear rate reached 2.5 × 10-5 mm3/Nm. Characterizations of NiCr/Ag-Mo composite coating revealed that at temperatures below 400 °C, Ag was smeared and spread onto the wear surface, reducing the friction and wear. At temperature above 500 °C, the Ag2MoO4 lubrication film formed by tribo-oxidation significantly improved the coating's lubrication effect and wear resistance.

  4. The low cycle fatigue behavior of a plasma-sprayed coating material

    Science.gov (United States)

    Gayda, J.; Gabb, T. P.; Miner, R. V., Jr.

    1986-01-01

    Single crystal nickel-base superalloys employed in turbine blade applications are often used with a plasma spray coating for oxidation and hot corrosion resistance. These coatings may also affect fatigue life of the superalloy substrate. As part of a large program to understand the fatigue behavior of coated single crystals, fully reversed, total strain controlled fatigue tests were run on a free standing NiCoCrAlY coating alloy, PWA 276, at 0.1 Hz. Fatigue tests were conducted at 650 C, where the NiCoCrAlY alloy has modest ductility, and at 1050 C, where it is extremely ductile, showing tensile elongation in excess of 100 percent. At the lower test temperature, deformation induced disordering softened the NiCoCrAlY alloy, while at the higher test temperature cyclic hardening was observed which was linked to gradual coarsening of the two phase microstructure. Fatigue life of the NiCoCrAlY alloy was significantly longer at the higher temperature. Further, the life of the NiCoCrAlY alloy exceeds that of coated, /001/-oriented PWA 1480 single crystals at 1050 C, but at 650 C the life of the coated crystal is greater than that of the NiCoCrAlY alloy on a total strain basis.

  5. Plasma-Sprayed ZnO/TiO2 Coatings with Enhanced Biological Performance

    Science.gov (United States)

    Zhao, Xiaobing; Peng, Chao; You, Jing

    2017-08-01

    Surface chemical composition and topography are two key factors in the biological performance of implants. The aim of this work is to deposit ZnO/TiO2 composite coatings on the surface of titanium substrates by plasma spraying technique. The effects of the amount of ZnO doping on the microstructure, surface roughness, corrosion resistance, and biological performance of the TiO2 coatings were investigated. The results indicated that the phase composition of the as-sprayed TiO2 coating was mainly rutile. Addition of 10% ZnO into TiO2 coating led to a slight shift of the diffraction peaks to lower angle. Anatase phase and Zn2TiO4 were formed in 20%ZnO/TiO2 and 30%ZnO/TiO2 coatings, respectively. Doping with ZnO changed the topography of the TiO2 coatings, which may be beneficial to enhance their biological performance. All coatings exhibited microsized surface roughness, and the corrosion resistance of ZnO/TiO2 coatings was improved compared with pure TiO2 coating. The ZnO/TiO2 coatings could induce apatite formation on their surface and inhibit growth of Staphylococcus aureus, but these effects were dose dependent. The 20%ZnO/TiO2 coating showed better biological performance than the other coatings, suggesting potential application for bone implants.

  6. Low cycle fatigue behaviour of a plasma-sprayed coating material

    Science.gov (United States)

    Gayda, J.; Gabb, T. P.; Miner, R. V.

    1986-01-01

    Single crystal nickel-base superalloys employed in turbine blade applications are often used with a plasma spray coating for oxidation and hot corrosion resistance. These coatings may also affect fatigue life of the superalloy substrate. As part of a large program to understand the fatigue behavior of coated single crystals, fully reversed, total strain controlled fatigue tests were run on a free standing NiCoCrAlY coating alloy, PWA 276, at 0.1 Hz. Fatigue tests were conducted at 650 C, where the NiCoCrAlY alloy has modest ductility, and at 1050 C, where it is extremely ductile, showing tensile elongation in excess of 100 percent. At the lower test temperature, deformation induced disordering softened the NiCoCrAlY alloy, while at the higher test temperature cyclic hardening was observed which was linked to gradual coarsening of the two phase microstructure. Fatigue life of the NiCoCrAlY alloy was significantly longer at the higher temperature. Further, the life of the NiCoCrAlY alloy exceeds that of coated, /001/-oriented PWA 1480 single crystals at 1050 C but at 650 C the life of the coated crystal is greater than that of the NiCoCrAlY alloy on a total strain basis.

  7. Bilayer Suspension Plasma-Sprayed Thermal Barrier Coatings with Enhanced Thermal Cyclic Lifetime: Experiments and Modeling

    Science.gov (United States)

    Gupta, Mohit; Kumara, Chamara; Nylén, Per

    2017-08-01

    Suspension plasma spraying (SPS) has been shown as a promising process to produce porous columnar strain tolerant coatings for thermal barrier coatings (TBCs) in gas turbine engines. However, the highly porous structure is vulnerable to crack propagation, especially near the topcoat-bondcoat interface where high stresses are generated due to thermal cycling. A topcoat layer with high toughness near the topcoat-bondcoat interface could be beneficial to enhance thermal cyclic lifetime of SPS TBCs. In this work, a bilayer coating system consisting of first a dense layer near the topcoat-bondcoat interface followed by a porous columnar layer was fabricated by SPS using Yttria-stabilised zirconia suspension. The objective of this work was to investigate if the bilayer topcoat architecture could enhance the thermal cyclic lifetime of SPS TBCs through experiments and to understand the effect of the column gaps/vertical cracks and the dense layer on the generated stresses in the TBC during thermal cyclic loading through finite element modeling. The experimental results show that the bilayer TBC had significantly higher lifetime than the single-layer TBC. The modeling results show that the dense layer and vertical cracks are beneficial as they reduce the thermally induced stresses which thus increase the lifetime.

  8. High Temperature Multilayer Environmental Barrier Coatings Deposited Via Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Harder, Bryan James; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2014-01-01

    Si-based ceramic matrix composites (CMCs) require environmental barrier coatings (EBCs) in combustion environments to avoid rapid material loss. Candidate EBC materials have use temperatures only marginally above current technology, but the addition of a columnar oxide topcoat can substantially increase the durability. Plasma Spray-Physical Vapor Deposition (PS-PVD) allows application of these multilayer EBCs in a single process. The PS-PVD technique is a unique method that combines conventional thermal spray and vapor phase methods, allowing for tailoring of thin, dense layers or columnar microstructures by varying deposition conditions. Multilayer coatings were deposited on CMC specimens and assessed for durability under high heat flux and load. Coated samples with surface temperatures ranging from 2400-2700F and 10 ksi loads using the high heat flux laser rigs at NASA Glenn. Coating morphology was characterized in the as-sprayed condition and after thermomechanical loading using electron microscopy and the phase structure was tracked using X-ray diffraction.

  9. Custom-designed orthopedic implants evaluated using finite element analysis of patient-specific computed tomography data: femoral-component case study

    Directory of Open Access Journals (Sweden)

    Nayfeh Jamal F

    2007-09-01

    Full Text Available Abstract Background Conventional knee and hip implant systems have been in use for many years with good success. However, the custom design of implant components based on patient-specific anatomy has been attempted to overcome existing shortcomings of current designs. The longevity of cementless implant components is highly dependent on the initial fit between the bone surface and the implant. The bone-implant interface design has historically been limited by the surgical tools and cutting guides available; and the cost of fabricating custom-designed implant components has been prohibitive. Methods This paper describes an approach where the custom design is based on a Computed Tomography scan of the patient's joint. The proposed design will customize both the articulating surface and the bone-implant interface to address the most common problems found with conventional knee-implant components. Finite Element Analysis is used to evaluate and compare the proposed design of a custom femoral component with a conventional design. Results The proposed design shows a more even stress distribution on the bone-implant interface surface, which will reduce the uneven bone remodeling that can lead to premature loosening. Conclusion The proposed custom femoral component design has the following advantages compared with a conventional femoral component. (i Since the articulating surface closely mimics the shape of the distal femur, there is no need for resurfacing of the patella or gait change. (ii Owing to the resulting stress distribution, bone remodeling is even and the risk of premature loosening might be reduced. (iii Because the bone-implant interface can accommodate anatomical abnormalities at the distal femur, the need for surgical interventions and fitting of filler components is reduced. (iv Given that the bone-implant interface is customized, about 40% less bone must be removed. The primary disadvantages are the time and cost required for the

  10. Wear predictions for UHMWPE material with various surface properties used on the femoral component in total knee arthroplasty: a computational simulation study.

    Science.gov (United States)

    Kang, Kyoung-Tak; Son, Juhyun; Kim, Ho-Joong; Baek, Changhyun; Kwon, Oh-Ryong; Koh, Yong-Gon

    2017-07-01

    The wear of ultrahigh-molecular weight polyethylene (UHMWPE) tibial inserts in total knee arthroplasty (TKA) remains a major limitation that hinders the longevity of clinically successful devices. Surface properties significantly affect the overall performance of TKA, and surface modification with mechanically and chemically stable materials is an effective method for overcoming the wear of TKA. However, wear tests are not cost-efficient or time-efficient; thus, the effects of geometric, loading, and alignment perturbations are often evaluated via parametric studies. Computational wear prediction using a finite element (FE) model followed by validation through comparison with experimental data is effective for assessing new prosthetic designs or surface change methods prior to functional testing and surgical implementation. The aim of this study was to evaluate the weight loss, wear depth, and kinematics for different surface properties, including nanostructured diamond (NSD), diamond-like carbon (DLC), titanium-nitride (TiN), and oxidized zirconium (OxZr) on femoral components in TKA using FE analysis under gait-cycle loading conditions. Weight loss and wear depth were lowest with OxZr followed by TiN, NSD, and DLC. However, the DLC femoral component did not show any improvement in wear rate compared to an uncoated cobalt-chromium (Co-Cr) femoral component. Not all surface changes applied in this study did lead to improvement in wear performance. However, this study demonstrates the potential of OxZr and TiN for reducing UHMWPE wear and offers new insights into the effects of wear on TKA.

  11. The association of lesion eccentricity with plaque morphology and components in the superficial femoral artery: a high-spatial-resolution, multi-contrast weighted CMR study

    Directory of Open Access Journals (Sweden)

    Zhao Xihai

    2010-07-01

    Full Text Available Abstract Background Atherosclerotic plaque morphology and components are predictors of subsequent cardiovascular events. However, associations of plaque eccentricity with plaque morphology and plaque composition are unclear. This study investigated associations of plaque eccentricity with plaque components and morphology in the proximal superficial femoral artery using cardiovascular magnetic resonance (CMR. Methods Twenty-eight subjects with an ankle-brachial index less than 1.00 were examined with 1.5T high-spatial-resolution, multi-contrast weighted CMR. One hundred and eighty diseased locations of the proximal superficial femoral artery (about 40 mm were analyzed. The eccentric lesion was defined as [(Maximum wall thickness- Minimum wall thickness/Maximum wall thickness] ≥ 0.5. The arterial morphology and plaque components were measured using semi-automatic image analysis software. Results One hundred and fifteen locations were identified as eccentric lesions and sixty-five as concentric lesions. The eccentric lesions had larger wall but similar lumen areas, larger mean and maximum wall thicknesses, and more calcification and lipid rich necrotic core, compared to concentric lesions. For lesions with the same lumen area, the degree of eccentricity was associated with an increased wall area. Eccentricity (dichotomous as eccentric or concentric was independently correlated with the prevalence of calcification (odds ratio 3.78, 95% CI 1.47-9.70 after adjustment for atherosclerotic risk factors and wall area. Conclusions Plaque eccentricity is associated with preserved lumen size and advanced plaque features such as larger plaque burden, more lipid content, and increased calcification in the superficial femoral artery.

  12. Does mismatch of the femoral component aspect ratio influence the range of knee flexion after posterior-stabilized total knee arthroplasty?

    Institute of Scientific and Technical Information of China (English)

    JIA Yu-tao; WANG Lei; ZHANG Yu; ZHAO Cong; SUN Zhen-hui; LIU Jun

    2012-01-01

    Objective: To study whether the range of knee flexion (ROF) is affected by geometrical mismatch of the femoral component and the resultant change in the posterior condylar offset (PCO) after high-flexion posterior-stabilized total knee arthroplasty (TKA).Methods:One hundred osteoarthritic patients (50 males and 50 females) underwent femoral osteotomy by the anterior referencing technique.The PCO for each patient was measured from lateral radiographs before,during and 2 years after TKA.The thickness of the joint cartilage was measured by magnetic resonance imaging before TKA and added onto the radiographic measurement.The relationship between changes in the PCO and improvements in the ROF before,during and 2 years after TKA were statistically analyzed.Results: Compared with the preoperative value,the PCO was reduced by (3.45±3.28) mm after TKA,with a significantly larger reduction observed in female patients than male patients (P<0.05).When examining the subject population as a whole,there was a significant positive correlation between PCO and ROF improvement during TKA (P< 0.05),but this improvement was not maintained 2 years after TKA (P>0.05).However,when male and female patients were analyzed separately,there was a significant positive correlation between PCO change and ROF improvement for both sexes at both time points (all P<0.05).Conclusions: Restoration of PCO plays an important role in the optimization of knee flexion even after posteriorstabilized TKA.Femoral components based on Caucasian anatomic characteristics could not match the native anatomy of distal femurs in Chinese population especially female Chinese.Rotated resection of distal femur with anterior referencing technique usually leads to a decreased PCO and therefore reduces maximal obtainable flexion.

  13. Optimizing surface characteristics for cell adhesion and proliferation on titanium plasma spray coatings on polyetheretherketone.

    Science.gov (United States)

    Yoon, Byung Jo Victor; Xavier, Fred; Walker, Brendon R; Grinberg, Samuel; Cammisa, Frank P; Abjornson, Celeste

    2016-10-01

    Titanium plasma spray coating on polyetheretherketone (PEEK) is a recent innovation to interbody spacer technology. The inherent hydrophobic properties of standard, uncoated PEEK implants can hamper cell attachment and bone healing during fusion. The addition of titanium coating not only offers initial stability due to increased surface roughness but also long-term stability due to bony ongrowth created from osteoconductive microenvironment on the device surface. The previously established hydrophilic and osteophilic properties of commercially pure titanium (CPTi) can potentially provide an ideal environment promoting cell attachment and bony ongrowth when applied at the end plate level of the fusion site. Because the surface material composition and topography is what seems to directly affect cell adhesion, it is important to determine the ideal titanium coating for the highest effectiveness. The purpose of the study is to determine whether there is an optimal surface roughness for the titanium coatings and whether different polishing methods have a greater effect than roughness or topography in mediating cell adhesion to the surface. The study was divided into two phases. In Phase 1, the effects of varying surface roughnesses on identical polishing method were compared. In Phase 2, the effect of varying polishing methods was compared on identical surface roughnesses. Coating thickness, porosity, and surface roughness were characterized using an optical microscope as per ASTM F 1854 standards. For both phases, PEEK coupons with plasma-sprayed CPTi were used, and human mesenchymal stem cells (hMSCs) at an initial density of 25,000 cells/cm(2) were seeded and cultured for 24 hours before fixation in 10% formalin. The cultured hMSCs were visualized by 4',6-diamidino-2-phenylindole (DAPI) staining, a fluorescent stain that binds to the DNA of living cells. Samples were imaged using an environmental scanning electron microscope (eSEM) (Carl Zeiss Microscopy

  14. Surface characterization and cytotoxicity analysis of plasma sprayed coatings on titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Zia ur; Shabib, Ishraq [School of Engineering and Technology, Central Michigan University, Mount Pleasant, MI 48859 (United States); Science of Advanced Materials, Central Michigan University, Mount Pleasant, MI 48859 (United States); Haider, Waseem, E-mail: haide1w@cmich.edu [School of Engineering and Technology, Central Michigan University, Mount Pleasant, MI 48859 (United States); Science of Advanced Materials, Central Michigan University, Mount Pleasant, MI 48859 (United States)

    2016-10-01

    In the realm of biomaterials, metallic materials are widely used for load bearing joints due to their superior mechanical properties. Despite the necessity for long term metallic implants, there are limitations to their prolonged use. Naturally, oxides of titanium have low solubilities and form passive oxide film spontaneously. However, some inclusion and discontinuity spots in oxide film make implant to adopt the decisive nature. These defects heighten the dissolution of metal ions from the implant surface, which results in diminishing bio-integration of titanium implant. To increase the long-term metallic implant stability, surface modifications of titanium alloys are being carried out. In the present study, biomimetic coatings of plasma sprayed hydroxyapatite and titanium were applied to the surface of commercially pure titanium and Ti6Al4V. Surface morphology and surface chemistry were studied using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Cyclic potentiodynamic polarization and electrochemical impedance spectroscopy were carried out in order to study their electrochemical behavior. Moreover, cytotoxicity analysis was conducted for osteoblast cells by performing MTS assay. It is concluded that both hydroxyapatite and titanium coatings enhance corrosion resistance and improve cytocompatibility. - Highlights: • Surface morphology and surface chemistry were studied using scanning electron microscopy and X-ray photoelectron spectroscopy. • The cyclic polarization tests revealed noticeable improvement towards the positive potentials for both Tip coatings. • CpTi-Hap and Ti6Al4V-Hap both demonstrate similar corrosion rate. • High cytotoxicity was observed for Mp when compared with Tip and Hap after 21 days of immersion. • Both Tip and Hap coatings promoted the osteoblast cell adhesion and exhibited stellar morphology.

  15. Method and Process Development of Advanced Atmospheric Plasma Spraying for Thermal Barrier Coatings

    Science.gov (United States)

    Mihm, Sebastian; Duda, Thomas; Gruner, Heiko; Thomas, Georg; Dzur, Birger

    2012-06-01

    Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments.

  16. Erosion Performance of Gadolinium Zirconate-Based Thermal Barrier Coatings Processed by Suspension Plasma Spray

    Science.gov (United States)

    Mahade, Satyapal; Curry, Nicholas; Björklund, Stefan; Markocsan, Nicolaie; Nylén, Per; Vaßen, Robert

    2017-01-01

    7-8 wt.% Yttria-stabilized zirconia (YSZ) is the standard thermal barrier coating (TBC) material used by the gas turbines industry due to its excellent thermal and thermo-mechanical properties up to 1200 °C. The need for improvement in gas turbine efficiency has led to an increase in the turbine inlet gas temperature. However, above 1200 °C, YSZ has issues such as poor sintering resistance, poor phase stability and susceptibility to calcium magnesium alumino silicates (CMAS) degradation. Gadolinium zirconate (GZ) is considered as one of the promising top coat candidates for TBC applications at high temperatures (>1200 °C) due to its low thermal conductivity, good sintering resistance and CMAS attack resistance. Single-layer 8YSZ, double-layer GZ/YSZ and triple-layer GZdense/GZ/YSZ TBCs were deposited by suspension plasma spray (SPS) process. Microstructural analysis was carried out by scanning electron microscopy (SEM). A columnar microstructure was observed in the single-, double- and triple-layer TBCs. Phase analysis of the as-sprayed TBCs was carried out using XRD (x-ray diffraction) where a tetragonal prime phase of zirconia in the single-layer YSZ TBC and a cubic defect fluorite phase of GZ in the double and triple-layer TBCs was observed. Porosity measurements of the as-sprayed TBCs were made by water intrusion method and image analysis method. The as-sprayed GZ-based multi-layered TBCs were subjected to erosion test at room temperature, and their erosion resistance was compared with single-layer 8YSZ. It was shown that the erosion resistance of 8YSZ single-layer TBC was higher than GZ-based multi-layered TBCs. Among the multi-layered TBCs, triple-layer TBC was slightly better than double layer in terms of erosion resistance. The eroded TBCs were cold-mounted and analyzed by SEM.

  17. Advanced Vacuum Plasma Spray (VPS) for a Robust, Longlife and Safe Space Shuttle Main Engine (SSME)

    Science.gov (United States)

    Holmes, Richard R.; Elam, Sandra K.; McKechnie, Timothy N.; Power, Christopher A.

    2010-01-01

    In 1984, the Vacuum Plasma Spray Lab was built at NASA/Marshall Space Flight Center for applying durable, protective coatings to turbine blades for the space shuttle main engine (SSME) high pressure fuel turbopump. Existing turbine blades were cracking and breaking off after five hot fire tests while VPS coated turbine blades showed no wear or cracking after 40 hot fire tests. Following that, a major manufacturing problem of copper coatings peeling off the SSME Titanium Main Fuel Valve Housing was corrected with a tenacious VPS copper coating. A patented VPS process utilizing Functional Gradient Material (FGM) application was developed to build ceramic lined metallic cartridges for space furnace experiments, safely containing gallium arsenide at 1260 degrees centigrade. The VPS/FGM process was then translated to build robust, long life, liquid rocket combustion chambers for the space shuttle main engine. A 5K (5,000 Lb. thrust) thruster with the VPS/FGM protective coating experienced 220 hot firing tests in pristine condition with no wear compared to the SSME which showed blanching (surface pulverization) and cooling channel cracks in less than 30 of the same hot firing tests. After 35 of the hot firing tests, the injector face plates disintegrated. The VPS/FGM process was then applied to spraying protective thermal barrier coatings on the face plates which showed 50% cooler operating temperature, with no wear after 50 hot fire tests. Cooling channels were closed out in two weeks, compared to one year for the SSME. Working up the TRL (Technology Readiness Level) to establish the VPS/FGM process as viable technology, a 40K thruster was built and is currently being tested. Proposed is to build a J-2X size liquid rocket engine as the final step in establishing the VPS/FGM process TRL for space flight.

  18. Effects of isothermal treatment on microstructure and scratch test behavior of plasma sprayed zirconia coatings

    Directory of Open Access Journals (Sweden)

    Veloso Guilherme

    2004-01-01

    Full Text Available The increase of the petroleum cost in the last decades revitalized the interest for lighter and more economic vehicles. Simultaneously, the demand for safe and unpolluted transports grows. The application of thermal barriers coatings (TBC on combustion chamber and on flat surface of pistons reduces the thermal losses of the engines, resulting in higher temperatures in the combustion chamber. This fact contributes to the improvement of the thermal efficiency (performance and for the reduction of incomplete combustion. Supported on these initial ideas, thermal barriers coatings constituted by CaO partially stabilized zirconia were produced and their microstructure examined. This coating still presents some drawbacks associated with thermal stresses and permeability to oxidizing gases, which will, eventually, lead to failure of the TBC by spallation. The failure may, in general, be associated to one of three factors: oxide growth at the ceramic-metal interface, formed during thermal cycling; stress build-up due to thermal cycling; and metal-oxide interface segregation, mainly of S. However, it is also relevant to understand the behavior of TBC's under isothermal oxidation. Therefore, this paper investigates the effect of oxidation on the adherence of thermal sprayed coatings. The adherence was measured by linear scratching tests, widely used for thin coatings. Plasma sprayed calcia partially stabilized zirconia was used as TBC and Ni-5%Al as bond coat, with Al substrates. Coated samples were submitted to heat treatments at 500 °C, for 50 h. The microstructures were examined by optical light microscopy, X-ray diffraction, profilometry and SEM.

  19. Unique relationship between osteophyte and femoral-tibia component size mismatch in determining polyethylene wear in primary total knee arthroplasty: a case report

    Directory of Open Access Journals (Sweden)

    Ramappa Manjunath

    2009-02-01

    Full Text Available Abstract Introduction Knee pain is a complex problem that can occur after total knee arthroplasty. One cause of knee pain may be due to a retained osteophyte, but it is not clear if the retained osteophyte is sufficient explanation of the pain, as not all patients with retained osteophytes are symptomatic. In fact, the literature shows that excised osteophytes can also recur over a period of time, without any symptoms. Therefore a retained osteophyte alone is probably not sufficient to cause symptoms. Case presentation We present a case of intermittent medial knee pain occurring post-primary total knee arthroplasty, in a patient who underwent several investigations over a period of 5 years. Radiographs showed an osteophyte in the postero-medial femur along with slight tibial component overhang which was normal for that knee implant design. The symptoms eventually settled with excision of only the osteophyte, without altering the tibial component. Conclusion A retained osteophyte alone, or tibial component overhang alone, did not seem to cause significant symptoms in our patient whose symptoms completely settled with excision of the osteophyte alone, without changing the tibial component. Therefore, it seems that the combination of retained osteophyte and tibial component overhang (tibia-femoral component size mismatch are detrimental and therefore best avoided. This report also emphasises the importance of meticulous osteophyte excision and avoiding tibial component overhang during knee arthroplasty.

  20. Influence of a powder feed rate on the properties of the plasma sprayed chromium carbide- 25% nickel chromium coating

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2014-04-01

    Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 The plasma spray process is a leading technology of powder depositing in the production of coatings widely used in the aerospace industry for the protection of new parts and for the repair of worn ones. Cermet 75Cr3C2 - 25Ni(Cr coatings based on Cr3C2 carbides are widely used to protect parts as they retain high values of hardness, strength and resistance to wear up to a temperature of 850°C. This paper discusses the influence of the parameters of the plasma spray deposition of 75Cr3C2 - 25Ni(Cr powder on the structure and mechanical properties of the coating. The powder is deposited using plasma spraying at atmospheric pressure (APS. The plasma gas is He, which is an inert gas and does not react with the powder; it produces dense plasma with lower heat content and less incorporated ambient air in the plasma jet thus reducing temperature decomposition and decarburization of Cr3C2 carbide.. In this study, three groups of coatings were deposited with three different powder feed rates of: 30, 45 and 60 g/min. The  coating with the best properties was deposited on the inlet flange parts of the turbo - jet engine TV2-117A to reduce the influence of vibrations and wear. The structures and the mechanical properties of 75Cr3C2 - 25Ni(Cr coatings are analyzed in accordance with the Pratt & Whitney standard. Studies have shown that powder feed rates have an important influence on the mechanical properties and structures of 75Cr3C2 - 25Ni(Cr coatings. 

  1. Study of the Porosity in Plasma-Sprayed Alumina through an Innovative Three-Dimensional Simulation of the Coating Buildup

    Science.gov (United States)

    Beauvais, S.; Guipont, V.; Jeandin, M.; Jeulin, D.; Robisson, A.; Saenger, R.

    2008-11-01

    Porosity is a key feature of a thermally sprayed coating microstructure. Within ceramic coatings, porosity is made of pores and cracks of various shapes, dimensions, and orientations. Cracks can be intralamellar or interlamellar due to the buildup of the coating, which leads to piled-up lamellae from impinging and the additional rapid solidification of liquid droplets. Pores are interconnected with cracks, which results in a three-dimensional (3-D) porosity network. Direct observation of this network is an intricate task and current attempts remain somewhat limited. A 3-D simulation of this network was, therefore, developed in this work, based on a stochastic approach to the building up of simulated lamellae in the sprayed microstructure. A library of mathematical objects was achieved from morphological measurements, using confocal microscopy of actual isolated flattened lamellae, i.e., “splats” and scanning electron microscopy (SEM). This stochastic approach to the simulation of hundreds of lamellae also involves the random distribution of cracks and pores. Simulation fit parameters were selected according to the overall characteristics of porosity ( i.e., content, orientation, size, etc.) that were determined from the thorough quantitative image analysis (QIA) of cross-sectioned plasma-sprayed alumina coatings. Two plasma modes that varied the atmosphere in a controlled-atmosphere plasma spraying (CAPS) chamber were applied, to produce the microstructures of two different alumina coatings. The 3-D random modeling tool allowed the processing of a volume of digital material through a 3-D simulated binary image of a two-phased composite material. Using one 3-D image result of the simulation, finite element (FE) calculations were performed, in order to study the overall dielectric properties of a plasma-sprayed alumina as a function of porosity. The influence of anisotropy is discussed, in particular, and both analytical and numerical predicted values were

  2. A systematic review on the long-term success of calcium phosphate plasma-spray-coated dental implants.

    Science.gov (United States)

    van Oirschot, B A J A; Bronkhorst, E M; van den Beucken, J J J P; Meijer, G J; Jansen, J A; Junker, R

    2016-09-01

    The objectives of the current review were (1) to systematically appraise, and (2) to evaluate long-term success data of calcium phosphate (CaP) plasma-spray-coated dental implants in clinical trials with at least 5 years of follow-up. To describe the long-term efficacy of functional implants, the outcome variables were (a) percentage annual complication rate (ACR) and (b) cumulative success rate (CSR), as presented in the selected articles. The electronic search yielded 645 titles. On the basis of the inclusion criteria, 8 studies were finally included. The percentage of implants in function after the first year was estimated to be 98.4 % in the maxilla and 99.2 % in the mandible. The estimates of the weighted mean ACR-percentage increased over the years up to 2.6 (SE 0.7) during the fifth year of function for the maxilla and to 9.4 (SE 8.4) for the mandible in the tenth year of function. After 10 years, the mean percentage of successful implants was estimated to be 71.1 % in the maxilla and 72.2 % in the mandible. The estimates seem to confirm the proposed, long-term progressive bone loss pattern of CaP-ceramic-coated dental implants. Within the limits of this meta-analytic approach to the literature, we conclude that: (1) published long-term success data for calcium phosphate plasma-spray-coated dental implants are limited, (2) comparison of the data is difficult due to differences in success criteria among the studies, and (3) long-term CSRs demonstrate very weak evidence for progressive complications around calcium phosphate plasma-spray-coated dental implants.

  3. Fireside Corrosion Behavior of HVOF and Plasma-Sprayed Coatings in Advanced Coal/Biomass Co-Fired Power Plants

    Science.gov (United States)

    Hussain, T.; Dudziak, T.; Simms, N. J.; Nicholls, J. R.

    2013-06-01

    This article presents a systematic evaluation of coatings for advanced fossil fuel plants and addresses fireside corrosion in coal/biomass-derived flue gases. A selection of four candidate coatings: alloy 625, NiCr, FeCrAl and NiCrAlY were deposited onto superheaters/reheaters alloy (T91) using high-velocity oxy-fuel (HVOF) and plasma spraying. A series of laboratory-based fireside corrosion exposures were carried out on these coated samples in furnaces under controlled atmosphere for 1000 h at 650 °C. The tests were carried out using the "deposit-recoat" test method to simulate the environment that was anticipated from air-firing 20 wt.% cereal co-product mixed with a UK coal. The exposures were carried out using a deposit containing Na2SO4, K2SO4, and Fe2O3 to produce alkali-iron tri-sulfates, which had been identified as the principal cause of fireside corrosion on superheaters/reheaters in pulverized coal-fired power plants. The exposed samples were examined in an ESEM with EDX analysis to characterize the damage. Pre- and post-exposure dimensional metrologies were used to quantify the metal damage in terms of metal loss distributions. The thermally sprayed coatings suffered significant corrosion attack from a combination of aggressive combustion gases and deposit mixtures. In this study, all the four plasma-sprayed coatings studied performed better than the HVOF-sprayed coatings because of a lower level of porosity. NiCr was found to be the best performing coating material with a median metal loss of ~87 μm (HVOF sprayed) and ~13 μm (plasma sprayed). In general, the median metal damage for coatings had the following ranking (in the descending order: most to the least damage): NiCrAlY > alloy 625 > FeCrAl > NiCr.

  4. Dual-Layer Oxidation-Protective Plasma-Sprayed SiC-ZrB2/Al2O3-Carbon Nanotube Coating on Graphite

    Science.gov (United States)

    Ariharan, S.; Sengupta, Pradyut; Nisar, Ambreen; Agnihotri, Ankur; Balaji, N.; Aruna, S. T.; Balani, Kantesh

    2017-02-01

    Graphite is used in high-temperature gas-cooled reactors because of its outstanding irradiation performance and corrosion resistance. To restrict its high-temperature (>873 K) oxidation, atmospheric-plasma-sprayed SiC-ZrB2-Al2O3-carbon nanotube (CNT) dual-layer coating was deposited on graphite substrate in this work. The effect of each layer was isolated by processing each component of the coating via spark plasma sintering followed by isothermal kinetic studies. Based on isothermal analysis and the presence of high residual thermal stress in the oxide scale, degradation appeared to be more severe in composites reinforced with CNTs. To avoid the complexity of analysis of composites, the high-temperature activation energy for oxidation was calculated for the single-phase materials only, yielding values of 11.8, 20.5, 43.5, and 4.5 kJ/mol for graphite, SiC, ZrB2, and CNT, respectively, with increased thermal stability for ZrB2 and SiC. These results were then used to evaluate the oxidation rate for the composites analytically. This study has broad implications for wider use of dual-layer (SiC-ZrB2/Al2O3) coatings for protecting graphite crucibles even at temperatures above 1073 K.

  5. The Effect of Plasma Spraying on the Microstructure and Aging Kinetics of the Al-Si Matrix Alloy and Al-Si/SiC Composites

    Science.gov (United States)

    Altunpak, Yahya; Akbulut, Hatem; Üstel, Fatih

    2010-02-01

    The Al-Si (LM 13)-based matrix alloy reinforced with SiC particles containing 10, 20, and 30 vol.% SiC particles were spray-formed onto Al-Si substrates. The sprayed samples were directly subjected to a standard aging treatment (T551). From the experiments, it was observed that the high rate of solidification resulted in very fine silicon particles which were observed as continuous islands in the matrix and each island exhibited several very fine silicon crystals. Analysis showed that plasma-spraying caused an increased solid solubility of the silicon in the aluminum matrix. DSC measurements in the permanent mold-cast Al-Si matrix alloy and plasma-sprayed Al-Si matrix alloy showed that plasma-spraying causes an increase in the amount of GP-zone formation owing to the very high rate solidification after plasma-spraying. In the plasma-sprayed Al-Si/SiC composites GP zones were suppressed, since particle-matrix interfaces act as a sink for vacancies during quenching from high plasma process temperature. Introduction of SiC particles to the Al-Si age-hardenable alloy resulted in a decrease in the time required to reach plateau matrix hardness owing to acceleration of aging kinetics by ceramic SiC particles.

  6. Prediction and optimization of process variables to maximize the Young's modulus of plasma sprayed alumina coatings on AZ31B magnesium alloy

    Directory of Open Access Journals (Sweden)

    D. Thirumalaikumarasamy

    2017-03-01

    Full Text Available Like other manufacturing techniques, plasma spraying has also a non-linear behavior because of the contribution of many coating variables. This characteristic results in finding optimal factor combination difficult. Subsequently, the issue can be solved through effective and strategic statistical procedures integrated with systematic experimental data. Plasma spray parameters such as power, stand-off distance and powder feed rate have significant influence on coating characteristics like Young's modulus. This paper presents the use of statistical techniques in specifically response surface methodology (RSM, analysis of variance, and regression analysis to develop empirical relationship to predict Young's modulus of plasma-sprayed alumina coatings. The developed empirical relationships can be effectively used to predict Young's modulus of plasma-sprayed alumina coatings at 95% confidence level. Response graphs and contour plots were constructed to identify the optimum plasma spray parameters to attain maximum Young's modulus in alumina coatings. A linear regression relationship was established between porosity and Young's modulus of the alumina coatings.

  7. Mechanical properties and microstructure of vaccum plasma sprayed Cr3C2 - 25(Ni20Cr) coatings

    OpenAIRE

    MRDAK MIHAILO R.

    2015-01-01

    This paper analyzes vacuum plasma spray VPS - Cr3C2 - 25(Ni20Cr) coatings. Commercial powder marked Sulzer Metco Woka 7205 is used. The powder is deposited with a plasma gun F4 at a distance of 340 mm from the substrate. The main objective of the study was to eliminate, at the reduced pressure of inert gas Ar, the degradation of primary Cr3C2 carbide into Cr23C6 carbide which significantly reduces the microhardness and mechanical properties of the coating. The coating is deposited with a thic...

  8. Some adhesion/cohesion characteristics of plasma-sprayed ZrO2-Y2O3 under tensile loading

    Science.gov (United States)

    Mullen, Robert L.; Vlcek, Brian L.; Hendricks, Robert C.; Mcdonald, Glen

    1987-01-01

    A set of 12.7 mm diameter stainless steel tubes were coated with ceramic and expanded. The bond cast was 0.08 to 0.13 mm NiCrAlY with 0.38 mm of ZrO2-8Y2O3 ceramic. Upon pressurization, the tube substrate yielded and overstressed the coatings in tension. The coatings cracked (i.e., they failed) but did not come off the tube. These results demonstrate that tensile failure of plasma-sprayed coatings is not catastrophic as is compressive failure, which leads to spallation.

  9. Effect of Dry-Ice Blasting on Structure and Magnetic Properties of Plasma-Sprayed Fe-40Al Coating from Nanostructured Powders

    Science.gov (United States)

    Song, Bo; Dong, Shujuan; Hansz, Bernard; Liao, Hanlin; Coddet, Christian

    2014-01-01

    Amorphous and nanocrystalline materials have attracted much interest in the field of new materials design because of their excellent mechanical and physical properties as well as their magnetic properties. In this work, Fe-40Al coatings were prepared from a nanostructured feedstock by atmospheric plasma spray combined with dry-ice blasting. The scanning electron microscopy, x-ray diffraction, tensile test, and magnetic measurements were used to investigate microstructure, phase structure, adhesion, and magnetic properties of the deposited coatings. The results showed that after using dry-ice blasting, the oxidation and porosity decreased and the atmospheric plasma-sprayed Fe-40Al coatings exhibited a soft ferromagnetic character with lower coercivity and higher saturation magnetization due to their lower degree of order. The plasma-sprayed Fe-40Al coating from the nanostructured feedstock has a very high adhesive strength.

  10. One-Step Synthesis of Pt/Graphene Composites from Pt Acid Dissolved Ethanol via Microwave Plasma Spray Pyrolysis

    Science.gov (United States)

    Jo, Eun Hee; Chang, Hankwon; Kim, Sun Kyung; Choi, Ji-Hyuk; Park, Su-Ryeon; Lee, Chong Min; Jang, Hee Dong

    2016-09-01

    Pt nanoparticles-laden graphene (Pt/GR) composites were synthesized in the gas phase from a mixture of ethanol and Pt precursor by microwave plasma spray pyrolysis. The morphology of Pt/GR composites has the shape of wrinkled sheets of paper, while Pt nanoparticles (Pt NPs) that are less than 2.6 nm in the mean diameter are uniformly well deposited on the surface of GR sheets stacked in only three layers. The Pt/GR composite prepared with 20 wt% of Pt had the highest specific surface area and electrochemical surface area of up to 402 m2 g-1 and 77 m2 g-1 (Pt), respectively. In addition, the composite showed superior electrocatalytic activity compared with commercial Pt-carbon black. The excellent electrocatalytic activity was attributed to the high specific surface area and electrochemical surface area of the Pt/GR composite directly produced by microwave plasma spray pyrolysis. Thus, it is clearly expected that the Pt/GR composite is a promising material for DMFC catalysts.

  11. In vitro corrosion investigations of plasma-sprayed hydroxyapatite and hydroxyapatite–calcium phosphate coatings on 316L SS

    Indian Academy of Sciences (India)

    Gurpreet Singh; Hazoor Singh; Buta Singh Sidhu

    2014-10-01

    The present paper discusses various issues associated with biological corrosion of uncoated and plasma-sprayed hydroxyapatite (HA)-coated 316L SS and studies the effect of contents of calcium phosphate (CaP) on corrosion behaviour of hydroxyapatite (HA) coatings in simulated body fluid (Ringer’s solution). Three types of coatings, i.e. HA + 20 wt% CaP (type 1), HA + 10 wt% CaP (type 2), HA (type 3), were laid on 316L SS using plasma-spraying technique. Structural characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to investigate the crystallinity, microstructure and morphology of the coatings. Electrochemical potentiodynamic tests were performed to determine the corrosion resistance of uncoated and all the three coatings. After the electrochemical corrosion testing, the samples were examined by XRD, SEM and EDX. The electrochemical study showed a significant improvement in the corrosion resistance after HA coating and corrosion resistance of type 3 coating was found maximum.

  12. Modeling the impact, flattening and solidification of a molten droplet on a solid substrate during plasma spraying

    Science.gov (United States)

    Zheng, Y. Z.; Li, Q.; Zheng, Z. H.; Zhu, J. F.; Cao, P. L.

    2014-10-01

    It is quite important to clearly understand the dynamic process of single splat formation for optimizing the plasma spraying process. In present study, a three-dimensional model including heat transfer and phase change was developed on Ansys Fluent 14 platform to simulate the impact, flattening and solidification of a molten droplet on a solid substrate during plasma spraying. The phase, contact pressure, temperature and velocity fields at different spreading times were presented to gain an insight into splat formation mechanism. The predicted splat morphology was in good agreement with the experimental photos. The effect of mushy zone constant, a parameter dominating the solidification behavior of fluid in Fluent, on the flattening of droplet was further investigated. Through comparing the calculated spread factor from present model with the experimental value, a mushy zone constant of 108 or 109 was found to be more appropriate for simulation on the solidification problem occurring in high-speed impact and flattening process, instead of the range of 104-107 recommended in Fluent.

  13. Atmospheric plasma sprayed (APS) coatings of Al2O3-TiO2 system for photocatalytic application.

    Science.gov (United States)

    Stengl, V; Ageorges, H; Ctibor, P; Murafa, N

    2009-05-01

    The goal of this study is to examine the photocatalytic ability of coatings produced by atmospheric plasma spraying (APS). The plasma gun used is a common gas-stabilized plasma gun (GSP) working with a d.c. current and a mixture of argon and hydrogen as plasma-forming gas. The TiO(2) powders are particles of about 100 nm which were agglomerated to a mean size of about 55 mum, suitable for spraying. Composition of the commercial powder is 13 wt% of TiO(2) in Al(2)O(3), whereas also in-house prepared powder with the same nominal composition but with agglomerated TiO(2) and conventional fused and crushed Al(2)O(3) was sprayed. The feedstock materials used for this purpose are alpha-alumina and anatase titanium dioxide. The coatings are analyzed by scanning electron microscopy (SEM), energy dispersion probe (EDS) and X-ray diffraction. Photocatalytic degradation of acetone is quantified for various coatings. All plasma sprayed coatings show a lamellar structure on cross section, as typical for this process. Anatase titania from feedstock powder is converted into rutile titania and alpha-alumina partly to gamma-alumina. Coatings are proven to catalyse the acetone decomposition when irradiated by UV rays.

  14. Comparison of ZrB2-MoSi2 Composite Coatings Fabricated by Atmospheric and Vacuum Plasma Spray Processes

    Science.gov (United States)

    Niu, Yaran; Wang, Zhong; Zhao, Jun; Zheng, Xuebin; Zeng, Yi; Ding, Chuanxian

    2016-12-01

    In this work, ZrB2-20 vol.% MoSi2 (denoted as ZM) composite coatings were fabricated by atmospheric plasma spray (APS) and vacuum plasma spray (VPS) techniques, respectively. Phase composition and microstructure of the composite coatings were characterized. Their oxidation behaviors and microstructure changes at 1500 °C were comparatively investigated. The results showed that VPS-ZM coating was composed of hexagonal ZrB2, tetragonal and hexagonal MoSi2, while certain amount of ZrO2 existed in APS-ZM coating. The oxide content, surface roughness and porosity of VPS-ZM coating were apparently lower than those of APS-ZM coating. The mass gain of APS-ZM coating was maximum at the beginning (1500 °C, 0 h) and then decreased with the oxidation time extending, while the mass of VPS-ZM coating gradually increased with increasing the oxidation time. The possible reasons for the different oxidation behaviors of the two kinds of coatings were analyzed.

  15. La2NiO4+δ Infiltration of Plasma-Sprayed LSCF Coating for Cathode Performance Improvement

    Science.gov (United States)

    Li, Ying; Zhang, Shan-Lin; Li, Cheng-Xin; Wei, Tao; Yang, Guan-Jun; Li, Chang-Jiu; Liu, Meilin

    2016-01-01

    Perovskite-structured (La0.6Sr0.4Co0.2Fe0.8O3) LSCF has been widely studied as a cathode material for intermediate-temperature solid oxide fuel cells. However, the application of LSCF cathode is likely to be limited by its sluggish surface catalytic properties and long-term stability issues. Oxygen hyper-stoichiometric La2NiO4+δ with K2NiF4 structure exhibits higher catalytic properties, ionic conductivity, and stability in comparison with LSCF cathode. Due to the good chemical compatibility of these two cathode materials, it is possible to prepare a composite cathode by the infiltration of La2NiO4+δ in the porous LSCF. This composite structure fully utilizes the advantages of the two cathodes and enhances the LSCF cathode performance. In this study, the LSCF cathode was deposited by using an atmospheric plasma spray technique, and the porous LSCF cathode was then infiltrated by La2NiO4+δ. The atmospheric plasma spray technique was used to reduce the SOFC manufacturing cost. The microstructure of coatings was characterized by SEM and EDS. The cathode polarization resistance was found to decrease by ~40% after the La2NiO4+δ infiltration. Also, the activation energy decreased from 1.53 to 1.40 eV.

  16. Modification of vacuum plasma sprayed tungsten coating on reduced activation ferritic/martensitic steels by friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Tanigawa, Hiroyasu, E-mail: tanigawa.hiroyasu@jaea.go.jp [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Ozawa, Kazumi [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Morisada, Yoshiaki [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka (Japan); Noh, Sanghoon [Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori (Japan); Nuclear Material Development Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka (Japan)

    2015-10-15

    Highlights: • Friction stir processing (FSP) was applied on vacuum plasma spray (VPS) W to improve its low thermal conductivity and weakness due to high porosity. • FSP can achieve significant improvement both in mechanical and thermal properties of VPS-W coating. • It was indicated that the double pass FSP at 600 rpm/50 mm/min/2 ton on VPS-W show the most dense microstructure and hardest mechanical property. • Hardness test over FSPed VPS-W layer revealed that the hardness of W becomes higher than that of bulk W. • The thermal conductivity of double pass FSPed VPS-W was about 80% of bulk W at 200 °C, and it becomes equivalent to that of bulk W over 800 °C. - Abstract: Tungsten (W) is the primary candidate material as a plasma facing material in fusion devices, as for its high melting temperature, good thermal conductivity and low sputtering rate, and vacuum plasma spray (VPS) technique is preferred as it is applicable for large area without brittle interlayer, but the thermal conductivity of W layer is very poor, and easy to detach, mainly caused by its porous structure. W Friction stir processing (FSP) was applied on VPS-W to improve these poor properties, and it was suggested that FSP can contribute to significant improvement in both mechanical and thermal properties of the VPS-W coating.

  17. Thermal Fatigue Behavior of Air-Plasma Sprayed Thermal Barrier Coating with Bond Coat Species in Cyclic Thermal Exposure

    Directory of Open Access Journals (Sweden)

    Ungyu Paik

    2013-08-01

    Full Text Available The effects of the bond coat species on the delamination or fracture behavior in thermal barrier coatings (TBCs was investigated using the yclic thermal fatigue and thermal-shock tests. The interface microstructures of each TBC showed a good condition without cracking or delamination after flame thermal fatigue (FTF for 1429 cycles. The TBC with the bond coat prepared by the air-plasma spray (APS method showed a good condition at the interface between the top and bond coats after cyclic furnace thermal fatigue (CFTF for 1429 cycles, whereas the TBCs with the bond coats prepared by the high-velocity oxygen fuel (HVOF and low-pressure plasma spray (LPPS methods showed a partial cracking (and/or delamination and a delamination after 780 cycles, respectively. The TBCs with the bond coats prepared by the APS, HVOF and LPPS methods were fully delaminated (>50% after 159, 36, and 46 cycles, respectively, during the thermal-shock tests. The TGO thickness in the TBCs was strongly dependent on the both exposure time and temperature difference tested. The hardness values were found to be increased only after the CFTF, and the TBC with the bond coat prepared by the APS showed the highest adhesive strength before and after the FTF.

  18. Effect of TiB2 Additives on Wear Behavior of NiCrBSi-Based Plasma-Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Oleksandr UMANSKYI

    2016-05-01

    Full Text Available The influence of titanium diboride additives on microstructure and wear-resistance of NiCrBSi thermally sprayed coatings deposited on a steel substrate has been studied. NiCrBSi-based composite powders with 10, 20, 40 wt.% TiB2 particles content were produced. The structure of NiCrSiB-TiB2 coatings consists of TiB2 and CrB grains distributed in Ni-based matrix. The wear-resistance of NiCrSiB-TiB2 plasma sprayed coatings in dry sliding conditions against the same coating using pin-on-disk tester. It was determined that the amount of titanium diboride particles in  NiCrBSi-based coatings influences essentially on the wear  resistance and wear mechanism. The NiCrBSi-based plasma sprayed coatings containing 20 wt. % of TiB2 possess the highest wear resistance due to the realization of mechano-oxidational wear mechanism.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7307

  19. Influence of Oxidation Behavior of Feedstock on Microstructure and Ablation Resistance of Plasma-Sprayed Zirconium Carbide Coating

    Science.gov (United States)

    Hu, Cui; Ge, Xuelian; Niu, Yaran; Li, Hong; Huang, Liping; Zheng, Xuebin; Sun, Jinliang

    2015-10-01

    Plasma spray is one of the suitable technologies to deposit carbide coatings with high melting point, such as ZrC. However, in the spray processes performed under atmosphere, oxidation of the carbide powder is inevitable. To investigate the influence of the oxidation behavior of feedstock on microstructure and ablation resistance of the deposited coating, ZrC coatings were prepared by atmospheric and vacuum plasma spray (APS and VPS) technologies, respectively. SiC-coated graphite was applied as the substrate. The obtained results showed that the oxidation of ZrC powder in APS process resulted in the formation of ZrO and Zr2O phases. Pores and cracks were more likely to be formed in the as-sprayed APS-ZrC coating. The VPS-ZrC coating without oxides possessed denser microstructure, higher thermal diffusivity, and lower coefficients of thermal expansion as compared with the APS-ZrC coating. A dense ZrO2 layer would be formed on the surface of the VPS-ZrC-coated sample during the ablation process and the substrate can be protected sufficiently after being ablated in high temperature plasma jet. However, the ZrO2 layer, formed by oxidation of the APS-ZrC coating having loose structure, was easy to be washed away by the shearing action of the plasma jet.

  20. Influence of Cold-Sprayed, Warm-Sprayed, and Plasma-Sprayed Layers Deposition on Fatigue Properties of Steel Specimens

    Science.gov (United States)

    Cizek, J.; Matejkova, M.; Dlouhy, I.; Siska, F.; Kay, C. M.; Karthikeyan, J.; Kuroda, S.; Kovarik, O.; Siegl, J.; Loke, K.; Khor, Khiam Aik

    2015-06-01

    Titanium powder was deposited onto steel specimens using four thermal spray technologies: plasma spray, low-pressure cold spray, portable cold spray, and warm spray. The specimens were then subjected to strain-controlled cyclic bending test in a dedicated in-house built device. The crack propagation was monitored by observing the changes in the resonance frequency of the samples. For each series, the number of cycles corresponding to a pre-defined specimen cross-section damage was used as a performance indicator. It was found that the grit-blasting procedure did not alter the fatigue properties of the steel specimens (1% increase as compared to as-received set), while the deposition of coatings via all four thermal spray technologies significantly increased the measured fatigue lives. The three high-velocity technologies led to an increase of relative lives to 234% (low-pressure cold spray), 210% (portable cold spray), and 355% (warm spray) and the deposition using plasma spray led to an increase of relative lives to 303%. The observed increase of high-velocity technologies (cold and warm spray) could be attributed to a combination of homogeneous fatigue-resistant coatings and induction of peening stresses into the substrates via the impingement of the high-kinetic energy particles. Given the intrinsic character of the plasma jet (low-velocity impact of semi/molten particles) and the mostly ceramic character of the coating (oxides, nitrides), a hypothesis based on non-linear coatings behavior is provided in the paper.

  1. Trunnion Corrosion and Early Failure in Monolithic Metal-on-Polyethylene TMZF Femoral Components: A Case Series

    Directory of Open Access Journals (Sweden)

    Peter Walker

    2016-09-01

    Full Text Available We describe four patients who were treated with primary total hip arthroplasty (THA at two tertiary academic Australian teaching hospitals that experienced premature failure of head-neck trunnions through dissociation of the head-neck taper junction. This retrospective case series have similar clinical presentations and macroscopic pathology with severe head-neck taper junction loss of material, corrosion and early catastrophic failure. It is proposed that the accelerated wear is related to use of varus offset neck in a proprietary beta titanium alloy (Ti-12Mo-6Zr-2Fe  or TMZFÒ Stryker Osteonics, Mahwah NJ, USA TMZF femoral stem, longer head-neck combination in a relatively active, older, male patient population. In this limited case series presentation was on average 80 months (range 53-92 following index procedure. In three of the four patients, a prodromal period of groin or buttock pain was reported for between 1 week and 2 months prior to acute presentation. Significant metallosis and local tissue damage including gluteal muscle insufficiency was evident. Each stem revised was well fixed. An extended trochanteric osteotomy was required in two of the four cases for stem extraction. We recommend caution and further evaluation on the relationship between TMZF metal alloy and its longevity in higher demand patients with high neck offset, varus stem geometry and large CoCr bearing heads.

  2. Do post-operative changes of neck-shaft angle and femoral component anteversion have an effect on clinical outcome following uncemented total hip arthroplasty?

    Science.gov (United States)

    Müller, M; Abdel, M P; Wassilew, G I; Duda, G; Perka, C

    2015-12-01

    The accurate reconstruction of hip anatomy and biomechanics is thought to be important in achieveing good clinical outcomes following total hip arthroplasty (THA). To this end some newer hip designs have introduced further modularity into the design of the femoral component such that neck-shaft angle and anteversion, which can be adjusted intra-operatively. The clinical effect of this increased modularity is unknown. We have investigated the changes in these anatomical parameters following conventional THA with a prosthesis of predetermined neck-shaft angle and assessed the effect of changes in the hip anatomy on clinical outcomes. In total, 44 patients (mean age 65.3 years (standard deviation (SD) 7); 17 male/27 female; mean body mass index 26.9 (kg/m²) (SD 3.1)) underwent a pre- and post-operative three-dimensional CT scanning of the hip. The pre- and post-operative neck-shaft angle, offset, hip centre of rotation, femoral anteversion, and stem alignment were measured. Additionally, a functional assessment and pain score were evaluated before surgery and at one year post-operatively and related to the post-operative anatomical changes. The mean pre-operative neck-shaft angle was significantly increased by 2.8° from 128° (SD 6.2; 119° to 147°) to 131° (SD 2.1; 127° to 136°) (p = 0.009). The mean pre-operative anteversion was 24.9° (SD 8; 7.9 to 39.1) and reduced to 7.4° (SD 7.3; -11.6° to 25.9°) post-operatively (p neck-shaft angles was found with a significant decrease of the post-operative anteversion and slight increase of the neck-shaft angles, but without any impact on clinical outcome.

  3. Significance of in-situ dry-ice blasting on the microstructure, crystallinity and bonding strength of plasma-sprayed hydroxyapatite coatings.

    Science.gov (United States)

    Dong, Shujuan; Zeng, Jinyan; Li, Lifen; Sun, Junbin; Yang, Xiong; Liao, Hanlin

    2017-03-07

    To obtain hydroxyapatite (HA) coatings with high crystallinity which have long-term stability in clinical applications, coarse powders were usually injected to less energetic plasma. However, the HA coatings accumulated by partly melted particles usually have high porosity and poor mechanical properties, especially poor bonding strength. In this work, by profiting its quenching and mechanical impact, dry-ice blasting was in-situ employed during plasma spray process to improve the microstructure characterization and bonding strength of HA coatings. In addition, the influence of in-situ dry-ice blasting on the phase composition and crystallinity of plasma-sprayed HA coatings was investigated. The results show that a significant reduction of porosity and an apparent increase in bonding strength are revealed in plasma-sprayed HA coatings due to the cleaning effect of dry-ice blasting on the convex unmelted particles and splashing fragments. HA coatings prepared by the combination process of plasma spraying and dry-ice blasting have a compromise structure with minimum globular pores but with pronounced microcracks. The disappearance of CaO phase and the increase in crystallinity also derive from the application of dry-ice blasting.

  4. Surface Coating of NiTi Shape Memory Alloys with Calcium Phosphates by Dip-coating or Plasma-spraying-biological Characterization Examined by in vitro Testing Methods

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The influence of different surface coatings of NiTi shape memory alloys was examined using in vitro testing methods. Plates of superelastic nickel-titanium shape memory alloy (NiTi) were coated with calcium phosphates (hydroxyapatite) by high-temperature plasma-spraying or by dip-coating. The biocompatibility was tested in vitro by cultivation of isolated human granulocytes and whole blood cells. As substrates, pure NiTi,plasma-spray-coated NiTi and dip-coated NiTi were used. Isolated granulocytes showed an increased adhesion to both calcium phosphate-coated NiTi samples. Compared to non-coated NiTi or dip-coated NiTi, the number of dead granulocytes adherent to plasma-sprayed surfaces was significantly increased (p < 0.01). Whether the differences in apoptosis of granulocytes on dip-coated vs plasma-sprayed coatings observed are due to differences in material surface morphologies bas to be analyzed in further studies. Because of the cellular interactions with the coating layers, it is likely that the results obtained are not caused by the underlying NiTi but due to the coating itself.

  5. Induction of osteoconductivity by BMP-2 gene modification of mesenchymal stem cells combined with plasma-sprayed hydroxyapatite coating

    Science.gov (United States)

    Wu, Jiang; Guo, Ying-qiang; Yin, Guang-fu; Chen, Huai-qing; Kang, Yunqing

    2008-11-01

    Success in bone implant depends greatly on the composition and surface features of the implant. The surface-modification measures not only favor the implant's osteoconductivity, but also promote both bone anchoring and biomechanical stability. This paper reports an approach to combine a hydroxyapatite (HA) coated substrate with a cellular vehicle for the delivery of bone morphogenetic protein-2 (BMP-2) synergistically enhancing the osteoconductivity of implant surfaces. We examined the attachment, growth and osteoinductive activity of transfected BMP-producing bone marrow mesenchymal stem cells (BMSCs) on a plasma-sprayed HA coated substrate. It was found that the HA coated substrate could allow the attachment and growth of BMP-2 gene modified BMSCs, and this combined application synergistically enhanced osteconductivity of the substrate surface. This synergistic method may be of osseointegration value in orthopedic and dental implant surgery.

  6. Suspension Plasma-Sprayed ZnFe2O4 Nanostructured Coatings for ppm-Level Acetone Detection

    Science.gov (United States)

    You, Jiajun; Chen, Xia; Zheng, Bingbing; Geng, Xin; Zhang, Chao

    2017-02-01

    Zinc ferrite (ZnFe2O4) sensitive coatings have been deposited by suspension plasma spraying. The phase constitution of the coatings was characterized by x-ray diffraction while the top surface and cross-sectional morphology of the coatings were inspected by scanning electron microscopy. The response to acetone was tested with the concentration in the range of 25-500 ppm at the working temperature from 175 to 275 °C. The sensors that were deposited at an arc current of 400 A showed better performance than those at 600 A owing to small grain size and high porosity. The sensor response increased with acetone concentration. The optimized sensors showed excellent response/recovery time and selectivity to acetone at 200 °C.

  7. Deposition and properties of high-velocity-oxygen-fuel and plasma-sprayed Mo-Mo2C composite coatings

    Science.gov (United States)

    Prchlik, L.; Gutleber, J.; Sampath, S.

    2001-12-01

    Molybdenum thermal-spray coatings, dispersion strengthened by molybdenum oxides and molybdenum carbides, play an important role in industrial tribological applications. Traditionally, they have been prepared by plasma and wire flame spraying. High porosity and lower cohesion strength limit their application in situations where both galling and abrasion wear is involved. In this study, high-velocity-oxygen-fuel (HVOF) deposition of molybdenum and molybdenum carbide coatings was attempted. Deposition was achieved for all powders used. Composition, microstructure, mechanical, and wear properties of the HVOF synthesized coatings were evaluated and compared with plasma-sprayed counterparts. The HVOF coatings possessed a very good abrasion resistance, whereas plasma deposits performed better in dry sliding tests. Measurements showed a close relationship between the coating surface hardness and its abrasion resistance. Results also suggested correlation between molybdenum carbide distribution in the molybdenum matrix and the sliding friction response of Mo-Mo2C coatings.

  8. Electrochemical corrosion and metal ion release from Co-Cr-Mo prosthesis with titanium plasma spray coating.

    Science.gov (United States)

    Reclaru, Lucien; Eschler, Pierre-Yves; Lerf, Reto; Blatter, Andreas

    2005-08-01

    The corrosion behavior of CoCrMo implants with rough titanium coatings, applied by different suppliers by either sintering or vacuum plasma spraying, has been evaluated and compared with uncoated material. The open-circuit potential, corrosion current and polarization resistance were determined by electrochemical techniques. The Co, Cr and Ti ions released from the samples into the electrolyte during a potentiostatic extraction technique were analyzed using ICP-MS. The Ti coatings from the different suppliers showed a different porous morphology, and the implants exhibited a distinct corrosion activity, underlining the importance of the coating process parameters. Among the titanium coated samples, the one with the sintered overcoat turned out to be the most resistant. Yet, on an absolute scale, they all showed a corrosion resistance inferior to that of uncoated CoCrMo or wrought titanium.

  9. Evaluation of the behavior of shrouded plasma spray coatings in the platen superheater of coal-fired boilers

    Science.gov (United States)

    Sidhu, Buta Singh; Prakash, S.

    2006-06-01

    Nickel- and cobalt-based coatings were formulated by a shrouded plasma spray process on boiler tube steels, namely, ASTM-SA210-grade A1 (GrA1), ASTM-SA213-T-11 (T11), and ASTM-SA213-T-22 (T22). The Ni-22Cr-10Al-1Y alloy powder was sprayed as a bond in each case before the final coating. The degradation behavior of the bared and coated steels was studied in the platen superheater of the coal-fired boiler. The samples were inserted through the soot blower dummy points with the help of stainless steel wires. The coatings were found to be effective in increasing resistance to degradation in the given boiler environment. The maximum protection was observed in the case of Stellite-6 (St-6) coating.

  10. Evaluation of the behavior of shrouded plasma spray coatings in the platen superheater of coal-fired boilers

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, B.S.; Prakash, S. [GZS College of Engineering & Technology, Bathinda (India). Dept. of Mechanical Engineering

    2006-06-15

    Nickel- and cobalt-based coatings were formulated by a shrouded plasma spray process on boiler tube steels, namely, ASTM-SA210-grade A1 (GrA1), ASTM-SA213-T-11 (T11), and ASTM-SA213-T-22 (T22). The Ni-22Cr-10A1-1Y alloy powder was sprayed as a bond in each case before the final coating. The degradation behavior of the bared and coated steels was studied in the platen superheater of the coal-fired boiler. The samples were inserted through the soot blower dummy points with the help of stainless steel wires. The coatings were found to be effective in increasing resistance to degradation in the given boiler environment. The maximum protection was observed in the case of Stellite-6 (St-6) coating.

  11. Optimizing Compliance and Thermal Conductivity of Plasma Sprayed Thermal Barrier Coatings via Controlled Powders and Processing Strategies

    Science.gov (United States)

    Tan, Yang; Srinivasan, Vasudevan; Nakamura, Toshio; Sampath, Sanjay; Bertrand, Pierre; Bertrand, Ghislaine

    2012-09-01

    The properties and performance of plasma-sprayed thermal barrier coatings (TBCs) are strongly dependent on the microstructural defects, which are affected by starting powder morphology and processing conditions. Of particular interest is the use of hollow powders which not only allow for efficient melting of zirconia ceramics but also produce lower conductivity and more compliant coatings. Typical industrial hollow spray powders have an assortment of densities resulting in masking potential advantages of the hollow morphology. In this study, we have conducted process mapping strategies using a novel uniform shell thickness hollow powder to control the defect microstructure and properties. Correlations among coating properties, microstructure, and processing reveal feasibility to produce highly compliant and low conductivity TBC through a combination of optimized feedstock and processing conditions. The results are presented through the framework of process maps establishing correlations among process, microstructure, and properties and providing opportunities for optimization of TBCs.

  12. Numerical study of the spreading and solidification of a molten particle impacting onto a rigid substrate under plasma spraying conditions

    Directory of Open Access Journals (Sweden)

    Oukach Soufiane

    2015-01-01

    Full Text Available This paper deals with simulation of the spreading and solidification of a fully molten particle impacting onto a preheated substrate under traditional plasma spraying conditions. The multiphase problem governing equations of mass, momentum and energy conservation taking into account heat transfer by conduction, convection and phase change are solved by using a Finite Element approach. The interface between molten particle and surrounding air, is tracked using the Level Set method. The effect of the Reynolds number on the droplet spreading and solidification, using a wide range of impact velocities (40-250m/s, is reported. A new correlation that predicts the final spread factor of splat as a function of Reynolds number is obtained. Thermal contact resistance, viscous dissipation, wettability and surface tension forces effects are taken into account.

  13. Creep behavior of plasma sprayed NiCr and NiCrAl coating-based systems

    Institute of Scientific and Technical Information of China (English)

    Xiancheng ZHANG; Changjun LIU; Fuzhen XUAN; Zhengdong WANG; Shan-Tung TU

    2011-01-01

    The creep behavior of the plasma sprayed NiCr and NiCrAl coating/Nickel alloy 690substrate systems at 1033 K was investigated. Results showed that there was almost no difference in the creep lives between the NiCr and NiCrAl coated specimens at a given stress level, since the contents of Cr used in the NiCr and NiCrAl powders are almost same. The relationship between the minimum creep rate and the applied stress followed the well-known Norton's power law, εmin=Aσn, with the values of A=2.66× 10-16 Mpa-n.h-1 and n=6.48. The relation between the applied stress and time to rupture of the coated specimens can be estimated by using Larson-Miller equation. The θ projection method can be used to accurately characterize the creep behavior of the coated specimens.

  14. Apatite formation on alkaline-treated dense TiO2 coatings deposited using the solution precursor plasma spray process.

    Science.gov (United States)

    Chen, Dianying; Jordan, Eric H; Gell, Maurice; Wei, Mei

    2008-05-01

    A dense titania (TiO2) coating was deposited from an ethanol-based solution containing titanium isopropoxide using the solution precursor plasma spray (SPPS) process. XRD and Raman spectrum analyses confirmed that the coating is exclusively composed of rutile TiO2. SEM micrographs show the as-sprayed coating is dense with a uniform thickness and there are no coarse splat boundaries. The as-sprayed coating was chemically treated in 5M NaOH solution at 80 degrees C for 48 h. The bioactivity of as-sprayed and alkaline-treated coatings was investigated by immersing the coatings in simulated body fluid (SBF) for 14-28 days, respectively. After 28 days immersion, there is a complete layer of carbonate-containing apatite formed on the alkaline-treated TiO2 coating surface, but none formed on the as-sprayed coating.

  15. High Temperature Thermal Properties of Columnar Yttria Stabilized Zirconia Thermal Barrier Coating Performed by Suspension Plasma Spraying

    Science.gov (United States)

    Bernard, B.; Schick, V.; Remy, B.; Quet, A.; Bianchi, L.

    2016-09-01

    Performance enhancement of gas turbines is a main issue for the aircraft industry. Over many years, a large part of the effort has been focused on the development of more insulating Thermal Barrier Coatings (TBCs). In this study, Yttria Stabilized Zirconia (YSZ) columnar structures are processed by Suspension Plasma Spraying (SPS). These structures have already demonstrated abilities to get improved thermal lifetime, similarly to standard YSZ TBCs performed by EB-PVD. Thermal diffusivity measurements coupled with differential scanning calorimetry analysis are performed from room temperature up to 1100 °C, first, on HastelloyX substrates and then, on bilayers including a SPS YSZ coating. Results show an effective thermal conductivity for YSZ performed by SPS lower than 1 W.m-1K-1 whereas EB- PVD YSZ coatings exhibit a value of 1.5 W.m-1K-1.

  16. Microstructure and mechanical properties of plasma sprayed Al2O3 – 13%TiO2 Ceramic Coating

    Directory of Open Access Journals (Sweden)

    Wahab Juyana A

    2017-01-01

    Full Text Available This paper focused on the effect of deposition conditions on the microstructural and mechanical properties of the ceramic coating. In this study, Al2O3 – 13%TiO2 coated mild steel were prepared by using atmospheric plasma spray technology with different plasma power ranging from 25 kW to 40 kW. The as-sprayed coatings consist of γ-Al2O3 phase as the major phase and small amount of the titania phase existed in the coating structure. High degree of fully melted region was observed in the surface morphology for the coating sprayed with high plasma power, which lead to the high hardness and low percentage of porosity. In this study, nanoindentation test was carried out to investigate mechanical properties of the coating and the results showed that the coatings possess high elastic behaviour, which beneficial in engineering practice.

  17. 空气等离子镀覆技术的进展%Development of Air-plasma Spraying Technology

    Institute of Scientific and Technical Information of China (English)

    В.Я.Фролов; Г.К.Петров; Б.А.Юшин; Д.В.Иванов

    2014-01-01

    The air-plasma spraying technology has been found application in many fields .In recent years , research on both establishment of plasma generator and spraying process has been performed in the St .Petersburg State Polytechnic University , and many types of coatings , which may not only be used to protect freshly made parts but also to restore worn parts , have been developed .The theoretical and experimental investigations conducted by the St.Petersburg State Polytechnic University in conjunction with the Leibnits ( INP Greifswald ) Plasma and Technology Research Institute will allow amount of experimental work to be appreciably reduced in developing the plasma generator and the air-plasma spraying process .%空气等离子喷涂工艺在许多领域得到了应用。近年来,国立圣彼得堡综合技术大学在等离子体发生器的创建和涂覆工艺方面进行了研究,业已研制成多种涂层,既可用于新制零件的防护,也可用于磨损件的修复。国立圣彼得堡综合技术大学和雷波尼茨( INP Greifswald )等离子体及工艺研究院联合进行的理论和试验研究,可显著减少研发等离子体发生器和空气等离子涂覆工艺的试验工作量。

  18. The possibilities of atmospheric plasma-spraying application to obtain hydroxyapatite coatings on the stainless steel samples

    Directory of Open Access Journals (Sweden)

    Mihailović Marija D.

    2013-01-01

    Full Text Available For decades, the standard metallic materials for hip implants, besides the 316LVM stainless steel, were titanium- and cobalt/chromium-based alloys. Although bioinert, due to their corrosion resistance, they are not biocompatible. Contemporary surgical implants are not made just of bioinert metal anymore, but with deposited bioactive hydroxyapatite (HAp coating. Hydroxyapatite is chemically identical with the mineral constituent of bones and teeth, what besides its biocompatibility provides bioactivity as well. The HAp limitations are, however, weak tensile strength and low fatigue resistance for long term loadings, if used alone. This is the reason for HAp to be deposited onto the surgical implant, and to enable its bioactivity, what means intergrowth with bones, and therefore the long-lasting and mechanical stable non-cemented prosthesis. This is important predominantly because the need for such prostheses for younger population, and a better life quality. There are several contemporary techniques that have been used for deposition of these coatings onto the metal implant. The possibilities of atmospheric plasma-spraying for obtaining the stable HAp coatings on the 316LVM stainless steel, ordinary used as a standard material for hip implants production are presented in this paper. The coatings of a commercially available hydroxyapatite powder were plasma-sprayed onto the specimens of medical grade 316LVM stainless steel under various operating conditions. The optical microscopy was used for microstructure and porosity characterization, while coating morphology and Ca/P ratio were analyzed using SEM equipped with EDX. Coating microstructure varied from a porous to a glassy structure, depending on operating conditions applied and coating thickness. Coating porosity was determined to be at the lower required limit requested for the bone-coating intergrowth possibility, but nevertheless adhesion measurements showed good results. The Ca/P ratio was

  19. Prospective multi-centre study on a composite ceramic femoral component in total knee arthroplasty: Five-year clinical and radiological outcomes.

    Science.gov (United States)

    Bergschmidt, Philipp; Bader, Rainer; Ganzer, Dirk; Hauzeur, Christian; Lohmann, Christoph H; Krüger, Alexander; Rüther, Wolfgang; Tigani, Domenico; Rani, Nicola; Esteve, José Luis; Prats, Fernando Lopez; Zorzi, Claudio; Madonna, Vincenzo; Rigotti, Stefano; Benazzo, Francesco; Rossi, Stefano Marco Paolo; Mittelmeier, Wolfram

    2015-06-01

    Enhanced wear resistance of ceramics in general and improved mechanical characteristics of composite ceramics in terms of strength and resistance meet the demands for application in TKA. The aim of this prospective international multi-centre study was to evaluate the 5-year clinical and radiological outcomes of an unconstrained TKA with a composite ceramic femoral component. A total of 107 patients (109 knees) underwent TKA with the MULTIGEN-PLUS Ceramic Knee at seven centres in three European countries. Clinical and radiological assessments were performed preoperatively and postoperatively at 3, 12, 24 and 60 months, using HSS, WOMAC, SF-36 and standardised radiographs. Mean HSS and WOMAC increased significantly from 55.1±11.5 (21-83) and 48.1±16.6 (3-90) preoperatively to 85.6±9.6 (49-98) and 73.3±20.4 (17-100) at 60 months. Mean SF-36 showed significant improvements in patients' quality of life (49.1±17.6 (12-96) preoperatively versus 67.7±23.1 (12-100) at 60 months). Non-progressive radiolucent lines (ceramic knee is comparable to other metallic and ceramic unconstrained TKA systems. Although the assessment of long-term implant survivorship is still pending, the ceramic implants represent a promising solution for patients with allergies against metallic components and furthermore for the general osteoarthritis population due to enhanced wear resistance. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Yttria-stabilized zirkonia / gadolinium zirconate double-layer plasma-sprayed thermal barrier coating systems (TBCs)

    Energy Technology Data Exchange (ETDEWEB)

    Bakan, Emine

    2015-07-01

    Thermal barrier coating (TBC) research and development is driven by the desirability of further increasing the maximum inlet temperature in a gas turbine engine. A number of new top coat ceramic materials have been proposed during the last decades due to limited temperature capability (1200 C) of the state-of-the-art yttria-stabilized zirconia (7 wt. % Y{sub 2}O{sub 3}-ZrO{sub 2}, YSZ) at long term operation. Zirconate pyrochlores of the large lanthanides((Gd → La){sub 2}Zr{sub 2}O{sub 7}) have been particularly attractive due to their higher temperature phase stability than that of the YSZ. Nonetheless, the issues related with the implementation of pyrochlores such as low fracture toughness and formation of deleterious interphases with thermally grown oxide (TGO, Al{sub 2}O{sub 3}) were reported. The implication was the requirement of an interlayer between the pyrochlores and TGO, which introduced double-layer systems to the TBC literature. Furthermore, processability issues of pyrochlores associated with the different evaporation rates of lanthanide oxides and zirconia resulting in unfavorable composition variations in the coatings were addressed in different studies. After all, although the material properties are available, there is a paucity of data in the literature concerning the properties of the coatings made of pyrochlores. From the processability point of view the most reported pyrochlore is La{sub 2}Zr{sub 2}O{sub 7}. Hence, the goal of this research was to investigate plasma-sprayed Gd{sub 2}Zr{sub 2}O{sub 7} (GZO) coatings and YSZ/GZO double-layer TBC systems. Three main topics were examined based on processing, performance and properties: (i) the plasma spray processing of the GZO and its impact on the microstructural and compositional properties of the GZO coatings; (ii) the cycling lifetime of the YSZ/GZO double-layer systems under thermal gradient at a surface temperature of 1400 C; (iii) the properties of the GZO and YSZ coatings such as

  1. Effect of Liquid Feed-Stock Composition on the Morphology of Titanium Dioxide Films Deposited by Thermal Plasma Spray.

    Science.gov (United States)

    Adán, C; Marugán, J; van Grieken, R; Chien, K; Pershin, L; Coyle, T; Mostaghimi, J

    2015-09-01

    Titanium dioxide coatings were deposited on the surface of titanium foils by Thermal Plasma Spray (TPS) process. Three different TiO2 coatings were prepared using the commercial TiO2-P25 nanopowder and titanium isopropoxide precursor solution as feed-stocks. Structure and morphology of the TiO2-P25 powder and the plasma sprayed coatings were analyzed by X-ray diffraction (XRD), Raman spectroscopy, N2 adsorption-desorption isotherms, UV-visible spectroscopy and Scanning Electron Microscopy (SEM). XRD and Raman results indicate that the TiO2 coatings were composed of an anatase/rutile mixture that is conditioned by the suspension composition used to be sprayed. Coatings prepared from TiO2-P25 nanoparticles in water suspension (NW-P25) and titanium isopropoxide solution suspension (NSP-P25) are incorporated into the coatings without phase transformation and their anatase/rutile ratio percentage remains very similar to the starting TiO2-P25 powder. On the contrary, when titanium isopropoxide solution is used for spraying (SP), the amount of rutile increases in the final TiO2 coating. SEM analysis also reveals different microstructure morphology, coating thickness, density and porosity of the three TiO2 films that depend significantly on the type of feed-stock employed. Interestingly, we have observed the role of titanium isopropoxide in the formation of more porous and cohesive layers of TiO2. The NSP-P25 coating, prepared with a mix of titanium isopropoxide solution based on TiO2 nanoparticles, presents higher deposition efficiencies and higher coating thickness than the film prepared with nanoparticles suspended in water (NW-P25) or with titanium isopropoxide solutions (SP). This is due to the precursor solution is acting as the cement between TiO2 nanoparticles, improving the cohesive strength of the coating. In sum, NSP-P25 and NW-P25 coatings display a good photocatalytic potential, based on their light absorption properties and mechanical stability. Band gap of

  2. Microscopic, crystallographic and adherence properties of plasma-sprayed calcium phosphate coatings on Ti-6Al-4V

    Science.gov (United States)

    Tufekci, Eser

    Recently, plasma-spayed titanium implants have become very popular in the dentistry because of their biocompatibility and ability of providing osseointegration with the surrounding bone. Although there are numerous published studies on these materials, information and standards are still lacking. This study investigated the miscrostructural, crystallographic and adherence properties of plasma-sprayed hydroxyapatite coatings on Ti-6Al-4V substrates. The microstructures of the coatings and the elemental interdiffusion near the coating/substrate interface were investigated using a scanning electron microscope (SEM) equipped with x-ray energy-dispersive spectroscopy (EDS). X-ray diffraction analyses performed on Ti-6Al-4V coupons prepared with different percent crystallinities have provided structural information such as degree of crystallinity, phases present, average crystallite size, as well as the residual stresses within the coating. For evaluation of the adherence of the coatings to the substrates, experimental rods were subjected to torsion. The fracture surfaces were analyzed using SEM/EDS to develop a new methodology to determine the percent adherence of the coatings. SEM studies indicated that the surface microstructures of commercial dental implants were consistent with the plasma-spraying. In cross-section, coatings exhibited minimal porosity and limited interdiffusion of titanium and calcium at the coating/substrate interface. X-ray diffraction analyses indicated that the highest crystallinity coatings consisted of almost entirely HA and an amorphous calcium phosphate phase. As the coating crystallinity decreased, increasing amounts of alpha- and beta-tricalcium phosphate and tetracalcium phosphate were detected. The mean percent crystallinity for the three sets of coatings ranged from 50-60%. The mean HA crystallite size for the three sets of coatings ranged from about 0.02-0.04 mum. Differences in mean interplanar spacings for three selected

  3. 大气等离子喷涂氧化锆热障涂层研究进展%Research Progress of Atmospheric Plasma Sprayed Zirconia Thermal Barrier Coating

    Institute of Scientific and Technical Information of China (English)

    徐鹏; 宋仁国; 王超

    2011-01-01

    简要概述了大气等离子喷涂技术、等离子喷涂热障涂层选用氧化锆材料的原因及其具有的优异性能,同时也介绍了等离子喷涂制备热障涂层的国内外研究现状并指出了未来的发展方向.%The atmospheric plasma spraying and the reason of the choosing zirconia in the process of plasma sprayed thermal barrier coatings as well as its excellent performance were briefly overviewed. Meanwhile, the domestic and overseas research status of the plasma sprayed yttria partially stabilized zirconia (YSZ) thermal barrier coatings was also reviewed. Finally, the future development of plasma sprayed thermal barrier coatings was pointed out.

  4. Dielectric properties of Al2O3 coatings deposited via atmospheric plasma spraying and dry-ice blasting correlated with microstructural characteristics

    Science.gov (United States)

    Dong, Shujuan; Song, Bo; Liao, Hanlin; Coddet, Christian

    2015-01-01

    In this work, atmospheric plasma spraying combined with dry-ice blasting have been used to prepare alumina (Al2O3) coatings designed for insulating applications. The microstructural characteristics and dielectric properties of Al2O3 coatings were presented. The electrical insulating properties, i.e., dielectric strength and breakdown voltage, were investigated by dielectric breakdown test using direct current and alternating current. Relationships between dielectric properties and coating characteristics were discussed. The results showed that dry-ice blasting used during atmospheric plasma spray process allowed the production of coatings with better dielectric properties than those prepared without dry-ice blasting. The dielectric properties were correlated with the microstructural characteristics, not with phase composition.

  5. Study on the Mechanism of Adhesion Improvement Using Dry-Ice Blasting for Plasma-Sprayed Al2O3 Coatings

    Science.gov (United States)

    Dong, Shujuan; Song, Bo; Hansz, Bernard; Liao, Hanlin; Coddet, Christian

    2013-03-01

    The mechanisms of adhesion improvement of plasma-sprayed Al2O3 coatings using dry-ice blasting were investigated. In this study, the change of substrate surface characteristics in both the topography and the wettability due to the treatment of dry-ice blasting was mainly studied. The effect of dry-ice blasting on Al2O3 splat morphology with different treatment durations was also examined. The residual stress of plasma-sprayed Al2O3 coatings using dry-ice blasting was measured by curvature method and compared to that of coatings deposited with conventional air cooling. Based on these numerous assessment tests, it could be concluded that the adhesion improvement of Al2O3 coatings could be attributed to the cleaning effect of dry-ice blasting on different organic substances adsorbed on the substrates and the peening effect.

  6. Laser Remelting of Plasma Sprayed NiCrA1Y and NiCrAlY-A12O3 Coatings

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Two types of plasma sprayed coatings (NiCrAIY and NiCrAIY-AI2O3) were remelted by a 5 kW cw CO2 laser. With increasing laser power and decreasing traverse speed in the ranges of 200~700 W and 5~30 mm/s respectively, the melted track grew in width and depth. In the optimum range of laser parameters, a homogeneous remelted layer without voids, cavities, unmelted particles and microcracks was formed. On the surface of remelted layers, AI2O3 and YAIO3 were detected.As a result of isothermal oxidation tests, weight gains of laser remelted coatings were obviously lower than that only plasma sprayed, especially laser remelted NiCrAIY-AI2O3 coatings. The effects of laser remelting and incorporation of Al2O3 second phase in NiCrAIY matrix on high temperature oxidation resistance were discussed.

  7. Effect of Sealing Treatment on Corrosion Resistance of Plasma-Sprayed NiCrAl/Cr2O3-8 wt.%TiO2 Coating

    Science.gov (United States)

    Zhang, Jingjing; Wang, Zehua; Lin, Pinghua; Lu, Wenhuan; Zhou, Zehua; Jiang, Shaoqun

    2011-03-01

    Plasma-sprayed ceramic coatings inherently contain pores and micro-cracks which is deleterious when performed in aggressive environment. Various methods were applied to the as-sprayed coatings in order to improve the corrosion resistance. In the investigation of this study, plasma-sprayed NiCrAl/Cr2O3-8 wt.%TiO2 coatings were sealed by epoxy resin and silicone resin, respectively. Coatings were characterized by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), optical microscopy (OM) and x-ray diffraction (XRD). The possible corrosion mechanism was discussed. The results of salt spray test and electrochemical measurements indicated that after the sealing treatment, the porosity of coatings decreased obviously and a compact layer was formed to protect the coating from corrosion. The silicone resin proved to be more effective than epoxy resin in enhancing the corrosion resistance of the coatings used in this research.

  8. Erosion-corrosion of as-plasma-sprayed and laser-remelted NiCrAlY bond coats in working conditions of a coal-fired boiler

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, B.S.; Prakash, S. [College of Engineering & Technology, Bathinda (India). Dept. of Mechanical Engineering

    2008-01-15

    Ni-22Cr-10Al-1Y plasma spray coating has been formulated on boiler tube steels. namely, low-carbon steel ASTM SA210-Grade A1. 1Cr-0.5Mo steel ASTM SA213-T-11, and 2.25Cr-1Mo steel ASTM SA213-T-22. The coated steels also have been laser-remelted using a Nd:YAG laser. The degradation behavior of as-sprayed and laser-remelted coatings have been evaluated in actual conditions in a coal-fired boiler for 1,000 h at 755{sup o}C. The laser remelting has been found to be effective to increase the degradation resistance of plasma-sprayed boiler steels. ASTM SA213-T-22-coated and laser-remelted steel has proved to be most effective in resistance to degrading species.

  9. Frictional properties of CeO$_{2}$-Al$_{2}$O$_{3}$-ZrO$_{2}$ plasma-sprayed film under mixed and boundary lubricating conditions

    CERN Document Server

    Kita, H; Osumi, K; 10.2109/jcersj.112.615

    2004-01-01

    In order to find a counterpart for reducing the frictional coefficient of Al/sub 2/O/sub 3/-ZrO/sub 2/-CeO/sub 2/ plasma-sprayed film, the sliding properties in mixed and boundary lubricating conditions was investigated. It was found that combination of a CrN- coated cast iron pin and an Al/sub 2/O/sub 3/-ZrO/sub 2/-CeO/sub 2/ plasma sprayed plate provided the lowest frictional coefficient among several combinations chosen from practical materials. The coefficient of friction was much lower than that of the materials combination widely used for piston ring and cylinder liner. It was inferred that the combination of a pin made of hard materials with high density, a smooth surface such as CrN-coated cast iron and a porous plate can reduce the frictional coefficient because less sliding resistance is implemented and porosity retains oil.

  10. 非骨水泥股骨柄假体的中期疗效分析%Medium-term therapeutic evaluation of an uncemented femoral component

    Institute of Scientific and Technical Information of China (English)

    甄建国; 张卫国

    2011-01-01

    Objective :To study the clinical and radiographic results of tatal hip arthroplasty (THA) with an uncemented femoral component after 6 to 10 years follow-up, and to investigate factors effecting their efficacy. Methods: From January 2000 to December 2003,58 patients were treated with primary total hip arthroplasty. Among the patients, 27 patients were male and 31 patients were female ,ranging in age from 25 to 73 years ,with an average of 56 years. The 58 patients were clinically and radiographically followed up including before operation, postoperative 1.5,3,6 and 12 months, and then once a year. Therapeutic evaluation was measured by using Harris scoring system. The incidence of osteolysis around the components in different Gruen zones was radiologically determined. The data were analyzed by SPSS 16.0 software. Results:All the patients were followed up,and the duration ranged from 6 to 10 years,with a mean of 8.2 years. The Harris hip score of the patients improved from preoperative mean of(54.0±7.8 )to (88.3±6.1) at the latest follow-up. There were 32 patients with an excellent result, 22 good, 3 fair and 1 poor. Radiological analysis showed that 48 patients had stable bone in growth, 10 patients got stable fibrous in growth and nobody showed unstable fixation with aseptic loosening. Subsidence (1 to 3 mm) was observed in 4 patients. Osteolysis of the femoral cortex was seen in 4 patients without progressive development, and the latest follow-up radiographs showed a significantly greater incidence of osteolysis in Gruen zone Ⅰ , Ⅵ, Ⅶcompared with others (P=0.031 ). All the patients with low Harris score had received prostheses which were undersized in the intramedullary canal, and these differences were statistically significant. Conclusion:The uncemented femoral component has good medium-term clinical follow-up results because of high stability and no aseptic loosening.%目的:通过对一组行人工全髋关节置换术(THA)随访6~10年的病例

  11. Structure and magnetotransport properties in plasma-sprayed La 0.78Sr 0.22MnO 3 thick film

    Science.gov (United States)

    Orlando, M. T. D.; Cunha, A. G.; Freitas, J. C. C.; Orlando, C. G. P.; Bud'ko, S.; Giordanengo, B.; Sato, I. M.; Martinez, L. G.; Baggio-Saitovitch, E. M.

    2002-04-01

    Thick films of La 0.78Sr 0.22MnO 3 were produced by the plasma-spray technique onto stainless-steel substrate at 930°C. These films were obtained without the use of bond-layer, buffer-layer and annealing after deposition. The compound was deposited by a plasma-spray torch using nitrogen as the working gas. The films with thickness varying from 20 to 60 μm have good adherence and are composed of large splats with high degree of interconnection and small number of defects, as revealed by scanning electron microscopy. X-ray diffractometry analysis of the as-deposited film revealed that it had the same crystal structure as the original bulk. Measurements of electrical resistivity versus temperature for the film revealed a magnetic transition temperature near 340 K, with a ferromagnetic/metallic behavior below this temperature. The magnetoresistance of La 0.78Sr 0.22MnO 3 films exhibited similar magnetic field dependence as compared to the bulk sample, which indicates that the plasma-spray technique can be successfully employed for the deposition of thick films of manganites on large-area substrates while maintaining the main bulk properties.

  12. Role of process conditions on the microstructure, stoichiometry and functional performance of atmospheric plasma sprayed La(Sr)MnO3 coatings

    Science.gov (United States)

    Han, Su Jung; Chen, Yikai; Sampath, Sanjay

    2014-08-01

    Strontium doped lanthanum manganite (LSM) perovskite coatings were produced via atmospheric plasma spray technique to examine their applicability as electrically conductive coatings to protect chromium-poisoning of cathode side metallic interconnects in solid oxide fuel cells. Various plasma spray process conditions were manipulated including plasma power, total gas flow and content of H2 in the plasma gas in order to understand their effects on coating properties as well as efficacy as a protectant against Cr-poisoning. In-flight temperatures and velocities of spray particles were monitored for the various plasma spray conditions enabling assessment of thermal and kinetic energies of LSM particles. As anticipated, coating density improves with increasing thermal and/or kinetic energies of the LSM particles. However, the LSM particles also experienced significant phase decomposition at higher thermal exposure and longer residence time conditions. Due to preferential loss of oxygen and manganese, La2O3 phase is also formed under certain processing regimes. The resultant mixed-phase coating is ineffective both from electrical transport and as a protective coating for the metallic interconnect. Concomitantly, coatings with limited decomposition show excellent conductivity and protection characteristics demonstrating the need for mechanism driven process optimization for these functional oxide coatings.

  13. Corrosion resistance of plasma sprayed NiCrAl + (ZrO2 + Y2O3 ) thermal barrier coating on 18 -8 steel surface

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei; L(U) Tao; DING Hua-dong; ZHOU Hai; LIU Kai

    2005-01-01

    The corrosion resistance of NiCrAl +(ZrO2 + Y2 O3 )thermal barrier coating, formed with the plasma spraying technique, on the 18 - 8 steel surface was investigated. The phase structure and morphology of the coating were analyzed by means of X-ray diffraction(XRD) and scanning electron microscopy(SEM). The electrochemical corrosion behavior of the coating in 1.0 mol/L H2 SO4 solution was studied by using electrochemical measurement methods. The results show that the gradient plasma spraying coating is composed of the NiCrAlY primer coating and the (ZrO2 + Y2O3 ) top coating, and the coating thickness is 360 μm. The microhardness of coating reaches 1 100 HV. The corrosion resistance of the plasma sprayed coating of the 18 - 8 steel surface is about 5 times as great as that of the original pattern. The corrosion resistance of the coating is enhanced notably.

  14. Chemical stability and antimicrobial activity of plasma sprayed bioactive Ca2ZnSi2O7 coating.

    Science.gov (United States)

    Li, Kai; Yu, Jiangming; Xie, Youtao; Huang, Liping; Ye, Xiaojian; Zheng, Xuebin

    2011-12-01

    Calcium silicate ceramic coatings have received considerable attention in recent years due to their excellent bioactivity and bonding strength. However, their high dissolution rates limit their practical applications. In this study, zinc incorporated calcium silicate based ceramic Ca(2)ZnSi(2)O(7) coating was prepared on Ti-6Al-4V substrate via plasma spraying technology aiming to achieve higher chemical stability and additional antibacterial activity. Chemical stability of the coating was assessed by monitoring mass loss and ion release of the coating after immersion in the Tris-HCl buffer solution and examining pH value variation of the solution. Results showed that the chemical stability of zinc incorporated coating was improved significantly. Antimicrobial activity of the Ca(2)ZnSi(2)O(7) coating was evaluated, and it was found that the coating exhibited 93% antibacterial ratio against Staphylococcus aureus. In addition, in vitro bioactivity and cytocompatibility were confirmed for the Ca(2)ZnSi(2)O(7) coating by simulated body fluid test, MC3T3-E1 cells adhesion investigation and cytotoxicity assay.

  15. Surface silver-doping of biocompatible glasses to induce antibacterial properties. Part II: Plasma sprayed glass-coatings.

    Science.gov (United States)

    Miola, M; Ferraris, S; Di Nunzio, S; Robotti, P F; Bianchi, G; Fucale, G; Maina, G; Cannas, M; Gatti, S; Massé, A; Vitale Brovarone, C; Verné, E

    2009-03-01

    A 57% SiO(2), 3% Al(2)O(3), 34% CaO and 6% Na(2)O glass (SCNA) has been produced in form of powders and deposited by plasma spray on titanium alloy and stainless steel substrates. The obtained coatings have been subjected to a patented ion-exchange treatment to introduce silver ions in the surface inducing an antibacterial behavior. Silver surface-enriched samples have been characterized by means of X-ray diffraction, SEM observation, EDS analysis, in vitro bioactivity tests, leaching tests by GFAAS (graphite furnace atomic adsorption spectroscopy) analyses, cells adhesion and proliferation, and antibacterial tests using Staphylococcus Aureus strain. In vitro tests results showed that the modified samples acquired an antimicrobial action against tested bacteria maintaining unaffected the biocompatibility of the glass. Furthermore the ion-exchange treatment can be successfully applied to glass-coated samples without affecting the properties of the coatings; the simplicity and reproducibility of the method make it suitable for glass or glass-ceramic coatings of different composition in order to produce coated devices for bone healing and/or prostheses, able to reduce bacterial colonization and infections risks.

  16. Porous tantalum coatings prepared by vacuum plasma spraying enhance bmscs osteogenic differentiation and bone regeneration in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Ze Tang

    Full Text Available Tantalum, as a potential metallic implant biomaterial, is attracting more and more attention because of its excellent anticorrosion and biocompatibility. However, its significantly high elastic modulus and large mechanical incompatibility with bone tissue make it unsuitable for load-bearing implants. In this study, porous tantalum coatings were first successfully fabricated on titanium substrates by vacuum plasma spraying (VPS, which would exert the excellent biocompatibility of tantalum and alleviate the elastic modulus of tantalum for bone tissue. We evaluated cytocompatibility and osteogenesis activity of the porous tantalum coatings using human bone marrow stromal cells (hBMSCs and its ability to repair rabbit femur bone defects. The morphology and actin cytoskeletons of hBMSCs were observed via electron microscopy and confocal, and the cell viability, proliferation and osteogenic differentiation potential of hBMSCs were examined quantitatively by PrestoBlue assay, Ki67 immunofluorescence assay, real-time PCR technology and ALP staining. For in vivo detection, the repaired femur were evaluated by histomorphology and double fluorescence labeling 3 months postoperation. Porous tantalum coating surfaces promoted hBMSCs adhesion, proliferation, osteogenesis activity and had better osseointegration and faster new bone formation rate than titanium coating control. Our observation suggested that the porous tantalum coatings had good biocompatibility and could enhance osseoinductivity in vitro and promote new bone formation in vivo. The porous tantalum coatings prepared by VPS is a promising strategy for bone regeneration.

  17. Mechanical Properties of Double-Layer and Graded Composite Coatings of YSZ Obtained by Atmospheric Plasma Spraying

    Science.gov (United States)

    Carpio, Pablo; Rayón, Emilio; Salvador, María Dolores; Lusvarghi, Luca; Sánchez, Enrique

    2016-04-01

    Double-layer and graded composite coatings of yttria-stabilized zirconia were sprayed on metallic substrates by atmospheric plasma spray. The coating architecture was built up by combining two different feedstocks: one micro- and one nanostructured. Microstructural features and mechanical properties (hardness and elastic modulus) of the coatings were determined by FE-SEM microscopy and nanoindentation technique, respectively. Additional adherence and scratch tests were carried out in order to assess the failure mechanisms occurring between the layers comprising the composites. Microstructural inspection of the coatings confirms the two-zone microstructure. This bimodal microstructure which is exclusive of the layer obtained from the nanostructured feedstock negatively affects the mechanical properties of the whole composite. Nanoindentation tests suitably reproduce the evolution of mechanical properties through coatings thickness on the basis of the position and/or amount of nanostructured feedstock used in the depositing layer. Adhesion and scratch tests show the negative effect on the coating adhesion of layer obtained from the nanostructured feedstock when this layer is deposited on the bond coat. Thus, the poor integrity of this layer results in lower normal stresses required to delaminate the coating in the adhesion test as well as minor critical load registered by using the scratch test.

  18. Plasma Spraying and Characterization of Tungsten Carbide-Cobalt Coatings by the Water-Stabilized System WSP

    Directory of Open Access Journals (Sweden)

    Pavel Ctibor

    2009-01-01

    Full Text Available Tungsten carbide-cobalt powders (WC-17wt% Co were plasma sprayed by a water-stabilized system WSP. Experiments with variable feeding distances and spray distances were carried out. Thinner coatings were deposited on carbon steel substrates and thicker coatings on stainless steel substrates to compare different cooling conditions. Basic characterization of coatings was done by XRD, SEM, and light microscopy plus image analysis. Microhardness was measured on polished cross-sections. The main focus of investigation was resistance against wear in dry as well as wet conditions. The appropriate tests were performed with set-ups based on ASTM G65 and G75, respectively. The influence of spray parameters onto coating wear performance was observed. The results of mechanical tests were discussed in connection with changes of phase composition and with the quality of the coating's microstructure. The results show that for obtaining the best possible WC-17Co coating with WSP process, from the viewpoint of wear resistance, the desired parameters combination is long feeding distance combined with short spray distance.

  19. Degradation behavior of Ni3Al plasma-sprayed boiler tube steels in an energy generation system

    Science.gov (United States)

    Sidhu, Buta Singh; Prakash, S.

    2005-06-01

    Boiler steels, namely, low-C steel, ASTM-SA210-Grade A1 (GrA1), 1Cr-0.5Mo steel, ASTM-SA213-T-11 (T11) and 2.25Cr-1Mo steel, ASTM-SA213-T-22 (T22) were plasma sprayed with Ni3Al. The alloy powder was prepared by mixing Ni and Al in the stoichiometric ratio of 3 to 1. The Ni-22Cr-10Al-1Y alloy powder was used as a bond coat, with a 150 µm thick layer sprayed onto the surface before applying the 200 µm coating of Ni3Al. Exposure studies have been performed in the platen superheater zone of a coal-fired boiler at around 755 °C for 10 cycles, each of 100 h duration. The protection to the base steel was minimal for the three steels. Scale spallation and the formation of a porous and nonadherent NiO scale were probably the main reasons for the lack of protection. In the case of T22-coated steel, cracks in the coatings have been observed after the first 100 h exposure cycle.

  20. Microstructure and Anticorrosion Property of AT13 Coatings Made by Combination of Nanoparticles Doping and Plasma Spraying Technique

    Institute of Scientific and Technical Information of China (English)

    LI Chun-fu; DAI Jia-lin; WANG Bin; ZHANG Ying; HE Tao-e; LUO Ping-ya

    2004-01-01

    Al2O3+13wt%TiO2 (AT13) particles were doped with 5%~30% nanoparticles and prefabricating powders were prepared by renewed granulation. AT13 coatings were prepared on the surface of steel 45# by air plasma spraying technique with the prefabricating powders. The microstructures of the AT13 prefabricating powders and the resulting coatings were investigated by SEM and EDS and XRD. The samples were undergone corrosion in the medium of 10% H2SO4 aqueous solution at temperature 80℃. The results indicate that the blistering time of coatings in the corrosive medium was increased with the increase of doped nanoparticle concentration while the time from blistering to spalling is independent of nanoparticle concentration. The results revealed that the structure of prefabricating powders was a twisted micrometer grade particle with dimension of 40-60μm, encapsulated by nanoparticles. The homogeneity of element distribution in coatings was improved and porosity was reduced. The phases of (Al2O3) 5.333 and orthorhombic Al2TiO5 were identified . The fracture analysis confirmed that there is a large amount of vermiculate whiskers with diameter of 10nm and length of 100~200 nm in coatings and the fracture type of coatings was the ductile trans-granular fracture.

  1. Microstructure and Anticorrosion Property of AT13 Coatings Made by Combination of Nanoparticles Doping and Plasma Spraying Technique

    Institute of Scientific and Technical Information of China (English)

    LIChun-fu; DAIJia-lin; WANGBin; ZHANGYing; HETao-e; LUOPing-ya

    2004-01-01

    Al2O3+ 13wt%TiO2 (AT13) particles were doped with 5%-30% nanoparticles and prefabricating powders were prepared by renewed granulation. AT13 coatings were prepared on the surface of steel 45# by air plasma spraying technique with the prefabricating powders. The microstructures of the AT13 prefabricating powders and the resulting coatings were investigated by SEM and EDS and XRD. The samples were undergone corrosion in the medium of 10% H2SO4 aqueous solution at temperature 80℃. The results indicate that the blistering time of coatings in the corrosive medium was increased with the increase of doped nanoparticle concentration while the time from blistering to spalling is independent of nanoparticle concentration.The results revealed that the structure of prefabricating powders was a twisted micrometer grade particle with dimension of 40-60μm, encapsulated by nanoparticles. The homogeneity of element distribution in coatings was improved and porosity was reduced. The phases of (Al2O3)5.333 and orthorhombic Al2TiO5 were identified. The fracture analysis confirmed that there is a large amount of vermiculate whiskers with diameter of 10nm and length of 100-200 nm in coatings and the fracture type of coatings was the ductile trans-granular fracture.

  2. Sliding Wear Behavior of Plasma Sprayed Alumina-Based Composite Coatings against Al2O3 Ball

    Institute of Scientific and Technical Information of China (English)

    Minh-quy Le; Young-hun Chae; Seock-sam Kim

    2004-01-01

    The sliding wear behaviors of a single layer Al2O3-30 wt pct ZrO2, a double layer Al2O3-30 wt pct ZrO2/Ni-Cr and a single layer Al2O3-13 wt pct TiO2 coating deposited on low carbon steel by plasma spraying were investigated under lubricated conditions with various normal loads. The plastic deformation, detachment and pull out of splats were involved in the wear process of the studied coatings under test conditions. Crack propagation was found in Al2O3-13 wt pct TiO2 under loads of 70 and 100 N and in Al2O3-30 wt pct ZrO2/Ni-Cr under a load of 130 N.While increasing the normal load, the wear rates of Al2O3-30 wt pct ZrO2 and Al2O3-30 wt pct ZrO2/Ni-Cr slightly increased, the wear rate of Al2O3-13 wt pct TiO2 increased rapidly. The results showed that the Ni-Cr bonding layer improved the wear resistance of the coating system even it is relatively thin compared with the outer coating layer.The influence of this bonding layer on wear behavior of the coating increased as increasing the normal load.

  3. Effect of substrate materials on rutile crystalline orientation in plasma-sprayed TiO2 coatings

    Institute of Scientific and Technical Information of China (English)

    YANG Guan-jun; LI Chang-jiu; WANG Yu-yue

    2004-01-01

    TiO2 coatings are of technical importance owing to their promising applications to photocatalytical, electrical, optical and tribological coatings. Thermal spraying process has been widely used to deposit both metallic and nonmetallic coatings. During thermal spraying, spray particle at fully or partially melted condition is projected to a substrate and subsequently flattens, rapidly cools and solidifies. Therefore, a coating in lamellar structure is usually formed as a quenched microstructure. TiO2 coatings were deposited on different substrates through plasma spraying with fused-crushed powder in rutile phase as feedstock to reveal the crystalline orientation in the coatings. XRD results show that the coatings consist of rutile phase with a fraction of anatase phase, and the rutile phase presents a preferable crystalline orientation along [101] direction. It is found that the orientation factors of rutile phase in the thin coatings are significantly influenced by substrate materials. The thick coatings yield the same orientation factors of 0.22 to 0.23 on all substrates in spite of substrate materials. It is considered that the thermal properties of substrate materials are the dominant factors for the preferable crystalline orientation in rutile phase within plasmasprayed TiO2 coating.

  4. Degradation behavior of Ni{sub 3}Al plasma-sprayed boiler tube steels in an energy generation system

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, B.S.; Prakash, S. [GZS, Bathinda (India). College of Engineering

    2005-06-01

    Boiler steels, namely, low-C steel, ASTM-SA210-Grade A1 (GrA1), 1Cr-0.5Mo steel, ASTM-SA213-T-11 (T11) and 2.25Cr-1Mo steel, ASTM-SA213-T-22 (T22) were plasma sprayed with Ni3Al. The alloy powder was prepared by mixing Ni and Al in the stoichiometric ratio of 3 to 1. The Ni-22Cr-10Al-1Y alloy powder was used as a bond coat, with a 150{mu} m thick layer sprayed onto the surface before applying the 200{mu}m coating of Ni{sub 3}Al. Exposure studies have been performed in the platen superheater zone of a coal-fired boiler at around 755{sup o}C for 10 cycles, each of 100 h duration. The protection to the base steel was minimal for the three steels. Scale spallation and the formation of a porous and nonadherent NiO scale were probably the main reasons for the lack of protection. In the case of T22-coated steel, cracks in the coatings have been observed after the first 100 h exposure cycle.

  5. Interfacial microstructures and hardness distributions of vacuum plasma spraying W-coated ODS ferritic steels for fusion plasma facing applications

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Sanghoon, E-mail: shnoh@kaeri.re.kr [Nuclear Materials Division, Korea Atomic Energy Research Institute, Yuseong-gu, Daejeon (Korea, Republic of); Kasada, Ryuta; Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto (Japan); Nagasaka, Takuya [National Institute for Fusion Science, Toki, Gifu (Japan); Sokolov, Mikhail A. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Kim, Tae Kyu [Nuclear Materials Division, Korea Atomic Energy Research Institute, Yuseong-gu, Daejeon (Korea, Republic of)

    2014-04-15

    In the present study, interfacial microstructures and hardness distributions of W-coated ODS steels as plasma facing structural materials were investigated. A vacuum plasma spraying (VPS) technique was employed to fabricate a W layer on the surface of the ODS ferritic steel substrates. The microstructural observations revealed that the VPS-W has very fine grains aligned toward the spraying direction, and a favorable interface between W and ODS ferritic steels by a mechanical inter-locking without an intermetallic layer. However, crack-type defects were found in VPS-W. Because a brittle inter-diffused layer does not exist at the joint interface, the hardness was gradually distributed in the joint region. After neutron irradiation, irradiation hardening significantly occurred in the VPS-W. However, the hardening of VPS-W was less than that of bulk W irradiated at 773 K. Thus, the VPS is considered to be one of the promising ways to join dissimilar materials between W and ODS steels, which can avoid the formation of an interfacial intermetallic layer and create favorable irradiation hardening resistance on the W coated layer.

  6. Double-Layer Gadolinium Zirconate/Yttria-Stabilized Zirconia Thermal Barrier Coatings Deposited by the Solution Precursor Plasma Spray Process

    Science.gov (United States)

    Jiang, Chen; Jordan, Eric H.; Harris, Alan B.; Gell, Maurice; Roth, Jeffrey

    2015-08-01

    Advanced thermal barrier coatings (TBCs) with lower thermal conductivity, increased resistance to calcium-magnesium-aluminosilicate (CMAS), and improved high-temperature capability, compared to traditional yttria-stabilized zirconia (YSZ) TBCs, are essential to higher efficiency in next generation gas turbine engines. Double-layer rare-earth zirconate/YSZ TBCs are a promising solution. From a processing perspective, solution precursor plasma spray (SPPS) process with its unique and beneficial microstructural features can be an effective approach to obtaining the double-layer microstructure. Previously durable low-thermal-conductivity YSZ TBCs with optimized layered porosity, called the inter-pass boundaries (IPBs) were produced using the SPPS process. In this study, an SPPS gadolinium zirconate (GZO) protective surface layer was successfully added. These SPPS double-layer TBCs not only retained good cyclic durability and low thermal conductivity, but also demonstrated favorable phase stability and increased surface temperature capabilities. The CMAS resistance was evaluated with both accumulative and single applications of simulated CMAS in isothermal furnaces. The double-layer YSZ/GZO exhibited dramatic improvement in the single application, but not in the continuous one. In addition, to explore their potential application in integrated gasification combined cycle environments, double-layer TBCs were tested under high-temperature humidity and encouraging performance was recorded.

  7. Influence of chloride ion concentration on immersion corrosion behaviour of plasma sprayed alumina coatings on AZ31B magnesium alloy

    Directory of Open Access Journals (Sweden)

    D. Thirumalaikumarasamy

    2014-12-01

    Full Text Available Corrosion attack of aluminium and magnesium based alloys is a major issue worldwide. The corrosion degradation of an uncoated and atmospheric plasma sprayed alumina (APS coatings on AZ31B magnesium alloy was investigated using immersion corrosion test in NaCl solutions of different chloride ion concentrations viz., 0.01 M, 0.2 M, 0.6 M and 1 M. The corroded surface was characterized by an optical microscope and X-ray diffraction. The results showed that the corrosion deterioration of uncoated and coated samples were significantly influenced by chloride ion concentration. The uncoated magnesium and alumina coatings were found to offer a superior corrosion resistance in lower chloride ion concentration NaCl solutions (0.01 M and 0.2 M NaCl. On the other hand the coatings and Mg alloy substrate were found to be highly susceptible to localized damage, and could not provide an effective corrosion protection in solutions containing higher chloride concentrations (0.6 M and 1 M. It was found that the corrosion resistance of the ceramic coatings and base metal gets deteriorated with the increase in the chloride concentrations.

  8. Application of atmospheric solution precursor plasma spray to photocatalytic devices for small and medium industries in developing countries

    Science.gov (United States)

    Kindole, Dickson; Ando, Yasutaka

    2017-01-01

    For development of a functional film deposition process with high deposition rate, as a basic study, TiO2 films were deposited by atmospheric solution precursor plasma spray (ASPPS) process. Ethanol-diluted titanium tetraisobutoxide [TTIB: Ti(OC4H9)4] was used as a feedstock. To achieve a high plasma thermal energy at a low discharge power, N2-dominant Ar/N2 as the plasma working gas was used, for film deposition at various deposition distances. Consequently, photocatalytic TiO2 with a rutile/anatase mixture film structure was deposited evenly in this case. By conducting methylene blue decomposition and wettability tests, photocatalytic properties of the film were confirmed. When a TiO2 film was applied to photocatalytic dye-sensitized solar cells (DSSCs), the cells generated an electromotive force of 0.143V oc, which is close to those of commercial DSSCs. From these results, the ASPPS process was found to have high potential for high rate functional film deposition and was cost effective, making it suitable for developing countries.

  9. A comparative study on solid particle erosion behavior of plasma sprayed Cr2O3 coatings on 410 grade steel

    Science.gov (United States)

    Sreenivas Rao, K. V.; Girisha, K. G.; Eswar, Sushruta

    2016-09-01

    In the present investigation chromium oxide (Cr2O3) powder particles were used to deposit on 410 martensitic steel. Ni-Cr was used as bond coat. Erosion studies were directed on uncoated and also plasma sprayed steel examples at room temperature. The Erosion analyses were done utilizing an air-jet erosion test rig at a speed of 30 m/s by varying stand-off distance as per ASTM G-76. The stand-off distance considered were 10mm, 20mm, 30mm & 40mm. Silica sand particles of size 312μm was used as erodent. The surface morphologies were characterized using Scanning electron microscope (SEM) and presence of coating material was confirmed using energy dispersive X-ray analyzer (EDS). Vickers micro harness test was performed on surface of coated and un-coated substrates. It was observed that Cr2O3 Coated specimen exhibits better Erosion resistance when contrasted with uncoated substrates because of its enhanced property like micro hardness.

  10. Microstructural features and properties of plasma sprayed YPSZ/NiCrAlY thermal barrier coating (TBC)

    Institute of Scientific and Technical Information of China (English)

    孙大谦; 王文权; 宣兆志; 宫文彪

    2004-01-01

    The plasma sprayed thermal barrier coating (TBC) consists of NiCrAlY bond coating and yttria partially stabilized zirconia (YPSZ) top coating. NiCrAlY coating mainly contains Ni solid solution with face centered cubic lattice, Al2O3 oxides and pores. The most obvious feature of YPSZ coating with tetragonal zirconia is a lot of vertical microcracks in this coating. The thermal insulation capability of the TBC increased with an increase in YPSZ coating thickness, the temperature drop across the TBC increasing from 60℃ to 92℃ with increasing YPSZ coating thickness with increasing YPSZ coating thickness and cracks initiated mainly in original vertical microcrack tips of the YPSZ coating and propagated not only along YPSZ coating / NiCrAlY coating interface but also through into two stages: transient oxidation stage with rapid oxidation rate and steady oxidation stage with slow oxidation. Their transition time was favorable to increase YPSZ coating toughness and to decrease the pores and oxides of the TBC system for improving thermal shock resistance and oxidation resistance of the TBC.

  11. Characterization and Wear Behavior of Heat-treated Ni3Al Coatings Deposited by Air Plasma Spraying

    Science.gov (United States)

    Mehmood, K.; Rafiq, M. A.; Nusair Khan, A.; Ahmed, F.; Mudassar Rauf, M.

    2016-07-01

    Air plasma spraying was utilized to deposit Ni3Al coatings on AISI-321 steel substrate. The deposited coatings were isothermally heat-treated at various temperatures from 500 to 800 °C for 10, 30, 60, and 100 h. The x-ray diffraction analysis revealed NiO formation in Ni3Al at 500 °C after 100 h, and the percentage of NiO increased with increasing exposure time and temperature. The hardness of the coating increased with the formation of NiO. The DSC test showed the formation of minor phases, Al3Ni and Al3Ni2, within the coating along with the major phase Ni3Al. TGA revealed a slowing down of the oxidation rate upon surface oxide formation. The pin-on-disk wear test on the as-sprayed and heat-treated coatings showed that wear rate and coefficient of friction decreased with an increase in the NiO phase content.

  12. Wear resistance and microstructural properties of Ni–Al/h-BN/WC–Co coatings deposited using plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao, W.T. [Materials and Chemical Research Laboratories, Industrial Technology Research Institute, Chutung 310, Taiwan (China); Su, C.Y., E-mail: cysu@ntut.edu.tw [Graduate Institute of Manufacturing Technology, National Taipei University of Technology, Taipei 106, Taiwan (China); Huang, T.S. [China Steel Corporation, Kaohsiung, Taiwan (China); Liao, W.H. [Materials and Chemical Research Laboratories, Industrial Technology Research Institute, Chutung 310, Taiwan (China); Nano Technology Laboratory, Department of Materials Engineering, National Chung Hsing University, Taichung 402, Taiwan (China)

    2013-05-15

    Hexagonal boron nitride (h-BN) and tungsten carbide cobalt (WC–Co) were added to nickel aluminum alloy (Ni–Al) and deposited as plasma sprayed coatings to improve their tribological properties. The microstructure of the coatings was analyzed using a scanning electron microscope (SEM). Following wear test, the worn surface morphologies of the coatings were analyzed using a SEM to identify their fracture modes. The results of this study demonstrate that the addition of h-BN and WC–Co improved the properties of the coatings. Ni–Al/h-BN/WC–Co coatings with high hardness and favorable lubrication properties were deposited. - Highlights: • We mixed Ni–Al, h-BN and WC–Co powders and deposited them as composite coatings. • Adding WC–Co was found to increase the hardness and reduce the wear volume loss. • Adding h-BN was found to decrease the hardness and reduce the friction coefficient. • This composite coating was shown to have improved wear properties at 850 °C.

  13. Influence of in-flight particle state diagnostics on properties of plasma sprayed YSZ-CeO2 nanocomposite coatings

    Directory of Open Access Journals (Sweden)

    S. Mantry

    2014-07-01

    Full Text Available This article describes the influence of controlling in-flight hot particle characteristics on properties of plasma sprayed nanostructured yttria stabilized zirconia (YSZ coatings. This article depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on particle temperature, velocity and size of the splat prior to impact on the metallic substrate. Particle temperature measurement is based on two-color pyrometry and particle velocities are measured from the length of the particle traces during known exposure times. The microstructure and adhesion strength of as-sprayed nano-YSZ coatings were studied. Field emission scanning electron microscopy results revealed that morphology of coating exhibits bimodal microstructure consisting of nano-zones reinforced in the matrix of fully melted particles. The coating adhesion strength is noticed to be greatly affected by the melting state of agglomerates. Maximum adhesion strength of 42.39 MPa has been experimentally found out by selecting optimum levels of particle temperature and velocity. The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nano-zones.

  14. Phosphor-Doped Thermal Barrier Coatings Deposited by Air Plasma Spray for In-Depth Temperature Sensing.

    Science.gov (United States)

    Peng, Di; Yang, Lixia; Cai, Tao; Liu, Yingzheng; Zhao, Xiaofeng; Yao, Zhiqi

    2016-09-28

    Yttria-stabilized zirconia (YSZ)-based thermal barrier coating (TBC) has been integrated with thermographic phosphors through air plasma spray (APS) for in-depth; non-contact temperature sensing. This coating consisted of a thin layer of Dy-doped YSZ (about 40 µm) on the bottom and a regular YSZ layer with a thickness up to 300 µm on top. A measurement system has been established; which included a portable; low-cost diode laser (405 nm); a photo-multiplier tube (PMT) and the related optics. Coating samples with different topcoat thickness were calibrated in a high-temperature furnace from room temperature to around 900 °C. The results convincingly showed that the current sensor and the measurement system was capable of in-depth temperature sensing over 800 °C with a YSZ top layer up to 300 µm. The topcoat thickness was found to have a strong effect on the luminescent signal level. Therefore; the measurement accuracy at high temperatures was reduced for samples with thick topcoats due to strong light attenuation. However; it seemed that the light transmissivity of YSZ topcoat increased with temperature; which would improve the sensor's performance at high temperatures. The current sensor and the measurement technology have shown great potential in on-line monitoring of TBC interface temperature.

  15. Microstructural Effects and Properties of Non-line-of-Sight Coating Processing via Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Harder, Bryan J.; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2017-08-01

    Plasma spray-physical vapor deposition (PS-PVD) is a unique processing method that bridges the gap between conventional thermal spray and vapor phase methods, and enables highly tailorable coatings composed of a variety of materials in thin, dense layers or columnar microstructures with modification of the processing conditions. The strengths of this processing technique are material and microstructural flexibility, deposition speed, and potential for non-line-of-sight (NLOS) capability by vaporization of the feedstock material. The NLOS capability of PS-PVD is investigated here using yttria-stabilized zirconia and gadolinium zirconate, which are materials of interest for turbine engine applications. PS-PVD coatings were applied to static cylindrical substrates approximately 6-19 mm in diameter to study the coating morphology as a function of angle. In addition, coatings were deposited on flat substrates under various impingement configurations. Impingement angle had significant effects on the deposition mode, and microscopy of coatings indicated that there was a shift in the deposition mode at approximately 90° from incidence on the cylindrical samples, which may indicate the onset of more turbulent flow and PVD-like growth. Coatings deposited at non-perpendicular angles exhibited a higher density and nearly a 2× improvement in erosion performance when compared to coatings deposited with the torch normal to the surface.

  16. Cyclic delamination behavior of plasma-sprayed hydroxyapatite coating on Ti-6Al-4V substrates in simulated body fluid.

    Science.gov (United States)

    Otsuka, Yuichi; Kawaguchi, Hayato; Mutoh, Yoshiharu

    2016-10-01

    This study aimed to clarify the effect of a simulated body fluid (SBF) on the cyclic delamination behavior of a plasma-sprayed hydroxapatite (HAp) coating. A HAp coating is deposited on the surfaces of surgical metallic materials in order to enhance the bond between human bone and such surfaces. However, the HAp coating is susceptible to delamination by cyclic loading from the patient's gait. Although hip joints are subjected to both positive and negative moments, only the effects of tensile bending stresses on vertical crack propagation behavior have been investigated. Thus, the cyclic delamination behavior of a HAp coating was observed at the stress ratio R=-1 in order to determine the effects of tensile/compressive loading on the delamination behavior. The delamination growth rate increased with SBF immersion, which decreased the delamination life. Raman spectroscopy analysis revealed that the selective phase dissolution in the HAp coating was promoted at interfaces. Finite element analysis revealed that the energy release rate Gmax showed a positive value even in cases with compressive loading, which is a driving force for the delamination of a HAp coating. A prediction model for the delamination growth life was developed that combines a fracture mechanics parameter with the assumed stress-dependent dissolution rate. The predicted delamination life matched the experimental data well in cases of lower stress amplitudes with SBF. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Improved Thermally Grown Oxide Scale in Air Plasma Sprayed NiCrAlY/Nano-YSZ Coatings

    Directory of Open Access Journals (Sweden)

    Mohammadreza Daroonparvar

    2013-01-01

    Full Text Available Oxidation has been considered as one of the principal disruptive factors in thermal barrier coating systems during service. So, oxidation behavior of thermal barrier coating (TBC systems with nanostructured and microstructured YSZ coatings was investigated at 1000∘C for 24 h, 48 h, and 120 h. Air plasma sprayed nano-YSZ coating exhibited a trimodal structure. Microstructural characterization also demonstrated an improved thermally grown oxide scale containing lower spinels in nano-TBC system after 120 h of oxidation. This phenomenon is mainly related to the unique structure of the nano-YSZ coating, which acted as a strong barrier for oxygen diffusion into the TBC system at elevated temperatures. Nearly continues but thinner Al2O3 layer formation at the NiCrAlY/nano-YSZ interface was seen, due to lower oxygen infiltration into the system. Under this condition, spinels formation and growth on the Al2O3 oxide scale were diminished in nano-TBC system compared to normal TBC system.

  18. Phosphor-Doped Thermal Barrier Coatings Deposited by Air Plasma Spray for In-Depth Temperature Sensing

    Directory of Open Access Journals (Sweden)

    Di Peng

    2016-09-01

    Full Text Available Yttria-stabilized zirconia (YSZ-based thermal barrier coating (TBC has been integrated with thermographic phosphors through air plasma spray (APS for in-depth; non-contact temperature sensing. This coating consisted of a thin layer of Dy-doped YSZ (about 40 µm on the bottom and a regular YSZ layer with a thickness up to 300 µm on top. A measurement system has been established; which included a portable; low-cost diode laser (405 nm; a photo-multiplier tube (PMT and the related optics. Coating samples with different topcoat thickness were calibrated in a high-temperature furnace from room temperature to around 900 °C. The results convincingly showed that the current sensor and the measurement system was capable of in-depth temperature sensing over 800 °C with a YSZ top layer up to 300 µm. The topcoat thickness was found to have a strong effect on the luminescent signal level. Therefore; the measurement accuracy at high temperatures was reduced for samples with thick topcoats due to strong light attenuation. However; it seemed that the light transmissivity of YSZ topcoat increased with temperature; which would improve the sensor’s performance at high temperatures. The current sensor and the measurement technology have shown great potential in on-line monitoring of TBC interface temperature.

  19. Femoral revision surgery with impaction bone grafting

    NARCIS (Netherlands)

    B.L.E.F. ten Have (Bas); R.W. Brouwer (Reinoud); F.C. van Biezen (Frans); J.A.N. Verhaar (Jan)

    2012-01-01

    textabstractThe purpose of this prospective study was to evaluate the long-term clinical and radiological outcomes of revision of the femoral component of a total hip replacement using impaction bone grafting. Femoral revision with an impacted allograft was performed on 29 patients (31 hips). In all

  20. In Situ Fabrication of AlN Coating by Reactive Plasma Spraying of Al/AlN Powder

    Directory of Open Access Journals (Sweden)

    Mohammed Shahien

    2011-10-01

    Full Text Available Reactive plasma spraying is a promising technology for the in situ formation of aluminum nitride (AlN coatings. Recently, it became possible to fabricate cubic-AlN-(c-AlN based coatings through reactive plasma spraying of Al powder in an ambient atmosphere. However, it was difficult to fabricate a coating with high AlN content and suitable thickness due to the coalescence of the Al particles. In this study, the influence of using AlN additive (h-AlN to increase the AlN content of the coating and improve the reaction process was investigated. The simple mixing of Al and AlN powders was not suitable for fabricating AlN coatings through reactive plasma spraying. However, it was possible to prepare a homogenously mixed, agglomerated and dispersed Al/AlN mixture (which enabled in-flight interaction between the powder and the surrounding plasma by wet-mixing in a planetary mill. Increasing the AlN content in the mixture prevented coalescence and increased the nitride content gradually. Using 30 to 40 wt% AlN was sufficient to fabricate a thick (more than 200 µm AlN coating with high hardness (approximately 1000 Hv. The AlN additive prevented the coalescence of Al metal and enhanced post-deposition nitriding through N2 plasma irradiation by allowing the nitriding species in the plasma to impinge on a larger Al surface area. Using AlN as a feedstock additive was found to be a suitable method for fabricating AlN coatings by reactive plasma spraying. Moreover, the fabricated coatings consist of hexagonal (h-AlN, c-AlN (rock-salt and zinc-blend phases and certain oxides: aluminum oxynitride (Al5O6N, cubic sphalerite Al23O27N5 (ALON and Al2O3. The zinc-blend c-AlN and ALON phases were attributed to the transformation of the h-AlN feedstock during the reactive plasma spraying. Thus, the zinc-blend c

  1. Retention and release mechanisms of tritium loaded in plasma-sprayed tungsten coatings by plasma exposure

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, T., E-mail: t-otsuka@nucl.kyushu-u.ac.jp [Kyushu University, Interdisciplinary Graduate School of Engineering and Sciences, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581 (Japan); Tanabe, T. [Kyushu University, Interdisciplinary Graduate School of Engineering and Sciences, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581 (Japan); Tokunaga, K. [Kyushu University, Research Institute for Applied Mechanics, Kasugakoen 6-1, Kasuga-shi, Fukuoka 816-8580 (Japan)

    2013-07-15

    Depth profiles of tritium (T) loaded by gas and plasma in tungsten (W) coatings on ferritic steels have been examined by using a tritium imaging plate technique and their changes during storage and after annealing have been monitored. The depth profiles of T consisted of 4 components, (I) T trapped at impurities and defects newly introduced in the near surface region of the coating by plasma loading, (II) T trapped at the inner surfaces of the grains and dissolved in the grains resulting in a flat depth profile throughout the whole coating, (III) T dissolved and diffused into the substrate giving a decaying profile, and (IV) T trapped at the backside surface of the substrate. The results support that retention of T is mainly caused by pore diffusion of gaseous T followed by dissolution and trapping in/at each W grain, and dissolution of T into the F82H substrate to allow permeation. Release of T proceeds in an opposite way of retention but each component desorbs independently.

  2. Design and optimization of coating structure for the thermal barrier coatings fabricated by atmospheric plasma spraying via finite element method

    Directory of Open Access Journals (Sweden)

    L. Wang

    2014-06-01

    Full Text Available The first prerequisite for fabricating the thermal barrier coatings (TBCs with excellent performance is to find an optimized coating structure with high thermal insulation effect and low residual stress. This paper discusses the design and optimization of a suitable coating structure for the TBCs prepared by atmospheric plasma spraying (APS using the finite element method. The design and optimization processes comply with the rules step by step, as the structure develops from a simple to a complex one. The research results indicate that the suitable thicknesses of the bond-coating and top-coating are 60–120 μm and 300–420 μm, respectively, for the single ceramic layer YSZ/NiCoCrAlY APS-TBC. The embedded interlayer (50 wt.%YSZ + 50 wt.%NiCoCrAlY will further reduce the residual stress without sacrificing the thermal insulation effect. The double ceramic layer was further considered which was based on the single ceramic layer TBC. The embedded interlayer and the upper additional ceramic layer will have a best match between the low residual stress and high thermal insulation effect. Finally, the optimized coating structure was obtained, i.e., the La2Ce2O7(LC/YSZ/Interlayer/NiCoCrAlY coating structure with appropriate layer thickness is the best choice. The effective thermal conductivity of this optimized LC/YSZ/IL/BL TBC is 13.2% lower than that of the typical single ceramic layer YSZ/BL TBC.

  3. Determination of Scattering and Absorption Coefficients for Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings at Elevated Temperatures

    Science.gov (United States)

    Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.

    2009-01-01

    The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."

  4. Thermal barrier ZrO2 - Y2O3 obtained by plasma spraying method and laser melting

    Directory of Open Access Journals (Sweden)

    K. Kobylańska–Szkaradek

    2006-04-01

    Full Text Available Purpose: Purpose: The aim of the paper is to determine the influence of laser melting upon the selected physical properties of ZrO2 - Y2O3 ceramic coatings deposited by APS (Air Plasma Spraying method on super-alloys which function as TBC (Thermal Barriers Coatings.Design/methodology/approach: Laser melting which helps eliminate pores and other structural defects of coatings should contribute to the improvement of their density and durability as thermal barriers. In order to prove the assumptions made in the paper, coatings featuring varied porosity and deposited upon the nickel base super-alloys surface with the initially sprayed NiCrAlY bond coat have been subjected to laser melting and then their structure, thermal conductivity and thermal life prediction in the conditions of cyclic temperature changes from 20 to 1200ºC have been examined.Findings: It has been revealed that the coatings featuring low porosity laser melted on part of their thickness and heated up to about 700ºC demonstrate the highest thermal life prediction under the conditions mentioned and at slightly lower thermal conductivity.Research limitations/implications: Low wettability of metal by ceramic which results from various surface tensions of these materials is the cause of their lower adhesion to the substrate during laser melting all through their thickness. It is so because delaminations occur between phases the boundary and cracks.Practical implications: The worked out conditions of laser melting might be used in the process of creation of TBC which feature high working durability upon super-alloy elements.Originality/value: It has been found that homogenization of chemical composition of coatings occurs during laser melting leading to the reduction of ZrO2 - Y2O3 phase with monoclinic lattice participation as well as to the reduction of structural stresses which accompany this phase transformation during heating and cooling process.

  5. Development of Plasma-Sprayed Molybdenum Carbide-Based Anode Layers with Various Metal Oxides for SOFC

    Science.gov (United States)

    Faisal, N. H.; Ahmed, R.; Katikaneni, S. P.; Souentie, S.; Goosen, M. F. A.

    2015-12-01

    Air plasma-sprayed (APS) coatings provide an ability to deposit a range of novel fuel cell materials at competitive costs. This work develops three separate types of composite anodes (Mo-Mo2C/Al2O3, Mo-Mo2C/ZrO2, Mo-Mo2C/TiO2) using a combination of APS process parameters on Hastelloy®X for application in intermediate temperature proton-conducting solid oxide fuel cells. Commercially available carbide of molybdenum powder catalyst (Mo-Mo2C) and three metal oxides (Al2O3, ZrO2, TiO2) was used to prepare three separate composite feedstock powders to fabricate three different anodes. Each of the modified composition anode feedstock powders included a stoichiometric weight ratio of 0.8:0.2. The coatings were characterized by scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction, nanoindentation, and conductivity. We report herein that three optimized anode layers of thicknesses between 200 and 300 µm and porosity as high as 20% for Mo-Mo2C/Al2O3 (250-µm thick) and Mo-Mo2C/TiO2 (300 µm thick) and 17% for Mo-Mo2C/ZrO2 (220-µm thick), controllable by a selection of the APS process parameters with no addition of sacrificial pore-forming material. The nanohardness results indicate the upper layers of the coatings have higher values than the subsurface layers in coatings with some effect of the deposition on the substrate. Mo-Mo2C/ZrO2 shows high electrical conductivity.

  6. Chemical stability and osteogenic activity of plasma-sprayed boron-modified calcium silicate-based coatings.

    Science.gov (United States)

    Lu, Xiang; Li, Kai; Xie, Youtao; Huang, Liping; Zheng, Xuebin

    2016-11-01

    In recent years, CaSiO3 bio-ceramic coatings have attracted great attention because of their good bioactivity. However, their high degradation rates in physiological environment restrict their practical applications. In this work, boron-modified CaSiO3 ceramic (Ca11Si4B2O22, B-CS) coating was developed on Ti substrates by plasma-spraying technique attempting to obtain enhanced chemical stability and osteogenic activity. The B-CS coating possessed significantly increased chemical stability due to the introduction of boron and consequently the modified crystal structure, while maintaining good bioactivity. Scanning electron microscope and immunofluorescence studies showed that better cellular adhesion and extinctive filopodia-like processes were observed on the B-CS coating. Compared with the pure CaSiO3 (CS) coating, the B-CS coating promoted MC3T3-E1 cells attachment and proliferation. In addition, enhanced collagen I (COL-I) secretion, alkaline phosphatase activity, and extracellular matrix mineralization levels were detected from the B-CS coating. According to RT-PCR results, notable up-regulation expressions of mineralized tissue-related genes, such as runt-related transcription factor 2 (Runx2), bone sialoprotein and osteocalcin, and bone morphogenetic protein 7 (BMP-7) were observed on the B-CS coating compared with the CS coating. The above results suggested that Ca11Si4B2O22 coatings possess excellent osteogenic activity and might be a promising candidate for orthopedic applications.

  7. Effect of Suspension Plasma-Sprayed YSZ Columnar Microstructure and Bond Coat Surface Preparation on Thermal Barrier Coating Properties

    Science.gov (United States)

    Bernard, Benjamin; Quet, Aurélie; Bianchi, Luc; Schick, Vincent; Joulia, Aurélien; Malié, André; Rémy, Benjamin

    2017-08-01

    Suspension plasma spraying (SPS) is identified as promising for the enhancement of thermal barrier coating (TBC) systems used in gas turbines. Particularly, the emerging columnar microstructure enabled by the SPS process is likely to bring about an interesting TBC lifetime. At the same time, the SPS process opens the way to a decrease in thermal conductivity, one of the main issues for the next generation of gas turbines, compared to the state-of-the-art deposition technique, so-called electron beam physical vapor deposition (EB-PVD). In this paper, yttria-stabilized zirconia (YSZ) coatings presenting columnar structures, performed using both SPS and EB-PVD processes, were studied. Depending on the columnar microstructure readily adaptable in the SPS process, low thermal conductivities can be obtained. At 1100 °C, a decrease from 1.3 W m-1 K-1 for EB-PVD YSZ coatings to about 0.7 W m-1 K-1 for SPS coatings was shown. The higher content of porosity in the case of SPS coatings increases the thermal resistance through the thickness and decreases thermal conductivity. The lifetime of SPS YSZ coatings was studied by isothermal cyclic tests, showing equivalent or even higher performances compared to EB-PVD ones. Tests were performed using classical bond coats used for EB-PVD TBC coatings. Thermal cyclic fatigue performance of the best SPS coating reached 1000 cycles to failure on AM1 substrates with a β-(Ni,Pt)Al bond coat. Tests were also performed on AM1 substrates with a Pt-diffused γ-Ni/γ'-Ni3Al bond coat for which more than 2000 cycles to failure were observed for columnar SPS YSZ coatings. The high thermal compliance offered by both the columnar structure and the porosity allowed the reaching of a high lifetime, promising for a TBC application.

  8. Nondestructive inspection of plasma-sprayed metallic coatings for coal conversion equipment

    Energy Technology Data Exchange (ETDEWEB)

    Scott, G.W.; Snyder, S.D.; Simpson, W.A. Jr.

    1979-12-01

    This report describes the results of a project to develop nondestructive inspection techniques for metallic wear- and process-resistant coatings used in coal system components. Physical properties, especially porosity, and the nominal 0.25 mm (0.010 in.) thickness complicate the inspection of these coatings. The class of coatings selected for laboratory evaluation were CoCrAlY (cobalt-chromium-aluminum-yttrium) types; the specific material used was a Union Carbide spray powder, UCAR LCO-7, which is Co-22.8% Cr-12.9% Al-0.6% Y, sprayed onto alloy 800 substrates. The desired inspection techniques were to: (1) detect cracks or holes in the coating; (2) measure the coating thickness from the coated side; and (3) detect lamellar flaws or separations within the coating layer or between the coating and the substrate. Surface methods (such as liquid penetrant), eddy currents, and radiography were investigated for crack and hole detection; eddy currents, x-ray fluorescence, and ultrasonics were investigated for thickness measurement; and ultrasonics and infrared thermography were investigated for lamellar flaw detection. In general, we determined that significant development effort was required to adapt even the more common and highly developed techniques to the coating inspection problems. Significant progress was made in a number of the investigations undertaken, but financial restraints prevented completion of the planned work.

  9. Friction and Wear Characteristics of a Modified Composite Solid Lubricant Plasma Spray Coating

    Science.gov (United States)

    Stanford, M. K.; DellaCorte, C.

    2004-01-01

    LCR304 is a solid lubricant coating composed of Ni-10Cr, Cr2O3, BaF2-CaF2 and Ag and developed for dimensional stability in high temperature air. This coating is a modification of PS304, which differs in that the Ni-Cr constituent contains 20wt% Cr. The tribological characteristics of LCR304 were evaluated by pin-on-disk and foil air bearing rig testing from 25 to 650 C and compared to previous test results with PS304. For both tests, the friction coefficient decreased as temperature increased from 25 to 650 C. Wear generally decreased with increasing temperature for all pin-on-disk tests. LCR304 coated components produced the least wear of Inconel X-750 counterface materials at 427 and 650 C. These results indicate that the LCR304 coating has potential as a replacement for PS304 in, for example, low cycle (minimum wear) applications where dimensional stability is imperative.

  10. The femoral sulcus in total knee arthroplasty.

    Science.gov (United States)

    Lingaraj, Krishna; Bartlett, John

    2009-05-01

    The position of the femoral sulcus relative to the midline of the distal femoral resection in total knee arthroplasty (TKA) was studied to determine if centralized placement of the femoral component on the distal femur was justified in terms of aligning the prosthetic sulcus with the native femoral sulcus. The location of the femoral sulcus was studied in 112 consecutive patients undergoing TKA. The mean sulcus position was 0.7 mm lateral to the midline of the distal femoral resection (SD 1.4, 95% CI, 0.5-1.0 mm). However, the variation in sulcus positions ranged from 4 mm medial to 4 mm lateral to the midline. The mean sulcus position in valgus knees was 1.0 mm lateral to the midline (SD 1.8), and that in varus knees was 0.7 mm lateral to the midline (SD 1.2) (P = 0.501). It appears prudent to centre the femoral component on the native sulcus rather than the midline of the distal femoral resection, so as to ensure accurate alignment of the prosthetic sulcus with the native sulcus and to encourage normal patella tracking.

  11. Photoresponse and Donor Concentration of Plasma-Sprayed TiO2 and TiO2-ZnO Electrodes

    Science.gov (United States)

    Ye, F.-X.; Ohmori, A.; Li, C.-J.

    2005-12-01

    The photoelectrochemical characteristics of plasma-sprayed porous TiO2, TiO2-5%ZnO, and TiO2-10%ZnO electrodes in 0.1 N NaOH solution were studied through a three-electrode cell system. The microstructure, morphology, and composition of the electrodes were analyzed using an electron probe surface roughness analyzer (ERA-8800FE), scanning electron microscopy, and x-ray diffraction. The results indicate that the sprayed electrodes have a porous microstructure, which is affected by the plasma spray parameters and composition of the powders. The TiO2-ZnO electrodes consist of anatase TiO2, rutile TiO2, and Zn2Ti3O8 phase. The photoresponse characteristics of the plasma-sprayed electrodes are comparable to those of single-crystal TiO2, but the breakdown voltage is close to 0.5 V (versus that of a saturated calomel electrode). The short-circuit photocurrent density ( J SC) increases with a decrease of donor concentration, which was calculated according to the Gartner-Butler model. For the lowest donor concentration of a TiO2-5%ZnO electrode sprayed under an arc current of 600 A, the short-circuit J SC is approximately 0.4 mA/cm2 higher than that of the TiO2 electrodes under 30 mW/cm2 xenon light irradiation. The J SC increases linearly with light intensity.

  12. Experience of high-nitrogenous steel powder application in repairs and surface hardening of responsible parts for power equipment by plasma spraying

    Science.gov (United States)

    Kolpakov, A. S.; Kardonina, N. I.

    2016-02-01

    The questions of the application of novel diffusion-alloying high-nitrogenous steel powders for repair and surface hardening of responsible parts of power equipment by plasma spraying are considered. The appropriateness of the method for operative repair of equipment and increasing its service life is justified. General data on the structure, properties, and manufacture of nitrogen-, aluminum-, and chromium-containing steel powders that are economically alloyed using diffusion are described. It is noted that the nitrogen release during the decomposition of iron nitrides, when heating, protects the powder particles from oxidation in the plasma jet. It is shown that the coating retains 50% of nitrogen that is contained in the powder. Plasma spraying modes for diffusion-alloying high-nitrogenous steel powders are given. The service properties of plasma coatings based on these powders are analyzed. It is shown that the high-nitrogenous steel powders to a nitrogen content of 8.9 wt % provide the necessary wear resistance and hardness of the coating and the strength of its adhesion to the substrate and corrosion resistance to typical aggressive media. It is noted that increasing the coating porosity promotes stress relaxation and increases its thickness being limited with respect to delamination conditions in comparison with dense coatings on retention of the low defectiveness of the interface and high adhesion to the substrate. The examples of the application of high-nitrogenous steel powders in power engineering during equipment repairs by service companies and overhaul subdivisions of heat power plants are given. It is noted that the plasma spraying of diffusion-alloyed high-nitrogenous steel powders is a unique opportunity to restore nitrided steel products.

  13. Effect of pores on the micromechanics of plasma-sprayed Cr3C2-NiCr coating in the nanoindentation testing

    Science.gov (United States)

    Zhang, Yongang; Wang, Yinzhen; Feng, Tao; Sun, Yongxing; Dong, Junzhe; Gao, Wei

    2017-07-01

    The elastoplastic properties of plasma-sprayed Cr3C2-NiCr coatings were obtained through the dimension analysis and inverse analysis by combining the experimental nanoindentation tests and numerical modeling. The digital image processing technique was used to extract the pore distribution inside the coatings based on the actual microstructure. Finally, the effect of pore distribution on the coating residual stress during nanoindentation process was analyzed through simulations. The anisotropic pore microstructure shows different mechanical responses and stress propagation behaviors during nanoindentation process. The elastic modulus of the coating demonstrates anisotropy along the spraying direction and the transverse directions due to the presence of pores.

  14. Tribological properties of La2O3 and CeO2 doped CoCrW coatings deposited by supersonic plasma spraying

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel supersonic plasma spraying was used to prepare rare earth oxides doped CoCrW coatings. X-ray diffractometer, contact surface profiler, hardness tester, micro-friction and -wear tester and environmental scanning electron microscope equipped with energy dispersive X-ray spectroscopy were employed to investigate the phase structure, surface morphology, microhardness, friction and wear properties of the sprayed coatings. The results show that rare earth oxide doped coatings have high microhardness and excellent tribological properties. Furthermore, the friction and wear mechanisms of sprayed coatings are also discussed.

  15. Microstructure and properties of in-flight rare-earth doped thermal barrier coatings prepared by suspension plasma spray

    Science.gov (United States)

    Gong, Stephanie

    Thermal barrier coatings with lower thermal conductivity improve the efficiency of gas turbine engines by allowing higher operating temperatures. Recent studies were shown that coatings containing a pair of rare-earth oxides with equal molar ratio have lower thermal conductivity and improved sintering resistance compared to the undoped 4-4.5 mol.% yttria-stabilized zirconia (YSZ). In the present work, rare-earth doped coatings were fabricated via suspension plasma spray by spraying YSZ powder-ethanol suspensions that contained dissolved rare-earth nitrates. The compositions of the coatings determined by inductively coupled plasma mass spectroscopy verified that 68 +/- 8% of the rare-earth nitrates added into the suspension was incorporated into the coatings. Two coatings containing different concentrations of the same dopant pair (Nd2O3/Yb2O3), and three coatings having similar concentrations of different dopant pairs (Nd 2O3/Yb2O3, Nd2O3/Gd 2O3, and Gd2O3/Yb2O 3) were produced and compared. The effect of dopant concentration and dopant pair type on the microstructure and properties of the coatings in the as-sprayed and heat treated conditions were investigated using XRD, SEM, TEM, STEM-EDX, and the laser flash method. The cross-sectional morphology of all coatings displayed columnar structure. The porosity content of the coating was found to increase with increasing dopant concentration, but did not significantly change with dopant pairs. Similarly, increasing the Nd2O3/Yb2O 3 concentration lowered the thermal conductivity of the as-sprayed coatings. Although the effect of changing dopant pair type is not as significant as increasing the dopant concentration, the coating that contained Gd2O 3/Yb2O3 exhibited the lowest conductivity compared to coatings that had other dopant pairs. Thermal conductivity measurement performed on the heat treated coatings indicated a larger conductivity increase for the rare-earth doped coatings. A detailed study on the

  16. CT Assessment of the axial deviation of the femoral and tibial prosthetic components in total knee arthroplasty; Valutazione con Tomografia Computerizzata della rotazione delle componenti femorale e tibiale nell'artroprotesi totale del ginocchio

    Energy Technology Data Exchange (ETDEWEB)

    Rimondi, E.; Molinari, M.; Moio, A.; Busacca, M. [Istituto Ortopedico Rizzoli, Bologna (Italy). Servizio di Diagnostica per Immagini; Trentani, F.; Trentani, P.; Tigani, D. [Istituto Ortopedico Rizzoli, Bologna (Italy). VII Div.; Nigrosoli, M. [Istituto Ortopedico Rizzoli, Bologna (Italy). IV Div.

    2000-06-01

    CT assessment of the axial deviation of the femoral and tibial prosthetic components in total knee arthroplasty. From January to July 1999, 17 patients, 10 males and 7 females, mean age 66 years (standard deviation plus or minus 4) were examined after total knee arthroplasty. Exclusion criteria were prosthesis loosening and severe (equal or superior to 7 degrees) varus o valgus deviation. All patients were examined with knee radiography in the standing position completed by axial projection of patella and by CT scanning. It was used a modification of Berger technique and carried out comparative CT scans extended lower limbs and acquisitions perpendicular to the mechanical axis of the knee, from the femoral supracondylar region down to the plane crossing the distal end of the tibial prosthetic component. Reference lines were then drawn electronically on given scanning planes to reckon the axial deviation of the femoral and tibial prosthetic components. Six patients, one female and 5 males with normal rotational values of femoral and tibial prosthetic components presented no clinical symptoms. Eight patients, 4 females and 4 males, with abnormal values presented the following clinical symptoms: medial impingement, (incomplete) dislocation patella, and lateral instability. One female patient with a normal rotational value of femoral prosthetic component and an altered value of tibial prosthetic component presented medial impingement. Finally two patients, one female and one male, were absolutely asymptomatic although the rotational values of the two prosthetic components were beyond the normal range. Total knee arthroplasty is presently a standard treatment for many conditions involving this joint. There are several possible postoperative complications, namely fractures, dislocations (a)septic losening and femoropatellar instability. The latter condition is the most frequent complication among implant failures and is caused by bad orientation of the femoral and tibial

  17. PLASMA SPRAYED Al₂O₃-13 WT.%TiO₂ COATING SEALED WITH ORGANIC-INORGANIC HYBRID AGENT AND ITS CORROSION RESISTANCE IN ACID ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Zehua Zhou

    2016-07-01

    Full Text Available A novel organic-inorganic hybrid material of γ-methacryloxypropyltrime-thoxysilane (KH570 -SiO₂ was fabricated by Sol-Gel method. The hybrid material was used as the sealing agent for the plasma sprayed Al₂O₃-13 wt.% TiO₂ coating. Infrared spectrum and grafted mechanism of the hybrid agent (HA were studied. Moreover, morphology and porosity, as well as characteristics of immersion plus electrochemical corrosion in acid environment of the coating with and without sealing treatment were evaluated, compared with those of the coating sealed with the conventional silicone resin agent (SRA. The results reveal that KH570 was successfully grafted onto the surface of SiO₂. The HA film sealed on the surface of the coating presents a little better quality than the SRA film. The porosities of the coatings after the sealing treatment decreased. Furthermore, the sealing treatment can improve efficiently the corrosion resistance of the coating in 5 vol.% HCl solution. The hybrid sealing agent can become a candidate for the plasma sprayed Al₂O₃-13 wt.% TiO₂ coating used in acid environment to overcome some disadvantages of organic agents such as severely environmental pollution.

  18. Establishing empirical relationships to predict porosity level and corrosion rate of atmospheric plasma-sprayed alumina coatings on AZ31B magnesium alloy

    Directory of Open Access Journals (Sweden)

    D. Thirumalaikumarasamy

    2014-06-01

    Full Text Available Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. In this work, empirical relationships were developed to predict the porosity and corrosion rate of alumina coatings by incorporating independently controllable atmospheric plasma spray operational parameters (input power, stand-off distance and powder feed rate using response surface methodology (RSM. A central composite rotatable design with three factors and five levels was chosen to minimize the number of experimental conditions. Within the scope of the design space, the input power and the stand-off distance appeared to be the most significant two parameters affecting the responses among the three investigated process parameters. A linear regression relationship was also established between porosity and corrosion rate of the alumina coatings. Further, sensitivity analysis was carried out and compared with the relative impact of three process parameters on porosity level and corrosion rate to verify the measurement errors on the values of the uncertainty in estimated parameters.

  19. Cracking caused by cutting of plasma-sprayed hydroxyapatite coatings and its relation to the structural features of coatings deposited at different initial substrate temperatures

    Directory of Open Access Journals (Sweden)

    Gligorijević Bojan R.

    2017-01-01

    Full Text Available The present study estimated the cracking phenomenon in as-plasma-sprayed hydroxylapatite coatings (HACs after they were being subjected to the severe cutting conditions in the direction perpendicular to the coating/substrate interface. In order to evaluate the effects of substrate preheating on the occurrence of micro-cracks, the HACs were deposited at different initial substrate temperatures (TS = 20, 100 and 200°C. The changes in phase composition and HA splat morphology with TS were observed and were correlated with the cracking occurrence. The results showed that severe cutting conditions introduced a localized cracking in the regions of HACs dominantly attributed to the brittle hydroxyl-deficient amorphous calcium phosphate (ACP phase. This effect was particularly observable in the HACs deposited without preheating of substrate. On the other hand, the preheating of substrate reduced the presence of micro-cracks and caused insignificant changes in the average local phase composition. In HACs deposited with preheating of substrate, the HA splats (of which HACs are composed were thinner and recrystallized HA regions seemed smaller in size and more evenly distributed. These results implied potentially important roles of the HA splat formation mechanism on the distribution of ACP and recrystallized HA regions in the as-plasma-sprayed HACs and the cracking resistance of HACs. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 34022

  20. Effect of Gd2O3 on the microstructure and thermal properties of nanostructured thermal barrier coatings fabricated by air plasma spraying

    Institute of Scientific and Technical Information of China (English)

    Yixiong Wang; Chungen Zhou

    2016-01-01

    The nanostructured 4–8 mol% Gd2O3-4.5 mol% Y2O3-ZrO2 (4–8 mol% GdYSZ) coatings were developed by the atmospheric plasma spraying technique. The microstructure and thermal properties of plasma-sprayed 4–8 mol%GdYSZ coatings were investigated. The experimental results indicate that typical mi-crostructure of the as-sprayed coatings were consisted of melted zones, nano-zones, splats, nano-pores, high-volume spheroidal pores and micro-cracks. The porosity of the 4, 6 and 8 mol%GdYSZ coatings was about 9.3%, 11.7%and 13.3%, respectively. It was observed that the addition of gadolinia to the nano-YSZ could significantly reduce the thermal conductivity of nano-YSZ. The thermal conductivity of GdYSZ decreased with increasing Gd2O3 addition. And the reduction in thermal conductivity is mainly attrib-uted to the addition of Gd2O3, which results in the increase in oxygen vacancies, lattice distortion and porosity.

  1. Failure Behavior of Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings Under Three-Point Bending Test via Acoustic Emission Technique

    Science.gov (United States)

    Wang, L.; Ni, J. X.; Shao, F.; Yang, J. S.; Zhong, X. H.; Zhao, H. Y.; Liu, C. G.; Tao, S. Y.; Wang, Y.; Li, D. Y.

    2017-01-01

    In this paper, the failure behavior of plasma-sprayed yttria-stabilized zirconia thermal barrier coatings fabricated by atmospheric plasma spraying (APS-TBCs) under three-point bending (3PB) test has been characterized via acoustic emission (AE) technique. Linear positioning method has been adopted to monitor dynamic failure process of the APS-TBCs under 3PB test. The investigation results indicate that the variation of AE parameters (AE event counts, amplitudes and AE energy) corresponds well with the change of stress-strain curve of the loading processes. The failure mechanism was analyzed based on the characteristics of AE parameters. The distribution of frequency of crack propagation has been obtained. The AE signals came from two aspects: i.e., plastic deformation of substrates, initiation and propagation of the cracks in the coatings. The AE analysis combined with cross-sectional observation has indicated that many critical cracks initiate at the surface of the top-coat. And some main cracks tend to propagate toward the substrate/bond-coat interface. The actual failure mechanism of the APS-TBCs under 3PB test is attributed to the debonding of metallic coating from the substrates and the propagation of the horizontal crack along the substrate/bond-coat interface under the action of flexural moment.

  2. Effect of Gd2O3 on the microstructure and thermal properties of nanostructured thermal barrier coatings fabricated by air plasma spraying

    Directory of Open Access Journals (Sweden)

    Yixiong Wang

    2016-08-01

    Full Text Available The nanostructured 4–8 mol% Gd2O3−4.5 mol% Y2O3-ZrO2 (4–8 mol% GdYSZ coatings were developed by the atmospheric plasma spraying technique. The microstructure and thermal properties of plasma-sprayed 4–8 mol% GdYSZ coatings were investigated. The experimental results indicate that typical microstructure of the as-sprayed coatings were consisted of melted zones, nano-zones, splats, nano-pores, high-volume spheroidal pores and micro-cracks. The porosity of the 4, 6 and 8 mol% GdYSZ coatings was about 9.3%, 11.7% and 13.3%, respectively. It was observed that the addition of gadolinia to the nano-YSZ could significantly reduce the thermal conductivity of nano-YSZ. The thermal conductivity of GdYSZ decreased with increasing Gd2O3 addition. And the reduction in thermal conductivity is mainly attributed to the addition of Gd2O3, which results in the increase in oxygen vacancies, lattice distortion and porosity.

  3. Characterisations Of Al2O3-13% Wt TiO2 Deposition On Mild Steel Via Plasma Spray Method

    Science.gov (United States)

    Yusoff, N. H.; Ghazali, M. J.; Isa, M. C.; Daud, A. R.; Muchtar, A.; Forghani, S.

    2011-01-01

    To date, plasma sprayed alumina titania have been widely used as wear resistance coatings in textile, machinery and printing industries. Previous studies showed that the coating microstructures and properties were strongly depended on various parameters such as ceramic composition, grain size powders and spray parameters, thus, influencing the melting degree of the alumina titania during the deposition process. The aim of this study focuses on the evolution of the micron sizes of alumina-13%wt titania at different plasma spray power, ranging from 20kW to 40kW. It was noted that the coating porosity of alumina-13%wt titania were decreased from 6.2% to 4% by increasing the plasma power from 20 to 40 kW. At lower power value, partially melted powders were deposited, generating over 6% porosity within the microstructures. Percentage of porosity about 5.6% gave the best ratio of bi-modal structures, providing the highest microhardness value. Furthermore, the effect of microstructure and porosity formation on wear resistance was also discussed. Coatings with less porosity exhibited better resistance to wear, in which the wear resistance of coated mild steel possessed only ˜5 x 10-4 cm3/Nm with 4% of porosity.

  4. The Influence of Temperature on Frictional Behavior of Plasma-Sprayed NiAl-Cr2O3 Based Self-Adaptive Nanocomposite Coatings

    Science.gov (United States)

    Ramazani, M.; Ashrafizadeh, F.; Mozaffarinia, R.

    2013-10-01

    Frictional behavior of nano and hybrid-structured NiAl-Cr2O3-Ag-CNT-WS2 adaptive self-lubricant coatings was evaluated at a range of temperatures, from room temperature to 700 °C. For this purpose, hybrid structured (HS) and nanostructured (NS) composite powders with the same nominal compositions were prepared by spray drying and heat treatment techniques. A series of HS and NS coating samples were deposited on steel substrate by an atmospheric plasma spraying process. The tribological behavior of both coatings was studied from room temperature to 700 °C at 100° intervals using a custom designed high temperature wear test machine. Scanning electron microscopy was employed for the evaluation of the composite coatings and worn surfaces. Experimental results indicated that the hybrid coating had inferior tribological properties when compared to the nanostructured coating, showing the attractive frictional behavior on the basis of low friction and high wear resistance; the NS coating possessed a more stable friction coefficient in the temperature range of 25-700 °C against alumina counterface. Microstructural examinations revealed more uniformity in NS plasma-sprayed coatings.

  5. Investigation into the diffusion and oxidation behavior of the interface between a plasma-sprayed anode and a porous steel support for solid oxide fuel cells

    Science.gov (United States)

    Zhang, Shan-Lin; Li, Cheng-Xin; Li, Chang-Jiu; Liu, Meilin; Yang, Guan-Jun

    2016-08-01

    Porous metal-supported solid oxide fuel cells (SOFCs) have attracted much attention because their potential to dramatically reduce the cost while enhancing the robustness and manufacturability. In particular, 430 ferritic steel (430L) is one of the popular choice for SOFC support because of its superior performance and low cost. In this study, we investigate the oxidation and diffusion behavior of the interface between a Ni-based anode and porous 430L support exposed to a humidified (3% H2O) hydrogen atmosphere at 700 °C. The Ni-GDC (Ce0.8Gd0.2O2-δ) cermet anodes are deposited on the porous 430L support by atmospheric plasma spraying (APS). The effect of exposure time on the microstructure and phase structure of the anode and the supports is studied and the element diffusion across the support/anode interface is characterized. Results indicate that the main oxidation product of the 430L support is Cr2O3, and that Cr and Fe will diffuse to the anode and the diffusion thickness increases with the exposure time. The diffusion thickness of Cr and Fe reach about 5 and 2 μm, respectively, after 1000 h exposure. However, the element diffusion and oxidation has little influence on the area-specific resistance, indicating that the porous 430L steel and plasma sprayed Ni-GDC anode are promising for durable SOFCs.

  6. 等离子喷涂B4C涂层的抗辐射性能研究%Anti-radiation behavior of plasma sprayed boron carbide coatings

    Institute of Scientific and Technical Information of China (English)

    李龙根; 徐志勇; 钱浩

    2009-01-01

    目的 研究用等离子技术喷涂的碳化硼(B4C)涂层的抗辐射能力.方法 将0.1 mm厚度B4C涂在16号锰钢上,研究它对加速器产生的6、10、15 MV高能射线,6、9、12、15 MeV高能电子线,60Co γ线和快中子辐射的防护作用.同时将0.1 mm B4C涂在纸板上,研究它对深部X线机的X线辐射的防护作用.结果 等离子喷涂制备B4C涂层对高能X线和60Co γ线没有防护作用.对电子线有一定防护作用,且随深度的增加有增大趋势,但作用不大.对快中子有较大防护作用.对深部X线机X线有防护作用,防护能力较强.0.1 mm厚的涂层就可带来15%的衰减.结论 用等离子技术喷涂的B4C涂层可在医学领域用来防护千伏级射线.%Objective To study anti-radiation behavior of plasma sprayed boron carbide coatings. Methods The anti-radiation capacity of 16Mn steel which was coated with 0.1 mm plasma sprayed boron carbide were studied. The irradiation beams were 6,10,15 MY X-ray and 6,9,12,15 MeV electron emitted by accelerator, X-ray emitted by 60Co machine,fast neutron, and X-ray emitted by kilovoltage X-ray ma-chine. Results Anti-radiation capacity of plasma sprayed boron carbide coatings was not found for X-ray beams emitted by accelerator and 60Co machine. For electron beams,the anti-radiation capacity were found. The deeper of location, the stronger was anti-radiation. However, the anti-radiation capacity was not good. For fast neutron,the anti-radiation capacity was good. For X-ray emitted by kilovoltage X-ray machine,the anti-radiation was good,and only 0.1 nun plasma sprayed boron carbide had 15% attenuation. Conclusions The plasma sprayed boron carbide coatings have the anti-radiation capacity for X-ray emitted by kilovoltage X-ray machine in medical field.

  7. Femoral hernia causing pneumoperitoneum.

    OpenAIRE

    King, H. A.; Boulter, P. S.

    1986-01-01

    Richter's hernia, in which only a portion of the circumference of the intestine lies within the sac, is a common complication of femoral hernia. This case report is of 39 year old female who presented with a pneumoperitoneum and was found at laparotomy to have a right femoral Richter's hernia containing a knuckle of perforated small bowel. This is a previously unreported presentation of femoral hernia.

  8. Femoral hernia repair

    Science.gov (United States)

    Femorocele repair; Herniorrhaphy; Hernioplasty - femoral ... During surgery to repair the hernia, the bulging tissue is pushed back in. The weakened area is sewn closed or strengthened. This repair ...

  9. Mullite Plasma Spraying for In Situ Repair of Cracks in Mullite Refractories: Simultaneous Optimization of Porosity and Thickness by Statistical Design of Experiments

    Science.gov (United States)

    Schrijnemakers, A.; Francq, B. G.; Cloots, R.; Vertruyen, B.; Boschini, F.

    2013-10-01

    We report a laboratory-scale study about the suitability of the plasma spraying process for "in situ" repair of cracks in mullite refractories of industrial furnaces. The "design of experiments" approach is used to investigate how the coating porosity and thickness are influenced by six experimental parameters. Arc current, secondary gas (H2) flow rate, and stand-off distance are the most significant parameters for both responses. Several interaction terms also affect significantly the thickness response. The validity of the model equations is discussed both from a statistical point of view and regarding the physical credibility of the main model terms. Additional experiments confirm that the measured properties lie into the prediction intervals provided by the model. Using a set of parameters optimized for minimal porosity and high thickness (relevant for the crack repair application), coatings with 6% porosity and 1070 μm thickness can be prepared reproducibly.

  10. Combination Effect of Dry-Ice Blasting and Substrate Preheating on Plasma-Sprayed CoNiCrAlY Splats

    Science.gov (United States)

    Dong, Shujuan; Song, Bo; Hansz, Bernard; Liao, Hanlin; Coddet, Christian

    2013-02-01

    CoNiCrAlY splats were plasma-sprayed on the stainless steel substrate which was pretreated by dry-ice blasting. Only impact marks were distinguished on the glycerol-polluted substrate, while halo donut splats formed on the pretreated substrate because of the cleaning effect of dry-ice blasting on this organic substance. The proportions of different splat types vary as a function of the treatment time of dry-ice blasting. The condensation phenomenon was also detected on the substrate surface accompanying the cleaning effect after the pretreatment of dry-ice blasting. In this study, dry-ice blasting was investigated to be coupled with substrate preheating to control the substrate temperature. It was found that a regular disk-like CoNiCrAlY splat can be obtained as the substrate temperature is higher than dew point temperature.

  11. Effects of La2O3 on the microstructure and tribological properties of plasma-sprayed Cr2O3-TiO2 coatings

    Science.gov (United States)

    Ding, Qingjun; Zhang, Aihua; Zhao, Gai; Peng, Hanmin; Gao, Wei

    2017-07-01

    Cr2O3-TiO2 coatings with different proportions of La2O3 were deposited by atmospheric plasma spraying. The coatings were evaluated by hardness tester, surface roughness tester, SEM and wear tester. The experiment results showed that the addition of La2O3 could improve the microhardness and decrease porosity, wear rate and surface roughness of the coating. The coating containing 2 wt.% La2O3 had the best tribological properties. The dominant wear mechanism is a mixture of abrasive wear and adhesive wear. The microscopic analysis suggests that the addition of La2O3 could refine the microstructure and promote the formation of solid solution powder, and then affect the properties of coatings.

  12. Y2O3-CeO2-ZrO2 Powder Prepared by Co-Precipitation and As-Plasma-Sprayed Coating

    Institute of Scientific and Technical Information of China (English)

    SHAO Gang-qin; ZHANG Wen-xi; HOU Zhong-tao; YUAN Run-zhang

    2004-01-01

    The Y2O3-CeO2-ZrO2 powders were prepared using a co-precipitation process and the corresponding coatings were prepared by plasma spraying. The results show that an optimal composition exists in Y2O3-doped CeO2-ZrO2, but not in CeO2-doped Y2O3-ZrO2. The powders mainly contain tetragonal phase and a trace amount of monoclinic phase. The homogeneity in composition, large agglomerate size, ideal particle size distribution and high flowability were obtained. The as-sprayed coatings are composed of non-transformable tetragonal phase, tz′structure, and resistant to transformation under thermal or mechanical stresses.

  13. Properties of plasma sprayed NiCrAlY + (ZrO2 + Y2 O3 ) coating on refractory steel surface

    Institute of Scientific and Technical Information of China (English)

    L(U) Tao; CHEN Fei; DING Hua-dong; HAN Dan-feng

    2005-01-01

    NiCrAlY + (ZrO2 + Y2 O3 ) thermal barrier coating was prepared on the surface of refractory steel 1Cr18Ni9Ti with plasma spraying technique. The phases and microstructure of the thermal barrier coating were determined by scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results show that the bonding between thermal barrier coating and substrate is sound. The surface hardness of 1Cr18Ni9Ti reaches up to 1 000 HV, but that of substrate is only 300 HV. The patterns sprayed with CoNiCrAlY+(ZrO2+Y2 O3 ) ceramic coating have a good heat insulation effect at 800 ℃ for heat insulation temperature difference reaches 54 ℃, which increases the operating temperature and service life of refractory steel.

  14. Characterization of functionally graded ZrO2 thermal barrier coatings sprayed by supersonic plasma spray with dual powder feed ports

    Institute of Scientific and Technical Information of China (English)

    HAN Zhi-hai; WANG Hai-jun; ZHOU Shi-kui; XU Bing-shi

    2005-01-01

    The functionally graded thermal barrier coatings (FG-TBCs) with 80 % ZrO2-13 % CeO2-7 % Y2 Os ( CYSZ)/NiCoCrAlY were prepared using a recently developed supersonic plasma spraying(S-PS) with dual powder feed ports system. The thermal shock experiment of FG-TBCs specimens was carried out by means of the automatic thermal cycle device, in which the samples were heated to 1 200 ℃ by oxygen-acetylene flame jet then waterquenched to ambient temperature. The temperature-time curves of specimens and photographs can be watched online and recorded by a computer during the test. The results show that the totally 1 mm-thick FG-TBCs have excellent thermal shock resistance due to the fact that the coatings have no any peeling-off after 200 thermal cycles. The microstructures and morphologies of FG-TBCs were characterized and analyzed by SEM.

  15. Effects of various power process parameters on deposition efficiency of plasma-sprayed Al2O3-40% wt.TiO2 coatings

    Science.gov (United States)

    Wang, Y. J.; Xu, J. Y.; Zhao, Q. H.; Wang, Y.; Gao, B.

    2017-06-01

    To investigate effects of various power process parameters on deposition efficiency, Al2O3-40% wt. TiO2 is selected as raw material to be coated on Q235 steel substrate by air plasma spraying. Different variables of spraying current and voltage are designed, whose spraying power is from 12.8 KW to 16.8 KW and increment step is 0.8 KW. Deposition thickness is proposed as a simple method to characterize the deposition efficiency of coatings. Analysis of variance is used to observe the difference between two adjacent groups. It is shown that deposition efficiency increases with the increase of spraying current; by and large, it firstly rises and then decreases with the increment of spraying voltage. However, the effects of increasing the latter are much stronger on deposition efficiency.

  16. Optimized functionally graded La{sub 2}Zr{sub 2}O{sub 7}/8YSZ thermal barrier coatings fabricated by suspension plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chaohui [Laboratory of Nano Surface Engineering, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Wang, You, E-mail: wangyou@hit.edu.cn [Laboratory of Nano Surface Engineering, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Fan, Shan; You, Yuan [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Wang, Liang [Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201899 (China); Yang, Changlong [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Sun, Xiaoguang [National Engineering Research Center for High-speed EMU, CSR Qingdao Sifang Co. Ltd., Qingdao 266111 (China); Li, Xuewei [Laboratory of Nano Surface Engineering, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-11-15

    In this paper, an optimized functionally graded coating (OFGC) was successfully fabricated by suspension plasma spraying (SPS) with feedstocks of the suspension of nanoparticles. La{sub 2}Zr{sub 2}O{sub 7}/8YSZ OFGC with gradual compositional variation along the through-thickness direction is proposed to mitigate spallation and crack formation owing to the high residual stresses caused by frequent thermal cycling for TBCs. The single ceramic layer coatings (SCLC) of LZ and double ceramic layer coatings (DCLC) of LZ/8YSZ were fabricated by SPS as comparison. The phase composition and microstructure of the SCLC, OFGC and DCLC were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS). Moreover, the thermal cycling tests were carried out to evaluate their thermal shock behavior. Changes in weight and morphology of specimens were analyzed during thermal cycling tests. The results showed that OFGC has extended lifetime compared with SCLC and DCLC. The failure of DCLC with clear interface between different ceramic layers occurred via delamination mode, as a result of crack initiation and propagation generated by thermal mismatch between LZ and 8YSZ. While the failure of OFGC occurred in thermally grown oxide (TGO) layers, indicating that the gradual compositional variation avoided thermal stress concentration in the top ceramic layers. - Highlights: • Optimized functionally graded coatings and double ceramic layer coatings were deposited by suspension plasma spray. • The graded area of OFGC is continuously changed from inner 8YSZ to outer La{sub 2}Zr{sub 2}O{sub 7} (LZ). • The OFGC shows a more extended thermal cycling life than the LZ SCLC and LZ/8YSZ DCLC. • Various failure mechanisms were proposed to explain thermal cycling behavior.

  17. Determination of characteristics of erosion wear of grade 15Kh11MF steel with the Cr-CrC ion-plasma sprayed coating

    Science.gov (United States)

    Seleznev, L. I.; Mednikov, A. F.; Tkhabisimov, A. B.; Ryzhenkov, A. V.; Kachalin, G. V.; Zilova, O. S.

    2016-06-01

    Results of investigations of the influence of a Cr-CrC ion-plasma sprayed protective coating on characteristics and the intensity of erosion wear of grade 15Kh11MF steel at a gas-abrasive flow incidence angle of 30° and an experimental specimen (target) surface temperature of 550°C are presented. The Cr-CrC ion-plasma sprayed coating was formed in a Gefest vacuum installation by magnetron deposition. Investigations of the formed coating were carried out using a research and experimental facility complex that provided the study of the composition and structure of the coating, measurement of its thickness, roughness, microhardness, and determination of its relative resistance at the combined action of the gas-abrasive flow and high temperatures. The Cr-CrC coating with a thickness of 6.5 ± 0.3 μm has a finegrained structure with grains with dimensions of 20-40 nm and contains layers of chromium and chromium carbide. The main coating element is chromium. Its content in carbide layers is 89.4-91.9% at a carbon content of 6.8-9.5%. The coating microhardness is H 0.05 = 1350 ± 50 HV. The maximum wear of the 15Kh11MF steel target is observed at the angle of the gas-abrasive flow incidence that is close to 30° (30 7°). With this incidence angle and a target surface temperature of 550°C, the Cr-CrC coating extends the term to the surface failure and the appearance of a clear abrasive trace no less than four times. The coating failure has a local character, i.e., the target surface forms islands with the coating, between which the intensive wear of the base material occurs.

  18. Radiographic femoral varus measurement is affected unpredictably by femoral rotation

    DEFF Research Database (Denmark)

    Miles, James Edward

    Radiographic measurements of femoral varus are used to determine if intervention to correct femoral deformity is required, and to calculate the required correction. The varus angle is defined as the angle between the proximal femoral long axis (PFLA) and an axis tangential to the distal femoral c...

  19. Influence of Heat Treatment on the Bond Coat Cyclic Oxidation Behaviour in an Air-plasma-sprayed Thermal Barrier Coating System

    Institute of Scientific and Technical Information of China (English)

    W.R. Chen; X. Wu; B.R. Marple; P.C. Patnaik

    2004-01-01

    It is generally believed that a thermally grown oxide (TGO) layer of alumina provides enhanced protection to the metallic bond coat in thermal barrier coating (TBC) systems at elevated temperatures. However, in an air-plasma-sprayed (APS) TBC system with Co-32Ni-21Cr-8A1-0.5Y (wt%) bond coat, the TGO layer formed upon thermal exposure in air was predominantly chromia and spinels, which would not effectively protect the bond coat at above 1000℃. In addition,mixed oxides of chromia, spinel and nickel oxide formed heterogeneously between the ceramic coating and CoNiCrAlY bond coat, which would promote crack initiation and lead to premature TBC failure. A heat treatment in a low-pressure condition was applied to the as-sprayed TBC system, with the aim to produce an alumina layer as well as reduce the amount of detrimental oxides. The influence of this low-pressure oxidation treatment (LPOT) on the bond coat cyclic oxidation behaviour of the TBC system was also investigated.

  20. Self-healing atmospheric plasma sprayed Mn1.0Co1.9Fe0.1O4 protective interconnector coatings for solid oxide fuel cells

    Science.gov (United States)

    Grünwald, Nikolas; Sebold, Doris; Sohn, Yoo Jung; Menzler, Norbert Heribert; Vaßen, Robert

    2017-09-01

    Dense coatings on metallic interconnectors are necessary to suppress chromium poisoning of SOFC cathodes. Atmospherically plasma sprayed (APS) Mn1.0Co1.9Fe0.1O4 (MCF) protective layers demonstrated reduced chromium related degradation in laboratory and stack tests. Previous analyses revealed strong microstructural changes comparing the coating's as-sprayed and operated condition. This work concentrates on the layer-densification and crack-healing observed by annealing APS-MCF in air, which simulates the cathode operation conditions. The effect is described by a volume expansion induced by a phase transformation. Reducing conditions during the spray process lead to a deposition of the MCF in a metastable rock salt configuration. Annealing in air activates diffusion processes for a phase transformation to the low temperature stable spinel phase (T pressures, as there are the sample surface, cracks and pore surfaces. Calculations reveal a volume expansion induced by the oxygen uptake which seals the cracks and densifies the coating. The process decelerates when the cracks are closed, as the gas route is blocked and further oxidation continues over solid state diffusion. The self-healing abilities of metastable APS coatings could be interesting for other applications.

  1. Carbide Dissolution/Carbon Loss as a Function of Spray Distance in Unshrouded/Shrouded Plasma Sprayed Cr3C2-NiCr Coatings

    Science.gov (United States)

    Matthews, S.

    2015-02-01

    Thermal spraying of Cr3C2-NiCr composites generates varying degrees of carbide dissolution into the Ni binder. During high-temperature exposure, the carbide dissolution zones precipitate high concentrations of small carbides which develop into finely structured networks. This raises the possibility of producing unique tailored carbide composite structures through the generation of controlled carbide dissolution and appropriate heat treatment. The first step in this process is to produce a supersaturated Ni-Cr-C solid solution from which the carbide phase could be precipitated. In a previous work, a broad range of plasma parameters were trialed to assess their effect on the degree of carbide dissolution at a fixed spray distance of 100 mm. The current two-part work builds on the most promising plasma parameters from those trials. In Part 1 of this two-part article series, the effect of spray distance on the extent of carbide dissolution and carbon loss during high energy plasma spraying was investigated. The effectiveness of solid shield and gas shrouding is contrasted, and the mechanisms by which they influence the degree of decarburization discussed.

  2. Dose-Dependent Effects of CeO2 on Microstructure and Antibacterial Property of Plasma-Sprayed TiO2 Coatings for Orthopedic Application

    Science.gov (United States)

    Zhao, Xiaobing; Liu, Gaopeng; Zheng, Hai; Cao, Huiliang; Liu, Xuanyong

    2015-02-01

    Titanium and its alloys have been used extensively for orthopedic and dental implants. Although these devices have achieved high rates of success, two major complications may be encountered: the lack of osseointegration and the biomaterial-related infection. Accordingly, cerium oxide (CeO2)-doped titanium oxide (TiO2) materials were coated on titanium by an atmospheric plasma spraying (APS) technique. The phase structures, morphologies, and surface chemical states of the obtained coatings were characterized by x-ray diffraction, scanning electron microscopy, and x-ray photoelectron spectroscopy techniques. The in vitro antibacterial and cytocompatibility of the materials were studied with Staphylococcus aureus ( S. aureus, ATCC25923) and osteoblast precursor cell line MC3T3-E1. The results indicated that the addition of CeO2 shifts slightly the diffraction peaks of TiO2 matrix to low angles but does not change its rutile phase structure. In addition, the CeO2/TiO2 composite coatings possess dose-dependent corrosion resistance and antimicrobial properties. And doping of 10 wt.% CeO2 exhibits the highest activity against S. aureus, improved corrosion resistance, and competitive cytocompatibility, which argues a promising option for balancing the osteogenetic and antibacterial properties of titanium implants.

  3. Processing Parameter Effects and Thermal Properties of Y2Si2O7 Nanostructured Environmental Barrier Coatings Synthesized by Solution Precursor Induction Plasma Spraying

    Science.gov (United States)

    Darthout, Émilien; Laduye, Guillaume; Gitzhofer, François

    2016-09-01

    The solution precursor plasma spray process, in which a solution of metal salts is axially injected into an induction thermal plasma, is suitable for deposition of nanostructured environmental barrier coatings. The effects of main processing parameters, namely the solution precursor concentration, spraying distance, reactor pressure, and atomization gas flow rate, have been analyzed using D-optimal design of experiments regarding the deposition rate and coating porosity responses. Among these four parameters, the solution precursor concentration had the greatest influent on the coating structure, followed by the spraying distance and reactor pressure, and finally the atomization gas flow rate with a small contribution. It is pointed out that the species that impact on the substrate are agglomerates of nanoparticles. The equivalent thermal conductivity of selected coatings was computed from experimental temperature evolution curves obtained by laser flash thermal diffusivity analysis, using two methods: a multilayer finite-element model with optimization, and a multilayer thermal diffusion model. The results of the two models agree, with coatings exhibiting low thermal conductivity between 0.7 and 1 W/(m K) at 800 °C.

  4. Suspension Plasma Sprayed Sr2Fe1.4Mo0.6O6- δ Electrodes for Solid Oxide Fuel Cells

    Science.gov (United States)

    Zhang, Shan-Lin; Zhang, Ai-Ping; Li, Cheng-Xin; Yang, Guan-Jun; Li, Chang-Jiu

    2017-02-01

    In this study, suspension plasma spraying (SPS) was applied to deposit double perovskite Sr2Fe1.4Mo0.6O6- δ (SFM) which can be used as both cathode and anode for solid oxide fuel cells. The effects of SFM concentration on the electrode phase composition, microstructure, and catalytic performance were investigated. The electrodes showed a dense structure when it was deposited at a concentration of 0.05 mol/L. The cathode performance was limited by the limited three-phase boundaries and poor gas diffusion. At 750 °C, cathode polarization ( R pc) was 0.19 Ω cm2. When the SFM concentration increased to 0.075 mol/L, the deposits revealed a porous microstructure with well-bonded fine particles. As a result, the Rpc decreased significantly to 0.078 Ω cm2 at 750 °C. However, when the SFM concentration was further increased to 0.1 mol/L, the R pc increased owing to the limited interface bonding between the non-molten particles. As a result, it was found that the SFM suspension concentration should be optimized to achieve a highly active SFM by SPS process. Moreover, when the optimized deposit was employed as an anode and tested in a hydrogen atmosphere, it showed anode polarization resistance (Rpa) of 1.5 Ω cm2 at 750 °C.

  5. Evaporation of Droplets in Plasma Spray-Physical Vapor Deposition Based on Energy Compensation Between Self-Cooling and Plasma Heat Transfer

    Science.gov (United States)

    Liu, Mei-Jun; Zhang, Meng; Zhang, Qiang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2017-08-01

    In the plasma spray-physical vapor deposition process (PS-PVD), there is no obvious heating to the feedstock powders due to the free molecular flow condition of the open plasma jet. However, this is in contrast to recent experiments in which the molten droplets are transformed into vapor atoms in the open plasma jet. In this work, to better understand the heating process of feedstock powders in the open plasma jet of PS-PVD, an evaporation model of molten ZrO2 is established by examining the heat and mass transfer process of molten ZrO2. The results reveal that the heat flux in PS-PVD open plasma jet (about 106 W/m2) is smaller than that in the plasma torch nozzle (about 108 W/m2). However, the flying distance of molten ZrO2 in the open plasma jet is much longer than that in the plasma torch nozzle, so the heating in the open plasma jet cannot be ignored. The results of the evaporation model show that the molten ZrO2 can be partly evaporated by self-cooling, whereas the molten ZrO2 with a diameter heat transfer.

  6. High throughput production of nanocomposite SiO x powders by plasma spray physical vapor deposition for negative electrode of lithium ion batteries

    Directory of Open Access Journals (Sweden)

    Keiichiro Homma

    2014-04-01

    Full Text Available Nanocomposite Si/SiO x powders were produced by plasma spray physical vapor deposition (PS-PVD at a material throughput of 480 g h−1. The powders are fundamentally an aggregate of primary ~20 nm particles, which are composed of a crystalline Si core and SiO x shell structure. This is made possible by complete evaporation of raw SiO powders and subsequent rapid condensation of high temperature SiO x vapors, followed by disproportionation reaction of nucleated SiO x nanoparticles. When CH4 was additionally introduced to the PS-PVD, the volume of the core Si increases while reducing potentially the SiO x shell thickness as a result of the enhanced SiO reduction, although an unfavorable SiC phase emerges when the C/Si molar ratio is greater than 1. As a result of the increased amount of Si active material and reduced source for irreversible capacity, half-cell batteries made of PS-PVD powders with C/Si = 0.25 have exhibited improved initial efficiency and maintenance of capacity as high as 1000 mAh g−1 after 100 cycles at the same time.

  7. Modification of Plasma-sprayed TiO2 Coatings Characteristics via Controlling the In-flight Temperature and Velocity of the Powder Particles

    Science.gov (United States)

    Cizek, Jan; Dlouhy, Ivo; Siska, Filip; Khor, Khiam Aik

    2014-12-01

    The study presents a comprehensive research on the plasma spray fabrication of TiO2 coatings with microstructural properties adjustable via controlling the respective in-flight properties of the feedstock particles. The in-flight properties can be, in return, governed by tuning the plasma system spray parameters. By determining and linking the two interrelationships, a connection between the important coating characteristics (composition, microstructure, surface and mechanical properties) to the plasma system settings was established. It was shown that by changing the values of six parameters representing the flexibility of the plasma system, the temperatures and velocities of the particles within the jet can be altered from 2125 to 2830 K and 137 to 201 m s-1, respectively. The values of the in-flight temperature critically influenced the efficiency of the coating build-up (values ranging from 8 to 84 μm per 1 torch pass) and the content of anatase phase in the fabricated coatings (0-5.8%), while the in-flight velocity of the TiO2 particles was found to be connected to the porosity of the coatings (ranging from 14.4 to 26.2%) and the adhesion strength at the coating-substrate interface (2.6 × difference).

  8. Detection of segmentation cracks in top coat of thermal barrier coatings during plasma spraying by non-contact acoustic emission method.

    Science.gov (United States)

    Ito, Kaita; Kuriki, Hitoshi; Araki, Hiroshi; Kuroda, Seiji; Enoki, Manabu

    2014-06-01

    Numerous cracks can be observed in the top coat of thermal barrier coatings (TBCs) deposited by the atmospheric plasma spraying (APS) method. These cracks can be classified into vertical and horizontal ones and they have opposite impact on the properties of TBCs. Vertical cracks reduce the residual stress in the top coat and provide strain tolerance. On the contrary, horizontal cracks trigger delamination of the top coat. However, monitoring methods of cracks generation during APS are rare even though they are strongly desired. Therefore, an in situ, non-contact and non-destructive evaluation method for this objective was developed in this study with the laser acoustic emission (AE) technique by using laser interferometers as a sensor. More AE events could be detected by introducing an improved noise reduction filter and AE event detection procedures with multiple thresholds. Generation of vertical cracks was successfully separated from horizontal cracks by a newly introduced scanning pattern of a plasma torch. Thus, generation of vertical cracks was detected with certainty by this monitoring method because AE events were detected only during spraying and a positive correlation was observed between the development degree of vertical cracks and the total AE energy in one experiment.

  9. Microstructure studies of air-plasma-spray-deposited CoNiCrAlY coatings before and after thermal cyclic loading for high-temperature application

    Institute of Scientific and Technical Information of China (English)

    Dipak Kumar; KN Pandey; Dipak Kumar Das

    2016-01-01

    In the present study, bond-coats for thermal barrier coatings were deposited via air plasma spraying (APS) techniques onto Inconel 800 and Hastelloy C-276 alloy substrates. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and atomic force microscopy (AFM) were used to investigate the phases and microstructure of the as-sprayed, APS-deposited CoNiCrAlY bond-coatings. The aim of this work was to study the suitability of the bond-coat materials for high temperature applications. Confirmation of nanoscale grains of theγ/γ′-phase was obtained by TEM, high-resolution TEM, and AFM. We concluded that these changes result from the plastic deformation of the bond-coat during the deposition, resulting in CoNiCrAlY bond-coatings with excellent thermal cy-clic resistance suitable for use in high-temperature applications. Cyclic oxidative stability was observed to also depend on the underlying metallic alloy substrate.

  10. Microstructure studies of air-plasma-spray-deposited CoNiCrAlY coatings before and after thermal cyclic loading for high-temperature application

    Science.gov (United States)

    Kumar, Dipak; Pandey, K. N.; Das, Dipak Kumar

    2016-08-01

    In the present study, bond-coats for thermal barrier coatings were deposited via air plasma spraying (APS) techniques onto Inconel 800 and Hastelloy C-276 alloy substrates. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and atomic force microscopy (AFM) were used to investigate the phases and microstructure of the as-sprayed, APS-deposited CoNiCrAlY bond-coatings. The aim of this work was to study the suitability of the bond-coat materials for high temperature applications. Confirmation of nanoscale grains of the γ/γ'-phase was obtained by TEM, high-resolution TEM, and AFM. We concluded that these changes result from the plastic deformation of the bond-coat during the deposition, resulting in CoNiCrAlY bond-coatings with excellent thermal cyclic resistance suitable for use in high-temperature applications. Cyclic oxidative stability was observed to also depend on the underlying metallic alloy substrate.

  11. Insights on the High-Temperature Operational Limits of ZrO2-Y2O3 TBCs Manufactured via Air Plasma Spray

    Science.gov (United States)

    Lima, Rogerio S.; Marple, Basil R.

    2017-02-01

    The effective high-temperature operation limit of a ZrO2-7-8 wt.%Y2O3 (YSZ) thermal barrier coating (TBC) manufactured via air plasma spray (APS) is considered to be 1300 °C. This is related to the metastable tetragonal t'-phase formed during the rapid quenching of the YSZ particles during spraying. The t'-phase transforms into the equilibrium tetragonal and cubic phases at temperatures ≥ 1300 °C, which can lead to the formation of the monoclinic phase of YSZ upon cooling to room temperature. This formation of the monoclinic phase is accompanied by a volume expansion that leads to TBC failure due to extensive micro-cracking. To further investigate this limitation, an APS YSZ TBC was sprayed on a CMSX-4 substrate. By using a thermal (laser) gradient cyclic testing, a temperature gradient was generated across the TBC/substrate system. The YSZ T-front and substrate backside T-back temperature levels were 1500 and 1000 °C, respectively. In cycle conditions (5-min or 1-h hot and 2-min cool), no TBC failure has been observed. This behavior was partially attributed to the unexpected absence of the monoclinic phase of the YSZ in the cycled coatings. Although preliminary, these results are promising regarding increasing the effective high-temperature operational limits of APS YSZ TBCs.

  12. Influence of Isothermal Heat Treatment on Porosity and Crystallite Size in Axial Suspension Plasma Sprayed Thermal Barrier Coatings for Gas Turbine Applications

    Directory of Open Access Journals (Sweden)

    Ashish Ganvir

    2016-12-01

    Full Text Available Axial suspension plasma spraying (ASPS is an advanced thermal spraying technique, which enables the creation of specific microstructures in thermal barrier coatings (TBCs used for gas turbine applications. However, the widely varying dimensional scale of pores, ranging from a few nanometers to a few tenths of micrometers, makes it difficult to experimentally measure and analyze porosity in SPS coatings and correlate it with thermal conductivity or other functional characteristics of the TBCs. In this work, an image analysis technique carried out at two distinct magnifications, i.e., low (500× and high (10,000×, was adopted to analyze the wide range of porosity. Isothermal heat treatment of five different coatings was performed at 1150 °C for 200 h under a controlled atmosphere. Significant microstructural changes, such as inter-columnar spacing widening or coalescence of pores (pore coarsening, closure or densification of pores (sintering and crystallite size growth, were noticed in all the coatings. The noted changes in thermal conductivity of the coatings following isothermal heat treatment are attributable to sintering, crystallite size growth and pore coarsening.

  13. Processing Parameter Effects and Thermal Properties of Y2Si2O7 Nanostructured Environmental Barrier Coatings Synthesized by Solution Precursor Induction Plasma Spraying

    Science.gov (United States)

    Darthout, Émilien; Laduye, Guillaume; Gitzhofer, François

    2016-10-01

    The solution precursor plasma spray process, in which a solution of metal salts is axially injected into an induction thermal plasma, is suitable for deposition of nanostructured environmental barrier coatings. The effects of main processing parameters, namely the solution precursor concentration, spraying distance, reactor pressure, and atomization gas flow rate, have been analyzed using D-optimal design of experiments regarding the deposition rate and coating porosity responses. Among these four parameters, the solution precursor concentration had the greatest influent on the coating structure, followed by the spraying distance and reactor pressure, and finally the atomization gas flow rate with a small contribution. It is pointed out that the species that impact on the substrate are agglomerates of nanoparticles. The equivalent thermal conductivity of selected coatings was computed from experimental temperature evolution curves obtained by laser flash thermal diffusivity analysis, using two methods: a multilayer finite-element model with optimization, and a multilayer thermal diffusion model. The results of the two models agree, with coatings exhibiting low thermal conductivity between 0.7 and 1 W/(m K) at 800 °C.

  14. Influence of Heat Treatment on the Bond Coat Cyclic Oxidation Behaviour in an Air-plasma-sprayed Thermal Barrier Coating System

    Institute of Scientific and Technical Information of China (English)

    W.R.Chen; X.Wu; B.R.Marple; P.C.Patnaik

    2004-01-01

    It is generally believed that a thermally grown oxide (TGO) layer of alumina provides enhanced protection to the metallic bond coat in thermal barrier coating (TBC) systems at elevated temperatures. However, in an air-plasma-sprayed (APS) TBC system with Co-32Ni-21Cr-8A1-0.5Y (wt%) bond coat, the TGO layer formed upon thermal exposure in air was predominantly chromia and spinels, which would not effectively protect the bond coat at above 1000℃. In addition, mixed oxides of chromia, spinel and nickel oxide formed heterogeneously between the ceramic coating and CoNiCrA1Y bond coat, which would promote crack initiation and lead to premature TBC failure. A heat treatment in a low-pressure condition was applied to the as-sprayed TBC system, with the aim to produce an alumina layer as well as reduce the amount of detrimental oxides. The influence of this low-pressure oxidation treatment (LPOT) on the bond coat cyclic oxidation behaviour of the TBC system was also investigated.

  15. Effects of Bond Coating on NiCrBSi-Mo Composite Functional Coating Properties in Plasma Spraying NiCrBSi-Mo/Ni Coating

    Directory of Open Access Journals (Sweden)

    DU Ji-yu

    2017-09-01

    Full Text Available Nickel-based bond coating and composite functional coating were sprayed on leaf blade steel material FV520B successively by using air plasma spraying system. NiCrBSi-Mo powder deposition rate, coating porosity, bonding strength and surface hardness were tested. The results indicate that, for the NiCrBSi-Mo/Ni coating, bond coating with 180-220μm thickness can improve NiCrBSi-Mo powder deposition rate while the surface coating with lower porosity, higher bonding strength and high hardness is prepared; the increase of bond coating thickness can lead to increase of functional coating porosity in the bottom and speed up the process of porosity attenuating in the vertical direction.SEM analysis found that the increase of bond coating thickness results in the droplet deposition morphology change in the bending interface with the functional coating. The defects of bond coating have genetic influence on composite functional coating. Bond tensile test results show that excessive bond coating thickness will cause fracture in the interface between bond coating and functional coating during the stretching process; in different grinding surfaces, Vickers hardness of test blocks with a certain bood coating thickness attenuates slowly in the vertical direction. NiCrBSi-Mo/Ni coating not only maintains high surface hardness, but also increases the coating thickness to repair surface damage.

  16. Suspension Plasma Sprayed Sr2Fe1.4Mo0.6O6-δ Electrodes for Solid Oxide Fuel Cells

    Science.gov (United States)

    Zhang, Shan-Lin; Zhang, Ai-Ping; Li, Cheng-Xin; Yang, Guan-Jun; Li, Chang-Jiu

    2017-01-01

    In this study, suspension plasma spraying (SPS) was applied to deposit double perovskite Sr2Fe1.4Mo0.6O6-δ (SFM) which can be used as both cathode and anode for solid oxide fuel cells. The effects of SFM concentration on the electrode phase composition, microstructure, and catalytic performance were investigated. The electrodes showed a dense structure when it was deposited at a concentration of 0.05 mol/L. The cathode performance was limited by the limited three-phase boundaries and poor gas diffusion. At 750 °C, cathode polarization (R pc) was 0.19 Ω cm2. When the SFM concentration increased to 0.075 mol/L, the deposits revealed a porous microstructure with well-bonded fine particles. As a result, the Rpc decreased significantly to 0.078 Ω cm2 at 750 °C. However, when the SFM concentration was further increased to 0.1 mol/L, the R pc increased owing to the limited interface bonding between the non-molten particles. As a result, it was found that the SFM suspension concentration should be optimized to achieve a highly active SFM by SPS process. Moreover, when the optimized deposit was employed as an anode and tested in a hydrogen atmosphere, it showed anode polarization resistance (Rpa) of 1.5 Ω cm2 at 750 °C.

  17. Porosity, mechanical properties, residual stresses of supersonic plasma-sprayed Ni-based alloy coatings prepared at different powder feed rates

    Science.gov (United States)

    Zhang, X. C.; Xu, B. S.; Wu, Y. X.; Xuan, F. Z.; Tu, S. T.

    2008-04-01

    The aim of this paper was to investigate the effect of powder feed rate (PFR) on the microstructure and mechanical properties of the supersonic plasma-sprayed Ni-Cr-B-Si-C coatings. The microstructure, porosity and mechanical properties of the coatings and the residual stresses at the coating surfaces were experimentally determined. Results showed that the variations of porosity, elastic moduli and micro-hardness of the coatings followed Weibull distribution. From the statistical trend, the porosity of the coating increased with increasing PFR. However, the elastic modulus and the micro-hardness of the coating decreased and reached local minima and then increased with increasing PFR. Elastic modulus could be generally considered to be an increasing function of micro-hardness. The mean value of the elastic modulus of the coating calculated from Weibull plot was almost proportional to the square root of the mean value of the micro-hardness of the coating. Moreover, with increasing PFR, the residual stress at the coating surface, which was mainly governed by the elastic modulus of the coating, decreased to a local minimum and then increased.

  18. Mechanical properties, electrochemical corrosion and in-vitro bioactivity of yttria stabilized zirconia reinforced hydroxyapatite coatings prepared by gas tunnel type plasma spraying.

    Science.gov (United States)

    Yugeswaran, S; Yoganand, C P; Kobayashi, A; Paraskevopoulos, K M; Subramanian, B

    2012-05-01

    Yttria stabilized zirconia reinforced hydroxyapatite coatings were deposited by a gas tunnel type plasma spray torch under optimum spraying conditions. For this purpose, 10, 20 and 30 wt% of yttria stabilized zirconia (YSZ) powders were premixed individually with hydroxyapatite (HA) powder and were used as the feedstocks for the coatings. The effect of YSZ reinforcement on the phase formation and mechanical properties of the coatings such as hardness, adhesive strength and sliding wear rates was examined. The results showed that the reinforcement of YSZ in HA could significantly enhance the hardness and adhesive strength of the coatings. The potentiodynamic polarization and impedance measurements showed that the reinforced coatings exhibited superior corrosion resistance compared to the HA coating in SBF solution. Further the results of the bioactivity test conducted by immersion of coatings in SBF showed that after 10 days of immersion of the obtained coatings with all the above compositions commonly exhibited the onset of bioactive apatite formation except for HA+10%YSZ coating. The cytocompatibility was investigated by culturing the green fluorescent protein (GFP)-labeled marrow stromal cells (MSCs) on the coating surface. The cell culture results revealed that the reinforced coatings have superior cell growth than the pure HA coatings.

  19. Effect of chemical composition on hydrophobicity and zeta potential of plasma sprayed HA/CaO-P2O5 glass coatings.

    Science.gov (United States)

    Ferraz, M P; Monteiro, F J; Serro, A P; Saramago, B; Gibson, I R; Santos, J D

    2001-12-01

    Multilayered plasma sprayed coatings on the surface of Ti-6Al-4V alloys have been prepared, which were composed of an underlayer of HA and a surface layer of a CaO-P2O5 glass-HA composite, with 2 or 4wt% of glass. Contact angle and surface tension variation with time, for both water and a protein solution, were determined by the sessile and pendent drop methods respectively using the ADSA-P software. Wettability studies showed that hydrophobicity of the coatings increase with the glass addition. The work of adhesion of albumin was also altered in a controlled manner by the addition of the CaO-P2O5 glass, being lower on the composite coatings than on HA. Zeta potential (ZP) results showed that composite coatings presented a higher net negative charge than HA coatings and that ZP values were also influenced by the content of the glass. This study demonstrated that the surface properties of those coatings may be modified by the addition of CaO-P2O5 glass.

  20. Component

    Directory of Open Access Journals (Sweden)

    Tibor Tot

    2011-01-01

    Full Text Available A unique case of metaplastic breast carcinoma with an epithelial component showing tumoral necrosis and neuroectodermal stromal component is described. The tumor grew rapidly and measured 9 cm at the time of diagnosis. No lymph node metastases were present. The disease progressed rapidly and the patient died two years after the diagnosis from a hemorrhage caused by brain metastases. The morphology and phenotype of the tumor are described in detail and the differential diagnostic options are discussed.

  1. [Subtrochanteric femoral fractures].

    Science.gov (United States)

    Ulmar, B; Simon, S; Eschler, A; Mittlmeier, T

    2013-12-01

    Subtrochanteric femoral fractures are proximal femoral fractures which are located between the trochanter minor and an area of 3 cm below the minor trochanter on the femoral shaft. About 10-15% of all proximal femoral fractures correspond to this fracture site. Elderly or geriatric patients are generally affected and the injury is often the result of a fall in the home, while high-energy trauma is the cause in a small group of generally younger patients. Clinical evaluation of the affected extremity shows disability of axial weight-bearing and pain during compression and rotation of the hip joint. Basic diagnostics include conventional x-rays of the injured femur in the anterior-posterior and lateral planes. These subtrochanteric femoral fractures are almost always treated surgically due to the inherent high degree of instability. The main goals of surgical intervention are to achieve anatomic fracture reduction and primary full weight-bearing stability of the corresponding leg. Intramedullary interlocking nails are used for primary treatment, while extramedullary implants are often used in revision surgery. Early mobilization and intensive respiratory exercises are necessary to prevent early postoperative complications.

  2. Femoral varus: what's the angle

    DEFF Research Database (Denmark)

    Miles, James Edward; Svalastoga, Eiliv Lars; Eriksen, Thomas

    Agreement and reliability of femoral varus measurements: a comparison of four techniques Three different techniques have been described for measuring femoral varus radiographically in the dog, but how the measurements from these techniques compare is unknown. Further, measurement reliability has ...

  3. 全膝人工关节股骨假体屈曲对疗效的影响:1年随访结果%Effect of femoral component flexion in total knee arthroplasty One-year follow-up results One-year follow-up results

    Institute of Scientific and Technical Information of China (English)

    张洪美; 张志强; 孙钢; 赵铁军; 顾力军; 陈卫衡; 尹天; 刘道兵; 张淳; 谢斌

    2008-01-01

    BACKGROUND:The majority of people do not believe that the femoral component flexion in total knee arthroplasty affect or affect little postoperative function and it is the only that the radiographic films is not satisfactory.So it has not caused people's enollgh attention.But the femoral component flexion affects the results of total knee arthroplasty obviously.OnJECTIVE:To investigate the curative effects of femoral component installed in the position of flexion during the operative procedure of total knee arthroplasty(123 knees)on the follow up results in 78 patients.DESIGN:Grouping contrast observation.SETTlNG:First Department of Bone and Joint,Wangjing Hospital of China Academy of Traditional Cllinese Medicine.PARTlCIPANTS:123 knees(78 patients)were given total knee arthroplasty in the First Department of Bone and Joint,Wangjing Hospital of China Academy of Traditional Chinese Medicine from October 2001 to June 2004.Seventeen(13.8%,15 patients)knees were found with femoral component flexion(FCF),in which there were 5 male cases and 10 female cases,aged from 47 to 81 years old.106(63 patients)knees were found without FCF,in which there were 22 male cases and 41 female cases,aged from 47 to 79 years old.METHODS:Total knee arthroplasties about their HSS rating scores,ranges of motion and flexion contractures werecompared in the two groups before operation and after operation,and the degrees of the FCF angle and the distances of femoral component flexion were measured.MAIN OUTCOME MEASURES:①Femoral Drostllesis flexion measurement;②HSS scores and activity:③femoral prosthesis flexion angle and distance buckling;④adverse events and side effects.RESULTS:Follow up lasted for one year above.①The degrees of flexion of femoral components were from 7°to 19°(average 11.3°)and the distance of flexion was from 2 mm to 4 mm(average 2.6 mln)in those 17 knees of total knee arthroplasty.②Differences in HSS rating scores and range of motion were not statistically

  4. Laparoscopic repair of femoral hernia

    OpenAIRE

    Yang, Xue-Fei; Liu, Jia-Lin

    2016-01-01

    Laparoscopic repair of inguinal hernia is mini-invasive and has confirmed effects. Femoral hernia could be repaired through the laparoscopic procedures for inguinal hernia. These procedures have clear anatomic view in the operation and preoperatively undiagnosed femoral hernia could be confirmed and treated. Lower recurrence ratio was reported in laparoscopic procedures compared with open procedures for repair of femoral hernia. The technical details of laparoscopic repair of femoral hernia, ...

  5. Normal neurodynamic responses of the femoral slump test.

    Science.gov (United States)

    Lai, Weng-Hang; Shih, Yi-Fen; Lin, Pei-Ling; Chen, Wen-Yin; Ma, Hsiao-Li

    2012-04-01

    Femoral slump test is a neurodynamic testing, which could be used to assess the mechanosensitivity of the femoral component of the nervous system. Although Trainor and Pinnington reported the diagnosis accuracy of the femoral slump test, the neurodynamic responses of the femoral slump test have never been studied. The purposes of this study were to evaluate whether maneuvers that changed the nerve tension altered the responses of the femoral slump test and if these responses were influenced by gender and leg dominance; and to identify the correlations between flexibility and measured hip extension angle. Thirty-two asymptomatic subjects (16 males, 16 females) were recruited. The femoral slump test was performed in trunk slump and neutral positions, and cervical extension was used as the structure differential technique. Hip extension angle and visual analog scale (VAS) of thigh pain was measured during the test. Our results showed the decrease of nerve tension significantly increased hip extension ROM (P  0.05). These findings indicated that femoral slump test resulted in normal neurodynamic responses in individuals free of lower extremity problems, and these responses were independent of the influence of muscle flexibility or gender. Future research should emphasize the use of femoral slump test in patient groups such as low back and anterior knee pain.

  6. Karakterizacija WCCo/NiCrBSi prevlake otporne na habanje / Characterization of wear resistant plasma sprayed WCCo/NiCrBSi self-fluxing coatings

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2010-04-01

    Full Text Available U radu su analizirani mikrostruktura, mehaničke i tribološke karakteristike (APS prevlake WCCoNiCrBSi koja se primenjuje za reparaciju cilindara nosne noge helikoptera. Tribološka procena prevlake određena je primenom tribometra blok-na-prstenu. Spregnuti materijalblokovi sa prevlakom ispitani su na okaljenom i poboljšanom čeličnom prstenu. Za ukupno odstojanje od 3000 m bili su konstantna brzina 0,5 m/s i opterećenje 400 N. Prednost primene ove prevlake je u značajnom produženju resursa delova uz smanjenje troškova eksploatacije i održavanja. / In this paper, the microstructural, mechanical and tribological properties of WCCoNiCrBSi thermal spray coatings, applied to repair the cylinders of helicopter nasal feet, were analyzed. The process used for coating deposition on steel substrate was the Atmospheric Plasma Spraying (APS.The plasma spray process is a procedure widely used for applying coatings with increased resistance to wear. The combination of WCCo and NiCrBSi powders produced coatings for the protection of metal parts exposed to wear abrasion, erosion and cavitation to 540°C. The WCCoNiCrBSi 50/50% powder is specially developed for the production of coatings of high cohesion and adhesive strength. The coatings are very dense, hard and smooth. Microstructures present in the layers are tungsten carbides and chromium layers that increase resistance to wear and abrasion. Powder is deposited on the substrate rugged with Al2O3. The substrates were heated at temperatures up to 200°C. Powder deposition was performed with the optimal deposition parameters The microstructure and micro hardness of the coating layer was investigated on the cross section of samples using the Pratt & Whitney standard. Micro hardness was tested using the Vickers scale with a load of 300g. The microstructure of the layers was investigated on an optical microscope (OM with a magnification of 400X. Testing of bond strength between coatings and substrates

  7. Penetration treatment of plasma spray SUS316L stainless steel coatings by molten MnO–SiO{sub 2} oxides

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jin, E-mail: wangjinustb@gmail.com [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Kitakyusyu (Japan); Shinozaki, Nobuya [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Kitakyusyu (Japan); Zeng, Zhensu; Sakoda, Nobuaki [Kurashiki Boring Kiko Co., Ltd., Okayama (Japan); Fukami, Naotaka [Taiko Refractories Co., Ltd., Fukuoka (Japan)

    2015-01-15

    Highlights: • MnO–SiO{sub 2} oxides could penetrate into stainless steel coating with in 5 min. • MnO–SiO{sub 2} oxides infiltrated to interface (300 μm) when treatment extended to 20 min. • Spinel-type MnCr{sub 2}O{sub 4} crystal particles emerged in MnO–SiO{sub 2} oxides after penetration. - Abstract: A study of the penetration treatment of plasma sprayed SUS316L stainless steel coatings by molten MnO–SiO{sub 2} oxides with near-eutectic composition was performed. The penetration treatment was introduced at 1353 K for 5, 20, and 45 min, and the effectiveness of the penetration and the underlying mechanisms of interfacial reactions are discussed on the basis of structural observation (EPMA), high-temperature wetting measurements and further supported by a thermodynamic calculation and analysis. The results indicated that at 1353 K, the MnO–SiO{sub 2} oxides could infiltrate into the stainless steel coating within a depth of approximately 100 μm within 5 min due to the very good wettability of the stainless steel coating by molten MnO–SiO{sub 2} oxides. The oxide could further penetrate to the coating/substrate interface when the treatment was extended to 20 min. During the penetration into the coating, a reaction between the MnO–SiO{sub 2} oxides and adjacent stainless steel particles occurred, which produced MnCr{sub 2}O{sub 4} crystalline particles characterized by a spinel structure. As a result, a variation of the MnO–SiO{sub 2} oxides composition was observed.

  8. Prediction of cyclic delamination lives of plasma-sprayed hydroxyapatite coating on Ti-6Al-4V substrates with considering wear and dissolutions.

    Science.gov (United States)

    Otsuka, Yuichi; Kojima, Daisuke; Mutoh, Yoshiharu

    2016-12-01

    This study aims at developing the prediction model of cyclic delamination lives of plasma-sprayed HAp coating on Ti-6Al-4V substrate by considering wear by interface contacts and dissolution effect by Simulated Body Fluid (SBF). Delamination of HAp coating can lead to loosening of implants stem and final failure in vivo. In the fracture mechanism of interfaces between HAp coating with Ti substrates, only adhesive strength (interracial tensile strength) or fatigue behavior by longitudinal cracking have been observed. Cyclic delamination mechanism by considering various loading modes and corrosion effect has not been revealed yet. The interface delamination rates by cyclic loading were much higher than those by static loading tests. The result clearly demonstrated that the interface demalination behaviors are dominated not by maximum stress, but by stress range. Surface profile measurement and SEM observation also demonstrated damages by interface contact or third body wear at delamination tips of HAp coating only in the cases of compressions. The mechanisms of acceleration on the delaminations are third-body wear or wedge effect by worn particles which increased mean stress level during cyclic loading. Cyclic loading tests under SBF also revealed that cyclic delamination lives were shortened probably due to crevice corrosion at interfaces. Dissolutions at the tips of delaminations were observed by SEM images under tensile loading condition in SBF. Linearly adding the effects of wear and dissolutions into Paris law could successfully predict the delamination lives of HAp coating for various loading ratios in SBF. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  9. Estimation of pretraumatic femoral antetorsion in bilateral femoral shaft fractures

    Energy Technology Data Exchange (ETDEWEB)

    Citak, Musa; Jagodzinski, Michael; Krettek, Christian; Huefner, Tobias [Hannover Medical School, Trauma Department, Hannover (Germany); Citak, Mustafa [BG-University Hospital Bergmannsheil, Department of Surgery, Bochum (Germany); Kendoff, Daniel; O' Loughlin, Padhraig F. [Hospital for Special Surgery, Orthopaedic Department, New York, NY (United States); Tavassol, Frank [Hannover Medical School, Department of Oral and Maxillofacial Surgery, Hannover (Germany)

    2009-12-15

    To describe a system for measurement of the pretraumatic femoral antetorsion angle post-bilateral femoral shaft fracture with the use of new imaging software which allows segmentation and three dimensional (3D) reconstruction of DICOM (digital imaging and communications in medicine) images. This case involved a 20-year-old patient with bilateral femoral shaft fractures. Following initial clinical examination, CT scans of both femurs were performed. Subsequently, the DICOM datasets were uploaded to the new software tool. Following segmentation and 3D reconstruction, pretraumatic femoral antetorsion angles were determined. Femoral antetorsion was described and assessed in two ways by referring to the intersection of the posterior condylar plane and (1) a line drawn between the center of the femoral head and femoral neck, (2) a line drawn between the centers of the femoral head and greater trochanter. Using these definitions, values for femoral antetorsion were found to be, respectively, 20 at the right fracture site and 19 on the left site, and 33 bilaterally. The investigators describe in this current technical report the use of new imaging software which enables the calculation of femoral AV following reduction of virtual fracture fragments which are created from standard DICOM images. We believe that this 3D reconstruction method of measuring the antetorsion angle can be integrated into a regular treatment algorithm and may potentially optimize clinical outcomes. (orig.)

  10. Radiation induced femoral palsy

    Energy Technology Data Exchange (ETDEWEB)

    Aranda, B.; Esnault, S.; Brunet, P. (Hopital de la Salpetriere, Paris (France))

    1982-01-01

    We report four cases of femoral palsy due to compressive fibrosis, after pelvic radiation therapy. Three patients had Hodgkin's disease, and one testicular seminoma. Prominent clinical features include major groin induration and underlying swelling. Unlike what is usually seen in tumoral relapse, little or no pain is associated with these neuropathies. The femoral post-radic palsy develops earlier and faster than brachial plexus palsy of same aetiology. In one case, progressive aggravation led to surgical neurolysis which resulted in dramatic and long lasting improvement. The principal preventive and therapeutic management methods are discussed: since compressive fibrosis is related to the use of isolated and massive electron beam therapy, various associations of cobalt and electron beam therapy are designed to best prevent the side effects of each of these methods. The early treatment of developing fibrosis by D. penicillamine is discussed.

  11. Proximal femoral fractures

    DEFF Research Database (Denmark)

    Palm, Henrik; Teixidor, Jordi

    2015-01-01

    BACKGROUND: In hip fracture surgery, the exact choice of implant often remains somewhat unclear for the individual surgeon, but the growing literature consensus has enabled publication of evidence-based surgical treatment pathways. The aim of this article was to review author pathways and national...... guidelines for hip fracture surgery and discuss a method for future pathway/guideline implementation and evaluation. METHODS: By a PubMed search in March 2015 six studies of surgical treatment pathways covering all types of proximal femoral fractures with publication after 1995 were identified. Also we...... searched the homepages of the national heath authorities and national orthopedic societies in West Europe and found 11 national or regional (in case of no national) guidelines including any type of proximal femoral fracture surgery. RESULTS: Pathway consensus is outspread (internal fixation for un...

  12. Proximal Focal Femoral Deficiency

    Directory of Open Access Journals (Sweden)

    Vishal Kalia, Vibhuti

    2008-01-01

    Full Text Available Proximal focal femoral deficiency (PFFD is a developmental disorder of the proximal segment of thefemur and of acetabulum resulting in shortening of the affected limb and impairment of the function. It isa spectrum of congenital osseous anomalies characterized by a deficiency in the structure of the proximalfemur. The diagnosis is often made by radiological evaluation which includes identification and descriptionof PFFD and evaluation of associated limb anomalies by plain radiographs. Contrast arthrography orMagnetic Resonance Imaging is indicated when radiological features are questionable and to disclose thepresence and location of the femoral head and any cartilagenous anlage. The disorder is more commonlyunilateral and is apparent at birth. However, bilateral involvement is rarely seen. Therapy of the disorder isdirected towards satisfactory ambulation and specific treatment depending on the severity of dysplasia.

  13. Proximal Focal Femoral Deficiency

    OpenAIRE

    Vishal Kalia, Vibhuti

    2008-01-01

    Proximal focal femoral deficiency (PFFD) is a developmental disorder of the proximal segment of thefemur and of acetabulum resulting in shortening of the affected limb and impairment of the function. It isa spectrum of congenital osseous anomalies characterized by a deficiency in the structure of the proximalfemur. The diagnosis is often made by radiological evaluation which includes identification and descriptionof PFFD and evaluation of associated limb anomalies by plain radiographs. Contra...

  14. 等离子喷涂介质层提升臭氧发生器性能的试验研究%Experimental Study on Plasma Sprayed Dielectric Layer to Improve Ozone Performance

    Institute of Scientific and Technical Information of China (English)

    陈波; 杨学昌; 陶顺忠

    2013-01-01

    为了结合陶瓷的性能优势和搪瓷的工艺优势,利用先进的等离子喷涂工艺制备了臭氧发生器介质涂层.对涂层进行了微观结构分析和介电性能测试,并设计制作了管式臭氧发生器样机,研究了不同涂层对臭氧产生性能的影响.研究结果显示等离子喷涂涂层满足臭氧发生器的设计要求,且可以获得更高的相对介电常数εr,其中氧化铝(Al2O3)加氧化钛(TiO2)的双涂层方案具有最佳的臭氧生成性能.等离子喷涂工艺具有很强的灵活性,可替代玻璃和搪瓷成为臭氧发生器新的介质层负载工艺,具有良好的应用前景.%In order to obtain the advantages of both ceramic performance and enamel technique,we prepared dielectric coatings for the ozonizer by the advanced plasma spraying process,and analyzed and tested the microstructure and dielectric properties of the coatings.Moreover,we developed a tube ozonizer prototype on the basis of the plasma sprayed coatings,and studied the performance of different coatings in ozone production.The study results show that the plasma sprayed coatings meet the requirements of the ozonizer with higher dielectric constants,and the double A12O3 +TiO2 coatings have the best performance in ozone formation.It is concluded that plasma spraying,as a flexible process,can be substituted for glass and enamel and becomes the new dielectric layer deposition process for ozone generators,which is quite promising in application prospect.

  15. Properties of the ZrO2MgO/MgZrO3NiCr/NiCr triple-layer thermal barrier coating deposited by the atmospheric plasma spray process

    OpenAIRE

    Mihailo R. Mrdak

    2016-01-01

    This paper presents the results of the examinations of TBC - ZrO2MgO / MgZrO3NiCr / NiCr thermal barrier layers deposited by the plasma spray process at the atmospheric pressure on substrates of Al alloys. In order to obtain the structural and mechanical properties of layers, which will provide a good heat and abrasion protection of the tail elevators of aircraft J-22 when firing '.Lightning' and 'Thunder' rockets, the deposition of three powder types was performed on 0.6 mm thick Al alloy su...

  16. The Characteristic of Plasma Torch Designed for the Very Low-Pressure Plasma Spraying%超低压等离子喷涂喷嘴设计与喷枪特性

    Institute of Scientific and Technical Information of China (English)

    高阳; 杨德明

    2011-01-01

    相比大气等离子喷涂(APS),超低压等离子喷涂(VLPPS)在喷嘴出口处的自由区域对粉末的加热能力较低。目前,大多数超低压等离子喷涂设备采用大功率等离子喷枪,电弧电流高达2500A,以补偿加热能力较低的缺点,然而这样对等离子喷枪及其辅助设备要求较高。根据低压环境下的等离子体特性,设计了内送粉变径阳极等离子喷枪。本研究使用热焓探针系统测量了低压以及超低压状态下等离子体内部压力变化。在真空室压力为1000Pa,电流为500~600A,电压为50V时,制备了SUS316不锈钢涂层。结果表明:在适当的条件下涂层呈现类似结构材料的等轴晶组织。%In contrast with the atmosphere plasma spraying (APS), the very low pressure plasma spraying (VLPPS) exhibited lower heating ability for the feed materials at plasma freoe region exit of nozzle. Most very low pressure plasma spraying at the present usually are adopted a high power plasma gun which operated at great arc currents up to 2500A to remedy a lower heating ability, thus result in a series problems not only for the plasma torch but also for associated facility. According to the characteristic of plasma spray in the low pressure environment we designed a plasma torch with separating anode and nozzle, and the powder injected to the plasma jets is from inside nozzle intake. In this study, the pressures in the plasma gases intake, nozzle intake and out of the plasma torch were measured by enthalpy probe, respectively. For the practice, SUS 316 stainless steel coatings were prepared at plasma currents of 500-600A and arc voltage of 50V and the chamber pressure of 1000 Pa, the results indicated that the coatings with the equiaxed microstructure could deposited in the appropriate conditions.

  17. Corrosion behavior of plasma-sprayed coatings on a Ni-base superalloy in Na2SO4-60 Pct V2O5 environment at 900 °C

    Science.gov (United States)

    Singh, Harpreet; Puri, D.; Prakash, S.

    2005-04-01

    The shrouded plasma spray process was used to deposit NiCrAlY, Ni-20Cr, Ni3Al, and Stellite-6 metallic coatings on a Ni-based superalloy (62Ni-23Cr-1.48Al-0.80Mn-0.37Si-0.10Cu-0.025C-bal Fe). NiCrAlY was used as a bond coat in all cases. Hot corrosion studies were conducted on uncoated as well as plasma-spray-coated superalloy specimens after exposure to molten salt at 900 °C under cyclic conditions. The thermogravimetric technique was used to establish the kinetics of corrosion. X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray analysis (SEM/EDAX) and electron-probe microanalysis techniques were used to analyze the corrosion products. The uncoated superalloy suffered accelerated corrosion in the form of intense spalling of the scale. The NiCrAlY coated specimen showed a minimum weight gain, whereas the Stellite-6 indicated a maximum weight gain among the coatings studied. All the coatings were found to be successful in developing resistance against hot corrosion, which may be attributed to the formation of oxides, and spinels of nickel, aluminum, chromium, or cobalt.

  18. 提高等离子喷涂热障涂层隔热性能的方法%Methods of Increasing Thermal Insulation Property of Plasma-spraying Thermal Barrier Coatings

    Institute of Scientific and Technical Information of China (English)

    杨树森; 陈晓鸽

    2012-01-01

    The theory of thermal conduction of ceramic materials and thermal conductivities of current thermal barrier coatings were reviewed to increase further thermal insulation of plasma sprayed thermal barrier coatings. The methods of increasing thermal insulation of plasma sprayed thermal barrier coatings including seeking for alternative ceramic materials, addition of some dopants, preparing nanostructured coating and double-ceramic-layer coating were proposed. It is indicated that the combination of colouring plus nanostructured and double-ceramic-layer coatings with lower thermal conductivity is an very important research direction in future.%为进一步提高等离子喷涂热障涂层的隔热性能,对陶瓷材料的导热理论及热障涂层的热导率进行了研究.提出了包括寻求新型热障涂层陶瓷材料、添加掺杂剂、制备纳米涂层及双陶瓷层热障涂层等能够改善等离子喷涂涂层隔热性能的方法;并指出,采用等离子喷涂技术制备带颜色的稀土锆酸盐纳米双陶瓷层热障涂层,将会进一步改善热障涂层的隔热性能.

  19. Prevascular femoral hernia and its relation with inferior epigastric vessels: a rare presentation of the femoral hernia sac.

    Science.gov (United States)

    Boshnaq, Mohamed; Phan, Yih Chyn; Akhtar, Mansoor; Hamade, Ayman

    2016-04-18

    A 61-year-old man presented to the emergency department, with a 2-week history of a painful lump on his right groin. A diagnosis of an irreducible right femoral hernia was made. As such, an urgent operation was carried out on the same day, and the patient was found to have a rare prevascular femoral hernia in which the sac was lying over the femoral vessels and split by the inferior epigastric vessels into 2 components resembling 2 trouser limbs. The hernia sac presented in a different and challenging way that necessitated meticulous dissection and full orientation of the anatomy of the femoral triangle. Complete dissection and control of the inferior epigastric vessels, and complete reduction of the sac followed by repair with a prosthetic mesh plug were performed successfully. The patient was discharged home the next day.

  20. Femoral pseudoaneurysms in drug addicts

    DEFF Research Database (Denmark)

    Levi-Mazloum, Niels Donald; Rørdam, Peter; Jensen, L P

    1997-01-01

    OBJECTIVE: To evaluate the outcome of treatment of femoral pseudoaneurysms in drug addicts. METHODS: The records of eight patients undergoing vascular surgery for femoral pseudoaneurysms from substance abuse identified from a vascular database were reviewed. RESULTS: Were good in four out of five...