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Sample records for plasma-sprayed ceramic thermal

  1. Fabrication of samarium strontium aluminate ceramic and deposition of thermal barrier coatings by air plasma spray process

    Directory of Open Access Journals (Sweden)

    Baskaran T

    2018-01-01

    Full Text Available Thermal barrier coatings (TBC with the metallic NiCrAlY bond coat are often used in many aircraft engines to protect superalloy components from high-temperature corrosion thereby to improve the life of gas turbine components. The search for new TBC material has been intensified in recent years due to lack of thermo-physical properties of conventionally used Yttria stabilized Zirconia (YSZ TBCs. Recently, the rare earth containing Samarium Strontium Aluminate (SSA based ceramic was proposed as a new TBC material due to its matching thermo-physical properties with the substrate. The present work focused on the synthesis of SSA ceramics for TBCs application and its coatings development on Ni-based superalloy Inconel 718 substrate by air plasma spray process. The X-ray photoelectron spectroscopy (XPS result confirmed the formation of single phase SSA ceramic after synthesis. The surface morphology of SSA TBCs is mainly composed of melted splats, semi and un-melted particles. The cross-sectional SEM micrographs did not show any spallation at the interface which indicated good mechanical interlocking between the bond coat and ceramic top coat. The Young’s modulus and hardness of SSA TBCs were found to be 80 and 6.1 GPa, respectively. The load-depth curve of SSA TBC showed good elastic recovery about 47 %.

  2. Radio-frequency plasma spraying of ceramics

    International Nuclear Information System (INIS)

    Okada, T.; Hamatani, H.; Yoshida, T.

    1989-01-01

    This study was aimed at developing a novel spraying process using a radio-frequency (rf) plasma. Experiments of Al 2 O 3 and ZrO 2 - 8 wt% Y 2 O 3 spraying showed that the initial powder size was the most important parameter for depositing dense coatings. The optimum powder sizes of Al 2 O 3 and ZrO 2 - 8 wt% Y 2 O 3 were considered to be around 100 and 80 μm, respectively. The use of such large-size powders compared with those used by conventional dc plasma spraying made it possible to deposit adherent ceramics coatings of 150 to 300 μm on as-rolled SS304 substrates. It was also shown that low particle velocity of about 10 m/s, which is peculiar to rf plasma spraying, was sufficient for particle deformation, though it imposed a severe limitation on the substrate position. These experimental results prove that rf plasma spraying is an effective process and a strong candidate to open new fields of spraying applications

  3. Ceramic plasma-sprayed coating of melting crucibles for casting metal fuel slugs

    International Nuclear Information System (INIS)

    Kim, Ki Hwan; Lee, Chong Tak; Lee, Chan Bock; Fielding, R.S.; Kennedy, J.R.

    2013-01-01

    Thermal cycling and melt reaction studies of ceramic coatings plasma-sprayed on Nb substrates were carried out to evaluate the performance of barrier coatings for metallic fuel casting applications. Thermal cycling tests of the ceramic plasma-sprayed coatings to 1450 °C showed that HfN, TiC, ZrC, and Y 2 O 3 coating had good cycling characteristics with few interconnected cracks even after 20 cycles. Interaction studies by 1550 °C melt dipping tests of the plasma-sprayed coatings also indicated that HfN and Y 2 O 3 do not form significant reaction layer between U–20 wt.% Zr melt and the coating layer. Plasma-sprayed Y 2 O 3 coating exhibited the most promising characteristics among HfN, TiC, ZrC, and Y 2 O 3 coating

  4. Nonlinear Stress-Strain Behavior of Plasma Sprayed Ceramic Coatings

    Czech Academy of Sciences Publication Activity Database

    Nohava, Jiří; Kroupa, František

    2005-01-01

    Roč. 50, č. 3 (2005), s. 251-262 ISSN 0001-7043 R&D Projects: GA AV ČR KSK1010104 Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma spraying * ceramic coatings * Young’s modulus * nonlinear behavior * microcracks Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  5. Plasma spraying of bioactive glass-ceramics containing bovine bone

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    Annamária Dobrádi

    2017-06-01

    Full Text Available Natural bone derived glass-ceramics are promising biomaterials for implants. However, due to their price and weak mechanical properties they are preferably applied as coatings on load bearing implants. This paper describes result obtained by plasma spraying of bioactive glass-ceramics containing natural bone onto selected implant materials, such as stainless steel, alumina, and titanium alloy. Adhesion of plasma sprayed coating was tested by computed X-ray tomography and SEM of cross sections. The results showed defect free interface between the coating and substrate, without cracks or gaps. Dissolution rate of the coating in simulated body fluid (SBF was readily controlled by the bone additives (phase composition, as well as microstructure. The SBF treatment of the plasma sprayed coating did not influence the boundary between the coating and substrate.

  6. Bond strength of plasma sprayed ceramic coatings on phosphate steels

    Czech Academy of Sciences Publication Activity Database

    Pokorný, P.; Mastný, L.; Sýkora, V.; Pala, Zdeněk; Brožek, Vlastimil

    2015-01-01

    Roč. 54, č. 2 (2015), s. 411-414 ISSN 0543-5846 R&D Projects: GA ČR(CZ) GAP108/12/1872 Institutional support: RVO:61389021 Keywords : phosphating * plasma spraying * ceramic coatings * corrosion * bond strength Subject RIV: CA - Inorganic Chemistry Impact factor: 0.959, year: 2014

  7. Production of ceramic formed parts by means of plasma spraying

    International Nuclear Information System (INIS)

    Kirner, K.

    1989-01-01

    Open and closed pipes and tubes, nozzles and crucibles, conical parts and other molded articles of ceramic materials such as aluminium oxide, magnesium-aluminium spinel, zirconium oxide, zirconium silicate and special ceramics can be fabricated by spray application to a core which is afterwards removed. Because at the same time these are mainly high temperature materials and high temperature application areas, plasma spraying is preferred. The process and examples of application are described, the advantages and disadvantages are pointed out. (orig.) [de

  8. Functionally Graded Materials using Plasma Spray with Nano Structured Ceramic

    International Nuclear Information System (INIS)

    Sioh, E L; Tok, A I Y

    2013-01-01

    In this paper, nano structured FGM was fabricated using DC plasma spray technique. Nano structured and micro structured powder were used as the feeding powder with steel substrate. The spray parameters was optimized and characterisation of nano-ceramic FGM and micro-ceramic FGM were done using bending test and micro-hardness test. Experimental results have shown that the nano-structured FGM exhibit 20% improvement flexure strength and 10% in hardness. A comparison was made between sintered micro ceramic tile and nano ceramic FGM using simple drop test method.

  9. Antibacterial characteristics of thermal plasma spray system.

    Science.gov (United States)

    Goudarzi, M; Saviz, Sh; Ghoranneviss, M; Salar Elahi, A

    2018-03-15

    The objective of this study is to investigate antibacterial characteristics of a thermal plasma spray system. For this purpose, copper powder was coated on a handmade atmospheric plasma spraying system made by the stainless steel 316 substrate, which is preheated at different temperatures before spraying. A number of deposition characteristics such as antibacterial characteristics, adhesion strength and hardness of coating, was investigated. All of the spray parameters are fixed except the substrate temperature. The chemical composition was analyzed by X-ray diffraction (XRD). A scanning electron microscopy (SEM) and back scattering electron microscopy (BSE) were used to show the coating microstructure, its thickness and also the powder micrograph. The energy dispersive X-ray spectroscopy (EDX) was used to analyze the coating particles. Hardness of the deposition was examined by Vickers tester (HV0.1). Its adhesion strength was declared by cross cut tester (TQC). In addition, the percentage of bactericidal coating was evidenced with Staphylococcus aurous and Escherichia coli bacteria. Study results show that as the substrates temperature increases, the number of splats in the shape of pancake increases, the greatness and percentage of the deposition porosity both decrease. The increment of the substrate temperature leads to more oxidation and makes thicker dendrites on the splat. The enhancement of the substrate temperature also enlarges thickness and efficiency of coating. The interesting results are that antibacterial properties of coatings against the Escherichia coli are more than Staphylococcus aurous bacteria. However the bactericidal percentage of the coatings against Staphylococcus aurous and Escherichia coli bacteria roughly does not change with increasing the substrate temperature. Furthermore, by increment of the substrate temperature, coatings with both high adhesion and hardness are obtained. Accordingly, the temperature of substrate can be an

  10. 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.

  11. Finite element analysis of residual stress in plasma-sprayed ceramic

    International Nuclear Information System (INIS)

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

    1985-01-01

    Residual stress in a ZrO 2 -Y 2 O 3 ceramic coating resulting from the plasma spraying operation is calculated. The calculations were done using the finite element method. Both thermal and mechanical analysis were performed. The resulting residual stress field was compared to the measurements obtained by Hendricks and McDonald. Reasonable agreement between the predicted and measured moment occurred. However, the resulting stress field is not in pure bending

  12. 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.

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

    Czech Academy of Sciences Publication Activity Database

    Mušálek, Radek; Medřický, Jan; Tesař, T.; Kotlan, Jiří; Pala, Zdeněk; Lukáč, František; Chráska, Tomáš; Curry, N.

    2017-01-01

    Roč. 26, 1-2 (2017), s. 37-46 ISSN 1059-9630. [ISTC 2016: International Thermal Spray Conference. Shanghai, 10.05.2016-12.05.2016] R&D Projects: GA ČR GA15-12145S Institutional support: RVO:61389021 Keywords : alumina * ceramics * dense * hybrid plasma torch * suspension plasma spraying * water-stabilized plasma * yttria-stabilized zirconia (YSZ) Subject RIV: JK - Corrosion ; Surface Treatment of Materials OBOR OECD: Coating and films Impact factor: 1.488, year: 2016 http://link.springer.com/article/10.1007/s11666-016-0493-6

  14. High quality ceramic coatings sprayed by high efficiency hypersonic plasma spraying gun

    International Nuclear Information System (INIS)

    Zhu Sheng; Xu Binshi; Yao JiuKun

    2005-01-01

    This paper introduced the structure of the high efficiency hypersonic plasma spraying gun and the effects of hypersonic plasma jet on the sprayed particles. The optimised spraying process parameters for several ceramic powders such as Al 2 O 3 , Cr 2 O 3 , ZrO 2 , Cr 3 C 2 and Co-WC were listed. The properties and microstructure of the sprayed ceramic coatings were investigated. Nano Al 2 O 3 -TiO 2 ceramic coating sprayed by using the high efficiency hypersonic plasma spraying was also studied. Compared with the conventional air plasma spraying, high efficiency hypersonic plasma spraying improves greatly the ceramic coatings quality but at low cost. (orig.)

  15. DEVELOPMENT OF COMPLEX EQUIPMENT FOR PLASMA SPRAY CERAMIC COATINGS

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    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.

  16. Anisotropic Thermal Diffusivities of Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Akoshima, Megumi; Takahashi, Satoru

    2017-09-01

    Thermal barrier coatings (TBCs) are used to shield the blades of gas turbines from heat and wear. There is a pressing need to evaluate the thermal conductivity of TBCs in the thermal design of advanced gas turbines with high energy efficiency. These TBCs consist of a ceramic-based top coat and a bond coat on a superalloy substrate. Usually, the focus is on the thermal conductivity in the thickness direction of the TBC because heat tends to diffuse from the surface of the top coat to the substrate. However, the in-plane thermal conductivity is also important in the thermal design of gas turbines because the temperature distribution within the turbine cannot be ignored. Accordingly, a method is developed in this study for measuring the in-plane thermal diffusivity of the top coat. Yttria-stabilized zirconia top coats are prepared by thermal spraying under different conditions. The in-plane and cross-plane thermal diffusivities of the top coats are measured by the flash method to investigate the anisotropy of thermal conduction in a TBC. It is found that the in-plane thermal diffusivity is higher than the cross-plane one for each top coat and that the top coats have significantly anisotropic thermal diffusivity. The cross-sectional and in-plane microstructures of the top coats are observed, from which their porosities are evaluated. The thermal diffusivity and its anisotropy are discussed in detail in relation to microstructure and porosity.

  17. Wet Slurry Abrasion Tests of Ceramic Coatings Deposited by Water-Stabilized Plasma Spraying

    Czech Academy of Sciences Publication Activity Database

    Nohava, Jiří

    2003-01-01

    Roč. 48, č. 2 (2003), s. 203-214 ISSN 0001-7043 R&D Projects: GA ČR GA106/01/0094 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma spraying, wear resistence, ceramic coating Subject RIV: BL - Plasma and Gas Discharge Physics

  18. Measurement of residual stress in plasma-sprayed metallic, ceramic and composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Kesler, O.; Suresh, S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Matejicek, J.; Sampath, S. [State Univ. of New York, Stony Brook, NY (United States). Inst. for Mathematical Sciences; Gnaeupel-Herold, T.; Brand, P.C.; Prask, H.J. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

    1998-12-15

    Residual stresses in plasma-sprayed coatings were studied by three experimental techniques: curvature measurements, neutron diffraction and X-ray diffraction. Two distinct material classes were investigated: (1) single-material coatings (molybdenum) and (2) bi-material composites (nickel+alumina and NiCrAlY+yttria-stabilized zirconia), with and without graded layers. This paper deals with the effects of coating thickness and material properties on the evolution of residual stresses as a function of composition and thickness in both homogeneous and graded coatings. Mathematical analysis of the results allowed in some cases the separation of the quenching stress and thermal stress contributions to the final residual stress, as well as the determination of the through-thickness stress profile from measurements of different thickness specimens. In the ceramic-metal composites, it was found that the quenching stress plays a dominant role in the metallic phase, whereas the stress in the ceramic phase is mostly dominated by thermal mismatch. The respective thermal expansion coefficients and mechanical properties are the most important factors determining the stress sign and magnitude. The three residual stress measurement methods employed here were found to be complementary, in that each can provide unique information about the stress state. The most noteworthy outcomes are the determination of the through-thickness stress profile in graded coatings with high spatial resolution (curvature method) and determination of stress in each phase of a composite separately (neutron diffraction). (orig.) 25 refs.

  19. Thermal plasma spraying for SOFCs: Applications, potential advantages, and challenges

    Energy Technology Data Exchange (ETDEWEB)

    Hui, Rob; Wang, Zhenwei; Jankovic, Jasna; Yick, Sing; Maric, Radenka; Ghosh, Dave [National Research Council Institute for Fuel Cell Innovation, 4250 Wesbrook Mall, Vancouver, BC V6T 1W5 (Canada); Kesler, Olivera [National Research Council Institute for Fuel Cell Innovation, 4250 Wesbrook Mall, Vancouver, BC V6T 1W5 (Canada); Department of Mechanical Engineering, University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, BC V6T 1Z4 (Canada); Rose, Lars [National Research Council Institute for Fuel Cell Innovation, 4250 Wesbrook Mall, Vancouver, BC V6T 1W5 (Canada); Department of Materials Engineering, University of British Columbia, 309-6350 Stores Road, Vancouver, BC V6T 1Z4 (Canada)

    2007-07-10

    In this article, the applications, potential advantages, and challenges of thermal plasma spray (PS) processing for nanopowder production and cell fabrication of solid oxide fuel cells (SOFCs) are reviewed. PS processing creates sufficiently high temperatures to melt all materials fed into the plasma. The heated material can either be quenched into oxide powders or deposited as coatings. This technique has been applied to directly deposit functional layers as well as nanopowder for SOFCs application. In particularly, low melting point and highly active electrodes can be directly fabricated on zirconia-based electrolytes. This is a simple processing technique that does not require the use of organic solvents, offering the opportunity for flexible adjustment of process parameters, and significant time saving in production of the cell and cost reduction compared with tape casting, screen printing and sintering processing steps. Most importantly, PS processing shows strong potential to enable the deposition of metal-supported SOFCs through the integrated fabrication of membrane-electrode assemblies (MEA) on porous metallic substrates with consecutive deposition steps. On the other hand, the application of PS processing to produce SOFCs faces some challenges, such as insufficient porosity of the electrodes, the difficulty of obtaining a thin (<10 {mu}m) and dense electrolyte layer. Fed with H{sub 2} as the fuel gas and oxygen as the oxidant gas, the plasma sprayed cell reached high power densities of 770 mW cm{sup -2} at 900 C and 430 mW cm{sup -2} at 800 C at a cell voltage of 0.7 V. (author)

  20. Plasma transferred arc surface modification of atmospheric plasma sprayed ceramic coatings

    Energy Technology Data Exchange (ETDEWEB)

    Ulutan, Mustafa; Kilicay, Koray; Kaya, Esad; Bayar, Ismail [Dept. of Mechanical Engineering, Eskisehir Osmangazi University, Eskisehir (Turkmenistan)

    2016-08-15

    In this study, a 90MnCrV8 steel surface was coated with aluminum oxide and chromium oxide powders through the Atmospheric plasma spray (APS) and Plasma transferred arc (PTA) methods. The effects of PTA surface melting on the microstructure, hardness, and wear behavior were investigated. The microstructures of plasma-sprayed and modified layers were characterized by Optical microscopy (OM), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS). The dry-sliding wear properties of the samples were determined through the ball-on-disk wear test method. Voids, cracks, and nonhomogeneous regions were observed in the microstructure of the APS ceramic-coated surface. These microstructure defects were eliminated by the PTA welding process. The microhardness of the samples was increased. Significant reductions in wear rate were observed after the PTA surface modification. The wear resistance of ceramic coatings increased 7 to 12 times compared to that of the substrate material.

  1. Composite Coatings of Alumina-based Ceramics and Stainless Steel Manufactured by Plasma Spraying

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Ageorges, H.; Neufuss, Karel; Zahálka, F.

    2009-01-01

    Roč. 15, č. 2 (2009), s. 108-114 ISSN 1392-1320 R&D Projects: GA AV ČR 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : Cermet * plasma spraying * microstructure * elastic modulus * wear resistance Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.299, year: 2009 http://internet.ktu.lt/en/science/journals/medz/medz0-97.html#Composite_Coatings_

  2. High temperature tribological properties of plasma-sprayed metallic coatings containing ceramic particles

    International Nuclear Information System (INIS)

    Dallaire, S.; Legoux, J.G.

    1995-01-01

    For sealing a moving metal component with a dense silica-based ceramic pre-heated at 800 C, coatings with a low coefficient of friction and moderate wear loss are required. As reported previously, plasma-sprayed coatings containing solid lubricants could reduce sliding wear in high-temperature applications. Plasma-sprayed metal-based coatings containing ceramic particles have been considered for high temperature sealing. Selected metal powders (NiCoCrAlY, CuNi, CuNiIn, Ag, Cu) and ceramic particles (boron nitride, Zeta-B ceramic) were agglomerated to form suitable spray powders. Plasma-sprayed composite coatings and reference materials were tested in a modified pin-on-disc apparatus in which the stationary disc consisted of a dense silica-based ceramic piece initially heated at 800 C and allowed to cool down during tests. The influence of single exposure and repeated contacts with a dense silica-based ceramic material pre-heated to 800 C on the coefficient of friction, wear loss and damage to the ceramic piece was evaluated. Being submitted to a single exposure at high temperature, coatings containing malleable metals such as indium, silver and copper performed well. The outstanding tribological characteristics of the copper-Zeta-B ceramic coating was attributed to the formation of a glazed layer on the surface of this coating which lasted over exposures to high temperature. This glazed layer, composed of fine oxidation products, provided a smooth and polished surface and helped maintaining the coefficient of friction low

  3. Development and evaluation of suspension plasma sprayed yttria stabilized zirconia coatings as thermal barriers

    Science.gov (United States)

    van Every, Kent J.

    The insulating effects from thermal barrier coatings (TBCs) in gas turbine engines allow for increased operational efficiencies and longer service lifetimes. Consequently, improving TBCs can lead to enhanced gas turbine engine performance. This study was conducted to investigate if yttria-stabilized zirconia (YSZ) coatings, the standard industrial choice for TBCs, produced from nano-sized powder could provide better thermal insulation than current commericial YSZ coatings generated using micron-sized powders. The coatings for this research were made via the recently developed suspension plasma spraying (SPS) process. With SPS, powders are suspended in a solvent containing dispersing agents; the suspension is then injected directly into a plasma flow that evaporates the solvent and melts the powder while transporting it to the substrate. Although related to the industrial TBC production method of air plasma spraying (APS), SPS has two important differences---the ability to spray sub-micron diameter ceramic particles, and the ability to alloy the particles with chemicals dissolved in the solvent. These aspects of SPS were employed to generate a series of coatings from suspensions containing ˜100 nm diameter YSZ powder particles, some of which were alloyed with neodymium and ytterbium ions from the solvent. The SPS coatings contained columnar structures not observed in APS TBCs; thus, a theory was developed to explain the formation of these features. The thermal conductivity of the coatings was tested to evaluate the effects of these unique microstructures and the effects of the alloying process. The results for samples in the as-sprayed and heat-treated conditions were compared to conventional YSZ TBCs. This comparison showed that, relative to APS YSZ coatings, the unalloyed SPS samples typically exhibited higher as-sprayed and lower heat-treated thermal conductivities. All thermal conductivity values for the alloyed samples were lower than conventional YSZ TBCs

  4. Ceramic Materials Selection of Fuel Crucibles based on Plasma Spray Coating for SFR

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hoon; Kim, Jonghwan; Kim, Hyungtae; Ko, Youngmo; Woo, Yoonmyung; Oh, Seokjin; Kim, Kihwan; Lee, Chanbock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-07-01

    The plasma-sprayed coating can provide the crucible with a denser, more friable coating layer, compared with the more friable coating layer formed by slurry-coating, which was used to prevent the interaction between melt and crucibles. Plasma-sprayed coatings are consolidated by mechanical interlocking of the molten particles impacting on the substrate and are dense by the heat applied by the plasma. The increased coating density is advantageous because it should not require frequent re coating and U-Zr melt penetration through the protective layer is more difficult in a dense coating than in a porous coating. In this study, we used Vacuum Plasma Spray method to investigate permanent coatings for re-usable crucibles for melting and casting of metallic fuel onto niobium substrates. Niobium was selected as a substrate because of its refractory nature and the coefficient of thermal expansion is similar to that of many of the candidate materials. After the HfC, ZrC, TiC, TaC, Y{sub 2}O{sub 3}, and 8% YSZ coatings were applied the resulting microstructure and chemical compositions was characterized to find the optimum process conditions for coating. Thermal plasma-sprayed coatings of refractory materials can be applied to develop a re-usable crucible coating for metallic fuel, such as the U-Zr alloy proposed for sodium cooled fast reactors.

  5. Influence of Microstructure on Thermal Properties of Axial Suspension Plasma-Sprayed YSZ Thermal Barrier Coatings

    Czech Academy of Sciences Publication Activity Database

    Ganvir, A.; Curry, N.; Markocsan, N.; Nylen, P.; Joshi, S.; Vilémová, Monika; Pala, Zdeněk

    2016-01-01

    Roč. 25, 1-2 (2016), s. 202-212 ISSN 1059-9630. [ITSC 2015: International Thermal Spray Conference and Exposition. Long Beach, California, 11.05.2015-14.05.2015] Institutional support: RVO:61389021 Keywords : axial injection * column ar microstructure * porosity * suspension plasma spraying * thermal conductivity * thermal diffusivity Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.488, year: 2016 http://link.springer.com/article/10.1007%2Fs11666-015-0355-7

  6. Structure and properties of plasma sprayed BaTiO3 coatings after thermal posttreatment

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Sedláček, J.; Pala, Zdeněk

    2015-01-01

    Roč. 41, č. 6 (2015), s. 7453-7460 ISSN 0272-8842 Institutional support: RVO:61389021 Keywords : Electrical properties * BaTiO3 * Plasma spraying * Annealing * Microstructure Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.758, year: 2015 http://dx.doi.org/10.1016/j.ceramint.2015.02.065

  7. Optimized functionally graded La2Zr2O7/8YSZ thermal barrier coatings fabricated by suspension plasma spraying

    International Nuclear Information System (INIS)

    Wang, Chaohui; Wang, You; Fan, Shan; You, Yuan; Wang, Liang; Yang, Changlong; Sun, Xiaoguang; Li, Xuewei

    2015-01-01

    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 2 Zr 2 O 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 2 Zr 2 O 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. INTERACTION STUDIES OF CERAMIC VACUUM PLASMA SPRAYING FOR THE MELTING CRUCIBLE MATERIALS

    Directory of Open Access Journals (Sweden)

    JONG HWAN KIM

    2013-10-01

    Full Text Available Candidate coating materials for re-usable metallic nuclear fuel crucibles, TaC, TiC, ZrC, ZrO2, and Y2O3, were plasma-sprayed onto a niobium substrate. The microstructure of the plasma-sprayed coatings and thermal cycling behavior were characterized, and U-Zr melt interaction studies were carried out. The TaC and Y2O3 coating layers had a uniform thickness, and high density with only a few small closed pores showing good consolidation, while the ZrC, TiC, and ZrO2 coatings were not well consolidated with a considerable amount of porosity. Thermal cycling tests showed that the adhesion of the TiC, ZrC, and ZrO2 coating layers with niobium was relatively weak compared to the TaC and Y2O3 coatings. The TaC and Y2O3 coatings had better cycling characteristics with no interconnected cracks. In the interaction studies, ZrC and ZrO2 coated rods showed significant degradations after exposure to U-10 wt.% Zr melt at 1600°C for 15 min., but TaC, TiC, and Y2O3 coatings showed good compatibility with U-Zr melt.

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

    OpenAIRE

    D. Thirumalaikumarasamy; K. Shanmugam; V. Balasubramanian

    2014-01-01

    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 w...

  14. An analytical methodology to predict the coating characteristics of plasma-sprayed ceramic powders

    International Nuclear Information System (INIS)

    Varacalle, D.J. Jr.

    1990-01-01

    Experimental and analytical studies have been conducted at the Idaho National Engineering Laboratory (INEL) to investigate gas, particle, and coating dynamics in the plasma spray process. Nine experiments were conducted using a Taguchi statistical parametric approach. The thermal plasma produced by the commercial plasma spray torch and the related plasma/particle interaction were then numerically modeled from the cathode tip to varied standoff distances in the free plume for the nine experiments, which ranged in power from 28 to 43 kW. The flow and temperature fields in the plasma were solved using the governing conservation equations with suitable boundary conditions. This information was then used as boundary conditions to solve the plasma/particle interaction problem for the nine experiments. The particle dynamics (10- to 75-μm particles) for a yttria-stabilized zirconia powder were then simulated by computer. Particle morphology is discussed with respect to the changes in the process parameters. The predicted temperature and velocity of the zirconia particles were then used as initial conditions to a coating dynamics code. The code predicts the thickness and porosity of the zirconia coatings for the specific process parameters. The predicted coating characteristics exhibit reasonable correlation with the actual characteristics obtained from the Taguchi experimental studies. 12 refs., 7 figs., 6 tabs

  15. 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 (deposited and multilayer 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

  16. 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

    2018-01-01

    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.

  17. Mueller matrix polarimetry on plasma sprayed thermal barrier coatings for porosity measurement.

    Science.gov (United States)

    Luo, David A; Barraza, Enrique T; Kudenov, Michael W

    2017-12-10

    Yttria-stabilized zirconia (YSZ) is the most widely used material for thermal plasma sprayed thermal barrier coatings (TBCs) used to protect gas turbine engine parts in demanding operation environments. The superior material properties of YSZ coatings are related to their internal porosity level. By quantifying the porosity level, tighter control on the spraying process can be achieved to produce reliable coatings. Currently, destructive measurement methods are widely used to measure the porosity level. In this paper, we describe a novel nondestructive approach that is applicable to classify the porosity level of plasma sprayed YSZ TBCs via Mueller matrix polarimetry. A rotating retarder Mueller matrix polarimeter was used to measure the polarization properties of the plasma sprayed YSZ coatings with different porosity levels. From these measurements, it was determined that a sample's measured depolarization ratio is dependent on the sample's surface roughness and porosity level. To this end, we correlate the depolarization ratio with the samples' surface roughness, as measured by a contact profilometer, as well as the total porosity level, in percentage measured using a micrograph and stereological analysis. With the use of this technique, a full-field and rapid measurement of porosity level can be achieved.

  18. 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.

  19. Erosion resistance and adhesion of composite metal/ceramic coatings produced by plasma spraying

    OpenAIRE

    Ramm , D.; Hutchings , I.; Clyne , T.

    1993-01-01

    Ceramic coatings can exhibit greater erosion resistance than most metallic coatings. Such coatings are conveniently produced by thermal spraying. Unfortunately, thermally sprayed ceramic coatings often exhibit poor adhesion, partly as a consequence of the development of residual stresses during spraying and subsequent cooling. Composite coatings have been studied using aluminium/alumina deposits on steel substrates. The incorporation of ceramics within a ductile matrix has potential for sharp...

  20. Superhydrophobic ceramic coating: Fabrication by solution precursor plasma spray and investigation of wetting behavior.

    Science.gov (United States)

    Xu, Pengyun; Coyle, Thomas W; Pershin, Larry; Mostaghimi, Javad

    2018-03-16

    Superhydrophobic surfaces are often created by fabricating suitable surface structures from low-surface-energy organic materials using processes that are not suitable for large-scale fabrication. Rare earth oxides (REO) exhibit hydrophobic behavior that is unusual among oxides. Solution precursor plasma spray (SPPS) deposition is a rapid, one-step process that can produce ceramic coatings with fine scale columnar structures. Manipulation of the structure of REO coatings through variation in deposition conditions may allow the wetting behavior to be controlled. Yb 2 O 3 coatings were fabricated via SPPS. Coating structure was investigated by scanning electron microscopy, digital optical microscopy, and x-ray diffraction. The static water contact angle and roll-off angle were measured, and the dynamic impact of water droplets on the coating surface recorded. Superhydrophobic behavior was observed; the best coating exhibited a water contact angle of ∼163°, a roll-off angle of ∼6°, and complete droplet rebound behavior. All coatings were crystalline Yb 2 O 3 , with a nano-scale roughness superimposed on a micron-scale columnar structure. The wetting behaviors of coatings deposited at different standoff distances were correlated with the coating microstructures and surface topographies. The self-cleaning, water flushing and water jetting tests were conducted and further demonstrated the excellent and durable hydrophobicity of the coatings. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. 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.

  2. Thermal fatigue behavior of thermal barrier coatings by air plasma spray

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Han Sang; Kim, Eui Hyun [Korea Electric Power Research Institute, Daejeon (Korea, Republic of); Lee, Jung Hyuk [Korea Plant Service and Engineering Co. Ltd., Incheon (Korea, Republic of)

    2008-06-15

    Effects of top coat morphology and thickness on thermal fatigue behavior of Thermal Barrier Coatings (TBC) were investigated in this study. Thermal fatigue tests were conducted on three coating specimens with different top coat morphology and thickness, and then the test data were compared via microstructures, cycles to failure, and fracture surfaces. In the air plasma spray specimens (APS1, APS2), top coat were 200 and 300 {mu}m respectively. The thickness of top coat was about 700 {mu}m in the Perpendicular Cracked Specimen (PCS). Under thermal fatigue condition at 1,100 .deg. C, the cycles to top coat failure of APS1, APS2, and PCS were 350, 560 and 480 cycles, respectively. The cracks were initiated at the interface of top coat and Thermally Grown Oxide (TGO) and propagated into TGO or top coat as the number of thermal fatigue cycles increased. For the PCS specimen, additive cracks were initiated and propagated at the starting points of perpendicular cracks in the top coat. Also, the thickness of TGO and the decrease of aluminium concentration in bond coat do not affect the cycles to failure.

  3. Improving dielectric properties of plasma sprayed calcium titanate (CaTiO3) coatings by thermal annealing

    Czech Academy of Sciences Publication Activity Database

    Kotlan, Jiří; Ctibor, Pavel; Pala, Zdeněk; Homola, P.; Nehasil, V.

    2014-01-01

    Roč. 40, č. 8 (2014), s. 13049-13055 ISSN 0272-8842 Institutional support: RVO:61389021 Keywords : X-raymethods * Dielectricproperties * Perovskites * Plasma spraying Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.605, year: 2014 http://www.sciencedirect.com/science/article/pii/S027288421400724X

  4. Failure Analysis of Multilayered Suspension Plasma-Sprayed Thermal Barrier Coatings for Gas Turbine Applications

    Science.gov (United States)

    Gupta, M.; Markocsan, N.; Rocchio-Heller, R.; Liu, J.; Li, X.-H.; Östergren, L.

    2018-02-01

    Improvement in the performance of thermal barrier coatings (TBCs) is one of the key objectives for further development of gas turbine applications. The material most commonly used as TBC topcoat is yttria-stabilized zirconia (YSZ). However, the usage of YSZ is limited by the operating temperature range which in turn restricts the engine efficiency. Materials such as pyrochlores, perovskites, rare earth garnets are suitable candidates which could replace YSZ as they exhibit lower thermal conductivity and higher phase stability at elevated temperatures. The objective of this work was to investigate different multilayered TBCs consisting of advanced topcoat materials fabricated by suspension plasma spraying (SPS). The investigated topcoat materials were YSZ, dysprosia-stabilized zirconia, gadolinium zirconate, and ceria-yttria-stabilized zirconia. All topcoats were deposited by TriplexPro-210TM plasma spray gun and radial injection of suspension. Lifetime of these samples was examined by thermal cyclic fatigue and thermal shock testing. Microstructure analysis of as-sprayed and failed specimens was performed with scanning electron microscope. The failure mechanisms in each case have been discussed in this article. The results show that SPS could be a promising route to produce multilayered TBCs for high-temperature applications.

  5. 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.

  6. Erosion resistance and adhesion of composite metal/ceramic coatings produced by plasma spraying

    International Nuclear Information System (INIS)

    Ramm, D.A.J.; Hutchings, I.M.; Clyne, T.W.

    1993-01-01

    Ceramic coatings can exhibit greater erosion resistance than most metallic coatings. Such coatings are conveniently produced by thermal spraying. Unfortunately, thermally sprayed ceramic coatings often exhibit poor adhesion, partly as a consequence of the development of residual stresses during spraying and subsequent cooling. Composite coatings have been studied using aluminium/alumina deposits on steel substrates. The incorporation of ceramics within a ductile matrix has potential for sharply reducing the erosive wear at high erodent impact angles, whilst retaining the good erosion resistance of ceramics at low angles. It is shown that the proportion of metal and ceramic at the free surface can be specified so as to optimise the erosion resistance. Experiments have also been carried out on the resistance of the coatings to debonding during four-point bending of the coated substrate. Progress is being made towards the tailoring of composition profiles in graded coatings so as to optimise the combination of erosion resistance and adhesion. (orig.)

  7. 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.

  8. Plasma-sprayed CaTiSiO5 ceramic coating on Ti-6Al-4V with excellent bonding strength, stability and cellular bioactivity

    Science.gov (United States)

    Wu, Chengtie; Ramaswamy, Yogambha; Liu, Xuanyong; Wang, Guocheng; Zreiqat, Hala

    2008-01-01

    Novel Ca-Si-Ti-based sphene (CaTiSiO5) ceramics possess excellent chemical stability and cytocompatibility. The aim of this study was to prepare sphene coating on titanium alloy (Ti-6Al-4V) for orthopaedic applications using the plasma spray method. The phase composition, surface and interface microstructure, coating thickness, surface roughness and bonding strength of the plasma-sprayed sphene coating were analysed using X-ray diffraction, scanning electron microscopy, atomic force microscopy and the standard mechanical testing of the American Society for Testing and Materials, respectively. The results indicated that sphene coating was obtained with a uniform and dense microstructure at the interface of the Ti-6Al-4V surface and the thickness and surface roughness of the coating were approximately 150 and 10 μm, respectively. Plasma-sprayed sphene coating on Ti-6Al-4V possessed a significantly improved bonding strength and chemical stability compared with plasma-sprayed hydroxyapatite (HAp) coating. Plasma-sprayed sphene coating supported human osteoblast-like cell (HOB) attachment and significantly enhanced HOB proliferation and differentiation compared with plasma-sprayed HAp coating and uncoated Ti-6Al-4V. Taken together, plasma-sprayed sphene coating on Ti-6Al-4V possessed excellent bonding strength, chemical stability and cellular bioactivity, indicating its potential application for orthopaedic implants. PMID:18664431

  9. Influence of Bondcoat Spray Process on Lifetime of Suspension Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Gupta, M.; Markocsan, N.; Li, X.-H.; Östergren, L.

    2018-01-01

    Development of thermal barrier coatings (TBCs) manufactured by suspension plasma spraying (SPS) is of high commercial interest as SPS has been shown capable of producing highly porous columnar microstructures similar to the conventionally used electron beam-physical vapor deposition. However, lifetime of SPS coatings needs to be improved further to be used in commercial applications. The bondcoat microstructure as well as topcoat-bondcoat interface topography affects the TBC lifetime significantly. The objective of this work was to investigate the influence of different bondcoat deposition processes for SPS topcoats. In this work, a NiCoCrAlY bondcoat deposited by high velocity air fuel (HVAF) was compared to commercial vacuum plasma-sprayed NiCoCrAlY and PtAl diffusion bondcoats. All bondcoat variations were prepared with and without grit blasting the bondcoat surface. SPS was used to deposit the topcoats on all samples using the same spray parameters. Lifetime of these samples was examined by thermal cyclic fatigue testing. Isothermal heat treatment was performed to study bondcoat oxidation over time. The effect of bondcoat deposition process and interface topography on lifetime in each case has been discussed. The results show that HVAF could be a suitable process for bondcoat deposition in SPS TBCs.

  10. 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.

  11. Thermal response of plasma sprayed tungsten coating to high heat flux

    International Nuclear Information System (INIS)

    Liu, X.; Yang, L.; Tamura, S.; Tokunaga, K.; Yoshida, N.; Noda, N.; Xu, Z.

    2004-01-01

    In order to investigate the thermal response of tungsten coating on carbon and copper substrates by vacuum plasma spray (VPS) or inert gas plasma spray (IPS), annealing and cyclic heat load experiments of these coatings were conducted. It is indicated that the multi-layered tungsten and rhenium interface of VPS-W/CFC failed to act as a diffusion barrier at elevated temperature and tungsten carbides were developed after 1 h incubation time when annealing temperature was higher than 1600 deg. C. IPS-W/Cu and W/C without an intermediate bonding layer were failed by the detachment of the tungsten coating at 900 and 1200 deg. C annealing for several hours, respectively. Cyclic heat load of electron beam with 35 MW/m 2 and 3-s pulse duration indicated that IPS-W/Cu samples failed with local detachment of the tungsten coating within 200 cycles and IPS-W/C showed local cracks by 300 cycles, but VPS-W/CFC withstood 1000 cycles without visible damages. However, crack creation and propagation in VPS-W/CFC were also observed under higher heat load

  12. Microstructure and Properties of Plasma Sprayed Lead Zirconate Titanate (PZT) Ceramics

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Pala, Zdeněk; Boldyryeva, Hanna; Sedláček, J.; Kmetík, Viliam

    2012-01-01

    Roč. 2, č. 2 (2012), s. 64-75 ISSN 2079-6412 R&D Projects: GA TA ČR TA01010878 Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma spraying * electroceramics * PZT * phase composition * permittivity Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://www.mdpi.com/2079-6412/2/2/64

  13. Characteristics and Thermal Efficiency of a Non-transferred DC Plasma Spraying Torch Under Low Pressure

    International Nuclear Information System (INIS)

    Bao Shicong; Ye Minyou; Zhang Xiaodong; Guo Wenkang; Xu Ping

    2008-01-01

    Current-voltage (I-V) characteristics of a non-transferred DC arc plasma spray torch operated in argon at vacuum are reported. The arc voltage is of negative characteristics for a current below 200 A, flat for a current between 200 A to 250 A and positive for a current beyond 250 A. The voltage increases slowly with the increase in carrier gas of arc. The rate of change in voltage with currents is about 3∼4 V/100 A at a gas flow rate of about 1∼1.5 V/10 standard liter per minute (slpm). The I-V characteristics of the DC plasma torch are of a shape of hyperbola. Arc power increases with the argon flow rate, and the thermal efficiency of the torch acts in a similar way. The thermal efficiency of the non-transferred DC plasmatron is about 65∼78%. (low temperature plasma)

  14. Constrained sintering of an air-plasma-sprayed thermal barrier coating

    International Nuclear Information System (INIS)

    Cocks, A.C.F.; Fleck, N.A.

    2010-01-01

    A micromechanical model is presented for the constrained sintering of an air-plasma-sprayed, thermal barrier coating upon a thick superalloy substrate. The coating comprises random splats with intervening penny-shaped cracks. The crack faces make contact at asperities, which progressively sinter in-service by interfacial diffusion, accommodated by bulk creep. Diffusion is driven by the reduction in interfacial energy at the developing contacts and by the local asperity contact stress. At elevated operating temperature, both sintering and creep strains accumulate within the plane of the coating. The sensitivities of sintering rate and microstructure evolution rate to the kinetic parameters and thermodynamic driving forces are explored. It is demonstrated that the sintering response is governed by three independent timescales, as dictated by the material and geometric properties of the coating. Finally, the role of substrate constraint is assessed by comparing the rate of constrained sintering with that for free sintering.

  15. The structure and thermal properties of plasma-sprayed beryllium for the International Thermonuclear Experimental Reactor (ITER)

    International Nuclear Information System (INIS)

    Castro, R.G.; Bartlett, A.; Elliott, K.E.; Hollis, K.J.

    1996-01-01

    Plasma spraying is being studied for in situ repair of damaged Be and W plasma facing surfaces for ITER, the next generation magnetic fusion energy device, and is also being considered for fabricating Be and W plasma-facing components for the first wall of ITER. Investigators at LANL's Beryllium Atomization and Thermal Spray Facility have concentrated on investigating the structure-property relation between as-deposited microstructures of plasma sprayed Be coatings and resulting thermal properties. In this study, the effect of initial substrate temperature on resulting thermal diffusivity of Be coatings and the thermal diffusivity at the coating/Be substrate interface (interface thermal resistance) was investigated. Results show that initial Be substrate temperatures above 600 C can improve the thermal diffusivity of the Be coatings and minimize any thermal resistance at the interface between the Be coating and Be substrate

  16. 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

  17. Yttria-stabilized zirkonia / gadolinium zirconate double-layer plasma-sprayed thermal barrier coating systems (TBCs)

    International Nuclear Information System (INIS)

    Bakan, Emine

    2015-01-01

    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 2 O 3 -ZrO 2 , YSZ) at long term operation. Zirconate pyrochlores of the large lanthanides((Gd → La) 2 Zr 2 O 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 2 O 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 2 Zr 2 O 7 . Hence, the goal of this research was to investigate plasma-sprayed Gd 2 Zr 2 O 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 thermal conductivity, coefficient of thermal expansion as well

  18. Y2O3-MgO Nano-Composite Synthesized by Plasma Spraying and Thermal Decomposition of Solution Precursors

    Science.gov (United States)

    Muoto, Chigozie Kenechukwu

    This research aims to identify the key feedstock characteristics and processing conditions to produce Y2O3-MgO composite coatings with high density and hardness using solution precursor plasma spray (SPPS) and suspension plasma spray (SPS) processes, and also, to explore the phenomena involved in the production of homogenized nano-composite powders of this material system by thermal decomposition of solution precursor mixtures. The material system would find potential application in the fabrication of components for optical applications such as transparent windows. It was shown that a lack of major endothermic events during precursor decomposition and the resultant formation of highly dense particles upon pyrolysis are critical precursor characteristics for the deposition of dense and hard Y2O3-MgO coatings by SPPS. Using these principles, a new Y2O3-MgO precursor solution was developed, which yielded a coating with Vickers hardness of 560 Hv. This was a considerable improvement over the hardness of the coatings obtained using conventional solution precursors, which was as low as 110 Hv. In the thermal decomposition synthesis process, binary solution precursor mixtures of: yttrium nitrate (Y[n]) or yttrium acetate (Y[a]), with magnesium nitrate (Mg[n]) or magnesium acetate (Mg[a]) were used in order to study the effects of precursor chemistry on the structural characteristics of the resultant Y2O3-MgO powders. The phase domains were coarse and distributed rather inhomogeneously in the materials obtained from the Y[n]Mg[n] and Y[a]Mg[a] mixtures; finer and more homogeneously-distributed phase domains were obtained for ceramics produced from the Y[a]Mg[n] and Y[n]Mg[a] mixtures. It was established that these phenomena were related to the thermal characteristics for the decomposition of the precursors and their effect on phase separation during oxide crystallization. Addition of ammonium acetate to the Y[n[Mg[n] mixture changed the endothermic process to exothermic

  19. Calcium titanate (CaTiO{sub 3}) dielectrics prepared by plasma spray and post-deposition thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ctibor, Pavel [Materials Engineering Department, Institute of Plasma Physics ASCR, v.v.i., Za Slovankou 3, Prague 8 (Czech Republic); Kotlan, Jiri, E-mail: kotlan@ipp.cas.cz [Materials Engineering Department, Institute of Plasma Physics ASCR, v.v.i., Za Slovankou 3, Prague 8 (Czech Republic); Department of Electrotechnology, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6 (Czech Republic); Pala, Zdenek [Materials Engineering Department, Institute of Plasma Physics ASCR, v.v.i., Za Slovankou 3, Prague 8 (Czech Republic); Sedlacek, Josef [Department of Electrotechnology, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6 (Czech Republic); Hajkova, Zuzana; Grygar, Tomas Matys [Institute of Inorganic Chemistry ASCR, v.v.i., Husinec-Rez 1001, Rez (Czech Republic)

    2015-12-15

    Highlights: • Calcium titanate was sprayed by two different plasma spray systems. • Significant improvement of dielectric properties after annealing was observed. • Calcium titanate self-supporting parts can be fabricated by plasma spraying. - Abstract: This paper studies calcium titanate (CaTiO{sub 3}) dielectrics prepared by plasma spray technology. A water stabilized plasma gun (WSP) as well as a widely used gas stabilized plasma gun (GSP) were employed in this study to deposit three sample sets at different spray conditions. Prepared specimens were annealed in air at atmospheric pressure for 2 h at various temperatures from 530 to 1170 °C. X-ray diffraction (XRD), Raman spectroscopy and porosity measurements were used for sample characterization. Dielectric spectroscopy was applied to obtain relative permittivity, conductivity and loss factor frequency dependence. Band gap energy was estimated from reflectance measurements. The work is focused on the explanation of changes in microstructure and properties of a plasma sprayed deposit after thermal annealing. Obtained results show significant improvement of dielectric properties after thermal annealing.

  20. Practical Aspects of Suspension Plasma Spray for Thermal Barrier Coatings on Potential Gas Turbine Components

    Science.gov (United States)

    Ma, X.; Ruggiero, P.

    2018-04-01

    Suspension plasma spray (SPS) process has attracted extensive efforts and interests to produce fine-structured and functional coatings. In particular, thermal barrier coatings (TBCs) applied by SPS process gain increasing interest due to its potential for superior thermal protection of gas turbine hot sections as compared to conventional TBCs. Unique columnar architectures and nano- and submicrometric grains in the SPS-TBC demonstrated some advantages of thermal shock durability, low thermal conductivity, erosion resistance and strain-tolerant microstructure. This work aimed to look into some practical aspects of SPS processing for TBC applications before it becomes a reliable industry method. The spray capability and applicability of SPS process to achieve uniformity thickness and microstructure on curved substrates were emphasized in designed spray trials to simulate the coating fabrication onto industrial turbine parts with complex configurations. The performances of the SPS-TBCs were tested in erosion, falling ballistic impact and indentational loading tests as to evaluate SPS-TBC performances in simulated turbine service conditions. Finally, a turbine blade was coated and sectioned to verify SPS sprayability in multiple critical sections. The SPS trials and test results demonstrated that SPS process is promising for innovative TBCs, but some challenges need to be addressed and resolved before it becomes an economic and capable industrial process, especially for complex turbine components.

  1. 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.

  2. Overview on Recent Developments of Bondcoats for Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Naumenko, D.; Pillai, R.; Chyrkin, A.; Quadakkers, W. J.

    2017-12-01

    The performance of MCrAlY (M = Ni, Co) bondcoats for atmospheric plasma-sprayed thermal barrier coatings (APS-TBCs) is substantially affected by the contents of Co, Ni, Cr, and Al as well as minor additions of Y, Hf, Zr, etc., but also by manufacturing-related properties such as coating thickness, porosity, surface roughness, and oxygen content. The latter properties depend in turn on the exact technology and set of parameters used for bondcoat deposition. The well-established LPPS process competes nowadays with alternative technologies such as HVOF and APS. In addition, new technologies have been developed for bondcoats manufacturing such as high-velocity APS or a combination of HVOF and APS for application of a flashcoat. Future developments of the bondcoat systems will likely include optimization of thermal spraying methods for obtaining complex bondcoat roughness profiles required for extended APS-TBC lifetimes. Introduction of the newest generation single-crystal superalloys possessing low Cr and high Al and refractory metals (Re, Ru) contents will require definition of new bondcoat compositions and/or multilayered bondcoats to minimize interdiffusion issues. The developments of new bondcoat compositions may be substantially facilitated using thermodynamic-kinetic modeling, the vast potential of which has been demonstrated in recent years.

  3. 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

    2017-12-01

    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.

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

    Czech Academy of Sciences Publication Activity Database

    Chráska, Tomáš; Pala, Zdeněk; Mušálek, Radek; Medřický, Jan; Vilémová, Monika

    2015-01-01

    Roč. 24, č. 4 (2015), s. 637-643 ISSN 1059-9630 R&D Projects: GA ČR GAP107/12/1922 Institutional support: RVO:61389021 Keywords : ceramic s * heat treatment * nanostructured materials Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass Impact factor: 1.568, year: 2015

  5. Effects caused by thermal shocks in plasma sprayed protective coatings from materials based on Al2O3

    International Nuclear Information System (INIS)

    Gorski, L.; Wolski, T.; Gostynski, D.

    1996-01-01

    Plasma sprayed coatings from the materials based on Al 2 O 3 with addition of NiO and TiO 2 have been studied. Thermal shock resistance of these coatings has been tested on special experimental arrangement in the stream of hot and cold gases. Changes in coating microstructure has been determined by light microscopy methods. Phase transition caused by the experiments are revealed by X-ray diffraction methods. The resistance for thermal fatigue processes depends on used coatings materials. (author). 21 refs, 21 figs, 1 tab

  6. Wear Characteristics of Ceramic Coating Materials by Plasma Spray under the Lubricative Environment

    International Nuclear Information System (INIS)

    Kim, Chang Ho

    2001-02-01

    This paper is to investigate the wear behaviors of two types of ceramics, Al 2 O 3 and TiO 2 , by coated plasma thermal spray method under the lubricative environment. The lubricative environments are grease fluids, a general hydraulic fluids, and bearing fluids. The wear testing machine used a pin on disk type. Wear characteristics, which were friction force, friction coefficient and the specific wear rate, according to the lubricative environments were obtained at the four kinds of load, and the sliding velocity is 0.2m/sec. After the wear experiments, the wear surfaces of the each test specimen were observed by a scanning electronic microscope. The obtained results are as follows. : 1. The friction coefficients of TiO 2 coating materials are 0.11 ∼ 0.16 range and those of Al 2 O 3 are 0.24 ∼ 0.39. The friction coefficient of two coating materials is relative to the hardness of these materials. 2. The friction coefficient of TiO 2 coating materials in three lubricative environments is almost same to each other in spite of changing of applied loads. 3. The friction coefficient of Al 2 O 3 coating materials is more large in low load than high load. And the friction coefficient in grease is more large than a general hydraulic and bearing fluids had almost same friction coefficient. 4. The specific wear rate in TiO 2 is greatly increasing according to change the applied loads, but that in Al 2 O 3 is slightly. And the wear in grease is the least among three lubricating environments. 5. On the wear mechanism by SEM image observation, the wear of Al 2 O 3 is adhesive wear and TiO 3 is abrasive wear

  7. A laser-treatment condition of plasma-sprayed zirconia thermal barrier coatings on nickel-base superalloy substrate

    International Nuclear Information System (INIS)

    Kondo, Yasuo; Fukaya, Kiyoshi; Miyamoto, Yoshiaki

    1987-06-01

    In order to seal the surface pores, two plasma-sprayed zirconia coatings (containing 8 wt.% CaC 2 and 8 wt.% Y 2 O 3 ) of about 200 microns thickness were partially melted with a CO 2 laser. Preliminary experiment had shown that the laser beam with a power density of 35 W/mm 2 could melt plasma-sprayed zirconia to depth of 50 to 80 microns at a scanning speed of about 300 mm/min. There was little porosity in the laser-treated region. However, straiations and mud-flat cracking of about 50 microns in depth were produced by the laser-treatment. Numerous fine particles of a few microns diameter were formed on the laser-treated surface, and microcracks were propagated between these fine particles. In the CaC 2 /ZrO 2 ceramic coating system, calcium content of the laser-treated region became less compared with that of the nontreated region. While, in the Y 2 O 3 /ZrO 2 system, yttrium distribution in the laser-treated area was more uniform than that in the nontreated area. This indicates that Y 2 O 3 /ZrO 2 system is more stable than CaC 2 /ZrO 2 system to laser treatment. (author)

  8. Higher Temperature Thermal Barrier Coatings with the Combined Use of Yttrium Aluminum Garnet and the Solution Precursor Plasma Spray Process

    Science.gov (United States)

    Gell, Maurice; Wang, Jiwen; Kumar, Rishi; Roth, Jeffery; Jiang, Chen; Jordan, Eric H.

    2018-02-01

    Gas-turbine engines are widely used in transportation, energy and defense industries. The increasing demand for more efficient gas turbines requires higher turbine operating temperatures. For more than 40 years, yttria-stabilized zirconia (YSZ) has been the dominant thermal barrier coating (TBC) due to its outstanding material properties. However, the practical use of YSZ-based TBCs is limited to approximately 1200 °C. Developing new, higher temperature TBCs has proven challenging to satisfy the multiple property requirements of a durable TBC. In this study, an advanced TBC has been developed by using the solution precursor plasma spray (SPPS) process that generates unique engineered microstructures with the higher temperature yttrium aluminum garnet (YAG) to produce a TBC that can meet and exceed the major performance standards of state-of-the-art air plasma sprayed YSZ, including: phase stability, sintering resistance, CMAS resistance, thermal cycle durability, thermal conductivity and erosion resistance. The temperature improvement for hot section gas turbine materials (superalloys & TBCs) has been at the rate of about 50 °C per decade over the last 50 years. In contrast, SPPS YAG TBCs offer the near-term potential of a > 200 °C improvement in temperature capability.

  9. Higher Temperature Thermal Barrier Coatings with the Combined Use of Yttrium Aluminum Garnet and the Solution Precursor Plasma Spray Process

    Science.gov (United States)

    Gell, Maurice; Wang, Jiwen; Kumar, Rishi; Roth, Jeffery; Jiang, Chen; Jordan, Eric H.

    2018-04-01

    Gas-turbine engines are widely used in transportation, energy and defense industries. The increasing demand for more efficient gas turbines requires higher turbine operating temperatures. For more than 40 years, yttria-stabilized zirconia (YSZ) has been the dominant thermal barrier coating (TBC) due to its outstanding material properties. However, the practical use of YSZ-based TBCs is limited to approximately 1200 °C. Developing new, higher temperature TBCs has proven challenging to satisfy the multiple property requirements of a durable TBC. In this study, an advanced TBC has been developed by using the solution precursor plasma spray (SPPS) process that generates unique engineered microstructures with the higher temperature yttrium aluminum garnet (YAG) to produce a TBC that can meet and exceed the major performance standards of state-of-the-art air plasma sprayed YSZ, including: phase stability, sintering resistance, CMAS resistance, thermal cycle durability, thermal conductivity and erosion resistance. The temperature improvement for hot section gas turbine materials (superalloys & TBCs) has been at the rate of about 50 °C per decade over the last 50 years. In contrast, SPPS YAG TBCs offer the near-term potential of a > 200 °C improvement in temperature capability.

  10. Failure analysis of thermally cycled columnar thermal barrier coatings produced by high-velocity-air fuel and axial-suspension-plasma spraying: A design perspective

    Czech Academy of Sciences Publication Activity Database

    Ganvir, A.; Vaidhyanathan, V.; Markocsan, N.; Gupta, M.; Pala, Zdeněk; Lukáč, František

    2018-01-01

    Roč. 44, č. 3 (2018), s. 3161-3172 ISSN 0272-8842 Institutional support: RVO:61389021 Keywords : Columnar Thermal Barrier Coatings * Axial Suspension Plasma spraying * Thermal Cyclic Fatigue * High Velocity Air Fuel Spraying Subject RIV: JK - Corrosion ; Surface Treatment of Materials OBOR OECD: Coating and films Impact factor: 2.986, year: 2016 https://www.sciencedirect.com/science/article/pii/S0272884217325403

  11. SiC fiber and yttria-stabilized zirconia composite thick thermal barrier coatings fabricated by plasma spray

    Science.gov (United States)

    Ma, Rongbin; Cheng, Xudong; Ye, Weiping

    2015-12-01

    Approximately 4 mm-thick SiC fiber/yttria-stabilized zirconia (YSZ) composite thermal barrier coatings (TBCs) were prepared by atmospheric plasma spray (APS). The composite coatings have a 'reinforced concrete frame structure', which can protect the coating from failure caused by increasing thickness of coating. The SiC fiber plays an important role in reducing the residual stress level of the composite coatings. The thermal conductivity (TC) value of the composite coatings is 0.632 W/m K, which is about 50% reduction compared to that of typical APS YSZ TBCs. And the composite coatings have higher fracture toughness and better thermal shock resistance than the YSZ TBCs.

  12. Thermal Conductivity and Erosion Durability of Composite Two-Phase Air Plasma Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Schmitt, Michael P.; Rai, Amarendra K.; Zhu, Dongming; Dorfman, Mitchell R.; Wolfe, Douglas E.

    2015-01-01

    To enhance efficiency of gas turbines, new thermal barrier coatings (TBCs) must be designed which improve upon the thermal stability limit of 7 wt% yttria stabilized zirconia (7YSZ), approximately 1200 C. This tenant has led to the development of new TBC materials and microstructures capable of improved high temperature performance. This study focused on increasing the erosion durability of cubic zirconia based TBCs, traditionally less durable than the metastable t' zirconia based TBCs. Composite TBC microstructures composed of a low thermal conductivity/high temperature stable cubic Low-k matrix phase and a durable t' Low-k secondary phase were deposited via APS. Monolithic coatings composed of cubic Low-k and t' Low-k were also deposited, in addition to a 7YSZ benchmark. The thermal conductivity and erosion durability were then measured and it was found that both of the Low-k materials have significantly reduced thermal conductivities, with monolithic t' Low-k and cubic Low-k improving upon 7YSZ by approximately 13 and approximately 25%, respectively. The 40 wt% t' Low-k composite (40 wt% t' Low-k - 60 wt% cubic Low-k) showed a approximately 22% reduction in thermal conductivity over 7YSZ, indicating even at high levels, the t' Low-k secondary phase had a minimal impact on thermal in the composite coating. It was observed that a mere 20 wt% t' Low-k phase addition can reduce the erosion of a cubic Low-k matrix phase composite coating by over 37%. Various mixing rules were then investigated to assess this non-linear composite behavior and suggestions were made to further improve erosion durability.

  13. Electroform/Plasma-Spray Laminates for X-Ray Optics

    Science.gov (United States)

    Ulmer, Melville P.; Graham, Michael; Vaynman, Semyon

    2007-01-01

    Electroform/plasma-spray laminates have shown promise as lightweight, strong, low-thermal-expansion components for xray optics. The basic idea is to exploit both (1) the well-established art of fabrication of optical components by replication and (2) plasma spraying as a means of reinforcing a thin replica optic with one or more backing layer(s) having tailorable thermomechanical properties. In x-ray optics as in other applications, replication reduces the time and cost of fabrication because grinding and polishing can be limited to a few thick masters, from which many lightweight replicas can thereafter be made. The first step in the fabrication of a component of the type in question is to make a replica optic by electroforming a thin layer of nickel on a master. Through proper control of the electroforming process conditions, it is possible to minimize residual stress and, hence, to minimize distortion in the replica. Next, a powder comprising ceramic particles coated with a metal compatible with the electroformed nickel is plasma-sprayed onto the backside of the nickel replica. Then through several repetitions and variations of the preceding steps or perhaps a small compressive stress, alternating layers of electroformed nickel and plasma-sprayed metal-coated ceramic powder are deposited. The thicknesses of the layers and the composition of the metal-coated ceramic powder are chosen to optimize the strength, areal mass density, and toughness of the finished component. An important benefit of using both electroforming and plasma spraying is the possibility of balancing stresses to a minimum level, which could be zero or perhaps a small net compressive stress designed to enhance the function of the component in its intended application.

  14. DEVELOPMENT OF WEAR RESISTANT COATINGS FORMED BY PLASMA SPRAYING OF ALLOY Ni–Fe–Cr–Si–B–C SYSTEM REINFORCED WITH CERAMICS Al2O3

    Directory of Open Access Journals (Sweden)

    A. S. Kalinichenko

    2016-01-01

    Full Text Available . Creating a functionally oriented, including nanostructured, anti-friction materials and coatings with qualitatively new complex of service properties is an important scientific and practical problem. In particular, for the cable industry it is urgent task of ensuring the high performance properties of fast deteriorating stretching and supporting rollers. Working surfaces of these parts operate under practically dry friction conditions with constantly updated material of stretching wire. Plasma spraying is one of the widely used methods of surface engineering to create wear resistant coatings and which is characterized with process flexibility and the ability to create coatings using various materials and alloys including composite ones. The installation UPU-3D with the PP-25 plasma torch was used for plasma spraying. The thickness of the sprayed layer was 0.8–1.1 mm. As a material for the deposition of composite coatings a powder mixture of self-fluxing nickel alloy PG-HN80SR4 (system Ni–Fe–Cr–Si–B–C and a neutral oxide ceramics Al2O3 was used. The amount of ceramics varied from 15 to 33 %. This ceramic oxide was selected due to the desire to reduce coatings’ costs while providing high durability. Carried out phase and microstructural studies have shown when ceramics was added in an amount more than 20 % a formation of conglomerates formed by not melted alumina particles often was observed. These conglomerates serve as crack formation centers in the coating. The phase composition of the coatings practically does not depend on the content of ceramics compounds. Tribological tests have shown that the best results were obtained when the content of the oxide ceramic in the coating was in the range from 15 to 20 %.

  15. Plasma sprayed thermal barrier coatings for industrial gas turbines: morphology, processing and properties

    International Nuclear Information System (INIS)

    Gruenling, H.W.; Mannsmann, W.

    1993-01-01

    Thermal barrier coatings out of fully or partially stabilized zirconia offer a unique chance in gas turbines to increase the gas inlet temperature significantly while keeping the temperature of the structural material of the component within conventional limits. The protection of combustor parts and transition pieces as well as of some stationary gas turbine parts however is state of the art. As a consequence of still insufficient reliability, the application for hot rotating parts is very limited. The introduction as a design element requires safe life within defined time intervals. These depend on the overhaul and repair intervals of the engines. For large land based industrial or utility gas turbines, for example, coating life between 25.000 and 30.000 hrs. is a minimum requirement. Premature failure of a coating by e.g. local spalling causes local overheating of the component with the consequence of its total destruction or even more expensive secondary damages. Life limiting is the corrosion rate at the ceramic-metal interface and the behavior of the coated system under transient operating conditions, where multiaxial strain and stress distributions are generated. Sufficient strain tolerance of the coating both under tensile as well as compressive conditions is required. The properties of thermal barrier coating systems depend strongly on the structure and phase composition of the coating layers and the morphology of and the adhesion at the ceramic-metal interface. They have to be controlled by the process itself, the process parameters and the characteristics of the applied materials (e.g. chemical composition, processing, morphology, particle size and size distribution). It will be reviewed, how properties and structures of coating systems correlate and how structures can be modified by careful control of the process parameters. (orig.)

  16. Deposition and characterization of plasma sprayed Ni-5A1/ magnesia stabilized zirconia based functionally graded thermal barrier coating

    International Nuclear Information System (INIS)

    Baig, M N; Khalid, F A

    2014-01-01

    Thermal barrier coatings (TBCs) are employed to protect hot section components in industrial and aerospace gas turbine engines. Conventional TBCs frequently fail due to high residual stresses and difference between coefficient of thermal expansion (CTE) of the substrate and coatings. Functionally graded thermal barrier coatings (FG-TBCs) with gradual variation in composition have been proposed to minimize the problem. In this work, a five layered functionally graded thermal barrier coating system was deposited by atmospheric plasma spray (APS) technique on Nimonic 90 substrates using Ni-5Al as bond coat (BC) and magnesia stabilized zirconia as top coat (TC). The coatings were characterized by SEM, EDS, XRD and optical profilometer. Microhardness and coefficient of thermal expansion of the five layers deposited as individual coatings were also measured. The deposited coating system was oxidized at 800°C. SEM analysis showed that five layers were successfully deposited by APS to produce a FG-TBC. The results also showed that roughness (Ra) of the individual layers decreased with an increase in TC content in the coatings. It was found that microhardness and CTE values gradually changed from bond coat to cermet layers to top coat. The oxidized coated sample revealed parabolic behavior and changes in the surface morphology and composition of coating

  17. Effect of Microstructure on the Thermal Conductivity of Plasma Sprayed Y2O3 Stabilized Zirconia (8% YSZ

    Directory of Open Access Journals (Sweden)

    Ningning Hu

    2017-11-01

    Full Text Available In this paper, the effect of microstructure on the thermal conductivity of plasma-sprayed Y2O3 stabilized ZrO2 (YSZ thermal barrier coatings (TBCs is investigated. Nine freestanding samples deposited on aluminum alloys are studied. Cross-section morphology such as pores, cracks, m-phase content, grain boundary density of the coated samples are examined by scanning electron microscopy (SEM and electron back-scattered diffraction (EBSD. Multiple linear regressions are used to develop quantitative models that describe the relationship between the particle parameters, m-phase content and features of the microstructure such as porosity, crack-porosity, and the length density of small and big angle-cracks. Moreover, the relationship between the microstructure and thermal conductivity is investigated. Results reveal that the thermal conductivity of the coating is mainly determined by the microstructure and grain boundary density at room temperature (25 °C, and by the length density of big-angle-crack, monoclinic phase content and grain boundary density at high temperature (1200 °C.

  18. Improved Thermally Grown Oxide Scale in Air Plasma Sprayed NiCrAlY/Nano-YSZ Coatings

    International Nuclear Information System (INIS)

    Daroonparvar, M.; Yajid, M.A.M.; Yusof, N.M.; Hussain, M.S.

    2013-01-01

    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 nano structured and micro structured YSZ coatings was investigated at 1000 degree c for 24 h, 48 h, and 120 h. Air plasma sprayed nano-YSZ coating exhibited a tri modal 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 Al 2 O 3 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 Al 2 O 3 oxide scale were diminished in nano-TBC system compared to normal TBC system.

  19. New generation of plasma-sprayed mullite coatings on silicon carbide

    Science.gov (United States)

    Lee, Kang N.; Miller, Robert A.; Jacobson, Nathan S.

    1995-01-01

    Mullite is promising as a protective coating for silicon-based ceramics in aggressive high-temperature environments. Conventionally plasma-sprayed mullite on SiC tends to crack and debond on thermal cycling. It is shown that this behavior is due to the presence of amorphous mullite in the conventionally sprayed mullite. Heating the SiC substrate during the plasma spraying eliminated the amorphous phase and produced coatings with dramatically improved properties. The new coating exhibits excellent adherence and crack resistance under thermal cycling between room temperature and 1000 to 1400 C. Preliminary tests showed good resistance to Na2CO3-induced hot corrosion.

  20. 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.

  1. Study on the cutting behavior of plasma sprayed ceramic coatings. Plasma yosha ceramics himaku no sessaku kyodo ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Inui, Y; Kubohori, T; Ikuta, T [Kinki Univ., Higashi-Osaka, Osaka (Japan). Faculty of Science and Technology

    1992-09-30

    Fracture behavior of Al2O3-TiO2 sprayed ceramic coating was investigated at low cutting speeds when using two dimensional cutting. Scanning electron microscope was used to observe the generation, development and propagation of cracks during cutting. Small cracks and fracture have been developed in the cutting groove along the cutting direction, and there has been many fractures in spray particles unit. In the initial stage of cutting, radiant cracks have developed on the sprayed coating, however, linear big cracks starting from the cutting edge towards the cutting direction, have developed. The cracks have developed along the grain boundary of coating component, and cracks progressed along the portion with weak bonding force. When the depth of the cut was under 5[mu]m, the cutting face has formed many microfractures, and the cutting has been very stable. It has been necessary to select the cutting conditions that do not cause big fracture, microcutting and so on, in order to achieve favorable surface condition with minor fractures. 8 refs., 13 figs., 2 tabs.

  2. Plasma sprayed samarium--cobalt permanent magnets

    International Nuclear Information System (INIS)

    Willson, M.C.; Janowiecki, R.J.

    1975-01-01

    Samarium--cobalt permanent magnets were fabricated by arc plasma spraying. This process involves the injection of relatively coarse powder particles into a high-temperature gas for melting and spraying onto a substrate. The technique is being investigated as an economical method for fabricating cobalt--rare earth magnets for advanced traveling wave tubes and cross-field amplifiers. Plasma spraying permits deposition of material at high rates over large areas with optional direct bonding to the substrate, and offers the ability to fabricate magnets in a variety of shapes and sizes. Isotropic magnets were produced with high coercivity and good reproducibility in magnetic properties. Post-spray thermal treatments were used to enhance the magnetic properties of sprayed deposits. Samarium--cobalt magnets, sprayed from samarium-rich powder and subjected to post-spray heat treatment, displayed energy products in excess of 9 million gauss-oersteds and coercive forces of approximately 6000 oersteds. Bar magnet arrays were constructed by depositing magnets on ceramic substrates. (auth)

  3. Plasma sprayed samarium--cobalt permanent magnets

    International Nuclear Information System (INIS)

    Willson, M.C.; Janowiecki, R.J.

    1975-01-01

    Samarium--Co permanent magnets were fabricated by arc plasma spraying. This process involves the injection of relatively coarse powder particles into a high temperature gas for melting and spraying onto a substrate. The technique is being investigated as an economical method for fabricating Co--rare earth magnets for advanced traveling wave tubes and cross-field amplifiers. Plasma spraying permits deposition of material at high rates over large areas with optional direct bonding to the substrate, and offers the ability to fabricate magnets in a variety of shapes and sizes. Isotropic magnets were produced with high coercivity and good reproducibility in magnetic properties. Post-spray thermal treatments were used to enhance the magnetic properties of sprayed deposits. Samarium--Co magnets, sprayed from Sm-rich powder and subjected to post-spray heat treatment, displayed energy products in excess of 9 million G-Oe and coercive forces of approximately 6000 Oe. Bar magnet arrays were constructed by depositing magnets on ceramic substrates

  4. Re-emission and thermal desorption of deuterium from plasma sprayed tungsten coatings for application in ASDEX-upgrade

    International Nuclear Information System (INIS)

    Garcia-Rosales, C.; Franzen, P.; Plank, H.; Roth, J.; Gauthier, E.

    1996-01-01

    The trapping and release of deuterium implanted with an energy of 100 eV in wrought and in plasma sprayed tungsten of different manufacture and structure has been investigated by means of re-emission as well as thermal and isothermal desorption spectroscopy. The experimental data for wrought tungsten are compared with model calculations with the PIDAT code in order to estimate the parameters governing diffusion, surface recombination and trapping in tungsten. The amount of retained deuterium in tungsten is of the same order of magnitude as in graphite for the implantation parameters used in this work. The mobile hydrogen concentration in tungsten during the implantation is of the same order of magnitude than the trapped one, being released after the termination of the implantation. The fraction of deuterium trapped to defects increases strongly with the porosity of the samples. The temperature needed for the release of the trapped deuterium (∝600 K) are considerably lower than for graphite, due to the smaller trapping energy (≤1.5 eV). (orig.)

  5. 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.

  6. Evaluation of bond strength of isothermally aged plasma sprayed thermal barrier coating

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Jin; Lee, Dong Hoon; Koo, Jae Mean; Song, Sung Jin; Seok, Chang Sung [Sungkyunkwan University, Suwon (Korea, Republic of); Kim, Mun Young [Korea Plant Service and Engineering Co., Ltd., Seongnam (Korea, Republic of)

    2008-07-15

    In this study, disk type of thermal barrier coating system for gas turbine blade was isothermally aged in the furnace changing exposure time and temperature. For each aging condition, bond tests for three samples were conducted for evaluating degradation of adhesive or cohesive strength of thermal barrier coating system. For as-sprayed condition, the location of fracture in the bond test was in the middle of epoxy which have bond strength of 57 MPa. As specimens are degraded by thermal aging, bond strength gradually decreased and the location of failure was also changed from within top coat at the earlier stage of thermal aging to the interface between top coat and TGO at the later stage due to the delamination in the coating.

  7. 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."

  8. Evaluation of Degradation of Isothermally Aged Plasma-Sprayed Thermal Barrier Coating

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Jae Mean; Seok, Chang Sung; Kang, Min Sung; Kim, Dae Jin [Sungkyunkwan University, Seoul (Korea, Republic of); Lee, Dong Hoon [HYUNDAI STEEL CO., Incheon (Korea, Republic of); Kim, Mun Young [KPS Gas Turbine Technology Service Center, Seongnam (Korea, Republic of)

    2010-04-15

    The thermal barrier coating of a gas turbine blade was degraded by isothermal heating in a furnace and by varying the exposure time and temperature. Then, a micro-Vickers hardness test was conducted on the cross section of the bond coat and Ni-based superalloy substrate. Further, the thickness of TGO(Thermally Grown Oxide) was measured by using an image analyzer, and the changes in the microstructure and element contents in the coating were analyzed by using an optical microscope and by performing SEM-EDX analysis. No significant change was observed in the Vickers hardness of the bond coat when the coated specimen was degraded at a high temperature: delamination was observed between the top coat and the bond coat when the coating was degraded for 50 h at a temperature 1,151 .deg. C.

  9. Application of Structure-Based Models of Mechanical and Thermal Properties on Plasma Sprayed Coatings

    Czech Academy of Sciences Publication Activity Database

    Vilémová, Monika; Matějíček, Jiří; Mušálek, Radek; Nohava, J.

    2012-01-01

    Roč. 21, 3-4 (2012), s. 372-382 ISSN 1059-9630 R&D Projects: GA MŠk ME 901 Institutional research plan: CEZ:AV0Z20430508 Keywords : analytical model * elastic modulus * finite element modeling * image analysis * modeling of properties * thermal conductivity * water stabilized plasma Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.481, year: 2012 http://www.springerlink.com/content/3m24812367315142/fulltext. pdf

  10. Dielectric properties of plasma sprayed silicates

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Sedláček, J.; Neufuss, Karel; Dubský, Jiří; Chráska, Pavel

    -, č. 31 (2005), s. 315-321 ISSN 0272-8842 R&D Projects: GA ČR(CZ) GA202/03/0708 Institutional research plan: CEZ:AV0Z20430508 Keywords : Optical microscopy * electrical properties * silicates * insulators * plasma spraying Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.702, year: 2005

  11. Plasma sprayed alumina coatings for radiation detector development

    Indian Academy of Sciences (India)

    A mechanical as well as metallurgical bonding is necessary. 3. Applications ... Here the feasibility of using metallic components that were plasma spray- ... To study the electrical insulation, integrity of ceramic coating etc, tests were carried out.

  12. Behaviour of plasma spray coatings under disruption simulation

    International Nuclear Information System (INIS)

    Brossa, F.; Rigon, G.; Looman, B.

    1988-01-01

    The behaviour of metallic and ceramic protective coatings under disruption simulations was studied correlating the damage with their physical and structural parameters. Plasma Spray (PS) and Vacuum Plasma Spray (VPS) were the techniques used for the production of the coatings. W-5% Re was selected for divertor plates, and TiC, TiO 2 , Al 2 O 3 , low-Z ceramic materials for the first wall protection on 316 SS, Cu and Al as substrates. An electron beam gun was used to simulate the plasma disruptions. The tests were carried out from 0.6 to 6 MJ/m 2 . The thermal effects were studied by metallographic and EDXA analysis. The damage was observed comparing the degree of protection provided by each coating to discover the minimum thickness necessary to prevent the underlying material from melting. Good protective coatings must have a high melting point, great porosity and low thermal conductivity. Such coatings act as thermal barriers, increasing the surface temperature and radiating back large parts of the energy. (orig.)

  13. Plasma sprayed thermoregulating coatings

    International Nuclear Information System (INIS)

    Kudinov, V.V.; Puzanov, A.A.; Zambrzhitskij, A.P.; Soboleva, V.V.

    1979-01-01

    Shown is the possibility of plasma spraying application for thermoregulating coating formation. Given are test results of service properties of BeO, Al 2 O 2 plasma coatings on the substrates of the MA2-1 magnesium alloy. Described is a device for studying durability of coating optical parameters under ultraviolet irradiation in deep vacuum. Dynamics of absorption coefficient, growth caused by an increase in absorption centers amount under such irradiation is investigated

  14. Plasma spraying of beryllium and beryllium-aluminum-silver alloys

    International Nuclear Information System (INIS)

    Castro, R.G.; Stanek, P.W.; Elliott, K.E.; Jacobson, L.A.

    1994-01-01

    A preliminary investigation on plasma-spraying of beryllium and a beryllium-aluminum-4% silver alloy was done at the Los Alamos National Laboratory's Beryllium Atomization and Thermal Spray Facility (BATSF). Spherical Be and Be-Al-4%Ag powders, which were produced by centrifugal atomization, were used as feedstock material for plasma-spraying. The spherical morphology of the powders allowed for better feeding of fine (<38 μm) powders into the plasma-spray torch. The difference in the as-deposited densities and deposit efficiencies of the two plasma-sprayed powders will be discussed along with the effect of processing parameters on the as-deposited microstructure of the Be-Al-4%Ag. This investigation represents ongoing research to develop and characterize plasma-spraying of beryllium and beryllium-aluminum alloys for magnetic fusion and aerospace applications

  15. Plasma spraying of beryllium and beryllium-aluminum-silver alloys

    International Nuclear Information System (INIS)

    Castro, R.G.; Stanek, P.W.; Elliott, K.E.; Jacobson, L.A.

    1993-01-01

    A preliminary investigation on plasma-spraying of beryllium and a beryllium-aluminum 4% silver alloy was done at the Los Alamos National Laboratory's Beryllium Atomization and Thermal Spray Facility (BATSF). Spherical Be and Be-Al-4%Ag powders, which were produced by centrifugal atomization, were used as feedstock material for plasma-spraying. The spherical morphology of the powders allowed for better feeding of fine (<38 μm) powders into the plasma-spray torch. The difference in the as-deposited densities and deposit efficiencies of the two plasma-sprayed powders will be discussed along with the effect of processing parameters on the as-deposited microstructure of the Be-Al-4%Ag. This investigation represents ongoing research to develop and characterize plasma-spraying of beryllium and beryllium-aluminum alloys for magnetic fusion and aerospace applications

  16. Current Progress in Solution Precursor Plasma Spraying of Cermets: A Review

    Directory of Open Access Journals (Sweden)

    Romnick Unabia

    2018-06-01

    Full Text Available Ceramic and metal composites, known also as cermets, may considerably improve many material properties with regards to that of initial components. Hence, cermets are frequently applied in many technological fields. Among many processes which can be employed for cermet manufacturing, thermal spraying is one of the most frequently used. Conventional plasma spraying of powders is a popular and cost-effective manufacturing process. One of its most recent innovations, called solution precursor plasma spraying (SPPS, is an emerging coating deposition method which uses homogeneously mixed solution precursors as a feedstock. The technique enables a single-step deposition avoiding the powder preparation procedures. The nanostructured coatings developed by SPPS increasingly find a place in the field of surface engineering. The present review shows the recent progress in the fabrication of cermets using SPPS. The influence of starting solution precursors, such as their chemistry, concentration, and solvents used, to the micro-structural characteristics of cermet coatings is discussed. The effect of the operational plasma spray process parameters such as solution injection mode to the deposition process and coatings’ microstructure is also presented. Moreover, the advantages of the SPPS process and its drawbacks compared to the conventional powder plasma spraying process are discussed. Finally, some applications of SPPS cermet coatings are presented to understand the potential of the process.

  17. 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.

  18. Thermal shock behavior of toughened gadolinium zirconate/YSZ double-ceramic-layered thermal barrier coating

    International Nuclear Information System (INIS)

    Zhong, Xinghua; Zhao, Huayu; Zhou, Xiaming; Liu, Chenguang; Wang, Liang; Shao, Fang; Yang, Kai; Tao, Shunyan; Ding, Chuanxian

    2014-01-01

    Highlights: • Gd 2 Zr 2 O 7 /YSZ DCL thermal barrier coating was designed and fabricated. • The Gd 2 Zr 2 O 7 top ceramic layer was toughened by addition of nanostructured 3YSZ. • Remarkable improvement in thermal shock resistance of the DCL coating was achieved. - Abstract: Double-ceramic-layered (DCL) thermal barrier coating system comprising of toughened Gadolinium zirconate (Gd 2 Zr 2 O 7 , GZ) as the top ceramic layer and 4.5 mol% Y 2 O 3 partially-stabilized ZrO 2 (4.5YSZ) as the bottom ceramic layer was fabricated by plasma spraying and thermal shock behavior of the DCL coating was investigated. The GZ top ceramic layer was toughened by addition of nanostructured 3 mol% Y 2 O 3 partially-stabilized ZrO 2 (3YSZ) to improve fracture toughness of the matrix. The thermal shock resistance of the DCL coating was enhanced significantly compared to that of single-ceramic-layered (SCL) GZ-3YSZ composite coating, which is believed to be primarily attributed to the two factors: (i) the increase in fracture toughness of the top ceramic layer by incorporating nanostructured YSZ particles and (ii) the improvement in strain tolerance through the utilization of 4.5YSZ as the bottom ceramic layer. In addition, the failure mechanisms are mainly attributed to the still low fracture toughness of the top ceramic layer and oxidation of the bond-coat

  19. Development & characterization of alumina coating by atmospheric plasma spraying

    Science.gov (United States)

    Sebastian, Jobin; Scaria, Abyson; Kurian, Don George

    2018-03-01

    Ceramic coatings are applied on metals to prevent them from oxidation and corrosion at room as well as elevated temperatures. The service environment, mechanisms of protection, chemical and mechanical compatibility, application method, control of coating quality and ability of the coating to be repaired are the factors that need to be considered while selecting the required coating. The coatings based on oxide materials provides high degree of thermal insulation and protection against oxidation at high temperatures for the underlying substrate materials. These coatings are usually applied by the flame or plasma spraying methods. The surface cleanliness needs to be ensured before spraying. Abrasive blasting can be used to provide the required surface roughness for good adhesion between the substrate and the coating. A pre bond coat like Nickel Chromium can be applied on to the substrate material before spraying the oxide coating to avoid chances of poor adhesion between the oxide coating and the metallic substrate. Plasma spraying produces oxide coatings of greater density, higher hardness, and smooth surface finish than that of the flame spraying process Inert gas is often used for generation of plasma gas so as to avoid the oxidation of the substrate material. The work focuses to develop, characterize and optimize the parameters used in Al2O3 coating on transition stainless steel substrate material for minimizing the wear rate and maximizing the leak tightness using plasma spray process. The experiment is designed using Taguchi’s L9 orthogonal array. The parameters that are to be optimized are plasma voltage, spraying distance and the cooling jet pressure. The characterization techniques includes micro-hardness and porosity tests followed by Grey relational analysis of the results.

  20. Calcium titanate (CaTiO3) dielectrics prepared by plasma spray and post-deposition thermal treatment

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Kotlan, Jiří; Pala, Zdeněk; Sedláček, J.; Hájková, Zuzana; Matys Grygar, Tomáš

    2015-01-01

    Roč. 72, December (2015), s. 123-132 ISSN 0025-5408 Institutional support: RVO:61389021 ; RVO:61388980 Keywords : Ceramics * Plasma deposition * Impedance spectroscopy * Raman spectroscopy * Dielectrics Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass; JH - Ceramics, Fire-Resistant Materials and Glass (UACH-T) Impact factor: 2.435, year: 2015 http://www.sciencedirect.com/science/article/pii/S0025540815300623

  1. Thermal Conductivity and Thermal Gradient Cyclic Behavior of Refractory Silicate Coatings on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Lee, Kang N.; Miller, Robert A.

    2001-01-01

    Plasma-sprayed mullite and BSAS coatings have been developed to protect SiC/SiC ceramic matrix composites from high temperature environmental attack. In this study, thermal conductivity and thermal barrier functions of these coating systems are evaluated using a laser high-heat-flux test rig. The effects of water vapor on coating thermal conductivity and durability are studied by using alternating furnace and laser thermal gradient cyclic tests. The influence of laser high thermal-gradient cycling on coating failure modes is also investigated.

  2. Thermophysical Properties of Cold and Vacuum Plasma Sprayed Cu-Cr-X Alloys, NiAl and NiCrAlY Coatings. Part 1; Electrical and Thermal Conductivity, Thermal Diffusivity, and Total Hemispherical Emissivity

    Science.gov (United States)

    Raj, S. V.

    2017-01-01

    This two-part paper reports the thermophysical properties of several cold and vacuum plasma sprayed monolithic Cu and Ni-based alloy coatings. Part I presents the electrical and thermal conductivity, thermal diffusivity, and total hemispherical emissivity data while Part II reports the specific heat capacity data for these coatings. Metallic copper alloys, stoichiometric NiAl and NiCrAlY coatings were fabricated by either the cold sprayed or the vacuum plasma spray deposition processes for thermal property measurements between 77 and 1223 K. The temperature dependencies of the thermal conductivities, thermal diffusivities, electrical conductivities and total hemispherical emissivities of these cold and vacuum sprayed monolithic coatings are reported in this paper. The electrical and thermal conductivity data correlate reasonably well for Cu-8%Cr-1%Al, Cu-23%Cr-5%Al and NiAl in accordance with the Wiedemann-Franz (WF) law although a better fit is obtained using the Smith-Palmer relationship. The Lorentz numbers determined from the WF law are close to the theoretical value.

  3. Dielectric and mechanical properties of plasma-sprayed olivine

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Neufuss, Karel; Pala, Zdeněk; Kotlan, Jiří; Soumar, J.

    2015-01-01

    Roč. 67, č. 2 (2015), s. 600-616 ISSN 1221-1451. [International Conference on Plasma Physics and Applications/16./. Magurele, Bucharest, 20.06.2013-25.06.2013] Institutional support: RVO:61389021 Keywords : olivine * plasma spraying * dielectric properties Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.367, year: 2015 www.infim.ro/rrp

  4. Plasma spraying process of disperse carbides for spraying and facing

    International Nuclear Information System (INIS)

    Blinkov, I.V.; Vishnevetskaya, I.A.; Kostyukovich, T.G.; Ostapovich, A.O.

    1989-01-01

    A possibility to metallize carbides in plasma of impulsing capacitor discharge is considered. Powders granulation occurs during plasma spraying process, ceramic core being completely capped. X-ray phase and chemical analyses of coatings did not show considerable changes of carbon content in carbides before and after plasma processing. This distinguishes the process of carbides metallization in impulsing plasma from the similar processing in arc and high-frequency plasma generator. Use of powder composites produced in the impulsing capacitor discharge, for plasma spraying and laser facing permits 2-3 times increasing wear resistance of the surface layer as against the coatings produced from mechanical powders mixtures

  5. Plasma-sprayed tantalum/alumina cermets

    International Nuclear Information System (INIS)

    Kramer, C.M.

    1977-12-01

    Cermets of tantalum and alumina were fabricated by plasma spraying, with the amount of alumina varied from 0 to 65 percent (by volume). Each of four compositions was then measured for tensile strength, elastic modulus, and coefficient of thermal expansion. In general, strength and strain to failure decreased with increasing alumina content: 62 MPa for 100 percent Ta to 19 MPa for 35 v percent Ta. A maximum of 0.1 percent strain was observed for the sprayed 100 percent Ta specimens. The coefficient of thermal expansion measured for the pure Ta was 6.2 (10 -6 )/K

  6. Phase Formation Control in Plasma Sprayed Alumina–Chromia Coatings

    Czech Academy of Sciences Publication Activity Database

    Dubský, Jiří; Chráska, Pavel; Kolman, Blahoslav Jan; Stahr, C.Ch.; Berger, L.-M.

    2011-01-01

    Roč. 55, č. 3 (2011), s. 294-300 ISSN 0862-5468 R&D Projects: GA ČR GA106/08/1240 Institutional research plan: CEZ:AV0Z20430508 Keywords : Alumina * Chromia * Plasma spraying * Phase stabilization Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.382, year: 2011 http://www.ceramics-silikaty.cz/2011/2011_03_294.htm

  7. Automated Plasma Spray (APS) process feasibility study: Plasma spray process development and evaluation

    Science.gov (United States)

    Fetheroff, C. W.; Derkacs, T.; Matay, I. M.

    1979-01-01

    An automated plasma spray (APS) process was developed to apply two layer (NiCrAlY and ZrO2-12Y2O3) thermal-barrier coatings to aircraft gas turbine engine blade airfoils. The APS process hardware consists of four subsystems: a mechanical blade positioner incorporating two interlaced six-degree-of-freedom assemblies; a noncoherent optical metrology subsystem; a microprocessor-based adaptive system controller; and commercial plasma spray equipment. Over fifty JT9D first stage turbine blades specimens were coated with the APS process in preliminary checkout and evaluation studies. The best of the preliminary specimens achieved an overall coating thickness uniformity of + or - 53 micrometers, much better than is achievable manually. Factors limiting this performance were identified and process modifications were initiated accordingly. Comparative evaluations of coating thickness uniformity for manually sprayed and APS coated specimens were initiated. One of the preliminary evaluation specimens was subjected to a torch test and metallographic evaluation.

  8. 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.

  9. Low thermal expansion glass ceramics

    CERN Document Server

    1995-01-01

    This book is one of a series reporting on international research and development activities conducted by the Schott group of companies With the series, Schott aims to provide an overview of its activities for scientists, engineers, and managers from all branches of industry worldwide where glasses and glass ceramics are of interest Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated This volume describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization Thus glass ceramics with thermal c...

  10. On reactive suspension plasma spraying of calcium titanate

    Czech Academy of Sciences Publication Activity Database

    Kotlan, Jiří; Pala, Zdeněk; Mušálek, Radek; Ctibor, Pavel

    2016-01-01

    Roč. 42, č. 3 (2016), s. 4607-4615 ISSN 0272-8842 R&D Projects: GA ČR GA15-12145S Institutional support: RVO:61389021 Keywords : Suspensions * X-raymethods * Perovskites * Substrates * Suspension plasma spraying Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S0272884215022646

  11. Molybdenum disilicide composites produced by plasma spraying

    International Nuclear Information System (INIS)

    Castro, R.G.; Hollis, K.J.; Kung, H.H.; Bartlett, A.H.

    1998-01-01

    The intermetallic compound, molybdenum disilicide (MoSi 2 ) is being considered for high temperature structural applications because of its high melting point and superior oxidation resistance at elevated temperatures. The lack of high temperature strength, creep resistance and low temperature ductility has hindered its progress for structural applications. Plasma spraying of coatings and structural components of MoSi 2 -based composites offers an exciting processing alternative to conventional powder processing methods due to superior flexibility and the ability to tailor properties. Laminate, discontinuous and in situ reinforced composites have been produced with secondary reinforcements of Ta, Al 2 O 3 , SiC, Si 3 N 4 and Mo 5 Si 3 . Laminate composites, in particular, have been shown to improve the damage tolerance of MoSi 2 during high temperature melting operations. A review of research which as been performed at Los Alamos National Laboratory on plasma spraying of MoSi 2 -based composites to improve low temperature fracture toughness, thermal shock resistance, high temperature strength and creep resistance will be discussed

  12. Thermal Conductivity and Water Vapor Stability of Ceramic HfO2-Based Coating Materials

    Science.gov (United States)

    Zhu, Dong-Ming; Fox, Dennis S.; Bansal, Narottam P.; Miller, Robert A.

    2004-01-01

    HfO2-Y2O3 and La2Zr2O7 are candidate thermal/environmental barrier coating materials for gas turbine ceramic matrix composite (CMC) combustor liner applications because of their relatively low thermal conductivity and high temperature capability. In this paper, thermal conductivity and high temperature phase stability of plasma-sprayed coatings and/or hot-pressed HfO2-5mol%Y2O3, HfO2-15mol%Y2O3 and La2Zr2O7 were evaluated at temperatures up to 1700 C using a steady-state laser heat-flux technique. Sintering behavior of the plasma-sprayed coatings was determined by monitoring the thermal conductivity increases during a 20-hour test period at various temperatures. Durability and failure mechanisms of the HfO2-Y2O3 and La2Zr2O7 coatings on mullite/SiC Hexoloy or CMC substrates were investigated at 1650 C under thermal gradient cyclic conditions. Coating design and testing issues for the 1650 C thermal/environmental barrier coating applications will also be discussed.

  13. Low Thermal Expansion Glass Ceramics

    CERN Document Server

    Bach, Hans

    2005-01-01

    This book appears in the authoritative series reporting the international research and development activities conducted by the Schott group of companies. This series provides an overview of Schott's activities for scientists, engineers, and managers from all branches of industry worldwide in which glasses and glass ceramics are of interest. Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated. This new extended edition describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics. The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions. Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization. Thus g...

  14. Plasma sprayed alumina-titania coatings

    International Nuclear Information System (INIS)

    Steeper, T.J.; Rotolico, A.J.; Nerz, J.E.; Riggs, W.L. II; Varacalle, D.J. Jr.; Wilson, G.C.

    1992-01-01

    This paper presents an experimental study of the air plasma spraying (APS) of alumina-titania powder using argon-hydrogen working gases. This powder system is being used in the fabrication of heater tubes that emulate nuclear fuel tubes for use in thermal-hydraulic testing. Experiments were conducted using a Taguchi fractional-factorial design parametric study. Operating parameters were varied around the typical spray parameters in a systematic design of experiments in order to display the range of plasma processing conditions and their effect on the resultant coatings. The coatings were characterized by hardness and electrical tests, surface profilometry, image analysis, optical metallography, and x-ray diffraction. Coating qualities are discussed with respect to dielectric strength, hardness, porosity, surface roughness, deposition efficiency, and microstructure. attempts are made to correlate the features of the coatings with the changes in operating parameters

  15. Phase stabilization in plasma sprayed BaTiO3

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Seiner, Hanuš; Sedláček, J.; Pala, Zdeněk; Vaněk, Přemysl

    2013-01-01

    Roč. 39, č. 5 (2013), s. 5039-5048 ISSN 0272-8842 R&D Projects: GA ČR(CZ) GA101/09/0702 Institutional support: RVO:61389021 ; RVO:61388998 ; RVO:68378271 Keywords : Spectroscopy * BaTiO3 * Plasma spraying * Spark plasma sintering Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass; BJ - Thermodynamics (UT-L); JH - Ceramics, Fire-Resistant Materials and Glass (FZU-D) Impact factor: 2.086, year: 2013 http://www.sciencedirect.com/science/article/pii/S0272884212013582

  16. Plasma-Sprayed Fine-grained Zirconium Silicate and Its Dielectric Properties.

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Pala, Zdeněk; Nevrlá, Barbara; Neufuss, Karel

    2017-01-01

    Roč. 26, č. 5 (2017), s. 2388-2393 ISSN 1059-9495 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : electrical properties * insulators * plasma spraying * silica-substituted zirconia * zircon Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass OBOR OECD: Ceramics Impact factor: 1.331, year: 2016

  17. Dielectric properties and vacancy-like defects in plasma-sprayed barium titanate.

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Čížek, J.; Sedláček, J.; Lukáč, František

    2017-01-01

    Roč. 100, č. 7 (2017), s. 2972-2983 ISSN 0002-7820 Institutional support: RVO:61389021 Keywords : barium titanate * plasma spraying * vacancies Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass OBOR OECD: Ceramic s Impact factor: 2.841, year: 2016

  18. 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)

  19. Characterization of Plasma Sprayed Beryllium ITER First Wall Mockups

    International Nuclear Information System (INIS)

    Castro, Richard G.; Vaidya, Rajendra U.; Hollis, Kendall J.

    1997-10-01

    ITER first wall beryllium mockups, which were fabricated by vacuum plasma spraying the beryllium armor, have survived 3000 thermal fatigue cycles at 1 MW/sq m 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

  20. Lower-Conductivity Ceramic Materials for Thermal-Barrier Coatings

    Science.gov (United States)

    Bansal, Narottam P.; Zhu, Dongming

    2006-01-01

    Doped pyrochlore oxides of a type described below are under consideration as alternative materials for high-temperature thermal-barrier coatings (TBCs). In comparison with partially-yttria-stabilized zirconia (YSZ), which is the state-of-the-art TBC material now in commercial use, these doped pyrochlore oxides exhibit lower thermal conductivities, which could be exploited to obtain the following advantages: For a given difference in temperature between an outer coating surface and the coating/substrate interface, the coating could be thinner. Reductions in coating thicknesses could translate to reductions in weight of hot-section components of turbine engines (e.g., combustor liners, blades, and vanes) to which TBCs are typically applied. For a given coating thickness, the difference in temperature between the outer coating surface and the coating/substrate interface could be greater. For turbine engines, this could translate to higher operating temperatures, with consequent increases in efficiency and reductions in polluting emissions. TBCs are needed because the temperatures in some turbine-engine hot sections exceed the maximum temperatures that the substrate materials (superalloys, Si-based ceramics, and others) can withstand. YSZ TBCs are applied to engine components as thin layers by plasma spraying or electron-beam physical vapor deposition. During operation at higher temperatures, YSZ layers undergo sintering, which increases their thermal conductivities and thereby renders them less effective as TBCs. Moreover, the sintered YSZ TBCs are less tolerant of stress and strain and, hence, are less durable.

  1. Deposition of titanium nitride layers by electric arc – Reactive plasma spraying method

    International Nuclear Information System (INIS)

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

    2013-01-01

    Highlights: ► Titanium nitride layers deposited by electric arc – reactive plasma spraying method. ► Deposition of titanium nitride layers on C45 steel at different spraying distances. ► Characterization of the coatings hardness as function of the spraying distances. ► 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 2 N) and small amounts of Ti 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.

  2. Damping capacity and dynamic mechanical characteristics of the plasma-sprayed coatings

    International Nuclear Information System (INIS)

    Yu Liming; Ma Yue; Zhou Chungen; Xu Huibin

    2005-01-01

    The damping properties and dynamic mechanical performance of NiCrAlY coating, FeCrMo ferromagnetic coating, AlCuFeCr quasicrystalline coating and nanostructured ZrO 2 ceramic coating, which were prepared by plasma-spray method, were investigated. The measuring results of the dynamic mechanical thermal analyzer (DMTA) and the flexural resonance testing method show that the damping capacity (Q -1 ) of the coated sample has a notable improvement compared to the substrate, while the dynamic modulus has a dramatic decrease. The resonance frequency of the coated cantilever beam structure shifted to high-frequency, and the resonance amplitude, especially high mode resonance, was dramatically attenuated. The internal friction peaks were observed in the Q -1 -temperature spectrogram and a normal amplitude effects were shown in the coated samples damping characteristics. The damping mechanism based on the interaction between substrate and coating layer, and the microstructure of the coated sample were also discussed in this paper

  3. Ultrasonic technique for measuring porosity of plasma-sprayed alumina coatings

    Science.gov (United States)

    Parthasarathi, S.; Tittmann, B. R.; Onesto, E. J.

    1997-12-01

    Porosity is an important factor in plasma-sprayed coatings, especially ceramic coatings. Excessive poros-ity can adversely affect the performance of the coated component in various ways. An ultrasonic nonde-structive measurement technique has been developed to measure porosity in plasma-sprayed alumina coatings. The technique is generic and can be extended to other ceramic coating systems. To test the tech-nique, freestanding alumina coatings with varying levels of porosity were fabricated via plasma spray. Samples with varying porosity, obtained through innovative fabrication techniques, were used to gener-ate a calibration curve. The ultrasonic velocity in the low-frequency range was found to be dependent on the density of freestanding coatings (measured via Archimedian techniques). This dependence is the basis of the development of a technique to measure the density of coatings.

  4. Improved Metallography Of Thermal-Barrier Coatings

    Science.gov (United States)

    Brindley, William J.; Leonhardt, Todd A.

    1991-01-01

    New technique for preparation of metallographic samples makes interpretation of images of pores and microcracks more reliable. Involves use of vacuum epoxy infiltration and interference-film coating to reduce uncertainty. Developed for inspection of plasma-sprayed ceramic thermal-barrier coatings on metals but applicable to other porous, translucent materials, including many important ceramics.

  5. The development of beryllium plasma spray technology for the International Thermonuclear Experimental Reactor (ITER)

    International Nuclear Information System (INIS)

    Castro, R.G.; Elliott, K.E.; Hollis, K.J.; Watson, R.D.

    1999-01-01

    Over the past five years, four international parties, which include the European Communities, Japan, the Russian Federation and the United States, have been collaborating on the design and development of the International Thermonuclear Experimental Reactor (ITER), the next generation magnetic fusion energy device. During the ITER Engineering Design Activity (EDA), beryllium plasma spray technology was investigated by Los Alamos National Laboratory as a method for fabricating and repairing and the beryllium first wall surface of the ITER tokamak. Significant progress has been made in developing beryllium plasma spraying technology for this application. Information will be presented on the research performed to improve the thermal properties of plasma sprayed beryllium coatings and a method that was developed for cleaning and preparing the surface of beryllium prior to depositing plasma sprayed beryllium coatings. Results of high heat flux testing of the beryllium coatings using electron beam simulated ITER conditions will also be presented

  6. Heavy duty plasma spray gun

    International Nuclear Information System (INIS)

    Irons, G.C.; Klein, J.F.; Lander, R.D.; Thompson, H.C.; Trapani, R.D.

    1984-01-01

    A heavy duty plasma spray gun for extended industrial service is disclosed. The gun includes a gas distribution member made of a material having a coefficient of expansion different from that of the parts surrounding it. The gas distribution member is forcibly urged by a resilient member such as a coiled spring against a seal so as to assure the plasma gas is introduced into the gun arc in a manner only defined by the gas distribution member. The gun has liquid cooling for the nozzle (anode) and the cathode. Double seals are provided between the coolant and the arc region and a vent is provided between the seals which provides an indication when a seal has failed. Some parts of the gun are electrically isolated from others by an intermediate member which is formed as a sandwich of two rigid metal face pieces and an insulator disposed between them. The metal face pieces provide a rigid body to attach the remaining parts in proper alignment therewith

  7. Plasma spraying of zirconium carbide – hafnium carbide – tungsten cermets

    Czech Academy of Sciences Publication Activity Database

    Brožek, Vlastimil; Ctibor, Pavel; Cheong, D.-I.; Yang, S.-H.

    2009-01-01

    Roč. 9, č. 1 (2009), s. 49-64 ISSN 1335-8987 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma spraying * cermet coatings * microhardness * zirconium carbide * hafnium carbide * tungsten * water stabilized plasma Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  8. Structure and mechanical properties of plasma sprayed coatings of titania and alumina

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Boháč, Petr; Stranyánek, Martin; Čtvrtlík, Radim

    2006-01-01

    Roč. 26, č. 16 (2006), s. 3509-3514 ISSN 0955-2219 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z10100523 Keywords : Plasma spraying * Optical microscopy * Mechanical properties * TiO2 * Al2O3 Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.576, year: 2006

  9. PLASMA SPRAYING OF REFRACTORY CERMETS BY THE WATER-STABILIZED SPRAY (WSP®) SYSTEM

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Brožek, V.; Cheong, D.-I.; Chráska, Pavel

    2009-01-01

    Roč. 54, č. 3 (2009), s. 241-253 ISSN 0001-7043 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma spraying * cermet coatings * microhardness * zirconium carbide * tungsten Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  10. Vacuum-plasma-sprayed silicon coatings

    International Nuclear Information System (INIS)

    Varacalle, D.J. Jr.; Herman, H.; Bancke, G.A.; Burchell, T.D.; Romanoski, G.R.

    1991-01-01

    Vacuum plasma spraying produces well-bonded dense stress-free coatings for a variety of materials on a wide range of substrates. The process is used in many industries for the excellent wear, corrosion resistance and high temperature behavior of the fabricated coatings. In this study, silicon metal was deposited on graphite to study the feasibility of preventing corrosion and oxidation of graphite components for nuclear reactors. Operating parameters were varied in a Taguchi design of experiments to display the range of the plasma processing conditions and their effect on the measured coating characteristics. The coating attributes evaluated were thickness, porosity, microhardness and phase content. This paper discusses the influence of the processing parameters on as-sprayed coating qualities. The paper also discusses the effect of thermal cycling on silicon samples in an inert helium atmosphere. The diffraction spectrum for a sample that experienced a 1600degC temperature cycle indicated that more than 99% of the coating transformed to β-SiC. The silicon coatings protected the graphite substrates from oxidation in one experiment. (orig.)

  11. Thermomechanical processing of plasma sprayed intermetallic sheets

    Science.gov (United States)

    Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

    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.

  12. Air Plasma-Sprayed La2Zr2O7-SrZrO3 Composite Thermal Barrier Coating Subjected to CaO-MgO-Al2O3-SiO2 (CMAS)

    Science.gov (United States)

    Cai, Lili; Ma, Wen; Ma, Bole; Guo, Feng; Chen, Weidong; Dong, Hongying; Shuang, Yingchai

    2017-08-01

    La2Zr2O7-SrZrO3 composite thermal barrier coatings (TBCs) were prepared by air plasma spray (APS). The La2Zr2O7-SrZrO3 composite TBCs covered with calcium-magnesium-aluminum-silicate (CMAS) powder, as well as the powder mixture of CMAS and spray-dried La2Zr2O7-SrZrO3 composite powder, were heat-treated at 1250 °C in air for 1, 4, 8, and 12 h. The phase constituents and microstructures of the reaction products were characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. Experimental results showed that the La2Zr2O7-SrZrO3 composite TBCs had higher CMAS resistance than 8YSZ coating. A dense new layer developed between CMAS and La2Zr2O7-SrZrO3 composite TBCs during interaction, and this new layer consisted mostly of apatite (Ca2La8(SiO4)6O2) and c-ZrO2. The newly developed layer effectively protected the La2Zr2O7-SrZrO3 composite TBCs from further CMAS attack.

  13. Performance of ceramic coatings on diesel engines

    International Nuclear Information System (INIS)

    MacAdam, S.; Levy, A.

    1986-01-01

    Partially stabilized zirconia ceramic thermal barrier coatings were plasma sprayed on the valve faces and tulips and the piston crowns and cylinder heads of a locomotive size diesel engine at a designated thickness of 375μm (0.015''). They were tested over a range of throttle settings for 500 hours using No. 2 diesel oil fuel. Properly applied coatings performed with no change in composition, morphology or thickness. Improperly applied coatings underwent spalling durability was dependent on quality control of the plasma spray process

  14. The Influence of Nanodispersed Modifiers on the Structure and Properties of Plasma-Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Igor V. Smirnov

    2017-10-01

    Full Text Available Background. Currently, plasma-sprayed coatings are widely used to protect machine parts operating under conditions of high loads and temperatures, abrasive wear and exposure to corrosive media. Objective. The aim of the paper is to improve the physico-mechanical characteristics of plasma-sprayed coatings by modification of nano-sized particles of TiO2 oxides compounds. Methods. Experimental studies of corrosion resistance, microhardness, adhesion strength and residual stresses of plasma-sprayed coatings based on the oxide aluminum ceramic powder with the addition of nanodisperse TiO2 powder were conducted. Results. It is found that addition of TiO2 nanodisperse modifier to the oxide aluminum ceramic powder composition leads to corrosion resistance increase 2.8 times in a 10 % hydrochloric acid solution. The adhesive strength of ceramic nanomodified coatings is increased by 15–20 %. Conclusions. The positive influence of nanodispersed powders on the physico-mechanical and tribological characteristics of plasma-sprayed coatings is established.

  15. Plasma spray technology process parameters and applications

    International Nuclear Information System (INIS)

    Sreekumar, K.P.; Karthikeyan, J.; Ananthapadmanabhan, P.V.; Venkatramani, N.; Chatterjee, U.K.

    1991-01-01

    The current trend in the structural design philosophy is based on the use of substrate with the necessary mechanical properties and a thin coating to exhibit surface properties. Plasma spray process is a versatile surface coating technique which finds extensive application in meeting advance technologies. This report describes the plasma spray technique and its use in developing coatings for various applications. The spray system is desribed in detail including the different variables such as power input to the torch, gas flow rate, powder properties, powder injection, etc. and their interrelation in deciding the quality of the coating. A brief write-up on the various plasma spray coatings developed for different applications is also included. (author). 15 refs., 15 figs., 2 tabs

  16. Process development for synthesis and plasma spray deposition of LaPO4 and YPO4 for nuclear applications

    International Nuclear Information System (INIS)

    Chakravarthy, Y.; Sreekumar, K.P.; Jayakumar, S.; Thiyagarajan, T.K.; Ananthapadmanabhan, P.V.; Das, A.K.; Gantayet, L.M.; Krishnan, K.

    2009-01-01

    Rare earth phosphates are geologically very stable and considered as potential matrix material for nuclear waste disposal and also for many high temperature thermal barrier and corrosion barrier applications involving molten metals. This paper focuses on developmental studies related to synthesis, thermal stability and plasma spray deposition of LaPO 4 and YPO 4 . The rare earth phosphates were synthesized by chemical method from their respective oxide materials using ortho phosphoric acid. The as-precipitated powders were converted to thermal spray grade powder by compaction, sintering and crushing. Thermal stability of these phosphates up to their melting point was determined by arc plasma melting, followed by X-ray diffraction. Results indicate that LaPO 4 and YPO 4 melt congruently without decomposition. Plasma spray deposition was carried out using the in-house 40 kW atmospheric plasma spray system. Adherent coatings could be deposited on various substrates by optimizing the plasma spray parameters. (author)

  17. Measurement of residual stress in plasma-sprayed composite coatings with graded and uniform compositions

    Energy Technology Data Exchange (ETDEWEB)

    Kesler, O.; Suresh, S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Matejicek, J.; Sampath, S.

    1999-10-01

    Residual stresses in plasma sprayed composite coatings were studied experimentally by both curvature and neutron diffraction measurements. Graded and uniform composite coatings, consisting of nickel + alumina and NiCrAlY + yttria-stabilized zirconia, were investigated. This paper briefly summarizes our recent work dealing with the effects of coating thickness, composition, and material properties on the evolution of residual stresses in coatings. Analysis of the results allowed in some cases the separation of the quenching stress and thermal stress contributions to the final residual stress, as well as the determination of the through-thickness stress profile from measurements of different thickness specimens. In the ceramic-metal composites, it was found that the thermal mismatch stress plays a dominant role in the ceramic phase, whereas the stress in the metallic phase is mostly dominated by quenching stress. The residual stress measurement methods employed here were found to be complementary, in that each can provide unique information about the stress state. Through-thickness stress profiles in graded coatings were determined with high spatial resolution by the curvature method, and determination of the stress in each separate phase of a composite was made by neutron diffraction. (orig.) 14 refs.

  18. 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

  19. Mechanical Properties of Plasma Sprayed Alumina Coatings

    Czech Academy of Sciences Publication Activity Database

    Kovářík, O.; Nohava, Jiří; Siegel, J.

    2003-01-01

    Roč. 48, č. 2 (2003), s. 129-145 ISSN 0001-7043 R&D Projects: GA ČR GA106/01/0094 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma sprayed alumina coatings, fatigue test, metalography, fractography, residual stress, microhardness, Young's modulus , four-point bending Subject RIV: BL - Plasma and Gas Discharge Physics

  20. Thermal stability of double-ceramic-layer thermal barrier coatings with various coating thickness

    International Nuclear Information System (INIS)

    Dai Hui; Zhong Xinghua; Li Jiayan; Zhang Yanfei; Meng Jian; Cao Xueqiang

    2006-01-01

    Double-ceramic-layer (DCL) coatings with various thickness ratios composed of YSZ (6-8 wt.% Y 2 O 3 + ZrO 2 ) and lanthanum zirconate (LZ, La 2 Zr 2 O 7 ) were produced by the atmospheric plasma spraying. Chemical stability of LZ in contact with YSZ in DCL coatings was investigated by calcining powder blends at different temperatures. No obvious reaction was observed when the calcination temperature was lower than 1250 deg. C, implying that LZ and YSZ had good chemical applicability for producing DCL coating. The thermal cycling test indicate that the cycling lives of the DCL coatings are strongly dependent on the thickness ratio of LZ and YSZ, and the coatings with YSZ thickness between 150 and 200 μm have even longer lives than the single-layer YSZ coating. When the YSZ layer is thinner than 100 μm, the DCL coatings failed in the LZ layer close to the interface of YSZ layer and LZ layer. For the coatings with the YSZ thickness above 150 μm, the failure mainly occurs at the interface of the YSZ layer and the bond coat

  1. Scratch and wear behaviour of plasma sprayed nano ceramics bilayer Al2O3-13 wt%TiO2/hydroxyapatite coated on medical grade titanium substrates in SBF environment

    Science.gov (United States)

    Palanivelu, R.; Ruban Kumar, A.

    2014-10-01

    Among the various coating techniques, plasma spray coating is an efficient technique to protect the metal surface from the various surface problems like wear and corrosion. The aim of this present work is to design and produce a bilayer coating on the non- toxic commercially pure titanium (denoted as CP-Ti) implant substrate in order to improve the biocompatibility and surface properties. To achieve that, Al2O3-13 wt%TiO2 (AT13) and hydroxyapatite (HAP) were coated on CP-Ti implant substrate using plasma spray coating technique. Further, the coated substrates were subjected to various characterization techniques. The crystallite size of coated HAP and its morphological studies were carried out using X-ray diffractometer (XRD) and scanning electron microscopy (SEM) respectively. The wear test on the bilayer (AT13/HAP) coated CP-Ti implant surface was conducted using ball-on-disc tester under SBF environment at 37 °C, in order to determine the wear rate and the coefficient of friction. The adhesion strength of the bilayer coated surface was evaluated by micro scratch tester under the ramp load conditions with load range of 14-20 N. The above said studies were repeated on the single layer coated HAP and AT13 implant surfaces. The results reveal that the bilayer (AT13/HAP) coated CP-Ti surface has the improved wear rate, coefficient of friction in compared to single layer coated HAP and AT13 surfaces.

  2. Effect of Bauxite addition on Adhesion Strength and Surface Roughness of Fly ash based Plasma Sprayed Coatings

    Science.gov (United States)

    Bhuyan, S. K.; Samal, S.; Pattnaik, D.; Sahu, A.; Swain, B.; Thiyagarajan, T. K.; Mishra, S. C.

    2018-03-01

    The environment is being contaminated with advancement of new technology, day by day. One of the primary sources for this contamination is the industrial waste. Industrialization is the prime reason behind the prosperity of any country to meet the materialistic demand. To run the industries, a huge amount of (electric) power is needed and hence need for thermal power plants to serve the purpose. In present scenario, coal fired thermal power plants are set up which generates a huge quantity of Fly ash. Consumption of industrial waste (Fly ash), continually a major concern for human race. In recent years, fly ash is being utilized for various purposes i.e. making bricks, mine reclamation, production of cements etc. The presence of Silica and Alumina in fly ash makes it useful for thermal barrier applications also. The plasma spray technology has the advantage of being able to process any types of metal/ceramic mineral, low-grade-ore minerals etc. to make value-added products and also to deposit ceramics, metals and a combination of these to deposit composite coatings with desired microstructure and required properties on a range of substrate materials. The present work focuses on utilization of fly ash mixing with bauxite (ore mineral) for a high valued application. Fly ash with 10 and 20% bauxite addition is used to deposit plasma spray overlay coatings at different power levels (10-20kW) on aluminum and mild steel substrates. Adhesion strength and surface roughness of the coatings are evaluated. Phase composition analysis of the coatings were done using X-ray diffraction analysis. Surface morphology of the coatings was studied using a scanning electron microscope (SEM). Maximum adhesion strength of 4.924 MPa is obtained for the composition fly ash and bauxite (10%), coated on mild steel at 16kW torch power level. The surface roughness (Ra) of the coatings is found to vary between 10.0102 to 17.2341 micron.

  3. Application of plasma sprayed ceramic coatings to the base materials of the rotating disk in the centrifugal atomization process. Enshinryoku funmuho ni okeru kaiten enban eno ceramic yosha himaku no tekiyo

    Energy Technology Data Exchange (ETDEWEB)

    Sato, T; Okimoto, K [Government Industrial Research Inst., Kyushu, Tosu, Saga (Japan); Yasutake, R [Koeiseiko Co. Ltd., Fukuoka (Japan)

    1992-07-08

    Applicability of the ceramic coating on the rotating disk was studied. In regard to the synthesis of Cu-based rapidly solidified powders, centrifugal atomization with molten Cu-24.6Sn was carried out using rotating disks sprayed with four kinds of sprayed ceramic coatings. It was found that atomization of Al203-40%TiO2 sprayed coating has been the best, and the yield ratio has been about 60 %. The melt temperature in case of Fe-based rapidly solidified metal powders, has risen above 1600[degree]C, and the required conditions for rotating disk have been very difficult to meet. The reason for it is thought that there has also been limitations regarding the functions of the characteristics like heat transfer, heat capacity, etc. Fe-24Cr-5Ni-1Mo 2 phase stainless steel powder has shown the most suitable trend among the seven kinds of disk materials examined for ZrO2 ceramic sprayed coatings. 6 refs., 5 figs., 2 tabs.

  4. 3D-simulation of residual stresses in TBC plasma sprayed coating

    International Nuclear Information System (INIS)

    Kundas, S.; Kashko, T.; Hurevich, V.E.; Lugscheider, E.; Hayn, G. von; Ilyuschenko, A.

    2001-01-01

    Thermal barrier coatings (TBC) are used in gas turbine technology in order to protect against overheating of the nickel alloy turbine blades. This coatings allows to increase turbine inlet temperatures and improve their efficiency. Plasma spraying processes are widely used since several years in thermal barrier coating technology. Although the plasma spraying process of TBC's is largely successful, a fundamental understanding of the process parameters influencing the TBC microstructure and mechanical properties is necessary. But this investigation has received much less attention so they could lead to considerable advances in performance of plasma sprayed thermal barrier coatings. The main reason of this mate is difficulties in experimental investigation of high temperature and high velocity process. One of the most effective ways to accelerate the process optimization is the application of computer simulation for the modeling of plasma spraying. This enables the achievement of a maximum of information about the investigated process by carrying out a minimum number of experiments. The main problem of plasma spray TBC coatings is crack information during the deposition process and coating cooling. The reasons for this are quenched and residual stresses in the coating-substrate system, and peculiarities of TBC coating properties. The problem of deposition and solidification of plasma sprayed coatings have received little attention to date and remains one of the unintelligible parts of process. A fundamental understanding of heat transfer in the coating-substrate system and particles deformation processes are, however, critical for the prediction of the microstructural characteristics of the deposited coatings, the understanding of the mechanisms involved in formation of thermal stresses and defects (cracks, debonding etc.). (author)

  5. The dissociation of NZP (Ca{sub 0.5}Sr{sub 0.5}Zr{sub 4}P{sub 6}O{sub 24}) during plasma spraying[Sodium Zirconium Phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Trice, R.W.; Brewer, L.N.; Faber, K.T.

    2000-04-01

    Sodium zirconium phosphate (NaZr{sub 2}P{sub 3}O{sub 12} or NZP) was first systematically evaluated in the early 1980s by Roy and co-workers, who demonstrated its extremely low coefficient of thermal expansion (CTE). It was later shown that other group IA and IIA atoms can be ionically substituted into the NZP crystal structure to adjust the CTE. As a result of their low and tailorable CTEs, NZP's have potential use as a protective coating for silicon-based ceramics and carbon-carbon composites. One technique for the application of ceramic coatings employs plasma-spraying. In this process, powders are injected into a plasma flame, melted, and propelled onto a substrate. The resulting coating microstructure is typically composed of thin lamellae (from each melted particle) stacked on top of one another during each pass of the torch. In the current research, NZP has been plasma-sprayed using the recently patented small particle plasma-spray process. The microstructure was then analyzed using transmission electron microscopy and x-ray diffraction to identify the phases in the complex coating that resulted.

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

    International Nuclear Information System (INIS)

    Hou, Qing Yu; Luo, Lai Ma; Huang, Zhen Yi; Wang, Ping; Ding, Ting Ting; Wu, Yu Cheng

    2016-01-01

    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.

  7. Simulation of thermo-Elastics Properties of Thermal Barrier Coatings ...

    African Journals Online (AJOL)

    Thermal barrier coatings are used to protect different parts in compressors and turbines from heat. They are generally composed of two layers, one metallic layer providing resistance to heat corrosion and oxidation, and one thermally insulating ceramic layer. Two different techniques are industrially used. Plasma spray ...

  8. Improved methods for testing bond and intrinsic strength and fatigue of thermally sprayed metallic and ceramic coatings

    International Nuclear Information System (INIS)

    Schweitzer, K.K.; Ziehl, M.H.; Schwaminger, C.

    1991-01-01

    Conventional bond strength tests for thermally sprayed coatings represent only a rough means of obtaining overall strength values, with no differentiation between adhesion at the interface and intrinsic coating properties. In order to obtain information about the influence of substrate surface preparation on the adhesion of a Tribaloy T700 coating, tensile bond strength and modified crack-opening displacement (COD) specimens were tested by deliberate crack initiation at the interface. Crack initiation was achieved by weakening of the interface at the outer diameter in the case of bond strength specimens or at the notch root in the case of COD specimens. This made it possible to look at the influence of surface roughness and grit contamination on the coating adhesion separately. Modified COD specimens with the notch in the centre of the coating were used to determine crack-opening energies and critical stress intensity factors of atmospheric plasma-sprayed NiAl and low pressure plasma-sprayed CoNiCrAlY bond coatings and a ZrO 2 7Y 2 O 3 thermal barrier coating (TBC). Additionally, bond strength specimens were stressed dynamically, and it could be demonstrated that Woehler (S/N) diagrams can be established for a metallic NiAl bond coating and even for a ceramic ZrO 2 7Y 2 O 3 TBC. (orig.)

  9. Thermal analysis simulation for a spin-motor used in the advanced main combustion chamber vacuum plasma spray project using the SINDA computer program

    Science.gov (United States)

    Mcdonald, Gary H.

    1990-01-01

    One of the many design challenges of this project is predicting the thermal effects due to the environment inside the vacuum chamber on the turntable and spin motor spindle assembly. The objective of the study is to model the spin motor using the computer program System Improved Numerical Differencing Analyzer (SINDA). By formulating the appropriate input information concerning the motor's geometry, coolant flow path, material composition, and bearing and motor winding characteristics, SINDA should predict temperatures at various predefined nodes. From these temperatures, hopefully, one can predict if the coolant flow rate is sufficient or if certain mechanical elements such as bearings, O ring seals, or motor windings will exceed maximum design temperatures.

  10. Characterization of plasma sprayed NiCrAlY-Yttria stabilized zirconia coatings

    International Nuclear Information System (INIS)

    Bhave, V.S.; Rakhasia, R.H.; Tripathy, P.K.; Hubli, R.C.; Sengupta, P.; Bhanumurthy; Satpute, R.U.; Sreekumar, K.P.; Thiyagarajan, T.K.; Padmanabhan, P.V.A.

    2004-01-01

    Plasma sprayed coatings of yttria stabilized zirconia are used in many advanced technologies for thermal and chemical barrier applications. Development and characterization of NiCrAlY-yttria stabilized zirconia duplex coatings on Inconel substrates is reported in this paper. Plasma spraying was carried out using the 40 kW atmospheric plasma spray facility at the Laser and Plasma Technology Division, BARC. A bond coat of NiCrAlY was deposited on Inconel substrates and yttria stabilized zirconia (YSZ) was deposited over the bond coat. The coatings have been characterized by x-ray diffraction and EPMA. It is observed that the coating characteristics are affected by the input power to the torch. (author)

  11. 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.

  12. Metastable phases in yttrium oxide plasma spray deposits and their effect on coating properties

    International Nuclear Information System (INIS)

    Gourlaouen, V.; Schnedecker, G.; Boncoeur, M.; Lejus, A.M.; Collongues, R.

    1993-01-01

    Yttrium oxide coatings were obtained by plasma spray. Structural investigations on these deposits show that, due to the drastic conditions of this technique, a minor monoclinic B phase is formed in the neighborhood of the major cubic C form. The authors discuss here the influence of different plasma spray parameters on the amount of the B phase formed. They describe also the main properties of Y 2 O 3 B and C phases in these deposits such as structural characteristics, thermal stability and mechanical behavior

  13. Scratch and wear behaviour of plasma sprayed nano ceramics bilayer Al2O3-13 wt%TiO2/hydroxyapatite coated on medical grade titanium substrates in SBF environment

    International Nuclear Information System (INIS)

    Palanivelu, R.; Ruban Kumar, A.

    2014-01-01

    Graphical abstract: - Highlights: • Hydroxyapatite was synthesized by sol–gel route. • Bilayer (AT13/HAP) coating improves wear resistance of CP-Ti implant surface. • The microhardness values of bilayer coating surface were increased 4 times compared to uncoated sample surface. - Abstract: Among the various coating techniques, plasma spray coating is an efficient technique to protect the metal surface from the various surface problems like wear and corrosion. The aim of this present work is to design and produce a bilayer coating on the non- toxic commercially pure titanium (denoted as CP-Ti) implant substrate in order to improve the biocompatibility and surface properties. To achieve that, Al 2 O 3 -13 wt%TiO 2 (AT13) and hydroxyapatite (HAP) were coated on CP-Ti implant substrate using plasma spray coating technique. Further, the coated substrates were subjected to various characterization techniques. The crystallite size of coated HAP and its morphological studies were carried out using X-ray diffractometer (XRD) and scanning electron microscopy (SEM) respectively. The wear test on the bilayer (AT13/HAP) coated CP-Ti implant surface was conducted using ball-on-disc tester under SBF environment at 37 °C, in order to determine the wear rate and the coefficient of friction. The adhesion strength of the bilayer coated surface was evaluated by micro scratch tester under the ramp load conditions with load range of 14–20 N. The above said studies were repeated on the single layer coated HAP and AT13 implant surfaces. The results reveal that the bilayer (AT13/HAP) coated CP-Ti surface has the improved wear rate, coefficient of friction in compared to single layer coated HAP and AT13 surfaces

  14. Scratch and wear behaviour of plasma sprayed nano ceramics bilayer Al{sub 2}O{sub 3}-13 wt%TiO{sub 2}/hydroxyapatite coated on medical grade titanium substrates in SBF environment

    Energy Technology Data Exchange (ETDEWEB)

    Palanivelu, R.; Ruban Kumar, A., E-mail: arubankumarvit@gmail.com

    2014-10-01

    Graphical abstract: - Highlights: • Hydroxyapatite was synthesized by sol–gel route. • Bilayer (AT13/HAP) coating improves wear resistance of CP-Ti implant surface. • The microhardness values of bilayer coating surface were increased 4 times compared to uncoated sample surface. - Abstract: Among the various coating techniques, plasma spray coating is an efficient technique to protect the metal surface from the various surface problems like wear and corrosion. The aim of this present work is to design and produce a bilayer coating on the non- toxic commercially pure titanium (denoted as CP-Ti) implant substrate in order to improve the biocompatibility and surface properties. To achieve that, Al{sub 2}O{sub 3}-13 wt%TiO{sub 2} (AT13) and hydroxyapatite (HAP) were coated on CP-Ti implant substrate using plasma spray coating technique. Further, the coated substrates were subjected to various characterization techniques. The crystallite size of coated HAP and its morphological studies were carried out using X-ray diffractometer (XRD) and scanning electron microscopy (SEM) respectively. The wear test on the bilayer (AT13/HAP) coated CP-Ti implant surface was conducted using ball-on-disc tester under SBF environment at 37 °C, in order to determine the wear rate and the coefficient of friction. The adhesion strength of the bilayer coated surface was evaluated by micro scratch tester under the ramp load conditions with load range of 14–20 N. The above said studies were repeated on the single layer coated HAP and AT13 implant surfaces. The results reveal that the bilayer (AT13/HAP) coated CP-Ti surface has the improved wear rate, coefficient of friction in compared to single layer coated HAP and AT13 surfaces.

  15. Sintering of Fine Particles in Suspension Plasma Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Leszek Latka

    2010-07-01

    plasma spraying. The formation of necks having the relative size equal to 10% of particle diameter was found to be possible during the thermal cycles occurring at the coatings’ deposition. Transmission electron microscopic observations of the agglomerated zone hydroxyapatite coating confirm the sintering of some of the fine grains.

  16. Radio frequency induction plasma spraying of molybdenum

    International Nuclear Information System (INIS)

    Jiang Xianliang

    2003-01-01

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

  17. Thermal Gradient Cyclic Behavior of a Thermal/Environmental Barrier Coating System on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Lee, Kang N.; Miller, Robert A.

    2002-01-01

    Thermal barrier and environmental barrier coatings (TBCs and EBCs) will play a crucial role in future advanced gas turbine engines because of their ability to significantly extend the temperature capability of the ceramic matrix composite (CMC) engine components in harsh combustion environments. In order to develop high performance, robust coating systems for effective thermal and environmental protection of the engine components, appropriate test approaches for evaluating the critical coating properties must be established. In this paper, a laser high-heat-flux, thermal gradient approach for testing the coatings will be described. Thermal cyclic behavior of plasma-sprayed coating systems, consisting of ZrO2-8wt%Y2O3 thermal barrier and NASA Enabling Propulsion Materials (EPM) Program developed mullite+BSAS/Si type environmental barrier coatings on SiC/SiC ceramic matrix composites, was investigated under thermal gradients using the laser heat-flux rig in conjunction with the furnace thermal cyclic tests in water-vapor environments. The coating sintering and interface damage were assessed by monitoring the real-time thermal conductivity changes during the laser heat-flux tests and by examining the microstructural changes after the tests. The coating failure mechanisms are discussed based on the cyclic test results and are correlated to the sintering, creep, and thermal stress behavior under simulated engine temperature and heat flux conditions.

  18. Plasma sprayed coatings on mild steel split moulds for uranium casting

    International Nuclear Information System (INIS)

    Sreekumar, K.P.; Padmanaban, P.V.A.; Venkatramani, N.; Singh, S.P.; Saha, D.P.; Date, V.G.

    2002-01-01

    High velocity high temperature plasma jets are used to deposit metals and ceramics on metallic substrates for oxidation and corrosion protection applications. Plasma sprayed ceramic coatings on metallic substrates are also used to prevent its reaction with molten metals. Metal-alumina duplex coatings on mild steel split moulds have been developed and successfully used for casting of uranium. Techno-economics of the coated moulds against the conventional graphite moulds are a major advantage. Mild steel moulds of 600 mm long and 75 mm in diameter have been plasma spray coated with alumina over a bond coat of molybdenum. In-plant tests showed an increase in number of castings per mould compared to the commonly used graphite moulds. (author)

  19. Automatic targeting of plasma spray gun

    International Nuclear Information System (INIS)

    Abbatiello, L.A.; Neal, R.E.

    1978-01-01

    A means for monitoring the material portion in the flame of a plasma spray gun during spraying operations is described. A collimated detector, sensitive to certain wavelengths of light emission, is used to locate the centroid of the material with each pass of the gun. The response from the detector is then relayed to the gun controller to be used to automatically realign the gun

  20. Plasma spraying of cerium-doped YAG

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Kubát, J.; Pala, Zdeněk; Nevrlá, Barbara

    2014-01-01

    Roč. 29, č. 19 (2014), s. 2344-2351 ISSN 0884-2914 R&D Projects: GA ČR(CZ) GAP108/12/1872 Institutional support: RVO:61389021 Keywords : plasma spraying * water-stabilized plasma Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.647, year: 2014 http://dx.doi.org/10.1557/jmr.2014.251

  1. Automatic targeting of plasma spray gun

    Science.gov (United States)

    Abbatiello, Leonard A.; Neal, Richard E.

    1978-01-01

    A means for monitoring the material portion in the flame of a plasma spray gun during spraying operations is provided. A collimated detector, sensitive to certain wavelengths of light emission, is used to locate the centroid of the material with each pass of the gun. The response from the detector is then relayed to the gun controller to be used to automatically realign the gun.

  2. Development of Process for Plasma Spray:Case Study for Molybdenum

    Czech Academy of Sciences Publication Activity Database

    Sampath, S.; Jiang, X.; Kulkarni, A.; Matějíček, Jiří; Gilmore, D. L.; Neiser, R. A.

    2003-01-01

    Roč. 348, 1-2 (2003), s. 54-66 ISSN 0921-5093 Grant - others:NSF(US) DMR9632570 Institutional research plan: CEZ:AV0Z2043910 Keywords : process maps, plasma spray, thermal spray Subject RIV: JG - Metallurgy Impact factor: 1.365, year: 2003

  3. 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.

  4. Structure and properties of plasma sprayed BaTiO3 coatings

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Ageorges, H.; Sedláček, J.; Čtvrtlík, Radim

    2010-01-01

    Roč. 36, č. 7 (2010), s. 2155-2162 ISSN 0272-8842 R&D Projects: GA AV ČR KAN301370701 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z10100522 Keywords : Cermet * plasma spraying * microstructure * elastic modulus * wear resistance Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.471, year: 2010

  5. Plasma Spraying and Characterization of Chromium Carbide-Nickel Chromium Coatings

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Prantnerová, M.

    2016-01-01

    Roč. 9, č. 4 (2016), s. 281-290, č. článku PCCC-2016-09-16-339. ISSN 2008-2134 Institutional support: RVO:61389021 Keywords : Plasma spraying * Chromium carbide * Slurry abrasion * Dry rubber wheel test * Friction * Microhardness Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass http://www.pccc.icrc.ac.ir/?xid=0113010121000001804&id=976

  6. Study on the plasma sprayed amorphous diopside and annealed fine-grained crystalline diopside

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Nevrlá, Barbara; Pala, Zdeněk; Sedláček, J.; Soumar, J.; Kubatík, Tomáš František; Neufuss, Karel; Vilémová, Monika; Medřický, Jan

    2015-01-01

    Roč. 41, č. 9 (2015), s. 10578-10586 ISSN 0272-8842 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : Dielectric properties * Plasma spraying * Diopside * Annealing Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.758, year: 2015 http://www.sciencedirect.com/science/article/pii/S027288421500913X#

  7. Microstructural Analysis and Transport Properties of Thermally Sprayed Multiple-Layer Ceramic Coatings

    Science.gov (United States)

    Wang, Hsin; Muralidharan, Govindarajan; Leonard, Donovan N.; Haynes, J. Allen; Porter, Wallace D.; England, Roger D.; Hays, Michael; Dwivedi, Gopal; Sampath, Sanjay

    2018-02-01

    Multilayer, graded ceramic/metal coatings were prepared by an air plasma spray method on Ti-6Al-4V, 4140 steel and graphite substrates. The coatings were designed to provide thermal barriers for diesel engine pistons to operate at higher temperatures with improved thermal efficiency and cleaner emissions. A systematic, progressive variation in the mixture of yttria-stabilized zirconia and bondcoat alloys (NiCoCrAlYHfSi) was designed to provide better thermal expansion match with the substrate and to improve thermal shock resistance and cycle life. Heat transfer through the layers was evaluated by a flash diffusivity technique based on a model of one-dimensional heat flow. The aging effect of the as-sprayed coatings was captured during diffusivity measurements, which included one heating and cooling cycle. The hysteresis of thermal diffusivity due to aging was not observed after 100-h annealing at 800 °C. The measurements of coatings on substrate and freestanding coatings allowed the influence of interface resistance to be evaluated. The microstructure of the multilayer coating was examined using scanning electron microscope and electron probe microanalysis.

  8. An evaluation of the electric arc spray and (HPPS) processes for the manufacturing of high power plasma spraying MCrAIY coatings

    Science.gov (United States)

    Sacriste, D.; Goubot, N.; Dhers, J.; Ducos, M.; Vardelle, A.

    2001-06-01

    The high power plasma torch (PlazJet) can be used to spray refractory ceramics with high spray rates and deposition efficiency. It can provide dense and hard coating with high bond strengths. When manufacturing thermal barrier coatings, the PlazJet gun is well adapted to spraying the ceramic top coat but not the MCrAIY materials that are used as bond coat. Arc spraying can compete with plasma spraying for metallic coatings since cored wires can be used to spray alloys and composites. In addition, the high production rate of arc spraying enables a significant decrease in coating cost. This paper discusses the performances of the PlazJet gun, and a twin-wire are spray system, and compares the properties and cost of MCrAIY coatings made with these two processes. For arc spraying, the use of air or nitrogen as atomizing gas is also investigated.

  9. Dielectric and electrochemical properties through-thickness mapping on extremely thick plasma sprayed TiO2

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Sedláček, J.; Pala, Zdeněk

    2016-01-01

    Roč. 42, č. 6 (2016), s. 7183-7191 ISSN 0272-8842 Institutional support: RVO:61389021 Keywords : Electrical properties * TiO2 * Plasma spraying * Annealing * Microstructure Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S0272884216001395

  10. IMPROVEMENT OF MECHANICAL PROPERTIES OF ALUMINA AND ZIRCONIA PLASMA SPRAYED COATINGS INDUCED BY LASER POST-TREATMENT

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Kraus, L.; Tuominen, J.; Vuoristo, P.; Chráska, Pavel

    2007-01-01

    Roč. 51, č. 4 (2007), s. 181-189 ISSN 0862-5468 R&D Projects: GA AV ČR 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : Alumina * plasma spraying * wear resistance * slurry abrasion Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.488, year: 2007

  11. Hot corrosion of the ceramic composite coating Ni{sub 3}Al-Al{sub 2}O{sub 3}-Al{sub 2}O{sub 3}/MgO plasma sprayed on 316L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Shirazi, Amir Khodaparast; Kiahosseini, Seyed Rahim [Islamic Azad Univ., Damghan (Iran, Islamic Republic of). Dept. of Engineering

    2017-08-15

    Ni{sub 3}Al-Al{sub 2}O{sub 3}-Al{sub 2}O{sub 3}/MgO three-layered coatings with thicknesses of 50, 100, and 150 μm for Al{sub 2}O{sub 3}/MgO and 100 μm for the other layers were deposited on 316L stainless steel using plasma spraying. X-ray diffraction, atomic force microscopy, furnace hot corrosion testing in the presence of a mixture of Na{sub 2}SO{sub 4} and V{sub 2}O{sub 5} corrosive salts and scanning electron microscopy were used to determine the structural, morphological and hot corrosion resistance of samples. Results revealed that the crystalline grains of MgO and Al{sub 2}O{sub 3} coating were very small. Weight loss due to hot corrosion decreased from approximately 4.267 g for 316L stainless steel without coating to 2.058 g. The samples with 150 μm outer coating showed improved resistance with the increase in outer layer thickness. Scanning electron microscopy of the coated surface revealed that the coating's resistance to hot corrosion is related to the thickness and the grain size of Al{sub 2}O{sub 3}/MgO coatings.

  12. 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.

  13. 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.

  14. Cavitation Erosion of Plasma -sprayed Coatings

    International Nuclear Information System (INIS)

    Kim, J. J.; Park, J. S.; Jeon, S. B.

    1991-01-01

    Tungsten Carbide, chromium carbide and chromium oxide coatings were obtained on a 304 stainless steel substrate by plasma spraying technique. The coated samples were exposed to cavitation generated in distilled water by a 20KHz ultrasonic horn. The results of investigation reveal that all the samples tested are significantly eroded even within ten minutes of exposure, indicative of a short incubation period. The eroded surfaces can be characterized as having large pits and flat smooth areas. The latter may be associated with the poor cohesive strength of the coatings, which leads to the failures between individual lamellae

  15. Photocatalytic activity of visible-light-active iron-doped coatings prepared by plasma spraying

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Pala, Zdeněk; Štengl, Václav; Mušálek, Radek

    2014-01-01

    Roč. 40, č. 1 (2014), s. 2365-2372 ISSN 0272-8842 R&D Projects: GA AV ČR IAAX00430803 Institutional support: RVO:61389021 ; RVO:61388980 Keywords : Spectroscopy * Bandgap * Plasma spraying * Photocatalysis * TiO2–Fe2O3 Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass; JH - Ceramics, Fire-Resistant Materials and Glass (UACH-T) Impact factor: 2.605, year: 2014 http://www. sci encedirect.com/ sci ence/article/pii/S0272884213009541#

  16. Fabrication of MgAl2O4 spinel/niobium laminar composites by plasma spraying

    International Nuclear Information System (INIS)

    Boncoeur, M.; Lochet, N.; Miomandre, F.; Schnedecker, G.

    1994-01-01

    The feasibility of plasma spray manufacturing of laminar ceramic matrix composites made of alternate thin layers of a ceramic oxide and a metal is demonstrated with a composite made of 7 layers, each 0.2 mm thick, of MgAl 2 O 4 spinel and niobium. Microstructure and mechanical characteristics have been studied with both as-sprayed and heat-treated under vacuum at 1400 C conditions. It is shown that the as-sprayed composite is brittle but becomes pseudo-plastic after heat treatment. These laminar composites are very attractive for the manufacturing of large surface, few millimeter thick components. (from authors). 4 figs., 4 refs

  17. Preparation and in vitro evaluation of plasma-sprayed bioactive akermanite coatings

    International Nuclear Information System (INIS)

    Yi, Deliang; Wu, Chengtie; Chang, Jiang; Ma, Xubing; Ji, Heng; Zheng, Xuebin

    2012-01-01

    Bioactive ceramic coatings on titanium (Ti) alloys play an important role in orthopedic applications. In this study, akermanite (Ca 2 MgSi 2 O 7 ) bioactive coatings are prepared through a plasma spraying technique. The bonding strength between the coatings and Ti-6Al-4V substrates is around 38.7–42.2 MPa, which is higher than that of plasma sprayed hydroxyapatite (HA) coatings reported previously. The prepared akermanite coatings reveal a distinct apatite-mineralization ability in simulated body fluid. Furthermore, akermanite coatings support the attachment and proliferation of rabbit bone marrow mesenchymal stem cells (BMSCs). The proliferation rate of BMSCs on akermanite coatings is obviously higher than that on HA coatings. (paper)

  18. Building ceramics with improved thermal insulation parameters

    Directory of Open Access Journals (Sweden)

    Rzepa Karol

    2016-01-01

    Full Text Available One of the most important performance characteristics of masonry units is their high thermal insulation. There are many different ways to improve this parameter, however the most popular methods in case of ceramic masonry units are: addition of pore-creating raw materials and application of proper hole pattern. This study was an attempt to improve thermal insulation of ceramics by applying thermal insulation additives. Perlite dust created as a subgrain from expansion of perlite rock was used. Perlite subgrain is not very popular among consumers, that’s why it’s subjected to granulation to obtain coarse grain. The authors presented concept of direct application of perlite dust for the production of building ceramics with improved thermal insulation. Fineness of this additive is asset for molding of ceramic materials from plastic masses. Based on the results it was found that about 70% perlite by volume can be added to obtain material with a coefficient of heat conductivity of 0,37 W/mK. Higher content of this additive in ceramic mass causes deterioration of its rheological properties. Mass loses its plasticity, it tears up and formed green bodies are susceptible to deformation. During sintering perlite takes an active part in compaction process. Higher sintering dynamics is caused by: high content of alkali oxides in perlite and glass nature of perlite. Alkali oxides generate creation of liquid phase which intensifies mass compaction processes. Active role of perlite in sintering process causes good connection of its grains with clay groundwork which is important factor for mechanical parameters of ceramic materials. It was also noted that addition of perlite above 40% by volume of mass effectively neutralized negative effect of efflorescence in ceramic materials.

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

    International Nuclear Information System (INIS)

    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 Al 2 O 3 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

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

    International Nuclear Information System (INIS)

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

    1995-01-01

    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 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 2

  1. Application of sol gel spin coated yttria-stabilized zirconia layers for the improvement of solid oxide fuel cell electrolytes produced by atmospheric plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Lars [University of British Columbia, Department of Materials Engineering, 309-6350 Stores Road, Vancouver, British Columbia, V6T 1Z4 (Canada); National Research Council, Institute for Fuel Cell Innovation, 4250 Wesbrook Mall, Vancouver, British Columbia, V6T 1W5 (Canada); Kesler, Olivera [National Research Council, Institute for Fuel Cell Innovation, 4250 Wesbrook Mall, Vancouver, British Columbia, V6T 1W5 (Canada); University of British Columbia, Department of Mechanical Engineering, 2054-6250 Applied Science Lane, Vancouver, British Columbia, V6T 1Z4 (Canada); Tang, Zhaolin; Burgess, Alan [Northwest Mettech Corp., 467 Mountain Hwy, North Vancouver, British Columbia, V7J 2L3 (Canada)

    2007-05-15

    Due to its high thermal stability and purely oxide ionic conductivity, yttria-stabilized zirconia (YSZ) is the most commonly used electrolyte material for solid oxide fuel cells (SOFCs). Standard electrolyte fabrication techniques for planar SOFCs involve wet ceramic techniques such as tape-casting or screen printing, requiring sintering steps at temperatures above 1300 C. Plasma spraying (PS) may provide a more rapid and cost efficient method to produce SOFCs without sintering. High-temperature sintering requires long processing times and can lead to oxidation of metal alloys used as mechanical supports, or to detrimental interreactions between the electrolyte and adjacent electrode layers. This study investigates the use of spin coated sol gel derived YSZ precursor solutions to fill the pores present in plasma sprayed YSZ layers, and to enhance the surface area for reaction at the electrolyte-cathode interface, without the use of high-temperature firing steps. The effects of different plasma conditions and sol concentrations and solid loadings on the gas permeability and fuel cell performance have been investigated. (author)

  2. 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.

  3. In situ SANS study of pore microstructure in YSZ thermal barrier coatings

    Czech Academy of Sciences Publication Activity Database

    Strunz, Pavel; Schumacher, G.; Vassen, R.; Wiedenmann, A.

    2004-01-01

    Roč. 52, č. 11 (2004), s. 3305-3312 ISSN 1359-6454 R&D Projects: GA ČR GA202/03/0891 Institutional research plan: CEZ:AV0Z1048901 Keywords : plasma spraying * thermal barrier coatings * ceramics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.490, year: 2004

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

    International Nuclear Information System (INIS)

    Jiang Xianliang

    2002-01-01

    nano-crystalline powders of ω(Al 2 O 3 ) = 95%, ω(TiO 2 ) = 3%, and ω(SiO 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) μm. 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 lower microhardness than conventional microstructured coatings, the toughness of the nano-structured ceramic coatings is significantly improved

  5. Scratch induced failure of plasma sprayed alumina based coatings

    International Nuclear Information System (INIS)

    Hazra, S; Bandyopadhyay, P.P.

    2012-01-01

    Highlights: ► Scratch induced failure of alumina based coatings including nanostructured is reported. ► Ceramic is deposited on bond coat instead of steel, emulating a realistic situation. ► Lateral force data is supplemented with microscopy to observe coating failure. ► The failure mechanism during scratching has been identified. ► Critical load of failure has been calculated for each bond-top coat combination. -- Abstract: A set of plasma sprayed coatings were obtained from three alumina based top coat and two bond coat powders. Scratch test was undertaken on these coatings, under constant and linearly varying load. Test results include the lateral force data and scanning electron microscope (SEM) images. Failure occurred by large area spallation of the top coat and in most cases tensile cracks appeared on the exposed bond coat. The lateral force showed an increasing trend with an increase in normal load up to a certain point and beyond this, it assumed a steady average value. The locations of coating spallation and occurrence of maximum lateral force did not coincide. A bond coat did not show a significant role in determining the scratch adhesion strength.

  6. Development of Ceramic Coating on Metal Substrate using Industrial Waste and Ore Minerals

    Science.gov (United States)

    Bhuyan, S. K.; Thiyagarajan, T. K.; Mishra, S. C.

    2017-02-01

    The technological advancement in modern era has a boon for enlightening human life; but also is a bane to produce a huge amount of (industrial) wastes, which is of great concern for utilization and not to create environmental threats viz. polution etc. In the present piece of research work, attempts have been made to utilize fly ash (wastes of thermal power plants) and along with alumina bearing ore i.e. bauxite, for developing plasma spray ceramic coatings on metals. Fly ash and with 10 and 20% bauxite addition is used to deposit plasma spray coatings on a metal substrate. The surface morphology of the coatings deposited at different power levels of plasma spraying investigated through SEM and EDS analysis. The coating thickness is measured. The porosity levels of the coatings are evaluated. The coating hardness isalso measured. This piece of research work will be beneficial for future development and use of industrial waste and ore minerals for high-valued applications.

  7. Plasma sprayed TiC coatings for first wall protection in fusion devices

    International Nuclear Information System (INIS)

    Groot, P.; Laan, J.G. van der; Laas, L.; Mack, M.; Dvorak, M.

    1989-01-01

    For protection of plasma facing components in nuclear fusion devices thick titanium carbide coatings are being developed. Coatings have been produced by plasma spraying at atmospheric pressure (APS) and low pressure (LPPS) and analyzed with respect to microstructure and chemical composition. Thermo-mechanical evaluation has been performed by applying short pulse laser heat flux tests. The influence of coating thickness and porosity on the resistance to spalling by thermal shocks appears to be more important than aspects of chemical composition. (author)

  8. Temperature dependence of bending strength for plasma sprayed zirconia coating; Plasuma yosha zirconia himaku no magetsuyosa no ondo izonsei

    Energy Technology Data Exchange (ETDEWEB)

    Arai, M.; Sakuma, T. [Central Research Inst. of Electric Power Industry, Tokyo (Japan)] Mizutani, T. [Tokyo Inst. of Tech. (Japan)] Kishimoto, K. [Tokyo Inst. of Tech. (Japan). Faculty of Engineering] Saito, M. [Toshiba Corp. (Japan). Heavy Apparatus Engineering Lab.

    1998-02-01

    Plasma sprayed zirconia applying to the thermal barrier coating in gas turbine has been developing for protecting the hot parts such as blades and nozzles from high-temperature enviroments. In this paper, four point bending tests under various temperature conditions are conducted on plasma sprayed zirconia and its mechanical properties are examined. Results show that the bending strength at room temperature for plasma sprayed zirconia is much lower than that of sintered zirconia and is decreased with the increase in temperature. However, Weibull modulus at each temperature is relatively large and the dispersion of bending strength is very small in comparison with that of sintered zirconia. It is also clarified by the SEM observations of fracture surface that many defects such as debonding and microcrack are responsible for the lower bending strength. 9 refs., 8 figs., 1 tab.

  9. Erosion protection of carbon-epoxy composites by plasma-sprayed coatings

    International Nuclear Information System (INIS)

    Alonso, F.; Fagoaga, I.; Oregui, P.

    1991-01-01

    This paper deals with the production of plasma-sprayed erosion-resistant coatings on carbon-fibre - epoxy composites, and the study of their erosion behaviour. The heat sensitivity of the composite substrate requires a specific spraying procedure in order to avoid its degradation. In addition, several bonding layers were studied to allow spraying of the protective coatings. Two different functional coatings were sprayed onto an aluminium-glass bonding layer, a WC-12Co cermet and an Al 2 O 3 ceramic oxide. The microstructure and properties of these coatings were studied and their erosion behaviour determined experimentally in an erosion-testing device. (orig.)

  10. 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)

  11. Prediction of thermal fatigue life of ceramics

    International Nuclear Information System (INIS)

    Kamiya, N.; Kamigaito, O.

    1979-01-01

    On the assumption that the thermal fatigue life of ceramics is determined mainly by the duration over which a crack reaches a small critical length, a prediction of the life was made by application of fracture mechanics to ceramics based on subcritical crack growth. Approximated formulae were derived. Experimental examination showed that the formulae proved to be valid for glass, sintered mullite under moderate shock severity, and zirconia. Data given by other authors also prove their validity. The deviation of the life from the formulae for sintered mullite under a thermal shock of extremely low severty, suggests that a certain mechanism, for example strengthening, is needed to understand the life of the sintered mullite. (author)

  12. Thermophysical properties of YSZ and YCeSZ suspension plasma sprayed coatings having different microstructures

    Czech Academy of Sciences Publication Activity Database

    Sokołowski, P.; Björklund, S.; Mušálek, Radek; Candidato, Jr., R.T.; Pawłowski, L.; Nait-Ali, B.; Smith, D.

    2017-01-01

    Roč. 318, May (2017), s. 28-38 ISSN 0257-8972. [International Meeting on Thermal Spraying (RIPT)/7./. Limoges, 09.12.2015-11.12.2015] R&D Projects: GA ČR GA15-12145S Institutional support: RVO:61389021 Keywords : Thermal Barrier Coatings (TBC) * Suspension Plasma Spraying * Thermal conductivity * Specific heat * Thermal dilatation * Response function method Subject RIV: JK - Corrosion ; Surface Treatment of Materials OBOR OECD: Coating and films Impact factor: 2.589, year: 2016 http://www.sciencedirect.com/science/article/pii/S0257897217302086

  13. Plasma spraying of hard magnetic coatings based on Sm-Co alloys

    International Nuclear Information System (INIS)

    KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F. Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Saunin, V N; KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" data-affiliation=" (Siberian State Aerospace University named after Academician M.F. Reshetnev 31 KrasnoyarskiyRabochiy prospect, Krasnoyarsk, 660014 (Russian Federation))" >Telegin, S V

    2015-01-01

    Our research is focused on the formation of hard magnetic coatings by plasma spraying an arc-melted Sm-Co powder. We have studied basic magnetic characteristics depending on the components ratio in the alloy. A sample with a 40 wt.% Sm coating exhibits the highest coercive force (63 kOe) as compared to near-to-zero coercive force in the starting powder. X-ray structure analysis of the starting alloy and the coating reveals that the amount of SmCo 5 phase in the sprayed coating increases occupying up to 2/3 of the sample. We have also studied temperature dependence of the coating and have been able to obtain plasma sprayed permanent magnets operating within the temperature range from -100 to +500 °C. The technique used does not involve any additional thermal treatment and allows a coating to be formed right on the magnetic conductor surface irrespective of the conductor geometry

  14. Model of the macrostructure formation of plasma sprayed coatings

    International Nuclear Information System (INIS)

    Gnedovets, A.G.; Kalita, V.I.

    2007-01-01

    A 3D discrete ballistic model of plasma sprayed coatings structure formation is presented. The effect of a spraying angle on porous macrostructure of coatings is investigated by numerical computations.Computer simulation results as well as experimental data show that at a sputtering angle less than 45 deg the mechanism of surface relief formation is changed and the relief consists of valleys and ridges under such conditions of plasma spraying [ru

  15. Plasma sprayed Nd-Fe-B permanent magnets

    International Nuclear Information System (INIS)

    Willson, M.; Bauser, S.; Liu, S.; Huang, M.

    2003-01-01

    This study demonstrated that the plasma spray deposition method is an alternative process for producing Nd-Fe-B magnets in addition to the two existing principal processes: the powder metallurgy process for producing sintered Nd-Fe-B magnets and the melt spinning process for bonded Nd-Fe-B magnets. Plasma spray is a potentially better process for producing magnetic parts with complicated shape, large area, thin thickness, small dimension, or unusual geometry. High intrinsic coercivity greater than 15 kOe was readily obtained for Nd 16 Dy 1 Fe 76 B 7 even in the as-deposited condition when the substrate was preheated. The plasma spray process contains only three steps: melting, crushing, and plasma spray, which is much simpler than the powder metallurgy and melt spinning processes. Without preheating the substrate, the coercivity was usually very low (∼0.1 kOe) in the as-deposited condition and it increased to 10 to >15 kOe after anneal. Evidence of magnetocrystalline anisotropy was observed in plasma sprayed Nd 15 Dy 1 Fe 77 B 7 magnets when the substrate was not preheated. It is believed that a crystal texture was developed during the plasma spray as a result of the existence of a temperature gradient in the solidifying melt

  16. Characterizing Suspension Plasma Spray Coating Formation Dynamics through Curvature Measurements

    Science.gov (United States)

    Chidambaram Seshadri, Ramachandran; Dwivedi, Gopal; Viswanathan, Vaishak; Sampath, Sanjay

    2016-12-01

    Suspension plasma spraying (SPS) enables the production of variety of microstructures with unique mechanical and thermal properties. In SPS, a liquid carrier (ethanol/water) is used to transport the sub-micrometric feedstock into the plasma jet. Considering complex deposition dynamics of SPS technique, there is a need to better understand the relationships among spray conditions, ensuing particle behavior, deposition stress evolution and resultant properties. In this study, submicron yttria-stabilized zirconia particles suspended in ethanol were sprayed using a cascaded arc plasma torch. The stresses generated during the deposition of the layers (termed evolving stress) were monitored via the change in curvature of the substrate measured using an in situ measurement apparatus. Depending on the deposition conditions, coating microstructures ranged from feathery porous to dense/cracked deposits. The evolving stresses and modulus were correlated with the observed microstructures and visualized via process maps. Post-deposition bi-layer curvature measurement via low temperature thermal cycling was carried out to quantify the thermo-elastic response of different coatings. Lastly, preliminary data on furnace cycle durability of different coating microstructures were evaluated. This integrated study involving in situ diagnostics and ex situ characterization along with process maps provides a framework to describe coating formation mechanisms, process parametrics and microstructure description.

  17. Structure and properties of plasma sprayed BaTiO(3) coatings: Spray parameters versus structure and photocatalytic activity

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Ageorges, H.; Štengl, Václav; Murafa, Nataliya; Píš, I.; Zahoranová, T.; Nehasil, V.; Pala, Zdeněk

    2011-01-01

    Roč. 37, č. 7 (2011), s. 2561-2567 ISSN 0272-8842 R&D Projects: GA AV ČR IAAX00430803 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z40320502 Keywords : Spectroscopy * Optical properties * BaTiO3 * Plasma spraying * Photocatalysis Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.751, year: 2011 http://www.sciencedirect.com/science/article/pii/S0272884211002173

  18. 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.

  19. Advanced Microstructural Study of Suspension Plasma Sprayed Hydroxyapatite Coatings

    Science.gov (United States)

    Podlesak, Harry; Pawlowski, Lech; D'Haese, Romain; Laureyns, Jacky; Lampke, Thomas; Bellayer, Severine

    2010-03-01

    Fine, home-synthesized, hydroxyapatite powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto a titanium substrate. The deposition process was optimized using statistical design of 2 n experiments with two variables: spray distance and electric power input to plasma. X-ray diffraction (XRD) was used to determine quantitatively the phase composition of obtained deposits. Raman microscopy and electron probe microanalysis (EPMA) enabled localization of the phases in different positions of the coating cross sections. Transmission electron microscopic (TEM) study associated with energy-dispersive x-ray spectroscopy (EDS) enabled visualization and analysis of a two-zone microstructure. One zone contained crystals of hydroxyapatite, tetracalcium phosphate, and a phase rich in calcium oxide. This zone included lamellas, usually observed in thermally sprayed coatings. The other zone contained fine hydroxyapatite grains that correspond to nanometric and submicrometric solids from the suspension that were agglomerated and sintered in the cold regions of plasma jet and on the substrate.

  20. Filter media properties of mineral fibres produced by plasma spray.

    Science.gov (United States)

    Prasauskas, Tadas; Matulevicius, Jonas; Kliucininkas, Linas; Krugly, Edvinas; Valincius, Vitas; Martuzevicius, Dainius

    2016-01-01

    The purpose of this study was to determine the properties of fibrous gas filtration media produced from mineral zeolite. Fibres were generated by direct current plasma spray. The paper characterizes morphology, chemical composition, geometrical structure of elementary fibres, and thermal resistance, as well as the filtration properties of fibre media. The diameter of the produced elementary fibres ranged from 0.17 to 0.90 μm and the length ranged from 0.025 to 5.1 mm. The release of fibres from the media in the air stream was noticed, but it was minimized by hot-pressing the formed fibre mats. The fibres kept their properties up to the temperature of 956°C, while further increase in temperature resulted in the filter media becoming shrunk and brittle. The filtration efficiency of the prepared filter mats ranged from 95.34% to 99.99% for aerosol particles ranging in a size between 0.03 and 10.0 μm. Unprocessed fibre media showed the highest filtration efficiency when filtering aerosol particles smaller than 0.1 µm. Hot-pressed filters were characterized by the highest quality factor values, ranging from 0.021 to 0.064 Pa(-1) (average value 0.034 Pa(-1)).

  1. Systematic Investigation on the Influence of Spray Parameters on the Mechanical Properties of Atmospheric Plasma-Sprayed YSZ Coatings

    Science.gov (United States)

    Mutter, Markus; Mauer, Georg; Mücke, Robert; Guillon, Olivier; Vaßen, Robert

    2018-04-01

    In the atmospheric plasma spray (APS) process, micro-sized ceramic powder is injected into a thermal plasma where it is rapidly heated and propelled toward the substrate. The coating formation is characterized by the subsequent impingement of a large number of more or less molten particles forming the so-called splats and eventually the coating. In this study, a systematic investigation on the influence of selected spray parameters on the coating microstructure and the coating properties was conducted. The investigation thereby comprised the coating porosity, the elastic modulus, and the residual stress evolution within the coating. The melting status of the particles at the impingement on the substrate in combination with the substrate surface condition is crucial for the coating formation. Single splats were collected on mirror-polished substrates for selected spray conditions and evaluated by identifying different types of splats (ideal, distorted, weakly bonded, and partially molten) and their relative fractions. In a previous study, these splat types were evaluated in terms of their effect on the above-mentioned coating properties. The particle melting status, which serves as a measure for the particle spreading behavior, was determined by in-flight particle temperature measurements and correlated to the coating properties. It was found that the gun power and the spray distance have a strong effect on the investigated coating properties, whereas the feed rate and the cooling show minor influence.

  2. Phase transition stability within ceramics

    International Nuclear Information System (INIS)

    Wang, E.; Wang, D.

    1992-01-01

    Irreversible thermodynamics is applied to analyse nucleation, both in metals and ceramics, in order to distinguish the stability of metastable under cooled melts. The hypothesis of local equilibrium has been used to apply research results from equilibrium thermodynamics, for the study of irreversible processes. The under cooling equation for homogenous nucleation only depends on a coefficient which is not related to the melting point of the material. The calculated critical under cooling values for metals are compared with experimental data. The metastable phase formation of plasma-sprayed alumina and zircon coatings has been discussed based on irreversible thermodynamics. A critical under cooling parameter (β) is defined. The metastable phase formation of plasma-sprayed alumina and zircon has been discussed. The analysis shows that γ-Al 2 O 3 is first formed in the coating since it has a lower β value than α-Al 2 O 3 . Zircon dissociates into ZrO 2 and SiO 2 , and rapid quenching of plasma spraying prevents their re association. The cooling rate determines whether t-ZrO 2 or c-ZrO 2 will form in the sprayed coating. It can be confirmed by the experiments that the content of t-ZrO 2 will increase correspondingly as the sprayed particle size decreases. At high transition temperatures, c-ZrO 2 will be formed because of the anisotropic thermal expansion behaviour in the crystal structure. 22 refs., 2 tabs

  3. Thermal barrier coatings - Technology for diesel engines

    International Nuclear Information System (INIS)

    Harris, D.H.; Lutz, J.

    1988-01-01

    Thermal Barrier Coatings (TBC) are a development of the aerospace industry primarily aimed at hot gas flow paths in turbine engines. TBC consists of zirconia ceramic coatings applied over (M)CrAlY. These coatings can provide three benefits: (1) a reduction of metal surface operating temperatures, (2) a deterrent to hot gas corrosion, and (3) improved thermal efficiencies. TBC brings these same benefits to reciprocal diesel engines but coating longevity must be demonstrated. Diesels require thicker deposits and have challenging geometries for the arc-plasma spray (APS) deposition process. Different approaches to plasma spraying TBC are required for diesels, especially where peripheral edge effects play a major role. Bondcoats and ceramic top coats are modified to provide extended life as determined by burner rig tests, using ferrous and aluminum substrates

  4. Reduction in thermal conductivity of ceramics due to radiation damage

    International Nuclear Information System (INIS)

    Klemens, P.G.; Hurley, G.F.; Clinard, F.W. Jr.

    1976-01-01

    Ceramics are required for a number of applications in fusion reactors. In several of these applications, the thermal conductivity is an important design parameter as it affects the level of temperature and thermal stress in service. Ceramic insulators are known to suffer substantial reduction in thermal conductivity due to neutron irradiation damage. The present study estimates the reduction in thermal conductivity at high temperature due to radiation induced defects. Point, extended, and extended partly transparent defects are considered

  5. Deposition of porous cathodes using plasma spray technique for reduced-temperature SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Jankovic, J.; Hui, S.; Roller, J.; Kesler, O.; Xie, Y.; Maric, R.; Ghosh, D. [National Research Council of Canada, Vancouver, BC (Canada). Inst. for Fuel Cell Innovation

    2005-07-01

    Current techniques for Solid Oxide Fuel Cell (SOFC) materials deposition are often expensive and time-consuming. Plasma-spraying techniques provide higher deposition rates, short processing times and control over porosity and composition during deposition. Optimum plasma spraying for lanthanum based cathode materials were discussed. Plasma-spraying was used to deposit cathode materials onto ceramic and stainless steel substrates to obtain highly porous structures. Lanthanum cathode materials with composition of La{sub 0.6}Sr{sub 0.4}C{sub 0.2}Fe{sub 0.8}O{sub 3} were employed in the powder form. The powder was prepared from powder precursors with different power formers and binder levels, or from produced single-phase lanthanum powders. The (La{sub 0.8}Sr{sub 0.2}){sub 0.98}MnO{sub 3} cathode material was also processed for comparison purposes. The deposition process was developed to obtain coatings with good bond strength, porosity, film thickness and residual stresses. The phase and microstructure of deposited materials were characterized using X-Ray Diffraction and Scanning Electron Microscopy (SEM). It was concluded that good flow of the powder precursors is achieved by spraying 50-100 um particle size powders and using vibrating feeders. Further processing of the spraying powders was recommended. It was noted that oxide precursors showed greater reactivity among the precursors. The best precursor reactivity and coating morphology was obtained using 40 volume per cent of graphite pore former, incorporated into the precursor mixture during wet ball milling. It was concluded that higher power levels and larger distances between the plasma gun and the substrate result in coatings with the highest porosities and best phase compositions. 5 refs., 1 tab., 6 figs.

  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. Plasma sprayed and electrospark deposited zirconium metal diffusion barrier coatings

    International Nuclear Information System (INIS)

    Hollis, Kendall J.; Pena, Maria I.

    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.

  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. Sea water Corrosion of Nickel based Plasma Spray Coating

    Science.gov (United States)

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

    2018-03-01

    Different types of erosion resistant coatings are applied/deposited on aero components, depending on the operating/working temperatures. Nickel based coating are applied on the air craft (compressor) components, which can sustain up to working temperature of 650°C. In the present investigation, to improve the compatibility between substrate (i.e. the machine component) and the top coat, application of bond coat is there. The application of Nickel based coating by thermal plasma spray technique has proven to be a satisfactory means of producing acceptable sealing surface with excellent abradability. Before the corrosion study, coated sample is subjected to hardness, thickness and porosity testing. Hence the result is being evaluated. The corrosion behavior of coating was studied by sea water immersion with a time period of 16 weeks. It is observed that, up to 9 weeks increase in weight of coating occurs in a sharp trend and then takes a decreasing trend. The weight gain of the samples has varied from 37.23% (with one week immersion in sea water) to a maximum of about 64.36% for six weeks immersion. Coating morphology and composition analysis of the coatings are studied using SEM and EDS. This behavior shows adsorption/deposition of the foreign particles with polygonal shape on the coating surface by sea water interaction. Foreign particles with polygonal shape deposited on the coating and with increase in immersion/treatment time, washing out of the deposited materials starts, which reflects the decreasing trend of weight gain of the specimen.

  10. Fatigue life of layered metallic and ceramic plasma sprayed coatings

    Czech Academy of Sciences Publication Activity Database

    Kovářík, O.; Haušild, P.; Siegl, J.; Matějíček, Jiří; Davydov, V.

    2014-01-01

    Roč. 3, July (2014), s. 586-591 ISSN 2211-8128. [European Conference on Fracture (ECF20)/20./. Trondheim, 30.06.2014-04.07.2014] R&D Projects: GA ČR(CZ) GAP108/12/1872 Institutional support: RVO:61389021 Keywords : functionally graded materials * fatigue life * neutron diffraction * grit blasting Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://www.sciencedirect.com/science/article/pii/S2211812814000984#

  11. In situ carbon nanotube reinforcements in a plasma-sprayed aluminum oxide nanocomposite coating

    International Nuclear Information System (INIS)

    Balani, K.; Zhang, T.; Karakoti, A.; Li, W.Z.; Seal, S.; Agarwal, A.

    2008-01-01

    Carbon nanotubes (CNT) are potential reinforcements for toughening the ceramic matrix. The critical issue of avoiding CNT agglomeration and introducing CNT-matrix anchoring has challenged many researchers to improve the mechanical properties of the CNT reinforced nanocomposite. In the current work, dispersed CNTs are grown on Al 2 O 3 powder particles in situ by the catalytic chemical vapor deposition (CCVD) technique. Consequently, 0.5 wt.% CNT-reinforced Al 2 O 3 particles were successfully plasma sprayed to obtain a 400 μm thick coating on the steel substrate. In situ CNTs grown on Al 2 O 3 shows a promising enhancement in hardness and fracture toughness of the plasma-sprayed coating attributed to the existence of strong metallurgical bonding between Al 2 O 3 particles and CNTs. In addition, CNT tentacles have imparted multi-directional reinforcement in securing the Al 2 O 3 splats. High-resolution transmission electron microscopy shows interfacial fusion between Al 2 O 3 and CNT and the formation of Y-junction nanotubes

  12. Hydrogen permeation properties of plasma-sprayed tungsten

    International Nuclear Information System (INIS)

    Anderl, R.A.; Pawelko, R.J.; Hankins, M.R.; Longhurst, G.R.; Neiser, R.A.

    1994-01-01

    Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D + 3 ion beam with fluxes of similar 6.5x10 19 D/m 2 s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity. ((orig.))

  13. Hydrogen permeation properties of plasma-sprayed tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Anderl, R.A. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Pawelko, R.J. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Hankins, M.R. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Longhurst, G.R. (Idaho National Engineering Lab., EG and G Idaho Inc., Idaho Falls, ID (United States)); Neiser, R.A. (Sandia National Laboratories, Albuquerque, NM 87185 (United States))

    1994-09-01

    Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D[sup +][sub 3] ion beam with fluxes of similar 6.5x10[sup 19] D/m[sup 2] s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity. ((orig.))

  14. Hydrogen permeation properties of plasma-sprayed tungsten*1

    Science.gov (United States)

    Anderl, R. A.; Pawelko, R. J.; Hankins, M. R.; Longhurst, G. R.; Neiser, R. A.

    1994-09-01

    Tungsten has been proposed as a plasma-facing component material for advanced fusion facilities. This paper reports on laboratory-scale studies that were done to assess the hydrogen permeation properties of plasma-sprayed tungsten for such applications. The work entailed deuterium permeation measurements for plasma-sprayed (PS) tungsten coatings, sputter-deposited (SP) tungsten coatings, and steel substrate material using a mass-analyzed, 3 keV D 3+ ion beam with fluxes of ˜6.5 × 10 19 D/m 2 s. Extensive characterization analyses for the plasma-sprayed tungsten coatings were made using Auger spectrometry and scanning electron microscopy (SEM). Observed permeation rates through composite PS-tungsten/steel specimens were several orders of magnitude below the permeation levels observed for SP-tungsten/steel composite specimens and pure steel specimens. Characterization analyses indicated that the plasma-sprayed tungsten coating had a nonhomogeneous microstructure that consisted of splats with columnar solidification, partially-melted particles with grain boundaries, and void regions. Reduced permeation levels can be attributed to the complex microstructure and a substantial surface-connected porosity.

  15. 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.

  16. 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.

  17. Dielectric properties of plasma sprayed silicates subjected to additional annealing

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Sedláček, J.; Nevrlá, Barbara; Neufuss, Karel

    2017-01-01

    Roč. 10, č. 2 (2017), s. 105-114 ISSN 2008-2134 Institutional support: RVO:61389021 Keywords : Annealing * Dielectric properties * Plasma spraying * Silicates * Electrical properties * Insulators Subject RIV: JK - Corrosion ; Surface Treatment of Materials OBOR OECD: Coating and films http://pccc.icrc.ac.ir/Articles/1/18/990/

  18. Thermal Property Engineering: Exploiting the Properties of Ceramic Nanocomposites

    Science.gov (United States)

    2018-03-01

    ARL-TR-8308 ● MAR 2018 US Army Research Laboratory Thermal Property Engineering : Exploiting the Properties of Ceramic...return it to the originator. ARL-TR-8308 ● MAR 2018 US Army Research Laboratory Thermal Property Engineering : Exploiting the...2015 – Dec 31 2017 4. TITLE AND SUBTITLE Thermal Property Engineering : Exploiting the Properties of Ceramic Nanocomposites 5a. CONTRACT NUMBER 5b

  19. Microstructure and mechanical properties of plasma sprayed HA/YSZ/Ti-6Al-4V composite coatings.

    Science.gov (United States)

    Khor, K A; Gu, Y W; Pan, D; Cheang, P

    2004-08-01

    Plasma sprayed hydroxyapatite (HA) coatings on titanium alloy substrate have been used extensively due to their excellent biocompatibility and osteoconductivity. However, the erratic bond strength between HA and Ti alloy has raised concern over the long-term reliability of the implant. In this paper, HA/yttria stabilized zirconia (YSZ)/Ti-6Al-4V composite coatings that possess superior mechanical properties to conventional plasma sprayed HA coatings were developed. Ti-6Al-4V powders coated with fine YSZ and HA particles were prepared through a unique ceramic slurry mixing method. The so-formed composite powder was employed as feedstock for plasma spraying of the HA/YSZ/Ti-6Al-4V coatings. The influence of net plasma energy, plasma spray standoff distance, and post-spray heat treatment on microstructure, phase composition and mechanical properties were investigated. Results showed that coatings prepared with the optimum plasma sprayed condition showed a well-defined splat structure. HA/YSZ/Ti-6Al-4V solid solution was formed during plasma spraying which was beneficial for the improvement of mechanical properties. There was no evidence of Ti oxidation from the successful processing of YSZ and HA coated Ti-6Al-4V composite powders. Small amount of CaO apart from HA, ZrO(2) and Ti was present in the composite coatings. The microhardness, Young's modulus, fracture toughness, and bond strength increased significantly with the addition of YSZ. Post-spray heat treatment at 600 degrees C and 700 degrees C for up to 12h was found to further improve the mechanical properties of coatings. After the post-spray heat treatment, 17.6% increment in Young's modulus (E) and 16.3% increment in Vicker's hardness were achieved. The strengthening mechanisms of HA/YSZ/Ti-6Al-4V composite coatings were related to the dispersion strengthening by homogeneous distribution of YSZ particles in the matrix, the good mechanical properties of Ti-6Al-4V and the formation of solid solution among HA

  20. The Influence of Anode Inner Contour on Atmospheric DC Plasma Spraying Process

    Directory of Open Access Journals (Sweden)

    Kui Wen

    2017-01-01

    Full Text Available In thermal plasma spraying process, anode nozzle is one of the most important components of plasma torch. Its inner contour controls the characteristics of plasma arc/jet, determining the motion and heating behaviors of the in-flight particles and hence influencing the coating quality. In this study, the effects of anode inner contour, standard cylindrical nozzle, and cone-shaped Laval nozzle with conical shape diverging exit (CSL nozzle on the arc voltage, net power, thermal efficiency, plasma jet characteristics, in-flight particle behaviors, and coating properties have been systematically investigated under atmospheric plasma spraying conditions. The results show that the cylindrical nozzle has a higher arc voltage, net power, and thermal efficiency, as well as the higher plasma temperature and velocity at the torch exit, while the CSL nozzle has a higher measured temperature of plasma jet. The variation trends of the plasma jet characteristics for the two nozzles are comparable under various spraying parameters. The in-flight particle with smaller velocity of CSL nozzle has a higher measured temperature and melting fraction. As a result, the coating density and adhesive strength of CSL nozzle are lower than those of cylindrical nozzle, but the deposition efficiency is greatly improved.

  1. Tribological Behavior of Plasma-Sprayed Al2O3-20 wt.%TiO2 Coating

    Science.gov (United States)

    Cui, Shiyu; Miao, Qiang; Liang, Wenping; Zhang, Zhigang; Xu, Yi; Ren, Beilei

    2017-05-01

    Al2O3-20 wt.% TiO2 ceramic coatings were deposited on the surface of Grade D steel by plasma spraying of commercially available powders. The phases and the microstructures of the coatings were investigated by x-ray diffraction and scanning electron microscopy, respectively. The Al2O3-20 wt.% TiO2 composite coating exhibited a typical inter-lamellar structure consisting of the γ-Al2O3 and the Al2TiO5 phases. The dry sliding wear behavior of the coating was examined at 20 °C using a ball-on-disk wear tester. The plasma-sprayed coating showed a low wear rate ( 4.5 × 10-6 mm3 N-1 m-1), which was matrix ( 283.3 × 10-6 mm3 N-1 m-1), under a load of 15 N. In addition, the tribological behavior of the plasma-sprayed coating was analyzed by examining the microstructure after the wear tests. It was found that delamination of the Al2TiO5 phase was the main cause of the wear during the sliding wear tests. A suitable model was used to simulate the wear mechanism of the coating.

  2. Thermal Conductivity Measurement and Analysis of Fully Ceramic Microencapsulated fuel

    International Nuclear Information System (INIS)

    Lee, H. G.; Kim, D. J.; Park, J. Y.; Kim, W. J.; Lee, S. J.

    2015-01-01

    FCM nuclear fuel is composed of tristructural isotropic(TRISO) fuel particle and SiC ceramic matrix. SiC ceramic matrix play an essential part in protecting fission product. In the FCM fuel concept, fission product is doubly protected by TRISO coating layer and SiC ceramic matrix in comparison with the current commercial UO2 fuel system of LWR. In addition to a safety enhancement of FCM fuel, thermal conductivity of SiC ceramic matrix is better than that of UO2 fuel. Because the centerline temperature of FCM fuel is lower than that of the current UO2 fuel due to the difference of thermal conductivity of fuel, an operational release of fission products from the fuel can be reduced. SiC ceramic has attracted for nuclear fuel application due to its high thermal conductivity properties with good radiation tolerant properties, a low neutron absorption cross-section and a high corrosion resistance. Thermal conductivity of ceramic matrix composite depends on the thermal conductivity of each component and the morphology of reinforcement materials such as fibers and particles. There are many results about thermal conductivity of fiber-reinforced composite like as SiCf/SiC composite. Thermal conductivity of SiC ceramics and FCM pellets with the volume fraction of TRISO particles were measured and analyzed by analytical models. Polycrystalline SiC ceramics and FCM pellets with TRISO particles were fabricated by hot press sintering with sintering additives. Thermal conductivity of the FCM pellets with TRISO particles of 0 vol.%, 10 vol.%, 20 vol.%, 30 vol.% and 40 vol.% show 68.4, 52.3, 46.8, 43.0 and 34.5 W/mK, respectively. As the volume fraction of TRISO particles increased, the measured thermal conductivity values closely followed the prediction of Maxwell's equation

  3. Compensation for thermally induced birefringence in polycrystalline ceramic active elements

    International Nuclear Information System (INIS)

    Kagan, M A; Khazanov, E A

    2003-01-01

    Polycrystalline ceramics differ significantly from single crystals in that the crystallographic axes (and hence of the axes of thermally induced birefringence) are oriented randomly in each granule of the ceramic. The quaternion formalism is employed to calculate the depolarisation in the ceramics and the efficiency of its compensation. The obtained analytic expressions are in good agreement with the numerical relations. It is shown that the larger the ratio of the sample length to the granule size, the closer the properties of the ceramics to those of a single crystal with the [111] orientation (in particular, the uncompensated depolarisation is inversely proportional to this ratio). (active media)

  4. Dolomite addition effects on the thermal expansion of ceramic tiles

    International Nuclear Information System (INIS)

    Marino, Luis Fernando Bruno; Boschi, Anselmo Ortega

    1997-01-01

    The thermal expansion of ceramic tiles is of greater importance in engineering applications because the ceramics are relatively brittle and cannot tolerate large internal strain imposed by thermal expansion. When ceramic bodies are produced for glazed ties the compatibility of this property of the components should be considered to avoid damage in the final products. Carbonates are an important constituent of ceramic wall-title bodies and its presence in formulations and the reactions that occur between them and other components modify body properties. The influence in expansivity by additions of calcium magnesium carbonate in a composition of wall tile bodies has been investigated. The relative content of mineralogical components was determined by X-ray diffraction and thermal expansion by dilatometric measurements. The results was indicated that with the effect of calcium-magnesium phases and porosity on thermal expansion of wall tile bodies. (author)

  5. 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.

  6. 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.

  7. Microstructure and durability of zirconia thermal barrier coatings

    International Nuclear Information System (INIS)

    Suhr, D.S.; Mitchell, T.E.; Keller, R.J.

    1983-01-01

    Various combinations of plasma-sprayed bond coatings and zirconia ceramic coatings on a nickel-based superalloy substrate were tested by static thermal exposure at 1200 0 C and cyclic thermal exposure to 1000 0 C. The bond coats were based on Ni-Cr-Al alloys with additions of rare earth elements and Si. The ceramic coats were various ZrO 2 -Y 2 O 3 compositions, of which the optimum was found to be ZrO 2 -8.9 wt% Y 2 O 3 . Microstructural analysis showed that resistance to cracking during thermal exposure is strongly related to deleterious phase changes

  8. Gaseous material capacity of open plasma jet in plasma spray-physical vapor deposition process

    Science.gov (United States)

    Liu, Mei-Jun; Zhang, Meng; Zhang, Qiang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2018-01-01

    Plasma spray-physical vapor deposition (PS-PVD) process, emerging as a highly efficient hybrid approach, is based on two powerful technologies of both plasma spray and physical vapor deposition. The maximum production rate is affected by the material feed rate apparently, but it is determined by the material vapor capacity of transporting plasma actually and essentially. In order to realize high production rate, the gaseous material capacity of plasma jet must be fundamentally understood. In this study, the thermal characteristics of plasma were measured by optical emission spectrometry. The results show that the open plasma jet is in the local thermal equilibrium due to a typical electron number density from 2.1 × 1015 to 3.1 × 1015 cm-3. In this condition, the temperature of gaseous zirconia can be equal to the plasma temperature. A model was developed to obtain the vapor pressure of gaseous ZrO2 molecules as a two dimensional map of jet axis and radial position corresponding to different average plasma temperatures. The overall gaseous material capacity of open plasma jet, take zirconia for example, was further established. This approach on evaluating material capacity in plasma jet would shed light on the process optimization towards both depositing columnar coating and a high production rate of PS-PVD.

  9. Development of process maps for plasma spray: case study for molybdenum

    International Nuclear Information System (INIS)

    Sampath, S.; Jiang, X.; Kulkarni, A.; Matejicek, J.; Gilmore, D.L.; Neiser, R.A.

    2003-01-01

    A schematic representation referred to as 'process maps' examines the role of process variables on the properties of plasma-sprayed coatings. Process maps have been developed for air plasma spraying of molybdenum. Experimental work was done to investigate the importance of such spray parameters as gun current, primary gas flow, auxiliary gas flow, and powder carrier gas flow. In-flight particle temperatures and velocities were measured and diameters estimated in various areas of the spray plume. Empirical models were developed relating the input parameters to the in-flight particle characteristics. Molybdenum splats and coatings were produced at three distinct process conditions identified from the first-order process map experiments. In addition, substrate surface temperature during deposition was treated as a variable. Within the tested range, modulus, hardness and thermal conductivity increases with particle velocity, while oxygen content and porosity decreases. Increasing substrate deposition temperature resulted in dramatic improvement in coating thermal conductivity and modulus, while simultaneously increasing coating oxide content. Indentation reveals improved fracture resistance for the coatings prepared at higher substrate temperature. Residual stress was significantly affected by substrate temperature, although not to a great extent by particle conditions within the investigated parameter range. Coatings prepared at high substrate temperature with high-energy particles suffered considerably less damage in a wear test. The mechanisms behind these changes are discussed within the context relational maps, which have been proposed

  10. 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.

  11. Porous Alumina and Zirconia Ceramics With Tailored Thermal Conductivity

    Czech Academy of Sciences Publication Activity Database

    Gregorová, E.; Pabst, W.; Sofer, Z.; Jankovský, O.; Matějíček, Jiří

    2012-01-01

    Roč. 395, č. 1 (2012), 012022-012022 ISSN 1742-6588. [European Thermal Sciences Conference (Eurotherm)/6./. Poitiers, 04.09.2012-07.09.2012] Institutional support: RVO:61389021 Keywords : Ceramics * alumina * zirconia * porosity * thermal conductivity * pore-forming agent * oxide ceramics * starch * porosity Subject RIV: JK - Corrosion ; Surface Treatment of Materials http://iopscience.iop.org/1742-6596/395/1/012022/pdf/1742-6596_395_1_012022.pdf

  12. Thermal conductivity analysis of SiC ceramics and fully ceramic microencapsulated fuel composites

    International Nuclear Information System (INIS)

    Lee, Hyeon-Geun; Kim, Daejong; Lee, Seung Jae; Park, Ji Yeon; Kim, Weon-Ju

    2017-01-01

    Highlights: • Thermal conductivity of SiC ceramics and FCM pellets was measured and discussed. • Thermal conductivity of FCM pellets was analyzed by the Maxwell-Eucken equation. • Effective thermal conductivity of TRISO particles applied in this study was assumed. - Abstract: The thermal conductivity of SiC ceramics and FCM fuel composites, consisting of a SiC matrix and TRISO coated particles, was measured and analyzed. SiC ceramics and FCM pellets were fabricated by hot press sintering with Al_2O_3 and Y_2O_3 sintering additives. Several factors that influence thermal conductivity, specifically the content of sintering additives for SiC ceramics and the volume fraction of TRISO particles and the matrix thermal conductivity of FCM pellets, were investigated. The thermal conductivity values of samples were analyzed on the basis of their microstructure and the arrangement of TRISO particles. The thermal conductivity of the FCM pellets was compared to that predicted by the Maxwell-Eucken equation and the thermal conductivity of TRISO coated particles was calculated. The thermal conductivity of FCM pellets in various sintering conditions was in close agreement to that predicted by the Maxwell-Eucken equation with the fitted thermal conductivity value of TRISO particles.

  13. Plasma Sprayed Coatings for RF Wave Absorption

    Czech Academy of Sciences Publication Activity Database

    Nanobashvili, S.; Matějíček, Jiří; Žáček, František; Stöckel, Jan; Chráska, Pavel; Brožek, Vlastimil

    307-311, - (2002), s. 1334-1338 ISSN 0022-3115 Grant - others: COST (XE) Euratom DV4/04(TWO) Institutional research plan: CEZ:AV0Z2043910 Keywords : boron carbide, thermal spray coatings, fusion materials, RF wave absorption Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.730, year: 2002

  14. Consolidation of tungsten disilicide by plasma spraying

    Czech Academy of Sciences Publication Activity Database

    Brožek, Vlastimil; Ctibor, Pavel; Matějíček, Jiří; Rohan, Pavel; Janča, J.

    2007-01-01

    Roč. 52, č. 3 (2007), s. 311-320 ISSN 0001-7043 R&D Projects: GA ČR(CZ) GA104/05/0540 Institutional research plan: CEZ:AV0Z20430508 Keywords : Water stabilized plasma * tungsten disilicide * plasma deposition * thermal spray coatings Subject RIV: JJ - Other Materials

  15. Plasma spraying of Fe-Cr-Al alloy powder

    Czech Academy of Sciences Publication Activity Database

    Voleník, Karel; Leitner, J.; Kolman, Blahoslav Jan; Písačka, Jan; Schneeweiss, Oldřich

    2008-01-01

    Roč. 46, č. 1 (2008), s. 17-25 ISSN 0023-432X R&D Projects: GA AV ČR IAA1041404 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z20410507 Keywords : Fe-Cr-Al alloy powder * plasma spraying * oxidation * vaporization * composition changes Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.345, year: 2007

  16. Aligned, plasma sprayed SmCo5 deposits

    International Nuclear Information System (INIS)

    Kumar, K.; Das, D.

    1986-01-01

    Highly aligned SmCo 5 deposits were produced using plasma spraying. c-axis alignment, normal to the plane of the deposit, was achieved by depositing the Sm-Co alloys on steel substrates maintained at high temperatures. The substrates were heated by the plasma flame to obtain the high temperatures. The attainment of a range of substrate temperatures was made possible through control over the geometry of the substrate

  17. Evaluation of Plasma Spray hydroxy Apatite Coatings on Metallic Materials

    International Nuclear Information System (INIS)

    Take, S.; Mitsul, K.; Kasahara, M.; Sawal, R.; Izawa, S.; Nakayama, M.; Itoi, Y.

    2007-01-01

    Biocompatible Hydroxy apatite (HAp) coatings on metallic substrate by plasma spray techniques have been developed. Long-term credibility of plasma spray HAp coatings has been evaluated in physiological saline by electrochemical measurements. It was found that the corrosion resistance of SUS316L based HAp/Ti combined coatings was excellent even after more than 10 weeks long-term immersion. It was shown that postal heat treatment improved both the crystallinity and corrosion resistance of HAp. By lowering cooling rate during heat treatment process, less cracks produced in HAp coating layer, which lead to higher credibility of HAp during immersion in physiological saline. The ICP results showed that the dissolution level of substrate metallic ions was low and HAp coatings produced in this research can be acceptable as biocompatible materials. Also, the concentration of dissolved ions from HAp coatings with postal heat treatment was lower compared to those from samples without postal heat treatment. The adherence of HAp coatings with Ti substrate and other mechanical properties were also assessed by three-point bending test. The poor adhesion of HAp coating to titanium substrate can be improved by introducing a plasma spray titanium intermediate layer

  18. Production of press moulds by plasma spray forming process

    International Nuclear Information System (INIS)

    Borisov, Y.; Myakota, I.; Polyakov, S.

    2001-01-01

    Plasma spray forming process for production of press moulds which are used for manufacture of articles from plastics was developed. The press moulds were produced by plasma spraying of Cu-Al-Fe-alloy powder on surface of a master model. The master models were made from non-metallic materials with heat resistance below 70 C (wood, gypsum etc). Double cooling system which provides for a control of surface model temperature and quenching conditions of sprayed material was designed. It made possible on the one hand to support model surface temperature below 70 C and on the other hand to provide for temperature conditions of martensite transformation in Cu-Al-system with a fixation of metastable ductile α + β 1 -phase. This allowed to decrease residual stresses in sprayed layer (up to 0,5-2,5 MPa), to increase microhardness of the coating material (up to 1200-1800 MPa) and its ductility (σ B = 70-105 MPa, δ = 6-12 %). This plasma spray forming process makes possible to spray thick layers (5-20 mm and more) without their cracking and deformation. The process is used for a production of press moulds which are applied in shoes industry, for fabrication of toys, souvenirs etc. (author)

  19. Crack growth in thermally sprayed ceramic coatings

    Czech Academy of Sciences Publication Activity Database

    Kroupa, František; Náhlík, Luboš; Knésl, Zdeněk

    2004-01-01

    Roč. 49, č. 2 (2004), s. 149-168 ISSN 0001-7043 R&D Projects: GA ČR GP106/04/P084; GA ČR GA101/03/0331 Institutional research plan: CEZ:AV0Z2043910 Keywords : ceramic coatings, fracture mechanics, crack extension Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  20. The role of amorphous phase content on the electrical properties of atmospheric plasma sprayed (Ba,Sr)TiO3 coatings

    Czech Academy of Sciences Publication Activity Database

    Kotlan, Jiří; Seshadri, R.C.; Sampath, S.; Ctibor, Pavel

    2016-01-01

    Roč. 42, č. 9 (2016), s. 11010-11014 ISSN 0272-8842 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : X-ray methods * Electrical properties * Perovskites * Atmospheric Plasma Spray Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S0272884216303856

  1. Influence of the metallic matrix ratio on the wear resistance (dry and slurry abrasion) of plasma sprayed cermet (chromia / stainless steel) coatings

    Czech Academy of Sciences Publication Activity Database

    Ageorges, H.; Ctibor, Pavel; Medarhri, Z.; Touimi, S.; Fauchais, P.

    2006-01-01

    Roč. 201, č. 5 (2006), s. 2006-2011 ISSN 0257-8972 R&D Projects: GA AV ČR(CZ) 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma spraying * composite coating * tribology * hardness * wear * abrasion * chromia/stainless steel Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.559, year: 2006

  2. Characterization of metal-supported axial injection plasma sprayed solid oxide fuel cells with aqueous suspension plasma sprayed electrolyte layers

    Science.gov (United States)

    Waldbillig, D.; Kesler, O.

    A method for manufacturing metal-supported SOFCs with atmospheric plasma spraying (APS) is presented, making use of aqueous suspension feedstock for the electrolyte layer and dry powder feedstock for the anode and cathode layers. The cathode layer was deposited first directly onto a metal support, in order to minimize contact resistance, and to allow the introduction of added porosity. The electrolyte layers produced by suspension plasma spraying (SPS) were characterized in terms of thickness, permeability, and microstructure, and the impact of substrate morphology on electrolyte properties was investigated. Fuel cells produced by APS were electrochemically tested at temperatures ranging from 650 to 750 °C. The substrate morphology had little effect on open circuit voltage, but substrates with finer porosity resulted in lower kinetic losses in the fuel cell polarization.

  3. Characterization of metal-supported axial injection plasma sprayed solid oxide fuel cells with aqueous suspension plasma sprayed electrolyte layers

    Energy Technology Data Exchange (ETDEWEB)

    Waldbillig, D. [University of British Columbia, Department of Materials Engineering, 309-6350 Stores Road, Vancouver, BC (Canada); Kesler, O. [University of Toronto, Department of Mechanical and Industrial Engineering, 5 King' s College Road, Toronto, Ontario (Canada)

    2009-06-15

    A method for manufacturing metal-supported SOFCs with atmospheric plasma spraying (APS) is presented, making use of aqueous suspension feedstock for the electrolyte layer and dry powder feedstock for the anode and cathode layers. The cathode layer was deposited first directly onto a metal support, in order to minimize contact resistance, and to allow the introduction of added porosity. The electrolyte layers produced by suspension plasma spraying (SPS) were characterized in terms of thickness, permeability, and microstructure, and the impact of substrate morphology on electrolyte properties was investigated. Fuel cells produced by APS were electrochemically tested at temperatures ranging from 650 to 750 C. The substrate morphology had little effect on open circuit voltage, but substrates with finer porosity resulted in lower kinetic losses in the fuel cell polarization. (author)

  4. Novel Approach in the Use of Plasma Spray: Preparation of Bulk Titanium for Bone Augmentations

    Directory of Open Access Journals (Sweden)

    Michaela Fousova

    2017-08-01

    Full Text Available Thermal plasma spray is a common, well-established technology used in various application fields. Nevertheless, in our work, this technology was employed in a completely new way; for the preparation of bulk titanium. The aim was to produce titanium with properties similar to human bone to be used for bone augmentations. Titanium rods sprayed on a thin substrate wire exerted a porosity of about 15%, which yielded a significant decrease of Young′s modulus to the bone range and provided rugged topography for enhanced biological fixation. For the first verification of the suitability of the selected approach, tests of the mechanical properties in terms of compression, bending, and impact were carried out, the surface was characterized, and its compatibility with bone cells was studied. While preserving a high enough compressive strength of 628 MPa, the elastic modulus reached 11.6 GPa, thus preventing a stress-shielding effect, a generally known problem of implantable metals. U-2 OS and Saos-2 cells derived from bone osteosarcoma grown on the plasma-sprayed surface showed good viability.

  5. The effect of processing parameters on plasma sprayed beryllium for fusion applications

    International Nuclear Information System (INIS)

    Castro, R.G.; Stanek, P.W.; Jacobson, L.A.; Cowgill, D.F.; Snead, L.L.

    1993-01-01

    Plasma spraying is being investigated as a potential coating technique for applying thin (0.1--5mm) layers of beryllium on plasma facing surfaces of blanket modules in ITER and also as an in-situ repair technique for repairing eroded beryllium surfaces in high heat flux divertor regions. High density spray deposits (>98% of theoretical density) of beryllium will be required in order to maximize the thermal conductivity of the beryllium coatings. A preliminary investigation was done to determine the effect of various processing parameters (particle size, particle morphology, secondary gas additions and reduced chamber pressure) on the as-deposited density of beryllium. The deposits were made using spherical beryllium feedstock powder which was produced by centrifugal atomization at Los Alamos National Laboratory (LANL). Improvements in the as-deposited densities and deposit efficiencies of the beryllium spray deposits will be discussed along with the corresponding thermal conductivity and outgassing behavior of these deposits

  6. Application of Atmospheric Plasma-Sprayed Ferrite Layers for Particle Accelerators

    CERN Document Server

    Caspers, F; Federmann, S; Taborelli, M; Schulz, C; Bobzin, K; Wu, J

    2013-01-01

    A common problem in all kinds of cavity-like structures in particle accelerators is the occurrence of RF-resonances. Typically, ferrite plates attached to the walls of such structures as diagnostic devices, kickers or collimators, are used to dampen those undesired modes. However, the heat transfer rate from these plates to the walls is rather limited. Brazing ferrite plates to the walls is not possible in most cases due to the different thermal expansion coefficients. To overcome those limitations, atmospheric plasma spraying techniques have been investigated. Ferrite layers with a thickness from 50 μm to about 300 μm can be deposited on metallic surfaces like stainless steel exhibiting good thermal contact and still reasonable absorption properties. In this paper the technological aspects of plasma deposition are discussed and results of specifically developed RF loss measurement procedures for such thin magnetically lossy layers on metal are presented.

  7. The effect of processing parameters on plasma sprayed beryllium for fusion applications

    International Nuclear Information System (INIS)

    Castro, R.G.; Stanek, P.W.; Jacobson, L.W.; Cowgill, D.F.

    1993-01-01

    Plasma spraying is being investigated as a potential coating technique for applying thin (0.1-5mm) layers of beryllium on plasma facing surfaces of blanket modules in ITER and also as an in-situ repair technique for repairing eroded beryllium surfaces in high heat flux divertor regions. High density spray deposits (>98% of theoretical density) of beryllium will be required in order to maximize the thermal conductivity of the beryllium coatings. A preliminary investigation was done to determine the effect of various processing parameters (particle size, particle morphology, secondary gas additions and reduced chamber pressure) on the as-deposited density of beryllium. The deposits were made using spherical beryllium feedstock powder which was produced by centrifugal atomization at Los Alamos National Laboratory (LANL). Improvements in the as-deposited densities and deposit efficiencies of the beryllium spray deposits will be discussed along with the corresponding thermal conductivity and outgassing behavior of these deposits. (orig.)

  8. The influence of pore formers on the microstructure of plasma-sprayed NiO-YSZ anodes

    Science.gov (United States)

    Poon, Michael; Kesler, Olivera

    2012-07-01

    Four types of pore formers: high-density polyethylene (HDPE), polyether-ether-ketone (PEEK), mesocarbon-microbead (MCMB) carbon powder, and baking flour, are processed and characterized, then incorporated with NiO-YSZ nano-agglomerate powder to produce plasma sprayed SOFC anode coatings. Scanning electron microscopy (SEM) of the coating microstructure, gas permeability measurements, and porosity determinations by image analysis are used to evaluate the effectiveness of each potential pore former powder. Under the spray conditions studied, the flour and MCMB pore former powders are effective as plasma sprayed pore formers, increasing the permeability of the coatings by factors of four and two, respectively, compared to a similarly sprayed NiO-YSZ coating without pore formers. The HDPE powder is unable to survive the plasma spray process and does not contribute to the final coating porosity. The PEEK pore former, though ineffective with the current powder characteristics and spray parameters, exhibits the highest relative deposition efficiency and the most favorable thermal characteristics.

  9. Stainless steel coatings produced through atmospheric plasma spraying study of in flight powder behavior and coating structure

    International Nuclear Information System (INIS)

    Denoirjean, A.; Denoirjean, P.; Fauchais, P.; Labbe, J.C.; Khan, A.A.

    2005-01-01

    The Stainless Steel coatings deposited through Atmospheric Plasma Spraying over mild steel surface present an interest from commercial point of view, especially for the applications where corrosion resistance or inertness towards severe environment is required. Atmospheric Plasma Spraying is fast and relatively less expensive choice as compared to Vacuum Plasma Spraying, the only limitation being the extremely reactive nature of metallic powders used. A study of the behaviour of metallic powders within an Atmospheric Plasma Jet is presented in view of better understanding and eventual improvement in coating properties. Metallic powder particles show very interesting features when individual particles are collected after passing them through a DC Blown Arc Thermal Plasma Jet under Atmospheric Pressure. The spraying was carried out under air which makes the significance of these results even more interesting from the industrial point of view. Proper control of Spraying Parameters can help produce Stainless Steel coatings of reasonably low porosity and a typical lamellar microstructure. The results of SEM, AFM and XRD are discussed. A strange oxidation phenomenon under highly non equilibrium conditions is observed. (author)

  10. A comparative physico-chemical study of chlorapatite and hydroxyapatite: from powders to plasma sprayed thin coatings.

    Science.gov (United States)

    Demnati, I; Grossin, D; Combes, C; Parco, M; Braceras, I; Rey, C

    2012-10-01

    Due to their bioactivity and osteoconductivity, hydroxyapatite (HA) plasma sprayed coatings have been widely developed for orthopedic uses. However, the thermodynamic instability of HA leads frequently to a mixture of phases which limit the functional durability of the coating. This study investigates the plasma spraying of chlorapatite (ClA) powder, known to melt without decomposition, onto pure titanium substrates using a low energy plasma spray system (LEPS). Pure ClA powder was prepared by a solid gas reaction at 950 °C and thermogravimetric analysis showed the good thermal stability of ClA powder in the range 30-1400 °C compared to that of the HA powder. Characterization of ClA coating showed that ClA had a very high crystalline ratio and no other crystalline phase was detected in the coating. HA and ClA coatings composition, microstructure and in vitro bioactivity potential were studied, compared and discussed. In vitro SBF test on HA and ClA coatings revealed the formation of a poorly crystalline apatite on the coating surface suggesting that we could expect a good osteoconductivity especially for the ClA coating prepared by the LEPS system.

  11. 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).

  12. Synthesis and Characterization of Calcium Phosphate Powders for Biomedical Applications by Plasma Spray Coating

    OpenAIRE

    Sasidharan Pillai, Rahul

    2015-01-01

    This PhD work mainly focus on the synthesis and characterization of calcium phosphate powders for plasma spray coating. The preparation of high temperature phase stabilized βTCP and HA/βTCP powders for plasma spray coating applications has been the topic of investigation. Nowadays plasma sprayed coatings are widely used for biomedical applications especially in the dental and orthopaedic implantation field. Previously Ti based alloys were widely used for the orthopaedic and dental implant ap...

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

    National Research Council Canada - National Science Library

    Legg, Keith O; Sartwell, Bruce D; Legoux, Jean-Gabriel; Nestler, Montia; Dambra, Christopher; Wang, Daming; Quets, John; Natishan, Paul; Bretz, Philip; Devereaux, Jon

    2006-01-01

    .... This document constitutes the final report on an investigation of deposition of coatings using miniature plasma spray guns that could replace hard chromium on internal surfaces where conventional...

  14. Plasma-Sprayed Titania and Alumina Coatings Obtained from Feedstocks Prepared by Heterocoagulation with 1 wt.% Carbon Nanotube

    Science.gov (United States)

    Jambagi, Sudhakar C.; Agarwal, Anish; Sarkar, Nilmoni; Bandyopadhyay, P. P.

    2018-05-01

    Properties of plasma-sprayed ceramic coatings can be improved significantly by reinforcing such coatings with carbon nanotube (CNT). However, it is difficult to disperse CNT in the plasma spray feedstock owing to its tendency to form agglomerate. A colloidal processing technique, namely heterocoagulation, is effective in bringing about unbundling of CNT, followed by its homogeneous dispersion in the ceramic powder. This report deals with the mixing of micro-sized crushed titania and agglomerated alumina powders with CNT using the heterocoagulation technique. Heterocoagulation of titania was attempted with both cationic and anionic surfactants, and the latter was found to be more effective. Mixing of the oxides and carbon nanotube was also accomplished in a ball mill either in a dry condition or in alcohol, and powders thus obtained were compared with the heterocoagulated powder. The heterocoagulated powder has shown a more homogeneous dispersion of CNT in the oxide. The coatings produced from the heterocoagulated powder demonstrated improvement in hardness, porosity, indentation fracture toughness and elastic modulus. This is attributed to CNT reinforcement.

  15. Thin films by metal-organic precursor plasma spray

    International Nuclear Information System (INIS)

    Schulz, Douglas L.; Sailer, Robert A.; Payne, Scott; Leach, James; Molz, Ronald J.

    2009-01-01

    While most plasma spray routes to coatings utilize solids as the precursor feedstock, metal-organic precursor plasma spray (MOPPS) is an area that the authors have investigated recently as a novel route to thin film materials. Very thin films are possible via MOPPS and the technology offers the possibility of forming graded structures by metering the liquid feed. The current work employs metal-organic compounds that are liquids at standard temperature-pressure conditions. In addition, these complexes contain chemical functionality that allows straightforward thermolytic transformation to targeted phases of interest. Toward that end, aluminum 3,5-heptanedionate (Al(hd) 3 ), triethylsilane (HSi(C 2 H 5 ) 3 or HSiEt 3 ), and titanium tetrakisdiethylamide (Ti(N(C 2 H 5 ) 2 ) 4 or Ti(NEt 2 ) 4 ) were employed as precursors to aluminum oxide, silicon carbide, and titanium nitride, respectively. In all instances, the liquids contain metal-heteroatom bonds envisioned to provide atomic concentrations of the appropriate reagents at the film growth surface, thus promoting phase formation (e.g., Si-C bond in triethylsilane, Ti-N bond in titanium amide, etc.). Films were deposited using a Sulzer Metco TriplexPro-200 plasma spray system under various experimental conditions using design of experiment principles. Film compositions were analyzed by glazing incidence x-ray diffraction and elemental determination by x-ray spectroscopy. MOPPS films from HSiEt 3 showed the formation of SiC phase but Al(hd) 3 -derived films were amorphous. The Ti(NEt 2 ) 4 precursor gave MOPPS films that appear to consist of nanosized splats of TiOCN with spheres of TiO 2 anatase. While all films in this study suffered from poor adhesion, it is anticipated that the use of heated substrates will aid in the formation of dense, adherent films.

  16. Suspension plasma sprayed composite coating using amorphous powder feedstock

    International Nuclear Information System (INIS)

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

    2009-01-01

    Al 2 O 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 2 O 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 2 O 3 and ZrO 2 phases are homogeneously distributed in the composite coating

  17. The measurement of single particle temperature in plasma sprays

    International Nuclear Information System (INIS)

    Fincke, J.R.; Swank, W.D.; Bolsaitis, P.P.; Elliott, J.F.

    1990-01-01

    A measurement technique for simultaneously obtaining the size, velocity, temperature, and relative number density of particles entrained in high temperature flow fields is described. In determining the particle temperature from a two-color pyrometery technique, assumptions about the relative spectral emissivity of the particle are required. For situations in which the particle surface undergoes chemical reactions the assumption of grey body behavior is shown to introduce large Temperature measurement uncertainties. Results from isolated, laser heated, single particle measurements and in-flight data from the plasma spraying of WC-Co are presented. 10 refs., 5 figs

  18. On reactive suspension plasma spraying of calcium titanate

    OpenAIRE

    Kotlan, J. (Jiří); Pala, Z. (Zdeněk); Mušálek, R. (Radek); Ctibor, P. (Pavel)

    2016-01-01

    This study shows possibility of preparation of calcium titanate powder and coatings by reactive suspension plasma spraying. Suspension of mixture of calcium carbonate (CaCO3) and titanium dioxide (TiO2) powders in ethanol was fed into hybrid plasma torch with a DC-arc stabilized by a water–argon mixture (WSP-H 500). Various feeding distances and angles were used in order to optimize suspension feeding conditions. In the next step, the coatings were deposited on stainless steel substrates and ...

  19. Development Status and Performance Comparisons of Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan

    2016-01-01

    Environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft turbine engine systems, because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. This paper presents current NASA EBC-CMC development emphases including: the coating composition and processing improvements, laser high heat flux-thermal gradient thermo-mechanical fatigue - environmental testing methodology development, and property evaluations for next generation EBC-CMC systems. EBCs processed with various deposition techniques including Plasma Spray, Electron Beam - Physical Vapor Deposition, and Plasma Spray Physical Vapor Deposition (PS-PVD) will be particularly discussed. The testing results and demonstrations of advanced EBCs-CMCs in complex simulated engine thermal gradient cyclic fatigue, oxidizing-steam and CMAS environments will help provide insights into the coating development strategies to meet long-term engine component durability goals.

  20. Controlling of Nitriding Process on Reactive Plasma Spraying of Al Particles

    Energy Technology Data Exchange (ETDEWEB)

    Shahien, Mohammed [Graduate Student, Toyohashi University of Technology (Japan); Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro, E-mail: mo.shahien@yahoo.com [Toyohashi University of Technology (Japan)

    2011-10-29

    Reactive plasma spraying (RPS) has been considered as a promising technology for in-situ formation of aluminum nitride (AlN) thermally sprayed coatings. To fabricate thick A lN coatings in RPS process, controlling and improving the in-flight nitriding reaction of Al particles is required. In this study, it was possible to control the nitriding reaction by using ammonium chloride (NH{sub 4}Cl) powders. Thick and dense AlN coating (more than 300 {mu}m thickness) was successfully fabricated with small addition of NH{sub 4}Cl powders. Thus, addition of NH{sub 4}Cl prevented the Al aggregation by changing the reaction pathway to a mild way with no explosive mode (relatively low heating rates) and it acts as a catalyst, nitrogen source and diluent agent.

  1. Controlling of Nitriding Process on Reactive Plasma Spraying of Al Particles

    International Nuclear Information System (INIS)

    Shahien, Mohammed; Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro

    2011-01-01

    Reactive plasma spraying (RPS) has been considered as a promising technology for in-situ formation of aluminum nitride (AlN) thermally sprayed coatings. To fabricate thick A lN coatings in RPS process, controlling and improving the in-flight nitriding reaction of Al particles is required. In this study, it was possible to control the nitriding reaction by using ammonium chloride (NH 4 Cl) powders. Thick and dense AlN coating (more than 300 μm thickness) was successfully fabricated with small addition of NH 4 Cl powders. Thus, addition of NH 4 Cl prevented the Al aggregation by changing the reaction pathway to a mild way with no explosive mode (relatively low heating rates) and it acts as a catalyst, nitrogen source and diluent agent.

  2. 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.

  3. Modeling of thermal explosion under pressure in metal ceramic systems

    International Nuclear Information System (INIS)

    Shapiro, M.; Dudko, V.; Skachek, B.; Matvienko, A.; Gotman, I.; Gutmanas, E.Y.

    1998-01-01

    The process of reactive in situ synthesis of dense ceramic matrix composites in Ti-B-C, Ti-B-N, Ti-Si-N systems is modeled. These ceramics are fabricated on the basis of compacted blends of ceramic powders, namely Ti-B 4 C and/or Ti-BN. The objectives of the project are to identify and investigate the optimal thermal conditions preferable for production of fully dense ceramic matrix composites. Towards this goal heat transfer and combustion in dense and porous ceramic blends are investigated during monotonous heating at a constant rate. This process is modeled using a heat transfer-combustion model with kinetic parameters determined from the differential thermal analysis of the experimental data. The kinetic burning parameters and the model developed are further used to describe the thermal explosion synthesis in a restrained die under pressure. It is shown that heat removal from the reaction zone affects the combustion process and the final phase composition

  4. Modification of vacuum plasma sprayed tungsten coating on reduced activation ferritic/martensitic steels by friction stir processing

    International Nuclear Information System (INIS)

    Tanigawa, Hiroyasu; Ozawa, Kazumi; Morisada, Yoshiaki; Noh, Sanghoon; Fujii, Hidetoshi

    2015-01-01

    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.

  5. 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.

  6. Development of Composite for Thermal Barriers Reinforced by Ceramic Fibers

    Directory of Open Access Journals (Sweden)

    Ondřej Holčapek

    2018-01-01

    Full Text Available The paper introduces the development process of fiber-reinforced composite with increased resistance to elevated temperatures, which could be additionally increased by the hydrothermal curing. However, production of these composites is extremely energy intensive, and that is why the process of the design reflects environmental aspects by incorporation of waste material—fine ceramic powder applied as cement replacement. Studied composite materials consisted of the basalt aggregate, ceramic fibers applied up to 8% by volume, calcium-aluminous cement (CAC, ceramic powder up to 25% by mass (by 5% as cement replacement, plasticizer, and water. All studied mixtures were subjected to thermal loading on three thermal levels: 105°C, 600°C, and 1000°C. Experimental assessment was performed in terms of both initial and residual material properties; flow test of fresh mixtures, bulk density, compressive strength, flexural strength, fracture energy, and dynamic modulus of elasticity were investigated to find out an optimal dosage of ceramic fibers. Resulting set of composites containing 4% of ceramic fibers with various modifications by ceramic powder was cured under specific hydrothermal condition and again subjected to elevated temperatures. One of the most valuable benefits of additional hydrothermal curing of the composites lies in the higher residual mechanical properties, what allows successful utilization of cured composite as a thermal barrier in civil engineering. Mixtures containing ceramic powder as cement substitute exhibited after hydrothermal curing increase of residual flexural strength about 35%; on the other hand, pure mixture exhibited increase up to 10% even higher absolute values.

  7. 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.

  8. Ternary ceramic thermal spraying powder and method of manufacturing thermal sprayed coating using said powder

    Energy Technology Data Exchange (ETDEWEB)

    Vogli, Evelina; Sherman, Andrew J.; Glasgow, Curtis P.

    2018-02-06

    The invention describes a method for producing ternary and binary ceramic powders and their thermal spraying capable of manufacturing thermal sprayed coatings with superior properties. Powder contain at least 30% by weight ternary ceramic, at least 20% by weight binary molybdenum borides, at least one of the binary borides of Cr, Fe, Ni, W and Co and a maximum of 10% by weight of nano and submicro-sized boron nitride. The primary crystal phase of the manufactured thermal sprayed coatings from these powders is a ternary ceramic, while the secondary phases are binary ceramics. The coatings have extremely high resistance against corrosion of molten metal, extremely thermal shock resistance and superior tribological properties at low and at high temperatures.

  9. Erosion and foreign object damage of thermal barrier coatings

    International Nuclear Information System (INIS)

    Nicholls, J.R.; Jaslier, Y.; Rickerby, D.S.

    1997-01-01

    Thermal barrier coating technology is used in the hot sections of gas turbines to extend component life. To maximise these benefits, the thermal barrier coating has to remain intact throughout the life of the turbine. High velocity ballistic damage can lead to total thermal barrier removal, while erosion may lead to progressive loss of thickness during operation. This paper particularly addresses the erosion resistance and resistance to foreign object damage of thermal barrier coatings. It was found that EB-PVD thermal barriers are significantly more erosion resistant when impacted with alumina or silica, than the equivalent plasma spray coating, both at room temperature and 910 C. Examination of tested hardware, reveals that cracking occurs within the near surface region of the columns for EB-PVD ceramic and that erosion occurs by removal of these small blocks of material. In stark contrast, removal of material for plasma sprayed ceramic occurs through poorly bonded splat boundaries. Large particle impact results in severe damage to the EB-PVD thermal barrier, with cracks penetrating through the ceramic coating to the ceramic/bond coat interface. Material removal, per particle impact, increases with increased particle size. (orig.)

  10. 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

  11. Evaluation of the thermal comfort of ceramic floor tiles

    Directory of Open Access Journals (Sweden)

    Carmeane Effting

    2007-09-01

    Full Text Available In places where people are bare feet, the thermal sensation of cold or hot depends on the environmental conditions and material properties including its microstructure and crustiness surface. The uncomforting can be characterized by heated floor surfaces in external environments which are exposed to sun radiation (swimming polls areas or by cold floor surfaces in internal environments (bed rooms, path rooms. The property named thermal effusivity which defines the interface temperature when two semi-infinite solids are putted in perfect contact. The introduction of the crustiness surface on the ceramic tiles interferes in the contact temperature and also it can be a strategy to obtain ceramic tiles more comfortable. Materials with low conductivities and densities can be obtained by porous inclusion are due particularly to the processing conditions usually employed. However, the presence of pores generally involves low mechanical strength. This work has the objective to evaluate the thermal comfort of ceramics floor obtained by incorporation of refractory raw materials (residue of the polishing of the porcelanato in industrial atomized ceramic powder, through the thermal and mechanical properties. The theoretical and experimental results show that the porosity and crustiness surface increases; there is sensitive improvement in the comfort by contact.

  12. Thermal properties of lithium ceramics for fusion applications

    International Nuclear Information System (INIS)

    Hollenberg, G.W.; Baker, D.E.

    1982-03-01

    Specific heat, thermal diffusivity and thermal conductivity were measured on Li 2 O, Li 4 SiO 4 , Li 2 ZrO 3 and LiAlO 2 . Data on these properties were needed for design of an irradiation experiment to be performed on these materials. In general, the specific heat of a ceramic is primarily enrichment-dependent, but the thermal diffusivity and thermal expansion coefficient may be influenced by microstructure. Hence, it will be necessary to duplicate these measurements on the engineering materials finally selected for a particular design

  13. Thermal shock behavior of rare earth modified alumina ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Junlong; Liu, Changxia [Ludong Univ., Yantai (China). School of Transportation

    2017-05-15

    Alumina matrix ceramic composites toughened by AlTiC master alloys, diopside and rare earths were fabricated by hot-pressing and their thermal shock behavior was investigated and compared with that of monolithic alumina. Results showed that the critical thermal shock temperature (ΔT) of monolithic alumina was 400 C. However, it decreased to 300 C for alumina incorporating only AlTiC master alloys, and increased with further addition of diopside and rare earths. Improvement of thermal shock resistance was obtained for alumina ceramic composites containing 9.5 wt.% AlTiC master alloys and 0.5 wt.% rare earth additions, which was mainly attributed to the formation of elongated grains in the composites.

  14. Aerospace Ceramic Materials: Thermal, Environmental Barrier Coatings and SiC/SiC Ceramic Matrix Composites for Turbine Engine Applications

    Science.gov (United States)

    Zhu, Dongming

    2018-01-01

    Ceramic materials play increasingly important roles in aerospace applications because ceramics have unique properties, including high temperature capability, high stiffness and strengths, excellent oxidation and corrosion resistance. Ceramic materials also generally have lower densities as compared to metallic materials, making them excellent candidates for light-weight hot-section components of aircraft turbine engines, rocket exhaust nozzles, and thermal protection systems for space vehicles when they are being used for high-temperature and ultra-high temperature ceramics applications. Ceramic matrix composites (CMCs), including non-oxide and oxide CMCs, are also recently being incorporated in gas turbine engines for high pressure and high temperature section components and exhaust nozzles. However, the complexity and variability of aerospace ceramic processing methods, compositions and microstructures, the relatively low fracture toughness of the ceramic materials, still remain the challenging factors for ceramic component design, validation, life prediction, and thus broader applications. This ceramic material section paper presents an overview of aerospace ceramic materials and their characteristics. A particular emphasis has been placed on high technology level (TRL) enabling ceramic systems, that is, turbine engine thermal and environmental barrier coating systems and non-oxide type SiC/SiC CMCs. The current status and future trend of thermal and environmental barrier coatings and SiC/SiC CMC development and applications are described.

  15. Glass ceramics for sealing to high-thermal-expansion metals

    International Nuclear Information System (INIS)

    Wilder, J.A. Jr.

    1980-10-01

    Glass ceramics were studied, formulated in the Na 2 O CaO.P 2 O 5 , Na 2 O.BaOP 2 O 5 , Na 2 O.Al 2 O 3 .P 2 O 5 , and Li 2 O.BaO.P 2 O 5 systems to establish their suitability for sealing to high thermal expansion metals, e.g. aluminum, copper, and 300 series stainless steels. Glass ceramics in Na 2 O.CaO.P 2 O 5 and Na 2 O.BaO.P 2 O 5 systems have coefficients of thermal expansion in the range 140 x 10 -1 per 0 C less than or equal to α less than or equal to 225 x 10 -7 per 0 C and fracture toughness values generally greater than those of phosphate glasses; they are suitable for fabricating seals to high thermal expansion metals. Crystal phases include NaPo 3 , (NaPO 3 ) 3 , NaBa(PO 3 ) 3 , and NaCa(PO 3 ) 3 . Glass ceramics formed in the Na 2 O.Al 2 O 3 .P 2 O 5 systems have coefficients of thermal expansion greater than 240 x 10 -7 per 0 C, but they have extensive microcracking. Due to their low thermal expansion values (α less than or equal to 120 x 10 -7 per 0 C), glass ceramics in the Li 2 O.BaO.P 2 O 5 system are unsuitable for sealing to high thermal expansion metals

  16. Computational image analysis of Suspension Plasma Sprayed YSZ coatings

    Directory of Open Access Journals (Sweden)

    Michalak Monika

    2017-01-01

    Full Text Available The paper presents the computational studies of microstructure- and topography- related features of suspension plasma sprayed (SPS coatings of yttria-stabilized zirconia (YSZ. The study mainly covers the porosity assessment, provided by ImageJ software analysis. The influence of boundary conditions, defined by: (i circularity and (ii size limits, on the computed values of porosity is also investigated. Additionally, the digital topography evaluation is performed: confocal laser scanning microscope (CLSM and scanning electron microscope (SEM operating in Shape from Shading (SFS mode measure surface roughness of deposited coatings. Computed values of porosity and roughness are referred to the variables of the spraying process, which influence the morphology of coatings and determines the possible fields of their applications.

  17. Synthesis and characterization of Yb and Er based monosilicate powders and durability of plasma sprayed Yb2SiO5 coatings on C/C–SiC composites

    International Nuclear Information System (INIS)

    Khan, Zuhair S.; Zou Binglin; Huang Wenzhi; Fan Xizhi; Gu Lijian; Chen Xiaolong; Zeng Shuibing; Wang Chunjie; Cao Xueqiang

    2012-01-01

    Highlights: ► Ultra-pure rare-earth monosilicate powders based on Er and Yb have been fabricated by solid-state reaction. ► Spray-drying treatment results in powders with free flowing characteristics and rounded surface morphologies. ► CTEs are found to be 7.1 ppm/°C for Yb 2 SiO 5 and 7.5 ppm/°C for Er 2 SiO 5 . ► Plasma spraying has been used to deposit Yb 2 SiO 5 coatings on C/C–SiC substrate. ► Coatings remain strongly intact with the substrate on thermal cycling between ∼400 °C and 1500 °C in gas burner rig experiment. - Abstract: Rare-earth silicates such as Yb 2 SiO 5 and Er 2 SiO 5 are promising environmental barrier coating materials for ceramic matrix composites. In this work, Yb 2 SiO 5 and Er 2 SiO 5 ceramic powders have been synthesized by solid-state reaction using Yb 2 O 3 , Er 2 O 3 and SiO 2 as starting materials. The fabricated powders were subjected to spray drying treatment for subsequent synthesis of coatings by plasma spraying. The spray drying resulted in well-dispersed and spherical powder particles with good flowability. Analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry and differential scanning calorimetry (TGA/DSC) and dilatometry were applied to study the microstructural and thermal characteristics of the powders. Ultra-high purity monosilicate powders formed as a result of heating treatments at 1400 °C in a box furnace for 20 h. TG/DSC revealed the genesis temperatures of the silicate formation (low temperature polymorphs) and also showed that the solid-state reactions to form Yb and Er based monosilicates proceeded without any weight-loss in the tested temperature range. The values of coefficients of thermal expansion (CTE) of the fabricated compounds are found to be 7.1 ppm/°C for Yb 2 SiO 5 and 7.5 ppm/°C for Er 2 SiO 5 by dilatometric measurements. Besides these studies, coating formation by plasma spraying of spray-dried Yb 2 SiO 5 powders on the ceramic

  18. Characterization of gas tunnel type plasma sprayed hydroxyapatite-nanostructure titania composite coatings

    Science.gov (United States)

    Yugeswaran, S.; Kobayashi, A.; Ucisik, A. Hikmet; Subramanian, B.

    2015-08-01

    Hydroxyapatite (HA) can be coated onto metal implants as a ceramic biocompatible coating to bridge the growth between implants and human tissue. Meanwhile many efforts have been made to improve the mechanical properties of the HA coatings without affecting its bioactivity. In the present study, nanostructure titania (TiO2) was mixed with HA powder and HA-nanostructure TiO2 composite coatings were produced by gas tunnel type plasma spraying torch under optimized spraying conditions. For this purpose, composition of 10 wt% TiO2 + 90 wt% HA, 20 wt% TiO2 + 80 wt% HA and 30 wt% TiO2 + 70 wt% HA were selected as the feedstock materials. The phase, microstructure and mechanical properties of the coatings were characterized. The obtained results validated that the increase in weight percentage of nanostructure TiO2 in HA coating significantly increased the microhardness, adhesive strength and wear resistance of the coatings. Analysis of the in vitro bioactivity and cytocompatibility of the coatings were done using conventional simulated body fluid (c-SBF) solution and cultured green fluorescent protein (GFP) labeled marrow stromal cells (MSCs) respectively. The bioactivity results revealed that the composite coating has bio-active surface with good cytocompatibility.

  19. Deposition stress effects on thermal barrier coating burner rig life

    Science.gov (United States)

    Watson, J. W.; Levine, S. R.

    1984-01-01

    A study of the effect of plasma spray processing parameters on the life of a two layer thermal barrier coating was conducted. The ceramic layer was plasma sprayed at plasma arc currents of 900 and 600 amps onto uncooled tubes, cooled tubes, and solid bars of Waspalloy in a lathe with 1 or 8 passes of the plasma gun. These processing changes affected the residual stress state of the coating. When the specimens were tested in a Mach 0.3 cyclic burner rig at 1130 deg C, a wide range of coating lives resulted. Processing factors which reduced the residual stress state in the coating, such as reduced plasma temperature and increased heat dissipation, significantly increased coating life.

  20. 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.

  1. A Novel Electro-Thermal Laminated Ceramic with Carbon-Based Layer

    Directory of Open Access Journals (Sweden)

    Yi Ji

    2017-06-01

    Full Text Available A novel electro-thermal laminated ceramic composed of ceramic tile, carbon-based layer, dielectric layer, and foaming ceramic layer was designed and prepared by tape casting. The surface temperature achieved at an applied voltage of 10 V by the laminated ceramics was 40.3 °C when the thickness of carbon-based suspension was 1.0 mm and the adhesive strength between ceramic tile and carbon-based layer was 1.02 ± 0.06 MPa. In addition, the thermal aging results at 100 °C up to 192 h confirmed the high thermal stability and reliability of the electro-thermal laminated ceramics. The development of this laminated ceramic with excellent electro-thermal properties and safety provides a new individual heating device which is highly expected to be widely applied in the field of indoor heat supply.

  2. Characterization of alumina scales formed during isothermal and cyclic oxidation of plasma-sprayed TBC systems at 1150 C

    International Nuclear Information System (INIS)

    Haynes, J.A.; Ferber, M.K.; Porter, W.D.; Rigney, E.D.

    1999-01-01

    The isothermal- and cyclic-oxidation behavior of thermal barrier coating (TBC) systems consisting of vacuum plasma-sprayed (VPS) Ni-22Cr-10Al/Y (wt%) bond coatings and air plasma-sprayed (APS) Y 2 O 3 -stabilized ZrO 2 (YSZ) top coatings (on single-crystal superalloys) was investigated. The microstructures, flaw contents, and fracture behavior of the Al 2 O 3 scales formed during oxidation testing at 1150 C were characterized (by analysis of coating and scale fracture surfaces and metallographic cross sections). Significant localized fracture and buckling of the Al 2 O 3 scales that formed along the bond-coat--top-coat interfaces were observed after cyclic oxidation of TBCs. However, substantial amounts of localized scale damage did not induce rapid TBC failure. Decohesion of the columnar alumina scales on the rough bond-coat surfaces occurred by both internal Al 2 O 3 fracture (parallel to the metal surface) and oxide-metal delamination. There were microstructural indications of Al 2 O 3 scale crack healing by sintering into planar arrays of voids. Alumina scales that formed on convex NiCrAlY surfaces (with radii of 50 microm or less) after cyclic oxidation, whereas scales formed by isothermal oxidation contained few visible voids. Accelerated void growth in Al 2 O 3 scales on the irregular NiCrAlY surfaces appeared to be creep-related and was attributed to the synergistic effects of geometric and thermal stresses

  3. Performance of vacuum plasma spray and HVOF bond coatings at 900° and 1100 °C

    Energy Technology Data Exchange (ETDEWEB)

    Lance, Michael J. [ORNL; Haynes, James A. [ORNL; Pint, Bruce A. [ORNL

    2017-12-01

    The effects of Ti and B additions to a vacuum plasma sprayed (VPS) NiCoCrAlYHfSi bond coating on thermal barrier coating (TBC) performance were studied at 1100 °C and 900 °C and compared to high-velocity oxy-fuel (HVOF) bond coatings. Using alloy 247 substrates and air plasma sprayed Y2O3-stabilized ZrO2 top coatings, additions of B or Ti + B did not improve the average TBC lifetime in 1-h cycles at 1100 °C in air with 10% H2O. The addition of Ti resulted in a decrease in lifetime. Photo-stimulated luminescence spectroscopy was used to map residual stresses in the thermally-grown Al2O3 scale. At 900 °C, closer to a typical land based turbine operating bond coating temperature, specimens were examined after ten 500-h cycles in laboratory air and air with 10%H2O to study the effect of H2O. The addition of water vapor had little effect on the measured parabolic rate constants at 900 °C and a comparison of the oxide microstructures in both environments is reported.

  4. Al-Si/B{sub 4}C composite coatings on Al-Si substrate by plasma spray technique

    Energy Technology Data Exchange (ETDEWEB)

    Sarikaya, Ozkan [Sakarya University, Faculty of Engineering, Department of Mechanical Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Anik, Selahaddin [Sakarya University, Faculty of Engineering, Department of Mechanical Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Aslanlar, Salim [Sakarya University, Faculty of Technical Education, Department of Mechanical Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Cem Okumus, S. [Sakarya University, Faculty of Engineering, Department of Metallurgical and Materials Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Celik, Erdal [Dokuz Eylul University, Engineering Faculty, Department of Metallurgical and Materials Engineering, Buca, Izmir 35160 (Turkey)]. E-mail: erdal.celik@deu.edu.tr

    2007-07-01

    Plasma-sprayed coatings of Al-Si/B{sub 4}C have been prepared on Al-Si piston alloys for diesel engine motors. The Al-Si/B{sub 4}C composite powders including 5-25 wt% B{sub 4}C were prepared by mixing and ball-milling processes. These powders were deposited on Al-Si substrate using an atmospheric plasma spray technique. The coatings have been characterised with respect to phase composition, microstructure, microhardness, bond strength and thermal expansion. It was found that Al, Si, B{sub 4}C and Al{sub 2}O{sub 3} phases were determined in the coatings with approximately 600 {mu}m thick by using X-ray diffraction analysis. Scanning electron microscope observation revealed that boron carbide particles were uniformly distributed in composite coatings and B{sub 4}C particles were fully wetted by Al-Si alloy. Also, no reaction products were observed in Al-Si/B{sub 4}C composite coatings. It was found that surface roughness, porosity, bond strength and thermal expansion coefficient of composite coatings decreased with increasing fraction of the boron carbide particle. It was demonstrated that the higher the B{sub 4}C content, the higher the hardness of coatings because the hardness of B{sub 4}C is higher than that of Al-Si.

  5. Metallography and thermal analysis of ceramic nuclear fuels

    International Nuclear Information System (INIS)

    Tebaldi, V.

    1988-01-01

    The book contains two parts: the ceramography laboratory and the thermal treatment laboratory. After general remarks on sintering the first part includes sample preparation for ceramography (grinding, polishing, etching), microscopic examination and quantitative image analysis. The second part deals with temperature measurement, oxide/metal ratio determination, thermogravimetry, differential thermal analysis (DTA), melting point determination and constitution of phase diagrams. Installation of a Pu laboratory, sample decontamination, and research with a microprobe are described. 188 photomicrographs present the microstructure of ceramics based on U, Pu and higher actinides

  6. Alumina-fluorapatite composite coating deposited by atmospheric plasma spraying: An agent of cohesion between bone and prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Ghorbel, Halima Feki, E-mail: ghorbel.halima@yahoo.fr [LCI, Ecole Nationale d' Ingénieurs de Sfax “ENIS”, Soukra 1173-3038, Sfax (Tunisia); LERMPS, Université de Technologie de Belfort-Montbeliard “UTBM”, Belfort 90010 (France); Guidara, Awatef [LCI, Ecole Nationale d' Ingénieurs de Sfax “ENIS”, Soukra 1173-3038, Sfax (Tunisia); Danlos, Yoan [LERMPS, Université de Technologie de Belfort-Montbeliard “UTBM”, Belfort 90010 (France); Bouaziz, Jamel [LCI, Ecole Nationale d' Ingénieurs de Sfax “ENIS”, Soukra 1173-3038, Sfax (Tunisia); Coddet, Christian [LERMPS, Université de Technologie de Belfort-Montbeliard “UTBM”, Belfort 90010 (France)

    2017-02-01

    In order to remedy the poor biological and tribological properties of 316 L stainless steel (SS), plasma sprayed bio-ceramic coatings have been widely investigated. In the present study, a small amount of fluorapatite (Fap) was introduced into alumina in order to enhance its bioactivity. The powder feedstock was sprayed on 316 L substrate by Atmospheric Plasma Spraying (APS) technology. The roughness profiles and average roughness values were determined using 3D profilometry. The cross sectional morphologies of the coatings were examined by scanning electron microscopy (SEM). Adhesive strength, micro-hardness and tribological properties were also examined. Experimental results revealed that Al{sub 2}O{sub 3}/Fap coating showed a good microhardness property revealing that the calcium aluminates were quite effective in improving the Fap mechanical behavior. The tribological characteristics of both alumina and alumina-Fap coating were also compared to those of classical hydroxyapatite (Hap) coatings as reported in the literature. The main finding of this work was that Fap coating can contribute to the cohesion between bone and prostheses and thus ensure a more durable and reliable prostheses. - Highlights: • This research addresses tissue engineering and novel biomaterials consisting of combination of Al{sub 2}O{sub 3} and Fap. • The addition of Fap to alumina results in higher coating porosity, which may be beneficial for the mechanical fixture by bone ingrowth. • Adhesion strength of the alumina ceramic coating is improved by the Fap addition • The presence of CaO in the synthesized Fap may help in improving the mechanical resistance through to formation of the calcium aluminates.

  7. Alumina-fluorapatite composite coating deposited by atmospheric plasma spraying: An agent of cohesion between bone and prostheses

    International Nuclear Information System (INIS)

    Ghorbel, Halima Feki; Guidara, Awatef; Danlos, Yoan; Bouaziz, Jamel; Coddet, Christian

    2017-01-01

    In order to remedy the poor biological and tribological properties of 316 L stainless steel (SS), plasma sprayed bio-ceramic coatings have been widely investigated. In the present study, a small amount of fluorapatite (Fap) was introduced into alumina in order to enhance its bioactivity. The powder feedstock was sprayed on 316 L substrate by Atmospheric Plasma Spraying (APS) technology. The roughness profiles and average roughness values were determined using 3D profilometry. The cross sectional morphologies of the coatings were examined by scanning electron microscopy (SEM). Adhesive strength, micro-hardness and tribological properties were also examined. Experimental results revealed that Al 2 O 3 /Fap coating showed a good microhardness property revealing that the calcium aluminates were quite effective in improving the Fap mechanical behavior. The tribological characteristics of both alumina and alumina-Fap coating were also compared to those of classical hydroxyapatite (Hap) coatings as reported in the literature. The main finding of this work was that Fap coating can contribute to the cohesion between bone and prostheses and thus ensure a more durable and reliable prostheses. - Highlights: • This research addresses tissue engineering and novel biomaterials consisting of combination of Al 2 O 3 and Fap. • The addition of Fap to alumina results in higher coating porosity, which may be beneficial for the mechanical fixture by bone ingrowth. • Adhesion strength of the alumina ceramic coating is improved by the Fap addition • The presence of CaO in the synthesized Fap may help in improving the mechanical resistance through to formation of the calcium aluminates

  8. 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

  9. Plasma sprayed rutile titania-nanosilver antibacterial coatings

    International Nuclear Information System (INIS)

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

    2015-01-01

    Graphical abstract: - Highlights: • TiO_2/Ag feedstock powders containing 1–10,000 ppm silver nanoparticles were double sintered and deposited by plasma spray. • TiO_2/Ag coatings were composed of pure rutile phase and homogeneously-distributed metallic silver. • TiO_2/Ag coatings with more than 10 ppm silver nanoparticles exhibited strong antibacterial activity against E. coli and S. aureus. - Abstract: Rutile titania (TiO_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_2 coatings. In the study, titania-nanosilver (TiO_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_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_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_2/Ag coatings and no crystalline changed happened in the TiO_2 structure. The reduction ratios on the TiO_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_2/Ag coatings with 100–1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO_2/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the antibacterial properties of TiO_2/Ag coatings were discussed with

  10. Interaction of plasma-sprayed YBa/sub y/Cu/sub 3/0/sub x/ coatings with alumina substrates

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, C; Parent, L; Dallaire, S; Champagne, B

    1989-01-01

    Superconducting YBa/sub 2/Cu/sub 3/O/sub x/ coatings can be obtained by plasma spraying. Since the as-sprayed coatings do not have an appropriate crystalline structure and are not superconducting, a thermal treatment must be done for crystallizing them in the appropriate YBa/sub 2/Cu/sub 3/O/sub x/ phase. During heat treatment, reactions between the substrate and coating occur and in some cases, may prevent superconducting properties to be obtained. In the present study, YBa/sub 2/Cu/sub 3/O sub/x/ coatings have been deposited on alumina substrates by plasma spraying and heat treated under flowing oxygen at 950/sup 0/C for different periods of time. The modification in coating microstructure has been investigated after different heat treatments. A degradation mechanism of superconducting coatings is proposed. 14 refs., 7 figs., 2 tabs.

  11. Molybdenum plasma spray powder, process for producing said powder, and coating made therefrom

    International Nuclear Information System (INIS)

    Lafferty, W.D.; Cheney, R.F.; Pierce, R.H.

    1979-01-01

    Plasma spray powders of molybdenum particles containing 0.5 to 15 weight percent oxygen and obtained by reacting molybdenum particles with oxygen or oxides in a plasma, form plasma spray coatings exhibiting hardness comparable to flame sprayed coatings formed from molybdenum wire and plasma coatings of molybdenum powders. Such oxygen rich molybdenum powders may be used to form wear resistant coatings, such as for piston rings. (author)

  12. Induction plasma-sprayed photocatalytically active titania coatings and their characterisation by micro-Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Burlacov, I.; Jirkovský, Jaromír; Muller, M.; Heimann, R. B.

    2006-01-01

    Roč. 201, 1-2 (2006), s. 255-264 ISSN 0257-8972 Grant - others:European Communities(XE) EVKI-2002-30025 Institutional research plan: CEZ:AV0Z40400503 Source of funding: R - rámcový projekt EK Keywords : titania (anatase) coatings * induction plasma spraying * suspension plasma spraying * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 1.559, year: 2006

  13. X-ray structural analysis of plasma sprayed europium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Gorshkov, B.N.; Loskutov, V.S.; Gavrish, A.A.; Shakh, G.E.

    1981-12-01

    An X-ray structure microanalysis is made for europium oxide powder produced by sintering and plasmic spheroidization for plasma spraying. The technique of concern is shown not to alter chemical composition of the powder. It is stated that a rise in the plasma jet enthalpy while spraying does not result in dissociation of europium oxide and its interaction with the plasma flux. The coating (to 15.2 kWxs/g) is found to have only a high-temperature (monoclinic) europium oxide phase and there appears a low-temperature (cubic) phase with a subsequent increase in the enthalpy. The plasma jet enthalpy increasing the grain size and the crystal lattice c parameter of the sprayed europium oxide are shown to decrease; the a parameter reduces with an enthalpy growth to 16.2 kW s/g and then smoothly increases with the enthalpy further growth. It is noticed that the europium oxide coating does not interact with an aluminium D16 alloy substrate.

  14. Plasma Sprayed Hydroxyapatite Coatings: Influence of Spraying Power on Microstructure

    International Nuclear Information System (INIS)

    Mohd, S. M.; Abd, M. Z.; Abd, A. N.

    2010-01-01

    The plasma sprayed hydroxyapatite (HA) coatings are used on metallic implants to enhance the bonding between the implant and bone in human body. The coating process was implemented at different spraying power for each spraying condition. The coatings formed from a rapid solidification of molten and partly molten particles that impact on the surface of substrate at high velocity and high temperature. The study was concentrated on different spraying power that is between 23 to 31 kW. The effect of different power on the coatings microstructure was investigated using scanning electron microscope (SEM) and phase composition was evaluated using X-ray diffraction (XRD) analysis. The coatings surface morphology showed distribution of molten, partially melted particles and some micro-cracks. The produced coatings were found to be porous as observed from the cross-sectional morphology. The coatings XRD results indicated the presence of crystalline phase of HA and each of the patterns was similar to the initial powder. Regardless of different spraying power, all the coatings were having similar XRD patterns.

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

    International Nuclear Information System (INIS)

    Tang, Dapei

    2015-01-01

    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. (paper)

  16. Numerical Coupling of the Particulate Phase to the Plasma Phase in Modeling of Multi-Arc Plasma Spraying

    International Nuclear Information System (INIS)

    Bobzin, K.; Öte, M.

    2017-01-01

    Inherent to Euler-Lagrange formulation, which can be used in order to describe the particle behavior in plasma spraying, particle in-flight characteristics are determined by calculating the impulse, heat and mass transfer between the plasma jet and individual powder particles. Based on the assumption that the influence of the particulate phase on the fluid phase is insignificant, impulse, heat and mass transfer from particles to the plasma jet can be neglected using the so-called numerical approach of “one-way coupling”. On the other hand, so-called “two-way coupling” considers the two-sided transfer between both phases. The former is a common simplification used in the literature to describe the plasma-particle interaction in thermal spraying. This study focuses on the significance of this simplification on the calculated results and shows that the use of this simplification leads to significant errors in calculated plasma and particle in-flight characteristics in three-cathode plasma spraying process. (paper)

  17. Aging of vacuum plasma sprayed MCrAlY protective layers and their interaction with nickel- and cobalt-based γ/γ'-superalloys

    International Nuclear Information System (INIS)

    Terberger, Philipp J.

    2015-01-01

    γ/γ' single crystal superalloys with plasma-sprayed thermal barrier coating systems are used as turbine rotor blades in gas turbines if the blades are exposed to high temperatures and high mechanical loads. A bond coat (BC) is part of the thermal barrier coating system. It protects the substrate from oxidation and ensures good bonding of the ceramic coating that serves as a thermal insulator. MCrAlY (M=Ni,Co) alloys are commonly used as BCs. They form a protective Al 2 O 3 layer. This study investigates four different vacuum plasma-sprayed MCrAlY BCs with and without Re after thermal treatment of up to 1000 h at 1044 C in air. The employed substrates are the Ni-based superalloy ERBO1 and the novel Co-based γ/γ' superalloy ERBOCo-1. Additionally, the ternary γ/γ' alloy Co-9Al-9W (in at.%) was aged with a BC for up to 500 h at 900 C. Up to now little is known about the interaction of the Co-based substrates and the BCs. Oxidation and Al depletion of the BC as well as the interdiffusion of BCs and substrates are analysed primarily on the basis of SEM/EDX and XRD. The effect of Y and Hf on the microstructure of the oxide scale is discussed. Rate constants show that Hf results in higher oxidation rates while Re slows down the oxidation. The influence of the alloying elements on the BC microstructure is described. For example, Co prevents the formation of γ' phase, Re slows down diffusion and results in the formation of brittle phases. The choice of substrate material has no measurable influence on the oxidation. Qualitative and quantitative analysis of the interdiffusion zone (IDZ) shows that the choice of substrate surface pre-treatment (grit blasting or grinding) has a major influence on the interdiffusion behaviour with the BC. Grinding results in a thinner IDZ and fewer topologically closed packed (TCP) phases. The reason for this is the recrystallisation of the single crystal substrate. A study of the influence of the substrate crystal

  18. Deposition stress effects on the life of thermal barrier coatings on burner rigs

    Science.gov (United States)

    Watson, J. W.; Levine, S. R.

    1984-01-01

    A study of the effect of plasma spray processing parameters on the life of a two layer thermal barrier coating was conducted. The ceramic layer was plasma sprayed at plasma arc currents of 900 and 600 amps onto uncooled tubes, cooled tubes, and solid bars of Waspalloy in a lathe with 1 or 8 passes of the plasma gun. These processing changes affected the residual stress state of the coating. When the specimens were tested in a Mach 0.3 cyclic burner rig at 1130 deg C, a wide range of coating lives resulted. Processing factors which reduced the residual stress state in the coating, such as reduced plasma temperature and increased heat dissipation, significantly increased coating life.

  19. Impact of impurity content on the sintering resistance and phase stability of dysprosia- and yttria-stabilized zirconia thermal barrier coatings

    Czech Academy of Sciences Publication Activity Database

    Curry, N.; Janikowski, W.; Pala, Zdeněk; Vilémová, Monika; Markocsan, N.

    2014-01-01

    Roč. 23, 1-2 (2014), s. 160-169 ISSN 1059-9630. [International Thermal Spray Conference (ITSC2013). Busan, 13.05.2013-15.05.2013] Institutional support: RVO:61389021 Keywords : atmospheric plasma spray (APS) * thermal and phase stability of coatings * thermal barrier coatings (TBCs) * thermal conductivity * zirconia Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.344, year: 2014 http://link.springer.com/article/10.1007%2Fs11666-013-0014-9/fulltext.html

  20. Glass-ceramic hermetic seals to high thermal expansion metals

    Science.gov (United States)

    Kramer, D.P.; Massey, R.T.

    1987-04-28

    A process for forming glass-ceramic materials from an alkaline silica-lithia glass composition comprising 60-72 mole-% SiO/sub 2/, 18-27 mole-% Li/sub 2/O, 0-5 mole-% Al/sub 2/O/sub 3/, 0-6 mole-% K/sub 2/O, 0-3 mole-% B/sub 2/O/sub 3/, and 0.5-2.5 mole-% P/sub 2/O/sub 5/, which comprises heating said glass composition at a first temperature within the 950-1050/degree/C range for 5-60 minutes, and then at a devitrification temperature within the 700-900/degree/C range for about 5-300 minutes to obtain a glass-ceramic having a thermal expansion coefficient of up to 210 x 10/sup /minus/7///degree/C. These ceramics form strong, hermetic seals with high expansion metals such as stainless steel alloys. An intermediate nucleation heating step conducted at a temperature within the range of 675-750/degree/C for 10-120 minutes may be employed between the first stage and the devitrification stage. 1 fig., 2 tabs.

  1. Thermal expansion of ceramic samples containing natural zeolite

    Science.gov (United States)

    Sunitrová, Ivana; Trník, Anton

    2017-07-01

    In this study the thermal expansion of ceramic samples made from natural zeolite is investigated. Samples are prepared from the two most commonly used materials in ceramic industry (kaolin and illite). The first material is Sedlec kaolin from Czech Republic, which contains more than 90 mass% of mineral kaolinite. The second one is an illitic clay from Tokaj area in Hungary, which contains about 80 mass% of mineral illite. Varying amount of the clay (0 % - 50 %) by a natural zeolite from Nižný Hrabovec (Slovak Republic), containing clinoptilolite as major mineral phase is replaced. The measurements are performed on cylindrical samples with a diameter 14 mm and a length about 35 mm by a horizontal push - rod dilatometer. Samples made from pure kaolin, illite and zeolite are also subjected to this analysis. The temperature regime consists from linear heating rate of 5 °C/min from 30 °C to 1100 °C. The results show that the relative shrinkage of ceramic samples increases with amount of zeolite in samples.

  2. Effective thermal conductivity of advanced ceramic breeder pebble beds

    Energy Technology Data Exchange (ETDEWEB)

    Pupeschi, S., E-mail: simone.pupeschi@kit.edu; Knitter, R.; Kamlah, M.

    2017-03-15

    As the knowledge of the effective thermal conductivity of ceramic breeder pebble beds under fusion relevant conditions is essential for the development of solid breeder blanket concepts, the EU advanced and reference lithium orthosilicate material were investigated with a newly developed experimental setup based on the transient hot wire method. The effective thermal conductivity was investigated in the temperature range RT–700 °C. Experiments were performed in helium and air atmospheres in the pressure range 0.12–0.4 MPa (abs.) under a compressive load up to 6 MPa. Results show a negligible influence of the chemical composition of the solid material on the bed’s effective thermal conductivity. A severe reduction of the effective thermal conductivity was observed in air. In both atmospheres an increase of the effective thermal conductivity with the temperature was detected, while the influence of the compressive load was found to be small. A clear dependence of the effective thermal conductivity on the pressure of the filling gas was observed in helium in contrast to air, where the pressure dependence was drastically reduced.

  3. Plasma-Sprayed LSM Protective Coating on Metallic Interconnect of SOFC

    Directory of Open Access Journals (Sweden)

    Jia-Wei Chen

    2017-12-01

    Full Text Available In this study, a (La0.8Sr0.20.98MnO3 protective layer was prepared on the C276, Crofer22 APU, SUS304, and SUS430 alloys by the atmospheric plasma spraying technique (APS. The oxidation behavior and electrical property of these metal alloys have been investigated isothermally at 800 °C in air for up to 300 h. Results showed that the ferritic steels transform into MnCr2O4 spinels and a Cr2O3 layer during isothermal oxidation. The C276 alloy formed NiCr2O4 and FeCr2O4 layers; these are protective and act as an effective barrier against chromium migration into the outer oxide layer, and the alloy demonstrated good oxidation resistance and a reasonable match to the coefficient of thermal expansion of the substrate and a low-oxide scale area-specific resistance. The ASR effects on the formation of oxide scale have been investigated, and the ASR of coated samples was below 0.024 Ω·cm2. It has good electrical conductivity for SOFC in long-term use.

  4. Hot corrosion behavior of plasma-sprayed partially stabilized zirconia coatings in a lithium molten salt

    International Nuclear Information System (INIS)

    Cho, Soo Haeng; Hong, Sun Seok; Kang, Dae Seong; Park, Byung Heong; Hur, Jin Mok; Lee, Han Soo

    2008-01-01

    The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. It is essential to choose the optimum material for the process equipment handling molten salt. IN713LC is one of the candidate materials proposed for application in electrolytic reduction process. In this study, Yttria-Stabilized Zirconia (YSZ) top coat was applied to a surface of IN713LC with an aluminized metallic bond coat by an optimized plasma spray process, and were investigated the corrosion behavior at 675 .deg. C for 216 hours in the molten salt LiCl-Li 2 O under an oxidizing atmosphere. The as-coated and tested specimens were examined by OM, SEM/EDS and XRD, respectively. The bare superalloy reveals obvious weight loss, and the corrosion layer formed on the surface of the bare superalloy was spalled due to the rapid scale growth and thermal stress. The top coatings showed a much better hot-corrosion resistance in the presence of LiCl-Li 2 O molten salt when compared to those of the uncoated superalloy and the aluminized bond coatings. These coatings have been found to be beneficial for increasing to the hot-corrosion resistance of the structural materials for handling high temperature lithium molten salts

  5. Impact of plasma-sprayed metal particles on hot and cold glass surfaces

    International Nuclear Information System (INIS)

    McDonald, A.; Lamontagne, M.; Moreau, C.; Chandra, S.

    2006-01-01

    Plasma-sprayed molten molybdenum and amorphous steel particles (38-55 μm diameter) were photographed during impact (velocity 120-200 m/s) and spreading on a smooth glass surface that was maintained at either room temperature or 400 deg. C. Droplets approaching the surface were identified by a photodetector and after a known delay, a 5-ns laser pulse was triggered to illuminate the spreading splat and photograph it with a charge-coupled device (CCD) camera. A rapid two-color pyrometer was used to collect thermal radiation from particles during flight and impact to follow the evolution of their temperature and size. Particles that impacted the surface at room temperature ruptured and splashed, leaving a small central solidified core on the substrate. On a surface held at 400 deg. C, there was no splashing and a circular, disk-like splat remained on the surface. Splats on a glass surface held at room temperature had a maximum spread diameter almost three times that on a hot surface. A simple analysis was done to estimate the area of the splat in contact with the non-heated glass surface during spreading. The analysis supports the hypothesis that only a portion of the splat is in good contact with the surface at room temperature, while the rest of the fluid is separated from the substrate by a gas barrier

  6. Fabrication of gas turbine water-cooled composite nozzle and bucket hardware employing plasma spray process

    Science.gov (United States)

    Schilke, Peter W.; Muth, Myron C.; Schilling, William F.; Rairden, III, John R.

    1983-01-01

    In the method for fabrication of water-cooled composite nozzle and bucket hardware for high temperature gas turbines, a high thermal conductivity copper alloy is applied, employing a high velocity/low pressure (HV/LP) plasma arc spraying process, to an assembly comprising a structural framework of copper alloy or a nickel-based super alloy, or combination of the two, and overlying cooling tubes. The copper alloy is plamsa sprayed to a coating thickness sufficient to completely cover the cooling tubes, and to allow for machining back of the copper alloy to create a smooth surface having a thickness of from 0.010 inch (0.254 mm) to 0.150 inch (3.18 mm) or more. The layer of copper applied by the plasma spraying has no continuous porosity, and advantageously may readily be employed to sustain a pressure differential during hot isostatic pressing (HIP) bonding of the overall structure to enhance bonding by solid state diffusion between the component parts of the structure.

  7. Wear behaviour of plasma-sprayed AlSi/B4C composite coatings

    International Nuclear Information System (INIS)

    Sarikaya, Ozkan; Anik, Selahaddin; Celik, Erdal; Okumus, S. Cem; Aslanlar, Salim

    2007-01-01

    This paper describes the wear behaviour of AlSi/B 4 C composite coatings with 0-25 wt% B 4 C particles for diesel engine motors. These coatings were successfully fabricated on AlSi substrates using an atmospheric plasma spray technique. The produced samples were characterized by means of an optical microscope, scanning electron microscope and microhardness tester. The obtained results pointed out that an increase of B 4 C particles in AlSi coatings was caused on the rising of the microhardness values and the decrease of the thermal expansion coefficient of the coatings. The friction and wear experiments were performed under dry conditions using a ball-on-dics configuration against WC/Co counter material for different loads. It was concluded that wear resistance of the coatings produced using B 4 C powders is greatly improved compared with the substrate material. The highest wear resistance of the coatings were also determined in the 20% B 4 C coating

  8. Ballistic Performance of Porous-Ceramic, Thermal-Protection-Systems

    Science.gov (United States)

    Christiansen, E. L.; Davis, B. A.; Miller, J. E.; Bohl, W. E.; Foreman, C. D.

    2009-01-01

    Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Space Shuttle and are currently being proposed for the next generation of manned spacecraft, Orion. These materials insulate the structural components of a spacecraft against the intense thermal environments of atmospheric reentry. Furthermore, these materials are also highly exposed to space environmental hazards like meteoroid and orbital debris impacts. This paper discusses recent impact testing up to 9 km/s, and the findings of the influence of material equation-of-state on the simulation of the impact event to characterize the ballistic performance of these materials. These results will be compared with heritage models1 for these materials developed from testing at lower velocities. Assessments of predicted spacecraft risk based upon these tests and simulations will also be discussed.

  9. Epitaxial Growth and Cracking Mechanisms of Thermally Sprayed Ceramic Splats

    Science.gov (United States)

    Chen, Lin; Yang, Guan-jun

    2018-02-01

    In the present study, the epitaxial growth and cracking mechanisms of thermally sprayed ceramic splats were explored. We report, for the first time, the epitaxial growth of various splat/substrate combinations at low substrate temperatures (100 °C) and large lattice mismatch (- 11.26%). Our results suggest that thermal spray deposition was essentially a liquid-phase epitaxy, readily forming chemical bonding. The interface temperature was also estimated. The results convincingly demonstrated that atoms only need to diffuse and rearrange over a sufficiently short range during extremely rapid solidification. Concurrently, severe cracking occurred in the epitaxial splat/substrate systems, which indicated high tensile stress was produced during splat deposition. The origin of the tensile stress was attributed to the strong constraint of the locally heated substrate by its cold surroundings.

  10. Nanostructured glass–ceramic coatings for orthopaedic applications

    Science.gov (United States)

    Wang, Guocheng; Lu, Zufu; Liu, Xuanyong; Zhou, Xiaming; Ding, Chuanxian; Zreiqat, Hala

    2011-01-01

    Glass–ceramics have attracted much attention in the biomedical field, as they provide great possibilities to manipulate their properties by post-treatments, including strength, degradation rate and coefficient of thermal expansion. In this work, hardystonite (HT; Ca2ZnSi2O7) and sphene (SP; CaTiSiO5) glass–ceramic coatings with nanostructures were prepared by a plasma spray technique using conventional powders. The bonding strength and Vickers hardness for HT and SP coatings are higher than the reported values for plasma-sprayed hydroxyapatite coatings. Both types of coatings release bioactive calcium (Ca) and silicon (Si) ions into the surrounding environment. Mineralization test in cell-free culture medium showed that many mushroom-like Ca and phosphorus compounds formed on the HT coatings after 5 h, suggesting its high acellular mineralization ability. Primary human osteoblasts attach, spread and proliferate well on both types of coatings. Higher proliferation rate was observed on the HT coatings compared with the SP coatings and uncoated Ti-6Al-4V alloy, probably due to the zinc ions released from the HT coatings. Higher expression levels of Runx2, osteopontin and type I collagen were observed on both types of coatings compared with Ti-6Al-4V alloy, possibly due to the Ca and Si released from the coatings. Results of this study point to the potential use of HT and SP coatings for orthopaedic applications. PMID:21292725

  11. Plasma-sprayed titanium coating to polyetheretherketone improves the bone-implant interface.

    Science.gov (United States)

    Walsh, William R; Bertollo, Nicky; Christou, Chrisopher; Schaffner, Dominik; Mobbs, Ralph J

    2015-05-01

    Rapid and stable fixation at the bone-implant interface would be regarded as one of the primary goals to achieve clinical efficacy, regardless of the surgical site. Although mechanical and physical properties of polyetheretherketone (PEEK) provide advantages for implant devices, the hydrophobic nature and the lack of direct bone contact remains a limitation. To examine the effects of a plasma-sprayed titanium coated PEEK on the mechanical and histologic properties at the bone-implant interface. A preclinical laboratory study. Polyetheretherketone and plasma-sprayed titanium coated PEEK implants (Ti-bond; Spinal Elements, Carlsbad, CA, USA) were placed in a line-to-line manner in cortical bone and in a press-fit manner in cancellous bone of adult sheep using an established ovine model. Shear strength was assessed in the cortical sites at 4 and 12 weeks, whereas histology was performed in cortical and cancellous sites at both time points. The titanium coating dramatically improved the shear strength at the bone-implant interface at 4 weeks and continued to improve with time compared with PEEK. Direct bone ongrowth in cancellous and cortical sites can be achieved using a plasma-sprayed titanium coating on PEEK. Direct bone to implant bonding can be achieved on PEEK in spite of its hydrophobic nature using a plasma-sprayed titanium coating. The plasma-sprayed titanium coating improved mechanical properties in the cortical sites and the histology in cortical and cancellous sites. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Effect of Liquid Phase Content on Thermal Conductivity of Hot-Pressed Silicon Carbide Ceramics

    International Nuclear Information System (INIS)

    Lim, Kwang-Young; Jang, Hun; Lee, Seung-Jae; Kim, Young-Wook

    2015-01-01

    Silicon carbide (SiC) is a promising material for Particle-Based Accident Tolerant (PBAT) fuel, fission, and fusion power applications due to its superior physical and thermal properties such as low specific mass, low neutron cross section, excellent radiation stability, low coefficient of thermal expansion, and high thermal conductivity. Thermal conductivity of PBAT fuel is one of very important factors for plant safety and energy efficiency of nuclear reactors. In the present work, the effect of Y 2 O 3 -Sc 2 O 3 content on the microstructure and thermal properties of the hot pressed SiC ceramics have been investigated. Suppressing the β to α phase transformation of SiC ceramics is beneficial in increasing the thermal conductivity of liquid-phase sintered SiC ceramics. Developed SiC ceramics with Y 2 O 3 -Sc 2 O 3 additives are very useful for thermal conductivity on matrix material of the PBAT fuel

  13. Thermal shock testing of ceramics with pulsed laser irradiation

    International Nuclear Information System (INIS)

    Benz, R.; Naoumidis, A.; Nickel, H.

    1986-04-01

    Arguments are presented showing that the resistance to thermal stressing (''thermal shock'') under pulsed thermal energy deposition by various kinds of beam irradiations is approximately proportional to Φ a √tp, where Φ a is the absorbed power density and tp is the pulse length, under conditions of diffusivity controlled spreading of heat. In practical beam irradiation testing, incident power density, Φ, is reported. To evaluate the usefulness of Φ√tp as an approximation to Φ a √tp, damage threshold values are reviewed for different kinds of beams (electron, proton, and laser) for a range of tp values 5x10 -6 to 2 s. Ruby laser beam irradiation tests were made on the following ceramics: AlN, BN, graphite, αSiC, β-SiC coated graphites, (α+β)Si 3 N 4 , CVD (chemical vapor deposition) TiC coated graphite, CVD TiC coated Mo, and CVD TiN coated IN 625. The identified failure mechanisms are: 1. plastic flow followed by tensile and bend fracturing, 2. chemical decomposition, 3. melting, and 4. loss by thermal spallation. In view of the theoretical approximations and the neglect of reflection losses there is reasonable accord between the damage threshold Φ√tp values from the laser, electron, and proton beam tests. (orig./IHOE)

  14. 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.

  15. Resonant mode for a dc plasma spray torch by means of pressure–voltage coupling: application to synchronized liquid injection

    International Nuclear Information System (INIS)

    Krowka, J; Rat, V; Coudert, J F

    2013-01-01

    Electric arc instabilities in dc plasma torches result in non-homogeneous treatment of nanosized solid particles injected into the plasma jets. In the particular case of suspension plasma spraying, large discrepancies in the particles trajectories and thermal histories make the control of coating properties more difficult to achieve. In this paper, a new approach of arc dynamics highlights the existence of different resonant modes and the possibility of their coupling. This study leads us to design a special plasma torch working in a very regular pulsed regime. Then, an innovative injection system based on the drop-on-demand method synchronized with the plasma oscillations is presented as an efficient method to control the dynamics of plasma/particles interactions. (paper)

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

    International Nuclear Information System (INIS)

    You, J.H.; Hoeschen, 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

  17. 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.

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

    International Nuclear Information System (INIS)

    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

  19. Thermal compatibility of dental ceramic systems using cylindrical and spherical geometries

    Science.gov (United States)

    DeHoff, Paul H.; Barrett, Allyson A.; Lee, Robert B.; Anusavice, Kenneth J.

    2009-01-01

    Objective To test the hypothesis that bilayer ceramic cylinders and spheres can provide valid confirmation of thermal incompatibility stresses predicted by finite element analyses. Methods A commercial core ceramic and an experimental core ceramic were used to fabricate open-ended cylinders and core ceramic spheres. The core cylinders and spheres were veneered with one of four commercial dental ceramics representing four thermally compatible groups and four thermally incompatible groups. Axisymmetric thermal and viscoelastic elements in the ANSYS finite element program were used to calculate temperatures and stresses for each geometry and ceramic combination. This process required a transient heat transfer analysis for each combination to determine input temperatures for the structural model. Results After fabrication, each specimen was examined visually using fiberoptic transillumination for evidence of cracking. There were 100% failures of the thermally incompatible cylinders while none of the thermally compatible combinations failed. Among the spheres, 100% of the thermally incompatible systems failed, 16% of one of the thermally compatible systems failed, and none of the remaining compatible combinations failed. The calculated stress values were in general agreement with the experimental observations, i.e., low residual stresses for the specimens that did not fail and high residual stresses for the specimens that did fail. Significance Simple screening geometries can be used to identify highly incompatible ceramic combinations, but they do not identify marginally incompatible systems. PMID:17949805

  20. Radiation properties modeling for plasma-sprayed-alumina-coated rough surfaces for spacecrafts

    International Nuclear Information System (INIS)

    Li, R.M.; Joshi, Sunil C.; Ng, H.W.

    2006-01-01

    Spacecraft thermal control materials (TCMs) play a vital role in the entire service life of a spacecraft . Most of the conventional TCMs degrade in the harmful space environment . In the previous study, plasma sprayed alumina (PSA) coating was established as a new and better TCM for spacecrafts, in view of its stability and reliability compared to the traditional TCMs . During the investigation, the surface roughness of PSA was found important, because the roughness affects the radiative heat exchange between the surface and its surroundings. Parameters such as root-mean-square roughness cannot properly evaluate surface roughness effects on radiative properties of opaque surfaces . Some models have been developed earlier to predict the effects, such as Davies' model , Tang and Buckius's statistical geometric optics model . However, they are valid only in their own specific situations. In this paper, an energy absorption geometry model was developed and applied to investigate the roughness effects with the help of 2D surface profile of PSA coated substrate scanned at micron level. This model predicts effective normal solar absorptance (α ne ) and effective hemispherical infrared emittance (ε he ) of a rough PSA surface. These values, if used in the heat transfer analysis of an equivalent, smooth and optically flat surface, lead to the prediction of the same rate of heat exchange and temperature as that of for the rough PSA surface. The model was validated through comparison between a smooth and a rough PSA coated surfaces. Even though not tested for other types of materials, the model formulation is generic and can be used to incorporate the rough surface effects for other types of thermal coatings, provided the baseline values of normal solar absorptance (α n ) and hemispherical infrared emittance (ε h ) are available for a generic surface of the same material

  1. Effect of plasma spraying modes on material properties of internal combustion engine cylinder liners

    Science.gov (United States)

    Timokhova, O. M.; Burmistrova, O. N.; Sirina, E. A.; Timokhov, R. S.

    2018-03-01

    The paper analyses different methods of remanufacturing worn-out machine parts in order to get the best performance characteristics. One of the most promising of them is a plasma spraying method. The mathematical models presented in the paper are intended to anticipate the results of plasma spraying, its effect on the properties of the material of internal combustion engine cylinder liners under repair. The experimental data and research results have been computer processed with Statistica 10.0 software package. The pare correlation coefficient values (R) and F-statistic criterion are given to confirm the statistical properties and adequacy of obtained regression equations.

  2. Transformation kinetics in plasma-sprayed barium- and strontium-doped aluminosilicate (BSAS)

    International Nuclear Information System (INIS)

    Harder, B.J.; Faber, K.T.

    2010-01-01

    The hexacelsian-to-celsian phase transformation in Ba 1-x Sr x Al 2 Si 2 O 8 is of interest for environmental barrier coating applications. Plasma-sprayed microstructures were heat treated above 1100 o C and the kinetics of the hexacelsian-to-celsian transformation were quantified. Activation energies for bulk and crushed materials were determined to be ∼340 and ∼500 kJ mol -1 , respectively. X-ray diffraction and electron backscattered diffraction were used to establish how plasma spraying barium- and strontium-doped aluminosilicate effectively reduces the energy required for its transformation.

  3. Investigation on the suitability of plasma sprayed Fe-Cr-Al coatings as tritium permeation barrier

    International Nuclear Information System (INIS)

    Fazio, C.; Serra, E.; Benamati, G.

    1999-01-01

    Results on the fabrication of a tritium permeation barrier by spraying Fe-Cr-Al powders are described. The sprayed coatings were deposited at temperatures below the A c1 temperature of the ferritic-martensitic steel substrate and no post-deposition heat treatment was applied. The aim of the investigation was the determination of the efficiency of the coatings to act as tritium permeation barrier. Metallurgical investigations as well as hydrogen isotope permeation measurements were carried out onto the produced coatings. The depositions were performed on ferritic-martensitic steels by means of three types of spray techniques: high velocity oxy fuel, air plasma spray and vacuum plasma spray. (orig.)

  4. Compatibility tests between Solar Salt and thermal storage ceramics from inorganic industrial wastes

    International Nuclear Information System (INIS)

    Motte, Fabrice; Falcoz, Quentin; Veron, Emmanuel; Py, Xavier

    2015-01-01

    Highlights: • ESEM and XRD characterizations have been performed. • Compatibility of these ceramics with the conventional binary Solar Salt is tested at 500 °C. • Tested ceramics have relevant properties to store thermal energy up to 1000 °C. • Feasibility of using ceramics as filler materials in thermocline is demonstrated. - Abstract: This paper demonstrates the feasibility of using several post-industrial ceramics as filler materials in a direct thermocline storage configuration. The tested ceramics, coming from several industrial processes (asbestos containing waste treatment, coal fired power plants or metallurgic furnaces) demonstrate relevant properties to store thermal energy by sensible heat up to 1000 °C. Thus, they represent at low-cost a promising, efficient and sustainable approach for thermal energy storage. In the present study, the thermo-chemical compatibility of these ceramics with the conventional binary Solar Salt is tested at medium temperature (500 °C) under steady state. In order to determine the feasibility of using such ceramics as filler material, Environmental Scanning Electron Microscopy (ESEM) and X-Ray Diffraction (XRD) characterizations have been performed to check for their chemical and structural evolution during corrosion tests. The final objective is to develop a molten salt thermocline direct storage system using low-cost shaped ceramic as structured filler material. Most of the tested ceramics present an excellent corrosion resistance in molten Solar Salt and should significantly decrease the current cost of concentrated solar thermal energy storage system

  5. Ballistic Performance of Porous-Ceramic, Thermal Protection Systems

    Science.gov (United States)

    Miller, J. E.; Bohl, W. E.; Christiansen, Eric C.; Davis, B. A.; Foreman, C. D.

    2011-01-01

    Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of US manned spacecraft, Orion. These systems insulate reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are highly exposed to space environment hazards like solid particle impacts. This paper discusses impact studies up to 10 km/s on 8 lb/cu ft alumina-fiber-enhanced-thermal-barrier (AETB8) tiles coated with a toughened-unipiece-fibrous-insulation/ reaction-cured-glass layer (TUFI/RCG). A semi-empirical, first principals impact model that describes projectile dispersion is described that provides excellent agreement with observations over a broad range of impact velocities, obliquities and projectile materials. Model extensions to look at the implications of greater than 10 GPa equation of state is also discussed. Predicted penetration probabilities for a vehicle visiting the International Space Station is 60% lower for orbital debris and 95% lower for meteoroids with this model compared to an energy scaled approach.

  6. Application of Hot-wire Method for Measuring Thermal Conductivity of Fine Ceramics

    Directory of Open Access Journals (Sweden)

    Shangxi WANG

    2016-11-01

    Full Text Available Ceramic substrate is preferred in high density packaging due to its high electrical resistivity and moderate expansion coefficient. The thermal conductivity is a key parameter for packaging substrates. There are two common methods to measure the thermal conductivity, which are the hot-wire method and the laser-flash method. Usually, the thermal conductivities of porcelain is low and meet the measurement range of hot-wire method, and the measured value by hot-wire method has little difference with that by laser-flash method. In recent years, with the requirement of high-powered LED lighting, some kinds of ceramic substrates with good thermal conductivity have been developed and their thermal conductivity always measured by the means of laser flash method, which needs expensive instrument. In this paper, in order to detect the thermal conductivity of fine ceramic with convenience and low cost, the feasibility of replacing the laser flash method with hot wire method to measure thermal conductivity of ceramic composites was studied. The experiment results showed that the thermal conductivity value of fine ceramics measured by the hot-wire method is severely lower than that by the laser-flash method. However, there is a positive relationship between them. It is possible to measure the thermal conductivity of fine ceramic workpiece instantly by hot-wire method via a correction formula.DOI: http://dx.doi.org/10.5755/j01.ms.22.4.12543

  7. Thermal-Conductivity Studies of Macro-porous Polymer-Derived SiOC Ceramics

    Science.gov (United States)

    Qiu, L.; Li, Y. M.; Zheng, X. H.; Zhu, J.; Tang, D. W.; Wu, J. Q.; Xu, C. H.

    2014-01-01

    A three-dimensional reticular macro-porous SiOC ceramics structure, made of spherical agglomerates, has been thermally characterized using a freestanding sensor-based method. The effective thermal conductivity of the macro-porous SiOC ceramics, including the effects of voids, is found to be to at room temperature, comparable with that of alumina aerogel or carbon aerogel. These results suggest that SiOC ceramics hold great promise as a thermal insulation material for use at high temperatures. The measured results further reveal that the effective thermal conductivity is limited by the low solid-phase volume fraction for the SiOC series processed at the same conditions. For SiOC ceramics processed under different pyrolysis temperatures, the contact condition between neighboring particles in the SiOC networks is another key factor influencing the effective thermal conductivity.

  8. Evaluation of Monolithic Ceramics and Ceramic Thermal Barrier Coatings for Diesel Engine Applications

    National Research Council Canada - National Science Library

    Swab, Jeffrey J

    2001-01-01

    The Metals and Ceramics Research Branch (MCRB) of the Weapons and Materials Research Directorate is providing ceramic material characterization and evaluation to the Tank Automotive Research, Development, and Engineering Center (TARDEC...

  9. 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.

  10. Characterisations Of Al2O3-13% Wt TiO2 Deposition On Mild Steel Via Plasma Spray Method

    International Nuclear Information System (INIS)

    Yusoff, N. H.; Isa, M. C.; Ghazali, M. J.; Muchtar, A.; Forghani, S.; Daud, A. R.

    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 cm 3 /Nm with 4% of porosity.

  11. Mechanical properties of plasma-sprayed layers of aluminium and aluminium alloy on AZ 91

    Czech Academy of Sciences Publication Activity Database

    Kubatík, Tomáš František; Ctibor, Pavel; Mušálek, Radek; Janata, Marek

    2017-01-01

    Roč. 51, č. 2 (2017), s. 323-327 ISSN 1580-2949 R&D Projects: GA ČR(CZ) GP14-31538P Institutional support: RVO:61389021 Keywords : plasma spraying of aluminium * adhesion of coating * wear * magnesium alloy AZ91 Subject RIV: JG - Metallurgy OBOR OECD: Materials engineering Impact factor: 0.436, year: 2016

  12. 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

  13. Superconducting and structural properties of plasma sprayed YBaCuO layers deposited on metallic substrates

    NARCIS (Netherlands)

    Hemmes, Herman K.; Jäger, D; Smithers, M.A.; Smithers, M.; van der Veer, J.; van der Veer, J.M.; Stover, D.; Rogalla, Horst

    1993-01-01

    The properties of plasma sprayed Y-Ba-Cu-O coatings deposited on metallic substrates are studied. Stainless steel, nickel steels and pure nickel are used as substrate. Y-Ba-Cu-O deposited on stainless steel and nickel steel reacts with the substrate. This interaction can be suppressed by using an

  14. Plasma Sprayed Tungsten-based Coatings and their Usage in Edge Plasma Region of Tokamaks

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Weinzettl, Vladimír; Dufková, Edita; Piffl, Vojtěch; Peřina, Vratislav

    2006-01-01

    Roč. 51, č. 2 (2006), s. 179-191 ISSN 0001-7043 Grant - others:Evropská unie EFDA Task TW-5-TVM-PSW (EU – Euratom) Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z10480505 Keywords : plasma sprayed coatings * fusion * plasma facing components * tungsten * tokamak Subject RIV: BL - Plasma and Gas Discharge Physics

  15. Formation of nanocomposite alumina-zirconia-silica ceramics

    Czech Academy of Sciences Publication Activity Database

    Chráska, Tomáš; Klementová, Mariana; Hostomský, Jiří

    2007-01-01

    Roč. 52, č. 4 (2007), s. 331-341 ISSN 0001-7043 R&D Projects: GA AV ČR KAN300430651 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z40320502 Keywords : TEM * sample preparation * plasma spraying * ceramic s Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass

  16. The effect of irradiation of the thermal conductivity of lithium ceramics

    International Nuclear Information System (INIS)

    Ethridge, J.L.; Baker, D.E.

    1987-01-01

    An apparatus for measuring the thermal conductivity of irradiated lithium ceramics to 900 0 C was designed, fabricated, and tested. Special attention was necessary in order to accommodate tritium released during the high-temperature measurements

  17. Plasma Spraying of Silica-Rich Calcined Clay Shale

    Czech Academy of Sciences Publication Activity Database

    Dubský, Jiří; Chráska, Tomáš; Pala, Zdeněk; Nevrlá, Barbara; Chráska, Pavel

    2014-01-01

    Roč. 23, č. 4 (2014), s. 732-741 ISSN 1059-9630 R&D Projects: GA ČR GAP107/12/1922; GA ČR(CZ) GAP108/12/1872 Institutional support: RVO:61389021 Keywords : clay shale * crystallinity * grain size * mullite * water stabilized plasma * x-ray diffraction Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.344, year: 2014 http://link.springer.com/article/10.1007%2Fs11666-014-0076-3

  18. Microstructure Analysis of Laser Remelting for Thermal Barrier Coatings on the Surface of Titanium Alloy

    Directory of Open Access Journals (Sweden)

    Lu Bin

    2016-01-01

    Full Text Available In this paper, the preparation and organization performance of thermal barrier coatings (TCBs on the surface of titanium were studied experimentally. Nanostructured 8 wt% yttria partially stabilized zirconia coatings were deposited by air plasma spraying. The microstructure of nanostructured and the conventional coating was studied after laser remelting. It has shown that formed a network of micro-cracks and pits after laser remelting on nanostructured coatings. With the decrease of the laser scanning speed, mesh distribution of micro cracks was gradually thinning on nanostructured coatings. Compared with conventional ceramic layers, the mesh cracks of nanostructured coating is dense and the crack width is small.

  19. Electrical and thermal properties of lead titanate glass ceramics

    International Nuclear Information System (INIS)

    Shankar, J.; Deshpande, V.K.

    2011-01-01

    Glass samples with composition of (50-X)PbO-(25+X)TiO 2 -25B 2 O 3 (where X=0, 5, 10 and 12.5 mol%) were prepared using conventional quenching technique. The glass transition temperature, T g and crystallization temperature T c were determined from the DTA. These glass samples were converted to glass ceramics by following two stage heat treatment schedule. The glass ceramic samples were characterized by XRD, SEM and dielectric constant measurements. The XRD results revealed the formation of ferroelectric lead titanate (PT) as a major crystalline phase in the glass ceramics. The density increases and the CTE decreases for all glass ceramics with increase in X (mol%). This may be attributed to increase in PT phase. The SEM results which show rounded crystallites of lead titanate, also supports other results. Hysteresis loops observed at room temperature confirms the ferroelectric nature of glass ceramics. The optimized glass ceramic sample exhibits high dielectric constant which is of technical importance. -- Research Highlights: →Lead titanate glass ceramics prepared by conventional quenching technique. →Lead titanate is a major crystalline phase in the glass ceramics. →The ferroelectric nature of glass ceramics is confirmed by the hysteresis study. →The high value of ε observed at room temperature is quite promising in the study.

  20. Thermal shock resistance of ceramic fibre composites characterized by non-destructive methods

    Directory of Open Access Journals (Sweden)

    M. Dimitrijević

    2008-12-01

    Full Text Available Alumina based ceramic fibres and alumina based ceramic were used to produce composite material. Behaviour of composite ceramics after thermal shock treatments was investigated. Thermal shock of the samples was evaluated using water quench test. Surface deterioration level of samples was monitored by image analysis before and after a number of quenching cycles. Ultrasonic measurements were done on samples after quench tests. Dynamic Young modulus of elasticity and strength degradation were calculated using measured values of ultrasonic velocities. Strengths deterioration was calculated using the non-destructive measurements and correlated to degradation of surface area and number of quenches. The addition of small amount of ceramic fibres improves the strengths and diminishes the loss of mechanical properties of samples during thermal shock experiments.

  1. Environmental/Thermal Barrier Coatings for Ceramic Matrix Composites: Thermal Tradeoff Studies

    Science.gov (United States)

    Murthy, Pappu L. M.; Brewer, David; Shah, Ashwin R.

    2007-01-01

    Recent interest in environmental/thermal barrier coatings (EBC/TBCs) has prompted research to develop life-prediction methodologies for the coating systems of advanced high-temperature ceramic matrix composites (CMCs). Heat-transfer analysis of EBC/TBCs for CMCs is an essential part of the effort. It helps establish the resulting thermal profile through the thickness of the CMC that is protected by the EBC/TBC system. This report documents the results of a one-dimensional analysis of an advanced high-temperature CMC system protected with an EBC/TBC system. The one-dimensional analysis was used for tradeoff studies involving parametric variation of the conductivity; the thickness of the EBC/TBCs, bond coat, and CMC substrate; and the cooling requirements. The insight gained from the results will be used to configure a viable EBC/TBC system for CMC liners that meet the desired hot surface, cold surface, and substrate temperature requirements.

  2. Ceramic Foams from Pre-Ceramic Polymer Routes for Reusable Acreage Thermal Protection System Applications

    Science.gov (United States)

    Stackpoole, Mairead; Chien, Jennifer; Schaeffler, Michelle

    2004-01-01

    Contents include the following: Motivation. Current light weight insulation. Advantages of preceramic-polymer-derived ceramic foams. Rigid insulation materials. Tailor foam microstructures. Experimental approach. Results: sacrificial materials, sacrificial fillers. Comparison of foam microstructures. Density of ceramic foams. Phase evolution and properties: oxidation behavior. mechanical properties, aerothermal performance. Impact damage of microcellular foams. Conclusions.

  3. 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, CaSiO 3 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 CaSiO 3 ceramic (Ca 11 Si 4 B 2 O 22 , 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 CaSiO 3 (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 Ca 11 Si 4 B 2 O 22 coatings possess excellent osteogenic activity and might be a promising candidate for orthopedic applications.

  4. Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former

    Science.gov (United States)

    Medřický, Jan; Curry, Nicholas; Pala, Zdenek; Vilemova, Monika; Chraska, Tomas; Johansson, Jimmy; Markocsan, Nicolaie

    2015-04-01

    Yttria-stabilized zirconia thermal barrier coatings are extensively used in turbine industry; however, increasing performance requirements have begun to make conventional air plasma sprayed coatings insufficient for future needs. Since the thermal conductivity of bulk material cannot be lowered easily; the design of highly porous coatings may be the most efficient way to achieve coatings with low thermal conductivity. Thus the approach of fabrication of coatings with a high porosity level based on plasma spraying of ceramic particles of dysprosia-stabilized zirconia mixed with polymer particles, has been tested. Both polymer and ceramic particles melt in plasma and after impact onto a substrate they form a coating. When the coating is subjected to heat treatment, polymer burns out and a complex structure of pores and cracks is formed. In order to obtain desired porosity level and microstructural features in coatings; a design of experiments, based on changes in spray distance, powder feeding rate, and plasma-forming atmosphere, was performed. Acquired coatings were evaluated for thermal conductivity and thermo-cyclic fatigue, and their morphology was assessed using scanning electron microscopy. It was shown that porosity level can be controlled by appropriate changes in spraying parameters.

  5. Unlubricated Gross Slip Fretting Wear of Metallic Plasma Sprayed Coatings for Ti6A14V Surfaces

    National Research Council Canada - National Science Library

    Hager, Jr., Carl H; Sanders, Jeffrey H; Sharma, Shashi K

    2006-01-01

    ... to simulate cold engine startup. Alternative coatings such as plasma sprayed molybdenum and nickel were also evaluated because of their potential for reducing fretting wear under certain simulated engine conditions...

  6. Properties of tungsten coating deposited onto copper by high-speed atmospheric plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Huang Jianjun, E-mail: huangjj@szu.edu.cn [Applied Low Temperature Plasma Laboratory, College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China); Wang Fan; Liu Ying; Jiang Shishou; Wang Xisheng; Qi Bing; Gao Liang [Applied Low Temperature Plasma Laboratory, College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China)

    2011-07-01

    Tungsten (W) coatings were fabricated on copper (Cu) by high-speed atmospheric plasma spray (HAPS) technique. The properties of the porosity, oxygen content, bonding strength and microhardness were measured. The results obtained indicated that the HAPS-W coating showed good properties particularly in terms of porosity and oxygen content. The porosity of the HAPS-W coating was 2.3% and the distribution of pore size diameter was mainly concentrated in the range of 0.01-1 {mu}m. The oxygen content of the coating measured by means of Nitrogen/Oxygen Determinator was about 0.10 wt.%. These initial results suggest that the HAPS-W coating has achieved the reported properties of the vacuum plasma spray (VPS) W coating. Compared with VPS, HAPS-W technique could provide a convenient and low cost way to obtain adequate W coatings for fusion applications.

  7. Creep behavior of the titanium alloy with zirconia plasma sprayed coating

    International Nuclear Information System (INIS)

    Reis, D.A.P.; Moura Neto, C.; Couto, A.A.

    2009-01-01

    The proposal of this research has been the study of the plasma spayed coating on creep of the Ti-6Al-4V, focusing on the determination of the experimental parameters related to the first and second creep stages. Yttria (8 wt %) stabilized zirconia (YSZ) (Metco 204B-NS) with CoNiCrAlY ( AMDRY 995C) has been plasma sprayed coated on Ti-6Al-4V substrate. Creep tests with constant load had been done on Ti-6Al-4V coated samples, the stress level was from 250 to 319 MPa at 600 deg C. Highest values of t p and the decrease of the second stage rate had shown a better creep resistance on coated sample. Results indicate that the coated sample was greater than uncoated sample, thus the plasma sprayed coating prevent the sample oxidation efficiently. (author)

  8. Low pressure plasma spray deposition of W-Ni-Fe alloy

    International Nuclear Information System (INIS)

    Mutasim, Z.Z.; Smith, R.W.

    1991-01-01

    The production of net shape refractory metal structural preforms are increasing in importance in chemical processing, defense and aerospace applications. Conventional methods become limited for refractory metal processing due to the high melting temperatures and fabrication difficulties. Plasma spray forming, a high temperature process, has been shown to be capable of refractory metal powder consolidation in net shape products. The research reported here has evaluated this method for the deposition of heavy tungsten alloys. Plasma Melted Rapidly Solidified (PMRS) W 8%Ni-2%Fe refractory metal powders were spray formed using vacuum plasma spray (VPS) process and produced 99% dense, fine grain and homogeneous microstructures. In this paper plasma operating parameters (plasma arc gas type and flowrate plasma gun nozzle size and spray distance) were studied and their effects on deposit's density and microstructure are reported

  9. Yb2Si2O7 Environmental Barrier Coatings Deposited by Various Thermal Spray Techniques: A Preliminary Comparative Study

    Science.gov (United States)

    Bakan, Emine; Marcano, Diana; Zhou, Dapeng; Sohn, Yoo Jung; Mauer, Georg; Vaßen, Robert

    2017-08-01

    Dense, crack-free, uniform, and well-adhered environmental barrier coatings (EBCs) are required to enhance the environmental durability of silicon (Si)-based ceramic matrix composites in high pressure, high gas velocity combustion atmospheres. This paper represents an assessment of different thermal spray techniques for the deposition of Yb2Si2O7 EBCs. The Yb2Si2O7 coatings were deposited by means of atmospheric plasma spraying (APS), high-velocity oxygen fuel spraying (HVOF), suspension plasma spraying (SPS), and very low-pressure plasma spraying (VLPPS) techniques. The initial feedstock, as well as the deposited coatings, were characterized and compared in terms of their phase composition. The as-sprayed amorphous content, microstructure, and porosity of the coatings were further analyzed. Based on this preliminary investigation, the HVOF process stood out from the other techniques as it enabled the production of vertical crack-free coatings with higher crystallinity in comparison with the APS and SPS techniques in atmospheric conditions. Nevertheless, VLPPS was found to be the preferred process for the deposition of Yb2Si2O7 coatings with desired characteristics in a controlled-atmosphere chamber.

  10. The Influence of Interface Characteristics on the Adhesion/Cohesion of Plasma Sprayed Tungsten Coatings

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Vilémová, Monika; Mušálek, Radek; Sachr, P.; Horník, J.

    2013-01-01

    Roč. 3, č. 2 (2013), s. 108-125 ISSN 2079-6412 R&D Projects: GA ČR(CZ) GAP108/12/1872; GA MPO FR-TI2/702 Grant - others:EFDA(XE) WP12-MAT-01-HHFM Institutional support: RVO:61389021 Keywords : Tungsten * plasma spraying * adhesion * cohesion * PVD * interlayers Subject RIV: JG - Metallurgy http://www.mdpi.com/2079-6412/3/2/108

  11. Photocatalytic Activity of Titanium Oxide – Iron Oxide Coatings Prepared by Plasma Spraying

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Štengl, Václav; Pala, Zdeněk

    2013-01-01

    Roč. 3, č. 4 (2013), s. 387-400 ISSN 2249-0205 R&D Projects: GA AV ČR IAAX00430803 Institutional support: RVO:61389021 ; RVO:61388980 Keywords : TiO2-Fe2O3 * plasma spraying * spectroscopy * band gap * photocatalysis Subject RIV: JG - Metallurgy; CA - Inorganic Chemistry (UACH-T) http://www.sciencedomain.org/issue.php?iid=242&id=16

  12. Through-thickness Residual Stress Measurement by Neutron Diffraction in Cu+W Plasma Spray Coatings

    Czech Academy of Sciences Publication Activity Database

    Luzin, V.; Matějíček, Jiří; Gnäupel-Herold, T.

    2010-01-01

    Roč. 652, č. 652 (2010), s. 50-56 ISSN 1662-9752. [International Conference on Mechanical Stress Evaluation by Neutrons and Synchrotron Radiation/5th./. Mito, 10.11.2009-12.11.2009] R&D Projects: GA MŠk ME 901 Institutional research plan: CEZ:AV0Z20430508 Keywords : fusion materials * plasma sprayed coatings * residual stress * neutron diffraction Subject RIV: JG - Metallurgy http://www.scientific.net/MSF.652.50

  13. Stresses in plasma-sprayed Cr2O3 coatings measured by neutron diffraction

    Czech Academy of Sciences Publication Activity Database

    Dubský, Jiří; Prask, H. J.; Matějíček, Jiří; Gnäupel-Herold, T.

    2002-01-01

    Roč. 75, - (2002), s. 1-3 ISSN 0947-8396. [International Conference on Neutron Scattreing. Munich, 09.08.2001-13.08.2002] R&D Projects: GA ČR GA106/01/0094 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma sprayed, diffraction Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 2.231, year: 2002

  14. Metallurgical bond between magnesium AZ91 alloy and aluminium plasma sprayed coatings

    Czech Academy of Sciences Publication Activity Database

    Kubatík, Tomáš František; Pala, Zdeněk; Neufuss, Karel; Vilémová, Monika; Mušálek, Radek; Stoulil, J.; Slepička, P.; Chráska, Tomáš

    2015-01-01

    Roč. 282, November (2015), s. 163-170 ISSN 0257-8972 R&D Projects: GA ČR(CZ) GP14-31538P Institutional support: RVO:61389021 Keywords : Plasma spraying * AZ91 magnesium alloy * Aluminium * Metallurgical bond * X-ray diffraction Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 2.139, year: 2015 http://www.sciencedirect.com/science/article/pii/S0257897215303297

  15. Plasma spraying of refractory metals and refractory hard materials. State of the art

    International Nuclear Information System (INIS)

    Eschnauer, H.; Lugscheider, E.; Jaeger, D.

    1989-01-01

    Suitable spraying processes for manufacturing refractory metals, refractory hard materials as well as spray materials with refractory components are the VPS- and IPS-spraying techniques. The advantages of these special spraying process variations are described. The reactive spraying materials are systematically organized. The characteristical properties used in purpose of improving the substrate surfaces are explained. Finally some examples of the latest results of research concerning plasma spraying of reactive materials are shown. 16 refs., 10 figs. (Author)

  16. Development of suspension plasma sprayed alumina coatings with high enthalpy plasma torch

    Czech Academy of Sciences Publication Activity Database

    Tesař, Tomáš; Mušálek, Radek; Medřický, Jan; Kotlan, Jiří; Lukáč, František; Pala, Zdeněk; Ctibor, Pavel; Chráska, Tomáš; Houdková, Š.; Rimal, V.; Curry, N.

    2017-01-01

    Roč. 325, September (2017), s. 277-288 ISSN 0257-8972 R&D Projects: GA ČR GA15-12145S Institutional support: RVO:61389021 Keywords : Suspension plasma spraying * Aluminium oxide * Mechanical properties * Hardness * Adhesion * Wear resistance Subject RIV: JK - Corrosion ; Surface Treatment of Materials OBOR OECD: Coating and films Impact factor: 2.589, year: 2016 http://www.sciencedirect.com/science/article/pii/S0257897217306424

  17. Plasma sprayed manganeseecobalt spinel coatings: Process sensitivity on phase, electrical and protective performance

    Czech Academy of Sciences Publication Activity Database

    Han Jung, S.; Pala, Zdeněk; Sampath, S.

    2016-01-01

    Roč. 304, February (2016), s. 234-243 ISSN 0378-7753 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : Interconnect protection * Cr-poisoning * Manganese cobalt spinel * Electrical conductivity * Plasma spray Subject RIV: JE - Non-nuclear Energetics, Energy Consumption ; Use Impact factor: 6.395, year: 2016 http://www.sciencedirect.com/science/article/pii/S0378775315305383

  18. Thermomechanical and Environmental Durability of Environmental Barrier Coated Ceramic Matrix Composites Under Thermal Gradients

    Science.gov (United States)

    Zhu, Dongming; Bhatt, Ramakrishna T.; Harder, Bryan

    2016-01-01

    This paper presents the developments of thermo-mechanical testing approaches and durability performance of environmental barrier coatings (EBCs) and EBC coated SiCSiC ceramic matrix composites (CMCs). Critical testing aspects of the CMCs will be described, including state of the art instrumentations such as temperature, thermal gradient, and full field strain measurements; materials thermal conductivity evolutions and thermal stress resistance; NDE methods; thermo-mechanical stress and environment interactions associated damage accumulations. Examples are also given for testing ceramic matrix composite sub-elements and small airfoils to help better understand the critical and complex CMC and EBC properties in engine relevant testing environments.

  19. Vacuum Plasma Spraying W-coated Reduced Activation Structural Steels for Fusion Plasma Facing Components

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Sanghoon; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Tungsten (W) and its alloys are considered as candidate materials for plasma facing materials of the first wall and diverter components in fusion reactor systems because of high sputtering resistance and low tritium retention in a fusion environment. Therefore, it is considered that the joining between W and reduced activation structural steels, and its evaluation, are critical issues for the development of fusion reactors. However, the joining between these materials is a very challenging process because of significant differences in their physical properties, particularly the mismatch of coefficients of thermal expansion (CTE). For instance, the CTE of pure W is known to be about 4.3Χ10{sup -6}K{sup -1}; however, that of martensitic steels reaches over three times, about 12-14Χ10{sup -6}K{sup -1} at room temperature even up to 373K. Nevertheless, several joining techniques have been developed for joining between W and structural steels, such as a vapor deposition method, brazing and diffusion bonding. Meanwhile, vacuum plasma spraying (VPS) is supposed to be one of the prospective methods to fabricate a sufficient W layer on the steel substrates because of the coating of a large area with a relatively high fabricating rate. In this study, the VPS method of W powders on reduced activation steels was employed, and its microstructure and hardness distribution were investigated. ODS ferritic steels and F82H steel were coated by VPS-W, and the microstructure and hardness distribution were investigated. A microstructure analysis revealed that pure W was successfully coated on steel substrates by the VPS process without an intermediate layer, in spite of a mismatch of the CTE between dissimilar materials. After neutron irradiation, irradiation hardening significantly occurred in the VPSW. However, the hardening of VPS-W was lesser than that of bulk W irradiated HFIR at 773K. Substrate materials, ODS ferritic steels, and F82H steel, did not show irradiation hardening

  20. Engineered high expansion glass-ceramics having near linear thermal strain and methods thereof

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Steve Xunhu; Rodriguez, Mark A.; Lyon, Nathanael L.

    2018-01-30

    The present invention relates to glass-ceramic compositions, as well as methods for forming such composition. In particular, the compositions include various polymorphs of silica that provide beneficial thermal expansion characteristics (e.g., a near linear thermal strain). Also described are methods of forming such compositions, as well as connectors including hermetic seals containing such compositions.

  1. Evaluating microhardness of plasma sprayed Al2O3 coatings using Vickers indentation technique

    International Nuclear Information System (INIS)

    Yin Zhijian; Tao Shunyan; Zhou Xiaming; Ding Chuanxian

    2007-01-01

    In this work, the microhardness of plasma sprayed Al 2 O 3 coatings was evaluated using the Vickers indentation technique, and the effects of measurement direction, location and applied loads were investigated. The measured data sets were then statistically analysed employing the Weibull distribution to evaluate their variability within the coatings. It was found that the Vickers hardness (VHN) increases with decreasing applied indenter load, which can be explained in terms of Kick's law and the Meyer index k of 1.93, as well as relating to the microstructural characteristics of plasma sprayed coatings and the elastic recovery taking place during indentation. In addition, VHN, measured on the cross section of coatings, was obviously higher than that on its top surface. The obtained Weibull modulus and variation coefficient indicate that the VHN was less variable when measured at a higher applied load and on the cross section of coating. The obvious dependence of the VHN on the specific indentation location within through-thickness direction was also realized. These phenomena described above in this work were related to the special microstructure and high anisotropic behaviour of plasma sprayed coatings

  2. XPS and bioactivity study of the bisphosphonate pamidronate adsorbed onto plasma sprayed hydroxyapatite coatings

    International Nuclear Information System (INIS)

    McLeod, Kate; Kumar, Sunil; Smart, Roger St.C.; Dutta, Naba; Voelcker, Nicolas H.; Anderson, Gail I.; Sekel, Ron

    2006-01-01

    This paper reports the use of X-ray photoelectron spectroscopy (XPS) to investigate bisphosphonate (BP) adsorption onto plasma sprayed hydroxyapatite (HA) coatings commonly used for orthopaedic implants. BPs exhibit high binding affinity for the calcium present in HA and hence can be adsorbed onto HA-coated implants to exploit their beneficial properties for improved bone growth at the implant interface. A rigorous XPS analysis of pamidronate, a commonly used nitrogenous BP, adsorbed onto plasma sprayed HA-coated cobalt-chromium substrates has been carried out, aimed at: (a) confirming the adsorption of this BP onto HA; (b) studying the BP diffusion profile in the HA coating by employing the technique of XPS depth profiling; (c) confirming the bioactivity of the adsorbed BP. XPS spectra of plasma sprayed HA-coated discs exposed to a 10 mM aqueous BP solution (pamidronate) for periods of 1, 2 and 24 h showed nitrogen and phosphorous photoelectron signals corresponding to the BP, confirming its adsorption onto the HA substrate. XPS depth profiling of the 2 h BP-exposed HA discs showed penetration of the BP into the HA matrix to depths of at least 260 nm. The bioactivity of the adsorbed BP was confirmed by the observed inhibition of osteoclast (bone resorbing) cell activity. In comparison to the HA sample, the HA sample with adsorbed BP exhibited a 25-fold decrease in primary osteoclast cells

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    Anatase (A-) TiO 2 is a photocatalytic material that can decompose air-pollutants, acetaldehyde, bacteria, and so on. In this study, three kinds of powder (A-TiO 2 without HAp, TiO 2 + 10mass%HAp, and TiO 2 +30mass%HAp, where HAp is hydroxyapatite and PBS is polybutylene succinate) were plasma sprayed on biodegradable PBS substrates. HAp powder was mixed with A-TiO 2 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-TiO 2 coatings without HAp. HAp addition improved photocatalytic sterilization when plasma preheating of the PBS was performed

  4. 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...

  5. A study on the effect of heat treatment on electrical properties of plasma sprayed YSZ

    International Nuclear Information System (INIS)

    Elshikh, S.S.M.

    2012-01-01

    Free standing samples of plasma sprayed (PS) zirconia partially stabilized with yettria (YSZ) were prepared with two machines of plasma spray deposition (Triplex gun- 100 kw, F-4 gun 64 kw) have different electrical power and spraying parameters, which produced different microstructures; contain different amounts and varieties of pores and micro-cracks.The study included heat treatment of samples at 1200 degree C for 1 h, 5 h, 10 h, 100 h and 500 h, to study the changes in macrostructure (pores and micro-cracks) which affect the electrical conductivity.The electrical properties (resistively, electrical conductivity) of plasma sprayed ZrO 2 stabilized by 8 wt. % Y 2 O 3 samples were determined by using electrical impedance spectroscopy (IS). Specimen's microstructure was examined by optical microscopy. By measuring electrical properties and connected porosity percent of the coatings obtained under various spraying conditions, it would be possible to select the optimum spraying condition to spray coatings which have high efficiency at high temperature.The results showed that the electrical conductivity of (YSZ) samples after heat treatment increased by a rate of (20%-30%) as compared to that of as sprayed.

  6. Process maps for plasma spray. Part II: Deposition and properties

    International Nuclear Information System (INIS)

    XIANGYANG, JIANG; MATEJICEK, JIRI; KULKARNI, ANAND; HERMAN, HERBERT; SAMPATH, SANJAY; GILMORE, DELWYN L.; NEISER A, RICHARD Jr.

    2000-01-01

    This is the second paper of a two part series based on an integrated study carried out at the State University of New York at Stony Brook and Sandia National Laboratories. The goal of the study is the fundamental understanding of the plasma-particle interaction, droplet/substrate interaction, deposit formation dynamics and microstructure development as well as the deposit property. The outcome is science-based relationships, which can be used to link processing to performance. Molybdenum splats and coatings produced at 3 plasma conditions and three substrate temperatures were characterized. It was found that there is a strong mechanical/thermal interaction between droplet and substrate, which builds up the coatings/substrate adhesion. Hardness, thermal conductivity, and modulus increase, while oxygen content and porosity decrease with increasing particle velocity. Increasing deposition temperature resulted in dramatic improvement in coating thermal conductivity and hardness as well as increase in coating oxygen content. Indentation reveals improved fracture resistance for the coatings prepared at higher deposition temperature. Residual stress was significantly affected by deposition temperature, although not significant by particle energy within the investigated parameter range. Coatings prepared at high deposition temperature with high-energy particles suffered considerably less damage in wear tests. Possible mechanisms behind these changes are discussed within the context of relational maps which are under development

  7. Structural evolution of plasma-sprayed nanoscale 3 mol% and 5 mol% yttria-stabilized zirconia coatings during sintering

    Science.gov (United States)

    Zhao, Yan; Gao, Yang

    2017-12-01

    The microstructure of plasma-sprayed nanostructured yttria-stabilized zirconia (YSZ) coatings may change during high-temperature exposure, which would influence the coating performance and service lifetime. In this study, the phase structure and the microstructural evolution of 3YSZ (zirconia-3 mol% yttria) and 5YSZ (zirconia-5 mol% yttria) nanostructured coatings were investigated by means of sintering at 1400 °C for 50-100 h. The microhardness, elastic moduli, and thermal shock cycles of the 3YSZ and 5YSZ nanostructured coatings were also investigated. The results showed that the redistribution of yttrium ions at 1400 °C caused the continuous increase of monoclinic-phase zirconia, but no obvious inter-splat cracking formed at the cross-sections, even after 100 h. Large voids appeared around the nanoporous zone because of the sintering of nanoscale granules upon high-temperature exposure. The microhardness and elastic moduli of the nanostructured coatings first increased and then decreased with increasing sintering times. The growth rate of the nanograins in the 3YSZ coating was lower than that in 5YSZ, which slowed the changes in 3YSZ coating porosity during sintering. Although the 3YSZ coating was prone to monoclinic phase transition, the experimental results showed that the thermal shock resistance of the 3YSZ coating was better than that of the 5YSZ coating.

  8. The Influence of Heat Treatments on the Porosity of Suspension Plasma-Sprayed Yttria-Stabilized Zirconia Coatings

    Science.gov (United States)

    Ekberg, Johanna; Ganvir, Ashish; Klement, Uta; Creci, Simone; Nordstierna, Lars

    2018-02-01

    Suspension plasma-sprayed coatings are produced using fine-grained feedstock. This allows to control the porosity and to achieve low thermal conductivity which makes the coatings attractive as topcoats in thermal barrier coatings (TBCs). Used in gas turbine applications, TBCs are exposed to high temperature exhaust gases which lead to microstructure alterations. In order to obtain coatings with optimized thermomechanical properties, microstructure alterations like closing of pores and opening of cracks have to be taken into account. Hence, in this study, TBC topcoats consisting of 4 mol.% yttria-stabilized zirconia were heat-treated in air at 1150 °C and thereafter the coating porosity was investigated using image analysis (IA) and nuclear magnetic resonance (NMR) cryoporometry. Both IA and NMR cryoporometry showed that the porosity changed as a result of the heat treatment for all investigated coatings. In fact, both techniques showed that the fine porosity decreased as a result of the heat treatment, while IA also showed an increase in the coarse porosity. When studying the coatings using scanning electron microscopy, it was noticed that finer pores and cracks disappeared and larger pores grew slightly and achieved a more distinct shape as the material seemed to become more compact.

  9. Production of coloured glass-ceramics from incinerator ash using thermal plasma technology.

    Science.gov (United States)

    Cheng, T W; Huang, M Z; Tzeng, C C; Cheng, K B; Ueng, T H

    2007-08-01

    Incineration is a major treatment process for municipal solid waste in Taiwan. It is estimated that over 1.5 Mt of incinerator ash are produced annually. This study proposes using thermal plasma technology to treat incinerator ash. Sintered glass-ceramics were produced using quenched vitrified slag with colouring agents added. The experimental results showed that the major crystalline phases developed in the sintered glass-ceramics were gehlenite and wollastonite, but many other secondary phases also appeared depending on the colouring agents added. The physical/mechanical properties, chemical resistance and toxicity characteristic leaching procedure of the coloured glass-ceramics were satisfactory. The glass-ceramic products obtained from incinerator ash treated with thermal plasma technology have great potential for building applications.

  10. Study on Metal Microfilter Coated with Ceramics by Using Plasma Thermal Spray Method

    International Nuclear Information System (INIS)

    Song, In Gyu; Shin, Hyun Myung; Choi, Hae Woon; Lee, Young Min

    2011-01-01

    This research was performed on a microfilter made of a hybrid material (ceramic + metal) that was coated with ceramics on the metal-filter surface by using the thermal spray method. The ceramic powders used were Al 2 O 3 +40TiO 2 powder with a particle size of 20 μm and Al 2 O 3 (98%+)powder with a particle size of 45 μm. The metal filters were filter-grade 20 μm, 30 μm, and 50 μm sintered metal powder filters (SIKA-R 20 IS, 30 IS, 50 IS: Sinter Metals Filters) and filter-grade 75 μm sintered mesh filter with five layers. Ceramic-coated filters that were coated using the thermal spray method had a great influence on powder material, particle size, and coating thickness. However, these filters showed a fine performance when used as micro-filters

  11. A comparative study on thermal efficiency between the present floor and a ceramic floor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y.M.; Kim, K.S. [Korea Institute of Science and Technology, Seoul (Korea, Republic of); Choi, B.S. [Kyung Hee University, Yongin (Korea, Republic of); Ko, J.S.; Park, S.K. [Bomwoo and Co. LTD., Kwangju (Korea, Republic of)

    1999-04-01

    A ceramic floor with improved thermal conductivity and efficiency has been developed in this study. The new ceramic floor minimizes the shrinkage rate to below 0.07% and shows almost no cleavage. There is no need to repair the ceramic floor because its bottom surface is flat. It especially shows an excellent performance in the test of a compressive strength (300 kg/cm{sup 2} based on 28 days), a flexural strength (64 kg/cm{sup 2} based on 28 days), and a convenient pressing. It is lighter than the present floor and it is expected to be applicable for a self-leveling ceramic motar in the residences and apartments. It shows an excellent character in the thermal conductivity and other physical properties compare to the present cement mortar. 5 refs., 3 figs., 2 tabs.

  12. Structural response testing of thermal barrier load bearing ceramic pads

    International Nuclear Information System (INIS)

    Pickering, J.L.; Black, W.E.; Luci, R.K.; Oland, C.B.

    1983-01-01

    A load-bearing insulating structure for use in a high-temperature gas-cooled reactor (HTGR) was investigated. The structure was composed of dense ceramic materials in the form of circular pads arranged in a stack. Specifically, the test program was structured to investigate the isolation effectiveness of interface materials placed between the ceramic pads to reduce the effectiveness of mechanically induced loads. The tests were conducted at room temperature using tapered loading platens on single ceramic pads. Seventeen alumina specimens, representing two types of material and two thicknesses, were tested. Three interface material thicknesses were introduced using silica cloth and graphite foil. Pre- and post-test nondestructive examinations were conducted in an effort to identify potential damage-inducing anomalies in the ceramic pads. A total of 62 tests was conducted with all specimens eventually loaded to failure

  13. Laser Remelting of Plasma-Sprayed Tungsten Coatings

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Holub, P.

    2014-01-01

    Roč. 23, č. 4 (2014), s. 750-754 ISSN 1059-9630 R&D Projects: GA ČR(CZ) GAP108/12/1872 Grant - others:European Project ExtreMat(XE) NMP-CT-2004-500253 Institutional support: RVO:61389021 Keywords : functionally graded coatings * laser remelting * plasma facing materials * thermal conductivity * water stabilized plasma Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.344, year: 2014 http://link.springer.com/article/10.1007%2Fs11666-014-0067-4

  14. Thermal properties of PZT95/5(1.8Nb) and PSZT ceramics

    International Nuclear Information System (INIS)

    DiAntonio, Christopher Brian; Rae, David F.; Corelis, David J.; Yang, Pin; Burns, George Robert

    2006-01-01

    Thermal properties of niobium-modified PZT95/5(1.8Nb) and PSZT ceramics used for the ferroelectric power supply have been studied from -100 C to 375 C. Within this temperature range, these materials exhibit ferroelectric-ferroelectric and ferroelectric-paraelectric phase transformations. The thermal expansion coefficient, heat capacity, and thermal diffusivity of different phases were measured. Thermal conductivity and Grueneisen constant were calculated at several selected temperatures between -60 C and 100 C. Results show that thermal properties of these two solid solutions are very similar. Phase transformations in these ceramics possess first order transformation characteristics including thermal hysteresis, transformational strain, and enthalpy change. The thermal strain in the high temperature rhombohedral phase region is extremely anisotropic. The heat capacity for both materials approaches to 3R (or 5.938 cal/(g-mole*K)) near room temperature. The thermal diffusivity and the thermal conductivity are quite low in comparison to common oxide ceramics, and are comparable to amorphous silicate glass. Furthermore, the thermal conductivity of these materials between -60 C and 100 C becomes independent of temperature and is sensitive to the structural phase transformation. These phenomena suggest that the phonon mean free path governing the thermal conductivity in this temperature range is limited by the lattice dimensions, which is in good agreement with calculated values. Effects of small compositional changes and density/porosity variations in these ceramics on their thermal properties are also discussed. The implications of these transformation characteristics and unusual thermal properties are important in guiding processing and handling procedures for these materials

  15. Thermal Conductivity of Ceramic Thermal Barrier and Environmental Barrier Coating Materials

    Science.gov (United States)

    Zhu, Dong-Ming; Bansal, Narottam P.; Lee, Kang N.; Miller, Robert A.

    2001-01-01

    Thermal barrier and environmental barrier coatings (TBC's and EBC's) have been developed to protect metallic and Si-based ceramic components in gas turbine engines from high temperature attack. Zirconia-yttria based oxides and (Ba,Sr)Al2Si2O8(BSAS)/mullite based silicates have been used as the coating materials. In this study, thermal conductivity values of zirconia-yttria- and BSAS/mullite-based coating materials were determined at high temperatures using a steady-state laser heat flux technique. During the laser conductivity test, the specimen surface was heated by delivering uniformly distributed heat flux from a high power laser. One-dimensional steady-state heating was achieved by using thin disk specimen configuration (25.4 mm diam and 2 to 4 mm thickness) and the appropriate backside air-cooling. The temperature gradient across the specimen thickness was carefully measured by two surface and backside pyrometers. The thermal conductivity values were thus determined as a function of temperature based on the 1-D heat transfer equation. The radiation heat loss and laser absorption corrections of the materials were considered in the conductivity measurements. The effects of specimen porosity and sintering on measured conductivity values were also evaluated.

  16. Ballistic Performance of Porous-Ceramic, Thermal Protection Systems to 9 km/s

    Science.gov (United States)

    Miller, Joshua E.; Bohl, William E.; Foreman, Cory D.; Christiansen, Eric C.; Davis, Bruce A.

    2010-01-01

    Porous-ceramic, thermal protection systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of US manned spacecraft, Orion. These materials insulate the structural components and sensitive components of a spacecraft against the intense thermal environments of atmospheric reentry. These materials are also highly exposed to solid particle space environment hazards. This paper discusses recent impact testing up to 9.65 km/s on ceramic tiles similar to those used on the Orbiter. These tiles are a porous-ceramic insulator of nominally 8 lb/ft(exp 3) alumina-fiber-enhanced-thermal-barrier (AETB8) coated with a damage-resistant, toughened-unipiece-fibrous-insulation/reaction-cured-glass layer (TUFI/RCG).

  17. Investigation of a ceramic vane with a metal disk thermal and mechanical contact in a gas turbine impeller

    Directory of Open Access Journals (Sweden)

    Resnick S.V.

    2015-01-01

    Full Text Available Promising directions of a new generation gas turbine engines development include using in gas turbines ceramic materials blades with high strength, thermal and chemical stability. One of the serious problems in developing such motors is insufficient knowledge of contact phenomena occurring in ceramic and metal details connection nodes. This work presents the numerical modeling results of thermal processes on ceramic and metal details rough boundaries. The investigation results are used in conducting experimental researches in conditions reproducing operating.

  18. On the Validity of Continuum Computational Fluid Dynamics Approach Under Very Low-Pressure Plasma Spray Conditions

    Science.gov (United States)

    Ivchenko, Dmitrii; Zhang, Tao; Mariaux, Gilles; Vardelle, Armelle; Goutier, Simon; Itina, Tatiana E.

    2018-01-01

    Plasma spray physical vapor deposition aims to substantially evaporate powders in order to produce coatings with various microstructures. This is achieved by powder vapor condensation onto the substrate and/or by deposition of fine melted powder particles and nanoclusters. The deposition process typically operates at pressures ranging between 10 and 200 Pa. In addition to the experimental works, numerical simulations are performed to better understand the process and optimize the experimental conditions. However, the combination of high temperatures and low pressure with shock waves initiated by supersonic expansion of the hot gas in the low-pressure medium makes doubtful the applicability of the continuum approach for the simulation of such a process. This work investigates (1) effects of the pressure dependence of thermodynamic and transport properties on computational fluid dynamics (CFD) predictions and (2) the validity of the continuum approach for thermal plasma flow simulation under very low-pressure conditions. The study compares the flow fields predicted with a continuum approach using CFD software with those obtained by a kinetic-based approach using a direct simulation Monte Carlo method (DSMC). It also shows how the presence of high gradients can contribute to prediction errors for typical PS-PVD conditions.

  19. 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.

  20. Thermal Effect of Ceramic Substrate on Heat Distribution in Thermoelectric Generators

    DEFF Research Database (Denmark)

    Kolaei, Alireza Rezania; Rosendahl, Lasse

    2012-01-01

    in the heat sink, a parallel microchannel heat sink is applied to a real TEG. The focus of this study is a discussion of the temperature difference variation between the cold/hot sides of the TEG legs versus the variation of the thermal conductivity of the ceramic substrate and the thickness of the substrate...... that the temperature difference is affected remarkably by the pressure drops in the heat sink, the thermal conductivity of the ceramic substrate, and the thickness of the substrate on the hot side....

  1. Spectroscopic study of local thermal effect in transparent glass ceramics containing nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Local thermal effect influencing the fluorescence of triply ionized rare earth ions doped in nanocrystals is studied with laser spectroscopy and theory of thermal transportation for transparent oxyfluoride glass ceramics containing nanocrystals. The result shows that the local temperature of the nanocrystals embedded in glass matrices is much higher than the environmental temperature of the sample. It is suggested that the temperature-dependent thermal energy induced by the light absorption must be considered when the theory of thermal transportation is applied to the study of local thermal effect.

  2. Correlation of physical properties of ceramic materials with resistance to fracture by thermal shock

    Science.gov (United States)

    Lidman, W G; Bobrowsky, A R

    1949-01-01

    An analysis is made to determine which properties of materials affect their resistance to fracture by thermal stresses.From this analysis, a parameter is evaluated that is correlated with the resistance of ceramic materials to fracture by thermal shock as experimentally determined. This parameter may be used to predict qualitatively the resistance of a material to fracture by thermal shock. Resistance to fracture by thermal shock is shown to be dependent upon the following material properties: thermal conductivity, tensile strength, thermal expansion, and ductility modulus. For qualitative prediction of resistance of materials to fracture by thermal shock, the parameter may be expressed as the product of thermal conductivity and tensile strength divided by the product of linear coefficient of thermal expansion and ductility modulus of the specimen.

  3. Local thermal conductivity of polycrystalline AlN ceramics measured by scanning thermal microscopy and complementary scanning electron microscopy techniques

    International Nuclear Information System (INIS)

    Zhang Yue-Fei; Wang Li; Wei Bin; Ji Yuan; Han Xiao-Dong; Zhang Ze; Heiderhoff, R.; Geinzer, A. K.; Balk, L. J.

    2012-01-01

    The local thermal conductivity of polycrystalline aluminum nitride (AlN) ceramics is measured and imaged by using a scanning thermal microscope (SThM) and complementary scanning electron microscope (SEM) based techniques at room temperature. The quantitative thermal conductivity for the AlN sample is gained by using a SThM with a spatial resolution of sub-micrometer scale through using the 3ω method. A thermal conductivity of 308 W/m·K within grains corresponding to that of high-purity single crystal AlN is obtained. The slight differences in thermal conduction between the adjacent grains are found to result from crystallographic misorientations, as demonstrated in the electron backscattered diffraction. A much lower thermal conductivity at the grain boundary is due to impurities and defects enriched in these sites, as indicated by energy dispersive X-ray spectroscopy. (condensed matter: structural, mechanical, and thermal properties)

  4. Effect of substrate and cathode parameters on the properties of suspension plasma sprayed solid oxide fuel cell electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Waldbillig, D.; Tang, Z.; Burgess, A. [British Columbia Univ., Vancouver, BC (Canada); Kesler, O. [Toronto Univ., ON (Canada)

    2008-07-01

    An axial injection suspension plasma spray system has been used to produce layers of fully stabilized yttriastabilized zirconia (YSZ) that could be used as solid oxide fuel cell (SOFC) electrolytes. Suspension plasma spraying is a promising technique for the rapid production of coatings with fine microstructures and controlled porosity without requiring a post-deposition heat treatment. This new manufacturing technique to produce SOFC active layers requires the build up of a number of different plasma sprayed SOFC functional layers (cathode, electrolyte and anode) sequentially on top of each other. To understand the influence of the substrate and previouslydeposited coating layers on subsequent coating layer properties, YSZ layers were deposited on top of plasma sprayed composite lanthanum strontium manganite (LSM)/YSZ cathode layers that were first deposited on porous ferritic stainless steel substrates. Three layer half cells consisting of the porous steel substrate, composite cathode, and suspension plasma sprayed electrolyte layer were then characterized. A systematic study was performed in order to investigate the effect of parameters such as substrate and cathode layer roughness, substrate surface pore size, and cathode microstructure and thickness on electrolyte deposition efficiency, cathode and electrolyte permeability, and layer microstructure. (orig.)

  5. Tungsten oxide coatings deposited by plasma spray using powder and solution precursor for detection of nitrogen dioxide gas

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao, E-mail: zhangc@yzu.edu.cn [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Wang, Jie [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Geng, Xin [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China)

    2016-05-25

    Increasing attention has been paid on preparation methods for resistive-type gas sensors based on semiconductor metal oxides. In this work, tungsten oxide (WO{sub 3}) coatings were prepared on alumina substrates and used as gas sensitive layers. The coatings were deposited by atmospheric plasma spray using powder, solution precursor, or a combination of both. Tungsten oxide powder through a powder port and ammonium tungstate aqueous solution through a liquid port were injected into plasma stream respectively or together to deposit WO{sub 3} coatings. Phase structures in the coatings were characterized by X-ray diffraction analyzer. The field-emission scanning electron microscopy images confirmed that the coatings were in microstructure, nanostructure or micro-nanostructure. The sensing properties of the sensors based on the coatings exposed to 1 ppm nitrogen dioxide gas were characterized in a home-made instrument. Sensing properties of the coatings were compared and discussed. The influences of gas humidity and working temperature on the sensor responses were further studied. - Highlights: • Porous gas sensitive coatings were deposited by plasma spray using powder and solution precursor. • Crystallized WO{sub 3} were obtained through hybrid plasma spray plus a pre-conditioned step. • Plasma power had an important influence on coating microstructure. • The particle size of atmospheric plasma-sprayed microstructured coating was stable. • Solution precursor plasma-sprayed WO{sub 3} coatings had nanostructure and showed good responses to 1 ppm NO{sub 2}.

  6. Fabrication of dense yttrium oxyfluoride ceramics by hot pressing and their mechanical, thermal, and electrical properties

    Science.gov (United States)

    Tahara, Ryuki; Tsunoura, Toru; Yoshida, Katsumi; Yano, Toyohiko; Kishi, Yukio

    2018-06-01

    Excellent corrosion-resistant materials have been strongly required to reduce particle contamination during the plasma process in semiconductor production. Yttrium oxyfluoride can be a candidate as highly corrosion-resistant material. In this study, three types of dense yttrium oxyfluoride ceramics with different oxygen contents, namely, YOF, Y5O4F7 and Y5O4F7 + YF3, were fabricated by hot pressing, and their mechanical, thermal, and electrical properties were evaluated. Y5O4F7 ceramics showed an excellent thermal stability up to 800 °C, a low loss factor, and volume resistivity comparable to conventional plasma-resistant oxides, such as Y2O3. From these results, yttrium oxyfluoride ceramics are strongly suggested to be used as electrostatic chucks in semiconductor production.

  7. 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.

  8. Deposition of Lanthanum Strontium Cobalt Ferrite (LSCF) Using Suspension Plasma Spraying for Oxygen Transport Membrane Applications

    Science.gov (United States)

    Fan, E. S. C.; Kesler, O.

    2015-08-01

    Suspension plasma spray deposition was utilized to fabricate dense lanthanum strontium cobalt ferrite oxygen separation membranes (OSMs) on porous metal substrates for mechanical support. The as-sprayed membranes had negligible and/or reversible material decomposition. At the longer stand-off distance (80 mm), smooth and dense membranes could be manufactured using a plasma with power below approximately 81 kW. Moreover, a membrane of 55 μm was observed to have very low gas leakage rates desirable for OSM applications. This thickness could potentially be decreased further to improve oxygen diffusion by using metal substrates with finer surface pores.

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

    International Nuclear Information System (INIS)

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

  10. On-line monitoring on thermal shock damage of ceramics using acoustic emission

    International Nuclear Information System (INIS)

    Lee, Jin Kyung; Lee, Joon Hyun; Song, Sang Hun

    1999-01-01

    The objective of this paper is to investigate the degree of the thermal shock damage on alumina ceramic using acoustic emission technique. For this purpose, alumina ceramic specimen was heated in the elastic furnace and then was quenched into the water tank. When the specimen was quenched into water tank, a lot of micro-cracks were generated on the surface of specimen due to the thermal shock damage. In this study, acoustic emission technique was used to evaluate the elastic waves generated by the crack initiation and propagation on the surface of specimen. It was found that when the micro-crack was initiated on the surface of specimen, AE signals were the higher in amplitude than those of bubbling effect and crack propagation. A lot of AE events were generated at the first thermal shock, the number of AE events decreased gradually as the thermal shock cycle increased.

  11. Photoacoustic thermal characterization of Al{sub 2}O{sub 3}-Ag ceramic nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    George, Sajan D. [Institut fuer Nano- und Mikroprozesstechnik, Leibniz Universitaet Hannover, Callinstrasse 36, D 30167, Hannover (Germany)]|[International School of Photonics, Cochin University of Science and Technology, Cochin 682022 (India)], E-mail: george@nmp.uni-hannover.de; Anappara, Aji A. [NEST-INFM and Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa (Italy)]|[University College, Thiruvanathapuram 695001 (India)]|[Ceramic Technology Division, Regional Research Laboratory, CSIR, Thiruvanathapuram 695019 (India); Warrier, P.R.S. [University College, Thiruvanathapuram 695001 (India); Warrier, K.G.K. [Ceramic Technology Division, Regional Research Laboratory, CSIR, Thiruvanathapuram 695019 (India); Radhakrishnan, P.; Nampoori, V.P.N.; Vallabhan, C.P.G. [International School of Photonics, Cochin University of Science and Technology, Cochin 682022 (India)

    2008-09-15

    Laser-induced nondestructive photoacoustic (PA) technique has been employed to determine the thermal diffusivity of nanometal (Ag) dispersed ceramic alumina matrix sintered at different temperatures. The thermal diffusivity values are evaluated by knowing the transition frequency from the amplitude spectrum of PA signal using the one-dimensional heat flow model of Rosencwaig and Gersho. Analysis of the data shows that heat transport and hence the thermal diffusivity value is greatly affected by the influence of incorporation of foreign atom. It is also seen that sintering temperature affects the thermal diffusivity value in a substantial manner. The results are interpreted in terms of variation in porosity and carrier-assisted heat transport mechanism in nanometal dispersed ceramics.

  12. Thermal Properties of Transparent Yb-Doped YAG Ceramics at Elevated Temperatures

    Czech Academy of Sciences Publication Activity Database

    Hostaša, J.; Matějíček, Jiří; Nait-Ali, B.; Smith, D.S.; Pabst, W.; Esposito, L.

    2014-01-01

    Roč. 97, č. 8 (2014), s. 2602-2606 ISSN 0002-7820 Institutional support: RVO:61389021 Keywords : yttrium aluminium garnet * Yb:YAG * thermal diffusivity Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.610, year: 2014 http://onlinelibrary.wiley.com/doi/10.1111/jace.13015/abstract

  13. Mechanical and thermal cycling effects on the flexural strength of glass ceramics fused to titanium

    NARCIS (Netherlands)

    Vasquez, Vanessa; Ozcan, Mutlu; Nishioka, Renato; Souza, Rodrigo; Mesquita, Alfredo; Pavanelli, Carlos

    This study evaluated the effects of mechanical and thermal cycling on the flexural strength (ISO 9693) of three brands of ceramics fused to commercially pure titanium (cpTi). Metallic frameworks of 25 x 3 x 0.5 mm dimensions (N = 84) were cast in cpTi, followed by 150-mu m aluminum oxide airborne

  14. Grain-size effects on thermal properties of BaTiO3 ceramics

    Indian Academy of Sciences (India)

    Administrator

    decreasing grain size. Furthermore, the Curie temperature shifts to lower temperature with decreasing grain size. Keywords. Nanocrystalline ceramics; thermal properties; size effect. 1. Introduction. BaTiO3 has been widely used in the electronic industry for its high dielectric constant and low losses above room temperature ...

  15. The influence of substrate temperature and spraying distance on the properties of plasma sprayed tungsten and steel coatings deposited in a shrouding chamber

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Vilémová, Monika; Nevrlá, Barbara; Kocmanová, Lenka; Veverka, Jakub; Halasová, Martina; Hadraba, Hynek

    2017-01-01

    Roč. 318, May (2017), s. 217-223 ISSN 0257-8972. [International Meeting on Thermal Spraying (RIPT)/7./. Limoges, 09.12.2015-11.12.2015] R&D Projects: GA ČR GB14-36566G EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 ; RVO:68081723 Keywords : Tungsten * Steel * Atmospheric plasma spraying * Shrouding * Substrate temperature * Fusion reactor materials * Plasma facing components Subject RIV: JK - Corrosion ; Surface Treatment of Materials; JK - Corrosion ; Surface Treatment of Materials (UFM-A) OBOR OECD: Coating and films; Coating and films (UFM-A) Impact factor: 2.589, year: 2016 http://www.sciencedirect.com/science/ article /pii/S0257897216310520

  16. Fuel Retention Improvement at High Temperatures in Tungsten-Uranium Dioxide Dispersion Fuel Elements by Plasma-Spray Cladding

    Science.gov (United States)

    Grisaffe, Salvatore J.; Caves, Robert M.

    1964-01-01

    An investigation was undertaken to determine the feasibility of depositing integrally bonded plasma-sprayed tungsten coatings onto 80-volume-percent tungsten - 20-volume-percent uranium dioxide composites. These composites were face clad with thin tungsten foil to inhibit uranium dioxide loss at elevated temperatures, but loss at the unclad edges was still significant. By preheating the composite substrates to approximately 3700 degrees F in a nitrogen environment, metallurgically bonded tungsten coatings could be obtained directly by plasma spraying. Furthermore, even though these coatings were thin and somewhat porous, they greatly inhibited the loss of uranium dioxide. For example, a specimen that was face clad but had no edge cladding lost 5.8 percent uranium dioxide after 2 hours at 4750 dgrees F in flowing hydrogen. A similar specimen with plasma-spray-coated edges, however, lost only 0.75 percent uranium dioxide under the same testing conditions.

  17. Correlation between metal-ceramic bond strength and coefficient of linear thermal expansion difference

    Directory of Open Access Journals (Sweden)

    Stella Crosara Lopes

    2009-04-01

    Full Text Available The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs of the metals and ceramics. Verabond (VB Ni-Cr-Be alloy, Verabond II (VB2, Ni-Cr alloy, Pors-on 4 (P, Pd-Ag alloy, and IPS (I and Duceram (D ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01 for the MCBS test results (MPa, with PI showing higher MCBS (67.72 than the other pairs, which did not present any significant differences. The CTE (10-6 oC-1 differences were: VBI (0.54, VBD (1.33, VB2I (-0.14, VB2D (0.63, PI (1.84 and PD (2.62. Pearson's correlation test (r=0.17 was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.

  18. Correlation between metal-ceramic bond strength and coefficient of linear thermal expansion difference.

    Science.gov (United States)

    Lopes, Stella Crosara; Pagnano, Valéria Oliveira; Rollo, João Manuel Domingos de Almeida; Leal, Mônica Barbosa; Bezzon, Osvaldo Luiz

    2009-01-01

    The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS) of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics) and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs) of the metals and ceramics. Verabond (VB) Ni-Cr-Be alloy, Verabond II (VB2), Ni-Cr alloy, Pors-on 4 (P), Pd-Ag alloy, and IPS (I) and Duceram (D) ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length) made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length) of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01) for the MCBS test results (MPa), with PI showing higher MCBS (67.72) than the other pairs, which did not present any significant differences. The CTE (10(-6) oC(-1)) differences were: VBI (0.54), VBD (1.33), VB2I (-0.14), VB2D (0.63), PI (1.84) and PD (2.62). Pearson's correlation test (r=0.17) was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.

  19. Argon Shrouded Plasma Spraying of Tantalum over Titanium for Corrosion Protection in Fluorinated Nitric Acid Media

    Science.gov (United States)

    Vetrivendan, E.; Jayaraj, J.; Ningshen, S.; Mallika, C.; Kamachi Mudali, U.

    2018-02-01

    Argon shrouded plasma spraying (ASPS) was used to deposit a Ta coating on commercially pure Ti (CP-Ti) under inert argon, for dissolver vessel application in the aqueous spent fuels reprocessing plant with high plutonium content. Oxidation during plasma spraying was minimized by shrouding argon system. Porosity and oxide content were controlled by optimizing the spraying parameters, to obtain a uniform and dense Ta coating. The Ta particle temperature and velocity were optimized by judiciously controlling the spray parameters, using a spray diagnostic charge-coupled device camera. The corrosion resistance of the Ta coatings developed by ASPS was investigated by electrochemical studies in 11.5 M HNO3 and 11.5 M HNO3 + 0.05 M NaF. Similarly, the durability of the ASPS Ta coating/substrate was evaluated as per ASTM A262 Practice-C test in boiling nitric acid and fluorinated nitric acid for 240 h. The ASPS Ta coating exhibited higher corrosion resistance than the CP-Ti substrate, as evident from electrochemical studies, and low corrosion rate with excellent coating stability in boiling nitric, and fluorinated nitric acid. The results of the present study revealed that tantalum coating by ASPS is a promising strategy for improving the corrosion resistance in the highly corrosive reprocessing environment.

  20. Atmospheric Plasma Spraying Low-Temperature Cathode Materials for Solid Oxide Fuel Cells

    Science.gov (United States)

    Harris, J.; Kesler, O.

    2010-01-01

    Atmospheric plasma spraying (APS) is attractive for manufacturing solid oxide fuel cells (SOFCs) because it allows functional layers to be built rapidly with controlled microstructures. The technique allows SOFCs that operate at low temperatures (500-700 °C) to be fabricated by spraying directly onto robust and inexpensive metallic supports. However, standard cathode materials used in commercial SOFCs exhibit high polarization resistances at low operating temperatures. Therefore, alternative cathode materials with high performance at low temperatures are essential to facilitate the use of metallic supports. Coatings of lanthanum strontium cobalt ferrite (LSCF) were fabricated on steel substrates using axial-injection APS. The thickness and microstructure of the coating layers were evaluated, and x-ray diffraction analysis was performed on the coatings to detect material decomposition and the formation of undesired phases in the plasma. These results determined the envelope of plasma spray parameters in which coatings of LSCF can be manufactured, and the range of conditions in which composite cathode coatings could potentially be manufactured.

  1. 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

    2017-10-01

    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.

  2. A novel method to predict the highest hardness of plasma sprayed coating without micro-defects

    Science.gov (United States)

    Zhuo, Yukun; Ye, Fuxing; Wang, Feng

    2018-04-01

    The plasma sprayed coatings are stacked by splats, which are regarded generally as the elementary units of coating. Many researchers have focused on the morphology and formation mechanism of splat. However, a novel method to predict the highest hardness of plasma sprayed coating without micro-defects is proposed according to the nanohardness of splat in this paper. The effectiveness of this novel method was examined by experiments. Firstly, the microstructure of splats and coating, meanwhile the 3D topography of the splats were observed by SEM (SU1510) and video microscope (VHX-2000). Secondly, the nanohardness of splats was evaluated by nanoindentation (NHT) in order to be compared with microhardness of coating measured by microhardness tester (HV-1000A). The results show that the nanohardness of splats with diameter of 70 μm, 100 μm and 140 μm were in the scope of 11∼12 GPa while the microhardness of coating were in the range of 8∼9 GPa. Because the splats had not micro-defects such as pores and cracks in the nanohardness evaluated nano-zone, the nanohardness of the splats can be utilized to predict the highest hardness of coating without micro-defects. This method indicates the maximum of sprayed coating hardness and will reduce the test number to get high hardness coating for better wear resistance.

  3. Characterization of Fe-based alloy coating deposited by supersonic plasma spraying

    International Nuclear Information System (INIS)

    Piao, Zhong-yu; Xu, Bin-shi; Wang, Hai-dou; Wen, Dong-hui

    2013-01-01

    Highlights: • Fe-based coating exhibited few oxides, high density and bond strength. • Amorphous/nanocrystalline phases were found in the coating. • Formation mechanism of excellent coating was investigated. -- Abstract: The objective of the present study is to characterize the Fe-based alloy coating deposited by the supersonic plasma spraying process. The condition of the melting particles was in situ monitored. The microstructure of the coating was examined by scanning electron microscope and high resolution transmission electron microscope. The phase composition was examined by X-ray diffraction. The microhardness and porosity were also measured, respectively. Results show the prepared coatings have excellent properties, such as few oxides, high microhardness and a low porosity amount. At the same time, a mass of amorphous/nanocrystalline phases was found in the coating. The mechanism of the formation of amorphous/nanocrystalline phases was investigated. The appropriate material composition of spraying material and flash set process of plasma spraying are the key factors. Moreover, the mechanism for oxidation resistance is also investigated, where the separation between melting metal and oxygen by the formation of SiO 2 films is the key factor

  4. Method of forming a leak proof plasma sprayed interconnection layer on an electrode of an electrochemical cell

    Science.gov (United States)

    Kuo, Lewis J. H.; Vora, Shailesh D.

    1995-01-01

    A dense, substantially gas-tight, electrically conductive interconnection layer is formed on an electrode structure of an electrochemical cell by: (A) providing an electrode structure; (B) forming on a selected portion of the electrode surface, an interconnection layer having the general formula La.sub.1-x M.sub.x Cr.sub.1-y N.sub.y O.sub.3, where M is a dopant selected from the group of Ca, Sr, Ba, and mixtures thereof, and where N is a dopant selected from the group of Mg, Co, Ni, Al, and mixtures thereof, and where x and y are each independently about 0.075-0.25, by thermally spraying, preferably plasma arc spraying, a flux added interconnection spray powder, preferably agglomerated, the flux added powder comprising flux particles, preferably including dopant, preferably (CaO).sub.12. (Al.sub.2 O.sub.3).sub.7 flux particles including Ca and Al dopant, and LaCrO.sub.3 interconnection particles, preferably undoped LaCrO.sub.3, to form a dense and substantially gas-tight interconnection material bonded to the electrode structure by a single plasma spraying step; and, (C) heat treating the interconnection layer at from about 1200.degree. to 1350.degree. C. to further densify and heal the micro-cracks and macro-cracks of the thermally sprayed interconnection layer. The result is a substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode structure. The electrode structure can be an air electrode, and a solid electrolyte layer can be applied to the unselected portion of the air electrode, and further a fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell for generation of electrical power.

  5. Effect of precursor solutions on ZnO film via solution precursor plasma spray and corresponding gas sensing performances

    Science.gov (United States)

    Yu, Z. X.; Ma, Y. Z.; Zhao, Y. L.; Huang, J. B.; Wang, W. Z.; Moliere, M.; Liao, H. L.

    2017-08-01

    Solution precursor plasma spraying (SPPS) as a novel thermal spray method was employed to deposit nano-structured ZnO thin film using different formulations of the precursor solution. This article focuses on the influence of the solution composition on the preferential orientation of crystal growth, on crystal size and surface morphology of the resulting ZnO films. The trend of preferential growth along (002) lattice plane of ZnO film was studied by slow scanning X-ray diffraction using a specific coefficient P(002). It appears that the thermal spray process promotes the buildup of ZnO films preferentially oriented along the c-axis. The shape of single particle tends to change from round shaped beads to hexagonal plates by increasing the volume ratio of ethanol in the solvent. Both cauliflower and honeycomb-like surface morphologies featuring high specific surface area and roughness were obtained through the SPPS process by varying solution composition. These ZnO films are hydrophobic with contact angle as high as 136°, which is seemingly associated with micro reliefs developing high surface specific area. Then the gas sensing performances of ZnO films preferentially oriented along (002) face were tentatively predicted using the "first principle calculation method" and were compared with those of conventional films that are mainly oriented along the (101) face. The (002) face displays better hydrogen adsorption capability than the (101) face with much larger resulting changes in electrical resistance. In conclusion, the c-axis oriented ZnO films obtained through SSPS have favorable performances to be used as sensitive layer in gas sensing applications.

  6. Thermal shock resistance behavior of a functionally graded ceramic: Effects of finite cooling rate

    Directory of Open Access Journals (Sweden)

    Zhihe Jin

    2014-01-01

    Full Text Available This work presents a semi-analytical model to explore the effects of cooling rate on the thermal shock resistance behavior of a functionally graded ceramic (FGC plate with a periodic array of edge cracks. The FGC is assumed to be a thermally heterogeneous material with constant elastic modulus and Poisson's ratio. The cooling rate applied at the FGC surface is modeled using a linear ramp function. An integral equation method and a closed form asymptotic temperature solution are employed to compute the thermal stress intensity factor (TSIF. The thermal shock residual strength and critical thermal shock of the FGC plate are obtained using the SIF criterion. Thermal shock simulations for an Al2O3/Si3N4 FGC indicate that a finite cooling rate leads to a significantly higher critical thermal shock than that under the sudden cooling condition. The residual strength, however, is relatively insensitive to the cooling rate.

  7. Thermal shock behaviour of mullite-bonded porous silicon carbide ceramics with yttria addition

    International Nuclear Information System (INIS)

    Ding Shuqiang; Zeng Yuping; Jiang Dongliang

    2007-01-01

    Thermal shock resistance of mullite (3Al 2 O 3 · 2SiO 2 )-bonded porous silicon carbide (SiC) ceramics with 3.0 wt% yttria (Y 2 O 3 ) addition was evaluated by a water-quenching technique. The thermal shock damage was investigated as a function of the quenching temperature, quenching cycles and specimen thickness. The residual flexural strength of the quenched specimens decreases with increasing quenching temperature and specimen thickness due to the larger thermal stress caused by thermal shock. However, quenching cycles at the temperature difference of 1200 deg. C have no effect on the residual strength since the same thermal stress was produced in repeated thermal shock processes. The good thermal shock damage resistance of the specimens is contributed mainly by the low strength and moderate elastic modulus. Moreover, the pores prevent the continuous propagation of cracks and alleviate further damage

  8. Negative thermal expansion of lithium aluminosilicate ceramics at cryogenic temperatures

    International Nuclear Information System (INIS)

    Garcia-Moreno, Olga; Fernandez, Adolfo; Khainakov, Sergei; Torrecillas, Ramon

    2010-01-01

    Five lithium aluminosilicate compositions of the LAS system have been synthesized and sintered. The coefficient of thermal expansion of the sintered samples has been studied down to cryogenic conditions. The data presented here under cryogenic conditions will be of value in the future design of new composite materials with very low thermal expansion values. The variation in thermal expansion properties with composition and sintering temperature was studied and is discussed in relation to composition and crystal structure.

  9. Thermal expansion at low temperatures of glass-ceramics and glasses

    Energy Technology Data Exchange (ETDEWEB)

    White, G K [National Measurement Lab., Sydney (Australia)

    1976-08-01

    The linear thermal expansion coefficient, ..cap alpha.., has been measured from 2 to 32 K and from 55 to 90 K for a machineable glass-ceramic, an 'ultra-low expansion' titanium silicate glass (Corning ULE), and ceramic glasses (Cer-Vit and Zerodur), and for glassy carbon. ..cap alpha.. is negative for the ultra-low expansion materials below 100 K, as for pure vitreous silica. Comparative data are reported for ..cap alpha..-quartz , ..cap alpha..-cristobalite, common opal, and vitreous silica.

  10. Ballistic Performance of Porous Ceramic Thermal Protection Systems at 9 km/s

    Science.gov (United States)

    Miller, Joshua E.; Bohl, W. E.; Foreman, C. D.; Christiansen, Eric L.; Davis, B. A.

    2009-01-01

    Porous-ceramic, thermal-protection-systems are used heavily in current reentry vehicles like the Orbiter, and they are currently being proposed for the next generation of manned spacecraft, Orion. These materials insulate the structural components and sensitive electronic components of a spacecraft against the intense thermal environments of atmospheric reentry. Furthermore, these materials are also highly exposed to space environmental hazards like meteoroid and orbital debris impacts. This paper discusses recent impact testing up to 9 km/s on ceramic tiles similar to those used on the Orbiter. These tiles have a porous-batting of nominally 8 lb/cubic ft alumina-fiber-enhanced-thermal-barrier (AETB8) insulating material coated with a damage-resistant, toughened-unipiece-fibrous-insulation (TUFI) layer.

  11. CRYSTALLIZATION KINETICS OF GLASS-CERAMICS BY DIFFERENTIAL THERMAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    A. NOZAD

    2011-06-01

    Full Text Available The crystallization behavior of fluorphlogopite, a glass-ceramic in the MgO–SiO2–Al2O3–K2O–B2O3–F system, was studied by substitution of Li2O for K2O in the glass composition. DTA, XRD and SEM were used for the study of crystallization behavior, formed phases and microstructure of the resulting glass-ceramics. Crystallization kinetics of the glass was investigated under non-isothermal conditions, using the formal theory of transformations for heterogeneous nucleation. The crystallization results were analyzed, and both the activation energy of crystallization process as well as the crystallization mechanism were characterized. Calculated kinetic parameters indicated that the appropriate crystallization mechanism was bulk crystallization for base glass and the sample with addition of Li2O. Non-isothermal DTA experiments showed that the crystallization activation energies of base glasses was in the range of 234-246 KJ/mol and in the samples with addition of Li2O was changed to the range of 317-322 KJ/mol.

  12. Analysis of thermal stability of ceramic engobes developed with marble reject

    International Nuclear Information System (INIS)

    Carlos, E.M.; Assis, R.B.; Sousa, R.F.; Galvao, A.C.P.; Mendes, J.U.L.

    2014-01-01

    Considering the technological growth and technical production in the ceramic industry, ceramic mass formulations were evaluated with addition of marble residue to substitute the quartz for obtaining of engobes. Five formulations were prepared varying the proportions of raw material, sieved at 200 mesh, ball mill homogenised, characterized by fluorescence (FRX) and X-ray diffraction (XRD). Samples were separated from the formulations for thermal analysis (TG / DSC) and dilatometry. The specimens were prepared in uniaxial press (25 Mpa). The FIII and FIV formulations presented satisfactory results, evidencing the potential of replacing quartz by the marble residue in ceramic formulation for engobes, minimizing the environmental impact by the undue discard of waste, reducing costs and increasing the range of raw materials for the coatings industry

  13. Thermal Stress Analysis for Ceramics Stalk in the Low Pressure Die Casting Machine

    Science.gov (United States)

    Noda, Nao-Aki; Hendra, Nao-Aki; Takase, Yasushi; Li, Wenbin

    Low pressure die casting (LPDC) is defined as a net shape casting technology in which the molten metal is injected at high speeds and pressure into a metallic die. The LPDC process is playing an increasingly important role in the foundry industry as a low-cost and high-efficiency precision forming technique. The LPDC process is that the permanent die and filling systems are placed over the furnace containing the molten alloy. The filling of the cavity is obtained by forcing the molten metal by means of a pressurized gas in order to rise into a ceramic tube, which connects the die to the furnace. The ceramics tube called stalk has high temperature resistance and high corrosion resistance. However, attention should be paid to the thermal stress when the stalk is dipped into the molten aluminum. It is important to develop the design of the stalk to reduce the risk of fracture because of low fracture toughness of ceramics. In this paper, therefore, the finite element method is applied to calculate the thermal stresses when the stalk is dipped into the crucible by varying the dipping speeds and dipping directions. It is found that the thermal stress can be reduced by dipping slowly if the stalk is dipped into the crucible vertically, while the thermal stress can be reduced by dipping fast if it is dipped horizontally.

  14. The effect of ion implantation on the oxidation resistance of vacuum plasma sprayed CoNiCrAlY coatings

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Jie [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Zhao Huayu; Zhou Xiaming [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China); Tao Shunyan, E-mail: shunyantao@mail.sic.ac.cn [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China); Ding Chuanxian [Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai 200050 (China); Shanghai Institute of Ceramic, Chinese Academy of Sciences, Shanghai 200050 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer We used ion implantation to improve the oxidation resistance of CoNiCrAlY coating. Black-Right-Pointing-Pointer The oxidation process of CoNiCrAlY coating at 1100 Degree-Sign C for 1000 h was studied. Black-Right-Pointing-Pointer The Nb ion implanted coating exhibited better oxidation resistance. Black-Right-Pointing-Pointer The influences of Nb and Al ion implantation into CoNiCrAlY coatings were evaluated. - Abstract: CoNiCrAlY coatings prepared by vacuum plasma spraying (VPS) were implanted with Nb and Al ions at a fluence of 10{sup 17} atoms/cm{sup 2}. The effects of ion implantation on the oxidation resistance of CoNiCrAlY coatings were investigated. The thermally grown oxide (TGO) formed on each specimen was characterized by XRD, SEM and EDS, respectively. The results showed that the oxidation process of CoNiCrAlY coatings could be divided into four stages and the key to obtaining good oxidation resistance was to remain high enough amount of Al and promote the lateral growth of TGO. The implantation of Nb resulted in the formation of continuous and dense Al{sub 2}O{sub 3} scale to improve the oxidation resistance. The Al implanted coating could form Al{sub 2}O{sub 3} scale at the initial stage, however, the scale was soon broken and TGO transformed to non-protective spinel.

  15. Light Weight Ceramic Ablators for Mars Follow-on Mission Vehicle Thermal Protection System

    Science.gov (United States)

    Tran, Huy K.; Rasky, Daniel J.; Hsu, Ming-Ta; Turan, Ryan

    1994-01-01

    New Light Weight Ceramic Ablators (LCA) were produced by using ceramic and carbon fibrous substrates, impregnated with silicone and phenolic resins. The special infiltration techniques (patent pending) were developed to control the amount of organic resins in the highly porous fiber matrices so that the final densities of LCA's range from 0.22 to 0.24 g/cc. This paper presents the thermal and ablative performance of the Silicone Impregnated Reusable Ceramic Ablators (SIRCA) in simulated entry conditions for Mars-Pathfinder in the Ames 60 MW Interaction Heating Facility (I HF). Arc jet test results yielded no evidence of char erosion and mass loss at high stagnation pressures to 0.25 atm. Minimal silica melt was detected on surface char at a stagnation pressure of 0.31 atm. Four ceramic substrates were used in the production of SIRCA's to obtain the effective of boron oxide present in substrate so the thermal performance of SIRCA's. A sample of SIRCA was also exposed to the same heating condition for five cycles and no significant mass loss or recession was observed. Tensile testing established that the SIRCA tensile strength is about a factor of two higher than that of the virgin substrates. Thermogravimetric Analysis (TGA) of the char in nitrogen and air showed no evidence of free carbon in the char. Scanning Electron Microscopy of the post test sample showed that the char surface consists of a fibrous structure that was sealed with a thin layer of silicon oxide melt.

  16. Study on Metal Microfilter Coated with Ceramics by Using Plasma Thermal Spray Method

    Energy Technology Data Exchange (ETDEWEB)

    Song, In Gyu; Shin, Hyun Myung; Choi, Hae Woon [Keimyung University, Daegu (Korea, Republic of); Lee, Young Min [Korea Polytechincs VI, Daegu (Korea, Republic of)

    2011-09-15

    This research was performed on a microfilter made of a hybrid material (ceramic + metal) that was coated with ceramics on the metal-filter surface by using the thermal spray method. The ceramic powders used were Al{sub 2}O{sub 3}+40TiO{sub 2} powder with a particle size of 20 {mu}m and Al{sub 2}O{sub 3} (98%+)powder with a particle size of 45 {mu}m. The metal filters were filter-grade 20 {mu}m, 30 {mu}m, and 50 {mu}m sintered metal powder filters (SIKA-R 20 IS, 30 IS, 50 IS: Sinter Metals Filters) and filter-grade 75 {mu}m sintered mesh filter with five layers. Ceramic-coated filters that were coated using the thermal spray method had a great influence on powder material, particle size, and coating thickness. However, these filters showed a fine performance when used as micro-filters.

  17. Thermal/chemical degradation of ceramic cross-flow filter materials

    Energy Technology Data Exchange (ETDEWEB)

    Alvin, M.A.; Lane, J.E.; Lippert, T.E.

    1989-11-01

    This report summarizes the 14-month, Phase 1 effort conducted by Westinghouse on the Thermal/Chemical Degradation of Ceramic Cross-Flow Filter Materials program. In Phase 1 expected filter process conditions were identified for a fixed-bed, fluid-bed, and entrained-bed gasification, direct coal fired turbine, and pressurized fluidized-bed combustion system. Ceramic cross-flow filter materials were also selected, procured, and subjected to chemical and physical characterization. The stability of each of the ceramic cross-flow materials was assessed in terms of potential reactions or phase change as a result of process temperature, and effluent gas compositions containing alkali and fines. In addition chemical and physical characterization was conducted on cross-flow filters that were exposed to the METC fluid-bed gasifier and the New York University pressurized fluidized-bed combustor. Long-term high temperature degradation mechanisms were proposed for each ceramic cross-flow material at process operating conditions. An experimental bench-scale test program is recommended to be conducted in Phase 2, generating data that support the proposed cross-flow filter material thermal/chemical degradation mechanisms. Papers on the individual subtasks have been processed separately for inclusion on the data base.

  18. Plasma Spraying and Characterization of Tungsten Carbide-Cobalt Coatings by the Water-Stabilized System WSP

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Kašparová, M.; Bellin, J.; Le Guen, E.; Zahálka, F.

    2009-01-01

    Roč. 2009, - (2009), s. 1-11 ISSN 1687-8434 R&D Projects: GA AV ČR 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : Tungsten karbide – cobalt, cermet * wear resistance * abrasion * plasma spraying Subject RIV: JG - Metallurgy http://www.hindawi.com/journals/amse/2009/254848.html

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

    International Nuclear Information System (INIS)

    Huang Yi; Song Lei; Liu Xiaoguang; Xiao Yanfeng; Wu Yao; Chen Jiyong; Wu Fang; Gu Zhongwei

    2010-01-01

    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 μm 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.

  20. Heat-Treated TiO2 Plasma Spray Deposition for Bioactivity Improvement in Ti-6Al-4V Alloy

    Science.gov (United States)

    Kumari, Renu; Majumdar, Jyotsna Dutta

    2017-12-01

    In the present study, titanium di-oxide (TiO2) coating has been developed on Ti-6Al-4V substrate by plasma spray deposition. Followed by plasma spraying, heat treatment of the sprayed sample has been carried out by isothermally holding it at 823 K (550 °C) for 2 h. Microstructural analysis shows the presence of porosity and unmelted particles on the as-sprayed surface, the area fraction of which reduces after heat treatment. X-ray diffraction analysis shows the phase transformation from anatase (in precursor powder) to rutile (in as-sprayed coating and the same after heat treatment). There is an improvement in nano-hardness, "Young's modulus" and wear resistance in plasma-sprayed TiO2 coating (as-sprayed as well as post-heat-treated condition) as compared to as-received Ti-6Al-4V, though post-heat treatment offers a superior hardness, "young's modulus" and wear resistance as compared to as-sprayed coating. The corrosion behavior in "hank's solution" shows decrease in corrosion resistance after plasma spraying and post-heat treatment as compared to as-received substrate. A significant decrease in contact angle and improvement in bioactivity (in terms of apatite deposition) were observed in TiO2-coated surface as compared to as-received Ti-6Al-4V.

  1. The effect of YBa2Cu3O7-x powder characteristics on thick coatings prepared by atmospheric plasma spraying

    International Nuclear Information System (INIS)

    Georgiopoulos, E.; Tsetsekou, A.

    2000-01-01

    The development of superconducting YBa 2 Cu 3 O 7-x plasma sprayed coatings on metal substrates can be very useful for applications such as targets for thin-film deposition techniques (sputtering, laser ablation, ion assisted deposition) or magnetic shielding, due to the brittle nature of bulk superconductors. The plasma spraying technique is very flexible and can be used for manufacturing components with a large variety of geometries. This technique requires the use of powders with good rheological characteristics. In this study, YBa 2 Cu 3 O 7-x powders were produced by using the conventional solid-state reaction route and also by spray drying a solution of nitrate precursors. Both powders, as well as mixtures of them, were plasma sprayed to develop coatings on stainless-steel substrates, with the aim of studying the effect of the feedstock powder characteristics on the coating properties. It was found that by optimizing the plasma spraying conditions, good quality coatings could be obtained. However, the powder morphology and homogeneity significantly affect the coating quality. More homogeneous powders lead to better results, the spray-dried powder being the best because of its enhanced rheological properties and good morphology. (author)

  2. Metallic-fibre-reinforced ceramic-matrix composite

    International Nuclear Information System (INIS)

    Prevost, F.; Schnedecker, G.; Boncoeur, M.

    1994-01-01

    A refractory metal wire cloth is embedded in an oxide ceramic matrix, using a plasma spraying technology, in order to elaborate composite plates. When mechanically tested, the composite fails with a pseudo-ductile fracture mode whereas the ceramic alone is originally brittle. It exhibits a higher fracture strength, and remains in the form of a single piece even when straining is important. No further heat treatment is needed after the original processing to reach these characteristics. (authors). 2 figs., 2 refs

  3. Ceramic thermal wind sensor based on advanced direct chip attaching package

    International Nuclear Information System (INIS)

    Zhou Lin; Qin Ming; Chen Shengqi; Chen Bei

    2014-01-01

    An advanced direct chip attaching packaged two-dimensional ceramic thermal wind sensor is studied. The thermal wind sensor chip is fabricated by metal lift-off processes on the ceramic substrate. An advanced direct chip attaching (DCA) packaging is adopted and this new packaged method simplifies the processes of packaging further. Simulations of the advanced DCA packaged sensor based on computational fluid dynamics (CFD) model show the sensor can detect wind speed and direction effectively. The wind tunnel testing results show the advanced DCA packaged sensor can detect the wind direction from 0° to 360° and wind speed from 0 to 20 m/s with the error less than 0.5 m/s. The nonlinear fitting based least square method in Matlab is used to analyze the performance of the sensor. (semiconductor devices)

  4. 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.

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

    International Nuclear Information System (INIS)

    Wang, Yi; Wang, Dezhi; Yan, Jianhui; Sun, Aokui

    2013-01-01

    MoSi 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 2 and Mo 5 Si 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 2 coated Mo substrate exhibited a good oxidation resistance at 1200 °C.

  6. Mechanical properties of nanodiamond-reinforced hydroxyapatite composite coatings deposited by suspension plasma spraying

    Science.gov (United States)

    Chen, Xiuyong; Zhang, Botao; Gong, Yongfeng; Zhou, Ping; Li, Hua

    2018-05-01

    Hydroxyapatite (HA) coatings suffer from poor mechanical properties, which can be enhanced via incorporation of secondary bioinert reinforcement material. Nanodiamond (ND) possesses excellent mechanical properties to play the role as reinforcement for improving the mechanical properties of brittle HA bioceramic coatings. The major persistent challenge yet is the development of proper deposition techniques for fabricating the ND reinforced HA coatings. In this study, we present a novel deposition approach by plasma spraying the mixtures of ND suspension and micron-sized HA powder feedstock. The effect of ND reinforcement on the microstructure and the mechanical properties of the coatings such as hardness, adhesive strength and friction coefficient were examined. The results showed that the ND-reinforced HA coatings display lower porosity, fewer unmelted particles and uniform microstructure, in turn leading to significantly enhanced mechanical properties. The study presented a promising approach to fabricate ND-reinforced HA composite coatings on metal-based medical implants for potential clinical application.

  7. Fatigue properties of Fe-Al intermetallic coatings prepared by plasma spraying

    Czech Academy of Sciences Publication Activity Database

    Mušálek, Radek; Kovářík, O.; Skiba, Tomáš; Haušild, P.; Karlík, M.; Colmenares-Angulo, J.

    2010-01-01

    Roč. 18, č. 7 (2010), s. 1415-1418 ISSN 0966-9795. [FEAL 2009 - 5th Discussion Meeting on the Development of Innovative Iron Aluminium Alloys. Prague, 21.09.2009-24.09.2009] R&D Projects: GA MŠk ME 901 Institutional research plan: CEZ:AV0Z20430508 Keywords : Iron aluminides * Fatigue resistance and crack growth * plasma spraying * scanning electron microscopy Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 2.327, year: 2010 http://www.sciencedirect.com/science?_ob=GatewayURL&_method=citationSearch&_uoikey=B6TX8-4YGHK94-2&_origin=SDEMFRHTML&_version=1&md5=557fd571c715e5f2cff573d5255bb184

  8. 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.

  9. 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.

  10. 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.

  11. Behaviour of plasma-sprayed TiC coatings under H and He irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Fournier, D; Saint-Jacques, R G; Ross, G G; Terreault, B

    1987-02-01

    The effects of H and He irradiation on plasma-sprayed TiC coatings have been studied. The effects were studied by SEM and TEM microscopy, and by H depth-profiling with the ERD technique. Samples prepared by CVD were also implanted for comparison. In the case of H, bubbles have been observed during an in-situ implantation inside the TEM. In order to understand the absence of hydride, H depth-profiling was performed. The H saturation concentration is about 20 at.% or slightly more (the uncertainty is due to the effect of the porosity of the coatings on the ERD technique). Helium bubbles are observed above 10/sup 15/Hecm/sup 2/. Blisters are formed on polished samples above 10/sup 17/Hecm/sup 2/. In contrast, the high roughness of non-polished samples prevents blister formation. CVD samples behave essentially like the polished samples.

  12. Interface characterization of plasma sprayed hydroxy apatite coat on Ti-6 Al-4 V

    International Nuclear Information System (INIS)

    Ghorbani, M.; Afshar, A.; Ehsani, N.; Saeri, R.; Sorrell, C.C.

    2002-01-01

    Hydroxyapatite, a material proven to be biocompatible within the human body, has been produced to a high level of purity. This material has been applied as a coating on Ti-6 Al-4 V alloy by using the air plasma spraying technique.The coat was characterized with SEM, XRD, FTIR and Raman spectroscopy methods to consist of a mixture of calcium phosphates including H A mainly and traces of tricalcium phosphate, tetra calcium phosphate and calcium oxide phases. This H A phase was dehydrated and partially decomposed to oxy apatite and amorphous H A. EPMA method was used cross-sectionally on the interface in order to determine the depth profiles and elemental maps of Calcium, Phosphorous, Oxygen, Titanium, Vanadium and Aluminum elements.The results clearly showed to evidence of interdiffusion at the interface. Ultimately, the diffusion depth of each element was studied and compared with each other

  13. Thermal conductivity of aluminum nitride ceramics. Waermeleitfaehigkeit von Aluminiumnitrid-Keramik

    Energy Technology Data Exchange (ETDEWEB)

    Ruessel, C.; Hofmann, T.; Limmer, G. (Erlangen-Nuernberg Univ., Erlangen (Germany, F.R.). Inst. fuer Werkstoffwissenschaften 3)

    Aluminium nitride ceramics made by the authors, as well as others produced commercially, mostly using yttrium oxide as an additive, were characterized with respect to their phase and chemical composition, their microstructure, and their thermal conductivity. It was shown that conventional ideas, especially with regard to the correlations between thermal conductivity and the oxygen content and the microstructure, could not withstand a critical examination. Instead, a connection can be seen between the oxygen not bound up in yttrium-aluminum garnet and thermal conductivity. Relatively low thermal conductivities were always observed when yttrium-aluminum garnet was present as a grain-boundary phase; in contrast, high values of thermal conductivity were seen when the yttrium-aluminum garnet was present in the form of isolated grains. (orig.).

  14. Thermal stability of hydroxyapatite in biphasic calcium phosphate ceramics

    CSIR Research Space (South Africa)

    Nilen, RWN

    2008-04-01

    Full Text Available temperatures greater than 1125 C. Because the HA/b-TCP ratio dominantly determines the rate and extent of BCP resorption in vivo, the possible thermal decomposition of HA during BCP synthesis must be considered, particularly if high temperature treatments...

  15. Some observations on the high temperature oxidation behaviour of plasma sprayed Ni3Al coatings

    International Nuclear Information System (INIS)

    Singh, H.; Prakash, S.; Puri, D.

    2007-01-01

    High temperature oxidation resistance of the superalloys can be greatly enhanced by plasma sprayed coatings and this is a growing industry of considerable economic importance. The purpose of these coatings is to form long-lasting oxidation protective scales. In the current investigation, Ni 3 Al powder was prepared by mechanical mixing of pure nickel and aluminium powders in a ball mill. Subsequently Ni 3 Al powder was deposited on three Ni-base superalloys: Superni 600, Superni 601 and Superni 718 and, one Fe-base superalloy, Superfer 800H by shrouded plasma spray process. Oxidation studies were conducted on the coated superalloys in air at 900 deg. C under cyclic conditions for 50 cycles. Each cycle consisted of 1 h heating followed by 20 min of cooling in air. The thermogravimetric technique was used to approximate the kinetics of oxidation. All the coated superalloys nearly followed parabolic rate law of oxidation. X-ray diffraction, SEM/EDAX and EPMA techniques were used to analyse the oxidation products. The Ni 3 Al coating was found to be successful in maintaining its adherence to the superalloy substrates in all the cases. The oxide scales formed on the oxidised coated superalloys were found to be intact and spallation-free. XRD analysis revealed the presence of phases like NiO, Al 2 O 3 and NiAl 2 O 4 in the oxide scales, which are reported as protective oxides against high temperature oxidation. The XRD results were further supported by SEM/EDAX and EPMA

  16. Comparison of solidity and fractal dimension of plasma sprayed splat with different spreading morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shu-ying; Ma, Guo-zheng, E-mail: magz0209@163.com; Wang, Hai-dou, E-mail: wanghaidou@aliyun.com.cn; He, Peng-fei; Liu, Ming; Wang, Hai-jun; Xu, Bin-shi

    2017-07-01

    Highlights: • The solidification mechanism of the plasma sprayed droplets deposited on substrate preheated with different temperature was discussed. • The solidified morphology of individual splat was detected by image analysis method. • The fractal dimension, solidity, area and perimeter, were employed to characterize the morphology of the splat. • The typical solidification modes of Fe-based alloy droplet could be divided into three types, namely, flower-like splat, splashed splat and disk-like splat, which may be attributed the differences of solidification rate of the droplets and adsorption on the substrates. - Abstract: The paper deals with the quantitative characterization of spreading morphologies of plasma sprayed Fe-based alloy droplets deposited on mirror polished steels with different preheated temperature. The plasma torch was utilized as heat producer. The influence of substrate temperature on the solidification mechanism of molten droplets was investigated. The image analysis method (IMA) was employed to identify single splat from the field emission scanning electron microscope (FE-SEM) morphology. The result shows that the substrate preheated temperature has a significant effect on the flattening behavior of molten droplets. With the increment of substrate temperature, the solidification mode of splat changes from flower-like and splashed splat to disk-like splat due to the modification of wettability and cooling velocity between molten droplet and substrate. Compared with area and perimeter, both fractal dimension (FD) and solidity could separately detect the solidification mode of splat to a certain extent, while the FD seems to be more excellent in characterizing irregular morphology of splat in contrast with solidity. However, the combination of FD and solidity is more efficient in classifying solidification mode of splat.

  17. Applications in the Nuclear Industry for Thermal Spray Amorphous Metal and Ceramic Coatings

    OpenAIRE

    Blink, J.; Farmer, J.; Choi, J.; Saw, C.

    2009-01-01

    Amorphous metal and ceramic thermal spray coatings have been developed with excellent corrosion resistance and neutron absorption. These coatings, with further development, could be cost-effective options to enhance the corrosion resistance of drip shields and waste packages, and limit nuclear criticality in canisters for the transportation, aging, and disposal of spent nuclear fuel. Iron-based amorphous metal formulations with chromium, molybdenum, and tungsten have shown the corrosion resis...

  18. Effect of alumina-silica-zirconia eutectic ceramic thermal barrier coating on the low cycle fatigue behaviour of cast polycrystalline nickel-based superalloy at 900 °C

    Czech Academy of Sciences Publication Activity Database

    Obrtlík, Karel; Čelko, L.; Chráska, Tomáš; Šulák, Ivo; Gejdoš, P.

    2017-01-01

    Roč. 318, MAY (2017), s. 374-381 ISSN 0257-8972. [RIPT - International Meeting on Thermal Spraying /7./. Limoges, 09.12.2015-12.12.2015] R&D Projects: GA ČR(CZ) GA15-20991S Institutional support: RVO:68081723 ; RVO:61389021 Keywords : Thermal barrier coating * Nickel-based superalloy * Plasma spraying * High temperature fatigue * Fatigue life * Cyclic stress-strain curve Subject RIV: JL - Materials Fatigue, Friction Mechanics; JL - Materials Fatigue, Friction Mechanics (UFP-V) OBOR OECD: Audio engineering, reliability analysis; Audio engineering, reliability analysis (UFM-A); Audio engineering, reliability analysis (UFP-V) Impact factor: 2.589, year: 2016

  19. Failure mechanism for thermal fatigue of thermal barrier coating systems

    Energy Technology Data Exchange (ETDEWEB)

    Giolli, C.; Scrivani, A.; Rizzi, G. [Turbocoating S.p.A., Rubbiano di Solignano (Italy); Borgioli, F. [Firenze Univ., Sesto Fiorentino (Italy); Bolelli, G.; Lusvarghi, L. [Univ. di Modena e Reggio Emilia, Modena (Italy)

    2008-07-01

    High temperature thermal fatigue causes the failure of Thermal Barrier Coating (TBC) systems. Due to the difference in thickness and microstructure between thick TBCs and traditional thin TBCs, they cannot be assumed a-priori to possess the same failure mechanisms. Thick TBCs, consisting of a CoNiCrAlY bond coat and Yttria Partially Stabilised Zirconia top coat with different values of porosity, were produced by Air Plasma Spray. Thermal fatigue resistance limit of TBCs was tested by Furnace Cycling Tests (FCT) according to the specifications of an Original Equipment Manufacturer (OEM). TBC systems were analyzed before and after FCT. The morphological and chemical evolution of CoNiCrAlY/TGO microstructure was studied. Sintering effect, residual stress, phase transformation and fracture toughness were evaluated in the ceramic Top Coat. All the tested samples passed FCT according to the specification of an important OEM. Thermal fatigue resistance increases with the amount of porosity in the top coat. The compressive in-plane stresses increase in the TBC systems after thermal cycling, nevertheless the increasing rate has a trend contrary to the porosity level of top coat. The data suggest that the spallation happens at the TGO/Top Coat interface. The failure mechanism of thick TBCs subjected to thermal fatigue was eventually found to be similar to the failure mechanism of thin TBC systems made by APS. (orig.)

  20. Novel ceramic coatings for containment of uranium and reactive molten metals

    International Nuclear Information System (INIS)

    Sreekumar, K.P.; Satpute, R.U.; Ramanathan, S.; Thiyagarajan, T.K.; Padmanabhan, P.V.A.; Kutty, T.R.G.

    2005-01-01

    Plasma sprayed aluminium oxide coatings, which are currently used for casting uranium metal are, however, not suitable for long duration handling of molten uranium and is also unstable under reducing conditions. Yttrium oxide and rare earth phosphates are suggested as promising materials for prevention of high temperature corrosion by molten metals. The present paper reports research efforts directed towards development of plasma sprayed coatings of yttria and lanthanum phosphate. Thermal spray grade powders of yttrium oxide and lanthanum phosphate, synthesized using locally available raw materials have been used as feedstock powders for plasma spray deposition. The coatings have been deposited using the indigenously developed 40 kW atmospheric plasma spray system and have been characterized. Results of preliminary experiments on compatibility of yttria and lanthanum phosphate with molten uranium are quite encouraging. (author)

  1. Thermal conductivity measurements of PTFE and Al2O3 ceramic at sub-Kelvin temperatures

    Science.gov (United States)

    Drobizhev, Alexey; Reiten, Jared; Singh, Vivek; Kolomensky, Yury G.

    2017-07-01

    The design of low temperature bolometric detectors for rare event searches necessitates careful selection and characterization of structural materials based on their thermal properties. We measure the thermal conductivities of polytetrafluoroethylene (PTFE) and Al2O3 ceramic (alumina) in the temperature ranges of 0.17-0.43 K and 0.1-1.3 K, respectively. For the former, we observe a quadratic temperature dependence across the entire measured range. For the latter, we see a cubic dependence on temperature above 0.3 K, with a linear contribution below that temperature. This paper presents our measurement techniques, results, and theoretical discussions.

  2. Fundamental Thermal and Mechanical Properties of Boride Ceramics

    Science.gov (United States)

    2014-02-28

    Zr ,Y)B2 ( Zr ,Hf)B2 ( Zr ,Ti)B2 ZrB2 El ec tri ca l R es is tiv ity (µ Ω -c m ) Temperature (°C) Figure 17. Electrical resistivity as a function...family as Zr , namely Ti and Hf, had minimal effect on thermal conductivity, while others such as Nb , Ta, and W had an increasing impact based on their...diffusivity (α), heat capacity (Cp) from the NIST-JANAF tables, and bulk density (ρ) using Equation 6. (5) (6) Electrical resistivity

  3. A high temperature ceramic heat exchanger element for a solar thermal receiver

    Science.gov (United States)

    Strumpf, H. J.; Kotchick, D. M.; Coombs, M. G.

    1982-01-01

    The development of a high-temperature ceramic heat exchanger element to be integrated into a solar receiver producing heated air was studied. A number of conceptual designs were developed for heat exchanger elements of differing configuration. These were evaluated with respect to thermal performance, pressure drop, structural integrity, and fabricability. The final design selection identified a finned ceramic shell as the most favorable concept. The shell is surrounded by a larger metallic shell. The flanges of the two shells are sealed to provide a leak-tight pressure vessel. The ceramic shell is to be fabricated by a innovative combination of slip casting the receiver walls and precision casting the heat transfer finned plates. The fins are bonded to the shell during firing. The unit is sized to produce 2150 F air at 2.7 atm pressure, with a pressure drop of about 2 percent of the inlet pressure. This size is compatible with a solar collector providing a receiver input of 85 kw(th). Fabrication of a one-half scale demonstrator ceramic receiver was completed.

  4. High-temperature ceramic heat exchanger element for a solar thermal receiver

    Science.gov (United States)

    Strumpf, H. J.; Kotchick, D. M.; Coombs, M. G.

    1982-01-01

    A study was performed by AiResearch Manufacturing Company, a division of The Garrett Corporation, on the development a high-temperature ceramic heat exchanger element to be integrated into a solar receiver producing heated air. A number of conceptual designs were developed for heat exchanger elements of differing configuration. These were evaluated with respect to thermal performance, pressure drop, structural integrity, and fabricability. The final design selection identified a finned ceramic shell as the most favorable concept. The shell is surrounded by a larger metallic shell. The flanges of the two shells are sealed to provide a leak-tight pressure vessel. The ceramic shell is to be fabricated by an innovative combination of slip casting the receiver walls and precision casting the heat transfer finned plates. The fins are bonded to the shell during firing. The unit is sized to produce 2150 F ar at 2.7 atm pressure, with a pressure drop of about 2 percent of the inlet pressure. This size is compatible with a solar collector providing a receiver input of 85 kw(th). Fabrication of a one-half scale demonstrator ceramic receiver has been completed.

  5. Ceramic/Metal Composites with Positive Temperature Dependence of Thermal Conductivity

    International Nuclear Information System (INIS)

    Li Jianhui; Yu Qi; Sun Wei; Zhang Rui; Wang Ke; Li Jingfeng; Ichigozaki, Daisuke

    2013-01-01

    Most materials show decreasing thermal conductivity with increasing temperature, but an opposite temperature dependence of thermal conductivity is required for some industrial applications. The present work was conducted with a motivation to develop composite materials with a positive temperature dependence of thermal conductivity. ZrO 2 / stainless steel powders (304L) composite, with 3% stearic acid, was prepared by normal sintering under the protecting of Ar after mixing by mechanical ball milling technique. With the 304L content increasing from 10% to 20%, the thermal conductivity values increased. For all samples, the thermal conductivity in the temperature range of room temperature to 700 °C decreased with temperature below 300 °C, and then began to increase. The increasing thermal conductivity of the composites (within the high temperature range was attributed to the difference of the thermal conductivity and thermal expansion coefficient between ZrO 2 ceramic and 304L stainless steel powders. Two simple models were also used to estimate the thermal conductivity of the composites, which were in good agreement with the experiment results.

  6. Development of a fluid model for DC arc plasma torches and its integration with downstream models of atmospheric plasma spray particle plumes

    Science.gov (United States)

    Cannamela, Michael J., III

    The plasma spray process uses plasma flames to melt micron sized particles of e.g. ceramic and propel the droplets to impinge upon and freeze to the target workpiece, forming a functional coating. Variations in the process arise from many sources, and because sensing of the process is imperfect one is motivated to pursue a modeling approach. This dissertation models the major elements of the process; the torch that produces the plasma flame, the jet of hot plasma issuing from the torch, and the plume of particles conveyed and heated by the jet. The plasma in the torch is modeled by a one-fluid magnetohydrodynamic (MHD) approach and it is found that the MHD equations can accurately predict the power dissipated in the bulk of the plasma, while special treatment is required in regions near the electrodes. Treatment of the cathode region is eased since it can be de-coupled from the bulk flow. Treatment of the anode region aims to extract the correct amount of power from the plasma. With MHD in the bulk and these special conditions at the electrode boundaries, the net power into the plasma can be matched with experiment. For one simulation of an SG-100 torch operating at 500A, the measured net power was 7.0kW while the computed net power was 7.1kW. Using outlet information from the torch, the impact of plasma arc oscillations on the free jet and on the in-flight particle states is predicted. The model of the plasma jet is validated against the existing LAVA code, and is able to predict the fraction of entrained air in the jet to within 20% of the experimental value. The variations in particle states due to the arc fluctuations are found to be similar in size to variations due to changes in particle injection velocity, and so cannot be neglected when considering particle state distributions. The end result of this work is to make available a complete chain of models for the plasma spray process, from torch input conditions to in-flight particle state.

  7. HNS steelmaking process using thermal plasma in a ceramic crucible

    International Nuclear Information System (INIS)

    Siwka, J.; Svyazhin, A.G.; Jowsa, J.; Derda, W.

    1999-01-01

    The problems related to HNS (high nitrogen steels) steelmaking technology in a laboratory plasma furnace (100 kW DC, 25 kg liquid metal) are discussed in the paper. Results of investigations on mass transfer in the bath, modelling of the temperature fields by the FEM method, the dynamics of nitriding and refining of the liquid metal are presented. The results show many advantageous features of this technology and identify the necessary modifications. Realization of the one-stage production process of HNS is possible using thermal plasma. This means that any kind of metallic scrap can be used with simultaneous nitriding of liquid metal by nitrogen gas phase and its refining. A technological scheme of the discussed process is presented. (orig.)

  8. Microstructural Improvement of Hydroxyapatite-ZrO2 Composite Ceramics via Thermal Precipitation Techniques.

    Science.gov (United States)

    Sangmala, A.; Limsuwan, P.; Kaewwiset, W.; Naemchanthara, K.

    2017-09-01

    Hydroxyapatite-ZrO2 composite ceramic were synthesized using a thermal precipitation techniques. The chemical precursors were prepared from di-ammonium hydrogen orthophosphate, calcium oxide (CaO) derived from chicken eggshell, zirconium dioxide (ZrO2) and distilled water. The mixture were heated at the various temperatures from 100 to 700 °C in the furnace with an incremental temperature of 100 °C. The ZrO2 contents in the composite ceramic were varied from 0 to 15 percent weight of CaO. The prepared composites were then annealed at 300, 600 and 700 °C for 4 h in air. The crystal structure, function group and morphology of all samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and universal testing machine (UTM), respectively. The results indicated that the undoped-ZrO2 samples hydroxyapatite phase with a hexagonal structure. However, the hydroxyapatite was transformed to the tri-calcium phosphate after thermal treatment at 700 °C. For the doped-ZrO2 samples, the hydroxyapatite and ZrO2 phases were found. Moreover, the result showed that the compressive strength of hydroxyapatite-ZrO2 composite ceramic increased with increasing the ZrO2 content.

  9. Effect of precursor solutions on ZnO film via solution precursor plasma spray and corresponding gas sensing performances

    International Nuclear Information System (INIS)

    Yu, Z.X.; Ma, Y.Z.; Zhao, Y.L.; Huang, J.B.; Wang, W.Z.; Moliere, M.; Liao, H.L.

    2017-01-01

    Highlights: • C-axis preferential oriented grown ZnO films were firstly deposited via SPPS with different solutions. • ZnO films were hydrophobic due to cauliflower and honeycomb-like surface morphologies with high surface specific area. • Gas detecting performance of (002) plane oriented ZnO was predicted and compared by “first principle calculation method”. - Abstract: Solution precursor plasma spraying (SPPS) as a novel thermal spray method was employed to deposit nano-structured ZnO thin film using different formulations of the precursor solution. This article focuses on the influence of the solution composition on the preferential orientation of crystal growth, on crystal size and surface morphology of the resulting ZnO films. The trend of preferential growth along (002) lattice plane of ZnO film was studied by slow scanning X-ray diffraction using a specific coefficient P_(_0_0_2_)_. It appears that the thermal spray process promotes the buildup of ZnO films preferentially oriented along the c-axis. The shape of single particle tends to change from round shaped beads to hexagonal plates by increasing the volume ratio of ethanol in the solvent. Both cauliflower and honeycomb-like surface morphologies featuring high specific surface area and roughness were obtained through the SPPS process by varying solution composition. These ZnO films are hydrophobic with contact angle as high as 136°, which is seemingly associated with micro reliefs developing high surface specific area. Then the gas sensing performances of ZnO films preferentially oriented along (002) face were tentatively predicted using the “first principle calculation method” and were compared with those of conventional films that are mainly oriented along the (101) face. The (002) face displays better hydrogen adsorption capability than the (101) face with much larger resulting changes in electrical resistance. In conclusion, the c-axis oriented ZnO films obtained through SSPS have

  10. Effect of precursor solutions on ZnO film via solution precursor plasma spray and corresponding gas sensing performances

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Z.X., E-mail: zexin.yu@utbm.fr [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Ma, Y.Z., E-mail: yangzhou.ma@outlook.com [School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan 243002 (China); Zhao, Y.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Huang, J.B.; Wang, W.Z. [Key Lab of Safety Science of Pressurized System, Ministry of Education, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China); Moliere, M.; Liao, H.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France)

    2017-08-01

    Highlights: • C-axis preferential oriented grown ZnO films were firstly deposited via SPPS with different solutions. • ZnO films were hydrophobic due to cauliflower and honeycomb-like surface morphologies with high surface specific area. • Gas detecting performance of (002) plane oriented ZnO was predicted and compared by “first principle calculation method”. - Abstract: Solution precursor plasma spraying (SPPS) as a novel thermal spray method was employed to deposit nano-structured ZnO thin film using different formulations of the precursor solution. This article focuses on the influence of the solution composition on the preferential orientation of crystal growth, on crystal size and surface morphology of the resulting ZnO films. The trend of preferential growth along (002) lattice plane of ZnO film was studied by slow scanning X-ray diffraction using a specific coefficient P{sub (002).} It appears that the thermal spray process promotes the buildup of ZnO films preferentially oriented along the c-axis. The shape of single particle tends to change from round shaped beads to hexagonal plates by increasing the volume ratio of ethanol in the solvent. Both cauliflower and honeycomb-like surface morphologies featuring high specific surface area and roughness were obtained through the SPPS process by varying solution composition. These ZnO films are hydrophobic with contact angle as high as 136°, which is seemingly associated with micro reliefs developing high surface specific area. Then the gas sensing performances of ZnO films preferentially oriented along (002) face were tentatively predicted using the “first principle calculation method” and were compared with those of conventional films that are mainly oriented along the (101) face. The (002) face displays better hydrogen adsorption capability than the (101) face with much larger resulting changes in electrical resistance. In conclusion, the c-axis oriented ZnO films obtained through SSPS have

  11. Hollow ceramic block: containment of water for thermal storage in passive solar design. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Winship, C.T.

    1983-12-27

    The project activity has been the development of designs, material compositions and production procedures to manufacture hollow ceramic blocks which contain water (or other heat absorptive liquids). The blocks are designed to serve, in plurality, a dual purpose: as an unobtrusive and efficient thermal storage element, and as a durable and aesthetically appealing surface for floors and walls of passive solar building interiors. Throughout the grant period, numerous ceramic formulas have been tested for their workabilty, thermal properties, maturing temperatures and color. Blocks have been designed to have structural integrity, and textured surfaces. Methods of slip-casting and extrusion have been developed for manufacturing of the blocks. The thermal storage capacity of the water-loaded block has been demonstrated to be 2.25 times greater than that of brick and 2.03 times greater than that of concrete (taking an average of commonly used materials). Although this represents a technical advance in thermal storage, the decorative effects provided by application of the blocks lend them a more significant advantage by reducing constraints on interior design in passive solar architecture.

  12. Thermal Stress and Heat Transfer Coefficient for Ceramics Stalk Having Protuberance Dipping into Molten Metal

    Science.gov (United States)

    Noda, Nao-Aki; Hendra; Li, Wenbin; Takase, Yasushi; Ogura, Hiroki; Higashi, Yusuke

    Low pressure die casting is defined as a net shape casting technology in which the molten metal is injected at high speeds and pressure into a metallic die. The low pressure die casting process plays an increasingly important role in the foundry industry as a low-cost and high-efficiency precision forming technique. In the low pressure die casting process is that the permanent die and filling systems are placed over the furnace containing the molten alloy. The filling of the cavity is obtained by forcing the molten metal, by means of a pressurized gas, to rise into a ceramic tube having protuberance, which connects the die to the furnace. The ceramics tube, called stalk, has high temperature resistance and high corrosion resistance. However, attention should be paid to the thermal stress when the stalk having protuberance is dipped into the molten aluminum. It is important to reduce the risk of fracture that may happen due to the thermal stresses. In this paper, thermo-fluid analysis is performed to calculate surface heat transfer coefficient. The finite element method is applied to calculate the thermal stresses when the stalk having protuberance is dipped into the crucible with varying dipping speeds. It is found that the stalk with or without protuberance should be dipped into the crucible slowly to reduce the thermal stress.

  13. Electrostatic Assembly Preparation of High-Toughness Zirconium Diboride-Based Ceramic Composites with Enhanced Thermal Shock Resistance Performance.

    Science.gov (United States)

    Zhang, Baoxi; Zhang, Xinghong; Hong, Changqing; Qiu, Yunfeng; Zhang, Jia; Han, Jiecai; Hu, PingAn

    2016-05-11

    The central problem of using ceramic as a structural material is its brittleness, which associated with rigid covalent or ionic bonds. Whiskers or fibers of strong ceramics such as silicon carbide (SiC) or silicon nitride (Si3N4) are widely embedded in a ceramic matrix to improve the strength and toughness. The incorporation of these insulating fillers can impede the thermal flow in ceramic matrix, thus decrease its thermal shock resistance that is required in some practical applications. Here we demonstrate that the toughness and thermal shock resistance of zirconium diboride (ZrB2)/SiC composites can be improved simultaneously by introducing graphene into composites via electrostatic assembly and subsequent sintering treatment. The incorporated graphene creates weak interfaces of grain boundaries (GBs) and optimal thermal conductance paths inside composites. In comparison to pristine ZrB2-SiC composites, the toughness of (2.0%) ZrB2-SiC/graphene composites exhibited a 61% increasing (from 4.3 to 6.93 MPa·m(1/2)) after spark plasma sintering (SPS); the retained strength after thermal shock increased as high as 74.8% at 400 °C and 304.4% at 500 °C. Present work presents an important guideline for producing high-toughness ceramic-based composites with enhanced thermal shock properties.

  14. Manufacturing aspheric mirrors made of zero thermal expansion cordierite ceramics using Magnetorheological Finishing (MRF)

    Science.gov (United States)

    Sugawara, Jun; Maloney, Chris

    2016-07-01

    NEXCERATM cordierite ceramics, which have ultra-low thermal expansion properties, are perfect candidate materials to be used for light-weight satellite mirrors that are used for geostationary earth observation and for mirrors used in ground-based astronomical metrology. To manufacture the high precision aspheric shapes required, the deterministic aspherization and figure correction capabilities of Magnetorheological Finishing (MRF) are tested. First, a material compatibility test is performed to determine the best method for achieving the lowest surface roughness of RMS 0.8nm on plano surfaces made of NEXCERATM ceramics. Secondly, we will use MRF to perform high precision figure correction and to induce a hyperbolic shape into a conventionally polished 100mm diameter sphere.

  15. Review of US Nanocorp - SNL Joint Development of Thermal-Sprayed Thin-Film Cathodes for Thermal Batteries

    Energy Technology Data Exchange (ETDEWEB)

    GUIDOTTI,RONALD A.; REINHARDT,FREDERICK W.; DAI,JINXIANG; XIAO,T. DANNY; REISNER,DAVID E.

    2000-11-14

    The use of plasma spray to deposit thin metal-sulfide cathode films is described in this paper. Conventional electroactive stack components in thermal batteries are constructed from pressed-powder parts that are difficult to fabricate in large diameters in thicknesses <0.010. Plasma-sprayed electrodes do not steer from this difficulty, allowing greater energy densities and specific energies to be realized. Various co-spraying agents have been found suitable for improving the mechanical as well as electrochemical properties of plasma-sprayed cathodes for thermal batteries. These electrodes generally show equal or improved performance over conventional pressed-powder electrodes. A number of areas for future growth and development of plasma-spray technology is discussed.

  16. Phase transformations in air plasma-sprayed yttria-stabilized zirconia thermal barrier coatings

    Directory of Open Access Journals (Sweden)

    Julián D. Osorio

    2014-01-01

    Full Text Available En este trabajo, las transformaciones de fase en Recubrimientos de Barrera Térmica (TBC constituidos por ZrO 2 – 8 wt.% Y2O3 (zirconia - 8 wt.% ytrria fueron estudiados a través de Difracción de Rayos X (XRD y refinamiento Rietveld. Las muestras de TBC fueron depositadas mediante aspersión por plasma atmosférico sobre un sustrato tipo Inconel 625 y fueron tratadas térmicamente con dos condiciones diferentes: en la primera se utilizó una temperatura de 1100oC con tiempos de exposición entre 1 hora y 1000 horas; en la segunda las muestras fueron sometidas a temperaturas entre 700oC y 1100o durante 50 horas. De acuerdo a los resultados obtenidos mediante refinamiento Rietveld el contenido de fase cúbica en el recubrimiento (TC se incrementa con el tiempo y la temperatura, desde 7.3 wt.% hasta 15.7 wt.% después de 1000 horas a 1100oC. La fase cúbica en grandes cantidades es indeseable debido a que presenta inferiores propiedades mecánicas cuando se compara con la fase tetragonal. Después de 800 horas de exposición a alta temperatura, el contenido de Y2O3 en la fase tetragonal se reduce hasta 6.6 wt.% y una fracción de la fase tetragonal transforma a monoclínica durante el enfriamiento. La fase monoclínica alcanza 18.0 wt.% después de 1000 horas. Esta fase es también indeseable porque además de tener una mayor conductividad térmica, la transformación de tetragonal a monoclínica viene acompañada de un cambio volumétrico de alrededor de 5% que promueve la formación y propagación de grietas, las cuales comprometen la integridad del recubrimiento.

  17. Structural analysis and thermal behavior of diopside-fluorapatite-wollastonite-based glasses and glass-ceramics.

    Science.gov (United States)

    Kansal, Ishu; Tulyaganov, Dilshat U; Goel, Ashutosh; Pascual, Maria J; Ferreira, José M F

    2010-11-01

    Glass-ceramics in the diopside (CaMgSi2O6)-fluorapatite (Ca5(PO4)3F)-wollastonite (CaSiO3) system are potential candidates for restorative dental and bone implant materials. The present study describes the influence of varying SiO2/CaO and CaF2/P2O5 molar ratio on the structure and thermal behavior of glass compositions in the CaO-MgO-SiO2-P2O5-Na2O-CaF2 system. The structural features and properties of the glasses were investigated by nuclear magnetic resonance (NMR), infrared spectroscopy, density measurements and dilatometry. Sintering and crystallization behavior of the glass powders were studied by hot-stage microscopy and differential thermal analysis, respectively. The microstructure and crystalline phase assemblage in the sintered glass powder compacts were studied under non-isothermal heating conditions at 825 °C. X-ray diffraction studies combined with the Rietveld-reference intensity ratio (R.I.R) method were employed to quantify the amount of amorphous and crystalline phases in the glass-ceramics, while scanning electron microscopy was used to shed some light on the microstructure of resultant glass-ceramics. An increase in CaO/SiO2 ratio degraded the sinterability of the glass powder compacts, resulting in the formation of akermanite as the major crystalline phase. On the other hand, an increase in P2O5/CaF2 ratio improved the sintering behavior of the glass-ceramics, while varying the amount of crystalline phases, i.e. diopside, fluorapatite and wollastonite. Copyright © 2010. Published by Elsevier Ltd.

  18. Incorporation of tungsten metal fibers in a metal and ceramic matrix

    Czech Academy of Sciences Publication Activity Database

    Brožek, Vlastimil; Vokáč, M.; Kolísko, J.; Pokorný, P.; Kubatík, Tomáš František

    2017-01-01

    Roč. 56, 1-2 (2017), s. 79-82 ISSN 0543-5846 Institutional support: RVO:61389021 Keywords : tungsten wires * tungsten fibers * plasma spraying * metallic coatings * ceramic coatings Subject RIV: JI - Composite Materials OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics http://hrcak.srce.hr/168890

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

    International Nuclear Information System (INIS)

    Chung, Shen Shou Max; Chuang, Yu-Chou

    2016-01-01

    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. (paper)

  20. Numerical study of melted particles crush metallic substrates and the interaction between particles and a plasma beam in the thermal projection process

    International Nuclear Information System (INIS)

    Kriba, Ilhem; Djebaili, A.

    2009-01-01

    Plasma spray processes have been widely used to produce high performance coatings of a wide range of materials (metallic, non-metallic, and ceramics), offering protection from, e.g. wear, extreme temperature, chemical attack and environmental corrosion. To obtain good quality coatings, spray parameters must be carefully selected. Due to the large variety in process parameters, it is difficult to optimize the process for each specific coating and substrate combinations. Furthermore modelling the spray process allows a better understanding of the process sequences during thermal spraying. The simulation of coating formation to estimate the process parameters is an important tool to develop new coating structures with defined properties. In this work, the process of plasma sprayed coating has been analyzed by numerical simulation. Commercial code is used to predict the plasma jet characteristics, plasma-particle interaction, and coating formation. Using this model we can obtain coating microstructure and characteristics which form a foundation for further improvement of an advanced ceramic coating build up model

  1. Lightweight Ablative and Ceramic Thermal Protection System Materials for NASA Exploration Systems Vehicles

    Science.gov (United States)

    Valentine, Peter G.; Lawrence, Timothy W.; Gubert, Michael K.; Milos, Frank S.; Kiser, James D.; Ohlhorst, Craig W.; Koenig, John R.

    2006-01-01

    As a collaborative effort among NASA Centers, the "Lightweight Nonmetallic Thermal Protection Materials Technology" Project was set up to assist mission/vehicle design trade studies, to support risk reduction in thermal protection system (TPS) material selections, to facilitate vehicle mass optimization, and to aid development of human-rated TPS qualification and certification plans. Missions performing aerocapture, aerobraking, or direct aeroentry rely on advanced heatshields that allow reductions in spacecraft mass by minimizing propellant requirements. Information will be presented on candidate materials for such reentry approaches and on screening tests conducted (material property and space environmental effects tests) to evaluate viable candidates. Seventeen materials, in three classes (ablatives, tiles, and ceramic matrix composites), were studied. In additional to physical, mechanical, and thermal property tests, high heat flux laser tests and simulated-reentry oxidation tests were performed. Space environmental effects testing, which included exposures to electrons, atomic oxygen, and hypervelocity impacts, was also conducted.

  2. A comparative analysis of reticular crack on ceramic plate driven by thermal shock

    Science.gov (United States)

    Xu, XiangHong; Sheng, ShiLong; Tian, Cheng; Yuan, WenJun

    2016-07-01

    Reticular crack is generally found on the surface of ceramic material that has been subjected to a thermal-shock condition. In the present study, a quantitative effect of thermal shock and quench temperature has been studied and investigated. Experimental tests were carried out to characterize the reticular crack that has been found in the Ge Kiln, which is a famous art of the ancient Chinese culture. After comparative analysis between thermal-shock cracks and the glaze crack patterns of the Ge Kiln porcelain, it is found that this study is expected to provide a powerful tool for recurrence of the long-lost firing and cooling process of the Ge Kiln porcelain.

  3. Non linear thermal behaviour induced by damage of ceramic matrix composite

    International Nuclear Information System (INIS)

    El-Yagoubi, J.

    2011-10-01

    In this work the relationship between the evolution of damage and the loss of thermal properties of Ceramic Matrix Composites is investigated by a multi-scale approach. Research are conducted both experimentally and theoretically. The implemented approach is to consider two significant scales (micro and meso) where different damage mechanisms are operating and then assess the effect on the effective thermal properties by homogenization techniques. Particular attention has been given to the development of a thorough experimental work combining various characterization tools (mechanical, thermal and microstructural). At the two aforementioned scales, an experimental setup was designed to perform thermal measurements on CMC under tensile test. Thermal diffusivity of mini-composites is estimated using Lock-in thermography. Also, transverse diffusivity mapping as well as global in-plane diffusivity of woven CMC are determined by suitable rear face flash methods. The evolution of damage is then derived from acoustic emission activity along with postmortem microstructural observations. Experimental results are systematically compared to simulations. At microscale, a micromechanical-based model is used to simulate the loss of thermal conductivity of a mini-composite under tensile test. At mesoscale, a multi-scale Finite Element Model is proposed to compute the effect of damage on thermal properties of woven CMC. (author) [fr

  4. Implications of electronic short circuiting in plasma sprayed solid oxide fuel cells on electrode performance evaluation by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    White, B.D. [Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Sciences Lane, Vancouver, British Columbia (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, Ontario (Canada)

    2008-02-15

    Electronic short circuiting of the electrolyte in a solid oxide fuel cell (SOFC) arising from flaws in the plasma spray fabrication process has been found to have a significant effect on the perceived performance of the electrodes, as evaluated by electrochemical impedance spectroscopy (EIS). The presence of a short circuit has been found to lead to the underestimation of the electrode polarization resistance (R{sub p}) and hence an overestimation of electrode performance. The effect is particularly noticeable when electrolyte resistance is relatively high, for example during low to intermediate temperature operation, leading to an obvious deviation from the expected Arrhenius-type temperature dependence of R{sub p}. A method is developed for determining the real electrode performance from measurements of various cell properties, and strategies for eliminating the occurrence of short circuiting in plasma sprayed cells are identified. (author)

  5. Implications of electronic short circuiting in plasma sprayed solid oxide fuel cells on electrode performance evaluation by electrochemical impedance spectroscopy

    Science.gov (United States)

    White, B. D.; Kesler, O.

    Electronic short circuiting of the electrolyte in a solid oxide fuel cell (SOFC) arising from flaws in the plasma spray fabrication process has been found to have a significant effect on the perceived performance of the electrodes, as evaluated by electrochemical impedance spectroscopy (EIS). The presence of a short circuit has been found to lead to the underestimation of the electrode polarization resistance (R p) and hence an overestimation of electrode performance. The effect is particularly noticeable when electrolyte resistance is relatively high, for example during low to intermediate temperature operation, leading to an obvious deviation from the expected Arrhenius-type temperature dependence of R p. A method is developed for determining the real electrode performance from measurements of various cell properties, and strategies for eliminating the occurrence of short circuiting in plasma sprayed cells are identified.

  6. Synthesis of mullite-based coatings from alumina and zircon powder mixtures by plasma spraying and laser remelting

    International Nuclear Information System (INIS)

    Hazra, S.; Das, J.; Bandyopadhyay, P.P.

    2015-01-01

    A mechanical mixture of alumina and pulverized zircon sand in 3:2 M ratio has been plasma sprayed to obtain mullite coating. Thereafter, the top layer of the coating has been remelted using laser. The presence of a mullite phase in the as-sprayed and laser remelted coatings has been confirmed qualitatively using X-ray diffraction. Both as-sprayed and laser remelted coatings have been characterized for their microstructure, hardness and porosity. The ultrafine grain structure of the coating produced by rapid quenching has been analyzed using transmission electron microscope. Presence of a mullite phase in the coatings has also been confirmed using small angle electron diffraction. Laser remelting has resulted in an appreciable reduction in porosity and increase in hardness in the coatings. - Highlights: • Mullite has been produced by plasma spraying of alumina–zircon powder mixture. • As sprayed coating shows good integrity. • Laser remelting reduced porosity and increased coating hardness

  7. Synthesis of mullite-based coatings from alumina and zircon powder mixtures by plasma spraying and laser remelting

    Energy Technology Data Exchange (ETDEWEB)

    Hazra, S. [Integrated Test Range, Chandipur, Balasore, Odisha 756025 (India); Das, J. [Department of Metallurgical and Materials Engineering, IIT Kharagpur, 721302 (India); Bandyopadhyay, P.P., E-mail: ppb@mech.iitkgp.ernet.in [Department of Mechanical Engineering, IIT Kharagpur, 721302 (India)

    2015-03-15

    A mechanical mixture of alumina and pulverized zircon sand in 3:2 M ratio has been plasma sprayed to obtain mullite coating. Thereafter, the top layer of the coating has been remelted using laser. The presence of a mullite phase in the as-sprayed and laser remelted coatings has been confirmed qualitatively using X-ray diffraction. Both as-sprayed and laser remelted coatings have been characterized for their microstructure, hardness and porosity. The ultrafine grain structure of the coating produced by rapid quenching has been analyzed using transmission electron microscope. Presence of a mullite phase in the coatings has also been confirmed using small angle electron diffraction. Laser remelting has resulted in an appreciable reduction in porosity and increase in hardness in the coatings. - Highlights: • Mullite has been produced by plasma spraying of alumina–zircon powder mixture. • As sprayed coating shows good integrity. • Laser remelting reduced porosity and increased coating hardness.

  8. Very low pressure plasma sprayed yttria-stabilized zirconia coating using a low-energy plasma gun

    International Nuclear Information System (INIS)

    Zhu, Lin; Zhang, Nannan; Bolot, Rodolphe; Planche, Marie-Pierre; Liao, Hanlin; Coddet, Christian

    2011-01-01

    In the present study, a more economical low-energy plasma source was used to perform a very low pressure plasma-spray (VLPPS) process. The plasma-jet properties were analyzed by means of optical emission spectroscopy (OES). Moreover, yttria-stabilized zirconia coating (YSZ) was elaborated by a F100 low-power plasma gun under working pressure of 1 mbar, and the substrate specimens were partially shadowed by a baffle-plate during plasma spraying for obtaining different coating microstructures. Based on the SEM observation, a column-like grain coating was deposited by pure vapor deposition at the shadowed region, whereas, in the unshadowed region, the coating exhibited a binary microstructure which was formed by a mixed deposition of melted particles and evaporated particles. The mechanical properties of the coating were also well under investigation. (orig.)

  9. Ceramics and healthy heating and cooling systems: thermal ceramic panels in buildings. Conditions of comfort and energy demand versus convective systems

    Directory of Open Access Journals (Sweden)

    V. Echarri Iribarren

    2016-12-01

    Full Text Available Porcelain stoneware is a widely used building material. In recent years, its range of uses has expanded to encompass a new spectrum of innovative and inventive applications in architecture. In this research, we analysed the patented Thermal Ceramic Panel. This consists of a thin porcelain stoneware panel that incorporates a capillary system of polypropylene tubes measuring 3.5 mm in diameter embedded in a conductive ceramic interface. The system works with hot or cold water, producing healthy heating and cooling by means of radiant surfaces. Following an initial prototype test in which panels were placed on the walls of an office, we conducted simulations at the University of Alicante Museum using wall, ceiling and baffle panels, having previously monitored the state of the building. Thermal behaviour parameters were analysed and compared with those of other standard finishing materials, obtaining results for thermal comfort and energy savings in comparison with all-air systems.

  10. Examination of Internally and Externally Coated Cr3C2 Exhaust Pipe of a Diesel Engine via Plasma Spray Method

    OpenAIRE

    H. Hazar; S. Sap

    2017-01-01

    In this experimental study; internal and external parts of an exhaust pipe were coated with a chromium carbide (Cr3C2) material having a thickness of 100 micron by using the plasma spray method. A diesel engine was used as the test engine. Thus, the results of continuing chemical reaction in coated and uncoated exhaust pipes were investigated. Internally and externally coated exhaust pipe was compared with the standard exhaust system. External heat transfer occurring as a result of coating th...

  11. Preparation and properties of plasma sprayed NiAl10 and NiAl40 coatings on AZ91 substrate.

    Czech Academy of Sciences Publication Activity Database

    Kubatík, Tomáš František; Lukáč, František; Stoulil, J.; Ctibor, Pavel; Průša, F.; Stehlíková, K.

    2017-01-01

    Roč. 319, June (2017), s. 145-154 ISSN 0257-8972 R&D Projects: GA ČR(CZ) GP14-31538P Institutional support: RVO:61389021 Keywords : Nickel aluminide * AZ91 magnesium alloy * Plasma spraying * Potentiodynamic measurement * Adhesion strength Subject RIV: JJ - Other Materials OBOR OECD: Materials engineering Impact factor: 2.589, year: 2016 http://www.sciencedirect.com/science/article/pii/S0257897217303250

  12. Effect of Fluctuations of DC Current on Properties of Plasma Jet Generated in Plasma Spraying Torch with Gerdien Arc

    Czech Academy of Sciences Publication Activity Database

    Hrabovský, Milan; Kopecký, Vladimír; Chumak, Oleksiy; Kavka, Tetyana; Mašláni, Alan; Sember, Viktor; Ctibor, Pavel

    2009-01-01

    Roč. 13, č. 2 (2009), s. 229-240 ISSN 1093-3611 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma torch * dc arc * plasma jet * fluctuations * plasma spraying Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.333, year: 2009 http://www.begellhouse.com/journals/57d172397126f956,4e2a92412d8c6bb5.html

  13. 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

  14. 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

  15. Fabrication of High Temperature Cermet Materials for Nuclear Thermal Propulsion

    Science.gov (United States)

    Hickman, Robert; Panda, Binayak; Shah, Sandeep

    2005-01-01

    Processing techniques are being developed to fabricate refractory metal and ceramic cermet materials for Nuclear Thermal Propulsion (NTP). Significant advances have been made in the area of high-temperature cermet fuel processing since RoverNERVA. Cermet materials offer several advantages such as retention of fission products and fuels, thermal shock resistance, hydrogen compatibility, high conductivity, and high strength. Recent NASA h d e d research has demonstrated the net shape fabrication of W-Re-HfC and other refractory metal and ceramic components that are similar to UN/W-Re cermet fuels. This effort is focused on basic research and characterization to identify the most promising compositions and processing techniques. A particular emphasis is being placed on low cost processes to fabricate near net shape parts of practical size. Several processing methods including Vacuum Plasma Spray (VPS) and conventional PM processes are being evaluated to fabricate material property samples and components. Surrogate W-Re/ZrN cermet fuel materials are being used to develop processing techniques for both coated and uncoated ceramic particles. After process optimization, depleted uranium-based cermets will be fabricated and tested to evaluate mechanical, thermal, and hot H2 erosion properties. This paper provides details on the current results of the project.

  16. Measurement of the thermal diffusivity on ceramics and metals using the laser flash method

    International Nuclear Information System (INIS)

    Blumm, J.; Sauseng, B.

    2001-01-01

    diffusivity. Presented in this work are thermal diffusivity results on various kinds of industrial relevant materials such as metals or ceramics. Additionally the application of the laser flash technique on liquid materials and multi-laser samples is discussed. (author)

  17. Cyclic oxidation behavior of plasma sprayed NiCrAlY/WC-Co/cenosphere coating

    Science.gov (United States)

    Mathapati, Mahantayya; Ramesh M., R.; Doddamani, Mrityunjay

    2018-04-01

    Components working at elevated temperature like boiler tubes of coal and gas fired power generation plants, blades of gas and steam turbines etc. experience degradation owing to oxidation. Oxidation resistance of such components can be increased by developing protective coatings. In the present investigation NiCrAlY-WC-Co/Cenosphere coating is deposited on MDN 321 steel substrate using plasma spray coating. Thermo cyclic oxidation behavior of coating and substrate is studied in static air at 600 °C for 20 cycles. The thermo gravimetric technique is used to approximate the kinetics of oxidation. X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray mapping techniques are used to characterize the oxidized samples. NiCrAlY-WC-Co/Cenosphere coating exhibited lower oxidation rate in comparison to MDN 321 steel substrate. The lower oxidation rate of coating is attributed to formation of Al2O3, Cr2O3, NiO and CoWO4 oxides on the outermost surface.

  18. Computer model of polycrystal structure formation of plasma sprayed Be coatings

    International Nuclear Information System (INIS)

    Tyupkina, O.G.; Meshchankin, N.V.; Sarymsakov, D.A.

    1996-01-01

    One of problems of controlled thermonuclear syntheses reactor creation is obtaining of a material, having significant radiation firmness. Perspective materials from this point of view might be ones obtained by Be plasma spraying on substrate. The analytical method of Be coating durability properties is impossible because of varied inter effective processes, taking place in crystallizing bodies, and experimental one requires significant financial spends. In the present article an attempt is made to estimate the influence of different regimes of cooling on forming polycrystal structure, to analyse dynamics of liquid coating solidifying using method of computer simulation. The research of number and sizes of grain distribution in the layers change was carried out in different regimes of cooling. For this purpose coefficient of heat exchanged was varied in the equation describing process of heat exchange between Be and substrate. Results obtained with proposed model well correspond with pattern observed in practice. Therefore a computer model of crystallization was developed, which allows to obtain characteristics of element acts of crystallization out coming from macroscopic parameters of sample, and to observe the process of melted Be solidifying

  19. Air plasma spray processing and electrochemical characterization of SOFC composite cathodes

    Science.gov (United States)

    White, B. D.; Kesler, O.; Rose, Lars

    Air plasma spraying has been used to produce porous composite cathodes containing (La 0.8Sr 0.2) 0.98MnO 3- y (LSM) and yttria-stabilized zirconia (YSZ) for use in solid oxide fuel cells (SOFCs). Preliminary investigations focused on determining the range of plasma conditions under which each of the individual materials could be successfully deposited. A range of conditions was thereby determined that was suitable for the deposition of a composite cathode from pre-mixed LSM and YSZ powders. A number of composite cathodes were produced using different combinations of parameter values within the identified range according to a Uniform Design experimental grid. Coatings were then characterized for composition and microstructure using EDX and SEM. As a result of these tests, combinations of input parameter values were identified that are best suited to the production of coatings with microstructures appropriate for use in SOFC composite cathodes. A selection of coatings representative of the types of observed microstructures were then subjected to electrochemical testing to evaluate the performance of these cathodes. From these tests, it was found that, in general, the coatings that appeared to have the most suitable microstructures also had the highest electrochemical performances, provided that the deposition efficiency of both phases was sufficiently high.

  20. Permeability and Microstructure of Suspension Plasma-Sprayed YSZ Electrolytes for SOFCs on Various Substrates

    Science.gov (United States)

    Marr, Michael; Kesler, Olivera

    2012-12-01

    Yttria-stabilized zirconia electrolyte coatings for solid oxide fuel cells were deposited by suspension plasma spraying using a range of spray conditions and a variety of substrates, including finely structured porous stainless steel disks and cathode layers on stainless steel supports. Electrolyte permeability values and trends were found to be highly dependent on which substrate was used. The most gas-tight electrolyte coatings were those deposited directly on the porous metal disks. With this substrate, permeability was reduced by increasing the torch power and reducing the stand-off distance to produce dense coating microstructures. On the substrates with cathodes, electrolyte permeability was reduced by increasing the stand-off distance, which reduced the formation of segmentation cracks and regions of aligned and concentrated porosity. The formation mechanisms of the various permeability-related coating features are discussed and strategies for reducing permeability are presented. The dependences of electrolyte deposition efficiency and surface roughness on process conditions and substrate properties are also presented.

  1. Air plasma spray processing and electrochemical characterization of SOFC composite cathodes

    Energy Technology Data Exchange (ETDEWEB)

    White, B.D. [Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Sciences Lane, Vancouver, British Columbia (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, Ontario (Canada); Rose, Lars [Department of Materials Engineering, The University of British Columbia, 309-6350 Stores Road, Vancouver, British Columbia (Canada); National Research Council (Canada)

    2008-03-15

    Air plasma spraying has been used to produce porous composite cathodes containing (La{sub 0.8}Sr{sub 0.2}){sub 0.98}MnO{sub 3-y} (LSM) and yttria-stabilized zirconia (YSZ) for use in solid oxide fuel cells (SOFCs). Preliminary investigations focused on determining the range of plasma conditions under which each of the individual materials could be successfully deposited. A range of conditions was thereby determined that was suitable for the deposition of a composite cathode from pre-mixed LSM and YSZ powders. A number of composite cathodes were produced using different combinations of parameter values within the identified range according to a Uniform Design experimental grid. Coatings were then characterized for composition and microstructure using EDX and SEM. As a result of these tests, combinations of input parameter values were identified that are best suited to the production of coatings with microstructures appropriate for use in SOFC composite cathodes. A selection of coatings representative of the types of observed microstructures were then subjected to electrochemical testing to evaluate the performance of these cathodes. From these tests, it was found that, in general, the coatings that appeared to have the most suitable microstructures also had the highest electrochemical performances, provided that the deposition efficiency of both phases was sufficiently high. (author)

  2. Electrochemical testing of suspension plasma sprayed solid oxide fuel cell electrolytes

    Science.gov (United States)

    Waldbillig, D.; Kesler, O.

    Electrochemical performance of metal-supported plasma sprayed (PS) solid oxide fuel cells (SOFCs) was tested for three nominal electrolyte thicknesses and three electrolyte fabrication conditions to determine the effects of electrolyte thickness and microstructure on open circuit voltage (OCV) and series resistance (R s). The measured OCV values were approximately 90% of the Nernst voltages, and electrolyte area specific resistances below 0.1 Ω cm 2 were obtained at 750 °C for electrolyte thicknesses below 20 μm. Least-squares fitting was used to estimate the contributions to R s of the YSZ bulk material, its microstructure, and the contact resistance between the current collectors and the cells. It was found that the 96% dense electrolyte layers produced from high plasma gas flow rate conditions had the lowest permeation rates, the highest OCV values, and the smallest electrolyte-related voltage losses. Optimal electrolyte thicknesses were determined for each electrolyte microstructure that would result in the lowest combination of OCV loss and voltage loss due to series resistance for operating voltages of 0.8 V and 0.7 V.

  3. 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.

  4. Method of forming a plasma sprayed interconnection layer on an electrode of an electrochemical cell

    Science.gov (United States)

    Spengler, Charles J.; Folser, George R.; Vora, Shailesh D.; Kuo, Lewis; Richards, Von L.

    1995-01-01

    A dense, substantially gas-tight, electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO.sub.3 particles doped with an element selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by plasma spraying doped LaCrO.sub.3 powder, preferably compensated with chromium as Cr.sub.2 O.sub.3 and/or dopant element, preferably by plasma arc spraying; and, (C) heating the doped and compensated LaCrO.sub.3 layer to about 1100.degree. C. to 1300.degree. C. to provide a dense, substantially gas-tight, substantially hydration-free, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the unselected portion of the air electrode, and a fuel electrode can be applied to the solid electrolyte, to provide an electrochemical cell.

  5. Process maps for plasma spray: Part 1: Plasma-particle interactions

    International Nuclear Information System (INIS)

    Gilmore, Delwyn L.; Neiser, Richard A. Jr.; Wan, Yuepeng; Sampath, Sanjay

    2000-01-01

    This is the first paper of a two part series based on an integrated study carried out at Sandia National Laboratories and the State University of New York at Stony Brook. The aim of the study is to develop a more fundamental understanding of plasma-particle interactions, droplet-substrate interactions, deposit formation dynamics and microstructural development as well as final deposit properties. The purpose is to create models that can be used to link processing to performance. Process maps have been developed for air plasma spray of molybdenum. Experimental work was done to investigate the importance of such spray parameters as gun current, auxiliary gas flow, and powder carrier gas flow. In-flight particle diameters, temperatures, and velocities were measured in various areas of the spray plume. Samples were produced for analysis of microstructures and properties. An empirical model was developed, relating the input parameters to the in-flight particle characteristics. Multi-dimensional numerical simulations of the plasma gas flow field and in-flight particles under different operating conditions were also performed. In addition to the parameters which were experimentally investigated, the effect of particle injection velocity was also considered. The simulation results were found to be in good general agreement with the experimental data

  6. Microstructure and corrosive wear resistance of plasma sprayed Ni-based coatings after TIG remelting

    Science.gov (United States)

    Tianshun, Dong; Xiukai, Zhou; Guolu, Li; Li, Liu; Ran, Wang

    2018-02-01

    Ni based coatings were prepared on steel substrate by means of plasma spraying, and were remelted by TIG (tungsten inert gas arc) method subsequently. The microstructure, microhardness, electrochemical corrosion and corrosive wear resistance under PH = 4, PH = 7 and PH = 10 conditions of the coatings before and after remelting were investigated. The results showed that the TIG remelting obviously reduced the defects and dramatically decreased the coating’s porosity from 7.2% to 0.4%. Metallurgical bonding between the remelted coating and substrate was achieved. Meanwhile, the phase compositions of as-sprayed coating were γ-Ni, Mn5Si2 and Cr2B, while the phase compositions of the remelting coating were Fe3Ni, Cr23C6, Cr2B and Mn5Si2. The microhardness of the coating decreased from 724 HV to 608 HV, but the fracture toughness enhanced from 2.80 MPa m1/2 to 197.3 MPa m1/2 after remelting. After corrosive wear test, the average wear weight loss and 3D morphology of wear scar of two coatings indicated that the wear resistance of the remelted coating was remarkably higher than that of as-sprayed coating. Therefore, TIG remelting treatment was a feasible method to improve the coating’s microstructure and enhance its corrosive wear resistance.

  7. Correlation of microstructure and wear resistance of molybdenum blend coatings fabricated by atmospheric plasma spraying

    International Nuclear Information System (INIS)

    Hwang, Byoungchul; Lee, Sunghak; Ahn, Jeehoon

    2004-01-01

    The correlation of microstructure and wear resistance of various molybdenum blend coatings applicable to automotive parts was investigated in this study. Five types of spray powders, one of which was pure molybdenum powder and the others were blends of brass, bronze, and aluminum alloy powders with molybdenum powder, were deposited on a low-carbon steel substrate by atmospheric plasma spraying (APS). Microstructural analysis of the coatings showed that they consisted of a curved lamellar structure formed by elongated splats, with hard phases that formed during spraying being homogeneously distributed in the molybdenum matrix. The wear test results revealed that the blend coatings showed better wear resistance than the pure molybdenum coating because they contained a number of hard phases. In particular, the molybdenum coating blended with bronze and aluminum alloy powders and the counterpart material showed an excellent wear resistance due to the presence of hard phases, such as CuAl 2 and Cu 9 Al 4 . In order to improve overall wear properties for the coating and the counterpart material, appropriate spray powders should be blended with molybdenum powders to form hard phases in the coatings

  8. Deposition of nanostructured photocatalytic zinc ferrite films using solution precursor plasma spraying

    International Nuclear Information System (INIS)

    Dom, Rekha; Sivakumar, G.; Hebalkar, Neha Y.; Joshi, Shrikant V.; Borse, Pramod H.

    2012-01-01

    Highlights: ► Highly economic solution precursor route capable of producing films/coating even for mass scale production. ► Pure spinel phase ZnFe 2 O 4 porous, immobilized films deposited in single step. ► Parameter optimization yields access to nanostructuring in SPPS method. ► The ecofriendly immobilized ferrite films were active under solar radiation. ► Such magnetic system display advantage w.r.t. recyclability after photocatalyst extraction. -- Abstract: Deposition of pure spinel phase, photocatalytic zinc ferrite films on SS-304 substrates by solution precursor plasma spraying (SPPS) has been demonstrated for the first time. Deposition parameters such as precursor solution pH, concentration, film thickness, plasma power and gun-substrate distance were found to control physico-chemical properties of the film, with respect to their crystallinity, phase purity, and morphology. Alkaline precursor conditions (7 2 O 4 film. Very high/low precursor concentrations yielded mixed phase, less adherent, and highly inhomogeneous thin films. Desired spinel phase was achieved in as-deposited condition under appropriately controlled spray conditions and exhibited a band gap of ∼1.9 eV. The highly porous nature of the films favored its photocatalytic performance as indicated by methylene blue de-coloration under solar radiation. These immobilized films display good potential for visible light photocatalytic applications.

  9. 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.

  10. Analytical interpretation of arc instabilities in a DC plasma spray torch: the role of pressure

    Science.gov (United States)

    Rat, V.; Coudert, J. F.

    2016-06-01

    Arc instabilities in a plasma spray torch are investigated experimentally and theoretically thanks to a linear simplified analytical model. The different parameters that determine the useful properties of the plasma jet at the torch exit, such as specific enthalpy and speed, but also pressure inside the torch and time variations of the flow rate are studied. The work is particularly focused on the link between the recorded arc voltage and the pressure in the cathode cavity. A frequency analysis of the recorded voltage and pressure allows the separation of different contributions following their spectral characteristics and highlights a resonance effect due to Helmholtz oscillations; these oscillations are responsible for the large amplitude fluctuations of all the parameters investigated. The influence of heat transfer, friction forces and residence time of the plasma in the nozzle are taken into account, thanks to different characteristics’ times. The volume of the cathode cavity in which the cold gas is stored before entering the arc region appears to be of prime importance for the dynamics of instabilities, particularly for the non-intuitive effect that induces flow-rate fluctuations in spite of the fact that the torch is fed at a constant flow rate.

  11. 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.

  12. 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.

    2017-03-01

    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.

  13. Thermophysical Properties of Cold and Vacuum Plasma Sprayed Cu-Cr-X Alloys, NiAl and NiCrAlY Coatings. Part 2; Specific Heat Capacity

    Science.gov (United States)

    Raj, S. V.

    2017-01-01

    Part I of the paper discussed the temperature dependencies of the electrical resistivities, thermal conductivities, thermal diffusivities and total hemispherical emissivities of several vacuum plasma sprayed (VPS) and cold sprayed copper alloy monolithic coatings, VPS NiAl, VPS NiCrAlY, extruded GRCop-84 and as-cast Cu-17(wt.%)Cr-5%Al. Part II discusses the temperature dependencies of the constant pressure specific heat capacities, CP, of these coatings. The data were empirically were regression-fitted with the equation: CP = AT4 + BT3 + CT2 + DT +E where T is the absolute temperature and A, B, C, D and E are regression constants. The temperature dependencies of the molar enthalpy, molar entropy and Gibbs molar free energy determined from experimental values of molar specific heat capacity are reported. Calculated values of CP using the Neumann-Kopp (NK) rule were in poor agreement with experimental data. Instead, a modification of the Neumann-Kopp rule was found to predict values closer to the experimental data with an absolute deviation less than 6.5%. The specific molar heat capacities for all the alloys did not agree with the Dulong-Petit law, and CP is greater than 3R, where R is the universal gas constant, were measured for all the alloys except NiAl for which CP is less than 3R at all temperatures.

  14. Thermal Protection of Carbon Fiber-Reinforced Composites by Ceramic Particles

    Directory of Open Access Journals (Sweden)

    Baljinder Kandola

    2016-06-01

    Full Text Available The thermal barrier efficiency of two types of ceramic particle, glass flakes and aluminum titanate, dispersed on the surface of carbon-fiber epoxy composites, has been evaluated using a cone calorimeter at 35 and 50 kW/m2, in addition to temperature gradients through the samples’ thicknesses, measured by inserting thermocouples on the exposed and back surfaces during the cone tests. Two techniques of dispersing ceramic particles on the surface have been employed, one where particles were dispersed on semi-cured laminate and the other where their dispersion in a phenolic resin was applied on the laminate surface, using the same method as used previously for glass fiber composites. The morphology and durability of the coatings to water absorption, peeling, impact and flexural tension were also studied and compared with those previously reported for glass-fiber epoxy composites. With both methods, uniform coatings could be achieved, which were durable to peeling or water absorption with a minimal adverse effect on the mechanical properties of composites. While all these properties were comparable to those previously observed for glass fiber composites, the ceramic particles have seen to be more effective on this less flammable, carbon fiber composite substrate.

  15. Applications in the Nuclear Industry for Thermal Spray Amorphous Metal and Ceramic Coatings

    Science.gov (United States)

    Blink, J.; Farmer, J.; Choi, J.; Saw, C.

    2009-06-01

    Amorphous metal and ceramic thermal spray coatings have been developed with excellent corrosion resistance and neutron absorption. These coatings, with further development, could be cost-effective options to enhance the corrosion resistance of drip shields and waste packages, and limit nuclear criticality in canisters for the transportation, aging, and disposal of spent nuclear fuel. Iron-based amorphous metal formulations with chromium, molybdenum, and tungsten have shown the corrosion resistance believed to be necessary for such applications. Rare earth additions enable very low critical cooling rates to be achieved. The boron content of these materials and their stability at high neutron doses enable them to serve as high efficiency neutron absorbers for criticality control. Ceramic coatings may provide even greater corrosion resistance for waste package and drip shield applications, although the boron-containing amorphous metals are still favored for criticality control applications. These amorphous metal and ceramic materials have been produced as gas-atomized powders and applied as near full density, nonporous coatings with the high-velocity oxy-fuel process. This article summarizes the performance of these coatings as corrosion-resistant barriers and as neutron absorbers. This article also presents a simple cost model to quantify the economic benefits possible with these new materials.

  16. Influence of gas pressure on the effective thermal conductivity of ceramic breeder pebble beds

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Weijing [School of Civil Engineering, The University of Sydney, Sydney (Australia); Pupeschi, Simone [Institute for Applied Materials, Karlsruhe Institute of Technology (KIT) (Germany); Hanaor, Dorian [School of Civil Engineering, The University of Sydney, Sydney (Australia); Institute for Materials Science and Technologies, Technical University of Berlin (Germany); Gan, Yixiang, E-mail: yixiang.gan@sydney.edu.au [School of Civil Engineering, The University of Sydney, Sydney (Australia)

    2017-05-15

    Highlights: • This study explicitly demonstrates the influence of the gas pressure on the effective thermal conductivity of pebble beds. • The gas pressure influence is shown to correlated to the pebble size. • The effective thermal conductivity is linked to thermal-mechanical properties of pebbles and packing structure. - Abstract: Lithium ceramics have been considered as tritium breeder materials in many proposed designs of fusion breeding blankets. Heat generated in breeder pebble beds due to nuclear breeding reaction must be removed by means of actively cooled plates while generated tritiums is recovered by purge gas slowly flowing through beds. Therefore, the effective thermal conductivity of pebble beds that is one of the governing parameters determining heat transport phenomenon needs to be addressed with respect to mechanical status of beds and purge gas pressure. In this study, a numerical framework combining finite element simulation and a semi-empirical correlation of gas gap conduction is proposed to predict the effective thermal conductivity. The purge gas pressure is found to vary the effective thermal conductivity, in particular with the presence of various sized gaps in pebble beds. Random packing of pebble beds is taken into account by an approximated correlation considering the packing factor and coordination number of pebble beds. The model prediction is compared with experimental observation from different sources showing a quantitative agreement with the measurement.

  17. Influence of gas pressure on the effective thermal conductivity of ceramic breeder pebble beds

    International Nuclear Information System (INIS)

    Dai, Weijing; Pupeschi, Simone; Hanaor, Dorian; Gan, Yixiang

    2017-01-01

    Highlights: • This study explicitly demonstrates the influence of the gas pressure on the effective thermal conductivity of pebble beds. • The gas pressure influence is shown to correlated to the pebble size. • The effective thermal conductivity is linked to thermal-mechanical properties of pebbles and packing structure. - Abstract: Lithium ceramics have been considered as tritium breeder materials in many proposed designs of fusion breeding blankets. Heat generated in breeder pebble beds due to nuclear breeding reaction must be removed by means of actively cooled plates while generated tritiums is recovered by purge gas slowly flowing through beds. Therefore, the effective thermal conductivity of pebble beds that is one of the governing parameters determining heat transport phenomenon needs to be addressed with respect to mechanical status of beds and purge gas pressure. In this study, a numerical framework combining finite element simulation and a semi-empirical correlation of gas gap conduction is proposed to predict the effective thermal conductivity. The purge gas pressure is found to vary the effective thermal conductivity, in particular with the presence of various sized gaps in pebble beds. Random packing of pebble beds is taken into account by an approximated correlation considering the packing factor and coordination number of pebble beds. The model prediction is compared with experimental observation from different sources showing a quantitative agreement with the measurement.

  18. Thermally and optically stimulated luminescence of AlN-Y2O3 ceramics after ionising irradiation

    DEFF Research Database (Denmark)

    Trinkler, L.; Bos, A.J.J.; Winkelman, A.J.M.

    1999-01-01

    , an essential drawback of AlN-Y2O3 is its high fading rate. Special attention has been focused on understanding and improving the fading properties. In particular, the influence of the ceramics production conditions and the additive concentration on the fading rate have been studied. Experimental results......Thermally (TL) and optically stimulated luminescence (OSL) were studied in AlN-Y2O3 ceramics after irradiation with ionising radiation. The extremely high TL sensitivity (approximately 60 times the sensitivity of LiF:Mg,Tl (TLD-100)) makes AlN-Y2O3 ceramics attractive as a TLD material. However...... on spectral properties and thermal evolution of OSL are also presented. The stimulation spectrum covers the spectral range from green to infrared light. A combination of thermal and optical stimulation allowed a correlation to be found between parameters of OSL and TL after the same irradiation dose...

  19. Formation of Green compact structure of low-temperature ceramics with taking into account the thermal degradation of the binder

    Science.gov (United States)

    Tovpinets, A. O.; Leytsin, V. N.; Dmitrieva, M. A.; Ivonin, I. V.; Ponomarev, S. V.

    2017-12-01

    The solution of the tasks in the field of creating and processing materials for additive technologies requires the development of a single theory of materials for various applications and processes. A separate class of materials that are promising for use in additive technologies includes materials whose consolidation is ensured by the presence of low-melting components in the initial mixture which form a matrix at a temperature not exceeding the melting point, recrystallization or destruction of any of the responsible refractory components of the initial dispersion. The study of the contribution of the binder thermal destruction to the structure and phase composition of the initial compact of the future composite is essential for the development of modern technologies for the synthesis of low-temperature ceramics. This paper investigates the effect of the thermal destruction of a binder on the formation of a green compact of low-temperature ceramics and the structural-mechanical characteristics of sintered ceramics. The approach proposed in Ref. [1] for evaluating the structure and physical characteristics of sintered low-temperature ceramics is improved to clarify the structure of green compacts obtained after thermal destruction of the polymer binder, with taking into account the pores formed and the infusible residue. The obtained results enable a more accurate prediction of thermal stresses in the matrix of sintered ceramics and serve as a basis for optimization.

  20. The glass-like thermal conductivity in ZrO2-Dy3TaO7 ceramic for promising thermal barrier coating application

    Science.gov (United States)

    Wu, Peng; Hu, Ming Yu; Chong, Xiao Yu; Feng, Jing

    2018-03-01

    Using the solid-state reaction method, the (ZrO2)x-(Dy3TaO7)1-x (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.1) ceramics are synthesized in this work. The identification of the crystal structures indicates that the (ZrO2)x-(Dy3TaO7)1-x ceramics belong to the orthorhombic system, and the space group is C2221 in spite of the value of x increasing to 0.1. The thermal conductivities of the (ZrO2)x-(Dy3TaO7)1-x ceramics range from 1.3 W/(m K) to 1.8 W/(m K), and this value is much lower than that of 7-8 YSZ (yttria-stabilized zirconia). Besides, the (ZrO2)x-(Dy3TaO7)1-x ceramics possess the glass-like thermal conductivity caused by intrinsic oxygen vacancies existing in the lattice of Dy3TaO7. Moreover, the results of thermal expansion rates demonstrate that the (ZrO2)x-(Dy3TaO7)1-x ceramics possess excellent high temperature phase stability, and the thermal expansion coefficients [(9.7-11) × 10-6 K-1] are comparable to that of 7-8 YSZ.