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Sample records for spray ceramic coatings

  1. Material design of ceramic coating by plasma spray method

    International Nuclear Information System (INIS)

    Nakamichi, M.; Kawamura, H.; Takabatake, T.

    1998-01-01

    In the ceramic coating on substrate, cracking and peeling occur due to the difference of thermal expansion between substrate material and coating material. For evaluation of peeling property of plasma sprayed coating, it is demanded that thermal properties of plasma sprayed coating are estimated in detail. In this study, the results of comparison of thermal properties between bulk material and plasma sprayed material are investigated to design the ceramic coating quantitatively. Thermal conductivity of plasma sprayed MgO.Al 2 O 3 is decreased by approximately 50% to that of sintered MgO.Al 2 O 3 . Thermal conductivity of plasma sprayed 410SS agreed well with the calculation results of relation between porosity and thermal conductivity of iron sintered material. Thermal expansions of atmospheric plasma sprayed MgO.Al 2 O 3 and bulk 410SS, respectively. Therefore, as to material design on ceramic coating, it was made clear that thermal conductivity is more important than thermal expansion. (orig.)

  2. 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.)

  3. 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.

  4. 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

  5. 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...

  6. 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.

  7. 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.)

  8. Characterization of nanostructured ceramic and cermet coatings deposited by plasma spraying

    OpenAIRE

    Sánchez Vilches, Enrique Javier; Bannier, Emilie; Vicent, Mónica; Moreno Berto, Arnaldo; Salvador Moya, María Dolores; Bonache Bezares, Victoria; Klyatskina, Elizabeta; Boccaccini, Aldo R.

    2011-01-01

    Industry has a growing need of advanced coatings for a variety of applications (aerospace, special machinery, medicine ...). Nanostructured coatings have the potential of providing novel materials with enhanced properties. This paper describes the results of recent research on wear resistant nanostructured coatings. Cermet (WC- Co) and ceramic (Al2O3-TiO2) coatings were obtained by atmospheric plasma spraying. Coating microstructure and phase composition were characterized using SEM, EDX and ...

  9. Essential Factors Influencing the Bonding Strength of Cold-Sprayed Aluminum Coatings on Ceramic Substrates

    Science.gov (United States)

    Drehmann, R.; Grund, T.; Lampke, T.; Wielage, B.; Wüstefeld, C.; Motylenko, M.; Rafaja, D.

    2018-02-01

    The present work summarizes the most important results of a research project dealing with the comprehensive investigation of the bonding mechanisms between cold-sprayed Al coatings and various poly- and monocrystalline ceramic substrates (Al2O3, AlN, Si3N4, SiC, MgF2). Due to their exceptional combination of properties, metallized ceramics are gaining more and more importance for a wide variety of applications, especially in electronic engineering. Cold spray provides a quick, flexible, and cost-effective one-step process to apply metallic coatings on ceramic surfaces. However, since most of the existing cold-spray-related publications focus on metallic substrates, only very little is known about the bonding mechanisms acting between cold-sprayed metals and ceramic substrates. In this paper, the essential factors influencing the bonding strength in such composites are identified. Besides mechanical tensile strength testing, a thorough analysis of the coatings and especially the metal/ceramic interfaces was conducted by means of HRTEM, FFT, STEM, EDX, EELS, GAXRD, and EBSD. The influence of substrate material, substrate temperature, and particle size is evaluated. The results suggest that, apart from mechanical interlocking, the adhesion of cold-sprayed metallic coatings on ceramics is based on a complex interplay of different mechanisms such as quasiadiabatic shearing, static recrystallization, and heteroepitaxial growth.

  10. DEVELOPMENT OF COMPLEX EQUIPMENT FOR PLASMA SPRAY CERAMIC COATINGS

    Directory of Open Access Journals (Sweden)

    V. V. Okovity

    2017-01-01

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

  11. Mechanical and tribological performance of coated ceramic tiles with alumina by thermal spraying process

    Directory of Open Access Journals (Sweden)

    Marilse Araque-Pabón

    2015-07-01

    Full Text Available Mechanical and tribological performance of red clay ceramic tiles uncoated and coated by oxy-fuel thermal spraying process from α-Al2O3 powder was evaluated. The ceramic tile substrates were manufactured by uniaxial pressing at 30 bar pressure, and sintered at 1100°C, while alumina Sulzer-Metco 105SPFTM was used as feedstock powder to elaborate coatings with three different thicknesses. Both, the bending and the deep abrasion resistances were evaluated according to ISO 10545-4 e ISO 10545-6 standards respectively. The results obtained indicate that the deep abrasion in the ceramic tiles decreases when the thickness of alumina coating increases. On the other hand, the bending resistance of ceramic tiles coated increased between 5 and 49% regarding to those uncoated. These results contribute to the development of ceramic products with high value added, which can be used in various technological applications.

  12. 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

  13. 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.

  14. 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_

  15. 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.

  16. Ceramic electrolyte coating methods

    Energy Technology Data Exchange (ETDEWEB)

    Seabaugh, Matthew M.; Swartz, Scott L.; Dawson, William J.; McCormick, Buddy E.

    2004-10-12

    Processes for preparing aqueous suspensions of a nanoscale ceramic electrolyte material such as yttrium-stabilized zirconia. The invention also includes a process for preparing an aqueous coating slurry of a nanoscale ceramic electrolyte material. The invention further includes a process for depositing an aqueous spray coating slurry including a ceramic electrolyte material on pre-sintered, partially sintered, and unsintered ceramic substrates and products made by this process.

  17. Spray process for in situ synthesizing Ti(C,N)-TiB2-Al2O3 composite ceramic coatings

    Science.gov (United States)

    Zhou, Jian; Liu, Hongwei; Sun, Sihao

    2017-12-01

    Using core wires with Ti-B4C-C as core and Al as strip materials, Ti(C,N)-TiB2-Al2O3 composite ceramic coatings were prepared on 45 steel substrates by the reactive arc spray technology. The influence of spray voltage, current, gas pressure and distance on the coatings was discussed. The spray parameters were optimized with porosity of the coatings as evaluation standard. The results showed that the most important factor which influences the quality of the coatings was spray distance. Then spray gas pressure, current and voltage followed in turn. The optimum process was spray current of 120A, voltage of 36, gas pressure of 0.7MPa and distance of 160mm. The porosity of coatings prepared in this spray process was only 2.11%. The coatings were composed of TiB2, TiC0.3N0.7, TiN, Al2O3 and AlN. Good properties and uniform distribution of these ceramic phases made the coatings have excellent comprehensive performances.

  18. Optimizing the vacuum plasma spray deposition of metal, ceramic, and cermet coatings using designed experiments

    Science.gov (United States)

    Kingswell, R.; Scott, K. T.; Wassell, L. L.

    1993-06-01

    The vacuum plasma spray (VPS) deposition of metal, ceramic, and cermet coatings has been investigated using designed statistical experiments. Processing conditions that were considered likely to have a significant influence on the melting characteristics of the precursor powders and hence deposition efficiency were incorporated into full and fractional factorial experimental designs. The processing of an alumina powder was very sensitive to variations in the deposition conditions, particularly the injection velocity of the powder into the plasma flame, the plasma gas composition, and the power supplied to the gun. Using a combination of full and fractional factorial experimental designs, it was possible to rapidly identify the important spraying variables and adjust these to produce a deposition efficiency approaching 80 percent. The deposition of a nickel-base alloy metal powder was less sensitive to processing conditions. Generally, however, a high degree of particle melting was achieved for a wide range of spray conditions. Preliminary experiments performed using a tungsten carbide/cobalt cermet powder indicated that spray efficiency was not sensitive to deposition conditions. However, microstructural analysis revealed considerable variations in the degree of tungsten carbide dissolution. The structure and properties of the optimized coatings produced in the factorial experiments are also discussed.

  19. Development of Thermal Spraying and Coating Techniques by Using Thixotropic Slurries Including Metals and Ceramics Particles

    International Nuclear Information System (INIS)

    Kirihara, S; Tasaki, S; Itakura, Y

    2013-01-01

    Thermal nanoparticles coating and microlines patterning were newly developed as novel technologies to fabricate fine ceramics layers and geometrical intermetallics patterns for mechanical properties modulations of practical alloys substrates. Nanometer sized alumina particles were dispersed into acrylic liquid resins, and the obtained slurries were sputtered by using compressed air jet. The slurry mists could blow into the arc plasma with argon gas spraying. On stainless steels substrates, the fine surface layers with high wear resistance were formed. In cross sectional microstructures of the coated layers, micromater sized cracks or pores were not observed. Subsequently, pure aluminum particles were dispersed into photo solidified acrylic resins, and the slurry was spread on the stainless steel substrates by using a mechanical knife blade. On the substrates, microline patterns with self similar fractal structures were drawn and fixed by using scanning of an ultra violet laser beam. The patterned pure metal particles were heated by the argon arc plasma spray assisting, and the intermetallics or alloys phases with high hardness were created through reaction diffusions. Microstructures in the coated layers and the patterned lines were observed by using a scanning electron microscopy.

  20. 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

  1. 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

  2. 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 (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

  3. Bond strength of plasma sprayed ceramic coatings on the phosphated steels

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2015-04-01

    Full Text Available In the presented work, results of adhesion measurements for different systems of steel sheet-phosphate interlayer-ceramiccoating are described. The interlayers were produced by zinc phosphating; alumina, olivine and zirconiasilica-alumina (e.g. eucor coatings were deposited by water stabilized plasma torch WSP®. However, successful application of the WSP technique depends on the choice of correct deposition parameters preserving the hydrated phosphates from thermal destruction by the molten ceramic particles. For the adhesion measurement ISO 4624standardized test was used. Corrosion resistivity was measured by polarisation resistance and free corrosion potential in 3 % NaCl solution.

  4. Investigation of the microstructure of Ni and B4C ceramic-metal mixtures obtained by cold spray coating and followed by laser cladding

    Science.gov (United States)

    Filippov, A. A.; Fomin, V. M.; Orishich, A. M.; Malikov, A. G.; Ryashin, N. S.; Golyshev, A. A.

    2017-10-01

    In the present work, a combined method is considered for the production of a metal-matrix composite coating based on Ni and B4C. The coating is created by consistently applied methods: cold spray and laser cladding. Main focus of this work aimed to microstructure of coatings, element content and morphology of laser tracks. At this stage, the authors focused on the interaction of the laser unit with the substance without affecting the layer-growing technology products. It is shown that coating has deformed particles of nickel and the significantly decreased content of ceramic particles B4C after cold spray. After laser cladding there are no boundaries between nickel and dramatically changes in ceramic particles.

  5. 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 %.

  6. 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

  7. Plasma sprayed ceramic coatings without and with epoxy resin sealing treatment and their wear resistance

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Neufuss, Karel; Zahálka, F.; Kolman, Blahoslav Jan

    2007-01-01

    Roč. 262, 9-10 (2007), s. 1274-1280 ISSN 0043-1648 R&D Projects: GA AV ČR 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : Epoxy sealing * Alumina * Alumina-titania * Dry abrasion * Slurry abrasion Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.395, year: 2007

  8. Excellent stability of plasma-sprayed bioactive Ca3ZrSi2O9 ceramic coating on Ti-6Al-4V

    International Nuclear Information System (INIS)

    Liang Ying; Xie Youtao; Ji Heng; Huang Liping; Zheng Xuebin

    2010-01-01

    In this work, novel zirconium incorporated Ca-Si based ceramic powder Ca 3 ZrSi 2 O 9 was synthesized. The aim of this study was to fabricate Ca 3 ZrSi 2 O 9 coating onto Ti-6Al-4V substrate using atmospheric plasma-spraying technology and to evaluate its potential applications in the fields of orthopedics and dentistry. The phase composition, surface morphologies of the coating were examined by XRD and SEM, which revealed that the Ca 3 ZrSi 2 O 9 coating was composed of grains around 100 nm and amorphous phases. The bonding strength between the coating and the substrate was 28 ± 4 MPa, which is higher than that of traditional HA coating. The dissolution rate of the coating was assessed by monitoring the ions release and mass loss after immersion in the Tris-HCl buffer solution. The in vitro bioactivity of the coating was determined by observing the formation of apatite on its surface in simulated body fluids. It was found that the Ca 3 ZrSi 2 O 9 coating possessed both excellent chemical stability and good apatite-formation ability, suggesting its potential use as bone implants.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. Plasma Processes: Plasma sprayed alumina coatings for radiation ...

    Indian Academy of Sciences (India)

    Conventional design of radiation detectors uses sintered ceramic insulating modules. The major drawback of these ceramic components is their inherent brittleness. Ion chambers, in which these ceramic spacers are replaced by metallic components with plasma spray coated alumina, have been developed in our Research ...

  11. Plasma sprayed alumina coatings for radiation detector development

    Indian Academy of Sciences (India)

    Abstract. Conventional design of radiation detectors uses sintered ceramic insulating modules. The major drawback of these ceramic components is their inherent brittleness. Ion chambers, in which these ceramic spacers are replaced by metallic components with plasma spray coated alumina, have been developed in our ...

  12. Microplasma sprayed hydroxyapatite coatings

    CERN Document Server

    Dey, Arjun

    2015-01-01

    ""This unique book on development of microplasma sprayed HAp coating has been organized in a very compact yet comprehensive manner. This book also highlights the horizons of future research that invites the attention of global community, particularly those in bio-medical materials and bio-medical engineering field. This book will surely act as a very useful reference material for both graduate/post-graduate students and researchers in the field of biomedical, orthopedic and manufacturing engineering and research. I truly believ that this is the first ever effort which covers almost all the

  13. Coated ceramic breeder materials

    Science.gov (United States)

    Tam, Shiu-Wing; Johnson, Carl E.

    1987-01-01

    A breeder material for use in a breeder blanket of a nuclear reactor is disclosed. The breeder material comprises a core material of lithium containing ceramic particles which has been coated with a neutron multiplier such as Be or BeO, which coating has a higher thermal conductivity than the core material.

  14. 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

  15. Spray coated nanosilver functional layers

    Science.gov (United States)

    Krzemiński, J.; Szałapak, J.; Dybowska-Sarapuk, L.; Jakubowska, M.

    2016-09-01

    Silver coatings are highly conductive functional layers. There are many different ways to product the silver coating but most of them need vacuum or high temperature. Spray coating is a technique that is free of this disadvantages - it doesn't need a cleanroom or high temperature. What's more the layer thickness is about 10 μm. In this article the spray coating process of silver nanolayer is described. Four different inks were tested and measured. The layer resistance was measured and show as a graph. After the layer resistance was measured the adhesion test was performed. The pull-off test was performed on testing machine with special self made module. To conclude the article include the test and measurements of spray coated nanosilver functional layers. The layers was examined for the current conductivity and adhesion force.

  16. Microstructures and properties of double-ceramic-layer thermal barrier coatings of La2(Zr0.7Ce0.3)2O7/8YSZ made by atmospheric plasma spraying

    Science.gov (United States)

    Chen, Shuhai; Xiang, Jianying; Huang, Jihua; Zhao, Xingke

    2015-06-01

    A double-ceramic-layer (DCL) thermal barrier coatings (TBC) of La2(Zr0.7Ce0.3)2O7/8YSZ (LZ7C3/8YSZ) was prepared by atmospheric plasma spraying (APS). The phase structure, composition, thermal conductivity, surface and cross-sectional morphologies, adhesion strength and thermal shock behavior of the LZ7C3/8YSZ coating were investigated. The X-ray diffraction pattern showed that the phase structures of top coat LZ7C3 was different from the powder for spraying, which consists of pyrochlore LZ and fluorite LC structures. Main peaks between LZ and LC in as-sprayed LZ7C3 have almost overlapping diffracted angles and approximately equal diffracted intensity. Thermal shock lifetime and adhesion strength of the DCL LZ7C3/8YSZ coating are enhanced significantly as compared to single LZ7C3 coating, and are very close to that of single 8YSZ coating. The mechanisms of performance improvement are considered to be effictive reduction of stress concentration between substrate and LZ7C3 coating by 8YSZ buffer effect, and the gentle thermal gradient initiated at the time of quenching in water. The DCL LZ7C3/8YSZ coating has lower thermal conductivity than 8YSZ, which was only 25% of 8YSZ bulk material and 65% of 8YSZ coating by APS.

  17. Microstructural and mechanical evaluation of laser-assisted cold sprayed bio-ceramic coatings: potential use for biomedical applications

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2014-02-01

    Full Text Available Bio-composite coatings of 20 wt.%, HAP and 80 wt.%, HAP were synthesized on Ti-6Al-4V substrates using LACS technique. The coatings were produced with a laser power of 2.5 kW, powder-laser spot trailing by 5 s. The coatings were analyzed...

  18. Applications and properties of thermally sprayed oxide ceramics

    International Nuclear Information System (INIS)

    Pawlowski, L.

    1991-01-01

    After a brief discussion of the general properties of thermally sprayed oxide ceramics, some of the more important materials are discussed in detail. The electric properties of Al 2 O 3 , such as electric resistivity, dielectric constant and dielectric strength, are shown together with the applications of thermally sprayed alumina coatings in 'corona rolls' and substrates in hybrid microelectronics. The thermal conductivity of ZrO 2 stabilized with a different Y 2 O 3 content is discussed together with the coatings' microstructure. The research on the development of zirconia coatings for application in the advanced turbines is briefly described. The mechanical properties of thermally sprayed Cr 2 O 3 coatings as well as their microstructure are shown. As chromia coatings often contain suboxides or even metallic chromium, a special powder giving metal free deposits has been developed and the coatings sprayed therefrom are applied in the printing industry as 'anilox rolls'. Finally, microstructure and some electrical properties of a high temperature superconductor YBa 2 CU 3 O 7-x are presented. (orig.) [de

  19. Dilation Behavior of Thermal Spray Coatings

    Science.gov (United States)

    Bejarano Lopez, Miryan Lorena

    Thermal Spray (TS) is a very versatile manufacturing process to deposit thick coatings on a variety of substrates. Coatings are used in protective (i.e. wear, chemical attack, high temperature, etc.) and functional (i.e. sensors) applications. TS coatings have a unique lamellar microstructure as a result of the overlapping of millions of molten and partially-molten particles. During processing, high deformation by impact, high temperature, and rapid solidification lead to a complex hierarchical material system that contains a high amount of microstructural defects. The presence of defects in the microstructure contribute to differences in property values in comparison to bulk materials. Thermal stresses and residual strains arise from processing, thermal gradients and thermal exposure. Evaluation of thermal properties, in this case, the coefficient of thermal expansion (CTE) is of vital importance to enhance coating performance. In this dissertation, expansion measurements of various metals, alloys, ceramics, and cermet coatings; were carried out using various techniques (push rod dilatometry, x-ray diffraction XRD, digital image correlation DIC, and curvature method) to determine the dilation behavior at the atomic, micro- and macro-scale levels. The main results were. 1) Mathematical models (Turner and Kerner) used for composite materials, successfully predicted the CTE property of a TS coating where the primary phase is the coating material and the secondary phases can be oxides, precipitates, etc. (formed as a byproduct of the spraying process). CTE was found not to be affected by porosity. 2) Despite the anisotropic behavior characteristic of TS coatings, the experimental results shown that CTE results to be reasonable isotropic within the scope of this study. 3) The curvature method was found to be an alternative technique to obtain the CTE, as well as the Young's modulus of coating in a bi-material strip, with good approximation. 4) An anomalous expansion

  20. Production of Composite Ceramic Material for Thermal Spraying

    OpenAIRE

    Оковитый, В. А.; Пантелеенко, Ф. И.; Оковитый, В. В.; Асташинский, В. М.

    2017-01-01

    A composite ceramic material has been developed for thermal spraying that permits to increase wear resistance due to introduction of high-chromium steel and molybdenum in its structure, to obtain optimum porosity in the starting charge material while synthesizing  FeCrMo – MoS2/CaF2/С – TiC compositions,  to improve technological parameters of powders and thereby increase coefficient of powder usage in spraying, to reduce cost of wear-resistant coating technology. The paper presents character...

  1. Abrasion resistance of alloy coatings deposited by plasma spraying

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Lescoffit, A.-E.; Teboul, B.; Neufuss, Karel; Voleník, Karel

    2009-01-01

    Roč. 54, č. 2 (2009), s. 113-126 ISSN 0001-7043 R&D Projects: GA AV ČR 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma spraying * alloy coatings * slurry abrasion * hardness and microhardness Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  2. 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.

  3. Plasma spraying of ceramic powders produced by the sol-gel technique

    International Nuclear Information System (INIS)

    Joshi, S.V.; Ganguli, D.

    1992-01-01

    The development of plasma-sprayed protective layers to enhance the surface properties of critical engineering components represents one of the most promising achievements of materials technology in recent times. The important aspects associated with plasma spraying of ceramic powders are discussed and the influence of the powder characteristics on the quality of sprayed coatings is highlighted. The advantages of the sol-gel technique for preparing spray grade powders are briefly outlined. The sol-gel synthesis of a Yttria-stabilized-zirconia powder is discussed as a case study. Results of powder characterization studies and evaluation of its plasma sprayed coating are also presented. (author). 28 refs., 5 figs., 1 tab

  4. Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rajendra Bordia

    2009-07-31

    processing techniques for these coatings. In addition, we investigated the effect of microstructure on the mechanical properties and oxidation protection ability of the coatings. Coatings were developed to provide oxidation protection to both ferritic and austentic alloys and Ni-based alloys. The coatings that we developed are based on low viscosity pre-ceramic polymers. Thus they can be easily applied to any shape by using a variety of techniques including dip-coating, spray-coating and painting. The polymers are loaded with a variety of nanoparticles. The nanoparticles have two primary roles: control of the final composition and phases (and hence the properties); and control of the shrinkage during thermal decomposition of the polymer. Thus the selection of the nanoparticles was the most critical aspect of this project. Based on the results of the processing studies, the performance of selected coatings in oxidizing conditions (both static and cyclic) was investigated.

  5. 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...

  6. Ceramic thermal barrier coatings for electric utility gas turbine engines

    Science.gov (United States)

    Miller, R. A.

    1986-01-01

    Research and development into thermal barrier coatings for electric utility gas turbine engines is reviewed critically. The type of coating systems developed for aircraft applications are found to be preferred for clear fuel electric utility applications. These coating systems consists of a layer of plasma sprayed zirconia-yttria ceramic over a layer of MCrAly bond coat. They are not recommended for use when molten salts are presented. Efforts to understand coating degradation in dirty environments and to develop corrosion resistant thermal barrier coatings are discussed.

  7. Properties of Plasma and HVOF Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Wojciech Żórawski

    2012-11-01

    Full Text Available The work compares the properties of plasma and HVOF thermally sprayed coatings obtained by blending the NiCrBSi and Fe2O3 powders. The deposition was performed by means of the Plancer PN-120 and the Diamond Jet guns for plasma spraying and HVOF spraying respectively. The SEM (EDS method was employed to study the microstructure of the produced coatings. Although the blended powders differ in particle size, shape, and distribution, it is possible to obtain composite coatings with an NiCrBSi matrix containing iron oxides. Except for a different microstructure, plasma and HVOF coatings have a different phase composition, which was examined using the Bruker D-8 Advance diffractometer. Studies of the coatings wear and scuffing resistance showed that an optimal content of Fe2O3 is about 26 % for plasma sprayed coatings and 22.5 % for HVOF deposited coatings.

  8. Nano-Ceramic Coated Plastics

    Science.gov (United States)

    Cho, Junghyun

    2013-01-01

    Plastic products, due to their durability, safety, and low manufacturing cost, are now rapidly replacing cookware items traditionally made of glass and ceramics. Despite this trend, some still prefer relatively expensive and more fragile ceramic/glassware because plastics can deteriorate over time after exposure to foods, which can generate odors, bad appearance, and/or color change. Nano-ceramic coatings can eliminate these drawbacks while still retaining the advantages of the plastic, since the coating only alters the surface of the plastic. The surface coating adds functionality to the plastics such as self-cleaning and disinfectant capabilities that result from a photocatalytic effect of certain ceramic systems. These ceramic coatings can also provide non-stick surfaces and higher temperature capabilities for the base plastics without resorting to ceramic or glass materials. Titanium dioxide (TiO2) and zinc oxide (ZnO) are the candidates for a nano-ceramic coating to deposit on the plastics or plastic films used in cookware and kitchenware. Both are wide-bandgap semiconductors (3.0 to 3.2 eV for TiO2 and 3.2 to 3.3 eV for ZnO), so they exhibit a photocatalytic property under ultraviolet (UV) light. This will lead to decomposition of organic compounds. Decomposed products can be easily washed off by water, so the use of detergents will be minimal. High-crystalline film with large surface area for the reaction is essential to guarantee good photocatalytic performance of these oxides. Low-temperature processing (plastics. One possible way of processing nanoceramic coatings at low temperatures (plastic materials (silicone, Teflon, PET, etc.) that can possess both photocatalytic oxide properties and flexible plastic properties. Processing cost is low and it does not require any expensive equipment investment. Processing can be scalable to current manufacturing infrastructure.

  9. Cold-Sprayed AZ91D Coating and SiC/AZ91D Composite Coatings

    Directory of Open Access Journals (Sweden)

    Yingying Wang

    2018-03-01

    Full Text Available As an emerging coating building technique, cold spraying has many advantages to elaborate Mg alloy workpieces. In this study, AZ91D coatings and AZ91D-based composite coatings were deposited using cold spraying. Coatings were prepared using different gas temperatures to obtain the available main gas temperature. Compressed air was used as the accelerating gas, and although magnesium alloy is oxidation-sensitive, AZ91D coatings with good performance were obtained. The results show that dense coatings can be fabricated until the gas temperature is higher than 500 °C. The deposition efficiency increases greatly with the gas temperature, but it is lower than 10% for all coating specimens. To analyze the effects of compressed air on AZ91D powder particles and the effects of gas temperature on coatings, the phase composition, porosity, cross-sectional microstructure, and microhardness of coatings were characterized. X-ray diffraction and oxygen content analysis clarified that no phase transformation or oxidation occurred on AZ91D powder particles during cold spraying processes with compressed air. The porosity of AZ91D coatings remained between 3.6% and 3.9%. Impact melting was found on deformed AZ91D particles when the gas temperature increased to 550 °C. As-sprayed coatings exhibit much higher microhardness than as-casted bulk magnesium, demonstrating the dense structure of cold-sprayed coatings. To study the effects of ceramic particles on cold-sprayed AZ91D coatings, 15 vol % SiC powder particles were added into the feedstock powder. Lower SiC content in the coating than in the feedstock powder means that the deposition efficiency of the SiC powder particles is lower than the deposition efficiency of AZ91D particles. The addition of SiC particles reduces the porosity and increases the microhardness of cold-sprayed AZ91D coatings. The corrosion behavior of AZ91D coating and SiC reinforced AZ91D composite coating were examined. The Si

  10. Ceramic with zircon coating

    Science.gov (United States)

    Wang, Hongyu (Inventor)

    2003-01-01

    An article comprises a silicon-containing substrate and a zircon coating. The article can comprise a silicon carbide/silicon (SiC/Si) substrate, a zircon (ZrSiO.sub.4) intermediate coating and an external environmental/thermal barrier coating.

  11. Tantalum oxide-based plasma-sprayed environmental barrier coatings

    Science.gov (United States)

    Weyant, Christopher M.

    Energy efficiency in gas turbine engines is linked to the high temperature capabilities of materials used in the hot section of the engine. To facilitate a significant increase in engine efficiency, tough structural ceramics have been developed that can handle the thermo-mechanical stresses that gas turbine components experience. Unfortunately, the high-temperature, high-pressure, and high-velocity combustion gases in a gas turbine contain water vapor and/or hydrogen which have been shown to volatilize the protective silica layer on silicon-based ceramics. This degradation leads to significant surface recession in ceramic gas turbine components. In order to maintain their structural integrity, an environmental barrier coating (EBC) could be used to protect ceramics from the harsh gas turbine environment. Due to its coefficient of thermal expansion and phase stability at elevated temperatures, tantalum oxide (Ta2O5) was examined as the base material for an air plasma-sprayed EBC on Si3N 4 ceramics. As-sprayed pure Ta2O5 was comprised of both low-temperature beta-Ta2O5 and high-temperature alpha-Ta 2O5 that was quenched into the structure. Residual stress measurements via X-ray diffraction determined the as-sprayed coating to be in tension and extensive vertical macrocracks were observed in the coating. Heat treatments of the pure coating led to conversion of alpha-Ta2 O5 to beta-Ta2O5, conversion of tensile stresses to compressive, localized buckling of the coating, and significant grain growth which caused microcracking in the coating. The pure coating was found to be an inadequate EBC. Al2O3 was investigated as a solid solution alloying addition designed to enhance the stability of beta-Ta2O 5, and reduce grain growth by slowing grain boundary diffusion. La 2O3 was investigated as an alloying addition designed to form second phase particles which would reduce grain growth through pinning. Al2O3 was successful at both stabilizing beta-Ta 2O5 and reducing grain

  12. 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

  13. Thermal spray of ceramics driven by converging shock waves; Entojo shusoku shogekiha wo riyoshita seramikkusu ryushi no yosha

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Kazuhito; Matsuo, Hideo; Hiroe, Tetsuyuki [Kumamoto University, Kumamoto (Japan). Department of Mechanical Engineering and Materials Science; Tomikawa, Hisao [Wakayama National College of Technology, Wakayama (Japan); Fukuoka, Hiromasa [Kumamoto University, Kumamoto (Japan). Graduate School of Science and Technology

    1999-08-31

    A tough wear-resistant surface of metal is produced by thermal spraying ceramic particles on the metal surface. The harder surface is formed by impulsive spraying in which energetic gases explode. The mass of applied ceramics depends on the driving gas energy and is restricted to small amount. In this study, high temperature and high pressure gases generated by converging shock waves are utilized as driver gases of thermal spray to break the restriction. The converging shock wave is generated by a simultaneous explosion of a cylindrical explosive shell and has been applied to a hypervelocity accelerator. As the shock is focusing to the center, the energy density just behind the shock front is increasing. After the reflection of the shock a high energy condition is generated around the focusing center. The generated gas flow has high enthalpy and transfers large amount of kinetic energy into ceramic particles. The thermal spray system composed of a cylindrical shock generator, an accelerating tube, a nozzle and a vacuum chamber was constructed, and ceramics were sprayed onto iron plate. The performance of spray was examined under several conditions and the coated surfaces were observed. The ceramic coatings had sufficient strength in the case that the ceramic particles were sets in the cylindrical shock generator, but the ceramic coatings were not formed in the case in accelerating tube. It is found that the ceramics were required to be molten by heat exchange with high temperature gas. (author)

  14. Industrial applications of thermal sprayed coatings in Venezuelan steelmaking industry

    International Nuclear Information System (INIS)

    Liscano, S; Gil, L; Nuñez, E; Zerpa, R

    2013-01-01

    The metal components subjected to high temperature conditions, abrasive wear, corrosion, impact, etc.; tend to present degradation of manufacturing material, causing the failure imminent of the component. One of the alternatives to minimize or eliminate such effect is the application of ceramic coatings, which are thermal insulators and exhibit high mechanical strength. Its extreme hardness, coupled with the low friction properties and chemical stability, allowing its use in a wide variety of applications. Therefore, the following paper describes the application of thermal sprayed coatings obtained by HVOF and Plasma technologies like alternative to protect the metallic equipment in different venezuelan industrial sectors, such as to operate under aggressive conditions of service, such as the steelmaking nationals industries. This study presents applications cases of ceramic-based coatings, in order to minimize the sticking of metallic material in components of reduction reactor of FINMET® and MIDREXTM process

  15. Effect of Impact Angle on Ceramic Deposition Behavior in Composite Cold Spray: A Finite-Element Study

    Science.gov (United States)

    Chakrabarty, Rohan; Song, Jun

    2017-10-01

    During the cold spraying of particle-reinforced metal matrix composite coatings (ceramic and metal particles mixture) on metal substrates, ceramic particles may either get embedded in the substrate/deposited coating or may rebound from the substrate surface. In this study, the dependence of the ceramic rebounding phenomenon on the spray angle and its effect on substrate erosion have been analyzed using finite-element analysis. From the numerical simulations, it was found that the ceramic particle density and substrate material strength played the major roles in determining the embedding and ceramic retention behavior. Substrate material erosion also influenced the ceramic retention, and the material loss increased as the impact angles decreased from normal. In general, the results concluded that decreasing the impact angle promoted the retention possibility of ceramics in the substrate. This study provides new theoretical insights into the effect of spray angles on the ceramic retention and suggests a new route toward optimizing the spraying process to increase the ceramic retention in composite coatings cold spray.

  16. Plasma-Sprayed Photocatalytic Zinc Oxide Coatings

    Science.gov (United States)

    Navidpour, A. H.; Kalantari, Y.; Salehi, M.; Salimijazi, H. R.; Amirnasr, M.; Rismanchian, M.; Azarpour Siahkali, M.

    2017-04-01

    Fabrication of semiconductor coatings with photocatalytic action for photodegradation of organic pollutants is highly desirable. In this research, pure zinc oxide, which is well known for its promising photocatalytic activity, was deposited on stainless-steel plates by plasma spraying. The phase composition and microstructure of the deposited films were studied by x-ray diffraction analysis and scanning electron microscopy, respectively. Despite the low-energy conditions of the plasma spraying process, the zinc oxide coatings showed good mechanical integrity on the substrate. Their photocatalytic activity was evaluated using aqueous solution of methylene blue at concentration of 5 mg L-1. The results showed the potential of the plasma spraying technique to deposit zinc oxide coatings with photocatalytic action under ultraviolet illumination. Ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy confirmed that the plasma spraying method could deposit zinc oxide films with higher photoabsorption ability relative to the initial powder.

  17. 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.

  18. Plasma sprayed basalt/chromium oxide coatings

    Czech Academy of Sciences Publication Activity Database

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

    2007-01-01

    Roč. 11, č. 1 (2007), s. 71-82 ISSN 1093-3611 Institutional research plan: CEZ:AV0Z20430508 Keywords : Chromia, basalt * plasma spraying * microstructure * phase analysis Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.268, year: 2007

  19. In-situ formation of multiphase air plasma sprayed barrier coatings for turbine components

    Science.gov (United States)

    Subramanian, Ramesh

    2001-01-01

    A turbine component (10), such as a turbine blade, is provided which is made of a metal alloy (22) and a base, planar-grained thermal barrier layer (28) applied by air plasma spraying on the alloy surface, where a heat resistant ceramic oxide overlay material (32') covers the bottom thermal barrier coating (28), and the overlay material is the reaction product of the precursor ceramic oxide overlay material (32) and the base thermal barrier coating material (28).

  20. Examining properties of arc sprayed nanostructured coatings

    Directory of Open Access Journals (Sweden)

    A. Czupryński

    2016-04-01

    Full Text Available The article presents the results of examining properties of arc sprayed coating obtained with nano-alloy on the iron matrix with a high amount of fine carbide precipitates sprayed on non-alloyed steel plates intended for high temperature operation. Powder metal cored wire EnDOtec DO*390N 1,6 mm diameter, was used to produce, dense, very high abrasion and erosion resistant coatings approx. 1,0 mm thick. Nano-material coatings characterization was done to determine abrasion resistance, erosion resistance, adhesion strength, hardness as well as metallographic examinations. Results have proved high properties of arc sprayed nano-material coatings and have shown promising industrial applications.

  1. Testing of Flame Sprayed Al2O3 Matrix Coatings Containing TiO2

    Directory of Open Access Journals (Sweden)

    Czupryński A.

    2016-09-01

    Full Text Available The paper presents the results of the properties of flame sprayed ceramic coatings using oxide ceramic materials coating of a powdered aluminium oxide (Al2O3 matrix with 3% titanium oxide (TiO2 applied to unalloyed S235JR grade structural steel. A primer consisting of a metallic Ni-Al-Mo based powder has been applied to plates with dimensions of 5×200×300 mm and front surfaces of Ø40×50 mm cylinders. Flame spraying of primer coating was made using a RotoTec 80 torch, and an external coating was made with a CastoDyn DS 8000 torch. Evaluation of the coating properties was conducted using metallographic testing, phase composition research, measurement of microhardness, substrate coating adhesion (acc. to EN 582:1996 standard, erosion wear resistance (acc. to ASTM G76-95 standard, and abrasive wear resistance (acc. to ASTM G65 standard and thermal impact. The testing performed has demonstrated that flame spraying with 97% Al2O3 powder containing 3% TiO2 performed in a range of parameters allows for obtaining high-quality ceramic coatings with thickness up to ca. 500 µm on a steel base. Spray coating possesses a structure consisting mainly of aluminium oxide and a small amount of NiAl10O16 and NiAl32O49 phases. The bonding primer coat sprayed with the Ni-Al-Mo powder to the steel substrate and external coating sprayed with the 97% Al2O3 powder with 3% TiO2 addition demonstrates mechanical bonding characteristics. The coating is characterized by a high adhesion to the base amounting to 6.5 MPa. Average hardness of the external coating is ca. 780 HV. The obtained coatings are characterized by high erosion and abrasive wear resistance and the resistance to effects of cyclic thermal shock.

  2. PRODUCTION OF COMPOSITE CERAMIC MATERIAL FOR THERMAL SPRAYING

    Directory of Open Access Journals (Sweden)

    V. A. Okovity

    2017-01-01

    Full Text Available A composite ceramic material has been developed for thermal spraying that permits to increase wear resistance due to introduction of high-chromium steel and molybdenum in its structure, to obtain optimum porosity in the starting charge material while synthesizing  FeCrMo – MoS2/CaF2/С – TiC compositions,  to improve technological parameters of powders and thereby increase coefficient of powder usage in spraying, to reduce cost of wear-resistant coating technology. The paper presents characteristics and parameters of the developed material and coating which is based on it. Methodology is based on  complex metallographical, X-ray diffraction and electron microscopy investigations of structural elements of composite plasma coatings. Main components of composite particles are solid solutions based on iron, titanium carbides, solid lubricant inclusions in the form of molybdenum disulfide, calcium fluoride, carbon. Presence of such powder particles predetermines obtaining wear-resistant coatings which are rather efficient in case of molecular and mechanical and abrasive wear-out under disadvantageous friction conditions (boundary lubrication or absence of lubrication material, elevated temperature actions.  The contemplated powders are characterized by complex geometric shape and developed surface relief of particles. There has been observed a stable distribution of hard carbide phase in volumes of deposited materials and absence of superficial zone with deficit of TiC inclusions that positively influence on working capacity of the investigated wear-resistant coatings. Plasma coatings which have been deposited with the help of  FeCrMo – MoS2 – TiC powders in accordance with the technology developed by authors have better wear resistance in case of dry friction in a steel 45 (coating wear-out is less by 1.2-fold; scoring load is higher by 1.2-fold than a coating which has been obtained with the help of Ni80Cr20 – 12 % MoS2 – 50

  3. Ceramic protective coating

    International Nuclear Information System (INIS)

    Harbach, F.; Nicoll, A.

    1987-01-01

    The basic material of the above-mentioned layer consists of pure aluminium oxide or essentially aluminium oxide. To improve this protective layer metal oxides from the groups IIA, IIIA, IIIB, VB, VIB, VIIB or VIII of the periodic system are added to its basic material before the said protective coating is applied. In this way a corundum structure is formed in the case of aluminium oxide. Gallium oxide, vanadium oxide, chromium oxide or iron oxide are particularly suited for the correlation of such a corundum structure. The formation of the corundum structure increases the resistance of the protective coating to the corrosive effects of vanadium pentoxide and sodium sulfate. By the addition of a specific quantity of magnesium oxide it is possible not only to stimulate the formation of corundum but also to reduce the increase in grain size in the case of the aluminium oxide. The other metallic oxides are especially favorable to the formation of the corundum structure, so that preferably magnesium oxide is to be added to these metallic oxides in order to reduce the increase in grain size. (author)

  4. 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

    2018-02-01

    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.

  5. 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.

  6. Preparation of high critical temperature YBa2Cu3O7 superconducting coatings by thermal spray

    International Nuclear Information System (INIS)

    Lacombe, Jacques

    1991-01-01

    The objective of this research thesis is the elaboration of YBa 2 Cu 3 O 7 superconducting coatings by thermal spray. These coatings must have a high adherence, a high cohesion, and the best possible electrical characteristics. The author first briefly presents physical-chemical characteristics of this ceramic, and proposes a bibliographical synthesis on thick coatings prepared by thermal spray. In the next parts, he studies and describes conditions of elaboration of poly-granular coatings of YBa 2 Cu 3 O 7 , and their structural and electric characteristics [fr

  7. Study on plasma sprayed boron carbide coating

    Science.gov (United States)

    Zeng, Yi; Lee, Soo W.; Ding, Chuanxian

    2002-03-01

    The microstructure, phase composition, and mechanical properties of boron carbide coatings formed by atmospheric plasma spraying (APS) are studied in the present work. The boron carbide coating with high microhardness and low porosity could be produced by APS. The decomposition of boron carbide powder during the plasma spray process would result in the formation of the BxC phase and an increase of the carbon phase, which is confirmed by transmission electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction results.

  8. 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

  9. 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

  10. Fullerene monolayer formation by spray coating

    Czech Academy of Sciences Publication Activity Database

    Červenka, Jiří; Flipse, C.F.J.

    2010-01-01

    Roč. 21, č. 6 (2010), 065302/1-065302/7 ISSN 0957-4484 Institutional research plan: CEZ:AV0Z10100521 Keywords : monolayer * spray coating * fullerene * atomic force microscopy * scanning tunnelling microscopy * electronic structure * graphite * gold Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.644, year: 2010

  11. 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

  12. 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)

  13. Optimization of laser cladding of cold spray coatings with B4C and Ni powders

    Science.gov (United States)

    Fomin, V. M.; Golyshev, A. A.; Malikov, A. G.; Orishich, A. M.; Filippov, A. A.; Ryashin, N. S.

    2017-12-01

    In the present work, a combined method is considered for the production of a metal-matrix composite coating based on Ni and B4C. The coating is created by consistently applied methods: cold spray and laser cladding. The conditions of obtaining cermet layers are investigated depending on the parameters of laser cladding and cold spray. It is shown that the laser track structure significantly changes in accordance to the size of ceramic particles ranging 3-75 µm and its concentration. It is shown that the most perspective layers for additive manufacturing could be obtain from cold spray coatings with ceramic concentrations more than 50% by weight treated in the heat-conductivity laser mode.

  14. Influence of Bond Coat on HVOF-Sprayed Gradient Cermet Coating on Copper Alloy

    Science.gov (United States)

    Ke, Peng; Cai, Fei; Chen, Wanglin; Wang, Shuoyu; Ni, Zhenhang; Hu, Xiaohong; Li, Mingxi; Zhu, Guanghong; Zhang, Shihong

    2017-06-01

    Coatings are required on mold copper plates to prolong their service life through enhanced hardness, wear resistance, and oxidation resistance. In the present study, NiCr-30 wt.%Cr3C2 ceramic-metallic (cermet) layers were deposited by high velocity oxy-fuel (HVOF) spraying on different designed bond layers, including electroplated Ni, HVOF-sprayed NiCr, and double-decker Ni-NiCr. Annealing was also conducted on the gradient coating (GC) with NiCr bond layer to improve the wear resistance and adhesion strength. Coating microstructure was investigated by scanning electron microscopy and x-ray diffraction analysis. Mechanical properties including microhardness, wear resistance, and adhesion strength of the different coatings were evaluated systematically. The results show that the types of metallic bond layer and annealing process had a significant impact on the mechanical properties of the GCs. The GCs with electroplated Ni bond layer exhibited the highest adhesion strength (about 70 MPa). However, the GC with HVOF-sprayed NiCr bond layer exhibited better wear resistance. The wear resistance and adhesion strength of the coating with NiCr metallic bond layer were enhanced after annealing.

  15. Modifications of optical properties with ceramic coatings

    International Nuclear Information System (INIS)

    Besmann, T.M.; Abdel-Latif, A.I.

    1990-01-01

    Coatings of ceramic materials that exhibited high thermal absorptivities and emissivities were chemical vapor deposited on graphite and refractory metals. In this paper the coatings prepared were SiC and B 4 C, and the substrates used were graphite, molybdenum, titanium, and Nb-1Zr. The coatings are characterized with regard to adherence, optical properties, and response to potential harsh environments

  16. Mechanical and microstructural evaluation of laser assisted cold sprayed bioceramic coatings: potential use for biomedical applications

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2014-02-01

    Full Text Available Coatings of commercial pure titanium (CP)-Ti and HAP bio-ceramic were synthesised on Ti-6Al-4V substrate using laser assisted cold spray (LACS) deposition technique. The LACS system comprised of 4.4 kW Nd:YAG laser system, AT-12000HPHV 5000PSI (35...

  17. Ceramic-coated components for the combustion zone of natural gas engines

    Science.gov (United States)

    Holloman, L.; Levy, A. V.

    1992-03-01

    The use of ceramic coatings on the combustion zone surfaces of large,natural gas-fueled,internal com-bustion engines is discussed. Unique handling and quality control systems are required for plasma spray-ing thin (0.25 mm,0.0010) in.coatings on up to 48.25(cm19)-in.diameter piston crowns and cylinder heads weighing up to(1200 lb).The in-service performance characteristics of two types of natural gas-fu-eled combustion engines powering natural gas compressors that had thin zirconia ceramic coatings ap-plied to their combustion zone surfaces are presented. Their performance was measured in the field be-fore and after coating. It was determined that the durability,power output,fuel consumption,exhaust emissions,and other operating characteristics all improved due to ceramic coating of the flame side sur-faces of cylinder heads,power pistons,and valves.

  18. 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

  19. 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.

  20. Mechanical and Microstructural Behavior of Cold-Sprayed Titanium- and Nickel-Based Coatings

    Science.gov (United States)

    Cavaliere, P.; Silvello, A.

    2015-12-01

    Cold spraying is a coating technology that can deposit materials with unique properties. The coating forms through intensive plastic deformation of particles impacting on a substrate at temperature well below the melting point of the sprayed material. Recently, various studies have been published regarding the microstructural and mechanical evolution of metal-matrix composite coatings produced by cold spraying. Herein, we describe the principal results of the available literature in the field of cold-sprayed composites. It is shown that more research is required to solve various questions in this field, for example, the different deformation modes of the material exhibited for various processing conditions, the reinforcing percentage of different material combinations, and the mechanical properties resulting from these complex systems. In the present study, this issue is approached and described for cold-sprayed Ni- and Ti-based composites. Materials were produced with varying ceramic phase (BN and TiAl3) fraction. The variation of the grain size, adhesion strength, porosity, and hardness of the deposits as a function of the ceramic phase fraction and processing parameters (impacting particle speed) is described. The interaction mechanisms between the cold-sprayed particles and the metal matrix during the coating process are presented and described. The results demonstrate a beneficial effect on grain size and porosity with increasing reinforcing phase percentage, as well as narrow processing parameter ranges to achieve the optimal properties with respect to the pure parent materials.

  1. Finite Element Simulation of Residual Stress Development in Thermally Sprayed Coatings

    Science.gov (United States)

    Elhoriny, Mohamed; Wenzelburger, Martin; Killinger, Andreas; Gadow, Rainer

    2017-04-01

    The coating buildup process of Al2O3/TiO2 ceramic powder deposited on stainless-steel substrate by atmospheric plasma spraying has been simulated by creating thermomechanical finite element models that utilize element death and birth techniques in ANSYS commercial software and self-developed codes. The simulation process starts with side-by-side deposition of coarse subparts of the ceramic layer until the entire coating is created. Simultaneously, the heat flow into the material, thermal deformation, and initial quenching stress are computed. The aim is to be able to predict—for the considered spray powder and substrate material—the development of residual stresses and to assess the risk of coating failure. The model allows the prediction of the heat flow, temperature profile, and residual stress development over time and position in the coating and substrate. The proposed models were successfully run and the results compared with actual residual stresses measured by the hole drilling method.

  2. 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

  3. 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

  4. A sputtered zirconia primer for improved thermal shock resistance of plasma-sprayed ceramic turbine seals

    Science.gov (United States)

    Bill, R. C.; Sovey, J.; Allen, G. P.

    1981-01-01

    It is shown that the application of sputtered Y2O3-stabilized ZrO2 (YSZ) primer in plasma-sprayed YSZ ceramic-coated turbine blades results in an improvement, by a factor of 5-6, in the thermal shock life of specimens with a sprayed, porous, Ni-Cr-Al-Y intermediate layer. Species with and without the primer were found to be able to survive 1000 cycles when the intermediate layer was used, but reduced laminar cracking was observed in the specimen with the primer. It is suggested that the sputtered YZS primer-induced properties are due to (1) more effective wetting and adherence of the plasma-sprayed YZS particles to the primer, and (2) the primer's retardation of impinging, molten plasma sprayed particles solidification rates, which result in a less detrimental residual stress distribution.

  5. Low-Energy Plasma Spray (LEPS) Deposition of Hydroxyapatite/Poly-ɛ-Caprolactone Biocomposite Coatings

    Science.gov (United States)

    Garcia-Alonso, Diana; Parco, Maria; Stokes, Joseph; Looney, Lisa

    2012-01-01

    Thermal spraying is widely employed to deposit hydroxyapatite (HA) and HA-based biocomposites on hip and dental implants. For thick HA coatings (>150 μm), problems are generally associated with the build-up of residual stresses and lack of control of coating crystallinity. HA/polymer composite coatings are especially interesting to improve the pure HA coatings' mechanical properties. For instance, the polymer may help in releasing the residual stresses in the thick HA coatings. In addition, the selection of a bioresorbable polymer may enhance the coatings' biological behavior. However, there are major challenges associated with spraying ceramic and polymeric materials together because of their very different thermal properties. In this study, pure HA and HA/poly-ɛ-caprolactone (PCL) thick coatings were deposited without significant thermal degradation by low-energy plasma spraying (LEPS). PCL has never been processed by thermal spraying, and its processing is a major achievement of this study. The influence of selected process parameters on microstructure, composition, and mechanical properties of HA and HA/PCL coatings was studied using statistical design of experiments (DOE). The HA deposition rate was significantly increased by the addition of PCL. The average porosity of biocomposite coatings was slightly increased, while retaining or even improving in some cases their fracture toughness and microhardness. Surface roughness of biocomposites was enhanced compared with HA pure coatings. Cell culture experiments showed that murine osteoblast-like cells attach and proliferate well on HA/PCL biocomposite deposits.

  6. Bone reaction adjacent to microplasma-sprayed calcium phosphate-coated oral implants subjected to an occlusal load, an experimental study in the dog

    NARCIS (Netherlands)

    Junker, R.; Manders, P.J.D.; Wolke, J.G.C.; Borisov, Y.; Braceras, I.; Jansen, J.A.

    2011-01-01

    BACKGROUND: A new microplasma spraying equipment (MSE) to deposit calcium phosphate (CaP) ceramic coatings onto titanium substrates has been developed. With this system, it is possible to spray fine particles and to apply textured hydroxylapatite coatings onto titanium surfaces. Moreover, due to the

  7. Effect of thermal aging on the erosion resistance of air plasma sprayed zirconia thermal barrier coating

    International Nuclear Information System (INIS)

    Janos, B.Z.; Lugscheider, E.; Remer, P.

    1999-01-01

    To increase the performance, efficiency and reliability of thermal barrier coatings, it is important to understand the influence of the microstructure on the erosion resistance. Therefore, the erosion behavior of air-plasma-sprayed 7 wt% yttria stabilized zirconia (7YSZ) thermal barrier coatings (TBC) at elevated temperatures was investigated. The paper focuses on both the porosity of the coating as well as the thermal pre-treatment of the ceramic. To simulate operating conditions on the ceramic samples, high-temperature erosion experiments at 1093 C were carried out on as-sprayed samples as well as on samples, thermally aged at different temperatures up to 1482 C in air prior to erosion testing. A significant dependence of erosion rate on porosity and thermal pre-treatment was found. Finally, a technique was developed to predict the erosion rates of air-plasma-sprayed 7YSZ TBCs independent of aging conditions or porosity levels. Erosion rates seem to be highly correlated to the micro-hardness of the zirconia TBC. A power-law model was empirically derived to estimate erosion rates of plasma-sprayed 7YSZ ceramic thermal barrier coatings. (orig.)

  8. Influence of the spray velocity on arc-sprayed coating structures

    Science.gov (United States)

    Steffens, H.-D.; Nassenstein, K.

    1999-09-01

    Thermal spray processes such as plasma spraying and HVOF have gained markets due to a steady process of development of materials and equipment. One disadvantage of thermal spray processes is that costs must be competitive compared to techniques such as PTA and electroplating. In order to reduce costs, the more economical spray processes like conventional wire flame spraying, as well as arc spraying, are becoming more popular. There are modern arc spray gun designs on the market that meet the requirements of modern coating properties, for example aviation overhaul applications as well as the processing of cored wires. Nevertheless, the physical basis of arc spraying is well known. The aim of the present investigation is to show how the influence of spray velocity (not particle velocity) affects coating structure with respect to arc spray parameters.

  9. 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.

  10. 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

  11. 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.

  12. Influence of spray parameters on the microstructure and mechanical properties of gas-tunnel plasma sprayed hydroxyapatite coatings

    International Nuclear Information System (INIS)

    Morks, M.F.; Kobayashi, Akira

    2007-01-01

    For biomedical applications, hydroxyapatite (HA) coatings were deposited on 304 stainless steel substrate by using a gas tunnel type plasma spraying process. The influences of spraying distances and plasma arc currents on the microstructure, hardness and adhesion properties of HA coatings were investigated. Microstructure observation by SEM showed that HA coatings sprayed at low plasma power have a porous structure and poor hardness. HA coatings sprayed at high plasma power and short spraying distance are characterized by good adhesion and low porosity with dense structure. Hardness increased for HA coatings sprayed at shorter spraying distance and higher plasma power, mainly due to the formation of dense coatings

  13. Thermal Spraying of Bioactive Polymer Coatings for Orthopaedic Applications

    Science.gov (United States)

    Chebbi, A.; Stokes, J.

    2012-06-01

    Flame sprayed biocompatible polymer coatings, made of biodegradable and non-biodegradable polymers, were investigated as single coatings on titanium and as top coatings on plasma sprayed Hydroxyapatite. Biocompatible polymers can act as drug carriers for localized drug release following implantation. The polymer matrix consisted of a biodegradable polymer, polyhydroxybutyrate 98%/ polyhydroxyvalerate 2% (PHBV) and a non-biodegradable polymer, polymethylmethacrylate (PMMA). Screening tests were performed to determine the suitable range of spraying parameters, followed by a Design of Experiments study to determine the effects of spraying parameters on coating characteristics (thickness, roughness, adhesion, wettability), and to optimize the coating properties accordingly. Coatings characterization showed that optimized flame sprayed biocompatible polymers underwent little chemical degradation, did not produce acidic by-products in vitro, and that cells proliferated well on their surface.

  14. Method for non-destructive evaluation of ceramic coatings

    Science.gov (United States)

    Peterson, Kristen A.; Rosen, Elias P.; Jordan, Eric H.; Shahbazmohamadi, Sina; Vakhtin, Andrei B.

    2016-11-08

    A method for evaluating the condition of a ceramic coating deposited on a substrate comprising illuminating the ceramic coating with light, measuring the intensity of light returned from the ceramic coating as function of depth in the coating and transverse position on the coating, and analyzing the measured light intensities to obtain one or more of intensity of the light returned from the exposed coating surface relative to the intensity of light returned from the coating/substrate interface, intensity of the light returned from the coating/substrate interface relative to the intensity of light returned from the bulk of the ceramic coating, determination of roughness at the exposed surface of the ceramic coating, and determination of roughness of the interface between the ceramic coating and underlying bond coat or substrate.

  15. 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.

  16. Efficient spray-coated colloidal quantum dot solar cells

    KAUST Repository

    Kramer, Illan J.

    2014-11-10

    (Figure Presented). A colloidal quantum dot solar cell is fabricated by spray-coating under ambient conditions. By developing a room-temperature spray-coating technique and implementing a fully automated process with near monolayer control - an approach termed as sprayLD - an electronic defect is eliminated resulting in solar cell performance and statistical distribution superior to prior batch-processed methods along with a hero performance of 8.1%.

  17. Performances and reliability of WC based thermal spray coatings

    International Nuclear Information System (INIS)

    Scrivani, A.; Rosso, M.; Salvarani, L.

    2001-01-01

    Thermal spray processes are used for a lot of traditional and innovative applications and their importance is becoming higher and higher. WC/CoCr based thermal spray coatings represent one of the most important class of coatings that find application in a wide range of industrial sectors. This paper will address a review of current applications and characteristics of this kind of coating. The most important spraying processes, namely HVOF (high velocity oxygen fuel) are examined, the characterization of the coatings from the point of view of corrosion and wear resistance is considered. (author)

  18. The corrosion resistance of HVOF sprayed coatings with intermetallic phases in aggressive environments

    OpenAIRE

    B. Formanek; J. Cizner; B. Szczucka-Lasota; R. Przeliorz

    2006-01-01

    Purpose: The cyclic corrosion behavior of coatings with intermetallic matrix ( FeAl, NiAl and FeAl-TiAl) was investigated in aggressive gases.Design/methodology/approach: The composite coatings strengthened by a fine dispersive Al2O3 and other ceramic phases were thermally sprayed by HVOF method in Jet Kote 2 system. A kinetics test was carried out by periodic method for exposure times of up to 500 hours. Mass changes of the studied coatings during the corrosion test are presented. The surfac...

  19. Effect of Spray Parameters on the Corrosion Behavior of HVOF Sprayed WC-Co-Cr Coatings

    Science.gov (United States)

    Hong, Sheng; Wu, Yuping; Zheng, Yugui; Wang, Bo; Gao, Wenwen; Li, Gaiye; Ying, Guobing; Lin, Jinran

    2014-04-01

    WC-10Co-4Cr cermet coatings were deposited on the substrate of AISI 1045 steel by using high-velocity oxygen-fuel (HVOF) thermal spraying process. The Taguchi method including the signal-to-noise (S/N) ratio and the analysis of variance (ANOVA) was employed to optimize the porosity and, in turn, the corrosion resistance of the coatings. The spray parameters evaluated in this study were spray distance, oxygen flow, and kerosene flow. The results indicated that the important sequence of spray parameters on the porosity of the coatings was spray distance > oxygen flow > kerosene flow, and the spray distance was the only significant factor. The optimum spraying condition was 300 mm for the spray distance, 1900 scfh for the oxygen flow, and 6.0 gph for the kerosene flow. The results showed the significant influence of the microstructure on the corrosion resistance of the coatings. Potentiodynamic polarization and electrochemical impendence spectroscopy (EIS) results showed that the WC-10Co-4Cr cermet coating obtained by the optimum spraying condition with the lowest porosity exhibits the best corrosion resistance and seems to be an alternative to hard chromium coating.

  20. Biocompatible wear-resistant thick ceramic coating

    Directory of Open Access Journals (Sweden)

    Vogt Nicola

    2016-09-01

    Full Text Available Sensitisation to immunologically active elements like chromium, cobalt or nickel and debris particle due to wear are serious problems for patients with metallic implants. We tested the approach of using a hard and thick ceramic coating as a wear-resistant protection of titanium implants, avoiding those sensitisation and foreign body problems. We showed that the process parameters strongly influence the coating porosity and, as a consequence, also its hardness.

  1. Plasma Spraying of Magnetite Coatings for M.W. Applications

    OpenAIRE

    Enikov, R.; Nedkov, I.; Oliver, D.

    1997-01-01

    The possibilities of arc - plasma spray deposition of polycrystalline ferromagnetic coating are investigated. Powder sintered microwave absorbing ferrite materials were deposited by arc-plasma jet on polycrystalline substrates. By varying the distance between plasma torch and substrates and the spray duration, coatings with different thickness and porosity were obtained. The coatings characteristics were studied by optical, SEM and XRD methods. The mechanism of the magnetic structure formatio...

  2. RETRACTED: Chemical densification of plasma sprayed yttria stabilized zirconia (YSZ) coatings for high temperature wear and corrosion resistance

    Science.gov (United States)

    Ye, Yaping; Fehr, Karl Thomas; Faulstich, Martin; Wolf, Gerhard

    2012-12-01

    Plasma-sprayed yttria stabilized zirconia (YSZ) ceramic coatings have been widely used as wear- and corrosion-resistant coatings in high temperature applications and an aggressive environment due to their high hardness, wear resistance, heat and chemical resistance, and low thermal conductivity. The highly porous structure of plasma-sprayed ceramic coatings and their poor adhesion to the substrate usually lead to the coating degradation and failure. In this study, a two-layer system consisting of atmospheric plasma-sprayed 8 wt.% yttria-stabilized zirconia (8YSZ) and Ni-based alloy coatings was post-treated by means of a novel chemical sealing process at moderate temperatures of 600-800 °C. Microstructure characteristics of the YSZ coatings were studied using an electron probe micro-analyzer (EPMA). Results revealed that the ceramic top coat was densified by the precipitated zirconia in the open pores. Therefore, the sealed YSZ coatings exhibit reduced porosity, higher hardness and a better adhesion onto the bond coat. The mechanisms for the sealing process were also proposed.

  3. Coating of ceramic powders by chemical vapor deposition techniques (CVD)

    International Nuclear Information System (INIS)

    Haubner, R.; Lux, B.

    1997-01-01

    New ceramic materials with selected advanced properties can be designed by coating of ceramic powders prior to sintering. By variation of the core and coating material a large number of various powders and ceramic materials can be produced. Powders which react with the binder phase during sintering can be coated with stable materials. Thermal expansion of the ceramic materials can be adjusted by varying the coating thickness (ratio core/layer). Electrical and wear resistant properties can be optimized for electrical contacts. A fluidized bed reactor will be designed which allow the deposition of various coatings on ceramic powders. (author)

  4. 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

  5. Tribological Properties of HVOF-Sprayed TiB2-NiCr Coatings with Agglomerated Feedstocks

    Science.gov (United States)

    Zhao, Zichun; Li, Hui; Yang, Tianlong; Zhu, Hongbin

    2018-04-01

    Boride materials have drawn great attention in surface engineering field, owing to their high hardness and good wear resistance. In our previous work, a plasma-sprayed TiB2-based cermet coating was deposited, but the coating toughness was significantly influenced by the formation of a brittle ternary phase (Ni20Ti3B6) derived from the reaction between TiB2 and metal binder. In order to suppress such a reaction occurred in the high-temperature spraying process, the high-velocity oxygen-fuel spraying technique was applied to prepare the TiB2-NiCr coating. Emphasis was paid on the microstructure, the mechanical properties, and the sliding wearing performance of the coating. The result showed that the HVOF-sprayed coating mainly consisted of hard ceramic particles including TiB2, CrB, and the binder phase. No evidence of Ni20Ti3B6 phase was found in the coating. The mechanical properties of HVOF-sprayed TiB2-NiCr coating were comparable to the conventional Cr3C2-NiCr coating. The frictional coefficient of the TiB2-NiCr coating was lower than the Cr3C2-NiCr coating when sliding against a bearing steel ball.

  6. Tribological Properties of HVOF-Sprayed TiB2-NiCr Coatings with Agglomerated Feedstocks

    Science.gov (United States)

    Zhao, Zichun; Li, Hui; Yang, Tianlong; Zhu, Hongbin

    2018-03-01

    Boride materials have drawn great attention in surface engineering field, owing to their high hardness and good wear resistance. In our previous work, a plasma-sprayed TiB2-based cermet coating was deposited, but the coating toughness was significantly influenced by the formation of a brittle ternary phase (Ni20Ti3B6) derived from the reaction between TiB2 and metal binder. In order to suppress such a reaction occurred in the high-temperature spraying process, the high-velocity oxygen-fuel spraying technique was applied to prepare the TiB2-NiCr coating. Emphasis was paid on the microstructure, the mechanical properties, and the sliding wearing performance of the coating. The result showed that the HVOF-sprayed coating mainly consisted of hard ceramic particles including TiB2, CrB, and the binder phase. No evidence of Ni20Ti3B6 phase was found in the coating. The mechanical properties of HVOF-sprayed TiB2-NiCr coating were comparable to the conventional Cr3C2-NiCr coating. The frictional coefficient of the TiB2-NiCr coating was lower than the Cr3C2-NiCr coating when sliding against a bearing steel ball.

  7. 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.

  8. 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.

  9. 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.

  10. Phase analysis of plasma-sprayed zirconia-yttria coatings

    Science.gov (United States)

    Shankar, N. R.; Berndt, C. C.; Herman, H.

    1983-01-01

    Phase analysis of plasma-sprayed 8 wt pct-yttria-stabilized zirconia (YSZ) thermal barrier coatings and powders was carried out by X-ray diffraction. Step scanning was used for increased peak resolution. Plasma spraying of the YSZ powder into water or onto a steel substrate to form a coating reduced the cubic and monoclinic phases with a simultaneous increase in the tetragonal phase. Heat treatment of the coating at 1150 C for 10 h in an Ar atmosphere increased the amount of cubic and monoclinic phases. The implications of these transformations on coating performance and integrity are discussed.

  11. Development of Cold Spray Coatings for Accident-Tolerant Fuel Cladding in Light Water Reactors

    Science.gov (United States)

    Maier, Benjamin; Yeom, Hwasung; Johnson, Greg; Dabney, Tyler; Walters, Jorie; Romero, Javier; Shah, Hemant; Xu, Peng; Sridharan, Kumar

    2018-02-01

    The cold spray coating process has been developed at the University of Wisconsin-Madison for the deposition of oxidation-resistant coatings on zirconium alloy light water reactor fuel cladding with the goal of improving accident tolerance during loss of coolant scenarios. Coatings of metallic (Cr), alloy (FeCrAl), and ceramic (Ti2AlC) materials were successfully deposited on zirconium alloy flats and cladding tube sections by optimizing the powder size, gas preheat temperature, pressure and composition, and other process parameters. The coatings were dense and exhibited excellent adhesion to the substrate. Evaluation of the samples after high-temperature oxidation tests at temperatures up to 1300°C showed that the cold spray coatings significantly mitigate oxidation kinetics because of the formation of thin passive oxide layers on the surface. The results of the study indicate that the cold spray coating process is a viable near-term option for developing accident-tolerant zirconium alloy fuel cladding.

  12. Surface Roughness Reduction of Additive Manufactured Products by Applying a Functional Coating Using Ultrasonic Spray Coating

    OpenAIRE

    Deferme, Wim; Reddy, Naveen; D'Haen, Jan; Drijkoningen, Jeroen

    2017-01-01

    To reduce the high surface roughness of additive manufactured (AM) products, typically a post-treatment is required. Subtractive post-treatments are often performed by hand and are therefore expensive and time consuming, whereas conventional additive post-treatments, such as pneumatic spray coating, require large quantities of coating material. Ultrasonic spray coating, in contrast, is an additive post-treatment technology capable of applying coatings in an efficient way, resulting in less ma...

  13. 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

  14. 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.

  15. Method and Process Development of Advanced Atmospheric Plasma Spraying for Thermal Barrier Coatings

    Science.gov (United States)

    Mihm, Sebastian; Duda, Thomas; Gruner, Heiko; Thomas, Georg; Dzur, Birger

    2012-06-01

    Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments.

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

    International Nuclear Information System (INIS)

    Fauchais, P; Vardelle, M; Vardelle, A

    2013-01-01

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

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

    Science.gov (United States)

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

    2013-06-01

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

  18. Plasma-sprayed coatings for fusion reactor applications

    International Nuclear Information System (INIS)

    Mullendore, A.W.; Mattox, D.M.; Whitley, J.B.; Sharp, D.J.

    1979-01-01

    A series of plasma-sprayed coatings has been given a preliminary evaluation to assess the potential of this class of materials in fusion reactor applications. TiC, TiB 2 , Be and VBe 12 coatings on copper and stainless steel were tested for coating adherence, ion erosion resistance and susceptability to arc erosion. The coatings, in general, display a good resistance to thermal shock failure. The TiC and TiB 2 coatings exhibit favorable ion erosion characteristics and the resistance of the coatings to arc erosion was, in general, superior to that of stainless steel

  19. Bone reaction adjacent to microplasma-sprayed CaP-coated oral implants subjected to occlusal load, an experimental study in the dog. Part I: short-term results.

    NARCIS (Netherlands)

    Junker, R.; Manders, P.J.D.; Wolke, J.G.C.; Borisov, Y.; Jansen, J.A.

    2010-01-01

    BACKGROUND: A new microplasma spraying equipment (MSE) to deposit calcium phosphate ceramic (CaP) coatings onto titanium substrates has been developed. With this system, it is possible to spray fine particles and to apply textured hydroxylapatite coatings onto titanium surfaces. Moreover, due to the

  20. COMPOSITION AND METHOD FOR COATING A CERAMIC BODY

    Science.gov (United States)

    Blanchard, M.K.

    1958-11-01

    A method is presented for protecting a beryllium carbide-graphite body. The method consists in providing a ceramic coating which must contain at least one basic oxide component, such as CaO, at least one amphoteric oxide component, such as Al/sub 2/O/sub 3/, and at least one acidic oxide component, such as SiO/ sub 2/. Various specific formulations for this ceramic coating are given and the coating is applied by conventional ceramic techniques.

  1. Process optimization of ultrasonic spray coating of polymer films

    DEFF Research Database (Denmark)

    Bose, Sanjukta; Keller, Stephan Sylvest; Boisen, Anja

    2013-01-01

    In this work we have performed a detailed study of the influence of various parameters on spray coating of polymer films. Our aim is to produce polymer films of uniform thickness (500 nm to 1 μm) and low roughness compared to the film thickness. The coatings are characterized with respect...... these two regimes, where we obtain a film of desired quality. Both with increasing nozzle-substrate distance and temperature, the deposition moves from a wet state to a dry regime. Similar results are also achieved for solvents with low boiling points. Finally, we study film formation during spray coating...

  2. Simulation of the coating film appearance for spray application

    OpenAIRE

    Seeler, Fabian; Hager, Christian; Schneider, Matthias; Tiedje, Oliver

    2015-01-01

    The coating film topography depends on the substrate structure, the application parameters and the coating material’s levelling properties. Substrates consisting of several materials with different surface structures and differently inclined areas make a homogenous coating film structure difficult. By means of simulations, the paint film structure is intended to be controlled so that the theoretical optimum is reached and the experimental effort can be reduced. The focus is on spray applicati...

  3. Advanced Nanoscale Coatings with Plasma Spray

    National Research Council Canada - National Science Library

    Atteridge, David

    2000-01-01

    .... A secondary research charter developed as this program proceeded was the assessment of the feasibility of using cored wire filled with WE-Co powder as a feed-stock for both plasma spray and twin-wire-arc spray (TWAS...

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

    Science.gov (United States)

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

    2016-12-01

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

  5. Microstructure and fatigue behavior of cold spray coated Al5052

    International Nuclear Information System (INIS)

    Ghelichi, R.; MacDonald, D.; Bagherifard, S.; Jahed, H.; Guagliano, M.; Jodoin, B.

    2012-01-01

    The effect of cold spray coating in inducing residual stresses in the substrate and its effect on delaying crack initiation under cyclic loading have been studied on Al5052 alloy specimens. Different sets of Al5052 specimens have been coated with pure Al and Al7075 feedstock powder, using a low-pressure cold spray coating technique. Some sets of specimens were grit blasted (GB) before coating. The microstructural evolution of the substrate after coating and the fatigue behavior of the coated structure have been studied. In order to obtain the fatigue S–N diagram for each set, as-received and coated specimens with and without preceding GB treatment have been tested in a load-controlled condition. X-ray diffraction has been used to measure the residual stresses both in the deposited materials and the substrates. The results are discussed to highlight the effect of this emerging surface treatment on the characteristics of the treated material. Compressive residual stresses, which led to appreciable increase in the fatigue life, have been observed in all the coated sets. The results indicate that the fatigue strength was significantly improved up to 30% in the case of Al7075 coatings. The results show a strong dependency of the fatigue strength on the deposited material and the spray parameters.

  6. Characterization of wet powder-sprayed zirconia/calcium phosphate coating for dental implants.

    Science.gov (United States)

    Pardun, Karoline; Treccani, Laura; Volkmann, Eike; Li Destri, Giovanni; Marletta, Giovanni; Streckbein, Philipp; Heiss, Christian; Rezwan, Kurosch

    2015-02-01

    Yttria-stabilized zirconia (TZ) is used for dental applications because of its low toxicity and beneficial mechanical properties, but it does not stimulate bone regeneration around the implant due to its bioinertness. Therefore, hydroxyapatite (HA) coatings are often utilized to increase the surface bioactivity and to achieve a better osseointegration. These coatings, however, are chemically nonstable and provide a weak bonding to the substrate surface. In this study, zirconia substrates were coated with a calcium phosphate/zirconia mixture to achieve ceramic coatings with a high bioactivity potential and a good mechanical stability. The coatings were obtained by wet powder spraying (WPS). Pure HA and TZ coatings were employed as reference materials. The coatings were characterized with regard to microstructure, surface roughness, and phase composition. Scratch tests were carried out to investigate the coating adhesion. The influence of the coating on the mechanical strength was evaluated with the ball on three balls test (B3B). In addition, zirconia dental implant screws were also coated and inserted in a biomechanical test block and bovine rip bone. After sintering, the mixed coating exhibited a porous morphology with a surface roughness of about 4 μm and a total porosity of 17%. Phase analysis showed a transformation from TZ and HA to calcium zirconium oxide and tricalcium phosphate. Investigations of the bond strength confirmed a strong adhesion of the mixed coating to the substrate, while the biaxial fracture strength was only slightly affected. Insertion experiments confirmed the scratch test results and evidenced an intact mixed coating on the zirconia screw. The present study revealed a higher stability and firm adhesion of the mixed coating compared with a pure calcium phosphate coating. We also successfully demonstrate the particular versatility of the WPS technique for dental implants by coating a complex curved surface. © 2013 Wiley Periodicals, Inc.

  7. Spray-Deposited Superconductor/Polymer Coatings

    Science.gov (United States)

    Wise, Stephanie A.; Tran, Sang Q.; Hooker, Matthew W.

    1993-01-01

    Coatings that exhibit the Meissner effect formed at relatively low temperature. High-temperature-superconductor/polymer coatings that exhibit Meissner effect deposited onto components in variety of shapes and materials. Simple, readily available equipment needed in coating process, mean coatings produced economically. Coatings used to keep magnetic fields away from electronic circuits in such cryogenic applications as magnetic resonance imaging and detection of infrared, and in magnetic suspensions to provide levitation and/or damping of vibrations.

  8. Development of nondestructive evaluation methods for ceramic coatings

    International Nuclear Information System (INIS)

    Ellingson, W. A.; Deemer, C.; Sun, J. G.; Erdman, S.; Muliere, D.; Wheeler, B.

    2002-01-01

    Various nondestructive evaluation (NDE) technologies are being developed to study the use of ceramic coatings on components in the hot-gas path of advanced low-emission gas-fired turbines. The types of ceramic coatings include thermal barrier coatings (TBCs) and environmental barrier coatings (EBCs). TBCs are under development for vanes, blades, and combustor liners to allow hotter gas-path temperatures, and EBCs are under development to reduce environmental damage to high-temperature components made of ceramic matrix composites. The NDE methods will be used to (a) provide data to assess the reliability of new coating application processes, (b) identify defective components that could cause unscheduled outages, (c) track growth rates of defects during component use in engines, and (d) allow rational judgment for replace/repair/re-use decisions regarding components. Advances in TBC application, both electron beam-physical vapor deposition (EB-PVD) and air plasma spraying (APS), are allowing higher temperatures in the hot-gas path. However, as TBCs become ''prime reliant,'' their condition at scheduled or unscheduled outages must be known. NDE methods are under development to assess the condition of the TBC for pre-spall conditions. EB-PVD test samples with up to 70 thermal cycles have been studied by a newly developed method involving polarized laser back-scatter NDE. Results suggest a correlation between the NDE laser data and the TBC/bond-coat topography. This finding is important because several theories directed toward understanding the pre-spall condition suggest that the topography in the thermally grown oxide layer changes significantly as a function of the number of thermal cycles. Tests have also been conducted with this NDE method on APS TBCs. Results suggest that the pre-spall condition is detected for these coatings. One-sided, high-speed thermal imaging also has shown promise for NDE of APS coatings. Testing of SiC/SiC composites for combustor liners

  9. 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.

  10. Facility for continuous CVD coating of ceramic fibers

    International Nuclear Information System (INIS)

    Moore, A.W.

    1992-01-01

    The development of new and improved ceramic fibers has spurred the development and application of ceramic composites with improved strength, strength/weight ratio, toughness, and durability at increasingly high temperatures. For many systems, the ceramic fibers can be used without modification because their properties are adequate for the chosen application. However, in order to take maximum advantage of the fiber properties, it is often necessary to coat the ceramic fibers with materials of different composition and properties. Examples include (1) boron nitride coatings on a ceramic fiber, such as Nicalon silicon carbide, to prevent reaction with the ceramic matrix during fabrication and to enhance fiber pullout and increase toughness when the ceramic composite is subjected to stress; (2) boron nitride coatings on ceramic yarns, such as Nicalon for use as thermal insulation panels in an aerodynamic environment, to reduce abrasion of the Nicalon and to inhibit the oxidation of free carbon contained within the Nicalon; and (3) ceramic coatings on carbon yarns and carbon-carbon composites to permit use of these high-strength, high-temperature materials in oxidizing environments at very high temperatures. This paper describes a pilot-plant-sized CVD facility for continuous coating of ceramic fibers and some of the results obtained so far with this equipment

  11. Development of spray coated cathodes for RITS-6.

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, Sean; Leckbee, Joshua J.; Miller, Stephen Samuel

    2013-09-01

    This report documents work conducted in FY13 to conduct a feasibility study on thermal spray coated cathodes to be used in the RITS-6 accelerator in an attempt to improve surface uniformity and repeatability. Currently, the cathodes are coated with colloidal silver by means of painting by hand. It is believed that improving the cathode coating process could simplify experimental setup and improve flash x-ray radiographic performance. This report documents the experimental setup and summarizes the results of our feasibility study. Lastly, it describes the path forward and potential challenges that must be overcome in order to improve the process for creating uniform and repeatable silver coatings for cathodes.

  12. Glass-ceramic coating material for the CO2 laser based sintering of thin films as caries and erosion protection.

    Science.gov (United States)

    Bilandžić, Marin Dean; Wollgarten, Susanne; Stollenwerk, Jochen; Poprawe, Reinhart; Esteves-Oliveira, Marcella; Fischer, Horst

    2017-09-01

    The established method of fissure-sealing using polymeric coating materials exhibits limitations on the long-term. Here, we present a novel technique with the potential to protect susceptible teeth against caries and erosion. We hypothesized that a tailored glass-ceramic material could be sprayed onto enamel-like substrates to create superior adhesion properties after sintering by a CO 2 laser beam. A powdered dental glass-ceramic material from the system SiO 2 -Na 2 O-K 2 O-CaO-Al 2 O 3 -MgO was adjusted with individual properties suitable for a spray coating process. The material was characterized using X-ray fluorescence analysis (XRF), heating microscopy, dilatometry, scanning electron microscopy (SEM), grain size analysis, biaxial flexural strength measurements, fourier transform infrared spectroscopy (FTIR), and gas pycnometry. Three different groups of samples (each n=10) where prepared: Group A, powder pressed glass-ceramic coating material; Group B, sintered hydroxyapatite specimens; and Group C, enamel specimens (prepared from bovine teeth). Group B and C where spray coated with glass-ceramic powder. All specimens were heat treated using a CO 2 laser beam process. Cross-sections of the laser-sintered specimens were analyzed using laser scanning microscopy (LSM), energy dispersive X-ray analysis (EDX), and SEM. The developed glass-ceramic material (grain size d50=13.1mm, coefficient of thermal expansion (CTE)=13.310 -6 /K) could be spray coated on all tested substrates (mean thickness=160μm). FTIR analysis confirmed an absorption of the laser energy up to 95%. The powdered glass-ceramic material was successfully densely sintered in all sample groups. The coating interface investigation by SEM and EDX proved atomic diffusion and adhesion of the glass-ceramic material to hydroxyapatite and to dental enamel. A glass-ceramic material with suitable absorption properties was successfully sprayed and laser-sintered in thin films on hydroxyapatite as well as on

  13. 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.

  14. Microstructure and abrasion resistance of plasma sprayed titania coatings

    Science.gov (United States)

    Ctibor, P.; Neufuss, K.; Chraska, P.

    2006-12-01

    Agglomerated titania nanopowder and a “classical” titania were sprayed by the high throughput water-stabilized plasma (WSP) and thoroughly compared. Optical microscopy with image analysis as well as mercury intrusion porosimetry were used for quantification of porosity. Results indicate that the “nano” coatings in general exhibit finer pores than coatings of the “conventional” micron-sized powders. Mechanical properties such as Vickers microhardness and slurry abrasion response were measured and linked to the structural investigation. Impact of the variation in the slurry composition on wear resistance of tested coatings and on character of the wear damage is discussed. The overall results, however, suggest that the “nano” coatings properties are better only for carefully selected sets of spraying parameters, which seem to have a very important impact.

  15. Vacuum-plasma-sprayed silicon coatings for biomedical application

    International Nuclear Information System (INIS)

    Niu Yaran; Liu Xuanyong; Ding Chuanxian

    2008-01-01

    Silicon coating was deposited on titanium alloy substrates by vacuum plasma spraying technology. The morphologies and phase composition of the coatings were analyzed by field-emission scanning electron microscopy and X-ray diffraction. The thermal expansion coefficient of silicon coating was measured to be about 3.70 x 10 -6 K -1 . The bond strength of coating was approximately 20.6 MPa. The density, open porosity, roughness and Young's modulus of silicon coating were also measured. The as-sprayed silicon coating was treated by deionized water at 60 deg. C, 80 deg. C and 100 deg. C for a period of time and soaked in simulated body fluids to evaluate its bioactivity. The results showed that the water-treated coating could induce apatite to precipitate on its surface in simulated body fluid, indicating that the bioactivity of silicon coating was improved. The increase of temperature and duration of water treatment had a positive effect on the bioactivity of silicon coatings

  16. Thermal Shock Resistance of Stabilized Zirconia/Metal Coat on Polymer Matrix Composites by Thermal Spraying Process

    Science.gov (United States)

    Zhu, Ling; Huang, Wenzhi; Cheng, Haifeng; Cao, Xueqiang

    2014-12-01

    Stabilized zirconia/metal coating systems were deposited on the polymer matrix composites by a combined thermal spray process. Effects of the thicknesses of metal layers and ceramic layer on thermal shock resistance of the coating systems were investigated. According to the results of thermal shock lifetime, the coating system consisting of 20 μm Zn and 125 μm 8YSZ exhibited the best thermal shock resistance. Based on microstructure evolution, failure modes and failure mechanism of the coating systems were proposed. The main failure modes were the formation of vertical cracks and delamination in the outlayer of substrate, and the appearance of coating spallation. The residual stress, thermal stress and oxidation of substrate near the substrate/metal layer interface were responsible for coating failure, while the oxidation of substrate near the substrate/coating interface was the dominant one.

  17. Particulate generation in plasma sprayed hydroxyapatite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Gross, K.A.; Ray, N. [Monash Univ., Clayton (Australia). Dept. of Materials Engineering; Roekkum, M. [Oslo Univ. (Norway). Center for Orthopaedics

    2001-07-01

    A hydroxyapatite coated femoral stem, matching a retrieved recovered from a case of third body wear, was analysed to investigate particle release from the hydroxyapatite coating. The stem was sectioned into 12 pieces, mounted in epoxy resin and polished to reveal the microstructure. One section was analysed with X-ray diffraction and Fourier transform infra-red spectroscopy. It was found that the coating contained a large amorphous phase content indicating that the coating has the potential for rapid dissolution. The small crystalline particles in the coating were mainly in the 1-8 micron size range. Exposure to dilute nitric acid showed that the coating is capable of releasing particles into the peri-implant area. (orig.)

  18. Key Durability Issues with Mullite-Based Environmental Barrier Coatings for Si-Based Ceramics

    Science.gov (United States)

    Lee, Kang N.

    2000-01-01

    Plasma-sprayed mullite (3Al2O3.2SiO2) and mullite/yttria-stabilized-zirconia (YSZ) dual layer coatings have been developed to protect silicon -based ceramics from environmental attack. Mullite-based coating systems show excellent durability in air. However, in combustion environments, corrosive species such as molten salt or water vapor penetrate through cracks in the coating and attack the Si-based ceramics along the interface. Thus the modification of the coating system for enhanced crack-resistance is necessary for long-term durability in combustion environments. Other key durability issues include interfacial contamination and coating/substrate bonding. Interfacial contamination leads to enhanced oxidation and interfacial pore formation, while a weak coating/substrate bonding leads to rapid attack of the interface by corrosive species, both of which can cause a premature failure of the coating. Interfacial contamination can be minimized by limiting impurities in coating and substrate materials. The interface may be modified to improve the coating/substrate bond.

  19. Longitudinal impedance calculation of coated ceramic vacuum chamber at HLS

    International Nuclear Information System (INIS)

    Wang Lin; Xu Hongliang; Shang Lei; Wang Xiangqi; Li Weimin

    2003-01-01

    The purpose of this paper is to estimate the longitudinal coupling impedance of the coated ceramic vacuum chamber employed in new injection system of Hefei Light Source. For the regular axially symmetric boundary, the analytical results of the impedance for the coated ceramic chamber can be easily obtained by application field matching techniques to Maxwell equations in cylindrical coordinate system. For the irregular boundary used in HLS, it is very hard to obtain analytical result of impedance. Based on the impedance measurement principle of coaxial wire method, the impedance of ceramic chamber was numerically calculated. The calculated results showed that, although coating inside ceramic chamber can reduce impedance by some factor, the coated ceramic chamber is one of the main impedance sources of HLS storage ring

  20. Optimization of nanocrystalline γ-alumina coating for direct spray ...

    Indian Academy of Sciences (India)

    Hoffman and Leibowitz 1971) and sput- tering (Jin et al 2003). On the other hand, aluminum oxide layer could be useful for coating the spray water-cooled optical and electrical devices, due to its interesting proper- ties such as optical transparency, ...

  1. Optimization of nanocrystalline γ-alumina coating for direct spray ...

    Indian Academy of Sciences (India)

    7, December 2014, pp. 1583–1588. c Indian Academy of Sciences. Optimization of nanocrystalline γ-alumina coating for direct spray water-cooling of optical devices. S N ALAM1,2,∗. , M ANARAKY3, Z SHAFEIZADEH3 and P J PARBROOK1. 1Tyndall National Institute, University College Cork, Lee Maltings, Dyke Parade, ...

  2. Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Halbig, Michael Charles; Puleo, Bernadette J.; Costa, Gustavo; Mccue, Terry R.

    2017-01-01

    This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiC-SiC Ceramic Matrix Composite (CMC) combustors particularly under the NASA Environmentally Responsible Aviation, Fundamental Aeronautics and Transformative Aeronautics Concepts Programs. The emphases have been placed on the current design challenges of the 2700-3000F capable environmental barrier coatings for low NOX emission combustors for next generation turbine engines by using advanced plasma spray based processes, and the coating processing and integration with SiC-SiC CMCs and component systems. The developments also have included candidate coating composition system designs, degradation mechanisms, performance evaluation and down-selects; the processing optimizations using TriplexPro Air Plasma Spray Low Pressure Plasma Spray (LPPS), Plasma Spray Physical Vapor Deposition and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements under the NASA development programs, as demonstrated in the simulated engine high heat flux, combustion environments, in conjunction with high heat flux, mechanical creep and fatigue loading testing conditions.

  3. Mo-Si-B-Based Coatings for Ceramic Base Substrates

    Science.gov (United States)

    Perepezko, John Harry (Inventor); Sakidja, Ridwan (Inventor); Ritt, Patrick (Inventor)

    2015-01-01

    Alumina-containing coatings based on molybdenum (Mo), silicon (Si), and boron (B) ("MoSiB coatings") that form protective, oxidation-resistant scales on ceramic substrate at high temperatures are provided. The protective scales comprise an aluminoborosilicate glass, and may additionally contain molybdenum. Two-stage deposition methods for forming the coatings are also provided.

  4. 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

  5. Workplace exposure and release of ultrafine particles during atmospheric plasma spraying in the ceramic industry.

    Science.gov (United States)

    Viana, M; Fonseca, A S; Querol, X; López-Lilao, A; Carpio, P; Salmatonidis, A; Monfort, E

    2017-12-01

    Atmospheric plasma spraying (APS) is a frequently used technique to produce enhanced-property coatings for different materials in the ceramic industry. This work aimed to characterise and quantify the impact of APS on workplace exposure to airborne particles, with a focus on ultrafine particles (UFPs, nanoparticles (Particle number, mass concentrations, alveolar lung deposited surface area concentration, and size distributions, in the range 10nm-20μm were simultaneously monitored at the emission source, in the potential worker breathing zone, and in outdoor air. Different input materials (known as feedstock) were tested: (a) micron-sized powders, and (b) suspensions containing submicron- or nano-sized particles. Results evidenced significantly high UFP concentrations (up to 3.3×10 6 /cm 3 ) inside the spraying chamber, which impacted exposure concentrations in the worker area outside the spraying chamber (up to 8.3×10 5 /cm 3 ). Environmental release of UFPs was also detected (3.9×10 5 /cm 3 , outside the exhaust tube). Engineered nanoparticle (ENP) release to workplace air was also evidenced by TEM microscopy. UFP emissions were detected during the application of both micron-sized powder and suspensions containing submicron- or nano-sized particles, thus suggesting that emissions were process- (and not material-) dependent. An effective risk prevention protocol was implemented, which resulted in a reduction of UFP exposure in the worker area. These findings demonstrate the potential risk of occupational exposure to UFPs during atmospheric plasma spraying, and raise the need for further research on UFP formation mechanisms in high-energy industrial processes. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Mechanical characterization of copper coatings realized by thermal spraying

    International Nuclear Information System (INIS)

    Gassot, H.; Junquera, T.; Legoff, A.; Lescornet, J.C.; Ji, V.; Grandsire, L.

    2000-11-01

    The stiffening of superconducting cavities is required to assure mechanical stability. The stiffening method used for the tesla test facility (TTF) is non-sufficient for the Tesla project (TeV energy superconducting linear accelerator). A new method has been developed, this method is based on the thermal spraying of a copper coating on the backside of a niobium cavity, simulations show a promising future for this technique. This report presents the structure, the behaviour and the characteristics of a copper coating realized by thermal spraying. The elastic properties of the coating plays an important role for the stiffening of the cavity. A stress analysis has been achieved on samples by using X-ray diffraction, this technique is the only one that takes into account anisotropy effects. From the results of tensile tests it appears that copper coatings are very fragile and far less ductile than massive metal, it is mainly due to the strong oxidation rate of the coating (about 12%). The hardness of a coating is 20% higher than of massive copper. Other tensile tests have been performed to evaluate the adherence of the coating to the niobium, an adherence force of 50 MPa has been deduced from testing. (A.C.)

  7. Structural characterization of an electrically insulating diffusion barrier on a plasma-sprayed ceramic for severe environment applications

    International Nuclear Information System (INIS)

    Joly, Alexandre; Brun, Patrice; Lacombe, Jacques; Tricot, Gregory; Denoirjean, Alain

    2013-01-01

    We investigate in this paper the physical properties and the structure of a protective barrier based on a thermal-sprayed alumina coating. This coating is known to form an electrically insulating barrier that efficiently protects stainless steel structures of melting furnaces subjected to high differences of voltage. Sealing the open and/or interconnected porosity of the alumina coating with aluminum phosphate is also known to improve the protection by mitigating leakage in the ceramic. The sealing procedure has been achieved by (i) impregnating the plasma-sprayed alumina coating with a mono aluminum phosphate (MAlP) solution and (ii) applying a thermal treatment to the system. A waterproof diffusion barrier presenting a good electric insulation is finally obtained and the protective performances were tested on specimens to assess their behavior under aggressive conditions. The formation procedure is characterized by parameters related to the solution and is dependent on the heating rate, the process temperature, and the isothermal duration of the thermal treatment. We show in this paper how these different parameters impact (i) the coating physical properties (thermal and electrical tests) and (ii) the coating structure that has been probed with 31 P solid state nuclear magnetic resonance (NMR). (authors)

  8. Hardness and electrochemical behavior of ceramic coatings on Inconel

    Directory of Open Access Journals (Sweden)

    C. SUJAYA

    2012-03-01

    Full Text Available Thin films of ceramic materials like alumina and silicon carbide are deposited on Inconel substrate by pulsed laser deposition technique using Q-switched Nd: YAG laser. Deposited films are characterized using UV-visible spectrophotometry and X-ray diffraction. Composite microhardness of ceramic coated Inconel system is measured using Knoop indenter and its film hardness is separated using a mathematical model based on area-law of mixture. It is then compared with values obtained using nanoindentation method. Film hardness of the ceramic coating is found to be high compared to the substrates. Corrosion behavior of substrates after ceramic coating is studied in 3.5% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The Nyquist and the Bode plots obtained from the EIS data are fitted by appropriate equivalent circuits. The pore resistance, the charge transfer resistance, the coating capacitance and the double layer capacitance of the coatings are obtained from the equivalent circuit. Experimental results show an increase in corrosion resistance of Inconel after ceramic coating. Alumina coated Inconel showed higher corrosion resistance than silicon carbide coated Inconel. After the corrosion testing, the surface topography of the uncoated and the coated systems are examined by scanning electron microscopy.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Electrophoretic deposition of sol-gel-derived ceramic coatings

    International Nuclear Information System (INIS)

    Zhang, Y.; Crooks, R.M.

    1992-01-01

    In this paper the physical, optical, and chemical characteristics of electrophoretically and dip-coated sol-gel ceramic films are compared. The results indicate that electrophoresis may allow a higher level of control over the chemistry and structure of ceramic coatings than dip-coating techniques. For example, controlled-thickness sol-gel coatings can be prepared by adjusting the deposition time or voltage. Additionally, electrophoretic coatings can be prepared in a four-component alumino-borosilicate sol display interesting optical characteristics. For example, the ellipsometrically-measured refractive indices of electrophoretic coatings are higher than the refractive indices of dip-coated films cast from identical sols, and they are also higher than any of the individual sol components. This result suggests that there are physical and/or chemical differences between films prepared by dip-coating and electrophoresis

  14. An electrothermal chemical technology for thermal spray coatings

    International Nuclear Information System (INIS)

    Wald, S.; Appelbaum, G.; Alimi, R.; Rabani, L.; Zoler, D.; Zhitomirsky, V.; Factor, M.; Roman, I.

    1998-01-01

    A new spray technology for producing hard-coatings, has been developed at the SOREQ Nuclear Research Center. The concept is based on the extensive experience accumulated at SOREQ in the course of the development of Electrothermal (ET), Electrothermal-Chemical (ETC) and Solid-Propellant Electrothermal-Chemical (SPETC) guns(r). High quality coatings may be obtained by thermal spraying powder particles onto a variety of substrates. Mature state-of-the-art technologies such as plasma spray, high velocity oxy fuel (HVOF) and detonation gun (D-Gun) are widely used for many applications. As each method has its own drawbacks there is a need for a combination of several parameters which cannot be achieved by any existing individual commercial technology. The method presented is oriented toward a high-quality, multi-step, high-throughput, easily programmable continuous coating process and relatively inexpensive technology. The combustion products of a solid or liquid propellant accelerate the powder particles of the coating material. A pulsed-plasma jet, provided by a confined capillary discharge, ignites the propellant and controls the combustion process. The powder particles are accelerated to velocities over 1000 m/s. Due to the very high carrier gas density, high velocity, high throughput and high powder consumption efficiency are obtained. The plasma jet enables control of the gas temperature and consequently influences the powder temperature

  15. Thermal spray coating for corrosion under insulation (CUI) prevention

    Science.gov (United States)

    Fuad, Mohd Fazril Irfan Ahmad; Razak, Khalil Abdul; Alias, Nur Hashimah; Othman, Nur Hidayati; Lah, Nik Khairul Irfan Nik Ab

    2017-12-01

    Corrosion under insulation (CUI) is one of the predominant issues affecting process of Oil and Gas and Petrochemical industries. CUI refers to external corrosion, but it is difficult to be detected as the insulation cover masks the corrosion problem. One of the options to prevent CUI is by utilizing the protective coating systems. Thermal spray coating (TSC) is an advanced coating system and it shows promising performance in harsh environment, which could be used to prevent CUI. However, the application of TSC is not attractive due to the high initial cost. This work evaluates the potential of TSC based on corrosion performance using linear polarization resistance (LPR) method and salt spray test (SST). Prior to the evaluation, the mechanical performance of TSC was first investigated using adhesion test and bend test. Microstructure characterization of the coating was investigated using Scanning Electron Microscope (SEM). The LPR test results showed that low corrosion rate of 0.05 mm/years was obtained for TSC in compared to the bare steel especially at high temperature of 80 °C, where usually normal coating would fail. For the salt spray test, there was no sign of corrosion products especially at the center (fully coated region) was observed. From SEM images, no corrosion defects were observed after 336 hours of continuous exposure to salt fog test. This indicates that TSC protected the steel satisfactorily by acting as a barrier from a corrosive environment. In conclusion, TSC can be a possible solution to minimize the CUI in a long term. Further research should be done on corrosion performance and life cycle cost by comparing TSC with other conventional coating technology.

  16. Corrosion Resistance of Copper Coatings Deposited by Cold Spraying

    Science.gov (United States)

    Winnicki, M.; Baszczuk, A.; Jasiorski, M.; Małachowska, A.

    2017-12-01

    In the article, a study of corrosion resistance of copper and copper-based cermet (Cu+Al2O3 and Cu+SiC) coatings deposited onto aluminum alloy substrate using the low-pressure cold spraying method is presented. The samples were subjected to two different corrosion tests at room temperature: (1) Kesternich test and (2) a cyclic salt spray test. The selected tests were allowed to simulate service conditions typical for urban, industrial and marine environment. Examination of corroded samples included analysis changes on the coating surface and in the microstructure. The physicochemical tests were carried out using x-ray diffraction to define corrosion products. Moreover, microhardness and electrical conductivity measurements were conducted to estimate mechanical and physical properties of the coatings after corrosion tests. XRD analysis clearly showed that regardless of corrosion conditions, for all samples cuprite (Cu2O) was the main product. However, in the case of Cu+Al2O3 cermet coating, chlorine- and sulfate-containing phases such as Cu2Cl(OH)3 (paracetamite) and Cu3(SO4)(OH)4 (antlerite) were also recorded. This observation gives better understanding of the lowest microstructure changes observed for Cu+Al2O3 coating after the corrosion tests. This is also a justification for the lowest decrease in electrical conductivity registered after the corrosion tests for this coating.

  17. 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.

  18. Study on the neotype zirconia's implant coated nanometer hydroxyapatite ceramics

    Science.gov (United States)

    Zhu, J. W.; Yang, D. W.

    2007-07-01

    In recent years, biologic ceramics is a popular material of implants and bioactive surface modification of dental implant became a research emphasis, which aims to improve bioactivity of implants materials and acquire firmer implants-bone interface. The zirconia ceramic has excellent mechanical properties and nanometer HA ceramics is a bioceramic well known for its bioactivity, therefore, nanometer HA ceramics coating on zirconia, allows combining the excellent mechanical properties of zirconia substrates with its bioactivity. This paper shows a new method for implant shape design and bioactive modification of dental implants surface. Zirconia's implant substrate was prepared by sintered method, central and lateral tunnels were drilled in the zirconia hollow porous cylindrical implants by laser processing. The HA powders and needle-like HA crystals were made by a wet precipitation and calcining method. Its surface was coated with nanometer HA ceramics which was used brush HA slurry and vacuum sintering. Mechanical testing results revealed that the attachment strength of nanometer HA ceramics coated zirconia samples is high. SEM and interface observation after inserted experiment indicated that calcium and phosphor content increased and symmetrically around coated implant-bone tissue interface. A significantly higher affinity index was demonstrated in vivo by histomorphometric evaluation in coated versus uncoated implants. SEM analysis demonstrated better bone adhesion to the material in coated implant at any situation. In addition, the hollow porous cylindrical implant coated with nanometer HA ceramics increase the interaction of bone and implant, the new bone induced into the surface of hollow porous cylindrical implant and through the most tunnels filled into central hole. The branch-like structure makes the implant and bone a body, which increased the contact area and decreased elastic ratio. Therefore, the macroscopical and microcosmic nested structure of

  19. 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.

  20. 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)

  1. Sintering of Fine Particles in Suspension Plasma Sprayed Coatings.

    Science.gov (United States)

    Latka, Leszek; Goryachev, Sergey B; Kozerski, Stefan; Pawlowski, Lech

    2010-07-01

    Suspension plasma spraying is a process that enables the production of finely grained nanometric or submicrometric coatings. The suspensions are formulated with the use of fine powder particles in water or alcohol with some additives. Subsequently, the suspension is injected into plasma jet and the liquid additives evaporate. The remaining fine solids are molten and subsequently agglomerate or remain solid, depending on their trajectory in the plasma jet. The coating's microstructure results from these two groups of particles arriving on a substrate or previously deposited coating. Previous experimental studies carried out for plasma sprayed titanium oxide and hydroxyapatite coatings enabled us to observe either a finely grained microstructure or, when a different suspension injection mode was used, to distinguish two zones in the microstructure. These two zones correspond to the dense zone formed from well molten particles, and the agglomerated zone formed from fine solid particles that arrive on the substrate in a solid state. The present paper focuses on the experimental and theoretical analysis of the formation process of the agglomerated zone. The experimental section establishes the heat flux supplied to the coating during deposition. In order to achieve this, calorimetric measurements were made by applying experimental conditions simulating the real coatings' growth. The heat flux was measured to be in the range from 0.08 to 0.5 MW/m²,depending on the experimental conditions. The theoretical section analyzes the sintering during the coating's growth, which concerns the fine particles arriving on the substrate in the solid state. The models of volume, grain boundary and surface diffusion were analyzed and adapted to the size and chemistry of the grains, temperature and time scales corresponding to the suspension plasma spraying conditions. The model of surface diffusion was found to best describe the sintering during suspension plasma spraying. The formation

  2. Mikrostruktur dan Karakterisasi Sifat Mekanik Lapisan Cr3C2-NiAl-Al2O3 Hasil Deposisi Dengan Menggunakan High Velocity Oxygen Fuel Thermal Spray Coating

    Directory of Open Access Journals (Sweden)

    Edy Riyanto

    2012-03-01

    Full Text Available Surface coating processing of industrial component with thermal spray coatings have been applied in many industrial fields. Ceramic matrix composite coating which consists of Cr3C2-Al2O3-NiAl had been carried out to obtain layers of material that has superior mechanical properties to enhance component performance. Deposition of CMC with High Velocity Oxygen Fuel (HVOF thermal spray coating has been employed. This study aims to determine the effect of powder particle size on the microstructure, surface roughness and hardness of the layer, by varying the NiAl powder particle size. Test results show NiAl powder particle size has an influence on the mechanical properties of CMC coating. Hardness of coating increases and surface roughness values of coating decrease with smaller NiAl particle size.  

  3. The erosion performance of particle reinforced metal matrix composite coatings produced by co-deposition cold gas dynamic spraying

    Science.gov (United States)

    Peat, Tom; Galloway, Alexander; Toumpis, Athanasios; McNutt, Philip; Iqbal, Naveed

    2017-02-01

    This work reports on the erosion performance of three particle reinforced metal matrix composite coatings, co-deposited with an aluminium binder via cold-gas dynamic spraying. The deposition of ceramic particles is difficult to achieve with typical cold spray techniques due to the absence of particle deformation. This issue has been overcome in the present study by simultaneously spraying the reinforcing particles with a ductile metallic binder which has led to an increased level of ceramic/cermet particles deposited on the substrate with thick (>400 μm) coatings produced. The aim of this investigation was to evaluate the erosion performance of the co-deposited coatings within a slurry environment. The study also incorporated standard metallographic characterisation techniques to evaluate the distribution of reinforcing particles within the aluminium matrix. All coatings exhibited poorer erosion performance than the uncoated material, both in terms of volume loss and mass loss. The Al2O3 reinforced coating sustained the greatest amount of damage following exposure to the slurry and recorded the greatest volume loss (approx. 2.8 mm3) out of all of the examined coatings. Despite the poor erosion performance, the WC-CoCr reinforced coating demonstrated a considerable hardness increase over the as-received AA5083 (approx. 400%) and also exhibited the smallest free space length between adjacent particles. The findings of this study reveal that the removal of the AA5083 matrix by the impinging silicon carbide particles acts as the primary wear mechanism leading to the degradation of the coating. Analysis of the wear scar has demonstrated that the damage to the soft matrix alloy takes the form of ploughing and scoring which subsequently exposes carbide/oxide particles to the impinging slurry.

  4. Sintering of Fine Particles in Suspension Plasma Sprayed Coatings

    OpenAIRE

    Latka, Leszek; Goryachev, Sergey B.; Kozerski, Stefan; Pawlowski, Lech

    2010-01-01

    Suspension plasma spraying is a process that enables the production of finely grained nanometric or submicrometric coatings. The suspensions are formulated with the use of fine powder particles in water or alcohol with some additives. Subsequently, the suspension is injected into plasma jet and the liquid additives evaporate. The remaining fine solids are molten and subsequently agglomerate or remain solid, depending on their trajectory in the plasma jet. The coating’s microstructure results ...

  5. Thermal Spray Coatings for Fusion Applications — Review

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Chráska, Pavel; Linke, J.

    2007-01-01

    Roč. 16, č. 1 (2007), s. 64-83 ISSN 1059-9630 Grant - others:-(XE) EFDA Task DV4/04 (TW0; -(XE) EFDA Task TW5-TVM-PSW Institutional research plan: CEZ:AV0Z20430508 Keywords : beryllium * boron carbide * plasma facing components * plasma sprayed coatings * thermonuclear fusion * tungsten Subject RIV: JG - Metallurgy Impact factor: 1.204, year: 2007

  6. An integrated study of thermal spray process-structure-property correlations: A case study for plasma sprayed molybdenum coatings

    International Nuclear Information System (INIS)

    Vaidya, A.; Streibl, T.; Li, L.; Sampath, S.; Kovarik, O.; Greenlaw, R.

    2005-01-01

    Thermal spray coatings exhibit a wide variety of hierarchial and multiscale microstructural characteristics that lead to variation in their functional properties and performance. The array of defect structures, orthotropic behaviour and process-induced attributes (e.g. quenching stresses) all add to complexity in understanding and predicting their performance. A complete understanding of the plasma spray process includes examination of the particle-jet interaction, particle impact (to form the splats) and the particle-substrate interaction during coating deposition. This link has been established by using diagnostic tools in conjunction with a splat collection shutter and an 'in situ' curvature measurement instrument. In this study, commercial grade spherical molybdenum (Mo) powder was plasma sprayed and the spray stream was characterized for resulting particle state. A 'splat map' was deposited through a 'spray stream guillotine' to capture the fingerprint of the plume cross-section. Subsequently, coatings were deposited at these spray conditions on a newly developed 'in situ' curvature measurement instrument to measure coating residual stresses and to estimate the coating modulus. Splats and coatings were subsequently characterized by microdiffraction (for splat residual stresses), nano and microindentation for elastic and elastic-plastic properties and by electron microscopy. This complete history of the process followed by splat and coating characterization provides insight into the correlation between processing parameters, resultant particle states and final coating properties. The role of particle temperature and velocity on the splat (and coating) morphology and residual stress is explained in the results

  7. Effect of High Velocity Arc Spraying Parameters on Properties of FeNiCrAl Coating

    Directory of Open Access Journals (Sweden)

    TIAN Haoliang

    2016-12-01

    Full Text Available FeNiCrAl coating is a kind of surface wear resistant material for shaft parts. Microstructure, adhesive strength, phase composition and microhardness were analyzed in order to study the influence mechanism of spraying parameters on coating properties. The relation among the spraying current, coating microstructure and cohesive strength was studied in detail. The results shown that the spraying current is very important to obtain the dense coating (porosity of 8.76% with cohesive strength of 52.3 MPa and an excellent coating is prepared by spraying current 200 A, spraying voltage 34 V and spraying distance 160 mm. The hardness of coating is 626 HV0.1 and about 1.6 times as that of the matrix. The effective mechanism is relevant to the scatter distribution of the Fe-Al intermetallic compound and Cr0.19Fe0.1Ni0.11 solution in the coating.

  8. Process Optimization for Spray Coating of Poly (vinyl pyrrolidone)

    DEFF Research Database (Denmark)

    Bose, Sanjukta; Keller, Stephan Sylvest; Boisen, Anja

    . Here, we present a study of the parameters determining the quality of the deposited film. Spray Coating was done in an Exacta Coat Ultrasonic Spraying System (Sonotek, USA) .The main components are illustrated in fig. 1. The tip of the ultrasonic atomizer nozzle was actuated at a frequency of 120 k...... was controlled by an x-y-z stage. A shadow mask was put on a glass slide before deposition to cover some area from spraying. The masked areas acted as a baseline for characterizing the final coating by a surface profilometer (Veeco Dektak8) from where the thickness and roughness value were calculated as shown.......e., at the wet state, Ra reduces to 22nm. The disadvantage of the wet condition is that as the polymer remains wet for a longer time it accumulates at the edge of the deposition to form peaks of few microns in height (fig.3b). The optimized condition (fig.3c) lies in between at a distance of 90mm where we get...

  9. Systems and methods for coating conduit interior surfaces utilizing a thermal spray gun with extension arm

    Science.gov (United States)

    Moore, Karen A.; Zatorski, Raymond A.

    2005-07-12

    Systems and methods for applying a coating to an interior surface of a conduit. In one embodiment, a spray gun configured to apply a coating is attached to an extension arm which may be inserted into the bore of a pipe. The spray gun may be a thermal spray gun adapted to apply a powder coating. An evacuation system may be used to provide a volume area of reduced air pressure for drawing overspray out of the pipe interior during coating. The extension arm as well as the spray gun may be cooled to maintain a consistent temperature in the system, allowing for more consistent coating.

  10. 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.

  11. Glass and glass–ceramic coatings, versatile materials for industrial ...

    Indian Academy of Sciences (India)

    Unknown

    due to sliding effect with another contacting surface or due to chemical attack .... which prevents fish scale and copper head formation and promotes .... Properties of corrosion resistant glass–ceramic coating. Properties. Results. Acid resistance (2 h boiling in 1% sulphuric acid). 5 mg⋅dm–2. Coat thickness. 0⋅15–0⋅2 mm.

  12. Structure Analysis Of Corrosion Resistant Thermal Sprayed Coatings On Low Alloy Steels

    Science.gov (United States)

    Chaliampalias, D.; Vourlias, G.; Pistofidis, N.; Pavlidou, E.; Stergiou, A.; Stergioudis, G.; Polychroniadis, E. K.

    2007-04-01

    Metallic coatings have been proved to reduce the rate of corrosion of steel in various atmospheres. In this work the structure of Al, Cu-Al and Zn thermal sprayed coatings is examined. The as formed coatings are extremely rough, and they are composed of several phases which increase corrosion resistance as it was determined Salt Spray Chamber tests.

  13. Chemical stability and antimicrobial activity of plasma sprayed bioactive Ca2ZnSi2O7 coating.

    Science.gov (United States)

    Li, Kai; Yu, Jiangming; Xie, Youtao; Huang, Liping; Ye, Xiaojian; Zheng, Xuebin

    2011-12-01

    Calcium silicate ceramic coatings have received considerable attention in recent years due to their excellent bioactivity and bonding strength. However, their high dissolution rates limit their practical applications. In this study, zinc incorporated calcium silicate based ceramic Ca(2)ZnSi(2)O(7) coating was prepared on Ti-6Al-4V substrate via plasma spraying technology aiming to achieve higher chemical stability and additional antibacterial activity. Chemical stability of the coating was assessed by monitoring mass loss and ion release of the coating after immersion in the Tris-HCl buffer solution and examining pH value variation of the solution. Results showed that the chemical stability of zinc incorporated coating was improved significantly. Antimicrobial activity of the Ca(2)ZnSi(2)O(7) coating was evaluated, and it was found that the coating exhibited 93% antibacterial ratio against Staphylococcus aureus. In addition, in vitro bioactivity and cytocompatibility were confirmed for the Ca(2)ZnSi(2)O(7) coating by simulated body fluid test, MC3T3-E1 cells adhesion investigation and cytotoxicity assay.

  14. Spray-coated ligand-free Cu2ZnSnS4 nanoparticle thin films

    DEFF Research Database (Denmark)

    Engberg, Sara Lena Josefin; Murthy, Swathi; Kofod, Guggi

    We have fabricated Cu2ZnSnS4 (CZTS) thin films from spray-coating ligand-free nanoparticle inks. The as-synthesized CZTS nanoparticles were inherently ligand-free [1], which allows the use of polar solvents, such as water and ethanol. Another advantage of these particles is that user...... as an unquantifiable amount of ZnS. A Sono-tek spray-coating system is used which utilizes ultrasonic atomization. We investigate the effect of different binders, ink concentration, and spray-coating conditions, i.e. spray power, flow rate from syringe pump, distance between spray nozzle and the substrate, and time...

  15. Arc-discharge system for nondestructive detection of flaws in thin ceramic coatings

    International Nuclear Information System (INIS)

    Scott, G.W.; Davis, E.V.

    1978-04-01

    The feasibility of nondestructively detecting small cracks or holes in plasma-sprayed ceramic coatings with an electric arc-discharge system was studied. We inspected ZrO 2 coatings 0.46 mm (0.018 in.) thick on Incoloy alloy 800 substrates. Cracks were artificially induced in controlled areas of the specimens by straining the substrates in tension. We designed and built a system to scan the specimen's surface at approximately 50 μm (0.002 in.) clearance with a sharp-pointed metal-tipped probe at high dc potential. The system measures the arc currents occurring at flaws, or plots a map of the scanned area showing points where the arc current exceeds a preset threshold. A theoretical model of the probe-specimen circuit shows constant dc potential to be the best choice for arc-discharge inspection of insulating coatings. Experimental observations and analysis of the data disclosed some potential for flaw description

  16. Photoelectrode Fabrication of Dye-Sensitized Nanosolar Cells Using Multiple Spray Coating Technique

    Directory of Open Access Journals (Sweden)

    Chien-Chih Chen

    2013-01-01

    Full Text Available This paper presents a spray coating technique for fabricating nanoporous film of photoelectrode in dye-sensitized nanosolar cells (DSSCs. Spray coating can quickly fabricate nanoporous film of the photoelectrode with lower cost, which can further help the DSSCs to be commercialized in the future. This paper analyzed photoelectric conversion efficiency of the DSSCs using spray coated photoelectrode in comparison with the photoelectrode made with the doctor blade method. Spray coating can easily control transmittance of the photoelectrode through the multiple spray coating process. This work mainly used a dispersant with help of ultrasonic oscillation to prepare the required nano-TiO2 solution and then sprayed it on the ITO glasses. In this work, a motor-operated conveyor belt was built to transport the ITO glasses automatically for multiple spray coating and drying alternately. Experiments used transmittance of the photoelectrode as a fabrication parameter to analyze photoelectric conversion efficiency of the DSSCs. The influencing factors of the photoelectrode transmittance during fabrication are the spray flow rate, the spray distance, and the moving speed of the conveyor belt. The results show that DSSC with the photoelectrode transmittance of ca. 68.0 ± 1.5% and coated by the spray coating technique has the best photoelectric conversion efficiency in this work.

  17. Laser Processing of Multilayered Thermal Spray Coatings: Optimal Processing Parameters

    Science.gov (United States)

    Tewolde, Mahder; Zhang, Tao; Lee, Hwasoo; Sampath, Sanjay; Hwang, David; Longtin, Jon

    2017-12-01

    Laser processing offers an innovative approach for the fabrication and transformation of a wide range of materials. As a rapid, non-contact, and precision material removal technology, lasers are natural tools to process thermal spray coatings. Recently, a thermoelectric generator (TEG) was fabricated using thermal spray and laser processing. The TEG device represents a multilayer, multimaterial functional thermal spray structure, with laser processing serving an essential role in its fabrication. Several unique challenges are presented when processing such multilayer coatings, and the focus of this work is on the selection of laser processing parameters for optimal feature quality and device performance. A parametric study is carried out using three short-pulse lasers, where laser power, repetition rate and processing speed are varied to determine the laser parameters that result in high-quality features. The resulting laser patterns are characterized using optical and scanning electron microscopy, energy-dispersive x-ray spectroscopy, and electrical isolation tests between patterned regions. The underlying laser interaction and material removal mechanisms that affect the feature quality are discussed. Feature quality was found to improve both by using a multiscanning approach and an optional assist gas of air or nitrogen. Electrically isolated regions were also patterned in a cylindrical test specimen.

  18. Thermal Conductivity Change Kinetics of Ceramic Thermal Barrier Coatings Determined by the Steady-State Laser Heat Flux Technique

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    2000-01-01

    A steady-state laser heat flux technique has been developed at the NASA Glenn Research Center at Lewis Field to obtain critical thermal conductivity data of ceramic thermal barrier coatings under the temperature and thermal gradients that are realistically expected to be encountered in advanced engine systems. In this study, thermal conductivity change kinetics of a plasma-sprayed, 254-mm-thick ZrO2-8 wt % Y2O3 ceramic coating were obtained at high temperatures. During the testing, the temperature gradients across the coating system were carefully measured by the surface and back pyrometers and an embedded miniature thermocouple in the substrate. The actual heat flux passing through the coating system was determined from the metal substrate temperature drop (measured by the embedded miniature thermocouple and the back pyrometer) combined with one-dimensional heat transfer models.

  19. Optimization and Characterization of High Velocity Oxy-fuel Sprayed Coatings: Techniques, Materials, and Applications

    Directory of Open Access Journals (Sweden)

    Maria Oksa

    2011-09-01

    Full Text Available In this work High Velocity Oxy-fuel (HVOF thermal spray techniques, spraying process optimization, and characterization of coatings are reviewed. Different variants of the technology are described and the main differences in spray conditions in terms of particle kinetics and thermal energy are rationalized. Methods and tools for controlling the spray process are presented as well as their use in optimizing the coating process. It will be shown how the differences from the starting powder to the final coating formation affect the coating microstructure and performance. Typical properties of HVOF sprayed coatings and coating performance is described. Also development of testing methods used for the evaluation of coating properties and current status of standardization is presented. Short discussion of typical applications is done.

  20. Sol-gel coatings of ceramic fibres for composites with ceramic matrix

    International Nuclear Information System (INIS)

    Maier, B.; Grathwohl, G.; Spallek, M.; Pannhorst, W.

    1992-01-01

    The aim of this work was to show the feasibility in principle of sol-gel coating of ceramic reinforcement components for composites from technical aspects as well. The complexity of the coating task rises with the transition from individual fibres to bundles of fibres of different thickness to weaves, and finally to composites. (orig.) [de

  1. Sintering of Fine Particles in Suspension Plasma Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Leszek Latka

    2010-07-01

    Full Text Available Suspension plasma spraying is a process that enables the production of finely grained nanometric or submicrometric coatings. The suspensions are formulated with the use of fine powder particles in water or alcohol with some additives. Subsequently, the suspension is injected into plasma jet and the liquid additives evaporate. The remaining fine solids are molten and subsequently agglomerate or remain solid, depending on their trajectory in the plasma jet. The coating’s microstructure results from these two groups of particles arriving on a substrate or previously deposited coating. Previous experimental studies carried out for plasma sprayed titanium oxide and hydroxyapatite coatings enabled us to observe either a finely grained microstructure or, when a different suspension injection mode was used, to distinguish two zones in the microstructure. These two zones correspond to the dense zone formed from well molten particles, and the agglomerated zone formed from fine solid particles that arrive on the substrate in a solid state. The present paper focuses on the experimental and theoretical analysis of the formation process of the agglomerated zone. The experimental section establishes the heat flux supplied to the coating during deposition. In order to achieve this, calorimetric measurements were made by applying experimental conditions simulating the real coatings’ growth. The heat flux was measured to be in the range from 0.08 to 0.5 MW/m2,depending on the experimental conditions. The theoretical section analyzes the sintering during the coating’s growth, which concerns the fine particles arriving on the substrate in the solid state. The models of volume, grain boundary and surface diffusion were analyzed and adapted to the size and chemistry of the grains, temperature and time scales corresponding to the suspension plasma spraying conditions. The model of surface diffusion was found to best describe the sintering during suspension

  2. Ballistic performance of polyurea-coated armor grade ceramic tiles

    Science.gov (United States)

    Samiee, Ahsan; Isaacs, Jon; Nemat-Nasser, Sia

    2010-04-01

    The use of ceramics as energy absorbents has been studied by many researchers and some improvements in the ballistic performance of ceramic tiles have been made by coating them with different classes of materials (e.g. E-glass/epoxy, carbon-fiber/epoxy, etc.). Using ceramics for energy absorbing applications leads to a significant weight reduction of the system. Therefore, any modification to the ceramic configuration in the system which leads to more energy absorption with the same or less areal density is significant. On the other hand, polyurea has been proved to be an excellent energy dissipating agent in many applications. Inspired by this, we are studying the effect of coating ceramics with polyurea and other materials, on the energy absorption and ballistic performance of the resulting ceramic-based composites. In this study, we investigate the effect of polyurea on ballistic efficiency of ceramic tiles. To this end, we have performed a set of penetration tests on polyurea-ceramic composites. In our experiments, a high velocity projectile is propelled to impact and perforate the ceramic-polyurea composite. The velocity and mass of the projectile are measured before and after the penetration. The change in the kinetic energy of the projectile is evaluated and compared for different polyurea-ceramic configurations (e.g., polyurea on front face, polyurea on back face, polyurea between two ceramic tiles, etc.). The experimental results suggest that polyurea is not as effective as other restraining materials such as E-glass/epoxy and carbon-fiber/epoxy.

  3. 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.

  4. Characteristics and heat treatment of cold-sprayed Al-Sn binary alloy coatings

    International Nuclear Information System (INIS)

    Ning, Xian-Jin; Kim, Jin-Hong; Kim, Hyung-Jun; Lee, Changhee

    2009-01-01

    In this study, Al-Sn binary alloy coatings were prepared with Al-5 wt.% Sn (Al-5Sn) and Al-10 wt.% Sn (Al-10Sn) gas atomized powders by low pressure and high pressure cold spray process. The microstructure and microhardness of the coatings were characterized. To understand the coarsening of tin in the coating, the as-sprayed coatings were annealed at 150, 200, 250 and 300 o C for 1 h, respectively. The effect of annealing on microstructure and the bond strength of the coatings were investigated. The results show that Al-5Sn coating can be deposited by high pressure cold spray with nitrogen while Al-10Sn can only be deposited by low pressure cold spray with helium gas. Both Al-5Sn and Al-10Sn coatings present dense structures. The fraction of Sn in as-sprayed coatings is consistent with that in feed stock powders. The coarsening and/or migration of Sn phase in the coatings were observed when the annealing temperature exceeds 200 deg. C. Furthermore, the microhardness of the coatings decreased significantly at the annealing temperature of 250 deg. C. EDXA analysis shows that the heat treatment has no significant effect on fraction of Sn phase in Al-5Sn coatings. Bonding strength of as-sprayed Al-10Sn coating is slightly higher than that of Al-5Sn coating. Annealing at 200 o C can increase the bonding strength of Al-5Sn coatings.

  5. 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

  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. Iron-Based Amorphous Coatings Produced by HVOF Thermal Spray Processing-Coating Structure and Properties

    Energy Technology Data Exchange (ETDEWEB)

    Beardsley, M B

    2008-03-26

    The feasibility to coat large SNF/HLW containers with a structurally amorphous material (SAM) was demonstrated on sub-scale models fabricated from Type 316L stainless steel. The sub-scale model were coated with SAM 1651 material using kerosene high velocity oxygen fuel (HVOF) torch to thicknesses ranging from 1 mm to 2 mm. The process parameters such as standoff distance, oxygen flow, and kerosene flow, were optimized in order to improve the corrosion properties of the coatings. Testing in an electrochemical cell and long-term exposure to a salt spray environment were used to guide the selection of process parameters.

  8. Fatigue Crack Growth in Bodies with Thermally Sprayed Coating

    Czech Academy of Sciences Publication Activity Database

    Kovářík, O.; Haušild, P.; Medřický, Jan; Tomek, L.; Siegl, J.; Mušálek, Radek; Curry, N.; Björklund, S.

    2016-01-01

    Roč. 25, 1-2 (2016), s. 311-320 ISSN 1059-9630. [ITSC 2015 : International Thermal Spray Conference and Exposition. Long Beach, California, 11.05. 2015 -14.05. 2015 ] R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : Thermal barrier coating * fatigue * crack growth * digital image correlation * digital image correlation Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.488, year: 2016 http://link.springer.com/article/10.1007%2Fs11666-015-0329-9

  9. Fatigue Crack Growth in Bodies with Thermally Sprayed Coating

    Czech Academy of Sciences Publication Activity Database

    Kovářík, O.; Haušild, P.; Medřický, Jan; Tomek, L.; Siegl, J.; Mušálek, Radek; Curry, N.; Björklund, S.

    2016-01-01

    Roč. 25, 1-2 (2016), s. 311-320 ISSN 1059-9630. [ITSC 2015: International Thermal Spray Conference and Exposition. Long Beach, California, 11.05.2015-14.05.2015] R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : Thermal barrier coating * fatigue * crack growth * digital image correlation * digital image correlation Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.488, year: 2016 http://link.springer.com/article/10.1007%2Fs11666-015-0329-9

  10. Spherical resonators coated by glass and glass-ceramic films

    Science.gov (United States)

    Ristic, Davor; Chiappini, Andrea; Chiasera, Alessandro; Armellini, Cristina; Carpentiero, Alessandro; Mazzola, Maurizio; Moser, Enrico; Varas, Stefano; Berneschi, Simone; Nunzi Conti, Gualtiero; Pelli, Stefano; Soria, Silvia; Speranza, Giorgio; Lunelli, Lorenzo; Pederzolli, Cecilia; Prudenzano, Francesco; Feron, Patrice; Ivanda, Mile; Cibiel, Gilles; Righini, Giancarlo C.; Ferrari, Maurizio

    2012-02-01

    Coating of spherical microresonators is a very promising technique for optimizing their optical properties. Optical coatings are constituted by glasses, polymer, and glass ceramics, passive or activated by luminescent species, Glass ceramic activated by rare earth ions are nanocomposite systems that exhibit specific morphologic, structural and spectroscopic properties allowing to develop interesting new physical concepts, for instance the mechanism related to the transparency, as well as novel photonic devices based on the enhancement of the luminescence. At the state of art the fabrication techniques based on bottom-up and top-down approaches appear to be viable although a specific effort is required to achieve the necessary reliability and reproducibility of the preparation protocols. In particular, the dependence of the final product on the specific parent glass and on the employed synthesis still remain an important task of the research in material science. Looking to application, the enhanced spectroscopic properties typical of glass ceramic in respect to those of the amorphous structures constitute an important point for the development of integrated optics devices, including coating of spherical microresonators. Here we present a review regarding spherical microresonators coated by glass and glass-ceramic film activated by Er3+ ions. Er3+ ions appear to be embedded in a crystalline or amorphous environment and the lifetime dynamic is influenced by the geometry and by the morphology of the system. Photoluminescence results and morphologic properties are discussed for both amorphous and glass ceramic films.

  11. Glass enamel and glass-ceramic coatings for chemical apparatus

    International Nuclear Information System (INIS)

    Es'kov, A.S.; Oleinik, M.I.; Shabrova, E.A.

    1984-01-01

    Among the known anticorrosion coatings used in chemical engineering, glass enamel base coatings are distinguished by such advantages as a high degree of continuity and chemical resistance. The paper describes basic principles for the creation of acid and alkali resistant glass enamel and ceramic coatings for chemical apparatus. As the result of investgations, glass enamel coatings with increased electrical conductivity and also experimental production compositions of chemical, temperature and radiation resistant coatings for protection of chemical equipment of 12Kh18N10T stainless steel have been developed. The coatings have successfully passed testing under service conditions. A new type of coating is short-term glass enamel, which may be recommended for use in chemical machinery manufacturing and other branches of industry in oxidation-free heating and forming of stainless steels

  12. Method for preparing thin-walled ceramic articles of configuration

    International Nuclear Information System (INIS)

    Holcombe, C.E.; Powell, G.L.

    1975-01-01

    A method for preparing a hollow thin-walled ceramic product is described. Ceramic powder is plasma-sprayed onto a concave surface of a substrate having a coefficient of thermal expansion less than that of the ceramic. The coated substrate is heated to sinter the ceramic and then cooled to effect a separation of the ceramic product from the substrate

  13. 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.

  14. 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.

  15. A sputtered zirconia primer for improved thermal shock resistance of plasma sprayed ceramic turbine seals

    Science.gov (United States)

    Bill, R. C.; Sovey, J.; Allen, G. P.

    1981-01-01

    The development of plasma-sprayed yttria stabilized zirconia (YSZ) ceramic turbine blade tip seal components is discussed. The YSZ layers are quite thick (0.040 to 0.090 in.). The service potential of seal components with such thick ceramic layers is cyclic thermal shock limited. The most usual failure mode is ceramic layer delamination at or very near the interface between the plasma sprayed YSZ layer and the NiCrAlY bondcoat. Deposition of a thin RF sputtered YSZ primer to the bondcoat prior to deposition of the thick plasma sprayed YSZ layer was found to reduce laminar cracking in cyclic thermal shock testing. The cyclic thermal shock life of one ceramic seal design was increased by a factor of 5 to 6 when the sputtered YSZ primer was incorporated. A model based on thermal response of plasma sprayed YSZ particles impinging on the bondcoat surface with and without the sputtered YSZ primer provides a basis for understanding the function of the primer.

  16. Relationships between spray parameters, microstructures and ultrasonic cavitation erosion behavior of HVOF sprayed Fe-based amorphous/nanocrystalline coatings.

    Science.gov (United States)

    Qiao, Lei; Wu, Yuping; Hong, Sheng; Zhang, Jianfeng; Shi, Wei; Zheng, Yugui

    2017-11-01

    Fe-based amorphous/nanocrystalline coatings were prepared on the AISI 321 steel substrate by the high-velocity oxygen-fuel (HVOF) thermal spraying technology. The effect of selected parameters (oxygen flow, kerosene flow and spray distance) on the cavitation erosion resistance (denoted as Rc) of the coating were investigated by using the Taguchi method. Statistical tools such as design of experiments (DOE), signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were used to meet the expected objective. It was concluded that the kerosene flow had greater influence on the Rc of the coating and followed by the spray distance and the oxygen flow, respectively. The optimum spray parameters (OSP) were 963L/min for the oxygen flow, 28L/h for the kerosene flow, and 330mm for the spray distance. The Rc of the coating increased with the increase of hardness or the decrease of porosity, and the hardness had a greater influence on Rc than the porosity. The Fe-based coating deposited under the OSP exhibited the best cavitation erosion resistance in distilled water. The cracks initiated at the edge of the pores and the interfaces between the un-melted or half-melted particles, and finally leaded to the delamination of the coating. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. 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

  18. 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

  19. Organometallic Polymer Coatings for Geothermal-Fluid-Sprayed Air-Cooled Condensers: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Gawlik, K.; Sugama, T.; Jung, D.

    2002-08-01

    Researchers are developing polymer-based coating systems to reduce scaling and corrosion of air-cooled condensers that use a geothermal fluid spray for heat transfer augmentation. These coating systems act as barriers to corrosion to protect aluminum fins and steel tubing; they are formulated to resist the strong attachment of scale. Field tests have been done to determine the corrosion and scaling issues related to brine spraying and a promising organometallic polymer has been evaluated in salt spray tests.

  20. 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.

  1. Ceramic coated Y1 magnesium alloy surfaces by microarc oxidation ...

    Indian Academy of Sciences (India)

    TECS

    V V NARULKAR*, S PRAKASH and K CHANDRA. Metallurgical and Materials Engineering Department, Indian Institute of Technology, Roorkee 247 667, India .... The microarc oxidation ceramic coating is mainly composed of cubic MgO, and MgAl2O4 sharp spinels as well as a little amount of MgSiO3, which di-. Figure 2.

  2. Glass and glass–ceramic coatings, versatile materials for industrial ...

    Indian Academy of Sciences (India)

    Unknown

    In general, these glass–ceramic coating slips have excellent rheological properties and application is very easy and cost-effective too. They produce a good surface finish with a good soothing colour ranging from bluish grey to milky white. They can also be coloured using various inorganic pigments without affecting overall.

  3. Powder addition assessment of manganese residue ceramic matrix coating

    International Nuclear Information System (INIS)

    Conceicao, A.C.R. da; Santos, O.C.; Leao, M.A.

    2016-01-01

    The use of recycled materials in the composition of new products follows the production's worldwide trending, meeting new technological requirements and environmental concerns. This work aims to utilize the residue of manganese dust on ceramic mass for the production of ceramic coating. The raw materials were characterized by both x-ray fluorescence and diffraction. The powder residue added to clay in the percentage of 0%, 5%, 10% and 15% (measured in weight) was compressed by a uniaxial pressing of 30MPa and the sintering temperatures were 900°, 1000° and 1100°. The samples were analysed in relation to flexural strength, bulk density, water absorption and linear shrinkage. The microstructural variation was also analysed by x-ray diffraction and electron microscopy. The results showed that there is a viability for the production of porcelain ceramic coating (A3 and A4 formulations) and stoneware (A2 formulation) according to the specification of technical standards. author)

  4. Modeling of Thickness and Profile Uniformity of Thermally Sprayed Coatings Deposited on Cylinders

    Science.gov (United States)

    Yanjun, Zhang; Wenbo, Li; Dayu, Li; Jinkun, Xiao; Chao, Zhang

    2018-02-01

    In thermal spraying processes, kinematic parameters of the robot play a decisive role in the coating thickness and profile. In this regard, some achievements have been made to optimize the spray trajectory on flat surfaces. However, few reports have focused on nonholonomic or variable-curvature cylindrical surfaces. The aim of this study is to investigate the correlation between the coating profile, coating thickness, and scanning step, which is determined by the radius of curvature and scanning angle. A mathematical simulation model was developed to predict the thickness of thermally sprayed coatings. Experiments were performed on cylinders with different radiuses of curvature to evaluate the predictive ability of the model.

  5. 40 CFR 63.5755 - How do I demonstrate compliance with the aluminum recreational boat surface coating spray gun...

    Science.gov (United States)

    2010-07-01

    ... the aluminum recreational boat surface coating spray gun cleaning work practice standards? 63.5755... surface coating spray gun cleaning work practice standards? You must demonstrate compliance with the aluminum coating spray gun cleaning work practice standards by meeting the requirements of paragraph (a) or...

  6. Optimization of Arc-Sprayed Ni-Cr-Ti Coatings for High Temperature Corrosion Applications

    Science.gov (United States)

    Matthews, S.; Schweizer, M.

    2013-04-01

    High Cr content Ni-Cr-Ti arc-spray coatings have proven successful in resisting the high temperature sulfidizing conditions found in black liquor recovery boilers in the pulp and paper industry. The corrosion resistance of the coatings is dependent upon the coating composition, to form chromium sulfides and oxides to seal the coating, and on the coating microstructure. Selection of the arc-spray parameters influences the size, temperature and velocity of the molten droplets generated during spraying, which in turn dictates the coating composition and formation of the critical coating microstructural features—splat size, porosity and oxide content. Hence it is critical to optimize the arc-spray parameters in order to maximize the corrosion resistance of the coating. In this work the effect of key spray parameters (current, voltage, spray distance and gas atomizing pressure) on the coating splat thickness, porosity content, oxide content, microhardness, thickness, and surface profile were investigated using a full factorial design of experiment. Based on these results a set of oxidized, porous and optimized coatings were prepared and characterized in detail for follow-up corrosion testing.

  7. Influence of coating defects on the corrosion behavior of cold sprayed refractory metals

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S., E-mail: skumar@arci.res.in; Rao, A. Arjuna

    2017-02-28

    Highlights: • Long duration immersion tests reveal inhomogeneous weight losses. • The weight loss for different coatings are well corroborated with the coating defects. • Chemical and micro structural analysis elucidates the reason behind the in homogeneous performance of different type of cold sprayed coatings. • In cold sprayed titanium, formation of oxide along the inter-splat boundary hinders the aggressive attack of the medium. - Abstract: The defects in the cold sprayed coatings are critical in the case of corrosion performances of the coatings in aggressive conditions. To understand the influence of coating defects on corrosion, immersion tests have been carried out in HF solution for the cold sprayed and heat treated Titanium, Tantalum and Niobium coatings. Long duration immersion tests reveal inhomogeneous weight losses of the samples prepared at different heat treatment conditions. The weight loss for different coatings has been well corroborated with the coating defects and microstructures. Chemical and micro structural analysis elucidates the reason behind the inhomogeneous performance of different type of cold sprayed coatings in corrosion medium. In the case of cold sprayed titanium, formation of stable oxide along the inter-splat boundary hinders the aggressive attack of the corrosion medium which is not so in other cases.

  8. Structure, Mechanical Properties and Thermal Conductivity of Thermal Sprayed Nickel Coatings

    Science.gov (United States)

    Murakami, Kenji; Matsumoto, Hiroshi; Nakajima, Hideo

    Nickel powder was low pressure plasma sprayed onto a steel substrate, and the influence of the thermal history of the coating on the structures and the properties of the coating were examined. The lamellae of the coating was composed of fine columnar grains when the temperature of the coating was kept low during spraying. As the temperature of the coating during spraying increases, the length of the columnar grains became longer than the thickness of the lamellae. The coating heat-treated after spraying consisted of coarse equiaxed grains and had high porosity that came from the liberation of a plasma gas dissolved in rapidly solidified solid nickel. The hardness, apparent density and the tensile strength of the coating itself were the highest on the coating prepared at a low temperature and became low after heat-treatment. The thermal conductivity measured in the direction perpendicular to the coating was the largest on the coating that consisted of long columnar grains. The cause for the formation of the long columnar grains is discussed in terms of the momentary and local melting of the coating surface that is in contact with the sprayed droplet and the grain growth in the solid state due to the large temperature gradient in the coating.

  9. Sintering characteristics of nano-ceramic coatings

    NARCIS (Netherlands)

    de Hosson, J.T.M.; Popma, R.

    2003-01-01

    This paper concentrates on sintering characteristics of nano-sized ceramic SiO2 particles. The sintering process is studied as a function of temperature using a conventional furnace and using a laser beam. The underlying idea is to combine the nanoceramic sol-gel concept with inkjet technology and

  10. In situ measurement of ceramic vacuum chamber conductive coating quality

    International Nuclear Information System (INIS)

    Doose, C.; Harkay, K.; Kim, S.; Milton, S.

    1997-01-01

    A method for measuring the relative surface resistivity and quality of conductive coatings on ceramic vacuum chambers was developed. This method is unique in that it allows one to test the coating even after the ceramic chamber is installed in the accelerator and under vacuum; furthermore, the measurement provides a localized surface reading of the coating conductance. The method uses a magnetic probe is calibrated using the measured DC end-to-end resistance of the tube under test and by comparison to a high quality test surface. The measurement method has also been verified by comparison to high frequency impedance measurements. A detailed description, results, and sensitivity of the technique are given here

  11. Prime surface coating: A novel method for making thick ceramic coatings

    Science.gov (United States)

    Kashefi, Mehrdad

    The use of coatings to protect or enhance the performance of a component manufactured from a different material is well recognised as a cost effective solution in many engineering situations. This approach is particularly appropriate for ceramic materials deposited as coatings. However, in general such coatings are either relatively thin (determined that ceramic powders could be well dispersed in an alkoxyethyl cyanoacrylate binder to a maximum volume fraction of 0.45 for uni-modal powders with mean particle sizes 8 mum, and 0.58 for a bi-modal alumina powder, Para-toluene sulphonic acid and caffeine have been identified as suitable polymerization inhibitors and initiators respectively. Coatings with controlled thicknesses between 0.4 and 1.0 mm have been successfully deposited onto metallic and ceramic substrates. SEM micrographs show good uniformity of the coating and that successful adhesion can be achieved, as also shown by the joint shear strength test results. The versatile properties of the cyanoacrylates suggest that there are potential applications for the coatings at the cured stage. This study also describes and discusses the debinding and sintering of alumina and zirconia coatings. Using 96% alumina substrates resulted in successful sintering of the debonded layers to full density. The microstructural studies show good uniformity in the coatings with good adhesion to the substrate. The indentation hardness and toughness values measured in the sintered coatings were comparable with the results obtained on the commercial alumina used as the substrate.

  12. Determination of parameters for successful spray coating of silicon microneedle arrays.

    Science.gov (United States)

    McGrath, Marie G; Vrdoljak, Anto; O'Mahony, Conor; Oliveira, Jorge C; Moore, Anne C; Crean, Abina M

    2011-08-30

    Coated microneedle patches have demonstrated potential for effective, minimally invasive, drug and vaccine delivery. To facilitate cost-effective, industrial-scale production of coated microneedle patches, a continuous coating method which utilises conventional pharmaceutical processes is an attractive prospect. Here, the potential of spray-coating silicon microneedle patches using a conventional film-coating process was evaluated and the key process parameters which impact on coating coalescence and weight were identified by employing a fractional factorial design to coat flat silicon patches. Processing parameters analysed included concentration of coating material, liquid input rate, duration of spraying, atomisation air pressure, gun-to-surface distance and air cap setting. Two film-coating materials were investigated; hydroxypropylmethylcellulose (HPMC) and carboxymethylcellulose (CMC). HPMC readily formed a film-coat on silicon when suitable spray coating parameter settings were determined. CMC films required the inclusion of a surfactant (1%, w/w Tween 80) to facilitate coalescence of the sprayed droplets on the silicon surface. Spray coating parameters identified by experimental design, successfully coated 280μm silicon microneedle arrays, producing an intact film-coat, which follows the contours of the microneedle array without occlusion of the microneedle shape. This study demonstrates a novel method of coating microneedle arrays with biocompatible polymers using a conventional film-coating process. It is the first study to indicate the thickness and roughness of coatings applied to microneedle arrays. The study also highlights the importance of identifying suitable processing parameters when film coating substrates of micron dimensions. The ability of a fractional factorial design to identify these critical parameters is also demonstrated. The polymer coatings applied in this study can potentially be drug loaded for intradermal drug and vaccine delivery

  13. 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 * tribolog y * hardness * wear * abrasion * chromia/stainless steel Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.559, year: 2006

  14. Indentation creep behavior of cold sprayed aluminum amorphous/nano-crystalline coatings

    Energy Technology Data Exchange (ETDEWEB)

    Babu, P. Suresh [International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur, Hyderabad 500005, Andhra Pradesh (India); Nanomechanics and Nanotribology Laboratory, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States); Jha, R.; Guzman, M. [Nanomechanics and Nanotribology Laboratory, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States); Sundararajan, G. [International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Balapur, Hyderabad 500005, Andhra Pradesh (India); Agarwal, Arvind, E-mail: agarwala@fiu.edu [Nanomechanics and Nanotribology Laboratory, Department of Mechanical and Materials Engineering, Florida International University, Miami, FL 33174 (United States)

    2016-03-21

    In this study, we report room temperature creep properties of cold sprayed aluminum amorphous/nanocrystalline coating using nanoindentation technique. Creep experiments were also performed on heat treated coatings to study the structural stability and its influence on the creep behavior. The peak load and holding time were varied from 1000 to 4000 µN and 0 to 240 s respectively. Stress exponent value (n) vary from 5.6 to 2.3 in as-sprayed (AS) coatings and 7.2–4.8 in heat treated (HT) coatings at peak load of 1000–4000 µN at 240 s hold time. Higher stress exponent value indicates heat treated coatings have more resistance to creep deformation than as-sprayed coatings. Relaxed, partially crystallized structure with less porosity, and stronger inter-splat boundaries restrict the deformation in heat treated coatings as compared to greater free volume generation in amorphous as-sprayed coatings. The computed activation volume of heat treated coatings is twice of as-sprayed coatings indicating greater number of atom participation in shear band formation in heat treated coatings. The proposed mechanism was found to be consistent with the stress exponent values.

  15. Cermet composite thermal spray coatings for erosion and corrosion protection in combustion environments of advanced coal-fired boilers. Semiannual technical report, January 14, 1997--August 14, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Schorr, B.S.; Levin, B.F.; DuPont, J.N.; Marder, A.R.

    1997-08-31

    Research is presently being conducted to determine the optimum ceramic/metal combination in thermally sprayed metal matrix composite coatings for erosion and corrosion resistance in new coal-fired boilers. The research will be accomplished by producing model cermet composites using powder metallurgy and electrodeposition methods in which the effect of ceramic/metal combination for the erosion and corrosion resistance will be determined. These results will provide the basis for determining the optimum hard phase constituent size and volume percent in thermal spray coatings. Thermal spray coatings will be applied by our industrial sponsor and tested in our erosion and corrosion laboratories. Bulk powder processed Ni-Al{sub 2}O{sub 3} composites were produced at Idaho National Engineering Laboratory. The composite samples contained 0, 21, 27, 37, and 45 volume percent Al{sub 2}O{sub 3} with an average particle size of 12 um. Also, to deposit model Ni-Al{sub 2}O{sub 3} coatings, an electrodeposition technique was developed and coatings with various volume fractions (0-35%) of Al{sub 2}O{sub 3} were produced. The powder and electrodeposition processing of Ni-Al{sub 2}O{sub 3} Composites provide the ability to produce two phase microstructure without changing the microstructure of the matrix material. Therefore, the effect of hard second phase particles size and volume fraction on erosion resistance could be analyzed.

  16. Ferromagnetic shadow mask for spray coating of polymer patterns

    DEFF Research Database (Denmark)

    Keller, Stephan Sylvest; Bosco, Filippo; Boisen, Anja

    2013-01-01

    We present the fabrication of a wafer-scale shadow mask with arrays of circular holes with diameters of 150–400 μm. Standard UV photolithography is used to define 700 μm thick SU-8 structures followed by electroplating of nickel and etching of the template. The ferromagnetic properties of the sha......We present the fabrication of a wafer-scale shadow mask with arrays of circular holes with diameters of 150–400 μm. Standard UV photolithography is used to define 700 μm thick SU-8 structures followed by electroplating of nickel and etching of the template. The ferromagnetic properties...... of the shadow mask allow magnetic clamping to the substrate and spray coating of well defined polymer patterns....

  17. Bonding strength of glass-ceramic trabecular-like coatings to ceramic substrates for prosthetic applications.

    Science.gov (United States)

    Chen, Qiang; Baino, Francesco; Pugno, Nicola M; Vitale-Brovarone, Chiara

    2013-04-01

    A new approach based on the concepts of quantized fracture mechanics (QFM) is presented and discussed in this paper to estimate the bonding strength of trabecular-like coatings, i.e. glass-ceramic scaffolds mimicking the architecture of cancellous bone, to ceramic substrates. The innovative application of glass-derived scaffolds as trabecular-like coatings is proposed in order to enhance the osteointegration of prosthetic ceramic devices. The scaffolds, prepared by polymeric sponge replication, are joined to alumina substrates by a dense glass-ceramic coating (interlayer) and the so-obtained 3-layer constructs are investigated from micro-structural, morphological and mechanical viewpoints. In particular, the fracture strengths of three different crack propagation modes, i.e. glass-derived scaffold fracture, interface delamination or mixed fracture, are predicted in agreement with those of experimental mechanical tests. The approach proposed in this work could have interesting applications towards an ever more rational design of bone tissue engineering biomaterials and coatings, in view of the optimization of their mechanical properties for making them actually suitable for clinical applications. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Ceramic Fiber Coatings Development and Demonstration

    Science.gov (United States)

    1993-05-28

    sizing, which is compatible with PACVD , is to thermally remove it. Several tests in the plasma assisted coater with different plasma energies were...Desizing can now be accomplished continuously as the fibers pass through the furnace. PACVD Filament Coatings Plasma-assisted chemical vapor deposition... PACVD ) BN coatings were made from B2FH in H2 and NH3 gas precursors. These gases were the principle precursors evaluated. Process parameters examined

  19. Freeze-Spray Processing of Layered Ceramic Composites (Preprint)

    Science.gov (United States)

    2006-04-01

    used to spray thin layers of slurries on a cryogenically cooled metallic plate . The slurries freeze almost instantly, forming solid structures. The...34Optimization of FGM TBC and Their Thermal Cycling Stability," Mater. Sci Forum, 492,9-14 (2005). K . An, K. Ravichandran, R. Dutton, and S. Semiatin

  20. Polymer derived ceramic composites as environmental barrier coatings on steel

    Science.gov (United States)

    Torrey, Jessica D.

    Polymer derived ceramics have shown promise as a novel way to process low-dimensional ceramics such as fibers and coatings. They offer advantages over traditional ceramic processing routes including lower pyrolysis temperatures and the ability to employ polymeric processing techniques. The main drawback to preceramic polymers is that they undergo a shrinkage during pyrolysis that can be greater than 50-volume%. One way to overcome this shrinkage is to add filler particles, usually elemental or binary metals, which will expand upon reaction with the pyrolysis atmosphere, thereby compensating for the shrinkage of the polymer. The aim of this study is to develop a polymer derived ceramic composite coating on steel as a barrier to oxidation and carburization, while concurrently gaining insight as to the fundamental mechanisms for compositional and microstructural evolution within the system. A systematic approach to selecting the preceramic polymer and expansion agents was taken. Six commercially available poly(silsesquioxane) polymers and a polysiloxane were studied. Several metals and an intermetallic were considered as potential expansion agents. The most desirable polymer/expansion agent combination was achieved with poly(hydridomethylsiloxane) as the matrix and titanium disilicide as the filler. Processing parameters have been optimized and a relationship derived to predict final coating thickness based on slurry viscosity and dip coating withdrawal speed. Microstructural analysis reveals an amorphous composite coating of oxidized filler particles in a silica matrix. A diffusion layer is visible at the coating-steel interface, indicating good bonding. The optimized coatings are ˜18mum thick, have some residual porosity and a density of 2.57g/cm3. A systematic study of the phase transformations and microstructural changes in the coating and its components during pyrolysis in air is also presented. The system evolves from a polymer filled with a binary metal at

  1. The erosion performance of cold spray deposited metal matrix composite coatings with subsequent friction stir processing

    Science.gov (United States)

    Peat, Tom; Galloway, Alexander; Toumpis, Athanasios; McNutt, Philip; Iqbal, Naveed

    2017-02-01

    This study forms an initial investigation into the development of SprayStir, an innovative processing technique for generating erosion resistant surface layers on a chosen substrate material. Tungsten carbide - cobalt chromium, chromium carbide - nickel chromium and aluminium oxide coatings were successfully cold spray deposited on AA5083 grade aluminium. In order to improve the deposition efficiency of the cold spray process, coatings were co-deposited with powdered AA5083 using a twin powder feed system that resulted in thick (>300 μm) composite coatings. The deposited coatings were subsequently friction stir processed to embed the particles in the substrate in order to generate a metal matrix composite (MMC) surface layer. The primary aim of this investigation was to examine the erosion performance of the SprayStirred surfaces and demonstrate the benefits of this novel process as a surface engineering technique. Volumetric analysis of the SprayStirred surfaces highlighted a drop of approx. 40% in the level of material loss when compared with the cold spray deposited coating prior to friction stir processing. Micro-hardness testing revealed that in the case of WC-CoCr reinforced coating, the hardness of the SprayStirred material exhibits an increase of approx. 540% over the unaltered substrate and 120% over the as-deposited composite coating. Microstructural examination demonstrated that the increase in the hardness of the MMC aligns with the improved dispersion of reinforcing particles throughout the aluminium matrix.

  2. Coating Properties of WC-Ni Cold Spray Coating for the Application in Secondary Piping System of Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, JeongWon; Kim, Seunghyun; Kim, Ji Hyun [UNIST, Ulsan (Korea, Republic of)

    2015-10-15

    As a result of FAC(flow accelerated corrosion), severe accidents, failure of carbon steel like a Mihama Unit-3 occurred. Chemical composition change of carbon steel or coating to inner surface is one of methods to improve corrosion properties. Among them, thermal spray coating is convenient solution to apply at industry. Powder is melted at blast furnace and ejected to substrate. After adhesion, substrate and coating layer is cooled down and coated layer protects steel from corrosion finally. However high thermal energy is transferred to substrate and coating layer so it leads high thermal residual stress in coating procedure. Besides, high temperature for melting powder makes unexpected chemical reaction of powder like an oxidation or carburization. Whereas, cold spray uses low temperature comparing with other thermal spray. Thermal energy is used for not melting powder but high kinetic energy of powder and plastic deformation during collision. Therefore, fuel such as oxygen-acetylene gas is not needed. It needs carrier gas, compressed air, nitrogen or helium, to increase kinetic energy of powder and move powder to substrate. Comparing cold spray with high velocity oxy fuel (HVOF), one of thermal spray, cold spray coating layer contains only WC and Co. One of other problem about WC is brittleness during coating. To improve deformability of WC, binder metal is added. For example, Co, Cr, Ni, Cu, Al, Fe or etc. Additionally, binder metal lowering melting temperature of composite powder increases coating properties. Among them, Co which is widely used as binder metal maintains mechanical properties like a hardness and improves corrosion properties. Therefore Co is not suitable for binder metal of WC coating. In contrast, Ni has better corrosion resistance to alkaline environment and makes lower melting temperature. Moreover, in a view of cold spray, FCC structure has better deformability than BCC or HCP, and BCC has lowest deformability. WC is BCC structure so it

  3. Spray-coated fluorine-free superhydrophobic coatings with easy repairability and applicability.

    Science.gov (United States)

    Wu, Weici; Wang, Xiaolong; Liu, Xinjie; Zhou, Feng

    2009-08-01

    The present paper reports a very simple and low-cost fluorine-free superhydrophobic coating prepared by spray-coating metal alkylcarboxylates, for example, Cu[CH(3)(CH(2))(10)COO](2), onto virtually any substrates. Superhydrophobicity with a static water contact angle of about 160 degrees and a sliding angle of 5 degrees was achieved from the proper precursor concentration. The advantages of the present approach include the cheap and fluorine-free raw materials, environmentally benign solvents, an industrial implementation method, and easy repairability and applicability so as to make a great application potential in practice. The hydrophobicity of coatings and the adhesion to water were found to be dependent on the surface morphology that was governed by the precursor concentrations from which coatings were prepared. The static wetting behavior of water droplets with different sizes gentlly deposited on the coatings was studied in more detail and correlated to theories, i.e., Wenzel's and Cassie's models. The results indicated that nanoribbon-textured coatings prepared from low precursor concentration (0.02 M) exhibited a transition from the metastable Cassie-Baxter state to the Wenzel state with increments in the droplet volume, and eventually droplets firmly stick to the surface even when the droplet was gently deposited on the surface. Surface coatings with dual roughness at both microscale and nanometer scale were formed as the concentration (0.04 M) was increased and conferred a stable Cassie state, even for increased droplet size and increased droplet deposit speed.

  4. In Vitro and In Vivo Evaluation of Zinc-Modified Ca–Si-Based Ceramic Coating for Bone Implants

    Science.gov (United States)

    Zheng, Xuebin; He, Dannong; Ye, Xiaojian; Wang, Meiyan

    2013-01-01

    The host response to calcium silicate ceramic coatings is not always favorable because of their high dissolution rates, leading to high pH within the surrounding physiological environment. Recently, a zinc-incorporated calcium silicate-based ceramic Ca2ZnSi2O7 coating, developed on a Ti-6Al-4V substrate using plasma-spray technology, was found to exhibit improved chemical stability and biocompatibility. This study aimed to investigate and compare the in vitro response of osteoblastic MC3T3-E1 cells cultured on Ca2ZnSi2O7 coating, CaSiO3 coating, and uncoated Ti-6Al-4V titanium control at cellular and molecular level. Our results showed Ca2ZnSi2O7 coating enhanced MC3T3-E1 cell attachment, proliferation, and differentiation compared to CaSiO3 coating and control. In addition, Ca2ZnSi2O7 coating increased mRNA levels of osteoblast-related genes (alkaline phosphatase, procollagen α1(I), osteocalcin), insulin-like growth factor-I (IGF-I), and transforming growth factor-β1 (TGF-β1). The in vivo osteoconductive properties of Ca2ZnSi2O7 coating, compared to CaSiO3 coating and control, was investigated using a rabbit femur defect model. Histological and histomorphometrical analysis demonstrated new bone formation in direct contact with the Ca2ZnSi2O7 coating surface in absence of fibrous tissue and higher bone-implant contact rate (BIC) in the Ca2ZnSi2O7 coating group, indicating better biocompatibility and faster osseointegration than CaSiO3 coated and control implants. These results indicate Ca2ZnSi2O7 coated implants have applications in bone tissue regeneration, since they are biocompatible and able to osseointegrate with host bone. PMID:23483914

  5. 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

  6. Sprayed and Spin-Coated Multilayer Antireflection Coating Films for Nonvacuum Processed Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Abdullah Uzum

    2017-01-01

    Full Text Available Using the simple and cost-effective methods, spin-coated ZrO2-polymer composite/spray-deposited TiO2-compact multilayer antireflection coating film was introduced. With a single TiO2-compact film on the surface of a crystalline silicon wafer, 5.3% average reflectance (the reflectance average between the wavelengths of 300 nm and 1100 nm was observed. Reflectance decreased further down to 3.3% after forming spin-coated ZrO2 on the spray-deposited TiO2-compact film. Silicon solar cells were fabricated using CZ-Si p-type wafers in three sets: (1 without antireflection coating (ARC layer, (2 with TiO2-compact ARC film, and (3 with ZrO2-polymer composite/TiO2-compact multilayer ARC film. Conversion efficiency of the cells improved by a factor of 0.8% (from 15.19% to 15.88% owing to the multilayer ARC. Jsc was improved further by 2 mA cm−2 (from 35.3 mA cm−2 to 37.2 mA cm−2 when compared with a single TiO2-compact ARC.

  7. Effects of Bond Coating on NiCrBSi-Mo Composite Functional Coating Properties in Plasma Spraying NiCrBSi-Mo/Ni Coating

    OpenAIRE

    DU Ji-yu; LI Fang-yi; LU Hai-yang; SHANG Jian-tong; LI Zhen

    2017-01-01

    Nickel-based bond coating and composite functional coating were sprayed on leaf blade steel material FV520B successively by using air plasma spraying system. NiCrBSi-Mo powder deposition rate, coating porosity, bonding strength and surface hardness were tested. The results indicate that, for the NiCrBSi-Mo/Ni coating, bond coating with 180-220μm thickness can improve NiCrBSi-Mo powder deposition rate while the surface coating with lower porosity, higher bonding strength and high hardness is p...

  8. Glass/ceramic coatings for implants

    Science.gov (United States)

    Tomsia, Antoni P [Pinole, CA; Saiz, Eduardo [Berkeley, CA; Gomez-Vega, Jose M [Nagoya, JP; Marshall, Sally J [Larkspur, CA; Marshall, Grayson W [Larkspur, CA

    2011-09-06

    Glass coatings on metals including Ti, Ti6A14V and CrCo were prepared for use as implants. The composition of the glasses was tailored to match the thermal expansion of the substrate metal. By controlling the firing atmosphere, time, and temperature, it was possible to control the reactivity between the glass and the alloy and to fabricate coatings (25-150 .mu.m thick) with excellent adhesion to the substrate. The optimum firing temperatures ranged between 800 and 840.degree. C. at times up to 1 min in air or 15 min in N.sub.2. The same basic technique was used to create multilayered coatings with concentration gradients of hydroxyapatite (HA) particles and SiO.sub.2.

  9. Biofouling of Cr-Nickel Spray Coated Films on Steel Surfaces

    International Nuclear Information System (INIS)

    Yoshida, Kento; Kanematsu, Hideyuki; Kuroda, Daisuke; Ikigai, Hajime; Kogo, Takeshi; Yokoyama, Seiji

    2012-01-01

    Nowadays, corrosion of metals brings us serious economic loss and it often reaches several percentage of GNP. Particularly the marine corrosion was serious and the counter measure was very hard to be established, since the number of factors is huge and complicated. One of the complicated factors in marine corrosion is biofouling. Biofouling was classified into two main categories, microfouling and macrofouling. The former is composed of biofilm formation mainly. Marine bacteria are attached to material surfaces, seeking for nutrition in oligotrophic environment and they excrete polysaccharide to form biofilm on metal surfaces. Then larger living matters are attached on the biofilms to develop biofouling on metal surfaces, which often lead loss and failures of metals in marine environments. From the viewpoint of corrosion protection and maintenance of marine structures, biofouling should be mitigated as much as possible. In this study, we applied spray coating to steels and investigated if chromium-nickel spray coating could mitigate the biofouling, being compared with the conventional aluminium-zinc spray coating in marine environments. The specimens used for this investigation are aluminium, zinc, aluminium-zinc, stacked chromium/nickel and those films were formed on carbon steel (JIS SS400). And the pores formed by spray coating were sealed by a commercial reagent for some specimens. All of those specimens were immersed into sea water located at Marina Kawage (854-3, Chisato, Tsu, Mie Prefecture) in Ise Bay for two weeks. The depth of the specimen was two meter from sea water surface and the distance was always kept constant, since they were suspended from the floating pier. The temperature in sea water changed from 10 to 15 degrees Celsius during the immersion test. The biofouling behavior was investigated by low vacuum SEM (Hitachi Miniscope TM1000) and X-ray fluorescent analysis. When the spray coated specimens with and without sealing agents were compared

  10. Biofouling of Cr-Nickel Spray Coated Films on Steel Surfaces

    Science.gov (United States)

    Yoshida, Kento; Kanematsu, Hideyuki; Kuroda, Daisuke; Ikigai, Hajime; Kogo, Takeshi; Yokoyama, Seiji

    2012-03-01

    Nowadays, corrosion of metals brings us serious economic loss and it often reaches several percentage of GNP. Particularly the marine corrosion was serious and the counter measure was very hard to be established, since the number of factors is huge and complicated. One of the complicated factors in marine corrosion is biofouling. Biofouling was classified into two main categories, microfouling and macrofouling. The former is composed of biofilm formation mainly. Marine bacteria are attached to material surfaces, seeking for nutrition in oligotrophic environment and they excrete polysaccharide to form biofilm on metal surfaces. Then larger living matters are attached on the biofilms to develop biofouling on metal surfaces, which often lead loss and failures of metals in marine environments. From the viewpoint of corrosion protection and maintenance of marine structures, biofouling should be mitigated as much as possible. In this study, we applied spray coating to steels and investigated if chromium-nickel spray coating could mitigate the biofouling, being compared with the conventional aluminium-zinc spray coating in marine environments. The specimens used for this investigation are aluminium, zinc, aluminium-zinc, stacked chromium/nickel and those films were formed on carbon steel (JIS SS400). And the pores formed by spray coating were sealed by a commercial reagent for some specimens. All of those specimens were immersed into sea water located at Marina Kawage (854-3, Chisato, Tsu, Mie Prefecture) in Ise Bay for two weeks. The depth of the specimen was two meter from sea water surface and the distance was always kept constant, since they were suspended from the floating pier. The temperature in sea water changed from 10 to 15 degrees Celsius during the immersion test. The biofouling behavior was investigated by low vacuum SEM (Hitachi Miniscope TM1000) and X-ray fluorescent analysis. When the spray coated specimens with and without sealing agents were compared

  11. An assessment of thermal spray coating technologies for high temperature corrosion protection

    International Nuclear Information System (INIS)

    Heath, G.R.; Heimgartner, P.; Gustafsson, S.; Irons, G.; Miller, R.

    1997-01-01

    The use of thermally sprayed coatings in combating high temperature corrosion continues to grow in the major industries of chemical, waste incineration, power generation and pulp and paper. This has been driven partially by the development of corrosion resistant alloys, improved knowledge and quality in the thermal spray industry and continued innovation in thermal spray equipment. There exists today an extensive range of thermal spray process options, often with the same alloy solution. In demanding corrosion applications it is not sufficient to just specify alloy and coating method. For the production of reliable coatings the whole coating production envelope needs to be considered, including alloy selection, spray parameters, surface preparation, base metal properties, heat input etc. Combustion, arc-wire, plasma, HVOF and spray+fuse techniques are reviewed and compared in terms of their strengths and limitations to provide cost-effective solutions for high temperature corrosion protection. Arc wire spraying, HP/HVOF and spray+fuse are emerging as the most promising techniques to optimise both coating properties and economic/practical aspects. (orig.)

  12. Using of sawing quartzite fine residual for obtaining ceramic coating

    International Nuclear Information System (INIS)

    Nobrega, L.F.P.M.; Souza, M.M.

    2016-01-01

    Quartzite is a metamorphic rock that is consisting mainly of quartz. In Paraiba there is a mining activity of this rock, in the region of Varzea and Junco do Serido especially where many wastes are created, including the sawing residue. The objective is to use the waste cited as the ceramic component coating mass, thereby replacing the quartz. Initially, the raw materials samples were taken and the chemical analysis was done of them. This passed the comminution process to achieve the required minimum particle size. After this, a formulation which added the residue in ceramic mass was made. The specimens were subjected to sintering and it was later made physical tests according to NBR 13818. The results show that the residue can replace the quartz ceramic mass successfully, but not as good as the original raw material. (author)

  13. Coating of waste containing ceramic granules

    International Nuclear Information System (INIS)

    Neumann, W.; Kofler, O.

    1979-01-01

    Simulated high-level waste granules produced by fluidized-bed calcination were overcoated by chemical vapor deposition (CVD) with pyrocarbon and nickel in laboratory-scale experiments. Successful development enables pyrocrbon deposition at temperatures of 600 to 800 0 K. The coated granules have excellent properties for long-term waste storage

  14. 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.

  15. The erosion performance of cold spray deposited metal matrix composite coatings with subsequent friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Peat, Tom, E-mail: tompeat12@gmail.com [Department of Mechanical & Aerospace Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ (United Kingdom); Galloway, Alexander; Toumpis, Athanasios [Department of Mechanical & Aerospace Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ (United Kingdom); McNutt, Philip [TWI Ltd., Granta Park, Cambridge CB21 6AL (United Kingdom); Iqbal, Naveed [TWI Technology Centre, Wallis Way, Catcliff, Rotherham, S60 5TZ (United Kingdom)

    2017-02-28

    Highlights: • WC-CoCr, Cr{sub 3}C{sub 2}-NiCr and Al{sub 2}O{sub 3} coatings were cold spray deposited on AA5083 and friction stir processed. • The SprayStirred WC-CoCr demonstrated a hardness increase of 100% over the cold sprayed coating. • As-deposited and SprayStirred coatings were examined under slurry erosion test conditions. • Mass and volume loss was measured following 20-min exposure to the slurry. • The WC-CoCr and Al2O3 demonstrated a reduction in volume loss of approx. 40% over the cold sprayed coating. - Abstract: This study forms an initial investigation into the development of SprayStir, an innovative processing technique for generating erosion resistant surface layers on a chosen substrate material. Tungsten carbide – cobalt chromium, chromium carbide – nickel chromium and aluminium oxide coatings were successfully cold spray deposited on AA5083 grade aluminium. In order to improve the deposition efficiency of the cold spray process, coatings were co-deposited with powdered AA5083 using a twin powder feed system that resulted in thick (>300 μm) composite coatings. The deposited coatings were subsequently friction stir processed to embed the particles in the substrate in order to generate a metal matrix composite (MMC) surface layer. The primary aim of this investigation was to examine the erosion performance of the SprayStirred surfaces and demonstrate the benefits of this novel process as a surface engineering technique. Volumetric analysis of the SprayStirred surfaces highlighted a drop of approx. 40% in the level of material loss when compared with the cold spray deposited coating prior to friction stir processing. Micro-hardness testing revealed that in the case of WC-CoCr reinforced coating, the hardness of the SprayStirred material exhibits an increase of approx. 540% over the unaltered substrate and 120% over the as-deposited composite coating. Microstructural examination demonstrated that the increase in the hardness of the

  16. 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

  17. On the Interplay Between Adhesion Strength and Tensile Properties of Thermal Spray Coated Laminates—Part I: High Velocity Thermal Spray Coatings

    Science.gov (United States)

    Luo, Xiaotao; Smith, Gregory M.; Sampath, Sanjay

    2018-02-01

    Adhesion of thermal spray (TS) coatings is an important system level property in coating design and application. Adhesive-based pull testing (ASTM C633) has long been used to evaluate coating/substrate bonding. However, this approach is not always suitable for high velocity spray coatings, for example, where adhesion strengths are routinely greater than the strength of the adhesive bonding agent used in the testing. In this work, a new approach has been proposed to evaluate the adhesion of TS coatings. A systematic investigation of the effects of substrate roughness on both the uniaxial tensile yield strength and traditional bond pull adhesive strength of HVOF Ni and Ni-5wt.%Al, as well as cold-sprayed Ni-coated laminates revealed a strong correlation between these two test methodologies for the respective materials and processes. This approach allows measurement of the adhesion response even where the adhesive method is not applicable, overcoming many of the issues in the traditional ASTM C633. Analysis of cracking patterns of the coatings after 10.5% strain was used to assess the adhesion and cohesion properties. The mechanisms which determine the load transfer between the substrate and the coating are also briefly discussed.

  18. Spray-coating process in preparing PTFE-PPS composite super-hydrophobic coating

    Directory of Open Access Journals (Sweden)

    Rui Weng

    2014-03-01

    Full Text Available In order to improve the performance of a liquid-floated rotor micro-gyroscope, the resistance of the moving interface between the rotor and the floating liquid must be reduced. Hydrophobic treatment can reduce the frictional resistance between such interfaces, therefore we proposed a method to prepare a poly-tetrafluoroethylene (PTFE-poly-phenylene sulphide (PPS composite super-hydrophobic coating, based on a spraying process. This method can quickly prepare a continuous, uniform PTFE-PPS composite super-hydrophobic surface on a 2J85 material. This method can be divided into three steps, namely: pre-treatment; chemical etching; and spraying. The total time for this is around three hours. When the PTFE concentration is 4%, the average contact angle of the hydrophobic coating surface is 158°. If silicon dioxide nanoparticles are added, this can further improve the adhesion and mechanical strength of the super-hydrophobic composite coating. The maximum average contact angle can reach as high as 164° when the mass fraction of PTFE, PPS and silicon dioxide is 1:1:1.

  19. 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

  20. Spin coating of passive electroactive ceramic devices

    CERN Document Server

    Carson, E

    2001-01-01

    ferrite inductor paste materials as powders before and after thermal processing in the range 150, 500, 850 and 1150 deg C indicates a high carbon content in the surface region. By comparison, spin coated layers of each of these systems on alumina substrates before and after heating in the same temperature range as that used for the residual powders, showed a marked decrease in the carbon content in the surface region. In addition, deposition of the dielectric onto a ferrite surface which itself had been spin coated on alumina indicated no merging of the different layers. Thermal processing of this bi-layer system up to 850 deg C provides evidence that there may be some channelling of the bismuth photoelectrons through suitably sized pores in the dielectric layer. The commercial doctor blading method has also been used to produce dielectric layers and these are shown to be somewhat different to those produced by spin coating. In particular, the doctor bladed material contains more carbonaceous material in the ...

  1. Ceramic wash-coat for catalyst support

    Science.gov (United States)

    Kulkarni, Anand A.; Subramanian, Ramesh; Sabol, Stephen M.

    2012-08-14

    A wash-coat (16) for use as a support for an active catalyst species (18) and a catalytic combustor component (10) incorporating such wash-coat. The wash-coat is a solid solution of alumina or alumina-based material (Al.sub.2O.sub.3-0-3 wt % La.sub.2O.sub.3) and a further oxide exhibiting a coefficient of thermal expansion that is lower than that exhibited by alumina. The further oxide may be silicon dioxide (2-30 wt % SiO.sub.2), zirconia silicate (2-30 wt % ZrSiO.sub.4), neodymium oxide (0-4 wt %), titania (Al.sub.2O.sub.3-3-40% TiO.sub.2) or alumina-based magnesium aluminate spinel (Al.sub.2O.sub.3-25 wt % MgO) in various embodiments. The active catalyst species may be palladium and a second metal in a concentration of 10-50% of the concentration of the palladium.

  2. Replacement of Chromium Electroplating on Gas Turbine Engine Components Using Thermal Spray Coatings

    National Research Council Canada - National Science Library

    Sartwell, Bruce D; Legg, Keith O; Schell, Jerry; Bondaruk, Bob; Alford, Charles; Natishan, Paul; Lawrence, Steven; Shubert, Gary; Bretz, Philip; Kaltenhauser, Anne

    2005-01-01

    .... This document constitutes the final report on a project to qualify high-velocity oxygen-fuel (HVOF) and plasma thermal spray coatings as a replacement for hard chrome plating on gas turbine engine components...

  3. An Investigation of Mechanisms in Bonding and Failure of Thermal Spray Coatings

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed project is an investigation of the mechanisms in bonding and failure of thermal spray coatings. The objectives for this project are as follows:...

  4. The Properties of Arc-Sprayed Aluminum Coatings on Armor-Grade Steel

    Directory of Open Access Journals (Sweden)

    Marcin Adamiak

    2018-02-01

    Full Text Available This article presents the results of an examination of the properties of arc-sprayed aluminum on alloyed armor-grade steel. Thermal arc spraying was conducted with a EuTronic Arc Spray 4 wire arc sprayer. Aluminum wire 1.6 mm in diameter was used to produce dense, abrasion- and erosion-resistant coatings approx. 1.0 mm thick with and without nickel/5% aluminum-buffered subcoating. Aluminum coatings were characterized in accordance with ASTM G 65-00 abrasion resistance test, ASTM G 76-95 erosion resistance tests, ASTM C 633-01 adhesion strength, HV0.1 hardness tests and metallographic analyses. Results demonstrate properties of arc-sprayed aluminum and aluminum-nickel material coatings that are especially promising in industrial applications where erosion-, abrasion- and corrosion-resistant coating properties are required.

  5. Characterization for Ceramic-coated magnets using E-beam and thermal annealing methods

    International Nuclear Information System (INIS)

    Kim, Hyug Jong; Kim, Hee Gyu; Kang, In Gu; Kim, Min Wan; Yang, Ki Ho; Lee, Byung Cheol; Choi, Byung Ho

    2009-01-01

    Hard magnet was usually used by coating SiO 2 ceramic thick films followed by the thermal annealing process. In this work, the alternative annealing process for NdFeB magnets using e-beam sources(1∼2 MeV, 50∼400 kGy) was investigated. NdFeB magnets was coated with ceramic thick films using the spray method. The optimal annealing parameter for e-beam source reveals to be 1 MeV and 300 kGy. The sample prepared at 1 MeV and 300 kGy was characterized by the analysis of the surface morphology, film hardness, adhesion and chemical stability. The mechanical property of thick film, especially film hardness, is better than that of thermal annealed samples at 180 .deg. C. As a result, e-beam annealing process will be one of candidate and attractive heat treatment process. In future, manufacturing process will be carried out in cooperation with the magnet company

  6. Warm spraying-a novel coating process based on high-velocity impact of solid particles.

    Science.gov (United States)

    Kuroda, Seiji; Kawakita, Jin; Watanabe, Makoto; Katanoda, Hiroshi

    2008-07-01

    In recent years, coating processes based on the impact of high-velocity solid particles such as cold spraying and aerosol deposition have been developed and attracting much industrial attention. A novel coating process called 'warm spraying' has been developed, in which coatings are formed by the high-velocity impact of solid powder particles heated to appropriate temperatures below the melting point of the powder material. The advantages of such process are as follows: (1) the critical velocity needed to form a coating can be significantly lowered by heating, (2) the degradation of feedstock powder such as oxidation can be significantly controlled compared with conventional thermal spraying where powder is molten, and (3) various coating structures can be realized from porous to dense ones by controlling the temperature and velocity of the particles. The principles and characteristics of this new process are discussed in light of other existing spray processes such as high-velocity oxy-fuel spraying and cold spraying. The gas dynamics of particle heating and acceleration by the spraying apparatus as well as the high-velocity impact phenomena of powder particles are discussed in detail. Several examples of depositing heat sensitive materials such as titanium, metallic glass, WC-Co cermet and polymers are described with potential industrial applications.

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

    Science.gov (United States)

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

    2002-01-01

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

  8. Development of an oxidation resistant glass-ceramic composite coating on Ti-47Al-2Cr-2Nb alloy

    Science.gov (United States)

    Li, Wenbo; Zhu, Shenglong; Chen, Minghui; Wang, Cheng; Wang, Fuhui

    2014-02-01

    Three glass-ceramic composite coatings were prepared on Ti-47Al-2Cr-2Nb alloy by air spraying technique and subsequent firing. The aim of this work is to study the reactions between glass matrix and inclusions and their effects on the oxidation resistance of the glass-ceramic composite coating. The powders of alumina, quartz, or both were added into the aqueous solution of potassium silicate (ASPS) to form slurries used as the starting materials for the composite coatings. The coating formed from an ASPS-alumina slurry was porous, because the reaction between alumina and potassium silicate glass resulted in the formation of leucite (KAlSi2O6), consuming substantive glass phase and hindering the densification of the composite coating. Cracks were observed in the coating prepared from an ASPS-quartz slurry due to the larger volume shrinkage of the coating than that of the alloy. In contrast, an intact and dense SiO2-Al2O3-glass coating was successfully prepared from an ASPS-alumina-silica slurry. The oxidation behavior of the SiO2-Al2O3-glass composite coating on Ti-47Al-2Cr-2Nb alloy was studied at 900 °C. The SiO2-Al2O3-glass composite coating acted as an oxygen diffusion barrier, and prevented the inward diffusion of the oxygen from the air to the coating/alloy interface, therefore, decreasing the oxidation rate of the Ti-47Al-2Cr-2Nb alloy significantly.

  9. [The antibacterial activity of plasma sprayed silver-containing hydroxyapatite coatings].

    Science.gov (United States)

    Wang, Yu-hua; Zhu, Zi-yuan; Zhang, Fu-qiang; Zhu, Cai-lian; Li, Ming-yu; Zheng, Xue-bin

    2009-06-01

    To study the antibacterial activity of plasma sprayed silver-containing hydroxyapative(HA) coatings. Silver-containing HA coatings were prepared on titanium substrated by vacuum plasma spraying (VPS). The samples were divided into 4 groups according to weight percent of the antimicrobial: group HA0 (0%),group HA1 (1%),group HA3 (3%) and group HA5 (5%). The antimicrobial properties against Streptococcus mutans were assayed with the pellicle-sticking method. When the weight percent of the silver was >3%, the silver-containing HA coatings exhibited significant anti-bacterial effects against Streptococcus mutans. The silver-containing HA coating has good inhibitory effect on Streptococcus mutans.

  10. Sealing of thermally-sprayed stainless steel coatings against corrosion using nickel electroplating technique

    Directory of Open Access Journals (Sweden)

    Hathaipat Koiprasert

    2007-07-01

    Full Text Available Electric arc spraying (EAS is one of the thermal spray techniques used for restoration and to providecorrosion resistance. It can be utilized to build up coatings to thicknesses of several millimeters, It is easy to use on-site. Most importantly, the cost of this technique is lower than other thermal spraying techniques thatmay be suitable for part restoration. A major disadvantage associated with the electric arc sprayed coating is its high porosity, which can be as high as 3-8% making it not appropriate for use in immersion condition. This work was carried out around the idea of using electroplating to seal off the pore of the EAS coating, with an aim to improve the corrosion resistance of the coating in immersion condition. This research compared the corrosion behavior of a stainless steel 316 electric arc sprayed coating in 2M NaOH solution at 25oC. It was found that the Ni plating used as sealant can improve the corrosion resistance of the EAS coating. Furthermore, the smoothened and plated stainless steel 316 coating has a better corrosion resistance than the plated EAS coating that was not ground to smoothen the surface before plating.

  11. Demonstration of Thermally Sprayed Metal and Polymer Coatings for Steel Structures at Fort Bragg, NC

    Science.gov (United States)

    2017-09-01

    demonstrated, the flame-sprayed polyole- fin coating is too costly for use on large steel structures. Guidance docu- ments are identified to help make...the feedstock material, the thermal-spray process and application parameters, and the post-treat- ment of the applied coating. An 85% zinc and 15...thickness (85/15 plus topcoat) was measured by gauge for compliance with project requirements. Total thickness measure- ments indicated that the

  12. Equipment and technologies of air-plasma spraying of functional coatings

    Directory of Open Access Journals (Sweden)

    Kuzmin Viktor

    2017-01-01

    Full Text Available This article presents a short description of the DC plasma torch "PNK-50" structural features (ITAM SB RAS, Novosibirsk used for spraying of functional coatings with powder materials as well as gives the results of thermophysical and technological studies of spraying regimes. We present preliminary results of the plasma torch supersonic modification development and the results of industrial approbation of the plasma torch and of multi-purposes functional coatings deposition processes.

  13. Cold spray of metal-polymer composite coatings onto carbon fiber-reinforced polymer (CFRP)

    OpenAIRE

    Bortolussi, Vincent; Borit, François; Chesnaud, Anthony; Jeandin, Michel; Faessel, Matthieu; Figliuzzi, Bruno; Willot, François; Roche, K.; Surdon, G.

    2016-01-01

    International audience; The growing use of Polymer-Matrix Composite (PMC) materials within transport industry raises new security concerns, especially those due to lightning. To protect these electrically insulating materials, conductive coatings can be applied. Due to the high level of required properties, cold spray is believed to be an effective way to achieve these coatings. Recent studies showed that obstacles remained to be overcome when cold spraying metallic particles onto Carbon Fibe...

  14. 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)

  15. Microstructure and performance of titanium oxide coatings sprayed by oxygen-acetylene flame

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Štengl, Václav; Zahálka, F.; Murafa, Nataliya

    2011-01-01

    Roč. 10, č. 3 (2011), s. 403-407 ISSN 1474-905X R&D Projects: GA AV ČR IAAX00430803 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z40320502 Keywords : Plasma spraying * flame spraying * photocatalysis * TiO2 Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.584, year: 2011

  16. Microstructural inhomogeneity in plasma-sprayed hydroxyapatite coatings and effect of post-heat treatment

    International Nuclear Information System (INIS)

    Lu Yupeng; Xiao Guiyong; Li Shitong; Sun Ruixue; Li Musen

    2006-01-01

    The microstructural inhomogeneity in the plasma-sprayed hydroxyapatite (HA) coatings was characterized by using electron probe microanalyser (EPMA). A simple and artful method was developed to detect the interface characteristics. All the samples for observation were ground and polished along the direction parallel to the coating surfaces. The BSE images directly and clearly showed the inhomogeneity in the as-sprayed coatings with the amorphous regions being bright gray and crystalline regions being dark gray. X-ray diffractometer (XRD) patterns indicated that after immersion in deionized water for 20 days, bone-like apatite and α-Ca 2 P 2 O 7 precipitated on the polished surfaces of the as-sprayed HA coatings. The post-heat treatment could eliminate the microstructural inhomogeneity in the coatings. Only β-Ca 2 P 2 O 7 precipitated on the surfaces of the heat-treated HA coatings. The immersed samples were re-polished till tiny substrate was bared to investigate the effect of immersion on interface. It was shown that the immersion decreased the cohesive strength of the as-sprayed coatings. There were more and broader cracks in the splats that came into contact with the substrate and amorphous phase increased toward the coating-substrate interface. Post-heat treatment was proved to reduce the peeling off of coating during re-polishing operation. It was proposed that the distributions of amorphous phase and cracks in as-sprayed coatings are detrimental to coating properties and should be modified through improving the plasma spraying processing

  17. Microstructural inhomogeneity in plasma-sprayed hydroxyapatite coatings and effect of post-heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Lu Yupeng [School of Materials Science and Engineering, South Campus of Shandong University, 73 Jingshi Road, Ji Nan 250062 (China)]. E-mail: Biosdu@sdu.edu.cn; Xiao Guiyong [School of Materials Science and Engineering, South Campus of Shandong University, 73 Jingshi Road, Ji Nan 250062 (China); Li Shitong [School of Materials Science and Engineering, South Campus of Shandong University, 73 Jingshi Road, Ji Nan 250062 (China); Sun Ruixue [School of Materials Science and Engineering, South Campus of Shandong University, 73 Jingshi Road, Ji Nan 250062 (China); Li Musen [School of Materials Science and Engineering, South Campus of Shandong University, 73 Jingshi Road, Ji Nan 250062 (China)

    2006-01-15

    The microstructural inhomogeneity in the plasma-sprayed hydroxyapatite (HA) coatings was characterized by using electron probe microanalyser (EPMA). A simple and artful method was developed to detect the interface characteristics. All the samples for observation were ground and polished along the direction parallel to the coating surfaces. The BSE images directly and clearly showed the inhomogeneity in the as-sprayed coatings with the amorphous regions being bright gray and crystalline regions being dark gray. X-ray diffractometer (XRD) patterns indicated that after immersion in deionized water for 20 days, bone-like apatite and {alpha}-Ca{sub 2}P{sub 2}O{sub 7} precipitated on the polished surfaces of the as-sprayed HA coatings. The post-heat treatment could eliminate the microstructural inhomogeneity in the coatings. Only {beta}-Ca{sub 2}P{sub 2}O{sub 7} precipitated on the surfaces of the heat-treated HA coatings. The immersed samples were re-polished till tiny substrate was bared to investigate the effect of immersion on interface. It was shown that the immersion decreased the cohesive strength of the as-sprayed coatings. There were more and broader cracks in the splats that came into contact with the substrate and amorphous phase increased toward the coating-substrate interface. Post-heat treatment was proved to reduce the peeling off of coating during re-polishing operation. It was proposed that the distributions of amorphous phase and cracks in as-sprayed coatings are detrimental to coating properties and should be modified through improving the plasma spraying processing.

  18. 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)

  19. On the Interplay Between Adhesion Strength and Tensile Properties of Thermal Spray Coated Laminates—Part II: Low-Velocity Thermal Spray Coatings

    Science.gov (United States)

    Luo, Xiaotao; Smith, Gregory M.; Sampath, Sanjay

    2018-02-01

    In this two-part study, uniaxial tensile testing was used to evaluate coating/substrate bonding and compared with traditional ASTM C633 bond pull test results for thermal spray (TS) coated steel laminates. In Part I, the rationale, methodology, and applicability of the test to high-velocity TS coatings were demonstrated. In this Part II, the method was investigated for low-velocity TS processes (air plasma spray and arc spray) on equivalent materials. Ni and Ni-5wt.%Al coatings were deposited on steel substrates with three different roughness levels and tested using both uniaxial tensile and ASTM C633 methods. The results indicate the uniaxial tensile approach provides useful information about the nature of the coating/substrate bonding and goes beyond the traditional bond pull test in providing insightful information on the load sharing processes across the interface. Additionally, this proposed methodology alleviates some of the longstanding shortcomings and potentially reduces error associated with the traditional ASTM C633 test. The mechanisms governing the load transfer between the substrate and the coating were investigated, and the influence of Al in the coating material evaluated.

  20. Development of Bioactive Ceramic Coating on Titanium Alloy substrate for Biomedical Application Using Dip Coating Method

    Science.gov (United States)

    Asmawi, R.; Ibrahim, M. H. I.; Amin, A. M.; Mustafa, N.; Noranai, Z.

    2017-08-01

    Bioactive apatite, such as hydroxyapatite ceramic (HA), [Ca10(PO4)6(OH)2] has been extensively investigated for biomedical applications due to its excellent biocompatibility and tissue bioactivity properties. Its bioactivity provides direct bonding to the bone tissue. Because of its similarity in chemical composition to the inorganic matrix of bone, HA is widely used as implant materials for bone. Unfortunately, because of its poor mechanical properties,. this bioactive material is not suitable for load bearing applications. In this study, by the assistance of dip-coating technique, HA coatings were deposited on titanium alloy substrates by employing hydrothermal derived HA powder. The produced coatings then were oven-dried at 130°C for 1 hour and calcined at various temperature over the range of 200-800°C for 1 hour. XRD measurement showed that HA was the only phase present in the coatings. However coatings calcined at 800°C comprised a mixture of HA and tri-calcium phosphate (TCP). FTIR measurement showed the existence of hydroxyl, phosphate, and carbonate bands. PO4 - band became sharper and narrower with the increased of calcination temperature. FESEM observation showed that the coating is polycrystalline with individual particles of nano to submicron size and has an average particle size of 35 nm. The thickness of the coating are direcly propotional with the viscosity of coating slurry. It was shown that the more viscous coating slurry would produce a thicker ceramic coating. Mechanical properties of the coating were measured in term of adhesion strength using a Micro Materials Nano Test microscratch testing machine. The result revealed that the coating had a good adhesion to the titanium alloy substrate.

  1. 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.

  2. Development of Copper Canister through Cold Sprayed Coating Method

    International Nuclear Information System (INIS)

    Lee, Min Soo; Choi, Jong Won; Choi, Heui Joo; Lee, Jong Youl; Jeong, Jong Tae; Kim, Sung Ki; Cho, Dong Keun

    2007-12-01

    General thickness of a copper canister is 5 cm for a underground disposal application. The lower limit of a thickness is determined by a forging technology. But many experts in this area agrees that the thickness 1 cm is enough at the underground disposal for the life time of 1,000,000 years. Thus new technology is suggested for the making 1 cm thickness copper canister, that is a cold spray coating method(CSC). In this report, the CSC is examined and the technical possibility for making copper canister is measured. The overview of CSC and its characteristics are discussed. Various copper particles for the CSC are analyzed and the formed coating layers are examined to find their porosity and uniformity. A Tafa copper particle and Chang-sung copper particle are selected for making 1 cm thick test specimen. Using the CSC specimens, tensile test and XRD analysis are performed. As a corrosion evaluation, a electrochemical test such as a polarization test is done, together with humid corrosion test and chloric acid immersion test. Through the corrosion tests, it is tried to confirm that the CSC is valuable method for making a copper canister. Consequently, it is confirmed that the CSC method is very usful for making 1 cm thick copper canister. the porosity of CSC layer is very low at 0.3 in case of Tafa copper layer. In corrosion tests, the CSC layers are very stable in active environments. It is hard to say that the difference of processing method but the purity of copper is important for the corrosion rate evaluation. The CSC method is very effective method for making 1 cm thick copper canister, It is hoped that the CSC method is applied in a HLW underground disposal system in the future

  3. Development of Copper Canister through Cold Sprayed Coating Method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Soo; Choi, Jong Won; Choi, Heui Joo; Lee, Jong Youl; Jeong, Jong Tae; Kim, Sung Ki; Cho, Dong Keun

    2007-12-15

    General thickness of a copper canister is 5 cm for a underground disposal application. The lower limit of a thickness is determined by a forging technology. But many experts in this area agrees that the thickness 1 cm is enough at the underground disposal for the life time of 1,000,000 years. Thus new technology is suggested for the making 1 cm thickness copper canister, that is a cold spray coating method(CSC). In this report, the CSC is examined and the technical possibility for making copper canister is measured. The overview of CSC and its characteristics are discussed. Various copper particles for the CSC are analyzed and the formed coating layers are examined to find their porosity and uniformity. A Tafa copper particle and Chang-sung copper particle are selected for making 1 cm thick test specimen. Using the CSC specimens, tensile test and XRD analysis are performed. As a corrosion evaluation, a electrochemical test such as a polarization test is done, together with humid corrosion test and chloric acid immersion test. Through the corrosion tests, it is tried to confirm that the CSC is valuable method for making a copper canister. Consequently, it is confirmed that the CSC method is very usful for making 1 cm thick copper canister. the porosity of CSC layer is very low at 0.3 in case of Tafa copper layer. In corrosion tests, the CSC layers are very stable in active environments. It is hard to say that the difference of processing method but the purity of copper is important for the corrosion rate evaluation. The CSC method is very effective method for making 1 cm thick copper canister, It is hoped that the CSC method is applied in a HLW underground disposal system in the future.

  4. One-step spray-coating process for the fabrication of colorful superhydrophobic coatings with excellent corrosion resistance.

    Science.gov (United States)

    Li, Jian; Wu, Runni; Jing, Zhijiao; Yan, Long; Zha, Fei; Lei, Ziqiang

    2015-10-06

    A simple method was used to generate colorful hydrophobic stearate particles via chemical reactions between inorganic salts and sodium stearate. Colored self-cleaning superhydrophobic coatings were prepared through a facile one-step spray-coating process by spraying the stearate particle suspensions onto stainless steel substrates. Furthermore, the colorful superhydrophobic coating maintains excellent chemical stability under both harsh acidic and alkaline circumstances. After being immersed in a 3.5 wt % NaCl aqueous solution for 1 month, the as-prepared coatings remained superhydrophobic; however, they lost their self-cleaning property with a sliding angle of about 46 ± 3°. The corrosion behavior of the superhydrophobic coatings on the Al substrate was characterized by the polarization curve and electrochemical impedance spectroscopy (EIS). The electrochemical corrosion test results indicated that the superhydrophobic coatings possessed excellent corrosion resistance, which could supply efficient and long-term preservation for the bare Al substrate.

  5. Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

    Energy Technology Data Exchange (ETDEWEB)

    Amir, N., E-mail: norlailiamir@petronas.com.my; Othman, W. M. S. W., E-mail: wamosa@gmail.com; Ahmad, F., E-mail: faizahmad@petronas.com.my [Mechanical Engineering Department, Universiti Teknologi PETRONAS Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2015-07-22

    This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

  6. Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

    Science.gov (United States)

    Amir, N.; Othman, W. M. S. W.; Ahmad, F.

    2015-07-01

    This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

  7. Residual stress in sprayed Ni+5%Al coatings determined by neutron diffraction

    CERN Document Server

    Matejicek, J; Gnaeupel-Herold, T; Prask, H J

    2002-01-01

    Coatings of nickel-based alloys are used in numerous high-performance applications. Their properties and lifetimes are influenced by factors such as residual stress. Neutron diffraction is a powerful tool for nondestructive residual stress determination. In this study, through-thickness residual stress profiles in Ni+5%Al coatings on steel substrates were determined. Two examples of significantly different spraying techniques - plasma spraying and cold spraying - are highlighted. Different stress-generation mechanisms are discussed with respect to process parameters and material properties. (orig.)

  8. Mechanical Performance of Cold-Sprayed A357 Aluminum Alloy Coatings for Repair and Additive Manufacturing

    Science.gov (United States)

    Petráčková, K.; Kondás, J.; Guagliano, M.

    2017-12-01

    Cold-sprayed coatings made of A357 aluminum alloy, a casting alloy widely used in aerospace, underwent set of standard tests as well as newly developed fatigue test to gain an information about potential of cold spray for repair and additive manufacturing of loaded parts. With optimal spray parameters, coating deposition on substrate with smooth surface resulted in relatively good bonding, which can be further improved by application of grit blasting on substrate's surface. However, no enhancement of adhesion was obtained for shot-peened surface. Process temperature, which was set either to 450 or 550 °C, was shown to have an effect on adhesion and cohesion strength, but it does not influence residual stress in the coating. To assess cold spray perspectives for additive manufacturing, flat tensile specimens were machined from coating and tested in as-sprayed and heat-treated (solution treatment and aging) condition. Tensile properties of the coating after the treatment correspond to properties of the cast A357-T61 aluminum alloy. Finally, fatigue specimen was proposed to test overall performance of the coating and coating's fatigue limit is compared to the results obtained on cast A357-T61 aluminum alloy.

  9. Microstructural Evaluation of Suspension Thermally Sprayed WC-Co Nanocomposite Coatings

    Science.gov (United States)

    Ahmed, R.; Faisal, N. H.; Ali, O.; Al-Anazi, Nayef M.; Al-Mutairi, S.; Mamour, S.; Polychroniadis, E. K.; Goosen, M. F. A.

    Microstructural and sliding wear evaluations of nanostructured coatings deposited by Suspension High Velocity Oxy-Fuel (S-HVOF) spraying were conducted in as-sprayed and HIPed (Hot Isostatically Pressed) conditions. S-HVOF coatings were nanostructured via ball milling of the WC-12Co start powder, and deposited via an aqueous based suspension using modified HVOF (TopGun) spraying. Microstructural evaluations of these hardmetal coatings included TEM (Transmission Electron Microscopy), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Sliding wear tests were conducted using a ball-on-flat test rig. Results indicated that nanostructured features inherited from the start powder in S-HVOF spraying were retained in the resulting coatings. The decarburisation of WC due to a higher surface area to volume ratio was also observed in the S-HVOF coatings. Nanostructured and amorphous phases caused by the high cooling rates during thermal spraying crystallized into complex eta-phases after the HIPing treatment. Sliding wear performance indicated that the coating wear was lower for the HIPed coatings.

  10. Current Issues with Environmental Barrier Coatings for Ceramics and Ceramic Composites

    Science.gov (United States)

    Lee, Kang N.

    2004-01-01

    The environmental barrier coating (EBC) for SiC/SiC ceramic matrix composites and Si3N4 ceramics is an emerging field as the application of silicon-based ceramics in the gas turbine engine hot section is on the horizon, both for aero and industrial gas turbines. EBC is an enabling technology for silicon-based ceramics because these materials without an EBC cannot be used in combustion environments due to rapid surface recession. Significant progress in EBC development has been made during the last decade through various government-sponsored programs. Current EBCs are based on silicon, mullite (3Al2O3-2SiO2) and BSAS (barium strontium aluminum silicate with celsian structure). Volatility of BSAS, BSAS-silica chemical reaction, and low melting point of silicon limit temperature capability of current EBCs to about 1350 C for long-term applications. There is a need for higher temperature EBCs as the temperature capability of silicon-based ceramics continue to increase. Therefore, research is underway to develop EBCs with improved temperature capability compared to current EBCs. The current status and issues with the advanced EBC development efforts will be discussed.

  11. Plasma-sprayed boron carbide coatings for first-wall protection

    Science.gov (United States)

    van der Laan, J. G.; Schnedecker, G.; van Osch, E. V.; Duwe, R.; Linke, J.

    1994-08-01

    Plasma-sprayed boron carbide coatings have been manufactured by different suppliers onto substrates of type 316L stainless steel. The coating thickness ranges from 0.3 to 2.0 mm. The larger thicknesses could only be achieved by application of an adaptive or gradient bond-layer between substrate and the boron carbide top coating. Measurements of the thermal diffusivity of coating materials are reported. Several high heat flux facilities have been used to study the thermal shock and erosion behaviour of the coated samples. A supporting numerical analysis of the thermal behaviour of the coating under normal and off-normal heat loads is presented, focussing on the differences between electron beam and laser beam tests due to volumetric energy deposition. Some aspects of the applicability of plasma sprayed B 4C coatings for first-wall protection in a next step device are discussed.

  12. Ceramic Coatings for Clad (The C3 Project): Advanced Accident-Tolerant Ceramic Coatings for Zr-Alloy Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Sickafus, Kurt E. [Univ. of Tennessee, Knoxville, TN (United States); Wirth, Brian [Univ. of Tennessee, Knoxville, TN (United States); Miller, Larry [Univ. of Tennessee, Knoxville, TN (United States); Weber, Bill [Univ. of Tennessee, Knoxville, TN (United States); Zhang, Yanwen [Univ. of Tennessee, Knoxville, TN (United States); Patel, Maulik [Univ. of Tennessee, Knoxville, TN (United States); Motta, Arthur [Pennsylvania State Univ., University Park, PA (United States); Wolfe, Doug [Pennsylvania State Univ., University Park, PA (United States); Fratoni, Max [Univ. of California, Berkeley, CA (United States); Raj, Rishi [Univ. of Colorado, Boulder, CO (United States); Plunkett, Kenneth [Univ. of Colorado, Boulder, CO (United States); Was, Gary [Univ. of Michigan, Ann Arbor, MI (United States); Hollis, Kendall [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nelson, Andy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stanek, Chris [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Comstock, Robert [Westinghouse Electric Corporation, Pittsburgh, PA (United States); Partezana, Jonna [Westinghouse Electric Corporation, Pittsburgh, PA (United States); Whittle, Karl [Univ. of Sheffield (United Kingdom); Preuss, Michael [Univ. of Manchester (United Kingdom); Withers, Philip [Univ. of Manchester (United Kingdom); Wilkinson, Angus [Univ. of Oxford (United Kingdom); Donnelly, Stephen [Univ. of Huddersfield (United Kingdom); Riley, Daniel [Australian Nuclear Science and Technology Organisation, Syndney (Australia)

    2017-02-14

    The goal of this NEUP-IRP project is to develop a fuel concept based on an advanced ceramic coating for Zr-alloy cladding. The coated cladding must exhibit demonstrably improved performance compared to conventional Zr-alloy clad in the following respects: During normal service, the ceramic coating should decrease cladding oxidation and hydrogen pickup (the latter leads to hydriding and embrittlement). During a reactor transient (e.g., a loss of coolant accident), the ceramic coating must minimize or at least significantly delay oxidation of the Zr-alloy cladding, thus reducing the amount of hydrogen generated and the oxygen ingress into the cladding. The specific objectives of this project are as follows: To produce durable ceramic coatings on Zr-alloy clad using two possible routes: (i) MAX phase ceramic coatings or similar nitride or carbide coatings; and (ii) graded interface architecture (multilayer) ceramic coatings, using, for instance, an oxide such as yttria-stabilized zirconia (YSZ) as the outer protective layer. To characterize the structural and physical properties of the coated clad samples produced in 1. above, especially the corrosion properties under simulated normal and transient reactor operating conditions. To perform computational analyses to assess the effects of such coatings on fuel performance and reactor neutronics, and to perform fuel cycle analyses to assess the economic viability of modifying conventional Zr-alloy cladding with ceramic coatings. This project meets a number of the goals outlined in the NEUP-IRP call for proposals, including: Improve the fuel/cladding system through innovative designs (e.g. coatings/liners for zirconium-based cladding) Reduce or eliminate hydrogen generation Increase resistance to bulk steam oxidation Achievement of our goals and objectives, as defined above, will lead to safer light-water reactor (LWR) nuclear fuel assemblies, due to improved cladding properties and built-in accident resistance, as well as

  13. Lubrication And Wear Of Hot Ceramics

    Science.gov (United States)

    Sliney, H. E.; Jacobson, T. P.; Deadmore, D.; Miyoshi, K.

    1988-01-01

    Report presents results of experiments on tribological properties of ceramics. Describes friction and wear characteristics of some ceramics under consideration for use in gas turbines, diesel engines, and Stirling engines. Discusses formulation of composite plasma-sprayed ceramics containing solid lubricant additives, and data for carbide- and oxide-based composite coatings for use at temperatures up to at least 900 degree C.

  14. Surface silver-doping of biocompatible glasses to induce antibacterial properties. Part II: Plasma sprayed glass-coatings.

    Science.gov (United States)

    Miola, M; Ferraris, S; Di Nunzio, S; Robotti, P F; Bianchi, G; Fucale, G; Maina, G; Cannas, M; Gatti, S; Massé, A; Vitale Brovarone, C; Verné, E

    2009-03-01

    A 57% SiO(2), 3% Al(2)O(3), 34% CaO and 6% Na(2)O glass (SCNA) has been produced in form of powders and deposited by plasma spray on titanium alloy and stainless steel substrates. The obtained coatings have been subjected to a patented ion-exchange treatment to introduce silver ions in the surface inducing an antibacterial behavior. Silver surface-enriched samples have been characterized by means of X-ray diffraction, SEM observation, EDS analysis, in vitro bioactivity tests, leaching tests by GFAAS (graphite furnace atomic adsorption spectroscopy) analyses, cells adhesion and proliferation, and antibacterial tests using Staphylococcus Aureus strain. In vitro tests results showed that the modified samples acquired an antimicrobial action against tested bacteria maintaining unaffected the biocompatibility of the glass. Furthermore the ion-exchange treatment can be successfully applied to glass-coated samples without affecting the properties of the coatings; the simplicity and reproducibility of the method make it suitable for glass or glass-ceramic coatings of different composition in order to produce coated devices for bone healing and/or prostheses, able to reduce bacterial colonization and infections risks.

  15. Alkali corrosion resistant coatings and ceramic foams having superfine open cell structure and method of processing

    Science.gov (United States)

    Brown, Jr., Jesse J.; Hirschfeld, Deidre A.; Li, Tingkai

    1993-12-07

    Alkali corrosion resistant coatings and ceramic foams having superfine open cell structure are created using sol-gel processes. The processes have particular application in creating calcium magnesium zirconium phosphate, CMZP, coatings and foams.

  16. Development of a thin film vitreous bond based composite ceramic coating for corrosion and abrasion services

    International Nuclear Information System (INIS)

    Franke, B.

    2003-01-01

    IPC has been involved with the Alberta Research Council in developing a vitreous bond (VB) - based composite ceramic fluoropolymer coating technology. Compared to the present state of the art which is based on a hard discontinuous phase (ceramic particles) suspended in a soft continuous matrix (fluoropolymer mix) the novelty of our approach consists of designing a composite system in which both the ceramic and the fluoropolymer phases are continuous. The ceramic matrix will provide the strength and the erosion resistance for the fluoropolymer matrix even at high temperatures. The ceramic formulation employed is not affected by temperatures up to 500 o F while the fluoropolymer matrix provides a corrosion protection seal for the ceramic matrix. The inherent flexibility of the polymer matrix will protect against brittle fractures that may develop by handling or impact. Therefore the composite coating is able to withstand the deformation of the substrate without chipping or disbanding. The fluoropolymer matrix also provides dry lubrication properties further enhancing the erosion resistance of the ceramic phase. The thickness of the coating is very thin, in the 25 to 100 micron range. In summary, the coating technology is able to provide the following features: Corrosion protection levels similar to those of fluoropolymer coatings; Erosion resistance similar to that of ceramic coatings; Price comparable to that of polymer coatings; Exceptional wear resistance properties; and Capability for coating complicated shapes internally or externally or both. This paper will discuss the theory and development of this new technology and the resultant coating and potential properties. (author)

  17. Development of thermally-sprayed Al-Cu-Fe-Cr quasicrystal coating

    Science.gov (United States)

    Setiamarga, Budi Hartono

    A class of quasicrystal alloys that has drawn a lot of attention is aluminum based quasicrystal alloys because they are hard, light weight, wear resistant, and have a non-stick property. Quasicrystalline materials in the form of coatings produced by thermal spray techniques have been developed to utilize their properties. The goal of this research has been to develop the knowledge necessary to produce good thermally sprayed Al-Cu-Fe-Cr quasicrystal coatings. Boron has been found to improve ductility, reduce porosity and increase hardness when added to other thermally sprayed powders, therefore, as part of this research, quasicrystal coatings containing boron will also be produced and evaluated. The first phase of this research utilized a fine QC-1 quasicrystal powder of Alsb{70.5}Cusb{10.1}Fesb{8.8}Crsb{10.6}. The addition of boron was done using mechanical mixing. The addition of boron in fused QC-1 powders shows that boron can reduce porosity and increase hardness. Due to difficulties with thermal spraying the fine QC-1 powder and evaporation of aluminum, a coarser QC-2 powder with similar composition to QC-1 powder was produced. QC-2 and boron modified QC-2 coatings have similar hardness and levels of porosity, around 11%, although boron modified QC-2 coatings proved to be more wear resistant than plain QC-2 coatings. Both coatings demonstrated a weak coating-substrate interface bonding. Laser heat treatment was used to reduce the porosity and strengthen the coating-substrate interface bonding. Laser treatment of QC-2 quasicrystal coatings resulted in harder and lower porosity coatings with better coating-substrate interface bonding. Unfortunately, hot-cracks in the coatings were also produced. Hot-cracks are undesireable because they decrease the coating's corrosion resistance. Thermal spraying using High Velocity Oxygen Fuel (HVOF) technique was done. It was used on QC-2 powder and QC-3 powder of composition Alsb{68.6}Cusb{10.8}Fesb{8.9}Crsb{9.7}Bsb{2.0}. This

  18. Influence of gas detonation spraying conditions on the quality of Fe-Al intermetallic protective coatings

    Directory of Open Access Journals (Sweden)

    Senderowski C.

    2007-01-01

    Full Text Available The aim of this paper is to present generalized research results and analyses of the quality of coatings produced with self decomposing Fe-Al intermetallic powders deposited on 1045 steel in the gas detonation spraying (GDS. A number of GDS experiments has been carried out with significantly changed operational spraying parameters (the volume of the fuel gas, carrier gas, distance and the frequency of spraying which define the process energy level directly influencing the quality of the coating. On the basis of the initial results the choice of the process parameters has been made to obtain the most advantageous set of geometrical and physical-mechanical properties of the coating material and substrate. The quality of the coatings was considered by taking into account the grain morphology, chemical content, phase inhomogeneity, cohesive porosity, as well as adhesive porosity in the substrate coating joint. The coating roughness was also considered. It was found that all GDS coatings produced are built with lamellar splats which result from the GDS process transformed (changed plasticity and geometry powder particles forming the deposit. The result of the GDS spraying parameters optimization is the lack of signs of melting of the material (even in microareas while the geometry of the deposited grains is considerably changed. This phenomenon has been considered as a proof of high plasticity of the GDS formed Fe-Al intermetallic coatings.

  19. Formation of hydrotalcite coating on the aluminum alloy 6060 in spray system

    DEFF Research Database (Denmark)

    Zhou, Lingli; Friis, Henrik; Roefzaad, Melanie

    2016-01-01

    -layer structure with average thickness of ∼1000 nm. The hydrotalcite-coated samples performed better than those without coatings in salt-spray and filiform-corrosion tests, and further treatment involving sealing with a Mg acetate solution and dipping in a H2O2 + Ce-based solution improved the corrosion...

  20. 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#

  1. Development of cold sprayed Cu coating for canister

    International Nuclear Information System (INIS)

    Kim, Hyung Jun; Kang, Yoon Ha

    2010-01-01

    Cold sprayed Cu deposition was studied for the application of outer part of canister for high level nuclear waste. Five commercially available pure Cu powders were analyzed and sprayed by high pressure cold spray system. Electrochemical corrosion test using potentiostat in 3.5% NaCl solution was conducted as well as microstructural analysis including hardness and oxygen content measurements. Overall evaluation of corrosion performance of cold sprayed Cu deposition is inferior to forged and extruded Cu plates, but some of Cu depositions are comparable to Cu plates. The simulated corrosion test in 200m underground cave is still in progress. The effect of cold spray process parameters was also studied and the results show that the type of nozzle is the most important other than powder feed rate, spray distance, and scan speed. 1/10 scale miniature of canister was manufactured confirming that the production of full scale canister is possible

  2. 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...

  3. 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

  4. Environmental Barrier Coatings for Ceramic Matrix Composites - An Overview

    Science.gov (United States)

    Lee, Kang; van Roode, Mark; Kashyap, Tania; Zhu, Dongming; Wiesner, Valerie

    2017-01-01

    SiC/SiC Ceramic Matrix Composites (CMCs) are increasingly being considered as structural materials for advanced power generation equipment because of their light weight, higher temperature capability, and oxidation resistance. Limitations of SiC/SiC CMCs include surface recession and component cracking and associated chemical changes in the CMC. The solutions pursued to improve the life of SiC/SiC CMCs include the incorporation of coating systems that provide surface protection, which has become known as an Environmental Barrier Coating (EBC). The development of EBCs for the protection of gas turbine hot section CMC components was a continuation of coating development work for corrosion protection of silicon-based monolithics. Work on EBC development for SiC/SiC CMCs has been ongoing at several national laboratories and the original gas turbine equipment manufacturers. The work includes extensive laboratory, rig and engine testing, including testing of EBC coated SiC/SiC CMCs in actual field applications. Another EBC degradation issue which is especially critical for CMC components used in aircraft engines is the degradation from glassy deposits of calcium-magnesium-aluminosilicate (CMAS) with other minor oxides. This paper addresses the need for and properties of external coatings on SiC/SiC CMCs to extend their useful life in service and the retention of their properties.

  5. Assessment of thermal spray coatings for wear and abrasion resistance applications

    Science.gov (United States)

    Karode, Ishaan Nitin

    Thermal spray cermet and metallic coatings are extensively used for wear, abrasion and corrosion control in a variety of industries. The first part of the thesis focuses mainly on testing of sand erosion resistance of thermal spray coatings on carbon composites used in the manufacture of helicopter rotor blades. The test set-up employed is a sand blasting machine and is an effort to duplicate the in-flight conditions especially those encountered in hot arid conditions. The technique adopted follows the Department of Defence test method standard. Carbon Composites have excellent stiffness, strength and low weight/density. The strength to weight ratio is high. Hence, these are used in aerospace applications to a large extent. However, the biggest problem encountered with carbon composites is its low abrasion resistance as its surface is very weak. Hence, thermal spray coatings are used to improve the surface properties of CFRP. Zinc bond coats and WC-Co coatings were tested. However, high amount of thermal stresses were developed between the substrate and the coating due to large differences in the CTE's of the both, leading to high mass losses within two minutes and just 130 grams of sand sprayed on to the coatings with the sand blasting machine built; and hence the coatings with CC as a substrate could not qualify for the application. The second part of the thesis focuses on the assessment of different thermal spray coatings used for manufacture of mechanical seals in pumps and analyze the best coating material for the wear resistance application through detail quantification of material loss by block-on-ring test set-up. A machine based on Block-on-ring test set-up following ASTM G77 (Measurement of Adhesive wear resistance of thermal spray coatings) standards was built to duplicate the pump conditions. Thermally sprayed coated materials were tested in different conditions (Load, time, abrasive). WC-Co had the highest wear resistance (lower volume losses) and

  6. Modelling of structure and properties of plasma-sprayed carbide coatings

    International Nuclear Information System (INIS)

    Nitkiewicz, Z.; Iwaszko, J.

    1999-01-01

    Subject to examination were carbide coatings deposited on the steel substrate by plasma spraying. The coatings were remelted using diverse methods of treatment, ranging from a single and multiple treatment with continuous micro-plasma arc, through laser remelting, to treatment by the TIG welding method. Both structural changes in the remelted zone and some of the properties, such as microhardness and wear resistance were analysed. Comparative investigations were performed both prior to, and after remelting. The present work is a continuation of studies on plasma sprayed and micro-plasma remelted oxide coatings commenced in early 90's in the Materials Engineering Institute of the Technical University of Czestochowa. (author)

  7. 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

  8. 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

  9. Mechanical and Thermal Transport Properties of Suspension Thermal-Sprayed Alumina-Zirconia Composite Coatings

    Czech Academy of Sciences Publication Activity Database

    Oberste-Berghaus, J.; Legoux, J.-G.; Moreau, C.; Tarasi, F.; Chráska, Tomáš

    2008-01-01

    Roč. 17, č. 1 (2008), s. 91-104 ISSN 1059-9630 Institutional research plan: CEZ:AV0Z20430508 Keywords : thermal spraying * nanocrystalline composites * wear Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.200, year: 2008

  10. Applicability assessment of ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ to the eradication of Legionella in rainwater storage tanks for household use.

    Science.gov (United States)

    Oana, Kozue; Kobayashi, Michiko; Yamaki, Dai; Sakurada, Tsukasa; Nagano, Noriyuki; Kawakami, Yoshiyuki

    2015-01-01

    Water environments appear to be the habitats of Legionella species. Legionellosis is considered as a preventable illness because bacterial reservoirs can be controlled and removed. Roof-harvested rainwater has attracted significant attention not only as a groundwater recharge but also as a potential alternative source of nonpotable water. We successfully developed ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ using the thermal spraying method. The ceramic microbeads were demonstrated to have bactericidal activities against not only Legionella but also coliform and heterotrophic bacteria. Immersing the ceramic microbeads in household rainwater storage tanks was demonstrated to yield the favorable eradication of Legionella organisms. Not only rapid-acting but also long-lasting bactericidal activities of the ceramic microbead were exhibited against Legionella pneumophila. However, time-dependent attenuation of the bactericidal activities against Legionella were also noted in the sustainability appraisal experiment. Therefore, the problems to be overcome surely remain in constantly managing the Legionella-pollution by means of immersing the ceramic microbeads. The results of our investigation apparently indicate that the earthplus™-coated ceramic microbeads would become the favorable tool for Legionella measures in household rainwater storage tanks, which may become the natural reservoir for Legionella species. Our investigation would justify further research and data collection to obtain more reliable procedures to microbiologically regulate the Legionella in rainwater storage tanks.

  11. Structure and Corrosion Behavior of Arc-Sprayed Zn-Al Coatings on Ductile Iron Substrate

    Science.gov (United States)

    Bonabi, Salar Fatoureh; Ashrafizadeh, Fakhreddin; Sanati, Alireza; Nahvi, Saied Mehran

    2018-02-01

    In this research, four coatings including pure zinc, pure aluminum, a double-layered coating of zinc and aluminum, and a coating produced by simultaneous deposition of zinc and aluminum were deposited on a cast iron substrate using electric arc-spraying technique. The coatings were characterized by XRD, SEM and EDS map and spot analyses. Adhesion strength of the coatings was evaluated by three-point bending tests, where double-layered coating indicated the lowest bending angle among the specimens, with detection of cracks at the coating-substrate interface. Coatings produced by simultaneous deposition of zinc and aluminum possessed a relatively uniform distribution of both metals. In order to evaluate the corrosion behavior of the coatings, cyclic polarization and salt spray tests were conducted. Accordingly, pure aluminum coating showed susceptibility to pitting corrosion and other coatings underwent uniform corrosion. For double-layered coating, SEM micrographs revealed zinc corrosion products as flaky particles in the pores formed by pitting on the surface, an indication of penetration of corrosion products from the lower layer (zinc) to the top layer (aluminum). All coatings experienced higher negative corrosion potentials than the iron substrate, indicative of their sacrificial behavior.

  12. Mechanical property changes in HVOF sprayed nano-structured WC-17wt.%Ni(80/20)Cr coating with varying substrate roughness

    Science.gov (United States)

    Ben Mahmud, Tarek A.; Saha, Gobinda C.; Khan, Tahir I.

    2014-06-01

    Thermally sprayed coatings developed by use of high velocity oxy-fuel (HVOF) process are known for their superior wear characteristics. In many industrial applications, new parts as well as repaired and refurbished parts coated with WC-Co microstructured coatings have shown enhanced erosion-corrosion and abrasive resistant properties when compared with other surface modification technologies such as chrome replacement, fusion welding, and cladding. This research has been further directed towards the development of HVOF technique to deposit dense nanostructured ceramic-metallic composites. The mechanism of plastic deformation, which determines the strength and ductility of materials, in nanostructured materials are different, thereby leading to novel mechanical properties. Various parameters can influence these properties, but the substrate surface preparation by grit blasting before thermal spraying is one critical parameter. The grit blasting process generates a surface roughness, which ensures mechanical anchoring between the coating and the substrate surface. In this work, the sliding wear behavior and microhardness of WC-17wt.%Ni(80/20)Cr cermet coatings deposited onto carbon steel substrates are examined as a function of three different surface roughness values under different loads. The results show that as-prepared surface with different blasting profiles have a direct influence on the surface roughness and wear performance of the coatings. The sliding wear resistance of the coatings increased as the substrate surface roughness increased. The wear depth decreased with increasing surface roughness.

  13. The Influence of Spray Parameters on the Characteristics of Hydroxyapatite In-Flight Particles, Splats and Coatings by Micro-plasma Spraying

    Science.gov (United States)

    Liu, Xiao-mei; He, Ding-yong; Wang, Yi-ming; Zhou, Zheng; Wang, Guo-hong; Tan, Zhen; Wang, Zeng-jie

    2018-02-01

    Hydroxyapatite (HA) is one of the most important bioceramic materials used in medical implants. The structure of HA coatings is closely related to their manufacturing process. In the present study, HA coatings were deposited on Ti-6Al-4V substrate by micro-plasma spraying. Results show that three distinct HA coatings could be obtained by changing the spraying power from 0.5 to 1.0 kW and spraying stand-off distance from 60 to 110 mm: (1) high crystallinity (93.3%) coatings with porous structure, (2) high crystallinity coatings (86%) with columnar structure, (3) higher amorphous calcium phosphate (ACP, 50%) coatings with dense structure. The in-flight particles melting state and splat topography was analyzed to better understand the formation mechanism of three distinct HA coatings. Results show that HA coatings sprayed at low spraying power and short stand-off distance exhibit high crystallinity and porosity is attributed to the presence of partially melted particles. High crystallinity HA coatings with (002) crystallographic texture could be deposited due to the complete melting of the in-flight particles and low cooling rate of the disk shape splats under higher spraying power and shorter SOD. However, splashed shape splats with relative high cooling can be provided by increasing SOD, which leads to the formation of ACP.

  14. The freezing process of continuously sprayed water droplets on the superhydrophobic silicone acrylate resin coating surface

    Science.gov (United States)

    Hu, Jianlin; Xu, Ke; Wu, Yao; Lan, Binhuan; Jiang, Xingliang; Shu, Lichun

    2014-10-01

    This study conducted experiments on freezing process of water droplets on glass slides covered with superhydrophobic coatings under the continuous water spray condition in the artificial climatic chamber which could simulate low temperature and high humidity environments. The freezing mechanism and freezing time of water droplets under the condition of continuous spray were observed by the microscope and were compared with those of the single static droplet. Then, differences of freezing process between continuously sprayed droplets and single static droplet were analyzed. Furthermore, the effects of static contact angle (CA), contact angle hysteresis (CAH) and roughness of the superhydrophobic coating surface on the freezing time of continuously sprayed droplets were explored. Results show that the freezing process of the continuously sprayed droplets on the superhydrophobic coating started with the homogeneous nucleation at gas-liquid interfaces. In addition, the temperature difference between the location near the solid-liquid interface and the location near the gas-liquid interface was the key factor that influenced the ice crystallization mechanism of water droplets. Moreover, with the larger CA, the smaller CAH and the greater roughness of the surface, droplets were more likely to roll down the surface and the freezing duration on the surface was delayed. Based on the findings, continuous water spray is suggested in the anti-icing superhydrophobic coatings research.

  15. 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)

  16. Failure of aluminium metal spray/organic duplex coating systems on structural steel

    OpenAIRE

    Sumon, T. A.; Scantlebury, J. D.; Lyon, S. B.

    2013-01-01

    Individually, aluminium metal spray (AMS) and organic paints are well established as effective protective coatings for steel substrates. These coatings are also frequently used together as duplex systems where their combination should produce a synergistic effect. However in certain, mainly marine, environments premature failure of such coatings, involving early blistering of the paint, has been observed in service after 3-5 years. This work aims to understand the mechanisms associated with t...

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

    OpenAIRE

    Moosavi SB; Fathi MH. BS; MSC; Feizi Gh; Mortazavi V

    2001-01-01

    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 cani...

  18. Processing and optimization of functional ceramic coatings and inorganic nanomaterials

    Science.gov (United States)

    Nyutu, Edward Kennedy G.

    Processing of functional inorganic materials including zero (0-D) dimensional (e.g. nanoparticles), 1-D (nanorods, nanofibers), and 2-D (films/coating) structures is of fundamental and technological interest. This research will have two major sections. The first part of section one focuses on the deposition of silicon dioxide onto a pre-deposited molybdenum disilicide coating on molybdenum substrates for both high (>1000 °C) and moderate (500-600 °C) temperature oxidation protection. Chemical vapor deposition (CVD/MOCVD) techniques will be utilized to deposit the metal suicide and oxide coatings. The focus of this study will be to establish optimum deposition conditions and evaluate the metal oxide coating as oxidation - thermal barriers for Mo substrates under both isothermal (static) and cyclic oxidation conditions. The second part of this section will involve a systematic evaluation of a boron nitride (BN) interface coating prepared by chemical vapor deposition. Ceramic matrix composites (CMCs) are prospective candidates for high (>1000 °C) temperature applications and fiber- matrix interfaces are the dominant design parameters in ceramic matrix composites (CMCs). An important goal of the study is to determine a set of process parameters, which would define a boron nitride (BN) interface coating by a chemical vapor deposition (CVD) process with respect to coating. In the first part of the second section, we will investigate a new approach to synthesize ultrafine metal oxides that combines microwave heating and an in-situ ultrasonic mixing of two or more liquid precursors with a tubular flow reactor. Different metal oxides such as nickel ferrite and zinc aluminate spinels will be studied. The synthesis of metal oxides were investigated in order to study the effects of the nozzle and microwave (INM process) on the purity, composition, and particle size of the resulting powders. The second part of this research section involves a study of microwave frequency

  19. Chemically sprayed PbS coatings for photothermal solar energy conversion

    Science.gov (United States)

    Agarwal, R. C.; Pillai, P. K. C.

    1982-05-01

    This paper reports on an investigation into the optical and physical properties of PbS coatings prepared by spray pyrolysis onto chemically brightened aluminum substrates. The advantages are low cost, reasonably good selectivity and the coatings' ability to be scaled onto collectors of any desired size. The coatings exhibit a high absorptivity in the solar range and a low emissivity in the thermal range. Finally, the photothermal conversion efficiencies of black paint-coated and PbS-coated solar collectors are compared.

  20. Intermetallic Al-, Fe-, Co- and Ni-Based Thermal Barrier Coatings Prepared by Cold Spray for Applications on Low Heat Rejection Diesel Engines

    Science.gov (United States)

    Leshchinsky, E.; Sobiesiak, A.; Maev, R.

    2018-02-01

    Conventional thermal barrier coating (TBC) systems consist of a duplex structure with a metallic bond coat and a ceramic heat insulating topcoat. They possess the desired low thermal conductivity, but at the same time they are very brittle and sensitive to thermal shock and thermal cycling due to the inherently low coefficient of thermal expansion. Recent research activities are focused on the developing of multilayer TBC structures obtained using cold spraying and following annealing. Aluminum intermetallics have demonstrated thermal and mechanical properties that allow them to be used as the alternative TBC materials, while the intermetallic layers can be additionally optimized to achieve superior thermal physical properties. One example is the six layer TBC structure in which cold sprayed Al-based intermetallics are synthesized by annealing in nitrogen atmosphere. These multilayer coating systems demonstrated an improved thermal fatigue capability as compared to conventional ceramic TBC. The microstructures and properties of the coatings were characterized by SEM, EDS and mechanical tests to define the TBC material properties and intermetallic formation mechanisms.

  1. 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.

  2. Hydroxyapatite-Coated Magnesium-Based Biodegradable Alloy: Cold Spray Deposition and Simulated Body Fluid Studies

    Science.gov (United States)

    Noorakma, Abdullah C. W.; Zuhailawati, Hussain; Aishvarya, V.; Dhindaw, B. K.

    2013-10-01

    A simple modified cold spray process in which the substrate of AZ51 alloys were preheated to 400 °C and sprayed with hydroxyapatite (HAP) using high pressure cold air nozzle spray was designed to get biocompatible coatings of the order of 20-30 μm thickness. The coatings had an average modulus of 9 GPa. The biodegradation behavior of HAP-coated samples was tested by studying with simulated body fluid (SBF). The coating was characterized by FESEM microanalysis. ICPOES analysis was carried out for the SBF solution to know the change in ion concentrations. Control samples showed no aluminum corrosion but heavy Mg corrosion. On the HAP-coated alloy samples, HAP coatings started dissolving after 1 day but showed signs of regeneration after 10 days of holding. All through the testing period while the HAP coating got eroded, the surface of the sample got deposited with different apatite-like compounds and the phase changed with course from DCPD to β-TCP and β-TCMP. The HAP-coated samples clearly improved the biodegradability of Mg alloy, attributed to the dissolution and re-precipitation of apatite showed by the coatings as compared to the control samples.

  3. Enhanced ductility in thermally sprayed titania coating synthesized using a nanostructured feedstock

    International Nuclear Information System (INIS)

    Lima, R.S.; Marple, B.R.

    2005-01-01

    Nanostructured and conventional titania (TiO 2 ) feedstock powders were thermally sprayed via high velocity oxy-fuel (HVOF). The microstructure, porosity, Vickers hardness, crack propagation resistance, bond strength (ASTM C633), abrasion behavior (ASTM G65) and the wear scar characteristics of these two types of coatings were analyzed and compared. The coating made from the nanostructured feedstock exhibited a bimodal microstructure, with regions containing particles that were fully molten (conventional matrix) and regions with embedded particles that were semi-molten (nanostructured zones) during the thermal spraying process. The bimodal coating also exhibited higher bond strength and higher wear resistance when compared to the conventional coating. By comparing the wear scars of both coatings (via scanning electron microscopy and roughness measurements) it was observed that when the coatings were subjected to the same abrasive conditions the wear scar of the bimodal coating was smoother, with more plastically deformed regions than the conventional coating. It was concluded that this enhanced ductility of the bimodal coating was caused by its higher toughness. The results suggest that nanostructured zones randomly distributed in the microstructure of the bimodal coating act as crack arresters, thereby enhancing toughness and promoting higher critical depth of cut, which provides a broader plastic deformation range than that exhibited by the conventional coating. This work provides evidence that the enhanced ductility of the bimodal coating is a nanostructured-related property, not caused by any other microstructural artifact

  4. 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.

  5. Characterisation of Ceramic-Coated 316LN Stainless Steel Exposed to High-Temperature Thermite Melt and Molten Sodium

    Science.gov (United States)

    Ravi Shankar, A.; Vetrivendan, E.; Shukla, Prabhat Kumar; Das, Sanjay Kumar; Hemanth Rao, E.; Murthy, S. S.; Lydia, G.; Nashine, B. K.; Mallika, C.; Selvaraj, P.; Kamachi Mudali, U.

    2017-11-01

    Currently, stainless steel grade 316LN is the material of construction widely used for core catcher of sodium-cooled fast reactors. Design philosophy for core catcher demands its capability to withstand corium loading from whole core melt accidents. Towards this, two ceramic coatings were investigated for its application as a layer of sacrificial material on the top of core catcher to enhance its capability. Plasma-sprayed thermal barrier layer of alumina and partially stabilised zirconia (PSZ) with an intermediate bond coat of NiCrAlY are selected as candidate material and deposited over 316LN SS substrates and were tested for their suitability as thermal barrier layer for core catcher. Coated specimens were exposed to high-temperature thermite melt to simulate impingement of molten corium. Sodium compatibility of alumina and PSZ coatings were also investigated by exposing samples to molten sodium at 400 °C for 500 h. The surface morphology of high-temperature thermite melt-exposed samples and sodium-exposed samples was examined using scanning electron microscope. Phase identification of the exposed samples was carried out by x-ray diffraction technique. Observation from sodium exposure tests indicated that alumina coating offers better protection compared to PSZ coating. However, PSZ coating provided better protection against high-temperature melt exposure, as confirmed during thermite melt exposure test.

  6. Investigation about the Chrome Steel Wire Arc Spray Process and the Resulting Coating Properties

    Science.gov (United States)

    Wilden, J.; Bergmann, J. P.; Jahn, S.; Knapp, S.; van Rodijnen, F.; Fischer, G.

    2007-12-01

    Nowadays, wire-arc spraying of chromium steel has gained an important market share for corrosion and wear protection applications. However, detailed studies are the basis for further process optimization. In order to optimize the process parameters and to evaluate the effects of the spray parameters DoE-based experiments had been carried out with high-speed camera shoots. In this article, the effects of spray current, voltage, and atomizing gas pressure on the particle jet properties, mean particle velocity and mean particle temperature and plume width on X46Cr13 wire are presented using an online process monitoring device. Moreover, the properties of the coatings concerning the morphology, composition and phase formation were subject of the investigations using SEM, EDX, and XRD-analysis. These deep investigations allow a defined verification of the influence of process parameters on spray plume and coating properties and are the basis for further process optimization.

  7. Effect of Post-spray Shot Peening Treatment on the Corrosion Behavior of NiCr-Mo Coating by Plasma Spraying of the Shell-Core-Structured Powders

    Science.gov (United States)

    Tian, Jia-Jia; Wei, Ying-Kang; Li, Cheng-Xin; Yang, Guan-Jun; Li, Chang-Jiu

    2018-01-01

    Corrosion of metal plays a detrimental role in service lifetime of parts or systems. Therefore, coating a protective film which is fully dense and defects free on the base metal is an effective approach to protect the base metal from corrosion. In this study, a dense NiCr-20Mo coating with excellent lamellar interface bonding was deposited by plasma spraying of the novel shell-core-structured Mo-clad-NiCr powders, and then post-spray shot peening treatment by cold spraying of steel shots was applied to the plasma-sprayed NiCr-20Mo coating to obtain a fully dense coating through eliminating possibly existed pores and un-bonded interfaces within the NiCr-20Mo coating. Corrosion behaviors of the NiCr-20Mo coatings before and after shot peening were tested to investigate the effect of the post-spray shot peening on the corrosion behavior of the NiCr-20Mo coating. Results showed that a much dense and uniform plasma-sprayed NiCr-20Mo coating with perfect lamellar bonding at most of interfaces was deposited. However, the electrochemical tests revealed the existence of through-thickness pores in the as-plasma-sprayed NiCr-20Mo coating. Through the post-spray shot peening treatment, a completely dense top layer in the coating was formed, and with the increase in the shot peening intensity from one pass to three passes, the dense top layer became thicker from 100 μm to reach 300 μm of the whole coating thickness. Thus, a fully dense bulk-like coating was obtained. Corrosion test results showed that the dense coating layer resulting from densification of shot peening can act as an effective barrier coating to prevent the penetration of the corrosive medium and consequently protect the substrate from corrosion effectively. Therefore, a fully dense bulk-like NiCr-20Mo coating with excellent corrosion resistance can be achieved through the plasma spraying of Mo-clad-NiCr powders followed by appropriate post-spray shot peening treatment.

  8. Design Optimization of Liquid Fueled High Velocity Oxy- Fuel Thermal Spraying Technique for Durable Coating for Fossil Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    Choudhuri, Ahsan [Univ. of Texas, El Paso, TX (United States); Love, Norman [Univ. of Texas, El Paso, TX (United States)

    2016-11-04

    High-velocity oxy–fuel (HVOF) thermal spraying was developed in 1930 and has been commercially available for twenty-five years. HVOF thermal spraying has several benefits over the more conventional plasma spray technique including a faster deposition rate which leads to quicker turn-around, with more durable coatings and higher bond strength, hardness and wear resistance due to a homogeneous distribution of the sprayed particles. HVOF thermal spraying is frequently used in engineering to deposit cermets, metallic alloys, composites and polymers, to enhance product life and performance. HVOF thermal spraying system is a highly promising technique for applying durable coatings on structural materials for corrosive and high temperature environments in advanced ultra-supercritical coal- fired (AUSC) boilers, steam turbines and gas turbines. HVOF thermal spraying is the preferred method for producing coatings with low porosity and high adhesion. HVOF thermal spray process has been shown to be one of the most efficient techniques to deposit high performance coatings at moderate cost. Variables affecting the deposit formation and coating properties include hardware characteristics such as nozzle geometry and spraying distance and process parameters such as equivalence ratio, gas flow density, and powder feedstock. In the spray process, the powder particles experience very high speeds combined with fast heating to the powder material melting point or above. This high temperature causes evaporation of the powder, dissolution, and phase transformations. Due to the complex nature of the HVOF technique, the control and optimization of the process is difficult. In general, good coating quality with suitable properties and required performance for specific applications is the goal in producing thermal spray coatings. In order to reach this goal, a deeper understanding of the spray process as a whole is needed. Although many researchers studied commercial HVOF thermal spray

  9. Fracture evaluation of thermally sprayed coatings in dependence on cohesive strength

    Science.gov (United States)

    Schubert, J.; Česánek, Z.

    2017-05-01

    Measuring the cohesive strength of thermally sprayed coatings is relatively difficult matter, which can be accessed in many directions. This issue is nowadays solved by use of Scratch test method. This method is not completely sufficient for the cohesive strength testing because the coating is under load of combined stresses during the Scratch test. The reason to develop this method was need for exact measurement of tensile cohesion toughness of thermally sprayed coatings, which could provide results as close to a classic tensile test as possible. Another reason for development of this method was the impossibility of direct comparison with results obtained by other methods. Tested coatings were prepared using HP / HVOF (Stellite 6, NiCrBSi, CrC-NiCr and Hastelloy C-276). These coatings were selected as commonly used in commercial sector and also on because of rising customer demand for ability to provide such coating characteristics. The tested coatings were evaluated in terms of cohesive strength (method based on tensile strength test). Final fractures were evaluated by optical microscopy together with scanning electron microscopy and EDS analysis. As expected higher cohesive strength showed metallic coatings with top results of coating Stellite 6. Carbide coatings showed approximately third of the cohesion strength in comparison with metal based coating.

  10. 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

  11. Formulation and evaluation of albumin microspheres and its enteric coating using a spray-dryer.

    Science.gov (United States)

    Bejugam, Naveen K; Uddin, Akm N; Gayakwad, Sanjay G; D'Souza, Martin J

    2008-12-01

    This study optimized and evaluated the conditions for surface coating of microspheres using a spray-dryer. Four formulations of Bromophenol blue (BPB)-loaded albumin microspheres were prepared using a spray-dryer, cross-linked at different concentrations and time periods. One of the optimized formulations with the desired characteristics was selected for enteric coating with Eudragit L100-55. The procedure involved suspending BPB microspheres in polymer solution and spray-drying it. Four enteric coated formulations were prepared with different concentrations of microspheres in suspension (0.25 and 0.5%w/v) and polymer concentrations (0.25 and 0.5%w/v). Change in the mean particle size after coating was determined using a Laser Particle Counter. The surface coating technique employed did not significantly increase the particle size. Enteric coating efficiency was determined in simulated gastric fluid. Compared to the uncoated microspheres the cumulative amount of drug released from coated microspheres was significantly lower for 3 h, implying efficient surface coating.

  12. Bioactive glass–ceramic coating for enhancing the in vitro corrosion resistance of biodegradable Mg alloy

    International Nuclear Information System (INIS)

    Ye Xinyu; Cai Shu; Dou Ying; Xu Guohua; Huang Kai; Ren Mengguo; Wang Xuexin

    2012-01-01

    Highlights: ► Sol–gel derived 45S5 glass–ceramic coating was prepared on Mg alloy substrate. ► The corrosion resistance of glass–ceramic coated Mg alloy was markedly improved. ► The corrosion behavior of the coated sample varied due to the cracking of coating. - Abstract: In this work, a bioactive 45S5 glass–ceramic coating was synthesized on magnesium (Mg) alloy substrate by using a sol–gel dip-coating method, to improve the initial corrosion resistance of AZ31 Mg alloy. The surface morphology and phase composition of the glass–ceramic coating were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The coating composed of amorphous phase and crystalline phase Na 2 Ca 2 Si 3 O 9 , with the thickness of ∼1.0 μm, exhibited a uniform and crack-free surface morphology. The corrosion behavior of the uncoated and coated Mg alloy substrates was investigated by the electrochemical measurements and immersion tests in simulated body fluid (SBF). Potentiodynamic polarization tests recorded an increase of potential (E corr ) form −1.60 V to −1.48 V, and a reduction of corrosion current density (i corr ) from 4.48 μA cm −2 to 0.16 μA cm −2 , due to the protection provided by the glass–ceramic coating. Immersion tests also showed the markedly improved corrosion resistance of the coated sample over the immersion period of 7 days. Moreover, after 14 days of immersion in SBF, the corrosion resistance of the coated sample declined due to the cracking of the glass–ceramic coating, which was confirmed by electrochemical impedance spectroscopy (EIS) analysis. The results suggested that the 45S5 glass–ceramic coated Mg alloy could provide a suitable corrosion behavior for use as degradable implants.

  13. Supplementary Microstructural Features Induced During Laser Surface Melting of Thermally Sprayed Inconel 625 Coatings

    Science.gov (United States)

    Ahmed, Nauman; Voisey, K. T.; McCartney, D. G.

    2014-02-01

    Laser surface melting of thermally sprayed coatings has the potential to enhance their corrosion properties by incorporating favorable microstructural changes. Besides homogenizing the as-sprayed structure, laser melting may induce certain microstructural modifications (i.e., supplementary features) in addition to those that directly improve the corrosion performance. Such features, being a direct result of the laser treatment process, are described in this paper which is part of a broader study in which high velocity oxy-fuel sprayed Inconel 625 coatings on mild-steel substrates were treated with a diode laser and the modified microstructure characterized using optical and scanning electron microscopy and x-ray diffraction. The laser treated coating features several different zones, including a region with a microstructure in which there is a continuous columnar dendritic structure through a network of retained oxide stringers.

  14. Raman microscopic studies of PVD deposited hard ceramic coatings

    International Nuclear Information System (INIS)

    Constable, C.P.

    2000-01-01

    PVD hard ceramic coatings grown via the combined cathodic arc/unbalance magnetron deposition process were studied using Raman microscopy. Characteristic spectra from binary, multicomponent, multilayered and superlattice coatings were acquired to gain knowledge of the solid-state physics associated with Raman scattering from polycrystalline PVD coatings and to compile a comprehensive spectral database. Defect-induced first order scattering mechanisms were observed which gave rise to two pronounced groups of bands related to the acoustical (150- 300cm -1 ) and optical (400-7 50cm -1 ) parts of the phonon spectrum. Evidence was gathered to support the theory that the optic modes were mainly due to the vibrations of the lighter elements and the acoustic modes due to the vibrations of the heavier elements within the lattice. A study into the deformation and disordering on the Raman spectral bands of PVD coatings was performed. TiAIN and TiZrN coatings were intentionally damaged via scratching methods. These scratches were then analysed by Raman mapping, both across and along, and a detailed spectral interpretation performed. Band broadening occurred which was related to 'phonon relaxation mechanisms' as a direct result of the breaking up of coating grains resulting in a larger proportion of grain boundaries per-unit-volume. A direct correlation of the amount of damage with band width was observed. Band shifts were also found to occur which were due to the stresses caused by the scratching process. These shifts were found to be the largest at the edges of scratches. The Raman mapping of 'droplets', a defect inherent to PVD deposition processes, found that higher compressive stresses and large amounts of disorder occurred for coating growth onto droplets. Strategies designed to evaluate the ability of Raman microscopy to monitor the extent of real wear on cutting tools were evaluated. The removal of a coating layer and subsequent detection of a base layer proved

  15. Nanosilver conductive lines made by spray coating and aerosol jet printing technique

    Science.gov (United States)

    Krzeminski, Jakub; Wroblewski, Grzegorz; Dybowska-Sarapuk, Lucja; Lepak, Sandra; Jakubowska, Malgorzata

    2017-08-01

    Printing electronics even though the printing techniques are known for a long time, are gaining in importance. The possibility of making the electronic circuits on flexible, big-area substrates with efficient and cheap technology make it attractive for the electronic industry. Spray coating, as a one of printing methods, additionally provide the chance to print on the non-flat, complicated shaped substrates. Despite the spray coating is mostly used to print a big pads, it is reachable to spray the separate conductive lines both as a quickly-produced prototype and as a fully manufactured circuit. Our work presents the directly printed lines with spray coating technique. For the printing process self-made ink was used. We tested three different approaches to line formation and compare them in the terms of line edge, resistivity and thickness. Line profiles provide the information about the roughness and the line size. In the end we showed the aerosol jet printed meander to give an overview of this similar to spray coating but more sophisticated technique.

  16. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    Science.gov (United States)

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. 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

  18. An electron microscopy study of the effect of Ce on plasma sprayed bronze coatings

    Science.gov (United States)

    Wensheng, Li; Wang, S. C.; Ma, Chao; Zhiping, Wang

    2012-07-01

    The Cu-Al eutectoid alloy is an excellent material for mould due to its superior low friction. The conventional sand casting technique, however, is not feasible to fabricate high Al bronze because of high hardness and brittleness. Plasma arc spray has been used to produce high Al/Fe bronze coatings for mould. The inherent impurities such as H, O, N, S during the spray, however, may affect the coating's mechanical strength. One approach is to utilise the active rare earth Ce to clean up these impurities. The study is to investigate the effect of Ce on the microstructure, which has few reported in the literature.

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

    Directory of Open Access Journals (Sweden)

    Niemiec D.

    2016-06-01

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

  20. Fundamental Study on the Effect of Spray Parameters on Characteristics of P3HT:PCBM Active Layers Made by Spray Coating

    Directory of Open Access Journals (Sweden)

    Yu Xie

    2015-08-01

    Full Text Available This paper is an attempt to elucidate the effects of the important spray characteristics on the surface morphology and light absorbance of spray-on P3HT:PCBM thin-films, used as an active layer in polymer solar cells (PSCs. Spray coating or deposition is a viable scalable technique for the large-scale, fast, and low-cost fabrication of solution-processed solar cells, and has been widely used for device fabrication, although the fundamental understanding of the underlying and controlling parameters, such as spray characteristics, droplet dynamics, and surface wettability, is still limited, making the results on device fabrication not reproducible and unreliable. In this paper, following the conventional PSC architecture, a PEDOT:PSS layer is first spin-coated on glass substrates, followed by the deposition of P3HT:PCBM using an automatic ultrasonic spray coating system, with a movable nozzle tip, to mimic an industrial manufacturing process. To gain insight, the effects of the spray carrier air pressure, the number of spray passes, the precursor flow rate, and precursor concentration are studied on the surface topography and light absorbance spectra of the spray-on films. Among the results, it is found that despite the high roughness of spray-on films, the light absorbance of the film is satisfactory. It is also found that the absorbance of spray-on films is a linear function of the number of spray passes or deposition layers, based on which an effective film thickness is defined for rough spray-on films. The effective thickness of a rough spray-on P3HT:PCBM film was found to be one-quarter of that of a flat film predicted by a simple mass balance.

  1. 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.

  2. Effect of 2D WS2 Addition on Cold-Sprayed Aluminum Coating

    Science.gov (United States)

    Loganathan, Archana; Rengifo, Sara; Hernandez, Alexander Franco; Emirov, Yusuf; Zhang, Cheng; Boesl, Benjamin; Karthikeyan, Jeganathan; Agarwal, Arvind

    2017-10-01

    Tungsten disulfide (WS2) has excellent solid lubrication properties due to its 2D layered structure. This study focuses on depositing Al-2 wt.% WS2 composite coating by cold spray technique. The effect of WS2 addition on the microstructure, mechanical and tribological properties of the composite coatings is examined in the as-deposited and heat-treated conditions. After heat treatment, the coating density increased to 99% with improved intersplat bonding. The microhardness of the heat-treated Al-2 wt.% WS2 coating increased by 56% as compared to the as-sprayed coating. The wear resistance of heat-treated Al-2 wt.% WS2 coating improved by 75% with a synergistic reduction in the coefficient of friction (COF) by 51%. Transmission electron microscopy investigation reveals the presence of layered WS2 within aluminum splats with a strong interface. This study shows that cold spraying can be effectively used to integrate 2D layered WS2 as a solid lubricant in the metallic coatings.

  3. In vitro and in vivo evaluation of zinc-modified ca-si-based ceramic coating for bone implants.

    Directory of Open Access Journals (Sweden)

    Jiangming Yu

    Full Text Available The host response to calcium silicate ceramic coatings is not always favorable because of their high dissolution rates, leading to high pH within the surrounding physiological environment. Recently, a zinc-incorporated calcium silicate-based ceramic Ca2ZnSi2O7 coating, developed on a Ti-6Al-4V substrate using plasma-spray technology, was found to exhibit improved chemical stability and biocompatibility. This study aimed to investigate and compare the in vitro response of osteoblastic MC3T3-E1 cells cultured on Ca2ZnSi2O7 coating, CaSiO3 coating, and uncoated Ti-6Al-4V titanium control at cellular and molecular level. Our results showed Ca2ZnSi2O7 coating enhanced MC3T3-E1 cell attachment, proliferation, and differentiation compared to CaSiO3 coating and control. In addition, Ca2ZnSi2O7 coating increased mRNA levels of osteoblast-related genes (alkaline phosphatase, procollagen α1(I, osteocalcin, insulin-like growth factor-I (IGF-I, and transforming growth factor-β1 (TGF-β1. The in vivo osteoconductive properties of Ca2ZnSi2O7 coating, compared to CaSiO3 coating and control, was investigated using a rabbit femur defect model. Histological and histomorphometrical analysis demonstrated new bone formation in direct contact with the Ca2ZnSi2O7 coating surface in absence of fibrous tissue and higher bone-implant contact rate (BIC in the Ca2ZnSi2O7 coating group, indicating better biocompatibility and faster osseointegration than CaSiO3 coated and control implants. These results indicate Ca2ZnSi2O7 coated implants have applications in bone tissue regeneration, since they are biocompatible and able to osseointegrate with host bone.

  4. Experimental Verification of Statistically Optimized Parameters for Low-Pressure Cold Spray Coating of Titanium

    Directory of Open Access Journals (Sweden)

    Damilola Isaac Adebiyi

    2016-06-01

    Full Text Available The cold spray coating process involves many process parameters which make the process very complex, and highly dependent and sensitive to small changes in these parameters. This results in a small operational window of the parameters. Consequently, mathematical optimization of the process parameters is key, not only to achieving deposition but also improving the coating quality. This study focuses on the mathematical identification and experimental justification of the optimum process parameters for cold spray coating of titanium alloy with silicon carbide (SiC. The continuity, momentum and the energy equations governing the flow through the low-pressure cold spray nozzle were solved by introducing a constitutive equation to close the system. This was used to calculate the critical velocity for the deposition of SiC. In order to determine the input temperature that yields the calculated velocity, the distribution of velocity, temperature, and pressure in the cold spray nozzle were analyzed, and the exit values were predicted using the meshing tool of Solidworks. Coatings fabricated using the optimized parameters and some non-optimized parameters are compared. The coating of the CFD-optimized parameters yielded lower porosity and higher hardness.

  5. 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)

  6. 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.sciencedirect.com/science/article/pii/S0272884213009541#

  7. TiB2/Al2O3 ceramic particle reinforced aluminum fabricated by spray deposition

    International Nuclear Information System (INIS)

    Chen Xing; Yang Chengxiao; Guan Leding; Yan Biao

    2008-01-01

    Aluminum matrix ceramic particle reinforced composites (AMCs) is a kind of composite with great importance. Aluminum matrix composite reinforced with TiB 2 /Al 2 O 3 ceramic particles was successfully in situ synthesized in Al-TiO 2 -B 2 O 3 system in this paper, using spray deposition with hot-press treatment technique. Five groups of composites with different reinforcement volume contents were prepared and the comparisons of porosity, ultimate tensile strength (UTS), elongation and Brinell hardness (BH) between the composites with and without hot-press treating were carried out. The composite with 21.0% reinforcement volume content was analyzed by X-ray diffraction (XRD), Environmental Scanning Electron Microscope (ESEM), Transmission Electron Microscope (TEM) and Energy Disperse Spectroscopy (EDS). The results revealed the formation and uniform distribution of fine reinforcements in the matrix after hot-press treating, while a new intermetallic phase Al 3 Ti was found besides TiB 2 /Al 2 O 3 ceramic phase

  8. Structure-property relationship of ceramic coatings on metals produced by laser processing

    NARCIS (Netherlands)

    de Hosson, J.T.M.; van den Burg, M.; Mazumder, J; Conde, O; Villar, R; Steen, W

    1996-01-01

    This paper concentrates on the mechanical performance of various ceramic coatings of Cr2O3 on steel (SAF2205), as produced by CO2 laser processing. The thickness of the coating that can be applied by laser coating is limited to about 200 mu m setting a limit to the maximum strain energy release rate

  9. Adhesion of YSZ suspension plasma-sprayed coating on smooth and thin substrates

    International Nuclear Information System (INIS)

    Vert, R.; Meillot, E.; Chicot, D.; Dublanche-Tixier, C.; Vardelle, A.; Mariaux, G.

    2010-01-01

    The design concept of the gas-cooled fast reactor which is a 4. generation nuclear reactor, requires protective coatings able to operate at 850 C and protect the underlying structure in case of sudden increase of the functional temperature up to 1250 C and depressurization from 0.70 MPa to atmospheric pressure. The parts to be covered are made of 1 mm thick materials resistant to heat and erosion and exhibiting high mechanical properties at high temperatures, such as the Haynes (R)230 nickel-based alloy. In this study, the use of suspension plasma spraying to manufacture zirconia coatings is explored. The spraying conditions were optimized for the elaboration of coatings on stainless steel AISI 304L substrates and then adapted for Haynes 230 substrates. A special attention was paid to coating adhesion that was investigated by using a Vickers indentation cracking method. (authors)

  10. Modulating Drug Release from Gastric-Floating Microcapsules through Spray-Coating Layers

    Science.gov (United States)

    Tan, Chaoyang Nicholas; Loo, Say Chye Joachim

    2014-01-01

    Floating dosage forms with prolonged gastric residence time have garnered much interest in the field of oral delivery. However, studies had shown that slow and incomplete release of hydrophobic drugs during gastric residence period would reduce drug absorption and cause drug wastage. Herein, a spray-coated floating microcapsule system was developed to encapsulate fenofibrate and piroxicam, as model hydrophobic drugs, into the coating layers with the aim of enhancing and tuning drug release rates. Incorporating fenofibrate into rubbery poly(caprolactone) (PCL) coating layer resulted in a complete and sustained release for up to 8 h, with outermost non-drug-holding PCL coating layer serving as a rate-controlling membrane. To realize a multidrug-loaded system, both hydrophilic metformin HCl and hydrophobic fenofibrate were simultaneously incorporated into these spray-coated microcapsules, with metformin HCl and fenofibrate localized within the hollow cavity of the capsule and coating layer, respectively. Both drugs were observed to be completely released from these coated microcapsules in a sustained manner. Through specific tailoring of coating polymers and their configurations, piroxicam loaded in both the outer polyethylene glycol and inner PCL coating layers was released in a double-profile manner (i.e. an immediate burst release as the loading dose, followed by a sustained release as the maintenance dose). The fabricated microcapsules exhibited excellent buoyancy in simulated gastric fluid, and provided controlled and sustained release, thus revealing its potential as a rate-controlled oral drug delivery system. PMID:25470374

  11. Thermal Conductivity and Wear Behavior of HVOF-Sprayed Fe-Based Amorphous Coatings

    Directory of Open Access Journals (Sweden)

    Haihua Yao

    2017-10-01

    Full Text Available To protect aluminum parts in vehicle engines, metal-based thermal barrier coatings in the form of Fe59Cr12Nb5B20Si4 amorphous coatings were prepared by high velocity oxygen fuel (HVOF spraying under two different conditions. The microstructure, thermal transport behavior, and wear behavior of the coatings were characterized simultaneously. As a result, this alloy shows high process robustness during spraying. Both Fe-based coatings present dense, layered structure with porosities below 0.9%. Due to higher amorphous phase content, the coating H-1 exhibits a relatively low thermal conductivity, reaching 2.66 W/(m·K, two times lower than the reference stainless steel coating (5.85 W/(m·K, indicating a good thermal barrier property. Meanwhile, the thermal diffusivity of amorphous coatings display a limited increase with temperature up to 500 °C, which guarantees a steady and wide usage on aluminum alloy. Furthermore, the amorphous coating shows better wear resistance compared to high carbon martensitic GCr15 steel at different temperatures. The increased temperature accelerating the tribological reaction, leads to the friction coefficient and wear rate of coating increasing at 200 °C and decreasing at 400 °C.

  12. Nondestructive inspection of plasma-sprayed metallic coatings for coal conversion equipment

    Energy Technology Data Exchange (ETDEWEB)

    Scott, G.W.; Snyder, S.D.; Simpson, W.A. Jr.

    1979-12-01

    This report describes the results of a project to develop nondestructive inspection techniques for metallic wear- and process-resistant coatings used in coal system components. Physical properties, especially porosity, and the nominal 0.25 mm (0.010 in.) thickness complicate the inspection of these coatings. The class of coatings selected for laboratory evaluation were CoCrAlY (cobalt-chromium-aluminum-yttrium) types; the specific material used was a Union Carbide spray powder, UCAR LCO-7, which is Co-22.8% Cr-12.9% Al-0.6% Y, sprayed onto alloy 800 substrates. The desired inspection techniques were to: (1) detect cracks or holes in the coating; (2) measure the coating thickness from the coated side; and (3) detect lamellar flaws or separations within the coating layer or between the coating and the substrate. Surface methods (such as liquid penetrant), eddy currents, and radiography were investigated for crack and hole detection; eddy currents, x-ray fluorescence, and ultrasonics were investigated for thickness measurement; and ultrasonics and infrared thermography were investigated for lamellar flaw detection. In general, we determined that significant development effort was required to adapt even the more common and highly developed techniques to the coating inspection problems. Significant progress was made in a number of the investigations undertaken, but financial restraints prevented completion of the planned work.

  13. Design of novel plasma sprayed hydroxyapatite-bond coat bioceramic systems

    Science.gov (United States)

    Heimann, R. B.

    1999-12-01

    Bond coats based on bioinert ceramic materials such as titania and zirconia were developed to increase the adhesion strength of the coating system hydroxyapatite-bond coat to Ti-6Al-4V alloy surfaces used for hip endoprostheses and dental root implants. The bond coats improved the adhesion strength, measured by a modified ASTM D 3167-76 peel test, by up to 100% and also the resorption resistance as determined by in vitro leaching in simulated protein-free body fluid for up to 28 days.

  14. Corrosion And Thermal Processing In Cold Gas Dynamic Spray Deposited Austenitic Stainless Steel Coatings

    Science.gov (United States)

    2016-06-01

    testing (ASTM G5) of low pressure cold spray austenitic stainless steel coatings. Several different powders and heat treatments will be applied to...diffusion eliminating the local low chromium region. The low carbon type stainless steel alloys as used here are generally considered to be...maximum 200words) This thesis presents research on the corrosion properties and effects of heat treatment on austenitic stainless steel coatings

  15. Microstructural evolution of cold-sprayed Inconel 625 superalloy coatings on low alloy steel substrate

    International Nuclear Information System (INIS)

    Chaudhuri, Atanu; Raghupathy, Y.; Srinivasan, Dheepa; Suwas, Satyam; Srivastava, Chandan

    2017-01-01

    This study illustrates microstructural evolution of INCONEL 625 superalloy coatings cold-sprayed on a 4130 chrome alloy steel with medium carbon content. INCONEL 625 powder (5–25 μm) were successfully cold sprayed without any oxidation. The comprehensive microstructure analysis of the as-sprayed coatings and of the substrate-coating interface was carried out using EBSD, TEM, and XRD. The coating microstructure at the substrate-coating interface was markedly different from the microstructure away from the interface. The coating microstructure at steel-coating interface consisted of a fine layer of small grains. The microstructure beyond this fine layer can be divided into splats, inter splat and intra splat boundaries. Both splat and splat boundaries exhibited deformation induced dislocations. Dynamic recovery of dislocations-ridden regions inside the splat was responsible for the development of sub grain structure inside a splat with both low and high angle grain boundaries. Splat-splat (inter splat) boundary consisted of a relatively high density of dislocations and shear bands as a result of adiabatic shear flow localisation. This flow instability is believed to enhance the microstructural integrity by eliminating porosity at splat-splat boundaries. Based on the microstructural analysis using electron microscopy, a plausible mechanism for the development of microstructure has been proposed in this work. Cold spray technique can thus be deployed to develop high quality coatings of commercial importance. - Graphical abstract: Schematics of the evolution of microstructure at the 4130 steel substrate close to interface. i) initial deformation close to interface. ii) Accumulation of dislocation in the substrate. iii) Formation of cell structure due to dislocation tangling and arrangement. iv) Dislocation rearrangement and subgrain formation. v.a) Formation HAGB from dislocation accumulation into LAGB. v.b) HAGB formation through DRX by progressive lattice rotation

  16. 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.

  17. Survival of Staphylococcus aureus exposed to UV radiation on the surface of ceramic tiles coated with TiO2.

    Science.gov (United States)

    Szczawiński, J; Tomaszewski, H; Jackowska-Tracz, A; Szczawińska, M E

    2011-01-01

    The aim of this study was to determine and compare the antimicrobial activity of UV radiation of wavelength 253.7 nm (used in typical germicidal lamps) against Staphylococcus aureus on the surfaces of conventionally produced white ceramic wall tiles (matt and shiny) and the same tiles coated with TiO2 using three different methods: RF diode sputtering, atmospheric pressure chemical vapour deposition (APCVD) and spray pyrolysis deposition (SPD). Results clearly indicate that the bactericidal action of UV radiation is much stronger on the surfaces of tiles coated with TiO2 than on the tiles uncovered. The strongest bactericidal effect of UV radiation was found for film prepared by APCVD. Results of experiments for shiny and matt tiles did not differ statistically. The use of ceramic wall tiles coated with TiO2 films in hospitals, veterinary clinics, laboratories, food processing plants and other places where UV radiation is applied for disinfection should greatly improve the efficiency of this treatment.

  18. Development of wear resistant ceramic coatings for diesel engine components

    Energy Technology Data Exchange (ETDEWEB)

    Haselkorn, M.H. (Caterpillar, Inc., Peoria, IL (United States))

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at these more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.

  19. 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

  20. 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

  1. Influences of spray parameters on the structure and corrosion resistance of stainless steel layers coated on carbon steel by plasma spray treatment

    International Nuclear Information System (INIS)

    Yeom, Kyong An; Lee, Sang Dong; Kwon, Hyuk Sang; Shur, Dong Soo; Kim, Joung Soo

    1996-01-01

    Stainless steel powders were sprayed on the grit-blasted SM45C carbon steel substrates using a plasma spray method. The influences of the spray parameters on the structure and corrosion resistance of the layers coated on the carbon steel were investigated. Corrosion behavior of the layers were analyzed by the anodic polarization tests in deaerated 0.1 M NaCl + 0.01 M NaOH solution at 80 deg C. The surface roughness and porosity were observed to decrease with decreasing the particle size. The surface hardness of the coating was always higher than that of the matrix, SM45C, implying that the higher resistance of the coating to erosion-corrosion than that of matrix, and increased as the spray power and the spray distance increase. Stainless steel coats showed more corrosion resistance than the carbon steel did, due to their passivity. The corrosion resistance of the coats, however, were inferior to that of the bulk stainless steels due to the inherent defects formed in the coats. The defects such as rough surface and pores provided the occluded sites favorable for the initiation of localized corrosion, resulting in the conclusion that finer the powder is, higher the corrosion resistance is. And the Cr oxides formation resulting in Cr depletion around the oxides reduced the corrosion resistance of the coats. (author)

  2. Powder/processing/structure relationships in WC-Co thermal spray coatings: A review of the published literature

    Science.gov (United States)

    de Villiers Lovelock, H. L.

    1998-09-01

    Thermally sprayed coatings based on tungsten carbide are widely used but not yet fully understood, particularly with regard to the chemical, microstructural, and phase changes that occur during spraying and their influence on properties such as wear resistance. The available literature on thermally sprayed WC-Co coatings is considerable, but it is generally difficult to synthesize all of the findings to obtain a comprehensive understanding of the subject. This is due to the many different starting powders, spray system types, spray parameters, and other variables that influence the coating structures and cause difficulties when comparing results from different workers. The purpose of this review is to identify broad trends in the powder/processing/structure relationships of WC-Co coatings, classified according to powder type and spray method. Detailed comparisons of coating microstructures, powder phase compositions and coating phase compositions as reported by different researchers are given in tabular form and discussed. The emphasis is on the phase changes that occur during spraying. This review concerns only WC-12% Co and WC-17% Co coatings, and contrasts the coatings obtained from the cast and crushed, sintered and crushed, and agglomerated and densified powder types. Properties such as hardness, wear, or corrosion resistance are not reviewed here.

  3. Wear Resistant Thermal Sprayed Composite Coatings Based on Iron Self-Fluxing Alloy and Recycled Cermet Powders

    Directory of Open Access Journals (Sweden)

    Heikki SARJAS

    2012-03-01

    Full Text Available Thermal spray and WC-Co based coatings are widely used in areas subjected to abrasive wear. Commercial  cermet thermal spray powders for HVOF are relatively expensive. Therefore applying these powders in cost-sensitive areas like mining and agriculture are hindered. Nowadays, the use of cheap iron based self-fluxing alloy powders for thermal spray is limited. The aim of this research was to study properties of composite powders based on self-fluxing alloys and recycled cermets and to examine the properties of thermally sprayed (HVOF coatings from composite powders based on iron self-fluxing alloy and recycled cermet powders (Cr3C2-Ni and WC-Co. To estimate the properties of  recycled cermet powders, the sieving analysis, laser granulometry and morphology were conducted. For deposition of coatings High Velocity Oxy-Fuel spray was used. The structure and composition of powders and coatings were estimated by SEM and XRD methods. Abrasive wear performance of coatings was determined and compared with wear resistance of coatings from commercial powders. The wear resistance of thermal sprayed coatings from self-fluxing alloy and recycled cermet powders at abrasion is comparable with wear resistance of coatings from commercial expensive spray powders and may be an alternative in tribological applications in cost-sensitive areas.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1338

  4. Transparent electrodes made with ultrasonic spray coating technique for flexible heaters

    Science.gov (United States)

    Wroblewski, G.; Krzemiński, J.; Janczak, D.; Sowiński, J.; Jakubowska, M.

    2017-08-01

    Transparent electrodes are one of the basic elements of various electronic components. The paper presents the preliminary results related to novel method of ultrasonic spray coating used for fabrication of transparent flexible electrodes. Experiments were conducted by means of specially made laboratory setup composed of ultrasonic spray generator and XYZ plotter. In the first part of the paper diverse solvents were used to determine the crucial technological parameters such as atomization voltage and fluid flow velocity. Afterwards paint containing carbon nanotubes suspended in the two solvent system was prepared and deposited on the polyethylene terephthalate foil. Thickness, roughness and electrical measurements were performed to designate the relations of technological parameters of ultrasonic spray coating on thickness, roughness, sheet resistance and optical transmission of fabricated samples.

  5. Investigating Tribological Characteristics of HVOF Sprayed AISI 316 Stainless Steel Coating by Pulsed Plasma Nitriding

    Science.gov (United States)

    Mindivan, H.

    2018-01-01

    In this study, surface modification of aluminum alloy using High-Velocity Oxygen Fuel (HVOF) thermal spray and pulsed plasma nitriding processes was investigated. AISI 316 stainless steel coating on 1050 aluminum alloy substrate by HVOF process was pulsed plasma nitrided at 793 K under 0.00025 MPa pressure for 43200 s in a gas mixture of 75 % N2 and 25 % H2. The results showed that the pulse plasma nitriding process produced a surface layer with CrN, iron nitrides (Fe3N, Fe4N) and expanded austenite (γN). The pulsed plasma nitrided HVOF-sprayed coating showed higher surface hardness, lower wear rate and coefficient of friction than the untreated HVOF-sprayed one.

  6. Electrochemical methods for characterisation of thermal spray corrosion resistant stainless steel coatings

    NARCIS (Netherlands)

    Hofman, R.; Vreijling, M.P.W.; Ferrari, G.M.; Wit, J.H.W. de

    1998-01-01

    The use of thermal spray stainless steel coatings for protection of low alloyed steels against different types of corrosion is limited due to high porosity levels and oxide inclusions. In this paper electrochemical methods like corrosion potential monitoring and cyclic voltammetry are reported to

  7. Flame Sprayed Al-12Si Coatings for the Improvement of the Adhesion of Composite Casting Profiles

    Science.gov (United States)

    Voyer, Joël; Peterlechner, Christian; Noster, Ulf

    2008-12-01

    In this study, flame sprayed Al-12Si coatings were produced on the surface of inlays (aluminum profiles) of composite castings parts. The aim was to enhance the strength between the joining partners inlay and cast. Due to the high surface roughness and the presence of pores in the coatings, combined with the formation of an intermetallic phase at the interface, the adhesion of flame sprayed inlays could be enhanced by a factor of 2 compared to blank inlays and by a factor of 1.3 when compared to sand-blasted inlays. However, results also show that gaps are present, mostly at the interface between the inlays and the flame sprayed coatings, and these gaps have a negative effect on the joining strength of the composite casting parts. Therefore, optimizing the adhesion of the coating on the Al profiles via an improvement in both the sand-blasting and the flame spraying parameters would be beneficial for further enhancement of the adhesion of composite casting parts.

  8. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, HVLP COATING EQUIPMENT, SHARPE MANUFACTURING COMPANY PLATINUM 2012 HVLP SPRAY GUN

    Science.gov (United States)

    This report presents the results of the verification test of the Sharpe Platinum 2013 high-volume, low-pressure gravity-feed spray gun, hereafter referred to as the Sharpe Platinum, which is designed for use in automotive refinishing. The test coating chosen by Sharpe Manufacturi...

  9. 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.

  10. 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

  11. Methods of Increasing Thermal Conductivity of Plasma Sprayed Tungsten-Based Coatings

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Iždinský, K.; Vondrouš, P.

    2009-01-01

    Roč. 59, - (2009), s. 82-86 ISSN 1022-6680. [International Conference on New Materials for Extreme Environments/1st./. San Sebastian, 02.06.2008-04.06.2008] Institutional research plan: CEZ:AV0Z20430508 Keywords : Extreme environments * fusion materials * plasma sprayed coatings * thermal conductivity Subject RIV: JG - Metallurgy

  12. Plasma sprayed alumina coatings for radiation detector development

    Indian Academy of Sciences (India)

    In view of potential applications in neutron-sensitive ion chambers used in reactor control instru- mentation, studies were carried out on alumina 100 μ to 500 μ thick coatings on copper, aluminium and SS components. The electrical insulation varied from 10 ohms to 10. 骄 ohms for coating thick- nesses above 200 μ.

  13. Comparison of performance coatings thermally sprayed subject to testing adhesive wear

    International Nuclear Information System (INIS)

    Marangoni, G.F.; Arnt, A.B.C.; Rocha, M.R. da

    2014-01-01

    In this work, the microstructural changes and wear resistance adhesive coatings obtained from powders thermally sprayed by high velocity oxy-fuel (HVOF) were evaluated. Based coatings chrome-nickel and tungsten-cobalt are applied in conditions subject to intense wear especially abrasive. With the aim of evaluate the performance of these coatings under conditions of adhesive wear, these coatings samples were tested by the standard ASTM G99. As test parameters were used: Tungsten carbide pin (SAE 52100) with 6 mm diameter, normal load of 50N and a tangential velocity of 0.5 m / s. The worn surfaces of the coatings were characterized by optical and scanning electron microscopy and X-ray diffraction. Results indicate that the performance front wear is related to the conditions of adhesion and uniformity of the coating applied. (author)

  14. Influence of Starting Powders on Hydroxyapatite Coatings Fabricated by Room Temperature Spraying Method.

    Science.gov (United States)

    Seo, Dong Seok; Lee, Jong Kook; Hwang, Kyu Hong; Hahn, Byung Dong; Yoon, Seog Young

    2015-08-01

    Three types of raw materials were used for the fabrication of hydroxyapatite coatings by using the room temperature spraying method and their influence on the microstructure and in vitro characteristics were investigated. Starting hydroxyapatite powders for coatings on titanium substrate were prepared by a heat treatment at 1100 °C for 2 h of bovine bone, bone ash, and commercial hydroxyapatite powders. The phase compositions and Ca/P ratios of the three hydroxyapatite coatings were similar to those of the raw materials without decomposition or formation of a new phase. All hydroxyapatite coatings showed a honeycomb structure, but their surface microstructures revealed different features in regards to surface morphology and roughness, based on the staring materials. All coatings consisted of nano-sized grains and had dense microstructure. Inferred from in vitro experiments in pure water, all coatings have a good dissolution-resistance and biostability in water.

  15. Mechanical and physical properties of plasma-sprayed stabilized zirconia

    Science.gov (United States)

    Siemers, P. A.; Mehan, R. L.

    1983-01-01

    Physical and mechanical properties were determined for plasma-sprayed MgO- or Y2O3-stabilized ZrO2 thermal barrier coatings. Properties were determined for the ceramic coating in both the freestanding condition and as-bonded to a metal substrate. The properties of the NiCrAlY bond coating were also investigated.

  16. Effects of Traverse Scanning Speed of Spray Nozzle on the Microstructure and Mechanical Properties of Cold-Sprayed Ti6Al4V Coatings

    Science.gov (United States)

    Tan, Adrian Wei-Yee; Sun, Wen; Phang, Yun Peng; Dai, Minghui; Marinescu, Iulian; Dong, Zhili; Liu, Erjia

    2017-10-01

    Cold spray has the potential to restore damaged aerospace components made from titanium alloy, Ti6Al4V at low temperature (200-400 °C). Traverse scanning speed during deposition is one of the key factors that affect the quality of the Ti6Al4V coatings as it influences the thermal build-up and coating thickness per pass. As there are fewer reported studies on this, this work investigated the effects of different traverse scanning speeds (100, 300 and 500 mm/s) of cold spray nozzle on the microstructure and mechanical properties of cold-sprayed Ti6Al4V coatings. The cross-sectional analysis showed coating porosities reduces with slower traverse speed, from 3.2 to 0.5%. In addition, the microhardness of the coatings increased from about 361-385 HV due to strain hardening. However, the adhesion strength of the coatings to the substrates significantly decreased with reduced traverse speed from about 60 MPa (glue failure) at 500 mm/s to 2.5 MPa (interface failure) at 100 mm/s. Therefore, this study revealed that the control of heat build-up and thickness per pass during the cold spray deposition of the Ti6Al4V coatings is crucial to attain the desirable properties of the coatings.

  17. Polyurethane spray coating of aluminum wire bonds to prevent corrosion and suppress resonant oscillations

    CERN Document Server

    Izen, Joseph; The ATLAS collaboration; Kurth, Matthew Glenn

    2015-01-01

    Unencapsulated aluminum wedge wire bonds are common in particle-physics pixel and strip detectors. Industry-favored bulk encapsulation is eschewed due to the range of operating temperatures and radiation. Wire bond failures are a persistent, source of tracking detector failure Unencapsulated bonds are vulnerable to condensation-induced corrosion, particularly when halides are present. Oscillations from periodic Lorenz forces are documented as another source of wire bond failure. Spray application of polyurethane coatings, performance of polyurethane-coated wire bonds after climate chamber exposure, and resonant properties of PU-coated wire bonds and their resistance to periodic Lorenz forces will be described.

  18. Alternative Gas Mixtures in Arc Spraying: A Chance to Improve Coating Properties and Residual Stress States

    Science.gov (United States)

    Hauer, Michél; Henkel, Knuth Michael; Krebs, Sebastian; Kroemmer, Werner

    2018-01-01

    The highly cavitation erosion-resistant propeller alloys CuAl9Ni5Fe4Mn (Ni-Al-Bronze) and CuMn13Al8Fe3Ni2 (Mn-Al-Bronze) were arc-sprayed using a mixture of nitrogen and 2% of hydrogen as atomizing gas and different traverse speeds. The objective was to identify the influences of the different spraying conditions, such as temperature regime and melting loss, on the resulting residual stress states and coating properties. Residual stresses were measured by the incremental hole-drilling method using ESPI. Temperature measurements were carried out by thermographic imaging. Microstructural, chemical and mechanical analyses were realized to examine adhesive and cohesive properties. Additionally, the cavitation erosion behavior was investigated to analyze cohesive coating properties. The spraying process itself was improved, which was apparent by mainly enhanced deposition efficiency and reduced surface temperatures. The amount of oxides and pores as well as the melting loss of alloying elements were reduced. Moreover, an increased cavitation erosion resistance and thus coating cohesion as well as less residual stresses were identified. The change in atomizing gas diminished the impact of the quenching stresses on the coating properties. In contrast, the adhesive strength, Young's moduli and partially the hardness were slightly reduced. With regard to materials, Ni-Al-Bronze revealed superior coating properties in comparison with Mn-Al-Bronze.

  19. Study on modernization processes in the coating metal surfaces (plain bearings by thermal spraying

    Directory of Open Access Journals (Sweden)

    Elena IRIMIE

    2011-09-01

    Full Text Available Knowledge accumulated within the metal coating through thermal spraying allows the understanding of aspects related to the coat structure phenomena, in this case of the routs that need to be followed in order to create strong and stabile connections between the coats subsided through thermal spraying, between the particles that compose those coats, respectively. However, all this knowledge does not ensure the understanding of some practical situations that are apparently paradoxes, as for instance the absence of tin bronze adherence to ignobly steel holders, the perfect adherence of bronze to the aluminum on the same types of holders, in the context in which both elements, tin and aluminum, respectively are found in equal quantity in the two type of bonze that maintain them in solid solutions (below 10%.The parallel study in the sinter antifriction domain has offered information regarding the optimal correlation between the composition of antifriction material and the required type of application, the optimal pinches level and the way that this morphological characteristic may be influenced. By experimental research it is necessary to determine the conditions under which such coverage can be obtained by thermal spraying of the metal coatings.

  20. Development of HVOF Sprayed Erosion/Oxidation Resistant Coatings for Composite Structural Components in Propulsion Systems

    Science.gov (United States)

    Knight, R.; Ivosevic, M.; Twardowski, T. E.; Kalidindi, S. R.; Sutter, James K.; Kim, D. Y.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Thermally sprayed coatings are being studied and developed as methods of enabling lightweight composites to be used more extensively as structural components in propulsion applications in order to reduce costs and improve efficiency through weight reductions. The primary goal of this work is the development of functionally graded material [FGM] polymer/metal matrix composite coatings to provide improved erosion/oxidation resistance to polyimide-based polymer matrix composite [PMC] substrates. The goal is to grade the coating composition from pure polyimide, similar to the PMC substrate matrix on one side, to 100 % WC-Co on the other. Both step-wise and continuous gradation of the loading of the WC-Co reinforcing phase are being investigated. Details of the coating parameter development will be presented, specifically the high velocity oxy-fuel [HVOF] combustion spraying of pure PMR-11 matrix material and layers of various composition PMR-II/WC-Co blends onto steel and PMR-15 composite substrates. Results of the HVOF process optimization, microstructural characterization, and analysis will be presented. The sprayed coatings were evaluated using standard metallographic techniques - optical and scanning electron microscopy [SEM]. An SEM + electron dispersive spectroscopy [EDS] technique has also been used to confirm retention of the PMR-II component. Results of peel/butt adhesion testing to determine adhesion will also be presented.

  1. Friction in Sliding Orthodontic Mechanics: Ceramic Brackets, Teflon-Coated Wires and Comparative Resistances

    Science.gov (United States)

    1989-01-01

    N Tn FRICTION IN SLIDING ORTHODONTIC MECHANICS: N CERAMIC BRACKETS, TEFLON-COATED WIRES , AND COMPARATIVE RESISTANCES 0 DTICSFLECTED James R. Gill1...obsolete. SECURITY CLASSIFICATION OF THIS PAGE AFIT/CI "OVERPRINT" I FRICTION IN SLIDING ORTHODONTIC MECHANICS: CERAMIC BRACKETS, TEFLON-COATED WIRES ...brackets, arch- wires , and ligations during simulated orthodontic edgewise sliding mechanics. Independent variables and their values were 1) bracket

  2. Hybrid Plasma-Sprayed Thermal Barrier Coatings Using Powder and Solution Precursor Feedstock

    Science.gov (United States)

    Joshi, S. V.; Sivakumar, G.; Raghuveer, T.; Dusane, R. O.

    2014-04-01

    A novel approach of hybridizing the conventional atmospheric plasma spraying (APS) technique with the solution precursor plasma spray (SPPS) route to achieve thermal barrier coatings (TBCs) with tailored configurations is presented. Such a hybrid process can be conveniently adopted for forming composite, multi-layered and graded coatings employing simultaneous and/or sequential feeding of solution precursor as well as powder feedstock, yielding distinct TBC microstructures that bear promise to further extend coating durability. TBC specimens generated using conventional APS technique, the SPPS method and through APS-SPPS hybrid processing have been comprehensively characterized for microstructure, phase constitution, hardness and thermal cycling life, and the results were compared to demonstrate the advantages that can ensue from hybrid processing.

  3. Laser Annealing for Gas-Dynamical Spraying of HA Coating upon a Titanium Surface

    Directory of Open Access Journals (Sweden)

    Victor Saphronov

    2015-10-01

    Full Text Available Laser post-heating computer controlled detonation spraying (CCDS and cold spray (CS hybrid processes were proposed for fabrication of near sub micron structure coatings of hydroxyapatite (HA + Ti system. Optical and SEM with energy dispersive X-ray analysis and comparative XRD phase analysis were used to evaluate microstructure. After those hybrid processes, no substantial variation in HA composition was noted by structural and phase examination. Nano-sized HA powders can be recommended for laser annealing CS (LaCS process. Regimes of laser treatment optimal for increasing the adhesion between the HA and titanium coatings, providing more strength, ductility and decreasing of HA destruction in the coatings were determined.

  4. Enhancement of low pressure cold sprayed copper coating adhesion by laser texturing on aluminum substrates

    Science.gov (United States)

    Knapp, Wolfgang; Gillet, Vincent; Courant, Bruno; Aubignat, Emilie; Costil, Sophie; Langlade, Cécile

    2017-02-01

    Surface pre-treatment is fundamental in thermal spraying processes to obtain a sufficient bonding strength between substrate and coating. Different pre-treatments can be used, mostly grit-blasting for current industrial applications. This study is focused on Cu-Al2O3 coatings obtained by Low Pressure Cold Spray on AW5083 aluminum alloy substrate. Bonding strength is measured by tensile adhesion test, while deposition efficiency is measured. Substrates are textured by laser, using a pattern of equally spaced grooves with almost constant diameter and variations of depth. Results show that bonding strength is improved up to +81% compared to non-treated substrate, while deposition efficiency remains constant. The study of the samples after rupture reveals a modification of the failure mode, from mixed failure to cohesive failure. A modification of crack propagation is also noticed, the shape of laser textured grooves induces a deviation of cracks inside the coating instead of following the interface between the layers.

  5. Synthesis and Behavior of Nanostructured Coatings Using Thermal Spraying

    National Research Council Canada - National Science Library

    Lavernia, E

    2003-01-01

    ... (powder as well as coatings) for structure, composition, properties, and performance. One of the program's accomplishments was the successful synthesis of diverse nanostructured feedstock powders using mechanical milling in different...

  6. Coated particle waste form development

    Energy Technology Data Exchange (ETDEWEB)

    Oma, K.H.; Buckwalter, C.Q.; Chick, L.A.

    1981-12-01

    Coated particle waste forms have been developed as part of the multibarrier concept at Pacific Northwest Laboratory under the Alternative Waste Forms Program for the Department of Energy. Primary efforts were to coat simulated nuclear waste glass marbles and ceramic pellets with low-temperature pyrolytic carbon (LT-PyC) coatings via the process of chemical vapor deposition (CVD). Fluidized bed (FB) coaters, screw agitated coaters (SAC), and rotating tube coaters were used. Coating temperatures were reduced by using catalysts and plasma activation. In general, the LT-PyC coatings did not provide the expected high leach resistance as previously measured for carbon alone. The coatings were friable and often spalled off the substrate. A totally different concept, thermal spray coating, was investigated at PNL as an alternative to CVD coating. Flame spray, wire gun, and plasma gun systems were evaluated using glass, ceramic, and metallic coating materials. Metal plasma spray coatings (Al, Sn, Zn, Pb) provided a two to three orders-of-magnitude increase in chemical durability. Because the aluminum coatings were porous, the superior leach resistance must be due to either a chemical interaction or to a pH buffer effect. Because they are complex, coated waste form processes rank low in process feasibility. Of all the possible coated particle processes, plasma sprayed marbles have the best rating. Carbon coating of pellets by CVD ranked ninth when compared with ten other processes. The plasma-spray-coated marble process ranked sixth out of eleven processes.

  7. Coated particle waste form development

    International Nuclear Information System (INIS)

    Oma, K.H.; Buckwalter, C.Q.; Chick, L.A.

    1981-12-01

    Coated particle waste forms have been developed as part of the multibarrier concept at Pacific Northwest Laboratory under the Alternative Waste Forms Program for the Department of Energy. Primary efforts were to coat simulated nuclear waste glass marbles and ceramic pellets with low-temperature pyrolytic carbon (LT-PyC) coatings via the process of chemical vapor deposition (CVD). Fluidized bed (FB) coaters, screw agitated coaters (SAC), and rotating tube coaters were used. Coating temperatures were reduced by using catalysts and plasma activation. In general, the LT-PyC coatings did not provide the expected high leach resistance as previously measured for carbon alone. The coatings were friable and often spalled off the substrate. A totally different concept, thermal spray coating, was investigated at PNL as an alternative to CVD coating. Flame spray, wire gun, and plasma gun systems were evaluated using glass, ceramic, and metallic coating materials. Metal plasma spray coatings (Al, Sn, Zn, Pb) provided a two to three orders-of-magnitude increase in chemical durability. Because the aluminum coatings were porous, the superior leach resistance must be due to either a chemical interaction or to a pH buffer effect. Because they are complex, coated waste form processes rank low in process feasibility. Of all the possible coated particle processes, plasma sprayed marbles have the best rating. Carbon coating of pellets by CVD ranked ninth when compared with ten other processes. The plasma-spray-coated marble process ranked sixth out of eleven processes

  8. Transfer of Wire Arc-Sprayed Metal Coatings onto Plastic Parts

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Knoch, M. A.; Liao, X.; Hopmann, Ch.; Ochotta, P.

    2018-01-01

    By means of In-Mold-Metal-Spraying (IMMS), metal coatings deposited by means of arc spraying process (ASP) can be transferred onto plastic parts during injection molding, thus realizing an efficient production of metallized plastic parts. Parts produced by means of IMMS can be used in electrical applications. In the current study, the electrical resistivity of coatings applied with different feedstock materials was determined. As a starting point, pressurized air is used as atomizing gas for ASP. In contrast to Zn coatings, Cu coatings applied with pressurized air exhibit a significantly higher electrical resistivity in comparison with massive material. One possible reason is the more pronounced oxidation of Cu particles during ASP. Therefore, N2 and a mixture of N2 and H2 were used as atomizing gas. As a result, the electrical resistivity of coatings applied by means of IMMS could be significantly reduced. Furthermore, standoff distance, current and pressure of the atomizing gas were varied to investigate the influence of these process parameters on the electrical resistivity of Zn coatings using a full factorial experiment design with center point. It can be observed that the electrical resistivity of the Zn coatings increases with decreasing current and increasing standoff distance and pressure.

  9. Development and Characterization of B4C Reinforced Detonation-Sprayed Al Coatings

    Science.gov (United States)

    Tillmann, W.; Hollingsworth, P. S.; Fischer, G.; Nellesen, J.; Beckmann, F.

    2014-02-01

    Because of their excellent properties aluminum and its alloys cover a wide range of applications especially in the lightweight construction sector. In order to reach a higher strength and wear resistance metal matrix composites (MMCs) are used. Typically Al MMCs are manufactured by casting or extrusion processes. The disadvantage of these production routes is a cost-intensive and time-consuming finishing in terms of grinding and milling. The technique of thermal spraying provides the possibility to coat aluminum parts with MMCs close to their final shape. In addition to the shape accuracy the ductility and toughness of the coated parts are generally higher compared to extruded or casted parts. This study describes the development of detonation-sprayed boron carbide reinforced aluminum coatings on aluminum (EN AW 5754) substrates. The optimization of the coatings was focused on a homogeneous coating structure, a low coating porosity, a high deposition efficiency, a high number of embedded carbides, and a small percentage of oxides. In continuous tensile tests the influence of the MMC coating on the tensile strength was determined. Furthermore, the tensile strength was investigated in a discontinuous tensile test step by step. The different stages of deformation were analyzed by using micro computed tomography. This method enables the observation of tensile specimens in 3D, and consequently the site and moment of crack formation.

  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. Evaluation of surface residual stresses in HVOF sprayed WC-12Co coatings by XRD and ED-hole drilling

    Energy Technology Data Exchange (ETDEWEB)

    Azizpour, M. Jalali; Nourouzi, S. [Babol University of Technology, Babol (Iran, Islamic Republic of)

    2013-09-15

    Thermally sprayed coatings are inherently associated with residual stresses in the coatings. These stresses have a noticeable effect on the physical and mechanical properties of coatings. The high speed hole drilling method is widely used to measure the residual stress. Due to the nature of the thermally sprayed coatings, the application of this method for WC/Co coatings has some limitations. In the current study, WC-12Co coatings were deposited using HVOF thermal spraying. The electro discharge hole drilling method was developed to measure the through thickness residual stress in WC-Co thermally sprayed coatings. Morphological studies were conducted using optical microscopy and scanning electron microscopy (SEM) to evaluate the powder and coating characteristics. The sin2ψ method was used to evaluate the surface residual stress by means of XRD. The residual stress at the surface using EDM and XRD was approximately -32.54 MPa and -40.6 MPa respectively. The experimental results reveal that the stress curves are not uniform through the coating thickness. It has been found that the mean residual stress is of approximately -126 MPa. Obtained results are in good agreement with the reported values from literatures. The developed method confirms the feasibility of residual stresses measurement for HVOF thermally sprayed WC-Co coatings.

  12. Fabrication of CIS Absorber Layers with Different Thicknesses Using A Non-Vacuum Spray Coating Method

    Directory of Open Access Journals (Sweden)

    Chien-Chen Diao

    2014-01-01

    Full Text Available In this study, a new thin-film deposition process, spray coating method (SPM, was investigated to deposit the high-densified CuInSe2 absorber layers. The spray coating method developed in this study was a non-vacuum process, based on dispersed nano-scale CuInSe2 precursor and could offer a simple, inexpensive, and alternative formation technology for CuInSe2 absorber layers. After spraying on Mo/glass substrates, the CuInSe2 thin films were annealed at 550 °C by changing the annealing time from 5 min to 30 min in a selenization furnace, using N2 as atmosphere. When the CuInSe2 thin films were annealed, without extra Se or H2Se gas used as the compensation source during the annealing process. The aim of this project was to investigate the influence of annealing time on the densification and crystallization of the CuInSe2 absorber layers to optimize the quality for cost effective solar cell production. The thickness of the CuInSe2 absorber layers could be controlled as the volume of used dispersed CuInSe2-isopropyl alcohol solution was controlled. In this work, X-ray diffraction patterns, field emission scanning electron microscopy, and Hall parameter measurements were performed in order to verify the quality of the CuInSe2 absorber layers obtained by the Spray Coating Method.

  13. 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.

  14. Ultra High Temperature and Multifunctional Ceramic Matrix Composite – Coating Systems for Light-Weight Space and Aero Systems

    Data.gov (United States)

    National Aeronautics and Space Administration — Revolutionary ultra-high temperature, high mechanical loading capable, oxidation resistant, durable ceramic coatings and light-weight fiber-reinforced Ceramic Matrix...

  15. Chemical states and deuterium retention behavior of vacuum plasma sprayed tungsten coatings

    International Nuclear Information System (INIS)

    Niu Yaran; Suzuki, Sachiko; Zheng Xuebin; Ding Chuanxian; Chen Junling; Wang Wanjing; Oya, Yasuhisa; Okuno, Kenji

    2011-01-01

    Tungsten (W) coatings were prepared using vacuum plasma spraying (VPS) technology and then the chemical states and retention behaviors of deuterium in VPS-W coatings were analyzed by X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). The results showed that chemical reacted oxygen (W-O bonds) and chemisorbed oxygen (O-O bonds) existed both on the surface and interior of tungsten coatings. Oxygen was chemically sputtered during D 2 + implantation. Two deuterium desorption stages at the temperature ranges around 300-700 K and 800-1150 K were observed for tungsten coatings. The retention behavior of deuterium in tungsten coatings was greatly different from that of bulk tungsten, which was related to the existence of oxygen.

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

    International Nuclear Information System (INIS)

    Kim, Dae Jin; Lee, Dong Hoon; Koo, Jae Mean; Song, Sung Jin; Seok, Chang Sung; Kim, Mun Young

    2008-01-01

    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

  17. 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.

  18. 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.

  19. Development of a biodegradable sirolimus-eluting stent coated by ultrasonic atomizing spray.

    Science.gov (United States)

    Kim, Soon-Joong; Park, Jae-Geun; Kim, Jung Ho; Heo, Jung Sun; Choi, Jeong-Woo; Jang, Yang-Soo; Yoon, Junghan; Lee, Seung Jin; Kwon, Il Keun

    2011-07-01

    In this study, poly(D,L lactic-co-glycolic acid) (PLGA) was used as a drug carrier to generate two types of stents loaded with different concentrations of sirolimus. These stents were prepared by ultrasonic atomizing spray coating. Ultrasonic atomizing spray nozzle uses a low-pressure air/gas to produce a soft, highly focused beam of small spray drops. An isolated hypotube delivers liquid to the nozzle's atomizing surface while air/gas, delivered through the nozzle orifice at a fixed low pressure, shapes the atomized drops into a very precise, targeted spray. The stent was moved both in the traverse direction and rotated during the spraying process. The morphology of the sirolimus-eluting stents was examined by scanning electron microscopy (SEM) which indicated that the coating was very smooth and uniform. The coating was found to have the ability to withstand the compressive and tensile strains imparted without cracking during the stent inflation process. Release profile of sirolimus was measured by high performance liquid chromatography (HPLC). The release behavior of sirolimus from the stent surface had a two phase release profile with a burst release period of about 2 days, followed by a sustained and slow release phase. The mass loss behavior of PLGA appeared linear throughout most of the degradation period. At 28 days, neointimal formation was found to be significantly decreased for both sirolimus-eluting stents as compared to bare-metal stents (BMS). Assessment of vascular healing revealed an absence of increased inflammation in both sirolimus-eluting stents. Inflammation is commonly observed in drug-eluting stents (DES) with nonbiodegradable polymeric coatings. Taking these results into account, these novel sirolimus-eluting stents may be good candidates to resolve in-stent restenosis.

  20. Characterization and High-Temperature Erosion Behaviour of HVOF Thermal Spray Cermet Coatings

    Science.gov (United States)

    Kumar, Pardeep; Sidhu, Buta Singh

    2016-01-01

    High-velocity oxygen fuel (HVOF) thermal spray, carbide-cermet-based coatings are usually employed in high-temperature erosive and erosive-corrosive environments. Extensive literature is available on high-temperature erosion performance of HVOF coatings under moderate to low particle flux and velocities for application in boiler tubes. This research work presents the characterization and high-temperature erosion behaviour of Cr3C2-25NiCr and WC-10Co-4Cr HVOF-sprayed coatings. Coatings were formulated on the substrate steel of type AISI 304, commonly used for the fabrication of pulverized coal burner nozzles (PCBN). Erosion testing was carried out in high-temperature air-jet erosion tester after simulating the conditions akin to that prevailing in PCBN in the boiler furnace. The coatings were tested for erosion behaviour at different angles and temperatures by freezing other test parameters. Brittle erosion behaviour was depicted in erosion testing, and the coatings couldn't restrain the erodent attacks to protect the substrate. High particle velocity and high particle flux were attributed to be the reasons of extensive erosive weight loss of the coatings. The surface morphology of the eroded specimens was analysed from back-scattered electron images to depict the probable mechanism of material removal. The coatings were characterized with optical microscopy, SEM-EDS analysis, XRD analysis, micro-hardness testing, porosity measurements, surface roughness testing and bond strength testing. The work was undertaken to investigate the performance of the selected coatings in highly erosive environment, so as to envisage their application in PCBNs for protection against material degradation. The coatings could only sustain in oblique impact erosion at room temperature and depleted fully under all other conditions.

  1. Neutron and X-ray diffraction of plasma-sprayed zirconia-yttria thermal barrier coatings

    Science.gov (United States)

    Shankar, N. R.; Herman, H.; Singhal, S. P.; Berndt, C. C.

    1984-01-01

    ZrO2-7.8mol. pct. YO1.5, a fused powder, and ZrO2-8.7mol. pct. YO1.5, a prereacted powder, were plasma-sprayed onto steel substrates. Neutron diffraction and X-ray diffraction of the as-received powder, the powder plasma sprayed into water, as-sprayed coatings, and coatings heat-treated for 10 and 100 h were carried out to study phase transformations and ordering of the oxygen ions on the oxygen sublattice. The as-received fused powder has a much lower monoclinic percentage than does the pre-reacted powder, this resulting in a much lower monoclinic percentage in the coating. Heat treatment increases the percentages of the cubic and monoclinic phases, while decreasing the tetragonal content. An ordered tetragonal phase is detected by the presence of extra neutron diffraction peaks. These phase transformations and ordering will result in volume changes. The implications of these transformations on the performance of partially stabilized zirconia thermal barrier coatings is discussed.

  2. Application of Plasma Sprayed Zirconia Coating in Dental Implant: Study in Implant.

    Science.gov (United States)

    Huang, Zhengfei; Wang, Zhifeng; Li, Chuanhua; Yin, Kaifeng; Hao, Dan; Lan, Jing

    2018-01-05

    The aim was to investigate the osseointegration of a novel coating-plasma-sprayed nanostructured zirconia (NSZ) in dental implant. Nanostructured zirconia coating on non-thread titanium implant was prepared by plasma spraying, the implant surface morphology, surface roughness and wettability were measured. In vivo, nanostructured zirconia-coated implants were inserted in rabbit tibia and animals were respectively sacrificed at 2, 4, 8 and 12 weeks after implantation. The bond strength between implant and bone was measured by removal torque (RTQ) test. The osseointegration was observed by scanning electron microscopy (SEM), micro computed tomography (Micro CT) and histological analyses. Quantified parameters were calculated, including removal torque, Bone Volume to Tissue Volume (BV/TV), Trabecular Thickness (Tb. Th), Trabecular Number (Tb. N), Trabecular Separation/Spacing (Tb. Sp), and Bone-Implant contact (BIC) percentage. The statistical differences were detected by two-tail Mann-Whitney U test (SPSS 20.0). The surface roughness (1.58µm) and wettability (54.61°) of nanostructured zirconia coated implant was more suitable than those of titanium implant (0.598µm and 74.38°) for osseointegration and hierarchical surface morphology could be seen on zirconia coating. The histological analyses showed that zirconia coated implant induced earlier and more condensed bone formation than titanium implant at 2 and 4 weeks. Quantified parameters showed the significant differences between these two groups at early healing period, but the differences between these two groups decreased with the increase of healing period. All these results demonstrated that plasma sprayed zirconia coated implant induced better bone formation than titanium implant at early stage.

  3. Fabrication and Microstructure of Hydroxyapatite Coatings on Zirconia by Room Temperature Spray Process.

    Science.gov (United States)

    Seo, Dong Seok; Chae, Hak Cheol; Lee, Jong Kook

    2015-08-01

    Hydroxyapatite coatings were fabricated on zirconia substrates by a room temperature spray process and were investigated with regards to their microstructure, composition and dissolution in water. An initial hydroxyapatite powder was prepared by heat treatment of bovine-bone derived powder at 1100 °C for 2 h, while dense zirconia substrates were fabricated by pressing 3Y-TZP powder and sintering it at 1350 °C for 2 h. Room temperature spray coating was performed using a slit nozzle in a low pressure-chamber with a controlled coating time. The phase composition of the resultant hydroxyapatite coatings was similar to that of the starting powder, however, the grain size of the hydroxyapatite particles was reduced to about 100 nm due to their formation by particle impaction and fracture. All areas of the coating had a similar morphology, consisting of reticulated structure with a high surface roughness. The hydroxyapatite coating layer exhibited biostability in a stimulated body fluid, with no severe dissolution being observed during in vitro experimentation.

  4. Microstructural Characteristics and Tribological Behavior of HVOF-Sprayed Novel Fe-Based Alloy Coatings

    Directory of Open Access Journals (Sweden)

    Andrea Milanti

    2014-01-01

    Full Text Available Thermally-sprayed Fe-based coatings have shown their potential for use in wear applications due to their good tribological properties. In addition, these kinds of coatings have other advantages, e.g., cost efficiency and positive environmental aspects. In this study, the microstructural details and tribological performances of Fe-based coatings (Fe-Cr-Ni-B-C and Fe-Cr-Ni-B-Mo-C manufactured by High Velocity Oxygen Fuel (HVOF thermal spray process are evaluated. Traditional Ni-based (Ni-Cr-Fe-Si-B-C and hard-metal (WC-CoCr coatings were chosen as references. Microstructural investigation (field-emission scanning electron microscope FESEM and X-Ray diffractometry XRD reveals a high density and low oxide content for HVOF Fe-based coatings. Particle melting and rapid solidification resulted in a metastable austenitic phase with precipitates of mixed carbides and borides of chromium and iron which lead to remarkably high nanohardness. Tribological performances were evaluated by means of the ball on-disk dry sliding wear test, the rubber-wheel dry particle abrasion test, and the cavitation erosion wear test. A higher wear resistance validates Fe-based coatings as a future alternative to the more expensive and less environmentally friendly Ni-based alloys.

  5. Surface roughness reduction using spray-coated hydrogen silsesquioxane reflow

    Science.gov (United States)

    Cech, Jiri; Pranov, Henrik; Kofod, Guggi; Matschuk, Maria; Murthy, Swathi; Taboryski, Rafael

    2013-09-01

    Surface roughness or texture is the most visible property of any object, including injection molded plastic parts. Roughness of the injection molding (IM) tool cavity directly affects not only appearance and perception of quality, but often also the function of all manufactured plastic parts. So called “optically smooth” plastic surfaces is one example, where low roughness of a tool cavity is desirable. Such tool surfaces can be very expensive to fabricate using conventional means, such as abrasive diamond polishing or diamond turning. We present a novel process to coat machined metal parts with hydrogen silsesquioxane (HSQ) to reduce their surface roughness. Results from the testing of surfaces made from two starting roughnesses are presented; one polished with grit 2500 sandpaper, another with grit 11.000 diamond polishing paste. We characterize the two surfaces with AFM, SEM and optical profilometry before and after coating. We show that the HSQ coating is able to reduce peak-to-valley roughness more than 20 times on the sandpaper polished sample, from 2.44(±0.99) μm to 104(±22) nm and more than 10 times for the paste polished sample from 1.85(±0.63) μm to 162(±28) nm while roughness averages are reduced 10 and 3 times respectively. We completed more than 10,000 injection molding cycles without detectable degradation of the HSQ coating. This result opens new possibilities for molding of affordable plastic parts with perfect surface finish.

  6. Effect of Simulated High Hydrogen Content Combustion Environments on Abradable Properties of Ceramic Turbine Coatings

    OpenAIRE

    Basu Majumder, Madhura

    2015-01-01

    Air plasma sprayed (APS) abradable coatings are used in the turbine hot section to reduce the stator-rotor gap, minimizing gas leakage. These coatings are designed to exhibit controlled removal of material in thin layers when the turbine blades sweep through the coating, which protects the mechanical integrity of the turbine blade. In an effort to lower CO2 emissions, high H2 content fuel is being explored. This change in chemical composition of the fuel may affect the microstructure, abradab...

  7. Evaluation of coat uniformity and taste-masking efficiency of irregular-shaped drug particles coated in a modified tangential spray fluidized bed processor.

    Science.gov (United States)

    Xu, Min; Heng, Paul Wan Sia; Liew, Celine Valeria

    2015-01-01

    To explore the feasibility of coating irregular-shaped drug particles in a modified tangential spray fluidized bed processor (FS processor) and evaluate the coated particles for their coat uniformity and taste-masking efficiency. Paracetamol particles were coated to 20%, w/w weight gain using a taste-masking polymer insoluble in neutral and basic pH but soluble in acidic pH. In-process samples (5, 10 and 15%, w/w coat) and the resultant coated particles (20%, w/w coat) were collected to monitor the changes in their physicochemical attributes. After coating to 20%, w/w coat weight gain, the usable yield was 81% with minimal agglomeration (processor shows promise for direct coating of irregular-shaped drug particles with wide size distribution. The coated particles with 15% coat were sufficiently taste masked and could be useful for further application in orally disintegrating tablet platforms.

  8. Electrically conductive, black thermal control coatings for spacecraft applications. III - Plasma-deposited ceramic matrix

    Science.gov (United States)

    Hribar, V. F.; Bauer, J. L.; O'Donnell, T. P.

    1987-01-01

    Five black, electrically-conductive thermal control coatings have been formulated and tested for application on the Galileo spacecraft. The coatings consist of both organic and inorganic systems applied on titanium, aluminum, and glass/epoxy composite surfaces. The coatings were tested under simulated space environment conditions. Coated specimens were subjected to thermal radiation, convective and combustive heating, and cryogenic conditions over a temperature range between -196 C and 538 C. Mechanical, physical, thermal, electrical, and thermooptical properties are presented for one of these coatings. This paper describes the preparation, characteristics, and spraying of iron titanate on titanium and aluminum, and presents performance results.

  9. The use of electrochemical measurement techniques towards quality control and optimisation of corrosion properties of thermal spray coatings

    NARCIS (Netherlands)

    Vreijling, M.P.W.; Hofman, R.; Westing, E.P.M. van; Ferrari, G.M.; Wit, J.H.W. de

    1998-01-01

    Metal spray coatings are ever more recognised as a possible superior means of corrosion protection in many environments. Extended service life combined with little or no maintenance provides interesting opportunities for both environmentalists and corrosion engineers. Although many successful

  10. 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...

  11. Validation of HVOF WC/Co Thermal Spray Coatings as a Replacement for Hard Chrome Plating on Aircraft Landing Gear

    National Research Council Canada - National Science Library

    Sartwell, Bruce

    2004-01-01

    .... This document constitutes the final report on a project to quality high-velocity oxygen-fuel (HVOF) thermal spray WC/Co coatings as a replacement for hard chrome plating on landing gear components...

  12. Elastic moduli and elastic anisotropy of cold sprayed metallic coatings

    Czech Academy of Sciences Publication Activity Database

    Seiner, Hanuš; Cizek, J.; Sedlák, Petr; Huang, R.; Cupera, J.; Dlouhý, I.; Landa, Michal

    2016-01-01

    Roč. 291, April (2016), s. 342-347 ISSN 0257-8972 R&D Projects: GA ČR GA13-13616S; GA ČR(CZ) GA13-35890S Grant - others:NETME Centre Plus - národní program udržitelnosti(CZ) LO1202 Institutional support: RVO:61388998 Keywords : kinetic spray * CGDS * elastic properties * metals and alloys * deposition * resonant ultrasound spectroscopy Subject RIV: JG - Metallurgy Impact factor: 2.589, year: 2016 http://ac.els-cdn.com/S0257897216301165/1-s2.0-S0257897216301165-main.pdf?_tid=1083617a-017f-11e6-92e7-00000aacb361&acdnat=1460555773_2e80d3df20843f3af649bf3ac71c8844

  13. Polyurethane/polysiloxane ceramer coatings: Corrosion resistant unicoat system for aircraft application

    Science.gov (United States)

    Ni, Hai

    New organic/inorganic ceramer coating system was developed using polyurethane as an organic phase and polysiloxane as the inorganic phase. The objective of the study was to develop a unicoat corrosion resistant coating which strongly adheres to aluminum substrates. The pre-ceramic silicon-oxo clusters react with the metal substrate, protecting it from oxidation, whereas the organic composition functions as a binder providing mechanical properties, optical properties, and chemical, wear and fluid resistance. The new ceramer coatings were evaluated as a replacement for chromate based coatings. The alkoxysilane-functionalized coupling agent was prepared from hexamethylene diisocyanate (HDI) isocyanurate and 3-aminopropyltriethoxysilane. The functionalized isocyanurate was characterized by 1H, 13C and 29Si NMR and electrospray ionization-mass spectrometry. An organic/inorganic hybrid coating system was formulated using the alkoxysilane-functionalized isocyanurate and HDI isocyanurate. The coating properties indicated that alkoxysilane-functionalized isocyanurate enhanced adhesion up to 500%. Based on the hybrid polyurea/alkoxysilane system, the polyurea/polysiloxane ceramer coating system was formulated with tetraethyl orthosilicate (TEOS) oligomers. Evaluation of ceramer coatings showed that coating properties were affected by both the concentration of TEOS oligomers and alkoxysilane functionalized isocyanurate. In addition, the para-toluene sulfonic acid was used to catalyze the moisture curing process for the ceramer coating system. The addition of acid catalyst further increased the adhesion. A series of high solids cycloaliphatic polyesters were synthesized to improve the UV-resistance for the organic/inorganic unicoat system. The polyurethane/polysiloxane ceramer coatings were formulated with the addition of the cycloaliphatic polyesters into the polyurea/polysiloxane system. The investigation of the polyurethane ceramer coatings indicated that the film

  14. Surface roughness reduction using spray-coated hydrogen silsesquioxane reflow

    DEFF Research Database (Denmark)

    Cech, Jiri; Pranov, Henrik; Kofod, Guggi

    2013-01-01

    Surface roughness or texture is the most visible property of any object, including injection molded plastic parts. Roughness of the injection molding (IM) tool cavity directly affects not only appearance and perception of quality, but often also the function of all manufactured plastic parts. So...... are reduced 10 and 3 times respectively. We completed more than 10,000 injection molding cycles without detectable degradation of the HSQ coating. This result opens new possibilities for molding of affordable plastic parts with perfect surface finish....... called “optically smooth” plastic surfaces is one example, where low roughness of a tool cavity is desirable. Such tool surfaces can be very expensive to fabricate using conventional means, such as abrasive diamond polishing or diamond turning. We present a novel process to coat machined metal parts...

  15. Corrosion resistance and characterization of metallic coatings deposited by thermal spray on carbon steel

    International Nuclear Information System (INIS)

    Sá Brito, V.R.S.; Bastos, I.N.; Costa, H.R.M.

    2012-01-01

    Highlights: ► Five combinations of metallic coatings and intermediate bonds were deposited on carbon steels. ► High strength was reached in adhesion tests. ► Epoxy sealing of coatings improves corrosion resistance. -- Abstract: Carbon steels are not resistant to corrosion and several methods are used in surface engineering to protect them from aggressive environments such as marine. The main objective of this work is the evaluation of mechanical and metallurgical properties of five metallic coatings produced by thermal spray on carbon steel. Five chemical compositions were tested in order to give a large panel of possibility. Coatings were characterized by several methods to result in a screening of their performance. At first, the assessment of microstructural morphology by optical microscopy (OM) and by scanning electron microscopy (SEM) was made. OM and SEM results showed uniformity of deposited layer, low amount of oxides and porosity. The physical properties of coatings were also evaluated by microhardness measurement, adhesion and porosity quantification. The corrosion resistance was analyzed in salt spray and electrochemical polarization tests. In the polarization test, as well as in the salt spray, all sealed conditions presented low corrosion. A new intermediate 78.3Ni20Cr1.4Si0.3Fe alloy was studied in order to reduce pores and microcracks that are frequently found in ordinary 95Ni5Al alloy. Based on the performed characterizations, the findings suggested that the FeCrCo deposition, with an epoxy sealing, is suitable to be used as an efficient coating of carbon steel in aggressive marine environments.

  16. PROCESSING AND CHARACTERISATION OF HIGH-VELOCITY SUSPENSION FLAME SPRAYED (HVSFS BIOACTIVE GLASS COATINGS

    Directory of Open Access Journals (Sweden)

    GIOVANNI BOLELLI

    2010-03-01

    Full Text Available The High-Velocity Suspension Flame Spraying (HVSFS technique was employed in order to deposit bioactive glass coatings onto titanium substrates. Two different glass compositions were examined: the classical 45S5 Bioglass and a newly-developed SiO2–CaO–K2O–P2O5 glass, labelled as “Bio-K”. Suitable raw materials were melted in a furnace and fritted by casting into water. The frit was dry-milled in a porcelain jar and subsequently attrition-milled in isopropanol. The resulting micronsized powders were dispersed in a water+isopropanol mixture, in order to prepare suitable suspensions for the HVSFS process. The deposition parameters were varied; however, all coatings were obtained by performing three consecutive torch cycles in front of the substrate. The thickness and porosity of the coatings were significantly affected by the chosen set of deposition parameters; however, in all cases, the layer produced during the third torch cycle was thicker and denser than the one produced during the first cycle. As the system temperature increases during the spraying process, the particles sprayed during the last torch cycle remain at T > Tg while they spread, so that interlamellar viscous flow sintering takes place, favouring the formation of such denser microstructure. Both coatings are entirely glassy; however, micro-Raman spectroscopy reveals that, whereas the 45S5 coating is structurally identical to the corresponding bulk glass, the “Bio-K” coating is somewhat different from the bulk one.

  17. Airbrush Spray Coating of Amorphous Titanium Dioxide for Inverted Polymer Solar Cells

    Directory of Open Access Journals (Sweden)

    Luca La Notte

    2012-01-01

    Full Text Available One of the main topics of organic photovoltaics manufacturing is the need for simple, low cost, and large area compatible techniques. Solution-based processes are the best candidates to achieve this aim. Among these, airbrush spray coating has successfully applied to deposit both active and PEDOT layers of bulk-heterojunction solar cells. However, this technique is not yet sufficiently studied for interfacial layers (electron and hole transporting layers or optical spacers. In this paper, we show that amorphous titanium dioxide ( films, obtained with an airbrush from a solution of titanium (IV isopropoxide diluted in isopropanol, are successfully deposited on glass and PET substrates. Good surface covering results from the coalescence of droplets after optimizing the spray coating system. Simple inverted polymer solar cells are fabricated using as electron transporting layer obtaining encouraging electrical performances (% on glass/FTO and 0.7% on PET/ITO substrates.

  18. Carbon-coated hexagonal magnetite nanoflakes production by spray CVD of alcohols in mixture with water

    Science.gov (United States)

    Reyes-Reyes, Marisol; Hernández-Arriaga, Daniel; López-Sandoval, Román

    2014-12-01

    In this study, we report a successful technique for synthesizing magnetite hexagonal nanoflakes coated with carbon layers using spray thermal decomposition, which is a reproducible method that is easy to scale up. We investigated the effects of mixing different volumes of deionized (DI) water with alcohol on the population and quality of single-crystalline Fe3O4 hexagonal nanoflakes. Methanol and ethanol were used as the carbon and oxygen source, while ferrocene was mainly used as the Fe source. To obtain a large quantity of hexagonal structures, a strongly oxidative atmosphere was required. The DI water was used to enhance the oxidative environment during the reaction and was an important component for obtaining well-shaped hexagonal magnetite crystalline nanoflakes. The use of alcohols, water and the spray chemical vapor deposition (CVD) method make this procedure easy to use. In addition, this method provides a one-step process for synthesizing carbon-coated hexagonal Fe3O4 nanocrystals.

  19. Silica Coated Paper Substrate for Paper-Spray Analysis of Therapeutic Drugs in Dried Blood Spots

    Science.gov (United States)

    Zhang, Zhiping; Xu, Wei; Manicke, Nicholas E.; Cooks, R. Graham; Ouyang, Zheng

    2011-01-01

    Paper spray is a newly developed ambient ionization method that has been applied for direct qualitative and quantitative analysis of biological samples. The properties of the paper substrate and spray solution have a significant impact on the release of chemical compounds from complex sample matrices, the diffusion of the analytes through the substrate, and the formation of ions for mass spectrometry analysis. In this study, a commercially available silica-coated paper was explored in an attempt to improve the analysis of therapeutic drugs in dried blood spots (DBS). The dichloromethane/isopropanol solvent has been identified as an optimal spray solvent for the analysis. The comparison was made with paper spray using chromatography paper as substrate with methanol/water as solvent for the analysis of verapamil, citalopram, amitriptyline, lidocaine and sunitinib in dried blood spots. It has been demonstrated the efficiency of recovery of the analytes was notably improved with the silica coated paper and the limit of quantitation (LOQ) for the drug analysis was 0.1 ng mL−1 using a commercial triple quadrupole mass spectrometer. The use of silica paper substrate also resulted in a sensitivity improvement of 5-50 fold in comparison with chromatography papers, including the Whatmann ET31 paper used for blood card. Analysis using a handheld miniature mass spectrometer Mini 11 gave LOQs of 10~20 ng mL−1 for the tested drugs, which is sufficient to cover the therapeutic ranges of these drugs. PMID:22145627

  20. Failure modes of vacuum plasma spray tungsten coating created on carbon fibre composites under thermal loads

    Energy Technology Data Exchange (ETDEWEB)

    Hirai, T., E-mail: takeshi.hirai@iter.or [JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon (United Kingdom); Forschungszentrum Juelich EURATOM-Association, FZJ, D-52425 Juelich (Germany); Bekris, N. [JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon (United Kingdom); EFDA CSU, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Coad, J.P. [JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon (United Kingdom); Culham Science Centre, EURATOM-UKAEA Fusion Association, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Grisolia, C. [JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon (United Kingdom); Association Euratom-CEA, Cadarache DSM/DRFC, F-13108, St-Paul-lez-Durance (France); Linke, J. [JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon (United Kingdom); Forschungszentrum Juelich EURATOM-Association, FZJ, D-52425 Juelich (Germany); Maier, H. [JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon (United Kingdom); Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, D-85748 Garching bei Muenchen (Germany); Matthews, G.F. [JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon (United Kingdom); Culham Science Centre, EURATOM-UKAEA Fusion Association, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Philipps, V.; Wessel, E. [JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon (United Kingdom); Forschungszentrum Juelich EURATOM-Association, FZJ, D-52425 Juelich (Germany)

    2009-07-01

    Vacuum plasma spray tungsten (VPS-W) coating created on a carbon fibre reinforced composite (CFC) was tested under two thermal load schemes in the electron beam facility to examine the operation limits and failure modes. In cyclic ELM-like short transient thermal loads, the VPS-W coating was destroyed sub-layer by sub-layer at 0.33 GW/m{sup 2} for 1 ms pulse duration. At longer single pulses, simulating steady-state thermal loads, the coating was destroyed at surface temperatures above 2700 deg. C by melting of the rhenium containing multilayer at the interface between VPS-W and CFC. The operation limits and failure modes of the VPS-W coating in the thermal load schemes are discussed in detail.

  1. Manufacturing nanostructured YSZ coatings by suspension plasma spraying (SPS): effect of injection parameters

    International Nuclear Information System (INIS)

    Meillot, E; Vert, R; Caruyer, C; Damiani, D; Vardelle, M

    2011-01-01

    The suspension plasma spraying process is investigated using shadow imaging techniques to appreciate the different trajectories of the liquid jet interacting with a dc high-energy plasma flow. Then, the modelling of different liquid injections (isolated droplet, train of droplets and continuous jet) helps us to determine which injection type must be preferred. From that, coating depositions have been carried out with yttria zirconia suspension. Trajectory deviations at impact have been measured depending on the injection pressure and injection location. Coatings have been realized under the same operating investigations and their microstructures and mechanical properties have been characterized.

  2. 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

  3. Evaluation of thermal sprayed metallic coatings for use on the structures at Launch Complex 39

    Science.gov (United States)

    Welch, Peter J.

    1990-01-01

    The current status of the evaluation program is presented. The objective was to evaluate the applicability of Thermal Sprayed Coatings (TSC) to protect the structures in the high temperature acid environment produced by exhaust of the Solid Rocket Boosters during the launches of the Shuttle Transportation System. Only the relatively low cost aluminum TSC which provides some cathodic protection for steel appears to be a practical candidate for further investigation.

  4. 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

  5. Residual Stress in Sprayed Ni+5% Al Coatings Determined by Neutron Diffraction

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Sampath, S.; Gnaupel-Herold, T.; Prask, H. J.

    2002-01-01

    Roč. 74, supplement 8 (2002), s. S1692-S1694 ISSN 0947-8396 R&D Projects: GA ČR GA106/01/0094 Grant - others:NSF DMR(US) 6932570 Institutional research plan: CEZ:AV0Z2043910 Keywords : residual stress, thermal spray coatings, neutron diffraction Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 2.231, year: 2002

  6. Microstructure and sliding wear properties of HVOF sprayed, laser remelted and laser clad Stellite 6 coatings

    Czech Academy of Sciences Publication Activity Database

    Houdková, Š.; Pala, Zdeněk; Smazalová, E.; Vostřák, M.; Česánek, Z.

    2017-01-01

    Roč. 318, May (2017), s. 129-141 ISSN 0257-8972. [International Meeting on Thermal Spraying (RIPT)/7./. Limoges, 09.12.2015-11.12.2015] Institutional support: RVO:61389021 Keywords : Stellite 6 * HVOF * Laser remelting * Laser clad * Wear * Phase transformation 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/S0257897216308817

  7. Cost-effective electrostatic-sprayed SrAl2O4:Eu phosphor coatings ...

    Indian Academy of Sciences (India)

    Abstract. 3 Mol% of europium doped strontium aluminate (SrAl2O4:Eu2+) coatings on silicon substrates were prepared by electrostatic spray deposition method using a salted sol–gel derived solution as a starting material. As- deposited films at 100◦C for 5 h were heated at 1100◦C for 2 h under a reducing ambient ...

  8. Corrosion Testing of Thermal Spray Coatings in a Biomass Co-Firing Power Plant

    Directory of Open Access Journals (Sweden)

    Maria Oksa

    2016-11-01

    Full Text Available Large-scale use of biomass and recycled fuel is increasing in energy production due to climate and energy targets. A 40% cut in greenhouse gas emission compared to 1990 levels and at least a 27% share of renewable energy consumption are set in EU Energy Strategy 2030. Burning fuels with high content of corrosive species such as chlorine and heavy metals causes deterioration of boiler components, shortened lifetime, limited availability of a plant and hence higher maintenance and investment costs and lower thermal and economic efficiency. Coatings can be applied to protect the critical boiler components against high temperature corrosion. In this study, five thermal spray coatings were tested in an actual biomass co-firing boiler for 1300 h with a measurement probe. The coatings were analyzed after the exposure by metallographic means and scanning electron microscope/energy-dispersive X-ray spectroscope (SEM/EDX. The deposits formed on the specimens were analyzed by X-ray fluorescence. At 550 °C, the coatings showed excellent corrosion performance compared to reference material ferritic steel T92. At 750 °C, tube material A263 together with NiCr and NiCrTi had the highest corrosion resistance. To conclude, thermal spray coatings can offer substantial corrosion protection in biomass and recycled fuel burning power plants.

  9. The characterization of an oxide interfacial coating for ceramic matrix composites

    International Nuclear Information System (INIS)

    Coons, Timothy P.; Reutenauer, Justin W.; Mercado, Andrew; Kmetz, Michael A.; Suib, Steven L.

    2013-01-01

    This work focused on the use of metal organic chemical vapor deposition (MOCVD) to deposit a zinc oxide (ZnO) coating on ceramic fibers as an interfacial system for continuous fiber reinforced ceramic matrix composites (CFR-CMCs). ZnO coatings were deposited on ceramic grade (CG) Nicalon ™ , Hi-Nicalon ™ , and Hi-Nicalon ™ Type S fabric by the thermal decomposition of zinc acetate dihydrate in a low pressure hot wall CVD reactor. A duplex SiO 2 coating was also deposited in order to protect the ZnO layer from the reducing conditions during composite fabrication. Tow testing was used to evaluate the effect of the ZnO coating on the strength retention of the ceramic fabrics. Single strand unidirectional mini composites were fabricated by infiltrating SiC into the ZnO/SiO 2 duplex coated tows in order to understand the interfacial properties of the ZnO coating. The mini composite utilizing Hi-Nicalon ™ Type S produced the highest ultimate tensile strength (UTS) of 330 MPa. The coated fabrics and the mini composites were characterized using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and scanning Auger microscopy (SAM)

  10. Bioconductivity and mechanical properties of plasma-sprayed dicalcium silicate/zirconia composite coating

    International Nuclear Information System (INIS)

    Xie Youtao; Liu Xuanyong; Ding Chuanxian; Chu, Paul K.

    2005-01-01

    Dicalcium silicate (C 2 S)/yttria stabilized zirconia (YSZ) composite coatings possessing better durability and more superior mechanical properties than pure C 2 S coatings were produced by atmospheric plasma spraying. The microstructure and phase composition of the composite coatings were determined by scanning electron microscopy and X-ray diffraction. The bioconductivity of the coatings was evaluated in vitro by incubating in simulated body fluids (SBF). Apatite was observed to precipitate even on coatings comprising more than 70% YSZ after immersion in SBF for 7 days. The changes of the mechanical properties of the composite coatings due to immersion in SBF were also investigated. The durability was found to increase with a larger YSZ content in the coatings. Deterioration of the mechanical properties can be attributed to the degraded interlamellar or cohesive bonding due to fast dissolution of C 2 S. This study reveals factors affecting the durability of the C 2 S/YSZ composite coatings in simulated physiological environment and suggests means for improvement to address clinical needs

  11. Improved stability of plasma-sprayed dicalcium silicate/zirconia composite coating

    International Nuclear Information System (INIS)

    Xie Youtao; Liu Xuanyong; Zheng Xuebin; Ding Chuanxian; Chu, Paul K.

    2006-01-01

    Dicalcium silicate/zirconia composite coatings were produced on Ti-6Al-4V substrates using atmospheric plasma spraying. Different weight ratios of zirconia (50 wt.%, 70 wt.%, 90 wt.%) were mechanically blended with dicalcium silicate (C 2 S) powders as feedstocks. The composite coatings were immersed in a simulated body fluid (SBF) and a Tris-HCl solution for the in vitro appraisement of stability and long-term performance in a biological environment. The ion concentration changes of Ca, Si, and P in SBF and Tris-HCl solution were monitored using inductively-coupled plasma atomic emission spectroscopy (ICP-AES). Compared to the pure C 2 S coating, our results show that the dissolution rate of the composite coatings is effectively reduced and the stability is improved by the addition of zirconia. The high content of zirconia in the coatings ensures the long-term performance in biological environment, while dissolution of C 2 S in the coatings results in a higher Ca ion concentration in SBF and rapid precipitation of bone-like apatite on the composite coating surfaces indicating good bioconductivity of the coatings

  12. Anti-bacterial and cytotoxic properties of plasma sprayed silver-containing HA coatings.

    Science.gov (United States)

    Chen, Yikai; Zheng, Xuebin; Xie, Youtao; Ding, Chuanxian; Ruan, Hongjiang; Fan, Cunyi

    2008-12-01

    Silver-containing hydroxyapatite (HA) coatings have been prepared on titanium substrate by vacuum plasma spraying (VPS) method and anti-bacterial properties of the coatings were examined. Three types of bacteria stains, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, were employed in this test. The results showed that the silver-containing HA coatings exhibited significant anti-bacterial effects against the three bacteria with anti-bacterial ratios higher than 95%. The release of silver ions in the physiological environment ensured excellent anti-bacterial properties of the silver-containing HA coatings. International standard ISO 10993-12 was adopted for cytotoxicity evaluation using fibroblast cell line L929, and it was found that the cytotoxicity for the coatings ranked 0 that showed no cytotoxicity for the coatings. Hemolysis test was processed according to ASTM F 756 standard with anti-coagulated rabbit blood, and the hemolysis ratios of the coatings were below 0.4%, indicating of non-hemolysis for the coatings.

  13. Structure Property Relationship of Suspension Thermally Sprayed WC-Co Nanocomposite Coatings

    Science.gov (United States)

    Ahmed, R.; Faisal, N. H.; Al-Anazi, Nayef M.; Al-Mutairi, S.; Toma, F.-L.; Berger, L.-M.; Potthoff, A.; Polychroniadis, E. K.; Sall, M.; Chaliampalias, D.; Goosen, M. F. A.

    2015-02-01

    Tribomechanical properties of nanostructured coatings deposited by suspension high velocity oxy-fuel (S-HVOF) and conventional HVOF (Jet Kote) spraying were evaluated. Nanostructured S-HVOF coatings were obtained via ball milling of the agglomerated and sintered WC-12Co feedstock powder, which were deposited via an aqueous-based suspension using modified HVOF (TopGun) process. Microstructural evaluations of these hardmetal coatings included transmission electron microscopy, x-ray diffraction, and scanning electron microscopy equipped with energy dispersive x-ray spectroscopy. The nanohardness and modulus of the coated specimens were investigated using a diamond Berkovich nanoindenter. Sliding wear tests were conducted using a ball-on-flat test rig. Results indicated that low porosity coatings with nanostructured features were obtained. High carbon loss was observed, but coatings showed a high hardness up to 1000 HV2.9N. S-HVOF coatings also showed improved sliding wear and friction behavior, which were attributed to nanosized particles reducing ball wear in three-body abrasion and support of metal matrix due to uniform distribution of nanoparticles in the coating microstructure.

  14. Microstructure and Properties of Thermally Sprayed Functionally Graded Coatings for Polymeric Substrates

    Science.gov (United States)

    Ivosevic, M.; Knight, R.; Kalidindi, S. R.; Palmese, G. R.; Sutter, J. K.

    2003-01-01

    The use of polymer matrix composites (PMCs) in the gas flow path of advanced turbine engines offers significant benefits for aircraft engine performance but their useful lifetime is limited by their poor erosion resistance. High velocity oxy-fuel (HVOF) sprayed polymer/cermet functionally graded (FGM) coatings are being investigated as a method to address this technology gap by providing erosion and oxidation protection to polymer matrix composites. The FGM coating structures are based on a polyimide matrix filled with varying volume fractions of WC-Co. The graded coating architecture was produced using a combination of internal and external feedstock injection, via two computer-controlled powder feeders and controlled substrate preheating. Porosity, coating thickness and volume fraction of the WC-Co filler retained in the coatings were determined using standard metallographic techniques and computer image analysis. The pull-off strength (often referred to as the adhesive strength) of the coatings was evaluated according to the ASTM D 4541 standard test method, which measured the greatest normal tensile force that the coating could withstand. Adhesive/cohesive strengths were determined for three different types of coating structures and compared based on the maximum indicated load and the surface area loaded. The nature and locus of the fractures were characterized according to the percent of adhesive and/or cohesive failure, and the tested interfaces and layers involved were analyzed by Scanning Electron Microscopy.

  15. Effects of Oxygen-fuel Ratio on Structure and Property of Detonation Gun Sprayed WC Coating

    Directory of Open Access Journals (Sweden)

    ZHAO Li-ying

    2016-06-01

    Full Text Available The tungsten carbide coating with both high hardness and dense microstructure was prepared by optimizing the detonation gun spraying parameters. The phase identifications and microstructure of the coating were observed and analyzed by optical microscope, X-ray diffraction (XRD and energy dispersive spectrometer (EDS. The results show that with the increase of oxygen-fuel ratio, the hardness and adhesive strength of the coating firstly enhance and then decrease, while porosities firstly decrease and then increase. When the oxygen fuel ratio is too low, slow particle flight speed and insufficient melt are the main reasons for the degradation of the coating compactness and mechanical properties. When the oxygen fuel ratio is too high, particle decarburization and binder phase nonuniform contract in the cooling process are the determining factors to the coating structure and properties. When the oxygen-fuel ratio is 1.15, comprehensive performance of the coating is optimal, and the oxidation and decarburization of the coating can be effectively reduced. The Vickers microhardness HV0.3 of cross-section reaches 1178kg·mm-2, the porosity is 0.86%, and the bonding strength between the coating and substrate is 152MPa.

  16. 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.

  17. Comparative examination of the microstructure and high temperature oxidation performance of NiCrBSi flame sprayed and pack cementation coatings

    International Nuclear Information System (INIS)

    Chaliampalias, D.; Vourlias, G.; Pavlidou, E.; Skolianos, S.; Chrissafis, K.; Stergioudis, G.

    2009-01-01

    Coatings formed from NiCrBSi powder were deposited by thermal spray and pack cementation processes on low carbon steel. The microstructure and morphology of the coatings were studied by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Flame sprayed coatings exhibited high porosity and were mechanically bonded to the substrate while pack cementation coatings were more compact and chemically bonded to the substrate. The microhardness and the high temperature oxidation resistance of the coated samples were evaluated by a Vickers microhardness tester and by thermogravimetric measurements (TG), respectively. Pack cementation coatings showed higher hardness and were more protective to high temperature environments than the flame sprayed coatings.

  18. Electrochemical Behavior of Bilayer Thermal-Spray Coatings in Low-Temperature Corrosion Protection

    Directory of Open Access Journals (Sweden)

    Esmaeil Sadeghimeresht

    2017-09-01

    Full Text Available Cr3C2-NiCr coatings are greatly used to protect critical components in corrosive environments and to extend their lifetime and/or improve functional performance. However, the pores formed during spraying restrict the coating’s applicability area for many corrosion protection applications. To overcome this technical challenge, bilayer coatings have been developed, in which an additional layer (the so-called “intermediate layer” is deposited on the substrate before spraying the Cr3C2-NiCr coating (the so-called “top layer”. The corrosion behavior of the bilayer coating depends on the composition and microstructure of each layer. In the present work, different single-layer coatings (i.e., Cr3C2-NiCr, Fe- and Ni-based coatings were initially sprayed by a high-velocity air fuel (HVAF process. Microstructure analysis, as well as electrochemical tests, for example, open-circuit potential (OCP and polarization tests, were performed. The potential difference (ΔE had a great influence on galvanic corrosion between the top and intermediate layers, and thus, the coatings were ranked based on the OCP values (from high to low as follows: NiCoCrAlY > NiCr > Cr3C2-NiCr > NiAl > Fe-based coatings (alloyed with Cr > pure Ni. The Ni-based coatings were chosen to be further used as intermediate layers with the Cr3C2-NiCr top layer due to their capabilities to show high OCP. The corrosion resistance (Rp of the bilayer coatings was ranked (from high to low as follows: NiCoCrAlY/Cr3C2-NiCr > NiCr/Cr3C2-NiCr > NiAl/Cr3C2-NiCr > Ni/Cr3C2-NiCr. It was shown that splat boundaries and interconnected pores are detrimental for corrosion resistance, however, a sufficient reservoir of protective scale-forming elements (such as Cr or/and Al in the intermediate layer can significantly improve the corrosion resistance.

  19. 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

  20. Structure and wear behavior of NiCr–Cr3C2 coatings sprayed by supersonic plasma spraying and high velocity oxy-fuel technologies

    International Nuclear Information System (INIS)

    Lin, Li; Li, Guo-Lu; Wang, Hai-Dou; Kang, Jia-Jie; Xu, Zhong-Lin; Wang, Hai-Jun

    2015-01-01

    Highlights: • The SPS and HVOF technologies are used to prepare NiCr–Cr 3 C 2 coatings. • Coating microstructure and properties are systematically investigated and compared. • Wear behaviors of coatings are comprehensively and thoroughly evaluated. - Abstract: The 25%NiCr–Cr 3 C 2 coatings in the experiment were sprayed on 1045 steel substrates by supersonic plasma spraying (SPS) and high velocity oxy-fuel (HVOF) technologies. The microstructures of the coatings were evaluated using environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM) equipped with energy dispersive X-ray detector (EDX); the phase composition and chemical composition were analyzed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS); the distribution status and quantity of pores were assessed by an software named as ImageJ2x; the bonding strength, micro-hardness, elastic modulus were respectively experimented and analyzed by different equipments and methods. Besides, wear properties of coatings were determined by UMT-3MT. The results showed that both coatings fabricated by SPS and HVOF had a high micro-hardness, elastic modulus and low porosity; The phase composition of both coatings were similar to that of the NiCr–Cr 3 C 2 feedstock, while the coating deposited by HVOF (HVOF coating) produced a new compound Cr 23 C 6 and was somehow oxidized for the emerging of oxygen analyzed by XPS. Both coefficient of friction (COF) and the mass loss of coating deposited by SPS (SPS coating) were lower than those of HVOF coating under same test conditions. The HVOF coating had an obvious spalling and a deeper scratch. And there was a great deal of micro-cracks around the scratch, especially on both ends of scratch. The main wear mechanisms of both coatings were abrasive wear and lamellar spalling.

  1. Development of a permeation panel to test dermal protective clothing against sprayed coatings.

    Science.gov (United States)

    Ceballos, Diana M; Yost, Michael G; Whittaker, Stephen G; Reeb-Whitaker, Carolyn; Camp, Janice; Dills, Russell

    2011-03-01

    Design, construct, and characterize an apparatus to evaluate dermal protective clothing for resistance to polymerizing materials. Specifically, we evaluated the permeation of the most common glove material used in automotive collision repair (0.10-0.13 mm or 4-5 mil latex) with representative isocyanate-containing clear coats. Our ultimate goal is to make informed recommendations on dermal protective materials to prevent isocyanate exposures and reduce the likelihood of occupational illness in automotive collision repair and other industries. A novel permeation panel was developed to assess dermal protective clothing. With this apparatus, up to eight test materials may be evaluated under typical-spray application conditions. Solid collection media comprised of 1-(2-pyridyl)-piperazine (2-PP)-coated fiberglass filters or colorimetric SWYPE™ pads were placed behind test materials to capture permeants. The 2-PP-coated filters were subsequently analyzed using a modified OSHA42/PV2034 method. Color change in the SWYPEs provided an immediate field estimate of breakthrough time. In addition, Teflon filters were mounted proximal to the permeation cells to measure the mass of clear coat applied to the panel and to evaluate loading homogeneity. This study evaluated the permeation of isocyanates through 0.10-0.13 mm latex glove material at a fixed time (30 min post-spraying) and over a time course (6-91 min post-spraying). Monomers 1,6-hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) permeated through (0.10-0.13 mm) latex glove material under typical glove use conditions (30 min). The latex glove material exhibited immediate breakthrough, with a permeation rate of 2.9 ng min(-1) cm(-2). The oligomeric forms of HDI and IPDI did not permeate the latex glove material. The spray application at 71 ± 5 °F was fairly homogeneous (33.7 ± 8 mg weight of dry clear coat per 5 cm(2)). The permeation panel is a viable method to assess dermal protective clothing

  2. Plasma sprayed hydroxyapatite coatings on titanium substrates. Part 1: Mechanical properties and residual stress levels.

    Science.gov (United States)

    Tsui, Y C; Doyle, C; Clyne, T W

    1998-11-01

    Hydroxyapatite (HA) coatings have been sprayed on to substrates of Ti-6Al-4V, using a range of input power levels and plasma gas mixtures. Coatings have also been produced on substrates of mild steel and tungsten, in order to explore certain aspects of the mechanical behaviour of HA without the complication of yielding or creep in the substrate. Studies have been made of the phase constitution, porosity, degree of crystallinity, OH ion content, microstructure and surface roughness of the HA coatings. The Young's moduli in tension and in compression were evaluated by the cantilever beam bend test using a tungsten/HA composite beam. The flexural Young's modulus was determined using a free-standing deposit under the same test. Adhesion was characterised using the single-edge notch-bend test; this is considered superior to the tensile bond strength test in common use. Measured interfacial fracture energies were of the order 1-10 J m(-2). Stress levels were investigated using specimen curvature measurements in conjunction with a numerical process model. The quenching stress for HA was measured to be about 10-25 MPa and the residual stress level in HA coatings at room temperature are predicted to lie in the approximate range of 20-40 MPa (tensile). These residual stresses could be reduced in magnitude by maintaining the substrate at a low temperature (possibly below room temperature) during spraying and it may be worthwhile to explore this. Ideally, the HA coating should have low porosity, high cohesive strength, good adhesion to the substrate, a high degree of crystallinity and high chemical purity and phase stability. In practice, such combinations are rather difficult to achieve by just varying the spraying parameters.

  3. 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).

  4. Corrosion resistance of tungsten carbide based cermet coatings deposited by High Velocity Oxy-Fuel spray process

    Energy Technology Data Exchange (ETDEWEB)

    Aw, Poh Koon [Singapore Institute of Manufacturing Technology (Singapore)], E-mail: pkaw@SIMTech.a-star.edu.sg; Tan, Annie Lai Kuan [Singapore Institute of Manufacturing Technology (Singapore); Tan, Tai Phong [Hamilton Sundstrand Pacific Aerospace Pte Ltd (Singapore); Qiu, Jianhai [School of Materials Science and Engineering, Nanyang Technological University (Singapore)

    2008-06-30

    WC-17Ni and WC-17Co coatings were deposited on mild steel and stainless steel substrates by High Velocity Oxy-Fuel (HVOF) spray process. WC-17Ni and WC-17Co coatings were obtained by the spray process and the porosity of these coatings was measured. Polarization and electrochemical impedance spectroscopy (EIS) were performed on both uncoated substrates and coated samples immersed in 3% NaCl solution. WC-17Ni coating with a lower porosity, serve as a better barrier and effectively prevented corrosion attack when it was deposited on mild steel substrate. The nickel binder in the WC-17Ni coating was found to have a better corrosion resistance than the cobalt binder in the WC-17Co coating.

  5. Investigation of an as-sprayed NiCoCrAlY overlay coating - microstructure and evolution of the coating

    Energy Technology Data Exchange (ETDEWEB)

    Fritscher, K. [DLR German Aerospace Center, Institute of Materials Research, 51170 Cologne (Germany); Lee, Y.T. [KIMM Korea Institute of Machinery and Materials, Sangnam 66, Changwon 641-010 (Korea)

    2005-01-01

    A low pressure plasma sprayed (LPPS) NiCoCrAlY aircraft turbine blade overlay coating was investigated in the as-sprayed condition by X-ray diffraction (XRD) and analytical transmission electron microscopic (TEM) techniques. {gamma}-Ni, {beta}-NiAl and {gamma}'-Ni{sub 3}Al phases were identified by XRD showing predominant {gamma} phase at the expense of {beta} phase if compared to the fully processed state with {gamma} and {beta} at about equal portions. Besides grains of {gamma}-Ni and {beta}-NiAl, amorphous metallic grains and Cr-rich oxides were found by TEM. Close to the surface to the atmosphere {gamma}'-Ni{sub 3}Al phase was localized in composite grains with an off-plane oriented {gamma}-{gamma}' fibrous eutectic structure. They were neighbored by amorphous metallic grains. The evolution of these structures is discussed within the scope of crystal growth behavior. The dominant occurrence of face-centered cubic at the expense of body-centered phases observed in as-sprayed coatings is attributed to their higher growth rates on quenching. Also benefiting from rapid growth the {gamma}-{gamma}' fibrous eutectic grains will form, hereby relying on essentially binary phase compositions of highly extended solubility ranges. Accumulation of alloy constituents like Cr and Ti by segregation to the growth front is considered to pave the way for the evolution of amorphous grains at the coating surface on top of {gamma}-{gamma}' grains. The potentials of the microstructures in service are addressed. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  6. Thermal stability of phosphate coatings on steel

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2015-07-01

    Full Text Available The work was validated thermal stability of zinc, manganese and tri-cations phosphate coatings on steel, made from commercial phosphating bath type Pragofos. Thermogravimetric data dehydration of scholzite, phosphophylite and hureaulite coatings in the temperature range 160 °C – 400 °C define the conditions for applying paints with higher firing temperature or thermal spraying ceramic coatings.

  7. 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

  8. Cold Spray Coating Deposition Mechanism on the Thermoplastic and Thermosetting Polymer Substrates

    Science.gov (United States)

    Ganesan, Amirthan; Yamada, Motohiro; Fukumoto, Masahiro

    2013-12-01

    Cold spraying is a successful and promising coating technique for many engineering applications due to its high-rate and high-dense coating development abilities. Nevertheless, their practical use in polymer substrate is still in the fledgling phase. There are very few articles about the cold spray coating on polymers; however, the interaction of metallic particle with the polymer substrate is poorly understood, and thus a thick coating has not successfully been developed on the polymer substrate. In order to rationalize as full as possible the entire behavior of the high velocity particle with the polymer substrate, we used thermoplastic and thermosetting polymer materials as substrates. The particle behaviors with the substrate were observed under various gas pressure and temperature, and with various particles feed rate. The result showed that the particle behaviors were unique with respect to the substrate. Also it was clearly understood that the metal particles not experienced any plastic deformation due to the soft nature of the polymer substrates. The particles attached to the thermoplastic substrate either through adhesive bonding and/or mechanical inter locking, whereas only pure localized fracture observed on the thermosetting substrate and thus no particles attached firmly on the substrate.

  9. Plasma sprayed TiO2: The influence of power of an electric supply on particle parameters in the flight and character of sprayed coating

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Hrabovský, Milan

    2010-01-01

    Roč. 30, č. 15 (2010), s. 3131-3136 ISSN 0955-2219 R&D Projects: GA AV ČR IAAX00430803 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma spraying * DC plasma torch * Power supply * TiO2 * Wear testing * Bandgap Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.574, year: 2010

  10. Evaluation of the Shearing Strength of a WC-12Co Thermal Spray Coating by the Scraping Test Method

    Directory of Open Access Journals (Sweden)

    Kenji Kaneko

    2015-07-01

    Full Text Available This paper reports on an experimental and analytical investigation conducted into efficacy of the scraping shear-test method in estimating the shearing adhesive strength of a thermally sprayed coating. It was found that the critical average shear stress, the apparent failure strength of WC-Co thermal spray coating, depends on both the dimensions of the test piece and the loading position around the interface between the coating and the substrate. More specifically, the apparent critical shear stress decreased as the height and width of the test piece increased. In addition, the apparent critical shear stress increased with increasing coating thickness and with decreasing loading point distance measured from the interface. Consequently, the real adhesive strength of thermally sprayed coating could not be ascertained from these experimental results. Furthermore, most of the failure initiation points were inside the coating, as opposed to at the interface. This fact means that the results of the tests do not indicate the interfacial adhesive strength, but rather the shear strength of the coating. Three-dimensional finite element method (FEM analysis showed that the distributions of the shearing stress at the loading points were virtually the same at failure, regardless of the dimensions of the test piece. These results suggest that the scraping test method needs a corresponding numerical analysis of the failure mode in order to produce reliable results and is not necessarily able to estimate the interfacial adhesive strength of thermally sprayed coating.

  11. Effect of epoxy resin sealing on corrosion resistance of arc spraying aluminium coating using cathode electrophoresis method

    Science.gov (United States)

    Pang, Xuming; Wang, Runqiu; Wei, Qian; Zhou, Jianxin

    2018-01-01

    Arc-sprayed Al coating was sealed with epoxy resin using the cathode electrophoresis method. The anti-corrosion performance of the coatings sealed with epoxy resin was studied by means of a 3.5 wt.% NaCl solution test at 40 °C. For comparison, the anti-corrosion performance of Al coating sealed with boiling water was also performed under the same conditions. The results show that epoxy resin with a thickness of about 20 microns can entirely cover open pores and decreases the surface roughness of the as-sprayed Al coating, and the epoxy resin even permeates into the gaps among lamellar splats from open pores. After corrosion, the thickness of the epoxy resin layer is unchanged and can still cover the as-sprayed Al coating entirely. However, the thickness of Al coating sealed with boiling water decreases from 100 to 40 microns, which indicates that the arc-sprayed Al coating has much better corrosion resistance than the Al coating sealed with boiling water. Meanwhile, the content of substituted benzene ring in the epoxy resin increases, but aromatic ring decreases according to the fourier transform infrared spectra, which will cause the rigidity of the epoxy resin to increase, but the toughness slightly decreases after corrosion.

  12. Polyurethane spray coating of aluminum wire bonds to prevent corrosion and suppress resonant oscillations

    CERN Document Server

    INSPIRE-00092738; Kurth, Matthew; Boyd, Rusty

    2016-01-01

    Unencapsulated aluminum wedge wire bonds are common in particle physics pixel and strip detectors. Industry-favored bulk encapsulation is eschewed due to the range of operating temperatures and radiation. Wire bond failures are a persistent source of tracking-detector failure. Unencapsulated bonds are vulnerable to condensation-induced corrosion, particularly when halides are present. Oscillations from periodic Lorentz forces are documented as another source of wire bond failure. Spray application of polyurethane coatings, performance of polyurethane-coated wire bonds after climate chamber exposure, and resonant properties of polyurethane-coated wire bonds and their resistance to periodic Lorentz forces are under study for use in a future High Luminosity Large Hadron Collider detector such as the ATLAS Inner Tracker upgrade.

  13. Effect of plasma spray operating conditions on plasma jet characteristics and coating properties

    Science.gov (United States)

    Malmberg, S.; Heberlein, J.

    1993-12-01

    Using statistical design of experiments, the arc current, total gas flow rate, percent secondary gas (He), and powder feed rate have been varied to assess the torch behavior and establish its correlation to coating properties. The torch response includes arc voltage drop, torch efficiency, and plasma jet geometry. High-speed images of the luminous plasma jet for each operating condition have been acquired with a LaserStrobeℳ videocamera, and image analysis has been used to quantify the jet length and jet fluctuations as additional torch responses. Porosity and unmelted particles, which are determined using image analysis of a micrograph of a NiAl coating cross section, were selected as principal coating characteristics. These findings are expected to be useful for optimization of new spray processes and for evaluation of new torch designs.

  14. Spray polyurea coatings as containment liners in coal slurry storage ponds

    Energy Technology Data Exchange (ETDEWEB)

    Darden, J.W.; Loomis, R.; Roehm, F.T. [Willamette Valley Co., Eugene, OR (United States)

    1996-12-31

    The Southern California Edison (SCE) Mohave Generating Station was built in the early 1970`s in response to the shortage of oil due to the OPEC boycott. Coal/water slurry from the Black Mesa Pipeline is used to generate energy at the plant. Eight storage ponds, each about 175,000 square feet, were built in the mid to late 1970`s to insure a constant supply of slurry to feed the generating units. This paper describes the application of POLYQuik{trademark} P400 spray polyurea coating to the Marcona Pond, a coal slurry storage area at Southern California Edison`s Mohave Generating Station. The coating forms an impermeable barrier to prevent water loss and contamination of subgrade soils. The use of these coatings reduces facility downtime and liner replacement costs, offering a cost savings over the life of the pond.

  15. Optical property of La1-xSrxTiO3+δ coatings deposited by plasma spraying technique

    Science.gov (United States)

    Zhu, Jinpeng; Gao, Lihong; Ma, Zhuang; Liu, Yanbo; Wang, Fuchi

    2015-11-01

    Perovskite La1-xSrxTiO3+δ oxide is used in various industrial applications because of its excellent physical and chemical properties, which beneficially affects the lifetime and performance of electronic and optical devices. This study illustrates the effects of the spray parameters on particles molten state, microstructure, and optical reflectivity from room temperature up to 1000 °C of single-phase La1-xSrxTiO3+δ (x = 0.1) coating deposited by atmospheric plasma spraying technique. The phase structure and surface morphology of the coating were examined using X-ray diffraction and scanning electron microscopy analysis, respectively, whereas the optical property coating was characterized by UV-visible-near infrared spectroscopy. Results show that plasma spray parameters significantly influenced the microstructure and optical performance of the La1-xSrxTiO3+δ coating, and oxygen deficiency during spraying considerably reduced the coating reflectivity. A high-reflectivity coating can be prepared by adopting optimized plasma spraying parameters and subsequent heat treatment.

  16. POROSITY EVALUATION OF FLAME-SPRAYED AND HEAT-TREATED NICKEL-BASED COATINGS USING IMAGE ANALYSIS

    Directory of Open Access Journals (Sweden)

    Zoran Bergant

    2011-03-01

    Full Text Available Flame sprayed coatings are susceptible to the formation of inter-connected elongated porosity due to the lack of fusion between sprayed particles or the expansion of gases generated during the spraying process. The partial remelting of self-fluxing Ni-Cr-B-Si coating after spraying is an efficient method to reduce porosity and to improve coating microstructural and mechanical properties. The paper describes the image preprocessing procedure for noise removal which separates the pores from the background and the noise. The optimal temperature and time of a furnace heat treatment of Ni-Cr-B-Si coated specimens was determined by using a three-level factorial experiment. The purpose was to obtain the lowest possible porosity. Equivalent diameter, elongation, and major axis angle were analyzed and compared using probability density functions. The experiment shows zero-percent porosity cannot be obtained with a partial remelting of flame-sprayed Ni-Cr-B-Si coatings; however, porosity can be greatly reduced. This method of coating post-processing not only favours pore size and shape but also eliminates the undesired network of interconnected elongated pores.

  17. The detailed analysis of the spray time effects of the aluminium coating using self-generated atmospheric plasma spray system on the microstructure and corrosion behaviour

    Directory of Open Access Journals (Sweden)

    Sh. Khandanjou

    Full Text Available In the present paper our aim is to investigate the effect of the spray time of the aluminium coated layers on the microstructure and corrosion behaviour. For this purpose we use the self-generated atmospheric plasma spray system for coating of aluminium on the carbon steel substrate. The different thicknesses of coating are created. To evaluate this effect we use the several analyses such as X-ray diffraction, scanning electron microscope, Micro hardness analysis by Vickers method, Adhesion strength analysis and electrochemical polarization test. The results are very interesting and show that due to low porosity, thicker layers are more homogeneous. The nanoparticles are observed in the thicker layers. The micro hardness tests show that the thicker layers have the better micro hardness value. Next, the adhesion strength tests illustrate that the highest adhesion strength are for longer spray times. On the other hand, the corrosion resistance behaviour of the coating is investigated by electrochemical polarization test. It is shown that the corrosion resistance increases by increasing the thickness due to low percentage of porosity. Keywords: Plasma spray, Thickness, Aluminium, Micro hardness, Corrosion resistance

  18. Investigation of Droplet Atomization and Evaporation in Solution Precursor Plasma Spray Coating

    Directory of Open Access Journals (Sweden)

    Hongbing Xiong

    2017-11-01

    Full Text Available Solution precursor plasma spray (SPPS is a novel and promising technique in producing nanostructured coatings. This technique involves complex heat, mass and momentum transfer among the liquid feedstock, droplets, plasma jet and the coating material. Nevertheless, the droplet atomization and evaporation in the plasma jet is one of the most essential parts to obtain the desired coating architecture. In the present work, a three-dimensional two-way-coupled Eulerian-Lagrangian code is used to simulate the interactions between the solution precursor and plasma. In order to obtain a more realistic understanding regarding droplet atomization and vaporization, the flash-boiling effect is modeled by an improved vaporization model. This model could provide accurate details for the droplet pyrolysis and help to optimize the solution precursor plasma spray process. We show that the fragmentation of the liquid stock and its vaporization mainly dominate the spraying details and can be decisive to the coating quality. We further investigate their role in SPPS and separately probe their inner link with the flow field relating to the distinctive area when droplets are flying through the thermal flow field. Our studies reveal that ethanol droplets, compared to those of water, show a superior characteristics in SPPS, owing to the low boiling point and low surface tension, conducive to the evaporation and atomization of droplets. In addition, the mixture of the plasma gas with hydrogen breaks the droplets more thoroughly compared to the pure plasma. The numerical results were compared and found to agree well with previous experimental and simulation work.

  19. Polymer-Derived Ceramics as Innovative Oxidation Barrier Coatings for Mo-Si-B Alloys

    Science.gov (United States)

    Hasemann, Georg; Baumann, Torben; Dieck, Sebastian; Rannabauer, Stefan; Krüger, Manja

    2015-04-01

    A preceramic polymer precursor, perhydropolysilazane, is used to investigate its function as a new type of oxidation barrier coating on Mo-Si-B alloys. After dip-coating and pyrolysis at 1073 K (800 °C), dense and well-adhering SiON ceramic coatings could be achieved, which were investigated by SEM and cyclic oxidation tests at 1073 K and 1373 K (800 °C and 1100 °C). The coating is promising in reducing the mass loss during the initial stage of oxidation exposure at 1373 K (1100 °C) significantly.

  20. 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

  1. 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

  2. Spray deposition of organic electroluminescent coatings for application in flexible light emitting devices

    Directory of Open Access Journals (Sweden)

    Mariya Aleksandrova

    2015-12-01

    Full Text Available Organic electroluminescent (EL films of tris(8-hydroxyquinolinatoaluminum (Alq3 mixed with polystyrene (PS binder were produced by spray deposition. The influence of the substrate temperature on the layer’s morphology and uniformity was investigated. The deposition conditions were optimized and simple flexible light-emitting devices consisting of indium-tin oxide/Alq3:PS/aluminum were fabricated on polyethylene terephthalate (PET foil to demonstrate the advantages of the sprayed organic coatings. Same structure was produced by thermal evaporation of Alq3 film as a reference. The influence of the deposition method on the film roughness and contact resistance at the electrode interfaces for both types of structures was estimated. The results were related to the devices’ efficiency. It was found that the samples with sprayed films turn on at 4 V, which is 2 V lower in comparison to the device with thermal evaporated Alq3. The current through the sprayed device is six times higher as well (17 mA vs. 2.8 mA at 6.5 V, which can be ascribed to the lower contact resistance at the EL film/electrode interfaces. This is due to the lower surface roughness of the pulverized layers.

  3. 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.

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

    Science.gov (United States)

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

    2006-11-01

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

  5. Nanostructured Photocatalytic TiO2 Coating Deposited by Suspension Plasma Spraying with Different Injection Positions

    Science.gov (United States)

    Liu, Xuezhang; Wen, Kui; Deng, Chunming; Yang, Kun; Deng, Changguang; Liu, Min; Zhou, Kesong

    2018-02-01

    High plasma power is beneficial for the deposition efficiency and adhesive strength of suspension-sprayed photocatalytic TiO2 coatings, but it confronts two challenges: one is the reduced activity due to the critical phase transformation of anatase into rutile, and the other is fragmented droplets which cannot be easily injected into the plasma core. Here, TiO2 coatings were deposited at high plasma power and the position of suspension injection was varied with the guidance of numerical simulation. The simulation was based on a realistic three-dimensional time-dependent numerical model that included the inside and outside of torch regions. Scanning electron microscopy was performed to study the microstructure of the TiO2 coatings, whereas x-ray diffraction was adopted to analyze phase composition. Meanwhile, photocatalytic activities of the manufactured TiO2 coatings were evaluated by the degradation of an aqueous solution of methylene blue dye. Fragmented droplets were uniformly injected into the plasma jet, and the solidification pathway of melting particles was modified by varying the position of suspension injection. A nanostructured TiO2 coating with 93.9% anatase content was obtained at high plasma power (48.1 kW), and the adhesive coating bonding to stainless steel exhibited the desired photocatalytic activity.

  6. Laser surface modification (LSM) of thermally-sprayed Diamalloy 2002 coating

    Science.gov (United States)

    Gisario, A.; Barletta, M.; Veniali, F.

    2012-09-01

    Thermally-sprayed Diamalloy 2002 is widely used as overlay coating in several applications for their good wear and corrosion protection. Although, in the past, any effort has been produced to deposit Diamalloy 2002 with a low degree of defectiveness, some residual porosity and cracks can often affect the final property of the resulting coatings. Different techniques are commonly used to improve the performance of Diamalloy 2002. Recently, laser post-treatment seems to be one of the most promising, being an effective, non-contact, mini-invasive technology. In this respect, the present investigation deals with the application of a continuous wave high power diode laser to post-treat Diamalloy 2002 deposited by HVOF on AA 6082 T6 aluminum alloy. Different laser power and scan speed were investigated in order to identify the process window most favorable to improve the overall mechanical property of Diamalloy 2002 coatings. The changes in morphology, micro-structure and chemical composition of the coatings after laser post-treatments were investigated by inductive gage profilometry and combined SEM-EDXS. Further, the changes in the mechanical properties of the coatings were investigated in terms of hardness, elastic modulus, scratch and wear resistance. Consistent improvements in mechanical property can be achieved by Diamalloy 2002 when laser processing is performed at higher power and reduced scan speed. Yet, too much increase in power density should be always avoided as it can be detrimental to the final property of the coatings and cause high defectiveness and their failure.

  7. A Study on Cavitation Erosion Behaviors of Corrosion-resistance Thermal Spray Coating Materials

    International Nuclear Information System (INIS)

    Jin, Hee Seok

    2003-02-01

    The hydraulic machinery of screw propeller and pump impellers is damaged by cavitation erosion in sea water. The cavitation erosion is a phenomenon leading a functional disorder of various fluid machinery and dropping off in efficiency by cavity fluid fluctuation. This study is investigated the cavitation erosion of various metallic coatings made by thermal spraying methods. The coating materials are AMDRY625, Cr 2 O 3 , SUS316, Zn, Al. These metals are coated on substrate of high strength brass ( Cu - Zn ). Test specimens are immersed in 3.5% NaCl solution for 500 and 1000 hours, respectively. After pre-corrosion, the cavitation erosion test was conducted on coating specimens in 3.5% NaCl solution along 210 minutes. The results are summarized as follows : 1. Both substrate and test specimens coated by thermal spray underwent weight loss in proportion to the time length of the cavitation erosion test, and the weight loss happened more to 1,000 hour-immersed test specimens and 500 hour-immersed ones in the time order rather than the ones in non-corrosion condition. 2. Substrate and Amdry625 and SUS316 test specimens were all influenced very little by weight loss regardless of the time length and the conditions of the test. 3. The amount of weight loss of aluminum and zinc test specimens and Cr 2 O 3 test specimens heavily increased at the early stage regardless of the conditions but later decreased after the coated layers were fretted by cavitation erosion. 4. The comparison of weight loss after the test showed that Amdry625, SUS316 and substrate underwent very little weight loss, proving to be the very likely materials to bear cavitation erosion but aluminum and zinc and Cr 2 O 3 underwent very great weight loss, proving to be the very unlikely materials to bear cavitation erosion. 5. After the test, the surfaces of Amdry625, SUS316 and substrate showed that they had been less damaged by cavitation erosion but the rest showed that they had been very much damaged by

  8. Tough ceramic coatings: Carbon nanotube reinforced silica sol-gel

    Science.gov (United States)

    López, A. J.; Rico, A.; Rodríguez, J.; Rams, J.

    2010-08-01

    Silica coatings reinforced with carbon nanotubes were produced via sol-gel route using two mixing techniques of the sol-gel precursors, mechanical and ultrasonic mixing, and dip-coating as deposition process on magnesium alloy substrates. Effective incorporation and distribution of 0.1 wt.% of carbon nanotubes in the amorphous silica matrix of the coatings were achieved using both techniques. Fabrication procedure determines the morphological aspects of the coating. Only mechanical mixing process produced coatings dense and free of defects. Nanoindentation technique was used to examine the influence of the fabrication process in the mechanical features of the final coatings, i.e. indentation fracture toughness, Young's modulus and hardness. A maximum toughening effect of about 24% was achieved in silica coatings reinforced with carbon nanotubes produced by the mechanical mixing route. Scanning electron microscopy investigation revealed that the toughening of these reinforced coatings was mainly due to bridging effect of the reinforcement.

  9. Ceramic Matrix Composite Environmental Barrier Coating Durability Model, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — As the power density of advanced engines increases, the need for new materials that are capable of higher operating temperatures, such as ceramic matrix composites...

  10. Ceramic Matrix Composite Environmental Barrier Coating Durability Model, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — As the power density of advanced engines increases, the need for new materials that are capable of higher operating temperatures, such as ceramic matrix composites...

  11. Development and characterization of AlCrN coated Si3N4 ceramic cutting tool

    International Nuclear Information System (INIS)

    Souza, J.V.C.; Nono, M.C.A.; Machado, J.P.B.; Silva, O.M.M.; Sa, F.C.L.

    2010-01-01

    Ceramic cutting tools are showing a growing market perspective in terms of application on machining operations due to their high hardness, wear resistance, and machining without a cutting fluid, therefore are good candidates for cast iron and Nickel superalloys machining. The objective of the present paper was the development of Si 3 N 4 based ceramic cutting insert, characterization of its physical and mechanical properties, and subsequent coating with AlCrN using a PVD method. The characterization of the coating was made using an optical profiler, XRD, AFM and microhardness tester. The results showed that the tool presented a fracture toughness of 6,43 MPa.m 1/2 and hardness of 16 GPa. The hardness reached 31 GPa after coating. The machining tests showed an improvement on work piece roughness when machining with coated insert, in comparison with the uncoated cutting tool. Probably this fact is related to hardness, roughness and topography of AlCrN. (author)

  12. Cross-sectional AEM preparation technique for ceramic-coated WC-Co cutting tools.

    Science.gov (United States)

    Ostreicher, K; Sung, C

    1993-04-15

    The preparation of cross-sectional specimens for AEM studies of materials such as ceramic coated tungsten carbide presents some unique problems. Pieces joined by the use of epoxides often separate at the interface between the WC and ceramic coating during the initial mechanical grinding and subsequent thinning process as a result of the vibration and physical strain placed on the sample. These problems have been overcome through the use of a preparation process which essentially encapsulates the sample within the confines of an epoxy filled quartz tube. This preparation process has allowed for facile AEM cross-sectional analysis of TiN/TiCN coatings on WC-Co substrates, and has revealed two distinct grain morphologies within the TiCN coating.

  13. Infrared Thermography as a Non-destructive Testing Solution for Thermal Spray Metal Coatings

    Science.gov (United States)

    Santangelo, Paolo E.; Allesina, Giulio; Bolelli, Giovanni; Lusvarghi, Luca; Matikainen, Ville; Vuoristo, Petri

    2017-12-01

    In this work, an infrared (IR) thermographic procedure was evaluated as a non-destructive testing tool to detect damage in thermal spray metallic coatings. As model systems, polished HVOF- and HVAF-sprayed Fe-based layers deposited onto steel plates were employed. Damage by external-object impingement was simulated through a cyclic impact-test apparatus, which induced circumferential and radial cracks across all model systems, and interface cracks of different sizes in distinct samples. Damaged and undamaged plates were bulk-heated to above 100 °C using an IR lamp; their free-convection cooling was then recorded by an IR thermocamera. The intentionally induced defects were hardly detectable in IR thermograms, due to IR reflection and artificial "hot" spots induced by residuals of transfer material from the impacting counterbody. As a micrometer-thin layer of black paint was applied, surface emissivity got homogenized and any artifacts were effectively suppressed, so that failed coating areas clearly showed up as "cold spots." This effect was more apparent when large interface cracks occurred. Finite-element modeling proved the physical significance of the IR-thermography approach, showing that failed coating areas are cooled by surrounding air faster than they are heated by conduction from the hot substrate, which is due to the insulating effect of cracks.

  14. Bioinspired nanoparticle spray-coating for superhydrophobic flexible materials with oil/water separation capabilities.

    Science.gov (United States)

    Geraldi, Nicasio R; Dodd, Linzi E; Xu, Ben; Wood, David; Wells, Gary; McHale, Glen; Newton, Michael I

    2017-12-14

    Much of the inspiration for the creation of superhydrophobic surfaces has come from nature, from plant such as the Sacred Lotus (Nulembo nucifera), where the micro-scale papillae epidermal cells on the surfaces of the leaves are covered with nano-scale epicuticular wax crystalloids. The combination of the surface roughness and the hydrophobic wax coating produces a superhydrophobic wetting state on the leaves allowing them to self-clean and easily shed water. Here a simple scale-up carbon nanoparticle spray coating is presented that mimics the surface of the Sacred Lotus leaves and can be applied to a wide variety of materials, complex structures, and flexible substrates, rendering them superhydrophobic, with contact angles above 160°. The sprayable mixture is produced by combining toluene, polydimethylsiloxane (PDMS), and inherently hydrophobic rapeseed soot. The ability to spray the superhydrophobic coating allows for the hydrophobisation of complex structures such a metallic meshes, which allows for the production of flexible porous superhydrophobic materials that when formed into U-shape channels, can be used to direct flows. The porous meshes, whilst being superhydrophobic, are also oleophilic. Being both superhydrophobic and oleophilic allows oil to pass through the mesh, whilst water remains on the surface. The meshes were tested for their ability to separate mixtures of oil and water in a flow situation. When silicone oil/water mixtures were passed over the meshes, all meshes tested were capable of separating more than 95% of the oil from the mixture. © 2017 IOP Publishing Ltd.

  15. METAL-MATRIX COMPOSITES AND THERMAL SPRAY COATINGS FOR EARTH MOVING MACHINES

    Energy Technology Data Exchange (ETDEWEB)

    D. Trent Weaver; Matthew T. Kiser; Frank W. Zok; Carlos G. Levi; Jeffrey Hawk

    2004-02-01

    In an effort to realize minimum of a 2x increase in wear life of ground engaging components used on mining machines, two potentially cost effective processes were explored for the production of tailored, highly abrasion resistant materials: (1) hybrid pressure casting of steel composites, and (2) arc lamp fusing of thermal spray coatings. Steel composites comprised of cermet or oxide hard particles were successfully produced using pressure casting processes, although a cost effective process has not yet been identified for oxide particles. Both composites achieved project wear targets in high stress gouging wear, but the cermet composites did not meet the targets in impact wear, due to poor matrix toughness resulting from particle dissolution. Oxide composites had superior toughness and are expected to meet impact wear goals. Arc lamp processing of thermal spray coatings was successfully demonstrated to produce a metallurgical bond at the coating interface. Functionally graded materials were developed and successfully fused to allow for the accommodation of thermal process stresses in an intermediate layer. Ultimately, three functionally graded materials were identified as having high stress, three-body abrasion resistance sufficient to exceed project goals.

  16. High-Temperature Oxidation and Smelt Deposit Corrosion of Ni-Cr-Ti Arc-Sprayed Coatings

    Science.gov (United States)

    Matthews, S.; Schweizer, M.

    2013-08-01

    High Cr content Ni-Cr-Ti arc-sprayed coatings have been extensively applied to mitigate corrosion in black liquor recovery boilers in the pulp and paper industry. In a previous article, the effects of key spray parameters on the coating's microstructure and its composition were investigated. Three coating microstructures were selected from that previous study to produce a dense, oxidized coating (coating A), a porous, low oxide content coating (coating B), and an optimized coating (coating C) for corrosion testing. Isothermal oxidation trials were performed in air at 550 and 900 °C for 30 days. Additional trials were performed under industrial smelt deposits at 400 and 800 °C for 30 days. The effect of the variation in coating microstructure on the oxidation and smelt's corrosion response was investigated through the characterization of the surface corrosion products, and the internal coating microstructural developments with time at high temperature. The effect of long-term, high-temperature exposure on the interaction between the coating and substrate was characterized, and the mechanism of interdiffusion was discussed.

  17. Effects of Rare Earth Elements on the Microstructure and Mechanical Properties of HVOF-Sprayed WC-Co Coatings

    Science.gov (United States)

    Liu, Yan; Gou, Guoqing; Wang, Xiaomin; Jia, Qiang; Chen, Hui; Tu, Mingjing

    2014-10-01

    Rare earth has been widely used in materials manufacturing to improve hardness and toughness. In this paper, conventional, nanostructured, and rare earth CeO2-doped WC-12Co powders were sprayed by using HVOF spraying technology. Microstructure, hardness, elastic modulus, and fracture toughness of the three coatings were investigated. The results showed that nanostructured WC-12Co coatings possessed the densest microstructure and excellent combination of strength and toughness. The WC particles with the size ranging from 50 to 500 nm distributed uniformly in the nanostructured WC-12Co coating. The average free path of Co matrix in rare earth-doped WC-12Co coating was shorter than that of conventional WC-12Co coating. XRD results showed no obvious decarburization in all three coatings. The addition of rare earth could improve the mechanical properties of the coating compared with that without rare earth. The hardness value of nanostructured WC-12Co coating (12.2 GPa) was similar to that of rare earth-doped WC-12Co coating (12.2 GPa), which was 15.1% higher than that of conventional WC-12Co coating. The elastic modulus and fracture toughness of nanostructured WC-12Co coating were the highest, and that of conventional WC-12Co coating was the lowest.

  18. Glass-(nAg, nCu) Biocide Coatings on Ceramic Oxide Substrates

    OpenAIRE

    Esteban-Tejeda, Leticia; Malpartida, Francisco; Díaz, Luis Antonio; Torrecillas, Ramón; Rojo, Fernando; Moya, José Serafín

    2012-01-01

    The present work was focused on obtaining biocide coatings constituted by a glassy soda-lime matrix containing silver or copper nanoparticles on ceramic (alumina and zirconia based) substrates. Both glassy coatings showed a high biocide activity against Gram-, Gram+ bacteria and yeast, reducing cell numbers more than three logarithms. Silver nanoparticles had a significantly higher biocide activity than copper nanoparticles, since the lixiviation levels required to reduce cell numbers more th...

  19. Laser-Assisted Cold-Sprayed Corrosion- and Wear-Resistant Coatings: A Review

    Science.gov (United States)

    Olakanmi, E. O.; Doyoyo, M.

    2014-06-01

    Laser-assisted cold spray (LACS) process will be increasingly employed for depositing coatings because of its unique advantages: solid-state deposition of dense, homogeneous, and pore-free coatings onto a range of substrates; and high build rate at reduced operating costs without the use of expensive heating and process inert gases. Depositing coatings with excellent performance indicators via LACS demands an accurate knowledge and control of processing and materials' variables. By varying the LACS process parameters and their interactions, the functional properties of coatings can be manipulated. Moreover, thermal effect due to laser irradiation and microstructural evolution complicate the interpretation of LACS mechanical deformation mechanism which is essential for elucidating its physical phenomena. In order to provide a basis for follow-on-research that leads to the development of high-productivity LACS processing of coatings, this review focuses on the latest developments in depositing corrosion- and wear-resistant coatings with the emphasis on the composition, structure, and mechanical and functional properties. Historical developments and fundamentals of LACS are addressed in an attempt to describe the physics behind the process. Typical technological applications of LACS coatings are also identified. The investigations of all process sequences, from laser irradiation of the powder-laden gas stream and the substrate, to the impingement of thermally softened particles on the deposition site, and subsequent further processes, are described. Existing gaps in the literature relating to LACS-dependent microstructural evolution, mechanical deformation mechanisms, correlation between functional properties and process parameters, processing challenges, and industrial applications have been identified in order to provide insights for further investigations and innovation in LACS deposition of wear- and corrosion-resistant coatings.

  20. Entrapment of subtilisin in ceramic sol-gel coating for antifouling applications.

    Science.gov (United States)

    Regina, Viduthalai Rasheedkhan; Søhoel, Helmer; Lokanathan, Arcot Raghupathi; Bischoff, Claus; Kingshott, Peter; Revsbech, Niels Peter; Meyer, Rikke Louise

    2012-11-01

    Enzymes with antifouling properties are of great interest in developing nontoxic antifouling coatings. A bottleneck in developing enzyme-based antifouling coatings is to immobilize the enzyme in a suitable coating matrix without compromising its activity and stability. Entrapment of enzymes in ceramics using the sol-gel method is known to have several advantages over other immobilization methods. The sol-gel method can be used to make robust coatings, and the aim of this study was to explore if sol-gel technology can be used to develop robust coatings harboring active enzymes for antifouling applications. We successfully entrapped a protease, subtilisin (Savinase, Novozymes), in a ceramic coating using a sol-gel method. The sol-gel formulation, when coated on a stainless steel surface, adhered strongly and cured at room temperature in less than 8 h. The resultant coating was smoother and less hydrophobic than stainless steel. Changes in the coating's surface structure, thickness and chemistry indicate that the coating undergoes gradual erosion in aqueous medium, which results in release of subtilisin. Subtilisin activity in the coating increased initially, and then gradually decreased. After 9 months, 13% of the initial enzyme activity remained. Compared to stainless steel, the sol-gel-coated surfaces with active subtilisin were able to reduce bacterial attachment of both Gram positive and Gram negative bacteria by 2 orders of magnitude. Together, our results demonstrate that the sol-gel method is a promising coating technology for entrapping active enzymes, presenting an interesting avenue for enzyme-based antifouling solutions.

  1. Characterization and durability testing of plasma-sprayed zirconia-yttria and hafnia-yttria thermal barrier coatings. Part 2: Effect of spray parameters on the performance of several hafnia-yttria and zirconia-yttria coatings

    Science.gov (United States)

    Miller, Robert A.; Leissler, George W.

    1993-01-01

    This is the second of two reports which discuss initial experiments on thermal barrier coatings prepared and tested in newly upgraded plasma spray and burner rig test facilities at LeRC. The first report, part 1, describes experiments designed to establish the spray parameters for the baseline zirconia-yttria coating. Coating quality was judged primarily by the response to burner rig exposure, together with a variety of other characterization approaches including thermal diffusivity measurements. That portion of the study showed that the performance of the baseline NASA coating was not strongly sensitive to processing parameters. In this second part of the study, new hafnia-yttria coatings were evaluated with respect to both baseline and alternate zirconia-yttria coatings. The hafnia-yttria and the alternate zirconia-yttria coatings were very sensitive to plasma-spray parameters in that high-quality coatings were obtained only when specific parameters were used. The reasons for this important observation are not understood.

  2. Optimising the in vitro and in vivo performance of oral cocrystal formulations via spray coating.

    Science.gov (United States)

    Serrano, Dolores R; Walsh, David; O'Connell, Peter; Mugheirbi, Naila A; Worku, Zelalem Ayenew; Bolas-Fernandez, Francisco; Galiana, Carolina; Dea-Ayuela, Maria Auxiliadora; Healy, Anne Marie

    2018-03-01

    Engineering of pharmaceutical cocrystals is an advantageous alternative to salt formation for improving the aqueous solubility of hydrophobic drugs. Although, spray drying is a well-established scale-up technique in the production of cocrystals, several issues can arise such as sublimation or stickiness due to low glass transition temperatures of some organic molecules, making the process very challenging. Even though, fluidised bed spray coating has been successfully employed in the production of amorphous drug-coated particles, to the best of our knowledge, it has never been employed in the production of cocrystals. The feasibility of this technique was proven using three model cocrystals: sulfadimidine (SDM)/4-aminosalicylic acid (4ASA), sulfadimidine/nicotinic acid (NA) and ibuprofen (IBU)/ nicotinamide (NAM). Design of experiments were performed to understand the critical formulation and process parameters that determine the formation of either cocrystal or coamorphous systems for SDM/4ASA. The amount and type of binder played a key role in the overall solid state and in vitro performance characteristics of the cocrystals. The optimal balance between high loading efficiencies and high degree of crystallinity was achieved only when a binder: cocrystal weight ratio of 5:95 or 10:90 was used. The cocrystal coated beads showed an improved in vitro-in vivo performance characterised by: (i) no tendency to aggregate in aqueous media compared to spray dried formulations, (ii) enhanced in vitro activity (1.8-fold greater) against S. aureus, (iii) larger oral absorption and bioavailability (2.2-fold higher C max ), (iv) greater flow properties and (v) improved chemical stability than cocrystals produced by other methods derived from the morphology and solid nature of the starter cores. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Modeling of air-droplet interaction, substrate melting and coating buildup in thermal spraying

    Science.gov (United States)

    Wei, Guanghua

    Among the many surface coating techniques now available, thermal spray is known to offer the most advantages. It can meet a wide range of technical and engineering requirements in a relatively inexpensive and easily controllable way with the capability of producing repeatable results. In the last few decades a lot of important strides have been made in the field of measurements and modelling of thermal spraying. However, due to the complex of the process and the lack of basic materials-based knowledge about the particle melting, spreading and deposition, the relationship between the process parameters and the coating properties still remains unclear. In thermal spraying, a particle is melted to form a droplet with morphology and thermal- and kinetic-energy status change by the interaction with the plasma/flame. In order to produce higher-quality coatings and expand the use of this versatile family of technologies, modelling of the particle behaviors during in-flight, spreading and deposition is essential. This thesis investigates the connections between particle characteristics and coating properties. Momentum, heat and mass transfer phenomena related to particle in-flight, droplet impacting, spreading, and splat layering are studied. Numerical models are developed to establish the quantitative relationships between spray parameters, particle and substrate properties and deposition characteristics. Most existing theoretical studies of in-flight particle assume that the particle is in a spherical shape without voids inside. The behavior of porous particles in thermal spray has not been well understood. However, the presence of voids in the feedstock powders may have a great impact on particle in-flight behaviors such as particle acceleration, melting and oxidation because a hollowed particle is also lighter than a densed one and this will affect the particle trajectory. The particle shape also needs to be taken into account because it influences the drag force and

  4. Comparison of in vitro behavior of as-sprayed, alkaline-treated and collagen-treated bioceramic coatings obtained by high velocity oxy-fuel spray

    International Nuclear Information System (INIS)

    Melero, H.; Garcia-Giralt, N.; Fernández, J.; Díez-Pérez, A.; Guilemany, J.M.

    2014-01-01

    Hydroxyapatite (HAp)–TiO 2 samples obtained using high velocity oxy-fuel spray (HVOF), that had previously shown excellent mechanical behaviour, were innovatively surface treated in order to improve their biological performance. The chosen treatments were an alkaline treatment to increase –OH radicals density on the surface (especially on TiO 2 zones), and a collagen treatment to bond collagen fibrils to the –OH radicals present in hydroxyapatite. These coatings were analysed using scanning electron microscopy, energy-dispersive X-ray spectroscopy and infrared spectroscopy, and tested for human osteoblast biocompatibility and functionality. In the case of the alkaline treatment, although the –OH radicals density did not increase compared to the as-sprayed coatings, a nanostructured layer of sodium hydroxycarbonate precipitated on the surface, thus improving biological behaviour due to the nanoroughness effect. For the collagen-treated samples, collagen fibrils appeared well-adhered to the surface, and in vitro cell culture tests showed that these surfaces were much more conducive to cell adhesion and differentiation than the as-sprayed and alkaline-treated samples. These results pointed to collagen treatment as a very promising method to improve bioactivity of HAp–TiO 2 thermal-sprayed coatings.

  5. Compositions of corrosion-resistant Fe-based amorphous metals suitable for producing thermal spray coatings

    Science.gov (United States)

    Farmer, Joseph C; Wong, Frank M.G.; Haslam, Jeffery J; Ji, Xiaoyan; Day, Sumner D; Blue, Craig A; Rivard, John D.K.; Aprigliano, Louis F; Kohler, Leslie K; Bayles, Robert; Lemieux, Edward J; Yang, Nancy; Perepezko, John H; Kaufman, Larry; Heuer, Arthur; Lavernia, Enrique J

    2013-09-03

    A method of coating a surface comprising providing a source of amorphous metal that contains manganese (1 to 3 atomic %), yttrium (0.1 to 10 atomic %), and silicon (0.3 to 3.1 atomic %) in the range of composition given in parentheses; and that contains the following elements in the specified range of composition given in parentheses: chromium (15 to 20 atomic %), molybdenum (2 to 15 atomic %), tungsten (1 to 3 atomic %), boron (5 to 16 atomic %), carbon (3 to 16 atomic %), and the balance iron; and applying said amorphous metal to the surface by a spray.

  6. High resolution microstructure characterization of the interface between cold sprayed Al coating and Mg alloy substrate

    International Nuclear Information System (INIS)

    Wang, Qiang; Qiu, Dong; Xiong, Yuming; Birbilis, Nick; Zhang, Ming-Xing

    2014-01-01

    High-resolution transmission electron microscopy (HR-TEM) has validated the intimate metallurgical (atomic) bond formed along the interface of a cold-sprayed Al coating upon an Mg-alloy (AZ91) substrate. The compressive impact led to the formation of nanostructured layers of about 300–500 nm into the substrate. A highly distorted lattice structure with the inclusion of small amorphous zones was observed at the periphery of the particle/substrate interface, as a result of adiabatic shear plastic deformation at a high strain rate.

  7. In-situ observation of crack propagation in thermally sprayed coatings

    Czech Academy of Sciences Publication Activity Database

    Mušálek, R.; Kovářík, O.; Matějíček, Jiří

    2010-01-01

    Roč. 205, č. 7 (2010), s. 1807-1811 ISSN 0257-8972 R&D Projects: GA MŠk ME 901 Institutional research plan: CEZ:AV0Z20430508 Keywords : coating fracture * in-situ observation * alumina * stainless steel * plasma spraying Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.135, year: 2010 http://www.sciencedirect.com/science?_ob=GatewayURL&_method=citationSearch&_uoikey=B6TVV-4YTFBCY-5&_origin=SDEMFRHTML&_version=1&md5=896533bcc989ebaa374ff209558fbcf1

  8. High-Temperature Solid Lubricant Coating by Plasma Spraying Using Metal-Metal Clad Powders

    Science.gov (United States)

    Zhang, Tiantian; Lan, Hao; Yu, Shouquan; Huang, Chuanbing; Du, Lingzhong; Zhang, Weigang

    2017-08-01

    NiCr/Ag-Mo composite coating was fabricated by atmospheric plasma spray technology using clad powders as the feedstock. Its tribological properties at variable temperature were evaluated using a ball-on-disk high-temperature tribometer in air. The results showed that compared with NiCr, the NiCr/Ag-Mo composite coating exhibited better lubrication effect and higher wear resistance at all test temperatures, especially above 600 °C. At 800 °C, NiCr/Ag-Mo composite coating showed the lowest friction coefficient of about 0.2 and its corresponding wear rate reached 2.5 × 10-5 mm3/Nm. Characterizations of NiCr/Ag-Mo composite coating revealed that at temperatures below 400 °C, Ag was smeared and spread onto the wear surface, reducing the friction and wear. At temperature above 500 °C, the Ag2MoO4 lubrication film formed by tribo-oxidation significantly improved the coating's lubrication effect and wear resistance.

  9. Thermal spraying of functionally graded calcium phosphate coatings for biomedical implants

    Science.gov (United States)

    Wang, Y.; Khor, K. A.; Cheang, P.

    1998-03-01

    Biomedical requirements in a prosthesis are often complex and diverse in nature. Biomaterials for implants have to display a wide range of adaptability to suit the various stages of the bio-integration process of any foreign material into the human body. Often, a combination of materials is needed. The preparation of a functionally graded bioceramic coating composed of essentially calcium phosphate compounds is explored. The coating is graded in accordance to adhesive strength, bioactivity, and bioresorbability. The bond coat on the Ti-6Al-4V stub is deposited with a particle range of the hydroxyapatite (HA) that will provide a high adhesive strength and bioactivity but have poor bioresorption properties. The top coat, however, is composed of predominantly α-tricalcium phosphate (α-TCP) that is highly bioresorbable. This arrangement has the propensity of allowing accelerated bio-integration of the coating by the body tissues as the top layer is rapidly resorbed, leaving the more bioactive intermediate layer to facilitate the much needed bioactive properties for proper osteoconduction. The processing steps and problems are highlighted, as well as the results of post-spray heat treatment.

  10. Plasma Sprayed Bondable Stainless Surface (BOSS) Coatings for Corrosion Protection and Adhesion Treatments

    Science.gov (United States)

    Davis, G. D.; Groff, G. B.; Rooney, M.; Cooke, A. V.; Boothe, R.

    1995-01-01

    Plasma-sprayed Bondable Stainless Surface (BOSS) coatings are being developed under the Solid Propulsion Integrity Program's (SPIP) Bondlines Package. These coatings are designed as a steel case preparation treatment prior to insulation lay-up. Other uses include the exterior of steel cases and bonding surfaces of nozzle components. They provide excellent bondability - rubber insulation and epoxy bonds fail cohesively within the polymer - for both fresh surfaces and surfaces having undergone natural and accelerated environmental aging. They have passed the MSFC requirements for protection of inland and sea coast environment. Because BOSS coatings are inherently corrosion resistant, they do not require preservation by greases or oils. The reduction/elimination of greases and oils, known bondline degraders, can increase SRM reliability, decrease costs by reducing the number of process steps, and decrease environmental pollution by reducing the amount of methyl chloroform used for degreasing and thus reduce release of the ozone-depleting chemical in accordance with the Clean Air Act and the Montreal Protocol. The coatings can potential extend the life of RSRM case segments and nozzle components by eliminating erosion due to multiple grit blasting during each use cycle and corrosion damage during marine recovery. Concurrent work for the Air Force show that other BOSS coatings give excellent bondline strength and durability for high-performance structures of aluminum and titanium.

  11. Particle emission rates during electrostatic spray deposition of TiO2 nanoparticle-based photoactive coating

    DEFF Research Database (Denmark)

    Koivisto, Antti J.; Jensen, Alexander C. Ø.; Kling, Kirsten I.

    2017-01-01

    Here, we studied the particle release rate during Electrostatic spray deposition of anatase-(TiO2)-based photoactive coating onto tiles and wallpaper using a commercially available electrostatic spray device. Spraying was performed in a 20.3m3 test chamber while measuring concentrations of 5.6nm...... particlesconsisted of mainly TiO2, TiO2 mixed with Cl and/or Ag, TiO2particles coated with carbon, and Ag particles with size ranging from 60 nm to ca. 5 μm. As expected, no significant VOC emissions were observed as a result of spraying. Finally, we provide recommendations for exposure model parameterization....

  12. Corrosion protection of SiC-based ceramics with CVDMullite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Sarin, V.; Auger, M. [Boston Univ., MA (United States)

    1997-05-01

    Silicon carbide ceramics are the leading candidate materials for use as heat exchangers in advanced combined cycle power plants because of their unique combination of high temperature strength, high thermal conductivity, excellent thermal shock resistance, and good high temperature stability and oxidation resistance. Ceramic coatings are being considered for diesel engine cylinder liners, piston caps, valve faces and seats, piston rings, and for turbine components such as combustors, blades, stators, seals, and bearings. Under such conditions ceramics are better suited to high temperature environments than metals. For the first time, adherent crystalline mullite coatings have been chemically vapor deposited onto SiC substrates to enhance its corrosion/oxidation resistance. Thermodynamic and kinetic considerations have been utilized to produce mullite coatings with a variety of growth rates, compositions, and morphologies. The flexibility of processing can be exploited to produce coated ceramics with properties tailored to specific applications and varied corrosive environments. These corrosive environments include thermal, Na{sub 2}SO{sub 4}, O{sub 2} and coal slag.

  13. Evaluation of the behavior of shrouded plasma spray coatings in the platen superheater of coal-fired boilers

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, B.S.; Prakash, S. [GZS College of Engineering & Technology, Bathinda (India). Dept. of Mechanical Engineering

    2006-06-15

    Nickel- and cobalt-based coatings were formulated by a shrouded plasma spray process on boiler tube steels, namely, ASTM-SA210-grade A1 (GrA1), ASTM-SA213-T-11 (T11), and ASTM-SA213-T-22 (T22). The Ni-22Cr-10A1-1Y alloy powder was sprayed as a bond in each case before the final coating. The degradation behavior of the bared and coated steels was studied in the platen superheater of the coal-fired boiler. The samples were inserted through the soot blower dummy points with the help of stainless steel wires. The coatings were found to be effective in increasing resistance to degradation in the given boiler environment. The maximum protection was observed in the case of Stellite-6 (St-6) coating.

  14. Synthesis of fluor-hydroxyapatite powder for plasma sprayed biomedical coatings: Characterization and improvement of the powder properties

    OpenAIRE

    Demnati, Imane; Grossin, David; Errassifi, Farid; Combes, Christèle; Rey, Christian; Le Bolay, Nadine

    2014-01-01

    International audience; Fluor-hydroxyapatite (FHA) powder was synthesized by double decomposition in a view to produce bioactive and thermally stable coatings by plasma spray process. This work aims at studying the influence of chemical composition, microstructure and surface energy on the flowability of the FHA particles which is known as a determinant property during plasma spraying for the quality of the product in terms of yield and homogeneity of composition. The as-synthesized FHA powde...

  15. Microstructures of Metallic NiCrBSi Coatings Manufactured via Hybrid Plasma Spray and In Situ Laser Remelting Process

    OpenAIRE

    Serres, Nicolas; Hlawka, Françoise; Costil, Sophie; Langlade, Cécile; Machi, Frédérique

    2011-01-01

    International audience; This paper deals with coating alternatives to hard chromium plating. Thermal spraying is already used in industry, but results are not always satisfactory for reasons of porosity and microstructures. In this study, atmospheric plasma spraying (APS) and in situ laser irradiation by diode laser processes were combined to modify the structural characteristics of thick NiCrBSi alloy layers. The microstructure evolution was studied, and results show that in situ laser remel...

  16. Bioactive ceramic coating of cancellous screws improves the osseointegration in the cancellous bone.

    Science.gov (United States)

    Lee, Jae Hyup; Nam, Hwa; Ryu, Hyun-Seung; Seo, Jun-Hyuk; Chang, Bong-Soon; Lee, Choon-Ki

    2011-05-01

    A number of methods for coating implants with bioactive ceramics have been reported to improve osseointegration in bone, but the effects of bioactive ceramic coatings on the osseointegration of cancellous screws are not known. Accordingly, biomechanical and histomorphometric analyses of the bone-screw interface of uncoated cancellous screws and cancellous screws coated with four different bioactive ceramics were performed. After coating titanium alloy cancellous screws with calcium pyrophosphate (CPP), CaO-SiO(2)-B(2)O(3) glass-ceramics (CSG), apatite-wollastonite 1:3 glass-ceramics (W3G), and CaO-SiO(2)-P(2)O(5)-B(2)O(3) glass-ceramics (BGS-7) using an enameling method, the coated and the uncoated screws were inserted into the proximal tibia and distal femur metaphysis of seven male mongrel dogs. The torque values of the screws were measured at the time of insertion and at removal after 8 weeks. The bone-screw contact ratio was analyzed by histomorphometry. There was no significant difference in the insertion torque between the uncoated and coated screws. The torque values of the CPP and BGS-7 groups measured at removal after 8 weeks were significantly higher than those of the uncoated group. Moreover, the values of the CPP and BGS-7 groups were significantly higher than the insertion torques. The fraction of bone-screw interface measured from the undecalcified histological slide showed that the CPP, W3G, and BGS-7 groups had significantly higher torque values in the cortical bone area than the uncoated group, and the CPP and BGS-7 groups had significantly higher torque values in the cancellous bone area than the uncoated group. In conclusion, a cancellous screw coated with CPP and BGS-7 ceramic bonds directly to cancellous bone to improve the bone-implant osseointegration. This may broaden the indications for cancellous screws by clarifying their contribution to improving osseointegration, even in the cancellous bone area.

  17. 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.

  18. Positioning system of a torch used in thermal spray coatings applications

    Directory of Open Access Journals (Sweden)

    Edgar Absalón Torres-Barahona

    2016-07-01

    Full Text Available This paper presents the design, construction and performance evaluation of a positioning system used for the deposition of coatings with molten particles, by using a torch CastoDyn Ds 8000 thermal spray with oxyacetylene combustion. The design has been done with parameters obtained in the laboratory of materials of the Universidad Pedagógica y Tecnológica de Colombia, and the information determined from the evaluation of the device, allows to control the main process variables as the projection distance, flow powder, torch speed and rotation speed of the sample holder; this has been seen in coatings made in application tests zirconia / nickel on a carbon steel substrate and analyzed with Scanning Electron Microscopy - SEM.

  19. Thermophysical, mechanical and microstructural characterization of aged free-standing plasma-sprayed zirconia coatings

    Energy Technology Data Exchange (ETDEWEB)

    Cernuschi, F. [CESI RICERCA, Via Rubattino 54, 20134 Milano (Italy)], E-mail: federico.cernuschi@cesiricerca.it; Bison, P.G.; Marinetti, S. [CNR ITC, Corso Stati Uniti 4, 35100 Padova (Italy); Scardi, P. [Department of Materials Engineering and Industrial Technologies, University of Trento, 38100 via Mesiano 77, Trento (Italy)

    2008-10-15

    The effect of porosity on the thermal diffusivity and elastic modulus has been studied on artificially aged, free-standing thermal barrier coatings (TBCs) produced by air plasma spray (APS). The activation energy of the sintering phenomenon was estimated from the variation in diffusivity with time and temperature. X-ray diffraction was used to evaluate the phase stability of 7 wt.% yttria partially stabilized zirconia (YPSZ) coatings. The thermal diffusivity and elastic modulus as measured by photothermal techniques and three-point bending, respectively, are reported as a function of the ageing time. Correlations between the thermal and mechanical parameters are investigated by suitable models based on the microstructural features revealed by electron microscopy. The reliability of porosity information provided by image analysis and used as input for the modelling is critically discussed.

  20. Thermophysical, mechanical and microstructural characterization of aged free-standing plasma-sprayed zirconia coatings

    International Nuclear Information System (INIS)

    Cernuschi, F.; Bison, P.G.; Marinetti, S.; Scardi, P.

    2008-01-01

    The effect of porosity on the thermal diffusivity and elastic modulus has been studied on artificially aged, free-standing thermal barrier coatings (TBCs) produced by air plasma spray (APS). The activation energy of the sintering phenomenon was estimated from the variation in diffusivity with time and temperature. X-ray diffraction was used to evaluate the phase stability of 7 wt.% yttria partially stabilized zirconia (YPSZ) coatings. The thermal diffusivity and elastic modulus as measured by photothermal techniques and three-point bending, respectively, are reported as a function of the ageing time. Correlations between the thermal and mechanical parameters are investigated by suitable models based on the microstructural features revealed by electron microscopy. The reliability of porosity information provided by image analysis and used as input for the modelling is critically discussed

  1. Synthesis, characterization and physical properties of Al-Cu-Fe quasicrystalline plasma sprayed coatings

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, Sordelet [Iowa State Univ., Ames, IA (United States)

    1995-11-09

    Our lab has been working with plasma spraying of both high pressure gas atomized (HPGA) and cast and crushed quasicrystal powders. A major component of this research includes comparative studies of PAS coatings formed with starting powders prepared by both techniques. In addition, a thorough investigation of the effects of starting powder particle size on coating microstructure is included. During the course of the overall research, an interest developed in forming Al-Cu-Fe materials with finer grain sizes. Therefore, a brief study was performed to characterize the effect of adding boron to Al-Cu-Fe materials prepared by different techniques. In addition to characterizing the microstructural features of the above materials, oxidation and wear behavior was also examined.

  2. Comparison between alkali heat treatment and sprayed hydroxyapatite coating on thermally-sprayed rough Ti surface in rabbit model: Effects on bone-bonding ability and osteoconductivity.

    Science.gov (United States)

    Kawai, Toshiyuki; Takemoto, Mitsuru; Fujibayashi, Shunsuke; Tanaka, Masashi; Akiyama, Haruhiko; Nakamura, Takashi; Matsuda, Shuichi

    2015-07-01

    In this study, we investigated the effect of different surface treatments (hydroxyapatite (HA) coating, alkali heat treatment, and no treatment) on the ability of bone to bond to a rough arc-sprayed Ti metal surface, using rabbit models. The bone-to-implant contacts for untreated, HA-coated, and alkali heat-treated implants were 21.2%, 72.1%, and 33.8% at 4 weeks, 21.8%, 70.9%, and 30.0% at 8 weeks, and 16.3%, 70.2%, and 29.9% at 16 weeks, respectively (n = 8). HA -coated implants showed significantly higher bone-to-implant contacts than the untreated and alkali heat-treated implants at all the time point, whereas alkali heat-treated implants showed significantly higher bone-to-implant contacts than untreated implants at 4 and 16 weeks. The failure loads in a mechanical test for untreated, HA coated, alkali heat-treated plates were 65.4 N, 70.7 N, and 90.8 N at 4 weeks, 76.1 N, 64.7 N, and 104.8 N at 8 weeks and 88.7 N, 92.6 N, and 118.5 N at 16 weeks, respectively (n = 8). The alkali heat-treated plates showed significantly higher failure loads than HA-coated plates at 8 and 16 weeks. The difference between HA-coated plates and untreated plates were not statistically significant at any time point. Thus HA coating, although it enables high bone-to-implant contact, may not enhance the bone-bonding properties of thermally-sprayed rough Ti metal surfaces. In contrast, alkali heat treatment can be successfully applied to thermally-sprayed Ti metal to enhance both bone-to-implant contact and bone-bonding strength. © 2014 Wiley Periodicals, Inc.

  3. 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.

  4. Design and characterization of a carbon-nanotube-reinforced adhesive coating for piezoelectric ceramic discs

    International Nuclear Information System (INIS)

    Lanzara, G; Chang, F-K

    2009-01-01

    The silver paste electrode of piezoelectric (PZT) ceramic discs has been shown to produce a weak interface bond between a bare PZT and its paste coating under a peeling force. In this work, an investigation was conducted to reinforce the bond with a high density array of oriented carbon nanotube nano-electrodes (CNTs-NEA), between a bare PZT ceramic and a metal substrate. The ensuing design and fabrication of a carbon-nanotube-coated piezoelectric disc (CPZT) is presented along with a study of the bondline integrity of a CPZT mounted on a hosting structure. The CPZT has its electrode silver paste coating replaced with a high density array of CNTs-NEA. Mechanical tests were performed to characterize the shear strength of the bondline between CPZT discs and the substrate. The test results were compared with shear strengths of the bondlines made of pure non-conductive adhesive and adhesive with randomly mixed CNTs. The comparison showed the oriented CNT coating on PZTs could significantly enhance the interfacial shear strength. Through the microscopic examination, it was evident that the ratio between the CNT length (Lc) and the bond thickness (H) significantly influenced the bond strength of CPZT discs. Three major interface microstructure types and their corresponding failure modes for specific Lc/H values were identified. The study also showed that failure did not occur along the interface between the PZT ceramic element and the CNT coating

  5. Comparative assessment of coated and uncoated ceramic tools on ...

    Indian Academy of Sciences (India)

    H Aouici

    2017-11-20

    Nov 20, 2017 ... icant impact on the cutting force, cutting pressure and cutting power. In another recent work, Meddour et al [20] applied the RSM to investigate the effect of cutting parameters on cutting forces and surface roughness in hard turning of AISI 52100 steel with a ceramic tool. The study indicated that the depth of ...

  6. Durability of zirconia thermal-barrier ceramic coatings on air-cooled turbine blades in cyclic jet engine operation

    Science.gov (United States)

    Liebert, C. H.; Jacobs, R. E.; Stecura, S.; Morse, C. R.

    1976-01-01

    Thermal barrier ceramic coatings of stabilized zirconia over a bond coat of Ni Cr Al Y were tested for durability on air cooled turbine rotor blades in a research turbojet engine. Zirconia stabilized with either yttria, magnesia, or calcia was investigated. On the basis of durability and processing cost, the yttria stabilized zirconia was considered the best of the three coatings investigated.

  7. Nanocrystalline, superhard, ductile ceramic coatings for roller-cone bit bearings

    Energy Technology Data Exchange (ETDEWEB)

    Namavar, F.; Colter, P.; Karimy, H. [Spire Corp., Bedford, MA (United States)] [and others

    1997-12-31

    The established method for construction of roller bits utilizes carburized steel, frequently with inserted metal bearing surfaces. This construction provides the necessary surface hardness while maintaining other desirable properties in the core. Protective coatings are a logical development where enhanced hardness, wear resistance, corrosion resistance, and surface properties are required. The wear properties of geothermal roller-cone bit bearings could be further improved by application of protective ceramic hard coatings consisting of nanometer-sized crystallites. Nanocrystalline protective coatings provide the required combination of hardness and toughness which has not been available thus far using traditional ceramics having larger grains. Increased durability of roller-cone bit bearings will ultimately reduce the cost of drilling geothermal wells through increased durability.

  8. Spray-Coated Multiwalled Carbon Nanotube Composite Electrodes for Thermal Energy Scavenging Electrochemical Cells.

    Science.gov (United States)

    Holubowitch, Nicolas E; Landon, James; Lippert, Cameron A; Craddock, John D; Weisenberger, Matthew C; Liu, Kunlei

    2016-08-31

    Spray-coated multiwalled carbon nanotube/poly(vinylidene fluoride) (MWCNT/PVDF) composite electrodes, scCNTs, with varying CNT compositions (2 to 70 wt %) are presented for use in a simple thermal energy-scavenging cell (thermocell) based on the ferro/ferricyanide redox couple. Their utility for direct thermal-to-electrical energy conversion is explored at various temperature differentials and cell orientations. Performance is compared to that of buckypaper, a 100% CNT sheet material used as a benchmark electrode in thermocell research. The 30 to 70 wt % scCNT composites give the highest power output by electrode area-seven times greater than buckypaper at ΔT = 50 °C. CNT utilization is drastically enhanced in our electrodes, reaching 1 W gCNT(-1) compared to 0.036 W gCNT(-1) for buckypaper. Superior performance of our spray-coated electrodes is attributed to both wettability with better use of a large portion of electrochemically active CNTs and minimization of ohmic and thermal contact resistances. Even composites with as low as 2 wt % CNTs are still competitive with prior art. The MWCNT/PVDF composites developed herein are inexpensive, scalable, and serve a general need for CNT electrode optimization in next-generation devices.

  9. Heat treated twin wire arc spray AISI 420 coatings under dry and wet abrasive wear

    Science.gov (United States)

    Rodriguez, E.; González, M. A.; Monjardín, H. R.; Jimenez, O.; Flores, M.; Ibarra, J.

    2017-11-01

    The influence of applying two different heat treatments such as: deep cryogenic and tempering on dry/wet abrasive wear resistance of twin wire arc spray martensitic AISI 420 coatings was evaluated by using a modified rubber wheel type test apparatus. A load dependency was observed on the abrasive wear rate behavior of both; dry and wet tests. Three body (rolling) and two body (sliding) wear mechanisms were identified in dry conditions, prevailing rolling at lower and higher loads. However, at higher loads, more presence of grooving and pits formation was observed. Coatings tempered at 205 °C/1 h displayed better wear resistance than cryogenic treated ones. A change in wear mechanism between dry and wet conditions was observed; two body wear mechanism predominated respect to three body. In both; dry and wet conditions the microstructure (several inter-splat oxides) as well as strain and residual stress promotes brittle material removal which was more evident in cryogenic and as-sprayed samples during dry test and at higher loads in wet conditions.

  10. 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.

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

    Science.gov (United States)

    Liu, Ting; Zheng, Lili; Zhang, Hui

    2016-12-01

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

  12. Effect of the Cold-Sprayed Aluminum Coating-Substrate Interface Morphology on Bond Strength for Aircraft Repair Application

    Science.gov (United States)

    Blochet, Quentin; Delloro, Francesco; N'Guyen, Franck; Jeulin, Dominique; Borit, François; Jeandin, Michel

    2017-04-01

    This article is dealing with the effects of surface preparation of the substrate on aluminum cold-sprayed coating bond strength. Different sets of AA2024-T3 specimens have been coated with pure Al 1050 feedstock powder, using a conventional cold spray coating technique. The sets were grit-blasted (GB) before coating. The study focuses on substrate surface topography evolution before coating and coating-substrate interface morphology after coating. To study coating adhesion by LASAT® technique for each set, specimens with and without preceding GB treatment were tested in load-controlled conditions. Then, several techniques were used to evaluate the effects of substrate surface treatment on the final coating mechanical properties. Irregularities induced by the GB treatment modify significantly the interface morphology. Results showed that particle anchoring was improved dramatically by the presence of craters. The substrate surface was characterized by numerous anchors. Numerical simulation results exhibited the increasing deformation of particle onto the grit-blasted surface. In addition, results showed a strong relationship between the coating-substrate bond strength on the deposited material and surface preparation.

  13. Solar selective coatings based on nickel oxide obtained via spray pyrolysis.

    Science.gov (United States)

    Voinea, Mihaela; Ienei, Elena; Bogatu, Cristina; Duta, Anca

    2009-07-01

    The paper presents the optimization process for obtaining NiO thin layers on copper substrate for solar absorber coatings, using an inexpensive and up-scalable technique: spray pyrolysis deposition (SPD). Efficient selective coatings must present a high absorption coefficient of the incident solar irradiation, and low emission of heat. The solar selective coatings design involves tailoring the surface properties for superior optical properties. The deposition parameters were varied for maximizing the solar absorbance and minimizing the thermal emittance. The film morphology was controlled using copolymers of the maleic anhydride as additives into the precursors' solution. The structural and surface properties of the films were investigated by X-ray diffraction and atomic force microscopy, respectively. The Cu/CuO(x)/NiO solar absorber shows good values for the solar absorptance (alpha(s) = 0.95) and thermal emittance (epsilon(T) = 0.05) compared with the ones obtained by other methods employed in literature and new additives are recommended in tailoring the surface of solar selective coatings.

  14. The characteristics of alumina scales formed on HVOF-sprayed MCrAlY coatings

    International Nuclear Information System (INIS)

    Toma, D.; Brandl, W.; Koester, U.

    2000-01-01

    HVOF MCrAlY (M = Ni, Co) coatings were isothermally oxidized in synthetic air between 850 and 1050 C for times up to 167 hr. During thermal spraying, aluminum and yttrium oxidized to form a fine oxide dispersion. The HVOF MCrAlY coatings exhibited a microstructure similar to ODS alloys. The fine dispersion consisted of Al 2 O 3 and aluminum-yttrium oxides. The oxidation experiments showed that the oxidation rate of HVOF coatings was two times slower than the oxidation rate of VPS MCrAlY coatings. The oxidation mechanism changed mainly in the transient-stage (no metastable modification of Al 2 O 3 formed) and it was assumed that the oxide dispersion hindered diffusion of various elements from the bulk material during oxidation. The formation of the fine oxide dispersion also influenced the adherence of the oxide scale. The microstructures of the transient oxide scales were examined by X-ray diffraction (XRD) scanning electron microscopy (SEM), and transmission electron microscopy (TEM)

  15. Preparation and structures of plasma-sprayed γ- and α-Al2O3 coatings

    International Nuclear Information System (INIS)

    Heintze, G.N.; Uematsu, S.

    1992-01-01

    As-sprayed Al 2 O 3 coatings containing more than 99.5% γ-Al 2 O 3 were prepared by optimizing torch parameters. Lamellae were 1-4 μm thick with grains ranging from 0.1 to 1 μm in diameter. Using the same torch conditions, but slowly traversing the torch over the substrate, coatings containing α-Al 2 O 3 were produced. Three types of microstructures were observed in each pass of the torch: type I, in the lower region, believed to have nucleated as γ-Al 2 O 3 and transformed to α-Al 2 O 3 from the heat of the torch and coating; type II, above type I, which nucleated as α-Al 2 O 3 and had separate lamellae because solidifiction was completed before the next droplet arrived; type III, in the upper region, which nucleated as α-Al 2 O 3 and contained grains over 200 μm in length because the previous droplet had not finished solidifying before the next droplet impacted. Thermal expansion and pore size distributions were measured, as also were temperatures within the coatings during their deposition. (orig.)

  16. Substrate-Coated Illumination Droplet Spray Ionization: Real-Time Monitoring of Photocatalytic Reactions.

    Science.gov (United States)

    Zhang, Hong; Li, Na; Zhao, Dandan; Jiang, Jie; You, Hong

    2017-09-01

    Real-time monitoring of photocatalytic reactions facilitates the elucidation of the mechanisms of the reactions. However, suitable tools for real-time monitoring are lacking. Herein, a novel method based on droplet spray ionization named substrate-coated illumination droplet spray ionization (SCI-DSI) for direct analysis of photocatalytic reaction solution is reported. SCI-DSI addresses many of the analytical limitations of electrospray ionization (ESI) for analysis of photocatalytic-reaction intermediates, and has potential for both in situ analysis and real-time monitoring of photocatalytic reactions. In SCI-DSI-mass spectrometry (MS), a photocatalytic reaction occurs by loading sample solutions onto the substrate-coated cover slip and by applying UV light above the modified slip; one corner of this slip adjacent to the inlet of a mass spectrometer is the high-electric-field location for launching a charged-droplet spray. After both testing and optimizing the performance of SCI-DSI, the value of this method for in situ analysis and real-time monitoring of photocatalytic reactions was demonstrated by the removal of cyclophosphamide (CP) in TiO 2 /UV. Reaction times ranged from seconds to minutes, and the proposed reaction intermediates were captured and identified by tandem mass spectrometry. Moreover, the free hydroxyl radical (·OH) was identified as the main radicals for CP removal. These results show that SCI-DSI is suitable for in situ analysis and real-time monitoring of CP removal under TiO 2 -based photocatalytic reactions. SCI-DSI is also a potential tool for in situ analysis and real-time assessment of the roles of radicals during CP removal under TiO 2 -based photocatalytic reactions.Graphical Abstract.

  17. Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

    International Nuclear Information System (INIS)

    Wang, Jun-Hua; Wang, Jin; Lu, Yan; Du, Mao-Hua; Han, Fu-Zhu

    2015-01-01

    Highlights: • Single pulse energy remarkably influences the properties of ceramic coating prepared by MAO on Ti alloy. • The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. • The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. • Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. • The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle. - Abstract: The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti–6Al–4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO 2 , anatase TiO 2 , and a large amount of Al 2 TiO 5 . The effects of single pulse

  18. Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun-Hua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Wang, Jin [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China); Lu, Yan [School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Du, Mao-Hua [Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Han, Fu-Zhu, E-mail: hanfuzhu@mail.tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China)

    2015-01-01

    Highlights: • Single pulse energy remarkably influences the properties of ceramic coating prepared by MAO on Ti alloy. • The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. • The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. • Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. • The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle. - Abstract: The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti–6Al–4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO{sub 2}, anatase TiO{sub 2}, and a large amount of Al{sub 2}TiO{sub 5}. The effects of

  19. Microstructure evolution and mechanical properties of TiCN-Cr nano/micro composite coatings prepared by reactive plasma spraying

    Science.gov (United States)

    Zhang, Fanyong; He, Jining; Chen, Kai; Qin, Yanfang; Li, Chao; Yin, Fuxing

    2018-01-01

    Nanostructured TiCN based composite coatings with various Cr content were prepared by reactive plasma spray (RPS) from mixed powder (Ti-graphite + Cr) under nitrogen atmosphere. Results showed that composite coatings consisted mainly of TiC0.7N0.3 phase and residual metal Cr. Metal Cr plates were homogeneously embedded in TiCN matrix with good interface bond. The TiCN-Cr composite coatings exhibited lower porosity than TiCN coatings, but increasing porosity with excess Cr addition (30 wt.%). The TiCN-20 wt.% Cr coating showed the highest hardness (1309 HV0.2) among composite coatings, slight lower than the TiCN matrix coating (1526 HV0.2). Compared with the TiCN matrix coating, the TiCN-Cr composite coatings showed higher variability in surface microhardness distribution. The TiCN-Cr composite coatings showed slight higher friction coefficients (0.4-0.6) than TiCN matrix coating (0.35). The wear resistance of TiCN-Cr composite coatings was improved with less mass loss compared with TiCN coating under the test load of 400 N. The TiCN-Cr composite coatings with high Cr content showed the mixture of abrasive and adhesive wear.

  20. Preparation and characterization of hydroxyapatite-coated iron oxide particles by spray-drying technique

    Directory of Open Access Journals (Sweden)

    karina Donadel

    2009-06-01

    Full Text Available Magnetic particles of iron oxide have been increasingly used in medical diagnosis by magnetic resonance imaging and in cancer therapies involving targeted drug delivery and magnetic hyperthermia. In this study we report the preparation and characterization of iron oxide particles coated with bioceramic hydroxyapatite by spray-drying. The iron oxide magnetic particles (IOMP were coated with hydroxyapatite (HAp by spray-drying using two IOMP/HAp ratios (0.7 and 3.2. The magnetic particles were characterized by way of scanning electronic microscopy, energy dispersive X-ray, X-ray diffraction, Fourier transformed infrared spectroscopy, flame atomic absorption spectrometry,vibrating sample magnetometry and particle size distribution (laser diffraction. The surface morphology of the coated samples is different from that of the iron oxide due to formation of hydroxyapatite coating. From an EDX analysis, it was verified that the surface of the coated magnetic particles is composed only of HAp, while the interior containsiron oxide and a few layers of HAp as expected. The results showed that spray-drying technique is an efficient and relatively inexpensive method for forming spherical particles with a core/shell structure.As partículas de óxido de ferro têm sido extensivamente usadas em diagnósticos médicos como agente de contraste para imagem por ressonância magnética e na terapia do câncer, dentre estas, liberação de fármacos em sitos alvos e hipertermia magnética. Neste estudo nós reportamos a preparação e caracterização de partículas magnéticas de óxido de ferro revestidas com a biocerâmica hidroxiapatita. As partículas magnéticasde óxido de ferro (PMOF foram revestidas com hidroxiapatita por spray-drying usando duas razões PMOF/HAp (0,7 e 3,2. As partículas magnéticas foram caracterizadas por microscopia eletrônica de varredura, energia dispersiva de raios X, difração de raios X, espectroscopia de absorção no infra