Academic literature on the topic 'Oxidation protection by thin ceramic coatings'
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Journal articles on the topic "Oxidation protection by thin ceramic coatings"
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Reis, Danieli A. P., Carlos de Moura Neto, Antônio Augusto Couto, Cosme Roberto Moreira Silva, Francisco Piorino Neto, and M. J. R. Barboza. "A Comparison between CoNiCrAlY Bond Coat and Zirconia Plasma Sprayed Coatings on Creep Tests." Materials Science Forum 591-593 (August 2008): 30–35. http://dx.doi.org/10.4028/www.scientific.net/msf.591-593.30.
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Thermomechanical and electrical properties of zirconia-based ceramics have led to a wide range of advanced and engineering ceramic applications like solid electrolyte in oxygen sensors, fuel cells and furnace elements and its low thermal conductivity has allowed its use for thermal barrier coatings for aerospace engine components. A comparison between CoNiCrAlY bond coat and zirconia plasma sprayed coatings on creep tests of the Ti-6Al-4V alloy was studied. The material used was commercial Ti-6Al-4V alloy. Yttria (8 wt.%) stabilized zirconia (YSZ) with a CoNiCrAlY bond coat was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco Type 9 MB. Constant load creep tests were conducted on a standard creep machine in air on coated samples, at stress levels of 520 MPa at 500°C to evaluate the oxidation protection on creep of the Ti-6Al-4V alloy. Results indicate that the creep resistance of the ceramic coating was greater than metallic coating.
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Wierzbicka, Ewa, Borja Pillado, Marta Mohedano, Raul Arrabal, and Endzhe Matykina. "Calcium Doped Flash-PEO Coatings for Corrosion Protection of Mg Alloy." Metals 10, no. 7 (July 9, 2020): 916. http://dx.doi.org/10.3390/met10070916.
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This study demonstrates a significant improvement of the corrosion resistance of an AZ31B magnesium alloy achieved by the application of 1 μm-thin coatings generated by an environmentally friendly flash plasma electrolytic oxidation (FPEO) process in Ca-containing electrolytes. Two compounds with different solubility, calcium oxide (CaO) or calcium glycerophosphate (CaGlyP), were used as sources of Ca in the electrolyte. Very short durations (20–45 s) of the FPEO process were employed with the aim of limiting the energy consumption. The corrosion performance of the developed coatings was compared with that of a commercial conversion coating (CC) of similar thickness. The viability of the coatings in a full system protection approach, consisting of FPEO combined with an inhibitor-free epoxy primer, was verified in neutral salt spray and paint adhesion tests. The superior corrosion performance of the FPEO_CaGlyP coating, both as a stand-alone coating and as a full system, was attributed to the formation of a greater complexity of Ca2+ bonds with SiO2 and PO43− species within the MgO ceramic network during the in situ incorporation of Ca into the coating from a double chelated electrolyte and the resultant difficulties with the hydrolysis of such a network. The deterioration of the FPEO_CaGlyP coating during immersion was found over ten times slower compared with Ca-free flash-PEO coating.
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Parchovianský, Milan, Ivana Parchovianská, Peter Švančárek, Günter Motz, and Dušan Galusek. "PDC Glass/Ceramic Coatings Applied to Differently Pretreated AISI441 Stainless Steel Substrates." Materials 13, no. 3 (January 31, 2020): 629. http://dx.doi.org/10.3390/ma13030629.
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In this work, the influence of different cleaning procedures on adhesion of composite coatings containing passive ceramic and commercial glasses was investigated. Two compositions (C2c, D2-PP) of double-layer polymer-derived ceramic (PDC) coating systems, composed from bond coat and a top coat, were developed. In order to obtain adherent coatings, stainless steel substrates were cleaned by four different cleaning procedures. The coatings were then deposited onto the steel substrate via spray coating. Pretreatment by subsequent ultrasonic cleaning in acetone, ethanol and deionised water (procedure U) was found to be the most effective, and the resultant C2c and D2-PP coatings, pyrolysed at 850 °C, indicated strong adhesion without delamination or cracks, propagating at the interface steel/bond coat. In the substrate treated by sandblasting and chemical etching, small cracks in the bond coat were observed under the same pyrolysis conditions. After oxidation tests, all coatings, except for those subjected to the U-treated substrates, showed significant cracking in the bond coat. The D2-PP coatings were denser than C2c, indicating better protection of the substrate.
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Algahtani, Ali, Essam Mahmoud, Sohaib Khan, and Vineet Tirth. "Experimental Studies on Corrosion Behavior of Ceramic Surface Coating using Different Deposition Techniques on 6082-T6 Aluminum Alloy." Processes 6, no. 12 (November 26, 2018): 240. http://dx.doi.org/10.3390/pr6120240.
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Aluminum alloys cannot be used in aggressive corrosion environments application. In this paper, three different surface coating technologies were used to coat the 6082-T6 aluminum alloy to increase the corrosion resistance, namely Plasma Electrolytic Oxidation (PEO), Plasma Spray Ceramic (PSC) and Hard Anodizing (HA). The cross-sectional microstructure analysis revealed that HA coating was less uniform compared to other coatings. PEO coating was well adhered to the substrate despite the thinnest layer among all three coatings, while the PSC coating has an additional loose layer between the coat and the substrate. X-ray diffraction (XRD) analysis revealed crystalline alumina phases in PEO and PSC coatings while no phase was detected in HA other than an aluminum element. A series of electrochemistry experiments were used to evaluate the corrosion performances of these three types of coatings. Generally, all three-coated aluminum showed better corrosion performances. PEO coating has no charge transfer under all Inductive Coupled Plasma (ICP) tests, while small amounts of Al3+ were released for both HA and PSC coatings at 80 °C. The PEO coating showed the lowest corrosion current density followed by HA and then PSC coatings. The impedance resistance decreased as the immersion time increased, which indicated that this is due to the degradation and deterioration of the protective coatings. The results indicate that the PEO coating can offer the most effective protection to the aluminum substrate as it has the highest enhancement factor under electrochemistry tests compared to the other two coatings.
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CHEN, CHUANZHONG, QING DONG, and DIANGANG WANG. "MICROSTRUCTURE AND ELEMENT DISTRIBUTIONS OF CERAMIC-LIKE COATINGS ON THE AZ91 ALLOY BY MICRO-ARC OXIDATION." Surface Review and Letters 13, no. 01 (February 2006): 63–68. http://dx.doi.org/10.1142/s0218625x06007846.
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Ceramic-like coatings were deposited on the substrate of the AZ91 alloy by micro-arc oxidation (MAO). Many methods like X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron diffraction spectroscopy (EDS) were used to analyze the structure and composition of the coating. XRD showed that the MAO coating was mainly composed of MgO . The results of SEM showed that the coating surface possessed a porous microstructure and the pore size was in the range of 1–3 μm. EDS indicated that the coating matrix was relatively dense and had a homogeneous thickness. The element silicon from the applied electrolyte could be absorbed into the coating in the MAO process. The hardness of the MgO coatings could reach 513 HV0.025 that was about four times higher than that of the substrate. It is expected that the coatings have a great potential in the surface protection of magnesium alloys.
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Agüero, Alina, Marcos Gutiérrez, and Raúl Muelas. "Steam Oxidation Testing of Coatings for Next Generation Steam Power Plant Components." Materials Science Forum 522-523 (August 2006): 205–12. http://dx.doi.org/10.4028/www.scientific.net/msf.522-523.205.
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To achieve higher power generation efficiency in steam turbines, operating temperatures are expected to rise from 550°C to 650°C. The use of oxidation resistant coatings on currently available materials, with high creep strength but inferior steam oxidation resistance, is being explored in order to accomplish this goal in the context of the European project “Coatings for Supercritical Steam Cycles” (SUPERCOAT). Coating techniques have been chosen on the basis of being potentially appropriate for coating steam turbine components: the application of metallic and ceramic slurries, pack cementation and the deposition of alloyed and cermet materials by thermal spray. The coatings were characterised by metallography, SEM-EDS and XRD and steam oxidation and thermal cycling laboratory testing was carried out at 650º C. In this presentation, the testing results of selected coatings will be shown including those which exhibit the most promising behaviour. For instance, slurry aluminides have been exposed to steam at 650°C for more than 38,000 h (test ongoing) without evidence of substrate attack. Some HVOF coatings such as FeAl, NiCr and FeCr also have shown excellent behaviour. The results have provided information regarding the mechanism of protection and degradation of these coatings as well as insight into new coating development.
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Sebastian, Jobin, Abyson Scaria, and Don George Kurian. "Development & Characterization of Alumina Coating by Atmospheric Plasma Spraying." Applied Mechanics and Materials 877 (February 2018): 104–9. http://dx.doi.org/10.4028/www.scientific.net/amm.877.104.
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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
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Froitzheim, J., and J. E. Svensson. "Nanocoatings for SOFC Interconnects - Mitigating Chromium Volatilization and Improving Corrosion Properties." Materials Science Forum 696 (September 2011): 412–16. http://dx.doi.org/10.4028/www.scientific.net/msf.696.412.
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Two important degradation mechanisms in Solid Oxide Fuel Cells (SOFC) are directly related to the metallic interconnects. The formation of volatile chromium oxides from metallic interconnects commonly causes fast degradation in cell performance due to poisoning the cathode. Secondly is the ability of the metallic interconnect to form a thin protective oxide one of the most important lifetime limiting factors for SOFC. Chromium volatilization of various uncoated steels is studied as a function of temperature by a recently developed denuder technique which allows time resolved quantification of volatile chromium species. The inhibition of Cr evaporation by Co thin film coatings (800nm) is investigated; it will be shown that these coatings are more effective than much thicker ceramic coatings that are commonly used for this purpose. In order to increase the lifetime of the metallic components in SOFC nano-coatings of reactive elements (RE) have been investigated as well. The application of such coatings can reduce the corrosion rates substantially and thus increase the lifetime of the fuel cell stack. It will be shown that it is possible to combine the positive effects of RE with the beneficial effects of a Co coating and thus to obtain an interconnect material with low Cr evaporation and increased oxidation resistance.
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Liu, Peng, Lian Qi Wei, Shu Feng Ye, Xun Zhou, Yu Sheng Xie, and Yun Fa Chen. "Preparation and Property of Ceramic Matrix Coating of Anti-Oxidation for Stainless Steel at High Temperature by Slurry Method." Advanced Materials Research 105-106 (April 2010): 448–50. http://dx.doi.org/10.4028/www.scientific.net/amr.105-106.448.
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In this paper, the new high temperature ceramic matrix coating of anti-oxidation for stainless steel was prepared by slurry method. With the research about oxidation resistance of ceramic matrix coating formed on stainless steel, the effect of initial melting temperature, melting temperature range and thermal expansion coefficients of ceramic sintering change on protective properties of high temperature coating prepared at 1250°C is investigated, and then high temperature sintering ceramic with high-performance is gained through optimization. Through the test of TG-DTA and XRD to the coating, study on high temperature oxidation resistance of ceramic coating and the structure changing of the scale with coating from SEM images and photos, it is shown that the ceramic coating has excellent oxidation resistant properties, the weight loss with coating decrease more than 85%.
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Kyzioł, Lesław, and Aleksandr Komarov. "Influence of Micro-Arc Oxidation Coatings on Stress Corrosion of AlMg6 Alloy." Materials 13, no. 2 (January 12, 2020): 356. http://dx.doi.org/10.3390/ma13020356.
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This paper shows results of a study on the corrosion behavior of micro-arc oxidation (MAO) coatings sampled from the AlMg6 alloy. The alloy was simultaneously subjected to a corrosive environment and static tensile stress. For comparative purposes, the tests were run for both coated samples and samples without coatings. The research was conducted at a properly prepared stand; the samples were placed in a glass container filled with 3.5% NaCl aqueous solution and stretched. Two levels of tensile stress were accepted for the samples: σ1 = 0.8R0.2 σ2 = R0.2, and the tests were run for two time intervals: t1 = 480 h and t2 = 1000 h. Prolonged stress corrosion tests (lasting up to 1000 h) showed that the samples covered with ceramic coatings demonstrated significantly higher corrosion resistance than the samples without the coatings. Protective properties of the coating could be explained by its structure. Surface pores were insignificant, and their depth was very limited. The porosity level of the main coating layer was 1%. Such a structure of coating and its phase composition provided high protective properties.
Dissertations / Theses on the topic "Oxidation protection by thin ceramic coatings"
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OSTROVSKAYA, OXANA. "Oxidation resistance of Ti-Al intermetallic alloys and protection by ceramic coating." Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2705474.
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In recent years, TiAl intermetallic alloys been widely used in aircraft and automotive industry. With the aim of improving the mechanical behavior and the oxidation resistance at high temperature of the TiAl alloys firstly designed, new intermetallic alloys of second and third generation have been successively developed.
In this work, the oxidation resistance in air of four intermetallic alloys of second generation (Ti-48Al-2Cr-2Nb) and third generation ( Ti-48Al-2Nb-0.7Cr-0.3Si, Ti43.5Al-4Nb-1Mo and Ti-47Al-2Cr-8Nb) was investigated by TGA equipment under isothermal conditions in the range of 800-1000 °C. These alloys were cut from the core of bars, previously processed by Electron Beam Melting and successively heat-treated. The composition of the oxide layers was investigated by XRD, SEM-EDS and XPS. Each alloy showed different oxidation behavior at high temperatures. Layer exfoliation or spallation was observed for many samples, but at very different temperatures for the different alloys. When spallation did not happen in a significant extent the oxide layers grew according to a parabolic law. The kinetic rate constants and the activation energies were calculated. These kinetic parameters allowed to assess a rank of oxidation resistance, which can be correlated with the composition of the alloys.
In order to improve the oxidation resistance of Ti-48Al-2Cr-2Nb, ceramic nitride coatings were deposited by a High Power Impulse Magnetron Sputtering (HiPIMS) method. Differently engineered TiAlN and TaAlN protective films were processed and their performances compared. Samples were submitted to thermal cycling under oxidizing atmosphere up to 850° C (40 cycles) and 950°C (100 and 200 cycles), at high heating and cooling rates. For this purpose, a burner rig able to simulate the operating conditions of the different stages of turbine engines was used.
The microstructure and composition of samples before and after oxidation were investigated by several techniques: microscopy (optical and SEM-EDS), X-ray photoelectron spectrometry (XPS) and X-ray diffraction (XRD).
All the TiAlN coatings differently processed provided a remarkable improvement of oxidation resistance. Good adhesion properties were observed even after repeated thermal shocks. HiPIMS pretreatments of the substrate surfaces, performed before the coating deposition, significantly affected the oxidation rate, the oxide layer composition and the coating/substrate adhesion.
The oxide layers formed on the sample surface showed different thickness, depending on the presence of the protective coating and the processing path adopted for its deposition. The nitride coatings appreciably enhanced the oxidation resistance and sustained repeated thermal shocks without showing damage or spallation. Differently TaAlN coating did not improve the oxidation resistance of TiAl substrate.
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Dressler, Martin. "Sol-gel preparation and characterization of corundum based ceramic oxidation protection coatings." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2009. http://nbn-resolving.de/urn:nbn:de:bsz:105-8553447.
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The Ni-base superalloy, IN-718, has been coated with alumina sols. Coated surfaces, carrying alumina layers having thicknesses between 0.6 μm and 3.6 μm show a significantly reduced oxidation rate when compared with uncoated reference surfaces, even if heating temperature is increased up to 900 °C and heating time is extended to 800 h. Alumina layers were prepared via sol-gel processing using a modified Yoldas procedure to obtain alumina sols. No change in rheological sol behavior was observed for more than 1 year of aging under static conditions at room temperature. Depending on pH value, modified Yoldas sols contain a manifold of Al species, among them Al13 polycations. Thermal evolution of sol derived alumina powders depends on Al speciation of parent sols. Depending on sol composition, both gamma-Al2O3 and eta-Al2O3 occur as intermediate transition aluminas. Phase composition and gas phase velocity influence oxygen permeability of thin layers prepared with modified Yoldas sols.
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Oues, Adnan Khalil. "PROTECTION OPTIMIZATION OF CARBON-CARBON COMPOSITES AGAINST AIR OXIDATION BY COATING WITH ANTI-OXIDANTS." OpenSIUC, 2017. https://opensiuc.lib.siu.edu/dissertations/1376.
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AN ABSTRACT OF THE DISSERTATION OF TITLE: (OPTIMIZATION PROTECTION OF CARBOB-CARBON COMPOSITES DISC-BRAKES MATERIAL BY COATING WITH ANTI-OXIDANTS) Developing glass enhancer mixture solutions (Ki’s), which promote the formation of a stable glass layer, homogenous clear liquid solution, and low viscosity liquid form, are easy to apply, and penetrating. They are compatible with ceramic liquid glass based anti-oxidants for treating surfaces of carbon/carbon composites material, and significantly increase the rate of protection against oxidation. Ki’s’ are comprised of mixing chemical compositions at standard temperature and pressure conditions from group one and two such as Na, K, Ca, Mg, etc. of 5 to 25 wt. %, deionized water from 95 to 75 % by weight, and adding up to 1 % by weight of surfactants such as DF-16, DF-20, and CF-10 with specific proportions, and followed by thorough stirring to produce a homogeneous blend of mixture solution. The glass enhancers, which are aqueous mixture solutions, are applied to the surfaces of carbon/carbon (C/C) composites by dipping, brushing, spraying, or other painting application techniques, followed by annealing, or a heat-treating range of 80 to 110 ℃ for a minimum of 8 hours, and allowing cooling time of the coated C/C composites of a minimum of 12 hours to room temperature. Preferential compatibility of the glass enhancer mixture solutions (Ki's) is with liquid glass former's, anti-oxidants comprised mostly of borate and phosphate glasses. The glass enhancer solution mixtures (Ki’s) are supplemental additions to ceramics’ liquid anti-oxidants coatings used for carbon-carbon composites protection against oxidation, and it will increase the rate of protection against oxidation for low, and moderate temperature’s range from 400 to 900 ℃. The glass enhancer Ki’s mixture solutions should be used with liquid glass former's’ anti-oxidants, such as SiO₂, GeO₂, B₂O₃, and P₂O₅. A series of glass enhancer’s Ki’s, heat treatment cycle (char-cycle) ranged between 700 to 900 ℃, and application methods, were developed and tested experimentally. Two arbitrary isothermal temperatures of 650 ℃, and 871 ℃ were selected for thermal oxidation testing, and a temperature of 650 ℃ was selected, and tested against catalytic thermal oxidation. Additions of glass enhancer Ki’s improved protection of C/C composites disc-brakes against oxidation by double, and triple amount of time in hours versus the use of anti-oxidant coatings alone.
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Dressler, Martin. "Sol-gel preparation and characterization of corundum based ceramic oxidation protection coatings." Doctoral thesis, 2006. https://tubaf.qucosa.de/id/qucosa%3A22583.
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The Ni-base superalloy, IN-718, has been coated with alumina sols. Coated surfaces, carrying alumina layers having thicknesses between 0.6 μm and 3.6 μm show a significantly reduced oxidation rate when compared with uncoated reference surfaces, even if heating temperature is increased up to 900 °C and heating time is extended to 800 h. Alumina layers were prepared via sol-gel processing using a modified Yoldas procedure to obtain alumina sols. No change in rheological sol behavior was observed for more than 1 year of aging under static conditions at room temperature. Depending on pH value, modified Yoldas sols contain a manifold of Al species, among them Al13 polycations. Thermal evolution of sol derived alumina powders depends on Al speciation of parent sols. Depending on sol composition, both gamma-Al2O3 and eta-Al2O3 occur as intermediate transition aluminas. Phase composition and gas phase velocity influence oxygen permeability of thin layers prepared with modified Yoldas sols.
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Dressler, Martin [Verfasser]. "Sol-gel preparation and characterization of corundum based ceramic oxidation protection coatings / Martin Dressler." 2006. http://d-nb.info/986095559/34.
Full textBooks on the topic "Oxidation protection by thin ceramic coatings"
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Mitchell, D. R. G. The effect of thin, hard ceramic coatings on the friction, wear and oxidation behaviour of type 321 stainlesssteel in carbon dioxide environments. Manchester: UMIST, 1989.
Find full textBook chapters on the topic "Oxidation protection by thin ceramic coatings"
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Rebstock, K., D. Hertel, and W. D. Vogel. "Reliability of Oxidation Protection Systems for Ceramic Matrix Composites." In Protective Coatings and Thin Films, 511–22. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5644-8_41.
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Musil, J. "Hard Nanocomposite Coatings: Thermal Stability, Protection of Substrate against Oxidation, Toughness and Resistance to Cracking." In Advanced Ceramic Coatings and Materials for Extreme Environments III, 55–65. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118807651.ch6.
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Baufeld, Bernd, and Omer van der Biest. "Development of Thin Ceramic Coatings for the Protection against Temperature and Stress Induced Rumpling of the Metal Surface of Turbine Blades." In Key Engineering Materials, 273–76. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-424-3.273.
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Sonber, J. K., T. S. R. Ch. Murthy, C. Subramanian, R. C. Hubli, and A. K. Suri. "Processing Methods for Ultra High Temperature Ceramics." In MAX Phases and Ultra-High Temperature Ceramics for Extreme Environments, 180–202. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-4066-5.ch006.
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Ultra-high-temperature ceramics (UHTCs) are a group of materials that can withstand ultra high temperatures (1600-3000 oC) which will be encountered by future hypersonic re-entry vehicles. Future re-entry vehicles will have sharp edges to improve flight performance. The sharp leading edges result in higher surface temperature than that of the actual blunt edged vehicles that could not be withstood by the conventional thermal protection system materials. To withstand the intense heat generated when these vehicles dip in and out of the upper atmosphere, UHTC materials are needed. UHTC materials are composed of borides of early transition metals. From the larger list of borides, ZrB2 and HfB2 have received the most attention as potential candidates for leading edge materials because their oxidation resistance is superior to that of other borides due to the stability of the ZrO2 and HfO2 scales that form on these materials at elevated temperatures in oxidizing environments. Processing of these materials is very difficult as these materials are very refractory in nature. In this chapter, processes available for powder synthesis, fabrication of dense bodies, and coating processes is discussed.
Conference papers on the topic "Oxidation protection by thin ceramic coatings"
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Bobzin, K., T. Schläfer, T. Warda, and M. Brühl. "Thermally Sprayed Oxidation Protection Coatings for γ-TiAl Substrates." In ITSC2010, edited by B. R. Marple, A. Agarwal, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima, and G. Montavon. DVS Media GmbH, 2010. http://dx.doi.org/10.31399/asm.cp.itsc2010p0060.
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Abstract Due to excellent mechanical properties and low density compared to super alloys (e.g. Ni-based alloys) Titanium Aluminide is often used as base material in the aerospace industry. But the thermodynamic conditions within turbines limit the capabilities of the material. At the moment γ-TiAl is used for parts, which have to withstand temperatures up to 700 °C. Above this temperature oxidation kinetics cause a thick oxide layer consisting of several oxides, which tend to fast chipping. Therefore the surface of the γ-TiAl is being destroyed and the material loses its excellent mechanical properties. To enable the use of this material at higher temperatures, the development of an oxidation protection coating is necessary. Several coating techniques e.g. EB-PVD were tried in the last years, but the oxidation behaviour of the γ-TiAl could not be significantly improved. Protective thermal spray coatings so far seem to be a promising technology in order to protect γ-TiAl components against oxidation. Therefore this technique was used within this work, which aims for the development of new oxidation protection coatings. A multilayer system was developed. The multilayer consists of a ceramic ZrO2-7Y2O3 coating with a NiCoCrAlY top coat. In this case the ceramic coating avoids the diffusion of Ti or Al of the γ-TiAl into the MCrAlY coating or the other way around. The NiCoCrAlY coating improved the oxidation behaviour of the Titanium Aluminide by building a dense oxide layer on top of the multilayer. The paper will give an overview about the results of the oxidation tests with the new developed multilayer concept for protection of the γ-TiAl against oxidation.
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Tului, M., S. Lionetti, G. Marino, R. Gardi, T. Valente, and G. Pulci. "Ultra-High Temperature Resistance Coatings for Thermal Protection of Space Vehicles." In ITSC2009, edited by B. R. Marple, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima, and G. Montavon. ASM International, 2009. http://dx.doi.org/10.31399/asm.cp.itsc2009p0634.
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Abstract In this study, plasma sprayed ceramic coatings with different amounts of SiC and MoSi2 particles dispersed in a ZrB2 matrix were produced and tested. The results show that MoSi2 addition in ZrB2-SiC samples improves high-temperature oxidation resistance without affecting mechanical properties. Demonstrative components were manufactured and tested in simulated operating conditions by means of a plasma wind tunnel. Preliminary results indicate that thermal sprayed ceramics are well suited for use in space re-entry vehicles.
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Thornton, John, Darren Dale, Matthew Zonneveldt, Chris Wood, and Jon Almer. "Strain and Phase Mapping of Ceramic Matrix Composites and Protective Coatings." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26281.
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Coatings are frequently required to provide oxidation protection for high temperature materials. Silicon carbide (SiC) coatings have been used to protect carbon-carbon composites on leading edges and zirconia coatings are used as thermal barriers on gas turbine aerofoils. The effectiveness and durability of these coatings is dependent on the residual strains created in these coatings during their formation or deposition and also during service. Tensile strains in the plane of the coating can lead to through thickness cracks that expose the substrate, while compressive strains can cause the coating to delaminate. This paper presents strain measurements of these high temperature material systems obtained with high energy X-ray diffraction. The diffraction also provided useful information on phase, crystallite size and texture as a function of depth. Tensile strains were found in the SiC coatings, and compressive strains were found in the zirconia coatings. Both these strains were parallel to their coatings’ surfaces. The differences in thermal expansion coefficients between the coatings and their substrates can account for both the compressive strain in the zirconia and the tensile strain in the SiC.
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Bobzin, K., T. Schläfer, T. Warda, M. Brühl, and T. F. Linke. "Improving Long Term Oxidation Protection for γ-TiAl Substrates." In ITSC2011, edited by B. R. Marple, A. Agarwal, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima, and A. McDonald. DVS Media GmbH, 2011. http://dx.doi.org/10.31399/asm.cp.itsc2011p0010.
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Abstract In previous work, a thermal spray multilayer system consisting of ZrO2 and an MCrAlY top coat showed promising results regarding oxidation behavior of the γ-TiAl substrates tested, which encouraged further research activities. Diffusion of substrate material was successfully inhibited by a ceramic ZrO2 coating. A building up of a dense and stable oxide layer could be achieved by additional application of an MCrAlY top coat, leading to improved oxidation resistance and thus showing feasibility. In this work the main focus for development was put on enhancing adhesion and lowering residual stresses of the coatings in order to allow long term and cyclic testing without delamination taking place. Being a very brittle material, Gamma Titanium Aluminides require special surface treatment to enable roughening which is crucial for a strong mechanical bond between substrate and coating. Alternatives to conventional grit blasting as a standard preparation method were investigated. These were micro-abrasive blasting and blasting at elevated temperature (≈300-550 °C) to allow a more ductile behavior. The paper will highlight the implications by means of these measures and will also show the present development status of the multilayer system.
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Rusowicz, Artur. "The Plasma Spraying of Nitride Coatings." In ASME 2002 Engineering Technology Conference on Energy. ASMEDC, 2002. http://dx.doi.org/10.1115/etce2002/cmda-29085.
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Ceramics without oxides (i.e. nitrides) are vulnerable to oxidation in the presence of plasmagenic gases or oxygen from atmosphere during plasma spraying. Initially there were two ways of oxidation’s avoidance: first, modification of powder material and second, limitation of an oxygen’s stream flowing into plasma. The modification of the powder material consisted in covering of ceramic granules with material limiting contact with oxygen or usage of easily oxidizing material getting oxygen away (i.e. a graphite thin layer over carbide’s granule). This method seemed to be less economic due to additional increase in powder’s price. Eventually the second conception of limiting of oxidation was considered as worth developing. Originally the process of spraying was carried out in vacuum (VPS – Vacuum Plasma Spraying). Then application of atmosphere under control was examined (CAPS – Controlled Atmosphere Plasma Spraying). It includes process of spraying with application of different gaseous controlled atmospheres under different pressure (decreased, normal and increased). There are three kinds of atmosphere: neutral (argon, nitrogen), reductive (carbon monoxide, methane) and acting with spraying material. Eventually the process was carried out under atmospheric pressure with gaseous ring-shaped protective gas jet. Moreover the experiments with spraying of nitrides were described (AlN, TiN, Si3N4). The most suitable characteristics of the process was chosen and some properties of coatings were examined as well.
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Tului, M., B. Giambi, G. Pulci, and T. Valente. "Silicon Carbide Based Plasma Sprayed Coatings." In ITSC2011, edited by B. R. Marple, A. Agarwal, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima, and A. McDonald. DVS Media GmbH, 2011. http://dx.doi.org/10.31399/asm.cp.itsc2011p0823.
Full textAbstract:
Abstract Coatings containing up to 65 volume % of silicon carbide were deposited by plasma spray. Potential applications can be found in the protection of CMC (Ceramic Matrix Composite) against wear and high temperature oxidation. It is well known that SiC can not be deposited by thermal spray because it decomposes before melting. To face this problem, a mixture of SiC and ZrB2 was deposited, since those two compounds form an eutectic phase, at a temperature lower to the one of SiC decomposition. Coatings microstructure was characterised by XRD, SEM, and EDS, confirming the presence of SiC in the deposited layer and the formation of the eutectic phase during spraying. Samples of the coatings were exposed in air at high temperature, in the range between 1373 and 1873 K. The oxide scale was investigated by means of SEM and EDS. It was constituted by a SiO2 layer, which includes islands of ZrO2. Test results showed the good potentiality of the material investigated to be used as a protection against the high temperature oxidation.
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Mifune, N., Y. Harada, T. Doi, and R. Yamasaki. "Hot Corrosion Behavior of Graded Thermal Barrier Coatings Formed by Plasma Spraying Process." In ITSC2003, edited by Basil R. Marple and Christian Moreau. ASM International, 2003. http://dx.doi.org/10.31399/asm.cp.itsc2003p1525.
Full textAbstract:
Abstract Hot corrosion behavior of Thermal Barrier Coatings (TBCs) has been studied by comparison between double layer coatings and graded coatings. Two types of oxide ceramics, 8 mass % Y2O3-ZrO2(8YZ) and 2CaOSiO2-15mass% CaOZrO2 (C2S-15 CZ), with a bond coating of NiCrAlY were applied to metallic substrates in this study. After a hot corrosion test by V2O5-Na2SO4 corrosive ashes, hot corrosion behavior of TBC has been investigated by visual inspection, metallography, X-ray diffraction and EPMA. The C2S-15%CZ coating reacted with V2O5 only where it was in direct contact with the material. The affected area from the reaction was limited to the coating surface where V2O5 existed. The coating showed adequate hot corrosion-resistance. It was found on the 8YZ coating that Y2O3, the stabilizing component, particularly reacts with V2O5 and loses its function; this led to partial spalling of the coating. It was observed that the durability of the double layer TBC was largely influenced by the performance of a corrosion resistant NiCrAlY undercoat which provided protection against corrosive components penetrating through the ceramic topcoat. It was observed that the graded coating degraded due to oxidation of NiCrAlY particles which independently existed near the coating surface and affected the durability of TBC.
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Rodriguez Diaz, M., M. Szafarska, M. Nicolaus, K. Möhwald, and H. J. Maier. "Potentials of Thermal Spraying Processes in Silane-Doped Inert Gases." In ITSC2022. DVS Media GmbH, 2022. http://dx.doi.org/10.31399/asm.cp.itsc2022p0199.
Full textAbstract:
Abstract In addition to the proper functional properties, the adhesive strength represents one of the key criteria for industrial use of thermally sprayed coatings. Since conventional thermal spraying processes are almost carried out exclusively in air atmosphere, this leads to the oxidation of the particles and of interfaces within the coatings. As a result, conventional thermally sprayed metallic and metal-ceramic coatings are characterized by heterogeneous microstructures with interlamellar oxide fringes at the interfaces between individual splats and also between the coating and the substrate. This has a decisive influence on the bond strength and on the wear and corrosion protection properties of thermally sprayed coatings. The aim of this study is to present the potentials of thermal spraying processes carried out in a mixture of monosiliane and an inert gas at ambient pressure as an alternative to the known vacuum spraying process in order to prevent oxidation during the coating process. Using the example of arcsprayed coatings, it is demonstrated that the extremely low oxygen partial pressure in the silane-doped medium leads to coatings free of oxide seams with a reduced porosity and substantially enhanced properties.
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Mumm, Daniel R., and Anthony G. Evans. "Mechanisms Controlling the Performance and Durability of Thermal Barrier Coatings." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2684.
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Abstract Thermal protection systems based on ceramic thermal barrier coatings (TBCs) are used extensively to protect hot-section components in gas turbine engines. They comprise thermally insulating ceramic coatings, deposited on an aluminum-containing intermetallic bond coat (BC) that provides oxidation protection. A thin thermally-grown oxide (TGO layer forms between the TBC and BC during cyclic thermal exposure. Each of the system constituents evolves in service and all interact during thermal cycling to control the thermo-mechanical performance of the system. Exposed to thermal cycling conditions, TBC systems are susceptible to loss of adhesion and spalling failures. Multiple failure mechanisms exist, dependent upon differing thermal histoiy and processing approach for various coating systems. Coating failure is ultimately controlled by the large residual compression in the TGO and its role in amplifying the effects of imperfections in the vicinity of the TGO. The failure occurs through a process involving crack nucleation, propagation and coalescence events. For a particular commercial system, it is found that the TGO ‘ratchets’ into the bond coat with each thermal cycle, at an array of interfacial sites. The displacements induce strains in the superposed TBC that cause it to crack. The cracks extend laterally as the TGO ratcheting process proceeds, until the cracks from neighboring sites coalesce. Once this happens, the system fails by large scale buckling. It is shown that the displacements are ‘vectored’ by a lateral component of the growth strain in the TGO. The relative roles of bond coat visco-plasticity, initial interface morphology, and phase evolution are discuss. The behavior observed for this system is compared with predictions of a ratcheting model, as well as with the behavior observed for other commercial coating systems.
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Alvin, M. A., I. Anderson, A. Heidloff, E. White, R. Bhatt, J. Grady, B. McMordie, and B. Warnes. "Development of Advanced Material Systems for Future Gas Turbine Applications." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43456.
Full textAbstract:
Advanced coating systems in conjunction with novel internal airfoil cooling configurations continue to be a critical research focus to provide enhanced oxidation protection and cooling of commercial metal alloys as future land-based gas turbines are being designed for inlet gas temperature operations of >1300–1400°C. With the application of densified oxide dispersion strengthened (ODS) coatings on cast near surface embedded micro-channel (NSEMC) airfoil surfaces, improvements of >50–70% in heat removal capabilities are projected over that of conventional, smooth-channeled, internally-cooled, airfoil configurations. For turbine inlet and airfoil surface design temperatures exceeding 1400–1600°C, oxide-coated, silicon carbide-based ceramic matric composites (CMCs) have been developed. In this paper we will review our recent advancements that have been made with respect to ODS coating development and the oxidation stability of CMCs during bench-scale laboratory testing.