Download or read book Oxidation Studies of a MCrAlY Bond Coat in a Plasma Sprayed TBC System written by Edward A. G. Shillington and published by . This book was released on 1998 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oxidation behaviour of MCrAlX coatings written by Pimin Zhang and published by Linköping University Electronic Press. This book was released on 2018-02-12 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: MCrAlY coatings (M=Ni and/or Co) have been widely used for the protection of superalloy components against oxidation and hot corrosion in the hot sections of gas turbines. The drive to improve engine combustion efficiency while reducing emissions by increasing the operation temperature brings a big challenge for coating design. As a result, the need for improvement of MCrAlY coatings for better oxidation resistance is essential. Formation of a stable, dense, continuous, and slow-growing ?-Al2O3 layer, on the MCrAlY coating surface, is the key to oxidation protection, since the protective ?-Al2O3 scale offers superior oxidation resistance due to its lower oxygen-diffusion rate as compared with other oxides. The ability of a MCrAlY coating to form and maintain such a protective scale depends on the coating composition and microstructure, and can be improved through optimization of deposition parameters, modification of coating surface conditions, and so on. Part of this thesis work focuses on studying the effect of post-deposition surface treatments on the oxidation behavior of MCrAlX coatings (X can be yttrium and/or other minor alloying elements). The aim is to gain fundamental understanding of alumina scale evolution during oxidation which is important for achieving improved oxidation resistance of MCrAlX coatings. Oxide scale formed on coatings at initial oxidation stage and the effect of surface treatment were investigated by a multi-approach study combining photo-stimulated luminescence, microstructural observation and weight gain. Results showed that both mechanically polished and shot-peened coatings exhibited superior performance due to rapid formation of ?-Al2O3 fully covering the coating and suppressing growth of transient alumina, assisted by the high density of ?-Al2O3 nuclei on surface treatment induced defects. The early development of a two-layer alumina scale, consisting of an inward-grown inner ?-Al2O3 layer and an outer layer transformed from outward-grown transient alumina, resulted in a higher oxide growth rate of the as-sprayed coating. The positive effect of the surface treatments on retarding oxide scale growth and suppressing formation of spinel was also observed in oxidation test up to 1000 hrs. As the oxidation proceeds to the close-to-end stage, a reliable criterion to estimate the capability of coating to form ?-Al2O3 is of great importance to accurately evaluate coating lifetime, which is the aim of the other part of the thesis work. Survey of published results on a number of binary Ni-Al and ternary Ni-Cr-Al, Ni-Al-Si systems shows that the empirical Al-concentration based criterion is inadequate to properly predict the formation of a continuous ?-Al2O3 scale. On the other hand, correlating the corresponding Al-activity data, calculated from measured chemical compositions using the Thermo-Calc software, to the experimental oxidation results has revealed a temperature dependent, critical Al-activity value for forming continuous ?-Al2O3 scale. To validate the criterion, long-term oxidation tests were performed on five MCrAlX coatings with varying compositions and the implementation of the Al-activity based criterion on these coatings successfully predicted ?-Al2O3 formation, showing a good agreement with experiment results.
Download or read book Oxidation Studies of Air Plasma Sprayed Bond Coats for Thermal Barrier Coatings written by C. Ceccato and published by . This book was released on 2006 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Isothermal and Cyclic Oxidation of an Air Plasma sprayed Thermal Barrier Coating System written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermogravimetric methods for evaluating bond coat oxidation in plasma-sprayed thermal barrier coating (TBC) systems were assessed by high-temperature testing of TBC systems with air plasma-sprayed (APS) Ni-22Cr-10Al-1Y bond coatings and yttria-stabilized zirconia top coatings. High-mass thermogravimetric analysis (at 1150[sup degrees]C) was used to measure bond coat oxidation kinetics. Furnace cycling was used to evaluate APS TBC durability. This paper describes the experimental methods and relative oxidation kinetics of the various specimen types. Characterization of the APS TBCs and their reaction products is discussed.
Download or read book Superalloys written by Matthew J. Donachie and published by ASM International. This book was released on 2002 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers virtually all technical aspects related to the selection, processing, use, and analysis of superalloys. The text of this new second edition has been completely revised and expanded with many new figures and tables added. In developing this new edition, the focus has been on providing comprehensive and practical coverage of superalloys technology. Some highlights include the most complete and up-to-date presentation available on alloy melting. Coverage of alloy selection provides many tips and guidelines that the reader can use in identifying an appropriate alloy for a specific application. The relation of properties and microstructure is covered in more detail than in previous books.
Download or read book Performance of MCrAlX coatings written by Pimin Zhang and published by Linköping University Electronic Press. This book was released on 2019-11-04 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: MCrAlY coatings (M=Ni and/or Co) are widely used for the protection of superalloy components against oxidation and hot corrosion in the hot sections of gas turbines. The drive for coating systems to bestow adequate oxidation and corrosion resistance upon the components becomes urgent as an inevitable result of the necessary improvement in engine combustion efficiency and service lifetime. Through the careful design of the composition, MCrAlY coating performance can be optimized to meet the needs under different service conditions and component materials, therefore, “MCrAlX”, with “X” stands for the minor alloying elements, is used to highlight the effect. In the present thesis, the performance of new MCrAlX coatings is investigated with respect to oxidation, hot corrosion and interactions between coating-superalloy substrates. Oxidation of MCrAlX coatings can be generally categorized into initial, steady and close-to-end stages. Coating performance can be affected by various factors at different stages, therefore, experiments were designed by targeting the oxidation stages. Investigation on the initial stage oxidation behavior of MCrAlY coatings with post-deposition surface treatments reveals the different growth mechanisms of alumina scales. Surface treatments significantly reduce the alumina growth rate by suppressing transient alumina development and aiding the early formation of ?-Al2O3, which improves the long-term oxidation performance of the coating. Similarly, the modification of minor alloy elements in MCrAlX coatings also serves the purpose. The oxidation behavior of new MCrAlX coatings was investigated at the steady oxidation stage, followed by the microstructure observation, thermodynamic and kinetic simulations. As an alternative reactive element addition of Y, Ce shows a negative effect on the formation of columnar alumina scales of high strain tolerance. In comparison, Fe or Ru addition shows no influence on alumina growth, rather than strengthening the phase stability in the coating and reducing the interdiffusion between coating-substrate through different mechanisms. As the oxidation proceeds to the close-to-end stage, a reliable criterion to estimate the capability of coating to form ?-Al2O3 is of great importance to accurately evaluate coating lifetime. A temperature-dependent critical Al-activity criterion was proposed to better predict the formation of a continuous ?-Al2O3 scale based on correction of elemental activity using thermodynamic database to replace the empirical Al-concentration based criterion. Severe interdiffusion occurs between coating-substrate during high temperature oxidation, accelerating the degradation of the system. Interdiffusion behavior of diffusion couples of superalloys-MCrAlX coatings were examined. It is highlighted that the recrystallization of superficial layer of the substrate contributes to the secondary reaction zone formation and element interdiffusion controls subsequent zone thickening. Study on Type I hot corrosion behavior of new MCrAlX coatings shows that the addition of Fe has no influence on basic fluxing reactions before severe Al depletion from the coating occurs. Instead, it boosts the “effective” Al supply of coating by shifting the equilibrium concentration of Al in the ? phase to a low Al level. Besides, the pre-mature coating degradation at the coating-substrate interface was due to the fast growth of corrosion products from substrate induced large local volume expansions, resulting in early coating spallation. MCrAlY ytbeläggningar (M=Ni och/eller Co) används ofta för att skydda komponenter tillverkade av superlegeringar mot oxidation samt högtemperaturskorrosion i de heta gasturbindelarna. Förbättrad förbränningseffektivitet och livslängd hos gasturbiner, gör att ytbeläggningssystemen måste besitta adekvata oxidations- och korrosionsmotstånd. Genom att omsorgsfullt utforma den kemiska sammansättningen hos MCrAlY ytbeläggningar kan deras prestanda optimeras för att möta kraven från olika driftförhållanden samt olika substratmaterial, därför används beteckningen "MCrAlX" för att belysa förändringar av den kemiska kompositionen, där "X" står för reaktiva legeringsämnen som tillsätts i mindre mängder. I denna avhandling undersöks prestandan hos en ny MCrAlX ytbeläggning med hänsyn till oxidation, högtemperaturskorrosion och interaktionen mellan ytbeläggningen och superlegeringssubstratet. Oxidation av MCrAlX ytbeläggningar kan generellt kategoriseras i tre faser; initiala, stabila och nära-slutet fasen. Ytbeläggningens prestanda kan påverkas av olika faktorer vid de olika faserna, därför utformades olika experiment för att undersöka de olika oxidationsfaserna. Undersökningen av den initiala fasen av oxidationsbeteendet hos MCrAlX ytbeläggningar som genomgått ytbehandlingar efter ytbeläggningsdeponeringen avslöjade olika tillväxtmekanismer hos aluminiumoxidskikten. Aluminiumoxidens tillväxthastighet reducerades signifikant av ytbehandlingarna, detta genom att undertrycka utvecklingen av övergående aluminiumoxid och bistå den tidiga tillväxten av ?-Al2O3, vilket förbättrar ytbeläggningens oxidationsprestanda långsiktigt. De reaktiva legeringsämnena som tillsätts i mindre mänger påverkar ytbeläggningens oxidationsprestanda på liknande sätt. Oxidationsbeteendet hos de nya MCrAlX ytbeläggningarna i den stabila fasen följdes av mikrostrukturundersökning, termodynamiska och kinetiska simuleringar. Det framkom att Ce visar en negativ effekt på bildandet av kolumnära aluminiumoxidskikt med hög töjningstolerans som alternativt reaktivt legeringsämne till Y. Jämförelsevis ger Fe- eller Ru-tillsatser ingen påverkan på aluminiumoxidtillväxten, förutom att det förstärker fasstabiliteten i ytbeläggningen samt genom olika mekanismer reducerar interdiffusionen mellan ytbeläggningen och substratet. När oxidationsprocessen kommit till nära-slutet fasen, är det viktigt att uppskatta kapaciteten hos en ytbeläggning att bilda ?-Al2O3, detta då det är ett tillförlitligt kriterium för att noggrant kunna utvärdera ytbeläggningens livslängd. Därför föreslogs ett temperaturberoende kriterium för kritisk Al-aktivitet för att bättre kunna förutsäga bildandet av ett kontinuerligt ?-Al2O3-skikt. Kriteriet baserades på korrigering av legeringsämnens aktivitet genom att använda en termodynamisk databas, detta för att ersätta det empiriska Al-koncentrations baserade kriteriet. Vid högtemperatursoxidation sker en omfattande interdiffusion mellan ytbeläggningen och substratet, vilket accelererar degraderingen av ytbeläggningssystemet. Därför har interdiffusionsbeteendet mellan superlegeringssubstratet och MCrAlX ytbeläggningen undersökts i denna avhandling. Det framkom att rekristallisationen av ytliga skikt av substratet bidrar till formationen av den sekundära reaktionszonen och att interdiffusion kontrollerar zonens efterföljande tjocklektillväxt. Undersökningen av Typ I högtemperaturskorrosionsbeteendet hos en ny MCrAlX ytbeläggning visar att legeringstillägg av Fe inte påverkar de grundläggande flödesreaktionerna innan en kritisk Al utarmning sker i ytbeläggningen. Istället stimulerar det tillförseln av Al genom att skifta jämviktskoncentrationen av Al i ? fasen till en låg nivå av Al. Det framkom också att den tidiga degraderingen av ytbeläggningen vid gränsskiktet mellan ytbeläggningen och substratet kommer av att den snabba tillväxten av korrosionsprodukter från substratet inducerade en stor lokal volymsutvidgning, vilket ledde till tidig ytbeläggningsspallation.
Download or read book Evaluation of Oxidation Damage in Thermal Barrier Coating Systems written by and published by . This book was released on 1996 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Coatings for High Temperature Structural Materials written by National Research Council and published by National Academies Press. This book was released on 1996-05-13 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book assesses the state of the art of coatings materials and processes for gas-turbine blades and vanes, determines potential applications of coatings in high-temperature environments, identifies needs for improved coatings in terms of performance enhancements, design considerations, and fabrication processes, assesses durability of advanced coating systems in expected service environments, and discusses the required inspection, repair, and maintenance methods. The promising areas for research and development of materials and processes for improved coating systems and the approaches to increased coating standardization are identified, with an emphasis on materials and processes with the potential for improved performance, quality, reproducibility, or manufacturing cost reduction.
Download or read book Thermal Spray 2007 Global Coating Solutions Proceedings of the 2007 International Thermal Spray Conference written by Edited by Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, Ghislain Montavon and published by ASM International. This book was released on with total page 1246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermal Barrier Coatings written by Hongbo Guo and published by Woodhead Publishing. This book was released on 2023-01-18 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal Barrier Coatings, Second Edition plays a critical role in counteracting the effects of corrosion and degradation of exposed materials in high-temperature environments such as gas turbine and aero-engines. This updated edition reviews recent advances in the processing and performance of thermal barrier coatings, as well as their failure mechanisms. Novel technologies for the manufacturing of thermal barrier coatings (TBCs) such as plasma spray-physical vapor deposition and suspension plasma spray, are covered, as well as severe degradation of TBCs caused by CMAS attack. In addition to discussions of new materials and technologies, an outlook about next generation TBCs, including T/EBCs is discussed.This edition will provide the fundamental science and engineering of thermal barrier coatings for researchers in the field of TBCs, as well as students looking for a tutorial. Includes coverage of emerging materials, such as rare-earth doped ceramics Presents the latest on plasma spray-physical vapor deposition and suspension (solution precursor) Discusses the degradation of TBCs caused by CMAS attack and its protection Looks at thermally environmental barrier coatings, interdiffusion and diffusion barrier
Download or read book High Temperature Corrosion written by Per Kofstad and published by Elsevier Science & Technology. This book was released on 1988 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Temperature Coatings written by Sudhangshu Bose and published by Butterworth-Heinemann. This book was released on 2017-11-27 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: High Temperature Coatings, Second Edition, demonstrates how to counteract the thermal effects of rapid corrosion and degradation of exposed materials and equipment that can occur under high operating temperatures. This is the first true practical guide on the use of thermally protective coatings for high-temperature applications, including the latest developments in materials used for protective coatings. It covers the make-up and behavior of such materials under thermal stress and the methods used for applying them to specific types of substrates, as well as invaluable advice on inspection and repair of existing thermal coatings. With his long experience in the aerospace gas turbine industry, the author has compiled the very latest in coating materials and coating technologies, as well as hard-to-find guidance on maintaining and repairing thermal coatings, including appropriate inspection protocols. The book is supplemented with the latest reference information and additional support to help readers find more application- and industry-type coatings specifications and uses. Offers an overview of the underlying fundamental concepts of thermally-protective coatings, including thermodynamics, energy kinetics, crystallography and equilibrium phases Covers essential chemistry and physics of underlying substrates, including steels, nickel-iron alloys, nickel-cobalt alloys and titanium alloys Provides detailed guidance on a wide variety of coating types, including those used against high temperature corrosion and oxidative degradation and thermal barrier coatings
Download or read book Influence of Material and Testing Parameters on the Lifetime of TBC Systems with MCrAlY and NiPtAl Bondcoats written by Peng Song and published by Forschungszentrum Jülich. This book was released on 2012 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermal Barrier Coatings Failure Theory and Evaluation Technology written by Yichun Zhou and published by Springer Nature. This book was released on 2022-10-08 with total page 943 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights the failure theories and evaluation techniques of thermal barrier coatings, covering the thermal-mechanical–chemical coupling theories, performance and damage characterization techniques, and related evaluations. Thermal barrier coatings are the key thermal protection materials for high-temperature components in advanced aeroengines. Coating spallation is a major technical bottleneck faced by researchers. The extremely complex microstructure, diverse service environments, and failure behaviors bring challenges to the spallation analysis in terms of the selective use of mechanical theories, experimental methods, and testing platforms. In the book, the authors provide a systematic summary of the latest research and technological advances and present their insights and findings in the past couple of decades. This book is not only suitable for researchers and engineers in thermal barrier coatings and related fields but also a good reference for upper-undergraduate and postgraduate students of materials science and mechanics majors.
Download or read book Mechanical Alloying And Milling written by Cury Suryanarayana and published by CRC Press. This book was released on 2004-09-28 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book surveys the broad field of mechanical alloying from a scientific and technological perspective to form a timely and comprehensive resource valuable to both students and researchers. The treatment progresses from the historical background through a description of the process, the different metastable effects produced, and the mechanisms of
Download or read book Effects of Internal Oxidation on Thermo mechanical Properties of Atmospheric Plasma Sprayed CoNiCrAlY Coatings written by Travis Jay Patterson and published by . This book was released on 2008 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal barrier coatings (TBC) with MCrAlY (M=Co and/or Ni) bond coats have been widely used in hot sections of gas turbines to protect underlying superalloys from high temperatures, oxidation, and hot corrosion. Deposition of MCrAlY bond coats using atmospheric plasma spray (APS), as oppose to conventionally employed vacuum/low-pressure plasma spray and high velocity oxy-fuel deposition, allows greater flexibility in ability to coat economically and rapidly for parts with complex geometry including internal surfaces. There were three objectives of this study. First, relationships between APS spray parameters and coating microstructure was examined to determine optimum spray parameters to deposit APS CoNiCrAlY bond coats. Second, free-standing APS CoNiCrAlY coatings were isothermally oxidized at 1124°C for various periods to examine the evolving microstructure of internal oxidation. Third, as a function of time of isothermal oxidation (i.e., internal oxidation), thermal conductivity and coefficient of thermal expansion were measured for free-standing APS CoNiCrAlY bond coats. Thirteen CoNiCrAlY coatings were deposited on steel substrates by APS using the F4-MB plasma torch. APS CoNiCrAlY bond coats were produced by incremental variation in the flow rate of primary (argon) gas from 85 to 165 SCFH and the flow rate of secondary (hydrogen) gas from 9 to 29 SCFH. Optimum coating microstructure was produced by simultaneously increasing the flow rate of both primary and secondary gas, so that the particle temperature is high enough for sufficient melting and the particle velocity is rapid enough for minimum in-flight oxidation. Optimum spray parameters found in this study were employed to deposit free-standing APS CoNiCrAlY coatings that were isothermally oxidized at 1124°C for 1, 6, 50,100, and 300 hours. Extent of internal oxidation was examined by scanning electron microscopy and image analysis. Internal oxidation occurred by a thickening of oxide scales segregated at the splat boundaries oriented parallel to the coating surfaces. Thermal conductivity and coefficient of thermal expansion (CTE) of the free-standing APS CoNiCrAlY coatings were measured as a function of internal oxidation (i.e., time of oxidation or extent of internal oxidation). Thermal conductivity of free-standing APS CoNiCrAlY was found to decrease with increasing internal oxidation from 28 to 25 W/m-K. This decrease is due to an increase in the amount of internal oxides with lower thermal conductivity (e.g., Al2O3). CTE of free-standing APS CoNiCrAlY, measured in temperature range of 100°~500°C, was also found to decrease with increasing internal oxidation. Internal oxides have lower CTE than metallic CoNiCrAlY coatings. These evolving properties of APS CoNiCrAlY should be beneficial to the overall performance of TBCs in gas turbine applications.
Download or read book Paul Anderboubr written by and published by . This book was released on 1961 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
