引用本文:吴杨,郭星晔,贺定勇.航空发动机热障涂层的CMAS腐蚀与防护研究进展*[J].中国表面工程,2023,36(5):1~13
WU Yang,GUO Xingye,HE Dingyong.Research Progress of CMAS Corrosion and Protection Method for Thermal Barrier Coatings in Aero-engines[J].China Surface Engineering,2023,36(5):1~13
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航空发动机热障涂层的CMAS腐蚀与防护研究进展*
吴杨, 郭星晔, 贺定勇
北京工业大学材料与制造学部 北京 100124
摘要:
热障涂层(TBCs)广泛应用于先进航空发动机热端部件,可以有效提高发动机的工作效率和服役温度。随着发动机涡轮前进口温度不断提高以及工业生产和人类活动愈加频繁,TBCs 面临严峻的 CMAS 腐蚀问题。目前 CMAS 腐蚀已经成为制约 TBCs 应用和发展的关键因素,如何提高 TBCs 的 CMAS 防护能力是 TBCs 领域的研究热点和难点。针对此问题,对不同类型 CMAS 的室温和高温特性进行总结,深入分析 CMAS 作用下 TBCs 的失效机制,总结 TBCs 的 CMAS 防护方法,综述 TBCs 的 CMAS 腐蚀与防护研究进展。结果表明,不同 CMAS(如火山灰、沙石和灰尘等)的化学成分(质量分数)差异明显,影响了其高温黏度和熔化行为;高温下熔融 CMAS 渗入到涂层内部并与之发生化学反应,破坏了涂层的结构和性能稳定性,造成涂层失效;提出了增加惰性防护层、YSZ 材料掺杂改性和研发新材料等方法,以提高 TBCs 的 CMAS 防护能力。最后对未来的 CMAS 防护新方法进行展望,对超高温长寿命 TBCs 的研制提供理论支撑。
关键词:  先进航空发动机  热障涂层  CMAS  腐蚀防护
DOI:10.11933/j.issn.1007?9289.20221120001
分类号:TG174
基金项目:国家自然科学基金资助项目(51901006)
Research Progress of CMAS Corrosion and Protection Method for Thermal Barrier Coatings in Aero-engines
WU Yang, GUO Xingye, HE Dingyong
Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124 , China
Abstract:
Thermal barrier coatings (TBCs) are widely used in the hot-section components of gas-turbine engines to allow operation at higher temperatures (> 1 200 ℃), which has created some new issues. One issue is the spallation and premature failure of TBCs caused by calcium-magnesium-alumino-silicate (CMAS) deposits, which arise from entry of siliceous debris such as fly ash, sand, dust, and volcanic ash into engines. Since 1953, over 130 jet aircraft have encountered volcanic ash clouds, with varying degrees of damage and endangering the lives of many passengers. The 2010 eruption of Eyjafjallaj?kull volcano in Iceland led to the most severe air-traffic disruption since World War II. The operational response produced economic losses approaching 1.7 billion. When these debris enter the hot-section airfoil, they melt and are accelerated from low speed (~15 m / s) to near supersonic speed (~300 m / s), impacting and adhering to the TBC surface. Even with only a few molten silicate ash droplets adhering to the surface of hot-section airfoils, an initial deposit layer can form and large melt pockets (several cubic centimeters in volume) can accumulate. Such deposits can 1) block cooling holes and air flow paths, and 2) react with the top coating of hot-section airfoils. Furthermore, adhering droplets infiltrate the interior of TBCs under capillary forces. Due to the thermal gradient and thermal cycling, the infiltrated CMAS solidifies and fills in the microcracks, pores, and grain boundaries, resulting in loss of strain tolerance and increased coating stiffness. For traditional 7–8 wt.% yttria-stabilized zirconia (YSZ) material, chemical reaction with CMAS destroys the phase and structure stability. YSZ grains dissolve and Y-depleted ZrO2 grains precipitate due to the relatively low solubility of Zr4+ compared with Y3+ in melted CMAS. Upon cooling, the newly formed grains transform from tetragonal (t) to monoclinic (m) phases, accompanied by a 3%–4% volume expansion. As turbine inlet temperatures improve and industry production grows, TBCs are suffering from severe CMAS corrosion. This issue limits further application and development of TBCs; enhancing anti-corrosion performance of TBCs has become a concern. Herein, we compare the room-temperature and high-temperature properties of different CMAS and study the failure mechanism of TBCs exposed to CMAS. We also determine the most effective CMAS protection method. The results show that the chemical compositions, especially the Ca:Si ratio, of CMAS such as volcanic ash, dust and sand are different, further affecting their high-temperature viscosities and melting behaviors. With infiltration of molten CMAS toward the coating interior, chemical reaction occurs between them, resulting in instability of the coating microstructure and properties, and failure. Significant methods including inert-layer, rare-earth doping and novel materials have been proposed to improve the CMAS corrosion resistance of TBCs. The research and future development directions of CMAS corrosion and protection are proposed, providing a reference for design of novel TBCs.
Key words:  advanced aero-engines  thermal barrier coatings(TBCs)  calcium-magnesium-alumino-silicate(CMAS)  corrosion protection
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