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。
Thermal barrier coatings(TBCs)are widely used in the hot-section components of gas-turbine engines to allow operation at higher temperatures(>1200℃),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 Eyjafjallajokull 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 ZrO_(2) grains precipitate due to the relatively low solubility of Zr^(4+)compared with Y^(3+)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 c
作者
吴杨
郭星晔
贺定勇
WU Yang;GUO Xingye;HE Dingyong(Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China)
出处
《中国表面工程》
EI
CAS
CSCD
北大核心
2023年第5期1-13,共13页
China Surface Engineering
基金
国家自然科学基金资助项目(51901006)。
关键词
先进航空发动机
热障涂层
CMAS
腐蚀防护
advanced aero-engines
thermal barrier coatings(TBCs)
calcium-magnesium-alumino-silicate(CMAS)
corrosion protection
