钛合金基体YSZ复合热障涂层微观结构与热震性能研究

Microstructure and thermal shock properties of YSZ composite thermal barrier coatings on titanium alloy substrate

在钛合金表面制备热障涂层,提高钛合金使用温度上限,对于其在航空航天领域的应用尤为重要。本文采用大气等离子喷涂方式,在TA15钛合金表面制备了3种不同结构的热障涂层,研究了涂层热震前后的相结构、微观组织,对比了涂层的热震寿命,分析了其失效机理。研究结果表明,喷涂态涂层为T’相(c/(√2a)≤1.01),热震后涂层未发生相变,GYYSZ/8YSZ复合热障涂层热震寿命比单层8YSZ涂层高2.6倍,比单层GYYSZ高3倍,热膨胀系数不匹配、涂层较低的抗拉强度和钛合金表面氧化物的生成是涂层失效的主要原因。

Thermal barrier coatings(TBCs)is a crucial technique to improve the upper service temperature of titanium alloy in aerospace field.In this paper,three kinds of TBCs were deposited on TA15 titanium alloy by atmospheric plasma spraying process.The phase structure,microstructure and thermal shock life of coatings were investigated for better understanding of the failure mechanism.The results show that T’phase is formed in the assprayed coating(c/(√2a)≤1.01),and no phase transformation occurs during the thermal shock process.The thermal shock life of GYYSZ/8YSZ composite coating is 2.6 times higher than that of single 8YSZ coating and 3 times higher than that of single GYYSZ coating.Mismatch of thermal expansion coefficient,low coating tensile strength,and the formation of oxides on the surface of titanium matrix,result in the failure of TBCs.