YSZ层孔隙率对GYYSZ/YSZ热障涂层热冲击寿命的影响

Effect of YSZ layer porosity on thermal shock life of GYYSZ/YSZ thermal barrier coatings

采用等离子喷涂法在TA15上制备了3种不同结构的TBCs,对涂层的微观结构、显微硬度和隔热性能进行了表征。通过1 200℃下的热冲击试验,研究了过渡层YSZ孔隙率对其热冲击寿命性能的影响,讨论了涂层失效的机理。实验结果表明,涂层A由于高孔隙率和Gd、Yb稀土元素的掺杂,在1 200℃下隔热效果是涂层B的1.2倍,是涂层C的1.1倍,过渡层8YSZ涂层孔隙率的增加会在一定程度上提高TBCs整体的隔热效果。1 200℃下涂层C的热冲击寿命分别是涂层A的1.8倍,是涂层B的2.7倍。涂层C中LP-YSZ的设计,增强了界面处的强韧性,过渡层YSZ孔隙率的提高,增大了TBCs抵抗变形的能力,延缓了涂层中垂直与横向裂纹的相连。

Thermal barrier coating is an effective thermal protection measure for aerospace titanium alloy parts. As the increase of service temperature in aerospace, the traditional 6%-8% Y2O3stabilized ZrO2( 8YSZ) thermal barrier coating materials could not meet the thermal insulation and service life requirements of aerospace structural materials. It is necessary to develop a new thermal barrier coating with excellent thermal cycling performance at higher temperature. Three different structures of TBCs: A, B, and C were prepared on TA15 by plasma spraying, and the microstructure, microhardness and thermal insulation of the coatings were characterized. Through the thermal shock test at 1 200 ℃, the influence of the YSZ porosity of the transition layer on its thermal shock life performance was studied, and the failure mechanism of the coating was discussed. The experimental results show that the thermal insulation effect of coating A is 1.2 times that of coating B and 1.1 times that of coating C at 1 200 ℃ due to the high porosity and the doping of Gd and Yb rare earth elements. The transition layer 8YSZ coating has porosity. The increase of the thermal insulation rate will improve the overall thermal insulation effect of TBCs to a certain extent. The thermal shock life of coating C at 1 200 °C is 1.8 times that of coating A and 2.7 times that of coating B, respectively. The fracture toughness and tensile strength of high-porosity GYYSZ coatings are low, and the introduction of YSZ transition layers can significantly improve the overall mechanical properties of TBCs.The increase in porosity of the transition layer 8YSZ will improve the overall thermal insulation effect of TBCs to a certain extent.The design of LP-YSZ in coating C enhances the strength and toughness at the interface, and the increase in the porosity of the transition layer YSZ increases the ability of TBCs to resist deformation and delays the connection of vertical and transverse cracks in the coating.