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采用等离子喷涂-物理气相沉积(PS-PVD)工艺制备柱状7YSZ热障涂层,同时在7YSZ涂层表面沉积CMAS熔盐,研究在1250℃高温下,CMAS对柱状PS-PVD 7YSZ涂层抗热冲击性能的影响。采用SEM、EDS、XRD等检测方法分析热障涂层微观结构、元素分布和物相组成。结果表明:沉积CMAS熔盐的7YSZ涂层在热循环240次发生层离剥落失效,而未沉积CAMS的涂层无明显剥落,其热循环寿命明显优于沉积CMAS熔盐的7YSZ涂层。在CMAS和循环热冲击的耦合作用下,PS-PVD 7YSZ涂层失效机制为:在热冲击过程中,CMAS熔盐渗入并填充7YSZ涂层,引起渗透区和未渗透区热膨胀系数不均衡,从而产生热不匹配应力;此外,热冲击过程中由于温度梯度的存在也会引起温度梯度热应力,在这两种热应力的耦合作用下,引起涂层内部横向裂纹的产生,并随着热冲击次数的增加,横向裂纹发生扩展,最终导致涂层出现层离剥落失效。
The column 7YSZ thermal barrier coating was prepared by plasma spray-physical vapor deposition (PS-PVD) process. At the same time, the CMAS molten salt was deposited on the surface of 7YSZ coating. The effect of CMAS on the columnar PS-PVD 7YSZ coating Impact of impact. The microstructure, elemental distribution and phase composition of the thermal barrier coatings were analyzed by SEM, EDS and XRD. The results show that the 7YSZ coating deposited with CMAS molten salt failed to delaminate after 240 cycles of thermal cycling, while the unexposed CAMS coating did not peel off significantly. The thermal cycle life of the 7YSZ coating was significantly better than that of the 7YSZ coating deposited with CMAS molten salt. Under the coupling of CMAS and cyclic thermal shock, the failure mechanism of PS-PVD 7YSZ coating is as follows: CMAS molten salt infiltrates and fills 7YSZ coating during thermal shock, resulting in unbalanced thermal expansion coefficient between permeating zone and non-permeating zone. In addition, due to temperature gradient in the thermal shock process will also cause temperature gradient thermal stress, the coupling of these two thermal stresses, causing the coating to produce lateral cracks, and with the impact of thermal shock Increasing the number of transverse cracks occur, eventually leading to the coating layer peeling off failure.