Correlation between microstructure and degradation characteristics of plasma-spray ceramics coating under cyclic heating condition

摘要

Since plasma-spray ceramic coating is comparatively easy to form thick coating, this coating method is already applied as thermal barrier coating. When these structural materials modificated by ceramic coating were exposed at high-temperature environment, various problems such as corrosion, erosion and oxidation and so on, have been experienced. And in case when applying ceramics coating to actual components, it is very important to understand their degradation characteristics. Therefore, in this study, oxidation degradation characteristics of plasma-spray ceramic coating was evaluated under cyclic heating condition. And then, by means of observing their microstructure, the interrelation between the above result and their degradation characteristics was examined. And, for the purpose of improving oxidation-resistant property, the effect of sealing treatment by ethylsilicate and nickel plating was examined. The result of cyclic heating test showed that in the early stages of cyclic heating, LPPS coating have superior oxidation-resistant property than APS coating. This result is caused by dense microstructure of LPPS coating. However, with the increase in cycles of heating, this relation is reversed due to the macrocrack generation in LPPS coating. And it is recognized that many pores in APS coating contributed to relieve the damage in cyclic heating. And it was recognized that sealing treatment is effective for improving oxidation-resistant and relieving the damage.