预氧化处理对热障涂层热冲击性能及残余应力的影响

采用等离子喷涂工艺在镍基高温合金基体上制备了热障涂层(底层为MCrAlY,面层为ZrO2+ 8％ Y2O3),通过控制高真空烧结炉的氧分压对涂层进行预氧化处理,分析了预氧化处理对热障涂层热冲击性能和涂层应力状态的影响.结果表明,预氧化处理提高了粘接层的致密度,涂层组织变得均质化,降低了粘结层由于凸起尖角产生复杂应力的概率；有效干预热生长氧化物(TGO)的生长过程,降低了TGO的生长速度；热障涂层残余应力随热冲击次数的增加而增大,但经过预氧化处理的涂层应力增长幅度较缓慢,经过400次热冲击后的残余应力为492.5 MPa,未经过预氧化处理涂层热冲击350次后应力值为650.1 MPa.

Effect of pre-oxidation treatment on thermal shock resistance and residual stress of thermal barrier coating

The thermal barrier coating by taking MCrAlY as bonding coating and ZrO₂+8% Y₂O₃ as top coating were deposited on the nickel-based super-alloy by air plasma spraying. Pre-oxidation treatment was carried out on the thermal barrier coatings by controlling the oxygen pressure in high vacuum sintering furnace. Then,the effects of pre-oxidation treatment on the thermal shock resistance and residual stress were investigated, respectively. The results show that pre-oxidation treatment improves the density of bonding coating,which makes it uniform and reduces the probability of complex stress caused by convex point in interface area. Meanwhile,pre-oxidation treatment interferes the growth process of thermally grown oxide (TGO),reduces the TGO growth rate and the stress concentration of coating. Residual stress increases with the increasing of thermal cycles. However,pre-oxidation treatment can slow down the increasing rate of residual stress. The residual stress of 650.1 MPa can be reached after 350 thermal cycles without pre-oxidation, while the residual stress is only 492.5 MPa after 400 thermal cycles with pre-oxidation.