超音速火焰喷涂MCrAlY粘结层对热障涂层热震性能的影响

Effects of HVOF bond coat on thermal cyclic failure lifetime of thermal barrier coating

分别采用超音速火焰喷涂技术(HVOF)和等离子喷涂技术(APS)在高温合金GH99上制备MCrAlY粘结层(BC),对比研究了HVOF和APS喷涂BC对热障涂层(TBC)热震性能的影响。结果表明:APS喷涂BC界面不平整,起伏较大,而HVOF喷涂BC界面较为平整。经200次热循环后,APS喷涂TBC部分陶瓷层(TC)出现剥落,而HVOF喷涂TBC仅出现细小的微裂纹,生成的热生长氧化物(TGO)比较厚。APS喷涂TBC经过350次热循环后,涂层出现大面积剥离现象。而HVOF热障涂层直到热震430次后,才出现涂层剥落现象。拉曼光谱(RFS)残余应力分析表明,HVOF热障涂层残余应力随热循环次数的增加而增大,热震350次后APS热障涂层残余应力为650MPa,而HVOF热障涂层热震400次后其应力值仅为571MPa。可知,HVOF显著地提高了TBC的热震性能。

NiCoCrAlY bond coat（BC）was fabricated on the GH99 superalloy by high velocity oxy-fuel spray（HVOF）and air plasma spray（APS）respectively.Thermal cyclic failure of thermal barrier coating（TBC）with APS and HVOF BC were studied.The results show that the interface of APS BC is irregular with wave morphology,and it is relatively straight and uniform for the interface of HVOF BC.The ceramic top coat（TC）of TBC with APS BC partly spalled-off after 200 thermal cycles.Only micro-cracks were observed in the TBC with HVOF BC after same thermal cycles,and thicker layer of thermally grown oxide（TGO）formed.Most of the TC of TBC with APS BC spalled-off after 350 thermal cycles,however,after 430 thermal cycles,the propagation of micro-cracks led to the failure of TBC with HOVF BC.The residual stress analysis by Raman spectroscopy（RFS）shows that the residual stress of TBC with HVOF BC increased with increasing number of thermal cycle.The residual stress of TBC with APS BC reached a value of 650 MPa at 350 thermal cycles and that of TBC with HVOF BC only reached 571 MPa at 400 thermal cycles.Thermal shock resistance of TBC can be improved with NiCoCrAlY bond coat perpared by HVOF technology.