枪速对热障涂层组织性能及残余应力的影响

为了研究等离子喷涂制备热障涂层(TBCs)时不同枪速对陶瓷面层组织性能和残余应力的影响,在GH4169高温合金基体上采用超音速火焰喷涂(HVOF)Ni Co Cr Al Y粘结层(BC层)和大气等离子喷涂(APS)8YSZ陶瓷层(TC层).通过对比不同参数样品的微观组织以及显微硬度、残余应力和热震性能差异,研究了枪速对热障涂层的影响.结果表明:枪速过低或过高时,涂层表面残余应力较大,热震性能较低;随着枪速的增大,涂层表面粗糙度逐渐增大,而孔隙率和显微硬度逐渐减小;枪速过低时,涂层出现纵向裂纹,热震失效方式为整体剥落;而枪速较大时,涂层从边缘向中心不断剥落,涂层表面出现白点.

Effect of robot-scanning speed on microstructure,mechanical properties and residual stress of thermal barrier coatings

In order to study the influence of robot scanning speed on the microstructure, mechanical properties and residual stress of thermal barrier coatings （TBCs） during the preparation of TBCs with the plasma spray method, the NiCoCrAlY bond coating （BC） was sprayed with the high velocity oxygen fuel （HVOF） method and the 8YSZ ceramic coating （TC） was sprayed with the atmospheric plasma spray （APS） method on GH4169 superalloy substrate. Through comparing the differences in the microstructure, microhardness, residual stress and thermal shock performance of samples with different parameters, the influence of robot scanning speed on the TBCs was determined. The experimental results show that when the robot scanning speed is too low or too high, the residual stress on the surface of coatings is higher, and the thermal shock performance is lower. The surface roughness tends to increase with increasing the robot scanning speed, while the porosity and microhardness gradually reduce. When the robot scanning speed is too low, the vertical microcracks appear, and the thermal shock failure mode is whole spalling. When the robot scanning speed is higher, the coating spalls from the edge to the center, and the white dots appear on the surface of coating.