搭接率对激光重熔氧化锆涂层结构及热震性能的影响

The life of thermal barrier coatings prepared by large-area laser remelting is affected by change of structure in overlap region. The yttria stabilized zirconia coating was subjected to multi-pass laser remelting, and the change law of the surface and the cross-section microstructure morphology of the remelted coating under different overlap rates were investigated. Thermal shock experiment was conducted at 1 050℃ in the resistance heating furnace to analyze the influence of the coating structure with change of the overlap rate on the thermal cycle life. The result observed by scanning electron microscope shows that cracks around the dividing line between adjacent laser remelted coatings cross each other. In overlap region, with the increasing overlap rate, the density of cracks decreases, while the pits and small crumblings increase. After thermal shock experiment, the average width of surface crack decreases to 5 μm, and a large number of pits mostly caused by exfoliation of small fragments appear on the surface of laser remelted coating. As the overlap ratio increases, the deflection angle of the longitudinal cracks in the overlap region increases first and then decreases, while the thermal cycle life of the coating first decreases and then increases. The deflection of section longitudinal cracks in overlap region accelerates the generation of horizontal cracks, and the deflection angle is smallest when the overlap rate is 0.30. When the exfoliation percentage is or more than 20%, the laser remelted coating with 0.30 of overlap rate performs best.