飞秒激光加工气膜孔的热障涂层表面残余应力研究

Study of Residual Stress on the Surface of Thermal Barrier Coatings of Cooling Holes Processed by Femtosecond Laser

针对飞秒激光打孔后孔周热障涂层残余应力演化问题,采用cosα法对不同飞秒激光工艺制备的气膜冷却孔周围残余应力进行步进式逐点测量,结果表明,喷涂态热障涂层和激光打孔后气膜孔周围的涂层表面应力皆是以淬火应力主导的残余拉应力;不同飞秒激光加工工艺、不同的孔尺寸下,气膜孔周围都存在一个明显的径向残余应力影响区,且在该影响区内残余应力呈线性递减;由于飞秒激光热效应形成的飞溅物的影响,不同工艺制备的气膜孔周围径向残余应力场无明显差别,改变气膜孔直径无法改善这种热效应。

The evolution of residual stresses in the thermal barrier coating around the hole after femtosecond laser drilling was investigated by step-by-step measurement of residual stresses around the cooling hole prepared by different femtosecond laser processes using the cosa method.The results show that the surface stress of the sprayed thermal barrier coating and the coating around the hole after laser drilling are both residual tensile stresses dominated by quenching stresses.Under different femtosecond laser processing processes and different hole sizes,there is an obvious radial residual stress zone around the gas film hole,and the residual stress is linearly decreasing in this zone.There is no significant difference in the radial residual stress field around the gas film hole prepared by different processes due to the influence of the spatter formed by the thermal effect of femtosecond laser,and changing the diameter of the gas film hole cannot improve this thermal effect.