热循环对薄板镍基合金表面高辐射率涂层残余应力的影响

Effect of Thermal Cycling Evolution on Residual Stress of High Emissivity Coating on Ni-Based Superalloy Sheet

采用X射线衍射技术对不同次数热循环的镍基合金薄板表面的高辐射涂层的残余应力进行了分析,利用扫描电镜对热循环前后涂层的截面形貌进行了表征,研究热循环对涂层表面残余应力的影响。结果表明:涂层主要由非晶态的硼硅玻璃,硼酸镁,二硅化钼和四硼化硅组成;随着热循环次数的增加,涂层内部出现很多微裂纹和孔洞,但是涂层与基体的结合良好;涂层表面存在压应力,随着热循环次数的增加,涂层压应力先增加后减小。

A method based on the X-ray diffraction geometry has been applied to measure the residual stresses present in coatings on Ni-based superalloy sheet. The cross-sectional backscattered electron images of the coating before and after the thermal shock testing were tested by SEM. The results show that the coating contains amorphous borosilicate glass, Mg2B2O5 , MoSi2 and SiB4 . As the thermal shock cycles are prolonged, the crack density becomes higher but the coating is still adhered onto the substrate. The high compressive stress occurs in the coating. The radial stress in coating layer first increases and then decreases with more thermal cycling times.