陶瓷涂层三明治板的抗热震性

采用解析法研究了第3类边界条件下双面陶瓷涂层三明治板的瞬态温度场及瞬态热应力场.对不同Biot模数的热冲击过程中,Al2O3涂层/硬质合金(WC-8%Co,质量分数)基体/Al2O3涂层三明治板的瞬态热应力进行了数值计算.分析了涂层/基体厚度比、涂层与基体热-物理性能匹配对陶瓷涂层三明治板表面热应力峰值的影响.结果表明:陶瓷涂层三明治板的基体的热导率、线膨胀系数和弹性模量应高于涂层,这样可以降低其表面热应力,获得高抗热震性陶瓷涂层三明治板.此外,涂层厚度应尽可能小,以利于改善涂层的抗热震性.

THERMAL SHOCK RESISTANCE OF THE CERAMIC COATED SANDWICH PLATE

The transient temperature field and transient thermal stress field of a sandwich plate with double-sided ceramic coatings under the convective boundary condition were investigated by an analytical solution approach. Numerical calculations of transient thermal stresses for a plate of Al2O3 coating/ cemented carbide (WC-8%Co, mass fraction) substrate/Al2O3 coating system under different Biot numbers in thermal shock were performed. The effects of the coating-to-substrate thickness ratio and the thermo-physical properties matching of coating with substrate on the peak surface thermal stress of the ceramic coated sandwich plate were analyzed. The results reveal that the thermal conductivity, thermal expansion coefficient and Young's modulus of the substrate must be higher than that of the coating in the coated sandwich plate in order to reduce its surface thermal stress and obtain high thermal shock resistance. Furthermore, the coating must be as thin as possible in order to improve the thermal shock resistance of the coating on the surface of the coated cutting tools.