热喷涂构件中残余应力的理论分析

本文发展了一种新的分析涂层结构(平板、梁)热残余应力的模型,可以研究骤冷过程(Quenching)和冷却过程(Cooling)在涂层结构内引发的残余应力分布。与以往模型相比,其优势在于:它可以考虑源于喷涂过程的涂层孔隙率、温度梯度等因素对于涂层和基底内残余应力的影响。其中孔隙率和温度分布由计算机模拟涂层沉积过程得到。另外,当基底的材料和几何参数被固定时,我们分析了诸如涂层的理想模量、厚度、热膨胀系数等参数,对于涂层结构中最终残余应力分布的改变机理。

A NEW ANALYTICAL MODEL FOR RESIDUAL STRESSES DUE TO THERMAL SURFACE COATING

In this paper, a new analytical model, which can be used to deal with the residual stresses distributions in the processes of quenching and cooling, is presented with the consideration of effects of porosity and temperature gradient in the coating. Firstly, the distributions of porosity and temperature along the thickness are obtained by computer simulation of the deposition of heated particulates with the new model, the effects of thermal expanding coefficients, Young's modulus, temperature of substrate, etc., on the changing of residual stresses are investigated. It is found that the increase of the cooling temperature and the enlargement of the difference of expanding coefficients between substrate material and coating ceramic can reduce the tensile residual stress in the coating layers and prevent efficiently the coating from failing.