Thermo-Mechanical Analysis on Formation and Strength of Coated Ceramic Film

点击翻译按钮获取中文摘要

In this project, two types of ceramic coating methods were investigated to analyze the internal stress generated in their coating systems. The coating processes to be analyzed in this work were the detonation coating process and the spattering process.An analytical method was proposed to evaluate the unsteady temperature and stress fields during the detonation coating process. The proposed procedure was developed by means of finite element modeling. A simulation using the proposed model was conducted for the detonation coating of alumina on steel as a discontinuous coating process. The temperature variation with respect to time during and after the coating process was simulated by the selection of a suitable combination of heat-transmission parameters. The results almost coincided with the experimental observation. The simulated results for the stress field indicated that the residual stress generated in the coated ceramic layer was tensile, as observed in X-ray analysis.Thin films of alumina and silicon carbide were deposited on the glass substrate in an RF magnetron spattering apparatus. The hardness, as a mechanical property, of the spattered films were evaluated by using an ultra-microscopic hardness testing machine. It was found that the hardness decreased with increasing RF output power in both ceramic films. A molecular dynamics approach was tried to estimate the internal stress field in spattered film. A hard-sphere model was adopted in the molecular dynamics of spattered particles. Based on empirical information, cluster of spattered particles was assumed to be larger with increasing RF output power. The experimental result was explained qualitatively by using the proposed analytical method.