Failure Analysis of Engine Valves and its Performance Evaluation under Various Titanium Based Composite Coatings Using FE Analysis

摘要

In an internal combustion engine poppet valve is the crucial component which often opens and closes, thereby regulating gas flow in an engine cylinder. During engine operation, the valve is exposed to high temperature gases (thermal load) along with spring and cam loads (mechanical load). Due to high temperatures and fatigue loads, the valves are subjected to metallurgical changes and leads to failure. In order to resist these extreme conditions of high temperature and mechanical loads, the engine valve should possess special properties such as high surface hardness, a good amount of thermal conductivity, and fatigue strength. In this work, the reasons for the failure of two wheeler engine valve were evaluated and found that failure takes place due to change in the chemical composition mainly due to thermal diffusion at the interfaces. Thermal barrier coatings on the valve surface arrest the temperature load and increase its life. In this work, the performance of various titanium based composite coatings, i.e., TiN, TiC, TiC-Al_(2)O_(3), TiCN, TiAlN, TiN- Al_(2)O_(3), DLC, and uncoated valves of two wheeler engine was simulated using Finite Element Analysis. The simulation results indicated that coated valves have less thermal and fatigue loading and have more life than the uncoated valve. The Finite element simulation results of both coated and uncoated valves are presented and analyzed in this paper.