Development of High-Heat Resistant Materials for Aerospace Use by Means of Gas Tunnel Type Plasma Reactive Spraying

点击翻译按钮获取中文摘要

The results obtained by this study are as follows :1) The titanium nitride (TiN) coatings of 150μm thickness were obtained at P=25kW, t=5s in a short time operation, by means of the gas tunnel type plasma reactive spraying. Some coating characteristics which depend on the traverse number, powder feed rate, the environmental gas, etc. were clarified and the optimum condition was decided.2) The hardness of TiN coating was uniform in the cross section and the porosity was decreased with increase in the traverse number. The adhesion strength of TiN coating was about 14 MPa, and was decreased as the thickness was increased. As the results, 100μm thickness coating had better mechanical properties such as wear resistance.3) The TiN ratio of the obtained TiN coating was more than 95%, and was increased with increased in the mixing ratio of N_2 gas. After heat treatment the property of the TiN coating was improved without oxidation.4) High hardness zirconia (ZrO_2-Al_2O_3) composite coating formed by gas tunnel type plasma spraying had a graded functionality of hardness. With increase in Al_2O_3 mixing ratio, the graded functionality ZrO_2-Al_2O_3 composite coating was enhanced and dense coating was obtained. The combination of high hardness of Al_2O_3 with the low thermal conductivity of ZrO_2 will contribute the development of high functionally graded TBC (thermal barrier coating).5) The plasma temperature was 8000K at the torch exit, and the sprayed particle velocity was 150m/s, which were increased with increase in the plasma input power.6) This study proved that these coatings was available as High-Heat Resistant Materials for Aerospace Use, by using of gas tunnel type plasma spraying and/or reactive spraying method.