炉压和试样位置对CVD⁃SiC涂层组织与抗热疲劳性能的影响

Effects of Furnace Pressure and Sample Position on Microstructure and Thermal Fatigue Resistance of CVD⁃SiC Coatings

带有SiC涂层的石墨基体可以有效解决石墨材料在高温、腐蚀性气体环境中的腐蚀掉粉问题。在石墨基体表面制备碳化硅涂层,通过调整优化各项沉积工艺参数,以期达到快速制备高性能SiC涂层的目标,为其在石墨基体表面的应用提供理论基础和技术支持。以甲基三氯硅烷(MTS)、H_(2)为原料,使用工业级化学气相沉积设备在石墨基体表面制备碳化硅涂层,结合扫描电镜、X射线衍射仪、真空热循环等分析测试方法,研究了炉压和试样位置对涂层组织结构和抗热疲劳性能的影响规律。结果表明:炉压为2.0 kPa时可以制备出晶粒生长取向性单一且高纯的碳化硅涂层,随着炉压增大,涂层沉积速率和抗热疲劳性能均呈现出先升后降再升的非单调性变化,其中炉压为2.0 kPa时碳化硅涂层的沉积速率最快且其热疲劳性能最好;不同试样位置时制备的涂层均为纯的SiC涂层,试样悬挂位置距离布气盘越近时涂层沉积速率越快,且其抗热疲劳性能越好。炉压为2.0 kPa、试样位置为300 mm时可快速制备出抗热疲劳性能良好的SiC涂层。

The SiC coating prepared on graphite substrate can effectively solve the corrosion and powder loss problems of graphite material in environments with high temperature and corrosive gas.In this paper,a SiC coating was prepared on the surface of graphite substrate.The depo⁃sition process parameters were adjusted and optimized to realize rapid manufacturing of high⁃performance SiC coating with the aim of providing theoretical basis and technical support for SiC coating’application on the surface of graphite substrate.An industrial⁃grade chemical vapor dep⁃osition equipment was employed to prepare the silicon carbide coating on the surface of graphite substrates using methyl trichlorosilane(MTS)and H_(2) as raw materials.The effects of furnace pressure and sample position on the microstructure and thermal fatigue resistance of the coating were studied by analysis and testing methods such as scanning electron microscopy,X⁃ray diffractometer and vacuum thermal cycling.Results showed that when the furnace pressure was 2.0 kPa,a high⁃purity silicon carbide coating with single grain growth orientation could be pre⁃pared.As the furnace pressure increased,the deposition rate and thermal fatigue resistance of the coating both showed a non⁃monotonic change of first rising,then falling and then rising again.When the furnace pressure was 2.0 kPa,the silicon carbide coating had the highest deposition rate and the best thermal fatigue resistance.The coatings prepared with different sample positions were all pure SiC coatings,and the closer the substrate suspension position to the air distribution plate,the faster the coating deposition rate was and the better thermal fatigue resistance the coating showed.When the furnace pressure was 2.0 kPa and the sample position was 300 mm,a SiC coating with good thermal fatigue resist⁃ance could be quickly prepared.