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SiC/SiO2复合涂层是显著改善先进高温气冷用石墨抗氧化性能的一个理想涂层体系,但目前其优化的化学气相沉积工艺还未见诸报道。本研究利用HSC-CHEMISTRY 4.1分析了化学气相沉积工艺对制备的SiC/SiO2复合涂层的影响。分析结果表明:载气中加入足够的氢气对制备不含杂质的SiC/SiO2复合涂层很有必要;合适的沉积温度为1100~1200℃;最佳反应物浓度为:SiCl4摩尔分数为1%~2%,沉积SiC涂层时CH4与SiCl4的摩尔比为1,沉积SiO2涂层时水蒸气与SiCl4摩尔比为2,通过逐渐改变CVD气氛中的水蒸气与CH4的比例来沉积SiC/SiO2梯度过渡层。
SiC / SiO2 composite coating is an ideal coating system that can significantly improve the anti-oxidation performance of advanced graphite for high temperature gas-cooled graphite. However, the optimized chemical vapor deposition process has not been reported yet. In this study, HSC-CHEMISTRY 4.1 was used to analyze the effect of chemical vapor deposition on the prepared SiC / SiO2 composite coating. The results show that it is necessary to add enough hydrogen to the carrier gas to prepare the SiC / SiO2 composite coating without impurities. The suitable deposition temperature is 1100 ~ 1200 ℃. The optimum concentration of reactants is SiCl4 mole fraction is 1% ~ 2%, the molar ratio of CH4 to SiCl4 in the deposition of SiC coating is 1, the molar ratio of water vapor to SiCl4 in deposition of SiO2 coating is 2, SiC / SiO2 is deposited by gradually changing the ratio of water vapor to CH4 in the CVD atmosphere Gradient transition layer.