碳化铪氧化的热力学研究

A Thermodynamic Study on the Oxidation of HfC

采用平衡热力学方法研究了碳化铪(HfC)的氧化机理,分析了氧气含量O2、温度T和总压p三种因素的影响。结果表明,氧含量主要影响残余C-O产物的类型和含量,温度主要影响Hf和C的固相产物晶型,压强主要影响C的气相产物类型和含量。在低温区(T<1699.85℃)和高温区(1699.85℃≤T<2899.85℃),HfC中的Hf会分别氧化生成单斜相和四方相氧化铪。在低温区(T<1273.0℃)和氧含量较少时,HfC中的C元素以石墨态剩余,随氧含量增加C逐步氧化为CO和CO2;在高温区(T≥1273.0℃),HfC中的C和Hf同时被氧化;由此提出了HfC中Hf和C分别氧化的机理模型。计算结果与相关实验报道和理论计算结果一致,可为HfC在高温下的实际应用提供理论指导。

The per（ormanees of oxygen content, temperature and pressure on the oxidation behavior of HfC were thermodynamically investigated. The results of equilibrium thermodynamic calculations reveal that the amount of O2 affects the types and amounts of residual （2-0 products; the temperature has a significant influence on the solid phase structures of HI and C products; and the effect of total pressure results in the production of different types and amounts of C-containing gases. It is concluded that the temperature and O2 content are the major factors during the oxidation of HfC, while the pressure is a temperature-dependent minor factor. Based on the results and detailed analy- sis, a schematic model for the oxidation mechanism of Hf and C components in HfC is proposed. The present calcula- tion results are consistent with the available experimental and theoretical results, and they will guide the applications of HfC.