材料期刊网

从热力学角度出发，采用工程数学软件Matlab计算出了 在涉及超高温（2073 K以上）范围的宽温域内一些典型过渡金属 碳(硼)化物与氧反应的Δ G⁰，以及相应的平衡氧分压；在此基础上 绘制了2500 K时ZrC-ZrO₂体系和SiC-SiO₂体系的氧化物蒸气压图以及界面蒸气压随温度的变化曲线。依据上述热力学数据，可以了解不同碳化物的氧活性和平衡氧分压随温度的变化规律，以及ZrC-ZrO₂和SiC-SiO₂体系氧化物蒸气压特别是界面蒸气压的大小，对于深入了解改性C/C复合材料和超高温陶瓷的超高温氧化行为，特别是对于改性C/C复合材料中有效的抗氧化添加剂的选择有理论指导意义。

ΔG⁰-T diagrams of the reactions between some typical transition metal carbides (or borides) and oxygen were drawn using Matlab software. On the basis of these ΔG⁰-T diagrams, equilibrium partial oxygen pressures were obtained accordingly. The volatility diagrams for ZrC-ZrO₂ system and SiC-SiO₂ system at \linebreak2500 K were drawn and the function of the partial press of various related products in the ZrC-ZrO₂ system with temperature was evaluated. The calculation results indicated that the oxygen activity and equilibrium partial oxygen pressure of these carbides changed with temperature. According to the volatility diagrams of ZrC-ZrO₂ and SiC-SiO₂ systems, the vapour pressure of related oxides may be very high at the interfaces, even higher than 10⁵ Pa, which is detrimental to the formation of entire oxide scales on carbides during ultra-high temperature oxidation. This work provided significant insight into the behaviour of ultra-high temperature oxidation of C/C composites and ultra-high temperature ceramics. It especially provided theoretical considerations for choosing oxidation-resistance dopants in C or C/C composites.