论文部分内容阅读
通过差热-热重分析研究了ZrB2含量为10%的ZrO2-C-ZrB2复合材料在800~1100℃下空气中的氧化动力学,根据气固相反应原理建立氧化动力学模型,计算反应表观活化能,并得到氧化速率与温度的经验关系式。结果表明,试样在800℃时的氧化过程仅有化学反应控速阶段与化学反应和气体扩散共同作用的混合控速阶段。900~1100℃的氧化过程为前期是化学反应控速阶段,中期为混合控速阶段,后期为扩散控速阶段。三个阶段的表观活化能分别为111.7、71.5和166.0 kJ.mol-1。材料等温氧化的质量变化规律表明在900℃~1100℃内的氧化属于保护型氧化。
The oxidation kinetics of ZrO2-C-ZrB2 composites with ZrB2 content of 10% in the air at 800 ~ 1100 ℃ was studied by DTA-TG. The oxidation kinetics model was established according to the gas-solid reaction principle and the reaction table View activation energy, and get the empirical relationship between oxidation rate and temperature. The results show that the oxidation process of the sample at 800 ℃ has only a mixed speed control stage in which the chemical reaction rate control stage and the chemical reaction and gas diffusion function together. The oxidation process from 900 ℃ to 1100 ℃ is that in the early stage of chemical reaction control, in the middle stage of mixing speed control and in the later stage of diffusion control. The apparent activation energy of the three stages were 111.7, 71.5 and 166.0 kJ.mol-1, respectively. The law of the mass change of material isothermal oxidation shows that the oxidation in 900 ℃ ~ 1100 ℃ belongs to the protection of oxidation.