SiC/Fe_xSi_y复合材料抗氧化性能研究

Study on Inoxidizability of SiC/Fe_xSi_y Composites

对以铁尾矿为主要原料制备的S iC/FexS iy复合材料进行抗氧化性能实验。变温氧化实验结果表明,复合材料在1000℃下有很好的抗氧化性能,而在1180℃以上氧化明显加剧。随氧化时间的延长,扩散成为控制性环节,表现为保护性氧化。复合材料在整个变温氧化过程中,表现为先失重再增重;1210℃时,增重达到最大值;整个变温氧化过程分为三个阶段:(1)增重阶段;(2)恒重阶段;(3)失重阶段。复合材料的氧化规律服从化学反应控速-混合控速-扩散控速三段模型。通过对复合材料恒温氧化动力学推导,求出材料在不同阶段表观活化能及频率因子,进而可推导出各阶段氧化速度常数k和温度T(K)的经验关系式。

Through experiment of antioxidation for SiC/FexSiy composites whose main raw material was iron tailing,the inoxidizability of composites was very well below 1000 ℃.The oxidation of composites was enhanced distinctly after 1180 ℃.With time extension,the controlled factor became into diffusion and the process of oxidation was protected.During the course of oxidation of variable temperature,composites were weightless firstly then changed to weight increment next.At 1210 ℃ the weight increment reached a maximum.The process of oxidation in different temperature included three stages that were weight increment,constant weight and weightlessness.The oxidation mechanism fit in the chemical model which reaction velocity is controlled by chemical reaction,mixing and diffusion.Through deduction of kinetics for oxidation at the same temperature,activation energy and frequency factor were calculated.The relational formula was also obtained between reaction rate constant and temperature.