摘要
以铝粉、硅粉、和碳粉为原料制备出Al_(4)SiC_(4)粉体,采用连续称重法研究了Al_(4)SiC_(4)粉体在600~1200℃下的氧化动力学.研究结果表明,Al_(4)SiC_(4)粉体的氧化过程可分为两个阶段,两个阶段的氧化速率均随温度的升高而增大,但第二阶段的反应活化能远大于第一阶段的反应活化能.通过动力学分析可知,第一阶段的动力学方程符合表面化学反应控制模型,而第二阶段的动力学方程则符合扩散控制模型,两个阶段的氧化速率常数分别为:k_(1)=8.17exp(-47.47/RT)和k_(2)=105.34exp(17500/RT).Al_(4)SiC_(4)粉体的整个氧化过程符合两阶段模型,这是由于在其表面生成了一层由Al_(2)O_(3)和SiO_(2)组成的氧化膜.同时,该氧化膜使得反应物氧气和生成物二氧化碳的扩散变得缓慢,反应速率减小.因此,扩散被认为是整个氧化过程的限制性环节.
Al_(4)SiC_(4)powders have been synthesized from Al,Si,and C powder as raw materials and the oxidation kinetics of Al_(4)SiC_(4)powder in the temperature range of 600~1200℃have been studied by continuous weighing method.The results show that the oxidation process of Al_(4)SiC_(4)can be divided into two stages and the oxidation rates rise with increasing temperature,however,the apparent activation energy of the first stage is much higher than that of the second stage.Through kinetic analysis,it can be seen that the kinetic equation of the first stage conforms to the surface chemical reaction control model,while the kinetic equation of the second stage conforms to the diffusion control model.The oxidation rates of the two stages are k_(1)=8.17exp(-47.47/RT)and k_(2)=105.34 exp(-17500/RT),respectively.The entire oxidation process conforms to the two-stage model which is due to the formation of an oxide film composed of Al_(2)O_(3)and SiO_(2)on its surface.At the same time,the oxide film slows down the diffusion of the reactant O_(2)and the product CO and reduces the reaction rate.Therefore,diffusion is regarded as a restrictive parameter in the oxidation process of Al_(4)SiC_(4).
作者
郑岐
孙侨阳
袁磊
Zheng Qi;Sun Qiaoyang;Yuan Lei(Zhong Min Chi Yuan Industry Co.,Ltd.,Dashiqiao 115100,China;School of Metallurgy,Northeastern University,Shenyang 110819,China)
出处
《材料与冶金学报》
CAS
北大核心
2024年第5期427-431,共5页
Journal of Materials and Metallurgy
基金
国家自然科学基金项目(52174302)。
作者简介
郑岐(1994-),男,助理工程师,E-mail:835630025@qq.com;通讯作者:袁磊(1982-),男,教授,E-mail:yuanl@smm.neu.edu.cn.
