铁橄榄石的氧化动力学研究

Research of oxidation kinetics of fayalite

采用热重法研究了700～800℃条件下,铁橄榄石的氧化过程。根据重量的变化,铁橄榄石的氧化分为四个阶段:反应孕育期、迅速反应期、缓慢反应期、反应平衡期。随着氧化温度的升高,瞬时反应速率增加,宏观氧化率X增大。根据铁橄榄石颗粒的特点,确定其动力学模型属于带圆孔的收缩性未反应核模型。铁橄榄石刚开始氧化时是化学反应控制,生成较薄一层氧化层后受化学反应与内扩散同时控制,氧化层较厚时则受内扩散单独控制。

The fayalite oxidation process under the conditions of 700～800℃was studied using thermogravimetric method.According to the change of weight,the oxidation process was able to be divided into four stages：reaction incubation period,rapid reaction period,slow reaction period and reaction equilibrium period.Instantaneous reaction rate and oxidation ratio X increased with the rise of temperature.Based on the characteristics of fayalite grain,it was defined that the kinetics model of fayalite grain was shrinking unreacted core model with round holes.In the beginning of oxidation process,the reaction was mainly controlled by chemical reaction.After generating a thin layer of oxide layer,it was controlled by chemical reaction and internal diffusion simultaneously.When oxide layer become thicker,it was independent controlled by internal diffusion.