氩气下Fe_2O_3-TiO_2体系的固相反应

Solid state reaction of the Fe_2O_3-TiO_2 system in argon

在氩气气氛下,采用扩散偶法研究了1323-1473 K下的Fe2O3-TiO2体系的固相反应.使用电子探针对扩散偶的微观形貌进行观察,并对Fe、Ti离子的扩散摩尔分数曲线进行定量分析.动力学分析表明,氩气下体系的固相反应受铁、钛和氧离子的扩散控制.用Boltzmann-Matano法计算了体系的互扩散系数,其数量级在10-13-10-10 cm2·s-1范围内,并随着温度和Ti离子摩尔分数的增大而升高.氩气气氛下体系的扩散活化能约为356.06 kJ·mol-1,远比空气下的大,表明外界气氛中氧分压对体系的反应机理有重要影响.

ABSTRACT The diffusion couple method was used to study the solid-state reaction of the Fe2 O3-TiO2 system in the temperature range of 1323 K to 1473 K in argon. The microstructure of the diffusion couple and the diffusion concentration profiles of Fe and Ti were determined by electron probe microanalysis （ EPMA） . According to kinetic analysis, this solid-state reaction is controlled by the diffu-sion of Fe, Ti and O ions. The inter-diffusion coefficient, which increases with the increasing temperature and concentration of Ti ions, was calculated by the Boltzmann-Matano method, and its order of magnitude is in the range of 10 -13 to 10 -10 cm2·s-1 . The diffusion activation energy （ about 356.06 kJ·mol-1 ） of the system in argon is much bigger than that in air, which indicates that the partial pres-sure of oxygen in atmosphere has important effect on the reaction mechanism of the system.