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磁粉的封孔技术作为磁粉研制的关键技术之一,一直受到人们的重视。本文对γ-Fe_2O_3磁粉制造过程中热处理封孔技术的微观物理过程进行了探讨。实验结果表明,Fe_3O_4粉末的结晶致密化过程主要由氧离子扩散速度控制,其晶形收缩驱动力起源于其表面吉布斯能。在整个热处理封孔致密化过程中,物质流从晶粒表面向空洞处扩散,而空位〔注1〕由空洞表面向晶粒表面扩散。杂质和气氛往往影响整个扩散过程。
Magnetic particle sealing technology as one of the key technologies developed by magnetic particles, has been subject to people’s attention. In this paper, micro-physical process of heat-sealing sealing technology in the process of γ-Fe 2 O 3 magnetic powder manufacturing was discussed. The experimental results show that the crystal densification process of Fe 3 O 4 powder is mainly controlled by the diffusion speed of oxygen ions, and the driving force of crystal shrinkage originates from Gibbs energy of its surface. During the heat treatment, the material flow spreads from the surface of the grain to the cavity, while the vacancy [1] diffuses from the cavity surface to the grain surface. Impurities and atmosphere tend to affect the entire diffusion process.