Selective sintering of magnesia–calcia materials by utilizing hot spots during induction sintering process

• Published in: Journal of iron and steel research, international international, 2024-08, Vol.31 (8), p.1914-1922
• Main Authors: Dong, Yun-jie, Wang, Zhou-fu, Liu, Hao, Ma, Yan, Wang, Xi-tang, Yi, Nian, Xia, Zhong-feng, Zhu, Yu-xuan, Deng, Cheng-ji, Zhang, Ling
• Format: Article
• Language: English
• Subjects: Applied and Technical Physics; Engineering; Machines; Manufacturing; Materials Engineering; Materials Science; Metallic Materials; Original Paper; Physical Chemistry; Processes
• ISSN: 1006-706X; 2210-3988
• DOI: 10.1007/s42243-023-01164-4

Magnesia–calcia refractories are widely used in the production process of clean steel due to their excellent high-temperature stability, slag resistance and ability to purify molten steel. However, there are still problems such as difficult sintering and easy hydration. Magnesia–calcia materials with various calcium oxide contents were prepared by using induction sintering, and the sintering property combined with the hydration resistance of the materials was investigated. The experimental results showed that the magnesia–calcia materials prepared under induction field had higher density, microhardness and hydration resistance. In particular, the relative density of induction sintered magnesia–calcia materials with 50 mol% CaO was greater than 98%, and the average grain size of CaO was 4.56 μm, which was much larger than that of traditional sintered materials. In order to clarify the densification and microstructure evolution mechanism of the magnesia–calcia materials, the changes in temperature and magnetic field throughout the sintering process were analyzed by using finite element simulation. The results showed that the larger heating rate and higher sintering temperature under the induction sintering mode were beneficial to the rapid densification. In addition, the hot spots generated within the material due to the difference in high-temperature electric conductivity between MgO and CaO were the critical factor to realize selective sintering in MgO–CaO system, which provides a novel pathway to solve the problem of difficult sintering and control the microstructure of high-temperature composite material used in the field of high-purity steel smelting.