Tuning oxidation resistance and slag penetration resistance of MgO-SiC-C refractories via Si3N4 addition

• Published in: Journal of the European Ceramic Society 2024-12, Vol.44 (15), p.116718, Article 116718
• Main Authors: Zhao, Xu, Guo, Weijie, Zhu, Tianbin, Chen, Qilong, Xu, Xiaofeng, Wang, Zhiqiang, Li, Yawei, Xu, Yibiao, Dai, Yajie, Li, Yuanjin, Wang, Xuyuan, Yan, Wen
• Format: Article
• Language: English
• Subjects: MgO-SiC-C refractories; Microstructure; Oxidation resistance; Si3N4 power; Slag resistance
• ISSN: 0955-2219
• DOI: 10.1016/j.jeurceramsoc.2024.116718

The infiltration of matte smelting slag into refractories and the oxidation of graphite pose significant challenges in MgO-SiC-C refractories used for matte smelting furnaces. In this work, the Si3N4 was selected as the additive, aiming to enhance the oxidation resistance and slag resistance of MgO-SiC-C refractories. With 6 wt% Si3N4, the oxidation resistance of specimens was improved by 15.4 %. The Si3N4 functioned as an antioxidant, providing protection to the graphite, while the forsterite was formed through an in-situ reaction facilitated by the addition of Si3N4, and a large amount of forsterite was formed in the specimens with Si3N4 added in the air atmosphere, resulting in a decrease in the apparent porosity after oxidation compared with the specimens without Si3N4, thereby improving the oxidation resistance of the material. Also, the Si3N4 facilitated the formation of the forsterite layer at slag/refractory interface, resulting in a significant 61 % reduction in the thickness of the penetration layer. Furthermore, the addition of Si3N4 increased the wetting angle between the slag and refractory, leading to a decrease in the penetration ability of matte smelting slag.