Tuning oxidation resistance and slag penetration resistance of MgO-SiC-C refractories via Si 3 N 4 addition

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 Si 3 N 4 was selected as the additive, aiming to enhance the oxidation resistance and slag resistance of MgO-SiC-C refractories. With 6 wt% Si 3 N 4 , the oxidation resistance of specimens was improved by 15.4 %. The Si 3 N 4 functioned as an antioxidant, providing protection to the graphite, while the forsterite was formed through an in-situ reaction facilitated by the addition of Si 3 N 4 , and a large amount of forsterite was formed in the specimens with Si 3 N 4 added in the air atmosphere, resulting in a decrease in the apparent porosity after oxidation compared with the specimens without Si 3 N 4 , thereby improving the oxidation resistance of the material. Also, the Si 3 N 4 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 Si 3 N 4 increased the wetting angle between the slag and refractory, leading to a decrease in the penetration ability of matte smelting slag.