Microstructure and Properties of Low‐Carbon MgO─C Refractories Containing Various Particle Size of Microporous Magnesia

ABSTRACT

The development of low‐carbon magnesia–carbon refractories is of great significance for clean steel smelting. To overcome the deterioration of thermal shock resistance and slag resistance of low‐carbon magnesia–carbon refractories caused by the reduction of carbon content, microporous magnesia aggregates were used to replace commercial fused magnesia aggregates in this study. The effects of microporous magnesia aggregates with different particle sizes on the structure and properties of low‐carbon magnesia–carbon refractories were investigated. The microporous structure inside the microporous magnesia aggregates can effectively disperse thermal stress. Meanwhile, the low dissolution rate of microporous magnesia aggregates and the intergranular CaZrO ₃ promote the formation of a dense erosion layer. Therefore, low‐carbon magnesium–carbon refractory materials prepared using a combination of 5–3 mm and 3–1 mm microporous magnesia aggregates exhibit good slag resistance after 3 h of heat treatment at 1600°C in an air atmosphere and good thermal shock resistance after 0.5 h of heat treatment at 1100°C in an air atmosphere followed by three cycles of air cooling. The residual strength retention rate reaches 97.2%, and the corrosion index and penetration index are 33.7% and 30.4%, respectively.