China's Refractories

Abstract: Multi-phase nitrides bonded silicon carbide lintel blocks were prepared using industrial SiC (SiC≥98 mass%, 3-0.5, ≤0.5 and ≤0.044 mm), Si powder (Si ≥98 mass%, ≤0.044 mm), and SiO₂ micropowder (SiO₂≥96 mass%, d₅₀=0.15 μm) as raw materials, and calcium lignosulfonate as the additive, batching, mixing, and molding on a vibration pressure molding machine, drying and then firing at 1 420 ℃ for 10 h in high-purity N₂. The apparent porosity, the bulk density, the cold modulus of rupture, the hot modulus of rupture, and the linear expansion coefficient of the samples were tested. The phase composition and the microstructure of the samples at different nitriding depths (50, 100, and 150 mm) were analyzed by XRD and SEM. The field application effects of the blocks were studied. The results show that: (1) the multi-phase nitrides bonded silicon carbide refractories can dynamically adjust their own phase composition and minimize structural and thermal stresses, improving the service life of key parts of dry quenching furnaces; (2) calcium lignosulfonate can improve the nitriding micro-environment of multi-phase nitrides bonded silicon carbide lintel blocks, successfully increasing the effective nitriding thickness of the blocks to 300 mm; (3) Sinosteel LIRR provides a unique concept in the design of materials and block types as well as the stable and scientific overall structure, promoting the industrialization process of dry quenching furnaces with long service life in China.

Key words: inclined channel area, dry quenching furnaces, silicon carbide, multi-phase nitrides, lintel blocks