Improving mullite-silicon carbide refractory in coke dry quenching using aluminum nitride whiskers formed in situ

The formation conditions and their influence on the properties of mullite-SiC refractory were studied by adding metallic Al powder to the raw materials to form AIN whiskers in a coke dry quenching furnace. The results show that the AIN whiskers were formed in situ and interacted to form networks in the matrix when the metallic Al powder was added into the mullite-SiC refractory after heat treatment above 850 degrees C for 8 h under nitrogen flow. The whiskers grew lengthwise as the firing temperature increased and the cold modulus of rupture, cold crushing strength, and hot modulus of rupture increased. The amount and particle size of the metallic Al powder also affected the properties of the refractory. The optimum amount of Al powder addition was determined to be 6 wt %, which provided the highest strength and excellent toughness after heat treatment at 1000 degrees C for 8 h under nitrogen. Reducing the particle size of the metallic Al powder could promote formation of the AlN whiskers and improve the strength of the refractory.