Effects of andalusite aggregate pre-fired at different temperatures on volume stability and oxidation resistance of Al2O3-SiC-C castables

摘要

In the present work, the effects of the pre-firing temperature of andalusite aggregates (5-3 mm) on the conversion of andalusite as well as the volume stability and oxidation resistance of the Al2O3-SiC-C castables were investigated. The phases of the andalusite aggregates were tested via X-ray diffraction, and their microstructures as well as those of the castables were characterized via scanning electron microscopy. The linear expansion of the castables decreased with increase in the pre-firing temperature of andalusite, as less residual andalusite in the pre-fired aggregates lowered its transformation in the castables during firing at high temperatures. Moreover, the higher amounts of SiO2-rich glass produced by andalusite pre-fired at high temperatures and secondary mullite generated between andalusite and the matrixes were both favorable to the production of castables with denser structure. This prevented the diffusion of O-2 into the castables and improved their oxidation resistance.