China's Refractories

Abstract: In this study, raw silica was replaced by the silica pre-calcined at two different temperatures: 1 100 ℃ and 1 300 ℃ to prepare self-flow silica castables. The properties of the synthesized castables adopting different kinds of silica were compared. The results show that: (1) the silica become loose after pre-calcination at 1 100 ℃ for 5 h or at 1 300 ℃ for 5 h; metastable cristobalite and glass phase are found in the silica pre-calcined at 1 300 ℃ for 5 h, which have a promoting effect on sintering; (2) with the increase of the pre-calcining temperature as well as the replacement of pre-calcined silica, the linear change rate decreases, the apparent porosity and bulk density change mildly, and flexural strength and compressive strength are enhanced; for the refractoriness under load, the increasing pre-calcining temperature has promotion effect but the replacing amount has very mild influence.

Key words: pre-calcined silica, expansion, tridymite, physical performance