Study on the sintering mechanism and properties of porous ceramics prepared by silicon carbide abrasive particles with multi-mineral sintering additives and silica sols

Abstract

Reducing the sintering temperature of SiC ceramics while maintaining performance has been a significant challenge. This study proposes the preparation of SiC porous ceramics at lower sintering temperatures using industrial-grade SiC abrasives, instead of expensive high purity SiC ceramic particles, as ceramic aggregates by combining two process routes, namely liquid-phase sintering and additive doping, with industrial silica sol as the liquid-phase binder and three common minerals, namely kaolin, talc, and bentonite, as sintering additives. SiC ceramic precast blanks were first prepared by a semi-solid injection moulding process. The reasonable SiC sintering temperature was determined to be 1400 °C by studying the effect of sintering temperature on the component composition and microscopic morphology of the blanks. Then, SiC porous ceramics with macroscopic and microscopic pore structures were successfully prepared using an organic foam impregnation-high temperature sintering process, in which the maximum compressive load was 210.2 N at a porosity of 72.66%. Finally, the rationality of this process route was determined, which shows that this technology can reduce the complexity and production cost with cheaper raw materials and lower sintering temperature without atmosphere protection.