Preparation of SiC porous ceramics by a novel gelcasting method assisted with surface modification

The SiC porous ceramics were successfully prepared by gelcasting process using Isobam as gelling agent. The pretreatment and surface modification of SiC was proposed to solve the problem that Isobam is difficult to crosslink and gelling with non-oxide ceramics. The SiC powder was firstly pre-oxidized, and then modified with a silane coupling agent to obtain a functional end group -NH2 on the surface, so that it can be crosslinked with Isobam to obtain a green body with uniform structure. With low amount of organic matter, no additional de-binding procedure was required before sintering. The suitable oxide thickness was investigated, which shows a linear relationship with the original SiC particle size. Moreover, the solid content of the slurry was adjustable between 40 vol% and 52 vol%, and the porosity of the products varied between 50% and 60% after sintering.