The fabrication of reaction-formed silicon carbide with controlled microstructure by infiltrating a pure carbon preform with molten Si

This paper describes the production of shaped silicon carbide based ceramic materials by in situ reaction of silicon with fine, ultra-uniform porous carbon skeletons that were produced from liquid polymer solutions without any particulate additions. Three typical types of carbon preforms (spherical carbon particulates, crosslinked network carbon, and lamellate carbon particulates) were infiltrated with molten Si. The morphologies and mechanical properties of corresponding reaction-formed silicon carbide (RFSC) ceramics have been investigated. The results revealed that the RFSC obtained by molten Si reaction with the porous carbon preform with discrete and spherical carbon particulates has the most uniform microstructure, the highest flexural strength (410±30 MPa) and the lowest amount of residual Si (approximately 12 wt.%). The general feature of a fracture surface showed the typically brittle failure in those materials.