Production of silicon carbide pieces by immersion of silicon preforms in carbonaceous powders

In this work a novel method for production of silicon carbide (SiC) pieces, which involves the heating of silicon (Si) preforms immersed in graphite powder is presented. Such preforms were obtained via low-pressure injection molding (LPIM), although any other conformation route can be used. The process can be carried out at modest temperatures and gradients in standard furnaces used for processing other ceramics. These features make this process a simpler and cheaper alternative, when compared with other methods of SiC fabrication. The variables affecting the process have been identified, and an optimum-heating ramp has been established. Under these conditions, the obtained SiC products show no remnant-free Si, and their mechanical behavior allows their use in several less-demanding SiC applications, for which expensive high-performance SiC products are unaffordable. In the proposed chain of reactions, CO(g) is responsible for the carburization of the pieces. All phases present are identified, and their distribution is explained by means of competitive reactions. In our opinion, this novel method can be extended to an industrial scale because it is simple and involves cheap raw materials.