Silicon carbide, SiC, is a versatile ceramic with many high-performance applications. SiC is the most used non-oxide ceramic in the world with notable properties being the strength and hardness, even at elevated temperatures; oxidation resistance; abrasion resistance; low neutron absorption; reflectance; wide bandgap and thermal conductivity. SiC is difficult to fabricate, but the obstacles can be mitigated with sintering additives. The selection and processing of additives to facilitate the densification of a ceramic is an important aspect of grain boundary engineering.
The additives enhance densification, lower the sintering temperature or time, enable fabrication techniques, or improve the properties of SiC. Misused additives can have the opposite effect, especially a reduction in properties. A purpose of this study is to review the many sintering additives that have been investigated to densify sintered SiC. The role of additive chemistry and amount on densification and mechanical properties of SiC are examined and their implications in fabricating SiC shapes by powder injection molding are examined using examples from our recent experiments. The variations in densification, microstructure and properties as a result of nanoscale additives are presented and discussed.