This paper reports the effect of sintering processes and additives on the microstructures and mechanical properties of -SiC composite ceramics. We fabricated sintered bodies of -20 vol.% SiC with or without sintering additive, such as C or , densified by spark plasma sintering as well as hot pressing. While almost full densification was achieved regardless of sintering processes or sintering additives, significant grain growth was observed in the case of spark plasma sintering, especially with . With sintered bodies, mechanical properties, such as flexural strength and Vickers hardness, were also examined.

based composites are candidate materials for ultra-high temperature materials (UHTMs). has become an indispensable ingredient in UHTMs, due to its high melting temperature, relatively low density, and excellent resistance to thermal shock or oxidation. powders are usually synthesized by solid state reactions such as carbothermal, borothermal, or combined carbothermal reaction. SiC is added to this system in order to enhance the oxidation resistance of . In this study, ?based composites were successfully synthesized and densified through two different processing paths. or 25 vol.%SiC was fully synthesized from oxide starting materials with reducing agents after heat treatment at 1400. Besides, ?20 vol.%SiC was fully densified with as a sintering additive after hot pressing at 1900. The synthesis mechanism and the effect of sintering additives on densification of ?SiC composites were also discussed.

Ti(C,N) solid solutions in hot-pressed Ti() (x=0.0, 0.3, 0.5, 0.7, 1.0) and 40TiC-40TiN-20Ni (in wt.%) cermet were characterized in this study. For hot-pressed Ti(C,N)s, the lattice parameters and hardness values of Ti(C,N) were determined by using XRD (X-Ray Diffraction) and nanoindentation. The properties of hot-pressed Ti(C,N) samples changed linearly with their carbon or nitrogen contents. For the TiC-TiN-Ni cermet, the hardness of the hard phase and binder phase were determined by nanoindentation in conjunction with microstructural observation. The measured hardness values were GPa for the binder phase and GPa for the hard phase, which was close to the hardness of hot-pressed Ti().