Reaction synthesis of AlN-TiC ceramic and mechanism of densification

Compact AlN-TiC ceramics were fabricated by the combustion synthesis of Al particles in super-high pressure nitrogen (100 MPa). The maximal relative density of 95% could gained in the products, and maximal bending strength reached 240 MPa. In the SHS process of the Al-N₂-TiC system, when the temperature was up to 660°C, Al was melted. At high temperature of SHS reaction melting, Al spread over TiC particle surfaces, which led to liquid sinter occurrence in the SHS reaction zone. Since the liquid sinter occurrence, the porosity of reaction zone was apparently decreased. With increase of TiC content in the original powder system, the liquid sintering was strengthened, the relative density of the products was improved and the bending strength and fracture toughness were increased. In Al-N₂-TiC system, SHS-densification had the apparent tropism, which mainly occurred along the combustion front.