Combustion synthesis of Ti 3 SiC 2 was carried out in air with Si 3 N 4 , SiC, and Si as Si sources respectively, and the effect of Si source on the phase composition of the products was investigated. With Si 3 N 4 as Si source, the major product was TiC x N 12x and no Ti 3 SiC 2 was synthesised. When SiC and Si were used, Ti 3 SiC 2 was synthesised. Such effect of Si source is thought to be connected with the formation mechanism of Ti 3 SiC 2 , where the presence of a Ti-Si melt is required. The combustion synthesis was also performed under high gravity condition instead of common gravity. The apparent density of the product prepared under high gravity was y60% higher than that obtained under normal gravity. It is proposed that, the high gravity can facilitate the permeation of Ti-Si melt and enlarge the interface between the melt and carbide phases, which is helpful for the formation of Ti 3 SiC 2 .
Combustion synthesis of Ti 2 AlN was carried out in air and pressurised N 2 respectively. The reaction atmosphere had an evident effect on the phase composition and microstructure of the products. By combustion synthesis in 2 MPa N 2 , Ti 2 AlN was synthesised as the major product, but in the samples prepared in air, Ti 2 AlN was obtained only as a minor phase, and the predominant phases were Ti-Al intermetallics. The reaction mechanism has been studied, suggesting that TiN is a key intermediate in the formation of Ti 2 AlN. It is proposed that, in the combustion synthesis of Ti 2 AlN, the flux of N 2 plays an important role in determining both reaction kinetics and phase composition of the products.
Three systems of glass ceramics with different chemical compositions were prepared by high gravity combustion synthesis. Most samples were dense with a low porosity, which can be attributed to accelerated separation and removal of gas bubbles from ceramic melts in a high gravity field. The hardness of the as prepared glass ceramics varied in the range of 8?2-12?8 GPa and could be improved by a fine eutectic structure. Compared with conventional techniques, high gravity combustion synthesis can offer a fast and efficient way to prepare glass ceramic materials.
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