Carbon atmosphere effect on Ti3SiC2 based composites made from TiC/Si powders

The effect of carbon activity and CO pressure in the furnace atmosphere is investigated with respect to the phase reactions during heat treatment of TiC/Si powders. Special attention is given to the production and decomposition of Ti3SiC2. Samples were heated in graphite and alumina furnaces, connected to a dilatometer which enabled in situ analysis of the phase reactions. The phase compositions of the heat treated samples were determined by X-ray diffraction. The reducing atmosphere of the graphite furnace enhanced the reactivity of the starting powder and enabled phase reactions to take place at a lower temperature than in the alumina furnace. TiSi2 and SiC phases formed at temperatures below the melting point of Si and were continuously consumed at higher temperatures. Ti3SiC2 formed at the melting point of Si regardless of furnace atmosphere. No decomposition of the Ti3SiC2 was observed in either furnace.