Sintering of MoSi2 by reacting (Mo+Si3N4) compacts

The possibility of formation of dense MoSi2 has been studied by reacting Mo and Si3N4. Powder mixtures of Mo and Si3N4 were taken in a molar ratio (Mo:Si3N4=1:1 or 3:2), according to the following reactions: (Mo+Si3N4→MoSi2+1/3Si3N4+4/3N2 or 3Mo+2Si3N4→3MoSi2+4N2). The cold pressed compacts were reacted at different temperatures (1400, 1453 and 1480 °C) in carbon resistance furnace and under nitrogen. MoSi2 was the major phase after reaction at all temperatures. In Mo+Si3N4 compact, MoSi2–Si3N4 composite was formed at 1400 °C. The excess Si3N4 was decomposed and formed elemental Si after reaction at 1453 and 1480 °C. In (3Mo+2Si3N4) system as there was no excess Si3N4, lower silicides of Mo, i.e. Mo5Si3 and Mo3Si were formed at all temperatures. Neither Si nor SiC was formed in the 3Mo+2Si3N4 system.