The effect of sintering temperature on the mechanism of metal composite and self toughing and toughening Si_3N_4 ceramics coupling

摘要

Fe-Mo/Si_3N_4 cermet powers are prepared by heterogeneous precipitation-thermal reduction process and sintered on normal pressure with Y_2O_3-MgO additives. The effect of sintering temperature on the phase composition, microstructure and mechanical properties are discussed. Result of study indicates: the rise of sintering temperature is beneficial to retention the metal phase and the generation of β-Si_3N_4 whisker. At the temperature of 1650°C, Y-Mg-Si-O-N glass phase is generated, At the temperature of 1700°C, whiskers-like β-Si_3N_4, good wettability phases on Si_3N_4 surface, and high toughness Fe phase appeared in Fe-Mo/Si_3N_4 cermets. It can effectively better the microstructures of Fe-Mo/Si_3N_4 cermets, and contribute to improve the material mechanical perperties. When the temperature rise to 1750°C, the maximum particle MoSi_2 can destroy the microscopic structure, and decreases the density and mechanical properties of ceramics fast. The optimum sintering temperature is therefore about 1700°C.