Study On The Fabrication And Properties Of MoSi₂/SiC That By Melt Infiltration

MoSi2/SiC composite as materials that service at elevated temperature has adequate strength, good thermal compact resistance and excellent oxidation and corrosion resistance in high temperature. But its using has been limited because of the complex manufacture technology and high costing.So it will be good for expanding this composite using and have good social and commercial benefits,if wecan find out a simple technology to manufacture MoSi2/SiC composite.Reaction-bonded SiC was prepared by using melt silicon infiltrated carbon perform at 1500 C;then evaporated the resist silicon at 1800 C for 2h in vacuum and the porous body of SiC was attained.Using melting MoSi2 infiltrated SiC body at 2050 C we got the desitive MoSi2/SiC composite.The experiment result showed that ,in the infiltration melting the evaporation speed of Si is more rapid than Mo.The melting which enrich the Mo reacted with the SiC body and there existed Mo5Si3C.The content of MoSi2 can be controled by adjusting the contend of C in the perform;the content of C is more high the pore volume in composite is more high. At 1800 C heat SiC body for two hours can elimilated the SiO2 which on the SiC surface and is good for increasing the density of composite.Increasing infiltration temperature has no effect on composite's density.We also attainted MoSi2/SiC composite by using melting MoSi2 infiltrated SiC body which shaped by SiC powder.The result show that the diameters of SiC particle and shaping methods have effect on the composite's microstructure and properties.In this paper we studied the composite's mechanical properties in room temperature and oxidation resistance in different temperature. The fracture strengh at room temperature of 95.2% desity materials is lower than RBSC but higher than MoSi2;the fracture toughness at room temperature is higher than MoSi2 and reach the level of RBSC.When Oxidated at 900 C,the evaporation of MoO3,CO,CO2 destroyed the oxidation film(SiO2),the composite lost the weightbecause of the evaporation of MoO3.When oxidated at 1300 C ,densitive oxidation film coverd the surface which composed by SiO2 and Mo5Si3. At first,the composite lost the weight and then weight was increased.