Study On Preparation Of High-Strength SiC_W/SiC Composites By Reasction Bonded Method

SiC whisker is incorporated in the raw material of reaction bonded silicon carbide (RBSC) to prepare SiCw/SiC composites. The effect of fabrication process on the microstructure and the properties of the sintered body are investigated in this paper.Based on the research results on the sinter process, it is concluded that the SiC whisker solve rapidly even at 1450℃. So the sinter temperature of the material are controlled to under 1450℃, the sintered time under 5min. Sintered material has a density of 2.78g/cm3, a bending strength of 287MPa and fracture toughness of 5.5MPa .m1/2.The effect of SiO2 on the infiltration of the liquid Si into the SiCw/C preform is also discussed in the paper. With the comparison between the sinter densities of different carbon density body under high temperature, it is concluded that the incorporation of the SiC whisker has a good effect on the infiltration process. The gas produced in the sintered process can easily give off through the pore microstructure of SiCw/C preform.It is investigated in the paper the correlation between the microstructure and the mechanical properties, that is, the effect of the content of free carbon, free silicon, pore and granule size on the bending strength of the material. Under 1800℃,we obtain material with a density of 3.12 g/cm3, bending strength of 522MPa. It is considered that the increase of the bending strength of the material obtained upon the traditional RBSC material by 50% is mainly owing to a higher density and a lower porosity than the RBSC material.