Effect of oxide filler on the preparation and properties of reaction bonded silicon carbide ceramics

Effect of SiO2 content and sintering process on the composition and properties of Pure Carbon Reaction Bonded Silicon Carbide (PCRBSC) ceramics prepared with C-SiO2 green body by infiltrating silicon was discussed. The infiltrating mechanism of C-SiO2 perform was also explored. The experimental results indicated that the shaping pressure could be higher with the addition of SiO2 to the perform, and pore size of the body turned finer and distributed in a narrower range, which is beneficial to decreasing the residual silicon content in the sintered materials and to avoiding shocking off, thus increasing the conversion rate of SiC.SiO2 deoxidized by carbon at high temperature and the gaseous SiO and CO produced are the main reason to the crack of the body at elevated temperature. If the green body is deposited at 1800 C in vacuum before infiltration, crack will not be produced in the perform and fully dense RBSC can be obtained. The ultimate material has the following properties: a density of 3.05-3.12g/cm(3), a strength of 580 +/- 32 MPa and a hardness of (HRA)91 similar to 92.3.