Development of porous reaction-bonded silicon carbide at low sintering temperature

Abstract

Mullite-bonded porous silicon carbide samples were produced by the reaction sintering in air from silicon carbide (SiC), alumina (Al203), and using graphite as the pore former. The sintering process was based on the oxidation of SiC and the mullitization between Al203 and oxidation derived Cristobalite (Si02). At mullitization temperature (1450 ??C), SiC particles were bonded by the mullite (3Al203.2Si02) and Si02. Sintered samples will be characterized by density determination and three-point bend tests. Morphology and microstructure analysis study will be done by Scanning Electron Microscopy (SEM), while the phase composition will be investigated by X-Ray Diffraction (XRD). Mullite phase transformation start at 1450??C which was the optimum sintering temperature for mullite transformation. Mullite contents increase v4ith sintering temperature concurrent with decrease of Al203. Porous SIC ceramics were bonded by the mullite and oxidation-derived Si02. The density was increase while the open porosity was decreases with increasing of sintering temperature. Flexural strength was direct proportion to the sintering temperature but inverse proportional to the percentage of open porosity. Highest content of mullite and mechanical properties achieved at 1500??C.