Ceramics-Silikáty 58 (4) 326-332(2014)

EFFECT OF SiC PARTICLE SIZE ON THE MATERIAL AND MECHANICAL PROPERTIES OF MULLITE BONDED SiC CERAMICS PROCESSED BY INFILTRATION TECHNIQUE

The influence of SiC particles size on the bonding phase content, microstructure, SiC oxidation degree, flexural strength, porosity and pore size distribution of mullitebonded porous SiC ceramics were studied and compared with oxidebonded porous SiC ceramics. The SEM morphologies and EDS elemental analysis results showed the presence of needle shaped crystals of mullite and fish scaled cristobalite in the bond phase. It was found that increase of SiC particle size effectively enhanced the porosity and decreased the strength. The porosity decreased as the size of SiC particles decreased from 36 vol. % at 99 μm to 25 vol. % at 4.47 μm. The oxidation degree of SiC was found to be reduced by infiltration of mullite precursor sol and enhanced with sintering temperature. Bimodal pore size distributions were obtained for mullite-bonded porous SiC ceramics and the average pore diameter varied in the range of 2 - 30 μm with variation of particle size.

Keywords: Particle size, Mullite bond, Infiltration, Porous SiC, Microstructure