Effect of SiC whiskers on properties of porous silicon carbide ceramic

Abstract

The porous SiC ceramics reinforced by silicon carbide whisker were produced by mixing SiC whisker with core–shell structure powder precursor. The surface morphology, phase composition, porosity, mechanical and thermal properties of the products were analysed. The morphology images show that small part of the SiC whiskers are inserted in the holes of SiC matrix, and most of the SiC whiskers are well dispersed in the matrix. The X-ray diffraction (XRD) pattern indicates that the crystalline phase of porous SiC ceramics reinforced by SiC whisker is pure β-SiC. The bending strength of porous SiC ceramics is strengthened by SiC whisker through the reinforcement mechanisms of whisker bridging, crack deflection and pulling-out whisker effect. The influence of addition proportion of SiC whisker on the bending strength was studied. Along with increasing SiC whisker additive, the bending strength of the porous ceramics performs an increasing trend. When the percentage of SiC whisker in the SiC ceramics increases to 15%, the bending strength of the ceramic runs up to 2·4 times of the SiC ceramic without addition of SiC whisker. Thermal shock resistance tests reveal that the composite has both good bending strength and good high temperature performance, which are very meaningful for the application of composite ceramics in the high temperature fluid filtration field.