Improved resistance to damage of silicon carbide-whisker-reinforced silicon nitride-matrix composites by whisker-oriented alignment

The effects of whisker-oriented alignment on resistance to damage of SiC(w) /Si3N4 composites have been investigated by the Vickers indentation method and R-curve behavior. It is shown that increasing the degree of whisker-ori ented alignment decreases the lengths of Vickers Impressions and indentatio n cracks. The results exhibit rising R-curve behaviors for the SiC(w)/Si3N4 composites with different degree of whisker-oriented alignment. Moreover, the initial crack length c(i), the threshold of crack growth resistance K-i , and the upper bound of crack growth resistance K-infinity change regularl y with increasing degree of whisker-oriented alignment. All results suggest that the whisker-oriented alignment improves the resistance to damage of t he composites, resulting in a more reliable and usable composite.