COLLOIDAL PROCESSING OF SIC WHISKER COMPOSITES

In the present study, the dispersion processing and the characterizati on of the dispersity of SIC whiskers for reinforced ceramic-based comp osites were studied. Two kinds of methods were used to determine the d ispersity of SiC whiskers. First, the sedimentation density was employ ed to directly characterize the dispersity of the SLC whiskers. The ot her is an indirect characterization. The dispersity and the distributi on of the SiC whisker in a ceramic matrix were analyzed and characteri zed indirectly with SEM observation and the determination of the relat ive density. By means of the colloidal processing of the whiskers in w hich electrostatic and steric interaction were used to counteract the attractive forces between whiskers, four dispersion processing routes were used to mix the SiC whisker into the Al2O3 powder. The sedimentat ion results indicated that, with aluminum alkoxide as a dispersant, SL C whiskers were completely deflocculated and the sedimentation density increased twofold from 8.5% to 24% of theoretical density, and both t he homogeneous distribution of SIC whiskers and densification of the 3 0 vol% SIC whisker-reinforced Al2O3 (AS) were achieved by hot pressing . The relative density of the AS composites was more than 99.7%, SEM o bservation showed no agglomeration of SLC whiskers.