Densification and mechanical properties of shock-treated alumina and its composites

The effects of shock treatment and consolidation method on densification behaviour and mechanical properties of Al₂O₃, Al₂O₃-ZrO₂, Al₂O₃-SiC (whisker), and Al₂O₃-ZrO₂-SiC (whisker) have been studied. It was established that shock treatment does not improve the sintering kinetics of alumina or alumina-based composites. On the other hand, partial shock compaction followed by sintering provided higher densities compared to sintering alone. Unshocked and pressureless sintered materials possessed better mechanical properties than shock-treated materials, in general. No significant difference was noted in the mechanical properties of hot-pressed Al₂O₃-ZrO₂ composites with regard to shock treatment. Improved mechanical properties were occasionally found in shock-treated and hot-pressed whisker-reinforced alumina, although a direct relationship with shock pressure was not observed. The improvement was attributed to decreased whisker aspect ratios upon shock treatment, leading to enhanced microstructural uniformity.