The control of mechanical strength by an electric field in ceramic composites dispersed with piezoelectric particles

The control of mechanical strength in structural ceramic composite has been proposed and demonstrated by dispersing piezoelectric particles. The change in strength of barium titanate/zirconia composite on polarization treat-ment was evaluated, and the mechanism of this phenome-non is discussed based on the previously proposed mechanism for monolithic piezoelectric ceramics. The bending strength of BT/8YSZ composite increased upon longitudinal poling and decreased upon transverse poling compared to the untreated samples. Both the strengthened and weakened specimens tended to return almost to their original strength by heating over the T _c of barium titanate. Scanning electron microscopy was then used to examine the crack propagation after the polarization treatment, and cracks going in the poling direction were found to detour around the barium titanate grains, which was attributable to the increase in strength in the poling direction.