压电陶瓷颗粒对结构陶瓷力学行为的影响规律及机理

Piezoelectric ceramics possess piezoelectric effect due to their intrinsic domain structures. An attention has been given in this work to the effect of piezoelectric particles on structural ceramics and the mechanisms. After optimizing the components and fabrication processes of composite, LiTaO3p/Al2O3 (denoted as LTA) ceramic composite was hot pressed. It was found that the highest values reached 492.9MPa and 5.3MPa·m1/2, respectively, for the composite containing 15vol% LiTaO3p, which were 1.14 and 1.20 times of that of dense pure Al2O3 ceramic hot pressed at 1500℃. TEM observation revealed 90° domain structures were mainly formed in LiTaO3 grains in LTA ceramic composite due to mechanical restriction, which is impossible in LiTaO3 single crystal. This is a new discovery for hexagonal LiTaO3. Besides most banded 90° domains, a few of wedge shaped 90° domains and meandering 180° domains were also observed in LTA ceramic composite hot pressed at 1300℃/25MPa. The main toughening mechanisms in LTA ceramic composite include crack deflection toughening, crack branching toughening and domain switching toughening. Domain switching is suggested as a new toughening mechanism in structural matrix ceramics. Polarization treatment changed the mechanical properties and toughening mechanisms of LTA ceramic composite. Crack deflection and branching toughening induced by domains was weakened slightly. Crack detour toughening caused by the stress changes around LiTaO3p due to residual polarization took into effect.

本项目找到一条新的韧化结构陶瓷出现的有效途径或者赋予结构陶瓷以特殊性质，有利于促进结构陶瓷与功能陶瓷两子学科之间的交融，丰富发展陶瓷材料学科的理论体系。