金属基圧電複合材料における圧電セラミックスの強度向上

抄録

Piezoelectric ceramics are widely used as sensors and actuators because of their excellent mechanical-electrical energy conversion efficiency. However, piezoelectric ceramics is brittle materials, and its fracture strain is as low as 0.1%, therefore, it is not suitable for applications where high mechanical loads occur. In order to overcome this problem, metal matrix piezoelectric composite was developed in which piezoelectric ceramics was embedded in a metal which have excellent strength and reliability. In the embedding of ceramics in the metal, a significant improvement in mechanical properties is expected due to the compressive stress resulting from the difference in thermal expansion coefficient between the ceramics and metal. However, the improvement of mechanical properties by embedding in metal matrix has not been evaluated quantitatively. Therefore, in this study, the strength improvement by embedding in metal matrix was evaluated by comparing the three-point bending strength before and after embedding of piezoelectric ceramics. The strength of the piezoelectric ceramics when embedded was not directly calculated from the load obtained by the three-point bending test, so it was calculated using the stress concentration factor obtained by finite element analysis. In addition, acoustic emission sensor was used to confirm the occurrence of ceramic fracture in the metal matrix. As a result, it was found that the strength of the embedded piezoelectric ceramics was about 1.6 times that before the embedding in metal matrix.