Abstract
It has been shown in our previous work that the 28 GHz microwave sintering process can improve the performances of piezoelectric actuators. The improved performances include larger output force, higher strength and a larger electromechanical coupling factor. The improvement in performances is attributed to the repression of grain growth due to rapid heating and improvement of the microstructure because of internal heating. The sintering time was reduced to 1/10 the time needed for the conventional technology due to the larger power and uniform heating in the microwave sintering process. In this study, the microwave sintering process was combined with the hot-press sintering process for further improvement of the performances of lead zirconate titanate (PZT) actuators and the sintering conditions of the hybrid process were investigated. It was confirmed that the combination of microwave and hot-press sintering processes can improve the performances of sintered PZT. In particular, it was found that the piezoelectric constant d31 could be improved by as much as 30%.