Novel piezoelectric ceramic/polymer composite transducers

The design, processing conditions and electromechanical characterization of novel piezoelectric ceramic/polymer composites with 2-2 and 3-3 connectivity is presented. The ceramic structures made of PZT were prepared by Layered Manufacturing, namely by Fused Deposition of Ceramics (FDC) process. The ceramic phase in the form of fibers or sheets was oriented at different orientation angles theta with respect to the x(3) axis of the sample, which varied between 0degrees and 75degrees, in 15degrees increments. The sintered structures were placed in Spurr Epoxy polymer and diced in 2mm. thickness. The electromechanical and elastic properties were investigated as a function of orientation angle theta. The longitudinal piezoelectric charge coefficient showed a decrease in the property as the theta increases. It was found that as the orientation angle theta was increased, the transverse piezoelectric charge coefficient d(31) changed its sign from a negative to a positive value at theta=37.5degrees reaching a maximum value at 45degrees for both types of composites. Due to the contribution of a positive d(31) coefficient, a significant increase in the hydrostatic charge coefficient was observed.