Fabrication and properties of 2–2 multi-element piezoelectric composite

A 2–2 type multi-element piezoelectric composite was fabricated using PZT-5 as functional part, silicon gel and polyurethane as decoupling material to ensure the independence of transmitted acoustic beam and strengthen the signal power. The effects of composite thickness and decoupling material on dielectric, piezoelectric and electromechanical coupling properties were investigated. The results show that the piezoelectric, dielectric and the electromechanical coupling properties of each piezoelectric element in the composite exhibit excellent consistency. The relative permittivity of epoxy/silica piezoelectric composites(ESP) is higher than that of epoxy resin piezoelectric composites(ERP) and epoxy/polyurethane piezoelectric composites(EPP) at the same thickness, and EPP has the lowest permittivity. Multi-element piezoelectric composites can significantly improve the thickness electromechanical coupling coefficient (Kt and reduce the mechanical quality factor(Qm), in which Kt value of EPP is up to 65.19%. With increasing the composite thickness, the Qm value of the composites slightly decreases.