Fabrication and Characterization of Lead-Free Functionally Graded Piezocomposites

摘要

As the development of Internet of Things (IoT), the power supply to the sensors in IoT becomes more and more important. The piezoelectric material was widely studied as a material for energy harvesting devices. Our target is to design and fabricate a flexible, eco-friendly and light functionally graded piezocomposite for energy harvesting devices by polyvinylidene fluoride (PVDF) and lead-free piezoelectric particles. Two kinds of lead-free piezoelectric particles -barium titanate (BTO) and potassium sodium niobite (KNN) are used in the study. And the addition of the PVDF can greatly improve the toughness of the material and broaden the applications of the material. In this study, the multi-layer lead-free piezoelectric particle/PVDF composites with different contents of lead-free piezoelectric particles and structure are fabricated by spin coating and hot press method. The suitable parameters of the spin coating and hot press are found. The composites are polarized by corona poling method and optimal poling conditions of the composites are also studied. Scanning electron microscopic (SEM) observations are conducted to study the distribution of the particles in the matrix and the interface between the different layers. Then, the piezoelectric coefficient d_(33) is measured by a piezo-d_(33) meter. This study gives a workable fabrication method to the functionally graded piezocomposites and explores the piezoelectric properties of the composites which have potential to be used as energy harvesting device materials.