Study On PVDF Based Magnetoelectric Composite And Its Modification Mechanism

Magnetoelectric composite materials is widely used in the microwave field, current measurement of high voltage transmission lines, wide range of magnetic detection, magnetic field sensor, transducer for their magnetoelectricity conversion function, which has become a hot spot in ferroelectric and ferromagnetic material field research recently. In this paper, poly vinylidene fluoride PVDF based magnetoelectric composite material was chosen as the research object, by improving microstructure and using magnetic field to control structure to improve the material magnetoelectricity conversion performance, which provides the theoretical basis and practical reference to improve the performance of magnetoelectric composite material.This paper studied the relationship between the content of each phase in poly vinylidene fluoride PVDF, lead zirconate titanate PZT, rare earth alloy Terfenol-D(TD) three-phase particles of magnetoelectric composite material with the material properties. Considering the flexibility of the materials and electrical performance, when PVDF and PZT volume ratio is 3:7, the comprehensive performance of materials is the best. On this basis, by change in magnetostrictive TD content, the experimental results show that the material of the magnetoelectric transformation performance with the increase of TD levels first increases then decreases, this is caused by low TD magnetic to poor scalability, and high TD results in the decrease of piezoelectric properties caused by leakage, when the TD levels is 7vol%, material magnetoelectricity conversion performance reaches the maximum about 58 mV·cm-1·Oe-1.In terms of magnetic field control microstructure of magnetoelectric composite, PVDF/PZT/TD particles magnetoelectric composite materials wered prepared by solution mixing and hot press molding method with applying different induced magnetic field in the process of hot press molding. By analysing the magnetoelectric composite piezoelectric constant, dielectric constant and coefficient of magnetoelectricity conversion performance, the influence of induced magnetic field on the electric performances of magnetoelectric composite materials were explored.The experimental results showed that the magnetoelectricity magnetoelectricity conversion coefficient of material first increased with the increase of the induced magnetic field and then decreased, this is because can improve the magnetostrictive of magnetoelectric composites, and large induced magnetic field may reduce the coupling of different functional phases. magnetoelectric coefficient of thecomposite reach the maximum 82.5m V·cm-1·Oe-1 when the induced magnetic field is 200 Oe and the resonance frequency is 86 k Hz, 0-3 particles magnetoelectric composite materials could be improved by more than 40%. In the aspect of structure improvement, in order to overcome the low TD content in magnetoelectric composite, the sandwich structure of layered magnetoelectric composite materials is prepared. According to theoretical analysis, the PVDF+PZT chosen as an piezoelectric layer, and the PVDF + TD layers on both sides were chosen as magnetostrictive layer; In order to get the best laminated magnetoelectric composite materials, the influence of different layer thickness ratio on the material properties was studied, the results showed that when the PVDF+ TD, PVDF+PZT, PVDF+ TD layer thickness ratio was 1:1.5:1, the magnetoelectric properties of laminated materials reached a maximum of 2576.2 m V·cm-1·Oe-1, which increased by about 30 times than 0-3 particles magnetoelectric composites. 0-3 PVDF-based magnetoelectric composite materials have obvious advantages in flexibility, aging resistance, corrosion resistance, high frequency performance and anti vortex ability, but its low magnetoelectric properties restrict the further application of this kind of material. Magnetoelectric properties of induced magnetic field on the magnetoelectric composite material has the lifting function better, structure model of magnetoelectric composite materials have great influence on the magnetoelectric properties, By using the method of micro structure of magnetic field and structure improvement is beneficial to promote the practical application of flexible magnetoelectric composite materials.