The Preparation And Performance Of The Piezoelectric Composite With Spiral Structure

Piezoelectric composite material with good flexibility is widely used inunderwater acoustic sensing and medical testing and other areas due to combiningproperties of piezoelectric ceramic and polymer. In this paper, a novel spiralpiezoelectric composite PZN-PLZT/epoxy is fabricated by the roll forming-curlingmethod, overcoming a series of difficult challenges such as the low volume fraction ofthe piezoelectric composite molding, and which simplifies the preparation process andaccesses to a high-performance piezoelectric composite materials. Based on thecurrent situation of piezoelectric composites and the particular sound of waterapplication, A systematic study of Impact factor for properties of piezoelectriccomposites is made, such as the molding method, sintering and sintering system, thepolarization process, the electrode material, surface treatment, the polymermatrix,piezoelectric ceramic phase volume fraction,the ratio of width to thicknesslw/lt of the piezoelectric ceramic ring and so on. Eventually, to the optimal processparameters is obtained and the optimum volume fraction of piezoelectric ceramics andthe ratio of width to thickness lw/lt of the piezoelectric ceramic ring is determined.The results show that, rolling the film-a single curl forming method is suitablefor ceramic phase volume fraction greater than50%of the piezoelectric composites.Rolling film-more forming method is suitable for ceramic volume fraction of lessthan50%of the piezoelectric composite,and the rolling film-cut type manner issuitable for the piezoelectric composite samples with different thickness and samecurl patterns. The optimum process parameters is finally determined that thepolarization electric field strength is2.5Kv/mm, the polarization time is20min, thepolarization temperature is90℃, the sintering temperature is1220℃when samplesare buried by Al2O3. At this time,the composite is found to yield optimum figure ofmerit(FOM) value of77.1×10-12m2/N with a11%volume fraction, and theelectromechanical coupling coefficient of the composite is up to0.89when the thevolume fraction of the ceramic phase is25%. Acoustic impedance and the dielectricconstant of the composite material is substantially free from the effect of the ratio ofwidth to thickness lw/lt of the piezoelectric ceramic ring. However, the thicknesselectromechanical coupling coefficient decreases rapidly when the he ratio of width tothickness lw/lt of the piezoelectric ceramic ring increases. What’s more, thehydrostatic figure of merit had an expDec1correlation(y0+A1e(-x/t1)) with the ratio of width to thickness lw/lt of the ceramic ring.The correlation coefficient, R2, waslarger than0.93, and the related error,(1-R2), was less than7%. Meanwhileexperimental results show that the interface combine strongly after silane couplingagent KH570treated,and the breakdown field strength is up to3.8Kv/mm.For theelectrode material the piezoelectric and dielectric properties of the samples coated bycarbon black conductive adhesive is relatively good, but Considering thatpolarization of silver conductive adhesive samples ia easy and the hydroacousticperformance is excellent, so silver conductive adhesive is appropriate.Experimentalresults also show that the softer the polymer, the smaller the elastic modulus and thePoisson, the more excellent performance of the piezoelectric composites.