面向空耦电声换能器应用的高性能FEP/PTFE复合膜压电驻极体  

High performance laminated FEP/PTFE piezoelectret films for air-borne sound transducers

作　　者：安志鸿 黄林敏 赵锦波 胡倩倩 孙转兰[2] 郑欢 张晓青[2] An Zhi-Hong;Huang Lin-Min;Zhao Jin-Bo;Hu Qian-Qian;Sun Zhuan-Lan;Zheng Huan;Zhang Xiao-Qing(Laboratory of Low Frequency Electromagnetic Communication Technology,722 Research Institute,China State Shipbuilding Corporation Limited,Wuhan 430205,China;Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology,School of Physics Science and Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]中国船舶集团公司第七二二研究所低频电磁通信技术实验室,武汉430205 [2]同济大学物理科学与工程学院上海市特殊人工微结构材料与技术重点实验室,上海200092

出　　处：《物理学报》2022年第2期279-288,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61761136004)资助的课题。

摘　　要：压电驻极体(也称为铁电驻极体)是一类具有强压电效应的微孔结构驻极体材料,具有柔韧、低密度、低特性声阻抗等特征,是制备柔性空气耦合声电换能器的理想材料.针对器件对高灵敏度和高温工作环境的应用需求,本文报道高性能氟化乙丙烯/聚四氟乙烯(FEP/PTFE)复合膜压电驻极体的制备和性能表征.研究结果表明,FEP/PTFE膜的特性声阻抗为0.02 MRayl(1 Rayl=10 Pa·s/m);在小压强范围内的准静态压电电荷系数d_(33)可高达800 pC/N,且具有良好的压强特性.基于FEP/PTFE复合膜压电驻极体的麦克风的灵敏度最高可达6.4 mV/Pa@1 kHz,远高于文献报道的相同结构的压电驻极体麦克风的灵敏度,且具有平坦的频响曲线.对于直径为20 mm的超声波发射器,当驱动电压V_(p)为600 V时,样品中轴线上距离器件表面100 mm处,40—80 kHz频率范围内产生的超声波的声压级为80—90 dB(参考声压为20μPa).基于FEP/PTFE复合膜压电驻极体的声电换能器的热稳定性显著优于聚丙烯(PP)压电驻极体声电换能器:在125℃下老化211 h,器件的灵敏度保持初值的26%,这得益于基体材料FEP和PTFE优良的空间电荷储存稳定性.Piezoelectret(also known as ferroelectret)is a kind of cellular electret material with strong piezoelectric effect.Such a material exhibits flexibility,low density and small acoustic impedance.Therefore,piezoelectret is an ideal material for air-borne flexible sound transducers.Aiming at high-sensitivity and thermal-stability sound transducers,in this work,laminated fluorinated polyethylene propylene(FEP)and polytetrafluoroethylene(PTFE)piezoelectret film with a regular cellular microstructure is prepared by a procedure involving templatebased cellular structure formation and polarization.The results show that the characteristic acoustic impedance of such a laminated FEP/PTFE film is 0.02 MRayl.The quasi-static piezoelectric charge coefficient d_(33)up to 800 pC/N is achieved in a small applied pressure range.The maximum value of sensitivity of the microphones based on laminated FEP/PTFE piezoelectrets film can reach to 6.4 mV/Pa at 1 kHz.Besides,the frequency response curve of the device is flat in the whole audio range.For an ultrasonic transmitter with a diameter of 20 mm,driven by a voltage of 600 V(V_(p)),the sound pressure level(SPL)generated by it increases from 80 to 90 dB(Ref.20μPA)as frequency increases from 40 to 80 kHz.The thermal stability of the sensitivity for the transducers made of such a laminated FEP/PTFE piezoelectret film is much superior to that of polypropylene(PP)piezoelectret based device.The sensitivity of the present device remains 26%of the initial value after being annealed at 125℃for 211 h.The improvement of thermal stability is attributed to the excellent space charge storage stability of FEP and PTFE.

关 键 词：压电驻极体 氟化乙丙烯/聚四氟乙烯复合膜 声电换能器 空气耦合 

分 类 号：TQ317[化学工程—高聚物工业] TP212[自动化与计算机技术—检测技术与自动化装置]