材料表面缺陷检测用空气耦合超声换能器的研制  

Development of air-coupled ultrasonic transducer for material surface defect detection

作　　者：张浩 赵旭 曾涛[1] ZHANG Hao;ZHAO Xu;ZENG Tao(Shanghai Key Laboratory of Engineering Materials Application and Evaluation,Shanghai Research Institute of Materials,Shanghai 200437,China)

机构地区：[1]上海材料研究所上海市工程材料应用与评价重点实验室,上海200437

出　　处：《无损检测》2022年第1期60-62,共3页Nondestructive Testing

基　　金：上海材料研究所技术创新项目(21181302)。

摘　　要：为解决在材料表面缺陷检测用空气耦合超声换能器的研制中,压电陶瓷材料与空气之间存在的巨大阻抗失配问题,将空心玻璃微珠和环氧树脂进行复合,制备出密度为550 kg·m^(-3),声速为2 300 m·s^(-1),声阻抗为1.3 MRayl,声衰减系数(2.25 MHz下)为344 dB·m^(-1)的低声阻抗、低衰减的匹配层材料,并采用1/4波长匹配原理进行换能器设计。在此基础上制作空气耦合超声换能器,对其进行导纳谱测试和回波信号测试分析。结果表明,研制出的空气耦合超声换能器中心频率为204 kHz,-6 dB相对带宽为21.0%,具有较好的灵敏度和带宽。In order to solve the huge impedance mismatch problem between the piezoelectric ceramic material and the air in the development of air-coupled ultrasonic transducer for material surface defect detection, this paper selected hollow glass beads and epoxy resin for compounding. A type of low acoustic impedance and low attenuation matching layer material with its density of 550 kg·m^(-3), sound velocity of 2 300 m·s^(-1), acoustic impedance of 1.3 MRayl, and acoustic attenuation coefficient of 344 dB·m^(-1)at 2.25 MHz was prepared, and the quarter-wavelength matching principle was used for transducer design. On this basis, an air-coupled ultrasonic transducer was fabricated, and the admittance spectrum test and echo signal test analysis were performed on it. The results show that so developed air-coupled transducer has a center frequency of 204 kHz and relative bandwidth of-6 dB is 21.0% with better sensitivity and bandwidth.

关 键 词：空气耦合超声换能器 阻抗匹配 空心玻璃微珠 环氧树脂 

分 类 号：TB552[理学—物理] TG115.28[理学—声学]