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.