空气耦合超声换能器作为一种无损检测(NDT)的重要设备, 具有广阔应用前景, 但由于压电元件与空气声阻抗失配导致低带宽(BW)、低灵敏度(SNS)及高双程插入损耗等缺陷而阻碍其应用。该文对空气耦合超声换能器制备工艺进行优化, 使用COMSOL软件模拟了压电元件的尺寸设计。同时通过采用1-3型压电复合元件与优化环氧树脂+空心玻璃微珠匹配层调控压电元件与空气的声阻抗, 制备了工作频率400 kHz的空气耦合换能器。在工作频率时, 该换能器的厚度振动模态较纯, 带宽较宽, 灵敏度与双程插入损耗为-38 dB。结果表明, 采用该文自研工艺制备的空气耦合超声换能器具有良好的性能与巨大应用潜力。

As an important device for non-destructive testing (NDT), the air-coupled ultrasonic transducer has a broad application prospect, but duo to the low bandwidth (BW), low sensitivity (SNS, high two-way insertion loss (IL) and other defects resulted from the mismatch between piezoelectric element and air acoustic impedance, its application is limited. The preparation process of air-coupled ultrasonic transducer is optimized in this paper, and the dimension design of piezoelectric elements is simulated by using COMSOL. An air-coupled transducer with operating frequency of 400 kHz is fabricated through regulating the acoustic impedance of piezoelectric elements and air by using 1-3 piezoelectric composite elements with optimizing matching layers of epoxy resin+hollow glass beads.The transducer has a pure thickness at the operating frequency, a wide bandwidth, and sensitivity with a two-way insertion loss of -38 dB. The results show that the air-coupled ultrasonic transducer fabricated by the self-developed process has good performance and great application potential.