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接触法和水浸法垂直入射纵波探伤中,可能获得的探伤灵敏度除主要决定于探头(换能器)和探伤仪的组合灵敏度外,还与探头与负载介质之间的声学阻抗匹配有关。一般用压电陶瓷作的探头上,为了防止晶片磨损,常加上钢、塑料、陶瓷或其它材料作成的保护膜。实际上,保护膜不但起着保护压电陶瓷片的作用,它还在晶片与负载介质之间起着匹配层的作
In contact and immersion vertical incidence P-wave flaw detection, the detection sensitivity that may be obtained depends not only on the combined sensitivity of the probe (transducer) and the flaw detector but also on the acoustic impedance matching between the probe and the load medium. The general piezoelectric ceramic probe, in order to prevent wafer wear, often with steel, plastic, ceramic or other materials made of protective film. In fact, the protective film not only plays a role in protecting the piezoelectric ceramic sheet, it also plays a matching layer between the wafer and the supporting medium