초전도 응용기기 안정성 진단을 위한 AE센서용 압전소자의 성능개선 연구

Abstract

Acoustic emission (AE) signal from an HTS tape has a low signal to noise ratio, due to the large amount of noise caused by the boiling of the liquid cryogen or mechanical vibration from the cryo-cooler. In an attempt to improve the sensitivity of the AE sensor, Pb(Zr0.54Ti0.46)O3 + 0.2 wt% Cr2O3 + 1.0 wt.% Nb2O5 ceramics sintered at 1200°C was synthesized. In addition, the resonance (fr) and anti-resonance frequencies (fa) were measured using the specimens with various thicknesses (1.0, 1.5, 2.0, 2.5 and 3.0 mm). According to the test results, large AE signals with high frequencies were obtained from the AE sensor fabricated using a piezoelectric disc with a thinner thickness.