Photo-Acoustic Spectroscopy (PAS) and Acoustic Emission (AE) to Evaluate the Degradation of Coated Steels

光声（PA），声发射（AE），和涂层钢的界面张力独立测量，以评估涂层膜的降解。当光束指向水泡和/或分层区域时，由斩波激光诱导的PA信号降低。因此，通过扫描激光方法进行二维退化检测。由于金属和薄膜之间的键断裂，在降解的最初阶段就观察到AE信号。降解过程中的AE事件的速率被认为是涂层抗分层性的可靠度量。声发射频谱分析揭示了降解和析氢引起的声发射信号的差异。界面阻抗的Bode图上的断点频率与降解区域非常一致。研究表明，这些方法应结合起来，建立一个新的评价技术。

Photo-acoustics (PA), acoustic emission (AE), and interfacial pedance of coated steels were independently measured to evaluate the degradation of coating films. The PA signals induced by chopped LASER light decreased when the light beam pointed the blisters and/or delaminated area. So, a two-dimensional detection of degradation was performed by the scanning LASER method. Due to bradk out of bonds between the metal and films, AE signals were observed at the very initial stage of degradation. The rate of AE ements during degradation was found as a reliable measure for the delamination resistivity of coatings. Spectrum analysis of AE revealed differences of AE signals caused by the degradation and a hydrogen evolution. The break point frequency on a Bode diagram of the interfacial impedance corresponded very well to the area of the degradation. The study showed that these methods should be combined to establish a new evaluation technique.