Evaluation of Corrosion Detection Performance of Directly Mounted Sol-Gel Composite Piezoelectric Ultrasonic Transducer

Corrosion monitoring of piping is an important initiative to ensure the efficiency and safety of production processes. Several studies have been reported on corrosion monitoring with ultrasound non-destructive testing, especially in high temperature environments. One challenge in ultrasound NDT in high temperature environments is the couplant which does not commonly have heat resistance. We have proposed a directly mounted type ultrasonic transducer that does not need any couplant. In this paper, high temperature corrosion detection performance is reported. The transducers for the evaluation were piezoelectric devices and were prepared by the sol-gel composite automatic spray method. As the sol-gel composite, BiT/TiO
2
(bismuth titanate piezoelectric ceramic powder(BiT) / titanium oxide(TiO
2
) sol-gel solution) was used. With the BiT/TiO
2
transducer, the high temperature corrosion test was conducted by calcined ash. To detect corrosion, the pulse-echo test was conducted. As a result, the thickness decreased could be calculated. Compared with the cross-sectional image of the corroded area of the substrate, the acquired thickness by the transducer made with the proposed method was reasonable.