Research on Localized Corrosion Monitoring of Cu Substrate Based on Discrete Fiber Optic Sensors

The presence of corrosion on metal substrates can compromise the integrity of a structure. In this study, discrete fiber Bragg grating (FBG) sensing technology is used to monitor the corrosion process of a Cu surface in a corrosive environment. The surface morphology and nanostructures of corrosion products are observed to reveal their forms or structures. The results show that corrosion products are composed of loose or dense collections of micrometer/nanometer-sized particles in a crystalline state. Furthermore, this study experimentally explores how localized corrosion affects the sensing signal between an optical fiber and a corroded copper substrate. This phenomenon is also theoretically modeled using contact mechanics, enabling a semi-quantitative calculation of how corrosive particles influence Bragg wavelength. The wavelength shift trends of the four monitoring points over a period of 10 days were similar under the same corrosive environment. Results show that fiber Bragg grating sensors can identify the corrosion process in real time using wavelength demodulation methods. This study will lay the foundation for subsequent work on the precise monitoring of copper corrosion using fiber Bragg grating sensors.