Fe–C-coated fibre Bragg grating sensor for steel corrosion monitoring

A steel corrosion sensor based on fibre Bragg gratings (FBGs) has been developed and tested in this paper. The steel corrosion sensor has been formed by electroplating a Fe–C film on a metallized FBG. The coated FBG sensors have been tested in cabinets in which the availability of chloride ions and oxygen are controlled. The microstructural changes have been investigated by optical microscopy and SEM imaging. The FBG spectra are collected by a spectrometer. The results show that the spectra change, the wavelength shift, and the occurrence of multiple peaks are related to the corrosion degree of the Fe–C film.

Research highlights
► Fe–C film is electroplated on the surface of the Fiber Bragg Gratings.
► Expansion of the Fe–C film induces Bragg wavelength shift or multiple peaks.
► Occurrence of corrosion is indicated by wavelength shift or multiple peaks.
► Grain sizes of the Fe–C film are increased with the corrosion process.
► The proposed sensor is sensitive to the corrosion of the coating film.