Monitoring Passive Film Growth on Steel using Fe-C Coated Long Period Grating Fiber Sensor


Fe-C coating is electroplated on the surface of a long period grating (LPG) optical fiber, and the growth of passive film on its surface is monitored through the change of transmitted spectrum. The test is performed in saturated calcium hydroxide solution for 50 h, during which the passivation of the Fe-C coating is monitored with electrochemical impedance spectroscopy, and the change of the transmission spectrum of Fe-C coated LPG fiber is recorded with an optical spectrum analyzer (OSA). Results indicate that an increase is observed in open-circuit potential (OPC), passive film resistance, and transmission intensity while a decrease is present in passive film capacitance and resonant wavelength, all of which are associated with the growth of passive film. This Fe-C coated LPG optical sensor can be used to monitor the growth of passive film on steel in aqueous environment with varying sensitivity from 0.04 to 0.12 nm thickness increase corresponding to 1.0 nm decrease in the resonant wavelength.


Electrical and Computer Engineering

Second Department

Materials Science and Engineering

Research Center/Lab(s)

Intelligent Systems Center


This work was supported in part by the National Natural Science Foundation of China under Grant 51878119 and Grant 51738007, and in part by the National Key Research and Development Program of China under Grant 2016YFC0701108.

Keywords and Phrases

Deposition; Electrochemical Impedance Spectroscopy; Fiber Optics; Long-Period Grating Fiber; Passivation

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Document Type

Article - Journal

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© 2019 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Aug 2019