| Steel corrosion is a major cause of early destruction of concrete structures. The safety service of structures depends on an effective corrosion monitoring. Optical fiber sensing with the advantages of anti-electromagnetic interference, high sensitivity, stable signal, and etc., is widely applied on the structural health monitoring. Fiber Bragg grating(FBG) takes an important part in optical sensing technology, sensitive to strain, temperature etc., achieves monitoring by wavelength demodulation.An optical corrosion monitoring technology based on Fe(C) film and fiber Bragg grating is studied in this thesis. This sensing method takes advantages of the corrosion sensitivity of Fe(C) film and the strain or refractive index response of fiber Bragg grating, to become a nondestructive, real-time and effective corrosion monitoring.Based on the research on Fe(C) film and fiber Bragg grating(chapter 2), three sensors of Fe(C)-FBG by electroplating(chapter 3), Fe(C)-FBG by magnetron sputtering(chapter 4), Fe(C)-etched-FBG(chapter 5) are fabricated and tested.The main research work in this thesis can be concluded as:(1) Based our former study of Fe(C)-FBG by electroplating, this thesis makes further research on film deposition process and optimization of electroplating parameters, to improve the quality of Fe(C) film coated on FBG. The effect of structural parameters and corrosion environments on sensing properties is discussed. Electrochemistry monitoring and optical sensing are compared. In the end, Fe(C)-FBG is dipped into simulated concrete pore solution for simulation monitoring in concrete environment.(chapter 3)(2) The magnetron sputtering of magnetic Fe(C) film is developed. Films fabricated by electroplating and magnetron sputtering are compared. The sensing characteristics of Fe(C)-FBG by electroplating and Fe(C)-FBG by sputtering are compared.(chapter 4)(3) A novel Fe(C)-etched-FBG refractive index sensing corrosion sensor is developed.(chapter 5)... |
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