Research And Application Of Metal Atmospheric Corrosion Monitoring Based On Electrochemical Noise Measurement

Electrochemical noise measurement as a kind of in-situ and non-destructive technique which was widely used in soil corrosion,and organic coatings evaluation,etc.but,the researchof atmospheric corrosion was less.In this study,an automated atmospheric corrosion based on electrochemical noise technique monitoring device was proposed.This paper processed and analyzed the electrochemical noise,besides,combined the synchronized results of the study on atmospheric corrosion,which studied the atmospheric corrosion behavior of Q235 carbon steel.The main results of the paper research were as follow:(1)The atmospheric corrosion monitoring device of Q235 carbon steel could be realized in-situ,non-destructively and continuously.The results could accurately reflect the noise fluctuations caused by atmospheric corrosion.Based on the MATLABplatform,a data analysis module was established,the advantages of the module were simple,fast processing speed and good reproducibility.The module can gettime-domain spectrogram through polynomial fitting,frequency-domain spectrogram through Fourier transform adding window and amplitude-time-frequency spectrogram through Hilbert-Huang transform,which creased the electrochemical noise analytical angle.(2)The change process of the rust layer of Q235 carbon steel was observed by morphological analysis: the brown rust layer,the red-brown rust layer and the dark brown rust layer.After 60 days' exposure,double rust layer appeared locally and three layers could be observed during exposure of 180 days by cross-sectional morphologies.According to EDS analysis,the oxygen content of the intermediate rust layer was the lowest.(3)There were five different feature of electrochemical noise time-domain spectrogram.a.the noise fluctuated uniformity,there were very few transient peaks.b.there was no obvious transient peak,low frequency fluctuation and large drift in early stage,and then high frequency fluctuation.c.there was a large number of transientof peaks.d.the potential noise and current noise was appeared opposite.d.the potential noise and current noise was appeared identically.The characteristic parametersof noise statistics and frequency spectrum had good consistency.In the 45 days of exposure of Q235 carbon steel,the value of W and k were the maximum and the potential noise of Rn was the minimum,which were related to the worst protective of the surface.There were three different characteristics of the time-frequency spectrum diagram: the noise signal was evenly distributed on the frequency domain axis;the noise signal was concentrated in the low frequency region;the noise signal wastransferred to the high frequency region.