Electrochemical Investigation On Galvanic Corrosion Of Seawater Desalination Evaporator And Prediction Of Corrosion Rate

The common materials used by the desalination evaporators are titanium,aluminum brass and 316L stainless steel.In this paper,the array electrode technology was used to measure the galvanic current and potential of the three metals under different temperature,Cl~-concentration,and relative positions by the use of controlling variable method.The electrochemical corrosion behavior of these three metals when coupled in artificial seawater was discussed.The results show that the anodic reactivity of HAl77-2 is enhanced with the increase of temperature,and the cathodic reaction on 316L SS and TA2 is the oxygen uptake reaction,which is controlled by oxygen diffusion and the increase of temperature is complicated for the dissolution of the open system.So according to the change of temperature,the change of corrosion rate of 316L SS and TA2 is mildly.The corrosion rate of HAl77-2 is kept to be basically stable at first and Cl~-concentration continues to increase cause the increase of corrosion rate of HAl77-2,The corrosion rate of 316L SS and TA2 fluctuates slightly with the increase of Cl~-concentration,which may be due to the passivation of 316L SS and TA2 in artificial seawater,and the stability of the blunt state is better,Cl~-is difficult to destroy the passivation of the two metals;In studying the effect of different electrodes on the corrosion conditions,the No.2 electrode is always the most stable state,followed by the No.1 electrode,No.3 electrode anode HAl77-2 corrosion the most intense.Two three-layer BP neural network models were established with the experimental data.The model?and model?is:3-4-3 and 3-6-3,respectively.These two models respectively predict galvanic current and galvanic potential of the three metals.The prediction results show that the BP neural network has good accuracy in predicting the corrosion rate in the range of allowable error,which would have important reference value for the study of the life prediction in desalination.The two models can also predict how the single factor change influence the current and galvanic potential of HAl77-2,316L SS and TA2.Four kinds of amino acid corrosion inhibitors SA1,SA2,SA3 and SA4 were screened by electrochemical impedance spectroscopy that can be used as aluminum brass inhibitor.SA1has the best corrosion inhibition efficiency when all the inhibitors are used alone,and then complex it with the other three kinds of corrosion inhibitors.The results show that SA1 and SA3 have the highest corrosion inhibition efficiency and higher than the corrosion inhibition efficiency when they were used alone.The performance and corrosion inhibition mechanism of the complex corrosion inhibitor were studied by weight loss method,polarization curve method and scanning electron microscope.The results show that the binary corrosion inhibitor is an adsorption inhibitor,which is a mixed type corrosion inhibitor with cathode control.The corrosion inhibition efficiency of the binary complex corrosion inhibitor increased with the increase of the concentration of the inhibitor,and the maximum corrosion inhibition efficiency was obtained when the SA1 of 140 mg/L SA1 and 10 mg/L were added and the efficiency is 92.322%.When the corrosion inhibitor concentration continues to increase,the inhibition efficiency will decline due to the desorption of corrosion inhibitor in the metal surface.