Sensitivity of Corrosion Behavior for Fe-Based Amorphous Coating to Temperature and Chloride Concentration

Weiyan Lu,Qi Wang,Suode Zhang,Fan Yang,Yutong Shi,Debin Wang,Baijun Yang,Tianrun Li

doi:10.3390/coatings11030331

Abstract

The effects of solution concentration and temperature on the electrochemical behavior of the Fe-based amorphous (AMCs) coatings in NaCl solution were studied by using conventional electrochemical measurement and XPS analysis. Results indicated that as solution concentration and temperature increased, the current density for the Fe-based AMCs increased and the pitting potential decreased. This reduced corrosion resistance was derived from the decreased passivation index and polarization resistance, which contributed to the decrease of the induction time (tm) for the initiation of corrosion pit. The passive films formed on Fe-based AMCs exhibit two types’ semiconductors higher and lower the flat band potential. The decrease of protectiveness of the passive film was mainly correlated with the reduction of Cr2O3 content, the increase of carrier density and the decrease of the work function (WF).

Highlights

Fe-based amorphous coatings (AMCs) are potential coatings against corrosion and wear for many applications in shipbuilding, petroleum, nuclear industry, and other fields owing to their unique structure and excellent combination properties [1,2,3,4,5]
The results indicated that the total amount of oxidized Fe in the passive film on the Fe-based AMCs decreases with the increase of solution concentration
The effects of solution concentration and temperature on the corrosion performance of Fe-based AMCs were studied by conventional electrochemical test, electrochemical impedance spectroscopy (EIS) combined with XPS

Summary

Introduction

Fe-based amorphous coatings (AMCs) are potential coatings against corrosion and wear for many applications in shipbuilding, petroleum, nuclear industry, and other fields owing to their unique structure and excellent combination properties [1,2,3,4,5]. As for the corrosion mechanism of Fe-based AMCs, it was well recognized that Cr-depleted zone among the intersplats in the coating was the major reason for the initiation of pitting corrosion of the coating [8,10]. It was noteworthy that Wu et al have investigated the corrosion performance of Fe-based AMCs under dry and wet cyclic conditions simulated marine environments for coating practical applications [17]. There is still a lack of relevant reports on the corrosion mechanism and behavior of Fe-based AMCs at different solution concentrations and temperatures. The concentration of aggressive ion (e.g., chloride ion) and the solution temperature probably change the composition and the properties of the passive film on Fe-based AMCs and change the corrosion behavior of the coating. The mechanism of this effect has not yet been fully understood

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