Synergistic Effect of S2-and Cl-on Corrosion and Passivation Behavior of 316L Austenitic Stainless Steel
The synergistic effect of S2-and Cl-on corrosion resistance of 316L austenitic stainless steel in artificial seawater with different S2-concentrations were studied by using electrochemical testing techniques,SEM,CLSM,EDS,and XPS.The results showed that S2-and Cl-have synergistic damaging effects on the corrosion resistance of 316L austenitic stainless steel.S2-inhibited passivation film genera-tion by competitive adsorption with OH-,and the participation of S2-in the passivation process is conduc-tive to the formation of FeS and MoS2,increasing the doping density but reducing the shielding perfor-mance of the passivation film,thus accelerating pitting induced by Cl-.As the S2-concentration increased from 0 to 100 mmol/L,the solution pH was increased from 8.2 to 12.8,resulting in a negative shift of the free-corrosion potential Ecorr by 0.328 V and an increase in the corrosion current density Icorr approximately one-fold.When the S2-concentration was greater than 0.1 mmol/L,316L austenitic stainless steel lost its repassivation performance.When the S2-concentration was greater than 100 mmol/L,316L austenitic stainless steel lost its passivation performance.
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