Mechanism of steel corrosion in concentrated NaOH solutions

Electrochemical Behaviour of Iron in NaOH 0.01 mol/L Solutions Containing Variable Amounts of Silicate

“…Generally three or four anodic peaks and one or two cathodic ones are identified for iron. Although the considered mechanisms may be different, almost all authors agree that the first and second anodic peaks are associated to ferrous species formation [2][3][4][5][6][7][8]11,16,45,46 although these anodic peaks are sometimes attributed to Fe 3 O 4 formation 8,11,15,16 , or the first one to adsorbed hydrogen oxidation 14,16 . The third and fourth anodic peaks are associated to ferric species formation [2][3][4][5][6][7][8]11,14,15,45,46 .…”

“…Many investigations were carried out using highly alkaline solutions [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] or using buffer solutions as carbonate/bicarbonate [19][20][21][22][23][24][25][26] or borate buffer [27][28][29][30][31][32] when a constant and not very high pH is desirable. Many products have been identified as resulting from the anodic polarization of iron at different potentials, by different surface analysis techniques [6][7][8][9][10][11][12][13]22,26,[33][34][35][36][37][38][39][40]…”

“…Many products have been identified as resulting from the anodic polarization of iron at different potentials, by different surface analysis techniques [6][7][8][9][10][11][12][13]22,26,[33][34][35][36][37][38][39][40][41][42][43][44][45] . Several electrochemical techniques have also been used to investigate the kinetics of the formation of these products and among them cyclic voltammetry is one of the most used [2][3][4][5][6][7][8][14][15][16][17][18][19][20][21][22] . The surface analysis techniques that perform in-situ analysis have the great advantage of avoiding decomposition and/or dehydration of products formed which is inevitable with ex-situ analysis due to the high vacuum conditions and to the heating promoted by electron bombardment 1,14,28,[33][34][35][36]…”

Role of Halides on the Passivation of Iron in Alkaline Buffer Solutions

“…In presence of various anions, iron dissolution was explained invoking the participation of SCTC and mechanistic schemes. Many studies about active dissolution and passivation were carried in alkaline solution [3][4][5][6][7][8][9][10][11][12] and many electrochemical studies have been investigating the behaviour of iron in aqueous solution. Several mechanisms have been suggested [3][4][5][6][7][8][9] [4,5,14].…”

“…Many studies about active dissolution and passivation were carried in alkaline solution [3][4][5][6][7][8][9][10][11][12] and many electrochemical studies have been investigating the behaviour of iron in aqueous solution. Several mechanisms have been suggested [3][4][5][6][7][8][9] [4,5,14]. Under potentiodynamic conditions, the first anodic peak is specifically related to Fe(OH) 2 formation and the second peak to Fe(OH) 2 with three dimensional oxide film, and the third peak to FeOOH formation [15][16][17][18].…”