Abstract
The anticorrosive and protective action of Ca(OH)2 solutions in the presence of corrosion activators (chlorides and sulphates) has been studied for a carbon steel. It was found that Ca(OH)2 soluiions with concentrations ≥0·76 g l−1 effeciively protect the steel from corrosion in the presenee of chloride ions in concentrations up to 0·365 g l−1 and sulphate ions in concentrations up to 0·44 g l−1. The addition of 0·010–0·050 g l−1 NaCl or 0·014–0·067 g l−1 Na2 SO4 to Ca(OH)2 soluiions enhances the inhibitive properties of those solutions containing insufficient concentrations of Ca(OH)2 to protect the steel completely alone. This enhancement is the result of the nature of the protective film, consisting of complex compounds of iron and calcium, that is formed on the steel surface in Ca(OH)2solution. Introducing the corrosion activators to the Ca(OH)2 solutions accelerates the accumulation of corrosion products necessary for film formation, thereby accelerating the subsequent formation of the protective film.
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