Abstract
An interruption by sulfate ion on the inhibitive effect of aluminium ion for iron corrosion in water has been investigated. The inhibitive effect of aluminium ion was found to be markedly deteriorated when the water contained sulfate ion. In the absence of sulfate ion, a thin and compact protective film of hydrated aluminium hydroxide was formed on the surface of the specimen during the corrosion, while in the presence of sulfate ion a dense film with many cracks of polynuclear sulfatecontaining oxy-aluminium complex was found to be formed, which caused a considerable deterioration of the inhibitive effect of aluminium ion. In order to overcome this defect, many additives that act co-operatively with aluminium ion were examined, whereby 2-mercaptobenzothiazole and some related compounds were found to be very effective.
