Investigation of corrosion protection afforded by inorganic anticorrosive coatings comprising micaceous iron oxide and zinc dust

Abstract

The present study deals with the investigation of the effects of partial replacement of sacrificial zinc dust by high efficiency barrier micaceous iron oxide (MIO) pigments on the corrosion protection behaviour of inorganic zinc rich coatings. To this end, waterborne zinc rich silicate paints based on nanosilica modified potassium silicate were formulated with different contents of zinc and MIO. After being applied on carbon steel panels, the coatings were evaluated by electrochemical impedance spectroscopy, corrosion potential measurements and salt spray test. Replacement of zinc by MIO in the formulation of zinc rich paints was revealed to shorten the duration of cathodic protection stage while on the other hand giving satisfactory results in 1000 h of salt spray test. It was concluded that the incorporation of MIO pigments in conjunction with zinc into the formulation of inorganic zinc rich coatings is a potential means to control the reactivity and the barrier protection stage.