Corrosion Performance of Al and Zn Coatings Deposited by Arc Thermal Spray Process in 3.5 wt.% NaCl-Contaminated Concrete Pore Solution

Abstract

The corrosion of steel rebar embedded in the coastal areas is corroding once the chloride ions ingress through the pores of the concrete. Therefore, in the present study, a 100 μm thick Al and Zn coating was deposited by an arc thermal spray process onto the steel. The corrosion studies of these deposited coatings were assessed in 3.5 wt.% NaCl contaminated concrete pore (CP) solution with immersion periods. The results show that the Al coating is more corrosion resistance compared to the Zn coating attributed to the formation of gibbsite (γ-Al(OH)3) whereas Zn coating exhibits Zn(OH)2 onto the coating surface as passive layer. The Zn(OH)2 is readily soluble in an alkaline solution. Alternatively, γ-Al(OH)3 on the Al coating surface is less solubility in the alkaline pH, which further provides barrier protection against corrosion.