Pore blocking characteristics of corrosion products formed on Aluminum coating produced by arc thermal metal spray process in 3.5 wt.% NaCl solution

• Al coating by arc thermal metal spray gives significant protection to mild steel.
• Blocking effect to pores/defects are exerted by corrosion products.
• XRD and Raman spectroscopy revealed the formation of α-Al(OH)3 on coating surface.
• A schematic model is proposed to explain the corrosion phenomena of Al coating.

Arc thermal metal spray coating is very efficient process to protect the steel from corrosion in industrial, humid and saline/coastal environments. This paper incorporates the experimental results for the performance of Aluminum coating deposited on mild steel substrate by arc thermal metal spray. Different electrochemical techniques, FE-SEM, Raman spectroscopy and XRD were used to assess the performance of deposited coating. Electrochemical studies revealed the enhanced corrosion resistance properties of coating in 3.5 wt.% NaCl solution. The formation of α-Al(OH)3 on coating substrate during exposure periods block the pores of coating and impede the penetration of corrosive species to react with substrate.