Design and experimental studies of self-healable anti-corrosion coating: Passivation of metal surfaces by silicone oil impregnated porous oxides

Oil-impregnation into a hydrophobized porous surface structure effectively enhances corrosion resistance of metallic materials. In this study, an anti-corrosive silicone oil-impregnated porous oxide layer without hydrophobic coating (i.e., low surface energy materials) was created on metal surfaces. Various surface porous oxide layers were fabricated using magnesium alloy, stainless steel, aluminum alloy, and copper. Their corrosion resistances were compared after silicone oil-impregnation. The impregnation of silicone oil into a hydrophilic porous oxide layer followed by heat treatment lead to the formation of a polydimethylsiloxane (PDMS) brush on oxide surfaces, which enhanced the affinity with the impregnated oil and repellency to water. The silicone oil-impregnated porous oxide surfaces with PDMS brushes showed a high repellency to water, indicating inhibition of a direct contact with corrosive aqueous liquids. Hence, the corrosion resistances of the surface-treated magnesium alloy, stainless steel, aluminum alloy, and copper were significantly enhanced. In the presence of local damages, the silicone oil naturally permeated into the damaged region and the PDMS brush, which was formed by a simple heat treatment, showed the capability to repair anti-corrosion. It is believed that the results of this fundamental and practical study will provide a new approach for anti-corrosive surface finishing for metals.