Effects of metal film coatings on surface properties of laser-textured stainless steel

Stainless steel substrates were textured with a checkboard pattern by a NIR laser with different scan pitches and laser powers. The as-textured surfaces were found to be hydrophilic. However, after holding in air for 7-15 days, the surfaces exhibited strong superhydrophobicity with contact angles close to 150 degrees due to a reduction in the oxygen content. Thin-film Ag, Cu, Zn and Al coatings were deposited on the textured surfaces. The as-sputtered Ag and Cu films improved the hydrophobicity of the as-textured surface. However, the as-sputtered Zn and Al coatings increased the hydrophilicity. For all of the coatings, the hydrophobicity improved after aging in air for 7- 15 days. Furthermore, all of the coatings enhanced the corrosion resistance of the textured surface. Overall, the results indicate that laser texturing followed by thin-film metal deposition provides a feasible means of tuning both the wettability and the corrosion resistance of stainless steel surfaces.