Superhydrophobic corrosion resistant coatings for copper via IR nanosecond laser processing

A series of superhydrophobic coatings with contact angles, exceeding 170 degrees and roll-off angles less than 1.6 degrees on copper alloy was designed using nanosecond IR laser processing, followed by vapor deposition of fluorooxysilane molecules. The experimental data show that for all samples, the surface layer consisted of cupric and cuprous oxide and demonstrated multimodal roughness. The morphology and composition of a textured surface layer for four fabricated samples varied depending on the laser processing parameters. It was found that the variation of parameters of laser processing leads to variation in chemical and corrosion resistance of fabricated coatings. Coatings with higher ratio of cupric to cuprous oxide show notably better barrier properties of the oxide layer, better chemical resistance in contact with an aqueous medium, and lower corrosion rate in chloride-containing electrolytes. It was demonstrated that in agreement with the previously reported analysis of mechanisms of corrosion protection by the superhydrophobic coatings, the higher is the chemical resistance of the layer of hydrophobic molecules with respect to desorption from the surface the better is the protective potential. The variation of laser processing parameters allowed selecting a regime for obtaining the superhydrophobic coating, for which the prolonged contact with the saline solution is accompanied by a significant decrease in the corrosion rate and the prolonged preservation of the superhydrophobic state.