Effect of laser treatment and hydrophobization on the corrosion-electrochemical behavior of aluminum
The effect of laser treatment of aluminum on the properties of the surface oxide/hydroxide layer is studied. It is shown that the treatment in air leads to an increase in the thickness of the oxide layer and practically to the complete disappearance of the hydroxide forms. However, the protective properties deterioration of this layer is associated with an increase of it defectiveness and porosity. The optimal regime of laser treatment of aluminum resulting in the spontaneous formation of oxide layer with a significant proportion of the hydroxides on the surface is laser irradiation in an inert argon gas medium with a small content (1-2 vol.%) oxygen. The surface layer created effectively inhibits the anodic dissolution of aluminum in a model corrosive environment (borate buffer solution at pH = 7.4). It is shown that both the initial spontaneously formed oxide-hydroxide film and the obtained during laser treatment oxide film are hydrophilic, i.e. well moistened with water. It has been established that the surface treatment of aluminum both in the initial state and after laser irradiation with a solution of vinyltriethoxysilane (VTES) leads to the surface hydrophobization. The surface layer formed in this way leads to a significant reduction in the anodic dissolution currents. Modification of the surface by VTES leads to the formation of a complex adsorption layer with hydrophobic properties. Using X-ray photoelectron spectroscopy, it was shown that the adsorption of silane occurs both with the participation of silicon atoms and carbon atoms of the alkene bond. The hydrophobic layer of adsorbed silane on the laser-treated surface has a greater thickness and a higher effect of inhibiting the anodic dissolution of aluminum than in the case of the initial aluminum surface.