Construction of wear resistant superhydrophobic structure without degrading the surface mechanical properties of alloy layer

Abstract

The vulnerability of superhydrophobic surface structures frequently leads to a loss of their superhydrophobicity under friction, significantly restricting their broad-scale applicability. The preparation of alloy layers emerges as an effective strategy to enhance the mechanical properties of metal surfaces. The construction of superhydrophobic structures without loss of mechanical properties of alloy layer is expected to lead to the preparation of superhydrophobic surface with excellent wear resistance. In this study, a superhydrophobic surface with excellent hardness and wear resistance was successfully prepared by a two-step process of electrospark deposition and anodization. The superhydrophobic surface maintained superhydrophobicity under long distance friction. Firstly, alloy layer with micron bulges and excellent mechanical properties was constructed on the metal surface by electrospark deposition, which was then slightly anodized to create hierarchical micro-nano bulges rather favourable to superhydrophobicity, and anodization did not degrade mechanical properties of the surface. The surface is provided with excellent superhydrophobicity after modification with fluorosilane. SEM, 3D profilometer and roughness tester were adopted to explore microscopic morphology of the sample surfaces. XPS and FTIR were used to explore chemical components of the sample surfaces. The element distribution of the sample surfaces was analysed through EDS, and wettability of the sample surfaces was explored through the contact angle test. The hardness test and wear test were applied to explore mechanical properties of the sample surfaces. It was proved through linear friction, droplet impact, hammering and knife scratch that the superhydrophobic surface could maintain good superhydrophobicity under multiple forms of mechanical destruction, while the neutral salt spray test, electrochemical tests and acid and alkali soaking test proved the excellent property of corrosion resistance of the superhydrophobic surface. In addition, the prepared superhydrophobic surface also features an excellent self-cleaning property.