Laser Texturing for Superwetting Titanium Alloy and Investigation of Its Erosion Resistance

Abstract

Erosion of materials is one of the major causes that lead to the malfunction of equipment and facilities, and surface texturing can be a solution for enhancement of erosion resistance. In this work, superwetting (superhydrophilic/superhydrophobic) titanium (Ti) alloy surface with periodic microstructure was prepared by a facile laser-based surface texturing approach which combines laser surface texturing and low-temperature annealing. The effect of laser-induced surface texture and wettability on the erosion resistance of the laser textured surface was studied. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to analyze the chemical surface microstructure and surface on the untreated and laser textured surfaces. The hardness and contact angle of the untreated surface, superhydrophilic surface and superhydrophobic surface were measured by microhardness tester and contact angle goniometer. Using an in-house built erosion experimental setup, the erosion resistance of the untreated surface, superhydrophilic surface and superhydrophobic surface was investigated. The experimental results demonstrate that micro-bumps are formed after laser surface texturing. In the meantime, the surface hardness for the laser textured surface with a step size of 150 μm is increased by 48% under the load of 1.961 N. Compared with the untreated surface, the erosion resistance is increased by 33.9%, 23.8% and 16.1%, respectively, for the superhydrophobic surface. The SEM results show that the untreated surface has large and deep impact pits, while the superhydrophobic surface only has small and shallow impact pits, indicating that the erosion process resulted in less damage to the substrate. The EDS results shows that superhydrophobicity plays a critical role in protecting the substrate from erosion. It is thus believed that the superhydrophobic surface has pronounced effects for improving the hardness and erosion resistance of Ti alloy.