Fabrication of antireflection surfaces with superhydrophobic property for titanium alloy by nanosecond laser irradiation

Titanium alloy has been widely used in the aerospace field due to its advantages of low density, high specific strength and high-temperature resistance. Its scope of application, however, has been narrowed down because of its high reflectivity to light. In order to maximize the potential, it becomes necessary to construct a surface light trapping structure of titanium alloy. Therefore, a simple and tunable method was introduced in this paper to fabricate antireflection microstructures on titanium alloy surface with the superhydrophobicity based on nanosecond laser. By optimizing the laser processing speed parameters, microstructured surfaces with low reflectance over the entire visible wavelength range and near-infrared region (400–1000 nm) can be obtained. Results indicate that when the scanning speed is 100 mm/s, the minimum reflectance in the 900–1000 nm wavelength range is less than 1%, and the total reflectance in the 500–1000 nm wavelength range stabilizes below 6%. In contrast, the surface of conventional titanium alloy absorbs only about 50% of the incident light, and the remaining 50% is reflected. Furthermore, treated surfaces demonstrate effective performance concerning hydrophobicity, with a maximum contact angle of 153.03°. The results show that the nanosecond laser can induce the anti-reflection and super-hydrophobic properties, and improve the absorption capacity of the surface.