Spreading and Drying Dynamics of Water Drop on Hot Surface of Superwicking Ti-6Al-4V Alloy Material Fabricated by Femtosecond Laser

• Main Authors: Ranran Fang, Zekai Li, Xianhang Zhang, Xiaohui Zhu, Hanlin Zhang, Junchang Li, Zhonglin Pan, Zhiyu Huang, Chen Yang, Jiangen Zheng, Wensheng Yan, Yi Huang, Valeriy S. Maisotsenko, Anatoliy Y. Vorobyev
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Nanomaterials
• Subjects: femtosecond laser processing; nanostructures; microstructures; laser-induced periodic surface structures (LIPSS); wicking materials; super-hydrophilic materials
• Online Access: https://www.mdpi.com/2079-4991/11/4/899

A superwicking Ti-6Al-4V alloy material with a hierarchical capillary surface structure was fabricated using femtosecond laser. The basic capillary surface structure is an array of micropillars/microholes. For enhancing its capillary action, the surface of the micropillars/microholes is additionally structured by regular fine microgrooves using a technique of laser-induced periodic surface structures (LIPSS), providing an extremely strong capillary action in a temperature range between 23 °C and 80 °C. Due to strong capillary action, a water drop quickly spreads in the wicking surface structure and forms a thin film over a large surface area, resulting in fast evaporation. The maximum water flow velocity after the acceleration stage is found to be 225–250 mm/s. In contrast to other metallic materials with surface capillarity produced by laser processing, the wicking performance of which quickly degrades with time, the wicking functionality of the material created here is long-lasting. Strong and long-lasting wicking properties make the created material suitable for a large variety of practical applications based on liquid-vapor phase change. Potential significant energy savings in air-conditioning and cooling data centers due to application of the material created here can contribute to mitigation of global warming.