Wettability Of Laser Textured Solid Surfaces

Wetting phenomena exists widely in both nature and engineering applications, and surface wettability determines the application scope of materials to a great extent, while the solid surface topography is one of the most important factors that affect surface wettability. In order to study the effect of working conditions and solid surface topography on wettability, as well as the relevancy between wettability and3D surface topography characterization parameters, by controlling the shape, spacing and depth, a series of45steel specimens with the same surface arithmetic average height Sa and different surface microstructure were designed and manufactured by laser surface texturing. All the surfaces were measured by non-contact3D Optical Profiler Talysulf CCI Lite and characterized by ISO25178. A series of wetting experiments were conducted with32turbine oil on the Optical Contact Angle and Surface Tension Meter SL200KS, and the effect of temperature, droplet volume and surface microstructure was analyzed. Based on Flow-3D, the progress of liquid drops spreading on solid surfaces with different microstructure was simulated. Quantitative research of the relationship between the topography random characteristic and wettability of solid surface was conducted with some parameters from ISO25178.Based on the contact angle is an acute angle, the results show that the contact angle of droplet on the solid surface decreases rapidly to a stable value in wetting process. The stable value decreases with the increase of temperature, while with the increase of droplet volume it increases first and then decreases. Laser micro-texturing changes surface wettability, and the wettability of the surfaces even with the same Sa is not consonant with each other for the difference among both the shapes and directions. Textured surface with grooves along the droplet spreading shows the best wettability in this research. The wettability of surfaces has strong relevance with the amplitude parameters (Sku> Ssk), spatial parameters (Str、 Sal), hybrid parameters (Sdq、Sdr) as well as feature parameters (Sda、Sdv), which are all from ISO25178.