Droplet Spreading and Wettability of Abrasive Processed Aluminum Alloy Surfaces

One of the main cause of a droplet metastable state is found to be surface roughness. This state is characterized by a large contact angle hysteresis and condition when the static contact angle is larger than the advancing dynamic contact angle. Besides the texture, other factors can influence the deviation from the equilibrium state, in particular, the fluid flow rate (the growth rate of a droplet) affecting the contact line speed. An experimental study was done to determine the effect of roughness and fluid flow rate on wetting of aluminum-magnesium alloy surfaces with random roughness processed by abrasive polishing. Three-dimensional roughness parameters were used to evaluate their texture. The correlations between these parameters, static, advancing and receding dynamic contact angles, hysteresis, and contact line speed were obtained. The molecular-kinetic theory of wetting was used to interpret the dynamic contact angle data.