Tribological performance of microstructured surfaces with different wettability from superhydrophilic to superhydrophobic

The anti-friction function of superwetting surfaces with superhydrophobicity has been demonstrated. However, the influence regularity of wettability to tribological performance, and the underlying mechanism are still unclear. Here, two kinds of microstructured surfaces with different wettability are fabricated on the substrate of steel by controlling surface chemical compositions. The water contact angles on these surfaces range from 0° to 151°. The ball-plate tribological tests are performed under water lubrication. The results show that the tribological performance is closely related to surface wettability. The friction coefficient increases with the increase of contact angles when the surfaces are hydrophilic rather than superhydrophilic. In contrast, the friction coefficient on the hydrophobic surfaces decreases with the increase of contact angles. Furthermore, the best anti-friction capability is obtained on the superhydrophobic surfaces, and the anti-friction mechanism is elucidated. The lowest friction coefficient was 0.12 under the load of 10 N. This work provides strong evidence of an association between tribological property and wettability, which may inspire the fabrication and application of special wetting surfaces in friction control.