Friction regulation of laser textured PVA hydrogels against a titanium alloy

Abstract

Hydrogels have exhibited extremely complex tribological behaviors. Although various physical mechanisms have been proposed to explain their tribological behaviors, it is still a challenge to develop convenient and efficient regulation methods for tribological behaviors. We propose micro-grooves with different depths and spacings prepared on the PVA hydrogels surface by ultraviolet laser texturing to provide an effective method for understanding the tribology of hydrogels. At the sliding velocity range of 0.085 mm/s < v less than 2.3 mm/s, the effect of interlocking and ploughing force between the direct contact interfaces are the dominant origins of friction. Frictional stress increases when the spacing of the micro-groove getting smaller as the frequency of interlocking getting higher. Interestingly, frictional stress doesn’t increase with increasing micro-groove depth. Once the velocity exceeds to 6.9 mm/s, all the micro-grooves begin to wear and fracture, and the results of the frictional test become inaccurate. Smooth hydrogels without any micro-grooves enter elasto–hydrodynamic transition at the lowest velocity, which have minimum friction stress. These results take us a step closer to deriving a more effective, accurate, and dependable guideline for sliding friction control in hydrogel applications.