Low Wear Steel Counterface Texture Design: A Case Study Using Micro-pits Texture and Alumina–PTFE Nanocomposite

Abstract

Laser-induced surface micro-pits pattern has been successfully used under fluid lubrication to reduce friction and wear through mechanisms of enhanced hydrodynamic lubrication and fluid retention. Limited successes of friction and wear reduction using solid lubricant and textured surfaces have been reported in the literature, and there still lacks an efficient way of finding textures that produce desired tribological performances. This study evaluates the effect of counterface micro-pits texture on wear of a notable alumina–PTFE nanocomposite and uses the Taguchi method and “Simplex Method” to find the micro-pits parameters producing the lowest wear of the composite material. The optimum texture found yields a composite wear rate of 1 × 10−7 mm3/Nm, a value identical to the material’s wear rate against untextured counterface. However, when slid against a freshly replaced composite pin, the existing transfer film on the optimum texture reduces composite’s wear volume at low wear transition by 90% and yields a steady-state wear rate of 3.9 × 10−7 mm3/Nm. On the contrary, preexisting low wear transfer film on untextured counterface increases wear of the newly replaced pin by 10× and yields a wear rate of 4.4 × 10−6 mm3/Nm. Results in this study suggest larger, shallower and sparser counterface pits are more favorable for debris entrapment, transfer film formation and wear reduction when slid against polymeric solid lubricants. It also raises new possibilities of self-adapting low wear counterface texture design that could potentially support low wear without requiring large amounts of run-in wear volume of bulk solid lubricants.