**Joel Voyer 1,\*, Johann Zehetner 2,\*, Stefan Klien 1, Florian Ausserer <sup>1</sup> and Igor Velkavrh <sup>1</sup>**


Received: 28 June 2019; Accepted: 1 August 2019; Published: 6 August 2019

**Abstract:** The aim of the present study was firstly to determine the manufacturing feasibility of a specific surface 3D-microtexturing on steel through an ultra-short pulsed laser, and secondly to investigate the tribological properties under 2 different lubrication conditions: oil-lubricated and antifriction coated. The selected 3D-microtexture consisted of 2 different levels of quadratic micropillars having side dimensions of approximately 45 μm, heights of about 35 μm and periods of 80 μm. It was shown that the production of specific 3D-microtextures on steel substrates using an ultra-short pulsed laser was feasible, and that the reproducibility of the texture dimensions over the entire textured region was extremely good. Frictional investigations have shown that, in comparison to the benchmark (untextured samples), the 3D-microtextured samples do not induce any significant improvements in the coefficient of friction (COF) under oil-lubricated conditions, but that under antifriction coated conditions, significant improvements in the friction coefficients may be achieved. Wear-based tribological tests have shown that the antifriction coating on benchmark samples was completely depleted, which greatly influenced their friction and wear behavior, since steel-steel contact occurred during testing. For the 3D-microtexture, the antifriction coating was also partially depleted; however, it accumulated itself in the microtexture which acted as a potential lubricant reservoir.

**Keywords:** laser microtexturing; ultra-short pulsed laser; surface characterization; tribological characterization; friction; wear
