Synergistic effect of surface sinusoidal textures and oxide layer on tribological properties of 40Cr alloy steel

Researchers have been concentrating on enhancing the surface tribological properties and minimizing wear on mechanical components during the oil starvation stage. In this work, a nanosecond laser was used to prepare sinusoidal textures of different amplitudes on the surface of 40Cr alloy steel, and then the obtained surfaces were pre-oxidized at 100 °C, 300 °C, and 500 °C, respectively. The results demonstrated that excessively large or small amplitude values would reduce the wear debris trapping ability of the textures, which ultimately affected the formation of the tribofilm. In addition, the numerical simulation results reveal that the texture pressure difference is positively correlated with the texture amplitude, but excessively high or low amplitude leads to a significant micro-vortex effect within the texture. The tribological properties of the textured surfaces could be further enhanced by the pre-oxidation treatment. The experiment results indicated that the pre-oxidation treatment increased the degree of surface oxidation and promoted the formation of tribofilm. This work will pave the way to improve surface tribological properties by integrating sinusoidal textures and self-generated tribofilm.