Improved Friction and Wear of M50 Steel Composites Incorporated with ZnO as a Solid Lubricant with Different Concentrations Under Different Loads

This experimental study explores improving the tribological behavior of M50 steel using ZnO as a solid lubricant with different concentrations of 5, 10, 15, 20, and 25 wt.%. Tribological tests were conducted using pin-on-disk tribometer under different loads of 3, 6, 9, and 12 N and constant sliding speed of 0.2 m s⁻¹ in air. XRD, EPMA, FESEM, EDS mapping, and XPS tests were performed to understand the major mechanisms leading to improve the tribological and mechanical properties of M50 composites. Results showed that the best tribological and mechanical properties were obtained at 20.0 wt.% of ZnO. Friction coefficient and wear rate were reduced by 52.909 and 70%, respectively, due to the formation of tribo-films on the worn surfaces. Furthermore, the hardness of M50 composites increased by 27.86%. Our study provides results with suggestions to overcome the challenges facing the technology when using M50 matrix composites in mechanical applications.