Assessment of the Morphology, Microstructure, Stereometric and Tribological Properties of Al₂O₃ Surface Layers Produced Electrolytically with the Alternating Current Method in the Presence of Molybdenum Disulfide

Abstract

Dry friction tests were performed using a pin-on-plate tribological tester. In this study, Al₂O₃ and Al₂O₃ with MoS₂ admixture plate with PEEK/BG pin. Plate surfaces were created using the constant current method and the non-periodic alternating current method. The dimension of Al₂O₃ fibers walls were calculate based on SEM micrographs. SGP measurements of the oxide layers were made by a Taylor Hobson Talysurf 2D pin profilometer. It was found that the gradient structure favors the reduction of the friction coefficient and weight loss of PEEK/BG in the tested friction pairs, and the method of gradually reducing non-periodic alternating current allowed to obtain a more homogeneous microstructure of aluminum oxide. The use of high current densities at the beginning of the process leads to the production of non-gradient coatings characterized by higher SGP amplitude parameters. This property translates directly into higher wear of the sliding PEEK/BG material and higher values of the friction coefficients of the tribological pairs thus obtained. The research also identified a strong correlation between the friction coefficient µ and surface topography parameters before the tribological cooperation of PEEK/BG pairs - Al₂O₃ oxide coating.