Investigation of Mn- and Zn-Phosphate coated bearings designed to withstand axial loads: Effects of solid-liquid composite lubrication with contaminant particles

Abstract

In this study, Mn-based phosphate and Zn-based phosphate coatings were fabricated to establish a solid-liquid composite lubrication system, aiming to enhance the wear resistance of thrust roller bearings under contamination conditions (Fe₃O₄, Al₂O₃, and SiO₂).The friction and wear characteristics of the bearings under composite lubrication in contaminated conditions were investigated, and perform wear failure analysis on the bearings. The results show that both Mn-based phosphate and Zn-based phosphate coatings significantly reduced friction, coefficient of friction, and wear losses compared to uncoated bearings. The coatings altered the wear mechanisms of the bearings, with uncoated bearings wear surfaces primarily dominated by abrasive wear, while the coated surfaces exhibited more surface fatigue wear. During operation, centrifugal force and sliding velocity caused contaminants to accumulate at the outer raceway, significantly intensifying wear in this region. Additionally, a self-polishing phenomenon was observed in the coatings. During polishing, contaminant particles were embedded into the coatings, forming a self-adaptive composite layer that absorbed the particles and improved surface strength, further enhancing the wear resistance of the coatings.