This paper investigated the fretting failure of axial thrust steel bearings as per ASTM 4170 in the presence of anti-fretting pastes used in process industries. The pastes were differentiated based on the content of additives in them. The results indicated that the paste containing the additive package of copper, molybdenum disulfide, and graphite exhibited excellent anti-fretting properties (75–80% less bearing race mass loss) as compared with other lubricating pastes that contained only graphite/molybdenum disulfide and nickel as primary additives. There was less surface damage to the bearing races in the lubricating paste containing copper, graphite, and molybdenum disulfide. The machine vision images of the false brinelling indicated that the average area of false brinelling on the bearing races with the paste containing copper, molybdenum disulfide, and graphite was 2.537 ± 0.623 mm², while that of the other pastes containing graphite/molybdenum disulfide and nickel as primary additives were 4.504 ± 0.566 mm² and 4.914 ± 0.621 mm², respectively, indicating 50% less false brinelling area in the paste containing copper, molybdenum disulfide, and graphite as compared with the paste containing graphite/molybdenum disulfide and nickel. An asymmetric wear pattern was also observed in the thrust bearings used during the tribo test. Surface characterizations indicated the formation of wear debris, plastic deformations, and surface cracks during the tribo tests. The physico-chemical properties of the lubricating pastes such as the viscosity and work penetration properties played an important role in controlling the failure of the bearings due to fretting.

The rapid growth of electric vehicles and electrified systems has increased the risk of bearing failures due to combined mechanical and electrical stresses. This study investigated the performance of hexagonal boron nitride nanoparticle-enhanced lithium grease under electrified conditions. Experiments based on a Taguchi L9 orthogonal array were conducted on deep groove ball bearings using a full-scale test rig at 1200 rpm with varying loads (100–300 N), currents (6–10 A), and hBN concentrations (0.1–1 wt.%). The tribo-electrical performance of nano-enhanced grease was compared with the base grease and commercial grease. It was observed that the base grease exhibited superior performance with a lower current flow, reduced vibration, and minimal surface degradation. In contrast, the hBN-enhanced grease exhibited inferior tribo-performance, with high vibrations and surface damage in electrified conditions. The surface analysis revealed features morphologically similar to white etching areas and micro-pitting. The FTIR results indicated grease degradation, while ICP-OES confirmed higher wear debris generation in the commercial and hBN-added greases. The present work indicates that additives like hBN nanoparticles do not necessarily improve performance under electrified conditions, making it important to consider the type of additives to be added during lubricant formulation. Thus, the findings emphasize the importance of lubricant formulation for controlling electrically induced bearing failures and provide insights for developing advanced greases for electric machinery applications.