Friction and wear behaviors of sliding bearing under heavy loads and simulated sand-dust conditions

Sliding bearings, as critical supporting components in mechanical equipment, are widely utilized across various industries. With continuous technological advancements, sliding bearings are increasingly exposed to more demanding tribological conditions. In this work, we investigate the friction and wear behaviors of bushings with varying hardness induced by differences in precipitate morphology, when mated with nitriding shafts under high-load conditions and simulated sand-dust environments. The experimental results indicate that an increased applied load initiates the tribo-chemical reaction between tribo-pairs and the lubricant. Furthermore, the tribo-films formed on the worn surface of bushing, which exhibit enhanced hardness, show better durability, effectively reducing friction and wear. Under the simulated sand-dust environment, the introduction of even a small number of sand dusts intensifies abrasive wear between the tribo-pairs, with more Fe from the shaft detected as the sand-dust concentration increases. However, an appropriate concentration of embedded sand dust creates favorable conditions for the reaction and depolymerization of ZDDP (zinc dialkyldithiophosphate) additive in the lubricant, enhancing long-term protection regardless of bushing hardness.