Tribological Properties of Bronze Containing Micro Sized Sulfide -Application of Atomic Force Microscopy-

The present study describes the tribological properties of a bronze alloy used as a sliding interface for operation under dry conditions. Many industrial slide bearings are made from bronze alloy. To achieve easy running-in and enhanced anti-seizure, solid lubricants are added to the alloys. However, it is difficult to simultaneously achieve easy running-in and anti-seizure with one solid lubricant. Thus, the combined effects of a solid lubricant and a dispersed sulfide layer on reducing and stabilizing the friction coefficient were also examined. The tribological properties of the resulting alloy were evaluated with a 3-ball on disc type testing apparatus under dry conditions and in air atmosphere. The surface state of the solid lubricant and dispersed sulfide layer was evaluated by observation of the morphology and phase states via atomic force microscopy. Distinctive features of a phase comprising mixed stiff and soft regular regions on the micrometer scale were observed. These two regular regions are considered to be formed from graphite and sulfide by burnishing. The effect of the dual phase state leads to achievement of both easy running-in and anti-seizure

Effects of dispersed sulfides in bronze under line contact conditions

A sintered bronze system is applied to plane bearings with some lubricants. A bronze-based, sulfide-dispersed Cu alloy was developed via sintering. Sulfides had some functions, reduction of friction resistance, preventing scoring and seizure. Effects of the developed sulfide-containing bronze were investigated using a journal-type testing apparatus in wet conditions; results indicate that the developed bronze may have some anti-scoring properties

Effect of Surface Groove and Graphite Penetration on Friction Properties of Sulfide Containing Copper Alloy Journal Bearing in Dry Condition

AbstractThe present study describes friction properties of sintered copper alloy journal bearing. Sulfide contained copper alloy material studied as the material of the journal bearing. The micro structure of the copper alloy was consisted from micro sized pores and sulfide phase mainly dispersed at the boundary region. For the purpose of friction study, the sliding surface of the journal bearing was in the form of machined texture. A spiral groove was applied to the inner surface of the journal and graphite was occasionally penetrated into the groove. The experiment was carried out using a developed testing apparatus that consists of a spindle driven with an air cooled DC motor and a disc shape bearing holder in air atmosphere without lubricants. The hardened steel shaft having fine ground surface was used as the mating specimen. The results found that the application of spiral groove with graphite penetration was effective to increase the sliding distance up to the occurrence of seizure. In particular, the graphite penetration resulted in significant increase in the sliding distance despite that the decrease in friction coefficient. It was estimated that the application of the groove with graphite penetration restricted the transfer of the journal elements on the mating steel surface