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

The 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.