Development of Lead-Free Bronze with Sulfide Dispersion for Sliding Applications

Abstract

Cu alloys such as bronze have long been used as bearing materials because of their good run-in properties for steels used as mating materials. These Cu alloys are also suitable for various applications: High-strength brass castings and phosphorus bronze castings are used for their ability to obtain higher strengths, whereas Pb–bronze castings are used for anti-seizure applications. To prevent scoring and seizure, base materials such as Cu alloys were often combined with a solid lubricant. In this study, the tribological properties of sulfide-dispersed bronze were investigated. Friction tests were conducted under dry conditions for bronze with/without sulfides. It was found that seizure was prevented in sulfide–bronze systems only under certain test conditions. It was estimated that the dispersed sulfide restricted the transfer of the Cu alloy elements to the mating steel surface. Moreover, the addition of Si to a Cu–Fe–S system and to sulfide-dispersed bronze resulted in crystallization of Fe–Si compounds. The hardness and anti-wear properties of the compounds were also improved.