Study on Mechanical Properties of Cu-Bi Bearing Materials

Abstract

Cu-matrix bearing materials were prepared by powder metallurgy method and their mechanical properties were studied in present work. The continuity of copper alloy matrix was destroyed with the increase of Bi element. Because Bi is brittle phase and distributed in the copper alloy matrix grain boundaries as thin ribbon network. The hardness, crushing strength and impact toughness of copper-bearing materials were reduced with increase of the content of Bi. The mainly of Copper-bearing materials containing bismuth fracture are brittle intergranular fracture. When the Bi content is over 4wt%, the Bi has a relatively full distribution in the rich Bi phase of copper alloy matrix grain boundary like a chip mesh belt. As the further increase of Bi, the reduced trends of the mechanical properties of Cu-matrix bearing materials containing bismuth are slow down. because the role of fragmented Copper alloy matrix will not significantly increase with further increase of Bi.

Tribological performance optimization and synergistic lubrication evolution of Pb‐free FeS/Cu–Bi composites

“…Figure 10a,b present SEM and EDS images of the worn surfaces of CB and FCB, respectively. Figure 8a indicates that under the initial condition, the soft phase Bi was uniformly dissociated and distributed in a mesh shape at the grain boundary of the copper alloy because Bi is insoluble in copper and tends to segregate on the grain boundary of the copper alloy 3,4,23,24 . During the friction between CB and 304 steel, the microcracks expanded with the mesh Bi and copper alloy grain boundary edges, were delaminated, and eventually peeled off (Figure 10a).…”

“…Figure 8a indicates that under the initial condition, the soft phase Bi was uniformly dissociated and distributed in a mesh shape at the grain boundary of the copper alloy because Bi is insoluble in copper and tends to segregate on the grain boundary of the copper alloy. 3,4,23,24 During the friction between CB and 304 steel, the microcracks expanded with the mesh Bi and copper alloy grain boundary edges, were delaminated, and eventually peeled off (Figure 10a). The initial furrow morphology (280 s) of the CB material evolved into slight delamination wear; afterward, serious delamination, adhesion wear and slight furrow wear were formed.…”

“…During friction, Bi easily peels off from the friction surface under the action of external force, resulting in limited tribological properties of materials. [3][4][5][6] FeS with a hexagonal lamellar structure is a solid lubricant with low shear strength, high melting point and stable chemical properties, and it has been widely utilised in the surface modification of typical friction pair parts, such as gears, bearings and cylinder liners. 7 Li et al 8 prepared a Pb-free Cu-FeS (CF) selflubricating composite through mechanical alloying and studied its tribological properties.…”