Anti-friction and wear properties of the friction surface of M50-10 wt %(50Sn40Ag10Cu) composite

As the main steel used in aircraft bearings, tribological properties of M50 directly affect the performance of aero-engines. In this paper, the anti-friction and wear properties of friction surface of M50-10 wt %(50Sn40Ag10Cu) composites (MSACC-2) sliding against Si3N4 ball from 25 to 450 degrees C were investigated. XRD, XPS, EPMA, FESEM, and EDS mapping were conducted to understand the major mechanism leading to the improvement in the sliding behavior of MSACC-2. Results show that the surface of MSACC-2 exhibits excellent anti-friction and wear performances from 25 to 450 degrees C. At 350 degrees C, MSACC-2 shows the best tribological performance (0.18-0.27, 1.5-2.2 x 10(-6) mm(3) N-1 m(-1)). It is attributed to the formed lubricating structure on the friction surface which is composed of the upper surface lubricating layer and underneath load-bearing layer. The surface lubricating layer mainly contains massive added Sn-Ag-Cu, intermetallic compounds of Cu6Sn5 and Ag3Sn produced during the preparation process, and FeSn, FeSn2 and oxides formed in friction process. The load-bearing layer can support the surface lubricating layer to play an outstanding anti-friction and wear effect. Moreover, the martensitic phase transformation on surfaces caused by Sn-Ag-Cu and the action of cyclic stress of Si3N4 balls makes MSACC-2 have more excellent wear resistance performance. (C) 2018 Elsevier B.V. All rights reserved.