Synthesis of New Cu-based Self-lubricating Composites with Great Mechanical Properties

Abstract

New copper-based self-lubricating composites consisting of different quantities of graphite are prepared by means of powder metallurgy using a designed atomizing Cu-10Ni-3Sn-3Pb (wt.%) alloy with 0.5 wt.% Y₂O₃ as the matrix. Microstructures and properties of the composites are studied by scanning electron microscopy, X-ray diffraction, a hardness tester, and a wear tester. The results indicate that the composites sintered at 910°C for 4 h have the best mechanical properties. The composites prepared under such a condition are mainly composed of α-solid solution together with some CuNi ₂Sn, Pb, and graphite phases. Here, Ni and Sn play the reinforcing role in the materials by either dissolving into the Cu matrix or forming the second phase with Cu, while Pb and graphite as inclusions act as the lubricating phases. The composites have hardness but deteriorated wear and self-lubricating performance with the increasing graphite content. The composite with 1 wt.% graphite possesses better mechanical and frictional properties, while the composite with 2% graphite possesses better self-lubricating properties. These Cu-based composites with low friction coefficient and enough strength are suitable for the application as surface lubricating film to run under a dry friction condition.