Sliding wear behavior of copper–graphite composite material for use in maglev transportation system

Abstract

This paper reports the study of sliding wear behavior of a copper–graphite composite material (CGCM) for use in maglev vehicles and high-speed railway trains, prepared by means of the powder metallurgy method. The investigated samples were formed by cold pressing at 300 MPa, followed by sintering (950 °C × 3 h) in a hydrogen atmosphere. After specimens were cooled to room temperature with the furnace, a second pressing was performed at 300 MPa. Wear tests were conducted under laboratory conditions with a specially designed sliding wear apparatus, which simulated the tribological conditions of sliding current collectors in a maglev system. The material was slid against a stainless steel band under unlubricated conditions. Worn surfaces of the material were analyzed by scanning electron microscopy (SEM) and field-emission-gun environment SEM (ESEM) equipped with an energy dispersive X-ray spectroscopy (EDS). Within the studied range of normal pressure and electrical current, the wear loss increased with the increasing normal pressure and electrical current. Adhesive wear, abrasive wear and arc erosion were the dominant mechanisms during the electrical sliding. It provides a better understanding principle of design suitable sliding counter parts for the current collection device in maglev systems.