EFFECTS OF ELECTRICAL CURRENT AND ITS POLARITY ON THE PROPERTIES OF FRICTION AND WEAR OF COPPER--IMPREGNATED METALLIZED CARBON

Abstract

Copper-impregnated metallized carbon has been widely used in maglev vehicles and high-speed railway trains due to its excellent electrical conductivity and high mechanical strength. The wear of copper-impregnated metallized carbon has aroused wide concern. To decrease the cost of maintenance and keep trains running safely, a better understanding of the wear mechanisms is needed. In this work, the effects of electrical current and its polarity on sliding friction and wear of copper- impregnated metallized carbon against Cr-Zr-Cu alloy rings were studied on UMT-2 tribometer with a brush-on-ring configuration. SEM and EDS were used to observe the morphologies of the worn surfaces and analyze the compositions of worn surfaces. The results showed that the wear mass loss increased with the rising of electrical current, the friction coefficient with electrical current was lower than that without electrical current. The wear mass losses of positive brush specimens were higher than those of negative brush specimens. It was found that the surface damage of the worn surface of brush specimens became more serious with greater electrical current, the positive brush specimen suffered a heavier oxidation than that of negative brush specimen. Abrasive wear, adhesive wear and arc erosion were the dominant mechanisms during the electrical sliding process.