Role of transferred layers in friction and wear for magnetized dry frictional applications

Abstract

Abstract Dry rubbing of the XC48 steel/graphite couple has been studied in the presence of a magnetic field and the results are compared with those obtained from similar experiments without magnetic field. In this study, employing a combination of scanning electron microscopy and energy dispersive X-ray spectroscopy, the authors explored the properties of the friction tracks of steel/graphite couple and described their friction and wear mechanisms in open air of 20–30% relative humidity at room temperature, in partial vacuum (3×10 −3 Pa) conditions and in argon (purity, 99.95%). From the analyses of experimental data, it is shown that in presence of active gases, the oxide layer growth and the transferred carbon films on the steel track are enhanced by a magnetic field. The carbon layer possesses good adhesion to the steel surface and leads to the best reduction of wear and friction coefficient. However, when the friction test is operated in inert environment and in presence of a magnetic field, the opposed phenomenon is observed. The transfer of a harder steel to a softer graphite surface is responsible for the increase of friction and wear. This abnormal process is due to a magnetization of a ferromagnetic steel which is known to be accompanied by reduction of plasticity and increasing the brittleness.