Effects of selective transfer on friction and wear of magnetised steel–graphite sliding couples

This paper reviews the selective transfer in dry friction of the steel XC48rgraphite couple submitted to a magnetic field perpendicularly to the sliding surface in open air of 20% RH at room temperature and in vacuum under 3P10y3 Pa. Basis on 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 presents a good adhesion on steel surface and leads to the best reduce in wear and in friction coefficient. However, when the friction test is operated in inert environment and in presence of a magnetic field, the opposite phenomenon is observed. The transfer of harder steel to a softer graphite surface is responsible for the increase of friction and wear. This abnormal process is due to a magnetisation of a ferromagnetic steel which is known to be accompanied by reduction of plasticity and increasing brittleness. q1999 Elsevier Science B.V. All rights reserved