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 XC48 / graphite couple submitted to a magnetic field perpendicularly to the sli ding surface in open air of 20% RH at room temperature and in vacuum under 3 . 10(-3) Pa. Basis on the analyses of experimental data, it is shown that in presence of active gases, the oxide layer growth and the transferred ca rbon 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 reduc e in wear and in friction coefficient. However, when the friction test is o perated in inert environment and in presence of a magnetic field, the oppos ite phenomenon is observed. The transfer of harder steel to a softer graphi te surface is responsible for the increase of friction and wear. This abnor mal process is due to a magnetisation of a ferromagnetic steel which is kno wn to be accompanied by reduction of plasticity and increasing brittleness. (C) 1999 Elsevier Science B.V. All rights reserved.