Oxide film formation in magnetized sliding steel/steel contact—analysis of the contact stress field and film failure mode

A magnetic field was applied to the sliding contact of ferromagnetic steel/steel on a flat pin/flat disc tribometer, and was found to significantly modify its tribological properties. A thick film of black oxide was formed on the material surface, considerably reducing the friction stress and hence the wear rate. Contact is changed from direct metal/metal to metal/oxide layer/metal. The oxide layer created on the disc undergoes continuous stress which can create damage. Analysis of the stress distribution at the surface and in the sub-surface of the disc shows that there is a high concentration of tensile stress behind the contact zone in the direction of the sliding and that oxide layer rupture occurs in this zone. This is evidenced by cracks appearing in the oxide layer.