Effect of a magnetic field on boundary lubrication

The effect of a magnetic field applied externally on boundary lubricating performance was investigated under sliding contact conditions by using a ball-on-disc type tester. It was confirmed by measuring the change in surface contact potential that the surface reactivity of a carbon steel was increased by magnetizing. The temperature at which the coefficient of friction rapidly rose was increased by applying the magnetic field to the rubbing surfaces. Hence, the resistance of the adsorbed films or the boundary films to thermal disturbance was enhanced in the presence of the magnetic field. The enhancement was detected only with oils containing polar substances. In contrast, for oils without polar substances, which have poor adsorption ability and whose molecules are not expected to be oriented in the direction of the magnetic field, the enhancement in boundary lubricating performance was not detected.