Effects of friction on tribo-magnetization mechanisms for self-mated iron pairs under dry friction condition

Abstract

The effects of friction on tribo-magnetization mechanisms for self-mated iron pairs under dry friction were experimentally investigated in this study. By comparing the effects of sliding speeds and normal loads on surface magnetization, the physical contradiction in frictional magnetization can therefore be classified. Results showed that severe friction phenomena are the prerequisite conditions for tribo-magnetization to occur. The maximum dynamic saturated value of tribo-magnetization for the self-mated iron pairs during the friction process was found to be only about 18 G but rapidly decreased to the range of 0-1 G after the test. It was also found that tribo-magnetization decreased significantly with increasing sliding speed. This was due to a rise in surface temperature and the presence of oxide materials at the actual contact areas from higher sliding speeds. The magnetic domains were also randomly oriented due to thermal vibration, which explained surface demagnetization with increasing sliding speed. In general, the average tribo-magnetization was inversely proportional to the sliding speed. Under small normal loads, tribo-magnetization was insignificant. For normal loads exceeding 30 N, the average tribo-magnetization increased linearly with increasing normal load. It was revealed that variations of the average tribo-magnetization coincided with wear losses under heavy normal loads. The reasons were that as the oxide film broke, fresh ferromagnetism was exposed to severe wear and material transfer. The orientation of the magnetic domains was caused by both frictional activation and the earth's magnetic field. Tribo-magnetization was thus significantly increased by friction and wear with increasing normal load. Finally, this study proposed two perspectives on energy and material to clarify the physical contradictions of the tribo-magnetization.