The effects of non-friction time and atmosphere in friction/non-friction areas on the wear of metals

In repeated sliding wear tests of the pin-on-disk type, all of the wear track of the disk is not simultaneously in sliding contact with the pin. Accordingly, except for the actual duration of the contact, the disk is not sliding against the pin. We call this period the “non-friction time”. The present paper demonstrates that metals exhibit higher wear with increased non-friction time in severe wear mode. The mechanisms will be discussed with regard to the role of atmosphere in friction/non-friction areas. The effects of atmosphere around the friction area and the non-friction area are presented; oxygen atmosphere in the friction area increases severe wear, on the other hand, oxygen atmosphere in the non-friction area is influential for mild wear.