Sliding-motion experiments under unlubricated conditions have been carried out on various metals, and the results are discussed in terms of the simple wear theory advanced by Archard.
Oxide-film formation has been studied by electrical contact-resistance measurements made in conjunction with wear tests. The effects on the wear rate and basic wear formula are discussed. For the ring apparatus, a modified expression for the wear formula is suggested to incorporate surface oxidation.
Although it was found that the sliding of a soft material on a hard material follows simple wear rules, discrepancies are reported for the wear of brass against brass. In these experiments, the wear rate is affected by the geometry of the apparent area of contact.