A Novel Method for Quantitative Determination of Ultra-low Wear Rates of Materials, Part I: On Steels

A novel method for the quantitative determination of the wear of materials at very low wear rates is introduced here. The main concept involves implanting gold as a trace marker into the tested materials, and measuring the gold concentration and depth profile before and after the wear tests by Rutherford backscattering (RBS). The amount of gold loss is related to the material loss under the tested conditions. The background concentration of gold in AISI 1095 and 52100 steels has been determined by neutron activation analysis (NAA; ~3 and 33 wt. ppb, respectively). Several fluences (1 × 1015–1 × 1016 atoms/cm2) of gold were implanted into AISI 52100 steel samples in order to evaluate the changes in the mechanical and tribological properties induced by implantation. The new method shows the relative effectiveness for wear prevention of the different tested lubricants with and without antiwear additives. Even the thickness of the antiwear film and the amount of zinc (from zinc dialkyldithiophosphates used as antiwear additives) can be measured by this method.