TRIBOLOGICAL BORON CONCENTRATION PROFILES AT HARD STEEL SURFACES STUDIED BY SIMS

The samples for this analysis are hard steel machine elements. They ha ve been treated with boron as an additive of the lubricant during part of the contact process in a tribological test rig, in order to create wear resistant surfaces. After the tribological procedure the surface s are examined for their in-depth concentration profiles of oxygen, ca rbon, sulphur, iron and boron. This analysis is done with SIMS, using positively charged O-2 and Cs ion beams for erosion, and controlled B- 11 implantation in the base material for calibration of sputter depth and boron concentration. For the present samples the native surface ox ide concentration profile is found to enhance the signals considerably at the beginning of the SIMS measurements. This effect is discussed a nd tentatively corrected for through the observed C-12 profiles. Compa rison with TRIM-simulated profiles for the implanted samples shows tha t the suggested correction procedure clearly improves the results for the boron profiles. It therefore becomes possible to quantify the shal low boron concentration profiles and to relate them to the tribologica l properties of the surfaces.