Tribological studies on bearings implanted by N and B ions

Significant improvements of wear resistance for rotating systems are obtained using ion implantation. Our studies performed in co-operation with Institute de Physique Nucleaire de Lyon (France) consist in surface treatments of 100 C6 steel by ion implantation, leading to changes in tribological properties. Rings of axial pressure bearings were implanted using N, B and N + B ions. Doses of 2-3 x 1017 ions/cm2 in the energy ranges of 30-50 keV and 110-170 keV and current intensities of 20-30 μA were employed. Wear analysis was carried out using concentration measurements by Thin Layer Activation method. The following installations, were employed: - device for uniform irradiation of bearings; - device for check up of activation uniformity; - wear measuring stand for rotating systems under load. Three balls on the bearing ring, motor coupled, have been totally blocked. Sliding friction forces are present, producing a severe seize up of bearing. The motor has 2400 r.p.m, the load was 45 N/ball, and M20W40 oil was used as lubricant oil. The motor works in 2 min. steps. Between steps, gamma spectra of wear particles carried by the lubricant were recorded, using a Na(I) detector and a multichannel analyzer. The preliminary results show an optimum situation for nitrogen ion implantations, which leads to wear 3-8 times lower than in other ion implantations. (authors)