Continuous determination of the wear-reducing effect of ion implantation on gears by the double-labelling radionuclide technique☆

Abstract The wear-reducing effect of ion implantation can be investigated with a high accuracy in a single experiment if implanted and unimplanted regions of a symmetrical wear part are subjected to the same tribological conditions. By labelling these different surface sections with individual radioactive tags it is possible to compare the wear behaviours of differently processed surfaces at the same time using modern radionuclide wear measurement techniques. This procedure is illustrated for a gear. In order to obtain some initial ideas of the wear-reducing effect of ion implantation on gears a conventional gear with 16 teeth was tested on the Forschungsstelle Zahnrad und Getriebe rig. For direct demonstration of the effect of implantation the eight teeth of one half of the gear were implanted with nitrogen ions over the tooth flanks, while the other eight teeth remained untreated. For the wear measurement by the two-component concentration method, one half of the gear was irradiated with deuterons to convert iron into 57 Co, and the other half was irradiated with protons of a different energy to convert iron into 56 Co. Both radionuclides are clearly distinguishable in the γ spectrum. During the 614 h test a high quality oil was used over all the load range of the standardized test rig; this mainly caused slight wear. The wear rates of the implanted half were up to 58% lower than those of the other half. The higher load showed a clearer distinction between the two halves. It is possible to measure continuously and simultaneously the wear on two different iron surface sections by the two-component concentration method in one test run. Depending on the load the wear of the gear can be reduced below 50% by ion implantation. A final judgement of the influence of ion implantation on pitting or fatigue wear on a gear is not possible before further investigations have been completed.