SURFACE MODIFICATION OF AUSTENITIC STAINLESS-STEEL BY TITANIUM ION-IMPLANTATION

The wear properties of AISI 316 austenitic stainless steel implanted with Ti were investigated for ion doses in the range (2.3-5.4) x 10(16) ions cm(-2) and average ion energies of 60 and 90 keV. The implanted layer was examined by Rutherford backscattering, from which the retained doses were determined, and glow discharge optical emission spectroscopy. Following implantation, the surface microhardness was observed to increase with the greatest change occurring at higher ion energy. Pin-on-disc wear tests and associated friction measurements were also performed under both dry and lubricated conditions using applied loads of 2 N and 10 N. In the absence of lubrication, breakthrough of the implanted layer occurred after a short sliding time; only for a dose of 5.1 x 10(16) ions cm(-2) implanted at an average energy of 90 keV was the onset of breakthrough appreciably delayed. In contrast, the results of tests with lubrication showed a more gradual variation, with the extent of wear decreasing with implant dose at both 2 N and 10 N loads. Finally, the influence of Ti implantation on possible wear mechanisms is discussed in the light of information provided by several surface characterization techniques.