Improvement of tribological properties of 9Cr18 bearing steel using metal and nitrogen plasma-immersion ion implantation

Metal plasma-immersion ion implantation (PIII) employing an improved vacuum -arc plasma source is performed on 9Cr18 bearing steels. Titanium and tanta lum ions are implanted followed by nitrogen plasma-immersion ion implantati on to yield a modified surface layer with superior wear resistance. The sur face properties of the 9Cr18 bearing steel samples are evaluated by measuri ng the microhardness, wear properties and coefficient of friction. Elementa l depth profiles and the chemical composition of the modified layer are acq uired by Auger electron spectroscopy and X-ray photoelectron spectroscopy. The results show that the wear resistance of the samples implanted with (Ti + N) and (Ta + N) is better than that of the samples undergoing nitrogen P III alone. The XPS results indicate the presence of nitride phases in the i mplanted layer. In this paper, the new improvements made on the metal-are s ource are described. Using the new procedures incorporating both metal-ion and gas PIII, the surface properties of 9Cr18 bearing steel are significant ly improved. (C) 1999 Elsevier Science S.A. All rights reserved.