Effects of N + B ion implantation on the tribological behaviour of GCr15 bearing steel

Abstract

The ion implantation of N + B (3.1 × 10 17 N ions cm -2 at 90 keV followed by 3.2 × 10 17 B ions cm -2 at 90 keV) into GCrl15 bearing steel was carried out. The phase structure and the distribution and binding energy of elements in the implanted layer were investigated using X-ray diffraction, Auger electron spectroscopy and X-ray photoelectron spectroscopy. The dry sliding friction and wear behaviour of the implanted layer and GCr15 bearing steel substrate was also examined in detail using a friction and wear machine. It is found that a surface layer with a lower friction coefficient and a higher wear resistance than the substrate was obtained by implanting N + B into GCr15 bearing steel. Because of dispersion strengthening of the hexagonal BN phase and ε-Fe 2N-Fe 3N phase and solid solution strengthening of B atoms, the surface hardness of the implanted layer is increased. As a result of the increased hardness and the existence of a graphite-like carbon film on the surface of the implanted layer, the antiadhesive and antiabrasive properties of the implanted layer were considerably enhanced. the friction coefficient was reduced from 0.60 to 0.20 and the wear resistance was also greatly improved.