Abstract
The surface composition of low alloy steel after + N2 implantation was studied with X-ray photo-electron spectroscopy (XPS). The effect of the implantation on the mechanical hardness was evaluated by ultra-micro hardness indentation. Chemical characterisation of the surface indicated that a thin layer rich in N, C and Si was formed. It is shown that Fe played little role in the chemical composition and the structure of the modified surface. The mechanical hardness of + N2 implanted surface was 35SOH50 GPa compared with a value of 10 GPa for the untreated sample. It is thought that the high hardness observed on the surface and in the sub-surface was as a result of chemical modification to form a film of Si doped carbon nitride. There is strong evidence from the XPS and the nanoindentation studies that the bonding structure of the C-N in the near surface is essentially sp3 types expected in crystalline C3N4. The value of nitrogen ion implantation as process for improving the wear resistance of low alloy steels is emphasized.