Study of BN formation by dual implantation of boron and nitrogen in a 100Cr6 bearing steel

Boron nitride (BN) layers are well known to present interesting and various coating properties depending on their crystallographic structure. The aim of this work was to synthesize a surface layer containing BN compounds by dual implantations of boron and nitrogen in a 100Cr6 bearing steel. So as to superimpose both profiles, the implantation energies were 65 and 110 keV for boron and nitrogen respectively. The implantation fluences were ranging between 2 x 10(17) and 3 x 10(17) ions cm(-2). Nuclear backscattering spectrometry at 6.04 MeV was used to determine the distribution profiles of the implanted elements as well as to control the concentrations of contaminants carbon and oxygen. X-ray photoelectron spectroscopy analyses were carried out in order to reveal the formation of BN and its crystallographic structure (hexagonal or cubic). The effect of the current density as well as that of the implantation sequence (B + N or N + B) on the amount and structure of the BN phase were also investigated. It was shown that both these parameters have a combined influence on the BN phase structure. For the highest current density and the N + B sequence, the cubic structure is predominant, whereas for the lowest current density and the other sequence, the hexagonal phase is mainly formed.