Formation of a solid lubricant in boron carbide by nitrogen ion implantation and laser annealing

A boron nitride(lubricant)/boron carbide composite (approximately 70% boron nitride) has been formed in approximately the first 750 A of surface and near‐surface regions of a polycrystalline boron carbide sample by implanting nitrogen (N) ions at 100 keV with a total dose of 4×1017 N ions/cm2 followed by xenon chloride laser annealing. The composition and the profile of the boron, carbon, and nitrogen in the sample at various stages were determined by Rutherford backscattering spectrometry. During laser annealing, the deeply implanted N atoms diffused back toward the heated surface with about 50% of them remaining in the near‐surface region. Argon sputtering and x‐ray photoelectron spectroscopy measurements confirmed the formation and distribution of boron nitride.