金属バナジウムへの窒素イオン注入により生成する表面窒化薄層の特性

概要

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The surface composition depth profiles, chemical bonding and structure of a nitride layer in vanadium implanted with high doses of nitrogen ions were investigated. Nitrogen ions (N2++N+) were implanted into polycrystalline vanadium sheets in the dosage range of 3×1017∼1×1018 ions cm-2 at an accelerating voltage of 90kV. The implanted layers were characterized by means of Auger electron spectroscopy (AES), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Futhermore, the effect of the implantation on the embrittlement of cathodically hydrogen-charged vanadium was evaluated by measuring the formation of hydride.The formation of VN0.35 (bct) and VN (fcc) was found. The nitride composition changed continuously depending on the fluence level of the nitrogen ions and the depth from the surface. Composition changes were evaluated not only by the binding energy shift, but also by the full width of the half maximum (FWHM) of the XPS. The hydrogen absorption inhibiting effect of the nitride thin film was considered to be great. A dose of 5×1017 ions cm-2 was required to obtain the maximum hardness. When the fluence level exceeded its critical value, blisters appeared on the surface layer. High dose nitrogen ion implantation not only modifies nitride layer composition and the surface hardness, but also somewhat affects the surface topography.