Nitrogen Doping into Thin and Thick Coatings for Nano-structuring and Nano-texturing by Plasma Immersion Nitriding

A thin gold film, a polycrystalline diamond (PCD) coating and a carbon-supersaturated thick SiC (Silicon Carbide) coating, were nitrogen-doped or N-doped by using the plasma immersion nitriding. The N-doped gold thin film was characterized by lattice straining up to 3–5% and by hardening to 300 HV via the massive nitrogen supersaturation (MNS). The N-doped PCD was nano-textured to have a fine acicular-texture array on the PCD surface via self-organization process. The massively carbon supersaturated (MCSed) SiC thick coating was N-doped to have carbon-rich clusters along the 6H-structured SiC grain boundaries. The masking technique was employed to describe the difference in microstructures and electric resistivity between the N-doped and undoped MCSed SiC coatings. N-doping induced the reduction of SiC grain size, increased the stacking fault density in the SiC grains, and formed more carbon-rich clusters along the SiC grain boundaries. The electric resistivity was reduced to 1/2 to 1/3 by this N-doping.