Dense plasma focus ion-based titanium nitride coating on titanium

Abstract

We report the synthesis of titanium nitride coating on a titanium substrate by utilizing energetic nitrogen ions emitted from a 2.3kJ dense plasma focus device for 30 focus shots. The number of nitrogen ions transferred to the sample by a single ion pulse of about 140ns duration in the energy interval (40–600keV) is about 1.09×1012 with a mean energy per ion of 58keV. The corresponding energy flux delivered to the titanium surface is estimated to be 6.17×1014keVcm−3ns−1 leading to a transient temperature rise of the top layer of about 5400K which helps layer growth. The coating is investigated on the basis of its morphological, compositional and hardness properties. X-ray diffraction analysis of the sample reveals the formation of a nanocrystalline titanium nitride coating having (111) and (200) plane reflections with an average crystallite size of 40nm. The compressive residual stresses in the nitride coating have been evaluated to be 2.80GPa and 6.81GPa corresponding to (111) and (200) plane orientations. A complete restructuring of the manually polished titanium substrate has been observed with appearance of nano-sized multidimensional granular surface morphologies. The thickness of the nitride coating is about 1μm, whereas the coating has a nitrogen content of 35.35at.% and 13.78±3.57wt.% and a surface hardness of 8.19GPa.