Effect of ion peening and pulsed plasma nitriding on the structural properties of TiN coatings sputtered onto 100Cr6 steel

Ion peening with noble gas is typically used to generate lattice imperfections and a nanostructure within the bombarded metal surfaces. This might have therefore an impact on subsequent plasma nitriding, thus allowing for enhancing the adhesion and wear resistance of hard ceramic coatings deposited onto steel surfaces. In this work, the influence of pre-treating a 100Cr6 steel surface by Xe+ ion bombardment and pulsed plasma nitriding was investigated with respect to surface roughness, wear resistance and residual stresses of thin TiN coatings deposited by reactive ion beam assisted deposition.Xe+ ion bombardment was carried out using a 400 eV acceleration energy produced by a broad Kaufman cell and subsequent thermo-chemical nitrogen diffusion was accomplished at 520 degrees C. The results show that Xe+ ion bombardment intensifies nitrogen diffusion without inducing significant changes in the substrate topography. The combined pre-treatment with Xe+ ion bombardment and subsequent pulsed plasma nitriding leads to a reduction of compressive stresses in the TiN coatings. The presence of porosity in the white layer diminished the wear resistance.