Influence of Nitrogen Partial Pressure on the Microstructure and Properties of TiN Coatings

TiN coatings were prepared by using multi-arc ion plating technique at different N2 partial pressures. The surface morphology of the coatings was characterized by using a tabletop scanning electron microscope. The cross-sectional microstructure was investigated by using a field emission scanning electron microscope. The phase composition was evaluated by using an X-Ray diffractometer. The hardness and cohesion were measured by using a nanoindentation tester and a scratch instrument, respectively. The results show that the number and size of macro-particles decrease and the compactness of TiN coating increases with the increase of the N2 partial pressure. The hardness and cohesion of the coating increase gradually with increasing N2 partial pressures and reach a peak at 0.6 Pa; then the hardness and cohesion are significantly lower at higher N2 partial pressures.