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 N-2 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 nano indentation 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 N-2 partial pressure. The hardness and cohesion of the coating increase gradually with increasing N-2 partial pressures and reach a peak at 0.6 Pa; then the hardness and cohesion are significantly lower at higher N-2 partial pressures.