Preparation of titanium nitride films by reactive ion plating and the influence of discharge current density on the film properties

Abstract

Hard, adhesive and dense titanium nitride coatings were prepared in a triode ion-plating system. This work shows and explains the influence of the discharge current density on the film characteristics. Microstructure, densification, crystalline composition and hardness are functions of the chosen value for the discharge current density. For example, for 0.7 mA cm −2 with a nitrogen pressure of 7.5 × 10 −2 Pa and a negative cathode bias of 2 kV; the phase Ti 2N is the most important quantity and the deposit is the hardest ( ≈ 2500 kg mm -2 ). Deposits produced with a density of 0.6 mA cm −2 contain a predominant amount of titanium metal, are porous and have a columnar structure. On coatings produced with upper values ( ≈1 mA cm −2 ) the columnar structure is not seen and only phase TiN is detected. These different results may be explained by the role of the discharge current and the control of ion bombardment of the substrate during the film growth process.