Deposition of Ti-N compounds by thermionically assisted triode reactive ion plating

Details are given of the influence of the ion current density on the properties of Ti-N compounds deposited at low temperatures (<600°C) by a thermionically assisted triode reactive ion-plating technique. As the chamber pressure increases, greater specimen currents are necessary, both to prevent the deposition of powdery TiN and also to ensure reaction for the formation of Ti₂N and TiN at lower partial pressures of nitrogen. The ionization efficiency, being related to both pressure and current density, is suggested as a suitable parameter for defining optimum conditions. An ionization efficiency of about 0.3% is identified as the minimum required for the deposition of cohesive TiN, whilst values above this improve the densification and the hardness.