On high dose nitrogen implantation of PVD titanium nitride

A 3 × 3 matrix of samples has been ion implanted with nitrogen at low-to-high doses and low-to-high current densities (dose rates). All samples show surface exfoliation which results in a loss of the implanted nitrogen and a consequent loss of the wear-resistant properties-a condition of over-implantation reminiscent of that observed with metal ion implantation. There is an uptake of post-implantation oxygen which is believed to form an amorphous TiO₂ component in the surface leading to the well-established low frictional properties. This uptake decreases as the dose rate is increased and would lead to a loss of wear resistant properties. The work confirms that a dose of 3 × 10¹⁷ ions cm^{- 2} is optimal provided that the dose rate does not exceed the present industrial standard.