Duplex coatings with enhanced adhesion to Ti alloy substrate prepared by powder immersion nitriding and TiN/Ti multilayer deposition

Novel duplex titanium nitride-based coatings were produced on Ti6Al4V alloy by sequential PIRAC (powder immersion reaction assisted coating) nitriding and physical vapor deposition of multilayer TiN/Ti films. Extra load support provided by PIRAC nitrogen-hardened substrate resulted in superior coating adhesion and load-bearing capacity as demonstrated by 3-point bending, scratch test and Vickers indentation. The proposed duplex coating approach is suitable for applying hard, thick TiN layers with good interface quality and strong adhesion to soft titanium substrates. Such coatings appear to have a great potential to improve the performance of Ti alloys under conditions of abrasive wear and erosion.