Adhesion strength and high temperature wear behaviour of ion plating TiN composite coating with electric brush plating NiW interlayer

Adhesion strength and high temperature wear behaviour of ion plating TiN composite coating with electric brush plating NiW interlayer deposited on a hot work die steel were investigated using a plate-on-ring test rig. The microstructure and wear characteristics of the coating were analyzed using XRD, TEM, SEM and EDS. The adhesion of the coating to the substrate was determined by scratch test. The results indicated that crystallization and precipitation-hardening in the electric brush plating NiW interlayer and formation of interface diffusion layer and duplex composite layer at the interface occurred due to thermal effects during TiN deposition. The NiW interlayer could provide an effective support for the TiN coating, thus the adhesion strength and hardness of the TiN composite coating increased significantly. In the temperature range 500–700°C, the TiN composite coating with NiW interlayer revealed high wear resistance as compared with the single TiN coating. The coefficient of friction and wear rate of the single TiN coating increased as the temperature increased, while the TiN composite coating exhibited the lowest coefficient of friction and wear rate at 600°C. Abrasive and adhesive wear were the predominant wear mechanisms of the coatings at elevated temperatures.