Microstructure and tribological performance of a dimpled gradient nanoscale TiN layer

The dimpled gradient nanoscale TiN (nano-TiN) layer was prepared on the pure Ti surface by the combined process of supersonic fine particles bombarding (SFPB) and glow-discharge plasma nitriding. A large numbers of dimples (30-40 µm in diameter) homogenously distribute on the prepared nano-TiN layer surface and are beneficial to the reservation of oil and wear debris during friction process. The nano-TiN layer is about 25 µm in thickness with a three-layered nanoscale structure and the grain size decreases sequentially from the outer layer to the inner one. The nano-TiN layer with higher mechanical properties displays enhanced friction and wear reducing effects compared to the SFPB-dimpled Ti surface.