Studies on Nanocrystalline TiN Coatings Prepared by Reactive Plasma Spraying

Titanium nitride (TiN) coatings with nanostructure were prepared on the surface of 45 steel (Fe‐0.45%C) via reactive plasma spraying (denoted as RPS) Ti powders using spraying gun with self‐made reactive chamber. The microstructural characterization, phases constitute, grain size, microhardness, and wear resistance of TiN coatings were systematically investigated. The grain size was obtained through calculation using the Scherrer formula and observed by TEM. The results of X‐ray diffraction and electron diffraction indicated that the TiN is main phase of the TiN coating. The forming mechanism of the nano‐TiN was characterized by analyzing the SEM morphologies of surface of TiN coating and TiN drops sprayed on the surface of glass, and observing the temperature and velocity of plasma jet using Spray Watch. The tribological properties of the coating under nonlubricated condition were tested and compared with those of the AISI M2 high‐speed steel and Al2O3 coating. The results have shown that the RPS TiN coating presents better wear resistance than the M2 high‐speed steel and Al2O3 coating under nonlubricated condition. The microhardness of the cross‐section and longitudinal section of the TiN coating was tested. The highest hardness of the cross‐section of TiN coating is 1735.43HV100 g.