Microstructure and nanomechanical properties of TaN coating prepared by RF magnetron sputtering

In this work, TaN is coated on the high-speed steel substrates at 500 °C using radio frequency magnetron sputtering and its microstructural and nanomechanical properties are examined. The structural, surface morphology and mechanical properties are analyzed by X-ray diffraction, atomic force microscopy and nanoindentation, respectively. X-ray diffraction studies indicated the presence of hexagonal Ta₂N and cubic TaN phases at 5 sccm nitrogen flow at room temperature. It shows that the film prepared at 2 sccm and 500 °C revealed the strong intensity peak of FCC TaN phase, while the film prepared at 10 sccm and 500 °C showed that the broad peak demonstrating the nanocrystalline nature of the film. Atomic force microscopy analysis indicated the formation of crystallites of uniform size and homogeneous distribution. The surface roughness is ~ 2−6 nm in all the deposition conditions. The hardness of the TaN films has increased from 9.46 ± 1.15 to 30.05 ± 3.79 GPa with decreasing N₂ flow rate from 10 to 2 sccm. The microstructure depends on the preparation technique, processing parameters and nitrogen content in the films. TaN coating on high speed steel increased the hardness resulting the increase of wear resistance of the tool, leads to increase of the tool life.