Preparation and characterization of TiN coatings produced by combination of PI3D and ICP assisted magnetron PVD

Low pressure (0.5–1 mTorr), low temperature (50–100 °C) process combining plasma immersion ion implantation and deposition (PI3D) and reactive magnetron PVD, both conducted in ICP media, has been applied to prepare TiN films on hard stainless steel and tungsten carbide (WC–Co) substrates. The process comprised nitrogen plasma immersion ion implantation at the pulse bias of −25 kV, 3 μs to the incident dose of 3×1017 atom/cm2, followed by formation of (Ti+TixNy) buffer layer using ICP-magnetron PI3D at the pulse bias of −5 kV, 3 μs. Finally, TiN film was formed by ICP-assisted reactive magnetron PVD at the DC bias of −200 V. The prepared TiN films were stoichiometric (N/Ti≈1.1) and had dense structure with (1 1 1) main peak. Scratch test did not reveal strip-off or crack spread. The coatings had superior hardness and wear resistance. Both characteristics were found to improve when some amount of nitrogen was added to argon at the stage of the buffer layer formation, which is attributed to formation of Ti2N.