Superhard Ti-Ta-O coatings produced on titanium with electrospark deposited tantalum-containing layers using induction heat treatment

Tantalum-containing coatings on commercially pure titanium were formed by electrospark deposition (ESD) and subsequent induction heat treatment (IHT) with the duration from 30 to 120 s at the temperature from from 780-820 to 1100-1150 °C. ESD of the tantalum-containing layers and subsequent IHT at a temperature T = 950–970 °C with an exposure time t = 30 s ensured the formation of superhard (H = 60.12 ± 20.25 GPa) coatings with a content of tantalum of 4.08 ± 1.61 at.% and oxygen of 60.33 ± 1.73 at.%. The resulting Ti-Ta-O coatings were characterized by the presence of nanograins DG = 30 ± 5 nm and nanopores DP = 80 ± 16 nm on the surface, as well as the thickness of the hardened layer of about h = 50–70 μm.