Functionally graded "Ti-base + (Ta, Ta2O5 )-coatings" structure and its production using induction heat treatment

On the surface of the "Ti-base + Ta-coating" layered system, tantalum oxide coatings were obtained by induction heat treatment (IHT) within 600-1600 degrees C for 1-120 s. It was established that in the entire range of temperature and duration of IHT, the highest oxide with an oxygen concentration C-[O] = 70.35-72.48 at.% was formed on tantalum. An oxide coating without cracks having an average grain size D-G = 170-340 nm and pore size D-p = 130-150 nm was formed at T = 1000-1050 degrees C. With an exposure time t = 30-120 sin the temperature range from 850 to 900 to 1000-1050 degrees C, high hardness values about 39-47 HRA (105-135 HV) for the tantalum layer and about 69-84 HRN15 (240-495 HV) for the near-surface layer were noted. These samples also had a superhard oxide coating with H-0.1 = 55.27 +/- 16.00 GPa and H-0.1 = 39.09 +/- 13.10 GPa. The results of the study of these samples showed that high microhardness of 1579 +/- 537 HV0.2 combined with high Rockwell hardness and low defectiveness of the oxide coating allowed the creation of a mechanically stable "Tibase + (Ta, Ta2O5)-coating" layered system.