Superhard metallic coatings

摘要

The letter reports on the surface hardening of bulk soft metal materials by protective coatings made of the same metal as bulk but with up to 6 times higher hardness than that of the bulk material. This surface hardening is demonstrated by covering of the Ti substrate with a low hardness H-b(ulk) approximate to 5 GPa by a 1200 nm thick Ti coating with a high hardness H-coating approximate to 30 GPa. The protective hard Ti coatings were sputtered by a new sputtering technology based on extremely high pressures (= 1000 GPa), high temperatures exceeding the melting temperature T-m of the coating material and extremely high cooling rate of the created coating (= 10(10) K/s). The principle of this technology realized at an atomic level is described in detail. (C) 2019 Elsevier B.V. All rights reserved.