Coating made of a chromium-nitrogen alloy for confering good tribological properties to a substrate and process for its manufacture

摘要

The substrate coating of the invention is intended to impart good tribological properties to the substrate and consists of an alloy of chromium and nitrogen containing, per 100 atoms, from 87 to 68 atoms of chromium and 13 to 32 atoms of nitrogen. This alloy is two-phase, with a cubic monocrystalline chromium phase containing included nitrogen and a tetragonal chromium nitride phase with stoichiometric deficiency in relation to the nitride Cr2N. The ratio of the lattice constants of this tetragonal nitride is between 1.02 and 1.5. This tetragonal nitride was unknown hitherto and can probably exist only in combination with chromium. It withstands wear up to 5 times better than the known single-phase chromium-nitrogen alloys and does not exhibit the brittleness inherent in two-phase alloys containing hexagonal nitride Cr2N. …??These coatings are obtained by magnetron cathode sputtering of chromium, with a partial pressure of nitrogen in a rare gas atmosphere which is between a maximum and a minimum which are determined by experiment.