Mechanical Properties of Cr–Ni–N Films Deposited on Pre-Nitrided Steels

Austenitic type 304 stainless steel was ion-nitrided and subsequently ion-plated with Cr-Ni-N whose Ni content was varied from 0 at% to 50at%. The ceramic film of CrN coated onto the pre-nitrided steel demonstrated good wear resistance even under a heavy load. Furthermore, a 10 μm thick CrN film exhibited the least wear among the 3 to 19 μm thick CrN films. The Cr-Ni-N films containing Ni were composed of mixed phases of Cr*N and Ni. Cr*N is a newly observed Cr nitride that may contain some Ni and has been identified as an f.c.t. structure. A Cr-Ni-N film with Ni content of 11 at% coated onto the pre-nitrided steel demonstrated the best wear resistance among the CrN film or Cr-Ni-N films with high Ni content. This superior wear resistance was maintained even at film thicknesses exceeding 20 μm, unlike the tendency of CrN film.