Oxygen effect on the mechanical behaviors of Cr(N,O)/CrN double-layered coatings by cathodic arc evaporation

Cr(N,O)/CrN double-layered coatings synthesized by cathodic arc evaporation (CAE) process have been evaluated for a potential application in injection molding dies. The double-layered coatings were designed with CrN as an interlayer and Cr(N,O) as a surface layer. The Cr(N,O) coatings were deposited under the mixture of constant flow of N2 and various flows of O2. Well-adhered Cr(N,O)/CrN double-layered coatings were identified using a scratch test. The characteristics of the Cr(N,O)/CrN double-layered coatings were investigated by using XRD, SEM, tribological tests and water contact angle measurement. The XRD analysis shows Cr2O3 phase in the surface layer as the oxygen is introduced up to 46 sccm. The double-layered coatings exhibit an enhanced microhardness of 23 GPa comparable to CrN of 18.5 GPa. The tribological performance of the Cr(N,O)/CrN double-layered coatings also compares favorably with that of the CrN film. The water contact angle measurements revealed Cr(N,O)/CrN double-layered coating exhibited higher contact than CrN film.