For studying the effect of metal Ni and Cu co-doping on the toughness of CrBN coating, Ni-Cu-CrBN coatings with different Ni/Cu ratios were prepared by closed field unbalanced magnetron ray method.The structure of the coating was analyzed using transmission electron microscopy(TEM), presenting that the coating was a nano-composite structure composing of CrN crystal and amorphous matrix.With decreasing Ni content and increasing Cu content, the hardness of CrBN coating(H)decreased from 24.6 GPa to 12.1 GPa, but plastic deformation capacity(Dp)as well as resistance to circle cracks was enhanced.Combined with finite element emodel(FEM)analysis, there were three reasons for the improvement of the ability of the coating to resist circle cracks.The first and main reason was the weakening degree of indentation sink-in condition due to smaller performance difference between the coating and substrate.The second reason was the more uniform distribution of the tensile stress.The third reason was the increasing plastic deformation ability of the coating with the increasing Cu content.The above results showed that the similar mechanical properties between the coating and the substrate could effectively resist the generation of circle cracks.
