The toughness evaluation of CrBN coatings doped with Ni or Cu by experiment and FEM

By adjusting the current of NiCr or Cu target (0.4–2.0 A), the CrBN-Ni and CrBN-Cu coatings with different Ni (4.35–19.62 at.%) or Cu contents (3.7–19.06 at.%) were deposited to compare the toughening effect of Ni or Cu. The results showed that as Ni or Cu content increasing, the hardness (H) of CrBN coatings decreased from 38.1 to 11.7 GPa, but the resistance to circle cracks was enhanced. By combining the results of experiments and finite element method (FEM), three reasons contributed to the enhanced resistance to circle cracks. The first and major reason was the weakening degree of sink-in condition. The second reason was the even distribution of tensile stress. The third reason was the enhanced plastic deformation ability after Ni or Cu incorporation. The above results indicated that the good matching of mechanical properties between coating and substrate was prone to resisting cracks.