The effect of WC-Co substrates on TiN/TiCN/Al2O3/TiCNO multilayer coatings

In order to determine optimum substrate, TiN/TiCN/Al2O3/TiCNO coatings were deposited on WC-7Co substrate and WC-6Co substrate (named as Coating-7Co and Coating-6Co, respectively), and then the effect of WC-Co substrates on TiN/TiCN/Al2O3/TiCNO multilayer coatings was investigated by comparing the microstructure, hardness, adhesion strength, oxidation resistance and wear resistance of Coating-7Co and Coating-6Co. Results show that WC grain size of WC-6Co substrate is smaller, correspondingly the grain size of each layer in Coating-6Co is smaller, and the surface roughness is lower. Compared with Coating-7Co, Coating-6Co exhibits higher hardness, better plastic deformation capability, better oxidation resistance, lower friction coefficient and better short-period wear resistance. However, because of higher residual tensile stress and lower adhesion strength, the long-period wear resistance of Coating-6Co is worse than Coating-7Co conversely. To make good use of Coating-6Co, some post-deposition treatment techniques that can reduce residual tensile stress and improve adhesion strength should be considered.