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

ABSTRACT

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.

KEYWORDS:

• WC-Co substrate
• TiN/TiCN/Al₂O₃/TiCNO multilayer coating
• grain size
• hardness
• adhesion strength
• oxidation resistance
• wear resistance
• residual tensile stress

Acknowledgements

The authors would like to thank Kennametal Inc. for providing research funding and testing samples. The authors would like to thank Mr Qinglu Liu and Miss Tingting Si in Shanghai University for the help during the experiments. The authors also would like to thank Prof. Jinlong Li in Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences for providing the help in the measurement of nano-hardness, adhesion strength and tribological property.

Disclosure statement

No potential conflict of interest was reported by the author(s).