Microstructure and tribological properties of electrodeposited Ni–Co alloy deposits

Ni–Co alloys with different compositions and microstructures were produced by electrodeposition. The effects of Co content on the composition, surface morphology, phase structure, hardness and tribological properties of Ni–Co alloys were investigated systemically. Results showed that the morphology and grain size of alloys are mainly influenced by the Co content and the phase structure of Ni–Co alloys gradually changed from fcc into hcp structure with the increase of Co content. The hardness of Ni–Co alloys with a maximum around 49 wt.% Co followed the Hall–Petch effect. It was found that the improvement of wear resistance of Ni-rich alloys with hardness increase fits Archard’s law. In addition, the Co-rich alloys exhibited much lower friction coefficient and higher wear resistance when compared with Ni-rich alloys. It has been concluded that hcp crystal structure in Corich alloys contributed to the remarkable friction–reduction effect and better anti-wear performance under the dry sliding wear conditions.