Effects of CeO₂, Si and Co on the microstructure and properties of Ni–Cu composite coating on 6061 aluminium alloy by laser cladding

ABSTRACT

Ni–Cu composite coatings have been fabricated on a 6061 aluminium alloy surface using a pulsed Nd-YAG laser. The basic coating was Ni–Cu powder with a Ni:Cu ratio of 4:1. The effects of adding to this powder 0.9 wt.% CeO₂, 0.9 wt.% Si and 0.9 wt.% Co on the microstructure, microhardness and wear properties of the coatings have been investigated. The results show that, on adding the CeO₂, Si or Co powders, the microstructure of the top region of the coating is mainly composed of equiaxed grains, dendritic crystals and fine equiaxed crystals, whereas the bottom region mainly consists of long rod-like, dendritic crystals and some particles. The average microhardness of the 99.1 wt.% Ni–Cu + 0.9 wt.% CeO₂ coating is 529.05 HV, which was about four times higher than that of the bare 6061 aluminium alloy. In addition, the average friction coefficient decreased on adding CeO₂, Si and Co powder to the Ni–Cu composite coating.

KEYWORDS:

• Aluminium alloy
• coating
• microhardness
• wear
• friction coefficient

Acknowledgements

The authors would like to acknowledge the National Natural Science Foundation of China (U1810112).

Disclosure statement

No potential conflict of interest is reported by the authors.

Additional information

Funding

This work was supported by National Natural Science Foundation of China [grant number U1810112].