Influence of electric contact strengthening on the microstructure and properties of electro brush plating Ni-P/nano-WC composite coatings

Ni-P/nano-WC composite coatings were fabricated through electro brush plating and were reinforced by electric contact strengthening (ECS). Then, the microstructures and properties of the composite coatings were investigated using optical microscopy, field emission scanning electron microscopy (FESEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and Vickers hardness testing. The analysis indicated that after the application of ECS, the bonding between the composite coating and the 40Cr substrate changed from mechanical bonding to metallurgical bonding. Furthermore, the grain sizes of the coatings were refined, and the pores and cracks in the coating were reduced. After the application of ECS, the average hardness of the coatings increased from 637 to 885HV0.1. The wear scar micrographs after rolling wear tests were analyzed, and the results demonstrated that the dense coating structure and high adhesion strength improved the coating wear performance. •Ni-P/nano-WC composite coatings were treated by electrical contact strengthening (ECS).•Metallurgically bonded composite coatings with low porosities and fine grains were obtained after ECS.•The coating microhardness increased with increasing contact current.•The microhardness distribution of the Ni-P/nano-WC composite coating became more uniform after 20kA ECS.•The wear resistance of the Ni-P/nano-WC composite coating increased with increasing contact current.