Microstructure and properties of Ni-based self-lubricating coatings by laser cladding/friction stir processing

Journal article, 2021

The KF-2-WC-CaF2 Ni-based self-lubrication coatings were synthesized on the surface of 6061 aluminum alloy with preset powder by laser cladding / friction stir processing (FSP). OM, SEM, EDS and XRD were used to characterize the phase constituents, microstructure and properties of the coatings, and the micro-hardness distribution and wear properties were also analyzed. The results showed that smooth and good metallurgical bonding zone is formed between the coating and the substrate. The microstructure of the one-stepped coating is dendrite, cell crystal, columnar crystal and equiaxed crystal. The main phase constituents of the two-stepped coating consist of α-Ni, α-Al, AlNi3, Al3Ni2, WC and CaF2. And the micro-hardness is significantly higher than that by direct laser cladding. With the increase of distance between coating and stirring tool, mechanical effect gradually weakened, micro-hardness curve and friction coefficient showed a gradient feature along the thickness direction.