Tribological properties of laser surface cladding Ni-base alloy coatings under dry friction and seawater conditions

Ni-base alloy coatings were prepared on aluminium alloy 7005 by laser surface cladding (LSC). The tribological properties of the coatings under dry friction and seawater conditions were investigated. Results showed that the coatings contained the phases of NiAl, NiAl3, Al3Ni2 and a few Cr23C6 and CrB. Compared with atmosphere plasma spraying (APS) Ni-base alloy coatings, LSC Ni-base alloy coatings exhibited higher microhardness, interfacial adhesion and cohesion force, and smaller friction coefficients and wear losses. The wear mechanisms of LSC Ni-base alloy coatings changed from micro-cutting wear into multi-plastic deformation wear, adhesive wear and oxidative wear as loads increased in dry friction. In seawater environment, LSC Ni-base coatings experienced micro-cutting wear and pitting corrosion wear at the loads of 3∼6 N, and multi-plastic deformation wear and local fracture wear at the loads higher than 9 N.