Strengthening the mechanical properties and corrosion resistance of Ni[sbnd]W coatings by PDA-functionalized h-BN nanosheets

Abstract

PDA-functionalized h-BN nanomaterials (Ph-BN) were used to reinforce the electrodeposited NiW coatings. Compared with the h-BN nanomaterial, Ph-BN has better dispersion in the plating solution, which can effectively improve the mechanical and corrosion resistance of the coating. Compared with the NiW coating, the microhardness value of the Ni-W/Ph-BN coating (662.8 Hv) was increased by 33.47 % and the friction coefficient (0.382) was reduced by 41.86 %. This is due to the special ceramic composite layered structure of Ph-BN namely the combination of flexible unit PDA structure and rigid unit h-BN structure, which will synergistically hinder the shedding of the coating during the friction process and help to improve the wear resistance of the coating. The Rct value of Ni-W/Ph-BN is 34,500 Ω•cm2, which is 105.36 % higher compared to NiW coating. Ni-W/Ph-BN also has the smallest corrosion rate (0.0465 mm•a−1), which is 45.74 % lower relative to NiW coating. The uniformly dispersed Ph-BN nanosheets in the coating prolong the corrosion path for corrosive ions. Besides, the PDA has the effect of anchoring Fe2+/ Fe3+, which will be beneficial for the composite coating corrosion resistance improvement.