Electrodeposited Ni-B/SiC micro- and nano-composite coatings: A comparative study

摘要

Ni-B/SiC micro- and nano-composite coatings were electrodeposited in a modified watts bath containing SiC micro- and nano-particles with the average size of 3 mu m and 100 nm, respectively. The chemical composition, SiC content; X-SiC (wt.%), morphology, surface roughness, thickness, hardness and corrosion resistance of the deposited coatings were studied as a function of the particle concentration in the deposition bath (C-SiC = 2, 4, 6, 8 g/L) and deposition current density (i(d) = 0.5, 1, 2 and 3 A/dm(2)), using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Inductively Coupled Plasma (ICP), X-Ray Diffraction (XRD), microhardness measurements and potentiodynamic polarization (PP) tastings, respectively. The results indicated that the SiC content and surface roughness (R-a) of microcomposite coatings are increased with increasing both the Csic and id and reached to the maximum of X-SiC = 14.8 wt% and R-a= 4.58 mu m at the C-SiC= 8 g/L and i(d) = 3 A/dm(2). While the SiC content and roughness of nano-composite coating are initially increased and then decreased with increasing both the Csic and id and the maximum of X-SiC= 9.6 wt% and R-a= 2.28 mu m were obtained at the C-SiC = 4 g/L and i(d) =1 A/dm(2). The thickness of both type of coatings increases almost linearly with id and micro-composite coatings exhibit greater thickness values. The nano-composites exhibit higher hardness and corrosion resistance than micro-composites despite having lower SiC contents. The maximum hardness and minimum corrosion resistance were 1035 HV and 0.03 mu A/cm(2) for micro- and 889 HV and 0.38 mu A/cm(2) for nan-composite coatings, respectively. (C) 2018 Elsevier B.V. All rights reserved.