Ni–B/SiC nanocomposite coating obtained by pulse plating and evaluation of its electrochemistry and mechanical properties

Abstract

One of the important techniques for developing coatings with proper electrochemical and mechanical properties is electrodeposition method. The goal of the current work is to optimise contents of SiC particles in the bath to achieve Ni–B/SiC composite coatings with high corrosion resistance and wear properties. Pulse plating method was used to prepare Ni–B/SiC composite deposits of Watts bath including trimethylamine borane (TMAB) and SiC nanopowder addition. The effects of SiC concentration in the bath, which is the principal factor, on the main properties of the coatings were studied. Field Emission Scanning Electron Microscopy (FE-SEM), Energy-dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) were used to analyse the characterisations of the coatings. In order to evaluate the corrosion behaviour of the coatings, the open circuit potential (OCP), electrochemical impedance (EIS) and potentiodynamic polarisation (Tafel) tests were applied in 3.5% NaCl solution. Moreover, the pin-on-disc procedure was designed to assess the wear behaviour of coatings. Increasing the SiC nanoparticles up to 12 g l⁻¹ in the bath leads to produce a coating including 11 wt-% SiC particles which have a positive effect on the coating microstructure. Corrosion resistance improves by raising 4–12 g l⁻¹ SiC incorporation in the coatings; so that corrosion resistance of the Ni–B/SiC12 g l⁻¹ coating reaches to nearly 62 kΩ. The presence of SiC phase in the coating can result in decrease electrochemical active regions; therefore, this phenomenon can promote corrosion resistance of the composite coatings. Ni–B/SiC 12 g l⁻¹ composite coating illustrates the best wear resistance in comparison with the others after which it shows the lowest weight losses (0.98 mg cm⁻²) and the friction coefficient of 0.57 due to the formation of the packed structures with less porosity and high content of SiC particles in the deposit.