Corrosion assessment of electroless nickel-phosphorous/nanosilicon carbide composite coatings

Electroless nickel-phosphorous (Ni-P)/nano-SiC (silicon carbide) composite coatings were deposited onto API-5L-X65 steel substrates in the absence of any surfactants at different concentrations of SiC nanoparticles in the plating bath. The hardness and corrosion resistance of the composite coatings with different content of SiC nanoparticles were measured. Moreover, the structure of the composite coatings were investigated by means of X-ray diffraction, whereas their morphologies and elemental composition were analysed using scanning electron microscope equipt with energy dispersive spectrometer. Results showed that co-deposited SiC nanoparticles contributed to increase the hardness, but the corrosion resistance of the composite coatings depends on dispersion of nanoparticles throughout the coatings and decreases because of agglomeration of nanoparticles and porosity of the coatings.