Optimization and Characterization of Ni–B/SiC Nanocomposite Coatings: Effects of Deposition Parameters on Hardness and Corrosion Resistance

Abstract

Nanocomposite coatings of Ni–B/SiC on St-37 steel substrates were electrodeposited using a Watts’ nickel bath modified by the addition of borane-trimethylamine as a borane source and dispersion of SiC nanoparticles (20 nm). The effects of electrodeposition current density (i_d) and bath concentration of SiC nanoparticle (C_SiC) on different properties of the electrodeposited coatings such as boron content (C_B), SiC nanoparticle content; X_SiC (wt %), surface roughness; R_a, surface morphology, thickness, corrosion behavior and hardness were examined using inductively coupled plasma (ICP), energy dispersive spectroscopy (EDS), surface roughness profilometry, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, potentiodynamic polarization and microhardness testing. The achievements revealed a uniform dispersion of SiC nanoparticle agglomerates throughout the coating cross-section and the formation of spherical surface morphology. A close relationship between coatings’ surface morphology, roughness, hardness, and corrosion resistance with their SiC content has been established. The SiC nanoparticle content of the coatings initially is raised and then lowered via raising both the C_SiC and i_d. While the C_B is decreased monotonically with increasing the i_d. Optimal properties were observed in coatings electrodeposited at i_d = 1 A/dm² and C_SiC = 4 g/L with a maximum X_SiC of 3.6 wt %. These coatings exhibited the finest nodule size, maximum roughness (R_a = 1.94 µm), hardness (930 HV), and corrosion resistance (minimum corrosion current density of 0.2 µA/cm²).