Research on the Corrosion Resistance of Electrodeposited Ni-SiC Composites Constructed for Steel Storage Tank Application

In this paper, the effects of the SiC phase incorporated in Ni substrate deposits on storage tank steel during electrodeposition at different current densities are explored. The microstructure, phase content, and corrosion resistance of the resulting Ni-SiC composites were investigated by scanning electron microscopy (SEM) matched with energy disperse spectroscopy (EDS), X-ray diffraction (XRD), and an electrochemical workstation, respectively. SEM micrographs and EDS results show that at 2.5 A/dm², the composites presented a smooth and compact structure with high SiC content, while at 1.8 or 3.2 A/dm², it became uneven and loose in structure with low SiC content. XRD patterns showed that the nickel grain size of composites firstly increased and then decreased with the growth of the current density. Notably, the Ni-SiC composite produced at 2.5 A/dm² possessed a higher corrosion potential (-0.507 V) and lower corrosion current density (2.439 μA/cm²), illustrating that its excellent anti-corrosion ability was superior than that of other two composites. Hence, SiC co-deposited at 2.5 A/dm² conducted as a protective barrier and inhibited the corrosion rate against a corrosion medium of Cl^- and SO4^2- ions. In addition, the corrosion relationship illustrated that the SiC content of Ni-SiC composite firstly increased and then decreased with the growth of the current density, while the corrosion weight loss of Ni-SiC composites firstly decreased and then increased.