Preparation and Properties of Conductive Aluminum Powder (Al@Si@C) for Water-Borne Heavy-Duty Anticorrosive Coatings

Abstract

To improve the storage stability and conductivity of aluminum powder in an aqueous environment, the surface of aluminum powder was treated to form silica film by the sol–gel method, then was treated with conductive modification to introduce nanocarbon black particles so that conductive aluminum powder could be prepared to solve the application bottleneck of aluminum powder in water-borne heavy-duty anticorrosive coatings. The structure, surface morphology, and composition of the modified aluminum powder were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray powder diffraction (XRD). The corrosion resistance and electrochemical properties were measured using a hydrogen evolution test and an 2electrochemical test. The results showed that there was a compact SiO2 film formed on the surface of the prepared conductive aluminum powder, and the conductive filler nanocarbon black was uniformly grafted on the surface. According to the hydrogen evolution test at 100 h/50 °C, conductive aluminum powder with 5 wt% carbon black exhibited the best hydrogen evolution effect, with a hydrogen evolution amount of only 0.5 mL. The prepared conductive aluminum powder was applied to the water-borne coatings, and the storage stability test, electrochemical polarization test, and neutral salt spray test were further conducted. The water-borne coatings prepared with conductive aluminum powder still showed good performance and had no reaction after 6 months of storage. Compared with the coating containing SiO2-modified aluminum powder, the coating exhibited better corrosion resistance.