Anticorrosion Coating with Heterogeneous Assembly of Nanofillers Modulated by a Magnetic Field

An anticorrosive coating with randomly distributed passive barriers and regionally enriched active corrosion inhibitors is developed by integrating mica nanosheets (MNSs) and magnetic-responsive core–shell mesoporous nanoparticles with 2-mercaptobenzothiazole (Fe3O4@mSiO2/MBT) under magnetic field incubation. The bottom enriched Fe3O4@mSiO2/MBT rapidly releases the MBT to form a passivation layer on corrosion sites, enhancing the corrosion inhibition efficiency by 30.36% compared with the control (NP0.7EP-R). The impedance modulus |Z|0.01 Hz of the sample (NP0.7/MNS0.5/EP) increases by five orders of magnitude compared with that of its control (NP0.7/MNS0EP) after 30 days of corrosion immersion. NP0.7/MNS0.5/EP exhibited the lowest corrosion rate (3.984 × 10–5 mm/year) as compared to the other samples. Notably, the coating in a fractured state still maintains superior corrosion inhibition even after 40 day salt spray testing. The differentiated distribution of nanofillers was well confirmed by optical microscopy and SEM-EDS, and the synergistic effect of the active/passive integrated anticorrosive coating with merits of both comprehensive protection and fast responsiveness was systematically explored.