Stimuli-responsive inhibition of Al substrate corrosion
Recently, anti-corrosion coatings with auto-inhibition and self-reporting on their premature flaws are becoming more and more attractive. In a new work, researchers engineered a cerium nitrate/8-hydroxyquinoline (Ce-HQ) hybrid pigment to endow epoxy coatings with corrosion self-inhibiting and fluorescent self-reporting performances via molecule design. The Ce-HQ pigments were synthesised by physical mixture and then dispersed into the commercial epoxy coating. Once the epoxy coating gets degraded, the underneath aluminum alloy matrix may corrode to produce Al3+ ions, which can compete with Ce3+ ions in the Ce-HQ complex, and then chelate with dissociative 8-HQ to form fluorescent Al-HQ complex, due to the higher bonding strength of Al3+ with 8-HQ than Ce3+ ions.
High corrosion resistance
Thus, not only the responsive releasing of Ce3+ ions and 8-HQ can inhibit the underlying Al alloy, but the newly formed Al-HQ complex could indicate the location and severity of coating flaws through fluorescent emission under UV light. Electrochemical impedance evidenced that the composite epoxy coating containing 1 % mass Ce-HQ presents high corrosion resistance even after 504 h of salt spray test, showing 90 % corrosion refraining efficiency.
The study has been published in Progress in Organic Coatings, Volume 182, September 2023.
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