Corrosion Inhibition of a Sol-Gel Coating Modified with Cobalt- Enriched Zeolite on AA2024-T3 Aluminum Alloy

摘要

Cobalt-enriched zeolite (CoNaX) nanocontainers, synthesized by ion-exchange reactions of zeolite X(NaX) and Co(NO 3 ) 2 , were used as inhibitor additives to improve the corrosion protection of a sol-gelcoating. A dispersion of CoNaX zeolite was uniform in the sol-gel coating and caused no defects. Anincrease in coating thickness was unapparent with the addition of CoNaX zeolite. Results of testsindicated that the corrosion protective properties of the sol-gel coating were remarkably improved. Thiswas attributed to an enhanced cross-linking density by zeolite particles and a controlled release of Co 2+in CoNaX zeolite. The released Co 2+ reacted with OH - from corrosion products, which formed a Cooxide/hydroxide precipitation. The precipitation covered defects and prevented contact of electrolytewith the substrate, which further slowed corrosion processes. CoNaX zeolite provided the coating withlong-term inhibitive properties.