The most common way to protect metallic structures from corrosion is through the use of passive and active corrosion protection with coatings containing dispersed corrosion inhibitor particles. Current approaches use inorganic microparticles containing mostly toxic and/or critical elements (e.g. CrVI, Li-salts). Organic inhibitors have been identified as a potential replacement technology due to their high inhibiting efficiency in solution, high versatility and lower toxicity. Nevertheless, when brought into organic coatings these inhibitors lose their efficiency due to unwanted side reactions with the surrounding organic matrix (coating). In this work we propose a novel strategy to isolate the organic corrosion inhibitor microparticles from the surrounding matrix. The new approach is based on the gas-deposition of an oxide nanolayer on the microparticles using gas deposition in a fluidized bed reactor. As a result, the organic particles are better dispersed in the coating and do not react with the surrounding matrix. Upon coating damage the particles are exposed to water and release sufficiently high amounts of the organic corrosion inhibitor at the damaged location. The work introduces a technique that can be used in other applications with similar challenges and a new technology that enables for the first time to store large amounts of active organic corrosion inhibitors in reactive organic coatings for efficient protection of metallic infrastructure. This opens the path to the practical use of highly efficient organic inhibitors in coatings for corrosion protection.

The interaction of 2,5-dimercapto-1,3,4-thiadiazole (DMTD) with the AA2024-T3 local microstructure (S-phase, secondary phases and matrix) as function of the NaCl concentration is studied. The inhibiting power and the local interaction of DMTD with the metal were studied by in–situ opto-electrochemistry, XPS and Raman spectroscopy. The stability of the inhibiting layers was evaluated by re-exposing the samples to NaCl solutions without inhibitor. The amount of DMTD and its interaction state (chemisorption/physisorption) vary with the local microstructural composition and NaCl concentration. Higher stability of the inhibiting layers is obtained when these are formed in presence of small amounts of NaCl (0.025–0.25 M).