Abstract

Corrosion inhibitors have become indispensable since the 40’s to combat corrosion, the most well-known until recently were inorganic inhibitors with their anodic or cathodic natures, but in the face of pressure to develop environmentally friendly products, Researchers double efforts to replace these compounds. Organic corrosion inhibitors have shown similar performances against their inorganic siblings with 90% inhibition of corrosion or upper. This research concentrates on the evaluation of organic corrosion inhibitors extracted from radiata pine bark off in a pilot scale plant with capacity to process 4 m3, the extraction was done by solutions of 75% ethanol in the proportion 1:20 (w/v, bark/alcohol solution), followed by vacuum drying to finally obtain two fractions, firs one, water-soluble and second one water-insoluble. The two extracts were obtained with a maximum moisture content of 2%, different formulations were first formulated using epoxy resin crosslinked with polyamide, fillers, pigments and additives, the coatings were formulated with 0.34% (w / w) extract while maintaining l ration in 0.85 (l = PVC / CPVC, PVC = pigment volume concentration, CPVC = critical pigment volume concentration), the extracts were characterized by means of HPLC, UV-VIS, GPC and EPR technics, the coatings performance were evaluated following the ASTM D4541, B117, D3363, EN13523-1, SEM-EDS and electrochemical impedance spectroscopy (EIS) technique, the evaluations was made at different exposure times in a salt fog spray chamber. The results show that the water-soluble fraction of tannins has a 98.5% efficient of inhibition of corrosion, compared to the insoluble fraction which was 10% lower, this superior performance will follow the formation of a passive layer of iron-catechin complex on the alloy product of reduction of tannin, the equivalent circuit for this system is (R1(Q1(R2(Q2(R3(R4C))))) where R3 represent the oxidative layer under the primer coat when made the complex compound.