WEB Benefits of evaluating coatings in real marine enviroment
Laboratory accelerated weathering tests are extremely useful to estimate the life expectancy of coatings in a quick and standardized way. However, testing in real environment increases the representativeness of results and allows a correlation of results with those obtained in the lab. This correlation between accelerated and outdoor testing has been extensively studied for many years, but no direct correlation has been found until now as some environmental parameters are difficult to reproduce in accelerated tests (acid deposition, microorganisms growth, …).
In this work different coatings were tested both in real marine environment and in laboratory accelerated tests. The objective is to analyse the correlation of results and identify the benefits of evaluating coatings in real marine environment. On one hand, coatings were exposed during 13 months in HarshLab offshore materials and components lab, an offshore platform moored in the Biscay Gulf 1,6 miles away from the coast of Armintza (Bizkaia, Spain). HarshLab was commissioned in September 2018 in BiMEP area (Biscay Marine Energy Platform), a 5,6km2 open sea test site for marine energies demonstration. Meteoceanic conditions were 24/7 monitored during the testing period thanks to nearby oceanographic buoys and meteorological stations. In parallel, a classification, determination and estimation of corrosivity in HarshLab was carried out according to ISO 9223 and ASTM G116 standards.
On the other hand, coatings were tested in several accelerated laboratory tests: salt spray test according to ISO 9227 standard, cyclic corrosion tests based in ASTM G44 standard and ISO 12944-6 standard, thermal cyclic tests according to NACE TM304 and NACE TM204 standards, immersion test according to NACE TM304 standard and cathodic disbonding test according to ASTM G8 standard.
Biological conditions in HarshLab are extremely complex, with different communities of biofouling growing in samples exposed in immersion zone, while coatings placed in atmospheric zone are exposed to a variety of changing environmental conditions (salt sprays, UV light, rain, seagull excrement, …). Conditions in the laboratory ageing tests are influenced by the presence of NaCl, MgCl2 6H2O, Na2SO4 10H2O, higher salinity, corrosion products and by higher thermal shock than those occurring in HarshLab.
Results from both laboratory and natural weathering test were studied, with special focus on corrosion rate and adhesion loss in coatings.
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|Extended Abstract||BENEFITS OF EVALUATING COATINGS IN REAL MARINE ENVIROMENT||This is a short manuscript to the abstract||152 KB||Download|