Organic coatings protective mechanisms

Grundmeier G, Schmidt W and Stratmann M 2000 Corrosion protection by organic coatings electrochemical mechanism and novel methods of investigation Electrochim. Acta 45 2515... 

The symposium on which this book is based was organized to provide a forum for discussion of recent advances in the use of polymeric materials in corrosion control. Most of the papers presented in the symposium are included in this volume. Several chapters have been added. These include an introductory overview as well as separate review chapters on how organic coating systems protect against corrosion, on mechanisms of adhesion loss of organic coatings, and on the interfacial chemistry of adhesion loss in aggressive environments. 

The electrochemical, physicochemical and adhesional aspects of corrosion protection by organic coatings are shortly discussed. Attention is drawn to some inoonsist-ancies in the interpretation of protective mechanisms and suggestions are given how protective principles may be optimally realized in practical systems. 

There are essentially three Inportant mechanisms hy vhich organic coating systems protect against metal corrosion ... 

Carbonate particles embedded in the faecal pellets of planktonic crustaceans are protected from dissolution by an organic capsule. This mechanism is lEirgely responsible for the presence of remains of calcareous nannoplemk-ton in deep ocean sediments below the compensation level for carbonate (Honjo, 1976). Similarly, carbonate particles suspended in sea water are apparently coated by a layer of organic matter. After this layer is experimentally removed by a strong oxidant (e.g. hypochlorite or H2O2), the rate of carbonate dissolution increases significantly (Chave and Suess, 1967,... 

Blistering by volume expansion due to swelling Organic coatings for corrosion protection typically absorb water up to 3 or 4% if this absorption occurs locally, bKsters may form because of accumulation of water. This mechanism is however unimportant when compared with other mechanisms. 

Hare, C, Steele, M, Collins, SP. 2001. Zinc Loadings, Cathodic Protection, and Post-Cathodic Protective Mechanisms in Organic Zinc-Rich Metal Primers. J. Protect. Coat. Linings, 54. 

Kasemann, R, Schmidt, H. 1994. Coatings for Mechanical and Chemical Protection Based on Organic-Inorganic Sol-Gel Nanocomposites. New J. Chem., 18, 1117. 

Sathiyanarayanan, S., (eyaram, R., Muthukrishnan, S., and Venkatachari, G. (2009) Corrosion protection mechanism of polyaniline blended organic coating on steel./. Electrochem. Soc., 156, C127-C134. 

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