Improved Corrosion Control Through Nontoxic Corrosion Inhibitor Synergies

By Andrew Thorn, Amanda Adams, Tony Gichuhi, Wendy Novelli, Mary Ann Sapp

The idea of anticorrosive synergies is not a new concept but one that still holds a lot of promise for advancing the performance of environmentally compliant protective coat­ings. The most environmentally sound method for surpassing the high anticorrosion stan­dards set by toxic inhibitors such as lead- and chrome-base inhibitors is through the gains provided by nontoxic corrosion inhibitors synergies.

In order to realize the benefits that exist from combining inhibitor chemistries, one must first understand the mechanisms surrounding corrosion, the inhibitors themselves, and the key formulating guidelines required for success. “Solubility optimization” of the inhibitors in the coating film is an important factor for improving anticorrosive perform­ance. Resin type and formula parameters play a significant role in inhibitor selection and use level. This synergistic approach for improving performance also carries through to other components such as extender pigments and additives. Once the synergistic balance is achieved, the results are a clear indication of the power of this theory.

The economic cost of corrosion throughout the world is enormous. A study, jointly conducted by the Battelle Columbus Laboratories and the National Bureau of Standards (NBS) in 1975, showed corrosion to equal ap­proximately 4.2% of the gross national product (GNP) for the United States.1•2 A more recent study conducted in 1998, administered by Federal Highway Administration (FHWA) and performed by a team led by CC Technologies in collaboration with NACE International, showed that corro­sion accounted for 3.14% of the GNP. Similar studies have also been con­ducted in other countries and have shown corrosion to account for anywhere from 1.5% in Australia to 5.2% in Kuwait of the respective countries’ GNP.