Abstract
For the last thirty years, benzotriazole and its derivatives have dominated industrial yellow metal corrosion inhibitors. By far, the most popular of these has been tolyltriazole. It has become the industry standard and is, today, usually the only copper corrosion inhibitor considered by water treatment experts. However, even though it dominates all other competitors, tolyltriazole does have its weaknesses in certain applications. Tests have shown that chlorine added as a biocide can penetrate the thin tolyltriazole film, causing accelerated corrosion rates. The tenacious, hydrophobic film formed with tolyltriazole makes it very resistant to breakdown in aqueous environments. However, because of the film’s thinness, it is not very forgiving if breakdown does occur. At elevated levels, both chlorine and bromine have been found to attack and breakdown the formed film, causing corrosion inhibition failure. The user must assure that there is residual inhibitor present in these situations to repair the damage. This paper presents studies that explore alternative inhibitors that may offer an improvement over tolyltriazole in a number of areas. Numerous molecules, both aliphatic and aromatic, were evaluated for their copper corrosion inhibitive properties. The molecules’ performances were compared to that of tolyltriazole under identical conditions. These comparative tests were conducted in common corrosion testing systems, using both electrochemical corrosion cells and pilot cooling rigs, using various water conditions. The test methods included electrochemical studies, such as linear polarization resistance, open circuit potential versus time, Tafel and cyclic polarization.
