Protecting metallic substrates against corrosion is one of the prime functions of most coatings. Corrosion resistant coatings are typically formulated using anticorrosive pigments and suitable binders with the optimum formulation parameters. In addition, organic compounds known as corrosion inhibitors are often added at low levels, and can effectively reduce the corrosion rate of a metal or slow down the individual corrosion reactions.
Various organic compounds are useful as corrosion inhibitors, such as acetylene derivatives, heterocyclic compounds containing nitrogen, sulfur and/or oxygen, long-chain aldehydes and ketones, amines, carboxylic acids and their derivatives, thiourea derivatives and thiophosphates.
Based on their function, the corrosion inhibitors used in the coating industry are classified into two categories:
• Flash-rust inhibitors (temporary corrosion protection)
• Inhibitors for long-term protection