While coating plays an important role in the corrosion protection, using liquid corrosion inhibitors improves this property. These agents can be used alone like in clearcoats or in synergy with various anticorrosion pigments. This synergy improves the corrosion resistance of the paint and it is even possible to:
reduce the amount of anticorrosion pigments
- provide excellent results & an alternative to cost reduction and environmental questions.
Corrosion and Coatings
Corrosion is deterioration of the metal due to a chemical or electrochemical reaction with its environment. Typically, for ferrous materials such as iron and steel, corrosion is also called “rust
The corrosion of a metallic part can change the surface aspect, weaken its properties and damage the adjacent parts. Apart from color and appearance change, it can weaken the structure/destroy the structure itself.
In coatings, electrochemical corrosion is predominant. It is the combination of two conductors (electrodes) with an aqueous electrolyte solution. The metal with more negative potential will be the anode, and will corrode, where the one with more positive potential will be the cathode. Then occurs an oxido-reduction reaction, in the electrolyte solution.
But corrosion can also occur in same metal system, where differences of potential exists on the surface. These differences of potential can come from heterogeneous chemical composition like:-
- differences in the coating layer
In iron, corrosion occurs when different parts of the surface creating anode and cathode, are exposed to electrolyte solution. Without any electrolyte, the corrosion is strongly reduced. In other words, salted atmosphere (like marine conditions) are more aggressive than non-polluted atmosphere. In pure water, corrosion is nonexistent.
Besides this corrosion reaction, many other factors may influence the corrosion of the coating, such as :