MEA As Corrosion Inhibitor In Metal Surface Coatings

                   MEA As Corrosion Inhibitor In Metal Surface Coatings

1. Working principle of Monoethanolamine(MEA) as corrosion inhibitor

MEA mainly exerts its corrosion inhibition effect through the following mechanisms:

Adsorption film formation:

The molecular structure of MEA contains polar amino groups (-NH₂) and hydroxyl groups (-OH), which can be firmly attached to the metal surface (such as iron, copper, aluminum, etc.) through chemical adsorption or physical adsorption to form a monomolecular protective film. This film isolates the metal from contact with corrosive media (such as oxygen, water, acidic/alkaline substances), thereby inhibiting electrochemical corrosion reactions.

PH adjustment:

MEA is alkaline (pH≈10-11), which can neutralize acidic substances in the environment (such as CO₂, H₂S, etc.), reduce the risk of local acid corrosion, and is particularly effective in closed systems (such as boilers and cooling water systems).

Chelation:

The amino group of MEA can form soluble complexes with metal ions (such as Fe²⁺, Cu²⁺) to prevent metal ions from depositing or participating in corrosion reactions, but this property requires concentration control to avoid excessive chelation and corrosion.

2. Compounding requirements in practical applications

The use of MEA alone may affect the uniformity of the coating due to high volatility or viscosity. MEA usually needs to be compounded with other solvents or additives. Typical application scenarios and formula examples:
Water-based metal coating:
MEA (1-5%) + sodium molybdate (0.5-2%) + water-based acrylic resin, used for rust prevention of steel structures.
Coolant corrosion inhibitor:
MEA (2-3%) + borate (1%) + sodium nitrate (0.1%), inhibits pitting of aluminum and cast iron.
Vapor corrosion inhibitor (VCI):
MEA is mixed with benzoate to make corrosion-inhibiting paper for packaging metal parts.

Summary

MEA can be used directly as a corrosion inhibitor, but in actual industrial applications, it is often compounded with other solvents or additives to optimize performance. The specific formula needs to be designed according to the metal type, environmental conditions and coating syste.