Inhibitive Primer

Definition - What does Inhibitive Primer mean?

An inhibitive primer is an undercoat or preparatory coating consisting primarily of inhibitive pigments. These pigments are specially formulated to prevent corrosion on metallic substrates. They achieve this by undergoing a series of reactions that disrupt the electrochemical processes necessary for corrosion to occur.

Some inhibitive primers may also undergo self-healing to protect against macroscopic defects. In other words, the primer is designed to leach pigments from adjacent areas into the defect.

Corrosionpedia explains Inhibitive Primer

Inhibitive primers are usually applied as the base coating on metallic surfaces. When applied to the substrate, the primer alters the metal’s surface properties, making it inert (resistant to corrosive electrochemical reactions). This process is also known as passivation.

The primary mechanism by which inhibitive primers passivate the substrate is polarization. During this process, the electrode potential of the surface is shifted to either an anodic or a cathodic state. This change in surface property helps promote the growth of natural oxide protective barriers.

Red lead and zinc chromate primers are two of the most well-known inhibitive primers.

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