Corrosion Protection with Zinc Rich Primer Coating

by Protexion Services Protective Coating and Solution Provider

A epoxy zinc rich coating contains a high percentage of zinc dust and works sacrificially when in direct contact with steel. Zinc rich painting, commonly referred to as cold galvanizing. It’s corrosion protection process for steel or iron, in which the substrate is coated with zinc to prevent it from rusting. The method of galvanisation involves immersing a clean, oxide-free iron or steel material in molten zinc.

The protection mechanism of zinc rich coating is based on cathodic protection provided by the zinc dust in the paint. Zinc cathode protection is finite; however, since the electrical conductivity decreases after the zinc has corroded for some time, and at the same time zinc corrosion products build up on the pigments of zinc dust and polarize the zinc. Its high performance of epoxy zinc rich primer coating also protects steel in aggressive environment like platforms, pipelines, refineries, petrochemical plants and bridges.

How Epoxy zinc rich coating works?

Initially, once the zinc rich primer and the top coating are applied on the substrate as a continuous layer, the coating system acts as a barrier to corrosive environment. The coating fully isolates the substrate from the environment. Only after a defect in the coating has been created, thereby partially exposing the substrate to the corrosive environment, does the zinc-rich primary layer play its part in providing sacrificial corrosion safety to delay the onset of the substrate's electrochemical reaction.

The amount of sacrificial protection provided depends upon variables such as the purity of the zinc dust used, the presence of moisture, and the electrical conductivity between the substrate and interconnected zinc particles. Thus, the zinc used in the primer is anodic to the ferrous substrate that acts as a cathode. Once the zinc particles are converted into zinc oxide, the sacrificial protection will end.

Inorganic Zinc Rich Primer:-

· Inorganic zinc rich primer coating can be formulated with a higher volume of zinc.

· Inorganic zinc rich primers are easier to apply.

· Inorganic zinc rich primer coating are most commonly applied in the shop

Organic Zinc Rich Primer:-

· Organic zinc primer coating is normally applied by brush and spray.

· Organic premiers rich in zinc are most widely used in the region.

· Organic zinc-rich coatings have the same amount of protection as inorganic coatings when the coating is filled to the edges.

Protexion offer an advanced epoxy zinc rich primer coating, which forms a network within the powder coating substrate, designed to give excellent corrosion protection over steel substrates. It forms the base layer of a two-coat system and for external use it has to be coated with a second coat, typically a polyester coating. This solution is recommended where a significantly aggressive environment is being catered for.