What Does Powder Coating Mean?
Powder coating is coating that is applied as dry powder or free flowing. It is completely different from traditional liquid paint, as it requires a solvent for the filler and binder parts to form in a suspending liquid.
It is mainly used to coat metals, like aluminum extrusions, household appliances, bicycle and automobile parts and drum hardware.
Corrosionpedia Explains Powder Coating
Powder coating is applied through electrostatic means and cured by heating to build a skin. There are two basic types of powder coatings: thermoplastics and thermosets. Thermosetting uses a cross linker in its formulation. When baked, it reacts with the existing chemical groups present in the powder in order to undergo polymerization. This enhances the coating's properties and performance. The thermoplastic type involves no extra actions during the process of baking; it just flows into the resulting coating.
The most typical polymers used in powder coatings are the following type of acrylics:
- Straight epoxy
- Fusion-bonded epoxy
- Hybrid epoxy
- Polyester epoxy
These ingredients are melted, cooled and grounded to a consistency similar to baking flour. In terms of application, powder coatings involve three simple steps:
- Pre-treatment or surface preparation
- Application of powder coating
- Curing process
Electrostatic display deposition (ESD) is used to achieve the best application. This technique facilitates powder coating application onto a metal surface and uses a spray gun that releases electrostatic charges to the particles of the powder coating and then is attracted to the grounded part. After the powder coating is applied, the surface goes through a curing oven and with extra heat, the coating reacts chemically to create lengthy molecular chains, leading to elevated cross-linked density. Such molecular chains are anti-corrosive and serve as the most common technique to apply powder coatings. With this technique, powder coatings also can be applied on non-metal substrates, like fiberboard and plastic.