Powder coatings are powder materials that consist of pigmented thermoplastic particles. The powders are sprayed electrostatically onto components and then fused into a uniform and durable coating. Powder coatings are applied to cleaned, sandblasted surfaces that are free of dirt, oil, and paint. To prevent corrosion, degreasing may be required. An operator then uses a special gun to apply powder coatings made of resin and pigment. Heating the component in a large oven causes the powdery material to melt, gel, and cure. Often, the pigmented finish in powder coatings is both surface-enhancing and corrosion-resistant.
Powder coatings are usually made of thermoset, fluoropolymer, epoxy, or polyurethane materials. Thermoset powder coatings are made of cross-linked polymeric resins that are cured or set using heat or both heat and pressure. They generally have a higher resistance to heat than thermoplastics. Fluoropolymer powder coatings are similar to thermosets and thermoplastics in terms of their mechanical characteristics, but provide better resistance to solvents, acids and bases. Epoxy powder coatings have a resin and a hardener made of two different chemicals. Polyurethane powder coatings bond well to plastic surfaces and require a catalyst, heat, or air evaporation to initiate curing.
Product specifications for powder coatings include color, usage, finish, metallic effect, and gloss. Power coating colors include aluminum, black, beige, blue, bronze, brown, chrome, clear, gold, green, gray, ivory, orange, red, silver, violet, white and yellow. Usage is often specified as exterior or interior. Finishes range from raised to smooth. Powder coatings with a metallic effect are either blended or bonded. In terms of gloss, most products are either described as glossy or matte. Other parameters to consider when selecting powder coatings include pencil hardness, mar resistance, flexibility, chemical resistance, weathering, and yellowing resistance.
Powder coatings are used in a variety of agricultural, architectural, automotive, and industrial applications. Agricultural products are used with tractors, threshers, and other farm equipment. Architectural powder coatings are used to metal doors and frames, rails and railings, roofing and decking, fences and fencing, outdoor seating, and playground and recreational equipment. Automotive powder coatings are used to coat components such as bumpers, coil springs, engine parts, strut bars, sway bars, and trim parts. General-purpose industrial products are also commonly available.