Powder coating

UV Cured Powder Coating on Carbon Fiber

Powder coating is a type of coating that is applied as a free-flowing, dry powder. Unlike conventional liquid paint, which is delivered via an evaporating solvent, powder coating is typically applied electrostatically and then cured under heat or with ultraviolet light. The powder may be a thermoplastic or a thermoset polymer. It is usually used to create a hard finish that is tougher than conventional paint.

Process

The powder coating process involves three main steps: preparation, application, and curing.

Preparation

Proper surface preparation is crucial for achieving a high-quality finish. The surface must be cleaned of oils, dirt, and other contaminants. This can be done through various methods such as sandblasting, chemical etching, or phosphating.

Application

The powder is applied using a spray gun, which imparts an electrostatic charge to the powder particles. The charged particles adhere to the electrically grounded surface of the part being coated. This method ensures an even coating and minimizes waste.

Curing

After application, the coated part is placed in a curing oven where the powder melts and forms a continuous film. The curing process typically involves heating the part to a temperature of around 200°C (392°F) for 10 to 20 minutes. The exact temperature and time depend on the type of powder used.

Types of Powder Coating

There are two main types of powder coating: thermoplastic and thermoset.

Thermoplastic

Thermoplastic powder coatings melt and flow when heated but do not undergo a chemical change. They can be remelted and reformed, making them recyclable.

Thermoset

Thermoset powder coatings, on the other hand, undergo a chemical reaction during the curing process, forming a cross-linked polymer structure. This makes them more resistant to heat and chemicals but also means they cannot be remelted.

Advantages

Powder coating offers several advantages over traditional liquid paint:

• **Durability**: Powder-coated surfaces are more resistant to chipping, scratching, fading, and wearing than other finishes.
• **Environmental Impact**: Powder coating is more environmentally friendly as it emits negligible volatile organic compounds (VOCs).
• **Efficiency**: The overspray can be recycled, making it possible to achieve nearly 100% use of the coating.

Applications

Powder coating is used in a wide range of applications, including:

• Automotive parts
• Bicycles
• Appliances
• Furniture
• Architectural elements

Related Pages

• Electrostatic spray deposition
• Thermoplastic
• Thermoset polymer
• Sandblasting
• Phosphating
• Chemical etching