Surface treatment, also known as pretreatment, in powder coating involves preparing the surface of the substrate before applying the powder coating. This crucial step ensures proper adhesion, durability, and corrosion resistance. The primary goal is to remove contaminants and create a clean, rough surface for the powder coating to adhere to.
Methods of Surface Treatment:
- Cleaning: This involves removing dust, dirt, grease, and other contaminants from the surface.
- Degreasing: Removing oil, grease, and other oily residues to create a clean surface for the powder to adhere to.
- Sandblasting/Shot Blasting: Using abrasive media to create a rough surface profile for better adhesion and to remove rust, mill scale, and other inorganic contaminants.
- Acid Etching: Etching the surface with an acid to remove surface oxides, create a rough surface for adhesion, and form a conversion coating for corrosion protection.
- Phosphating: Applying a phosphate layer to the surface to improve adhesion, corrosion resistance, and create a more durable surface.
- Rinsing: Removing any residual chemicals or contaminants after the pretreatment stages.
- Drying: Ensuring the surface is completely dry before applying the powder coating.
Benefits of Surface Treatment:
- Improved Adhesion: The rough surface created by pretreatment allows the powder coating to bond more strongly with the substrate.
- Enhanced Durability: A clean, treated surface can improve the overall durability and longevity of the powder coating.
- Increased Corrosion Resistance: Conversion coatings, such as phosphating, can provide an additional layer of protection against corrosion.
- Flawless Finish: Proper surface preparation ensures a smoother, more uniform powder coating finish.
In summary, surface treatment in powder coating is a critical step that prepares the substrate for optimal powder coating performance and durability.