Electrophoretic coating generally includes four simultaneous processes:
1. Electrophoresis: under the action of DC electric field, positive and negative charged colloidal particles move in negative and positive directions, also known as swimming.
2. Electrolysis: oxidation and reduction reactions are carried out on the electrode respectively, but oxidation and reduction phenomena are formed on the electrode.
3. Electrodeposition: due to electrophoresis, the charged colloidal particles moved near the anode release electrons on the body of the template, which are deposited in an insoluble state and precipitated. At this time, the paint film is formed.
4. Electroosmosis: under the action of electric field, the solid phase does not move, but the liquid phase moves. Electroosmosis causes the water contained in the paint film to be gradually discharged outside the film, forming a dense paint film that can hardly even pass the current, with extremely low moisture content and high resistance.
5. Take iron red epoxy electrophoretic paint as an example: the electrophoretic paint is composed of modified epoxy resin, butanol, ethanolamine, talc powder and iron red. After the electrophoretic paint is mixed with distilled water, it is separated into positively charged cations and negatively charged anions under the action of DC electric field, and a series of complex physical and chemical colloidal chemistry and electrochemical change processes are carried out.
