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Electrophoretic Coating
What’s Electrophoretic Coating?
Electrophoretic coating (Electrophoretic Coating) is a coating deposition technique that utilizes electrochemical principles to deposit coatings on metal surfaces. It uses an electric field to direct charged coating particles and uniformly adhere to the workpiece surface. After curing, a dense, corrosion-resistant coating is formed.
Electrophoresis: A metal workpiece is immersed in a charged aqueous coating solution. When current is applied:
- Cathode electrophoresis (most commonly used): The workpiece acts as the cathode (negative electrode), and positively charged coating particles (such as epoxy resin) migrate toward it and are deposited.
- Anodic electrophoresis: The workpiece acts as the anode (positive electrode), and negatively charged coating particles are deposited (this technique can easily oxidize the substrate and is less commonly used).
Deposition Process: Coating particles discharge onto the workpiece surface, forming a uniform wet film. After washing and baking, the film is cured.
Electrophoretic Coating Products
FAQ Of Electrophoretic Coating
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Why is electrophoretic coating more corrosion-resistant than conventional spray painting?
Electrophoretic coating is formed through electrochemical deposition, which ensures uniform coverage on the workpiece surface (including edges, welds, and other hard-to-reach areas). Additionally, cathodic electrodeposition (e.g., automotive primers) provides self-passivation, effectively blocking moisture and corrosive agents. In contrast, conventional spray painting may suffer from uneven coverage or insufficient film thickness, resulting in poorer corrosion resistance.
Can electrophoretic coatings be colored, or are they only available in black?
Traditional electrophoretic coatings are primarily black or gray (e.g., epoxy-based). However, with technological advancements, colored electrophoretic coatings (e.g., silver, red) are now achievable using acrylic or polyurethane resins, commonly used in appliances and electronics. That said, colored coatings generally have higher costs and may differ in weather resistance compared to standard black coatings.
Why is high-temperature curing essential after electrophoretic coating?
The freshly deposited coating is a “wet film” that requires high-temperature baking (150-180°C) to trigger cross-linking reactions in the resin, forming a dense and hardened film. Inadequate curing leads to poor adhesion and reduced corrosion resistance. Some advanced electrophoretic coatings now support low-temperature curing (e.g., 120°C) to reduce energy consumption.