Electrostatic Powder Enamel (3) - Properties of Electrostatic Enamel Powder
Release time:
2026-03-29 22:44
Source:
China Enamel Industry Association
(Continued from previous article)
4. Electrostatic Enamel Powder
4.1 Properties of Electrostatic Enamel Powder
4.1.1 General Properties of Enamel Materials. After sintering, electrostatic enamel powder must achieve the properties of an enamel layer, including acid resistance, alkali resistance, wear resistance, impact resistance, resistance to rapid thermal changes, and good adhesion (for direct-on enamel or ground coat).
4.1.2 High Resistivity of the Powder. Generally, the resistivity of ordinary low-temperature enamel materials is between 10*E6 and 10*E7 ohm-cm, and the resistivity of high-temperature enamel materials does not exceed 10*E10 ohm-cm. Experience has shown that when the resistivity of enamel powder is less than 10*E11 ohm-cm, the inherent conductivity of the enamel material during electrostatic spraying easily causes the static electricity on the powder to dissipate, leading to powder detachment from the workpiece surface. Powder with a resistivity around 10*E12 ohm-cm can adhere stably to the workpiece, but it is significantly affected by temperature and humidity, which also impacts adhesion. When the resistivity reaches 10*E13-10*E14 ohm-cm, the powder can adhere stably to the workpiece, achieving ideal performance.
4.1.3 Reasonable Particle Distribution. Electrostatic enamel powder is finer than general enamel materials. Finer powder has better flowability, resulting in better fluidization during spraying. Simultaneously, the increased powder surface area also helps to improve the powder's resistivity.
4.1.4 Reasonable Powder Flowability. A fluidization process is required before electrostatic powder spraying to fully disperse the powder, ensuring continuous and uniform delivery to the spray gun during spraying. Powder flowability test values typically reflect the powder's transport speed and deposition rate.
1.5 Good Powder Accumulation. Good powder accumulation ensures the continuous spraying of the same amount of powder onto the workpiece surface to achieve a uniform enamel layer thickness. Deposition performance is closely related to spray gun voltage and air pressure.
4.1.6 Good Adhesion. The powder deposited on the workpiece also needs good adhesion, meaning that after a certain period, the workpiece retains the vast majority of the deposited powder. Adhesion is closely related to powder resistivity, ambient temperature, and humidity. As powder deposits on the workpiece surface, the powder layer thickness increases. Due to Coulomb forces and gravity, the adhesion between the outer powder layer and the workpiece decreases, causing some powder to fall off the workpiece surface. Ambient humidity exceeding the operating range also reduces adhesion. Good adhesion ensures that the enamel powder adheres to the workpiece during post-spraying movement and sintering.
4.2 Packaging and Lifespan. After preparation, electrostatic enamel powder needs to be sealed in plastic bags or other moisture-proof materials to minimize the impact of air humidity. Well-packaged powder can have a shelf life exceeding one year.
5. Conclusion.
The manufacturing of electrostatic powder enamel products involves multiple aspects, including enamel, electrical automation, machinery, thermal furnaces, and welding. Close cooperation among these processes is essential for producing high-quality products. With the accumulation of experience and the development of technology, this technology has gradually matured and plays a vital role in the enamel product manufacturing industry.
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