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Mechanism of Cathodic Electrocoat Primer Cratering
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English
Abstract
Cathodic electrocoat primers (cathodic e-coat) have been widely adopted by the automobile industry. One drawback to these coatings is that they display a tendency for formation of crater-like features when applied to zinc-rich surfaces under typical automotive application conditions.
Our studies show that cratering susceptibility is an inherent property of zinc and that the craters result from localized dielectric breakdown of the e-coat film during deposition. Energy from the electric discharges displaces the e-coat at the discharge sites and locally cures the adjacent e-coat. During cure-baking, the locally cured e-coat does not re-flow to fill the voids created by the discharges, resulting in crater-like features in the cured e-coat film.
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Citation
Hart, R. and Townsend, H., "Mechanism of Cathodic Electrocoat Primer Cratering," SAE Technical Paper 831818, 1983, https://doi.org/10.4271/831818.Also In
References
- Pierce, P. E. Journal of Coatings Technology 53 672 52 1981
- Froman G. W. Franks, L. L. Technological Impact of Surfaces: Relationship to Forming, Welding and Painting American Society for Metals Metals Park. Ohio 315 1981
- Handbook of Chemistry and Physics 46th Chemical Rubber Co. Cleveland, Ohio E-54 1965