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The aim of this research is to investigate the compatibility of different coated products with the degreasing and phosphatation treatments used in the automotive industry, and also the influence of the drawing deformation (with and without friction) on the quality of the phosphate layers. Severe drawing deformations (10%) without tool friction lead to a cracking of all the investigated coatings except the electrogalvanised and Zincrox coatings. Deformation with friction, as simulated with the "Draw bead test", leads to a matting of the coatings and to local abrasion of the superficial oxides. Surface analysis of the coated products, before and after either deformation or alkaline degreasing with Ridoline 1571, and phosphatability studies of these different coated products in a Granodine 908 bath, have shown that the nucleation and kinetics of phosphatation are dependent on the nature and distribution of the oxides present on the surface of the coated products. Drawing operations enhance crystal nucleation due to surface abrasions.

Additional information

Authors: SCHMITZ B, Centre de Recherches Métallurgiques, Liège (BE)
Bibliographic Reference: EUR 13247 FR (1991) 122 pp., FS, ECU 12,50
Availability: (2)
ISBN: ISBN 92-826-0538-8
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