Phosphate coatings for metal surfaces

• Main Authors: SOBATA; TAMOTSU, TOKUYAMA; AKIO, ENDO; KOETSU
• Format: Patent
• Language: English
• Published: 03.08.1993
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; METALLURGY; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION

The present inventin concerns a process for phosphating a metal surface comprising treating a metal surface with an acidic aqueous phosphate solution comprising zinc ion, phosphate ion, a phosphating accelerator and particular concentration of colloidal particles having an isoelectric point of 3 or less and an average particle diameter of 0.1 mu or less, the metal surface being iron-based surface, zinc-based surface or combination thereof and the resulted phosphate coating being excellent in film adhesion, corrosion resistance and especially scab corrosion resistance.