Process for phosphating metal surface to make thereon a zinc phosphate coating film
US5308413A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 17, 1991 |
| Grant date | May 3, 1994 |
| Priority date | — |
| Expiry date | Apr 17, 2011 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C22/73
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A metal surface is processed with dipping by a first zinc phosphating solution in which a fluoride complex and a simple fluoride are contained and a concentration of this simple fluoride is 200 to 300 mg/l on a basis converted into the HF concentration and that of the fluoride complex is in a mole ratio with the simple fluoride converted into the HF as shown as, [fluoride complex]/[simple fluoride].gtoreq.0.01, and then the surface is processed with spraying by a second zinc phosphating solution in which a simple fluoride concentration is 500 mg/l or less and higher than that in said first zinc phosphating solution. Thus, on a metal surface is formed a zinc phosphate coating film which is suitable for electrodeposition coating, particular for cationic electrodeposition coating, and superior in coating film adhesion, corrosion-resistance, particularly resistance for warm brine, and prevention of scab-corrosion.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.