Chromate-treated zinc-plated steel strip and method for making
US4902387A · kind A · utility
4Cited by
4References
4Claims
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Key dates
| Filing date | Aug 17, 1987 |
| Grant date | Feb 20, 1990 |
| Priority date | — |
| Expiry date | Aug 17, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12847
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A chromate-treated steel strip comprising a chromate film on a zinc plated steel strip is improved in corrosion resistance and coating adherence by forming the chromate film of three layer structure consisting of a metallic Cr layer, a Cr.sup.3+ oxide layer, and an outermost surface layer of SiO.sub.2, and Cr.sup.3+ oxide plus Cr.sup.6+ oxide. The three layered chromate film is deposited on a zinc plated steel strip by effecting cathodic electrolysis in a bath containing hexavalent chromium, colloidal silica, optional alumina sol, and a fluoride, by supplying electricity at a specific current density to a controlled quantity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.