Corrosion resistant surface-treated steel strip and process for making
US4629659A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 14, 1984 |
| Grant date | Dec 16, 1986 |
| Priority date | — |
| Expiry date | May 14, 2004 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12951
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
Highly corrosion resistant plated steel strips or sheets adapted for phosphate treatment and cathodic electrodeposition and intended for use in automobiles, are produced by electroplating at least one surface of a steel strip with an alloy consisting essentially of 0.0003 to 15% by weight of phosphorous, balance essentially iron, in a plating bath containing Fe.sup.2+ ions in an amount of from 0.3 mol/liter to the solubility limit and hypophosphorous acid and/or a hypophosphite in an amount of 0.001 to 25 g/liter expressed as NaH.sub.2 PO.sub.2.H.sub.2 O at a pH of 1.0 to 5.0, a temperature of 30.degree. to 60.degree. C., and a current density of from more than 20 to 200 A/dm.sup.2, preferably 40 to 150 A/dm.sup.2. A top coat can be applied thereover, of one element selected from the group consisting of Ni, Zn, Mn, and Ti, deposited on the Fe-P plating layer to a build-up of 5 to 50 mg/m.sup.2. A lower layer of zinc or a zinc alloy can also be electrodeposited on at least one surface of the steel strip, prior to formation of the Fe-P layer. A surface film can be formed by chemically treating the Fe-P plating layer with a phosphate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.