High current density semi-bright and bright zinc sulfur-acid salt electrogalvanizing process and composition
US5788822A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 12, 1997 |
| Grant date | Aug 4, 1998 |
| Priority date | — |
| Expiry date | May 12, 2017 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC25D3/565
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
The inventors disclose a process for producing semi-bright to bright electrogalvanic coatings at high current densities, comprising electroplating a cathodic conductive substrate in a coating bath based on: PA1 a) a zinc sulfur-acid salt; PA1 b) a low molecular weight polyoxyalkylene glycol based on 2 to about 4 carbon atom alkylene oxides; PA1 c) an aromatic sulfonate; and PA1 d) a conductivity enhancing salt. The process includes maintaining the coating composition at a pH from about 2 to about 5 and the current density on the substrate at from about 1,000 to about 3,700 ASF. The zinc sulfur-acid salt includes zinc sulfate or a zinc organosulfonate, and the conductivity enhancing salt, a potassium salt. In one embodiment, the aromatic sulfonate comprises a condensation product of an aromatic sulfonate and formaldehyde. The inventors also describes coating bath compositions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.