Hard anodic coating for magnesium alloys
US5470664A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 6, 1994 |
| Grant date | Nov 28, 1995 |
| Priority date | — |
| Expiry date | Jul 6, 2014 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC25D11/30
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A two-step process for the coating of magnesium and its alloys is disclosed. The first step comprises immersing the magnesium workpiece in an aqueous solution comprising about 0.2 to 5 molar ammonium fluoride having a pH of about 5 to 8 and a temperature of about 40.degree. to 100.degree. C. The second step is an electrochemical treatment of the pretreated article in an aqueous electrolytic solution having a pH of at least about 12.5 and which solution comprises about 2 to 12 g/L of a aqueous soluble hydroxide, about 2 to 15 g/L of a fluoride-containing composition selected from the group consisting of fluorides and fluorosilicates, and about 5 to 30 g/L of a silicate. This process results in a superior coating which has increased abrasion and corrosion resistance.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.