Twice-anodized aluminum article having an organo-phosphorus monolayer and process for making the article
US5277788A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 22, 1992 |
| Grant date | Jan 11, 1994 |
| Priority date | — |
| Expiry date | May 22, 2012 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC25D11/12
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A twice-anodized aluminum substrate is anodized sequentially in first and second aqueous electrolytes. In the first, the substrate is conventionally anodized to produce (i) a porous anodic oxide layer having open pores and a passivation layer thereunder. The substrate, now singly-coated, is then anodized in the second electrolyte of an aqueous solution of an organophosphorus compound which generates a residue which is chemisorbed and covalently bonded to the substrate to form (ii) a monomolecular essentially continuous monolayer on the outer surface of (i), and at the same time, the second anodizing step produces (iii) a barrier layer of non-porous aluminum oxide under (i). The thickness of this barrier layer can be increased as a function of the voltage used while maintaining the thickness of (i) substantially constant, and (ii) protects (i) from dissolution. Depending upon the choice of the organophosphorus compound, a hydrophobic, or chemically resistant surface may be produced; or, a surface which provides a leaving group to be reacted with an appropriate organic coating to be applied after the triplex layer is formed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.