Anodic oxidation of the surface of aluminum or aluminum alloys

US4939068A · kind A · utility

Assignee

• BASF SE

Inventors

• Harald Lauke · Mannheim, DE
• Bernhard Nick · Ludwigshafen, DE
• Reinhold J. Leyrer · Schifferstadt, DE

Key dates

• Filing date: Dec 1, 1988
• Grant date: Jul 3, 1990
• Expiry date: Dec 1, 2008

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C25D11/06
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

The surface of plates, foils or ribbons consisting of aluminum or aluminum alloys are anodically oxidized in an aqueous electrolyte as the anodizing bath by a process in which the electrolyte used may contain organic and inorganic acids together with further additives. The aqueous electrolyte must contain one or more silanes I of the formula I EQU X--(CH.sub.2).sub.y --Si(R.sup.1).sub.n (OR.sup.2).sub.3-n I where y is an integer from 1 to 4, n, independently of y, is 0, 1 or 2, R.sup.1 and R.sup.2 are each C.sub.1 -C.sub.9 -alkyl or C.sub.6 -C.sub.12 -aryl, X is selected from X.sup.1 to X.sup.11 ##STR1## where R.sup.3 is hydrogen, C.sub.1 -C.sub.9 -alkyl, an alkanecarboxylic acid group of 1 to 9 carbon atoms or a carboxylic anhydride ring obtained by reacting one of the said alkanecarboxylic acid groups of 1 to 9 carbon atoms with the methylenecarboxylic acid group ##STR2## bonded to R.sup.3, R.sup.4 and R.sup.5 are each C.sub.1 -C.sub.9 -alkyl or C.sub.6 -C.sub.12 -aryl, R.sup.6 is hydrogen, C.sub.1 -C.sub.12 -alkyl or C.sub.6 -C.sub.12 -aryl, Z is hydrogen or an alkali metal cation, Ar is C.sub.6 -C.sub.12 -arylene and Hal is chlorine or bromine. The silanes I are added to the aq…