Method of manufacturing an aluminum product

Abstract

The invention relates to a method of manufacturing an Al or Al alloy workpiece, including the steps of (a) providing an Al or Al alloy workpiece, (b) pre-treating of the outersurface of the Al or Al alloy workpiece, and (c) plating a metal layer including nickel onto the outersurface of the pre-treated Al or Al alloy workpiece. During step (c) the metal layer including nickel is deposited by electroplating both nickel and bismuth using an aqueous bath comprising a nickel-ion concentration in a range of 10 to 100 g/l and a bismuth-ion concentration in the range of 0.01 to 10 g/l. The invention further relates to an aqueous plating bath for use in the method of this invention.

Description

[0001] This is a continuation-in-part of U.S. patent application Ser. No. 09 / 573,980, filed May 19, 2000, now pending, incorporated herein by reference in its entirety.[0002] The invention relates to a method of manufacturing an Al or Al alloy workpiece, such as a brazing sheet product, comprising the steps of providing an Al or Al alloy workpiece, pre-treating of the outersurface of the Al or Al alloy workpiece, and plating a metal layer comprising nickel onto the outersurface of the pre-treated workpiece. The invention also relates to a brazed assembly comprising at least one component made of the workpiece obtained by the method of this invention. The invention further relates to an aqueous plating bath for use in the method of this invention.DESCRIPTION OF THE RELATED ART[0003] For the purpose of this invention brazing sheet is to be understood as a core sheet, for example of aluminum or aluminum alloy, having on at least one side a brazeable aluminum alloy. Typical brazeable al...

AI Technical Summary

Problems solved by technology

Vacuum brazing is an essentially discontinuous process and puts high demands on material cleanliness.

This can cause difficulties with certain types of assemblies because of their design.

For example, because evaporator type heat exchangers have a large internal surface, problems can arise because of poor access to the interior.

Unfortunately the brazing flux after drying can easily fall off due to small mechanical vibrations.

However, the use of lead for the production of a suitable nickel and/or cobalt layer on brazing sheet has several disadvantages.

The plating baths for electroplating are rather complex and due to the presence of lead comprising components such as salts thereof, these baths are much more environmentally unfriendly than plating baths comprising nickel- or cobalt-components alone.

The use of lead for manufacturing products, such as automotive products, is undesirable and it is envisaged that in the very near future there might possibly even be a ban on lead comprising products or products manufactured via one or more intermediate processing steps comprising lead or lead-based components.

A further disadvantage of the plating bath described in U....