The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 25, 1989
Filed:
Apr. 03, 1986
Amchem Products, Inc., Ambler, PA (US);
Abstract
In chromium-free aqueous acidic washing solutions for cleaning the surfaces of aluminum and aluminum-alloy particles, so as to remove therefrom smut and lubricating oil left on the surfaces thereof after metal forming operations, which solutions contain from 0.2 to 4 g/l ferric ion and sufficient sulfuric and/or nitric acid to impart a pH of 2 or less to the solutionh (and which optionally may also contain fluoride ions up to a concentration of 0.5 g/l) there is provided a method of controlling the effectiveness of the washing solution in which the ferric ion concentration therein is monitored, conveniently by the oxidation-reduction potential of the washing solution, as shown in FIG. 3, and is controlled within the desired limits by adding when appropriate suitable amounts of oxidant capable of oxidizing ferrous ions to ferric ions and, separately or in conjunction therewith, a replenisher containing a source of iron ions.