Metal treatment – Process of modifying or maintaining internal physical... – Processes of coating utilizing a reactive composition which...
Reexamination Certificate
2000-10-13
2002-08-13
Sheehan, John (Department: 1742)
Metal treatment
Process of modifying or maintaining internal physical...
Processes of coating utilizing a reactive composition which...
C148S274000, C148S275000, C148S286000, C106S014110, C106S014150, C252S389530
Reexamination Certificate
active
06432225
ABSTRACT:
FIELD OF THE INVENTION
This environmental-quality invention is in the field of chemical conversion coatings formed on aluminum and aluminum alloy substrates. One aspect of the invention is an improved process of forming an oxide coating, referred to as a “cobalt conversion coating,” that is chemically formed by oxidizing the surface of an aluminum or aluminum alloy substrate. The invention enhances the quality of the environment of mankind by contributing to the maintenance of air and water quality. The term “aluminum” as used herein includes aluminum and aluminum alloys.
BACKGROUND ART
Reference is made to the following patents, which are incorporated by reference herein: U.S. Pat. No. 5,298,092, issued Mar. 29, 1994; U.S. Pat. No. 5,415,687, issued May 16, 1995; U.S. Pat. No. 5,472,524, issued Dec. 5, 1995; U.S. Pat. No. 5,487,949, issued Jan. 30, 1996; U.S. Pat. No. 5,378,293, issued Jan. 3, 1995; U.S. Pat. No. 5,411,606, issued May 2, 1995; U.S. Pat. No. 5,551,994, issued Sep. 3, 1996; and U.S. Pat. No. 5,873,953, issued Feb. 23, 1999.
Recently, I have made significant improvements to this technology to further improve bath life and bath stability as well as coating performance characteristics. The details are described below.
Environmental regulations in the United States are mandating drastic reductions of allowed chromium compounds in effluent as well as emissions into the air which are generated from metal finishing processes. I have devoted considerable effort to the development of a non-chromated surface coating as a replacement for current chromated processes as detailed in MIL-C-5514 and Boeing Process Specification BAC 5719.
Chromium containing conversion coatings are used by The Boeing Company, its subcontractor base and generally throughout the industry. Solutions used to produce these conversion coatings contain carcinogenic hexavalent chromium, fluorides, and cyanides, all of which present a significant environmental, health, and safety problem. The constituents of a typical chromate conversion-coating bath are as follows: CrO
3
“chromic acid” (hexavalent); NaF sodium fluoride; KF
4
B potassium tetrafluoborate; K
2
ZrF
6
potassium hexafluorozirconate; K
3
Fe(CN)
6
potassium ferricyanide; and HNO
3
nitric acid.
Current chromium conversion films are deposited by immersion, meet a 168-hour corrosion resistance requirement when tested to ASTM B117, but also serve as a surface substrate to promote paint adhesion. Typical coating weights of these chromium films range from 40 to 120 mg/ft
2
and do not cause a fatigue life reduction of the aluminum substrate.
SUMMARY OF THE INVENTION
In one aspect the invention is an improved process that is commercially practical for forming an oxide film cobalt conversion coating exhibiting corrosion resistance and paint adhesion properties on a substrate, where the substrate is aluminum or aluminum alloy, the process including the steps of:
(a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution, containing no triethanolamine (TEA), prepared by reacting the following starting materials:
(1) a water soluble cobalt-II salt CoX
2
where X=Cl, Br, NO
3
, CN, SCN, ⅓PO
4
, ½SO
4
, ½CO
3
, formate, or acetate;
(2) a water soluble complexing agent selected from the group consisting of MeNO
2
, MeAc, MeFm, NH
4
Ac, and NH
4
Fm where Me is Na, K, or Li; Ac is acetate; and Fm is formate;
(3) an accelerator selected from the group consisting of NaClO
3
, NaBrO
3
, and NaIO
3
;
(4) water; and
(b) contacting the substrate with the aqueous reaction solution for a sufficient amount of time to oxidize the surface of the substrate, whereby the oxide film cobalt conversion coating is formed, thereby imparting corrosion resistance and paint adhesion properties to the substrate.
In another aspect the invention is a chemical conversion coating solution that is commercially practical for producing an oxide film cobalt conversion coating on an aluminum or aluminum alloy substrate, said solution comprising an aqueous reaction solution, containing no triethanolamine (TEA), prepared by reacting the following starting materials:
(1) a water soluble cobalt-II salt CoX
2
where X=Cl, Br, NO
3
, CN, SCN, ⅓PO
4
, ½SO
4
, ½CO
3
, formate, or acetate;
(2) a water soluble complexing agent selected from the group consisting of MeNO
2
, MeAc, MeFm, NH
4
Ac, and NH4Fm, where Me is Na, K, or Li; Ac is acetate; and Fm is formate;
(3) an accelerator selected from the group consisting of NaClO
3
, NaBrO
3
, and NaIO
3
;
(4) water.
In yet another aspect the invention is an improved process that is commercially practical for forming an oxide film cobalt conversion coating exhibiting corrosion resistance and paint adhesion properties on a substrate, where the substrate is aluminum or aluminum alloy, the process comprising the steps of:
(a) providing an oxide film forming cobalt conversion solution comprising an aqueous reaction solution, containing no triethanolamine (TEA), prepared by reacting the following starting materials:
(1) a water soluble cobalt-II salt CoX
2
where X=Cl, Br, NO
3
, CN, SCN, ⅓PO
4
, ½SO
4
, ½CO
3
, formate, or acetate;
(2) an ammonium salt NH
4
X where X=Cl, Br, NO
3
, CN, SCN, ⅓PO
4
, ½SO
4
, ⅓CO
3
, formate, or acetate;
(3) ammonium hydroxide (ammonia);
(4) an accelerator selected from the group consisting of NaClO
3
, NaBrO
3
, and NaIO
3
;
(5) water; and
(b) contacting the substrate with the aqueous reaction solution for a sufficient amount of time to oxidize the surface of the substrate, whereby the oxide film cobalt conversion coating is formed, thereby imparting corrosion resistance and paint adhesion properties to the substrate.
And in yet another aspect the invention is a chemical conversion coating solution that is commercially practical for producing an oxide film cobalt conversion coating on an aluminum or aluminum alloy substrate, the solution comprising an aqueous reaction solution, containing no triethanolamine (TEA), prepared by reacting the following starting materials:
(1) a water soluble cobalt-II salt CoX
2
where X=Cl, Br, NO
3
, CN, SCN, ⅓PO
4
, ½SO
4
, ½CO
3
, formate, or acetate;
(2) an ammonium salt NH
4
X where X=Cl, Br, NO
3
, CN, SCN, ⅓PO
4
, ½SO
4
, ½CO
3
, formate, or acetate;
(3) ammonium hydroxide (ammonia);
(4) an accelerator selected from the group consisting of NaClO
3
, NaBrO
3
, and NaIO
3
; and
(5) water.
REFERENCES:
patent: 1551613 (1925-09-01), Pacz
patent: 1607676 (1926-11-01), Jirotka
patent: 2796370 (1957-06-01), Ostrander et al.
patent: 2796371 (1957-06-01), Ostrander et al.
patent: 2906009 (1959-09-01), Knoll et al.
patent: 3138479 (1964-06-01), Foley
patent: 3403035 (1968-09-01), Schneble et al.
patent: 3423214 (1969-01-01), Koretzky
patent: 3438798 (1969-04-01), Baudrand et al.
patent: 3444007 (1969-05-01), Maurer et al.
patent: 3592747 (1971-07-01), Cohn
patent: 3615740 (1971-10-01), Goltz
patent: 3790453 (1974-02-01), Wanamaker et al.
patent: 3819424 (1974-06-01), Russell et al.
patent: 3870607 (1975-03-01), Bardach
patent: 3877981 (1975-04-01), Arnold
patent: 3905838 (1975-09-01), Ito
patent: 3928237 (1975-12-01), Davis
patent: 3954510 (1976-05-01), Gunn et al.
patent: 3993510 (1976-11-01), Bellavin
patent: 4088486 (1978-05-01), Bissonette
patent: 4150172 (1979-04-01), Kolk, Jr.
patent: 4208212 (1980-06-01), Kuzuwata et al.
patent: 4218240 (1980-08-01), Gingerich et al.
patent: 4233063 (1980-11-01), Ritsko et al.
patent: 4261766 (1981-04-01), Crouch
patent: 4278263 (1981-07-01), Vanderpool et al.
patent: 4278477 (1981-07-01), Reinhold
patent: 4337097 (1982-06-01), Tokumasu et al.
patent: 4348224 (1982-09-01), Gingerich et al.
patent: 4381203 (1983-04-01), Reinhold
patent: 4392920 (1983-07-01), McDonald
patent: 4631093 (1986-12-01), Etemovich
patent: 4637374 (1987-01-01), Arai
patent: 4647347 (1987-03-01), Schoener
patent: 4659605 (1987-04-01), Malik et al.
patent: 4696724 (1987-09-0
Cullom, Jr. Paul C.
Oltmans Andrew L.
Sheehan John
The Boeing Company
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