Stock material or miscellaneous articles – Composite – Of metal
Reexamination Certificate
1999-02-08
2001-06-12
Gorgos, Kathryn (Department: 1741)
Stock material or miscellaneous articles
Composite
Of metal
Reexamination Certificate
active
06245436
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to treatment of aluminum and aluminum alloy bodies by anodic spark deposition to form a novel lubricant-retaining and mechanically durable surface layer.
2. Description of Related Art
Fuel pump bodies commonly used to supply fuel to internal combustion engines now are made of hard-anodized and water-sealed cast aluminum alloys. For example, an anodized coating thickness of 18 microns, anodized surface roughness of 1.0 micron R
a
, and anodized surface hardness of about 250 Hv are specified for certain vehicle cast aluminum alloy fuel pump bodies. Fuel pumps including such hard-anodized and water-sealed pump bodies generally are replaced at least once in the lifetime of most vehicles as a result of the pump body caused by abrasive deposits and fuel impurities. Such abrasive wear occurs as a result of insufficient hardness of the anodized surface layer formed on the cast pump body. In particular, conventional hard anodizing has been found to generally produce a mixture of crystalline and amorphous alumina on the anodized surface with significant amounts of layer porosity even after a water sealing treatment whereby the anodized surface exhibits insufficient hardness and wear resistance.
There thus is a need for a surface treatment for fuel pump bodies made of aluminum and its alloys to impart improved surface hardness and wear resistance thereto.
SUMMARY OF THE INVENTION
An object of the present invention is to satisfy this need by subjecting an aluminum or aluminum alloy body to anodic spark deposition under deposition conditions in an electrolyte effective to form a surface layer that is enriched in alpha alumina to improve surface hardness and that includes lubricant-retaining surface pores distributed across an outer surface of the layer. The surface layer may be doped in-situ during deposition with a solid state lubricant. Aluminum or aluminum alloy bodies, such as fuel pump bodies discussed above, having such a surface layer formed thereon exhibit improved wear resistance as compared to conventional hard-anodized and water-sealed aluminum or aluminum alloy bodies.
REFERENCES:
patent: 3862892 (1975-01-01), Lautenschlager et al.
patent: 4276007 (1981-06-01), Sakamaki et al.
patent: 5094727 (1992-03-01), Schwarz et al.
patent: 5385662 (1995-01-01), Kurze et al.
patent: 5487825 (1996-01-01), Kurze et al.
patent: 5980723 (1999-11-01), Runge-Marchese et al.
Hubner and Schiltknecht: The Practical Anodising of Aluminum, p. 24, No month available/1960.
Boyle David
Collins David Robert
Pergande Paul Earl
Popoola Oludele Olusegun
Wong Tony Leung
Gorgos Kathryn
Tran Thao
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