Metal treatment – Stock – Amorphous – i.e. – glassy
Reexamination Certificate
1999-03-16
2001-07-03
Jones, Deborah (Department: 1775)
Metal treatment
Stock
Amorphous, i.e., glassy
C428S548000, C428S551000, C428S650000
Reexamination Certificate
active
06254699
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to aluminum-copper-iron quasicrystal alloys and in particular to wear-resistant quasicrystal coatings that exhibit non-adhesive properties.
2. Description of Related Art
Quasicrystals are materials whose structure cannot be understood within classic crystallographic methodology. These quasiperiodic structures have a long-range orientation order, but lack transitional periodicity. Conventional crystals consist of repeated copies of a single geometric atomic arrangement—a unit-cell stacked upon each other like bricks. Quasicrystals, on the other hand, while also being built up from a single type of atomic clusters, differ in that adjacent clusters overlap, sharing atoms with their neighbors. When clusters overlap by sharing atoms (quasiperiodic packing), they produce denser atomic arrays than conventional, periodic, repeated packing patterns.
The non-periodic structure of quasicrystal yields a broad, previously unobtainable range of physical properties embodied within a single material. Quasicrystals exhibit poor thermal conductivity while remaining stable up to about 1100° C. Thus, a thin layer on a heat-conducting surface will distribute heat evenly eliminating “hot spots”. These hard coatings promote wear and scratch resistance. Furthermore, due to their low coefficient of friction and electronic structure (low surface energy), they possess non-adhesive properties. Finally, they offer resistance to both corrosion and oxidation.
Researchers have identified over eight hundred different quasicrystal alloys. Many of these alloys contain a combination of aluminum, copper and iron. The Al—Cu—Fe alloys yield the specific icosahedral quasicrystal identified in atomic percent as Al
65
Cu
20
Fe
15
. (This specification expresses all compositions in weight percent, unless specifically stated otherwise). Furthermore, in some instances these alloys contain additional alloying elements such as, chromium, cobalt and nickel. This enables the alloy to accommodate specific operating conditions. For example, DuBois et al., in U.S. Pat. No. 5,204,191, describe several Al—Cu—Fe alloys containing quasicrystalline phases.
Regardless of chemistry however, quasicrystals do not lend themselves to conventional fabrication. They can not be formed or readily cast; however, they can be reduced to powder and thermally sprayed to form an adherent, useful coating. As far as known however, none of these alloys have established widespread commercial usage.
It is an object of this invention to produce an Al—Cu—Fe quasicrystal alloy coating having increased hardness for improved wear resistance.
It is a further object of this invention to produce an Al—Cu—Fe quasicrystal alloy coating having non-adhesive properties and oxidation resistance.
It is a further object of this invention to produce an Al—Cu—Fe quasicrystal alloy coating having a smooth-high density surface.
SUMMARY OF THE INVENTION
A thermally sprayed coating formed with a quasicrystal-containing alloy, the alloy consisting essentially of, by weight percent, 10 to 45 Cu, 7 to 22 Fe, 0 to 30 Cr, 0 to 30 Co, 0 to 20 Ni, 0 to 10 Mo, 0 to 7.5 W and balance aluminum with incidental impurities. The alloy contains at least 50 weight percent &psgr; phase. The coating has a macro hardness of at least about HR15N 75.
REFERENCES:
patent: 5204191 (1993-04-01), Dubois et al.
patent: 5432011 (1995-07-01), Dubois et al.
patent: 5433978 (1995-07-01), Shield et al.
patent: 5571344 (1996-11-01), Dubois et al.
patent: 5652877 (1997-07-01), Dubois et al.
patent: 5851317 (1998-12-01), Biner et al.
Peterson, “A Quasicrystal Construction Kit”, Science News, vol. 155 (1999) pp. 60-61 (no month).*
Sordelet “Synthesis Characterization and Physical Properties of A1-Cu-Fe Quasicrystalline Plasma Sprayed Coatings”, Dissertation, Iowa State University (1995) (no month).
Biederman Blake T.
Jones Deborah
Praxair S.T. Technology, Inc.
Savage Jason
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