Metal treatment – Compositions – Heat treating
Patent
1978-08-30
1980-05-27
Rutledge, L. Dewayne
Metal treatment
Compositions
Heat treating
148 115C, C22C 901, C22F 108
Patent
active
042048834
ABSTRACT:
A copper base alloy of superior tarnish resistance consisting essentially of 7.0 to 8.5% aluminum by weight and 1.5 to 2.5% nickel by weight with the balance (89-91.5 wt %) being essentially copper.
The process by which the alloy is prepared is controlled so that the alloy is primarily single phased, i.e., a face centered cubic alpha phase solid solution containing a fine dispersion of nickel aluminide compound (NiAl) and less than 2 volume percent of the brittle intermetallic phases known as beta and gamma. By composition control and by producing an essentially single phase microstructure, the alloys of the invention are capable of forming a stable oxide film having high tarnish resistance.
The alloy, upon prolonged exposure indoors to ambient air and frequent handling, develops a very thin, tight, uniform oxide film which, although visible, is still attractive and does not mask the basic warm tone of the base metal. This film, when intact, serves to protect the underlying metal from further oxidation, and when damaged, is self-healing and reestablishes itself to provide a uniform protective and decorative film.
REFERENCES:
patent: 1496269 (1924-06-01), Iytaka
patent: 3297497 (1967-01-01), Eichelman, Jr. et al.
patent: 4113475 (1978-09-01), Smith
The Journal of the Institute of Metals, 1937, vol. LXI, pp. 83-102.
The Journal of the Institute of Metals, 1939, vol. LXV, pp. 217-223.
Kennecott Copper Corporation
Lorusso Anthony M.
Rutledge L. Dewayne
Skiff Peter K.
Sniado John L.
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