US2189571A

US2189571A - Alloys

Info

Publication number: US2189571A
Application number: US294646A
Authority: US
Inventors: Sivil Cecil Spencer; Edward O Liebig
Original assignee: Baker and Co Inc
Current assignee: Baker and Co Inc
Priority date: 1939-09-13
Filing date: 1939-09-13
Publication date: 1940-02-06
Anticipated expiration: 1957-02-06

Description

Patented Feb} 6, 1940 UNITED STATES PATENT OFFICE Liebig, Arlington, N.

1., assignors to Baker &'

Company, Inc., Newark, N. J., acorporation of 7 New Jersey No Drawing. Application September-'13, 1939, Serial No. 294,646

7 Claims.

This application is a continuation in part of our application Serial No. 231,754, filed September 26, 1938, allowed April 5, 1939, and this invention relates in general to alloys .and more particularly to alloys for use in dentures and dental ically worked into suitable shapes, which shall' have great hardness and high tensile strength to 15 take and retain a high polish and to withstand stresses, particularly such as are incident to use in dental appliances, and which shall have a high temperature softening point so as topermit operations involving high temperatures, such as sol- 20 daring, welding, casting other metals against it, and the like, without the great strength being lost.

We have found that alloys of platinum, palladium, silver and gold are admirably suited for 20 the purpose with the proportions of the metals varying from 20 to 60% platinum, from to 40% palladium, from 10 to 50% silver, and from 1 to 25% gold. If particularly great corrosion resistance is desired the combined content of platinum a0 and gold should not fall below about 40% and as 40% palladium, from %to 50% silver and from 1% to gold, are desirable, while when great hardness and high corrosion resistance even toward contaminated acids are desired-the iollowing alloys are especially satisfactory:

40 (ll 40% platinum, 30% palladium, silver,

5% gold.

(2) 40% platinum, 25% palladium, 25% silver, 10% gold.

Those alloys having the gold content ranging- Experience has shown that these preferred alloys are resistant for extended periods or time to acids contaminated with iron and materials a usuallyoccurrinsinpicklingacidsusedindental laboratories, such as oxyphosphate cements, etc., even when in contact with other metals or alloys having a difierent electrical potential.

The alloys have been found to be highly resistant to corrosion and attack by acids including those acids most commonly used in dentistry, such as hydrochloric acid,.nitric acid and sulphuric acid, concentrated as well as dilute.

Also they have great hardnessand high tensile strength which is extremely desirable where denm) tal appliances are subject to stresses; for example the alloy containing 40% platinum,- palladium, 25% silver, 5% gold has, when hard, an ultimate tensile strength of 168,000 pounds per square inch and a Rockwell hardness of 110 B 15 scale. While sumcient restoration of ductility for further working is obtained by heating below 1200 C., the alloys do not become dead soft until they have been heated above 1200 C. When heated at the lower temperatures sufiicient hard- 20 ness is retained to render the alloys particularly suited for appliances subject to soldering and welding operations and for appliances against which other metals or alloys are cast, especiallysince such operations are carried out at temperg5 atures of 100 to 900 C. A clasp wire, for instance, may be soldered to dentures, or the dental metal or alloy may be cast against the clasp wire without danger of softening of the metal of the wire and without danger of overheating which 30 might affect detrimentally the structure of the alloy.

It should be understood that the limited proportions above speciiied are not critical and that suitable alloys may be formed with the metal proportions varying more or less from the maximum and minimum limits specifically stated.

Furthermore, the alloys may also contain small quantities, for example up to a few percent, of

any, other metal or metals which will not dele- I teriously aflect the iundamental characteristics of the alloys as described, such as another metal of the platinum group other than platinum and palladium, or; heavy base metals or metals contributing to age hardening such as tin, zinc and 5 cadmimn.

The alloys are especially useful for dental devices that are used in the mouth, such as orthodontia 'wirm, tooth bands, orthodontia locks, clasps, dentures and kindred devices.

Having thus described our invention, what we claim is:

- 1. An alloy of from twenty (20) to sixty (00) percent platinum, ten (10) to forty (40) peroentpalladlum, ten (10) toflity percent silu ver, and from one (1) to twenty-five (25) percent 801d.

2. An alloy of from twenty (20) to sixty (60) percent platinum, ten (10) to forty (40) percent palladium, ten (10) to fifty (50) percent silver, and from one (1) to twenty-five percent gold, wherein the combined content of platinum and gold is not less than about forty (40) percent and the combined content of palladium and silver is not more than sixty (60) percent.

3. An alloy of about thirty to forty percent platinum, from about twenty-five (25) to thirty (30) percent palladium, about twenty (20) to twenty-five (25) percent silver, and from about ten (10) to twenty-five (25) percent gold.

4. An alloy composed of from twenty (20) to fifty percent platinum, fifteen (15) to forty (40) percent palladium, fifteen (15) to fifty (50) percent silver, and from one (1) to twenty (20) percent gold.

5. An alloy composed of from twenty (20) to fifty (50) percent platinum, fifteen (15) to forty (40) percent palladium, fifteen (15) to fifty (50) percent silver, and from one (1) to twenty (20) percent gold, wherein the combined content of platinum and gold is not less than about forty (40) percent and the combined content of palladium and silver is not more than about sixty percent.

6. An alloy composed of from twenty (20) to fifty (50) percent platinum, fifteen (15) to forty (40) percent palladium, fifteen (15) to thirtyfive (35) percent silver, and from one (1) to twenty (20) percent gold, wherein the combined content of platinum and gold is not less than about forty (40) percent and the combined content of palladium and silver is not more than about sixty (60) percent.

7.An alloy consisting of about forty (40) percent platinum, irom about twenty-five (25) to thirty (30) percent palladium, about twenty-five (25) percent silver, and from about five (5) to ten (10) percent gold.

CECIL S. SIVIL. EDWARD O. LIEBIG.