US1999866A - Allot - Google Patents

Description

Patented Apr. 30, 1935 UNITED. STATES ALLOY Edward A. Capillon,

Baker & Company,

Attleboro. Mass. 'erlc E. Carter, Maplewood, N. 1., Inc., Newark,

poration of New Jersey No Drawing.- Original application April 25, 1984, a

Serial No. 722,316. tion July 4 Claims.

This application is a division of our copending application Serial No. 722,316 and, the invention relates in general to alloys and more particularly to an alloy to be used for the manufacture of 5 watch cases, optical frames, jewelry, dental appliances and metal parts of dentures, electrical switch contacts and conductors and the like; and the alloy may be used either alone or as a substitute for the gold alloys at present used in the manufacture of gold-filled or rolled gold plate articles.

One object of the invention is to provide an alloy containing a major portion of precious metals other than gold which shall be at least the equal of the gold alloys heretofore generally used in many properties and the superior of such gold alloys in other properties or characteristics for the purpose specified, and at the same time can be produced at less cost than the usual gold aloys.

Another object of the invention is toprovide an alloy which shall be less subject to tarnish and more resistant to attack by nitric acid than gold alloys, and which shall be sufiiciently soft to permit easy working without undue damage to tools and dies, and yet shall be hard enough to withstand wear and have some resiliency or springiness which is especially desirable in optical frames and jewelr Other objects and advantages of the invention will appear from the following description.

We have discovered that for the purpose described, useful alloys can be produced by combining palladium, platinum, silver, and a base metal, for example, a metal of the iron group, or copper, when palladium constitutes at least thirty per cent of the alloy. Palladium has a much lower specific gravity than gold, is less expensive and at the same time has better resistance to tarnishing and acid attack than the usual gold alloys; but palladium alone is too soft to withstand the wear incident to use in optical frames, jewelry and'watch cases. The combining of silver with the palladium in part compensates this softness of palladium and makes the alloy harder, although the alloy is much softer than, for example, white gold. Moreover, silver is relatively inexpensive which aids in producing the alloy at low cost. While silver has relatively less resistance than gold alloys to tarnish and acid attack, the palladium in the alloy greatly reduces the tendency to'tarnishing of the silver. Greater degree of hardness to provide a certain degree of springiness in the alloy and without material in- Div] 10, 1934, Serial No. 734,507

ded and this applicacrease in cost, which is desirable in optical frames and jewelry, is obtained by adding a relatively inexpensive base metal, for example, nickel, iron, cobalt or copper. The alloys have a fine whitish in quality excels the color of white gold.

The aforesaid alloy consisting of palladium silver and the base metal, has a high degree of resistance to tarnish'andacid attack, but the resistance is not complete. In many cases complete resistance to corrosion is highly desirable, and while working to accomplish this result, we discovered that the addition to the other metals of a relatively small amount of platinum'gives the unexpected effect of rendering the alloy practically completely resistant to tarnish and acid attack. Platinum is at the present time only slightly more costly than gold, and thus this remarkable efiect of such a small amount of platinum, is obtained at only a slight increase in cost, which is important where it is desired to provide an alloy at about the same or lower cost than the usual gold alloys.

We have found that these metals can be combined in difference proportions to produce satisfactory alloys. Good alloys may contain from thirty-five to seventy percent of palladium and platinum of which the major portion is palladium, the remainder of the alloy being silver, and a base metal with the amount of silver several times greater than the amount of base metal. The preferred alloy consists of about forty to forty-five percent of palladium, about five to ten percent of platinum, about forty-five percent of silver, and about five percent of base metal, for example, nickel, iron, cobalt or copper.

In all cases it is an important feature of the alloy that the small amount -of platinum very remarkably and unexpectedly increases the resistance of the alloy to tarnish and acid attack, and the great significance of this feature is emphasized when the relatively low resistance of the other component metals of the alloy to tarnish and acid attack, is remembered.

The alloy is less subject to tarnish and attack by'acids than the usual gold alloys. It has a lower specific gravity than gold and because of this and the lower cost of the metals, the alloy is less expensive than an alloy having a percentage of gold by weight equal to that of the percentage of the palladium and platinum in our alloy. The alloy is softer than white gold alloys and can be more easily worked, and yet is sufficiently hard to withstand wear and has mainder oi the alloy being sflver and about five percent oi nickel. A

3. An alloy consisting of iromforty to fortyfive percent of palladium, from five to ten percent of platinum, about forty-five percent of silver, and about five percent of nickel.

4. An alloy consisting 01.1mm thirty-five percent to seventy percent of palladium and platinum of which five to ten percent is platinum, the

remainder of the alloy being silver and about five 10 percent or a metal of the nickel group.

. EDWARD A. CAPILLON.

FREDERIC E. CARTER.