US2273806A - Platinum alloy - Google Patents

Description

Patented Feb. 17, 1942 PLATINUM ALLOY Edmund Merriman Wise, Westfield, and Raymond Francis Vines, Garwood, N. L, asslgnors to The International Nickel Company, Inc., New York, N. Y., a corporation of Delaware No Drawing. Original application April 24, 1941,

Serial No. 390,104? Divided and this applicatlon June 17, 1941, Serial No. 398,406. In Canada March 22, 1941 Claims. (01.75-172) The present invention relates to platinum alloys and more particularly to platinum alloys for use in jewelry, dental structures, and the like, and characterized by improved properties, especially hardness.

Heretofore, it has been proposed to incorporate iridium, ruthenium and/or osmium in platinum for use in jewelry, dental structures, electrical contacts, chemical equipment, etc., to harden the platinum. In addition to being more expensive than platinum, these alloys possessed certain disadvantages. The iridium-platinum alloys had a relatively higher melting point and were more difficult to cast in molds of the usual investments than was platinum. In addition, with the usual iridium contents of about 5% to the alloys were not very hard in the cast or fully annealed conditions and also had a higher density than platinum. The ruthenium-platinum and osmi- I um-platinum alloys, especially those containing more than about 5% of ruthenium or osmium,

gave ofi poisonous fumes during melting, had a higher melting point than platinum and did not have very good ductility. Because of the disadvantage of the higher ruthenium and osmium content alloys, the art has been limited essentially to the iridium-platinum alloys for applications where increased hardness was required. Although many attempts were made to. remedy the aforementioned shortcomings, none, as far as we are aware, was entirely successful when carried into practice commercially.

- We have discovered that the prior art shortcomings can be avoided and that new and unexpected results can be obtained by using small controlled amounts of tin as a hardener in platinum and platinum base alloys. We have discovered that platinum-tin alloys, especially platinum-ruthenium-tin alloys, possess improved hardnesses without loss of ductility, have lower melting points, and are easier to cast than the platinum-iridium alloys commonly used heretofore.

It is an object of the present invention to provide platinum-base alloys possessing improved hardnesses and containing small controlled amounts of tin.

It isanother object of the present invention to provide a novel hard platinum alloy which has a lower melting point, is easier to cast, and is lower in cost, while retaining good ductility, than the iridium-platinum alloy of similar hardness.

It is a further object of the present invention to provide a platinum-iridium-tin and a platinum-ruthenium-tin alloy having the same hardness as or higher hardness than a tin-free alloy containing higher amounts of iridium and ruthenium, respectively.

' This invention also contemplates dental structures and jewelry and other articles of manufacture made of the alloys provided by the present invention.

platinum-group metals such as iridium, palladium, osmium and rhodium, as well as or in place of ruthenium. Preferably, the platinum content of the alloys provided by the present invention will not be more than about 99.15% and will not be less than about 95% when other platinum group metals are not present in large amounts but may be as low as about 90% or particularly when substantial amounts of ruthenium and/or other platinum-group metals, such as iridium or palladium, are also present. In addition to tin and platinum group metal or metals, the alloys may contain small amounts less than about 5%-of base metals, e. g., copper, nickel, molybdenum, tungsten, etc. The base metals may be present as minor constituents which improve certain other desired properties. .Thus, the present invention includes platinum-copper-tin alloys containing tin and platinum in the amounts herein set forth and about 4% copper.

The use of small amounts of tin, i. e., about 0.35% to about 5%, in conjunction with the platinum group metal ruthenium in amounts up to 12%, say about 0.5% up to about 12%, and the balance substantially all platinum, i. e., about 85% to about 99.15% platinum, has produced marked improvement in the hardness values. In general when the maximum amount of tin is present the amount of ruthenium will be reduced. When the ruthenium content exceeds about 12% and/or the tin 'content exceeds about 5% the alloys become brittle and, in addition, high tin contents also deleteriously increase The alloys may contain minor amounts up to about 12% or about 15% of other cold rolling and after cold rolling and annealing.

low about 3%, for example, about 0.5% to about 1.5%, and the ruthenium content preferably does not exceed about 5% minus the tin content, i. e., the sum of the tin and ruthenium content does not exceed about 5%, for maximum ductility. Table I illustrates the beneficial hardening effect of small amounts of tin alone and in conjunction with ruthenium, upon platinum after Table I Composition V. H. N.

Alloy No.

Ru Pt Annd Per cent Per cent 100 Bal.

Bel. Ba].

V. H. N.=Vickers hardness number (10 kg. load). 0. R.=Cold rolled, 50% cold reduction. 1 Annd.=Annealed at ll00 C. for minutes and water quenched.

Alloy No. 2 containing about 0.5% tin and 2% ruthenium has a higher hardness than a 10% iridium-90% platinum alloy both in the No. 2 has substantially the same hardness as an alloy containing 4.5% ruthenium and 95.5% platinum.

The tin-containing platinum alloys provided by the present invention do not contain over about 5% tin, preferably not more than 3% tin for best ductility, Tin contents in excess of about 5% appear to detrimentally afiect the working properties and to cause cracking upon rolling, etc. Contrary to the belief that tin is detrimental in platinum and high platinum alloys due to its embrittling effect, we have made the astonishing discovery that platinum and high platinum alloys containing up to about 3% tin are ductile and exhibit satisfactory working properties. In general, it ispreferred to maintain the tin content toward the minimum values, for example, about 0.5%, for alloys to be fabricated into intricate design. A particularly suitable alloy for fabrication into intricate designs contains about 0.5% tin and the balance substantially all metals of the platinum group, the platinum content being at least 95%. A study of platinum alloys containing up to about 3% tin has revealed that such alloys apparently did not age harden and that the markedly increased hardness of the tin-containing alloys was not due to an age hardening effect. Some age hardening effects were observed in a 95/5 platinum-tin alloy.

The tin-containing platinum-base alloys of the present invention are characterized by improved hardnesses of at least about Vickers hardness number. When small amounts of ruthenium are present in the alloys the hardness will usually exceed about Vickers hardness number in the fully annealed condition. .Thus, an alloy containing about 0.5% tin and about 1% ruthenium would have a hardness of about to Vickers hardness number.

We have found that small amounts 'of tin have I much greater hardening effect than the same amount of known hardening agents for platinum such as iridium, ruthenium, osmium, rhodium,

gold, silver, nickel, copper, iron, etc. The beneficial and improved effects of tin compared to iridium in platinum alloys are illustrated in Table II which sets forth the comparative hardnesses in the fully annealed condition and the approximate melting points of various-alloys, and of substantially pure platinum.

Table II gy Composition gg g g V. H. N.

5 0 Sn, 4.5% Pd, 95% Pt. 1, 730 90 V. H. N.=Vickers hardness number (10 kg. load) after 50% cold reduction followed by annealing at l,l00 C. for 30 minutes and water quenching.

Alloys Nos. 8, 9 and 10 which were made in accordance with the present invention show marked increases in hardness, while retaining good ductility with comparatively small amounts of tin. As illustrated by alloy No. 8 in Table II, even 0.5% tin present in a 5% iridium-platinum alloy results in a marked improvement in hardness over the same alloy free from tin (alloy No. 4) without damaging the working properties of the. alloy.

The markedly improved properties of a platinum alloy containing 5% palladium and 1% tin is illustrated by alloy No. 9. Alloy 9 is ductile and has a hardness as high as the more expensive iridium-platinum alloy containing 10% iridium (alloy No. 5). Compared with a similar alloy not containing tin (alloy 7), alloy 9 and alloy 10 have markedly improvedhardness while exhibiting advantageous lower melting points.

In addition to platinum and tin, the alloys of the present invention may contain small amounts of incidental or minor constituents and impurities and when we state that platinum constitutes the balance or that the balance is-substantially all platinum or substantially all platinum group metals-or substantially all metal of the platinum group we do not intend to exclude small amounts of incidental or minor constituents and impurities. Thus, the alloys may contain small amounts of base metals, for example, copper, nickel, molybdenum, tungsten, etc., in small amounts more than 0.01% and less than 5%. Likewise, the platinum-base alloys may contain small amounts of other known non-platinum group metal hardeners of platinum to supplement the beneficial effects of tin. Furthermore, the alloys may contain small amounts of iron. magnesium, calcium and other elements commonly associated with platinum and platinum' alloys. It is to be understood that when it is stated that the balance is "platinum or substantially all platinum or that the balance is "substantially all metal of the platinum group or substantial- 1y all platinum group metals, we do not excludefrom the scope of the expression incidental and minor constituents and impurities which may be present in such amountsas occur in commercially available platinum and in commercially produced platinum products, or in amounts not adversely afiecting the desired properties of the platinum-base alloy. I

The present invention provides hard articles of manufacture made of the platinum alloys described hereinbefore. The articles contemplated herein may be made of cast or wrought alloys. Illustrative examples are given in Table III of suitable wrought alloys for the manufacture of articles where high platinum group metal content and good workability combined with adequate hardness is required.

Table III Sn Other metals Pt Percent Percent Percent 4.5 O. P. M Balance. 0. 5 4.5 Ru Do. 0.5 3-15 It D0. 0.5 3i5 Pd Do.

'0. P. M.=Platinnm-group metal other than platinum.

Larger amounts of tin may be used where high purity is not a primary factor but where good ductility is desired it is preferred that the tin content not exceed about 3%.

Illustrative examples are given in Table IV .of cast alloys and castings suitable for articles .where high hardness combined with adequate ductility are primary factors and where highest purity is not essential.

Table IV '0. P. M.=Platinum-group metal other than platinum.

Illustrative examples of wrought and/or cast articles within the scope of the present invention includecast and wrought dental structures, restorations and the like, for example, cast dental restorations, such as bridges, inlays, crowns, abutments, etc.; cast and wrought jewelry, for

example rings, chains, brooches, clips, pins, enamelled jewelry, etc., especially when such items are mounted with diamonds. High hardness is desirable to insure retention of gems; to prevent distortion and to reduce scratching and wear. The corrosion-resisting properties, refractory properties, etc., combined with improved hardness and wear resistance render the alloys oi. the present invention also suitable for use in such articles as chemical ware and equipment, electric contacts, etc.

The present application is a divisional cas of our co-pending application, Serial No. 390,104,

, filed April 24, 1941.

. parent to those skilled in the art are considered platinum.

Although the present invention has been de scribed in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spiritan'd scope of the invention, as those skilled in the art will readily understand. Such variations and modifications ap- 3. A workable platinum alloy comprising about 0.45% to about 1.5% tin, about 2% to about 4.5% ruthenium, and the balance substantially all platinum.

4. A platinum-base .alloy comprising about 0.35% to about 5% tin, about 0.5% to about 15% of at least one metal of the group consisting of ruth nium, iridium, palladium, osmium and rhodium, and the balance substantially all platinum.

5. A platinum alloy comprising about 0.35% to about 3% tin,'about 0.5% to about 5% of at least one metal of the group consisting of ruthenium, iridium, palladium, osmium and rhodium, and

the balance substantially all platinum.

EDMUND MERRIMAN WISE. RAYMOND FRANCIS VINES.