US2273805A - Platinum alloy - Google Patents

Description

Patented Feb. 17, 1942 UNITED STATES PATENT OFFICE 2,273,805 PLATINUM ALLOY .Edmund Merriman Wise, Westfield, and Raymond Francis Vines, Garwood, N. J., assignors to The International Nickel Company, Inc., New York, N. Y., a corporation of Delaware No Drawing. Application April-24, 1941, Serial No. 300,104. In Canada March 22, 1941 3 Claims.

' 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 osmiumplatinum 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 disadvantages of the higher ruthenium and. osmium content alloys, the art has been limited essentially to the iridiumplatinum .alloys for applications where increased hardness was required. However, as pointed out hereinbefore, the iridium-platinum alloys were costly, had a high melting point and were difficult to cast in the usual investments. The art has been constantly seeking to overcome these and other disadvantages and 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 canbe obtained by using small controlled amounts of tin as a hardener in platinum and platinum base alloys. We have discovered that platinum-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.

balance substantially all platinum.

lower in cost, while retaining good ductility, than the iridium-platinum alloy of similar hardness.

The present invention contemplates new hard platinum alloys for jewelry purposes, dental purposes, etc., which do not require the use of the rare and costly element iridium.

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

Other objects and advantages of the invention will become apparent from'the following description.

The invention provides improved platinumbase alloys containing small but effective amounts of tin, say about 0.35% to about 5%, and the In addition to tin and platinum, 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 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 affect the working propertiesand to cause cr'acking'upon rolling, etc. Contrary to the belief that tin is detrimental in platinum and high platinum alloys due' to its embrittling'efiect, 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 is pneferred 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 platinum. A study of platinum alloys containing up to about 3% tin has revealed that such alloys apparently did not age harden andthat the markedly in- It is anobject of the present invention to proa lower melting point, is easier to cast, and is creased 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. 1

The tin-containing platinum-base alloys of the present invention are characterized by improved hardnesses of at least about Vickers hardness number.

The improved hardening effects of tin as contemplated herein are obtained in alloys containing a small but effective amount of tin, say about 0.35%, to about 5% tin, and the balance platinum, i. e., about 95% to 99.65% platinum. Preferably, the alloys contain at least about 0.45 or 0.5% tin and up to about 3% tin where maximum ductility is desired. Wehave found that small amounts of tin have much greater hardening efiect 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 I which sets forth the comparative hardnesses in the fully annealed condition and the approximate melting points of tin-platinum, and iridium-platinum alloys, as well as of substantially pure platinum.

Table I Melting Composition Point Pure platinum V. H. N.=Vickers hardness number (10 kg. load) after 50% cold reduction followed by annealing at 1,l C. for 30 minutes and Water quenching.

over from the ore, incorporated during process- 7 ing, etc. Some of the purer grades of commercially available platinum may contain only about 0.001% or 0.01% of other platinum group metals while less pure grades may contain more. As will be apparent to those skilled in the art, the incidental elements and impurities contained in platarticle.

Alloys Nos. 5, 6 and 7 which were made in accordance with the present invention show marked increases in hardness, while retaining good duc- Alloys No. 6 and No.-7 which contained about 3% and about tin, respectively, possessedhigher hardnesses than alloys No. 2 and No. 3 which contained 10% and iridium, respectively.

The accompanying beneficial eifect of tin com- I pared to iridium in lowering the melting point while increasing the hardness is clearly illustrated in Table I.

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 we do not intend to exclude small amounts of incidental or minor constituents and impurities. small amounts of base metals, for example, copper, nickel, molybdenum, tungsten, etc., in small I amounts more than 0.01% and less than 5%.

Likewise, the platinum-base alloys may contain I 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 com- Thus, th alloys may contain inum may be carried over into-thefinal alloy or It isto be understood that when it is stated that the balance is platinum or substantially all platinum, we do not exclude from the scope of the expression incidental and minor constituents and impurities which may be present in such amounts as occur in commercially available platinum and in commercially produced platinum products, or in amounts not adversely affecting the desired properties of the platinumbase alloy.

The present invention provides hard articles of manufacture made of the platinum alloys described hereinbefore and containing small but eflective amounts of tin, for example, alloys containing about 0.35% to about 5% tin and the balance substantially all platinum, said platinum alloys possessing improved castability when molten and improved hardness in the solid state while retaining goodductility. The articles contemplated herein may be made of cast or wrought alloys. An illustrative example of a suitable wrought alloy for the manufacture of articles where high platinum group metal content and good workability combined with adequate hardness is required contains 0.5% tin and balance substantially all 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%. An illustrative example of a cast alloy and casting suitable for articles where high hardness combined with adequate ductility are primary factors and where highest purity is not essential contains 1% to 3% tin and the balance substantially all platinum.

Illustrative examples of wrought and/or cast articles within the scope of the present invention include 'cast 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,,

parting from the spirit and scope of the invention, as those skilled in the artwill readily understand. Such variations and modifications apparent to those skilled in the art are considered to be within the purview and scope of the ap- 0.35% to about 3% tin and the balance substan pended claims. tially all platinum.

We claim: 3. A workable platinum alloy comprising about 1. A platinum alloy comprising a small but 0.5% tin and the balance substantially all effective amount up to about 5% of tin and the 5 platinum.

balance substantially all platinum. EDMUND MERRIMAN WISE.

"2. A workable platinum alloy comprising about RAYMOND FRANCIS VINES.