US1878686A - Alloy - Google Patents

Description

Patented .Sept. 20, 1932 sum-:1) STATES OWEN W. ELLIS, OF TORONTO, ONTARIO, CANADA ALLOY ,No Drawing.

My invention relates to anti-friction alloys and more particularly to a lead base alloy that is suitable for hearing or type metals.

An object of my invention is to provide a 5 lead base alloy containing alloying ingredicuts in such proportions that it will have high strength and anti-frictional properties.

Another object of myinvention is to provide as a base for bearings or type. metals an alloy of lead and a metal which forms a solid it suitable for use the manufacture of high grade bearings,

It has heretofore been the practice to utilize tin as a base metal for alloys employed in the manufacture of high grade bearings. Bearings made of such alloys have proven satisfactory in service, but the price of tin has been rapidly increasing during recent years because of its broader application in the industry and because of the failure to discover any deposits of considerable quantity. At

the present time, tin base alloys are, therefore, relatively expensive and attempts have been made to reduce the cost by the substitution of lead base alloys. Lead, however, is a comparatively soft metal and its low limit of proportionality and ultimate strength renders it unadaptable for the purpose desired.

Attempts have been made to harden lead by working it or by adding alloying ingreclients. Lead, however, cannot be hardened D by cold working because its temperature of Application filed August 30, 1929. Serial No. 389,618.

recrystallization is about 20 0., and while the grain structure of coarsely crystalline lead can be refined somewhat by plastic deformation at ,room temperature, the increase in hardness is not sufli'cient to render the metal desirable inthe manufacture of bearing alloys which are subjected tolseve're strains in service.

The alkali or alkaline earth metals such as sodium, magnesium, barium or calcium have been utilized for hardening lead, and lead base alloys containing such metals have been employed in the manufacture of bearings. Certain difliculties, however, are encountered in remelting these alloys because of drossing and oxidation. A hydrate bloom also forms upon such alloys when they -areexposed to moisture which, under certain conditions, is objectionable.

Binary alloys, composed of lead and antimony and ternary alloys composed of lead, antimony and tin, have been utilized for bearing metals, but the lead-antimony al loys do not have sufiicient strength to meet the increasing loads to which. such bearings are being subjected and the lead-antimonytin alloys, while possessing greater hardness and compressivestrength, are more brittle and less able towithstand shock.

I have made the discovery that if in )lace of utilizing lead alone as the base for earing alloys, an ingredient is added to the lead which will form a solid solution therewith, a basic metal will be formed that has a higher melting point and greater strength and resistance to corrosion than lead. The only known metals which 'form a solid solution with lead in suflicient proportions to efl'ect a. material hardening action are thallium,

gallium and indium. For economical rea-' sons, I prefer to utilize thallium. These metals are members of the aluminum family and constitute the group of elements occurring basis the solid solutions of thallium, gallium, indium or two or more of these metals,

in lead, the usual anti-frictional ingredients Y are added as when lead alone is employed. The preferable alloying ingredients having theproperty of reducing friction are antimony, tin antimonide or the alkali or alkaline earth metals, such as sodium,- calcium, barium or magnesium.

I prefer to utilize antimony or a mixture of antimony and tin, although it will be understood that one or more ofthe alkali or alkaline earthmetals may be utilized when the hydrate bloom is not objectionable. It is well known that these ingredients have the property of hardening lead as well as increasing its anti-frictional properties. My researches show that these ingredients will produce a like effect when added to a basic metal composed of a solid solution of thallium, gallium or indium in lead, and a final alloy will thus be produced that is greatly superior in hardness and strength to lead base alloys; in fact, the properties of my improved alloy are at least equal, if not superior, to hearing alloys-having a tin base.

The proportions in which the elements may be utilized in making up the alloy may be widely varied. In the manufacture of leadthallium-antimony alloys, the antimony is maintained in the proportion of about 5% to 20% of the alloy and the proportion of thallium to lead is maintained in the ratio of about 1 to 9, the amount of thallium in the alloy, however, being greater than 5%.

The following table shows the stressrequired to compress a sample of an alloy containing lead, thallium and antimony, in which the proportion of thallium to lead was in the ratio of 1 to 9 and the amount of antimony varied from 5 to 20%.

i Stress in Thal- Anti- Lead pounds per hum mony square inch Per cent Per cent Per cent The stress required to compress similar samples containing 90% lead and 10% antimonyand 85% lead and 15% antimony was 12,880 and 12,820 lbs. per square inch, respectively, which shows that the substitution of thallium for part of the lead increases the strength of the alloy about 20%. The strength of alloys having the above composition compares favorably. with the tin-base alloys now utilized in bearing metals.

A series of alloys was next prepared in which 5% of tin was added, the total amount of antimony and tin being not more than 25%. The thallium and lead were maintained in the ratio of 1 to 9 and the stress required to compress a sample to .75 of its original length was determined. It wasfound that the stress varied somewhat, depending upon the size of the sample.

The following results were obtained:

Antl- Thal- Stress in pounds mony Tin lium Lead per square inch Per cent Per cent Per cent Per cent The proportional limit and the maximum unit stress to which the alloy may be subjected without permanent deformation is definitely raised by the addition of thallium.

While the limit of proportionality of lead is as low as 200 lbs, per square inch, the proportional limit of my improved alloy may be as hi h as 5650 lbs. per square inch.

y improved alloy is similar in structure to the tin-base alloys now employed in high grade bearings. As compared with a tinbase alloy containing up to 8% antimony and 8% copper, cast under the same conditions, tests show that the lead-thallium base alloys iire superior to a majority of the tin-base aloys.

While I have described my, invention in considerable detail and have given numerous examples, it will be understood that I do not desire to limit myinvention to the exact proportions given. In order to obtain the best.

limit may be varied, no mechanical advantage is to be gained in maintaining the proportions of thallium tolead at a greater ratio than 3 to 7 and because thalliumis consider ably more expensive than lead, I prefer to maintain the relations of these elements in the ratio of approximately 1 to 9.

When gallium and indium are utilized. they may be maintained in a somewhat higher proportion with respect to the lead, say up to about equal proportions. The amount of antimony and tin in the alloy should not be in excess of 15% of each of these elements. When the alkali'or alkaline earth metals are added to the solid solutions of thallium, gallium or indium in lead, the amount added may range up to 5%. I preferably utilize from to 1%.

In recapitulation, the preferred ranges of this bearing metal composition comprise about 5 to 20 percent antimony, or from 5 to 15 percent each of antimony and tin, with the balance essentially a matrix of lead containing dissolved gallium, indium, or thal lium. This dissolved metal strengthens the matrix. It may also contain about 0.25 to 5 percent alkali or alkali-earth mixture,

which hardens the solid solution of leadthallium, etc. The matrix thus constitutes about 65 to 95 percent with lead ranging from about 45 to 90 percent and thallium etc., from about 5 to percent of the bearing metal. In this the antimony acts as antifriction metal, which because of the physical chemical nature of this allo system is suspended throughout this lea solution. The antifriction metal'of antimony when united with tin is distributed as relatively hard cubes in a particularly strong matrix. Thus, this invention presents a bearing metal that contains no tin or but a low proportion-of tin and yet compares favorably in its engineering utility, with types of bearing metal that are high in tin.

"Other modifications of my invention will be apparent to those skilled in the art. I desire, therefore, that only such limitations shall be imposed upon my invention as are required by the prior art and the appended claims. I

I claim as my invention:

1. A hearing metal containing about 65 to 85 percent lead and 7 to 10 percent thal-, lium as matrix alloy, with the balance suspended as antifriction metal composed essentially of about 5 to 20 per cent antimony.

2. Abearing metal containing about 70 to 80 percent lead and about 7 to 10 ercent thallium as matrix alloy, with the alance suspended as antifriction metal composed essentially of about 5 to 10'percent tin and 5 to 10 percent antimony.

. 3. A hearing metal having as matrix alloy lead solution in which lead constitutes about 70 percent and thallium about 8 percent of the bearing metal, with about 15 per cent antimony and 5 percent tin as antifriction metal.

4. A hearing metal containing about 70 percent lead, 8 percent thallium, 15 percent antimony, 5 percent tin, and 0.25 to 1 percent alkali or alkali-earth metal.

Intestimony whereof, I have hereunto subscribed my name this 22nd day of August,

1929'. OWEN W. ELLIS.