US2210504A - Lead alloy bearing metal - Google Patents

Description

Patented Aug. 6, 1940 UNITED STATES PATENT OFFICE 2,210,504 LEAD ALLOY BEARING METAL Robert I. Shoemaker, Chicago, Ill.

No Drawing.

2 Claims.

This invention relates to hardened lead alloys having characteristics making them suitable for bearings.

The primary hardening agent is calcium and 5 it is used in amounts sufiicient so that a relatively large number of calcium-lead crystals PbaCa are produced, which give the alloy itscapacity for withstanding wear and resisting impact necessary to make the alloy useable for certain types potassium are variously employed as hardening agents, since it has been found that those ingredients imparted deleterious corrosive efiect to the alloy, particularly when used in thin bearing linings where the alloy may be only 1/32 inch to 1/ 16 inch thick, as in bearings for automobiles, Diesel engines, and the like. It has also been found that potassium and lithium are rather unstable and dross ofi readily on remelts.

The instant invention contemplates, not merely the use of as high as 2.0% calcium, but the avoidance of the use of lithium, and potassium, without the loss of the desirable characteristics usually imparted to alloys thereby.

The alloy differs radically in its characteristics from the lead alloy intended particularly for cable coverings, pipes, and like articles described and claimed in patent to Robert J. Shoemaker, No. 1,813,324, patented July 7, 1931, in which such small quantities of calcium are used that either all of it goes into solid solution with the lead or the calcium-lead crystals formed are so small in number and size, and consequently are so widely distributed in the body of the alloy, that they add substantially nothing to the wear or impact resistance qualities of the alloy.

The present invention also contemplates the use of secondary hardeners such as tin and mercury, the employment of which latter, however, is optional; and, as mercury is poisonous and to some extent dangerous if used in large quantities Application August 15, 1938, Serial No. 224,994

for the purpose of enhancing the hardness of the alloy, the' present invention contemplates the use of other secondary hardeners in place of all or part of the mercury, to wit, silver, magnesium, barium, strontium, copper, manganese, in quan- 5 tities to be indicated.

A preferred formula is as follows, percentages being by weight of the alloy, taking into account, so far as possible, oxidation and other compounding losses: l0

'- Percent Calcium 0.6 Tin 1.0 Mercury 0.25 Aluminum 0.05 15 Lead.... Balance These preferred quantities may be varied as follows:

' Percent 20 Calcium 0.6 to 2.0 Tin- 0.5 to 1.0 Mercury 0.1 to 1.0 Aluminum 0.02 to 0.15 25 Lead Balance If the calcium is used in quantities above 2.0%, the alloy when melted will be too viscous. If the tin is used in quantities above 1.0%, the alloy becomes too brittle, the hardness is decreased, 30 and the melting point is reduced. If the mercury is used in quantities above 1.0%, it will volatilize.

. The aluminum is optional, but practically necessary if the alloy is to be remelted. It is an antidrossing agent preventing oxidation of the cal-- 35 cium. Since it is largely customary in the industry to remel-t bearings of this type, it is also necessary to keep the barium content not in excess of 0.1% as in excess of that amount will 40 render the alloy unstable.

The use of mercury in excess of 1.0% will add considerably to the hardness of the alloy. For example, the'hardness of the alloy made in accordance with the preferred formula given above, is about 20 on the Brinell scale with the metal at Fahrenheit. The hardness may be increased to 25 by using mercury up to 1.0%; but the employment of mercury in this quantity is likely to result in the production of poisonous fumes, in the compounding or remelting of the alloy. To avoid this, where a high degree of hardness is desired, it is possible to employ, in place of the mercury, (or in addition to mercury in quantitles from 0.1% to 0.25%) any of the following metals in the quantities indicated:

Per cent Silver 0.5 to 2.0 Barium 0.02 to 0.1 Strontium 0.02 to 0.5 Copper 0.05 to 0.5 Manganese 0.05 to 0.5 Magnesium 0.01 to 0.15

The method of compounding the alloy is as follows: The lead is melted and heated to a. temperature of approximately 1500 Fahrenheit under a covering of calcium chloride or other suitable flux. The aluminum is introduced, preferably as an alloy consisting of 50% aluminum and 50% tin byweight. Since the amount of aluminum is very small, the tin introduced in this way is practically negligible. The calcium is in- I troduced as metallic calcium or as an alloy conor the bath'can be allowed to solidify and then rernelted to about 700 Fahrenheit, whereupon, in either case the mercury and tin are added.

Another preferred formula in compounding this alloy is as follows:

Per cent Calcium 0.8 Tin 1.0 Mercury 0.25, Aluminum 0.05

Lead Balance and anyone of the following in the amounts specified:

hardness of 24 Brinell, a tensile strength of 12,000 pounds per square inch and an elongation of 9 to 12% of two inches.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that-various changes may be made in the formulae herein disclosed and described without departing from the spirit and. scope of the invention or sacrificing all of itsmaterial advantages, the formulae hereinbefore disclosed being merely a preferred embodiment thereof.

I claim:

1. A hardened lead alloy for bearings containing, in addition to a main body of lead, a primary hardener comprising 0.6 to 2.0% of calcium; secondary hardeners comprising 0.5 to 1.0% of tin, and less than 1.0% of mercury, and a further hardening agent selected from a group comprising 0.5 to 2.0% of silver and 0.05 to 0.5% of copper; and an anti-drossing agent comprising 0.02 to 0.15% of aluminum.

2. A hardened lead alloy for bearings containing, in addition to a main body of lead, the following substances in quantities by weight substantially as follows: 0.8% of calcium; secondary hardeners comprising 1.0% of tin, .25% of mercury, and another hardening agent selected from a group composed of 1,0% silver and 0.25% of copper; and an anti-drossing agent comprising 0.05% of aluminum.

ROBERT J. SHOEMAKER.