US2215445A - Aluminum alloy as bearing metal - Google Patents

Description

Patented Sept. 17, 1940 UNITED STATES PATENT OFFICE 2,215,445 ALUMINUM ALLOY AS BEARING METAL g Eugen Vader-s, Frankfort-on-the-Main, Germany No Application February 10, 1940, Se-

rial No. 318,372.

In Germany December, 16,

4 Claims. (01. 75-148) In the white metal bearings heretofore commonly used the base metal consists principally of tin or of lead. The tin generally contains additions of antimony, bismuth, copper, etc., where "as the lead is alloyed principally with antimony and bismuth. The bearing metals having a tin base have up to now been considered the best of their kind. But in consequence of their high tin content which amounts up to 90%, they are very expensive so that for the sake of economy the expensive tin has been replaced by the cheaper lead. The lead content is very often used in the same proportion as the tin in the tin bearing ing metal alloy. provided that other metals exist,

which when added to this base metal alloy, form hard compo ndswithit. Aluminum is known to form numerous compounds with other metals and it has been proposed to use aluminum alloys for bearing purposes. This has, on several occasions, been tried but with very little success considering the fact that most aluminum bearing metals of the type referred to contain hard compounds which wear the axle too much. Bearing metals of this kind are, e. g., the aluminum-silibon-alloys with high silicon content of aluminum-magnesium-silicon-alloys.

According to the present invention much more useful aluminum alloys result from the addition of metals which form with the aluminum none or at leastonly few hard compounds, thus resulting. in no damage being done to the axle even after an extended time of working. Such additions are antimony andlead which may be present in quantities up to 10% each. The antimony forms with aluminum the compound AlSb which is present in the base. alloys as bearing component. Lead does not combine with aluminum. According to the opinion ofseveral exp'erts it is not soluble at all in the aluminum. If aluminum be melted together with lead, at the time of solidification a separation of the aluo minum andlead takes place, i. e., the lead is as insbluble in the aluminum as oil in water. By

adding antimony to the aluminum this sharp separation of lead from. the aluminum is obviated, so that with the presence of a sufllcient s5 quantity of antimony larger quantities of lead are distributed in the aluminum, resulting in an alloy which shows a structure more especially suitable for hearing purposes. Apart from aluminum an AlSb compound is contained in it, while lead is either alloyed with this Al-Sb compound, 5 or else is segregated in form of small drops which form an improvement .of the sliding surface, in-

asmuchas in the case of interruption of the .oil-

ing or sudden stoppage of the running or the bearing no damage will be caused to the axle. 10

All tests made in this direction proved in every instance that the sliding surface of the axle was covered with a thin layer'of the aluminum alloy; that could easily be removed. The aluminum-antimony-lead-alloys have a crystalline structure as also the other qualities of the knownwhite bearing metal. Thus they are easily formable' even in a cold state. t

The sliding properties have been ascertained with an especially suitable alloy consisting of m 2.5% Pb, 2.5% Sb and the balance aluminum by a bearing testing installation. On that occasion specific surface pressures of about 200 kg./cm.

' could be reached at a speed of 10 m./sec, whereby the bearing temperature rose up' to'100f C. The test axle that consisted of non-hardened steel was.perfectly smooth and free from indents at the end of the test. Apart from the bearing testing machine, tests were made in combustion motors in which the connecting rod bearings con- 110 sisted of the new aluminum alloys. These combustion motors have been driven by an electrical motor, so that the bearings were fullycharged. Also in that case the bearings of the new alloy proved successful, for during a working period Per cent Pb 1.

Sb- 1 I 2.5 1A1 J I Balance or Per cent Pb- 1 2.5

A1 Balance In cases in which the price of the bearing metal is of lesser importance, the tin content may also be higher. An alloy having a higher tin content is about the following:

Per cent Pb 2.5 Sb 2.3 Sn 5 Al Balance Since tin alloys well either with. antimony or with lead, it is particularly valuable as addition to the ternary aluminum-lead-antimony-alloy, but also the other metals added to, this three-partalloy result in very useful bearing metals.

While the additional metals mentioned above influence chiefly the sliding properties, the further possible additions of at least one of the metals of the group consisting of copper, nickel, co-

' balt,iron, manganese and zinc in quantities of 0.1-10% and silicon in quantities of 0.1-3% especially effect a strengthening of the bearing metal which consequently -is more suitable to resist higher pressures. Especially an addiiton of manganese has proved very effective, inasmuch as it not only, increases the hardness of the alloy, but even improves essentially the sliding properties. An alloy that proved particularly useful for the automobile motor is composed as follows: 2.5% Pb, 2.5% Sb, 3% Mn, remainder Al.

The basic alloy of aluminum with 1 to 10% of lead, 1 to 10% of antimony and 0.1 to 3% of sili-' con may contain an addition of a metal of the group consisting of zinc and cadmiumin quantitles from 0.1 to 10%. 'The zinc preferably is added in an amoutn of 0.1 to 10% and the cadmium in an amount of 0.1.to 5%.

. Further alloys that correspond about to the properties of the above mentioned alloys are as follows:

Percent The addition of metals of a higher melting point further serve the purpose of making the bearing metals capable of resisting higher temperatures. While it is correct that with most of the additional metals named above. the melting point of aluminum is lowered to the eutectic point, the,

substantially all aluminum.

could be reached without a clinging or sticking to the axle having occurred. Naturally with such high temperatures the higher heat expansion of the aluminum alloys has to be taken into account by provision of a greater bearing-play..

If the new bearing metals are used under favorable condiitons, i. e., presence of ample quantitles of lubricants, they show but a small wear, even after a comparatively short running-in period.

Summing up, it may be said that with the new bearing metals having an aluminum base as compared with the hitherto known bearing metals,

the following advantages exist:

1. Easier running-in,

2. High resistance to wear, a 3. Possibility of using unhardenedaxles, 4. High resistance to temperature.

adjusted in sucha way that the segregations remain at a minimum. The alloys may further be pressed, forged or rolled. In this respect itis surprising that the annealing in the drawing of rods and tubes may be accomplishedat about 500 C. in spite of the leadand antimony-content without a segregation of the alloys occurring thereby.

For the production of an alloy'as uniform as (possible, firstr of all antimony is melted together with aluminum whereupon lead is added as such or as a preliminary alloy.

, The rolling possibility moreover makes it possible to roll up the alloys to a firmer sheet base that may consist of iron or copper alloys or also of hardenable aluminum alloys and to produce from the compound metal sheets thus obtained especially firm bearing shells.

I claim: a

1. A bearing metal alloy containing about of lead, 1-10% of antimony, 0.1-3% of silicon, and 0.1-10% of a member of the group consisting ofzinc and cadmium, the balance being substantially all aluminum.

2. A bearing metal alloy containing about silicon, and a member of the group consisting of zinc and cadmium, the zinc in an amount of 0.1-10% and t e cadmium in an amount of 0.1-5%, the bal ce being substantially all aluminum.

.3; A bearing metal alloy containing about 140% of lead, 110% of antimony, 0.1-3% of silicon, and 0.1-10% of zinc, the balance being substantiallyall aluminum.

4. A hearing metal alloy containing about I 1-10%- of lead,,l,10% of antimony, 0.1-3% of silicon, and 0.1-5% of cadmium, th balance being nouns vsnnas.