US2288656A - Bearing - Google Patents

Description

' July 7, 1942. Q F, SMART 2,288,656

BEARING Filed Dec. 51, 1957 5 I STEEL Cd Ni 7 v IND/UM lmnntor Claw/Ice 55mm? attorneys Patented July 7 1942 UNITED STATES PATENT OFFICE I BEARING Clarence F. Smart Pontiac, Mich., assignor to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application December 3-1, 1937 Serial No. 182,642

' 20 Claims. (01. sot-237 This invention relates to bearings and more particularly tothose in which cadmium and lead are present. Various alloys of cadmium or lead without tin have been. proposed for use in the surface portions of relatively moving parts. Such alloys may include, for example, copper-lead (plastic bronze), cadmium-copper, cadmium percentages of additional metals, such as nickel, copper or antimony, which form relatively hard inclusions or particles within the'ground mass of the alloy. 1 f

The proportion of the ingredients of the cadmium-silver alloy is-preferably within the limits of .5-5% silver, .25 l% of ahardening metal or metals and the balance cadmium. Morespecifically I prefer the composition silver l.75-2.50%. copper, nickel or antimony, separately or in mixtures, 25 .5%, cadmium 97-98%,

One cadmium-copper alloy employed for bearings includes 95-97% cadmium and'from 3-5% of copper. Magnesium up to .5% may beadded to this alloy. Another known cadmium-coppermagnesium bearing alloy contains copper .2-1.5% magnesium .1-.75%, balance cadmium.

contains .257% nickel and the balance substantially cadmium. ;Magnesium, zinc, copper, antimany and aluminum'up to 3% may be added to The alloy known as plastic bronze is an alloy other ratios of leadand copper, also may be used as bearing materials.

Cadmium and lead and-the above described alloys thereof, as well as other alloys containing a substantial amount of cadmium or lead, are subject to attack by various acids and other corrosive media. The commercial uses of the copper -lead and cadmium base alloys for bearlugs, for example, have been retarded due to the corrosive action of acids present in, or formed during the use of certain lubricants. Some lubricants or ingredients thereof, suchas lard oil, I

contain organic acids that tend to corrode cadmium and lead. Other lubricants, for example, some mineral oil lubricants, when subjected to high temperatures, as 275 F. orhigher, in the presence of air tend to oxidize to produce acids which have a similar effect, Long life of bearings containing a substantial amount of'cadmium or lead may, therefore, be seriously affected by the presence of such acids, particularly under hard service conditions such as those that occur in automobile engines.

Lhave found that corrosionby such organic acids may be substantially prevented by the presencein the alloy or upon its surface of small quantities of indium. I contemplate the use of the indium either as a constituent in a substantially homogeneous alloy with the other constitu- The cadmium-nickel bearing alloy. ordinarily I cuts of the bearing or by applying indium to the surface, for example by electrolytic processes. When applied electrolytically it may be desirable to ,subject the bearing to heat treatment after deposition of the indium thereonto difiuse the indium into the alloy to some extent. Such heat treatment may be carried out by merely main- .taining the bearing, which has been preliminarily coated with metallic indium,, at a temperature below the melting point of thebearing alloy but sufliciently high, e, g... 340-500 F. for sufiicient time to cause the indium to alloy with the other constituents to the desired extent. In thecase of the cadmium base alloys. the indium is apparcontaining a large percentage oflead with th i balance approximately all copper, for example, from 30% lead and 70% copper tolead and 50% copper. One analysis-of a. copper-lead alloy foundespecially suitable for bearings in accordance 'with the invention contains approximately ently alloyed after a heat treatment at 340 F. for about third minutes. Diffusion through .10."-.l5" of a cadmium or a cadmium base alloy is accomplished in about two hours at 340 F.

The amount of indiumlrequired to effect a commercially satisfactory prevention of attack by the acids in question is relatively small. When i the indium is'introduced into the bearing by formation of a homogeneous alloy including cadmium from one-tenth of one percent to one percent is "found to be suflicient, the amount varying,

45% lead v and copper. Alloys containing 55 of course, with the degree of inhibition desired or indium is preferred. For example, indium within the range .4-.8% substantially prevents corrosion even when the bearing alloy is tested in prepared oils having a much greater corrosive effect than averagelubricating oils after high temperature service.- I

If however, the indium is applied to the surface portion only of the cadmium or alloy thereof, the amount required obviously will depend upon the extent of absorption of the indium or the depth of penetration in the cadmium or cadmium alloy. In cases in which it is desired to substantially uniformly diffuse the indium throughout the cadmium or alloy thereof the amount necessarywill be comparable with that in which the bearing is originally made from a homogeneous alloy.

When the indium is employed as a constituent of a homogeneous alloy including a cadmium its presencehas effects similar in some respects to those produced by silver. It is therefore possible to reduce the silver content of cadmiumsilver alloys to some extent while still retaining the desirable hardness and toughness imparted otherwise by a larger silver content. The following may be given as an example of acomposition which has been found to have satisfactory properties as a bearing alloy and suitable re-- sistance to corrosion of acids resulting from oxidation of mineral oils:

\ Per cent Silver 1-1.25 Copper 0.25 Indium 0.2-0.4

, The remainder substantially cadmium.

. The alloy given in this example compares favorably in properties with a similar alloy omittingv indium and having 2% or more or silver with the advantage for the indium containing alloy of greatly increased resistance to acid. 1

Bearing alloys containing a substantial amount of lead ordinarily reqiiire a somewhat greater amount of indium than the cadmium .base alloys in order to be protected from the eflect of corrosive lubricating oils. For example, with .the copper-lead alloys the amount of indium necessary may be within the range .5-8.0% of the weight of the copper and lead combined. Even greater amounts may be'used without detrimental effect on the other ,propertiesrof the alloy, but the cost factor of the indium is such that it is desirable to use the minimum amount necessary to effect the desired result as regards resistance to corrosion. I

, With the copper-lead alloys it is desirable that the indium be applied first to the surface of the copper-lead, for example, by electrodeposition, and then diffused therein, as by being heated to 340-600 F. for a time interval sufllcient to afiect the desired diffusion. As an example, a copper-lead alloy having an electrodeposited coating of indium may be heated to' about 340 F. for eighteen hours. The heat treatment is such that of approximately .016"-.020" thickness having an electrodeposited coating of indium of from .0001"-.001 in thickness and heat treated produces an excellent bearing surface that is highly resistant to the effect of the acids present in or produced during use of certain lubricating oils. In some, instances thicknesses of indium slightly less may be employed. Considerably greater thicknesses may be used also, but the cost of the indium is such that it is desirable to use the least possible amount necessary to obtain the desired result. a

' Alloys containing material amounts of tin, as the usual Babbitt metals, are not liable to attack by the acids occurring in mineral lubricating oils as the tin serves to protect the lead usually present in such alloys. Tin, however, is not used in the so-called plastic bronze copperlead alloys due to the low melting point of the tin-"lead eutectic formed, and I have found that tin when added to cadmium in sufficient quantity to excercise the desired protective effect renders the alloy too brittle for use in bearings.

As an. illustration of the application of my invention to bearings, I have shown in the-ac-v companyingdrawinga sectional view of a connecting rod bearing comprising a connecting rod 5, a sleeve or backing 5 of relatively hard and strong metal such as steel, or other ferrous metal or alloy, or bronze and facing I of an alloy of cadmium and silver, with or without a small amount of one or more additional metals, bonded to the surface of the sleeve .by an alloy layer 8 containing cadmium and nickel or cadmium and zinc, the facing I having at least at the surface a content or coating of indium 9. The cadmiumnickel bonding alloy may be composed of nickel from 375-270 with.the balance substantially all cadmium. Preferably, the nickel is used in a percentage of around 1%. The cadmium-zinc bonding alloy may contain zinc from 520% and cadmium from 80-95%.

Some difliculty is experienced in satisfactorily bonding a homogeneous cadmium base alloy containing indium to a steel backing. For this reason it is highly desirable to bond the cadmium or cadmium alloy to the steel backing and thereafter apply the indium to the bearing surface, as by electrodeposition. Thereupon the indium may bedifiused into the bearing by heat treatment at a temperature of 340 F. or high-er. In this way the alloy may be readily bonded to the steel backing.

The cadmium-nickel bonding alloy is greatly preferred/ since with this alloy the bond is not weakened during the subsequent step of diffusing the indium into the bearing. For example, I have found that a'bearing alloy composed of silver 2.25%, 0.25% copper and the balance cadmium may be readily bonded to a steel backing sixty hours.

In this case the facing I will be of copper-lead having -a coating of indium thereon as disclosed. The copper-lead facing may be integrally bonded to the steel backing by being heated to a brazing temperature in a hydrogen atmosphere furnace. Hence, the bonding layer 8 employed with the cadmium base alloys may be dispensed with.

It will be understood that the structure illustrated is merely an example of one use of the invention and is not intended as any limitation on the scope of theinvention.

While I have set forth herein specific examples of alloys protected against acid attack by the, presence of indium, it is not intended to restrict the invention to any specific alloy nor any particular amount ofindium. I believe that I am the first to have discovered the protecting or inhibiting effect of indium in preventing corrosion due to the organic acids in lubricating oils and particularly those resulting from oxidation of mineral oils at high temperatures, and it is therefore 'desired to cover such discovery .in broad terms.

This application is a continuation in part of my prior applications Serial Number 43,468, filed October 4, 1935, andmy application Serial Numbe! 167,707, filed October '7, 1937. I

I claim:

1. A hearing comprising a backing of relatively hard and strong metal and a facing thereon composed of a cadmium base alloy containing a small amount of indium sufficient to substantially prevent corrosion of the facing caused by acid products in lubricants, said small amount of indium being not less than .1% of the facing composition.

2. A bearing asin claim 1, in which a layer of cadmium-nickel alloy is between the backing and the facing.

3. A bearing comprising a backing of relatively hard and strong metal, a facing composed of a cadmium base alloy having a small amount of indium therein sufficient to substantially prevent corrosion of the facing caused by acid products in lubricants, and a layer composed of a cadmirum-nickel alloy for bonding said facing to said backing, the content-of indium in the facingvbethensurface thereof in amount sufficient to protect the bearing from acid products in lubricants.

6. A bearing as in claim 5, inwhich the facing-contains 50-70% copper and 30-50% lead.

7. A bearing having a facing contalningcopper and lead and a heat treated coating of indium on the surface thereof. v

8. A bearing having a facing containing cop-j per' and lead and having a coating of indium on the surface thereof of from .0001-.001" in thickness.

-' coating of indium.

12. A bearing containing a substantialamount of lead and having an electrodeposited coating of indium.

13. A bearing formed of a bearing alloy subject to attack by acid products in lubricants and having a coating of indium.

14. A hearing formed of a bearing alloy subject to attack by acid proucts in lubricants and having an electrodepositedcoating of indium.

15. A bearing having at least its surface portion formed'of a cadmium base or a copperlead bearing alloy subject to attack by acid products in lubricants, to which has been added a small amount of indium suflicient to substantialin lubricants,

16. A bearing having cadmium base bearing alloy subject to attack by acid products in lubricants and having a coating of indium. i

, 17. A bearing having tion composed of .a cadmium base bearing. alloy subject to attack by acid products in lubricants,

1y prevent corrosion caused by said acid products a in which is incorporated a small amount of indium sufficient to substantially prevent corrosion caused by acid products in lubricants.

18. A bearing having at least its surface portion formed of an alloy consisting essentially of cadmium, indium and a hardener, the hardener being present in effective amount up to about 10%, the indiumyin small amount sufliclentto' substantially prevent corrosion caused by acid products in lubricants and being at least about .1 and the balance substantially cadmium.

19. A'bearing comprising a backing of relative- 1y hard ,and strong metal, a facing containing cadmium and a small amount of indium, the quantity of indium at the surface being greater than at points spaced therefrom. f

- 20. A hearing having a facing containing cadmium and having a heat treated coating of indium onthe surface thereof.

CLARENCE F. sma'r.

a portion formed of aat least its surface pox.-

CERTIFICATE OF CORRECTION. Patent No. 2,2 8 65'6 July 7, 19L 2.

CLARENCE F. SMART.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, first column, line 58-59, for "antiman read --antimony; and second column,

, line 15, for "third" read thirty; page 5, second column, line 25, claim 1h, for "proucts" read -products--; lines 28 and 29, claim 15, for "cadmium base or a copper-lead" read plastic bronze-; and line 55, same claim, after "lubricants" and before the period insert the comma and words said plastic bronze containing about 5 0 to 70% copper and about 50 to 50% lead";

- and that the said Letters Patent should beread withthis correction therein 7 that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 18th day of August, A. ,D. 19LL2.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

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