US1895261A - Metal alloy - Google Patents

Description

per base a Patented Jan. 24.1932.

UNITED S'l'ATES PATENT OFFICE HARRY K. HEBSCHMAN, OF WASHINGTON, DISTRICT 01' COLUMBIA, AND JOHN L. BASIL,

OI ANNAPOLIS, .mynnm IETAL ALLOY Ho Drawing.

gunman man THE ACT or mac 3, 1883, as AMENDED urn. so, 1928; 370 o. e. 757) The invention described herein, if patented, may be manufactured and used by or for the Government for governmental purposes without payment of any royalty thereon.

This invention relates to improvements in metal allo s and more particularly to a coplloy of hi h lead content especially adapted for use in earings, it being under,- stood that numerous other uses will be found for such an alloy.

An object of this invention is to provide a:

bearing metalrof especially low frictional properties and having the following additional properties combined: high melting point, high strength, toughness, hlgh wear resistance and roper hardness and conformability, and f properties at elevated temperatures.

A further object in view is to provide all of the above without the use of tin, which is not only an expensive but a strategic metal obtai'nable only in small quantities in this .counmetals with particular reference to those containing lead, have lead 1028 percent; tin 2-10 percent, and the remainder copper and minor impurities. The aboVeis commonly known to the trade as lead bronze bearing metal and is the type of bearing metal improved by the discovery herein disclosed.

A satisfactory bearing metal should for obvious reasons be so composed as to tend to prevent seizure between the bearing and the shaft, when lubrication may for any reason fail. To provide such a bearing metal,

alloys containing large percentages of lead or,

other metals of the same characteristics are used.

Bearing metals subjected to heavy loads and high speeds cannot be made entirely of lead due to the fact that it does not have sufficient load-carrying ability. In order to give lead suflicient support for such service other metals are combined with it. In such combinations copper is usually used and forms a matrix in which the lead is distribut ed. In order to'properly distribute the lead urther, especially improved of these'elements in copper, thus distributing the lead in globular and discontinuous form throughout the mass.

Copper and lead are known to be miscible and will alloy in nearly all proportions when heated to sufiiciently high temperatures.

They, however, separate out when cooled I since these metals remain alloyed to a very negligible degree when cooled to room temperatures. In the prior art certain elements such as tin and sulphur have been added to prevent such separation. The degree of success with which this has been accomplished by the addition of these elements has been limited and the bearing metals so produced have failed to meet all the requirements which are known to be essential to an efiicient and successful bearing for operation at high speeds and high pressures with the result that they are unsuitable or deficient in one or all of the properties above refi "red to.

Further, in order that a bronze bearing metal meet all of the above requirements for the property of conformability, it is necessary that the matrix of the bearing metal be sufliciently soft and the lead content sufiiciently high, to allow for the so-called wiping action and flow of the bearing to prevent seizure, which should be accomphshed without sacrificing the necessary strength, tou h-- ness, and wear resistance required at hlgh operating temperatures resulting from in-. creasingly high speeds and high powers beand small amounts of other elements. 'The silicon-zirconium alloy may be prepared with other variations of silicon and zirconium of the elements mentioned, it having been envelope formation of lead and provide found that alloys containing additions of various amounts of sulphur, silicon, and zirconium permit the use of relatively high percentages of lead showing same to be present -in'the matrix in well distributed, fine and' discontinuous particles.

While it is known that the addition of sulphur alonewill permit the use of high lead content with good distribution, the lead in such instances is present in the form of continuous envelopes around the grains of copper. Under such conditions the metal does not have the strength .of one in which the lead particles are discontinuous and well distributed in the matrix. The addition of silicon and zirconium together with sulphur, has very definitely been found to breaku the el divided globular particles of lead filling thz interstices in the unbroken network of the copper base matrix. The silicon and zirconium either separately or together, further give improved mechanical properties to the bearing metal at elevated temperatures. a

The improved alloy here described not only permits a higher percentage of lead content than possible in the former art but also shows no appreciable effect in its composition or structure when remelted and cast a plurality of times. 7 I

The method of preparing this improved bearing metal is as follows: Melt down the copper in any suitable furnace, add the lead thereto when the copper is molten, then add the silicon-zirconium alloy which has preferably first been made up as a hardener containing copper 90 percent,.silicon-zirc onium alloy 10 percent, after all'of the metals while molten, have been thoroughly mixed, sulphur is added in the form of elemental sulphur or as lead or copper sulphide.

It will be understood that variations may be practicedin the preparation. of the improved bearing metal as follows: Melt down the copper, add the lead thereto when the copper is molten, then add silicon which has pre erably been first prepared as a Fhardener containing copper 90 percent, silicon 10 percent, then addzirconium which has preferably first been made up as a hardener containing copper 90 percent, zirconium 10 percent, after all the metals while molten have been thoroughly mixed, sulphur is added.

The above sequence may be varied, for instance, the silicon and zirconium prepared as hardeners may beadded to the molten copper, prior to adding-the lead. The molten .mass after alladditions have been m de,

should be heated to a 'sufliciently high tem perature to insure thorough alloying of all the elements resent. 7

A refer method of preparing this alloy with special reference to temperatures, is to heat the copper to approximately 1100- 1200 degrees 0., add the lead to the molten copper, then add the silicon and zirconium to the molten metal which is maintained at about 1150-1200 degrees C. to'insure complete allo ing of the constituents, cool the melt to a ut 1125 degrees C. and add sul- 2111, following'which the molten mass may Having thus fully described our invention what we claim and desire to secure by Letters Patent is:

1. An alloy composed of, about 60 percent I by weight of copper, about 38 percent by weight of lead, about 1.5 percent by weight of silicon-zirconium alloy and about 0.4 percent by weight of sulphur.

2. A hearing alloy comprising, about 60 ercent by weight of copper, about 38 percent y weight of lead, about 1.5 percent by weight of silicon-zirconium. alloy adapted to distribute the lead and harden and strengthen the bearing alloy and about 0.4 percent by weight of sulphur adapted to distribute the lead.

3. An alloy composed of, copper about 60 percent by weight, lead about 38 percent by weight, silicon zirconium alloy 0.5 to 2.5 percent and 0.2 to 0.6 percent sulphur 1n the form of copper sulp ide.

4.. An alloy composed of, copper about 60 percent by weight, lead about 38 percent by Weight, silicon zirconium alloy 0.5 to 2.5

percent and 0.2 to 0.6 percent of sulphur in