US3743502A - Process of preparing fine-grained blends of lead with copper or aluminum - Google Patents

Abstract

FINE-GRAINED ALLOYS OF METALS SUCH AS LEAD AND COPPER OR LEAD AND ALUMINUM ARE MADE BY MELTING THE INDIVIDUAL METALS SEPARATELY UNDER REDUCTION CONDITIONS AND MIXING THEM INTIMATELY UNDER REDUCTION CONDITIONS AND THEN CASTING THEM OR EXTRUDING THEM IMMEDIATELY THEREAFTER.

Description

U.S. Cl. 75-135 United States Patent 3,743,502 Patented July 3, 1973 PROCESS OF PREPARING FIN E-GRAINED BLENDS OF LEAD WITH COPPER OR ALUMINUM Ernest Hey, Eureka, Califi, assignor to Helen B. Sherry, Seattle, Wash. No Drawing. Filed Apr. 29, 1971, Ser. N 138,785 Int. Cl. C22c 1/02, 1/06 14 Claims ABSTRACT OFv THE DISCLOSURE Fine-grained alloys of metals such as lead and copper or lead and aluminum are made by melting the individual metals separately under reduction conditions and IlllXlIlg them intimately under reduction conditions and then casting them or extruding them immediately thereafter.

This invention relates to improvements in the alloying and blending of metals. It has particular applicability to blends of lead and copper and to blends of lead and aluminum, but it applies also to many other metals.

Lead and copper do not blend in the sense of fusing together, nor do lead and aluminum. The same is true of many other metals. They only melt and alloy or bond. This results in many flaws and in rather coarse graining.

In contrast, the present invention obtains uniform homogeneous mixtures or blends of such metals in practically any proportion. This blending is accomplished by creating an affinity between different metals. It is a chemical blend, not a mere mechanicalbond.

For example, lead cannot ordinarily be blended with copper or aluminum, while still having a uniform dispersion of the lead throughout the alloy, because after the lead reaches a certain rather low percentage, it tends to concentrate itself in clusters called dendrites. In contrast the present invention is able to provide blends free from a substantial number of such clusters, or even entirely free from them. Thus, for example, in a blend of about 60% copper and 40% lead made according to this invention, microphotograph taken of a cross-section of the sample was magnified 175 times and showed uniform homogeneous diffusion or dispersion of the lead throughout the copper. Such uniformity of blend has not been obtainable prior to the present invention.

The same thing has been done with lead and aluminum, which have such different specific gravities that they are quite difiicult to mix together well. The present invention provides blends that will not separate upon casting or extruding. The invention also applies to blends of magnesium and lead.

The alloy blends of this invention have various uses depending upon the particular compositions. For example, the copper-lead product of this invention can be used in journal-bearings and provides the type of lubrication that can overcome the hot-box problem on railroad journals. The metal blend is nonporous and is substantially self-lubricating having even a greasy feel, and can therefore give superior results as a journal bearing with graphite or oil.

The invention may also be used to produce superior bronzes which are not porous and do not leak and to produce zinc-free brasses.

Alloys of aluminum can be produced that eliminate the necessity for anodizing or enameling the aluminum.

Other objects and advantages of the invention will appear from the following description of some preferred embodiments.

The metals to be blended according to this invention are first individually Weighed out in amounts determined by the proportions desired in the finished blend. Then each metal is placed in a separate clean crucible and Bee melted separately, bringing each to its melting point while under a cover of granulated charcoal or other similar carbon at temperatures hot enough to dissolve most insolubles; if any insolubles do turn up they should be skimmed 01f.

Since metals have different specific gravities, they tend to separate when they are melted together, and one tends to float on top of the other, except to a relatively minor extent. An important purpose of the present process is to enable the metals to form a true blend, not just to bond as alloys, and that is why the metals are handled separately at this stage.

An important feature of the invention is to agitate each of these melts, for example, either by stirring each deeply with treated wooden sticks or by swirling each crucible. For stirring, the wood may be hardwood, either seasoned or green, and it should be specially treated. The preferred treatment is to soak the hardwood stick in a solution of lye and then to dry it. For even better results, it should be re-soaked and dried again. Of course, the stick should be completely dry and hot before it is used to stir the liquid metal, so that it will not cause the liquid metal to explode. After this stirring, the separate solutions should be again skimmed; and it is advisable at this stage to sprinkle powdered lye or other powerful alkaline on the charcoal cover, before mixing the two metals together.

The mixing may then be achieved by pouring one crucible into another back and forth several times, to obtain a thorough mix and while agitating by swirling the crucible or by stirring the mix thoroughly with a similarly treated stick. The heavier metal should preferably be poured into the lighter metal lead, for example, should be poured into the copper (or into the aluminum). There is intimate contact between the metal and escaping gases, with the hydrogen obtained from the sodium hydroxide or other alkali, as well as contact with the carbon or carbon compounds, including resins in the wood, for example. A silicate of a resin may be used instead of the wood, if desired. The important thing is to provide chemical reduction during the time of the mixing as well as shortly prior to it. The wood chars and some of the carbon combines with any oxygen present to produce carbon dioxide; hydrogen, if present, also helps to reduce the oxygen present. A charcoal or carbon layer must be kept on the hot metal to exclude oxygen from it. Pouring the molten content over and through charcoal and lye enables one to get inoculation, a complete homozenizing, or The texture of the metals, and similar treatments operating on the same principle can be used instead.

Immediately after mixing, the metal mixture should be poured and set. It may be poured into molds to achieve a desired shape. In order to make sure that the process is working satisfactorily, one or more samples may be broken apart while the alloy is still hot and plastic and still soft enough to raise from the mold and to break when twisted, and the metal structure may thus be inspected. If the process has been correctly performed, the structure will look like fine wires throughout the mixture, running the full length of the ingot. The alloys of this invention have a different crystal formation from other alloys and looks like fine wires of copper color, the ingot itself also having a copper color. To test an ingot or bar after it is cool, some cuts may be made and the cuts examined.

The metal resulting from this process is superior to bronze and brass and is not affected in the same Way by electrolysis. It can be used to produce fine bronzes, with or without tin, or fine brass without zinc. It may also be used to make superior solder and does not require silver in a silver solder. The metal is self-lubricating and has a rather greasy feel in its finished state because of this lubricative nature. These blends tend to be self protective against bruises and replace themselves if scarred or bruised.

As examples, very fine-grained alloys of copper and lead, with copper as high as 40% and with 60% lead have been made. A particular example was 61.02% copper, 38.75% lead, with the remainder being other metals or impurities. In other instances, 70%30% mixes have been :made. Any percentage of copper and any percentage of lead can be used. The same proportions and similar proportions apply to copper-aluminum blends, leadaluminum blends, and magnesium-lead blends.

A blend of 97.5% lead and 2.5% copper made accord ing to this invention makes an excellent material for covering or cladding wire cable, for it acts like a grease for the wire, when the wire is under strain and friction develops between Wires. Iron plates and bolts clad or plated by this blend are less subject to corrosion.

The blends of lead and copper made according to this invention have another remarkable property. When such a blend has been molded or extruded and cooled, it can be cut or sawed into, and the freshly cut surface appears as a silvery color, while the outside, uncut surface has a coppery color. After the cut surface has been exposed to the atmosphere for a short time, it takes on a coppery or brass-like surface. If this surface is filed off, the silvery color reappears, and this, too, becomes coppery after exposure to oil or water or air, and so on.

If the blend of this invention is remelted and poured again without the treatment of this invention, dendrites form throughout the cold ingot.

I claim:

1. Preparing a fine-grained blend of lead with metal chosen from the group consisting of copper and aluminum, comprising the steps of:

(a) separately melting each metal,

(b) maintaining each metal under chemical reduction conditions,

(c) mixing the metals together thoroughly while subjecting the mixture to chemical reduction, and

'(d) immediately pouring the mixture and hardening it.

2. The process of claim 1 wherein said chemical reduction conditions include a cover of carbon over each metal during and after melting.

3. The process of claim 2 wherein said chemical reduction conditions also include stirring each metal with a carboniferous stick before mixing and stirring the mixture during the mixing.

4. The process of claim 3 wherein said stick is hardwood that has been soaked in a lye solution and then thoroughly dried.

5. The process of claim 3 wherein said cover of carbon additionally contains an alkali hydroxide.

6. The process of claim 5 wherein said alkali hydroxid is sodium hydroxide.

7. The process of claim 2 wherein the metals are mixed while agitating and swirling them together.

8. The process of claim 1 wherein the heavier metal is poured into the lighter metal at the mixing step.

9. A process for making a fine-grained blend of copper and lead, comprising the steps of:

(a) weighing each metal out in an amount needed to provide desired preparations in the blend,

'4 (b) separately melting each metal in a separate crucible, (c) while covering each metal with a layer of charcoal, 4 (d) stirring each metal, when it has melted, with a wooden stick,

(e) adding to each charcoal layer an amount of lye,

(f) pouring the molten lead into the molten copper, While stirring with a wooden stick and while main taining the charcoal-lye cover,

(g) mixing the molten metals thoroughly, and

(h) then immediately pouring the mixture and cooling 10. The process of claim 9 wherein said step (g) includes pouring the mixture back and forth between crucibles.

11. The process of claim 9 wherein said wooden stick has previously been soaked in a lye solution and thereafter thoroughly dried.

12. A process for making a fine-grained blend of aluminum and lead, comprising the steps of:

(a) weighing each metal out in an amount needed to provide desired preparations in the blend,

(b) separately melting each metal in a separate graphite crucible, v

(0) while covering each metal with a layer of charcoal,

(d) stirring each metal, when it has melted, with a wooden stick,

'(e) adding to each charcoal layer an amount of lye,

(f) pouring the molten lead into the molten aluminum,

while stirring with a wooden stick and while maintaining the charcoal-lye cover,

(g) mixing the molten metals thoroughly, and

(h) then immediately pouring the mixture and cooling it. 13. The process of claim 12 wherein said step (g) includes pouring the mixture back and forth between cruciles.

14. The process of claim 12 wherein said wooden stick has previously been soaked in a lye solution and thereafter thoroughly dried.

References Cited UNITED STATES PATENTS L. DEWAYNE RUTLEDGE, Primary Examiner E. L. WEISE, Assistant Examiner U.S. c1. X.R., 162, 163, 166 R, 166 E