US1869498A - Process of treating molten copper and copper alloys with compositions containing "lithium-alkali" alloys and products resulting from such treatments - Google Patents

Description

Patented Aug. 2, 1932 UNITED STATES PATENT OFFICE HANS OSBOBG, OF FRANKFORT-ON-THE-MAIN, GERMANY PROCESS OF TREATING 'MOLTEN COPPER AND COPPER ALLOYS WITH COMPOSITIONS CONTAINING LITHIUM-ALKALI ALLOYS AND PRODUCTS RESULTING FROM SUCH TREATMENTS 1T0 Drawing. Application filed December 21, 1981, Serial No. 582,491, and in Canada June 26, 1931.

The present invention relates to a process of treating copper-bearing metals and alloys in their molten state with an alloy of lithium and a metal of the alkali group, including alkali and/or alkaline earth groups and/or rare earth group, and to the improved products resulting from such a process.

Heretofore, a great variety of scavengers and improvers of copper-bearing metals and i alloys have been proposed. Of these scavengers and improvers, the more important were manganese, silicon, zinc, magnesium, phosphor and phosphides, metallic lithium, metallic calcium, etc. From an industrial point of view manganese, silicon, zinc, magnesium, phosphor compoundsand phosphides have been the most important, but the art was attempting to'obtain better and more satisfactory results than those obtained J bv-the use of these substances. With this object in view, those skilled in the art were attempting to find improved scavengers. Metallic lithium and metallic calcium were proposed, but it was found that these metals" had shortcomings and disadvantages when used on an industrial scale. ous disadvantages were that the molten metal and alloy undergoing treatment was not cleaned completely, did not possess the desu sired improved properties and usually was contaminated with impurities or contained blow holes. In other words, when lithium or in fact some other vmetal of the alkali group or alkaline earth group was added to .15 a molten bath of. metal thesedisadvantages were encountered which in many cases not only counter-balanced any advantages but.

actually overbalanced any advantages. For instance, in the treatment of copper and cop- 40 per alloys, the lithium added to treat the molten mass of copper was quickly volatilized. from the molten bath and the remainder produced results which were not uniform nor satisfactory. Folinstance, the electrical conductivity of copper whentreated with lithium metal was sometimes only 90 to 95%} and the fracture as well as the specific gravitv were inferior to those usuallyobtained with the conventional easting methods and procedures employed in the copper indus- I known,

The more seritry. From a practical point of view, it was and disadvantages noted .hereinabove withrespect to prior scavengers including metallic lithium and metallic calcium and/or processes of using the same but, as far as is no scavenger and/or improver and/or process of using the same has been proposed which is wholly satisfactory-and vpractical when used on an industrial scale.

It is an object of the present invention to rovide a process'of treating copper, copperhearing metals and alloys in their molten state so as to obtain the-benefits resulting from lithium treatments without the disadvantage noted hereinabove.

It is a further object of the invention to provide a simple, economical and thoroughly satisfactory process of treating copper-bearing metals and alloys in their molten state with active lithium-bearing substance so as to improve the characteristics thereof.

It is another object of my invention to provide 'a process of treating molten copper metal and molten copper alloys with an active lithium alloy of a metal of the alkali group or alkaline earth group or' rare earth group which is capable of being carried into commercial practice on an industrial scale in' the ferrous .andthe non-ferrous industries, which is also capable of producing-greater efiects than providqd by the same amount of lithium and the like. i Other objects and advantages of the invenin%descriptioni I roadly stated, my invention contemplates tion will become apparent from the follow- I the treatment of molten copper-bearing metgroup in which the lith duced; At the same time, the alloy I can function actively to effect im rovements' in the properties and qualities 0 the metallic, substance under treatment. I have found that in carrying my invention into practice, that lithium alloys containing members of the alkali or alkaline earth families such, for example, as calcium, barium, strontium, magnesium, cerium, lanthanum sodium or potassium or relatively stable compositions of lithium and silicon or of mixtures of the foregoing substances can be utilized in the treatment of metals and alloys in their'molten state so as to efiect improvements in the properties and qualities in the metals or alloys treated.

The following examples are given for illustrative purposes and for a better understanding of carrying my invention into practice.

General In copper it is not difficult, to make a fairly good grade of copper from a poor one. There are even processes in use to produce a good copper, especially a high conductivity copper from a good grade of electrolytic copper.

But up to the present it seemed rather difii- Z of h gh conductivity copper, I have found it results in, for instance, very pure copper, free from oxygen, sulphur, gases etc. Since photomicrographs did not show impurities at all, the copper treated according to my process was subject to the hydrogen annealing test which is very sensitive for traces of oxygen, but no oxygen could be detected; An excellent electrical conductivity, ranging from about 99-104% alsoresulted {unusually high densities, ranging from about 8.90-8.95. Excellent fractures. i. e., excellent crystal structures of the thus produced material were obtained. It is easy to obtain a radial (so-called sunburst) structure, which is desirable for making seamless pipes, or to obtain a silky fracture (very fine grain) which gives the metal excellent working qualities by the use of the present invention.

The industrial application of my process has many other advantages. I Some of them are :The amount necessary is so little that it is economical to use my scavengers even for copper or copper alloys which are not produced for special electric conductivity purposes. The result of the treatment is in any case a first class material. The treatment cantake place at temperatures between 2100- 2206 F., 'i. e., it is-not necessary to heat the copper to 2300 F. or to overheat it as is c; necessary for other processes which yield even lower results. No chan e in customary procedure is necessary. new furnace, (1200 lbs. capacity) it was found that the amount of copper which had to be scrapped before obtaining a satisfactory Table I Electric Fracture Treated with rating ggigf' per cent per 09m;

Present scavenger B. 92 100 101. 3 Phosphorous 8. 83 93 88. 0 inc 8. 05 90 97. 6

Photomicrographs of copper treated in accordance with the present invention showed that the copper had improved characteristics including improved crystal structure; complete deoxidization, freedom from inclusions, gas holes, etc.; soundness; etc.

It should also be noted that a copper-tin alloy containing 1.75% of tin was materially improved when treated according to the present invention and that about a 0.04% addition of the present lithium-alkali alloy have been used by the industries for commercial purposes. Other copper alloys have been decidedly improved by the use of the present invention too.

Example 1 tively treating about 100 parts of molten copper or copperalloys.

The addition of the active lithium alloy to .the molten metal is preferably effected b plunging the selected amount of active lith1-' um alloy into the molten material in a crucible by any appropriate means such as an inverted cup with side openings or ports or they like. By adding the active lithium alloy to the molten metal in the aforesaid manner,

I am able to eflect a thorough distribution of the lithium alloy throughoutthe molten en starting a mass and to efiect the proper treatment of said metal to improve the properties and qualities thereof.

When copper or alloys thereof are treated with one of my active lithium-bearing alloys, the molten mass has a better fluidity and consequently, can be cast very much .betterthan heretofore and gives better and denser castings. In addition, the physical properties of the copper or metal or alloy treated are improved. For instance, there is an in-' creased toughness and corrosive resistance of the metal. thus treated and the finished product is relativelyor practically free. from blow holes, oxygen, sulphur and the like. The copper treated in this manner, has abetter conductivity than when untreated or treated in conventional ways.

Example 2 When copper or acopper alloy is used for the production of castings, I add to about 100 parts of molten copper'prior to casting enough of a lithium alloy such as a lithiumcalcium alloy or a mixture of lithium alloys having such a composition as to give a lithium content up to about 1%. The lithium al- .loy is preferably added in the form of a solid briquette, block, lump 'or the like, which is introduced into the body and preferably the lower portionof the molten mass of copper by means of an inverted cup or other appropriate instrumentality. The lithium 'alloy thus added, improves the crystal structure. of the copper; combines with gases, such as oxygen and nitrogen and also with such detrimental substances as sulphur and phosphorus increases the fluidity of the moltencopper and produces denser and sounder casting than produced heretofore. In practice -,I prefer in some instances to add the lithium alloy in a mass which is surrounded by or coated with copper silicide'. By adding the lithium alloy in this manner, the procedure is facilitated. If it is desired a lithium-calcium alloy can be silicided and then the silicided lithium alloy used for the treatment of the molten metal or alloy.

In some instances, I prefer to employ an alloy of lithium with the metal or alloy to be treated. For example, if copper is to be treated, I use an active lithium alloycontaining copper. -The. lithium alloys should preferably have a lithium content of about 50% and should be silicided or reacted with silicon prior to use.

The amount oftlithium alloy added to the molten metallic mass depends upon a number of variables as-one skilledin the art will readily'u'nderstand. For'exam'ple, the per-' cen'tage-of lithium in the lithium alloy will determine-in part how much of the substance s to Then a sin the amount of impuritiesand gases in t e molten metal or aloyfand the improvement to be given to the cessful and satisfactory results which are ac- I ceptable to those skilled in the art.

It will be further observed that the present invention provides a method for the pro-. duction of improved metals and alloys which not only can be carried out on a laboratory scale but which also can be carried out on an industrial scale.

It will also be noted that the present invention provides a process by the use of which thedisadvantages inherent in the sole use oflithium alone or other member of the alkali group or the alkaline earth group alone or rare earth group alone are avoided and unexpected advantages are obtained from the use of lithium alloys of metals of the alkali group. or the alkaline earth group or rare earth group. The lithium in alkali alloys contemplated by my invention is exceedingly active and has an activity which could not be predicted from the prior use of lithium alone orv of other metals of the alkali or alkaline earth groups alone.

Although I have herein described specific illustrative examples of my invention which included specific substances, percentages and the like, it is to be observed that the invention is not to be limited thereto but the scope and spirit thereof is to be determined by the appended claims. For instance, when in the specification and claims I use the term lithium-alkali alloy it isintended to mean lithium alloy of a metal of the alkali group or alkaline earth group or rare earth group. Similarly when the term alkali is used, it is intended to refer to alkali group, alkaline earth group or rare earth'group.

The present application is a continuation in part of my co-pending application, Serial No. 467,625, filed July 12, 1930, entitled Processes of treating molten metals and alloys with compositions containing lithium and products resulting from such treatment.

What is claimed is:

1. The process of treating copper and/or copper alloys thereof in their molten state to improve the properties thereof, which comprises treating said copper and/or copper, alloys thereof while ina molten state with a l thi m-alkali alloy.

2. The process set forth in claim 1 in which the lithium-alkali alloy contains lithium and calcium.'

' 3. The process set forth in claim 1 in which up to about 2 parts of the lithiumalkali alloysis used to about 100 parts of copper and/or copper alloys thereof.

4. The process of treating copper and/or copper alloys thereof in their molten state to improve the properties thereof which comprises dipping a solid body of an active lithium-alkali alloy into a molten mass of copper and/0r copper alloys thereof to be treated and stirring the thus treated molten mass to effect a thorough distribution of said lithium-alkali alloy.

5. The process of treating copper and/or copper alloys thereof in their molten state to. improve the properties thereof which comprises adding a briquette containing an active lithium-alkali alloy to the lower portion of a molten mass of copper an'd/or copper alloys thereof to be treated and causing a thorough mixing of said lithium alloy in said molten copper and/or copper alloys thereof.

-6. The process of. treating copper and/or copper alloys thereof in their molten state to improve the properties thereof which comprises adding a lithium-calcium alloy to a 'molten mass of copper and/or copper alloys thereof to be treated and stirring said molten mass to effect a treatment of the various parts of said mass with said lithium-calcium alloy.

7. The process of treating copper and/or copper alloys thereof in their molten state to improve the properties thereof which comprises dipping a block of lithium-calcium alloy into the lower portion of a molten mass of the copper and/or copper alloys to be treated and effecting a distribution of said flithium-calcium alloy substantially throughout said mass.

8. The process of treating copper and/or copper alloys thereof in their molten state to improve the properties thereof which comprises adding a lithium alloy containing an alkali metal to a molten mass of metal or alloy to be treated and stirring said molten mass to effect a treatment of the various parts of said mass with said lithium alloy containing an alkali metal.

9. The process set forth in claim8 in which the lithium alloy is coated with lithium.

10. The improved copper and/or copper alloys thereof which comprises a copper and/or copper alloy thereof resulting from the treatment thereof in molten state with a lithiumalkali allo 11. The improved copper and/or copper alloys thereof as set forth in claim 10. in

which the active lithium alloy is a lithium calcium alloy.

12. An article of manufacture comprising an improved copper and/or copper alloys thereof containing residual lithium-alkali alloy.

13. An article of manufacture set forth in claim 12 in which the lit-hiumalkalil alloy comprises lithium and calcium. I

In testimony whereof, I have hereunto set my hand.

HANS OSBORG.