US971136A - Process of producing compound metal bodies. - Google Patents

Description

Patented. Sept 27, 1910.

mania-#271111 S S J. F. MONNOT. PROCESS OF PRODUCING COMPOUND METAL BODIES. APPLICATION FILED 001'. s, 1965. RENEWED FEB. 24, 1910.

WITNESSES:

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JOHN rnnnnon MONNOT, or new YORK, N. Y., ASSIGNOR T DUPLEX METALS com- PANY, or new YonK, 1v. Y., A oonrona'rron on NEW YORK.

PROCESS OF PRODUCING COMPOUND METAL BODIES.

Specification of Letters Patent. Patented! Sept, 27, 191(1).

Applicationfiled. October 6, 1905, Serial No. 281,680. Renewed February 24, 1910. Serial No. 545,712.

To all whom it may concern:

Beit known that 1, JOHN FERREOL MON- NOT, a citizen of the United States, residing in the iiity, county, and State of New York,

have invented certain new and useful Processes of Producin Compound Metal Bodies;' and I hereby dec are the following to be a full, clear, and exact description of the same, such as will enable others skilled'in the art to which it appertains to make and use the same.

- together maybe used to great advantage in a variety of arts and for many different purposes, as combining the specific advantages of the component metals. For example, plates or sheets composed of a readily oxidizable metal, such as iron or steel, covered with an impervious coherent coating of copper or other less oxidizable metal, may

be used to great advantage in -place of ordinary iron or steel plates or sheets wherever such plates are exposed to the weather, air, or other oxidizing influences or to the action of corroding liquids, gases or vapors which readily attack iron or steel but do not attack at all, or at least to so serious an extent, the coating metal employed. Plates, sheets and other articles of copper, silver, gold, aluminum, brass, bronzes, etc., backed with iron or steel may be used with great advantage where considerable strength or stifi'ness of metal is desired,,coupled with the chemical, physical, electrical or other properties or color or appearance of the non-ferrous met als mentioned. For electrical conductors, it is desirable to combine the high electrical conductivity of copper, aluminum etc. With the great strength of steel. Many other uses might be pointed out. In all cases such as mentioned, it is a prime requisite that the unlike metals shall be so inseparably united that the compound ingot, sheet, rod, etc. may be capable of great extension or working, as

by rolling or hammering to thin sheets, rods, angles, tubes, etc, drawlng, pressing in dies, spinning etc., without separationof the component ayers, without development of seams, pores, flaws, etc; and it is in fact desirable that during such working the strata of the component metals shall maintain substantially their original relative proportions, even down to the thinnest'sheet or wire.

. Electro-plating or electro-deposition of metals does not produce a coating possessing the qualities above pointed out as substantial or absolute requisites. On the contrary, electricallydeposited coatings are porous, the metal being thrown down in crystalline form with dividing lines and interstices between the crystals, so that oxidizing or corrosive liquids, vapors, and gases penetrate the coating and attack the metal beneath; neither is the adhesion of electrically-deposited coatings good, such coatings being merely adherent to the base, and not coherent thereto, and for this reason "and also because of lack of cohesion in the coating itself, it is impracticable to roll or draw electro-plated metals without destroying the con tinuity of the coating.

For similar reasons, tinning and galvanizing do not produce as satisfactory results as is desirable, and it is not practicable by these processes to produce large coated surfaces which are everywhere free from defects and permanently united with the base; moreover for. many purposes tinned and galvanized surfaces are altogether unsuitable, because not possessing the desired superficial appearance and other qualities; and a tinned or galvanized coating will not stand extension by drawing, rolling, pressing between dies, etc., to any great extent. Neither do brazing, soldering and similar non-autogenous processes satisfactorily unite unlike metals for all purposes, the metals being merely stuck together, and the articles produced by such processes being incapable of extension by drawing and rolling, etc., to as great an extent as desired, being likely to separate'by heating, etc.

brass, -bronze, etc. to iron, steel and the like,

which coatings may vary from any desired thickness to a-tenuity comparable to that of ordinary elcctro-coatings. When the unlike metals are absolutely welded together, as by my process, no difficulties are encountered such as are experienced in the use of electroplated articles and in the use and working ing from its base, and with substantial maintenance of the original ratio of thickness of the coating to the thickness of the base. Moreover the coatings so extended or drawn out can be obtained in a dense and extremely hard condition as compared with electroplated, tinned and galvanized coatings, and thus are far more durable.

In the many unsuccessful attempts in the prior art to produce articles similar to or equivalent to those produced by me, no one has been able, so far as I am aware, to produce a coating such as described, as for example a coating of copper on steel, which could not be separated from its base by meansof a cold chisel or equivalent tool, or to produce a coating in-extended ware so indivisibly welded to the steel base as to rely wholly on the steel for support. In such prior articles, owing to lack of perfect union to the base it has been necessary to provide in the extended ware a thickness of coating sufficient in itself to furnish the necessary coherence and strength to prevent destruction. I am not aware that in such prior extended articles a coating of much less than 30 per cent. has ever been found practicable, whereas in ingots intended for extensive extension, I may provide a coating of no more than 5 per cent. thickness, or even as little as 3 per cent. or less when the articles to be made from such ingots (as for example, structural steel shapes) are not to be greatly reduced-in cross section. Whatever the proportionate thickness put on the ingots or intermediate products of my process, the same proportion will be found in the extended ware or final products of my process. For instance, if in the large ingots, I apply a 5 per cent. coating of copper, about a 5 per cent. coating will be found on wire drawn from said ingots. Naturally, if this wire v be very thin, the copper coating will also be thin, but it will still be about 5 per cent. at any portion of the Wire. the extension is carried, the coating will remain permanently united to the steel base, the weld film connecting the base and coat- Furthermore, to whatever extent ing extending indefinitely with extension of the material, and being absolutely lnseparahle from the base; so much so that either in the ingot or in the finished article it is impracticable to separate the coating from the base by a 'cold chisel or equivalent tool, the tool refusing-to follow the line of the weld. It is'also mseparable by heating short of melting, or by bending or other stress on the weld.

In the heavy-coated articles of the prior art just referred to, because of the lack of the intimate and perfect union such as socured by me, there is always found, in the ingot for example, a large proportion of thecompound metal in which there are flaws,

defects and places of no meeting of the joined metals which must be cut out and rejected, thereby entailing an undue wastage, both of material and of the skilled labor required in such prior processes. In my articles, on the other hand, and in my process, the union .is so intimate and thorough between all meeting surfaces that there is no need of loss by wastage or in labor. "The process is conducted in such manner that there is no possibility of scale-spots and similar defects developing.

' Of course it may be understood that I can in some cases, apply the coating to the finished article, and in such instances, if the article be lar egthe copper, .etc. may not be more than a fractional per cent. of the total metal. Ordinarily, however, I contemplate applying a substantial thickness to an intermediate article or compound ingot, and then reducing or extending the same in any of the well known ways to furnish a complete article, since by such working the impervious and other qualities of the coating are improved.

For the production of coated surfaces of large area, as for example sheets, wire etc., my process has the important advantage as compared with electro-plating, tinning, galvanizing, soldering, brazing etc., that whereas by such former processes the entire surface to be coated-must receive the careful attention of the operator to avoid flaws, etc., and such surface is substantially the same as that of the finished article, according to my process the surface of union between the V unlike metals is, in the first instance, relatively small, being that of the relatively thick ingot, slab, plate etc. from which the finished article is produced by extension;

. and the surface thus coated being relatively small, it is easy and economical to bestow thereon a high degree of care such as will insure an absolutely perfect unionbetween the unlike metals. In the subsequent work- 'ing of the welded ingots, plates etc., the

weld extends uniformly with the metals on each side of it, even to the thinnest articles; so that by the relatively small amount of care necessary to insure a perfect union in the ingot or equivalent preliminary stage,

the production of'perfect sheets, rods, wires etc. therefrom is substantially assured.

' a necessary that the union between the unlike ',metals shall be complete throughout; that I 23, 1905 Sr. No. 261,739; filed June 16, 1905,

there shall be no unwelded s ots, no bubbles', blisters, or particles 0 oxid, scale, cmder, or other foreign substance between the metals or embedded therein, and that the coatingshall be homogenous and free from-flaws, bubbles, pores, hard spots, etc.;

for it is of the utmost importance that in the process ofdrawing or working, a flaw or blister shall not develop in the sheet or other article being worked. In these respects former processes of uniting unlike metals .by attempted welding have been defective,

it having proved practically impossible to "produce sheets of reasonably large size, or

rods, tubes' or wire of reasonable. length, without the development of such flaws, blisters, scale-spots or the like, in all or a large portion of the product, as to greatly impair if not actually ruin the product, making the commercial carrying-out of such processes a practical impossibility.

In this specification, and in the specifications of copending applications filed May Sr. No. 265,508, (patentedas No.-851,684, April 30, 1907) and filed Sept. 6, 1906, Sr. No. 333,570 (patented as No. 853,716, May 14;, 1907,) I have set forth processes of pro, ducing compound ingots, plates,.bars etc. by which the difliculties above recited are overcome, an'absolute and permanent union between the metals at; all points being assured, and any desired thickness of the coat ing being applied; and this without the exercise of more care than may reasonably be expected of workmen skilled in similar metallur cal operations.

According to my process, I produce union between unlike metals such .as specified by producing actual molecular contact and interpenetration between the metals themselves, while one of said metals is at .a welding temperature and the other is .in what I term a super-molten condition, its temperaturebeing so high that the metal is extremely fluid and is apparently capable of direct chemical orsolvent action on the first metal. In order to produce this actual molecular contact of the metals, the surface of that metal which is in the solid condition must be an absolute metallic surface, entirely free from oxid, scale etc., the surface being not merely clean in the ordinary sense, but clean in the chemical sense. A' method of producing such a-surface is described molten metal contacts with such an absolute metallic surface, heated to or about its welding tcmperatlu'c, said molten metal unmcdiately wets the entire surface of the.

solid metal, attacking, impregnating and entering into combination or union or solution therewith possibly, forming an alloy; and there are no spots on the surface of the solid metal exposed'to the action of the supcrmoltcn metal which the latter does not attack, so that the union is complete and uniform lhrouglumt. The entire body of this coating metal. may-be in the supermolten condition described, in which case special means are employed for causing solidification, on the surface of the metal coated, of the predetermined thickness of coating, as described in my applications above mentioned; for wlthout'such special means only a mere film of molten metal would adhere to the base or core metal upon the withdrawal of the latter from the action of the molten metal, owing to the extreme fluidity of such molten metal. But preferably the metal coated is \\-'ithdra\vn from the action of the supermoltcn metal as soon as a thin coating or alloy-tilm has been formed thereon, and then a further body of coating metal at a more convenient temperature for casting, usually such tlmt'tlxc metal is only relatively slightly above its melting point (and it may even be in a semifiuid or plastic state) is brought into con.- tact with the surface so coated and is caused or permitted to solidify thereon to the predetermined thickness of coating, the welding together of the composite mass thus produced being accomplished finally by pressure, which inay be either the pressure due t0-s0lidification and shrinking of the coating metal, or may be pressure applied positively, or both. Preferably, particularly when copper or other metal wlnch tends to solidify in a fiawy or porous condition is the coating metal employed, I employ externallyapplied pressure, as by means of a hammer or press or bypassing the coated article through rolls, thereby condensing the metal of the coating, eliminating flaws, cracks, sponginess or porosity of the coating, and the like, and. at the same time tending to insure a perfect weld. And I may also ap-' ply pressure from an external source to the molten metal surrounding the core or in contact with the surface of the base to which the coating is applied, to condense the coating metal as it- 'solidifies, to eliminate air bubbles, etc. l

The ingot, plate or slab thus produced may then be rolled, drawn, pressed, or otherwise worked down into any of the desired. forms, in the ordinary manner. This operation I term, broadly, extending the material.

As 'an example of the carrying out of my process. I shall hereinafter describe the production of a compound welded steel-copper ingot. It is obviously unnecessary to describe specifically the process as carried out with each of the litlerent metals'above mentioned. the production .of the steel-copper ingot being broadly typical of the production of the variousiother compound ingots.

For cleaning the surface of themetal core or base to be coated, so as to expose an actual metallic surface, I customarily proceed as follows: This base, which'in the present instance is assumed to be steel, asdefined above. is generallyin the form of an ingot, bloom. or large billet, on which there is usually a thick and adherent scale which the ordinary cleansing with acids, termed pickling, cannot remove satisfactorily. I therefore customarily employ mechanical cleaning. For this purpose, I commonly employ a powerful sand blast which penetrates all the small cavities full of oxid, etc. cleaning the same out thoroughly, cutting oti' all scale, ox-id coatings, etc., and leaving a clean surface of the actual metal; but for very fine work, as Where a very smooth surface isdesired, I grind the surface of the base, or remove such surface with a tool, as may be done for example in a lathe, or other machine tool. When the vcore or -base is thus cleaned mechanically it is pickled to dissolve any trace of oxid formed during handling or working, is

washed in hot water, and is dipped into a preferably to a low yellow -heat, at which.

- heat the steel is in a condition of exceptional receptivity, and thus unites readily with the coating 'metal. Such heat of the steel may be termed the welding heat thereof. The heating may be done by bringing the core or base in contact with a body of molten coating metal heated to a high temperature, as by plunging said core or base into a bath of such molten metal and leaving it there until it is superficially heated to the desired temperature; a temperature at which a cohering film of such metal can be formed thereon; But since a body of highly heated molten metal large enough to heat a succession of cores to the weldlng heat is expensive, liable to oxidation, and is otherwisetr'oublesome, preferably said base or core is heated preliminarily to 0r near the welding point before it is subjectedto the action of the molten coating metal. Such preliminary heating should be conducted under conditions such that oxidation or other chemical change'of the metal is prewhat below the welding temperature of the metal to be coated,.though it may be as high as said welding temperature orhigher), and at such temperature doesnot attack the core or base, but preferably is also capable of dissolving any oxid on the surface of the base.

Heating the steelin a bath of this nature offers many important advantages for the present purpose since not only is the contact 'of air with the hot clean metal precluded but also the contact of-other gases, such as products of combustion, and of soot, etc.

sodium, sodium chlorid, and cuprous.chlorid.

Many of the substances which 'may be used, as for example borax and cuprous chlorid, form a. protecting coating or film on the core or base, if the core be not too hot as the same is drawn out of the heating bath,-which effectually prevents oxidation of the metallic surfaces after withdrawal from the bath sequent operations; The formation of such protecting coating is one of the important functions of the bath.

The appearance of the'coating of flux adhering to the core or base upon the with drawal of the latter from the action of the flux bath, indicates'the perfection of the previous cleaning or the condition of the surface of the core or base, any spots not perfectly clean being readily observable. The core or base thus cleaned and heated and protected against oxidation is then exposed momentarily to the action of the coating metal, which metal is'not merely in the molten condition, but is in a condition of extreme fluidity, comparable to the fluidity of water, which condition I term the supermolten condition In this condition, the molten metal not only immediately wets thoroughly and at all points the surface of the base or core exposed to-its action, penetrating also all irregularities .(the film of adhering flux rising as the molten metal avoiding the carrymgof air into the molten 'Hot, clean steel is extraordinarily sensitive and while in transit through the air to submetal and so avoiding oxidation thereof, and also leaving an absolutely clean surface for the action of the molten metal); but said molten metal appears to be chemically active, and it maybe that it exerts a chemical action on the surface ofthe base or core metal, entering into combination therewith and forming an alloy-film, which is the immediate means of uniting and bonding to gether the metal of the core or base to the coating metal. Obviously, because of the extreme fluidity of the metal which is used, but a very thin film of said metal will remain upon the surface of the core or base upon withdrawing the latter from the action of the super-molten metal; to overcome which difliculty, I have devised apparatus, illustrated and described in my Patent No. 851,68i, whereby as the core orbase is withdrawn a portion of the molten metal of sufficient thickness immediately surrounding said core or base is inclosed in a. suitable casing, being thereby segregated from the main body of-such molten metal and withdrawn with the core or base, and is caused thereby to solidify quickly upon the latter. Instead of so doing, in the present case I preferably withdraw the core or base from the action of the super-molten metal, with the layer of metal thereon, and bring against such surface of'the core or base apredeterminate volume of coating metal of lower temperature, permitting such coating metal to solidify on the surface of the core or base. In so doing, this second body of metal will unite readily and inseparably to the film already formed, the union of the second or main coating to the film-coating and to the base or core being completed by pressure, which may be either the pressure due to the solidification and shrinking of the main coating, or may be pressure specially applied, 2'. 0., applied from an external source, or may be both; The degree of pressure required or employed depends largely upon the temperature at which the operation takes place, pressure and temperature in this operation being in some degree interchangeable, so that the hotter the mass of coating metal and the core or base, the less the pressure required. But when the coating metal is copper, it is desirable to employ pressure applied from an external source, as otherwise there are likely to be flaws, blow-holes, sponginess, porosity,"etc., in the copper. The ingot or plate or slab thus formed is customarily worked down between rolls or in presses, or is drawn or otherwise treated in the ordinary manner,

to reduce or extend it to the desired form. In this working, the compound welded-material behaves in some respects as if composed of a single metal, except that it is in many respects more easy to work. Steelcop er plates, for example, are much-easier to draw than steel plates, requiring much less annealing. In drawing, spinning, rollmg, etc. the copper appears to act asa lubricant, greatly facilitating the operation.

During the working of the compound material the original proportion of thickness of coating to thickness of base or core is substantially maintained, down even to very thin sheets, so that it is perfectlypracticable, by regulating the thickness of the coating initiall to determine accurately the thickness 0 the coating of the finished article.

In the accompanying drawings I illustrate diagrammatically the carrying out of my process.

The apparatus illustrated is diagrammatic, but will indicate sufiiciently to those skilled in the art the actual construction. of

apparatus which may be employed.

In these drawings, Figure 1 shows diagrammatically and mainly in section apparatus comprising heating and filming baths, together with means for maintaining the same at the proper temperature, ingot molds, and means for dipping a core first into the heating bath, then into the filming bath,-and finally depositing the same in the ingot mold and withdrawing the finished ingot. Fig. 2 shows alternative means for applying and regulating the thickness of the coating applied to the base or core.

Referring first to Fig. 1, numeral 1 designates a heating bath, termed ordinarilythe flux bath, containing molten cuprous chlorid, borax, fluor spar, cryolite, or other fusible material which will serve to heat the core to an approximation to the welding heat while preventing oxidation thereof. 2 designates the final heating and filming bath,

containing the super-molten coating metal (copper, in the instance assumed) for forming the cohering-film on the core. In order to prevent oxidation of the metal of this bath, and also to cover the filmed core with a protecting coating when said core is withdrawn from this bath, the surface of the bath is covered with a layer of molten flux or borax, 3, or other material suitable for the purpose. 4 designates heating means for said baths, the particular means illustrated being a reverberatory furnace, though in lieu thereof anysuitable heating means may be employed. 5 designates elevating and traversing means for handling the core, the particular. means illustrated being a power hoist and traveling crane. 7 designates thecore.

In carrying out the process, the core 7,

which has first been cleaned rigorously as previously described so that it presents an actual metallic surface entirely uncontaminated and chemically clean, is immersed in the heating bath 1 and allowed to remain therein until heated to the proper temperature. I can advantageously employ cuprouschlorid for this purpose as it appears so that loan employ it at almost any temperature from that point up, it being one of the few salts which are practically unchangeable and undecomposable by heat. It also has the great advantage of dissolving any possible oxid which may remain or may have formed in handling the core. .Borax is also Well adapted for this purpose, and will also dissolve any traces of oxid present. Either material therefore affords suitable means for heating the steel core to what is, for the purpose of this process, at least, a Welding temperature, viz., a low yellow heat. However, I customarily heat the core only to a somewhat lower temperature in this preliminary heating bath, the final heating to the welding pointbeing done in the alloy-filming bath. Cuprous chlorid' has'no action on the core, but protects it absolutely from surface oxidation and when the core is removed from said bath a film of fiux remains on it to protect it from surface oxidation while in transit to the alloy-filming bath, excluding the air.

The core when heated in the flux bath to the proper degree is withdrawn therefrom and immersed in the filming bath 2, the flux on the surface of the core rising to the surface of the bath as the core descends, thus exposing an absolutely clean surface to the supermolten coatin metal, excluding air from the surface-o the core, and avoiding the carrying of the air down into the molten metal. Said molten metal, being in the supermolten condition, above described, in

which it appears to be chemically active,

raises the core to the welding temperature (if said core is not already at that temperature), and what may be an alloy film is formed next the core, the-molten metal apparently uniting chemically or by a solvent action with the steel. The core so filmed is then withdrawn from bath 2, dipped'in a bath of molten metal 12 (Fig. 2) maintained near its point of solidlfication, and then withdrawn from such bath 12, with the adhering mass of metal from said bath 12, any excess of metal from said bath being scraped off if desired by passing the ingot through a suitable scraping gage 13.

Instead of dipping the filmed core into a bath of molten metal maintained at such temperature that upon withdrawal a considerable mass of metal from such bath will adhere thereto, the filmed core may be placed within an ingot mold 6 (Fig. 1) such mold having preferably been charged previously with the required quantity of molten coating metal required for forming the predetermined thickness of coating, such molten metalrising up around the core as it descends into the mold and completely filling pressure due to passing the ingot between i the rolls or by hammering or the action of a press. A complete weld'and sound coating is thereby formed.

After the formation of the coating as thus described, the ingot is customarily worked between rolls, in a press, or under a hammer, to condense the metal of the coating. This may be done either before the ingot has cooled, or the ingot may be reheated by exposure to a soaking heat for the purpose. Finally, the in ot is worked in the ordinary manner to rec uce or extend it into rods, sheets, plates, tubes, wire, or any other desired final form. The coating thusproduced is dense, homogeneous, and free from flaws, cracks, pores, and defects, even when the material has been extended into thin plates is exceptionally hard and firm. Because the attention required for the production of the weld is confined to a relatively small surface, it is easy and economical to insure perfect conditions for the production of the weld; and the weld-film extendsindefinitely during the subsequent extension of the material, insuring equal perfection of union be tween the unlike metals in all portions of the extended article, even in the case of thin sheets. In this respect my process has an important advantage over processes of. joiuing sheets by soldering, brazing, et'c.; for in such processes the utmost care must be exereised over every part of the surface of every sheet; the amount of care required being therefore infinitely in excess of that required 111 my process.

I believe, as a result of careful observation both of ingots and of extended ware made according to my invention, that in my process .of welding, I produce a layer of the utmost tenuity between two unlike metals which appears to be dense and very strong (stronger than the Weaker of the two unlike metals, 6., in the case of the steel-copper material, the intermediate weld-film or unit-.- ing film appears to be stronger than the'eopper,) as is shown by the fact that in attempting to part the compound ingot with a cold chisel,'the tool refuses to follow the line of union, the separation produced by the chisel being usually in the coating. In other words, in my product there is no solution or break of continuity, and the coherence between. the molecules of the welded metals is rather stronger than between the molecules of the softer metal.

Obviously the above are onlyafew of the many available ways of carrying out my process. Many modifications will naturally suggest themselves to those skilled in the art. For example, instead of heating the core in a heating bath, as above described, or in the molten coating metal, it may be heated in an indifferent or non-oxidizing atmosphere, such as that produced by pro ducer gas, or may be heated electrically. In fact, any method of heating said core which will bring it to the required temperature while avoiding oxidation of its surface or other chemical change, may be used. To avoid any possible oxidation of the metallic surface to be coated while being heated or while being handled, or while awaiting heating and filming, I may cover said surface after pickling and washing, or at any other suitable stage, with a suitable protecting coating, as for example a fusible indifierent paint, such as a mixture of water glass and powdered aluminum, which will exclude air from the said surface. A protecting covering of this character will be especially desirable when handling extremely pure steel, such as that of the Tropenas process, which is especially prone to absorb oxygen, and

possibly other gases.

The protective coating or paint used should be of such character that when exposed to the molten metal it will melt and rise as slag, leaving an absolutely clean surface.

The metals which I customarily employ in. coating steel as above described are all metals having a melting point above 900? F., steel requiring tobe heated to above500 C. to

perinit the great extension after coating contemplated in my process. All of the metals herein mentioned as intendedto be used as coating metals, have melting temperatures far above 900 F., except possibly some of the brasses and bronzes and like alloys.

customarily, the metal used to form the film-coating is the same as the metal of the main coating; but it may at times be a different metal. For example, in forming steelcopper ingots, the alloy-filming metal em ployed may be aluminum, which unites readily with steel and to which the copper unites readily.

Obviously, it will often be desirable to apply the metallic coating merely to one or more, but not all, of the sides of an object; in which case the film-coating and the main coating may be applied only to the surface which'it is desired to coat, in ways which will be obvious to those skilled in similar metallurgical operations, as for example by shielding the surfaces which are not to be coated, or by contacting the molten metal only with those sides or surfaces which are to be coated,

In filming steel with copper, as above described, the copper of the filming bath is usually maintained'at a temperature, as nearly as I have been able to determine said temperatureaccurate determination of such high temperatures being very difficult; far above the melting point of copper. S11- ver may be treated in substantially the same way, and a filming bath of silver should be maintained at about the same temperature as one of co per. Aluminum, on the other hand, may e maintained at a somewhat lower temperature, say about 1800 Fahrenheit, since because of its greater afiinity for steel and lower melting point, it unites freely therewith at a temperature somewhat lower than do copper and silver.

One important field for my process above described, is the production of very pure iron or steel, containing practically no carbon or other metalloids, but coated with copper, aluminum, silver, gold, bronzes, or other suitable coating metals. Such pure iron or steel, as already stated, may be produced by the Tropenas process, for example, by carrying the operation to the point of substantially complete elimination of the metalloids, and then, before the steel com mences to burn, removing it from the converter. Such steel is very soft and ductile and malleable, and has also high electrical conductivity, but is extremely apt to take up oxygen and other impurities. By the method of handling and heating above described, however, it will be obvious that I can handle ingots or cores of such pure metal without oxidation or other contamination thereof; and once the coating of copper orother metal is applied, such coating protects the pure core metal from oxidation, etc. Because of the extremeductility of this pure steel, the compound ingots made from it may be extended to the most extreme thinness, thus making practicable the use of such material for foil, tinsel, gold leaf, silver leaf, etc. I may also produce electrical conductors consisting of this pure steel covered with a very thin protecting coating of copper, aluminum, or other suitable metal.

To recapitulate, my preferred process in the present application, speaking specifically of the copper-stee1 artlcles, consists in rigorously cleaning a surface of the steel core or base, preliminarily heating the same in a flux bath, preferably cuprous chlorid, withdrawing from the same and contacting said surface with supermolten copper, Withdrawing from the action of the same together with an adhering alloy-film, and contacting with said alloy-film, a predeterminate thickness of molten cop er and allowing said molten copper to solidify, then applying pressure thereto, as by rolls, and finally extending into the finished article.

In the following claims I employ the term ferrous metal to designate generically all inventions herein.

forms of iron, including not merely wrought iron, but also mild steel (the properties of which are very similar to those of Wrought iron), high carbon steel, and in fact steel of all grades and kinds, including various compound steels, such as tungsten steel, titanium steel, chrome steel, nickel steel, manganese steel, cobalt steel, etc.; also substantially pure iron, such as might be produced, for example by carrying the Tropenas process to the point of practically complete elimination of carbon and other metalloids, and then withdrawing it in this condition. I employ the terni non-ferrous metal to deslgnate generically the various unlike metals which may be welded or united to ferrous metals by the process herein described, including alloys, such for example as brass. bronze or other alloys having copper as their base or as an important constituent, aluminum alloys including aluminum bronze, etc.

In my said Patent No. 853,716, dated May 14, 1907. I have claimed the process of producing compound bodies of unlike metal involving the contacting of a surface of one metal with a supermolten mass of other metal, also the process of involving the film coating of a body of one metalby momen tary contact with a supermolten mass of the other metal and the formation of a substitution coating by contacting a further mass of molten metal wit-h such film coating and causing tlie same to solidify thereon; and in anotherapplication filed April 17, 1907, Sr. No. 368,770 I have claimed the process involving film coating a body of one metal with a second metal and then forming a substantial coating of a third metal on such film coating. Therefore. I do not claim these The. method of producing compound metal objects involving film coating a core with superniolten metal and then immersing the object so coated in a mold containing molten coating metal and permitting such coating metal to solidify on the film coating, and the process involving the preliminary heating of the object to be coated in a bath of heated .50.

molten metal, as previously described, are both claimed in my application filed November 5, 1907, Sr; No. 400,843, and there- 'fore are not claimed herein.

coating metalmaintained in the herein described supcrmolten condition, and thereby forming a film covering, withdrawing the object with such tilm covering thereon and contacting such film covering with a body of molten coating metal maintained near its point of solidification, and then withdrawing said object with the adhering mass of metal and permitting the coating so formed to solidify.

2. The process of producing compound surface of a body of one such metal withcoating metal maintained in the herein de scribed supermolten condition, and thereby forming a film covering,- withdrawing the object with such film covering thereon and contacting such film covering with a body of molten coating metal maintained near its point of solidification, and then withdrawing said object with the adhering mass of metal through a gage by which surplus metal is removed and permitting the coating so formed to solidify.

4C.'The process of producing compound bodies of unlike high-melting metals Welded together, which consists'in contacting a clean surface of a body of one such metal with coating metal maintained .in the herein described super-molten condition, and thereby forming a film covering, Withdrawing the object with such film'cove'ring thereon and contacting such film covering with a body of molten coating metal maintained near its lOtl point of solidification, and then withdrawingsaid object with the adhering mass of metal through a gage by which surplus metal is removed and compacting the coating so formed. I

In testimony whereof I aflix my signature, in the presence of two witnesses.

J OHN FERREOL MONNOT.

.Witnesses:

H. M. MARBLE, K. P. MoELRoY.

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