US1156170A - Alloy-surfaced wire and process of producing the same. - Google Patents

Description

W. M. PAGE.

ALLOY SURFACED WIRE AND PROCESS OF PRODUCING THE SAME..

APPLICATION FILED 11111.21. 1910.

11,156,170. Patented 001121915.

,WILLIAM MARSHALL PAGE, OF PHILADELPHIA, PENNSYLVANIA.

ALLOY-SURFAGED WIRE AND PROCESS OF PRODUCING THE SAME.

fipecification of Letters Patent.

Patented Oct. 12, 19 15.

Application filed January 21, 1910. Serial No. 539,289.

To all whom it may concern:

Be it known that I, WILLIAM MARSHALL PAGE, a citizen of the United States, residing atlhila'delphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Alloy-Surfaced Wire and Processes of Producing the Same, of which the following is a specification.

This invention relates to alloy surfaced wire and processes of producing the same; and it comprises a wire of ferrous metal carrying a welded-on homogeneous, nonporous surface or coating of an electrically indifferent alloy of copper and ferrous metal; and it alsocomprises a method of,

producing such wire which embraces the steps of preparing the surface of a wire to receive an alloy coat and thereafter passing such wire through an alloying bath comprising copper under such thermal and other conditions as to produce a tenuous coating of a ferrous metal containing copper firmly united to its surface; all as more fully hereinafter set forth and as claimed.

The problem of protecting the corrodible surfaces of iron, steel, alloy steels, and other ferrous metals from corrosion is a diflicult one and particularly in the case of wire which must be exposed to atmosphericconditions. Such wire is frequently tinned or galvanized, that is, it is covered with a coating of tin or zinc or their alloys. Zinc protects the iron for the reason that it is electropositive thereto, corroding before iron does. In use, also, a galvanized wire becomes covered with a thin impervious coating of zinc oxid which prevents further attack upon the zinc under many conditions. But where, as frequently happens under urban conditions, the wire is exposed to smoke and gases containing free acids capable of forming soluble zinc salts, the protective coating of zinc oxid cannot form and the zinc dissolves away until the iron or an ironzinc alloy is left bare, whereupon corrosion ensues. Tin being electronegative to iron protects it only in so far as it forms a hermetic sealing therefor and where cracks L flaws allow access of corrosive agents to the underlying iron, the corrosion of the iron is much more rapid in the presence of tin than in its absence. Copper, where existing as a continuous dense poreless coating, forms va better protection for ferrous metals but it is diflicult to cause it to cohere to H011 or steel by ordinary dip coating methods, though a good cohering welded-0n dense and poreless coating may be secured by the, use of sundryexpedients (see Patent 853,716). Unless the coating be thus denseand poreless, however, copper is not a good coating for wlre and other metals to be exposed to I the weather since copper is extremely electronegative to iron, forming a powerful galvanic couple therewith and very much hastening the oxidation of the iron. Electrocoatings of copper are always porous and are therefore of no. service on metal to be exposed to the weather. Where copper is used as a coating for iron and steel, there must be no line or seam of non-union between the joined metals or any pore or crevice through whichcorrosive agents can gain access to the metal below.- And while continuous poreless coheringwelded-on coatings of copper of substantial thickness can be attached to steel as by the methods of Patent 858,716, it is commercially desirable for such cheap purposes as fence wire and the like to provide a thinner coating which shall be cheaper than pure copper and shall be easily and economically applied.

In the present invention a new type of protected ferrous metal wire is provided, the iron carrying a coating which, like copper, is substantially incorrodible but unlike copper, zinc and tin, is substantially neutral or indifferent toward the iron in an electrical sense. I have found that by suitable methods of treatment I can produce alloys of iron and copper which are substantially non-corrodible, like copper, .but whichain contact with iron do'not .form a couple therewith, standing at about the same place in the galvanic scale asiron or steel and of these alloys I can provide iron, steel, and

other ferrous metals with an economical, thin coating which is weather resistant and which while shielding the iron mechanically 40 V heating the wire oxidized in this manner,

- so high a temperature.

, oxidizing such wire either does not promote its corrosion electrically. Such a coating may be provided in several ways. One way is to thoroughly clean the surface of the wire to be treated, as by pickling and Washing, and then through a superheated molten bath of a copper-iron alloy of the correct composition, the wire being protected from oxidation prior to entering the copper iron alloy bath and on withdrawal therefrom whilestill heated. This protection may be afforded by the use of a tubular conduit filled with producer gas. While steel and pure copper have substantially no tendency to unite to form any permanent union under ordinary conditions at the melting or ordinary casting temperature of 00 per and require a much greater degree 0 heat (such plication Serial No. 467,651, filed Dec. 15,.

1908, Patent No. 1,066,312. In operating in this manner, the iron or steel wire to be coated may. be first thoroughly cleansed by pickling and washing to produce a true metallic surface'and then carried through an atmosphere {of superheated steam. steam treatment produces a thin firmly cohering coat of oxid upon the ferrous metal; this oxid probably being some variety of.

the magnetic oxid of iron.- Upon now as by passing it into molten copper, the oxid which is in cohering contact with the underlymg, more or less carbonaceous metal, is

reduced at the expense of the superficial carbon of the steel giving oxids of carbon which escape as gases and forming a thin layer of pure iron, such iron coming both from the oxid and from the underlying metal which has been robbed of its carbon. This pure carbonless iron, unlike the commercial carbonaceous metal, such as steel, has a fairly strong tendency to alloy and unite with copper. A pure iron layer on the surface of the wire may be produced inby superficially in the way described or in any other manner, and then reducing by heating in producer gas; but

other ways, as for example,

these other methods of producing the pure iron are not so simple and economical as that just stated, and I therefore regard the described steam treatment as particularly advantageous. The pure iron produced by the pass it This I macaw reduction of ordinary rust or oxid of iron in producer gas is loose-textured and does not .cohere with the underlying metal as thoroughly as is desirable. Instead of being integral with the underlying metal it is more or less discrete therefrom. The preliminary pickling and washing may be omitted, since scale and oxid tend to crack ofi' in the steaming and other treatments, but such pickling and washing are advantageous as securing greater uniformity of product. Any particle of scale or oxid which may remain on the iron or steel and does not crack ofi', will of course form a flaw in the final product. The wire after having its surface decarbonized, on being passed through a bath of pure molten copper of the proper temperature and with the right time of contact therewith, will form a clinging and cohering layer of copper-iron alloy upon its surface of the proper composition for the present purposes. It is advantageous however to use a directly produced, alloy of iron and copper for coating as this unites more readily with the wire and there is greater certainty as to the composition of the coating. This is particularly the -case where the surface of the wire has not been decarbonized. The copper-iron alloy 'may be made of the requisite composition and directly melted. Or, and more simply, a mass of copper containing iron may be kept in a' molten condition in a suitable furnace by the heat of a' suitable flame and the iron in the copper replenished from time to time by dissolving copper-clad iron scrap or iron therein. Some iron is dissolved fromthe wireby the bath but with molten copper in an internally heated furnace, more iron will generally burn out than is furnishedby solution fromthe wire during the passage of the copper so that resuch wire through plenishment of the dissolved iron is necessary. The oxidation of the iron in the copper may be retarded'to some extent by floatf ing carbon, such as charcoal or coke, on the surface of the copper, but as thewcarbon forms carbon 'monoxid and carbon dioxid, both of which have an oxidizing influence upon iron, the presence of the carbon merely retards the oxidation of the iron Without preventing it. When decarbonized wire having a surface of pure iron is employed, the

- presence of any amount of dissolved iron in the copper is not necessary since the pure soft iron on the surface will form the requisite alloys directly. In the wire thus produced, there are generally several alloys in the surface coating, an alloy rich in'iron existingnext the iron and carrying 6 to 7 per cent. of copper while the exterior layer is composed of an alloy containing relatively little iron, down to six or seven per cent. of iron. Both of these alloys have the desiredthe copper fora period of time necessary to give the desired alloy coating. VVh-ile the wire may be introduced into the copper on a catenary curve, since iron is somewhat lighter than copper this is usually not positive enough for certainly producing the desired amount of immersion and it is better to use specific hold-down means. For this purpose iron rollers carrying a protective coating of a crucible mixture or the like may be kept floating on the surface of the copper. After going through the bath the wire is best passed through a die to scrape off the superfluous alloy and thereafter given a final pass through a wire drawing die to reduce it one or two sizes. This final pass compacts the coating and gives it a better surface. It is best to interpose an idle roller between the coating furnace and the reducing die in order to allow the exertion of a drawing ten-'- sion on thewire without disturbing its relation to the alloying bath. \Vith wire thus produced a cross section upon polishing and etching shows layers of different copper-iron alloys directly, firmly, and permanently attached to the steel. The wireafter the treatment may be suitably heat treated to give it any desired tensile strength. The melting temperature of copper and copper-iron alloys beingrelatively high, heat treatment at a high temperature to improve the quality of the steel is practicable. This is not possible in the case of zinc coated or tin coated wire, in both of which the coating metal is too low melting to permit suitable heat treatment. In the ordinary galvanizing and tinning, the steel of the wire is annealed and weakened by the treatment itself and there is no opportunity of restoring the strength to the core since subsequent heating would melt off the coating.

In the accompanying illustration I have shown, more or less diagrammatically, certain embodiments of apparatus elements useful in performing the described invention.

In this showing :Figure 1 is a vertical section of a typical apparatus for use in the .present invention; Fig. 2 is a horizontal secers which consist of an iron core 4, surrounded by a suitable jacket of a crucible mixture or the like to prevent any action of the iron upon the copper. At their ends these rollers are mounted between vertical flanges or guides 6 in the side walls of the furnace, permitting an up and down. movement of the rollers with changes in the level of the molten copper while retaining such rollers in a fixed position otherwise. Flue 7 communicates with down take 8 and leads the Waste furnace gas to a suitable stack (not shown). At one end of the furnace chamber is mounted a conduit 9 through which streaming steam or producer gas may be transmitted from a source not shown. This conduit extends somewhat (within the furnace chamber to allow it to become heat- .past the'smoothing die 13, thence through the" second named conduit over another reel 14 to the reducing die 15 and thence over the coiling or tension producing reel 16. This die is not shown heated since copper iron alloys exposed to air work better cold than hot. In the showing of Fig. 3, 17 represents an iron or steel core; 18, a layer of iron copper alloy, rich in iron; and 19, an iron copper alloy rich in copper. These three layers merge insensibly into each other, but for convenience of illustration, they have been shown as more or less discrete. The use of this structure in performing the described process may be easily seen. The wire 12, which may have been previously pickled, is passed'through conduit 9, through which streaming steam is passing. At the high temperature of the conduit, this steam reacts with the iron and covers it with a thin, cohering coating of magnetic oxid, having the function in this process already described. This treated wire passes through the copper or copper iron bath, being held submerged therein by the weight of the rollers. Passing out of the bath, any excess of copper which may be on the exterior of the wire is wiped off by die 13. If copper itself is used in the bath, this" leaves an alloy surface exposed. The gas or the-steam in 10 serves to cool the wire while protecting it from oxidation. Steam has no fact dissolved oxygen and dissolved iron passes through die 15 under the tension given by reel 16, receiving a smoothing and reducing pass. In this pass it is generally better to reduce the wire'one or two gages, as thismaterially compacts and hardens the coating. Wire of nickel and other ironlike metals may be similarly treated. The

process is a plicable to' all steels, whether ordinary car on steels or the so-called alloysteels. Rods, bars and other shapes may be given an alloy coating in the same manner as wire though other forms of dipping apparatus will be required. 7

The time of passage of the wire through the bath mustobviously be so regulated as to prevent toomuch permeation of the iron by copper-iron alloys; this being practically necessary sincethe bath is preferably kept rather hot. By the use of a hot, freely liquid bath of copper or copper-iron alloy not only is the alloying of the surface of the wire facilitated and the decarbonization of the iron permitted but no excess of cupriferous metal over and above the amount necessary for the desired alloy-surfacing, will remain clinging thereto,-the excess flowing back. I

Where the steam oxidation is omitted the same result in producing the alloy-facilitating superficial decarbonization may be efi'ected by another expedient. The wire is made clean-surfaced by a thorough pickling, which should be with acid producing volatile iron compounds, such as hydrochloric orhydrofiuoric acid and the copper is kept in a condition which may be described as underpoled; that is, so that it contains dissolved and combined oxygen. In a rever beratory furnace there is generally no trouble in maintaining plenty of oxygen in the copper where copper, as distinguished from an iron-copper alloy, is used. In passing the clean-surfaced wire through the oxygen-containing copper, the oxygen reacts with the superficial carbon of the wire, producing gaseous oxids of carbon and leaving pure iron on the surface with which the copper readily combines and alloys, no very high temperature being requisite for such a combination of copper with pure iren. In

this operation no iron should occur in solution in the copper though as a matter of cannot coexist in molten copper. The oxidation of carbon being preferential over that of iron, by a proper regulation of conditions the carbon may be removed leaving pure iron. With hot freely fluid copper any slight amount of iron oxid produced however will do no harm since it will rise and float. The steam-treated wire may also be passed through oxygen-containing copper,

though such copper is not necessary here since the magnetic oxid on the iron furnishes all the oxygen necessary to produce the desired amount of superficial pure iron.

In using clean, metallic surfaced wire, the conduit 9 may be kept charged with producer gas to preserve the metallic surface. The gas will flow into the furnace through the open end of the tube burning harmlessly and serving to heat the wire passing through the flame.

1. In the manufacture of protected steel wire, the process which comprises passing steel wire through a molten bath comprising copper under circumstances permitting the format-ion of a cohering surface coat consisting of an iron-copper alloy and removing the excess of coating metal.

2. In the manufacture I of protected steel wire, the process which comprises passing steel wire through a molten. bath comprising copper under circumstances permitting the removal of the superficial carbon of the steel and the formation of a cohering coat consisting of iron-copper alloy.

3. In the manufacture of protected steel wire, t-he process. which comprises passing steel wire through a molten bath comprising copper under circumstances permitting the removal of the superficial carbon of the steel and the formation of a cohering coat consisting of iron-copper alloy, and removing the excess of coating metal.

4. In the manufacture of protected steel wire, the process which comprises oxidizing the surface of a steel wire, re-reducing such surface to form superficial pure lI'OIl and producing a thin cohering surface coating consisting of iron-copper alloy with such superficial pure iron.

5. In the manufacture of protected wire, the process which comprises removing the superficial carbon of steel wire byoxidation and thereafter producing a thin, cohering surface layer consisting of copper-iron alloy on the decarbonized surface.

6. In the manufacture of protected steel wire, the process which comprises removing the superficial carbon of the steel in a molten bath comprising copper, forming a cohering surface coating consisting of an iron-copper alloy on the decarbonized surface and removing the excess of coating metal.

7. In the manufacture of protected steel wire, the process which comprises oxidizing the surface of a steel wire by a treatment with superheated steam, passing the oxi diz'ed Wire through a molten bath comprising copper to cause the oxid to react with underlying carbon and form superficial pure iron alloying with such copper to form a cohering copper-iron alloy and removing the excess of coating metal. 4

8. As a new article of manufacture, a steel article covered with a thin, cohering", dense,

impervious surface coating consisting of In te:.;timony whereof, I afiix my signalcopper-n-on alloy galvanlcnlly neutral to ture m the presence of wltnesses.

such steel- W II TIAM MAR HALL PXGE 9. As a new article of manufacture, a steel V J J S \vn'e cm'rylng :1 H1111, dense, eohermg, 1m- W ltnessesz pervlous coatmg conslstmg 0f copper-11 011 1. M. WVE'Is,

alloy galvanically neutral to such steel. 1. J. Swmmmn

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