DE1521241A1 - Method and device for the production of metallic coatings - Google Patents

Description

DIPL.-PHYS. F. FINALLY - sos * unterpfaffenhofen July 1, 1965

b. MDNOHEN

PATENT ADVOCATE ,, /. _v

FLOWER STREET 5 h / AA.

TELEPHONE CRUNCHEN} 873638

TELEGRAM ADDRESS: ",

1 -CO -1 O / Λ PATENDLICH MÖNCHENI. - "'''.',

My file: 1439 \. Γ "- ^ *

Applicant: Alfred Paul Pederman, 97'i ^ Sherman Road, Chesterland, Ohio,

Method and device for the production of metallic

Coatings

The invention relates to a method and a device for applying a metallic coating to a metallic one Object, in particular an aluminum coating on a steel wire, and an object coated with aluminum Steel that can be produced with such a method and apparatus. Under "aluminum" are in this context practically pure aluminum as well as various aluminum alloys to understand », preferably those alloys that have a good electrical conductivity and / or good properties in terms of have a corrosion protection.

There are several disadvantages and disadvantages of mass-producing thick aluminum coatings on steel wires Trouble. These disadvantages and difficulties of known methods are intended to be substantially avoided by the invention by allowing a thick aluminum coating with clatter surface finish on steel in an advantageous manner should be applied. "Thick" means thicker than 0.05 mm (0.02 inches). The aluminum coating preferably adheres on the steel body with an aluminum steel intermediate 1 (igieruri.'isschicht to which is interrupted or continuous over

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the entire surface of the steel beam and which along its extension have a thickness of less than 0.02 mm (0.0007 inches). Optionally, the intermediate alloy layer can be entirely or substantially absent, and the thick aluminum coating cannot adhere firmly to the steel body, so that subsequent mechanical working and / or heat treatment is required is to reliably connect the cover to the body.

Steel wire coated with aluminum is according to the invention by an exceptionally smooth and concentric thickness Aluminum coating marked, which has a preselectable thickness.

It is therefore the object of the invention to provide a method of manufacture a steel body with a relatively thick, smooth, essentially oxide-free, corrosion-resistant, electrically conductive aluminum coating of uniform thickness. In particular a steel wire provided with an aluminum coating is to be produced, which has a relative ratio. thick, plates and Has concentric coating of aluminum. Furthermore, a method for forming a relatively thick, smooth and uniform coating of aluminum on steel. The metal coating should be applied to a metal body in such a way that that an intermediate alloy layer between the coating and the body formed in the desired manner or avoided if desired can be. Furthermore, an apparatus for producing a thick, smooth, uniform coating of metal on a Metal bodies are specified.

The invention is to be explained in more detail with the aid of the drawing. Show it:

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Fig. 1 is an axial section through a device according to the invention, with certain parts broken away, and the valve device is shown in the closed state;

2 shows an enlarged partial section through this device, wherein the valve device is open;

3 is a photomicrograph at 1350X showing a cross section of 1065 steel wire (0.65% carbon). which is provided with an aluminum coating according to the invention;

Fig. 4 is a photomicrograph at 500X showing the Figure 3 shows another cross section of the same coated wire;

Figure 5 is a photomicrograph, magnified 500X, showing a cross section of I665 steel dralite covered with aluminum under other conditions according to the invention has been overlaid;

6 is a photomicrograph at 500X showing a cross section through 1095 steel wire (0.95% carbon). which is coated with aluminum according to the invention;

Figure 7 is a graph of the thickness of the coating versus the preheat temperature for a particular non coated wire size, the wire speed and the temperature of the coating bath being selected according to the invention; and

F sharp ,. >> a photomicrograph of a cross section through a lO ^ O steel wire of ";, 25 mm (0.12. ^ inch) diameter, of one having plates, concentrically formed aluminum coating according to a method according to the invention.

The following description relates in particular to the formation of a thick aluminum coating on a solid one Steel wire with circular cross-section. Under a "thick" cover such an aluminum coating is to be understood, which is considerable

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is thicker than 0.05 mm (0.002 inches) and preferably has a cross-sectional area of at least 1 ^v jo of the total cross-section of the coated wire. This coating is considerably thicker than those coatings which can be produced by known hot dipping processes in which the aluminum has melted when the steel wire leaves the aluminum bath and only remains on the wire because of its own surface tension. Such coatings produced by dipping processes have a thickness of 0.05 mm or less. Furthermore, the aluminum coating is not essentially free of dissolved iron. An aluminum coating made in accordance with the invention is considerably thicker than a coating made by dipping processes. The thickness of this coating enables the overeogenous wire to be used for purposes other than wires of known type produced by dipping processes, for example as an electrical conductor. Furthermore, a coating according to the invention is practically free of dissolved iron.

Before the aluminum coating is applied, the steel wire is preferably cleaned thoroughly. Although the invention is not is limited to the following details of the cleaning process, the cleaning process steps below will be described in more detail be explained with which beneficial results have been obtained?

(1) The steel wire is blown with a sandblast or the like treated to remove drawing grease or the like compounds from the wire;

(2) the wire is placed in an alkaline cleaning solution in which electrolytic attack may occur;

(3) the wire is rinsed in cold tap water;

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(4) the wire is pickled in a pickling solution at a temperature between 140 and 150 ⁰ P, which is stirred by an ultrasound transducer;

(5) the stripped wire is rinsed with cold tap water; and

(6) Finally, the wire is rinsed with hot distilled or deionized water.

The cleaned steel wire is then passed through a preheating furnace guided. This furnace has an elongated tubular housing 10, the upper end of which is shown in FIG. The wire 11 extends centrally in the longitudinal direction through this housing. The housing 10 of the preheating furnace is largely free of oxygen reducing gas such as hydrogen or carbon monoxide. This gas is kept above atmospheric pressure, by pumping in a continuous flow of gas that can exit the lower end of the housing 10. The exiting Gas is preferably lit for safety reasons. A suitable heat source such as a gas burner or induction heating is provided in the vicinity of the housing 10 to the ♦ To heat wire 11 to a suitable preheating temperature, as will be explained in more detail below. A number of not shown thermocouples or optical pyrometers is provided at intervals along the length of the housing 10 to the To prove wire temperature. Furthermore, control devices (not shown) can be provided to adjust the preheating temperature of the To regulate wire.

After preheating, the steel wire 11 runs in immediately vertical direction through a casting furnace according to the invention.

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This casting furnace shown in Fig. 1 contains a cone with a rigidly arranged, essentially cup-shaped Outer shell 12 made of steel or a corresponding metal, which holds a first heat-resistant ceramic lining 13. the Liner 15 carries a substantially cup-shaped, heat-resistant one inner ceramic liner 14t in which there is a bath 15 of molten aluminum. At their lower end the inner lining 14 is offset inward and tapers down to an annular part 16 which rests on a thick metal support 17 of the casting furnace. This lower end part l6 the inner liner 14 terminates in a tapered annular shape Projection 16a, which is provided in a corresponding opening 17a in the carrier 17.

The upper end of the housing 10 of the preheating furnace is provided with a annular steel flange 18, which is connected by bolts to the lower end of a steel sleeve 19. An enlarged ring-shaped Flange 20 at the upper end of this sleeve is flush with a correspondingly formed, downward-facing recess received, which is received in the underside of the support member 17. The support member 17 has a downwardly facing annular shape Shoulder 22 at the intersection of the recesses 17a and 21, which switches coplanar with the underside of the lower projection lba inner lining of the furnace. A flat, ring-shaped, heat-resistant Washer 23 lies between the top of flange 20 and shoulder 22 and the bottom of protrusion 16a.

A refractory ceramic tip 24 extends vertically at a distance from the inner ceramic liner 14 of the Pouring furnace. A drill 25 made of stainless steel is rigidly attached to the ceramic tip 24, for example by being cast therein.

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- 7 The tube 25 extends into the sleeve 19 coaxially thereto. A number of bolts 26 hold the tube 25 in the sleeve 19. The ceramic tip 2h ends with an upwardly facing frustoconical surface 27 which forms part of a valve device of this device. The tip 2k has a central channel 28 running in the longitudinal direction, which receives the steel wire 11 in a flush but sliding manner. In a tried and tested embodiment for a 3.25 mm (0.128 ") diameter wire, the diameter of this channel was 3.53 mm (0.139").

The other part of this valve device is through a vertically arranged, annular ceramic member 29 made of heat-resistant Formed material that has a laterally inwardly turned lower end 30, which in a downwardly facing frustoconical surface 51 ends corresponding to the Surface 27 is formed and engages sealingly thereon, which is present on the upper end of the ceramic tip 21. That Member 29 has a central vertical opening 52 extending upwardly from this sealing surface 31.

The ceramic member 29 is fixed by screws 33 to the lower end of a metal shell 3h. The upper end of this sleeve is closed by an end cap 35. The end cap 35 carries two separate protruding concentric vertically arranged metal tubes 36 and 37. The annular space 3β between the outer tube 56 and the inner tube 17 communicates with a cavity or recess 39 formed in the end cap 35. A conduit 40 is in communication with the recess 39. The upper end of the inner tube 37 is at the top to atmosphere

the end cap 55 opened. The end cap itself has a number of narrow vent openings hl .

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When operating the device, a suitable gas, the

is preferably nitrogen or argon, is introduced through the line kO and flows under pressure downwards through the space between the outer and inner tubes 36 and 37, whereby the space in the ceramic member 29 and the sleeve J> k is filled. It exits to atmosphere through the open top end of inner tube 36 and through vent openings 41 in end cap 35.

The arrangement of the ceramic member 29, the metallic sleeve 34, the end cap 35, the tubes 36,37 and the line kO is provided to be movable up and down in the vertical direction, around the frustoconical sealing surface 31 on the ceramic member 29 either in sealing contact to bring with the top 27 of the ceramic tip 2k , as shown in FIG. 1, or to be provided at a distance therefrom, as shown in FIG. From this it can be seen that the ceramic members 2k and 29 together constitute a valve which controls the flow of molten aluminum from the bath 15 into the interior of the ceramic member 29.

Before the casting process, the ceramic member 29 is in its lower position, the surface 31 sealing with the upper side 27 of the tip 2k. Before molten aluminum 15 is present in the furnace, or before molten aluminum in the furnace reaches the level of the seal between the ceramic member 29 and the ceramic tip 2k , the interior of the ceramic member 29 and the sleeve 3k is vented by adding nitrogen or argon is continuously passed under pressure. When the molten alurainium bath 15 is present, the molten aluminum is prevented from flowing into the interior of the ceramic member by the sealing between the valve surfaces 27 and 27.

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The cleaned and preheated steel wire 11 is conveyed up through the channel 23 in the ceramic tip and then through the interior of the ceramic member 29 and out through the inner tube uryl through the tip of the end cap 35 · Any suitable Wire feed mechanism can be used for this purpose. The wire feed is preferably carried out with an inside narrow Tolerances regulated uniform speed,

If the coating of the steel wire with aluminum is to begin, the unit is made up of the ceramic element 29, the metallic element Sleeve 34, end cap 35, conduit 40, and tubes 36 and 37 lifted so that molten aluminum in the bath 15 between the valve surfaces 27 and 31 in the interior of the »ceramic Link 29 can flow in at the same height as in the main part of the bath. The molten aluminum poured into the member 29 is practical oxide-free, because the inflow took place from places below the level of the nauptbad 15. Although the top of the main bath 15 air and may be contaminated with oxides, there is virtually no oxide contamination in the molten aluminum below of the mirror present. The molten aluminum entering the ceramic member 29 remains oxide-free and uncontaminated, because in the member 29 a non-reactive gas is present.

When the steel wire 11 rises up out of the ceramic tip 24 and through the molten aluminum in the ceramic member 29 is moved out, it picks up a uniformly thick, concentric coating layer of aluminum which adheres to the wire and solidifies on it. The play or the sliding fit of the steel wire 11 in the channel 2b, the surface tension of the molten Aluminum and the head from the molten aluminum above the

Tip 24 with relatively low pressure practically enable no leakage of aluminum into channel 28.

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Preferably, the vertical depth of the aluminum bath above the top of the ceramic tip 2k is between about 8 and 80 ram (5/16 inches). The wire speed is in excess of Ip m per minute (50 feet per minute), and is preferably 30 m per minute (100 feet per minute) or more. With a bath depth of about 20 mm ( 5 / hour inch) and a wire speed of 30 m per minute (100 feet per minute), the steel is exposed to the molten aluminum for 0.0175 seconds.

The bath 15 is continuously or intermittently refilled by adding aluminum to the melt by the depth of the bath practically the same through which the wire must pass.

When the invention, pure aluminum as the coating metal and a steel wire with 3.25 "in (0.126 inch) diameter is used in a method according to the preheating temperature for the wire between 500 and 12oo F, preferably 650 to 1000 ⁰ F. For other Aluminum alloys as the coating metal, the preferred preheating temperature is lower because of the lower melting point of such alloys. For certain alloys, a preheating temperature of single lent 500 ⁰ F is permitted. When it is preheated to such a temperature and then immediately passed through the aluminum bath, a smooth, concentric aluminum coating solidifies on the steel wire.

At preheat temperatures above about 625 ° F, the case pure aluminum as the overlay rivet, 3.25 mm (0.128 inch) diameter steel wire, and a hydrogen atmosphere in the preheating furnace the coating with deia steel with a thin Alloy intermediate layer of steel and aluminum connected to the steel. Although this intermediate alloy layer usually does not

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continuously covers the entire surface of the steel wire, is it large enough to allow the aluminum coating to adhere properly to ensure on the steel wire, so that the coated wire can then be drawn through a wire form or can otherwise be mechanically processed or deformed, for example with the help of a roller mold.

ο Forms below about 625 F when preheated in hydrogen

however, in the case of pure aluminum as the clad metal and a steel wire of 5.25 mm (0.126 inch) in diameter, these The coating layer does not have a significant amount, and therefore the aluminum coating does not adhere firmly to the steel wire. In such In some cases, however, the aluminum coating can still be smooth and concentric, so that after a subsequent heat treatment, a Adhesion to the steel wire is achieved and the coated wire can be drawn to the desired size, the coated Wire is corrosion resistant and also has good electrical conductivity, so that it can be used for various purposes is.

When preheated in hydrogen to between about 625 and 1200 ° F, using pure aluminum as the clad metal and 3.25 mm (0.126 in) diameter steel wire, the radial thickness of this intermediate alloy layer where it is present will now be within about 0.005 ( 0.0002 inch) and 0.02 mm (0.0007 inch), and usually about 0.00 ··? (0.0003 inches). In general, the higher the preheating door, the thicker the intermediate alloy layer will be. Since the brittleness of the intermediate alloy layer increases with its thickness, its thickness should preferably be about O ₁ Oo? 0.00Q5 inches (mm) or less. Any intermediate alloy layer that may be present is so thin

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and their formation is halted so quickly that there is practically no iron in the steel wire in the aluminum bath or the deposited one Aluminum coating is dissolved.

If the alloy intermediate layer is to be as small as possible or practically avoided, carbon monoxide can preferably be used as a gas in the preheating furnace use. It is believed that carbon monoxide is oxygen from the surface of the steel wire absorbs and deposits carbon on the surface of the wire, thereby slowing down the wetting of the wire, so that the formation of the intermediate alloy layer is reduced or prevented. All other things being equal, the use leads of carbon monoxide instead of hydrogen during preheating in each case results in a substantially smaller intermediate alloy layer. If desired, both carbon monoxide and hydrogen can preferably be introduced in this order, because hydrogen reacts faster with the surface of the steel wire than carbon monoxide to the gas atmosphere in the preheating furnace to build.

In the case of a steel wire that is not completely tempered, the tensile strength of the coated wire is lower than that of the steel wire that was not originally coated. The tensile strength changes inversely with the preheating temperature, with a practically straight line dependency. For a given increase in preheat temperature, there is therefore a generally proportional decrease in the tensile strength of the coated wire. If a high tensile strength is desired, the coated wire must be retightened. Because the preheating temperature is not above 1200 F, and preferably less than IuOO ⁰ F is, however, the tensile strength of the wire is not permanently on

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decreased to an extent that its use (even after a Retightening) for various purposes that require high tensile strength, such as free-hanging cables for the transmission of electrical energy. This is very important because it is a significant practical application of the Invention is to produce aluminum-coated steel wires with high tensile strength, in which the steel wire is a Heat treatment or other treatment to give it high tensile strength prior to the aluminum coating being applied will.

Figure 7 shows a graph of the diameter of a coated wire as a function of the preheat temperature for IOSO steel wire (0.80 # carbon) with an original diameter of 3.25 mm (0.128 inch) with pure aluminum as the coating metal. The maximum coating thickness is present at around 625 ° P during preheating. At this point, the aluminum coating has a cross-sectional area of about hl% of the total cross section of the coated wire.

At temperatures below 625 ° F, the coating thickness is pure aluminum not considerably larger than this thickness. The intermediate alloy layer is almost completely absent, as it was before has been explained while the aluminum coating does not adhere very firmly to the steel wire.

At a preheating temperature of about ⁰ F Soo in the case of this particular size and composition of the steel wire of pure aluminum coating has a cross-sectional area of about 2'j ^, of the total cross-sectional area of the coated wire.

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At a preheating temperature of about 96O ⁰ F of pure aluminum coating has a cross-sectional area of about 10% of the total cross-sectional area of the coated wire.

For wires with different steel compositions and grooves, different coating bath compositions, different preheating and bath temperatures, and different times of immersion of the wire in the plating bath, the specific values of the thickness of the aluminum coating for different wire preheating temperatures differ from the values shown in FIG. However, the curve is generally similar, wherein the coating thickness is a maximum at the minimum preheating temperature at which a smooth continuous, concentric coating layer is applied, and inclines gradually at progressively higher Vorwarmtemperaturen up to about 12üü F. At substantially over 1200 ⁰ F At preheating temperatures, the aluminum coating is thin enough to be comparable with those coatings that have been produced using known hot-dip processes.

In accordance with another embodiment of the invention, using the apparatus described, lOyO steel wire (0.80% carbon) with a diameter of 3.25 n \ ai (0.12 .; inch) was preheated to 720 F and passed through a bath of pure Aluminum passed through at a temperature of 126o ° F. The bath depth was about 53 mm (15/16 inches). The immersion time was ½, 6θ6 seconds.

The applied coating was smooth and concentric, although it was

at
did not adhere strongly to the steel core. The coated wire was 5 mm (0.200 inch) in diameter such that the aluminum coating was 59 percent of the total cross-sectional area of the coated wire.

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It can be seen from this that the lower the temperature of the coating bath, the thicker the applied coating given preheating temperature.

Also, as can be seen from Figure 7, for a given bath temperature, the lower the preheat temperature, the thicker the coating is.

As the steel wire passes through the aluminum bath, almost the entire thickness of the aluminum coating solidifies on the steel wire within the first few millimeters of the wire running through the bath. The preheated steel wire acts as a heat sink and absorbs heat from the molten aluminum in the bath to allow the aluminum to solidify on the wire. The higher the temperature to which the wire is preheated, the lower the heat capacity of the wire to absorb heat from the molten aluminum, and therefore the solidified aluminum coating becomes thinner, as can be seen from FIG. 7. Within the temperature range of the preheating between about 500 and 12O) ⁰ F when the immersion time is short enough, apparently carried no substantial re-melting the verlestigten aluminum in the bath when the steel wire is heated. When the wire emerges from the bath, the coating thereon is essentially completely solidified. This is in contrast to known hot dipping processes in which the aluminum is largely still molten when the wire exits the bath, and where the molten aluminum adheres to the wire primarily because of surface tension, while solidification of the aluminum largely occurs. after the wire is led out of the bath.

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The depth of the aluminum bath along which the wire is passed does not appear to be critical in and of itself. Good results have been obtained with various immersion depths between about 8 mm (0.3 inches) and 33 mm (15/16 inches), and at wire speeds between 3.3 and 43 meters per minute (11 and one thousand feet per minute). As already mentioned, most of the aluminum appears to solidify during the first few millimeters of the wire run through the bath, so that a bath depth sufficient for this effect appears suitable. The bath depth should not be so great that the steel wire is heated so much that there is substantial remelting of the aluminum coating in the bath.

The wire speed in the aluminum bath does not appear to be critical either, if it is sufficiently high that the immersion time is not long enough for the applied aluminum coating to be significantly remelted within the bath. Favorable results have been achieved with wire speeds between 5.3 and kj> meters per minute.

The immersion time of the wire in the aluminum bath depends on the bath depth and the wire speed. Beneficial results have been obtained with immersion times between about 0.03 and 0.6 Seconds scored.

Although it is preferred that the wire surface and the If the aluminum bath is practically free of oxide at the points where the wire enters the bath, satisfactory coatings can also be obtained can be produced according to the invention in such cases when the steel is intentionally placed in a reducing before preheating Atmosphere was oxidized.

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Fig. 3 is a photomicrograph, magnified 1350 times, showing a cross section through a drill rod wire made of 1065 steel (0.65% carbon) with an aluminum coating according to of the invention. The steel wire is identified by the reference number 50. The shaded area 51 is contiguous on the steel wire 50 represents the intermediate alloy layer of steel and aluminum, while the less shaded area 52 represents the other side of the area 51 represents the aluminum coating 52. This photomicrograph shows how the intermediate alloy layer 51 reduces the surface irregularities of the steel wire 50 to complete. This wire was preheated to 60 ° F and then through passed through a 22 mm (7/6 inch) deep aluminum bath at 1 ^ 2u ° F. The wire speed through the bath was 30 meters per minute (9 ^ 1/2 feet per minute) in the accordance with the invention procedures carried out.

Figure 4 shows another photomicrograph of another portion of the wire shown in Figure 5, but magnified 500 times. The steel wire is denoted by 53, the intermediate alloy layer by 5 ^ and the aluminum coating by 55. As can be seen from this figure, the steel wire had two relatively deep indentations 56 and 57. At these indentations, the intermediate alloy layer 5h is much thinner than at other locations and, moreover, is not formed continuously. However, it extends over most of the irregular surface of the steel wire in the area of these indentations. The aluminum coating adheres firmly to the steel wire despite these surface imperfections.

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5 is a photomicrograph, magnified 500 times, showing the cross section of another aluminum clad 1065 steel drill rod wire made in accordance with the invention. The steel wire shown was preheated to a temperature of 7 ^ 0 ⁰ F and then passed through a 25 ram (1 inch) deep bath of molten aluminum at 1255 ° F at a rate of 1 m per minute (112.5 feet per minute) . In this figure, the steel wire is indicated by 98, the intermediate alloy layer by 59 and the aluminum coating by 60. Because of the lower preheating temperature, the intermediate alloy layer 59 is not appreciably discontinuous. However, the aluminum coating adhered well to the steel wire

The photomicrograph shown in Fig. 6 is 500 times Enlargement of the cross-section of a 1095 steel tubular bar wire (0.95% carbon), which is covered with an alurainium layer according to the invention was covered. The illustrated wire was preheated to 825 F and then through a 50 mm (13/16 inch) deep Molten aluminum bath passed through at 1345 F at a rate of 113 feet per minute. The steel core is with denoted by reference numeral 61, the intermediate alloy layer by 62 and the aluminum coating by 65.

Figure 5 shows the full cross-section of 1030 (0.12% carbon) steel wire, 3.25 mm (0.12 inches) in diameter, coated with aluminum in accordance with the invention. The steel wire was preheated to 025 ⁰ F in a hydrogen atmosphere and then passed through an aluminum melt of 22 mm (7/0 inch) depth at 1430 ⁰ F. The wire speed was 100 meters per minute (94 feet per minute) and the immersion time

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of the wire into the bath was 0.0 ^ 5 seconds. The steel wire is with 64, the alloy interlayer with 65 and the aluminum plating denoted by 66. This figure shows the excellent smoothness and concentricity of the aluminum coating.

However, the invention is not limited to the illustrated, preferred exemplary embodiments of the invention, since other exemplary embodiments and numerous modifications are possible according to the present circumstances. For example can the device is used to apply a metal other than aluminum to a steel or other metal body, for example for applying a copper coating to steel. Further can be used in any such process in which the alloy interlayer is to be affected or even practically eliminated Preheating atmosphere, which is completely or partially a carbon-containing gas such as Kolilenstoffmonoxyd, in an advantageous manner find use according to the invention.

Claims

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Claims (1)

- July 20 - July 1, 1965 Ε / ΑΧ My files: 1,439 patent claims 1. Steel body coated with an aluminum layer, characterized in that the aluminum coating on the steel body with an intermediate alloy layer of steel-aluminum with a thickness of less than 0.02 mm (0.0007 inch) adheres and that the aluminum coating over the intermediate alloy layer has a thickness greater than Is 0.05 mm (0.002 inches). 2. Article according to claim 1, characterized in that the aluminum coating is smooth, has a substantially uniform thickness, and is practical is free of dissolved iron. 3. Article according to claim 1 or 2, characterized in that the aluminum coating on adheres so strongly to the steel body that subsequent mechanical processing is possible. k. Steel wire coated with aluminum according to any one of the preceding claims, characterized in that the steel body is the wire core and since the aluminum coating is continuously and concentrically cast around the core. 5. With aluminum coated steel wire according to claim 4, characterized in that the aluminum coating has a cross-sectional area which is at least 7% of the total cross-sectional area of the coated wire. 9098 1 5/0853 6. A method for coating a steel body with an aluminum layer which is substantially thicker than 0.05 mni (0.002 inches), characterized in that the steel body is ^{preheated to a temperature between about 500 and 1200 0} F that the preheated steel body by a Bath of molten aluminum is passed for a period of time sufficient to form a solidified aluminum coating on the steel body, which coating has a thickness of more than 0.05 mm (0.02 inches) and that the period of time is so short that a substantial remelting of the applied aluminum coating in the bath does not occur. 7. The method according to claim 6, characterized that the aluminum coating with the steel body joined by an intermediate alloy layer that is not significantly greater than 0.02 mm (0.0007 in) thick is. 8. The method according to claim 6 or 7, characterized in that that the steel body is a wire. 9. The method according to claim S, characterized net that the steel wire through the aluminum melt with a speed greater than 15 meters per minute (50 feet per minute). 10. The method according to claim 9, characterized that the steel wire is preheated in a reducing atmosphere and into the aluminum melt occurs below the surface of the melt. 9098 15/0853 "■ '■" - 11. The method according to any one of the preceding claims, characterized in that the steel body is preheated in an atmosphere containing carbon. 12. Device for carrying out the method according to one of the preceding claims, which has a crucible for a coating molten metal, characterized in that a temperature-resistant first member extends into the crucible, which has a wire channel which leads to an outlet opening at its upper end leads that the first member has a sealing surface on the outside, which surrounds this opening, and that a hollow temperature-resistant second member extends down into the crucible and has an opening on the underside, which with the exit)! ¹ inung is aligned in the first member that the second member has a sealing surface which surrounds the lower opening and engages the sealing surface on the first member in a sealing manner to prevent the flow of molten metal from the crucible into the second member via the outlet opening in the first member to prevent the two members from being movable away from each other to separate the sealing surfaces and to permit the passage of molten metal from the crucible into the second member via the exit opening in the first member. 13. The device according to claim 11, characterized that a preheating furnace is provided through which a wire channel extends which leads to the wire channel 9 09815/0853 in the first member, and that a device for Maintain an oxygen! 'Free, non-reactive Atmosphere in the wire channels in the preheating furnace and the first link is provided. Ik. Apparatus according to claim 12, characterized in that a device for maintaining an oxygen-free, non-reactive atmosphere is provided in the second member above the liquid level of the molten metal therein. 9098 15/0853