BE599918A - - Google Patents

Description

       

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  Explosion plating process and product obtained.



   The present invention relates to a new process for plating metals. More precisely, the invention relates to a process for plating metal surfaces and in particular for plating on a metal surface one or more layers of the same metal or of another metal, as well as new crafted articles obtained thereby. process.



   The use of clad or composite metals as building materials has become common in recent years.



  These plated metals comprise a base metal, usually inexpensive, on the surface of which is plated a layer of a second metal which has certain desirable properties, for example, high corrosion or oxidation resistance, which is not possessed by not the base metal. In most cases, the plating metal

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 is much more expensive than the base metal to which it is applied. Considerable savings can thus be made by using a thin layer rather than a thick layer of the expensive metal. Of course, the economy increases dramatically when plated metals are used in the construction of large pieces of equipment such as pipelines, storage tanks and process vessels for large chemical plants.



   A second advantageous feature resulting from the use of plated metals is that the lethal which possesses the desired corrosion resistance or some other property does not have the tensile strength, the properties. thermal tees or the compressive strength necessary to allow it to be used in applications where it is subjected to certain stresses. Thus, in addition to the savings realized when using the less expensive metal, the structural strength and stiffness which this metal can impart to the composite material is an important and valuable factor in composite articles.



   In addition to the uses mentioned above for clad or composite metals, the invention applies specifically, inter alia, to X-ray installations, to cooking vessels and to decorative fittings for automobiles and buildings. for example, in many cases it is desirable to protect metals such as molybdenum, tungsten, and their alloys, which are primarily used for high temperature applications, with a layer of a heat resistant material. oxidation such as "Nichrome".



   A large number of methods exist for plating from one metal to another metal so as to form a multi-layered composite article, however, each of these methods suffers from certain drawbacks which make them disadvantageous or altogether inadequate in some cases.

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   The oldest industrial process for applying a layer of one metal to another metal is that usually referred to as "hot dipping", or in the case of zinc coatings, "galvanizing". This process essentially consists of immersing the article to be coated in a bath of molten metal for a short period of time. In order to obtain a satisfactory coating, the two metals must ally at least to some extent.

   The disadvantages of the hot dipping process are: (1) it is difficult to precisely control the thickness of the outer shell or its distribution on the surface; and (2) some metals do not alloy with others, or else form deleterious brittle phases, making it practically impossible to obtain a continuous layer with combinations of these metals.



  As a result of the difficulties associated with handling large quantities of high-melting molten metals, for example, copper, nickel, tungsten and cobalt, and the possibility of producing unwanted thermal changes in the metal Basically, the hot dipping process has been seriously limited to relatively low melting point metals.



   Another known method of applying one layer of one metal to another is electroplating. In this process, the plated article, after having been thoroughly cleaned, is immersed in a solution of a compound of the plating metal, and then an electric current is passed through the solution, the object to be plated. plate serving as cathode. In electroplating, adherent layers can be obtained, the thickness of which can be easily adjusted, and the deposited layer is generally of high purity4. However, this process is slow and expensive, and in addition the porosity of the deposited layer and the problems posed by its fragility due to the hydrogen produced impose severe limitations on the use of coatings deposited by electrolysis for a large number of applications. applications.

   In addition, the process does not readily lend itself to the deposition of alloy coatings.

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   Spray deposition is a third method of applying one layer of one metal to another, but this technique has found only limited applications due to the expensive special processes and precision of controls required. The coatings produced by this process are generally tacky, flexible and have a high degree of purity. Certain elements such as silicon, tellurium, and selenium, which are difficult to deposit by other methods, can be deposited by vaporization.



   A fourth more convenient method of plating one metal to another metal is to directly roll one metal onto another metal under hot pressure and pressure. Although different variants of this laminating cladding technique are used industrially to manufacture sheets, wires, foils! bacon and the like plated, all have some serious flaws. First, the process is limited to those metals capable of forming an effective plating under the appropriate conditions. Indeed, there are certain combinations of metals, for example, tungsten and niobium, for which none of the currently known plating processes are effective.



  Second, under the extreme temperature conditions required to achieve effective hot rolling, highly undesirable brittle intermetallic compounds are often formed or other undesirable effects such as adsorption of fragilising agents from. of the surrounding atmosphere often occur. In addition, direct rolling still has the disadvantage of requiring expensive and difficult techniques, such as welding in a gas-tight environment, inert atmospheres or vacuum, and a complicated rolling plant.



   This being the case, the object of the present invention is in particular to provide: a method for welding metal surfaces by plating;

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 a device for plating two or more metals or metal alloys to form a multi-layered composite article; plated metal articles in which the plating is impermeable, uniform and adherent, by an advantageous and economical process; clad articles of metals which heretofore could not be effectively plating welded to each other -
Other objects will emerge from the description of the invention given below.



   It has been found that the above objects are achieved by supporting a layer of plating metal parallel to a face of a metal to be plated, the inner face of the plating metal being spaced from the face of the metal to be plated; a layer of detonating explosives, having a detonation speed less than 120% of the speed of sound in the metal of the future composite article which has the highest sonic speed, is placed on the exterior face of the plating metal, and the explosive layer is then ignited.



  Usually, it is desirable to use an explosive having a detonation speed not greater than the speed of sound in the metal having the highest sonic speed, which represents the preferred embodiment of the invention. The metal layers must be separated from each other at least sufficient distance to allow the layer propelled by the explosion to reach an adequate speed before overlapping the immobile layer. A 0.001 inch (0.025 mm) gap between the faces of the two layers facing each other represents the minimum distance which has been found to be adequate. The maximum allowable distance depends entirely on the braking of the layer propelled by the air located between the layers.

   By increasing the explosive charge or by evacuating the gap between the two layers, distances greater than 0.001 inch - (0.025 mm) can be used. In general, however, a distance greater than 0.5 d

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 inch (1.27 cm) is neither beneficial nor necessary.



   In order to better understand the present invention, reference will be made to the accompanying drawings, in which: FIG. 1 is a cross section of a sandwich which can be used to practice the present invention; the F'ig. 2 is a photomicrograph (450 magnification) of a bimetallic article obtained according to the present invention; Fig. 3 is a schematic view of the phenomenon believed to occur during the process of the present invention; Fig. 4 shows a typical sandwich for the manufacture of multilayer articles.



   In Fig. 1, the metal layer to be plated is indicated as 1. Layer 1 is embedded in a support medium 5 of hard plaster cement. The veneer layer 2 is supported on top of the base layer 1 by small embossments 4 formed in the surface of the veneer 2. This provides the required gap between the two layers, indicated by 6. A layer d A detonating explosive 3 is placed on top of the plating 2 and is contiguous with it, and an allunen 7 having conductors 8 is attached to one edge of the explosive layer.



   In the photomicrograph of Fig. 2, A indicates a molybdenum base layer, B a low carbon steel cladding, and F the weld area made up of material from layers A and B.



   In Fig. 3, A represents the base metallic layer, B the metallic plating, D the explosive layer before detonation, D 'the gases produced by the detonation of the layer D, E a sharp liquid stream of material composed of the layer A and layer B which hits the underside of layer B just in front of the point of impact C, and F the material immobilized between layers A and B which welds these two layers together.



   Fig. 4 shows a sandwich for making articles with more than two layers. The metallic layer

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 that 10 which is to be clad with the metal sheets 11 and 12 rests on a plywood backing 13. The metal layers 10, 11 and 12 are separated by an interval established by tiny metal particles 14. A layer of foam tape of polystyrene or other inert material 15 covers the upper face of layer 12 in order to protect it from the direct effects of explosive layer 16. The explosive is ignited by igniter 17 attached to one of its corners. and having conductors 18.

   The explosive layer 16 may extend slightly beyond the top plating so as to provide a convenient portion for securing the igniter and to ensure that the front of the deflection has reached maximum speed upon reaching the edge of the plating. .



   The following examples represent some of the many combinations of metals which can be plating welded by the process of the present invention. They are given by way of example only and do not limit the invention in any way. Any desired composite metal article can be obtained by suitably adjusting the various conditions necessary.



  EXAMPLE 1.-
The explosive used in this example is a thin and uniform sheet of a flexible explosive composition comprising 20% very fine pentaerythritol tetranitrate (PETN), 70% red and, as binder, 10% of a 50 mixture. 50 butyl rubber and thermoplastic terpene resin ± blend of poly-
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 mothers of iormule (CloH6) 3-plnene # 7, sold commercially as "Piccolyte" S-10 (manufactured by the Pennsylvania Industrial Chemical Corporation). The composition is easily rolled into sheets and detonates at a rate of about 4,100 meters per second.



   A mild steel plate is placed; 6 by 9 inches (15 by 23 cm) and 0.5 inch (1.27 cm) thick, on a plywood board. A place and we line up a steel plate

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 6 by 9 inch (15 by 23 cm) stainless steel 0.125 inch thick (3.2mm) above the mild steel plate with the two plates spaced 0.125 inch apart from each other (3.2 mm) by rectangular steel spacers mounted at each corner. The outer face of this plate is covered with a layer of masking tape which protects the iinale surface from any deterioration. A layer of equivalent dimensions of the explosive described above having a weight per unit area of 15 g per square inch (6.45 cm) was placed on the layer of masking tape.

   An industrial linear wave generator as described in US Pat. No. 2,943,571 of July 5, 1960 is attached to one side of the rectangular explosive layer and the generator is then energized. Upon detonation of the explosive, the mild steel and stainless steel were found to be firmly and evenly welded to each other and formed a composite article. A microscopic examination reveals an excellent weld. Tests performed according to ASTM Method Specified No. A263-44T on the composite article to determine the shear strength of the weld gave an average shear strength of 73,500 pounds / square inch (5.166 Kg / cm2).

   The minimum shear strength prescribed by ASTM standards for this type of cladding is 20,000 pounds / square inch (1406 Kg / cm2) and cladding made by conventional means usually exhibits a shear strength of between 30,000 and 35,000 pounds / square inch (2,108 to 2,460 kg / cm2). The composite article can be bent 1800 around a mandrel of diameter equal to the thickness of the article without breaking.



  EXAMPLE 2.-
A 24 x 24 x 0.75 inch (61 x 61 x 1.9 cm) mild steel plate was placed on a plywood support block. Cover one side of a 24 x 24 x 0.0313 inch (61 x 61 x 0.0795 cm) type 304 stainless steel sheet with masking tape and place it, masked side up, on top.

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 the mild steel plate so that it is spaced a distance of 0.0059 inch (0.15 mm) from it by a few scattered iron powder particles which have been sifted through a n 100 mesh screen and to be retained on a n 200 mesh screen. The surface of the sliver was then completely covered with TNT grains at a rate of 5.2 g per square inch (6.45 cm 2) and at a density of 0.8 g per cm 3.

   The explosive is ignited using a No. 6 electric detonator attached to one of the corners of the explosive layer. The granular TNT layer detonates at a speed of about 4,200 meters per second. Upon detonation of the explosive layer, the resulting 24 by 24 inch (61 by 61 cm) stainless steel clad mild steel composite article exhibited properties. metallurgical tees compared to those of the sample prepared in Example 1.
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  E.JU!;!. 1PLg "1.-
A 0.25 inch thick (6.35 mm) layer of nickel was applied to a 1 inch thick (2.54 cm) mild steel plate as follows. A 6 by 9 inch (15 by 23 cm) mild steel plate was placed on a plywood support block. Sieve iron powder particles as in Example 2 were placed at certain intervals on the top face of the mild steel plate so as to establish a gap of 0.0059 inch (0.15 mm). One side of the nickel plating is covered with a protective layer of masking tape so as to protect the nickel from minor deformation to the marking of its surface by explosive force.

   The tape layer was in turn covered with a layer of the explosive composition described in Example 1, having a weight per unit area of 30 g per square inch (6.45 cm 2), and the sandwich comprising the nickel, the tape and the explosive layer on the steel plate by aligning them correctly, the nickel side facing down. Attach a No. 6 electric igniter to a corner of the explosive layer and detour the explosive. We obtain a composite article

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 mild steel and nickel, the two metal layers of which adhere perfectly to each other.



  EXAMPLE 4.-
The technique and explosive composition of Example 3 was used to prepare a molybdenum-plated 304 type stainless steel composite article. The thickness of the molybdenum layer is U.040 inch (1 mm) and that of the stainless steel 0.0625 inch (1.58 mm). The weight per unit area of the explosive layer used is 15 g per square inch (6.45 cm2) and the interval provided is 0.0059 inch (0.15 mm). one gets an excellent tackle.



  EXAMPLE 5. -
A 0.0625 inch (1.58mm) layer of copper was plated onto a 0.5 inch (1.27cm) thick mild steel plate as follows. Cover one side of the copper sheet measuring 3 by 6 inches (7.6 by 15.2 cm) with a layer of polystyrene foam 1 inch thick (2.5 cm) and cover the polystyrene layer with a layer of the explosive composition of Example 1 at a rate of 1 g per square inch (6.45 cm 2). The edges of the explosive copper-polystyrene sandwich were sealed with waterproof tape, and the sandwich was placed on the mild steel plate with the copper layer spaced 0.0138 inch apart ( 0.35 mm) of the steel layer by uniform particles of iron powder.

   The iron particles were screened through a n 45 mesh screen and retained on an n 100 mesh screen. The edges of the completed sandwich are also sealed with tape, and an electric igniter is attached to a corner of the explosive layer.



  The sandwich is then immersed in water and the explosive is ignited. Excellent adhesion of the copper to the steel plate is obtained.



  EXAMPLE 6 - The process of Example 5 is used to plating titanium

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 on copper. The dimensions of the sheets are 3 inches (7.6 cm) by b inches (15.2 cm); the titanium layer has a thickness of Soft (1.27 mm) and the copper layer has a thickness of 0.0625 inch (1.58 mm). The interval which in this case is set by the screened titanium powder particles is 0.0138 inch (0.3 (mm) and the weight of the explosive is 10 g per square inch (6.45 cm2). After detonation of the explosive, the titanium and copper sheets adhere firmly and uniformly to each other.



   EXAMPLE 7. -
A 0.050 inch (1.27 cm) layer of titanium was plated onto a 0.5 inch (1.27 cm) mild steel plate by the process described in Example 5. The dimensions of the layers were 3 inches ( 7.6 cm) by 6 inches (15.2 cm), the weight of the explosive is 15 g per square inch (6.45 cm2), and the gap is 0.0017 inch (0.04 mm) and is produced by uniform particles of iron powder (passing through a n 325 '.iesh sieve).



  The plate obtained is solid and uniform.



  EXAMPLE 8. -
The process of Example 5 was again used to apply a 0.125 inch (3.17 mm) sheet of aluminum to a 0.5 inch (1.27 cm) plate of mild steel. The sheet and plate are each 3 inches, (7.6 cm) by 6 inches (15.2 cm), the distribution of the explosive layer is 15 g per square inch (6.35 cm2), and l The interval is 0.0059 inch (0.15 mm). After detonation of the explosive, the aluminum layer is solidly probed with mild steel.



  EXAMPLE 9. -
A 0.010 inch (0.25 mm) sheet of tantalum was plated onto a 4 by 5 by 0.5 inch (10 x 12.5 x 1.27 cm) mild steel plate by the process of the example. 5. The conditions are: 0.0059 inch (0.15 mm) apart; 10 g per square inch (6.43 cm2) of explosive. An excellent plated metal is obtained.



    @

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 EXAMPLE 10, -
The process of Example 5 was used to prepare a 6 by 9 inch (15 by 23 cm) composite article composed of
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 0.0625 inch thick (1.5g) sheet of "Hastauoy Cn clad to 0.5 inch (1.27cm) mild steel plate. The explosive sheet is a slightly modified version of the composition of Example 1 and has a weight per unit area of 15 g per square inch (6.45 cm2); it contains 72% minimum; 8% binder and 20% PETN and detonates at a speed of about 4000 meters per second The expected interval between the "Hastalloy C" and the mild steel is 0.0138 inch (0.35 mm) and the ignition of the sheet of the explosive layer is achieved, in this case, by a linear wave generator.
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  EXAMPLE 11.-
A 3 by 6 inch (7.6 by 15.2 cm) composite article of the copper plated tantalum was made using the technique of Example 5. The thickness of the tantalum layer was 0.01 inch ( 0.25mm) and the thickness of the copper layer is 0.0625 inch (1.58mm). The weight of the explosive is 10 g per square inch (6.45 cm2) and the range provided is 0.059 inch (0.15 mm).
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  Exr ;, THE AT2. =
A 48 by 96 inch (1.22 by 2.44 m) stainless steel sheet was plated onto mild steel using the technique of Example 5. The explosive composition was that used in. Example 10 and this explosive returned at a rate of 12.5 g per square inch (6.45 cm2). A 0.0138 inch (0.35 mm) gap is used. The veneer is 0.0313 inch (0.795mm) thick and the base layer is 0.75 inch (19mm) thick.



  EXAMPLE 13.-
An explosive composition containing 35; of PETN, 50% of red, and 15% of the binder of Example 1 comprising butyl rubber and a terpene resin. This composition

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 also easily rolls into flexible sheets and has a detonation speed of about 5,000 meters per second. A 10 by 10 by 0.050 inch (25.4 by 25.4 by 0.127 cm) mild steel plate was drowned in a block of hard plaster cement.

   On this plate, a 10 by 10 by 0.050 inch (25.4 by 25.4 by 0.127 cm) magnesium plate is lined up; the magnesium plate having several uniform surface ridges which serve to support it at a distance of 0.020 inch (0.5 mm) above the steel plate. A layer of the same dimensions of the aforementioned explosive containing an explosive charge of 3 g / square inch (6.45 cm2) is placed on the upper face of the magnesium plate, and an electric igniter is attached. industrial n 6 on one edge of this explosive layer which is then ignited.



  Examination of the resulting composite plate shows that the two layers are firmly and uniformly welded to each other. Microscopic examination does not reveal any cracks or defects in the weld, and efforts to separate the two layers mechanically are unsuccessful.
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  EXt.l1PLF; 14. -
The process, explosive and amount of explosive described in Example 13 was used to apply a layer of 0.10 inch (0.076 mm) titanium to 0.050 inch (1.27 mm) aluminum foil. . The dimensions of the layers are 10 by 10 inches (25.4 by 25.4 cm) and the interval between them is eqt
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 0.015 inch (0.8: nom). x.rLr 15. -
A composite plate of Inconel clad mild steel was made using the process and explosive and the amount of explosive from Example 13. The steel and Inconel layers were 0.050 inches thick ( 1.27 mm) and their dimensions are 10 by 10 inches (25.4 by 25.4 cm).

   The interval between the two layers is 0.120 inch (0.5 mm).

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  F: XHaL, 16. -
A 0.001 inch (0.025mm) layer of "Nichrome" was solidly plated onto a tungsten basecoat using the process of Example 13. The explosive and amount of explosive used was that of Example 10. and the interval used is 0.003 inch (0.076 mm). The tungsten layer is 0.050 inch (1.27 mm) thick.
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  EXAMPLE 17. -
Molybdenum was plated onto tungsten using the procedure of Example 16 but replacing the tungsten layer with a 0.050 inch (1.27 mm) layer of molybdenum.
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  ExFj4pLE -18, r-
A 0.003 inch (0.076 mm) thick 90/6/4 titanium, aluminum and vanadium alloy is plated onto a 1 in 1 by 0.050 inch (2.54 by 2.54 inch) square of tungsten. over 0.127 cm) by the process described in Example 13. The gap is 0.003 inch (J, 076 mm) and the explosive and amount of explosive are those of Example 13. The weld obtained is excellent.
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 E "KeLb 19.-
A U. 007 inch (0.178 mm) layer of an 80/10/10 niobium, titanium, and molybdenum alloy was plated onto a 1 in 1 by 0.050 inch (2.54 by 2.54 inch) molybdenum sheet. over 0.127 cm) using the process and explosive of the example
13 with a 0.010 inch (0.25 mm) gap.



   EXAMPLE 20. -
A 0.100 inch (2.5 mm) thick, 1 by 4 inch (2.5 by 10 cm) molybdenum plate is placed on a steel backing plate. A 1 in 4 by 0.005 inch (2.54 by 10 x 0.0127 cm) mild steel sheet is supported directly above the molybdenum plate at a distance of 0.0025 inch (0.635 mm) by means of wrinkles in the corners of the steel sheet.



   A 1 by 4 inch (2.54 by 10 cm) layer of the explosive of Example 13 with an explosive charge of 2 g / inch - square was glued to the top face of the steel sheet. After)

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 having ignited one edge of the explosive layer, it is found that the two metals are firmly welded to each other, no cracks can be detected.
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  E.crYLE 2I. -
A sheet of titanium 6 inches wide (15.2 cm), 10 inches long (25.5 cm) and 0.008 inch thick (0.2 mm) is rolled around a cylindrical iron mandrel. with approximately 1 inch coverage. (2.54 cm). Small indentations are left in one edge of the sheet so that the two intersecting edges are separated by an air gap. A strip of the explosive of Example 13 equal in length to the foil was padded near the covering edge of the foil and one end of the tape was ignited. The titanium tube thus totehu is uniform and free from cracks or other defects. The weld has excellent mechanical strength and a metallurgical examination does not reveal any discontinuity.
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  EXl! .L "Ü '1.1'; 2 2. -
A 0.029 inch (0.74 mm) thick stainless steel sheet was applied to molybdenum and tungsten supports by the process of Example 13 using the explosive composition of Example 1. The interval is 0.015 inch (0.38 mm) in each case, the dimensions of the metal layers being 2 by 2 inches (5 by 5 cm) and the thicknesses of the molybdenum and tungsten layers being 0.039 inch. (0.99mm) and 0.021 inch (0.53mm) respectively.



  EXAMPLE 23.-
A 0.040 inch (1 mm) layer of titanium was plated over Inconel by the procedure of Example 22. The Inconel basecoat was 0.055 inch (1.40 mm) thick. The interval is 0.015 inch (0.38 mm) and the dimensions of the layers are 2 by 2 inches (5 by 5 cm). An excellent weld is obtained.



   The following examples 24 to 33 illustrate the application of the process of the present invention to obtaining plated metals.

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 multi-layered or of the "sandwich" type, that is to say having more than two layers. In each of these examples, the composition used is the composition containing 70% of minimum, 20% of PETN and 10% of binder of example EXAMPLE 24.-
A 6 by 9 by 0.5 inch (15 by 23 by 1.27 cm) Type 1015 steel plate was placed on a plywood support block. A 0.018 inch (0.457 mm) layer of copper of corresponding dimensions is placed on the steel plate and supported at a distance of 0.0059 inch (0.15 mm) from it by means of iron particles. .

   Then place a 0.0625 inch (1.58 mm) layer of stainless steel over the copper layer and also space therefrom a distance of 0.0059 inch (0.15 mm) using iron particles. The exposed top side of the stainless steel layer was covered with a protective layer of tape and then a foil of explosive having a weight distribution of g per square inch (6.45 cm 2). Attach an electric igniter to a corner of the explosive sheet and detonate the explosive. Examination of the composite plate comprising stainless steel, copper and 1015 steel shows that a firm metallurgical weld has been obtained at both interfaces. No surface deformation or distortion can be detected.



  EXAMPLE 25. -
A 6 by 9 inch (15 by 23 cm) composite article of stainless steel, copper, mild steel and jaane brass was fabricated as described in Example 24 using a gap at each interface of 0 , 0059 inch (0.15 mm) and an explosive distribution of 20 g per square inch (6.45 cm2). The thicknesses of the layers of stainless steel, copper, mild steel and yellow brass are 0.0625 inch (1.58 mm), 0.0625 inch (1.58 mm), 0.0625 inch ( 1.58mm) and 0.125 inch (3.17mm).

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  EXAMPLE 26. -
A 6 by 9 inch (15 by 23 cm) composite article was made comprising 0.0625 inch (1.58 mm) stainless steel sheet clad to 0.0313 inch (0.795 mm) aluminum foil. itself plated onto a 0.5 inch (1.27 cm) mild steel plate using the process of Example 24. The gap provided at each interface is 0.0059 inch (0. 15 mm) and the distribution of the explosive is 15 g per square inch (6.45em 'EXAMPLE 27. -
A 6 by 9 inch (15 by 23 cm) composite article comprising stainless steel, mild steel, brass, and mild steel was fabricated using the technique described in Example 24.

   The gap at each interface is 0.0059 inch (0.15 mm), the explosive distribution is 20 g per square inch (6.45 cm2) and the thickness of the layers of stainless steel, mild steel, brass and mild steel are respectively 0.0625 inch (1.58 mm), 0.012 inch (0.3 mm), 0.0313 inch (0.795 mm) and 0.5 inch (1.27 cm).



  EXAMPLE 28. -
A 6 by 9 inch composite workpiece is fabricated: (15 by 23 cm) composed of five layers comprising respectively stainless steel, mild steel, copper, mild steel and stainless steel as described in Example 24.



  The layer thicknesses are: 0.0625 inch (1.58 mm) stainless steel layers; layers of mild steel 0.012 inch (0.3 mm); copper 0.0625 inch (1.58 mm). The interval between coats is 0.0059 inch (0.15 mm) and the explosive distribution is 20 g per square inch (6.45 cm2).



  EXAMPLE 29, -
A 12 inch (30.5 cm) square shaped composite fabricated article comprising titanium, copper and stainless steel was fabricated as follows. A 0.0625 inch (1.58 mm) layer of copper is placed over a layer of stainless steel.

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 dable 0.008 inch (0.2 mm) so that it is spaced therefrom a distance of 0.029 inch (0.07 mm) by particles of iron powder (passing through a n 200.mesh screen and retained on a n 325 mesh screen). Likewise, a 0.003 inch (0.076 mm) layer of titanium is placed above the copper layer at a distance of 0.0029 inch (0.07 mm) maintained by iron particles.

   The top face of the titanium was covered with a film of polyethylene terephthalate ("Myler" polyester film made by EI du Pont de Amours and Company) 10 thousandths of an inch thick (0.25 mm), and the edges of the sandwich are sealed so as to make them watertight by applying ruoan. A sheet of the explosive, distributed in weight at a rate of 15 g per square inch (6.45 cm2) is glued on the inside face of the bottom of an open box designed to fit over all the layers metallic. The interior depth of the box is sufficient to establish a 3/4 inch (19 mm) gap between the explosive layer and the titanium layer when the box is inverted and firmly attached to the metal layers.

   An igniter is attached to a corner of the explosive sheet, the box is placed on the metal layers, the whole is immersed in water, and the alluner is detonated. The composite article formed was heated to 550 ° C. and maintained at this temperature for one minute. After cooling in air to room temperature, the composite article is folded 90 degrees around a cylindrical mandrel. No cracking or delamination occurs.
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  E, Y, L, 4PLE 30. -
The technique of Example 29 was used to prepare a 6 by 6 inch (15.2 by 15.2 cm) 16-layer laminate composed of alternating 0.005 inch (0.1 mm) layers of mild steel and 0.005 inch (0.1 mm) of austenitic stainless steel. The explosive distribution is 10 g per square inch (6.45 cm2) and the interval between each layer is 0.0059 inch (0.15 mm).

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  A 1 inch (2.5 cm) thick layer of water is used between the explosive and the top metal layer. The laminate thus obtained is uniformly welded, and no imperfection or inconsistency can be noticed.
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  E.X.t .. "1.t> I..I:! .. 31.-
A 3 by 6 inch (7.6 by 15.2 cm) composite workpiece comprising aluminum over copper over mild steel was fabricated using an explosive layer of 15 g per Soft Square (6.45 cm2) and an interval (fixed by particles of
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 dre a fer Unitermes) between each of the 0.0059 inch (0.15 mm) metal layers. A protects the upper surface of the aluminum with a 1 inch (2.5 cm) layer of foam polystyrene, the edges of the sandwich are sealed with tape, and immersed in water after which the explosive is detonated.

   The aluminum, copper and mild steel layers are 0.125 inch (3.17 mm), 0.0625 inch (1.58 mm), and 0.5 inch (1.27 cm) thick, respectively.
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 fxr.4PL1 32. -
A 4 by 5 inch (10.1 by 12.7 cm) composite workpiece comprising tantalum on copper on mild steel was fabricated by using a protective layer of foamed polystyrene and immersing the sandwich in foam. water before igniting the explosive as described in Example 31. The interval used is 0.0138 inch (0.35 mm) and the weight of the explosive is 15 g per square inch (6, 45 cm2). The thickness of the metal layers are respectively: tantalum 0, ulO inch (0.25 mm), copper 0.0625 inch (1.58 mm) and mild steel 0.5 inch (12.7 mm).
 EMI19.4
 



  EJ \ .I! .1'1J: '. LE 33.-
The explosive composition of Example 1 was used to prepare a 3 by 6 inch (7.6 by 15.2 cm) composite article comprising silver on mild steel. The explosive distribution is 12.5 grains (810 mg) per square inch (6.45 cm2) and the technique described in Example 29 is used to place

 <Desc / Clms Page number 20>

 a 1/4 inch (6.35 mm) layer of water between the explosive layer and the silver. A 0.032g inch (0.833mm) gap is established between the steel and the silver using iron powder particles (passing through a 20 mesh n screen and retained on a 45 n screen) and igniting the explosive using a linear wave generator.



   Without any intention of limiting the present invention by any theory of operation, it is believed that the solder phenomenon described above can be attributed to a "jet" action which occurs, as shown schematically in FIG. 3. When the explosive layer is ignited, the detonation. progresses throughout the explosive layer at the rate of detonation of the explosive composition. The pressures produced by the detonation thus act progressively on the plating layer to propel it towards the material to be plated.

   If the metal plating is parallel to the surface of the metal to be plated, the part of the plating closest to the ignition point (s) makes contact with the surface of the metal to be plated while other parts are either stationary or en route to. the surface (see Fig. 3).



  If the conditions are suitable, a "jet" is obtained composed of the surface layers of the two metals, this jet being directed in the still unoccupied gap between the layer of the plating metal and the surface of the metal to be plated. The jet material is recirculated to produce an intimate mixture of the two metals.



    Removal of the surface metal layers and high pressure melting of the previously underlying metal layer provides the desired weld.



   An effective weld is not valued if the plating metal strikes the surface of the metal to be plated while moving roughly in a direction generally perpendicular to the latter.



  These conditions prevail in the case of parallel metallic layers in which a layer is driven by an explosive which is ignited substantially simultaneously over its entire surface, for example by a plane wave generator, or if a charge

 <Desc / Clms Page number 21>

 explosive is placed at a substantial distance, that is, more than a few centimeters from the plating layer and the pressure is transmitted by a relatively dense agent. In the latter case, the interval between the layers has the effect of making the ignition approximately simultaneous over the entire surface.



   In order to achieve the desired result, an explosive layer must be ignited so that the detonation propagates parallel to the plating layer. Of course, the dimensions of the explosive layer must correspond to the dimensions of the surface to be plated.



   An essential and critical feature of the present invention is the use of an explosive having a detonation speed not greater than about 120% of the speed of sound in the metal of the system having the higher sonic speed 1p. By "metal" in the foregoing discussion is meant a metallic element or a layer of the plating system which, in any case, can be an elemental metal or a mixture of elemental metals, ie. that is, an alloy. When the rate of detonation of the explosive exceeds this limitation, oblique shock waves frequently form which eliminate the above-mentioned "jet" phenomenon and prevent the formation of a good metal-to-metal weld.

   Likewise, in cases where a jet forms, pronounced side effects often arise such as deformation of the plates and cracking of the plating layer.



   Although several laws have been mentioned above of the "speed of sound" and the "sonic speed" of metals, scholars are well aware that these terms can be interpreted in slightly different ways depending on the circumstances. For example, these dulls have a different meaning for the physicist when it comes to plastic shock wave phenomena in solids as opposed to elastic shock wave phenomena. These are the first phenomena to which the present invention relates.

   The; terms "speed of sound" and "sonic speed" used in this same! -

 <Desc / Clms Page number 22>

 In conjunction with metals and metal systems, we are concerned with the speed of the plastic shock wave which is formed when a stress which is applied just exceeds the elastic limit for one-dimensional compression of the particular metal or metal system in question. The value of this sonic velocity can be obtained by means of the relation
 EMI22.1
 where "V" is the sonic speed in cm / second: "K" is the adiabatic mass modulus in dynes / cm2; and "d" is the density in g / cm3.



  Values of "K" can be obtained from values of Young's modulus "E" and beverage ratio "#" by means of the relation
K = E / (1-2 #) The values of "d" and "K" or of "E" and "#" can be easily found in the literature (see for example the "American Institute of Physics Handbook, McGraw-Hill, New York, 1957).



   Alternatively, the sonic velocity can be calculated from the published values of the plastic shock wave velocity - as a function of the particle velocity imparted to the metal by the shock wave as described by RG McQueen and SP Marsh, Journal of Applied Physics 31 (7), 1253 (1960).



   In cases where the literature does not provide any data, values of "V" can be obtained by performing shock wave measurements described by R.G. McQueen and S.P. Marsh supra) and in references cited by them. Alternatively, "V" can be calculated from the relation
 EMI22.2
 where "CL" is the speed of elastic compression waves and "Cs" is the speed of elastic shear waves in metal. The required elastic wave speeds can be measured by well known methods.

   For representative purposes, the sonic velocity values used in this brief for some representative metals are given in the following table:

 <Desc / Clms Page number 23>

 
 EMI23.1
 
<tb> Metal <SEP> 1 = se <SEP> of <SEP> sound <SEP> in <SEP> meters <SEP> seconds
<tb>
<tb>
<tb>
<tb>
<tb> Zinc <SEP> 3.000
<tb>
<tb>
<tb>
<tb> Copper <SEP> 4.000
<tb>
<tb>
<tb> Magnesium <SEP> 4. <SEP> 500
<tb>
<tb>
<tb> Niobium <SEP> 4.500
<tb>
<tb>
<tb>
<tb> Stainless steel <SEP>
<tb>
<tb>
<tb> - <SEP> austenitic <SEP> 4. <SEP> 500
<tb>
<tb>
<tb> Nickel <SEP> 4. <SEP> 700
<tb>
<tb>
<tb> Titanium <SEP> 4.800
<tb>
<tb>
<tb> Iron <SEP> 4.800
<tb>
<tb>
<tb>
<tb> Molybdenum <SEP> 5.

   <SEP> 200 <SEP>
<tb>
<tb>
<tb> Aluminum <SEP> 5.500
<tb>
 
 EMI23.2
 In addition to the maximum limit imposed on the rate of detonation of the explosive used, it has been found that the latter must have a minimum speed of d4t = .. tion of less than about 1200 meters per second. Explosive shots which detonate at a speed lower than: -. #minimum speed often does not manage to develop the energy n -: .- esssire to bend the "jet" postulated above, and are thus 4 -, i-able to firmly weld metals as required by present invention.



  As the yrent examples show, is the new plating soldering process applicable to a wide variety of metals such as aluminum, uminium = steel, iron, titanium, niobium, chromium, copper, gold, copper cobalt, =: '1ickel, beryllium, magnesium, molybdenum, tungsten or tantalum, vanadium, zirconium, silver, platinum, copper, 1- $ gold and their alloys as well as other metals are very difficult to ply weld by any of the conventional techniques. Each of the different: = ches can be in a single metal or in alloys of two ne. re-- several individual metals or one or the other of the layers pe5nVtre a composite set of two or more urf:; ies.



  The process is not suitable for fabricating plates or flat sheets, but rather, as shown in example 21, tubes and other articles from difficult material. welding. In industry, 1 = zche de ase is usually a piece of equipment where the plating layer has to be attached. Generally, the resistance of the plating weld

 <Desc / Clms Page number 24>

 is greater than the tensile strength of the lower metal.



  The ductility of the plating welded material is also comparable to that of unwelded layers and can often be increased by medium heat treatment.



   An exceptionally surprising and advantageous feature of the new clad systems of the present invention is that the continuous weld zone connecting the two layers can have a homogeneous composition throughout its extent. In conventional plating processes, the welded area consists of a series of layered compositions which are progressively richer in metal than the layer which is closest to each other and conversely, progressively lower in metal than. the furthest layer. the following example illustrates this aspect of the present invent.on.



  EXAMPLE 34. -
A series of 26 nickel-on-copper plate metals was made using the explosive of Example 1 at a rate of 5 per square inch (6.45 cm2), the interval between the nickel and copper layers being imperceptibly modified by 0.0017 to 0.160 inch (0.043 to 4 mm). The explosive sheet is spaced 1/4 inch (6.35 mm) from the plating layer and the gap is filled with water according to the technique described in Example 29. Metal layers measure 4 by 4 by 0.021 inch (10 by 10 by 0.53 mm).



  Subsequent X-ray diffraction studies carried out on the thrown area of each = plate show that in each case a cubic structure with identical centered faces is obtained. The structure parameter obtained for the discarded material is 3.575 + - 0.003.A. regardless of the interval used and the part of the discarded area examined. A composition of copper and nickel having a structure parameter of 3.575 A contains 33% nickel and 67% copper.



   The method used to establish the required interval between metal layers is not critical. As the drawings show, dt. tiny metal particles interspersed between

 <Desc / Clms Page number 25>

 the layers give complete satisfaction. Likewise, this small protrusions in the surface of the upper layer or on the surface of the lower layer can be used. The support device obviously cannot mask large areas of the metal superstraces if these areas are to be welded by plating.



   It is desirable that the metals be relatively free from surface impurities. When surfaces are not clean, a surface cleaning treatment with a medium abrasive followed by washing with a solvent is suitable: to remove any impurities which would destroy the adhesion or produce fragile areas. However, the intense and complicated cleaning operations required for other plating processes are not required for the process of the present invention.



   The rigid support device for the base layer is not critical in the practice of the present invention; however, the presence of a support agent helps to avoid deformation of the shaped assembly. Plywood, owing to its low cost price, represents a satisfactory support material.



   As has been shown in the foregoing examples, it is advantageous in certain cases to provide an inert or damping material such as polyester films, water, or a thin layer of tape between the explosive layer. and the surf ace of the plating metal to help maintain a smooth, uncontaminated surface.



   The explosive layer can be ignited by any conventional igniting device, for example, a detonator, detonating capsule, explosive wires, etc. The location of the ignition source on the explosive layer is not critical for- since the whole layer is not lit simultaneously. Thus, the ignition source can be located at a corner, which is preferable because of the larger welded surface it provides.

 <Desc / Clms Page number 26>

 along one edge, or in the center of the explosive layer, or alternatively several ignition sources or a wave generator; Linear can be used to light an entire oord of the layer simultaneously.

   The amount of explosive used is not critical as long as a sufficient charge is present to propel the layers at an adequate rate to achieve the desired plating weld. The particular amount and charge of the explosives suitable in any given case will be readily apparent to those skilled in the art by considering such factors as the type of explosive, the thickness of the metal layer, etc. Obviously, excess explosive. produces unwanted distortion and should be avoided.



   Obviously, if desired, in order to conserve the required quantity of explosive, a plating assembly can be placed on both sides of the explosive layer. Thus, two plated metals can be ootained in a single operation.



   Although the invention has been described in detail in the foregoing description given, by way of example, with reference to the examples and to the appended drawings, it is clear that it is in no way limited thereto but that many changes and modifications can be made without departing from its scope.


    

Claims (1)

R E V E N D I C A T I O N S. ----------------------------- 1. A method of plating weld together of metal layers to form a multi-layered body, characterized in that a metal plating layer is supported at a distance of at least 0.001 inch (0.025). mm) of a base metal layer and substantially parallel to it, a layer of a detonating explosive is placed on the outer face of one of the layers, this explosive having a detonation speed less than 120% of the speed of sound in the metal of the system having the highest sonic speed, and the explosive is ignited so that the detonation propagates in a direction parallel to the metal layers. <Desc / Clms Page number 27> 2. A process for plating metal layers together to form a multilayer body, characterized in that at least one metal layer is supported at a distance of at least 0.001 inch (0.025 mm) d 'a base metallic layer and substantially parallel to this, a layer of corresponding dimensions of an explosive having a detonation rate less than the maximum sonic velocity of either metal is placed on it. the outer face of one of the layers and the explosive is ignited so that the detonation propagates in a direction parallel to the metal layers. 3. method for welding together by plating metal layers, characterized in that at least one metal layer is supported in a substantially parallel manner, separated from a second metal layer by an interval of at least 0.001 inch (0.025 mm), a layer of a detonating explosive is placed on the face of one of the layers, this explosive having a detonation speed not greater than about 120% of the speed of sound in the metal of the system having the highest sonic speed, this explosive being present in sufficient quantity to propel the adjacent metal layer in the gap between the stumps during the detonation of the explosive without appreciably deforming one or the other metal layer, and igniting the explosive whereby the detonation propagates in a direction parallel to the metallic layers so that the layer which is propelled is driven out of the center of the surface of the other layer and is firmly welded to it. 4. Method according to claim 1, characterized in that the supported layer rests on projections provided on its surface. 5. Method according to claim 1, characterized in that the support is provided by metal particles of relatively uniform dimensions. 6. Method according to claim 1, characterized in that the cladding layer and the base layer are formed <Desc / Clms Page number 28> by the ends of a sheet made of a single metal which overlap each other, which makes it possible to obtain a container structure. 7. Method according to claim 1, characterized in that the metals forming the metal layers are chosen from the group consisting of iron, titanium, aluminum, niobium, tantalum, chromium, cobalt, nickel, molybdenum, beryllium, tungsten, magnesium. , copper, vanadium, zirconium, silver, platinum, gold and their alloys. 8. Process according to claim 1, characterized in that the re ultant multilayer body receives a milking. when hot it restores its ductility. 9. rocéd according to claim 1, characterized in that a layer of damping material is interposed between the explosive layer and the adjacent metal layer. 10. Multi-layered fabricated article, characterized in that it comprises a first metallic layer firmly welded to a second metallic layer ... by an intermediate layer comprising a homogeneous alloy of the metal of the first layer and the metal of the first layer. second layer. 11. A multi-layered article according to claim 10, characterized in that the first layer is copper and the second nickel. 12. The multiple layered article of the claim, characterized in that the first layer is stainless steel and the second is mild steel. 13. Multiple-layer fabricated article according to claim 10, characterized in that the first layer is nickel and the second is mild steel. 14. A multilayer fabricated article according to claim 10, characterized in that the first layer is molybdenum and the second is steel. stainless. 15. Multi-layered article according to claim 10, characterized in that -The first layer is of the following and the second of mild steel. .. <Desc / Clms Page number 29> 16. Multilayer openwork article according to claim 10, characterized in that the first layer is titanium and the second is copper. 17. Multilayer fabricated article according to claim 10, characterized in that the first layer is titanium and the second is mild steel. 18. A multilayer fabricated article according to claim 10, characterized in that the first layer is aluminum and the second is mild steel. 19. A multilayer fabricated article according to claim 10, characterized in that the first layer is tantalum and the second is mild steel. 20. A multilayer fabricated article according to claim 10, characterized in that the first layer is magnesium and the second layer is mild steel. 21. The following multilayer fabricated article, claim 10, characterized in that the first layer is titanium and the second is aluminum. 22. A multilayer fabricated article according to claim 10, characterized in that the first layer is Inconel and the second is mild steel. 23. A multi-conchwork article according to claim 10, characterized in that the first layer is Nichrome and the second is tungsten. 24. A multilayer fabricated article according to claim 10 characterized in that the first layer is Nichrome and the second is molybdenum. 25. A multi-layered article of manufacture according to claim 10, characterized in that the first layer is an alloy of herbal tea, aluminum and vanadium and the second is tungsten. 26. Multi-layered article following the re- <Desc / Clms Page number 30> vendication 10, characterized in that the first layer is an alloy of niobium, titanium and molybdenum and the second is molybdenum. 27. A multi-layered article of manufacture according to claim 10, characterized in that the first layer is molybdenum and the second is molybdenum. 28. A multilayer fabricated article according to claim 10, characterized in that the first layer is titanium and the second is also titanium. 29. A multilayer fabricated article according to claim 10, characterized in that the first layer is stainless steel and the second is tungsten. 30. Multi-layered fabricated article follows claim 1a, characterized in that the first layer is titanium and the second is Inconel. 31. A multi-layered article according to claim 10, characterized in that the first strain is silver and the second is mild steel. 32. A multilayer fabricated article according to claim 10, characterized in that the first layer is tantalum and the second is copper. 3. Multi-layered fabricated article, characterized in that it comprises a plurality of metallic layers firmly bonded to each other by a plating solder material of homogeneous composition, this material comprising an alloy of the metals of the layers which 'she welds one to the other.