JP2004518558A - Metallurgically bonded layered article with curved surface - Google Patents

Abstract

A layered article having a curved surface made of a supporting metal metallurgically bonded to a supported metal.

Description

[0001]
(Field of the Invention)
The present invention is in the field of shaped layered articles of the same or different metals.
[0002]
(Background of the Invention)
Where a single metal does not meet the physical, chemical, or economic requirements of an application, multiple layers, especially two layers, of metal articles are used. Examples of such articles are containers that must be corrosion resistant or chemically inert, such as heat exchanger tubes in corrosive use. Metals meeting these requirements, such as copper, gold, or platinum, may have insufficient strength or may be too expensive to use alone. Combining these metals with a stronger or less expensive metal layer, such as steel, is one way to provide strength or reduce costs. Various methods of joining such layers have been developed. The suitability of these methods depends on the application that will be imposed on the article. Especially for wide range of high temperature applications, the demands on interlayer bonding are severe.
[0003]
One of the more common methods of combining metal layers is to use a loose liner, ie, a lining or insert that is not bonded to the base metal. However, the absence of interlayer bonding has a negative effect on the efficiency of heat transfer through the layers of the article. Therefore, loose liners are not suitable for applications requiring good heat conduction between metal layers. In addition, loose liners are not supported against collapse, which can occur especially at high temperature or high flow conditions because the liner is not bonded to the base metal.
[0004]
If bonding between layers is desired, various bonding methods can be used. One such method is adhesive bonding using an organic or inorganic adhesive. Such bonding techniques are limited by the temperature tolerance of the adhesive. Further, the adhesive layer generally has a lower thermal conductivity than the metal layer to which it is bonded, so that the adhesive layer impedes heat conduction through the bonded layers.
[0005]
Metals are joined together by explosive pressure bonding (Gold Bulletin, vol. 10, no. 2, pp. 34 to 37, 2Apr1977). In this method, one of the metal layers is coated with an explosive. In the event of an explosion, the explosive force strikes the coated metal layer against the second metal layer, thereby achieving bonding. However, in this bonding, since the shock pressure on the metal varies due to the shock wave characteristics of the explosion, the strength or coverage is not always uniform. For the same reason, the bonded interface may have a corrugation, and thus the thickness of the metal layer may be uneven. Another disadvantage of this method is that the explosive force can cause work hardening of the metal, which is not always desirable. Moreover, explosive crimping is inadequate if one of the metals lacks the strength to withstand the explosive force required to achieve good bonding between the layers. Due to its properties, this method also imposes safety requirements when applied and can be difficult to control.
[0006]
Rolling or pressing these layers together is known to produce joined layered metal articles, but is only suitable for flat articles such as sheets. For non-planar articles, rolling is often not possible, and pressing can only be performed with tools, ie, dies, that conform to the shape of the article. For larger articles, and if one wishes to make different sizes and lengths, this can be extremely costly.
[0007]
Electroplating is only practical for thin layer applications and not all metals can be electroplated. Weld overlays are limited to articles of a shape and size accessible by the welding equipment. Coextrusion can only be used with metals whose flow properties are closely matched at the extrusion temperature. The need to match this flow characteristic limits the material combinations that can be co-extruded. Gas pressure bonding, or hot isostatic pressing, is used to bond the metals. This is done in an autoclave and is typically at temperatures between 1100 and 1700 ° C. and pressures between 10,000 and 15,000 psi (70-100 MPa). This method is not well suited for applying a liner to the inside surface of a container or tube.
[0008]
There is a need for non-planar, uniformly metallurgically bonded, layered, dissimilar metal articles and methods of making such articles.
[0009]
(Summary of the Invention)
It is an object of the present invention to provide a metallurgically bonded layered article that is corrosion resistant on at least one surface, such as piping for a heat exchanger in corrosive use.
[0010]
The present invention is a layered article having a curved surface, a non-planar layer of a supporting metal, and a forged non-planar layer of a supported metal, wherein the supporting metal layer and the supported metal layer are: An article is metallurgically bonded over an interface region having a substantially perfect bond, the interface region consisting essentially of a supporting metal and a supported metal. The supported metal or supported layer is also referred to as the applied metal or the applied layer.
[0011]
Another embodiment of the present invention is a tube comprising an outer layer of a supporting metal and an inner layer of a forged supported metal, wherein the supporting metal layer and the supported metal layer are substantially complete. It is intended for a tube which is metallurgically joined over an interfacial region having a joint and wherein the interfacial region consists essentially of the supporting metal and the supported metal.
[0012]
A further embodiment of the present invention is a method of making a layered article having a curved surface, comprising providing a non-planar layer of a wrought supported metal, providing a non-planar layer of a supporting metal, Finishing the facing surface of the supporting metal layer and the supporting metal layer, aligning the finished facing surface of the supporting metal layer and the supporting metal layer, and mechanically extending the supported layer with respect to the supporting layer. That is, by extending the supported layer with respect to the supporting layer by applying a hydraulic pressure to the supported layer, applying pneumatic pressure to the supported layer, and increasing the absolute melting point of the metal having the lower melting point by at most 98. %, Up to several days, and heating the article, as well as cooling the article.
[0013]
A further embodiment of the invention is a method of making a tube comprising providing a tubular outer layer of a support metal and a tubular inner layer of a wrought supported metal, an outer mating surface of the inner layer, and an outer layer. Finishing the inner mating surface of the inner layer, inserting the inner layer into the outer layer, mechanically stretching the inner layer relative to the outer layer, applying hydraulic pressure to the inner layer relative to the outer layer Stretching the inner layer, applying pneumatic pressure to the inner layer and heating the article up to 98% of the absolute melting point of the lower melting metal, up to several days, and cooling the article. A method comprising:
[0014]
(Detailed description)
The present invention is a layered article having a curved surface, a non-planar layer of a supporting metal, and a forged non-planar layer of a supported metal, wherein the supporting metal layer and the supported metal layer are: An article is metallurgically bonded over an interface region having a substantially perfect bond, the interface region consisting essentially of a supporting metal and a supported metal. The supported metal or supported layer is also referred to as the applied metal or the applied layer.
[0015]
In one embodiment, the invention is directed to a tube comprising an outer layer of a first metal and an inner layer, also called a lining, of a second metal. One of the layers must be a wrought metal, and both can be a wrought metal. In a preferred embodiment, the layered article is a tube, wherein the inner layer or lining contains platinum, palladium, gold, silver, copper, rhodium, and iridium, and at least one of these metals The outer layer is a metal selected from the group consisting of iron, nickel, copper, and alloys containing at least one of these metals.
[0016]
As used herein, “metal” includes steel, stainless steel, nickel-copper alloys (alloys in the range such as Monel®), or iron-based alloys (alloys in the range such as Incoloy®). Alternatively, a basic metal that is solid at room temperature, such as a nickel-based alloy (an alloy in a range such as Inconel® or Haynes® or Hastelloy®), or bronze or brass, is included. An extensive list of metals can be found in The Metals Handbook (R) Desk Edition, H.C. E. FIG. Boyer and T.S. L. Gall, Eds. , American Society for Materials, Metals Park, Ohio, 1985. The layered metal article made according to the present invention can have a layer whose metal is of the same chemical composition. This would be the case, for example, when a trained supported layer is bonded to a cast support layer of the same chemical composition.
[0017]
The supported layer is always a layer of wrought metal and, of the two layers of the two-layer metal article, generally has lower strength or higher cost. Preferred metals for the supported layer include oxidation-resistant or chemically-eroded metals such as platinum, gold, palladium, silver, rhodium, iridium, and alloys containing at least one of these metals. . When two or more metal layers are applied to make a multilayer article according to the present invention, each applied layer is a supported layer. The support metal layer can be forged, but this is not required.
[0018]
The term "wrought" refers to a metal that has been shaped by hot or cold plastic deformation, such as rolling and forging, usually from a cast state. The effect of the deformation is to crush the coarse-grained dendritic structure of the casting to produce a more uniform fine-grained structure. In some of the methods used, the metals are shaped as described in "Manufacturing Processes for Engineering Materials", Serope Kalpakjian, Addison-Wesley, Reading, MA (1985). More of the mass of the supported layer is forged, preferably more than 80% is forged, more preferably more than 90% is forged, and most preferably more than 95% is forged. In this case, this supported layer is considered to be trained for the purposes of the present invention.
[0019]
Preferred supporting metals include steel, stainless steel, nickel-copper alloys (alloys in the range such as Monel®), iron-based alloys (alloys in the range such as Incoloy®), nickel-based alloys (Inconel (Inconel®)). Or alloys such as Haynes® or Hastelloy®), or iron, nickel, and copper, such as bronze, brass, and alloys containing at least one of these metals. It is. The method of forming the supported metal depends on the final form or shape of the supported metal piece. Plates can be cast or forged, sheets can be forged, tubes or pipes can be centrifugally cast or drawn, in which case the metal is forged. It can be forged into more complex forms, in which case the metal is forged.
[0020]
The present invention also provides a method of making the above-described article. The supported and support layers should have a mating surface, i.e., the surface to be joined, of the layers to minimize the adhesion between the mating surfaces and the processing required to provide a substantially perfect bond. Are shaped so as to have almost the same shape and size as possible.
[0021]
The surface of the support layer is measured according to ANSI / ASME B46.1-1985, preferably by honing to a surface roughness of at least about RMS 8, and then by cleaning the surface, such as by degreasing, pickling, etc. Finish. If the supporting metal is susceptible to oxidation or corrosion during the fabrication of the layered article, steps must be taken to prevent oxidation. Oxidation can interfere with the bond and make it weaker or incomplete. One method of preventing oxygen from contacting the surface of the metal to be bonded is by applying a thin protective coating of an oxidation resistant metal, such as gold, silver or others, well known in the art. is there. This protective coating, also known as flash or strike, can be applied by electroplating or by electroless coating or by other means. Its thickness is typically about 0.1 μm. Another method of preventing oxidation is to evacuate the interlayer region so that oxidation does not occur during the heating. However, in particular, in the case of a large article, there is a possibility that complete evacuation may not be possible, so it is preferable to apply a protective coating of an oxidation-resistant metal.
[0022]
The supported layer is likewise cleaned and, if necessary, provided with a protective coating. If either the supported layer or the support layer is made of an oxidation resistant metal, any protective coating on the other layer is preferably the same for better bonding between the supported layer and the support layer. Of an oxidation-resistant metal. If both layers must be provided with a protective coating, it is preferred that both use the same oxidation resistant metal to promote better bonding between the supported layer and the support layer.
[0023]
If a protective coating is applied to the layer to be supported, the layer to be supported must be a metal that has been wrought as described above, but need not be a wrought protective coating.
[0024]
After performing the above-described surface treatment, the supported layer and the supporting layer are joined as described below.
[0025]
The mating surfaces of the supported metal and the supporting metal are aligned. If the supporting layer is a tube to be lined, the supported layer is also a tube whose outer diameter is only slightly smaller than the inner diameter of the supporting tube. These differences in diameter would not exceed the differences required to allow the inner tube to be inserted into the outer tube without sticking.
[0026]
The supported layer is first mechanically pressed against the support layer. If the supported layer is a liner in a supporting metal tube, the liner is mechanically pressed against the wall of the supporting tube, for example, by passing the supported tube layer and pulling out a mandrel.
[0027]
At this point, the interlayer region can optionally be evacuated to remove entrained gases, especially air. If it is desired to use vacuum pumping to prevent oxidation during the subsequent heating step, apply vacuum to one or more holes made through one or the other layer to reach the interface between the layers, Evacuate any gas remaining in between. After evacuation, seal the holes.
[0028]
Next, the supported layer is hydraulically pressed against the support layer. When the supported layer is on the interior surface of the article, the article can be filled with a liquid, such as water, and pressure is applied to make the mating surface more intimate. The magnitude of the applied pressure depends on the yield strength of the supported layer and of the support layer. Desirably, the pressure is sufficient to cause the supported layer to yield and move into more intimate contact with the support layer. Therefore, this pressure desirably exceeds the yield strength of the metal constituting the supported layer. The yield strength of many metals and alloys is described in The Metals Handbook® Desk Edition, H.E. E. FIG. Boyer and T.S. L. Gall, Eds. , American Society for Materials, Metals Park, Ohio, 1985. The measurement of the yield strength is performed according to ASTM method E8-99. If the support layer can be supported mechanically or by counter pressure during the hydraulic pressing step, the applied pressure can exceed the yield strength of the support layer. When the supported layer is on the outer surface of the article, pressure is applied to the outer surface by means determined by the shape of the article. For example, if the article is spherical and the supported layer is on the surface of the sphere, immerse the sphere in a liquid and then apply pressure to the liquid. Upon completion of the hydraulic press, the hydraulic liquid is removed and the article is dried.
[0029]
Next, an appropriate inert gas pressure is applied to the supported layer, and the article is heated to complete the bonding. The heating temperature shall be sufficient to form a metallurgical bond between the supported metal and the supporting metal. As used herein, "metallurgical bond" means a bond in which atoms of the metal in the supported layer and the metal in the support layer interdiffuse, that is, diffuse between each other. Sufficient pressure and heat are applied for a sufficient time to effect a diffusion or metallurgical bond. Pressure is applied by pneumatically pressurizing the supported layer with an inert gas such as argon. The pressure applied is less than or equal to the pressure required to keep the supported layer tight against the support layer while the metallurgical bond is being formed. A pressure of 700 to 3000 kPa is usually appropriate, and a pressure of 1500 to 2500 kPa is preferable. This pressure is lower than the pressure used for gas pressure bonding.
[0030]
In this step, the metallurgical bond mainly depends on the temperature applied, and the pressure has only a secondary effect. The temperature depends on the metal but is lower than the temperature that would be used in a hot isostatic press. The temperature can be close to the absolute melting point of the lower melting point metal. How close the temperature can be to the absolute melting point of the lower melting metal depends on the accuracy and precision of the temperature control of the heating device, and the ease of sagging or creep of the lower melting metal. This ease of sagging, or creep, will also be affected by the shape of the article. However, in most situations, it should be possible to heat up to 98% of the absolute melting point of the lower melting point metal. Preferably, the temperature during heating should be 50-95% of the absolute melting point of the lower melting metal. This heating lasts up to several days, preferably 1 to 24 hours, more preferably 5 to 15 hours, most preferably 8 to 12 hours. Second, the temperature should be such that substantial interdiffusion occurs within a reasonable time interval. This is from the literature (eg, Smithell's Metals Reference Book, EA Brandes, GB Brook and CJ Smithell, Butterworth-Heinemann, Boston, MA (1998), p. 13-1). It can be estimated from the required diffusion coefficient.
[0031]
Surprisingly, it has been found that omitting either the application of mechanical force or the application of hydraulic pressure reduces the quality of the metallurgical bond between the layers.
[0032]
The method can be repeated if the finished article needs to be provided with one or more additional layers of the same supported metal or of another supported metal. The resulting article comprises a supported layer and a support layer, both metallurgically bonded. At the interface between the supported layer and the support layer, there is a region where metal is interdiffused, and this region is called an interface region. If different metals are to be joined, the interface region comprises an alloy of the two constituent metals. This alloy is formed by interdiffusion of metals during the metallurgical bonding step. When chemically identical metals are joined, the interface region is composed of atoms from both the supported and support layers. To achieve a metallurgical bond, there must be some interdiffusion. Complete interdiffusion is undesirable because it completely defeats the purpose of layering the supported metal on the support metal. Therefore, the thickness of the interface region should be smaller than the thickness of the supported layer or the supporting layer. Interfacial areas with a thickness of a few micrometers are suitable. The interface area is determined from measurements on the cross section of the layered article. The thickness “100-0” is measured by a technique such as energy dispersive spectroscopy (ECD), since the metal composition is not the metal composition of only the supported layer first, so that the metal composition is It is the distance to the point where only the metal composition is obtained. Sometimes it is easier to measure the thickness "90 to 10", and the thickness "90 to 10" indicates that at least one component of the supported layer is the component in the material constituting the supported layer. The distance from the point where the concentration is reduced to 90% of the concentration to the point where the same component is reduced to 10% of the concentration.
[0033]
Preferably, the thickness of the interface region should be less than 150% of the original thickness of the supported layer, defined herein as the thickness "90-10", and the original thickness of the supported layer Is more preferably less than 50%, and most preferably less than 25% of the original thickness of the supported layer.
[0034]
"Substantially perfect bonding across the interface area" refers to bonding of at least 80%, preferably 90%, more preferably 95%, and most preferably 100% of the area of the interface.
[0035]
If one or both of the finished surface of the supported layer and the support layer is provided with an oxidation-resistant coating, the interface region consists essentially of an alloy of the metal constituting the supported layer and the support layer. . Even if the layer to be supported and / or the supporting layer has an oxidation-resistant coating on the contact surface of the two layers, the resulting interfacial area is essentially still small because of the small thickness of both oxidation-resistant coatings. And an alloy of the metal constituting the supported layer and the supporting layer.
[0036]
If a second layer to be supported is desired, the above steps are repeated.
[0037]
(Example)
The mating surface roughness of the supported and support layers is measured as described in the American Society of Mechanical Engineers (ASME) symbol ASME B46.1-1995 and is reported as an "RMS" number. The presence of a bond between the layers is measured by an ultrasonic test (UT). This technique uses the transmission of sound waves to determine whether a bond exists. If a bond is present, the sound waves penetrate the layered article and the thickness of the layered article is measured. In the absence of any bonding, the sound wave only penetrates the supporting metal part, and only the thickness of the supporting metal part can be measured by the American Society for Materials Handbook, Volume 17: Nondestructive Evaluation and Quality Control, SM, ATP. 231 is measured. The thickness of the interdiffusion region of the metal of the supported and support layers is measured by scanning electron microscopy and by electron dispersive X-ray analysis (EDAX) profiles of the elements concerned. A joint having a thickness of at least 10 μm and containing at least 10 atomic% of the diffusing element is considered metallurgical for the purposes of the present invention. The joint is also examined by metallographic examination, i.e. by high-power optical or scanning electron microscopy of a cross section cut from the joined article. The micrographs will clearly show the presence of gaps between the supported and supported metals, and the presence of oxide or other interference layers at the interface of these metals.
[0038]
Estimates of the time and temperature required to form a metallurgical bond are shown here for gold and nickel. The average penetration distance x, the distance over which a significant amount of diffusion occurs, is determined by the approximate solution to Fick's diffusion law (Structure and Properties of Alloys, RM Brick, RB Gordon and A. Phillips, It can be estimated from McGraw-Hill (1965), p.
x ² = Dt (1)
However, in the formula, D is a unit cm. ² / Diffusion coefficient and t is time in seconds. D can be estimated from Equation 2:
D = A · exp (−Q / RT) (2)
Where A is 0.034 ± 0.007 cm ² / Sec, Q is 42.0 ± 0.4 kcal / mol, R is the gas constant, and T is the absolute temperature. The values of A and Q are N. Kuhl, K .; Hirano and M.C. Cohen: Acta Met. , 11, 1 (1963). At 850 ° C. (1123 ° K), the value of D from equation 2 is 2.3 · 10 ^-10 cm ² / Sec. Using this value of D in Equation 1, the thickness of the significant diffusion region at 850 ° C. for 10 hours is determined to be about 30 μm. This is in good agreement with the thickness of 50 μm in the region from 90:10 to 10:90 described in Example 1 below.
[0039]
Example 1
This example describes the production of a tube of Inconel® 600 alloy with a gold lining according to a preferred embodiment of the present invention. This Inconel® tube is the support layer. The gold lining is the supported layer. Inconel® tubing has an outer diameter of 26.7 mm and an inner diameter of 20.9 mm and is less than 1 meter in length. The gold lining is a wrought tube of the same length, having an outer diameter of 20.50 mm and an inner diameter of 18.50 mm. The inner surface of the Inconel® tube is honed to RMS 8 finish and is first cleaned by degreasing with Oakite # 3 soap hot solution. This is followed by pickling using sulfuric acid and hydrochloric acid solution (7.9% by volume of 93% sulfuric acid, 12% by volume of 32% hydrochloric acid, mixed with the residual water ratio). The pickling time is 10 to 20 minutes. The tubes are then rinsed with deionized water for 0.5 to 1 minute. The tube is then pickled for 20 minutes in an aqueous nitric acid solution (made by mixing 20% by volume of 68% nitric acid in 80% by volume of water). This is followed by a 0.5 to 1 minute rinse with deionized water and drying. Visually inspect the tube and repeat any pickling steps if any abnormalities are found.
[0040]
The brass tube is prepared by degreasing with a suitable solvent, followed by pickling with nitric acid (aqueous solution made with 68% nitric acid in 20% by volume in water) for 20 minutes. This is followed by a 0.5 to 1 minute rinse with deionized water and drying.
[0041]
The gold lining is swaged on a mandrel and drawn into an Inconel® tube. The lining is then mechanically extended by withdrawing an extension plug or mandrel through the gold lining. Withdraw the progressively larger extension plug through the gold lining until the calculated outer diameter of the gold lining is within the tolerance of the Inconel® tube inner diameter. This Inconel®-gold combination structure is called a “tube”.
[0042]
The seam between the gold and Inconel® at both ends of the tube is sealed with nickel braze. At intervals along the tube, only holes in the Inconel® layer are drilled and the fittings are attached so that the space between the gold layer and the Inconel® layer can be evacuated. This space is evacuated. The tube is then filled with water and a hydraulic pressure of 20 MPa is applied for several hours at room temperature. Release pressure, drain water from tube and allow to dry. The tube is then pressurized to about 700 kPa with an inert gas such as argon and heated at 1050 K (777 C) to 1150 K (877 C) for about 8 hours. After cooling and depressurization, the tubing is tested to determine the extent of the bond (the ultrasonic test does not measure the quality of the bond-the ultrasonic test determines whether a bond is present). Ultrasonic testing on this tube showed that there was a bond on more than 99% of the tube surface. The metallographic cross section of the tube was prepared to confirm that the gold liner was bonded to Inconel®. There is no evidence of contamination at the gold-Inconel® interface. The element profile was measured and it was determined that this junction extended in the thickness direction over approximately 250 μm. This is the point on the graphical representation where the gold content first reaches 0 atomic%, from the point on the graphical representation where the gold content is first seen to decrease from 100 atomic%, the point on the FIG. 1 and FIG. Is the distance to The distance from the point where the gold content is 90 atomic% to the point where the gold content is 10 atomic% is 50 μm.
[0043]
Comparative Example A
The tubing is prepared in the manner described in Example 1, and the tubing is joined as described, except that the step of mechanical stretching is omitted. A test was performed using a UT to determine the absence of any bond between the liner and the support metal. This indicates that a mechanical elongation step is required to achieve a metallurgical bond.
[0044]
Comparative Example B
The tubing is prepared in the manner described in Example 1, and the tubing is joined as described, except that the step of hydraulic stretching is omitted. Diffusion bonding is performed in two steps: first at 775K (502C) for 10 hours, then at 1125K (852C) for 10 hours. Ultrasonic testing has shown that there is limited metallurgical bonding. The joint exists over approximately 66% of the tube surface. This indicates that a hydraulic extension step is required to achieve a perfect metallurgical bond.
[0045]
Comparative Example C
A tube is prepared as described in Example 1. In this example, mechanical stretching is performed as described in Example 1. Instead of continuing as in Example 1, metallurgical joining by explosive joining is attempted. The gold liner is coated with a charge and then exploded. This procedure is repeated until the ultrasonic test shows a minimum of 20% bonding over the length and circumference of the Inconel® tube. The tube is then sealed and subjected to a diffusion bonding process as described in Example 1. A thorough UT inspection of the tube was then performed and found that the extent of the joint was approximately 20%. This indicates that explosive bonding is not suitable for achieving perfect metallurgical bonding.
[0046]
Comparative Example D
This example is prepared as in Example 1, except that the tube is several meters long. The procedure of Example 1 is followed, but analysis shows little bonding between layers. Testing of both layers shows the presence of oxide on their surface. This indicates that the evacuation of a large article is not complete, leaving enough air to oxidize both surfaces, preventing the formation of a metallurgical bond.
[0047]
Example 2
This example is prepared as in Example D, except that the preparation of the tube surface is done differently. After cleaning the Inconel® tubing, the Inconel® tubing is immersed in a bath suitable for electroless gold plating to deposit a layer of gold about 0.1 μm thick on its surface. Thereafter, the tube is machined as described in Example 1. Metallographic examination shows that the metallurgical bond is well established without any signs of oxide at the interface. Such an oxide would inhibit the bonding between the metals. No ultrasonic testing was performed on this tube. The advantage of electroless gold plating is that it protects the Inconel® surface from oxidation during the diffusion bonding step. This is especially important for large tubes, in which case it is difficult to evacuate the annular space efficiently, and residual air tends to remain.
[Brief description of the drawings]
FIG.
FIG. 2 is a plot of the cross-sectional elemental profile of a gold-lined Inconel® tube, the tube being made in accordance with the present invention.
FIG. 2
FIG. 2 is a detailed view of FIG. 1.

Claims (44)

A layered article comprising a curved surface, a non-planar layer of a supporting metal, and a non-planar layer of a forged supported metal, wherein the supporting metal layer and the supported metal layer are substantially An article characterized in that it is metallurgically bonded over an interface region having a perfect bond, and wherein the interface region consists essentially of the supporting metal and the supported metal. The layered article of claim 1, further comprising a second, non-planar layer of wrought supported metal. The supported metal is selected from the group consisting of platinum, palladium, gold, silver, copper, rhodium, and iridium, and alloys containing at least one of these metals, and the supporting metal is iron, nickel, copper And a layered article according to claim 1, wherein the article is selected from the group consisting of alloys containing at least one of these metals. 4. A layered article according to claim 3, wherein the supported metal is gold and the supporting metal is an alloy of nickel. 4. A layered article according to claim 3, wherein the supported metal is palladium and the supporting metal is an alloy of nickel. 2. The layered article according to claim 1, wherein the thickness of the interface region is less than 150% of the original thickness of the supported metal layer. 2. The layered article according to claim 1, wherein the thickness of the interface region is less than 50% of the original thickness of the supported metal layer. 2. A layered article according to claim 1, wherein the thickness of the interface region is less than 25% of the original thickness of the supported metal layer. A method of making a layered article having a curved surface,
Providing a non-planar layer of forged supported metal, providing a non-planar layer of support metal, finishing a mating surface of the supported metal layer and the support metal layer, the finished supported metal layer and support Aligning the mating surfaces of the metal layers, mechanically extending the supported layer relative to the support layer, and extending the supported layer relative to the support layer by applying hydraulic pressure to the supported layer Applying pneumatic pressure to the supported layer and heating the article for up to several days up to 98% of the absolute melting point of the lower melting metal, and cooling the article. A method comprising: The method of claim 9 wherein the article is heated to within 50-95% of the absolute melting point of the lower melting metal. The method of claim 9, wherein the article is heated for 1 to 24 hours. Further, after the finishing step, the method further comprises applying an oxidation-resistant metal layer having a thickness of about 0.1 μm to the finished surface of either the supported layer or the support layer, or both. Item 10. The method according to Item 9. 13. The method of claim 12, wherein the oxidation resistant metal is gold. 13. The method according to claim 12, wherein the oxidation resistant metal is palladium. The method of claim 9, wherein the mating surfaces of the support layer and the supported layer are finished to a surface roughness of at least about RMS 8. The method of claim 9, further comprising evacuating the space between the supported layer and the support layer. 10. The method according to claim 9, further comprising evacuating the space between the supported layer and the supporting layer, wherein the evacuating is performed between a mechanical stretching step and a hydraulic stretching step. The described method. The method of claim 9, wherein the supporting metal layer is an alloy of nickel and the supported metal layer is gold. The method of claim 9, wherein the supporting metal layer is an alloy of nickel and the supported metal layer is palladium. The method of claim 9, wherein the thickness of the interface region is less than 150% of the original thickness of the supported metal layer. 10. The method of claim 9, wherein the thickness of the interface region is less than 50% of the original thickness of the supported metal layer. The method of claim 9, wherein the thickness of the interface region is less than 25% of the original thickness of the supported metal layer. A tube comprising an outer layer of a supporting metal and an inner layer of a forged supported metal, wherein the supporting metal layer and the supported metal layer are metallurgically bonded over an interface region having substantially perfect bonding. Wherein the interface region consists essentially of the supporting metal and the supported metal. The supported metal is selected from the group consisting of platinum, palladium, gold, silver, copper, rhodium, and iridium, and alloys containing at least one of these metals, and the supporting metal is iron, nickel, copper 24. The tube of claim 23, wherein the tube is selected from the group consisting of: and an alloy containing at least one of these metals. 25. The tube of claim 24, wherein the supporting metal is an alloy of nickel and the supported metal is gold. 25. The tube of claim 24, wherein the supporting metal is an alloy of nickel and the supported metal is palladium. 24. The tube according to claim 23, wherein the support layer and the supported layer have a circular cross section. 28. The tube of claim 27, wherein the thickness of the interface region is less than 150% of the original thickness of the inner layer of the supported metal. 28. The tube of claim 27, wherein the thickness of the interface region is less than 50% of the original thickness of the inner layer of the supported metal. 28. The tube of claim 27, wherein the thickness of the interface region is less than 25% of the original thickness of the inner layer of the supported metal. A method of making a tube, comprising:
Providing a tubular outer layer of support metal and a tubular inner layer of wrought supported metal, finishing the outer facing surface of the inner layer, and the inner facing surface of the outer layer, inserting the inner layer into the outer layer Doing, mechanically extending the inner layer relative to the outer layer, applying hydraulic pressure to extend the inner layer relative to the outer layer, applying air pressure to the inner layer, and having a melting point of A method comprising heating the article up to 98% of the absolute melting point of the lower metal, up to several days, and cooling the tube. 32. The method of claim 31, further comprising, after the finishing step, applying an oxidation-resistant metal layer having a thickness of about 0.1 μm to one or both of the finished surfaces. The method described in. 33. The method of claim 32, wherein the oxidation resistant metal is gold. 33. The method of claim 32, wherein the oxidation resistant metal is palladium. 32. The method of claim 31, wherein the tube is heated to 50 to 95% of the absolute melting point of the lower melting point metal. The method according to claim 31, wherein the tube is heated for 1 to 24 hours. 32. The method of claim 31, wherein the inner mating surface of the support layer and the outer mating surface of the supported layer are finished to a surface roughness of at least about RMS 8. The method of claim 31, further comprising evacuating the space between the supported layer and the support layer. 32. The method according to claim 31, further comprising evacuating the space between the supported layer and the supporting layer, wherein the evacuating is performed between a mechanical elongation step and a hydraulic elongation step. The described method. 32. The method of claim 31, wherein the tubular outer layer is an alloy of nickel and the tubular inner layer is gold. The method of claim 31, wherein the tubular outer layer is an alloy of nickel and the tubular inner layer is palladium. The method of claim 31, wherein the thickness of the interface region is less than 150% of the original thickness of the supported metal tubular inner layer. The method of claim 31, wherein the thickness of the interface region is less than 50% of the original thickness of the tubular inner layer of supported metal. The method of claim 31, wherein the thickness of the interface region is less than 25% of the original thickness of the tubular inner layer of supported metal.

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