Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
  • B32B15/018—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of a noble metal or a noble metal alloy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K1/00—Soldering, e.g. brazing, or unsoldering
  • B23K1/19—Soldering, e.g. brazing, or unsoldering taking account of the properties of the materials to be soldered
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K1/00—Soldering, e.g. brazing, or unsoldering
  • B23K1/20—Preliminary treatment of work or areas to be soldered, e.g. in respect of a galvanic coating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
  • B23K35/001—Interlayers, transition pieces for metallurgical bonding of workpieces
  • B23K35/004—Interlayers, transition pieces for metallurgical bonding of workpieces at least one of the workpieces being of a metal of the iron group
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
  • B23K35/001—Interlayers, transition pieces for metallurgical bonding of workpieces
  • B23K35/005—Interlayers, transition pieces for metallurgical bonding of workpieces at least one of the workpieces being of a refractory metal
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K9/00—Arc welding or cutting
  • B23K9/12—Automatic feeding or moving of electrodes or work for spot or seam welding or cutting
  • B23K9/124—Circuits or methods for feeding welding wire
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
  • B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
  • B32B15/013—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/02—Iron or ferrous alloys
  • B23K2103/04—Steel or steel alloys
  • B23K2103/05—Stainless steel
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/08—Non-ferrous metals or alloys
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/18—Dissimilar materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/18—Dissimilar materials
  • B23K2103/24—Ferrous alloys and titanium or alloys thereof
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49826—Assembling or joining
  • Y10T29/49885—Assembling or joining with coating before or during assembling
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12806—Refractory [Group IVB, VB, or VIB] metal-base component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12896—Ag-base component

Definitions

• the present invention relates to a method of manufacturing elements of chemical devices that are used to manipulate, store and / or process
• a steel support (carbon steel or stainless steel) which gives the assembly its mechanical strength and a corrosion-resistant metal coating based on a noble metal or a reactive metal, the latter giving a protective layer after reaction with the oxygen or with the corrosive medium concerned.
• a material such as tantalum, tungsten, vanadium or their alloys is chosen, or, if conditions permit, reactive metals such as zirconium, titanium, hafnium or their alloys. Because of the cost of these materials, it is sought to achieve coatings as thin as possible.
• the present invention relates more particularly to the elements of chemical devices having a thin zirconium coating, typically less than 1 mm thick. It may also concern the manufacture of elements of devices coated internally with zirconium and used for the storage, the exploitation and / or the transport of nuclear materials. We will later designate these with the help of the general expression "nuclear devices”. STATE OF THE ART
• the elements of chemical devices can be made in several ways, either by "dressing" the inside of the chemical device once it has been completely shaped, or by depositing the coating on parts already shaped and then assembling them, or by depositing the coating on semifinished products, such as plates or tubes, by shaping these half-products thus coated and assembling the various parts thus obtained.
• the dressing can be done without junction between the support and the coating ("floating coating” or "loose-lining").
• a mechanical attachment of the coating to the support is carried out, by anchoring, in a limited number of points of the assembly.
• Such a technique theoretically allows the use of anti-corrosion coatings of a few hundred microns thick.
• use of a thin coating is undesirable since the coating is not intimately attached to the substrate and may subside or to collapse when the enclosure is subjected to a depression.
• thermal projection technologies hot or cold projection, assisted or not by plasma.
• these technologies make it possible to obtain both a good cohesion of the assembly and a low consumption of noble metal, they do not make it possible to guarantee at 100% the tightness of the anti-corrosion coating.
• GB 874 271 proposes the use of two different intermediate metal layers between zirconium and steel: the steel plate is coated with vanadium, and the zirconium plate is coated with niobium or titanium; the thickness of each of these coatings of the order of one millimeter.
• Intermediate metals were also used to join two zirconium or ziracloy plates one on the other (see US Pat. No. 3,106,773), but the thicknesses used were much lower: on each side, a thickness of the order from 5 to 500 nm for titanium, and of the order of 300 to 500 nm for copper was used.
• the Applicant has shown that it is advantageous to produce chemical device elements by using steel plates or sheets which are coated with a metallic anti-corrosion material. melting of an intermediate layer of brazing alloy, by forming by plastic deformation the thus coated plates and then welding them between . they so that the element obtained gives the device its final geometry.
• the brazing temperature must be as low as possible. For this reason, it is generally used a brazing alloy well suited to low target temperatures, which comprises silver and copper and whose melting temperature is less than 900 ° C.
• this type of alloy can not be used to solder a zirconium coating because zirconium reacts with the copper of the solder to give weakening compounds which greatly limit the ductility of these assemblies.
• This loss of ductility leads to the decohesion of the coating during the shaping by plastic deformation of the assemblies (production convex bottom for example) and the chemical device thus loses its protection vis-à-vis corrosion.
• the Applicant has attempted to develop a method for obtaining elements of chemical or nuclear devices comprising a coating of zirconium or zirconium alloy, which has a thickness typically less than 1 mm, preferably less than 0.5 mm. or 0.3 mm and which has none of the disadvantages of the processes of the prior art.
• a first object of the invention is a method of manufacturing coated assembly parts intended for example for the manufacture of a chemical device element comprising a zirconium or zirconium alloy coating, said assembly parts comprising a part of steel support and at least one zirconium or zirconium alloy coating, said method comprising the following successive steps: a) forming an initial assembly comprising a steel support member, typically a plate, a zirconium coating or zirconium alloy, typically a sheet of dimension close to that of the steel plate, and at least one brazing material between the support member and the coating, said brazing material being an alloy comprising silver and silver.
• the method is characterized in that, prior to forming said initial assembly, depositing a layer of titanium or a titanium alloy on said coating. zirconium or zirconium alloy and that said coating is placed so that its coated surface of titanium or titanium alloy is brought into contact with said brazing material.
• the method of the invention makes it possible to fix firmly on a steel part, a coating of zirconium or zirconium alloy having a thickness of less than 1 mm, or even less than 0.5 mm, and for some favorable geometries, less than or equal to 0.3 mm.
• the coated assembly part has a sufficient ductility and can be shaped later by plastic deformation (embodiment convex bottom for example).
• the steel support piece and the zirconium or zirconium alloy coating typically have simple shapes (plate and sheet, for example), but they may possibly have been predeformed, especially if the part to be produced has a part that requires plastic deformation. important (folding or bending on a weak ray, less than 5 times the thickness for example).
• the coating is pure Van Arkel zirconium or, more generally, zirconium alloy, typically an alloy used in the chemical industry or the nuclear industry.
• zirconium-hafnium alloy of the Zirconium 702 type (UNS R60702 standard) or a zirconium-hafnium-niobium alloy, of the Zirconium 705 type (UNS R60705 standard) is generally used.
• non-hafnished zirconium is used, for example a zirconium-tin alloy such as zircaloy 2 or zircaloy 4 or a zirconium-niobium alloy
• the ability to shape the assemblies is obtained by changing the surface of the zirconium coating or zirconium alloy which is intended to come into contact with the brazing material.
• This modification consists in depositing on the surface of the coating a titanium or titanium alloy layer of a few microns, typically between 1 and 10 ⁇ m, preferably between 2 and 10 ⁇ m, more preferably between 2 and 7 ⁇ m and even more preferentially between 3 and 6 ⁇ m.
• the deposition may be carried out by cathode sputtering in a chamber equipped with a magnetron cathode at a pressure of between 10 -4 Torr and 10 -2 Torr
• the target is preferably pure titanium, typically 99.995% pure or more, but it is possible to use titanium alloy targets comprising other elements such as vanadium, niobium, molybdenum or chromium, typically Ti-Al-V alloys, Ti-Mo-Nb-Al-Si, Ti-Pd or else Ti-V-Cr-Al.
• Other deposition techniques can be envisaged, a PVD (Physical Vapor Deposition) assisted by plasma, a CVD deposit (Chemical Vapor Deposition) which can also be assisted.
• the zirconium sheet or zirconium alloy is preliminarily cleaned, degreased and the surface to be treated is etched by ionic etching. found that one can advantageously use thicker layers, a thickness of up to 50 microns, but preferably less than 30 microns. This allows in particular the use of other deposition techniques, such as the vacuum plasma torch.
• An initial assembly comprising a support piece, typically a plate, made of steel - carbon steel or stainless steel -, a zirconium or zirconium alloy sheet coated with a titanium layer on the face facing the support and at least one brazing material between the support member and the coating.
• Said soldering material is an ⁇ lji ⁇ ge including silver and copper, preferably easy to find in the trade.
• a binary Ag-Cu alloy of composition close to the eutectic typically Ag between 67% and 75% and complementary Cu, whose liquidus temperature is below 800 0 C
• a ternary alloy also comprising zinc is also comprising zinc.
• Ternary alloys (silver-copper-zinc) are commercially available in many variants. Silver is the main element, it allows to increase the fluidity and improve the resistance of the joint especially with alternating efforts, the money also confers on the alloy a ductility that is used for the deliver in various forms (thin sheets, end caps, rings, trellises, etc.) and adapt it to the most diverse cases.
• the ternary alloys of the silver-copper-zinc type for example Ag 33% - Zn 33.5% - Cu 33.5%, have a low liquidus temperature, which can fall below 730 ° C., with a solidification range. rather low, typically of the order of 40 ° C.
• a quaternary alloy comprising silver, copper, zinc and tin, for example Ag 55%, Zn 22%, Cu 21% and Sn 2%. Alloys quaternary type silver-copper-zinc-tin have a low liquidus temperature, of the order of 660 0 C for the composition mentioned above, with a relatively small solidification interval (of the order of 30 0 VS). They are very fluid and give resistant and not very fragile joints.
• a quaternary alloy comprising silver, copper, zinc and cadmium, for example Ag 50%, Zn 16.5%, Cu 15.5% and Cd 18%.
• Quaternary alloys of the silver-copper-zinc-cadmium type have a low liquidus temperature, of the order of 630 ° C. for the composition mentioned above, with a fairly low solidification range (of the order of 20 ° C. ). They are very fluid and give resistant and not very fragile joints
• the initial assembly is introduced into a controlled atmosphere soldering chamber.
• the controlled atmosphere is preferably a fairly high vacuum: the chamber is typically placed under a pressure of 10 S and 1 O 3 mbar, ie between 1 O 3 and TO -1 Pa. However, especially when the solder contains
• a neutral gas such as argon, nitrogen or an argon-nitrogen mixture under a partial pressure typically between 5 10 3 and 10 4 Pa.
• said w initial assembly is made by bringing said plates and coated sheet together in order to obtain a spacing D which is preferably chosen so as to avoid the formation of gas bubbles or bonding defects between the bonding surfaces during the soldering operation.
• the spacing D is typically less than 0.1 mm.
• the zirconium sheet is placed in such a way
• the titanium or titanium alloy layer is in contact with the brazing material.
• the brazing material is preferably uniformly distributed between the support member and the anti-corrosion coating to provide a uniform bonding layer and to increase the contact area between these two elements.
• the brazing material is typically in the form of a powder, a strip or a lattice. In his tests, the Applicant has found that the mesh has the advantage of effectively compensating for any variations in the spacing D between the bonding surfaces.
• the initial assembly is brought to a temperature slightly above the liquidus temperature of the brazing material, so that the brazing material melts and produces an intimate connection with the element with which it is soldered. is in contact.
• the brazing temperature is less than about 900 ° C., preferably less than the austenitization temperature of the steel of the support, ie, depending on the steels, less than a temperature generally in the range from 760.degree. 0 C and 850 0 C.
• the method advantageously comprises applying a plating pressure to said initial assembly during all or part of the brazing operation. More specifically, it is advantageous to apply a plating mechanical pressure on said assembly before and / or during, said heating.
• This plating pressure is exerted so that the support piece and the anti-corrosion coating are clamped against each other and in such a way as to compress the brazing material, which notably makes it possible to obtain the desired value. for the spacing D between the support piece and the coating.
• the plating pressure (also called docking pressure), typically greater than 0.1 MPa, can be applied by a mechanical clamping system, such as a system of tie rods, springs and clamping plates, or a system such as an airbag or a system using hydraulic cylinders.
• the brazing operation at low temperature limits the degradation of the mechanical clamping system.
• the invention it is avoided to form zirconium-copper compounds which weaken the interface between the steel support and the zirconium coating. In this way the substrate / coating bond is sufficiently ductile to be shaped by plastic deformation after soldering.
• the thickness of the titanium or titanium alloy layer deposited on the zirconium sheet does not exceed 10 ⁇ m. It is typically between 1 and 10 ⁇ m, preferably between 2 and 10 ⁇ m, even more preferably between 2 and 7 ⁇ m, and most preferably between 3 and 6 ⁇ m.
• the Applicant has indeed found a deterioration of the braziness of the assembly when the thickness of the titanium layer or titanium alloy is greater. The Applicant explains this degradation in the following manner: the contribution of titanium has the effect of increasing the allotropic transformation temperature of alpha zirconium (hexagonal structure compact) of zirconium beta (centered cubic structure) of 865 ° C.
• a Zr-Ag-Cu-Ti alloy is locally created with a content that can go beyond the eutectoid composition, so with a risk of creation during the cooling of a large number of embrittling intermetallic phases.
• the shaping by plastic deformation of the coated parts is typically carried out by rolling, calendering, stamping or embossing.
• the coated form pieces typically have curved, semi-cylindrical or other shapes.
• the assembly operation of the assembly parts coated, so as to produce a chemical device element comprises the formation of joints between said parts, typically by welding operations according to any known means, for example described in US 4,073. 427 or WO / 03/097230.
• Another subject of the invention is a sheet of zirconium or zirconium alloy characterized in that it is coated on one of its faces with a titanium or titanium alloy layer, of thickness typically between 1 and 10 ⁇ m, preferably between 2 and 10 ⁇ m, more preferably between 2 and 7 ⁇ m, and even more preferably between 3 and 6 ⁇ m.
• a titanium or titanium alloy layer typically between 1 and 10 ⁇ m, preferably between 2 and 10 ⁇ m, more preferably between 2 and 7 ⁇ m, and even more preferably between 3 and 6 ⁇ m.
• Such a sheet is particularly well suited for producing steel plates zirconium coated easy to shape by plastic deformation. With a thickness of less than 1 mm, or even less than 0.5 mm, and even possibly less than or equal to 0.3 mm, these sheets make it possible to produce chemical devices or elements of inexpensive chemical devices.
• Another subject of the invention is a process for producing a sheet of zirconium or zirconium alloy coated with a titanium or titanium alloy layer, typically between 1 and 10 ⁇ m thick, preferably between 2 and 10 ⁇ m thick. ⁇ m, more preferably between 2 and 7 ⁇ m, and even more preferably between 3 and 6 ⁇ m, characterized in that the titanium is deposited by sputtering in a chamber equipped with a magnetron cathode under a pressure of between 10 -4 Torr and 10 ' 2 Torr
• the zirconium or zirconium alloy sheet has been previously cleaned and degreased and the surface to be treated etched by ion etching.
• a steel plate coated with a zirconium or zirconium alloy layer comprising a support layer made of steel (carbon steel or stainless steel) of thickness typically and preferably between 1 mm and 50 mm, an intermediate layer made of titanium or titanium alloy and a layer of zirconium or zirconium alloy, of thickness typically and preferably less than 5 mm, preferably less than 1 mm, or even less than 0.5 mm, and even less than or equal to 0.3 mm.
• Another object of the invention is a method of manufacturing a steel plate coated with a zirconium or zirconium alloy layer, said method comprising the following steps: a) forming an assembly comprising a steel plate , a sheet of zirconium or zirconium alloy, typically of dimension close to that of the steel plate, and at least one brazing material between the support member and the coating, said solder material being an alloy comprising silver and copper; b) introducing the assembly into a controlled atmosphere brazing chamber; c) forming a controlled atmosphere in said chamber; d) heating said assembly to a temperature at least equal to the brazing temperature of said brazing material, so as to braze the zirconium sheet on the steel plate; characterized in that prior to forming said assembly, depositing a titanium or titanium alloy layer on said zirconium or zirconium alloy coating and placing said coating so that its face coated with titanium or titanium alloy is brought into contact with said brazing material.
• the zirconium or zirconium alloy coating has a thickness of less than 1 mm, or even less than 0.5 mm, possibly less than or equal to 0.3 mm.
• the deposition may be performed by sputtering in a chamber equipped with a cathode magnetron under a pressure of between 10 "* Torr and 10- 2 Torr.
• Other 'deposition techniques can be envisaged, a plasma-assisted PVD or a thermal spraying deposit of the "cold spray” type for example, or also the deposition by plasma torch under vacuum
• the surface on which the deposition is carried out is preferably prepared suitably before the deposition, for example cleaned, degreased and optionally etched by ion etching.
• the brazing material is an alloy comprising silver and copper, preferably easy to find in the
• an Ag-Cu binary alloy of composition close to the eutectic (Ag 72% -Cu 28%)
• a quaternary alloy comprising silver, copper, zinc and cadmium for example Ag 50%, Zn 16 , 5%, Cu 15.5% and Cd 18%.
• the controlled atmosphere is preferably a fairly high vacuum: the chamber is typically put under a lower pressure of between 10 3 and 10 1 Pa.
• the solder contains metals which tend to sublimate such tin or zinc (risk of pollution of the load or the oven during treatment), it is
• a neutral gas such as argon, nitrogen or an argon-nitrogen mixture at a partial pressure of typically between 10 3 and 10 4 Pa.
• the initial assembly is brought to a lower temperature, at about 900 ° C., preferably below the austenitization temperature of the support steel.
• the method advantageously comprises the application of a plating pressure (also called docking pressure) on said assembly during all or part of the soldering operation, typically greater than 0.1 MPa. 0
• Another subject of the invention is a method of manufacturing a chemical device element comprising a zirconium or zirconium alloy coating, comprising at least a first and a second coated assembly part, each said assembly part.
• coating 5 comprising a steel support member and at least one zirconium or zirconium alloy coating, said method being characterized in that it comprises the following successive steps: a) manufacturing of assembly parts coated according to the method of any one of claims 1 to 9; b) forming said intermediate coated parts, typically by rolling, bending, calendering, stamping or embossing, so as to obtain said coated assembly parts; c) assembling the coated assembly parts to obtain said chemical device element.
• the zirconium-hafnium alloy sheet is degreased with an organic solvent. Ion etching of the surface to be coated is then carried out using the same installation as that which will be used for the deposition.
• a 5 ⁇ m deposition of titanium is carried out by cathodic sputtering of a pure Ti target (99.995%).
• the support plate is 316L stainless steel (UNS reference S31603), 10 mm thick, 2m long and 1 m wide.
• the zirconium sheet is placed on the steel sheet.
• strips of alloy Ag 72% - Cu 28% degreased with an organic solvent were deposited on the steel sheet. These strips are placed so that they are between the steel support and the zirconium coating.
• the steel sheet and the coating are held together by applying with the help of tie rods and clamping plates a pressure close to 0.1 MPa, or 10 tons per square meter.
• the whole is brazed in a vacuum oven at a temperature of 83O 0 C and a pressure of 5 10- 5 mbar or 5 10- 3 Pa.
• the coated sheet is cooled slowly, first by maintaining the vacuum up to a plateau close to 600 0 C, then under nitrogen until about 500 0 C and then under forced convection air to 200 0 C
• the total cooling time reaches 48 hours.
• the titanium-coated zirconium sheet made in the first example is placed on the steel sheet, titanium face directed towards the steel sheet.
• 72% - Cu 28% Ag alloy strips defatted with an organic solvent were deposited on the steel sheet. These strips are placed so that they are between the steel support and the titanium layer of the zirconium coating.
• the steel sheet and the cladding are held together by applying with pressure rods and clamping plates a pressure close to 0.1 MPa, or 10 tonnes per square meter.
• the whole is brazed in a vacuum oven, at a temperature of 830 ° C. and at a pressure in the region of 5 10 -5 mbar, ie 5 ⁇ 10 -3 Pa.
• the assembly is then slowly cooled as previously described for the first assembly.
• the interface between the solder and the zirconium sheet is, thanks to the presence of the titanium layer, free from decohesion defects.
• the titanium-coated zirconium sheet made in the first example is placed on the steel sheet, titanium face directed to the steel sheet.
• quaternary alloy strips were deposited on the steel sheet. Ag 55% -Cu 21% -Zn 22% - Sn 2%. These strips have been degreased with an organic solvent and placed so that they are between the steel support and the titanium layer of the zirconium coating.
• the steel sheet and the coating are held together by applying with the aid of tie rods and clamping plates a pressure close to 0.1 MPa.
• the whole is brazed in a vacuum oven, at a temperature of 750 ° C and with a partial pressure of argon, of the order of 90 mbar, or 9 10 3 Pa.
• the assembly is then cooled for 48 hours. Then the assembly is bent to achieve a semi-cylindrical shell of radius 250 mm. The cylindrical shell is then coupled to another semi-cylindrical shell according to one of the techniques described in US 4073427 or WO / 03/097230.

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