Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00

Definitions

• Aluminum-containing nickel-based alloys and stainless steels are often used as carrier foils in automotive exhaust gas catalysts, as electrical heating conductors, as components in industrial furnaces, in plant construction and in gas turbines because of their excellent oxidation resistance and because of their heat resistance.
• Typical examples are nickel-based alloys with 1 to 3 mass% aluminum and 1 5 to 30% chromium as defined by materials 2.4633 and 2.4851 (DIN material number) and UNS 07214 (Unified Numbering System by ASTM). With high thermal loads and / or low wall thicknesses, however, the aluminum content in these materials is not sufficient to form an aluminum oxide layer over a long period of time. Chromium oxides then form locally, which lead to local corrosion at high temperatures. In addition, chromium oxides evaporate at temperatures above 1000 ° C and can e.g. B. in industrial furnaces lead to contamination of the annealing material.
• EP 051 1 699 B1 describes a process for producing aluminum-alloyed iron-chromium foils, in which an Fe-Cr steel is provided with a thin layer of aluminum. The resulting composite material is rolled to the desired final dimension or to an intermediate dimension, the final, homogeneous material being adjusted by diffusion annealing.
• US-A-5,336, 139 describes a method in which a composite is made by roll cladding with aluminum.
• the base material is a ferritic iron-based alloy.
• ferritic materials often do not have the heat resistance required for many high-temperature applications. If high heat resistance combined with good heat resistance is required, austenitic steels or nickel-based alloys must be used. Austenitic materials, however, have not yet been able to be produced using such processes, since the Diffusion annealing must be carried out at a temperature at which the aluminum coating is already melting.
• the invention is therefore based on the object of developing an economical method with which high aluminum contents can be achieved to produce heat-resistant austenitic materials.
• the object is achieved by a method for producing a composite material with high heat and abrasion resistance, in that a base material made of an austenitic nickel, cobalt or iron-based alloy on one or both sides with an intermediate layer made of a ferritic, a chromium content between (in wt. %) Containing 8 and 25%, chromium steel, to which a layer of aluminum or an aluminum alloy is applied on one or both sides, and this composite material formed from the base material, intermediate layer and aluminum layer by cold and / or hot shaping to the desired intermediate - or final dimension and then diffusion annealed at a temperature above 600 ° C.
• the method according to the invention is distinguished in that an intermediate layer made of a ferritic chromium steel with a chromium content between 8 and 25% by mass is applied between the aluminum coating and the base material. It has surprisingly been found that when an intermediate layer made of a ferritic chromium steel is used, the aluminum first penetrates into the intermediate layer and there immediately forms high-melting iron-aluminum and iron-chromium and iron-chromium-aluminum compounds before the aluminum melts he follows. The diffusion annealing can take place at temperatures above 600 ° C.
• the intermediate layer can consist of a sheet, tape, foil or, in the case of round cross sections, a tube. It is also possible to combine the intermediate layer and the aluminum layer by first coating a chromium steel with an aluminum layer by fire eium finishing or plating and then this two-phase composite is then plated onto the base material. Alternatively, the composite of base material and chrome steel or the composite of aluminum and chrome steel can also be produced directly using the continuous casting process. The thickness of the intermediate layer made of chrome steel, base material and aluminum layer is determined in each case according to the desired thickness and desired properties of the aluminum-rich outer layer.
• This method also has the advantage that special alloy elements, for example oxygen-affine elements, which improve the heat resistance and the adhesion of the protective oxide layers (yttrium, hafnium, zirconium, titanium, silicon, cerium, lanthanum) can be introduced into the intermediate layer and thus close to the surface To be available.
• special alloy elements for example oxygen-affine elements, which improve the heat resistance and the adhesion of the protective oxide layers (yttrium, hafnium, zirconium, titanium, silicon, cerium, lanthanum) can be introduced into the intermediate layer and thus close to the surface To be available.
• Another advantage of this method is that by choosing suitable combinations of base material, intermediate layer and support material, materials with a wide range of property combinations can be produced. For example, special requirements for the strength and physical properties of the base material with special requirements for surface properties such as hardness,
• Corrosion resistance and abrasion resistance can be combined.
• Another advantage of the method according to the invention is that of producing sheets or tubes with aluminum enrichment on one side. From this results there is the possibility of producing semi-finished products for components that have different material requirements due to different process media on both sides (e.g. in heat exchangers).
• the composite material according to the invention can be used for tools for cutting, cutting and grinding.
• Figures 1 to 4 show design examples for the production of a multi-phase composite material with high aluminum contents, as will be explained in more detail in the following examples.
• Fig. 1 shows the structure of the different materials before the diffusion annealing.
• the thickness of the base material, intermediate layer and aluminum layer are determined depending on the desired ratio of the aluminum-rich zone and the base material.
• the intermediate layer consists of a chrome steel with a chrome content between 8 and 25% by mass.
• the aluminum pad consists of an aluminum-silicon alloy or pure aluminum.
• a composite material consisting of a fire-aluminum chromium steel (Fe-Cr18) with additions of yttrium and hafnium was chosen as the cladding.
• the individual layers of the composite material are joined together by cold rolling.
• Cold rolling is carried out to the desired final dimension or an intermediate dimension with or without intermediate annealing.
• the aluminum penetrates completely into the intermediate layer and partially into the base material.
• a connection is created between the base material and the support, as shown in Fig. 2. Diffusion pores occurring in the interface can be eliminated by further shaping.
• the width of the aluminum-rich zone is determined by the time and temperature for the diffusion annealing. Highly heat-resistant and heat-resistant alloys with inadequate scale resistance at very high temperatures are particularly suitable for this process. This includes all nickel and cobalt-based alloys that form chromium oxide layers at high temperatures like the materials 2.4816, 2.4855, 2.4663, 2.4856, 2.4665, 2.4665. 2.4964, 2.4683 and 2.4650 (details: DIN material numbers).
• the material is produced by cold rolling and annealing the composite as described in Example 1.
• heat-resistant steels of the type 1.4876, for example, are available
• High temperature corrosion resistance in hot process gases is significantly improved by the aluminum-containing edge zone.
• the material is produced by cold rolling and annealing the composite material as described in Example 1.
• the one-sided plating of corrosion-resistant materials acc. Fig. 3 comes into question for semi-finished products made of typical corrosion-resistant stainless steels, pure nickel, Ni-Cu alloys and nickel-based alloys, which are exposed on one side to an aggressive aqueous medium (acids or alkalis, sea water) and on the other side to a hot process gas.
• the aluminum-rich surface layer protects the corrosion-resistant material on the process gas side against high-temperature corrosion.
• the material is produced by cold rolling and annealing the composite as described in Example 1.
• Manufacture of a semi-finished product with a round cross-section (tube or rod) with high aluminum contents in the area near the surface by applying aluminum or aluminum-silicon on one side to a corrosion-resistant, heat-resistant or high-temperature-resistant material.
• a tube or a rod is produced by the usual methods of tube or rod production (for example extrusion, cold hammering, vocationalage or drawing) as shown in Fig Composite of base material, Fe-Cr intermediate layer and aluminum layer.
• the diffusion annealing is carried out as described in Example 1.
• Example 1 The preparation is carried out as described in Example 1.
• the composite is rolled onto thin foils with or without intermediate annealing.
• the diffusion annealing is carried out as indicated in Example 1.
• the annealing times and annealing temperatures are chosen so that a homogeneous aluminum content is obtained over the entire film cross section, with the exception of a thin edge zone with an increased aluminum content.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Laminated Bodies (AREA)
• Other Surface Treatments For Metallic Materials (AREA)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Metal Rolling (AREA)
• Coating With Molten Metal (AREA)

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• 1999
  • 1999-09-03 DE DE19942234A patent/DE19942234C1/de not_active Expired - Fee Related
• 2000
  • 2000-07-22 EP EP00951429A patent/EP1226031B1/fr not_active Expired - Lifetime
  • 2000-07-22 AT AT00951429T patent/ATE249337T1/de not_active IP Right Cessation
  • 2000-07-22 AU AU64367/00A patent/AU6436700A/en not_active Abandoned
  • 2000-07-22 WO PCT/EP2000/007045 patent/WO2001017767A2/fr active IP Right Grant
  • 2000-07-22 JP JP2001521539A patent/JP2003508230A/ja active Pending
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