Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/48—After-treatment of electroplated surfaces
  • C25D5/50—After-treatment of electroplated surfaces by heat-treatment
• • 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
  • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
  • C23C10/02—Pretreatment of the material to be coated
• • 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
  • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
  • C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
• • 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
  • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
  • C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
  • C23C10/34—Embedding in a powder mixture, i.e. pack cementation
• • 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
  • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
  • C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
  • C23C10/34—Embedding in a powder mixture, i.e. pack cementation
  • C23C10/52—Embedding in a powder mixture, i.e. pack cementation more than one element being diffused in one step
• • 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
  • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
  • C23C10/60—After-treatment

Definitions

• the invention relates to a method for modifying a substrate, preferably a metallic substrate or a metallized substrate, comprising a diffusion layer, diffusion-coated metal substrates comprising this diffusion layer, workpieces comprising such modified substrates and methods for producing these workpieces.
• the diffusion layer forms a hard, tough, ductile, oxidation-resistant and resistant to aggressive media coating layer.
• the workpieces according to the invention are preferably used in general mechanical engineering, the construction and automotive industry, aviation and general industry.
• the DE-A-10116762 describes the production of diffusion layers with high contents of aluminum and titanium and their use as Corrosion protection for metallic materials (eg Stahl Wst. Nr. 1.4841) in reducing, sulfiding environments with high carbon activities at temperatures up to at least 700 ° C, where the layer in the codiffusion process using the diffusion elements Al and Ti as pure metal powder in the weight ratio 1: (0 , 1-5) is produced.
• the process provides for concurrent indiffusion of Al and Ti in a powder packing process. The deposition takes place without prior application of intermediate layers. On the substrate material no TiAl alloy is produced, but it formed depending on the composition of the substrate mixed phases of Al, Cr, Fe, Ni and Ti.
• the DE-A-10116762 discloses a method of forming Al / Ti diffusion layers on a steel substrate by a powder packing method. Depending on the substrate composition, mixed phases of Al, Cr, Fe, Ni and Ti are formed.
• the DE-A-10101070 discloses a method for gas phase diffusion coating with metallic components. Al and / or Cr and optionally further elements Si, Hf and Y can be used as the coating metal.
• the platinum intermediate layer galvanically on the Substrate surface is deposited, the coating with Al and / or Cr via an out of pack CVD method.
• the DE-A-4215664 discloses a method of applying metallic interlayers prior to an aluminum diffusion coating.
• the intermediate layers are applied to reduce the layer stresses.
• platinum metals or their alloys hafnium or rare earth metals are dusted.
• the DE-A-4035790 relates to a method for powder packing of hollow bodies. Qualitative details of the coating or the presence of intermediate layers does not disclose this document.
• the EP-A-0906967 discloses the use of titanium and aluminum as an anti-corrosion coating on steel.
• the WO-A-2005/045102 discloses the coating of a metallic substrate by electrodeposition of one or more layers containing at least one metal and / or one metal alloy.
• the outermost galvanic layer consists of aluminum, magnesium, tin or mixtures thereof and / or alloys thereof.
• the outermost layer contains an aluminum / magnesium and / or an aluminum / tin alloy.
• Also disclosed is the formation of one or more intermediate layers of metals selected from the group consisting of iron, iron / nickel, tin / nickel, nickel, cobalt, copper, chromium, molybdenum, vanadium or alloys of these metals.
• the heat treatment takes place at a temperature of 400 to 1000 ° C.
• the document discloses the electrodeposition of the individual layers (intermediate and outer layer) followed by a further step of the heat treatment.
• the WO-A-2006/013184 discloses a method of making coated workpieces of a light metal or a light alloy, which method comprises electrodepositing one or more layers of at least one metal or metal alloy selected from the group consisting of aluminum, magnesium, zinc, and subsequent heat treatment 200 ° C to 800 ° C.
• the document discloses two embodiments, namely the coating of an aluminum or aluminum alloy substrate with an intermediate layer of magnesium, zinc or an alloy thereof, followed by an outer layer of aluminum, magnesium or an alloy thereof.
• the document discloses coating a magnesium or magnesium alloy substrate with an intermediate layer of aluminum, zinc or an alloy thereof, followed by an outer layer of aluminum, magnesium, zinc or an alloy of these metals.
• a disadvantage in the application of cover layers is that too rapid depletion of the elements deposited by the packing or CVD method in the cover layer takes place by strong diffusion towards the substrate and the protective layer therewith breaks down prematurely.
• Kirkendall pores are formed in particular when strongly different diffusion velocities or diffusion coefficients occur during the interdiffusion of at least two different elements via an interface. It thus arises on the side of the interface on which the diffusion current or the removal of the elements via the interface is considerably stronger, the so-called Kirkendall pores. Furthermore, unfavorable effects are found, for example, on chromium plating layers on steels, resulting in hard and cracked alloy layers.
• the object has been achieved by a method for modifying a substrate with a diffusion layer, wherein the Diffusion layer is formed from a disposed on the substrate layer of Ni metal, NiW, NiMo or NiCo alloys and an optionally disposed thereon galvanic Cr layer as an intermediate layer by subsequent application of an outer layer comprising Al and / or Cr and / or Si and / or Ti by a packing process or by chemical vapor deposition (CVD) with simultaneous thermal treatment.
• the Diffusion layer is formed from a disposed on the substrate layer of Ni metal, NiW, NiMo or NiCo alloys and an optionally disposed thereon galvanic Cr layer as an intermediate layer by subsequent application of an outer layer comprising Al and / or Cr and / or Si and / or Ti by a packing process or by chemical vapor deposition (CVD) with simultaneous thermal treatment.
• CVD chemical vapor deposition
• the invention further relates to a diffusion-coated substrate, preferably metallic substrate or metallized substrate, which is obtainable by the method according to the invention.
• the invention also relates to a workpiece comprising the diffusion-coated substrate according to the invention, preferably metallic substrate or metallized substrate.
• the invention also relates to a diffusion layer for placement on a substrate, preferably on a metallic substrate or metallized substrate, wherein the diffusion layer is obtainable by the method according to the invention.
• the invention further relates to the use of the diffusion layer according to the invention.
• the diffusion layer obtained according to the invention may also be referred to as cover, coating or functional layer.
• the components are mixed into a powder mixture of the activator, halogen compounds (eg NH 4 Cl), donor (Al powder, Si powder, Ti Powder, Cr powder, or mixtures thereof) and from the inert filler (Al 2 O 3 ) packed and treated under inert gas atmosphere for several hours at high temperatures.
• halogen compounds eg NH 4 Cl
• donor Al powder, Si powder, Ti Powder, Cr powder, or mixtures thereof
• Al 2 O 3 inert filler
• the simultaneous thermal treatment during the packing or CVD process to form the diffusion layer at a temperature of 500 ° C to 1600 ° C, preferably from 550 ° C to 1500 ° C, more preferably from 600 ° C to 1450 ° C take place.
• the thermal treatment can be carried out for a period of 0.1 h to 250 h, preferably from 2 h to 16 h, particularly preferably from 3 h to 12 h.
• a particular embodiment of the method according to the invention is characterized in that the outer layer by application via the packing or CVD method, preferably of Al, Cr, Si, Ti or a mixture thereof, by simultaneous thermal treatment at a temperature of 500 ° C to 1600 ° C for a certain time, for example, as indicated above, is generated.
• the packing process is carried out in a batch process (rack or drum process).
• the substrate is electrically conductive and preferably selected from the group consisting of metallic substrates, metallized substrates, conductively rendered conductive by conductivity, intrinsically non-conductive materials, electrically conductive organic polymers and made conductive by metal or graphite deposits organic polymers.
• substrate is mentioned below, it means the above-mentioned electrically conductive substrate.
• Suitable substrates can thus for example be provided with metal layers, including conductive paints, body of a per se electrically non-conductive material, such as organic polymers or inorganic compounds (salts, etc.) or mixtures thereof, or even substrates entirely of a metal and by a Metal or graphite content (eg metal particles, metal particles, graphite powder) made electrically conductive, not conductive per se substrates, such as substrates of organic polymers or inorganic compounds.
• metal layers including conductive paints, body of a per se electrically non-conductive material, such as organic polymers or inorganic compounds (salts, etc.) or mixtures thereof, or even substrates entirely of a metal and by a Metal or graphite content (eg metal particles, metal particles, graphite powder) made electrically conductive, not conductive per se substrates, such as substrates of organic polymers or inorganic compounds.
• the substrate preferably the metallic substrate or the metallization of the substrate, consists of unalloyed, low-alloyed or high-alloy steel, cast iron, pure Cu, a Cu-based alloy, pure Ni, a Ni or Co base alloy, pure Ti, a Ti alloy or ⁇ -TiAl, the metals of W, Mo, Ta, Nb, Zr, V, Hf, Ru, Rh, Os, Ir, Pd, Pt, Re or alloys, which as a main component of the Elements W, Mo, Ta, Nb, Zr, V, Hf, Ru, Rh, Os, Ir, Pd, Pt, Re.
• the intermediate layer of Ni, NiW, NiMo or NiCo alloys and / or the optional further intermediate layer of Cr may additionally contain P and / or N and / or C.
• the outer layer applied thereto is not made of chromium or chromium.
• the intermediate layers serve to control the diffusion or alloying process and can be used for specific modification of the layer structure, the layer composition and thus the layer properties and the properties of the interdiffusion zone between substrate and alloyed functional layer.
• the interlayers may further prevent the formation of Kirkendall pores and may impede or prevent interdiffusion between the substrate and the outer layer.
• this essentially means that alloys are formed from the elements which have been applied by the packing or CVD method and from the elements involved in the construction of the intermediate layer, and components of the substrate only to a limited extent or not at all
• prevents too rapid depletion of the applied via the packing or CVD process elements in the cover layer takes place by strong diffusion towards the substrate and the protective layer collapses prematurely with it.
• the interlayer system consists of a layer of Ni, NiW, NiMo or NiCo alloys and another, optionally arranged thereon layer of Cr, preferably in sandwich construction.
• the at least one intermediate layer disposed on the substrate may preferably be thermally treated at 120 ° C. to 1600 ° C. before application of the outer layer.
• the Duration of treatment of the intermediate layer before application of the chromium layer may be from 0.1 h to 250 h, preferably from 2 h to 16 h, particularly preferably 3 h to 12 h.
• a further heat treatment of the entire layer structure can be carried out as described above in connection with the subsequent thermal treatment.
• the (total) thickness of the intermediate layer (s) can be from 0.1 ⁇ m to 500 ⁇ m, preferably from 1 ⁇ m to 100 ⁇ m, particularly preferably from 2 ⁇ m to 50 ⁇ m.
• the at least one intermediate layer can be deposited via a discontinuous or continuous chemical or electroplating process, a PVD (Physical Vapor Deposition) process or via decomposition reactions of volatile metal compounds, preferably metal-alkyl compounds.
• Volatile metal compounds are understood to mean those which have a sublimation or boiling point of 300 ° C. or less at normal pressure (101.325 kPa).
• metal alkyls C 1 -C 10 alkyl
• metal carbonyls metal ⁇ complexes and metal compounds which have several of these structures mixed.
• the outer layer formed by the process according to the invention and contained in the diffusion layer structure comprising Al and / or Cr and / or Si and / or Ti is characterized in that it contains, in addition to the metals Al and / or Cr and / or Si and / or Ti contains as alloying elements elements of the / the intermediate layer (s) and optionally the metal substrate.
• the intermediate layer (s) may include a portion of the element (s) of the outer layer (Al and / or Cr and / or Si and / or Ti) and the substrate as the alloying ingredient. In the presence of several intermediate layers of different elements, a diffusion of the elements between the intermediate layers can also take place.
• the diffusion layer is defined by the state which, due to the method according to the invention, is determined by the interdiffusion between the individual layers associated with the method Substrate-near layers and the substrate sets. This results in an alloying of the elements of the outer layer, the / the intermediate layer (s) and the metal substrate or the metallization of the substrate.
• the diffusion layer is one or more mixed crystal layers and / or one or more intermetallic phases. If the diffusion layer is composed of mixed crystal layers and / or intermetallic phases with phase width, it may be a multilayer gradient layer structure in which the composition of an axis perpendicular to the layer plane changes continuously.
• a structure is formed, in the outside, ie as the uppermost layer, a ⁇ -NiAl phase (about 50 atomic percent Al, about 50 atomic percent Ni) and further inside, an Al poorer nickel aluminide phase. Above the substrate, a ⁇ -Fe or Ni phase forms, which prevents the formation of Kirkendall pores on the ferritic substrate.
• the diffusion layer formed by the method according to the invention on the substrate, preferably on the metallic substrate or metallized substrate, comprising the original outer layer and the original intermediate layer (s) has a layer thickness of 0.2 ⁇ m to 2 ⁇ m, preferably of 2 microns to 400 microns, more preferably from 4 microns to 200 microns on.
• coated substrates preferably metallic or metallized substrates, such as workpieces, moldings and components can be produced, which are characterized by the absence of cracking and / or Kirkendall pores.
• the workpieces are preferably used in general mechanical engineering, the construction and automotive industry, aviation, the chemical and petrochemical industry and general industry. Concrete examples of workpieces and components are bearings, as well as tools for cold and hot work, in particular casting tools, mold punches, forming tools, wires, sheets, screws, nuts, machine components, Engines or engines or parts thereof eg turbine blades or pistons.
• the diffusion layer produced by the method according to the invention on substrates can be used as protection against oxidation, scale protection, hot gas corrosion protection, protection against metal dusting, protection against sulfidation, corrosion protection, wear protection or to increase the abrasive resistance Reduction of adhesion, to improve the tribological properties, to protect against aggressive molten metals (Zn, Al, Mg or mixtures thereof), used as a non-stick coating against molten metals, in particular Zn, Al, Mg or mixtures thereof.
• molten metals Zn, Al, Mg or mixtures thereof
• TiAl is applied in a temperature range of 700 ° C - 1200 ° C to a 20 ⁇ m hot-dip galvanized hot-work steel (material number 1.2344 / 1.2343) and the entire layer structure is simultaneously diffusion-heat treated.
• This layer structure is roughly subdivided into 3 parts, with the uppermost layer being rich in Ti and Al in addition to Ni.
• This is followed by another layer below, characterized by thread-like Ti-rich precipitates. Below this follows the Ni-rich intermediate layer over the substrate, which makes this structure on a ferritic substrate possible and thus can offer a good sulfiding protection on ferritic materials.
• a hot-working steel (material number 1.2344 / 1.2343) with a thickness of 20 ⁇ m and then 20 ⁇ m electroplated steel is applied by means of a packing process in the temperature range from 600 ° C to 1200 ° C and the entire layer structure is simultaneously diffusion heat treated.
• a ternary alloy structure of Al, Cr and Ni forms on the surface.
• Al-Cr-Ni layer structures are known from the aerospace industry and are there because of very complicated Co-deposition of Al and Cr via packing or CVD method not used.
• the Ni-rich layer which remains over the substrate, the stability of the layer structure is ensured by thermal aging and also prevents the formation of Kirkendall pores.
• TiAl is applied in a temperature range of 700 ° C - 1200 ° C to a 20 ⁇ m electroplated and then 20 ⁇ m electroplated hot-working steel (material number 1.2344 / 1.2343) and the entire layer structure is simultaneously diffusion-heat treated. On the surface, a ternary alloy structure of Ti, Al, Cr and Ni is formed. These Ti-Al-Cr-Ni layer structures are considered to be very stable in sulfiding environments due to their Ti content. The Ni-rich layer, which remains above the substrate, ensures the stability of the layer structure upon thermal aging and also avoids the formation of Kirkendall pores.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Electrochemistry (AREA)
• Chemical Vapour Deposition (AREA)
• Other Surface Treatments For Metallic Materials (AREA)

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Cited By (4)

Citations (3)

• 2006
  • 2006-09-11 EP EP06120446A patent/EP1900842A1/fr not_active Withdrawn

Patent Citations (3)

Non-Patent Citations (1)

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