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
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/02—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
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/82—After-treatment
  • C23C22/83—Chemical after-treatment

Definitions

• the invention relates to a method as specified in the preamble of claim 1.
• the invention further relates to a metallic object, e.g. a workpiece with a corrosion and wear-resistant cover layer, in which metals and / or metal compounds can also be embedded.
• the aim of the invention is to apply layers to metal bodies or metallic surfaces which improve the corrosion resistance, wear resistance and other properties of the object.
• Metallic protective layers and coatings in particular of base metal, such as Electrolytically deposited Zn and Cd layers, in largely undamaged condition, guarantee improved resistance to corrosive attacks compared to the untreated base material.
• the abrasion resistance or wear resistance of such layers is not sufficient for some applications, so that there is premature, possibly local, corrosion of objects when they are used in practice.
• the microstructure of the sample material in the hardened state consisted of carbonitrides, martensite and residual austenite, and that the proportion of residual austenite in the structure was significantly reduced by prior phosphating, although the transformation temperatures of the residual austenite remained the same.
• the carbonitriding of a phosphated metal causes complex Fem (C, N, P) n-type compounds to be formed which have an elongated shape.
• the local wear behavior is improved by means of such surfaces on rings, thereby increasing their load-bearing surface or reducing local surface pressures.
• the application of ceramic corrosion protection layers with a layer applied from an immersion bath or by spraying one or more times and a subsequent hardening at elevated temperature is known. However, these layers do not provide active protection against corrosion; the porosity, in particular thin layers, can have an adverse effect and there are difficulties with the application of uniformly thick layers and with regard to the adhesive strength.
• Al powder cathodic corrosion protection
• inorganic binding compound applied and hardened at approx. 350 ⁇ ° C. It turned out that the electrical conductivity of the layer (Al particles are embedded) is too low, that the layer is microporous and relatively soft.
• the previously known layers, with which the properties of the coated workpieces are to be improved, are usually not sufficiently hard or not sufficiently resistant to abrasion and wear. Furthermore, they have an undesirable microporosity and low adhesiveness, which in particular with ductile substrates and high specific mechanical loads leads to the peeling off of the layer with elastic or plastic deformation of the substrate; Furthermore, the body can become brittle on the surface due to the coating process, so that there is only a low fatigue strength, the coating itself inducing a risk of breakage in the object.
• the object of the invention is to avoid the disadvantages mentioned above and to create a metallic object with a corrosion and wear-resistant surface layer or a method for producing the same, the coating with high temperature stability having increased adhesive strength, improved corrosion resistance and best wear properties or Wear resistance in the case of surface-hardened base body, if applicable, and high fatigue strength and resistance to vibration crack corrosion of the object can be achieved.
• these objectives are achieved in that the dried coating and / or surface layer or surface layer of the metallic base material of the objects is (are) hardened in a gas nitriding or gas carbonitriding method.
• a metallic object with a corrosion-resistant and wear-resistant surface layer is essentially characterized in that the base part, which is made of an optionally nitridable or carbonitridable metal or an alloy having such properties, e.g. Nitriding steel, and optionally has a nitrided or carbonitrided surface, a coating with a density of 2 to 20 ⁇ 0 ⁇ ⁇ m from a chromium and / or molybdenum (poly) phosphate compound, in which metallic and / or nitrogen-containing metal compounds existing particles and / or ceramic particles are embedded, supports and is hardened with a gas nitriding or gas carbonitriding process.
• the base part which is made of an optionally nitridable or carbonitridable metal or an alloy having such properties, e.g. Nitriding steel, and optionally has a nitrided or carbonitrided surface, a coating with a density of 2 to 20 ⁇ 0 ⁇ ⁇ m from a chromium
• the procedure for the coating of metallic objects is explained in more detail below.
• the layer is applied to metallic objects, in particular from nitride or. carbonitride-forming metals or alloys, or on objects that are provided with such surface layers.
• Objects made of metal, steel or nitriding steel are advantageously provided with the layers which optionally contain nitridable and / or carbonitridable metals or alloys.
• the grain size of the powder particles is at most 10 ⁇ 0 ⁇ ⁇ m, preferably at most 50 ⁇ ⁇ m, since fine powders form smooth, thin layers and offer many crystallization points when the metal salts dry.
• metals or alloys which can be added to the coating mixture in powder form, there are preferably base metals, e.g. Aluminum or nitride and / or carbonitride formers in question.
• the coating mixture in particular in dispersed form, can contain oxides, in particular metal oxides, or ceramic substances as fillers and plasticizers.
• oxides in particular metal oxides, or ceramic substances as fillers and plasticizers.
• rare earth oxides MgO, ZrO2 Al2O3 and similar ceramic materials come into question.
• These ceramic particles have a grain size of up to 20 ⁇ ⁇ m, preferably up to 10 ⁇ ⁇ m, in particular up to 5 ⁇ m, so that these particles can form dense spherical packs with the metal powders.
• the metal powders and ceramic particles are homogeneously distributed in the aqueous solution, e.g. by stirring.
• the coating mixture can contain several different ceramic materials and / or several different metals or alloys, for example also high-alloy stainless steels in powder form.
• This coating mixture is applied to pure metallic surfaces in any coating process, for example spraying, dipping, immersion, brushing, rolling, in one or more layers.
• the application takes place in particular in a corresponding thickness. This can be the case if the layers are too thin occur that the surface is not sufficiently covered; layers that are too thick would hinder nitriding or carbonitriding of the substrate or the surface layer of the object.
• It can be provided to dry each of the applied layers individually or for the entire applied layer. Drying is preferably done with dry hot air at around 40 ⁇ to 80 ⁇ C.
• the applied layer optionally containing nitridable or carbonitridable metals or alloys, is hardened or hardened by a nitriding or carbonitriding process; at the same time, the surface of the object supporting the layer can be hardened in this gas nitriding process or gas carbonitriding process. After drying, the layer forms a porous matrix in which the spherical metal pigments are possibly held.
• this microporous matrix can be penetrated by the process gas, which effects nitriding or carbonitriding at least one surface layer of the base material, curing of the inorganic binder (the layer) and / or nitriding or carbonitriding of the metals in the applied dried coating.
• the surface of the base material and the applied layer can thus be hardened (optionally simultaneously with nitriding or carbonitriding of the metals and / or alloys contained in this layer) in one operation.
• compressive stresses arise in the surface of the substrate and the micropores are closed due to an increase in the volume of the metal pigments in the applied layer.
• Layers of this type are distinguished by very high temperature stability, excellent corrosion protection, high adhesive strength, good sliding and rubbing properties and good wear properties, with high fatigue strength and Vibration crack corrosion resistance of the coated body can be achieved.
• any method can be used as the gas nitriding or gas carbonitriding method, e.g. Ion nitriding, in question.
• the temperatures to be observed are between 480 Morris ° and 90 ⁇ 0 ⁇ ° C.
• the metal powder particles and / or the surface of the base material are nitrided or carbonitrided, in particular at the same time, and the layer matrix is hardened.
• spherical metal pigments are advantageous because a denser packing is possible and as a result there is a better electrical conductivity between the substrate and the base metal and thus a better corrosion resistance.
• the dense coating has a heat resistance, especially up to 140 ⁇ 0 ⁇ ° C, which is only limited by the vapor pressure of the stored or the underlying metals.
• compressor blades made of titanium or Cr steel compressor blades can be provided with such coatings, in particular to increase the resistance to vibration crack corrosion. Since this coating is dense and does not allow oxidation, a so-called titanium fire is prevented even with titanium bodies.
• the layer and the base body are treated in one work step, there are maximum advantages. With a nitride or. Carbonitride formation is associated with an increase in volume, as a result of which the micropores of the layer are closed and compressive stresses arise in the surface of the substrate. This also improves the fatigue strength or fatigue strength of the component.
• the applied layer has a very high hardness due to the embedded metal nitride or carbonitride. Since this layer is on a hardened surface of the Object rests or is carried by this, it is not easy to press in the coating or cause damage. In addition, the applied layer has good adhesive properties.
• the layers according to the invention have a particularly high hardness and adhere well to the base material, which is embossed in its surface layers for additional corrosion resistance, improved hardness and improved mechanical long-term properties.
• Compressor blades were nitrided to improve the fatigue strength in the ammonia gas flow and then protected against corrosion.
• the steel nitrided at about 50 ⁇ ° to 520 ⁇ ° C, for example 34 Cr Al 6, obtained a surface hardness of HV 5 110 ⁇ 0 ⁇ kp / mm2 after 20 ⁇ hours.
• metal-ceramic protective layers were then produced by baking on the base body at about 350 ° C.
• the improved fatigue strength due to the gas nitriding by the following coating process with the metal-ceramic corrosion protection coating was not significantly improved, it could be determined in the procedure according to the invention that the metal-ceramic protective layers, which could be applied in different layer thicknesses, and the metal body (e.g.
• Automobile parts e.g. All types of fasteners, lock parts, struts and similar parts machined or coated.
• the procedure according to the invention is particularly suitable for all steel components that can be hardened in gas nitriding processes and should have good corrosion and wear protection. Corrosion protection is considerably increased, since a metal-ceramic protective layer based on base metals becomes considerably more conductive during this treatment and the specific electrical resistance of the layer is below 10 ⁇ ohms, so that the layer or the embedded metal pigments can become effective as a sacrificial anode in the corrosive climate . can. It was also found that, in comparison with parts coated according to the prior art, the layer of the object had hardness values which are at least 50%, preferably 75%, higher than that of the base material.
• the coating composition can improve its properties (thermal insulation, oxidation protection, corrosion protection) Cr2O3, TiO2, Al2O3, MgO, SiO2, ZrO2, CaO, CaCO3, Y2O3, MgO, HfO2, amorphous and / or crystalline boron, SiC, MoSi2, sintered TiN, ZrN, TiB2, ZrB2, and / or similar substances are added individually or together.
• the layer as a metal or alloy powder preferably Al, Ni, Mg, C, Cr, W, P, Mo, Ni, Si, B, Fe, Nb, Zn, ZrO CaO, HfO, Al O and / or MgO added, e.g. Celsit V (C 1.1, Cr 2.8, W 4.5, balance cobalt), Celsit 50 ⁇ P (C 2, Cr 28, Mo 3.7, Ni 6.5, W 10 ⁇ , balance cobalt), niborite 6 (C 0 ⁇ , 8, Si 4.3, Cr 1.6, B 3.5, Fe 45, balance Ni), Ledurit 76-P (C 5.4, Si 1.4, Cr 12, B 1, V 6, Nb 6.5, rest Fe).
• Celsit V C 1.1, Cr 2.8, W 4.5, balance cobalt
• Celsit 50 ⁇ P C 2, Cr 28, Mo 3.7, Ni 6.5, W 10 ⁇ , balance cobalt
• niborite 6 C 0 ⁇ , 8, Si 4.3, Cr 1.6, B 3.5, Fe 45
• the binder used for the layer can contain filler metal powder from 20% by weight to 65% by weight, preferably 50% by weight, salts from 2.5 to 22% in the dry matter and ceramic proportions from 2.5 to 50% in the dry matter .
• the duration of the nitriding or carbonitriding is determined by the depth of penetration or the desired layer thickness and is usually 1 to 10 ⁇ 0 ⁇ hours, preferably 1 to 20 ⁇ hours.
• ceramic layers can be formed on nitridable or carbonitridable base bodies or nitridable or carbonitridable layers on optionally nitridable or carbonitridable base bodies. It should be noted that most steels can be nitrided or carbonitrided within certain limits, or that Fe-nitrides, Cr-nitrides etc. can be formed.
• the inorganic ceramic outer layer or the binder of the outer layer essentially consists of (poly) phasphate compounds of chromium and / or molybdenum, which are cured at the elevated temperatures of a nitriding or carbonitriding process.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Treatment Of Metals (AREA)
• Other Surface Treatments For Metallic Materials (AREA)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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• 1988
  • 1988-09-10 DE DE3830848A patent/DE3830848C1/de not_active Expired
• 1989
  • 1989-08-25 ES ES198989115665T patent/ES2038385T3/es not_active Expired - Lifetime
  • 1989-08-25 EP EP89115665A patent/EP0359002B1/de not_active Expired - Lifetime
  • 1989-08-25 DE DE8989115665T patent/DE58903648D1/de not_active Expired - Fee Related
  • 1989-08-25 AT AT89115665T patent/ATE86310T1/de not_active IP Right Cessation
• 1993
  • 1993-03-04 GR GR920402977T patent/GR3007211T3/el unknown

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