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 earth connection 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 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; moreover, the body can become embrittled by the coating process, so that only one low fatigue strength is given, whereby the coating itself induces a risk of breakage in the object.
• the object of the invention is to avoid the disadvantages mentioned above and to provide bodies with a coating which can be produced economically, which improves the properties of the coated article, has good adhesive properties, etc.
• the procedure for the coating of metallic objects e.g. Workpieces, tools, moldings or the like, explained in more detail.
• 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.
• it contains metal powder (preferably spherical grains), in particular water-atomized or preferably gas-atomized metal powder, which are advantageously kept in suspension with the aid of surfactants.
• the grain size of the powder particles is a maximum of 100 ⁇ m, preferably a maximum of 50 ⁇ m, since fine powders form smooth, thin layers and offer many crystallization points when the metal salts dry.
• Suitable metals or alloys, which can be added to the coating mixture in powder form are preferably base metals, for example aluminum or nitride and / or carbonitride formers.
• 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 tight ball 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 metallically pure surfaces in any coating process, for example spraying, dipping, immersion spinning, brushing, rolling, in one or more layers. The application takes place in particular in a corresponding thickness. If the layers are too thin, the case may occur that the surface is not adequately covered; layers that are too thick would hinder nitriding or carbonitriding of the substrate or the surface layer of the object.
• each of the applied layers individually or for the entire applied layer. Drying is preferably done with dry hot air at about 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 a nitriding or carbonitriding hardening of at least one surface layer of the base material, a hardening of the inorganic binder (the layer) and / or a 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 the coating body achieving high resistance to alternating strength and vibration corrosion.
• 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 ° and 900 ° 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 1400 ° 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 in particular to increase the Vibration crack corrosion resistance, can be provided with such coatings. 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 layer applied has a very high hardness due to the embedded metal nitride or carbonitride. Since this layer rests on or is supported by a hardened surface of the object, the coating cannot be pressed in or damaged as a result. In addition, the applied layer 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 Daure resistance in the ammonia gas flow and then protected against corrosion.
• the steel nitrated at about 500 ° to 520 ° C., for example 34 Cr Al 6, obtained a surface hardness of HV 5 1100 kp / mm2 after 20 hours.
• metal-ceramic protective layers were then produced by baking on the base body at about 350 ° C. Due to the baking process for the metal-ceramic layers, however, part of the nitrogen content of the metal surface diffused and the surface hardness decreased after the metal-ceramic coating process Values that were below HV 500 kp / mm2.
• 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 which can be hardened in gas nitriding processes and which should have good protection against corrosion and wear.
• the corrosion protection is increased considerably because a metal-ceramic protective layer based on base metals becomes considerably more conductive in this treatment and the specific electrical resistance of the layer is below 10 ohms, so that the layer or the embedded metal pigments can or can become effective as a sacrificial anode in the corrosive climate.
• 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 individually or together preferably Al, Ni, Mg, C, Cr, W, P, Mo, Ni, Si, B, Fe, Nb, Zn, ZrO CaO, HfO2, Al2O3 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, balance Ni
• the binder used for the layer Filler metal powder from 20% to 65% by weight, preferably 50% by weight, salts from 2.5 to 22% in the dry matter and ceramic parts 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 100 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) phosphate compounds of chromium and / or molybdenum, which are cured at the elevated temperatures of a nitriding or carbonitriding process.

Landscapes

• 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)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Other Surface Treatments For Metallic Materials (AREA)
• Chemical Treatment Of Metals (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6362705

Family Applications (1)

Country Status (5)

Cited By (7)

Citations (2)

Family Cites Families (1)

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

Patent Citations (2)

Non-Patent Citations (3)

Also Published As

Similar Documents

Legal Events