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
  • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/50—Multilayers
  • B05D7/51—One specific pretreatment, e.g. phosphatation, chromatation, in combination with one specific coating
• • 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
  • C23C24/00—Coating starting from inorganic powder
  • C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
• • 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

• the invention relates to a method for applying an inorganic coating to an electrically conductive body, in particular to a metallic workpiece.
• a wide variety of methods for applying an inorganic coating to an electrically conductive body are known from practice.
• the coating is built up under the action of temperature, which causes a reaction of the coating medium after its application to the body or the surface of the body.
• the reaction leads to the formation of an essentially inorganic network.
• different reaction temperatures are required. Such reactions differ significantly in terms of thermodynamics and kinetics from reactions with organic coating media.
• the coating described often serves to protect the often metallic body against corrosion.
• the reaction described above usually takes place in convection ovens after application of the coating medium.
• the reaction temperature is, depending on the coating medium between 180 ° C and 300 ° C. At these temperatures, reacts the coating medium from the coating.
• the present invention is therefore based on the object of specifying a method for applying an inorganic coating to an electrically conductive body, in which a precisely controllable temperature profile with short temperature change processes is made possible in an economical and energy-saving mode of operation.
• a method for applying an inorganic coating to an electrically conductive body is characterized by the following method steps:
• the body is made available.
• the body is then optionally degreased and / or chemically pretreated and / or blasted, for example sandblasted.
• the surface of the body can be prepared for the coating if necessary.
• a coating medium is then applied to at least the surface area of the body to be coated.
• At least the surface area of the body to be coated is then inductively heated to a reaction temperature before and / or during and / or after the application of the coating medium.
• this inductive heating according to the invention an energetically very particularly advantageous heating of the body is achieved, since only the surface area to be coated and not necessarily the entire body is heated.
• eddy currents are generated in the body which, due to the electrical resistance of the body material, cause the body to heat up. Energy losses due to heating a heating medium in the form of, for example, circulating air and its inevitable heat radiation are excluded.
• the heating is consequently brought about in a targeted manner in the body or in its surface area, with a suitably controllable temperature profile with it by suitably controlling the induction device resulting short temperature change processes is enabled.
• the body is warmed up from the inside by the inductive heating, whereby a highly efficient heating of the coating medium is also effected.
• the heating process according to the invention can be regulated in a simple manner by means of inductive heating via the energy supply to the associated induction heating device, which in addition to a short heating phase also results in extremely short reaction times to temperature control or changing processes due to the direct inductive energy transfer principle. Due to the direct heating of the surface area to be coated, an economical and energy-saving mode of operation is realized without the need for an extensive convection oven device.
• the surface area of the body to be coated can be heated to a reaction temperature in a simple manner before and / or during and / or after the application of the coating medium. This ensures a high degree of flexibility of the method.
• the body After the coating medium has reacted completely for coating, the body is cooled as the last process step of the process according to the invention.
• the body can be exposed to room temperature, which ultimately leads to an independent cooling of the body.
• cooling can also be carried out by an active method step using a cooling medium.
• the method according to the invention specifies a method for applying an inorganic coating to an electrically conductive body, in which a precisely controllable temperature profile with short temperature change processes in an economical and energy-saving mode of operation is realized.
• At least the surface area of the body to be coated could be in front of the Application of the coating medium to be heated inductively to a preheating temperature.
• the preheating temperature could be below the reaction temperature.
• reaction medium of the coating medium for coating could take place with the participation of water.
• a separate supply of the amount of water required for the reaction would be conceivable.
• the water supply could also be carried out in a simple manner by automatically removing the water from the atmospheric humidity of the surrounding atmosphere.
• the coating medium and thus the coating could have pigments of preferably zinc and / or aluminum. This would provide active corrosion protection through the coating medium.
• the coating medium could have additives such as internal lubricants, viscosity regulators, leveling agents and / or anti-crater additives. There are no limits to the individual design options for the coating medium.
• the coating medium could have a binder composed of at least one organic and / or inorganic metal compound.
• Metal compounds containing titanium, zirconium, chromium, boron, aluminum, silicon, cobalt, nickel or magnesium are particularly favorable.
• the aforementioned elements can be present individually or in combination in the metal compound.
• a high molecular aminically crosslinked epoxy / phenoxy binder is advantageous as a binder for the coating medium.
• the binders could be dissolved in an optionally commercially available organic solvent and / or in water.
• the preheating temperature could be between room temperature and the Boiling temperature of the solvent or water. This would ensure that the solvent or water escapes in a controlled manner from the layer that builds up, thus achieving an optimal compaction of the layer.
• Such preheating could take place both before the application of the coating medium and after the application. In the latter case, a gradual heating of the surface area of the body to be coated would then be realized with the coating medium already applied.
• the heating of the body to be coated and the application of the coating medium could take place in two different parts of the system, there is sufficient time in this case - with the body preheated before the application of the coating medium - after the application of the coating medium, so that the solvent or the water to Protection of the surface below the boiling temperature can escape while moving the body into the heating area. As soon as the solvent has escaped, the temperature of the surface to be coated can be brought to the necessary reaction temperature in a few seconds in order to achieve the optimal function and quality of the coating.
• the inductive heating of the body could only take place within partial areas.
• Such targeted heating of only the areas to be coated makes it possible, or only slightly, to heat adjacent and / or non-electrically conductive substances or surface areas. It would then only be possible to heat these areas by conduction.
• the targeted introduction of the heat further enables the coating of individual parts of an overall device on the one hand and complete entire devices on the other hand. For example, fully assembled bearings can be coated as a whole or only at selected locations.
• the body could be cooled partially or entirely during and / or after the heating with a suitable cooling medium.
• a gaseous or liquid cooling medium in the form of, for example, air, water or oil could be used as the cooling medium. This would easily protect temperature-sensitive areas from the effects of temperature. Only by using inductive heating is it possible to cool temperature-sensitive points or areas of the body to be coated at the same time as the surface areas to be coated are heated with air or liquid cooling media.
• the method according to the invention with inductive heating requires a shortening of the reaction time with a significant increase in the crosslinking temperature in order to achieve a fully crosslinked coating which only fully exhibits its favorable properties to the full extent. Too high a temperature can, however, destroy the network or the pigments and additives embedded in it. As a result, cooling the body at the appropriate time can have different positive effects. The cooling could only be used after the reaction temperature had been reached.
• the coating could have a cathodic effect.
• the coating could be electrical and / or thermally conductive in addition to or as an alternative to the cathodic effect. Almost metallic conductivity could be achieved.
• the coating could have a layer thickness of approximately 2 to 30 micrometers. If necessary, extreme corrosion protection would be achieved in the thinnest layers. In a further advantageous manner, the coating could also be weldable.
• the coating could have no heavy metals and in particular be free of chromium VI and cadmium.
• the control of the layer thickness could be set on the one hand via the viscosity of the coating medium and on the other hand or additionally via mechanical removal. With regard to mechanical removal, this could be done in a simple manner by spinning. All other known coating application methods can also be used.
• an additional organic cover layer could be applied to the coating.
• the composition of the cover layer could be matched to the composition of the coating with a view to the best possible adhesion.
• the binder has a significant influence.
• high-molecular aminically crosslinked epoxy / phenoxy binders of the cover layer are particularly favorable.
• the coating medium and / or the top layer are applied in a particularly simple manner by spraying, in particular electrostatic spraying, or by an immersion process.
• the immersion process in connection with centrifuging is particularly used for bulk goods.
• the heating and / or cooling or cooling could be computer-controlled. This would allow a fully automated process.
• the coating parameters could be controlled in a particularly simple manner by means of the alternating voltage frequency of the inductor and / or the induction duration and / or the reaction temperature.
• the method according to the invention can be used with all known technologies.
• an organic cover layer can serve the coloring, the insulation, the setting of a constant coefficient of friction and the improvement of the contact corrosion resistance.
• transistorized converters are used as induction devices, since these particularly favor the implementation of precise computer-controlled processes.
• the method according to the invention for applying an inorganic coating has a high protective action against chemical and electrochemical corrosion as well as contact corrosion of e.g. Steel versus aluminum. Furthermore, the coating has achieved high resistance in salt spray, condensation and kestemich tests. Hydrogen embrittlement does not occur on the coated surfaces.
• Reference number 1 denotes the first method step in which the body is made available.
• Process step 2 consists of an optional degreasing and / or chemical pretreatment and / or blasting of the body, for example sandblasting. If the body provided in step 1 no longer requires any further preparation, this method step 2 can be omitted.
• a coating medium is applied to at least the surface area of the body to be coated.
• the coating medium could also be applied to surface areas of the body that are not to be coated, which would result in the subsequent removal of the coating medium from the surface areas that are not to be coated.
• the subsequent inductive heating, identified by reference number 4, to at least the surface area of the body to be coated to a reaction temperature could take place before and / or during and / or after the application of the coating medium.
• preheating of at least the surface area to be coated is possible before the coating medium is applied. This could promote the escape of solvents that are not required in the crosslinking reaction of the coating medium.
• the coating usually has a high thermal resistance up to approx. 350 ° C. Too high a temperature can destroy the coating. If the temperature is too high, especially over a long period of time, it is also detrimental to heat-sensitive areas of the body to be coated, so that short-term induction treatment is particularly advantageous. In any case, care must be taken to ensure that a maximum temperature is not exceeded. Furthermore, it is only possible to use inductive heating to cool temperature-sensitive areas of the bodies to be coated at the same time as the coated areas are heated with air or liquid media.
• step 5 the coating medium reacts for coating.
• Inductive heating enables a fully networked coating or protective layer to be formed quickly with less effort than conventional air-conditioning technology.
• This rapid reaction thermodynamics and kinetics if the reaction time is shortened, requires a significant increase in the crosslinking temperature in order to achieve a fully crosslinked layer which only fully exhibits the properties mentioned.
• Temperature control is advantageous because too high a temperature can destroy the network or the pigments and additives embedded in it.
• the body is cooled in the last method step of an exemplary embodiment of the method according to the invention, designated by reference number 6. This can be done, on the one hand, by passive cooling in, for example, ambient air, or by active cooling using a special cooling medium such as water or oil.
• Inductive heating is ideally suited for the reaction of the coating media on partially coated, more or less large bodies, for the reaction of bodies coated over the entire surface or for coating bulk goods.
• the method described is advantageous in that multiple coatings are unnecessary due to defects and contact points.
• the spraying of preheated bulk goods while moving the bed ensures a particularly uniform coating without defects when coating such bodies.
• preheated bodies When using a dipping process to apply the coating medium, preheated bodies can also be dipped.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• General Chemical & Material Sciences (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Non-Insulated Conductors (AREA)
• Glass Compositions (AREA)

Applications Claiming Priority (5)

Publications (2)

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• 1997
  • 1997-11-13 JP JP52205098A patent/JP3253977B2/ja not_active Expired - Fee Related
  • 1997-11-13 KR KR10-1999-7004272A patent/KR100522663B1/ko not_active IP Right Cessation
  • 1997-11-13 BR BR9713354-0A patent/BR9713354A/pt not_active IP Right Cessation
  • 1997-11-13 AU AU54759/98A patent/AU5475998A/en not_active Abandoned
  • 1997-11-13 EP EP97951074A patent/EP0979317B1/fr not_active Revoked
  • 1997-11-13 AT AT97951074T patent/ATE218628T1/de not_active IP Right Cessation
  • 1997-11-13 PT PT97951074T patent/PT979317E/pt unknown
  • 1997-11-13 US US09/308,030 patent/US6153270A/en not_active Expired - Fee Related
  • 1997-11-13 ES ES97951074T patent/ES2176806T3/es not_active Expired - Lifetime
  • 1997-11-13 WO PCT/DE1997/002661 patent/WO1998021382A2/fr not_active Application Discontinuation

Non-Patent Citations (1)

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