Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D10/00—Modifying the physical properties by methods other than heat treatment or deformation
• • 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
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/26—After-treatment
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D7/00—Modifying the physical properties of iron or steel by deformation
  • C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0242—Flattening; Dressing; Flexing
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
  • C21D8/0257—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment with diffusion of elements, e.g. decarburising, nitriding
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular surface treatment
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
  • C21D9/54—Furnaces for treating strips or wire
  • C21D9/56—Continuous furnaces for strip or wire
  • C21D9/561—Continuous furnaces for strip or wire with a controlled atmosphere or vacuum
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
  • C21D9/54—Furnaces for treating strips or wire
  • C21D9/56—Continuous furnaces for strip or wire
  • C21D9/562—Details
• • 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
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
  • C23C2/06—Zinc or cadmium or alloys based thereon
• • 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
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/26—After-treatment
  • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
• • 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
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/26—After-treatment
  • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
  • C23C2/285—Thermal after-treatment, e.g. treatment in oil bath for remelting the 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
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
  • C23C2/36—Elongated material
  • C23C2/40—Plates; Strips
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D13/00—Electrophoretic coating characterised by the process
  • C25D13/12—Electrophoretic coating characterised by the process characterised by the article coated
  • C25D13/16—Wires; Strips; Foils
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/22—Electroplating: Baths therefor from solutions of zinc
• • 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
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D7/00—Electroplating characterised by the article coated
  • C25D7/06—Wires; Strips; Foils
  • C25D7/0614—Strips or foils

Definitions

• the invention relates to a method for producing a semi-finished product with a modified surface, comprising at least one method step of at least regionally modifying the surface of a coated, skin-passed, oiled, cleaned metallic steel substrate by means of a low-pressure or atmospheric-pressure plasma treatment of said surface areas with oxygen, air, argon , forming gas or a mixture of oxygen and argon, oxygen and air as process gas.
• the invention also relates to the semi-finished products and/or flat steel products produced therewith, optionally formed semi-finished products and/or flat steel products, and their use.
• alloying elements to hot-dip coatings has a strong influence on the chemical composition in the near-surface area.
• the composition of the area close to the surface in turn has a major influence on the further processing steps such as pre-treatment, gluing, phosphating and/or painting.
• the composition close to the surface can mean that they are not optimally covered by the existing process window, for example in the automotive process. This in turn can have a negative effect on properties such as paint adhesion or the fracture behavior of bonded surfaces, so that new materials/surfaces cannot be used or the existing process window has to be laboriously adjusted.
• Metal coatings particularly applied in the hot-dip process
• materials and surface concepts must be equally integrated into the standard process for typical automotive processes as well as for the coil coating process.
• the water wetting behavior of the surface concepts is a decisive criterion. Only if adhesion promoters, forming aids, activation or passivation pre-/or After-treatments are applied homogeneously and across the entire surface, they can also fully fulfill their function.
• adhesion promoters, forming aids, activation or passivation pre-/or After-treatments are applied homogeneously and across the entire surface, they can also fully fulfill their function.
• the water wettability deteriorates within 48 hours on contact with air or suddenly on direct contact with oils or other media such as organic solvents. Due to the short contact times and the optimally exhausted process in the automotive or coil coating (CC) process, there are great difficulties in restoring the wettability of Z or ZM surfaces.
• process-related superstructures can occur in the wet film of the pretreatment solution on various metal coatings during coil coating. These can remain even after the pre-treatment has dried and are suspected of leading to adhesion problems in the painting process.
• the object of the invention is therefore to overcome the above-mentioned disadvantages of the known methods and to provide an alternative to the methods used hitherto, which can be carried out with existing processes and process windows.
• the method should be optimized for metal coatings based on zinc. This problem is solved by the method with the features of patent claim 1.
• the method for producing a semi-finished product with a modified surface comprises the following method steps:
• step V. at least regional modification of the surface of the cleaned substrate from step V. by means of a low-pressure or atmospheric-pressure plasma treatment of said surface areas with oxygen, air, argon, forming gas or a mixture of oxygen and argon, oxygen and air as process gas.
• temper-passing is carried out prior to the electrogalvanizing step.
• the subject matter of the invention is therefore a method for producing a semi-finished product with a modified surface comprising the following method steps:
• Dressing, at least in certain areas, of the metallic substrate from step I. III. at least regional application of a zinc-based metallic coating on both sides by electrolysis, preferably in an electrolyte bath,
• step V. at least regional modification of the surface of the cleaned substrate from step V. by means of a low-pressure or atmospheric-pressure plasma treatment of said surface areas with oxygen, air, argon, forming gas or a mixture of oxygen and argon, oxygen and air as process gas.
• a strip-shaped steel substrate is understood to mean a substrate which can be provided in the form of a strip, for example wound up as a coil.
• a sheet-like substrate is a flat, usually rolled substrate whose thickness is significantly smaller than its width or length; in particular steel strips, steel sheets and blanks obtained therefrom, such as blanks and the like.
• the semi-finished product is subjected to further process steps, including, for example, forming steps.
• a steel substrate is a substrate made of steel.
• a substrate is generally prepared for the application of a zinc-based metallic coating on both sides, for example cleaned, preferably in a continuous annealing furnace.
• a continuous annealing furnace In its front oxidizing part, oil and dirt residues are removed and the steel surface starts to form a thin oxide layer.
• this oxide layer is removed by hydrogen by reduction.
• This furnace anneal causes recrystallization to take place, which also eliminates the work hardening of the cold rolled material.
• the strip is then brought to the temperature of the molten metal and made available in step I for coating.
• step II it is hot dip coated by passing it through a molten metal bath.
• the desired coating thickness is set using a nozzle wiper process.
• the coatings are then allowed to cool in a controlled manner, optionally the coating is quenched after the bath.
• diffusion of the liquid zinc and possibly other metals of the coating with the steel surface forms on the steel part a coating of differently composed iron-zinc alloy layers or iron-zinc alloy layers containing other metals.
• On the top alloy layer there is a pure layer consisting of the pure coating, i.e. without iron diffusion.
• the pure layer corresponds in its composition to the applied melt.
• the coated substrate is skin-passed in step III and optionally stretch or stretch-bend straightened.
• the elongation rate is usually in the range of 0.3 to 5%.
• the surface topography is to be understood as meaning a profile progression which is characterized, for example, by roughness, number of peaks and waviness.
• a surface post-treatment takes place.
• the workpiece to be galvanized is connected here as a cathode in a preferably aqueous electrolysis solution.
• Metallic zinc is used as an anode.
• the substrate is oiled, i.e. provided with a surface protection.
• the oiled substrate has the following sequence of layers close to the surface after step IV:
• the clean layer 1 is the above-described clean layer consisting of the pure coating and possibly unavoidable impurities such as iron.
• the reaction layer 2 with a thickness of 1-100 nm, preferably 50-100 nm, consists of reaction products of the clean layer and is formed by reaction of metals on the surface and optionally the next underlying atomic layers of the clean layer upon contact with the atmosphere. Accordingly, the reaction layer essentially has metal oxides and/or metal hydroxides. Additives, for example lubricants, can also be incorporated into the reaction layer; if appropriate, sulphides and/or carbonates are additionally present.
• the reaction layer merges into a sorption layer 3 with a thickness of 0.1-100 nm. These are accumulations of substances or of colloids or particles in a phase boundary between the solid phase of the reaction layer 2 and the surrounding atmosphere as a gas phase.
• This sorption layer 3 is rich in carbon (from hydrocarbons) and oxygen, contains or consists essentially of organic substances, in particular esters of carboxylic acids, optionally water.
• the substances or colloids or particles of the sorption layer cannot be removed with a simple chemical, non-reactive cleaning, since they are foreign substances that are more difficult to remove than the impurities of the subsequent contamination (impurity) layer.
• the contamination layer 4 follows as the outermost layer. With a thickness of at least 0.1 ⁇ m, preferably at least 1 ⁇ m, particularly preferably 10 ⁇ m to a maximum of 100 ⁇ m, it contains dirt to be removed, such as dirt, production residues and/or previously applied fats and/or oils.
• the term essentially corresponds to or essentially the same or equivalent statements, a deviation from a specific, predetermined value or a difference between 2 values of a maximum of 50%, 45%, 40%, preferably 30%, 25 %, particularly preferably 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, in particular 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% or 0.5%, 0.1%.
• the specified value is therefore composed of 100% organic substances.
• the layer thickness or the depth of a layer is always determined from the topmost atom of the respective surface.
• the cleaning of the substrate in step V. is necessary.
• the cleaning improves the wettability of the metallic coating with aqueous media.
• wet-chemical cleaning is carried out.
• Alkaline preferably mildly alkaline cleaning agents or organic solvents are used.
• one or more agents are used, selected from the group containing or consisting of: mildly alkaline cleaning agents with a pH of 9 to 11, preferably 9.5 to 10.5; strongly alkaline cleaning agents with a pH of 12 to 14, preferably 12.5 to 13.0; n-heptane, methyl ethyl ketone, tetrahydrofuran, isopropanol, ethanol, white spirit (also known as white spirit) or a mixture of two or more of the substances mentioned; preferably mixture of n-heptane with tetrahydrofuran, mixture of n-heptane with ethanol.
• This cleaning is a degreasing in an alternative.
• the contamination layers of the contamination layer are essentially removed in this cleaning step, and consequently the contamination layer is essentially removed. Nevertheless, oil and/or fat residues or components thereof can remain on the substrate, in particular in the sorption layer.
• Cleaning is carried out by spraying or dipping or as a strip coating.
• the cleaning can only take place in certain areas with respect to the entire surface of the substrate, on one side of the substrate in strip or sheet form or on both sides.
• the treatment is preferably carried out in certain, predefined areas or on one side of the substrate, i. H. over the entire area of a page, thus covering the entire area.
• step VI a modification of the surface by means of plasma treatment.
• the modification can only take place in certain areas with respect to the entire surface of the substrate, on one side of the strip-shaped or sheet-shaped substrate or on both sides.
• the treatment is preferably carried out in specific, predefined areas or on one side of the substrate, ie over the entire area of one side, thus covering the entire area.
• the plasma treatment takes place at low pressure, ie in a vacuum chamber at 10 -3 to 10 -9 bar (10 A -3 to 10 A -9 bar; preferably with a base pressure P of at least 0.1x10 A -4 mbar 0.5xl0 A -4 mbar, particularly preferably 1.0xl0 A -4 mbar, in particular 3.0xl0 A -4 mbar and a maximum of 100.0xl0 A -4 mbar, 10.0xl0 A -4 mbar, particularly preferably 6.0xl0 A -4 mbar, in particular 5.0x10 A -4 mbar and a test pressure p of at least 0.5x10 A -2 mbar, 1.0x10 A -2 mbar, particularly preferably 2.0x10-2 mbar, in particular 3.0x10-2 mbar and a maximum of 10.0x10 A -2 mbar, 1.0x10 A -2 mbar, particularly preferably 6.0x10 A -2 mbar, in particular preferably 6.0
• the plasma treatment takes place in an alternative at atmospheric pressure, i. H. at a pressure (air pressure) of at least 750 mbar, preferably 800 mbar, 850 mbar, 900 mbar, particularly preferably 950 mbar, in particular 1000 mbar and at most 1100 mbar, preferably 1070 mbar, 1050 mbar, particularly preferably 1030 mbar, in particular 1020 mbar.
• a pressure air pressure
• air, oxygen or argon is used as the process gas in an alternative.
• a mixture of air and oxygen, air and argon, or oxygen and argon is used.
• the use of air as the process gas is a plasma treatment in the atmosphere without the addition of other process gases.
• a mixture of air and oxygen refers to a plasma treatment in the atmosphere with enrichment of oxygen.
• forming gas is used.
• a gas mixture of nitrogen and hydrogen, alternatively argon and hydrogen is used within the meaning of the invention.
• a gas mixture of nitrogen and hydrogen is preferably used as the forming gas, with a proportion of hydrogen of 1-30%, preferably 1-20%, particularly preferably 1-10%, in particular 1-5% hydrogen, the remainder being nitrogen.
• Corresponding gas mixtures are commercially available.
• the sum of the individual gas flows g is in the range described above, for example a gas flow gAr and 200 sccm with a simultaneous gas flow g02 of 400 sccm.
• An alternative is plasma treatment at room temperature, at least 20.degree. C., at most 30.degree. C., preferably about 25.0.degree.
• the plasma treatment at low pressure has a treatment time t of at least 0.5 seconds, preferably 1, particularly preferably 5, 10, 20, particularly 30 seconds and a maximum of 1200, 900, 600, preferably 300, 180, particularly preferably 120, particularly 60 seconds per component on.
• Plasma treatment at atmospheric pressure is based on the application of the plasma to a substrate using devices known as nozzles.
• the application surface of an individual device is understood to mean a surface area on the substrate on which the plasma impinges.
• the treatment time t per application area is at least 0.1 seconds, 0.5 seconds, preferably 1, preferably 5, 10, 20, in particular 30 seconds and a maximum of 300, 180, particularly preferably 120, 60, in particular 30, 20, 10, 5 seconds , 3, or 1 seconds.
• the treatment time t is defined by the feed of the device or the substrate and is at least 0.1 m/min, 1 m/min, preferably 3, 7, 9, 10 m/min, preferably 15, 20 m/min , in particular 30 m/min and at most 20, 30 m/min, preferably 35, 40, 45, 50, 60 m/min, particularly preferably 70, 80, 90 or 100 m/min.
• the plasma treatment is defined by one or more of the following characteristics:
• a frequency f of at least 5, 10, 20, 30, 40 or 50 preferably 100, particularly preferably 150, particularly 180 Hz and a maximum of 500, preferably 300, particularly preferably 250, particularly 220 Hz;
• Characteristic of the modification of the surface by plasma treatment according to the invention is the removal of carbon and carbon-containing components from the surface of the substrate, with the chemical composition of the reaction layer 2 (see above) remaining essentially the same in relation to a control without the plasma treatment according to the invention.
• the respective proportions of metals, their oxides or hydroxides remain constant and are not changed by the plasma treatment.
• the residual coatings containing carbon, also in the form of organic compounds are removed from the reaction layer by the plasma treatment.
• a substrate with a coating is accordingly also present with a reaction layer of the same composition as before the oiling.
• the plasma treatment is additionally characterized in that the surface topography remains constant in relation to a control without the plasma treatment according to the invention.
• An untreated control within the meaning of the invention is a substrate with a metallic coating which, including the coating, is identical to the sample used according to the invention, i. H. except for the plasma treatment to be used according to the invention, the control has gone through the same processes and manufacturing steps.
• the only difference between the control and the substrate used according to the invention is that the control is subjected to a plasma treatment which is not to be used according to the invention.
• the steel substrate is coated with a metallic coating based on Zn, ZnMg, ZnAl and/or ZnMgAl.
• a hot-dip bath which is particularly suitable for the purposes according to the invention and a corresponding metallic coating on the substrate contains or consists of Zn and unavoidable impurities as an alternative.
• a hot-dip bath and a corresponding metallic coating contains or consists of between 0.1 and 10.0% by weight of magnesium and/or between 0.1 and 20.0% by weight of aluminum, preferably at least 0.3% by weight %, 0.5% by weight magnesium, particularly preferably 1.0% by weight Mg, in particular 2.0% by weight Mg and at most 4.0% by weight Magnesium, particularly preferably 3.0% by weight Mg, particularly 2.5% by weight, 2.0% by weight Mg and/or at least 0.5% by weight Al, particularly preferably 0.7% by weight.
• the Mg/Al mass ratio is preferably less than or equal to 1, particularly preferably less than 0.9.
• the hot-dip bath and the corresponding metallic coating can contain up to 0.3% by weight of each of the optional additional elements selected from the group containing or consisting of Si, Sb, Pb, Ti, Ca, Mn, Sn, La, Ce, Cr, Ni, Zr and Bi. There may also be residues of other elements, for example from the previous steps, or unavoidable impurities.
• the concentrations of the individual elements in the coating differ in layers close to the interface from the concentrations in the hot-dip bath. Especially in layers close to the surface, such as the reaction layer, the individual elements are present in a ratio that differs from that of the hot-dip bath.
• the magnesium-rich oxide layer in combination with the components of the oil, especially esters, ensures poor wetting behavior of process media in the further surface treatment steps.
• the zinc-based coating of the steel substrate has a coating of at least 20 g/m2, preferably 30 g/m2, 40 g/m2, 50 g/m2, 60 g/m2, 70 g/m2 , 80 g/m2, 90 g/m2, 100 g/m2 or 120 g/m2, in particular from at least 40 g/m2 to a maximum of 300 g/m2, 200 g/m2, preferably 150 g/m2, particularly preferably 120 g /m2, 100 g/m2, in particular 90 g/m2, 80 g/m2 per side on one or both sides, preferably covering the entire area.
• coatings with a thickness of at least 0.5 ⁇ m, 1.0 ⁇ m, 2.0 ⁇ m or 3.0 ⁇ m, preferably 4.0 ⁇ m, 5.0 ⁇ m or 6.0 ⁇ m, in particular at least 7.0 ⁇ m are obtained ⁇ m, 8.0 ⁇ m, 9.0 ⁇ m or 10.0 ⁇ m up to a maximum of 10.0 ⁇ m, 12.0 ⁇ m, 15.0 ⁇ m, 20.0 ⁇ m, preferably 25.0 ⁇ m, 30.0 ⁇ m, in particular preferably 35.0 ⁇ m, 40.0 ⁇ m, in particular 50.0 ⁇ m or more per side, applied to one or both sides, preferably covering the entire surface.
• steps I., III., IV., V. and/or VI. is wound up into a coil in order to be fed or fed to the next work steps.
• the coil is uncoiled accordingly.
• the results of the previous steps are not changed by winding or unwinding, which is therefore another feature of the substrate or semi-finished product.
• One embodiment relates to the method which, after step IV., oiling—can be referred to as IV.a in this embodiment—comprises an aging step IV.b.
• the aging step includes one or more of the following sub-steps: distribution of the oil on the surface topography of the substrate, reeling, storage, transport to the customer, reeling, etc.
• the aging step lasts at least 0.5 hours, 1.0, 6.0, 12, 0 or 24.0 hours up to several (at least 2) days, weeks, months or years.
• the influence of aging is relevant for the layers of the substrate close to the surface, since an oxide layer (reaction layer -2-) of up to 200 nm can form despite oiling.
• the metallic phases below this layer also oxidize as a result. Normal cleaning is therefore not sufficient for later, comprehensive hydrophilic wetting.
• step VI. a further surface treatment step VII.
• the surface of the cleaned substrate is modified in such a way that interfering components are removed and, if necessary, the surface is activated so that uniform, homogeneous wetting can take place.
• the plasma treatment is preferably carried out immediately before the subsequent surface treatment step, preferably a chemical post-treatment. How long the surface remains activated or reactive by the plasma treatment depends on the length of time between the two steps. The longer the treatment duration, the longer a surface remains active. In particular, the steel substrate comes into contact with as few deflection rollers as possible between plasma and post-treatment.
• the time intervals between the treatment steps are less than 300 s, 180 s, preferably 120 s, 90 s, 60 s, particularly preferably 45 s, 30 s, 25 s, 20 s, in particular 15 s, 10 s, 5 s, 1 s.
• step VII-i carried out a coil coating process.
• step VI. first carried out a pretreatment for coil coating as step VII-ia.
• the pretreatment comprises, for example, a chemical passivation known to the person skilled in the art or another or further pretreatment, such as the application of adhesion promoter, activating and/or passivating agent.
• the plasma treatment before the application of pre-treatment media ensures improved wetting behavior of the respective pre-treatment compared to a control without plasma treatment and thus for a stronger / more homogeneous connection of the layers to be applied subsequently, such as a more stable paint structure.
• step VII-i-b the coil coating process as step VII-i-b. carried out.
• the coating optionally in several layers such as a primer, top coat and/or clear coat, is applied using a roller process and baked at around 240°C.
• the paint can be protected with a laminating foil.
• the endless coated substrate / semi-finished product is wound up into a coil. Alternatively, the coil can be cut to length, if necessary before lamination.
• step III after skin-passing in step III. a modification of the surface of the tempered substrate from step III. by means of an at least regional plasma treatment of the surface in a step III-ii-a and optionally a step III-ii-b of the pre- and/or post-treatment. This and the plasma treatment are carried out as described above.
• a further embodiment relates to a method comprising steps I. to VII. and optionally step III-ii-a and optionally step III-ii-b, in which, before the purification in step V. - which in this embodiment is V- ii-b - at least one step V-ii-a selected from the group of processes containing or consisting of sheeting, forming, joining, degreasing, activating, phosphating, cathodic dip painting and painting is carried out.
• Joining can in turn be spot welding, gluing and laser soldering.
• a further surface treatment step VII-ii-a. after plasma treatment VI. an activation of the surface is carried out.
• the surface of the plasma-treated substrate is brought into a state that enables a chemical reaction.
• metal ions are released from the surface. Then you can come with me components of the solution form compounds. Dilute phosphoric acid compounds or special compounds that act like seed crystals are often used for activation.
• the activation is used for the following phosphating, which takes place as a further surface treatment step VII-ii-b in this alternative.
• the relative concentration of C, O, Mg and/or Zn is determined by determining the absolute concentration of these elements and subsequent normalization to 100%; the sum of the concentrations of these elements is set equal to 100 and the proportion of the respective element in this 100% is evaluated or weighted as a relative concentration, i.e. based on 100%.
• the relative concentration of an element therefore refers to the sum of the concentrations of the 4 elements, as this sum represents 100%. Because the absolute concentration of the elements can vary from coating to coating, the present invention is generally expressed in terms of relative concentration and percentage points to accurately define the changes.
• the XPS-typical information depth corresponds to a layer with a thickness of essentially 5 nm.
• the XPS measurement is carried out using a device: Phi Quantera II SXM Scanning XPS Microprobe from Physical Electronics GmbH.
• the device has the following general device parameters: Working pressure in the main chamber: ⁇ 1x10-6 Pa; Lock pressure: ⁇ 2.7x10-4 Pa; X-ray source: AI 1486.6 eV monochromatic; Maximum sample size: 70 mm x 70 mm x 15 mm (height) ; Neutralizing agent: Ar and electrons; Neutralizing voltage: 1.5 V; Neutralizing current: 20.0 mA; Beam diameter: 100 pm; Pass energy: 280eV; Spectral resolution: leV.)
• the subject matter of the invention is a semi-finished product with a modified surface, produced in a method as described above.
• Another subject of the invention is the use of a low-pressure or atmospheric-pressure plasma treatment with oxygen, air, argon, forming gas or a mixture of oxygen and argon, oxygen and air as process gas to restore a surface of a tempered, metal-coated substrate after oiling and cleaning of the substrate.
• plasma treatment, tempering, metallic coating, oiling and cleaning are described in detail above.
• a plasma treatment with oxygen, air, argon, forming gas or a mixture of oxygen and argon, oxygen and air as the process gas improves the wettability of metal-coated steel with aqueous media by removing residual carbon coatings that remain after standard cleaning.
• the improved wettability can be used for the coil coating process to achieve a more even coating result.
• a streak-free result can be achieved using the devices and processes previously used.
• the effect of the plasma treatment can be used for any aqueous chemical treatment in both the automotive and coil coating processes.
• a ZnMgAl-based coated substrate treated as described above was produced and degreased with organic solvents (combination of n-heptane with isopropanol, n-heptane with ethanol or ethanol with isopropanol).
• Table 1 :
• the results are shown in FIG. From this it becomes clear that the plasma treatment significantly increases the wettability.
• the plasma treatment significantly increases the wettability in general, not just for water. This means that the modification of the surface by plasma leads to a surface that can be easily wetted by polar liquids. Since the effect already occurs after the shortest treatment time of 5 minutes, i.e. the residual coatings containing carbon are completely removed, no difference in the wettability can be achieved by longer treatment times.
• the water contact angle of PI was measured immediately after plasma treatment (PI-0), after 1 day (PI-1), 2 days (PI-2) and after 2 weeks (PI-3).
• a Zn (ZI) or ZnMgAl (ZM1 and ZM2)-based and electrolytically galvanized (ZE1) coated substrate was prepared as described above, oiled with Fuchs anti-corrosion oil PL3802-39S and alkaline degreased. with Ridoline 1340 from Henkel.
• a plasma treatment was carried out with argon or an oxygen-argon mixture as the process gas, as described above, to increase the wettability. This was determined via the contact angle with water and diiodomethane immediately after plasma treatment; an identically prepared sheet served as a control (K), but without it.
• K control
• tempered substrates coated on a ZnMgAl basis were produced as described above and oiled with the corrosion protection oil PL3802-39S from Fuchs.
• 10 were alkaline degreased and 5 with MEK (methyl ethyl ketone).
• 5 of the alkaline degreased substrates were treated with plasma.
• adhesion promoter GBX 4537 adhesion promoter GBX 4537
• the wet film of the pre-treatment solution was displayed directly after coating using a thermal imaging camera.
• the wet film appeared even over a large area on the semi-finished products without plasma treatment, but fine transverse stripes were found in the wet film, which remained after drying.
• the uniformity of the adhesion promoter layer was assessed by coloring it dark with copper sulphate solution. Wetting defects were found in the semi-finished products without plasma treatment.
• the semi-finished products that were subjected to plasma treatment resulted in uniform, full-surface, homogeneous wetting without defects.
• the evaluation was carried out optically.

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• 2021
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