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
  • C23C22/05—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 using aqueous solutions
  • C23C22/68—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 using aqueous solutions using aqueous solutions with pH between 6 and 8
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
• • 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
  • C23C22/78—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
• • 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
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/04—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material
  • C23C28/042—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material including a refractory ceramic layer, e.g. refractory metal oxides, ZrO2, rare earth oxides
• • 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
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
  • C23G1/08—Iron or steel
• • 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
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
  • C23G1/08—Iron or steel
  • C23G1/086—Iron or steel solutions containing HF

Definitions

• the present invention relates to a method for producing surface-treated Corten steel, comprising the steps of cleaning, activating, coloring, and sealing the surface.
• the invention further relates to Corten steels produced by the method according to the invention.
• Corten steels (for example, Material Nos. 1.8946 ASTM A 242 and 1.8963 ASTM A 588 according to ASTM A 242) form a rust layer on their surface during weathering, which at its base is particularly seal-tight and prevents or at least greatly slows the development of corrosion. The surfaces then have a reddish-brown rust layer.
• Corten steels Due to the relatively good corrosion resistance paired with favorable acquisition costs, Corten steels are attractive for use in architecture, for example as facade cladding. However, they have several disadvantages, which thus far have precluded widespread use despite favorable costs.
• the corrosion process at the surface does not come to a complete halt, in particular in a corrosive atmosphere, which is usually present in cities and industrial areas.
• the rust layer on Corten steels is then porous on its outer surface and mechanically unstable. During contact or in flowing water it releases rust particles, which may result in rust stains on the hands or clothing.
• Corten steels whose surfaces may be designed in colors other than drab rust brown, which are stable against weathering and abrasion, and which do not cause rust stains.
• the present invention fulfills these requirements. Therefore, it is an object of the present invention to provide novel Corten steels and a method for producing same, wherein these Corten steels have the above-mentioned advantages and/or overcome the above-mentioned disadvantages.
• the subject matter of the present invention relates to a method, as defined in the claims, for producing various color effects in a controlled and targeted manner by means of a wet chemical treatment of surfaces on Corten steels, and permanently protecting the colored surfaces against further corrosion and change, and soiling.
• the present invention therefore relates to a method for producing surface-treated Corten steel, comprising the following steps:
• Stage (1) cleaning at least a portion of at least one surface of the Corten steel
• Stage (2) activating at least a portion of the cleaned surface of the Corten steel from stage (1) by bringing the cleaned surface into contact with an aqueous activating solution containing fluoride ions, one or more oxidizing agents, and optionally one or more stabilizers for the oxidizing agent(s), followed by an optional rinsing step with water in order to remove at least a portion of the aqueous activating solution from the activated surface; and
• Stage (3) coloring at least a portion of the activated surface of the Corten steel from stage (2) by treating the activated surface with water for a period of at least 30 minutes and until the desired coloration of the surface of the Corten steel is achieved; carrying out an optional rinsing step with water if aqueous activating solution is still present on the colored surface; and carrying out a drying step; and
• the invention further relates to a Corten steel having a treated surface, containing a colorless, transparent coating on a colored surface of the Corten steel, wherein the surface treatment is carried out by a method according to the present invention.
• step (i) involves a treatment of the surface of Corten steel in two steps.
• step (i) Corten steel is provided, and a desired color is produced by wet chemical treatment.
• step (ii) comprises sealing of the colored surface in order to permanently protect it from further corrosion and change, and to provide it with dirt-repellent properties.
• the present invention therefore relates to a method for producing surface-treated Corten steel, including or comprising the following steps:
• Step (i) comprises the provision of Corten steel and a treatment comprising the three stages of (1) cleaning, (2) activating, and (3) coloring.
• Corten steel is initially provided.
• a Corten steel according to elemental analysis may include or comprise: iron as the main component (for example, greater than 90% by weight or greater than 95% by weight), and one or more components selected from the group comprising: carbon in a proportion of 0 to 0.16% by weight, chromium in a proportion of 0.40 to 0.65% by weight, silicon in a proportion of 0.30 to 0.50% by weight, manganese in a proportion of 0.80 to 1.25% by weight, phosphorus in a proportion of 0 to 0.030% by weight, sulfur in a proportion of 0 to 0.030% by weight, copper in a proportion of 0.10 to 0.40% by weight, vanadium in a proportion of 0.02 to 0.10% by weight, and nickel in a proportion of 0 to 0.40% by weight.
• the above percentages refer to the total mass of all components in the Corten steel.
• the Corten steel is composed of iron in a proportion of at least 90% by weight or at least 95% by weight, and the following components: carbon in a proportion of 0 to 0.16% by weight, chromium in a proportion of 0 to 0.65% by weight, silicon in a proportion of 0 to 0.50% by weight, manganese in a proportion of 0 to 1.25% by weight, phosphorus in a proportion of 0 to 0.030% by weight, sulfur in a proportion of 0 to 0.030% by weight, copper in a proportion of 0 to 0.40% by weight, vanadium in a proportion of 0 to 0.10% by weight, and nickel in a proportion of 0 to 0.40% by weight.
• Corten steels are Material Nos. 1.8946 and 1.8963 according to ASTM A 242 and A 588.
• the Corten steel may be present as a material/starting material, for example as sheet steel, or as a product, for example as a component of a finished structure.
• the Corten steel should not be treated or coated. However, the surface must be clean.
• step (i) takes place in such a way that the cleaned surface of the Corten steel is metallically clean, free of grease, and free of rust.
• the cleaning in stage (1) of step (i) may take place in such a way that the surface of the Corten steel is first subjected to alkaline hot degreasing (for example, using the AK 161 from Schlötter), followed by intermediate rinsing of the surface with water, followed by a treatment with a pickling inhibitor (for example, BESTA-S from Poligrat, Germany, containing sulfuric acid amidosulfonic acid, oxalic acid, and inhibitors, or a pickling inhibitor containing sulfuric acid, orthophosphoric acid, dimethylsulfoxide, and hexamethyltetramine, for example), likewise followed by a rinse treatment in municipal water/drinking water/tap water.
• a pickling inhibitor for example, BESTA-S from Poligrat, Germany, containing sulfuric acid amidosulfonic acid, oxalic acid, and inhibitors, or a pickling inhibitor containing sulfuric acid, orthophosphoric acid, dimethylsulfoxide, and hexamethyltetramine,
• the second stage, stage (2) in step (i), is used for activating the cleaned surface or the cleaned surfaces for the subsequent coloring.
• the activation is carried out by treating the cleaned surface with an aqueous activating solution (solution A) by dipping and/or spraying.
• the treatment time at room temperature (20° C.) may be, for example, 2 to 30 minutes, or 2 to 15 minutes, preferably 2 to 5 minutes.
• the aqueous activating solution may be prepared using drinking water/process water/tap water by adding HF and oxidizing agent as well as one or more optional stabilizers for the oxidizing agent.
• the aqueous activating solution preferably contains no acids stronger than HF, based on the pKa value.
• the aqueous activating solution preferably contains HF as the only acid.
• the aqueous activating solution is preferably composed of HF, oxidizing agent(s), optionally one or more stabilizers for the oxidizing agent(s), and drinking water/process water/tap water.
• the aqueous activating solution may contain fluoride ions, for example by using hydrogen fluoride, in a quantity of greater than 0% by weight and less than or equal to 3% by weight, or greater than 0.5% by weight and less than or equal to 3% by weight, preferably greater than 0.5% by weight and less than or equal to 1% by weight, based on the weight of the aqueous activating solution.
• fluoride ions for example by using hydrogen fluoride
• a solution containing such a quantity of fluoride is advantageously not classified as toxic.
• the active fluoride portion is determined based on the material removal from a test sheet. The active fluoride content and the material removal are linearly related.
• At least a portion of the quantity or also the entire quantity of fluoride ions preferably originates from hydrogen fluoride which has been added to the aqueous activating solution.
• the fluoride ions may also originate from other sources, for example ammonium bifluoride, sodium bifluoride, and/or potassium bifluoride.
• a suitable, preferred oxidizing agent is hydrogen peroxide.
• Hydrogen peroxide may be used as an aqueous solution.
• the quantity of oxidizing agent may be selected by those skilled in the art depending on the oxidizing agent used, for example by conducting simple test trials.
• the aqueous activating solution may contain, for example, the oxidizing agent(s), preferably hydrogen peroxide, in a quantity of greater than 0% by weight and less than or equal to 30% by weight, or greater than 0% by weight and less than or equal to 20% by weight, preferably greater than 3% by weight and less than or equal to 20% by weight, or greater than 3% by weight and less than or equal to 10% by weight.
• the oxidizing agent(s) preferably hydrogen peroxide
• the aqueous activating solution may in particular contain fluoride ions, for example from hydrogen fluoride, in a quantity of greater than 0.5% by weight and less than or equal to 3% by weight, preferably greater than 0.5% by weight and less than or equal to 1% by weight, based on the weight of the aqueous activating solution, and may contain the oxidizing agent(s), preferably hydrogen peroxide, in a quantity of greater than 3% by weight and less than or equal to 20% by weight, based on the weight of the aqueous activating solution.
• fluoride ions for example from hydrogen fluoride
• oxidizing agent(s) preferably hydrogen peroxide
• Suitable optional stabilizers for the oxidizing agent are mixtures of urea and one or more alkane diphosphonic acids which are optionally substituted with one or more hydroxyl or amino groups, or the salts thereof.
• the hydrocarbon chain of the alkane diphosphonic acids preferably contains 1, 2, 3, or 4 C atoms.
• alkane diphosphonic acids are alkylene diphosphonic acids or amino- or hydroxy-substituted alkylidene diphosphonic acids.
• 1-Hydroxyethane-1,1-diphosphonic acid is a particularly suitable alkylidene diphosphonic acid.
• Suitable stabilizers are also described in EP 1 903 081.
• the quantity of stabilizers in the aqueous activating solution may be selected as described in EP 1 903 081. Particularly high effectiveness of this stabilizer has been observed when the weight ratio of urea to free alkane diphosphonic acids is in the range of 100:1 to 20:1. This weight ratio is preferably between 60:1 and 35:1, in particular approximately 50:1.
• the stabilizer is used for stabilizing aqueous peroxide-containing solutions.
• aqueous peroxide-containing solutions are primarily understood to mean aqueous hydrogen peroxide-containing solutions, although other peroxide-containing solutions may also be stabilized in this way, for example solutions containing persulfuric acids and/or peroxycarboxylic acids, such as peracetic acid, or the salts thereof.
• Chlorides/phosphates should not be present.
• the concentration of a stabilized aqueous solution of hydrogen peroxide may be 30% or 35%, for example, but may also be lower, for example 20%, 10%, or 5%.
• solution A may contain fluorides in a maximum quantity of 1% by weight, 0.8% hydrofluoric acid, and a strongly oxidizing component, for example hydrogen peroxide, in a quantity of approximately 5% by weight, together with a suitable stabilizer (for example, according to EP 1903081 (A2) from Poligrat).
• a strongly oxidizing component for example hydrogen peroxide
• the activation takes place by treating the cleaned surface in an aqueous solution (solution A) by dipping or spraying.
• Solution A contains, for example, fluorides in a maximum quantity of 1% by weight HF and a strongly oxidizing component, for example hydrogen peroxide, in a quantity of approximately 5% by weight together with a suitable stabilizer (for example, according to EP 1903081 (A2) or product C600, C410, or C400 from Poligrat).
• a suitable stabilizer for example, according to EP 1903081 (A2) or product C600, C410, or C400 from Poligrat.
• the treatment time at room temperature is approximately 2 to 5 minutes.
• munal water/drinking water/tap water relates to natural water with the minerals and trace elements typically contained therein.
• the aqueous activating solution contains HF in a quantity of 0.5% by weight to 1% by weight, hydrogen peroxide in a quantity of 2% by weight to 10% by weight, and optionally one or more stabilizers.
• an optional rinsing step with water may be carried out in order to partially or completely remove the aqueous activating solution. If the aqueous activating solution is not removed, or is only partially removed, this affects the subsequent coloring step. The remaining quantity of the aqueous activating solution may be set depending on the desired color of the surface. The less rinsing carried out, the darker the color.
• the treatment of the activated surface in stage (3) of step (i) may be carried out using water, for example having a pH in the range of 6-8, over a period of, for example, 30 minutes to 15 hours, preferably 1 hour to 12 hours.
• the treatment with water may take place in principle by spraying with water and keeping the treated area moist.
• the surface should not dry during the treatment.
• Stage (3) is thus preferably carried out in such a way that the surface does not completely dry during the treatment period.
• a moist surface could be obtained, for example, by conducting a simple test using a handkerchief, wherein the handkerchief appears moist/wet after contact with the surface.
• the surface to be treated may, for example, be covered, for example with plastic film, in such a way that the drying of the surface is at least slowed down.
• the area is preferably kept moist by light spraying or misting with water, similar to spray irrigation in a greenhouse.
• the quantity of water may be selected by those skilled in the art in such a way that the area to be treated is kept completely and uniformly moist, in particular in order to obtain a uniform color.
• Municipal water/drinking water/tap water for example Munich drinking water, may be used.
• Variant 1 for producing golden yellow, orange, or light brown surfaces is
• the surfaces are rinsed with water, for example municipal water, rinsed off, and subsequently treated with water, for example municipal water, in a horizontal, tilted, or vertical position, by lightly spraying and keeping the area moist.
• water for example municipal water
• various colors then result on the surface of the Corten steel; in particular, the following colors are obtained after the approximate indicated times:
• the method may thus be carried out, for example, in such a way that the optional rinsing step with water takes place in stage (2) of step (i), and the coloring of the activated surface in stage (3) of step (i) is carried out by spraying and keeping the activated surface moist.
• the optional rinsing step with water takes place in stage (2) of step (i)
• the coloring of the activated surface in stage (3) of step (i) is carried out by spraying and keeping the activated surface moist.
• very little water is used, for example 0.2-1 L/m 2 and L/h.
• Variant 2 for producing olive green and dark brown surfaces After the treatment in solution A, the surfaces, for example metal sheets, without rinsing, are sprayed with water, for example municipal water, in a horizontal, tilted, or vertical position, for example, for a period of 1 to 2 minutes, for example, and are subsequently kept only moist.
• water for example municipal water
• the following colors result on the surface of the Corten steel; in particular, the following colors are obtained after the approximate indicated times:
• the method may thus be carried out, for example, in such a way that the optional rinsing step with water in stage (2) of step (i) is not carried out, and the coloring of the activated surface in stage (3) of step (i) takes place using little water, in particular only by keeping moist and not by rinsing, for example by spraying once with water and subsequently keeping the area moist by covering the surface, or by lightly spraying with water as described above, continuously or at intervals, to minimize runoff of the activating solution.
• Structured color effects for example stripes, are obtained by treating the surfaces in the first few minutes, for example 10 minutes after the treatment in solution A, in a vertical or tilted position.
• different fine or coarse structures result from the original runoff tracks of the water.
• step (ii) After the desired color is achieved, the surfaces are carefully dried and further treated in step (ii).
• step (ii) the colored surfaces are sealed by means of a suitable colorless, transparent coating, preferably a sol-gel coating/sol-gel lacquer (for example, POLIANT or POLISEAL from Poligrat).
• a suitable colorless, transparent coating preferably a sol-gel coating/sol-gel lacquer (for example, POLIANT or POLISEAL from Poligrat).
• the sealing in step (ii) may thus take place, for example, using a sol-gel coating, the sol-gel coating being burned in after the application in order to achieve a glass ceramic structure.
• a sol-gel coating the sol-gel coating being burned in after the application in order to achieve a glass ceramic structure.
• sol-gel lacquer is initially applied in the form of a liquid sol, with colloidal particles suspended therein, which is subsequently converted into a gel and then forms a solid, hard lacquer layer.
• application of the sol-gel lacquer or to “hardening of the sol-gel lacquer,” those skilled in the art are aware of which state the sol-gel system is in.
• the sol is preferably a silica sol based on silanes dissolved in solvent, for example alcohol.
• solvent for example alcohol.
• These silica sols may also optionally contain one or more additional sol-forming elements, such as Al, Ti, Zr, Mg, Ca, or Zn, which replace Si atoms in the colloidal structures.
• the hydrolyzable OR′ groups are hydroxy, alkoxy, and/or cycloalkoxy groups. Suitable examples of such include, for example, hydroxy, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, t-butoxy, pentoxy, hexoxy, cyclopentyloxy, and cyclohexyloxy groups, with ethoxy, n-propoxy, and isopropoxy groups in particular being preferred.
• the hydrolyzable OR′ groups may be the same or different.
• the nonhydrolyzable R′′ groups are alkyl and/or cycloalkyl groups. Suitable examples of such include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, hexyl, cyclopentyl, and cyclohexyl groups, with methyl, ethyl, n-propyl, and isopropyl groups in particular being preferred.
• the nonhydrolyzable R′′ groups may likewise be the same or different.
• a preferred sol-gel lacquer may include the starting materials tetraethoxyorthosilane (TEOS) and methyltriethoxysilane (MTES) and/or dimethyldiethoxysilane (DMDES).
• the starting compounds are hydrolyzed in part to form the corresponding hydroxy compounds (such as orthosilicic acid, trihydroxyalkylsilane, etc.), which may be facilitated by adding a catalyst, for example acid. Due to the high tendency of these hydroxy compounds toward condensation, they may now condense, with cleavage of water, to form smaller siloxane networks. Colloidal particles containing siloxane bonds are already present in the sol. Siloxane bonds are bonds of the type Si—O—Si, where “ ⁇ ” symbolizes any three independent bonds with other moieties, in particular with OH, OR′, and R′′, resulting in a three-dimensional crosslinked structure in the colloidal particles. OR′ and R′′ have the same meanings as above.
• the sol-gel lacquer may be applied in any desired manner, for example by dipping, pouring, spraying, or spreading. However, it is preferably applied by spraying, since this allows precise control of the quantity applied per unit area.
• a sol-gel lacquer layer may have a layer thickness of up to approximately 6 ⁇ m, or approximately 0.5 to 3 ⁇ m.
• the viscosity of the sol-gel lacquer may be set by those skilled in the art. It is known that, with an appropriately high dilution, the sol has a sufficiently low viscosity in its solvent in order to penetrate into any surface pores that are present.
• Suitable solvents for the sol are water and in particular alcohols such as methanol, ethanol, n-propanol, or isopropanol, with ethanol and isopropanol being preferred due to their physical properties and low toxicity of their vapors.
• the applied sol may then be reacted to form a gel.
• This reaction converts the liquid sol into a solid gel layer in which the colloidal particles of the sol crosslink with one another due to further hydrolysis and condensation, and with starting compounds which are not yet hydrolyzed and condensed. This may take place, for example, by evaporating the alcoholic solvent during drying.
• the sol-gel coatings are burned in, thus forming a glass ceramic structure which is firmly adherent, resistant to aging, and insensitive to environmental influences, and which permanently preserves the color effects. Burning in of the coating may be carried out by those skilled in the art, using customary procedures.
• the surfaces coated with the gel are subjected to thermal hardening. This takes place at elevated temperatures, whereby the gel is converted into a colorless, transparent, glass-like layer.
• the silica sol components are converted into even more strongly crosslinked silicon dioxide, which, depending on the composition of the underlying sol, may contain further components such as aluminum oxide, titanium oxide, or zirconium oxide. These layers are hard, closed, and resistant to many of the chemicals with which a surface may come into contact under typical conditions, and are resistant to temperatures up to approximately 500° C.
• the coated surface is exposed to temperatures of 160° C. to 220° C. during the subsequent hardening of the gel.
• This hardening should take place for a period of at least 10 minutes, preferably 20 to 45 minutes, for example 30 minutes.
• the hardening is preferably carried out at temperatures between 180° C. and 210° C., for example 200° C., although temperatures below 180 ° C. are also suitable for this purpose.
• the gel is converted into a hard, colorless, transparent, glass-like lacquer which tightly seals the surface, for its part has no cracks, and imparts the surface with a high degree of hardness and wear resistance.
• cathodic hardening may take place according to patent application DE 21 26 129, for example.
• the invention further relates to a Corten steel having a treated surface containing a colorless, transparent coating on a colored surface of the Corten steel, wherein the surface treatment is carried out by a method according to the present invention.
• the Corten steel according to the invention differs structurally from known Corten steels, which is discernible based on the color and the properties, such as stability against corrosion.
• a metal sheet made of material No. 1.8963 having dimensions of 500 ⁇ 500 ⁇ 1.5 mm was degreased in an aqueous hot degreaser (AK 161 from Schlötter) at 60° C. for a period of 10 minutes.
• AK 161 from Schlötter
• the surfaces were subsequently rinsed twice with municipal water and then derusted in a pickling inhibitor (BESTA-S from Poligrat, Germany) at 60° C. for a period of 2 minutes.
• a pickling inhibitor BESTA-S from Poligrat, Germany
• the surfaces were subsequently rinsed twice with municipal water and then activated at room temperature (20° C.) by dipping in an aqueous solution containing 0.8% by weight HF, 5% by weight hydrogen peroxide, and a stabilizer for the peroxide (product C600 from Poligrat) for a period of 4 minutes.
• the surfaces were subsequently rinsed once with municipal water and then set down. In the horizontal position, the surfaces were kept moist by lightly spraying with municipal water for a period of 3 hours at room temperature. An orange-colored surface resulted.
• the surface was dried and subsequently coated with the POLIANT sol-gel method from Poligrat, using a spray process, and burned in at 200° C. for a period of 30 minutes.
• the surface obtained was orange-colored, having an attractive striped structure of lighter and darker colors, with a metallic effect that reflected the light iridescently.
• the surface was hydrophobic, so that water rolled off in beads without leaving behind traces of moisture.
• Example 1 A metal sheet corresponding to Example 1 was pretreated and activated as in Example 1.
• the metal sheet, without a rinsing process, was subsequently kept moist at room temperature in a horizontal position by spraying with municipal water. After a period of 3 hours and subsequent rinsing, the metal sheet had an olive green surface. Further treatment was carried out as in Example 1, with the metallic effect on the surface being slightly less pronounced in comparison to Example 1.

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• 2013
  • 2013-06-14 DE DE102013010080.1A patent/DE102013010080A1/de not_active Withdrawn
• 2014
  • 2014-06-13 EP EP14731592.3A patent/EP3008226B1/de not_active Not-in-force
  • 2014-06-13 US US14/896,931 patent/US20160177454A1/en not_active Abandoned
  • 2014-06-13 WO PCT/EP2014/062416 patent/WO2014198917A1/de active Application Filing

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