Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C19/00—Apparatus specially adapted for applying particulate materials to surfaces
  • B05C19/04—Apparatus specially adapted for applying particulate materials to surfaces the particulate material being projected, poured or allowed to flow onto the surface of the work
• • 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
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
  • B05D1/08—Flame spraying
  • B05D1/10—Applying particulate materials
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/62—Metallic pigments or fillers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/62—Metallic pigments or fillers
  • C09C1/64—Aluminium
  • C09C1/642—Aluminium treated with inorganic compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
  • C09C3/006—Combinations of treatments provided for in groups C09C3/04 - C09C3/12
• • 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
  • C23C24/02—Coating starting from inorganic powder by application of pressure only
  • C23C24/04—Impact or kinetic deposition of particles
• • 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
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
• • 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
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
  • C23C4/06—Metallic material
• • 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
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/18—After-treatment

Definitions

• the invention relates to coating technology of different steel products, such as continuously coated steel strips having metal coating on their surfaces.
• the present invention further relates to a steel product and more particularly to a steel product coated with a metal coating as defined in the preamble of independent claim 19.
• the present invention also relates to an arrangement for producing a coating on a steel substrate as defined in the preamble of claim 27.
• the present invention relates to a raw material as defined in the preamble of claim 36.
• metal coatings such as zinc and aluminum based coatings for example to enhance environmental resistance, such as protection against corrosion. It is also known to produce different kinds of metal coatings on steel substrates and products for other purposes.
• Known methods for providing a metal coating on a steel substrate comprise for example hot dipping, such as hot dip galvanizing, or electroplating, such as zinc electroplating.
• the steel substrate is further provided with a separate surface coloring applied on the metal coating. In the prior art, the surface coloring is formed as a separate coloring layer on the metal coated steel substrate.
• methods of prior art for providing the surface coloring comprise different painting methods with or without metallic particles, which has, in addition to a additional process step, disadvantages related to temperature resistance and ability for cathodic protection.
• the problem relating to the prior art coloring methods is that the coloring is provided only as a separate layer on the metal coating provided to the steel substrate.
• this separate coloring layer is typically organic compound.
• the separate surface layer may become detached from the inorganic metal coating due to environmental conditions and thus the color of metal coating is exposed.
• mechanical stress such as abrasion or impact may break the coloring surface layer and even detach part of the same.
• the prior art does not provide a durable color in surface coating to be used with steel substrates.
• Still one problem with the prior art coatings is that those known coatings cannot provide integral colored coating having good galvanic protection against corrosion and good durability and adhesion to steel.
• the object of the present invention is to provide a method, a steel product and an arrangement and a raw material so as to overcome or at least alleviate the prior art disadvantages.
• the objects of the present invention are achieved with a method according to the characterizing portion of claim 1.
• the objects of the present invention are further achieved with a steel product according to the characterizing portion of claim 19 and with an arrangement according to characterizing portion of claim 27.
• the objects of the present invention are also achieved with a raw material according to the characterizing portion of claim 36 and with use of the mentioned raw material.
• the present invention is based on the idea of producing a metal coating on a steel substrate with thermal spraying.
• the metal (s) or metal alloy(s) from which the metal coating is provided are deposited on the steel substrate as particles.
• the present invention provides a method for coating a steel substrate by depositing metal particles together with at least one inorganic coloring agent on the surface steel substrate by thermal spraying. Therefore the present invention also provides a steel product having a metal coating on at least part of a surface of the steel product, the metal coating consisting at least partly of metal particles deposited on the surface of the steel product such the metal coating further comprises inorganic coloring agent embedded into the metal coating.
• the metal coating may be produced by thermal spraying using raw material comprising metal particles with at least one inorganic coloring agent adhered to the metal particles.
• the inorganic coloring agent is preferably sintered or fused to the metal particles.
• the present invention further provides an arrangement for producing a metal coating on a steel strip, preferably as a continuous process.
• the arrangement comprises a pre-heating unit for heating the steel strip to an elevated temperature and a coating unit for producing a metal coating on at least part of the steel strip.
• the coating unit of the arrangement comprises one or more thermal sprayers for depositing metal particles on the surface of the steel strip.
• the one or more thermal sprayers are arranged to deposit at least one inorganic coloring agent on the surface of the steel substrate together with the metal particles for providing the metal coating with inorganic coloring agent embedded into metal coating, and that the coating unit further comprises post-heating unit arranged for heat treating the coated steel strip for providing metal bonding between the metal coating and the steel strip.
• the present invention provides a throughout colored metal coating to be formed on a steel substrate and also a steel product having a throughout colored metal coating.
• the coating according to the present invention prevents environmental conditions from detaching the color from the coating.
• the coating of the present invention provides an abrasion resistant coloring as scratching or the like does not remove or detach coloring from the coating. Therefore the present invention also provides a durable coloring of a coating.
• the present invention makes possible to provide a metal bonding between the colored metal coating and the steel product to provide a durable throughout colored metal coating with excellent cathodic corrosion protection which cannot be achieved with prior art paint coating or the like which may be difficult or even impossible to obtain with known resin paint coating solutions including metal particles or the like.
• the method according to the present invention obviates a separate coloring or painting process step with organic coating, which is usually made in addition to zinc plating. This reduces environmental load and realizes economical savings in manufacturing of steel products having colored metal based coatings.
• Figure 1 is a schematic view of a thermal sprayer to be used in the present invention
• FIG. 2 is schematic view of another thermal sprayer to be used in the present invention.
• Figure 3 shows schematically an arrangement for coating a steel strip according to the present invention.
• the figure 1 shows one embodiment of a thermal sprayer 2 to be used for providing a metal coating 6 on a steel substrate 4.
• Figure 1 shows a flame sprayer 2 and specifically a high velocity oxy-fuel (HVOF) sprayer.
• the sprayer 2 comprises a fuel inlet 12 for supplying fuel gas or liquid F into the sprayer 2 and an oxygen inlet 14 for supplying oxygen or oxygen containing gas O into the sprayer 2.
• the fuel F and the oxygen are mixed in a combustion chamber 16 of the sprayer 2.
• the formed hot combustion gases and/or flame flow through a converging-diverging nozzle 18 for accelerating the flow of the combustion gases.
• the sprayer 2 is further provided with one or more raw material inlets 20 for supplying raw material for the metal coating 6 into the sprayer 2.
• the sprayer 2 comprises also a barrel 22 in which the raw material supplied to sprayer 2 flows together with hot combustion gases and/or reacts with the hot combustion gases and/or the flame.
• the raw material and the combustion gases and/or the flame flow then out of the sprayer 2 through the outlet 23 of the sprayer 2 forming a raw material spray towards the surface of the steel substrate.
• the raw material is supplied to the sprayer 2 as metal powder P or as metal or metal alloy particles 8.
• hot combustion gases and/or flame heat the raw material particles 8.
• the raw material particles 8 may soften or even become at least partly molten in the barrel 23.
• the sprayer 2 is arranged to deposit metal or metal alloy particles 10 flowing the sprayer 2 on the surface of the steel substrate 4, as shown in figure 1, to form a metal coating 6 on the substrate.
• the high speed of the deposited metal or metal alloy particles 10 and the elevated heat of the metal or metal alloy particles 10 enhance formation of the metal coating 6 as the metal or metal alloy particles 10 impact on the surface of the steel substrate 4.
• metal or metal alloy particles 10 adhere to each other and to the surface of the steel substrate 4 for forming the metal coating 6.
• Figure 1 shows schematically a high velocity oxy-fuel sprayer.
• the present invention is not restricted to any specific thermal spraying method or sprayer, but any kind of thermal spraying method and sprayer may be utilized for providing a metal coating 6 according to the present invention.
• the metal coating 6 according to the present invention maybe produced by carrying out the thermal spraying with plasma spraying, flame spraying, cold spraying, electric arc spraying or detonation.
• HVOF spraying is one application of flame spraying.
• the raw material is in particle form, in some application it may also be possible to use metal wire or rod as raw mater supplied into the sprayer 2.
• the metal wire or rod will form metal or metal alloy particles 10 due to the high flow speed and elevated temperature of the combustion gases and/or flame and/or plasma.
• thermal spraying methods such as electric arc spraying and plasma spraying
• the metal particles are heated to high temperatures and in these methods the flow speed of the metal particles is usually slower for providing the coating.
• thermal spraying methods such as detonation and cold spraying
• the metal particles are accelerated to very high speeds and thus the metal particles do not have to be heated to very high temperatures.
• the processes including low processing temperature such as processes in which the temperature of the coating is below the melting temperature of the metal or metal alloy concerned, may be advantageous because then liquid metallurgical issues are not necessary setting substantial limitations.
• Detailed description of different thermal spraying methods and sprayers is omitted in this context, as the present invention does not concern thermal spraying as such.
• the present invention may be carried out with any thermal spraying method and apparatus.
• Figure 1 shows one embodiment of the present invention for producing a colored metal coating 6 on at least part of a steel substrate 4.
• the colored metal coating 6 is provided by depositing metal or metal alloy particles 8 on the steel substrate 4 with thermal spraying using a thermal sprayer 2.
• the coating is carried out by depositing the metal or metal alloy particles 8 together with at least one inorganic coloring agent on the surface steel substrate 4 by thermal spraying.
• the at least inorganic coloring agent is added and/or adhered to the at least one inorganic coloring agent to the metal or metal alloy particles 8 before the thermal spraying and before supplying the metal or metal alloy particles 8 into the thermal sprayer 2.
• thermal spraying process does not necessarily require any binding agent to be added to the material deposited, because the adhesion created by thermal spraying process is mainly created by high velocity and/or high temperature of deposited material . This way, by obviating the use of binding agents, the method provides a steel product having a metal coating in which the metal is closer to the steel surface. This may provide better galvanic protection compared to solutions including binding agent.
• the method can provide a mechanical keying or interlocking and/or diffusion bonding between the colored metal coating and the steel substrate.
• the raw material is supplied into the thermal sprayer 2 as metal powder comprising metal or metal alloy particles 8.
• the inorganic coloring agent may be added and/or adhered to the metal or metal alloy particles 8 by sintering or agglomerating the at least one inorganic coloring agent to the metal or metal alloy particles 8.
• the sintering or agglomeration may be carried out in a sintering furnace or the like such that particles of inorganic coloring agent and the metal particles adhere to each other due to elevated temperature.
• the metal or metal alloy particles 8 are milled together with particles of the inorganic coloring agent for mixing and adhering coloring agent to the metal or metal alloy particles 8.
• the milling the metal or metal alloy particles 8 together with at least one inorganic coloring agent is carried out in a ball mill, rod mill or in another grinding machine suitable for adhering particles of the inorganic coloring agent to the metal or metal alloy particles 8 are mixing the them together.
• other known methods may be used for adhering solid inorganic coloring agent mechanically or chemically to the metal or metal alloy particles 8.
• cold spraying is used for depositing zinc or zinc alloy particles on steel substrate together with inorganic coloring agent as described in this context.
• the metal product may be for example a steel strip, tube, pylon or bridge.
• Cold spraying may therefore be used for providing local colored zinc coatings on steel products.
• cold spraying for example Cold Gas Dynamic Spraying
• metal particles are accelerated in a preheated high pressure gas stream passing through a nozzle, such as De laval type nozzle, before they impact the substrate.
• the impact velocity may be in the range 200 to 1200 m/s and depends mainly on the nozzle geometry, particle size and shape velocity of process gas as well as process gas conditions.
• the impacting particles form dense coating with low oxide content.
• the bonding in cold spraying is caused by the particle deformation during impact and depends on impact conditions.
• the bonding mechanism may be compared to explosive welding or shock wave powder compaction. The bonding is achieved when critical impact velocity is exceeded.
• a raw material for producing a coating 6 on at least part of a steel substrate 4 with thermal spraying, the raw material comprising metal or metal alloy particles 8 to be deposited on the surface of the steel substrate 4.
• the raw material further comprises at least one inorganic coloring agent adhered to the metal or metal alloy particles 8.
• the metal or metal alloy particles 8 comprise zinc particles, or aluminum particles, or magnesium particles or all aluminum and zinc and magnesium particles, or particles comprising zinc or aluminum or magnesium or all for providing a corrosion resistant metal coating 6 on the surface of the steel substrate 4.
• the metal coating of the present invention may be a zinc-based coating, aluminum-based coating or zinc-aluminum based coating or other kind of metal coating.
• the metal coating is zinc-based coating including more than 50% zinc, preferably metallic zinc or metallic zinc with small amount of aluminum (Al) and magnesium (Mg) or the like. This provides better resistance against corrosion. Additional metal particles such as magnesium (Mg) and/or aluminum may be alloyed in small amounts, such as 2-8 weight-% in total, to improve formability, for example.
• the raw material comprises preferably at least 50 weight-% metal or metal alloy from which the coating is made, more preferably more than 60 weight-%, or most preferably more than 75 weight-%.
• the inorganic coloring agent may comprises cobalt, iron, chromium or titanium compounds or oxides thereof. It should be understood that also other inorganic coloring agents may be used.
• the average particle diameter of the used metal or metal alloy particles 8 may be between 0,5 and 150 micrometers, preferably between to 50 micrometers, most preferably 0,5 to 10 micrometers. Respectively the average particle diameter of the inorganic coloring agent may be between 0, 1 and 100 micrometers, preferably between 0, 1 to 5 micrometers, most preferably 0,1 to 1 micrometers.
• the raw material may comprise inorganic coloring agent adhered to the metal or metal alloy particles 8 as particles having average diameter between 0, 1 and 100 micrometers, preferably between 0, 1 to 5 micrometers, most preferably 0, 1 to 1 micrometer.
• the average diameter of the metal or metal alloy particles 8 and the particles of the inorganic coloring agent, and the raw material may decrease. Milling may provide a raw material in which the inorganic coloring agent is mechanically adhered to the metal or metal alloy particles 8.
• the inorganic coloring agent is adhered to the metal or metal alloy particles 8
• chemical methods for adhering the inorganic coloring agent to the metal or metal alloy particles 8 may be used.
• the inorganic metal or metal alloy particles 8 may also be in vapor or liquid phase for adhering to the metal particles.
• the metal or metal alloy particles 8 are coated at least partly with an inorganic coloring agent using a vapor phase deposition method.
• the present invention provides use of raw material comprising metal or metal alloy particles 8 and inorganic coloring agent adhered to at least part of the metal or metal alloy particles 8 in thermal spraying for producing a throughout dyed metal coating on a steel substrate 4.
• the average size or diameter of metal particles can basically vary between 0,5 to 150 micrometer.
• the average metal particle size is 0,5-50 micrometers, most preferably the average metal particle size is small, for instance 0,5- 10 micrometer because smaller particle size may lead to better surface quality and/or color stability and further it makes possible to achieve thin coatings.
• the size or diameter of inorganic coloring particle can basically vary between 0, 1 to 100 micrometer.
• the metal particle size is small, for instance 0, 1-5 micrometer, most preferably 0,1-1 micrometer because smaller inorganic coloring particle size may lead to better surface quality and/or color stability and further it makes possible to achieve advantageous fusion of coloring pigment and metal pigment.
• the sizes of pigments accordingly, one may realize a metal pigment which is surrounded by color pigments.
• the particles of the inorganic coloring agent and the metal or metal alloy particles 8 are not adhered together before the thermal spraying, but they are only mechanically mixed together for forming a powder to be used in thermal spraying before or during supplying them to a thermal sprayer 2.
• the powder comprises thus both metal or metal alloy particles 8 and the particles of at least one inorganic coloring agent.
• the powder is further deposited on the surface of the steel substrate 4 with thermal spraying.
• the average diameter of the metal or metal alloy particles 8 and the particles of inorganic coloring agent are substantially the same such that they will be deposited evenly on the steel substrate 4 for providing a metal coating 6 with homogenous color throughout the coating 6.
• the mass of the metal or metal alloy particles 8 and the particles of inorganic coloring agent may be arranged to be substantially the same such that they will be deposited evenly on the steel substrate 4 for providing a metal coating 6 with homogenous color throughout the coating 6.
• the raw material may be prepared by providing a suspension or a colloidal solution comprising metal or metal alloy particles 8 and at least one coloring agent, the metal or metal alloy particles 8 and the at least one coloring agent being as separate particles 26 in the suspension or colloidal solution, or the coloring agent is adhered to the metal or metal alloy particles 8.
• the suspension or the colloidal solution is then supplied to the thermal sprayer 2.
• the metal and the coloring agent used for providing the colored metal coating 6 are in liquid form and they are supplied to the thermal sprayer as liquid such that they will form particles during the deposition through nucleation as they are vaporized during the thermal spraying.
• Figure 2 shows an alternative embodiment of the present invention in which the at least one inorganic coloring agent is mixed or adhered to the metal or metal alloy particles 8 during the thermal spraying.
• the metal or metal alloy particles 8 are supplied to the thermal sprayer 2 via raw material inlet 20 and the particles 26 of the inorganic coloring agent via coloring agent inlet 24.
• the metal or metal alloy particles 8 and particles 26 of the inorganic coloring agent are supplied separately into the thermal sprayer 2 and mixed together inside the thermal sprayer 2 for depositing them together on the surface of the steel substrate 4.
• the particle spray formed with the thermal sprayer 2 comprises both metal or metal alloy particles 10 and particles 28 of the at least one coloring agent.
• At least one metal particle spray 10 is provided with one or more thermal sprayer 2 and at least one coloring agent spray 28 is provided with one or more coloring agent sprayer (not shown) .
• the thermal sprayer 2 and the coloring agent sprayer are arranged and directed such that the metal particle spray 10 and the coloring agent spray 28 are mixed before the metal particles of the metal particle spray 10 and the coloring agent particles of the coloring agent spray 28 collide to the surface of the steel substrate 4.
• the coloring agent sprayer may be a thermal sprayer or some other kind of sprayer.
• the mixed sprays 10, 28 provide a colored metal coating 6 according to the present invention.
• the average diameter of the metal or metal alloy particles 8 and the particles of inorganic coloring agent are substantially the same such that they will be deposited evenly on the steel substrate 4 for providing a metal coating 6 with homogenous color throughout the coating 6.
• the mass of the metal or metal alloy particles 8 and the particles of inorganic coloring agent may be arranged to be substantially the same such that they will be deposited evenly on the steel substrate 4 for providing a metal coating 6 with homogenous color throughout the coating 6.
• the steel substrate may also be pre-treated before producing the metal coating 6.
• the pre-treating may comprise preheating the steel substrate 4 or at least the surface or surface layer of the steel substrate or product to at least 100 °C, preferably to at least 200 °C or even higher temperature such as about 250°C.
• the temperature of the steel substrate may be raised, momentarily, above the melting point of the metal or metal alloy, for example to temperature of 400 to 700 °C, but the temperature is lowered such that the temperature is below the melting temperature during the coating. Therefore, the elevated temperature of the pre-heating in the context of the present application refers to temperature of the steel substrate during coating.
• the preheating may be carried out by separate heating means such a heating furnace or a flame.
• the thermal sprayer 2 is used for spraying the metal or metal alloy particles and the inorganic coloring agent and the flame or hot combustion gases of the same are used for heating the surface of the steel substrate 4 to the elevated temperature before or during coating.
• the surface to be coated of the steel substrate 4 or product may further be pre-treated by roughening.
• the roughening such as mechanical roughening, may be carried out for example by shot blasting, abrasion, etching or by some other known roughening method.
• the preheating and the roughening of the surface of the steel substrate enhance the adhesion between the coating 6 and the steel substrate 4.
• the surface to be coated of the steel substrate 4 or product may further be pre-treated by pickling or other chemical treatment in order to improve adhesion related properties of the contact surface prior thermal spraying.
• the coated steel substrate 4 or product may be further post-treated with one or more post-treating methods.
• the post heating is carried out by heat treating the coated steel substrate 4 at a temperature of at least 400 °C. This heat treatment may be carried out in a galvannealing furnace. The heat treatment further enhances the adhesion between the colored coating 6 and the steel substrate or product.
• Post-heating may provide heat treating the coated steel strip 4 such that a metal bonding is formed between the metal coating 6 and the steel strip 4.
• the metal bonding may be formed by diffusion bonding between the particles of the metal powder and between the metal particles and the steel substrate.
• the phases at the interface of steel substrate 4 and coating 6, or the boundary layer between the steel substrate 4 and the coating 6, which are formed during or after plating and sintering or post-treatment can be Fe-Zn or Fe-AI- Zn or Fe-AI-Mg-Zn intermetallic compounds similar to compounds after immersion galvanizing, i.e. hot-dip galvanizing and post-dip annealing, ie. annealing after hot-dip galvanizing.
• the coated steel substrate 4 or product may further be coated with a substantially transparent surface coating.
• the surface coating may be provided for example by providing a varnish coating on the colored metal coating 6 or by providing a surface coating on the metal coating 6 by sol- gel process or by some vapor phase coating method such as chemical vapor deposition.
• excess heat which is generated in thermal spraying may be used in heating of the steel substrate 4.
• the excess heat i .e. heat generated by the thermal sprayers 2
• the method of the present invention may be used for coating separate steel products or it may also be carried out as a continuous process for coating a steel strip.
• the present invention provides also an arrangement for producing a metal coating 6 on a steel strip 4.
• the arrangement comprises a pre-heating unit 30 for heating the steel strip 4 to an elevated temperature and a coating unit 34 for producing a metal coating 6 on at least part of the steel strip 4, as shown in figure 3.
• figure 3 is only very schematic and the continuous coating process for a steel strip 4 may be carried with many alternative arrangements and methods and for different kinds of metal coatings.
• the arrangement can be implemented for instance in a continuous hot-dip galvanizing line.
• Figure 3 shows schematically an arrangement for providing a zinc-based coating on a steel strip 4.
• the coating unit 34 comprises one or more thermal sprayers 2 for depositing metal or metal alloy particles 8, 10 on the surface of the steel strip 4.
• the thermal spraying in the coating unit may be carried out as described above.
• the steel strip 4 is transported along a process line with rollers 40.
• At least one of the thermal sprayers 2 of the coating unit 34 is arranged to deposit at least one inorganic coloring agent on the surface of the steel substrate 4 for providing the metal coating 6 with inorganic coloring agent embedded into metal coating 6.
• At least one of the thermal sprayers 2 may be arranged to: deposit particles 26, 28 of at least one inorganic coloring agent mixed with metal or metal alloy particles 8, 10; or deposit metal or metal alloy particles 8, 10 comprising at least one inorganic coloring agent; or mix particles 26 of at least one inorganic coloring agent with the metal or metal alloy particles 8 inside the thermal sprayer 2 and deposit them together; or provide a coloring agent spray 28 and to mix the coloring agent spray 28 with at least one metal particle spray 10 provided with another thermal sprayer.
• the pre-heating unit 30 may be arranged to heat the steel strip to at least 100 °C, and preferably to at least 200 °C.
• the arrangement may further comprise surface roughening unit 32 for roughening the surface of the steel strip 4 before the coating.
• the surface roughening unit 32 may be arranged before or after the pre-heating unit 30 and it may comprise for example shot blasting, abrasion or etching the surface of the steel strip 4.
• the arrangement may further comprise a post-heating unit 36 for heat treating the coated steel substrate 4.
• the post-heating unit 36 may be arranged to heat treat the coated substrate 4 at a temperature of at least 400 °C, but preferably below the melting temperature of the metal or metal alloy concerned.
• the post-heating unit 36 is a galvannealing furnace. Post-heating may provide metal bonding between the steel strip 4 and the metal coating 6. After spraying, the steel strip may be cooled by liquid or other opportune medium, which may include passivation chemicals or protective oil .
• the steel substrate is coated by multi-stage metal coating process.
• the coating process includes at least two stages: at least the first stage and the second stage.
• the steel strip is galvanized as usual, such as hot-dip galvanized as usual, and subsequently, in said second stage, subjected to the coating process, such as by using said coating unit 2, according to the independent claim 1.
• the metal coating obtained thereby includes different metal layers: first metal layer which includes pure metal without coloring agent and second metal layer which includes coloring agents.
• the first metal layer is applied in the first stage before the second metal layer applied in the second stage. In case the second stage is accomplished when the heat of metal coating gained in the first stage is still available, i .e.
• the second metal layer i .e. the throughout colored metal coating deposited in the second stage will form metal bonding with first metal layer, ie. with pure metal layer obtained in the first stage.
• the throughout colored metal coating may be applied to the steel strip having warm or even melt first metal layer, preferably zinc layer, on the steel strip after first stage. Solution provides for layers which are tightly attached to each others due the metal bonding . This may be accomplished in commonly used hot dip galvanizing - lines in the industry.
• providing a throughout colored coating on a steel substrate may be carried out after galvanizing at least part of the steel substrate 4 such that the throughout colored metal coating 6 is formed on a zinc layer for providing a metal coating having a zinc layer and a throughout colored metal layer 6 on the zinc layer.
• the arrangement according to the present invention may be provided to a continuous galvanizing line downstream of a galvanizing unit, preferably hot-dip galvanizing unit, such that the throughout colored metal coating 6 is formed on a zinc layer for providing a metal coating having a zinc layer and a throughout colored metal layer 6 on the zinc layer.
• the apparatus arrangement comprises at least two coating units, first coating unit (not drawn) and the second coating unit 2 for first and the second coating stages, respectively.
• the sprayed coating may be further levelled by slight rolling.
• the arrangement may further comprise a coiling and/or cutting unit 38, depending on the application.
• the steel strip is transferred and/or cooled in protective gas after the pre-heating and before the spraying at desired temperature. Therefore arrangement may be provided with means for providing the protective gas atmosphere to the pre-heating unit 10 for carrying out the pre-heating protective atmosphere.
• the means for producing the protective gas atmosphere may for example comprise a pre-heating chamber substantially isolated from the ambient atmosphere for example with gas curtains or the like.
• the means for providing the protective gas atmosphere may also comprise gas supplies for supplying protective gas into the heat treatment chamber. This provides for non-oxidized surface prior coating enhancing the adhesion.
• the protective atmosphere prevents or diminishes oxidation of the metal coating and/or the steel substrate and provides for a surface with good adhesion potential .
• the protective atmosphere is preferable in pre-heating step before the coating of the steel substrate, and the steel substrate 4 is transported to the coating unit 2 in protective gas atmosphere.
• temperature of the steel product after the pre- heating and before the thermal spraying is less than melting point of zinc.
• temperature of the steel product after the pre-heating and before the spraying is more than melting point of zinc.
• the arrangement may also comprise heat transfer means 41, 42 for transferring excess heat generated by the thermal sprayers 2 in the coating unit 34 to the pre-heating unit 30 and/or to the post-heating unit 36.
• the heat transfer means 41, 42 may thus enhance significantly the overall energy efficiency of the process. For instance, in continuous hot-dip galvanizing line, there is needed a lot of heat in the heating section, i.e. in the recrystallization furnace.
• At least part of the heat can be transmitted from the upstream of the process, i.e. from the thermal spraying coating unit 34 to the pre-heating section.
• the heat energy may transmitted from downstream of the process, i.e. from the thermal spraying coating unit 34, to galvannealing furnace.
• Coating unit 34 may be thermally insulated from the ambient air, by suitable enclosure or such, in order to ensure controlled recovery of heat energy.
• the heat transfer means may be arranged to conduct the excess heat in gaseous or in liquid phase.
• the method, arrangement and raw material of the present invention as described above enable forming a steel product 4 having a metal coating 6 on at least part of a surface of the steel product 4.
• the metal coating 6 of the present invention consists at least partly of metal or metal alloy particles 8, 10 deposited on the surface of the steel product.
• the metal coating 6 further comprises inorganic coloring agent embedded into the metal coating 6. As disclosed above, the coloring agent is deposited on the surface of the steel product 4 together with metal or metal alloy particles 8, 10 by thermal spraying. The inorganic coloring agent is adhered to the metal or metal alloy particles 8, 10 in the metal coating 6 before or during thermal spraying and thus before the coating 6 is produced. Alternatively, the inorganic coloring agent may be embedded between the metal or metal alloy particles 8, 10 in the metal coating.
• the colored metal coating 6 may be provided such that the thickness of the metal coating 6 is at least 10 micrometers, or at least 50 g/m 2 .
• the colored metal coating 6 may be provided by providing several layers on top of each other and one layer may be such as 20 to 100 micrometers thick.
• the overall thickness of the coating may be for example 150 micrometers or 137 g/m 2 .
• the metal coating 6 may be a zinc-based coating, aluminum-based coating or zinc-aluminum or zinc-aluminium- magnesium based metal coating 6 or that the metal or metal alloy particles 8, 10 comprise zinc particles, or aluminum particles, magnesium particles or all aluminum and zinc particles, or particles comprising zinc or aluminum or magnesium or all .
• the amount of zinc and aluminum in an aluminum-zinc coating may vary between 0 to 100 %.
• a zinc-aluminium coating may be pure zinc coating or pure aluminium coating or it may comprise both zinc and aluminium in desired ratio.
• the inorganic coloring agent may comprise, depending on the desired colour, one or more of cobalt, iron, chromium or titanium compounds or oxides thereof, such as Co 2 O 4 , CoAI 2 O 4 , Co(AI,Cr) 2 O 4 , Co(AI,Cr) 2 O 4 , (Co,Ni,Zn) 2 (Ti,AI)O 4 , (Fe,Cr)O 3 , Fe(Fe,Cr) 2 O 4 , Cu(Cr,Fe) 2 O 4 , CuCr 2 O 4 , Cu(Cr,Fe) 2 O 4 , Co(Cr,Fe) 2 O 4 , Cr 2 O 3 , (Ni,Sb,Ti)O 2 , (Ni,C
• inorganic coloring agent Preferable metal oxides or compounds are used as inorganic coloring agent because of their high temperature resistant.
• the amount of the inorganic coloring agent in the produced coating may vary from 5 to 40 weight-% of the volume of the coating, and preferably about 20 weight-%, depending on the desired color of the coating 6. According to the above mentioned the present invention enables to provide a thin throughout colored metal coating 6 having good corrosion resistance.
• the colored metal coating 6 may further comprise transparent surface coating on the colored metal coating 6, such as varnish coating.
• the steel product of the present invention may be for example a hot- or cold-rolled strip steel or steel plate, or further a processed component thereof, such as an external building element or a part thereof, roofing element, structural element, part of a building or structure, a part of a vehicle or a component of an apparatus used in an industrial process or plant.
• a processed component thereof such as an external building element or a part thereof, roofing element, structural element, part of a building or structure, a part of a vehicle or a component of an apparatus used in an industrial process or plant.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Other Surface Treatments For Metallic Materials (AREA)
• Coating By Spraying Or Casting (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=44318392

Family Applications (1)

Country Status (3)

Families Citing this family (3)

Family Cites Families (2)

• 2011
  • 2011-07-06 FI FI20115719A patent/FI124667B/fi not_active IP Right Cessation
• 2012
  • 2012-07-06 WO PCT/FI2012/050712 patent/WO2013004913A2/en active Application Filing
  • 2012-07-06 EP EP12766454.8A patent/EP2729593A2/de not_active Withdrawn

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events