EP3880860B1 - Verfahren zur verzinkung, insbesondere feuerverzinkung, von eisen- und stahlerzeugnissen - Google Patents

Verfahren zur verzinkung, insbesondere feuerverzinkung, von eisen- und stahlerzeugnissen Download PDF

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Publication number
EP3880860B1
EP3880860B1 EP19801839.2A EP19801839A EP3880860B1 EP 3880860 B1 EP3880860 B1 EP 3880860B1 EP 19801839 A EP19801839 A EP 19801839A EP 3880860 B1 EP3880860 B1 EP 3880860B1
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Prior art keywords
aluminum
range
iron
hot
zinc
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German (de)
English (en)
French (fr)
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EP3880860A1 (de
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Thomas PINGER
Lars Baumgürtel
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Fontaine Holdings NV
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Fontaine Holdings NV
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    • 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
    • C23C2/003—Apparatus
    • C23C2/0038—Apparatus characterised by the pre-treatment chambers located immediately upstream of the bath or occurring locally before the dipping process
    • 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

Definitions

  • the present invention relates to the technical field of galvanizing iron-based or iron-containing components, in particular steel-based or steel-containing components (steel components), preferably for the automobile or motor vehicle industry, but also for other technical fields of application (e.g. for the construction industry, the field of general mechanical engineering, the electrical industry, etc.), by means of hot-dip galvanizing (hot-dip galvanizing).
  • steel-based or steel-containing components steel components
  • hot-dip galvanizing hot-dip galvanizing
  • the present invention relates to a method for producing an aluminum-alloyed or aluminum-containing zinc layer, in particular with an increased layer thickness, on an iron-based component, in particular steel component, and also the products obtainable by the method according to the invention (i.e. hot-dip galvanized iron-containing components) and their respective use.
  • components made of steel for the motor vehicle sector such as. B. for cars, trucks, commercial vehicles, etc., but also for other technical areas (e.g. construction industry, mechanical engineering, electrical industry, etc.), often require efficient corrosion and / or wear protection, which also withstands long-term stress.
  • galvanizing it is known to protect steel-based components against corrosion and wear by means of galvanizing (galvanizing).
  • galvanizing When galvanizing, the steel is provided with a layer of zinc to protect the steel from corrosion and wear.
  • Various galvanizing processes can be used to galvanize steel components, i.e. to coat them with a metallic coating of zinc, in particular hot-dip galvanizing (also known as hot-dip galvanizing), spray galvanizing (flame spraying with zinc wire), diffusion galvanizing (Sherard galvanizing ), galvanizing (electrolytic galvanizing), non-electrolytic galvanizing using zinc flake coatings and mechanical galvanizing.
  • hot-dip galvanizing also known as hot-dip galvanizing
  • spray galvanizing flame spraying with zinc wire
  • diffusion galvanizing Stard galvanizing
  • galvanizing electrolytic galvanizing
  • non-electrolytic galvanizing using zinc flake coatings and mechanical galvanizing.
  • Hot-dip galvanizing is probably the most important method of protecting steel against corrosion, but also protecting it against wear and tear with metallic zinc coatings.
  • Steel is immersed continuously (e.g. strip and wire) or piecemeal (e.g. components) at temperatures of around 450 °C to 600 °C in a heated tank with liquid zinc (melting point of zinc: 419.5 °C C), so that a resistant alloy layer of iron and zinc forms on the steel surface and a very firmly adhering layer of pure zinc forms above it (cf. also Figure 1A ).
  • Hot-dip galvanizing is therefore a method that has been recognized and proven for many years to protect parts or components made of ferrous materials, especially steel materials, from corrosion, but also from wear.
  • the typically pre-cleaned or pre-treated component is immersed in a liquid-hot zinc bath, which reacts with the molten zinc and, as a result, forms a zinc layer that is metallurgically bonded to the base material.
  • discontinuous batch galvanizing cf. e.g. DIN EN ISO 1461
  • continuous strip and wire galvanizing cf. e.g. DIN EN 10143 and DIN EN 10346.
  • Both batch galvanizing and strip and wire galvanizing are standardized processes.
  • Continuously galvanized steel strip and continuously galvanized wire are each a preliminary or intermediate product (semi-finished product), which is further processed after galvanizing, in particular by forming, punching, cutting, etc., whereas components to be protected by piece galvanizing are first completely manufactured and only then hot-dip galvanized (which protects the components from corrosion all around).
  • Strip/wire galvanizing and batch galvanizing also differ in terms of the zinc layer thickness, which results in different protection periods - also depending on the zinc layer.
  • the zinc layer thickness of strip-galvanized sheet metal is usually at most 20 to 25 microns, whereas the zinc layer thickness of piece-galvanized steel parts can usually be in the range of 50 to 200 microns and even more.
  • Hot-dip galvanizing provides both active and passive protection against corrosion. Passive protection is provided by the barrier effect of the zinc coating. The active corrosion protection is due to the cathodic effect of the zinc coating. Compared to more noble metals of the electrochemical series, such. B. iron, zinc serves as a sacrificial anode, which protects the underlying iron from corrosion until the zinc itself is completely corroded.
  • Conventional hot-dip galvanizing is based in particular on dipping iron or steel components into molten zinc to form a zinc coating or coating on the surface of the components.
  • a thorough preliminary surface preparation of the components to be galvanized is generally required, which usually includes degreasing followed by rinsing, followed by acid pickling followed by rinsing and finally fluxing (i.e. a so-called fluxing ) with subsequent drying process.
  • the typical procedure for conventional batch galvanizing using hot-dip galvanizing is usually as follows: First, the component surfaces of the relevant components are subjected to degreasing in order to remove residues of fats and oils, with aqueous, alkaline or acidic degreasing agents usually being able to be used as degreasing agents. After cleaning in the degreasing bath, a rinsing process usually follows, typically by immersion in a water bath, in order to avoid carrying over degreasing agents with the galvanizing material into the subsequent pickling process step is of great importance.
  • a pickling treatment (pickling) is usually carried out, which is used in particular to remove native impurities, such as e.g. B. rust and scale, from the steel surface is used.
  • Acid pickling is usually carried out in diluted hydrochloric acid, with the duration of the pickling process depending, among other things, on the degree of contamination (e.g. degree of rusting) of the goods to be galvanized and the acid concentration and temperature of the pickling bath.
  • a rinsing process (rinsing step) is usually also carried out after the pickling treatment.
  • fluxing (synonymously also referred to as flux treatment), whereby the previously degreased and pickled steel surface is treated with a so-called flux, which is typically an aqueous solution of inorganic chlorides, most commonly a mixture of zinc chloride (ZnCl 2 ) and ammonium chloride (NH 4Cl ).
  • flux typically an aqueous solution of inorganic chlorides, most commonly a mixture of zinc chloride (ZnCl 2 ) and ammonium chloride (NH 4Cl ).
  • ZnCl 2 zinc chloride
  • NH 4Cl ammonium chloride
  • the flux should increase the wetting ability between the steel surface and the molten zinc.
  • the flux treatment is then usually followed by drying in order to produce a solid flux film on the steel surface and to remove adhering water, so that subsequent undesirable reactions (in particular the formation of water vapor) in the liquid zinc immersion bath are avoided.
  • the components pretreated in the manner mentioned above are then hot-dip galvanized by immersion in the molten zinc.
  • the zinc content of the melt is at least 98.0% by weight according to DIN EN ISO 1461.
  • the galvanizing After the galvanizing has been immersed in the molten zinc, it remains in the molten zinc bath for a sufficient period of time, in particular until the galvanizing has reached its temperature and is coated with a layer of zinc.
  • oxides, zinc ash, flux residues and the like are removed from the surface of the zinc melt, in particular, before the galvanizing product is pulled out of the zinc melt again.
  • the hot-dip galvanized in this way The component is then subjected to a cooling process (e.g. in air or in a water bath). Finally, any existing holding means for the component, such. B. slings, tie wires or the like removed.
  • a passivation or sealing can also be carried out as part of the post-treatment.
  • post-processing or post-treatment can usually be carried out.
  • a criterion for the quality of hot-dip galvanizing with pure zinc is the thickness of the zinc coating in ⁇ m (micrometers).
  • the DIN EN ISO 1461 standard specifies the minimum values for the required coating thicknesses that are to be supplied for batch galvanizing depending on the material thickness. In practice, the layer thicknesses are significantly higher than the minimum layer thicknesses specified in DIN EN ISO 1461.
  • zinc coatings produced by batch galvanizing with pure zinc have a thickness in the range of 50 to 200 microns and even more.
  • a relatively brittle layer based on an alloy (mixed crystal layer) between iron and zinc (Fe/Zn phase layer) first forms on the steel surface and only then does the pure zinc layer form (cf. Figure 1A ).
  • the relatively brittle iron/zinc alloy layer improves adhesion to the base material, but makes it difficult to form the galvanized steel.
  • Higher silicon contents in the steel, as they are used in particular for so-called calming of the steel during its production lead to increased reactivity between the zinc melt and the base material and consequently to strong growth of the iron/zinc alloy layer. This leads to the formation of relatively large overall layer thicknesses. Although this allows for a very long corrosion protection period, the thicker the zinc layer, the greater the risk that the layer will flake off under mechanical stress, in particular local sudden impacts, and the corrosion protection effect will be disrupted as a result.
  • Components hot-dip galvanized with a zinc/aluminium melt can be formed without any problems due to their low layer thickness, but still have improved corrosion protection properties (i.e. generally improved compared to the thicker galvanizing layers from hot-dip galvanizing with pure zinc).
  • a zinc/aluminium alloy used in the hot-dip galvanizing bath also has better fluidity properties and a lower melting point than pure zinc.
  • zinc coatings produced by hot-dip galvanizing using such zinc/aluminium alloys have greater corrosion resistance (which is up to six times better than that of pure zinc), better appearance, improved formability and better paintability than pure zinc formed zinc coatings. This technology can also be used to produce lead-free zinc coatings.
  • Such a hot-dip galvanizing process using a zinc/aluminum melt or using a zinc/aluminum hot-dip galvanizing bath is known, for example, from WO 2002/042512 A1 and the relevant publication equivalents to this patent family (e.g. EP 1 352 100 B1 , DE 601 24 767 T2 and U.S. 2003/0219543 A1 ).
  • Suitable fluxes for hot-dip galvanizing using molten zinc/aluminum baths are also disclosed there, since flux compositions for zinc/aluminum hot-dip galvanizing baths have to be different from those for conventional hot-dip galvanizing with pure zinc.
  • anti-corrosion coatings can be produced with very small layer thicknesses (generally below 25 micrometers, typically in the range from 2 to 15 micrometers) and with very low weight with high cost-efficiency, the method described there being commercially available under the name microZINQ ® procedure is applied.
  • the zinc layer can be significantly influenced by alloying elements in the zinc melt.
  • Aluminum is one of the most important elements here: It has been shown that with an aluminum content of just 100 ppm (weight-based) in the molten zinc, the appearance of the resulting zinc layer can be improved towards a brighter, shinier appearance. This effect increases steadily with increasing aluminum content in the zinc melt up to 1,000 ppm (weight-based).
  • the anti-corrosion effect of a zinc layer is influenced on the one hand by the composition of the zinc layer and on the other by the thickness of the zinc layer.
  • the zinc layer should only be as thick as is necessary for the relevant area of application and the expected service life.
  • the zinc layers formed by a classic hot-dip galvanizing ie in a pure zinc bath
  • the zinc layers of an average of 8 to 15 ⁇ m, which are formed by hot-dip galvanizing in zinc/aluminium alloys are considerably thinner.
  • a particular disadvantage of using aluminum-alloyed or aluminum-containing zinc melts is that the formation of thicker or individually adjustable zinc layers is not possible within the framework of the known processes. Because as soon as the maximum layer thickness of the aluminum-alloyed zinc coating has been reached using conventional methods, even a longer residence time in the zinc/aluminium melt does not lead to any further increase in the zinc layer thickness, since the formation of the Fe/Al phase in the form of a barrier layer (barrier layer) the kinetics of the zinc layer growth is blocked, which in turn limits the layer growth and a maximum layer thickness cannot be exceeded.
  • the WO 2017/153062 A1 relates to a system and a method for hot-dip galvanizing of components, preferably for large-scale hot-dip galvanizing of a large number of identical or similar components, in particular in discontinuous operation, preferably for batch galvanizing.
  • the EP 0 337 402 A1 relates to a two-stage zinc alloy or galvanizing process, in which the component to be coated is first galvanized in an essentially pure zinc melt in a temperature range of 430 to 480 °C, then subjected to cooling and then immersed in another zinc bath , which contains at least 0.1% by weight Aluminum has, wherein the coating takes place in the second zinc bath at a temperature in the range of 390 to 460 ° C.
  • the WO 2012/083345 A1 relates to an in-line process for galvanizing an elongate element with a coating comprising zinc and aluminum, the aluminum being contained in an amount of 5 to 20% by weight, the process comprising the following steps: cleaning and application of an alkali metal-free applying flux to an outer surface of the component, drying the flux on the element and preheating the element, passing the preheated element through a bath comprising the zinc and aluminum coating, and then removing the coated element.
  • the problem underlying the present invention is therefore to provide a method for hot-dip galvanizing (hot-dip galvanizing), in particular iron-based or iron-containing components, preferably steel-based or steel-containing components (steel components), using an aluminum-containing or aluminum-alloyed zinc melt, the previously described Disadvantages of the prior art are to be at least largely avoided or at least mitigated.
  • such a method is to be provided which, compared to conventional hot-dip galvanizing methods using aluminum-containing or aluminum-alloyed zinc melts, enables an individual or specifically adaptable increase in the zinc layer thickness obtained when using aluminum-alloyed or aluminum-containing galvanizing baths and in particular also improved process economy and/or enables a more efficient, in particular more flexible and/or more reliable, in particular less error-prone process flow and/or improved business compatibility and/or improved use of costs and resources.
  • the present invention proposes - according to a first aspect of the present invention - a method for hot-dip galvanizing according to claim 1; further, particularly special and/or advantageous configurations of the method according to the invention are the subject matter of the relevant method dependent claims.
  • the present invention relates—according to a second aspect of the present invention—to a hot-dip galvanized (hot-dip galvanized) iron-based component, preferably a steel component, obtainable by the method according to the invention, according to the relevant independent product claims; further, particularly special and/or advantageous configurations of this aspect of the invention are the subject matter of the relevant product dependent claims.
  • a hot-dip galvanized (hot-dip galvanized) iron-based component preferably a steel component
  • the present invention relates—according to a third aspect of the present invention—to the use of a hot-dip galvanized (hot-dip galvanized) iron-based component according to the invention for automobile production or for the technical field according to the relevant independent use claims.
  • the present invention relates to the use of increasing and/or adjusting the surface roughness for adjusting and increasing the zinc layer thickness according to the relevant independent claim for use.
  • the present invention is associated with a large number of completely unexpected advantages, special features and surprising technical effects, the following description of which makes no claim to completeness, but illustrates the inventive character of the present invention:
  • the mechanical processing of the iron-based component surface and the resulting adjustment of the surface roughness in step (a) make it possible to adjust the zinc layer thickness in the subsequent step (b) in a targeted manner and thus to increase and adjust the zinc layer thickness in a targeted manner (and although without the quality of the resulting anti-corrosion properties and the resulting mechanical properties being impaired in particular).
  • the term "increase or increase in the surface roughness” relates to the original surface condition of the component (ie before step (a) was carried out).
  • the mechanical increase or adjustment of the surface roughness in process step (a) means that in the subsequent hot-dip galvanizing step (b) the layer thickness of the aluminum-alloyed or aluminum-containing galvanizing layer compared to conventional hot-dip galvanizing with a Zn/Al melt (ie without pretreatment according to step ( a)) can be significantly increased or adjusted individually is completely surprising and was not to be expected by a person skilled in the art. Because in the hot-dip galvanizing processes known from the prior art using a Zn/Al melt, the thin barrier layer (Fe/Al phase layer, approx. 500 nm) that forms due to the high affinity of aluminum for iron increases the thickness of the galvanizing layer opposite.
  • the thin barrier layer Fe/Al phase layer, approx. 500 nm
  • the mechanical roughening of the component surface in question and the resulting adjustment of the surface roughness can be used to specifically or individually adjust the layer thickness of the galvanized layer produced by hot-dip galvanizing with a Zn/Al melt, with compared to conventional Hot-dip galvanizing process with a Zn/Al melt the resulting galvanizing layer thicknesses can be significantly increased or increased or adjusted.
  • the phenomenon described above can be explained in particular (at least among other things) by the fact that the increase or adjustment of the surface roughness leads to a change in the drainage behavior, which means that the zinc layer thickness - depending on the Surface roughness - increased, with the result that there is an increase in the anti-corrosion effect, as well as mechanical and other properties. Due to the increased zinc layer thickness, an increase in the anti-corrosion effect is achieved, based on the occurrence of base material corrosion (red rust). Furthermore, the mechanical resistance also improves, in particular the resistance of the component to an applied load, above all the abrasion resistance, which describes the resistance to friction, and also the adhesive strength and the resilience as a result of impact or impact-type influences, such as stone chips. This finding is all the more surprising given that zinc layers that are produced using the classic batch galvanizing process become more susceptible to mechanical stress as the layer thickness increases.
  • the present invention it is thus possible to further improve the excellent properties of aluminum-alloyed or aluminum-containing zinc layers, which have properties that are superior to pure zinc layers. It is therefore not necessary to resort to a pure zinc melt with inferior properties for an increased layer thickness; because, surprisingly, the layer thickness of an aluminum-alloyed or aluminum-containing zinc layer can be increased in a targeted manner by the method according to the invention and even adjusted in a tailor-made or individual manner.
  • the hot-dip galvanized iron-based components that can be obtained according to the invention also have all the other advantages associated with a zinc/aluminium alloy compared to zinc coatings formed from pure zinc, such as B. improved optics, improved formability and better paintability.
  • B. improved optics improved formability and better paintability.
  • the total layer thickness resulting from the process according to the invention is not only higher than with identical hot-dip galvanizing without prior roughening of the surface, but - depending on the set surface roughness - is always reproducible, i. H. if the surface roughness is set identically in process step (a), identical hot-dip galvanizing conditions according to process step (b) always result in identical aluminum-alloyed or aluminum-containing zinc-coated layers, in particular with identical layer thicknesses. Due to this good reproducibility, the method according to the invention can also be used in large-scale production or in large-scale production.
  • a further advantage of the method according to the invention is that the surface roughness can be increased or adjusted both on the entire component and only partially in selected areas of the component and thus a targeted reinforcement or increase or adjustment of the zinc layer thickness can only take place in the required areas. so that application-specific solutions can be achieved for the respective area of application. This results in a reduction in costs and resources.
  • An area by area Increasing the thickness of the aluminum-alloyed or aluminum-containing zinc coating of a component can, for example, make sense if only the relevant areas of a component are exposed to increased corrosion and/or increased mechanical stress (e.g. special vehicle support components in body construction, special building components, etc. ).
  • the surface roughness introduced in step (a) in the method according to the invention is at least largely or even completely flattened or leveled in the subsequent hot-dip galvanizing according to step (b), so that ultimately a continuous and uniform surface of the aluminum-alloyed or aluminum-containing galvanized layer results, whereby the surface roughness introduced in step (a) does not impair the surface quality of the hot-dip galvanized component obtained after step (b) and thus the end use is not restricted.
  • a further advantage of the present invention is that by increasing or adjusting the surface roughness, mechanical cleaning of the components takes place at the same time, so that the cleaning effort before the galvanizing process is reduced. Above all, cleaning by means of pickling in an acidic medium can be significantly reduced or even completely omitted. This also significantly reduces or even completely eliminates the undesired possible entry of hydrogen from the acidic pickling solution into the galvanizing material. This is particularly advantageous for high-strength and ultra-high-strength steel components with a strength of more than 1,000 MPa, for which there is an increased risk of embrittlement due to hydrogen according to DIN 55969, which is why the pickling time is limited to less than 15 minutes even for high-strength components. In addition, the shortening or omission of pickling results in an improvement from a business point of view, above all an improvement in the use of costs and resources.
  • the special features of the process according to the invention are also directly reflected in the process products that can be obtained, i. H. the hot-dip galvanized iron-based components:
  • the hot-dip galvanized components obtainable according to the invention not only have improved mechanical properties and improved corrosion properties as a result of the aluminium-containing or aluminium-alloyed galvanizing layer, but can also be provided with a tailor-made aluminum-alloyed or aluminium-containing zinc layer, in particular precisely adapted to the corresponding requirements be provided.
  • the components according to the invention are characterized by a special surface structure (cf. Figure 1C such as figs 3A and 3B ):
  • Figure 1C such as figs 3A and 3B
  • the components according to the invention have a significantly higher or set roughness of the surface of the base material compared to non-roughened component surfaces, which, however, is at least essentially completely leveled in the finished end product by the applied aluminum-containing or aluminum-alloyed zinc coating or is leveled.
  • the microscopic investigations show that the upper aluminum-containing or aluminum-alloyed hot-dip galvanized layer is significantly thicker than hot-dip galvanized layers produced by hot-dip galvanizing without prior roughening.
  • the increase in layer thickness leads in the same way to improved anti-corrosion properties and improved mechanical properties (e.g. improved abrasion resistance, improved wear protection properties, etc.), since the other properties of the aluminum-containing or aluminum-alloyed zinc coating are not impaired by the pretreatment according to the invention, in particular not their Adhesion in relation to the underlying material surface.
  • the products according to the invention therefore have a special layer structure, which can be documented and proven by microscopic examinations of sections of the products in question (cf. Figures 1A, 1B and 1C as well as 3A and 3B discussed below in comparison to those produced by conventional methods shifts according to figs 1A and 1B ).
  • the remains before hot-dip galvanizing treatment roughening of the surface carried out in the microscopic section can also be seen or verified in the end product.
  • an efficient and economical hot-dip galvanizing process can thus be provided, with the disadvantages of the prior art described above being at least largely avoided or at least mitigated.
  • the method according to the invention initially comprises a method step (a) of increasing and/or adjusting the surface roughness of at least one surface of the iron-based component, preferably a steel component.
  • the surface roughness is increased and/or adjusted (also referred to synonymously as surface roughness or surface roughness).
  • surface roughness (synonymously also referred to as roughness) is a term from surface physics that describes the unevenness of the surface height.
  • the surface roughness can be characterized by so-called roughness parameters, in particular by the so-called mean roughness value Ra, the mean roughness depth Rz and the maximum roughness depth Rmax.
  • the relevant roughness parameters and their measurements are regulated and specified in particular in DIN EN ISO 4288:1998-04. This will be discussed in more detail below.
  • the surface roughness can be increased and/or adjusted in method step (a) on at least one surface of the iron-based component, preferably on a plurality of surfaces of the iron-based component.
  • the surface roughness can be increased and/or adjusted in method step (a) on the entire iron-based component, in particular on all surfaces of the iron-based component.
  • This particular embodiment of the present invention is particularly advantageous when components are exposed to a particularly high load over their entire surface, which components can then be provided with a zinc coating with an increased zinc coating thickness as a whole or as a whole.
  • the surface roughness can be increased and/or adjusted in method step (a) only in certain areas, in particular only on one surface and/or not on all surfaces of the iron-based component.
  • Such an embodiment is particularly advantageous when components are only partially or locally exposed to increased stress (e.g. corrosion stress and/or wear stress) when they are used, so that only these relevant areas have to be protected more intensively, namely through training a galvanizing layer that is thicker in the relevant areas. It is thus also possible within the scope of the method according to the invention to increase or adjust the surface roughness only on those surfaces of a component which, because of their arrangement in the end product, require an increased zinc layer thickness.
  • chassis components used in the automotive sector can only be additionally reinforced on their side facing the road, since these surfaces are increasingly exposed to stone chipping, corrosion stress from de-icing salt, thermal stress due to the exhaust gas duct running above and increased mechanical stress .
  • the zinc layer thickness can be increased locally or in certain areas in a targeted manner only at the relevant wear points of the component and thus the resistance can only be improved in a targeted manner there.
  • the surface roughness is increased and/or adjusted by mechanical treatment.
  • Mechanical treatment methods for increasing and/or adjusting the surface roughness are well known as such to those skilled in the art.
  • this increase and/or adjustment of the surface roughness in process step (a) is concerned by mechanical treatment, this increase and/or adjustment of the surface roughness is carried out by means of abrasion and/or by means of an abrasive process, preferably by means of compressed air jets with solid blasting material (synonymous also as referred to as "sandblasting").
  • abrasion or an abrasive process is to be understood as meaning, in particular, the abrasive removal, ie the removal of material through the mechanical action of a friction(ing) partner.
  • the abrasive removal ie the removal of material through the mechanical action of a friction(ing) partner.
  • the roughness peaks of one friction partner penetrate the surface layers of the other, or hard particles from an intermediate material penetrate the surface layers of the friction partner, resulting in micro-chipping, scratching, scoring or the like.
  • This effect is used within the scope of the invention when increasing or adjusting the surface roughness, for example by means of compressed air blasting with solid blasting material (blasting agent).
  • compressed air blasting With compressed air blasting, compressed air serves as a carrier medium for the blasting material to be accelerated, which is thus brought to the surface to be treated and whose impact has an abrasive effect.
  • a particular advantage of using compressed air blasting systems is the extensive adaptability to the size, shape and surface requirements of the objects to be processed, as well as the almost unlimited usability of a wide variety of metallic, mineral and organic blasting material (also called “blasting media" as a synonym), so that the right system can be selected for each application or the system can be adapted to the object to be processed.
  • the blasting material (blasting agent) used can be selected in particular from the group of metallic, mineral (inorganic) and organic blasting material and combinations thereof, preferably in particulate form, preferably from the group of metallic, natural-mineral, synthetic-mineral , natural-organic and synthetic-organic blasting material and combinations thereof, in particular particulate stainless steel blasting material and/or glass bead blasting material.
  • the blasting material used in process step (a) has a round, spherical, angular or cylindrical grain shape, preferably an angular grain shape.
  • edged blasting material is particularly preferred, since this allows strong roughening in a short time and with low steel pressure.
  • the blasting material used in process step (a) has an absolute grain size in the range from 30 to 5000 ⁇ m, in particular in the range from 50 to 3000 ⁇ m, preferably in the range from 60 to 1500 ⁇ m, particularly preferably in the range from 70 to 1000 ⁇ m, very particularly preferably in the range from 75 to 800 ⁇ m.
  • This grain size is particularly suitable for roughening the surface without permanently damaging or changing the components. In the case of irregular formation of the blasting material or the blasting material particles, the grain size is related to the largest extent of the blasting material particles.
  • the blasting material used in process step (a) has a hardness, in particular grain hardness, preferably Vickers hardness, in the range from 20 to 2500 HV, in particular in the range from 100 to 2100 HV, preferably in the range from 200 to 2000 HV in the range of 250 to 1,500 HV.
  • the blasting material used in process step (a) has a hardness, in particular grain hardness, preferably Mohs hardness, in the range from 2 to 9 Mohs, in particular in the range from 2.5 to 8 Mohs, preferably in the range from 3 to 7 Mohs, preferably in the range of 3.5 to 6.5 Mohs.
  • Shot blasting material with the aforementioned Vickers hardness or Mohs hardness is particularly efficient in increasing or adjusting the surface roughness of iron-based components without causing damage to the component (i.e. a surface change that cannot be compensated for or leveled out by subsequent galvanizing ).
  • the steel pressure used in process step (a) can equally vary within wide ranges: It is preferred according to the invention if the blasting material is blasted with a blasting pressure in the range from 1 to 15 bar, in particular in the range from 2 to 11 bar, preferably in the range from 3 to 8 bar, particularly preferably in the range from 3 to 5 bar, to the at least a surface of the iron-based component is left to act.
  • the blasting material is usually allowed to act on the at least one surface of the iron-based component with a blasting pressure of at least 1 bar, in particular at least 2 bar, preferably at least 3 bar.
  • the blasting material is advantageously allowed to act on the at least one surface of the iron-based component with a blasting pressure of at most 15 bar, in particular at most 11 bar, preferably at most 8 bar, particularly preferably at most 5 bar.
  • the blasting duration in process step (a) can also vary within wide ranges: It is generally advantageous if the blasting material is allowed to act on the at least one surface of the iron-based component for a period of 10 seconds to 30 minutes, in particular 15 seconds to 20 minutes, preferably 20 seconds to 10 minutes.
  • blasting material is allowed to act on the at least one surface of the iron-based component for a period of up to 30 minutes, in particular up to 20 minutes, preferably up to 10 minutes.
  • the blasting material is allowed to act on the at least one surface of the iron-based component for a period of at least 10 seconds, in particular at least 15 seconds, preferably at least 20 seconds.
  • process step (a) in particular by increasing the surface roughness in a targeted manner, the layer thickness of the galvanized layer resulting from process step (b) can be controlled or monitored or tailored in a targeted manner.
  • process step (a) enable the surface roughness to be set and/or increased particularly efficiently (without damaging the surface in the process) and in particular enable individual adaptation to the corresponding application requirements.
  • the present invention provides for the surface roughness to be increased and/or adjusted in step (a) in such a way that the surface treated in step (a) has an average roughness value Ra, in particular according to DIN EN ISO 4288:1998-04 , of at least 0.3 ⁇ m, in particular at least 0.6 ⁇ m, preferably at least 0.7 ⁇ m, particularly preferably at least 0.8 ⁇ m.
  • Ra average roughness value
  • the surface roughness is increased and/or adjusted in process step (a) in such a way that the surface treated in process step (a) has an average roughness value Ra, in particular according to DIN EN ISO 4288:1998-04, in the range of 0, 3 to 15 ⁇ m, preferably in the range from 0.7 to 13 ⁇ m, particularly preferably in the range from 0.8 to 12 ⁇ m.
  • Ra average roughness value
  • the mean roughness value Ra describes the roughness of a technical surface and is the arithmetic mean of the amounts of the ordinate values of the roughness profile within a single measurement section. It represents the mean deviation of the profile from the middle line. To determine this measured value, the surface is scanned over a defined measuring section and all height and depth differences of the rough surfaces are recorded. The integral is formed from this roughness curve and divided by the length of the measuring section (cf. DIN EN ISO 4288:1998-04 cited above).
  • the increase and / or adjustment of the surface roughness in process step (a) is carried out in such a way that the surface treated in process step (a) has an average peak-to-valley height Rz, in particular according to DIN EN ISO 4288:1998-04, of at least 2 ⁇ m, in particular at least 3 ⁇ m, preferably at least 4 ⁇ m.
  • the increase and/or adjustment of the surface roughness in process step (a) is carried out in such a way that the surface treated in process step (a) has an average peak-to-valley height Rz, in particular according to DIN EN ISO 4288:1998-04 , in the range from 2 to 75 ⁇ m, in particular in the range from 3 to 70 ⁇ m, preferably in the range from 3 to 65 ⁇ m.
  • Rz average peak-to-valley height
  • the mean peak-to-valley height Rz describes the sum of the height of the largest profile peak and the depth of the largest profile valley within a single measurement section. Usually, Rz results from the averaging of the results from five individual measurement sections. The average peak-to-valley height Rz reacts more sensitively to changes in surface structures than the average peak-to-valley height Ra (cf. DIN EN ISO 4288:1998-04 cited above).
  • the increase and/or adjustment of the surface roughness in process step (a) is carried out in such a way that the surface treated in process step (a) has a maximum peak-to-valley height Rmax, in particular according to DIN EN ISO 4288:1998-04, of at least 3 ⁇ m, in particular at least 4 ⁇ m, preferably at least 5 ⁇ m.
  • step (a) it is preferred if the increase and / or adjustment of the surface roughness in step (a) is carried out in such a way that the surface treated in step (a) has a maximum peak-to-valley height Rmax, in particular according to DIN EN ISO 4288:1998-04, in the range from 3 to 95 ⁇ m, in particular in the range from 4 to 90 ⁇ m, preferably in the range from 5 to 85 ⁇ m.
  • Rmax in particular according to DIN EN ISO 4288:1998-04, in the range from 3 to 95 ⁇ m, in particular in the range from 4 to 90 ⁇ m, preferably in the range from 5 to 85 ⁇ m.
  • the maximum peak-to-valley height Rmax describes the largest of the five individual peak-to-valley heights within a measuring section (cf. previously cited DIN EN ISO 4288:1998-04).
  • the surface roughness is increased in step (a) in such a way that the mean roughness value Ra, in particular according to DIN EN ISO 4288:1998-04, of the surface treated in step (a) is at least 10%, in particular is increased by at least 25%, preferably by at least 50%, more preferably by at least 75%, even more preferably by at least 100% (i.e. based on the mean roughness value Ra before the surface treatment).
  • the surface roughness can be increased in step (a) in such a way that the mean roughness value Ra, in particular according to DIN EN ISO 4288:1998-04, of the surface treated in step (a) is by 10% up to 300%, in particular by 25% up to 200% (i.e.
  • the percentage increase in surface roughness characterized by the increase in the mean roughness value Ra, is described by the percentage ratio of the mean roughness value Ra after carrying out method step (a) to the mean roughness value Ra before carrying out method step (a).
  • the surface roughness is increased in process step (a) in such a way that the mean peak-to-valley height Rz, in particular according to DIN EN ISO 4288:1998-04, of the surface treated in process step (a) is at least 10% , in particular by at least 25%, preferably by at least 50%, particularly preferably by at least 75%, even more preferably by at least 100% (ie based on the average peak-to-valley height Rz before the surface treatment).
  • the surface roughness can be increased in method step (a) in such a way that the average peak-to-valley height Rz, in particular according to DIN EN ISO 4288:1998-04, in method step (a) treated surface is increased by 10% to 300%, in particular by 25% to 200% (ie based on the average peak-to-valley height Rz before the surface treatment).
  • the percentage increase in surface roughness characterized by the increase in the mean peak-to-valley height Rz, is described by the percentage ratio of the mean peak-to-valley height Rz after carrying out method step (a) to the mean peak-to-valley height Rz before carrying out method step (a).
  • the surface roughness is increased in step (a) in such a way that the maximum peak-to-valley height Rmax, in particular according to DIN EN ISO 4288:1998-04, of the surface treated in step (a) is at least 10 %, in particular by at least 25%, preferably by at least 50%, particularly preferably by at least 75%, even more preferably by at least 100% (i.e. based on the maximum peak-to-valley height Rmax before the surface treatment).
  • the surface roughness can be increased in step (a) in such a way that the maximum peak-to-valley height Rmax, in particular according to DIN EN ISO 4288:1998-04, of the surface treated in step (a) is by 10% up to 300%, in particular by 25% up to 200% (i.e. related to the maximum peak-to-valley height Rmax before surface treatment).
  • the percentage increase in surface roughness characterized by the increase in the maximum roughness depth Rmax, is described by the percentage ratio of the maximum roughness depth Rmax after carrying out method step (a) to the maximum roughness depth Rmax before carrying out method step (a).
  • method step (a) in method step (b) is followed by hot-dip galvanizing of the iron-based component in an aluminum-alloyed or aluminum-containing zinc melt ("Zn/Al melt").
  • the iron-based component is provided or coated or covered with an aluminum-alloyed and/or aluminum-containing zinc layer.
  • an iron-based component provided or coated or covered with an aluminum-alloyed and/or aluminum-containing zinc layer is obtained.
  • the aluminum-alloyed or aluminum-containing zinc layer as obtained in the process according to the invention, in particular after process step (b) of the process according to the invention, preferably has a layer thickness in the range from 3 to 30 ⁇ m, in particular in the range from 4 to 28 ⁇ m in the range from 5 to 27 ⁇ m, particularly preferably in the range from 6 to 25 ⁇ m.
  • the aluminum-alloyed or aluminum-containing zinc layer which can be obtained by the method according to the invention or results from the method according to the invention preferably has a layer thickness which is 110 to 300%, in particular 125 to 280%, preferably 130 to 250% of that layer thickness , which is obtained after carrying out step (b) while omitting the preceding step (a).
  • the aluminum-alloyed or aluminum-containing zinc layer which results or is obtainable by the process according to the invention, has 110 to 300%, in particular 125 to 280%, preferably 130 to 250%, of that layer thickness which can only be achieved by identical hot-dip galvanizing without preliminary surface roughening is obtained.
  • the method according to the invention thus produces a zinc layer which has an increased layer thickness compared to the conventional hot-dip galvanizing layers made from Zn/Al melts.
  • the aluminum-alloyed or aluminum-containing zinc layer which is obtained by the method according to the invention described above, has a layer thickness which is around 0.5 to 15 ⁇ m, in particular around 1 to 12 ⁇ m, preferably around 2 to 10 ⁇ m, is greater than that layer thickness which is obtained after carrying out process step (b) while omitting the preceding process step (a).
  • the zinc layer thickness produced according to the invention is correspondingly thicker than a zinc layer which is only obtained by hot-dip galvanizing without prior surface roughening.
  • the hot-dip galvanized iron-based component obtained by method steps (a) and (b) has an at least essentially homogeneous or uniform or continuous aluminum-alloyed or aluminum-containing zinc layer, in particular on its upper or outer side.
  • the outer surface is therefore uniform, ie the roughening, which is introduced in process step (a), in process step (b) filled or leveled or leveled, so that the surface of the hot-dip galvanized iron-based component does not have any grooves or roughening, but is continuous or planar or even (cf. also Figure 1C and figures 3A and 3B).
  • the surface with increased or adjusted surface roughness resulting in process step (a) is at least essentially flattened or leveled in process step (b), in particular by the aluminum-alloyed or aluminum-containing zinc layer applied in process step (b).
  • This has the advantage that roughening the surface does not affect the surface structure of the finished hot-dip galvanized component (i.e. the end product).
  • the surface roughness is increased and/or adjusted in method step (a) only in certain areas, in particular only on one surface or not on all surfaces of the iron-based component, so that the in method step (b ) aluminum-alloyed or aluminum-containing zinc layer obtained has different thickness ranges;
  • the layer thickness of the aluminum-alloyed or aluminum-containing zinc layer in the area of the surface(s) or surface areas previously treated in process step (a) is increased compared to the layer thickness in the area of the untreated surface(s) or surface areas.
  • This embodiment is particularly preferred when, during the application or use of a component, certain areas of the component are exposed to greater stress than other areas of the component and these are further reinforced by the method according to the invention, while the remaining surfaces of the component are not subjected to any further stress need reinforcement and a conventionally produced hot-dip galvanizing layer provides sufficient protection.
  • An example application is chassis components whose surface facing the roadway is exposed to increased stress due to a combination of increased stone chipping, corrosion stress from de-icing salts and thermal stress as a result of the exhaust gas duct running above.
  • a corresponding increase and/or adjustment of the zinc layer thickness in the load area provided in certain areas or locally is sufficient, while the other or remaining surfaces of the chassis components do not require an increased and/or individually adjusted zinc layer thickness, since they are not exposed to increased loads.
  • An increase and/or adjustment of the zinc layer thickness as a measure against increased stress or stress can also be used in applications in which there is increased mechanical stress, e.g. B. in the form of abrasion.
  • the hot-dip galvanizing of the iron-based component is carried out in an aluminum-alloyed and/or aluminum-containing zinc melt ("Zn/Al melt").
  • the aluminum-alloyed or aluminum-containing zinc melt used in process step (b) preferably contains at least 0.1% by weight, in particular at least 0.15% by weight, preferably at least 0.2% by weight, based on the zinc melt at least 0.5% by weight, more preferably at least 1% by weight, very preferably at least 2% by weight, aluminum.
  • the aluminum-alloyed or aluminum-containing zinc melt used in process step (b), based on the zinc melt contains at most 25% by weight, in particular at most 20% by weight, preferably at most 17.5% by weight, preferably at most 15% by weight, particularly preferably at most 12.5% by weight, very particularly preferably at most 10% by weight, of aluminum.
  • the aluminum-alloyed or aluminum-containing zinc melt used in process step (b), based on the zinc melt contains aluminum in amounts in the range from 0.1% by weight to 25% by weight, in particular in the range from 0.15% by weight. % to 20% by weight, preferably in the range from 0.2% by weight to 17.5% by weight, preferably in the range from 0.5% by weight to 15% by weight, particularly preferably in the range from 1% to 12.5% by weight, most preferably in the range from 2% to 10% by weight.
  • the aluminum-alloyed or aluminum-containing zinc melt used in process step (b) has a temperature in the range from 375 to 750 ° C, in particular in the range from 380 to 700 ° C, preferably in the range of 390 to 680°C, more preferably in the range of 395 to 675°C.
  • hot-dip galvanizing is particularly economical.
  • the iron-based component is immersed in the aluminum-alloyed or aluminum-containing zinc melt, in particular immersed and moved therein, in particular for a period of time which is sufficient to ensure effective hot-dip galvanizing (hot-dip galvanizing).
  • hot-dip galvanizing hot-dip galvanizing
  • the iron-based component is immersed in the aluminum-alloyed or aluminum-containing zinc melt, in particular immersed and moved therein, in particular for a period of time which is sufficient to ensure effective hot-dip galvanizing (hot-dip galvanizing).
  • hot-dip galvanizing hot-dip galvanizing
  • the aluminum-alloyed or aluminum-containing zinc melt used in process step (b) is contacted or purged or passed through with at least one inert gas, in particular nitrogen. This avoids an undesired reaction of the uncoated surface with the oxygen that is present; thus no defects are obtained in the formed zinc layer.
  • a pretreatment of the iron-based component obtained in process step (a) is carried out before the hot-dip galvanizing in process step (b). This pre-treatment enables a particularly even and error-free galvanizing result.
  • Pre-treatment steps (3) and (4) are mutually dependent, so that if pre-treatment step (3) is omitted, pre-treatment step (4) is also omitted.
  • the component is also mechanically cleaned, which means that the usual pickling in an acidic medium, in particular as described in pretreatment step (3), is completely omitted or the required treatment time is at least significantly reduced can be shortened.
  • the omission of pre-treatment step (3) or the shortening of its duration has the advantage that the risk of hydrogen entering the galvanizing product from the acidic pickling solution can be completely ruled out or at least significantly reduced, and the risk of the component becoming brittle as a result of hydrogen entering can thus be ruled out or can be significantly reduced.
  • a pretreatment of the iron-based component obtained in method step (a) is carried out (in particular of the type described above).
  • the pretreatment comprises at least one flux treatment (fluxing).
  • the flux treatment means that the surface is cleaned intensively, the wettability between the component surface and the molten zinc is increased and oxidation of the component surface is prevented during a possible waiting time and drying before the galvanizing process.
  • the iron-based component obtained in method step (a) is pretreated with a flux.
  • the flux is located or dissolved in a flux bath.
  • the flux contains the following components (ingredients): (I) zinc chloride (ZnCl 2 ), (II) ammonium chloride (NH 4 Cl), (III) optionally at least one alkali metal and/or alkaline earth metal salt and ( IV) optionally at least one other metal salt, preferably selected from salts, preferably chlorides, of nickel (Ni), cobalt (Co), manganese (Mn), lead (Pb), tin (Sn), bismuth (Bi), antimony (Sb ), Aluminum (AI) and silver (Ag) and combinations thereof, preferably selected from NiCl 2 , CoCl 2 , MnCl 2 , PbCl 2 , SnCl 2 , BiCl 3 , SbCl 3 , AlCl 3 and AgCl and combinations thereof.
  • redients preferably zinc chloride (ZnCl 2 ), (II) ammonium chloride (NH 4 Cl), (III) optionally at least one alkali metal and/
  • the flux contains the following components (ingredients): (I) zinc chloride (ZnCl 2 ), (II) ammonium chloride (NH 4 Cl), (III) at least one alkali metal and/or alkaline earth metal salt, preferably Sodium chloride and/or potassium chloride, preferably sodium chloride and potassium chloride, and (IV) at least one other metal salt, preferably selected from salts, preferably chlorides, of nickel (Ni), cobalt (Co), manganese (Mn), lead (Pb), tin (Sn), bismuth (Bi), antimony (Sb), aluminum (AI) and silver (Ag) and combinations thereof, preferably selected from NiCl 2 , CoCl 2 , MnCl 2 , PbCl 2 , SnCl 2 , BiCl 3 , SbCl 3 , AlCl 3 and AgCl and combinations thereof, particularly preferably selected from NiCl 2 , CoC
  • the flux contains the following components (ingredients), all of the quantities specified below being based on the flux and to be selected in such a way that a total of 100% by weight results: (I) 60 to 80% by weight % of zinc chloride (ZnCl 2 ), (II) 7 to 20% by weight of ammonium chloride (NH 4 Cl), (III) 2 to 20% by weight of at least one alkali metal and/or alkaline earth metal salt, preferably sodium chloride and/or Potassium chloride, preferably sodium chloride and potassium chloride, (IV') 0.1 to 5% by weight of at least one metal salt from the group consisting of NiCl 2 , CoCl 2 and MnCl 2 and (IV") 0.1 to 1.5% by weight % of at least one other metal salt from the group consisting of PbCl 2 , SnCl 2 , BiCl 3 and SbCl 3 .
  • the flux bath used in the method according to the invention is water-based or water-alcohol-based.
  • the flux bath is usually adjusted to a defined or predetermined, in particular acidic pH value, in particular in the pH range from 0 to 6.9, preferably in the pH range from 0.5 to 6, 5, preferably in the pH range from 1 to 5.5, particularly preferably in the pH range from 1.5 to 5, very particularly preferably in the pH range from 2 to 4.5, even more preferably in the pH range from 2 to 4.
  • a defined or predetermined, in particular acidic pH value in particular in the pH range from 0 to 6.9, preferably in the pH range from 0.5 to 6, 5, preferably in the pH range from 1 to 5.5, particularly preferably in the pH range from 1.5 to 5, very particularly preferably in the pH range from 2 to 4.5, even more preferably in the pH range from 2 to 4.
  • the flux bath is adjusted to a defined or predetermined, in particular acidic, pH value, with the adjustment of the pH value using a preferably inorganic acid in combination with a preferably inorganic basic compound, in particular ammonia (NH 3 ), he follows.
  • a preferably inorganic acid in combination with a preferably inorganic basic compound, in particular ammonia (NH 3 )
  • NH 3 ammonia
  • the flux bath - in addition to the ingredients or components mentioned above - can also contain at least one wetting agent and / or surfactant, in particular at least one ionic or nonionic wetting agent and / or surfactant, preferably at least one nonionic wetting agent and / or surfactant included.
  • the flux bath can contain the at least one wetting agent and/or surfactant in amounts of 0.0001 to 15% by weight, preferably in amounts of 0.001 to 10% by weight, preferably in amounts of 0.01 to 8% by weight. , even more preferably in amounts of 0.01 to 6% by weight, very particularly preferably in amounts of 0.05 to 3% by weight, even more preferably in amounts of 0.1 to 2% by weight on the flux bath.
  • the flux bath can contain the at least one wetting agent and/or surfactant in amounts of 0.0001 to 10% by volume, preferably in amounts of 0.001 to 8% by volume, preferably in amounts of 0.01 to 5% by volume , even more preferably in amounts of 0.01 to 5% by volume, based on the flux bath.
  • the amount or concentration of the flux composition used according to the invention in the flux bath used according to the invention can equally vary within wide ranges:
  • the flux bath can contain the flux composition in an amount of 150 g/l to 750 g/l, in particular in amounts of 200 g/l to 700 g/l, preferably in an amount of 250 g/l to 650 g/l in an amount from 300 g/l to 625 g/l, particularly preferably in an amount from 400 g/l to 600 g/l, very particularly preferably in an amount from 450 g/l to 580 g/l, even more preferred in an amount of 500 g/l to 575 g/l, calculated in particular as the total salt content of the flux composition.
  • the flux treatment takes place at a temperature between 20 and 90°C, in particular between 30 and 85°C, preferably between 40 and 80°C, particularly preferably between 50 and 75°C.
  • the procedure is generally such that the flux treatment takes place by bringing the iron-based component into contact with the flux bath or the flux composition, in particular by immersion or spray application, preferably immersion.
  • the iron-based component can be treated with the flux bath or The flux composition are brought into contact, in particular immersed in the flux bath.
  • the hot-dip galvanizing carried out in process step (b) can be followed by a cooling step or the iron-based component hot-dip galvanized in process step (b) can be subjected to a cooling treatment, optionally followed by further post-processing and/or post-treatment.
  • the optional cooling step or cooling treatment can be carried out in particular by means of air and/or in the presence of air, preferably down to ambient temperature.
  • the further post-processing and/or post-treatment to be optionally carried out can in particular include passivation and/or sealing.
  • Such post-processing or post-treatment can be used to produce a further protective layer on the component, which further strengthens the protection against corrosion.
  • the process according to the invention can be operated continuously or batchwise.
  • the iron-based component to be treated can be a single product or a large number of individual, in particular identical, products. Equally, the iron-based component can be a long product, in particular a wire, pipe, sheet metal, coil material or the like.
  • the iron-based component can be a steel component for automobile production, in particular for car, truck or commercial vehicle production, or a steel component for the technical sector, in particular for the construction industry, mechanical engineering industry or electrical industry.
  • the devices (A) and (B) can be spatially separated from one another.
  • the device (A) for increasing and/or adjusting the surface roughness comprises an abrasion device, in particular a device for compressed air blasting with solid blasting material (blasting agent), or is designed as such.
  • the device (A) for increasing and/or adjusting the surface roughness in particular the abrasion device, preferably the device for compressed air blasting with solid blasting material, comprises at least one receptacle for a solid blasting material.
  • the blasting material used in device (A) and/or in the receptacle is selected from the group of metallic, mineral (inorganic) and organic blasting material and combinations thereof, preferably in particulate form, preferably from the group of metallic , natural-mineral, synthetic-mineral, natural-organic and synthetic-organic blasting material and combinations thereof, in particular particulate stainless steel blasting material and/or glass bead blasting material.
  • the blasting material used in device (A) and/or located in the receiving container usually has a round, spherical, angular or cylindrical grain shape, preferably an angular grain shape.
  • the grain size of the blasting material used in device (A) and/or in the receptacle can vary within wide ranges:
  • the blasting material used in device (A) and/or located in the receiving container can have an absolute grain size in the range from 30 to 5000 ⁇ m, in particular in the range from 50 to 3000 ⁇ m, preferably in the range from 60 to 1500 ⁇ m, particularly preferably in the range from 70 to 1000 ⁇ m, very particularly preferably in the range from 75 to 800 ⁇ m.
  • the absolute grain size is related to the largest dimension of the blasting material particle.
  • the grain hardness of the blasting material used in device (A) and/or located in the receptacle can also vary within wide ranges:
  • the blasting material used in device (A) and/or located in the receptacle has a hardness, in particular grain hardness, preferably Vickers hardness, in the range from 20 to 2,500 HV, in particular in the range from 100 to 2,100 HV, preferably in the range from 200 to 2,000 HV, preferably in the range from 250 to 1500 HV.
  • the blasting material used in device (A) and/or located in the receiving container can have a hardness, in particular grain hardness, preferably Mohs hardness, in the range from 2 to 9 Mohs, in particular in the range from 2.5 to 8 Mohs, preferably in the range from 3 to 7 Mohs, preferably in the range of 3.5 to 6.5 Mohs.
  • the abrasion device preferably the device for compressed air blasting with solid blasting material
  • this is designed in particular in such a way that the blasting material can be blasted with a blasting pressure in the range from 1 to 15 bar, in particular in the range from 2 to 11 bar, preferably in the range from 3 to 8 bar, particularly preferably in the range from 3 to 5 bar, and/or is allowed to act on the at least one surface of the iron-based component.
  • the device (A) for increasing and/or adjusting the surface roughness in particular the abrasion device, preferably the device for compressed air blasting with solid blasting material, is designed in such a way that the blasting material is blasted with a blasting pressure of at least 1 bar, in particular at least 2 bar, preferably at least 3 bar, discharged and/or allowed to act on the at least one surface of the iron-based component.
  • the device (A) for increasing and/or adjusting the surface roughness in particular the abrasion device, preferably the device for compressed air blasting with solid blasting material, is designed in such a way that the blasting material can be blasted with a maximum blasting pressure of 15 bar, in particular a maximum of 11 bar , preferably a maximum of 8 bar, particularly preferably a maximum of 5 bar, is discharged and/or is allowed to act on the at least one surface of the iron-based component.
  • the hot-dip galvanizing device (B) comprises a galvanizing bath containing an aluminum-alloyed and/or aluminum-containing molten zinc, in particular as defined above.
  • the hot-dip galvanizing device (B) is designed to provide and/or coat and/or coat the iron-based component with an aluminum-alloyed and/or aluminum-containing zinc melt.
  • the system is usually designed in such a way that downstream and/or arranged downstream of device (A) and upstream and/or arranged upstream of hot-dip galvanizing device (B), a pretreatment device (C) is provided for pretreating the iron-based component roughened in device (A) and /or is arranged.
  • the pretreatment device (C) is arranged between the device (A) and the hot-dip galvanizing device (B).
  • the pickling device (C3) together with the rinsing device (C4) can even be completely omitted. This is particularly possible when in device (A) the abrasion device has already removed all of the contamination, in particular that is specific to the species, so that pickling in a corresponding pickling device is no longer required.
  • the devices (C3) and (C4) are mutually dependent, so that the omission of the pickling device (C3) automatically results in the omission of the rinsing device (C4).
  • a cooling device is arranged downstream of the hot-dip galvanizing device (B) in the process direction.
  • the cooling device can be designed for cooling by means of air or in the presence of air, preferably down to ambient temperature.
  • a post-processing device and/or post-treatment device can be arranged in the process direction after or downstream of the hot-dip galvanizing device (B) and the optionally present cooling device.
  • the post-processing device and/or post-treatment device can include a passivation device and/or sealing device or be designed as such.
  • the plant can in principle be designed to be operated continuously or discontinuously and/or be operated continuously or discontinuously.
  • the system can be designed in such a way that the iron-based component can be hot-dip galvanized as a single product or as a large number of individual, in particular identical products, or that the iron-based component can be hot-dip galvanized as a long product, in particular a wire, pipe, sheet metal or coil material or the like, can be hot-dip galvanized.
  • hot-dip galvanized iron-based component preferably a steel component, which can be obtained using the method according to the invention as described above.
  • the special features of the process according to the invention are also directly reflected in the products of the process that can be obtained thereby or with it, i. H. the hot-dip galvanized iron-based components.
  • the hot-dip galvanized components obtainable according to the invention not only have improved mechanical properties and improved anti-corrosion properties as a result of the aluminium-containing or aluminium-alloyed galvanizing layers, but can also be provided with a tailor-made aluminium-alloyed or aluminium-containing zinc layer, in particular precisely adapted to the relevant requirements.
  • the components according to the invention are characterized by a special surface structure (cf. figs 1C and 3A and 3B):
  • a special surface structure cf. figs 1C and 3A and 3B:
  • the microscopic examinations prove also that in comparison to aluminium-containing or aluminium-alloyed galvanizing layers produced by means of hot-dip galvanizing without prior roughening, a significantly greater layer thickness of the upper aluminium-containing or aluminium-alloyed hot-dip galvanizing layer is obtained.
  • the increase in layer thickness leads in the same way to improved anti-corrosion properties and improved mechanical properties (e.g. improved abrasion resistance, improved wear protection properties, etc.), since the other properties of the aluminum-containing or aluminum-alloyed zinc coating are not impaired by the pretreatment according to the invention, in particular not their Adhesion in relation to the underlying material surface.
  • the products according to the invention therefore have a special layer structure, which can be documented and proven by microscopic examinations of sections of the products in question (cf. Figures 3A and 3B, discussed below, in comparison to the layers produced by conventional methods according to figs 1A and 1B ).
  • the roughening of the surface carried out before the hot-dip galvanizing treatment can also be seen or verified in the microscopic section of the end product.
  • a hot-dip galvanized iron-based component which has the aforementioned properties in combination can only be obtained using the method according to the invention.
  • conventional hot-dip galvanizing with pure zinc the zinc layer thickness increases with the residence time in the molten zinc;
  • aluminium-alloyed or aluminium-containing zinc melts since initially a barrier layer in the form of a thin (approx. 500 nm) Fe/Al alloy layer forms, which allows further growth of the overlying pure Zn/Al layer beyond a certain limit value addition (average 6 to 15 ⁇ m).
  • step (a) by increasing and/or adjusting the surface roughness according to the invention in step (a), it is surprisingly possible to increase and/or increase the zinc layer thickness of aluminum-alloyed zinc layers despite the barrier layer that forms (i.e. Fe/Al phase or Fe/Al barrier layer). or discontinue. Only by using the method according to the invention is it possible to obtain an aluminum-alloyed or aluminum-containing zinc layer which has the combination of the aforementioned properties; In particular, significantly higher layer thicknesses are achieved in comparison to conventionally produced aluminium-containing or aluminium-alloyed zinc layers (i.e.
  • the microscopic section showing that the originally roughened surface is at least essentially completely leveled by the aluminium-alloyed or aluminium-containing zinc layer or leveled, but remains recognizable and verifiable as such in the section.
  • the hot-dip galvanized iron-based component can be obtained by first subjecting the iron-based component to at least one surface of a treatment to increase and/or adjust the surface roughness by means of an abrasive process such that the surface has an average roughness value Ra according to DIN EN ISO 4288:1998-4 in the range from 0.3 to 15 ⁇ m and subsequently the iron-based component of hot-dip galvanizing surface-treated in this way in a aluminum-alloyed or aluminum-containing molten zinc (“Zn/Al melt”), the zinc melt containing at least 0.1% by weight of aluminum, based on the zinc melt, and the hot-dip galvanized iron-based component having an aluminum-alloyed and/or aluminum-containing component Zinc layer is provided and / or coated and / or covered, the aluminum alloyed and / or aluminum-containing zinc layer having a layer thickness in the range of 3 to 30 microns.
  • abrasive process such that the surface has an average roughness value Ra according to DIN EN ISO 4288:1998-4
  • the hot-dip galvanized iron-based component is provided and/or coated and/or coated with an aluminum-alloyed or aluminum-containing zinc layer.
  • an aluminum-alloyed or aluminum-containing zinc melt thinner zinc layers can be obtained than with classic hot-dip galvanizing (i.e. with pure zinc melts, e.g. according to ISO 1461), but these are significantly increased compared to zinc layers that are obtained without prior surface roughening.
  • the aluminum-alloyed or aluminum-containing zinc layer produced or obtainable according to the invention has a layer thickness in the range from 3 to 30 ⁇ m, in particular in the range from 4 to 28 ⁇ m, preferably in the range from 5 to 27 ⁇ m, particularly preferably in the range from 6 to 25 ⁇ m.
  • the aluminum-alloyed or aluminum-containing zinc layer which is obtained in particular by the method according to the invention described above, has a layer thickness which is 110 to 300%, in particular 125 to 280%, preferably 130 to 250%, of that layer thickness is which is obtained after carrying out method step (b) omitting the preceding method step (a).
  • the method according to the invention gives a hot-dip galvanizing layer which is thicker than a conventionally produced aluminum-alloyed or aluminum-containing hot-dip galvanizing layer without prior surface roughening.
  • Process step (a) and process step (b) such an increase or adjustment of the zinc layer thickness is possible at all.
  • the aluminum-alloyed or aluminum-containing zinc layer which is obtained by the method according to the invention described above, has a layer thickness which is around 0.5 to 15 ⁇ m, in particular around 1 to 12 ⁇ m, preferably around 2 to 10 ⁇ m, is greater than that layer thickness which is obtained after carrying out process step (b) while omitting the preceding process step (a).
  • the aluminium-alloyed or aluminium-containing zinc layer thickness obtained according to the invention is therefore higher or greater than conventionally produced aluminium-alloyed or aluminium-containing zinc layer thicknesses of hot-dip galvanizing without prior surface roughening.
  • the hot-dip galvanized iron-based component has an at least essentially homogeneous and/or uniform and/or continuous aluminum-alloyed and/or aluminum-containing zinc layer, in particular on its upper side or outside.
  • the outer surface of the hot-dip galvanized iron-based component according to the invention is therefore uniform or evened out or leveled in comparison to the roughened surface of the component after process step (a) has been carried out, i. H. the roughened areas resulting from process step (a) are leveled or filled or levelled.
  • the surface with increased and/or adjusted surface roughness resulting from process step (a) is at least essentially leveled and/or leveled within the scope of process step (b), in particular by the surface applied in process step (b). aluminum-alloyed or aluminum-containing zinc layer.
  • the iron-based component is provided with an increased or adjusted surface roughness only in regions, in particular only on one surface and/or not on all surfaces of the iron-based component.
  • the increase and/or adjustment of the surface roughness can be application-specific be performed. Examples of this particular embodiment are explained above in connection with the method according to the invention.
  • the invention provides for the aluminum-alloyed or aluminum-containing zinc layer to have different thickness ranges .
  • the layer thickness of the aluminum-alloyed or aluminum-containing zinc layer in the area of the previously treated surface(s) or surface areas is increased compared to the layer thickness in the area of the untreated surface(s) or surface areas.
  • Another subject of the present invention - according to a third aspect of the present invention - is the use of a hot-dip galvanized (hot-dip galvanized) iron-based component, preferably a steel component, as described above, according to the present invention, as described in the relevant use claims.
  • a hot-dip galvanized (hot-dip galvanized) iron-based component preferably a steel component, as described above, according to the present invention, as described in the relevant use claims.
  • the hot-dip galvanized iron-based components according to the invention can be used in a variety of ways, since the thickness of the aluminum-alloyed or aluminum-containing zinc layer can be increased and/or adjusted specifically for the application, and customized corrosion protection solutions and/or wear protection solutions can therefore be provided.
  • the subject matter of the present invention is in particular the use of a hot-dip galvanized (hot-dip galvanized) iron-based component, preferably a steel component, according to the present invention for automobile production, in particular for passenger car, truck or commercial vehicle production, or for the technical area especially for the construction industry, mechanical engineering industry or electrical industry.
  • a hot-dip galvanized (hot-dip galvanized) iron-based component preferably a steel component
  • the present invention for automobile production, in particular for passenger car, truck or commercial vehicle production, or for the technical area especially for the construction industry, mechanical engineering industry or electrical industry.
  • the hot-dip galvanized (hot-dip galvanized) iron-based components according to the invention can be used as components, materials or parts for automobile production, in particular car, truck or commercial vehicle production, or as components, materials or parts for the technical field , used in particular for the construction industry, mechanical engineering industry or electrical industry.
  • the present invention relates, according to a particular embodiment, in particular to the use of a hot-dip galvanized (hot-dip galvanized) iron-based component, preferably a steel component, according to the present invention as a component, material or part for automobile production, in particular car, truck or Commercial vehicle production, or as a component, material or part for the technical area, in particular for the construction industry, mechanical engineering industry or electrical industry.
  • a hot-dip galvanized (hot-dip galvanized) iron-based component preferably a steel component
  • the present invention as a component, material or part for automobile production, in particular car, truck or Commercial vehicle production, or as a component, material or part for the technical area, in particular for the construction industry, mechanical engineering industry or electrical industry.
  • Another subject of the present invention - according to a fourth aspect of the present invention - is the use of increasing and / or adjusting the surface roughness of at least one surface of an iron-based component by mechanical treatment using an abrasive process for adjusting and increasing the zinc layer thickness in a hot-dip galvanizing process using an aluminum-alloyed and/or aluminum-containing zinc melt with at least 0.1% by weight aluminum, based on the zinc melt.
  • FIG 1A is a schematic of the layer structure of a hot-dip galvanized iron-based component by classic hot-dip galvanizing in a pure zinc melt (ie without aluminum content), e.g. B. according to DIN EN ISO 1461, shown (prior art).
  • a coating of Fe/Zn alloy layers 2 of various compositions forms on the iron-based component 1 in the form of an Fe/Zn alloy phase.
  • the growth of the Fe/Zn alloy phase 2 is a time-dependent process, so the alloy phase 2 grows with residence time.
  • the alloy phase 2 partly grows into the iron-based component 1, whereby the original surface 1a of the iron-based component "shifts" and the actual or original component thickness is reduced, partly the zinc layer grows on the iron-based material.
  • a layer 3 of zinc also referred to as the pure zinc phase 3 also remains on the alloy phase 2, the composition of which corresponds to the molten zinc.
  • a relatively brittle layer 2 in the form of an Fe/Zn alloy phase first forms on the steel surface and only then does the pure zinc phase 3 form. In this way, a relatively thick overall galvanizing layer 4 is formed.
  • Figure 1B shows the schematic layer structure of an iron-based component hot-dip galvanized in an aluminum-alloyed or aluminum-containing zinc melt (prior art).
  • a very thin Fe/Al alloy phase 2' a so-called blocking layer or barrier layer (approx. 500 nm), first forms on the iron-based component 1'. Due to this Fe/Al alloy phase 2', the otherwise usual diffusion processes between iron and molten zinc are inhibited, as a result of which the original surface 1a' of the iron-based component' does not shift. The Fe/Al alloy phase 2' does not grow into the iron-based component 1' and there is no Fe/Zn alloy phase.
  • a pure aluminum-alloyed or aluminum-containing zinc layer 3' also remains on the Fe/Al alloy phase 2', the composition of which corresponds to the aluminum-containing or aluminum-alloyed zinc melt.
  • the formation of the barrier layer 2' also limits the thickness of the entire galvanizing layer 4', and a significantly thinner overall layer 4' is formed overall than in the case of hot-dip galvanizing in pure zinc melts, e.g. B. according to DIN EN ISO 1461 (ie the total layer thickness 4' in Figure 1B is less than the total layer thickness 4 from Figure 1A ).
  • FIG 1C shows the schematic layer structure of an iron-based component hot-dip galvanized according to the invention with increased or adjusted surface roughness (invention).
  • the surface roughness of the iron-based component 1" is first mechanically increased or adjusted.
  • a very thin Fe/Al alloy phase 2 a so-called blocking layer or barrier layer, then initially forms on the roughened iron-based component 1".
  • Fe/Al alloy phase 2 the otherwise usual diffusion processes between iron and molten zinc are inhibited, as a result of which the original surface 1a" of the iron-based component does not shift.
  • the Fe/Al alloy phase 2" does not grow into the iron-based component 1" and it is formed no Fe/Zn alloy phase.
  • a pure aluminum-alloyed or aluminum-containing zinc layer 3" also remains on the Fe/Al alloy phase 2", which corresponds in its composition to the aluminum-containing or aluminum-alloyed zinc melt and which
  • the surface of the hot-dip galvanized nkten iron-based component with increased surface roughness is therefore even or flat.
  • the formation of the barrier layer limits the thickness of the overall galvanizing layer 4", however, due to the previous roughening of the surface, it is higher than in hot-dip galvanized iron-based components without increased surface roughness (as in Figure 1B shown), so that a significantly thinner overall layer than with hot-dip galvanizing in pure zinc melts, e.g. B.
  • FIG. 2 shows graphically the correlation between the surface roughness of the component and the zinc layer thickness resulting from hot-dip galvanizing in an aluminum-alloyed or aluminum-containing zinc melt of a component with previously increased surface roughness.
  • An increased surface roughness characterized by the average peak-to-valley height Rz, results in a higher zinc layer thickness.
  • the surface roughness is linearly proportional to the zinc layer thickness resulting from hot-dip galvanizing according to the invention.
  • figs 3A /B show microscopic sections (cross sections) of the components obtainable according to the invention.
  • the special surface structure is evident:
  • the roughened surface of the iron-based component (base material) obtainable according to process step (a) is completely leveled or evened out in the finished end product by the applied aluminum-containing or aluminum-alloyed zinc coating.
  • the microscopic investigations also show that a significantly higher layer thickness of the upper aluminum-containing or aluminum-alloy hot-dip galvanizing layer is obtained in comparison to hot-dip galvanizing layers produced by hot-dip galvanizing without prior roughening. This can be seen from the measured layer thicknesses, which are shown in figs 3A /B are documented.
  • the iron-based components were all previously compressed air blasted with an angular particulate stainless steel blasting agent (stainless steel blasting material).
  • the iron-based component in Figure 3A was blasted with a low beam intensity
  • the iron-based component in Figure 3B was irradiated with a high beam intensity.
  • the component blasted with a low beam intensity (shown in Figure 3A ) has an average hot-dip galvanizing layer thickness of 12.44 ⁇ m in the measured section
  • the component blasted with a high blasting intensity shown in Figure 3B ) has an average hot-dip galvanizing layer thickness of 32.92 ⁇ m in the measured section.
  • the layer thicknesses are essentially significantly higher, especially after blasting with medium and high intensity.
  • the previously effected surface roughening also remains verifiable or recognizable in the microscopic section.
  • the bottom curve represents - as a function of the galvanizing time (ie immersion time in the galvanizing bath) - the course of the growth of the zinc layer of hot-dip galvanizing layers by hot-dip galvanizing in aluminum-alloyed or aluminum-containing zinc melts; the zinc layer thickness reaches its maximum thickness after a very short time (approx. 1 minute) and the zinc layer does not increase further as the immersion time continues.
  • the middle curve characterized by diamonds, represents - as a function of the galvanizing time (ie immersion time in the galvanizing bath) - the course of the growth of the zinc layer of hot-dip galvanizing layers according to the invention by prior surface roughening and subsequent hot-dip galvanizing in aluminum-alloyed or aluminum-containing zinc layers; the zinc layer thickness only reaches its maximum thickness after approx. 2 minutes, and the zinc layer does not increase any further as the immersion time continues.
  • the hot-dip galvanizing layer produced according to the invention has an increased layer thickness compared to conventional hot-dip galvanizing layers produced in an aluminum-alloyed or aluminum-containing zinc melt without prior surface roughening (i.e. without prior increase in surface roughness), but nevertheless has a significantly thinner zinc layer than those zinc layers which are produced by hot-dip galvanizing in a pure molten zinc can be produced.
  • Zinc alloy used Zn5%AI (microZINQ ® )
  • the microscopic analysis of the zinc layers produced reveals that the molten zinc largely evens out the defined surface roughness so that a continuous and even surface is present after hot-dip galvanizing (cf. Figures 3A and 3B ). Due to the roughness of the substrate, a zinc layer forms, which locally has areas with somewhat greater or lesser layer thicknesses, but the average layer thickness overall is higher than on untreated (ie not roughened) surfaces and the outer surface is flat overall.
  • the average zinc layer thickness should be used, because based on the cathodic effect of the zinc layer, the slightly thinner areas have an overall protective effect due to the areas with a thicker layer.
  • the surface roughness of the goods to be galvanized can be set in a defined manner and thus a zinc layer with an increased zinc layer thickness can be applied.
  • reference substrates namely sheet metal or components, are passed through the hot-dip galvanizing process without prior mechanical surface treatment.
  • the recording of the characteristic roughness parameters Ra, Rz and Rmax to describe the surface roughness achieved is carried out in accordance with DIN EN ISO 4288.
  • the surface roughness is measured at 3 different measuring points on the substrates; the determined individual measured values, their mean ("x") and the respective standard deviations ("SD") are shown in the following table: sheet Low beam intensity Medium beam intensity High beam intensity measuring point Ra [ ⁇ m ] Rz [ ⁇ m ] Rmax [ ⁇ m ] Ra [ ⁇ m ] Rz [ ⁇ m ] Rmax [ ⁇ m] Ra [ ⁇ m ] Rz [ ⁇ m ] Rmax [ ⁇ m] 1 2.3 15.9 17.3 6.6 38.0 46.5 9.4 58.0 72.3 2 2.6 16.9 18.5 5.9 38.4 44.2 10.0 65.2 80.3 3 2.2 14.8 17.5 5.7 36.8 39.2 11.4 633 88.4 x 2.4 15.9 17.8 6.1 37.7 43.3 103 62.2 80.3 SD 0.2 1.0 0.6 0.5 0.8 3.7
  • all substrates ie both the blasted and the reference or comparison
  • the layer thickness according to DIN EN ISO 2178 is then measured on each substrate. For this purpose, measurements are taken at 6 measuring points on the sheets and at 8 measuring points on the components. A total of 5 series of measurements are recorded.
  • the choice of beam intensity determines the surface roughness of the substrates, which directly affects the resulting zinc layer thickness. With increasing surface roughness, the zinc layer thickness also increases.
  • the neutral salt spray test does not represent a realistic corrosion exposure and therefore no determination of the absolute protection period of zinc coatings can be derived; however, this test can be used for a meaningful relative comparison of coatings and coatings.
  • the coated substrate is placed in a test chamber and continuously sprayed with a 5% sodium chloride solution. The time it takes for corrosion to appear on the substrate is recorded and used as an evaluation criterion.
  • Empirical values show that substrates without surface treatment with a 6 ⁇ m thick Zn5Al layer have a service life of more than 720 hours in the neutral salt spray test before the base material corrosion (red rust) occurs.
  • the climate change test according to the VDA standard summarizes various load scenarios so that it represents a test under realistic conditions.
  • the test is made up of different load intervals, which result in a weekly overall cycle, which is then run through again until signs of corrosion appear on the test specimen.
  • Empirical values show that substrates without surface treatment with a 13 ⁇ m thick Zn5Al layer and subsequent sealing can achieve 4 to 5 cycles without the occurrence of base material corrosion. Experiments have shown that the number of cycles without the occurrence of base material corrosion increases to more than 6 cycles in the case of the substrates coated according to the invention.
  • Zinc layers produced in the hot-dip galvanizing process are characterized by a high resistance to mechanical influences due to the metallurgical bond between the zinc layer and the ferrous substrate. As is known, however, the greater the thickness, the greater the risk that the zinc layer will flake off under load and/or show cracks.
  • Various methods are used to test the mechanical resistance of the zinc coatings produced by the process according to the invention.
  • a technological bending test (folding test) according to DIN 50111 is carried out on sample sheets.
  • the sheets are mechanically pre-treated with different blasting parameters and then galvanized, resulting in different zinc layer thicknesses according to the following overview.
  • beam parameters Rz [ ⁇ m] Zinc layer thickness [ ⁇ m] without rays 6.7 7.2 low beam intensity 21.3 15.2 medium beam intensity 47.5 26.3 high beam intensity 71.2 32.6
  • the sheets are then checked and formed.
  • the tear-off stresses are within the usual scatter for this test at a uniformly high level.
  • the mechanical resistance is also measured in accordance with EN 438-2.
  • the abrasion value is 0.01 ⁇ m / cycle. Experiments have shown that the mechanical resistance of the substrates coated according to the invention also improves.
  • a stone impact test is carried out according to DIN EN ISO 20567-1, in which a sample provided with a coating or metallic coating is loaded with many small, sharp-edged impact bodies accelerated by compressed air. The degree of damage to the coating (penetration of the layer down to the base material) is evaluated. Zn/Al coatings behave very positively in this test because, on the one hand, the metallurgical bond between the zinc layer and steel ensures a very high level of adhesion and, on the other hand, the energy of the impacting grains is absorbed very well thanks to the high ductility of the zinc layer. In the case of conventional pure zinc layers with brittle phases according to the prior art, on the other hand (e.g. very pronounced in a high-temperature galvanizing layer), local spalling occurs under rockfall.
  • the components are blasted with an edged blasting material (stainless steel) using a two-turbine continuous blasting system with medium blasting intensity.
  • reference substrates (comparative components) are passed through the hot-dip galvanizing process without mechanical surface treatment.
  • the components and the references go through the hot-dip galvanizing process.
  • the layer thickness is then measured in accordance with DIN EN ISO 2178.
  • comparison components ie without surface pre-treatment only have an average layer thickness of 11.7 ⁇ m.
  • the mechanical resistance is measured in accordance with EN 438-2.
  • the number of wear cycles that can be endured is significantly increased in relation to the hot-dip galvanized reference components. This is equivalent to an increase in the resistance of the zinc layer to mechanical friction stress.
  • the adhesive strength measured in accordance with DIN EN 24624, is unchanged compared with components without surface treatment.
  • the load-bearing capacity as a result of shock or impact-like effects also remains unchanged as a result of the increase in the zinc layer thickness according to the invention.
  • a stone impact test according to DIN EN ISO 20567-1 is carried out for testing, in which a hot-dip galvanized component is subjected to loads from many small, sharp-edged impact bodies accelerated by means of compressed air.
  • the degree of damage to the galvanized layer is significantly reduced in the components hot-dip galvanized according to the invention compared to hot-dip galvanized components without surface treatment.

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EP19801839.2A 2019-02-25 2019-11-08 Verfahren zur verzinkung, insbesondere feuerverzinkung, von eisen- und stahlerzeugnissen Active EP3880860B1 (de)

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