EP3880860A1

EP3880860A1 - Method for the zinc plating, in particular galvanising, of iron and steel products

Info

Publication number: EP3880860A1
Application number: EP19801839.2A
Authority: EP
Inventors: Thomas PINGER; Lars Baumgürtel
Original assignee: Fontaine Holdings NV
Current assignee: Fontaine Holdings NV
Priority date: 2019-02-25
Filing date: 2019-11-08
Publication date: 2021-09-22
Anticipated expiration: 2039-11-08
Also published as: PL3880860T3; MA54218A; DK3880860T3; SI3880860T1; HUE060841T2; DE102019108033A1; WO2020173586A1; EP3880860B1; ES2934125T3

Abstract

The present invention relates to a method for producing an aluminium-alloyed (aluminium-containing) zinc layer, in particular with increased layer thickness, on an iron-based component, preferably a steel component, by means of galvanisation (hot-dip galvanisation), in particular a method for increasing and/or adjusting, preferably increasing, the layer thickness of an aluminium-alloyed (aluminium-containing) zinc layer produced by means of galvanising on an iron-based component, and to a component provided with an aluminium-alloyed (aluminium-containing) zinc layer and obtainable in this way, and to the use of said component.

Description

Process for galvanizing, in particular

Hot-dip galvanizing of iron and steel products

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 areas of application (e.g. for the construction industry, the area of general mechanical engineering, the electrical industry, etc.), by means of hot-dip galvanizing (hot-dip galvanizing).

In particular, the present invention relates to a method and a system for producing an aluminum-alloyed or aluminum-containing zinc layer, in particular with an increased layer thickness, on an iron-based component, in particular a steel component, and also the products obtainable by the method according to the invention or in the system according to the invention (ie hot-dip galvanized iron-containing components) and their respective use.

Metallic components of any kind made of ferrous material, in particular components made of steel, often require efficient protection against corrosion, depending on the application. In particular, steel components for the automotive sector (automotive 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 that can withstand long-term loads.

In this context, it is known to protect steel-based components against corrosion and wear by means of galvanizing (galvanizing). When galvanizing, the steel is provided with a zinc layer to protect the steel from corrosion and wear. Various galvanizing processes can be used to galvanize components made of steel, i.e. to coat them with a metallic coating of zinc, whereby in particular hot-dip galvanizing (synonymously also known as hot-dip galvanizing), spray galvanizing (flame spraying with zinc wire), diffusion galvanizing (Sherard galvanizing ), galvanizing (electrolytic galvanizing), non-electrolytic galvanizing by means of zinc flake coatings and mechanical galvanizing are to be mentioned. There are major differences between the aforementioned galvanizing processes, particularly with regard to the process implementation, but also with regard to the nature and properties of the zinc layers or zinc coatings produced.

Probably the most important process for corrosion protection, but also wear protection of steel through metallic zinc coatings, is hot-dip galvanizing (hot-dip galvanizing). Steel is immersed continuously (e.g. strip and wire) or piece by piece (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), so that a resistant alloy layer of iron and zinc is formed on the steel surface and a very firmly adhering pure zinc layer is formed on top (see also Fig. 1A).

Hot-dip galvanizing has therefore been a recognized and proven method for many years to protect parts or components made of ferrous materials, in particular steel materials, from corrosion, but also from wear. As described above, the typically pre-cleaned or pretreated component is immersed in a hot liquid zinc bath, which reacts with the zinc melt and, as a result, a zinc layer that is metallurgically bonded to the base material is formed.

In hot-dip galvanizing, a distinction is made between discontinuous batch galvanizing (see e.g. DIN EN ISO 1461) and continuous strip and wire galvanizing (see e.g. DIN EN 10143 and DIN EN 10346). Both batch galvanizing and strip and wire galvanizing are standardized or 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 afterwards be hot-dip galvanized (which protects the components from corrosion all round). Strip / wire galvanizing and piece galvanizing also differ in terms of the zinc layer thickness, which - also depending on the zinc layer - results in different protection periods. The zinc layer thickness of galvanized sheet metal is mostly at most 20 to 25 micrometers, whereas the zinc layer thickness of piece-galvanized steel parts can usually be in the range of 50 to 200 micrometers 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 nobler metals of the electrochemical voltage series, such. B. iron, zinc serves as a sacrificial anode, which protects the underlying iron from corrosion until the zinc itself is completely corroded.

In the so-called piece galvanizing in accordance with DIN EN ISO 1461, mostly larger steel components and structures are hot-dip galvanized. Steel-based blanks or finished workpieces (components) are immersed in the molten zinc bath after pre-treatment. By dipping, in particular, inner surfaces, weld seams and hard-to-reach areas of the workpieces or components to be galvanized can also be easily reached.

Conventional hot-dip galvanizing is based in particular on the immersion of iron or steel components in a zinc melt with the formation of a zinc coating or a zinc coating on the surface of the components. To ensure the adhesion, the cohesion and the uniformity of the zinc coating, a careful surface preparation of the components to be galvanized is generally required beforehand, which is usually degreasing with subsequent rinsing, subsequent acid pickling with subsequent rinsing and finally flux treatment (i.e. so-called fluxing) ) with subsequent drying process.

The typical process sequence for conventional batch galvanizing using hot-dip galvanizing is usually as follows:

First, the component surfaces of the components in question are subjected to degreasing in order to remove residues of fats and oils, whereby aqueous, alkaline or acidic degreasing agents can usually be used as degreasing agents. After cleaning in the degreasing bath, there is usually a rinsing process, typically by immersion in a water bath, in order to prevent degreasing agents from being carried over into the subsequent pickling process step, especially when changing from alkaline degreasing to acidic pickling is of great importance. Following the degreasing with a subsequent rinsing process, a pickling treatment (pickling) is usually carried out, which is used, in particular, to remove impurities inherent in the species, such as. B. rust and scale, is used by the steel surface. Acid pickling is usually carried out in dilute hydrochloric acid, the duration of the pickling process depending, among other things, on the state of contamination (e.g. degree of rusting) of the material to be galvanized and the acid concentration and temperature of the pickling bath. To avoid or minimize the carryover of acid and / or salt residues with the galvanized material, a rinsing process (rinsing step) is usually also carried out after the pickling treatment.

Then the so-called fluxing (synonymously also referred to as flux treatment) takes place, whereby the previously degreased and pickled steel surface with a so-called flux, which is typically an aqueous solution of inorganic chlorides, most often with a mixture of zinc chloride (ZnCh) and ammonium chloride (NH ₄ CI). On the one hand, it is the task of the flux to carry out a final, intensive, ultra-fine cleaning of the steel surface before the steel surface reacts with the molten zinc and to dissolve the oxide skin of the zinc surface and to prevent renewed oxidation of the steel surface until the galvanizing process. On the other hand, the flux should increase the wettability between the steel surface and the molten zinc. After the flux treatment, drying then usually takes place in order to create a solid flux film on the steel surface and to remove adhering water, so that subsequent undesired reactions (especially the formation of water vapor) in the liquid zinc immersion bath are avoided.

The components pretreated in the aforementioned manner are then hot-dip galvanized by immersion in the liquid zinc melt. In hot-dip galvanizing with pure zinc, the zinc content of the melt according to DIN EN ISO 1461 is at least 98.0% by weight. After the material to be galvanized has been dipped into the molten zinc, it remains in the molten zinc bath for a sufficient period of time, in particular until the material to be galvanized has reached its temperature and is coated with a zinc layer. Typically, the surface of the zinc melt is cleaned, in particular of oxides, zinc ash, flux residues and the like, before the material to be galvanized is then pulled out of the zinc melt. 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 holding means for the component, such as B. slings, tie wires or the like removed. Passivation or sealing can also take place as part of the post-treatment.

Subsequent to the galvanizing process, post-processing or post-treatment can usually take place. Here z. B. excess zinc bath residues, in particular so-called dripping noses of the zinc solidifying at the edges and oxide or ash residues that adhere to the component, removed as far as possible.

One criterion for the quality of hot-dip galvanizing with pure zinc is the thickness of the zinc coating in pm (micrometers). The standard DIN EN ISO 1461 specifies the minimum values of the required coating thicknesses, as they are to be delivered depending on the material thickness for batch galvanizing. In practice, the layer thicknesses are significantly higher than the minimum layer thicknesses specified in DIN EN ISO 1461. Generally, zinc coatings produced by batch galvanizing with pure zinc have a thickness in the range of 50 to 200 micrometers and even more.

During the galvanizing process with pure zinc, as a result of the mutual diffusion of the liquid zinc with the steel surface on the steel part, a coating of differently composed iron / zinc alloy layers is formed (cf. FIG. 1A). The growth of the iron / zinc alloy layer is a time-dependent process, so that the alloy layer grows with the dwell time and very thick iron / zinc alloy layers are formed with long dwell times. When the hot-dip galvanized objects are pulled out, a layer of zinc - also known as the pure zinc layer - remains adhering to the topmost alloy layer, the composition of which corresponds to the zinc melt. Because of the high temperatures during hot dipping, a relatively brittle layer based on an alloy (mixed crystal layer) between iron and zinc (Fe / Zn phase layer) forms on the steel surface and only above does the pure zinc layer (see Fig. 1A ). The relatively brittle iron / zinc alloy layer (Fe / Zn phase layer) improves the adhesive strength with the base material, but makes it more difficult to form the galvanized steel. Higher silicon contents in steel, as they are in particular for So-called calming of the steel are used during its production, lead to an increased reactivity between the zinc melt and the base material and consequently to a strong growth of the iron / zinc alloy layer. In this way, relatively large total layer thicknesses are formed. Although this enables a very long corrosion protection period, the greater the zinc layer thickness, the greater the risk that the layer will flake off under mechanical stress, in particular local sudden impacts, and that the corrosion protection effect will be impaired as a result.

In order to counteract the previously described problem of the appearance of the rapidly growing, brittle and thick iron / zinc alloy layer and also to enable thinner layers with a high level of corrosion protection during galvanizing, it is equally known from the prior art to use the zinc melt or the liquid Add aluminum to the zinc bath. For example, adding up to 5% by weight of aluminum to a liquid zinc melt produces a zinc / aluminum alloy with a lower melting temperature than pure zinc. By using a zinc / aluminum melt (Zn / Al melt) or a liquid zinc / aluminum bath (Zn / Al bath), on the one hand, significantly lower layer thicknesses can be achieved for reliable corrosion protection (generally below 25 micrometers) ); On the other hand, the formation of the brittle iron / zinc alloy layer does not occur because the aluminum - without being bound by any particular theory - initially forms a barrier layer on the steel surface of the component in question in the form of a very thin (approx. 500 nm) Al / Fe phase -Barrier layer forms on which the actual aluminum-alloyed or aluminum-containing galvanized layer is then deposited (see. Fig. 1 B). The formation of the barrier layer also limits the total layer thickness, so that longer dwell times do not result in an increase in the layer thickness and a maximum layer thickness cannot be exceeded.

Components that are hot-dip galvanized with a zinc / aluminum melt can be reshaped without any problems due to their low layer thickness, but still have improved properties - despite the significantly lower layer thickness compared to conventional hot-dip galvanizing with a virtually aluminum-free zinc melt Corrosion protection properties (ie generally improved compared to the thicker galvanized layers from hot-dip galvanizing with pure zinc).

A zinc / aluminum alloy used in the hot-dip galvanizing bath also has improved fluidity properties and a lower melting point than pure zinc. In addition, zinc coatings, which are produced by means of hot-dip galvanizing carried out using such zinc / aluminum alloys, have greater corrosion resistance (which is up to six times better than that of pure zinc), a better appearance, improved formability and better paintability than pure zinc zinc coatings formed. 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 US 2003/0219543 A1). There, suitable fluxes for hot-dip galvanizing using zinc / aluminum melt baths are also disclosed, since flux compositions for zinc / aluminum hot-dip galvanizing baths have to be of a different nature than those for conventional hot-dip galvanizing with pure zinc. With the method disclosed there, corrosion protection coatings with very small layer thicknesses (generally below 25 micrometers, typically in the range from 2 to 15 micrometers) and with a very low weight can be produced with high cost efficiency, the method described there being commercially available under the name microZINQ - Procedure is applied.

With regard to the formation of the zinc layer and its properties, it has been shown that the zinc layer can be significantly influenced by alloying elements in the zinc melt. Aluminum is one of the most important elements: It has been shown that with an aluminum content of 100 ppm in the zinc melt (based on weight), the appearance of the resulting zinc layer can be improved to a lighter, shinier appearance. With an increasing aluminum content in the zinc melt of up to 1,000 ppm (based on weight), this effect increases steadily. Furthermore, it has been shown that - as already described above - from an aluminum content in the Zinc melt of 0.12% by weight forms an intermetallic Fe / Al phase between the iron material and the upper zinc layer, which leads to the otherwise usual diffusion processes between iron and zinc melt being inhibited and thus the growth of the Zn / Fe phases is significantly reduced; As a result, significantly thinner zinc layers result from this aluminum content in the zinc melt (cf. FIG. 1B). Finally, it has been shown that, in principle, with increasing aluminum content in the zinc melt, the corrosion protection effect of the resulting zinc layer increases; The basis for this is that the Al / Zn compounds form significantly more stable outer layers more quickly.

Known examples of the commercial use of aluminum-containing zinc baths are the so-called Galfan method and the aforementioned MICROZINQ ^® process with an aluminum content in the zinc melt is typically in the range of 4.2 wt .-% to 6.2 wt .-%. The advantage of this alloy is, among other things, that the Al / Zn system has a eutectic composition of around 5% by weight with a melting point of 382 ° C, which enables the operating temperature to be reduced in the galvanizing process.

The corrosion protection effect of a zinc layer is influenced on the one hand by the composition of the zinc layer and on the other hand by the thickness of the zinc layer.

For economic and technical reasons, however, the zinc layer should, if possible, only be as thick as is necessary for the corresponding area of application and the expected service life. The zinc layers formed by classic hot-dip galvanizing (ie in a pure zinc bath) are generally disproportionately thick, while the zinc layers of 8 to 15 μm on average, which are formed by hot-dip galvanizing in zinc / aluminum alloys, are considerably thinner. Despite this highly efficient use of resources, under special boundary conditions it can happen that a higher zinc layer thickness is required in order to meet the specific corrosion requirements. This can be the case when there is a very high level of corrosion, e.g. B. by the action of aggressive chemicals, or when a combined corrosive, mechanical and / or thermal load occurs. In particular, it has so far not been possible to use iron-based components in this way to provide an aluminum-alloyed or aluminum-containing zinc layer that results in a thickness that is between the thickness obtainable by classic hot-dip galvanizing and the thickness obtainable by hot-dip galvanizing in a Zn / Al alloy and which can be individually adjusted for the specific area of application.

The disadvantage of using aluminum-alloyed or aluminum-containing zinc melts (Zn / Al melts) is therefore in particular that the formation of specifically 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 galvanized layer is reached according to conventional methods, even a longer dwell time in the zinc / aluminum melt does not lead to any further increase in the zinc layer thickness, as the formation of the Fe / Al phase in the manner of a 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 problem on which the present invention is based therefore consists in providing a method for hot-dip galvanizing (hot-dip galvanizing), in particular of iron-based or iron-containing components, preferably steel-based or steel-containing components (steel components), using an aluminum-containing or aluminum-alloyed zinc melt and a relevant system for Carrying out this process, the disadvantages of the prior art described above being at least largely avoided or at least alleviated.

In particular, such a method or such a system is to be provided which, compared to conventional hot-dip galvanizing processes or systems operated using an aluminum-containing or aluminum-alloyed zinc melt, 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 enables improved process economy and / or a more efficient, in particular more flexible and / or more reliable, in particular less error-prone process flow and / or improved economic compatibility and / or improved use of costs and resources. To solve the problem described above, the present invention proposes - according to a first aspect of the present invention - a method for hot-dip galvanizing according to claim 1; further, in particular special and / or advantageous configurations of the method according to the invention are the subject matter of the related method subclaims.

Furthermore, the present invention relates - according to a second aspect of the present invention - to a system for hot-dip galvanizing according to the relevant independent system claim; further, in particular special and / or advantageous configurations of the system according to the invention are the subject of the relevant system subclaims.

Furthermore, the present invention relates - according to a third aspect of the present invention - to a hot-dip galvanized (hot-dip galvanized) iron-based component, preferably steel component, obtainable by the method according to the invention or in a system according to the invention, according to the relevant independent product claims; further, in particular special and / or advantageous configurations of this aspect of the invention are the subject matter of the relevant product subclaims.

Finally, the present invention relates - according to a fourth 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 area according to the relevant independent claims.

It goes without saying in the following statements that configurations, embodiments, advantages and the like, which are explained below for the purpose of avoiding repetitions only for one aspect of the invention, of course also apply accordingly with regard to the other aspects of the invention, without this being a separate one Mention is required. With all of the relative or percentage weight-related information mentioned below, in particular relative amounts or weight information, it should also be noted that these are to be selected by the person skilled in the art within the scope of the present invention in such a way that they are in total including all components or ingredients, in particular as defined below, always add to or add to 100% or 100% by weight; but this goes without saying for the expert.

In addition, it applies that the person skilled in the art - depending on the application or in individual cases - can, if necessary, deviate from the range information listed below without departing from the scope of the present invention.

In addition, all of the values or parameters or the like mentioned below can in principle be determined or determined using standardized or standardized or explicitly stated determination methods or otherwise with determination or measurement methods that are familiar to the person skilled in the art.

Having said that, the present invention will now be explained in detail below.

The present invention - according to a first aspect of the present invention - is thus a method for producing an aluminum-alloyed and / or aluminum-containing zinc layer, in particular with an increased layer thickness, on an iron-based component, preferably a steel component, by means of hot-dip galvanizing (hot-dip galvanizing), in particular a method to increase and / or adjust, preferably increase, the layer thickness of an aluminum-alloyed and / or aluminum-containing zinc layer on an iron-based component produced by means of hot-dip galvanizing,

wherein the process comprises the following process steps in the order listed below:

(A) increasing and / or setting, preferably increasing, the surface roughness of at least one surface of the iron-based component; then

(b) Hot-dip galvanizing of the iron-based component in an aluminum-alloyed and / or aluminum-containing zinc melt ("Zn / Al melt"). As explained below, the present invention is associated with a large number of completely unexpected advantages, special features and surprising technical effects, the description of which does not claim to be exhaustive, but illustrates the inventive character of the present invention:

Surprisingly, within the scope of the present invention, through the mechanical processing of the iron-based component surface and through the adjustment of the surface roughness achieved in step (a), it is possible to adjust the zinc layer thickness in the subsequent step (b) and thereby increase and adjust the zinc layer thickness in a targeted manner (and although without in particular the quality of the resulting corrosion protection properties and the resulting mechanical properties being impaired). The term “increase or increase in the surface roughness” relates to the original surface state of the component (i.e. before step (a) is carried out).

On the contrary, the present invention results in improved anti-corrosion properties and also excellent, if not improved, mechanical and other properties (e.g. wear properties).

The fact that the mechanical increase or adjustment of the surface roughness in process step (a) leads to the fact 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 (i.e. without pretreatment according to step (a)) can be significantly increased or adjusted individually, is completely surprising and was not to be expected by the person skilled in the art. In the hot-dip galvanizing process 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 galvanized layer opposite. In the context of the present invention, however, it was completely surprisingly found that the mechanical pretreatment according to method step (a) of the method according to the invention nevertheless completely unexpectedly leads to a significant increase in layer thickness and to an individual controllability of the layer thickness growth in the subsequent hot-dip galvanizing step (b) using a Zn / Al- Melt leads. In the context of the method according to the invention, it has surprisingly been shown that the mechanical roughening of the component surface in question and the resulting adjustment of the surface roughness, the layer thickness of the galvanized layer produced by hot-dip galvanizing with a Zn / Al melt can be specifically or individually adjusted, with opposite conventional hot-dip galvanizing processes with a Zn / Al melt, the resulting galvanizing layer thicknesses can be significantly increased or increased or adjusted.

Without wishing to be tied to a specific theory, 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 run-off behavior, which means that the zinc layer thickness - depending on the Surface roughness - increased, so that as a result there is an increase in the anti-corrosion effect as well as mechanical and other properties. The increased zinc layer thickness therefore increases the anti-corrosion effect, based on the occurrence of base material corrosion (red rust). Furthermore, the mechanical resistance, in particular the resistance of the component to an applied load, especially the abrasion resistance, which denotes the resistance to friction, and also the adhesive strength and the resilience as a result of impacts or impacts, such as stone chips. This finding is all the more surprising as zinc layers that are produced in the traditional batch galvanizing process become susceptible to mechanical loads with increasing layer thickness.

As a result of the present invention, the already good properties of aluminum-alloyed or aluminum-containing galvanized layers with regard to their corrosion protection effect and their mechanical resistance can consequently be further enhanced.

In the context of 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. For an increased layer thickness, it does not have to go back to a pure zinc melt that correlates with inferior properties. be grasped; 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 can even be tailored or individually adjusted.

By using an aluminum-alloyed or aluminum-containing zinc melt ("Zn / Al melt"), the hot-dip galvanized iron-based components available according to the invention also have all the other advantages associated with a zinc / aluminum alloy compared to zinc coatings formed from pure zinc, such as: B. improved optics, improved formability and better paintability. The advantage of the melting point of the zinc / aluminum melt, which is lower than that of a pure zinc melt, with the lower working temperatures that this makes possible is also retained.

Furthermore, the total layer thickness resulting from the method 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.e. 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 galvanized layers, in particular with identical layer thicknesses. Because of this good reproducibility, the method according to the invention can also be used in large-scale productions or in large-scale production.

Another 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. Increasing the layer thickness of the aluminum-alloyed or aluminum-containing galvanized layer of a component can be useful, for example, if only the relevant areas of a component are exposed to increased corrosion and / or increased mechanical stress (e.g. special vehicle carrier components in body construction, special building components Etc.). Surprisingly, the surface roughness introduced in step (a) in the process according to the invention is at least largely or even completely leveled 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 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.

Another 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. In particular, cleaning using pickling in an acidic medium can be significantly shortened or even omitted entirely. This also significantly reduces or even completely eliminates the undesired possible introduction of hydrogen from the acidic pickling solution into the galvanized material. This is particularly advantageous for high-strength and ultra-high-strength steel components with a strength above 1,000 MPa, which according to DIN 55969 has an increased risk of embrittlement due to hydrogen, which is why the pickling time is limited to less than 15 minutes for high-strength components. In addition, the shortening or omission of the pickling process results in an improvement from an economic point of view, above all an improvement in the use of costs and resources.

Existing systems for conventional hot-dip galvanizing with Zn / Al melts can also be easily supplemented or retrofitted (namely by adding a device for performing step (a), which is also implemented decentrally or spatially separated from the actual hot-dip galvanizing in step (b) can be).

The peculiarities of the process according to the invention and consequently the system according to the invention described below are also reflected directly in the process products available, ie 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 due to the aluminum-containing or aluminum-alloyed components Galvanized layer on, but can also use a made-to-measure aluminum-alloyed or aluminum-containing zinc layers are provided, in particular precisely adapted to the corresponding requirements.

As microscopic examinations of sections (cross-sections) of the components obtainable according to the invention show, the components according to the invention are characterized by a special surface structure (cf. Fig. 1C and Figs. 3A and 3B): As a result of the roughening treatment according to process step (a), the Components according to the invention have a significantly higher or adjusted roughness of the surface of the base material compared to non-roughened component surfaces, but which is at least substantially completely leveled or leveled in the finished end product by the applied aluminum-containing or aluminum-alloyed galvanizing layer. The microscopic examinations also show that in comparison to aluminum-containing or aluminum-alloyed galvanizing layers produced by means of hot-dip galvanizing without prior roughening, a significantly higher layer thickness of the upper aluminum-containing or aluminum-alloyed hot-dip galvanizing layer is obtained. The increase in layer thickness leads in the same way to improved corrosion protection properties and to improved mechanical properties (e.g. improved abrasion resistance, improved wear protection properties, etc.), since the pretreatment according to the invention does not affect the other properties of the aluminum-containing or aluminum-alloyed galvanized layer, in particular not their Adhesion in relation to the underlying material surface.

As a result, the products according to the invention therefore have a special layer structure, which can be documented and demonstrated by microscopic examinations of sections of the products in question (see figure representations 1A, 1B and 1C as well as 3A and 3B discussed below in comparison with the conventional ones Method produced layers according to FIGS. 1A and 1B). In particular, the roughening of the surface carried out prior to the hot-dip galvanizing treatment remains recognizable or verifiable in the microscopic section in the end product. In the context of the present invention, an efficiently and economically working hot-dip galvanizing process or a corresponding system can thus be provided, whereby the above-described disadvantages of the prior art can at least largely be avoided or at least mitigated.

Preferred embodiments of the method according to the invention and the method sequence according to the invention are described and explained in more detail below:

As described above, 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.

In the context of method step (a) according to the invention, the surface roughness is increased and / or adjusted (also referred to synonymously as surface roughness or surface roughness). The term surface roughness (synonymously also referred to as roughness) is a term from surface physics, which describes the unevenness of the surface height. There are different calculation methods for the quantitative characterization of the roughness, each of which takes into account the different characteristics of the surfaces. 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 detail below.

Within the scope of the method according to the invention, the increase and / or adjustment of the surface roughness in method step (a) can be carried out on at least one surface of the iron-based component, preferably on several surfaces of the iron-based component. According to a particular embodiment of the present invention, the increase and / or adjustment of the surface roughness in method step (a) can be carried out 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 on their entire surface, which components can then be provided as a whole or as a whole with a galvanized layer with an increased zinc layer thickness. According to an alternative particular embodiment of the present invention, the increase and / or adjustment of the surface roughness in method step (a) can only be carried out 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 and / or wear and tear) when they are used, so that only these areas in question have to be protected more intensively, namely by Formation of a thicker galvanized layer in the relevant areas. Thus, within the scope of the method according to the invention, it is also possible to increase or adjust the surface roughness only on those surfaces of a component which, due to their arrangement in the end product, require an increased zinc layer thickness. For example, chassis components used in the automotive sector, such as axle carriers and tension struts, can only be specifically reinforced on the side facing the road, as these surfaces are more exposed to stone chips, corrosion loads from de-icing salts, thermal loads due to the exhaust duct running above and increased mechanical loads are. In order to enable a long service life without premature wear of the component despite this increased load or stress, the zinc layer thickness can be increased locally or in areas only at the relevant wear points of the component and thus the resistance can only be improved there. In the context of process step (a) of the process according to the invention, the increase and / or adjustment of the surface roughness is usually carried out by a mechanical treatment. Mechanical treatment methods for increasing and / or adjusting the surface roughness are sufficiently known as such to the person skilled in the art.

As far as the increase and / or adjustment of the surface roughness in process step (a) by a mechanical treatment is concerned, this increase and / or adjustment of the surface roughness can in particular by means of abrasion and / or by means of an abrasive method, preferably by means of compressed air blasting with solid blasting material (synonymous also referred to as "sandblasting").

In the context of the invention, abrasion or an abrasive method is to be understood as meaning, in particular, abrasive removal, that is to say the removal of material through the mechanical action of a friction partner. During abrasive removal, the roughness peaks of one friction partner penetrate the edge layers of the other or hard particles from an intermediate material penetrate the edge layers of the friction partner, which leads to micro-machining, scoring, scoring or the like. This effect is used in the context of the invention when increasing or adjusting the surface roughness, for example by means of compressed air jets with solid blasting material (blasting media). With compressed air blasting, compressed air serves as a carrier medium for the blasting material to be accelerated, which is brought onto the surface to be treated and the impact of which has an abrasive effect. A particular advantage of using compressed air blasting systems lies in the extensive adaptability to the size, shape and surface technical requirements of the objects to be processed, as well as in the almost unlimited usability of a wide variety of metallic, mineral and organic blasting material (also known as "blasting media"), see above that the right system can be selected for every application or the system can be adapted to the object to be processed.

In the context of the invention, the blasting material (blasting medium) 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 ball blasting material.

It is particularly preferred if the blasting material used in process step (a) has a round, spherical, angular or cylindrical grain shape, preferably an angular grain shape. The use of angular blasting material is particularly preferred, since this enables a strong roughening in a short time and with low steel pressure.

It is preferred if the blasting material used in process step (a) has an absolute grain size in the range from 30 to 5,000 μm, in particular in the range from 50 to 3,000 μm, preferably in the range from 60 to 1,500 μm, particularly preferably in the range from 70 to 1 .000 pm, very particularly preferably in the range from 75 to 800 pm. This grain size is particularly suitable for roughening the surface without permanently damaging or changing the components. If the blasting material or the blasting material particles are irregularly formed, the grain size is based on the largest dimension of the blasting material particles.

It is also preferred if the blasting material used in process step (a) 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 in the range from 250 to 1,500 HV.

In addition, it is preferred if 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 of 3 to 7 Mohs, preferably in the range from 3.5 to 6.5 Mohs.

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 or leveled by the 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 exposed to 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 at least one surface of the iron-based component is allowed 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 a maximum of 15 bar, in particular a maximum of 11 bar, preferably a maximum of 8 bar, particularly preferably a maximum of 5 bar.

The blasting duration in process step (a) can also vary within a wide range:

In general, it is advantageous if the blasting material is allowed to act on the at least one surface of the iron-based component for a duration of 10 seconds to 30 minutes, in particular 15 seconds to 20 minutes, preferably 20 seconds to 10 minutes.

It is preferred if the blasting material is allowed to act on the at least one surface of the iron-based component for a duration of up to 30 minutes, in particular up to 20 minutes, preferably up to 10 minutes.

In the context of the invention, it is particularly preferred if the blasting material is allowed to act on the at least one surface of the iron-based component for a duration of at least 10 seconds, in particular at least 15 seconds, preferably at least 20 seconds.

In general, the aforementioned process conditions or process parameters for process step (a), in particular the conditions for the mechanical treatment, in particular by means of abrasion, preferably by means of a compressed air jet with solid blasting material, such as the type and size of the Blasting material, blasting treatment, blasting pressure, blasting duration, etc., designed or selected in such a way that the surface roughness is adapted or tailored to the target or intended layer thickness of the aluminum-alloyed or aluminum-containing galvanized layer resulting after hot-dip galvanizing in process step (b). In this way, by carrying out process step (a), in particular the specifically adjusted increase in surface roughness, the layer thickness of the galvanized layer resulting from process step (b) can be specifically controlled or controlled or tailored.

The aforementioned process conditions for process step (a) enable a particularly efficient setting and / or increase in the surface roughness (without damaging the surface) and in particular enable individual adaptation to the corresponding application requirements.

In the context of the present invention, it is preferred if 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 roughness value Ra, in particular according to DIN EN ISO 4288: 1998-04 , of at least 0.3 μm, in particular at least 0.6 μm, preferably at least 0.7 μm, particularly preferably at least 0.8 μm.

According to a particular embodiment of the present invention, 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 roughness value Ra, in particular according to DIN EN ISO 4288: 1998-04, in the range from 0.3 to 20 pm, in particular in the range from 0.6 to 15 pm, preferably in the range from 0.7 to 13 pm, particularly preferably in the range from 0.8 to 12 pm.

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 mean line. To determine this measured value, the surface is scanned on 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 (see DIN EN ISO 4288: 1998-04 cited above). It is also preferred if 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 roughness depth Rz, in particular according to DIN EN ISO 4288: 1998-04, of at least 2 gm, in particular at least 3 gm, preferably at least 4 gm.

In addition, it is particularly preferred according to the invention if 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 roughness depth Rz, in particular according to DIN EN ISO 4288: 1998-04 , in the range from 2 to 75 gm, in particular in the range from 3 to 70 gm, preferably in the range from 3 to 65 gm.

The mean roughness depth 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 averaging the results of five individual measurement sections. Overall, the mean roughness depth Rz reacts more sensitively to changes in surface structures than the mean roughness value Ra (cf. DIN EN ISO 4288: 1998-04 cited above).

In addition, it is preferred according to the invention if 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 roughness depth Rmax, in particular according to DIN EN ISO 4288: 1998-04, of at least 3 gm, in particular at least 4 gm, preferably at least 5 gm.

It is particularly preferred if 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 roughness depth Rmax, in particular according to DIN EN ISO 4288: 1998-04, in the range from 3 to 95 gm, in particular in the range from 4 to 90 gm, preferably in the range from 5 to 85 gm.

The maximum roughness depth Rmax describes the greatest of the five individual roughness depths within a measuring section (cf. DIN EN ISO 4288: 1998-04 cited above). According to a particular embodiment of the present invention, the surface roughness is increased in process 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 process step (a) by at least 10%, in particular is increased 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 mean roughness value Ra before the surface treatment). For example, the surface roughness can be increased in process 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 process step (a) by 10% up to 300%, in particular by 25% up to 200% (ie based on the mean roughness value Ra before surface treatment). In other words, the percentage increase in the 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 process step (a) to the mean roughness value Ra before carrying out process step (a).

According to a further particular embodiment of the present invention, the surface roughness is increased in process step (a) in such a way that the mean roughness depth Rz, in particular according to DIN EN ISO 4288: 1998-04, of the surface treated in process step (a) by 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 mean roughness depth Rz before the surface treatment). For example, the surface roughness can be increased in process step (a) in such a way that the mean roughness depth Rz, in particular according to DIN EN ISO 4288: 1998-04, of the surface treated in process step (a) by 10% up to 300% , in particular by 25% up to 200% (ie based on the mean surface roughness Rz before surface treatment). In other words, the percentage increase in surface roughness, characterized by the increase in the mean roughness depth Rz, is described by the percentage ratio of the mean roughness depth Rz after carrying out process step (a) to the mean roughness depth Rz before carrying out process step (a). According to yet another special embodiment of the present invention, the surface roughness is increased in process step (a) in such a way that the maximum roughness depth Rmax, in particular according to DIN EN ISO 4288: 1998-04, of the surface treated in process step (a) by 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 maximum surface roughness Rmax before the surface treatment). For example, the surface roughness can be increased in process step (a) in such a way that the maximum roughness depth Rmax, in particular according to DIN EN ISO 4288: 1998-04, of the surface treated in process step (a) by 10% up to 300% , in particular by 25% up to 200%, is increased (ie based on the maximum surface roughness Rmax before the surface treatment). In other words, the percentage increase in surface roughness, characterized by the increase in the maximum surface roughness Rmax, is described by the percentage ratio of the maximum surface roughness Rmax after performing method step (a) to the maximum surface roughness Rmax before performing method step (a).

In the process according to the invention, process step (a) is followed by process step (b), the hot-dip galvanizing of the iron-based component in an aluminum-alloyed or aluminum-containing zinc melt ("Zn / Al melt").

In general, in method step (b), the iron-based component is provided or coated or coated with an aluminum-alloyed and / or aluminum-containing zinc layer. In other words, after the method described above has been carried out, an iron-based component provided or coated or coated with an aluminum-alloyed and / or aluminum-containing zinc layer is obtained.

Advantageously, the aluminum-alloyed or aluminum-containing zinc layer, as obtained within the scope of the method according to the invention, in particular after method step (b) of the method according to the invention, preferably has a layer thickness in the range from 3 to 30 μm, in particular in the range from 4 to 28 μm in the range from 5 to 27 pm, particularly preferably in the range from 6 to 25 pm. The aluminum-alloyed or aluminum-containing zinc layer, which is obtainable by the method according to the invention or results in the context of 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 performing method step (b) with omission of the preceding method step (a). This means that the aluminum-alloyed or aluminum-containing zinc layer, which results or is obtainable by the method according to the invention, has 10 to 300%, in particular 125 to 280%, preferably 130 to 250%, of that layer thickness which can only be obtained by identical hot-dip galvanizing is obtained without prior surface roughening. With the method according to the invention, a zinc layer is thus obtained which has an increased layer thickness compared to conventional hot-dip galvanizing layers made from Zn / Al melts.

According to a further particular embodiment, it is provided that 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 μm, in particular around 1 to 12 μm, preferably around 2 up to 10 μm, is greater than the layer thickness which is obtained after carrying out method step (b) with omission of the previous method step (a). This therefore means that 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.

According to a particular embodiment, the hot-dip galvanized iron-based component obtained by method steps (a) and (b) has an at least substantially 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 that is introduced in process step (a) is filled or leveled or leveled in process step (b) so that the surface of the hot-dip galvanized iron-based component does not have any grooves or roughening, but rather is continuous or planar or flat (see. Also Fig. 1C and figure representations 3A and 3B). According to a further particular embodiment, the surface resulting in process step (a) with increased or adjusted surface roughness is at least substantially leveled 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 the roughening of the surface has no influence on the surface structure of the finished hot-dip galvanized component (ie the end product).

In a particular embodiment, it is provided that the increase and / or adjustment of the surface roughness in process step (a) is only carried out in certain areas, in particular only on one surface or not on all surfaces of the iron-based component, so that the in process step (b ) obtained aluminum-alloyed or aluminum-containing zinc layer has different thickness ranges; In particular, 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, as part of 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 further Need reinforcement and adequately protect a conventionally produced hot-dip galvanizing layer. An exemplary application are chassis components whose surface facing the road is exposed to increased stress due to a combination of increased rockfall, corrosion from de-icing salts and thermal stress due to the exhaust gas duct running above. As a countermeasure against the load, which occurs only in some areas or locally, a corresponding increase and / or adjustment of the zinc layer thickness in the load area is sufficient, while the other or remaining surfaces of the chassis components do not require an increased and / or individually adjusted zinc layer thickness because they are not exposed to increased stress. 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 comes. As part of process step (b) of the process according to the invention, 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) usually contains, based on the zinc melt, at least 0.1% by weight, in particular at least 0.15% by weight, preferably at least 0.2% by weight, preferably at least 0.5% by weight, particularly preferably at least 1% by weight, very particularly preferably at least 2% by weight, aluminum.

It is advantageous if the aluminum-alloyed or aluminum-containing zinc melt used in process step (b), based on the zinc melt, 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

Contains 12.5% by weight, very particularly preferably at most 10% by weight, of aluminum.

The aluminum-alloyed or aluminum-containing zinc melt used in method step (b) advantageously contains, based on the zinc melt, 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 wt%, preferably in the range from 0.5 wt% to 15 wt%, particularly preferably in the range from 1 wt% to 12.5 wt%, very particularly preferably in the range from 2 Wt% to 10 wt%.

When using aluminum in the aforementioned amounts in the

Zinc melts are obtained that are particularly corrosion-resistant and particularly easy to process zinc layers.

The aluminum-alloyed or aluminum-containing zinc melt used in process step (b) typically contains

(i) Zinc, especially in amounts ranging from 75 wt% to

99.9% by weight, in particular in the range from 80% by weight to

99.85 wt%, preferably in the range from 85 wt% to

99.8% by weight, preferably in the range from 90% by weight to 99.5% by weight, based on the zinc melt, (ii) Aluminum, in particular 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 15% by weight, preferably in the range from 0.5% by weight to 10% by weight, based on the zinc melt,

(iii) optionally at least one further metal, in particular selected from the group of bismuth (Bi), lead (Pb), tin (Sn), nickel (Ni), silicon (Si), magnesium (Mg) and their combinations, in particular in Amounts of up to 5% by weight and / or in particular in amounts in the range from 0.0001% by weight to 5% by weight, in particular in the range from 0.0005% by weight to 4% by weight, preferably in the range from 0.001% by weight to 3% by weight, preferably in the range from 0.005% by weight to 2% by weight, based on the zinc melt, all of the above-mentioned quantities being selected such that a total of 100% by weight .-% result. The use of a zinc melt with the aforementioned composition has proven to be particularly advantageous in the context of the method according to the invention, since this gives particularly homogeneous and resilient, as well as corrosion-resistant, zinc layers.

According to a particular embodiment, the aluminum-alloyed or aluminum-containing zinc melt used in process step (b) has the following composition, all of the quantities given below refer to the zinc melt and are to be selected such that a total of 100% by weight results:

Zinc (Zn), in particular in amounts in the range from 75 to 99.9% by weight, in particular in the range from 80 to 99.85% by weight, preferably in the range from 85 to 99.8% by weight, preferably in the range from 90 to 99.5% by weight,

- Aluminum (AI), in particular in amounts in the range from 0.1 to 25% by weight, in particular in the range from 0.15 to 20% by weight, preferably in the range from 0.2 to 15% by weight, preferably in the range from 0.5 to 10% by weight,

- optionally bismuth (Bi), in particular in amounts of up to 0.5% by weight, preferably in amounts of up to 0.3% by weight, preferably in amounts of up to 0.1% by weight,

- optionally lead (Pb), in particular in amounts of up to 0.5% by weight, preferably in amounts of up to 0.2% by weight, preferably in amounts of up to 0.1% by weight, Optionally tin (Sn), in particular in amounts of up to 0.9% by weight, preferably in amounts of up to 0.6% by weight, preferably in amounts of up to 0.3% by weight,

- optionally nickel (Ni), in particular in amounts of up to 0.1% by weight, preferably in amounts of up to 0.08% by weight, preferably in amounts of up to 0.06% by weight,

- optionally silicon (Si), in particular in amounts of up to 0.1% by weight, preferably in amounts of up to 0.05% by weight, preferably in amounts of up to 0.01% by weight,

optionally magnesium (Mg), in particular in amounts of up to 5% by weight, preferably in amounts of up to 2.5% by weight, preferably in amounts of up to 0.8% by weight.

According to a typical embodiment of the present invention, it is advantageous if 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 and economical in this temperature range.

Furthermore, it is preferred according to the invention if in method step (b) the iron-based component is immersed in the aluminum-alloyed or aluminum-containing zinc melt, in particular immersed therein and moved, in particular for a period of time which is sufficient to ensure effective hot-dip galvanizing (hot-dip galvanizing) , in particular for a period of time in the range from 0.0001 to 60 minutes, preferably in the range from 0.001 to 45 minutes, preferably in the range from 0.01 to 30 minutes, even more preferably in the range from 0.1 to 15 minutes. In this way, particularly homogeneous, gap-free or flawless and uniform zinc layers are obtained.

According to a further preferred embodiment, the aluminum-alloyed or aluminum-containing zinc melt used in process step (b) is contacted or flushed or passed through with at least one inert gas, in particular nitrogen. This avoids an undesirable reaction of the uncoated surface with the oxygen present; thus no defects are obtained in the zinc layer formed. In the context of the present invention, it is preferred if, before the hot-dip galvanizing in process step (b), a pretreatment of the iron-based component obtained in process step (a) is carried out. This pretreatment enables a particularly uniform and error-free galvanizing result.

According to a preferred embodiment of the present invention, the pretreatment comprises at least one of the following pretreatment steps (wherein the pretreatment preferably comprises the following pretreatment steps (1) to (6) in the order specified below):

(1) degreasing,

(2) rinsing,

(3) pickling if necessary,

(4) rinsing if necessary,

(5) flux treatment (fluxing),

(6) drying if necessary.

According to a particular embodiment of the present invention, the pretreatment step (3) of pickling - compared to a pretreatment for hot-dip galvanizing according to method step (b), but omitting the preceding method step (a) - can be shortened, in particular by at least 10%, preferably by at least 30% of the pickling time, or together with pretreatment step (4) completely. 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.

Due to the increase or adjustment of the surface roughness in process step (a), there is also mechanical cleaning of the component, whereby the otherwise usual pickling in an acidic medium, in particular as described in pretreatment step (3), is completely eliminated or the required treatment time is at least significantly can be shortened. Omitting pretreatment step (3) or shortening its duration has the advantage that the risk of hydrogen entry from the acidic pickling solution into the galvanized material can be completely eliminated or at least significantly reduced, thus excluding the risk of the component becoming brittle as a result of hydrogen entry or can be reduced significantly. As described above, according to one embodiment of the present invention, a pretreatment of the iron-based component obtained in method step (a) is carried out before the hot-dip galvanizing in method step (b) (in particular of the type described above). In particular, within the scope of the present invention, the pretreatment comprises at least one flux treatment (fluxing). The flux treatment leads to an intensive fine cleaning of the surface as well as the wettability between the component surface and the molten zinc is increased and an oxidation of the component surface is prevented during a possible waiting time and drying until the galvanizing process.

According to a particular embodiment of the present invention, a pretreatment of the iron-based component obtained in process step (a) with a flux is carried out before the hot-dip galvanizing in process step (b). In particular, the flux is located or dissolved in a flux bath.

According to a particular embodiment of the present invention, the flux contains the following components (ingredients): (I) zinc chloride (ZnCh), (II) ammonium chloride (NH ₄ CI), (III) optionally at least one alkali and / or alkaline earth salt and (IV ) optionally at least one further 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 their combinations, preferably selected from N1CI ₂ , CoCI ₂ , MnCI ₂ , PbCI ₂ , SnCI ₂ , BiCI ₃ , SbCI ₃ , AICI ₃ and AgCI and their combinations.

According to a further particular embodiment of the method according to the invention, the flux contains the following components (ingredients): (I) zinc chloride (ZnCh), (II) ammonium chloride (NH ₄ CI), (III) at least one alkali and / or alkaline earth salt, preferably sodium chloride and / or potassium chloride, preferably sodium chloride and potassium chloride, and (IV) at least one further 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 , AICI ₃ and AgCI and their combinations, particularly preferably selected from N1CI ₂ , COCI ₂ , MnC, PbC, SnCh, BiCI ₃ and SbCI ₃ and their combinations. According to yet another particular embodiment of the method according to the invention, the flux contains the following components (ingredients), all of the quantities given below refer to the flux and are to be selected such that a total of 100% by weight results: (I) 60 to 80 wt .-% zinc chloride (ZnCl ₂ ), (II) 7 to 20 wt .-% ammonium chloride (NH ₄ CI), (III) 2 to 20 wt .-% of at least one alkali and / or alkaline earth salt, preferably sodium chloride and / or potassium chloride, preferably sodium chloride and potassium chloride, (IV) 0.1 to 5 wt.% of at least one metal salt from the group of NiCl ₂ , COCl ₂ and MnCl ₂ and (IV ") 0.1 to 1.5 wt. % of at least one further metal salt from the group of PbCl ₂ , SnCl ₂ , BiCl ₃ and SbCl ₃ .

The use of the flux compositions described above has proven to be particularly advantageous in order to obtain optimum galvanizing results.

Typically, within the scope of the method according to the invention, the flux bath is aqueous-based or aqueous-alcohol-based.

According to the present invention, the flux bath is usually set to a defined or predetermined, in particular acidic, pH, 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.

According to a particularly preferred embodiment, the flux bath is adjusted to a defined or predetermined, in particular acidic pH value, 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. This embodiment, ie the fine adjustment of the pH value by means of a preferably inorganic basic compound, in particular ammonia (NH ₃ ), is particularly advantageous, since this counteracts undesirable hydrogen embrittlement of the treated component. As far as the flux used according to the invention is concerned, 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.

The amounts of the relevant wetting agent and / or surfactant can vary within wide ranges:

In particular, 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.

Furthermore, 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 likewise vary within wide ranges:

Usually, 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 preferably in an amount of 500 g / l to 575 g / l, in particular calculated as the total salt content of the flux composition. According to the invention it is preferred if the flux treatment is carried out 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.

In the context of the present invention, the procedure is generally such that the flux treatment is carried out by bringing the iron-based component into contact with the flux bath or the flux composition, in particular by dipping or spray application, preferably dipping. In particular, the iron-based component can be used for a period of 0.01 to 30 minutes, in particular 1.5 to 20 minutes, preferably 2 to 15 minutes, preferably 2.5 to 10 minutes, particularly preferably 3 to 5 minutes, with the flux bath or The flux composition are brought into contact, in particular immersed in the flux bath.

According to a particular embodiment of the present invention, 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 in particular take place by means of air and / or in the presence of air, preferably down to ambient temperature.

The further post-processing and / or post-treatment that can optionally be carried out can in particular include passivation and / or sealing. Such post-processing or post-treatment can produce a further protective layer on the component, which further strengthens the corrosion protection.

In principle, the process according to the invention can be operated continuously or discontinuously. 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.

In particular, 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.

Another object of the present invention - according to a second aspect of the present invention - is a system for producing an aluminum-alloyed and / or aluminum-containing zinc layer, in particular with an increased layer thickness, on an iron-based component, preferably a steel component, by means of hot-dip galvanizing (hot-dip galvanizing), in particular a system for Increasing and / or setting, preferably increasing, the layer thickness of an aluminum-alloyed and / or aluminum-containing zinc layer produced by means of hot-dip galvanizing on an iron-based component, preferably a system for carrying out a method as described above,

the system comprising the following devices in the order listed below:

(A) a device for increasing and / or adjusting, preferably increasing, the surface roughness of at least one surface of an iron-based component; arranged downstream and / or downstream of this in the process sequence

(B) a hot-dip galvanizing device for hot-dip galvanizing the iron-based component in an aluminum-alloyed and / or aluminum-containing zinc melt ("Zn / Al melt").

In the context of the present invention, the devices (A) and (B) can be spatially separated from one another.

The device (A) for increasing and / or adjusting the surface roughness typically comprises an abrasion device, in particular a device for compressed air blasting with solid blasting material (blasting media), or is designed as such. It is preferred if 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.

As far as the blasting material used in device (A) and / or located in the receptacle is concerned, it 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 ball blasting material.

The blasting material used in device (A) and / or located in the receptacle usually has a round, spherical, angular or cylindrical grain shape, preferably an angular grain shape.

The grain size of the device (A) used and / or in the

The blasting material in the receptacle can vary over a wide range:

In particular, the device (A) used and / or in the

The blasting material located in the receptacle has an absolute grain size in the range from 30 to 5,000 mti, in particular in the range from 50 to 3,000 mti, preferably in the range from 60 to 1,500 mΐti, particularly preferably in the range from 70 to 1,000 mΐti, very particularly preferably in the range of 75 to 800 mΐti. When using irregularly shaped blasting material, the absolute grain size is related to the largest dimension of the blasting material particle.

Also the grain hardness of the device (A) used and / or in the

The blasting material in the receptacle can vary over a wide range:

In particular, the device (A) used and / or in the

The blasting material 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 1,500 HV . Furthermore, the blasting material used in device (A) and / or located in the receptacle 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 from 3.5 to 6.5 Mohs.

As far as the device (A) used according to the invention 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 concerned, this is in particular designed in such a way that the blasting material 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 on which at least one surface of the iron-based component is allowed to act.

According to a particular embodiment of the system according to the invention, 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 with a blasting pressure of at least 1 bar, in particular at least 2 bar, preferably at least 3 bar, is discharged and / or is allowed to act on the at least one surface of the iron-based component.

It is preferred according to the invention if 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 with a blasting pressure of a maximum of 15 bar, in particular a maximum 11 bar, preferably a maximum of 8 bar, particularly preferably a maximum of 5 bar, is discharged and / or is allowed to act on at least one surface of the iron-based component.

In the context of the present invention it is preferred if the hot-dip galvanizing device (B) comprises a galvanizing bath containing an aluminum-alloyed and / or aluminum-containing zinc melt, in particular as defined above. In particular, it is preferred if the hot-dip galvanizing device (B) is designed to provide and / or coat and / or cover the iron-based component with an aluminum-alloyed and / or aluminum-containing zinc melt.

The system according to the invention is usually designed in such a way that arranged downstream and / or downstream of device (A) and upstream and / or upstream of hot-dip galvanizing device (B), a pretreatment device (C) for pretreatment of the iron-based component roughened in device (A) is provided and / or arranged. In other words, the pretreatment device (C) is arranged between the device (A) and the hot-dip galvanizing device (B).

The pretreatment device (C) typically comprises at least one of the following pretreatment devices, preferably in the order specified below:

(C1) at least one degreasing device, in particular at least one degreasing bath, for degreasing the iron-based component roughened in device (A); downstream in process direction and / or downstream to (C1)

(C2) at least one rinsing device, in particular at least one rinsing bath, for rinsing the iron-based component degreased in the degreasing device (C1); downstream in process direction and / or downstream to (C2)

(C3) optionally at least one pickling device, in particular at least one pickling bath, for the preferably acidic pickling treatment of the iron-based component degreased in the degreasing device (C1) and rinsed in the rinsing device (C2); downstream in process direction or downstream to (C3)

(C4) optionally at least one rinsing device, in particular at least one rinsing bath, for rinsing the iron-based component degreased in the degreasing device (C1), rinsed in the rinsing device (C2) and pickled in the pickling device (C3); downstream in process direction or downstream to (C4) (C5) at least one flux treatment device (flux device), in particular at least one flux bath, for the flux treatment of the flux which has been degreased in the degreasing device (C1), rinsed in the rinsing device (C2) and optionally pickled in the pickling device (C3) and optionally in the rinsing device (C4) flushed iron-based component; downstream in process direction or downstream to (C5)

(C6) optionally at least one drying device, in particular for drying the iron-based metal component subjected to a flux treatment in the flux treatment device (C5).

According to a particular embodiment, the pickling device (C3) together with the rinsing device (C4) can even be completely omitted. This is possible in particular if in device (A) the abrasion device has already removed all of the impurities of their own species, in particular, and thus no pickling in a corresponding pickling device is required.

The devices (C3) and (C4) are mutually dependent, so that if the pickling device (C3) is omitted, the rinsing device (C4) is automatically omitted.

According to the invention it is preferred if a cooling device is arranged downstream in the process direction or downstream of the hot-dip galvanizing device (B). In particular, the cooling device can be designed for cooling by means of air or in the presence of air, preferably down to ambient temperature.

According to a further preferred embodiment, a post-processing device and / or post-treatment device can be arranged downstream in the process direction or downstream of the hot-dip galvanizing device (B) and the cooling device that may be present. In particular, the post-processing device and / or post-treatment device can include a passivation device and / or sealing device or be designed as such. As already described above in connection with the method according to the invention, the plant according to the invention can in principle be designed to be operated continuously or discontinuously and / or operated continuously or discontinuously.

In particular, the system according to the invention can be designed in such a way that the iron-based component can be hot-dip galvanized as a single product or as a plurality of individual, in particular identical products, or that the iron-based component is a long product, in particular a wire, pipe, sheet metal, coil Material or the like, can be hot-dip galvanized.

For further details on the plant according to the invention, to avoid unnecessary repetition, reference can be made to the above statements on the method according to the invention, which apply accordingly with regard to the plant according to the invention.

Another object of the present invention - according to a third aspect of the present invention - is a hot-dip galvanized (i.e. hot-dip galvanized) iron-based component, preferably steel component, which is obtainable by the method according to the invention as described above or in the system according to the invention as described above.

As already described at the outset and in particular also documented by the exemplary embodiments according to the invention, the products according to the invention are associated with particular advantages, in particular an increased layer thickness, especially in specific areas of the component or on the entire component. The increase and / or adjustment of the zinc layer thickness can be controlled by the surface roughness.

As stated above in the context of the method according to the invention, the special features of the method according to the invention or the special features of the system according to the invention are also reflected directly in the process products obtainable hereby or with it, ie 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 protection properties as a result of the aluminum-containing or aluminum-alloyed galvanizing layers, but can also be provided with a tailor-made aluminum-alloy or aluminum-containing zinc layer, in particular precisely adapted to the corresponding requirements.

As microscopic examinations of sections (cross-sections) of the components obtainable according to the invention show, the components according to the invention are distinguished by a special surface structure (cf. Figs. 1 C and 3A and 3B): As a result of the roughening treatment according to process step (a), the components according to the invention have a significantly higher roughness of the surface of the base material compared to non-roughened component surfaces, which, however, is at least substantially completely leveled or leveled in the finished end product by the applied aluminum-containing or aluminum-alloyed galvanizing layer. The microscopic examinations also show that in comparison to aluminum-containing or aluminum-alloyed galvanizing layers produced by means of hot-dip galvanizing without prior roughening, a significantly higher layer thickness of the upper aluminum-containing or aluminum-alloyed hot-dip galvanizing layer is obtained. The increase in layer thickness leads in the same way to improved corrosion protection properties and to improved mechanical properties (e.g. improved abrasion resistance, improved wear protection properties, etc.), since the pretreatment according to the invention does not affect the other properties of the aluminum-containing or aluminum-alloyed galvanized layer, in particular not their Adhesion in relation to the underlying material surface.

As a result, 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 relevant products (cf. figure representations 3A and 3B, which will be discussed below, in comparison to the layers produced by conventional methods according to FIGS. 1A and 1 B). In particular, the roughening of the surface carried out prior to the hot-dip galvanizing treatment remains recognizable or verifiable in the microscopic section in the end product. A hot-dip galvanized iron-based component which has the aforementioned properties in combination can only be obtained by the method according to the invention or only in the system according to the invention. In particular, it is not possible to increase and / or adjust the zinc layer thickness with measures known from conventional hot-dip galvanizing (ie with pure zinc melts) in the case of aluminum-alloyed or aluminum-containing zinc layers. In conventional hot-dip galvanizing with pure zinc, for example, the thickness of the zinc layer increases with the dwell time in the zinc melt; However, this is not possible with aluminum-alloyed or aluminum-containing zinc melts, since initially a barrier layer in the form of a thin (approx. 500 nm) Fe / Al alloy layer is formed, which further growth of the overlying pure Zn / Al layer over a certain amount Limit value beyond (average 6 to 15 pm) prevented.

By increasing and / or adjusting the surface roughness according to the invention in step (a), however, it is surprisingly possible to increase the zinc layer thickness of aluminum-alloyed zinc layers despite the barrier layer being formed (ie Fe / Al phase or Fe / Al barrier layer) and / or discontinue. Only by using the method according to the invention or the system according to the invention is an aluminum-alloyed or aluminum-containing zinc layer obtainable which has the aforementioned properties in their combination; In particular, significantly higher layer thicknesses are achieved compared to conventionally produced aluminum-containing or aluminum-alloyed zinc layers (i.e. hot-dip galvanizing without prior roughening of the surface), whereby the microscopic section shows that the originally roughened surface is at least essentially completely leveled by the aluminum-alloyed or aluminum-containing galvanizing layer or leveled, but remains recognizable or verifiable as such in the section.

Furthermore, it is surprising that the surface structure produced by the method according to the invention is leveled or leveled (leveled) in the course of hot-dip galvanizing and thus a zinc layer that is flat or even on its outer surface is obtained on the iron-based component, as in FIG. 1C and in Figs. 3A and 3B can be seen. The different layer structure of galvanizing layers obtainable by means of hot-dip galvanizing based on pure zinc layers (Fig. 1A, prior art), aluminum-alloyed or aluminum-containing zinc melts without prior roughening of the surface (Fig. 1 B, prior art) and finally aluminum-alloyed or aluminum-containing according to the invention Zinc layers after the surface has been roughened (FIG. 1 C, invention) can be seen in the relevant figure representations, which will be discussed in detail below.

Within the scope of the present invention, the hot-dip galvanized iron-based component is obtainable in that the iron-based component is first subjected to a treatment to increase and / or adjust the surface roughness on at least one surface and then the iron-based component which has been surface-treated in this way is subjected to hot-dip galvanizing in an aluminum-alloyed or aluminum-containing zinc melt ("Zn / Al melt") is subjected. Only through the combination of these process steps is it possible to obtain such a hot-dip galvanized iron-based component with an increased or individually adjusted zinc layer thickness according to the present invention. For further details, reference can also be made to the above statements on the method according to the invention and on the system according to the invention, which apply accordingly in this regard.

According to the present invention, the hot-dip galvanized iron-based component is provided and / or coated and / or covered with an aluminum-alloyed or aluminum-containing zinc layer. By using 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. in accordance with ISO 1461), but these are significantly higher than zinc layers that are obtained without prior surface roughening.

According to a particular embodiment of the present invention, the aluminum-alloyed or aluminum-containing zinc layer produced or obtained according to the invention has a layer thickness in the range from 3 to 30 μm, in particular in the range from 4 to 28 μm, preferably in the range from 5 to 27 μm, particularly preferred in the range from 6 to 25 pm. According to a further particular embodiment of the present invention, the aluminum-alloyed or aluminum-containing zinc layer, which is obtained in particular by the above-described method according to the invention or the above-described system according to the invention, is a layer thickness which is 1 10 to 300%, in particular 125 to 280%, preferably 130 to 250% of the layer thickness which is obtained after performing process step (b) with omission of the preceding process step (a). This means that a hot-dip galvanizing layer is obtained by the method according to the invention or in the plant according to the invention, which is thicker than a conventionally produced aluminum-alloyed or aluminum-containing hot-dip galvanizing layer without prior surface roughening. Such an increase or adjustment of the zinc layer thickness is only possible at all through the combination of process step (a) and process step (b).

Furthermore, it is provided according to the invention that the aluminum-alloyed or the aluminum-containing zinc layer, which is obtained by the above-described fiction, contemporary method or the relevant system, has a layer thickness which is 0.5 to 15 μm, in particular 1 to 12 μm , preferably by 2 to 10 μm, is greater than the layer thickness which is obtained after carrying out process step (b) with omission of the preceding process step (a). The aluminum-alloyed or aluminum-containing zinc layer thickness obtained according to the invention is thus higher or greater than conventionally produced aluminum-alloy or aluminum-containing zinc layer thicknesses of hot-dip galvanizing without prior surface roughening.

Furthermore, it can be provided according to the invention that the hot-dip galvanized iron-based component has an at least substantially homogeneous and / or uniform and / or continuous aluminum-alloyed and / or aluminum-containing zinc layer, in particular on its upper or outer side. The outer surface of the hot-dip galvanized iron-based component according to the invention is therefore uniform or leveled or leveled in comparison to the roughened surface of the component after carrying out process step (a), ie the roughening resulting from process step (a) is leveled or decayed or leveled. According to the invention, it can therefore preferably be provided that the surface resulting from method step (a) with increased and / or adjusted surface roughness is at least substantially leveled and / or leveled in the context of method step (b), in particular by the surface applied in method step (b) aluminum-alloyed or aluminum-containing zinc layer.

According to the invention, it can be preferred that the iron-based component is provided with an increased or adjusted surface roughness only in certain areas, in particular only on one surface and / or not on all surfaces of the iron-based component. In the context of the present invention, the increase and / or adjustment of the surface roughness can be carried out in an application-specific manner. Examples of this particular embodiment are explained above in connection with the method according to the invention.

In the event that the surface roughness is only increased and / or adjusted in certain areas, in particular only on one surface and / or not on all surfaces of the iron-based component, the invention provides that the aluminum-alloyed or aluminum-containing zinc layer has different thickness areas . In particular, 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. According to the invention, it is therefore possible that only those surfaces are provided with an increased zinc layer thickness which are exposed to increased corrosion or increased stress, for example vehicle chassis components such as axle carriers or tension struts, if they are already highly corrosive due to de-icing salts and mechanically high due to stone impact loaded part are positioned in the area of the exhaust duct and also experience a thermal load. As is known, there are also high loads on loading sills, for example, which are subject to very high levels of abrasion. A deliberately increased zinc layer thickness is also advantageous here. For further details on the iron-based component according to the invention, to avoid unnecessary repetition, reference can be made to the above statements with regard to the method according to the invention and to the system according to the invention, which apply accordingly with regard to the hot-dip galvanized iron-based component according to the invention.

Another object of the present invention - according to a fourth aspect of the present invention - is the use of a hot-dip galvanized (hot-dip galvanized) iron-based component, preferably a steel component, according to the present invention, as described in the relevant use claims.

As described below, the hot-dip galvanized iron-based components according to the invention can be used in many ways, since the thickness of the aluminum-alloyed or aluminum-containing zinc layer can be increased and / or adjusted according to the application and thus customized corrosion protection solutions and / or wear protection solutions can be provided.

According to this aspect of the invention, 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 the production of cars, trucks or commercial vehicles, or for the technical field, especially for the construction industry, mechanical engineering industry or electrical industry.

Typically, the hot-dip galvanized (hot-dip galvanized) iron-based components according to the invention, preferably steel components, as described above, can be used as components, materials or parts for automobile production, in particular for car, truck or commercial vehicle production, or as components, materials or parts for the technical area, in particular for the construction industry, mechanical engineering industry or electrical industry.

According to this aspect of the invention, according to a particular embodiment, the present invention relates 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 component for automobile production, in particular car, truck or commercial vehicle production, or as a component, material or component for the technical field, in particular for the construction industry, mechanical engineering industry or electrical industry.

For further details on the use according to the invention, reference can be made to the above statements with regard to the other aspects of the invention, which also apply in a corresponding manner to the use according to the invention.

Further features, advantages and possible applications of the present invention emerge from the following description of exemplary embodiments with reference to the drawings and the drawings themselves. All of the features described and / or illustrated form the subject matter of the present invention by themselves or in any combination, regardless of their summary in the claims and their interrelationships.

It shows:

1A shows a schematic representation of the layer structure of means

Hot-dip galvanizing available galvanizing layers of iron-based components in pure zinc melts (state of the art),

Fig. 1B is a schematic representation of the layer structure of means

Hot-dip galvanizing in aluminum-alloyed zinc melts available galvanizing layers of iron-based components (state of the art),

1 C shows a schematic representation of the layer structure of galvanizing layers of iron-based components obtainable by means of hot-dip galvanizing in aluminum-alloyed zinc melts according to the invention after the surface has been roughened beforehand (invention),

2 shows a graphic representation of the correlation between the roughness Rz and the zinc layer thickness in the context of the method according to the invention,

Figs. 3A / B microscopic cross-sections of hot-dip galvanized iron-based components obtainable according to the invention, 4 shows a graphic representation of different zinc layer thicknesses of components according to the invention as a function of the galvanizing time (immersion time in the galvanizing bath).

In Fig. 1A the layer structure of a hot-dip galvanized iron-based component is shown schematically by the classic hot-dip galvanizing in a pure zinc melt (i.e. without aluminum components), e.g. B. according to DIN EN ISO 1461, shown (state of the art). During the galvanizing process, as a result of mutual diffusion of the liquid zinc with the (original) surface of the iron-based component 1 a, a coating of variously composed Fe / Zn alloy layers 2 in the form of an Fe / Zn alloy phase is initially formed on the iron-based component 1. The growth of the Fe / Zn alloy phase 2 is a time-dependent process, so that the alloy phase 2 grows with the dwell time. Due to the mutual diffusion, the alloy phase 2 grows partly into the iron-based component 1, whereby the original surface 1 a 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. When the hot-dip galvanized component is pulled out, a layer 3 of zinc - also referred to as the pure zinc phase 3 - which corresponds in its composition to the zinc melt, also remains on the alloy phase 2. Because of the high temperatures involved in hot-dip galvanizing, a relatively brittle layer 2 in the form of an Fe / Zn alloy phase is initially formed on the steel surface, followed by the pure zinc phase 3. In this way, a relatively thick overall galvanizing layer 4 is formed.

1B shows the schematic layer structure of an iron-based component that is hot-dip galvanized in an aluminum-alloyed or aluminum-containing zinc melt (prior art).

During the galvanizing process, a very thin Fe / Al alloy phase 2 ', a so-called barrier layer (approx. 500 nm), is initially formed on the iron-based component T. Due to this Fe / Al alloy phase 2 ', the otherwise usual diffusion processes between iron and zinc melt are inhibited, so that the original surface 1 a' 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. When the hot-dip galvanized component is pulled out, a pure aluminum-alloyed or aluminum-containing zinc layer 3 'remains adhering to the Fe / Al alloy phase 2', the composition of which corresponds to the aluminum-containing or aluminum-alloyed zinc melt. However, the formation of the barrier layer 2 'also limits the thickness of the total galvanizing layer 4' and, overall, a much thinner overall layer 4 'is formed than with hot-dip galvanizing in pure zinc melts, e.g. B. according to DIN EN ISO 1461 (ie the total layer thickness 4 'in Fig. 1B is less than the total layer thickness 4 from Fig. 1A).

1 C shows the schematic layer structure of a hot-dip galvanized iron-based component 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. In the galvanizing process, a very thin Fe / Al alloy phase 2", a so-called barrier layer, is then initially formed on the roughened iron-based component 1 " Fe / Al alloy phase 2 ", the otherwise usual diffusion processes between iron and zinc melt are inhibited, as a result of which the original surface 1a" of the iron-based component is not shifted. The Fe / Al alloy phase 2 "does not grow into the iron-based component 1" and it no Fe / Zn alloy phase is produced. When the hot-dip galvanized component is pulled out, a pure aluminum-alloyed or aluminum-containing zinc layer 3 "remains on the Fe / Al alloy phase 2", which corresponds in its composition to the aluminum-containing or aluminum-alloyed zinc melt and the surface roughness is leveled or leveled Galvanized iron-based components with increased surface roughness are therefore even or even. The formation of the barrier layer limits the thickness of the total galvanized layer 4 ", but due to the previous roughening of the surface, it is higher than with hot-dip galvanized iron-based components without increased surface roughness (as shown in FIG. 1B), so that overall a much thinner total layer than with hot-dip galvanizing in pure zinc melts, e.g. according to DIN EN ISO 1461, but a thicker overall layer than with hot-dip galvanizing in aluminum-alloyed or aluminum-containing zinc melts without prior surface roughening, e.g. in the microZINQ® or Galfan process (ie the total layer thickness 4 ″ is less than the total layer thickness 4 from FIG. 1A, but thicker than the total layer thickness 4 ′ from FIG. 1 B). 2 graphically shows the correlation between the surface roughness of the component and the zinc layer thickness of a component with previously increased surface roughness resulting from hot-dip galvanizing in an aluminum-alloyed or aluminum-containing zinc melt. An increased surface roughness, characterized by the mean roughness depth 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. In particular, the special surface structure can be seen: The roughened surface of the iron-based component (base material) obtainable in process step (a) is completely leveled or leveled in the finished end product by the aluminum-containing or aluminum-alloyed galvanized layer. The microscopic examinations also show that in comparison to aluminum-containing or aluminum-alloyed galvanizing layers produced by means of hot-dip galvanizing without prior roughening, a significantly higher layer thickness of the upper aluminum-containing or aluminum-alloyed hot-dip galvanizing layer is obtained. This can be seen from the measured layer thicknesses, which are shown in Figs. 3A / B are documented. The iron-based components were previously all blasted with compressed air using an angular, particulate stainless steel abrasive (stainless steel abrasive). The iron-based component in FIG. 3A was blasted with a low beam intensity, whereas the iron-based component in FIG. 3B was blasted with a high beam intensity. The component blasted with a low beam intensity (shown in Fig. 3A) has an average hot-dip galvanizing layer thickness in the measured section of 12.44 μm, while the component blasted with a high blasting intensity (shown in Fig. 3B) has an average hot-dip galvanizing layer thickness in the measured section of 32.92 pm. Overall, compared to conventionally produced aluminum-containing or aluminum-alloyed zinc layers (ie hot-dip galvanizing without prior roughening of the surface), there are essentially significantly greater layer thicknesses, in particular after blasting with medium and high intensity. The previously performed surface roughening also remains verifiable or recognizable in the microscopic section. Finally, Fig. 4 shows the course of the zinc growth of the zinc layer thickness through classic hot-dip galvanizing in a pure zinc melt (state of the art) in an aluminum-alloyed or aluminum-containing zinc melt without prior surface roughening (state of the art) and in an aluminum-alloyed or aluminum-containing zinc melt after previous surface roughening ( Invention) as a function of the galvanizing time (immersion time). The upper curve, characterized by squares, represents - depending on the galvanizing time (i.e. immersion time in the galvanizing bath) - the course of the growth of the zinc layer of hot-dip galvanizing layers through classic hot-dip galvanizing in pure zinc melts, z. B. in accordance with DIN EN ISO 1461; the zinc layer grows very strongly at the beginning of the hot-dip galvanizing process, with the duration of the immersion the growth rate decreases, but the zinc layer thickness continues to grow. The bottom curve, marked by crosses, represents - depending on the galvanizing time (ie immersion time in the galvanizing bath) - the course of the growth of the zinc layer of hot-dip galvanizing layers through 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 any further with continuous immersion. The middle curve, characterized by diamonds, represents - depending on 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 through prior surface roughening and subsequent hot-dip galvanizing in aluminum-alloyed or aluminum-containing zinc layers; the zinc layer only reaches its maximum thickness after approx. 2 minutes, and the zinc layer does not increase any further with continuous immersion. Overall, the illustration in Fig. 4 makes it clear that 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 a significantly thinner zinc layer has zinc layers as such, which are produced by hot-dip galvanizing in a pure zinc melt. Further refinements, modifications and variations of the present invention can be readily recognized and implemented by the person skilled in the art when reading the description, without leaving the scope of the present invention.

The present invention is illustrated with the aid of the following exemplary embodiments, which, however, are in no way intended to restrict the present invention, but rather are intended to explain exemplary and non-limiting modes of implementation and configurations.

EXAMPLES:

Input materials:

- alkaline cleaner: Henkel AG & Co. KGaA, Düsseldorf / DE, (based on phosphate with potassium hydroxide)

- Degreasing booster: Henkel AG & Co. KGaA, Düsseldorf / DE, (nonionic and anionic surfactants)

- Pickling degreaser: Lutter Galvanotechnik GmbH, Bischberg / DE, (anionic wetting agents, non-ionic emulsifiers, solubilizers, inhibitors)

- Inhibitor: Lutter Galvanotechnik GmbH, Bischberg / DE, (anion-active and non-ionic compounds)

- Wetting agent: Lutter Galvanotechnik GmbH, Bischberg / DE, (anion-active and non-ionic surfactants)

- Amacast ^® 10: round stainless steel abrasive, grain size 0.09 - 0.2 mm

(Ervin Germany GmbH, Berlin / DE)

- Amacast ^® 20: round stainless steel abrasive, grain size 0.09 - 0.3 mm

(Ervin Germany GmbH, Berlin / DE)

- Amagrit ^® 10: angular stainless steel abrasive, grain size 0.09 - 0.2 mm

(Ervin Germany GmbH, Berlin / DE)

- Amagrit ^® 20: angular stainless steel abrasive, grain size 0.09 - 0.3 mm

(Ervin Germany GmbH, Berlin / DE)

- Amagrit ^® 30: angular stainless steel abrasive, grain size 0.09 - 0.6 mm

(Ervin Germany GmbH, Berlin / DE)

Hot-dip galvanizing by means of Zn / Al melt of steel surfaces with increased

Surface roughness

As part of an extensive series of tests, the influence of a specifically set surface roughness on the zinc layer thickness when using a zinc melt with an Al content of> 0.1% is investigated.

Zinc alloy used: Zn5% AI (microZINQ ^® )

First, the steel surfaces are treated by mechanical blasting with a two-turbine continuous blasting system with the blasting agents listed below and then the resulting roughness is measured in accordance with DIN EN ISO 4288. The results are shown in the table below:

This is followed by the hot-dip galvanizing process with the following process steps:

In relation to the resulting zinc layer thickness, the following results are achieved:

- Increasing the blasting pressure basically also leads to an increased zinc layer thickness.

- When using the spherical, round grit, a lower one is used

Increase in the zinc layer thickness than when using the angular blasting material.

- The surface roughness is linearly proportional to the resulting zinc layer thickness (see also Fig. 2).

The microscopic analysis of the zinc layers produced reveals that the zinc melt largely levels the defined surface roughness so that a continuous and uniform surface is present after hot-dip galvanizing (cf. FIGS. 3A and 3B). Due to the roughness of the substrate, a zinc layer forms, which has local areas with slightly greater or lesser layer thicknesses, but the average layer thickness is overall higher than with untreated (i.e. not roughened) surfaces and the outer surface is flat overall.

From the point of view of corrosion protection, the average zinc layer thickness is to be used, since, based on the cathodic effect of the zinc layer, an overarching protective effect of the slightly thinner areas is given by the areas with a higher layer thickness.

Overall, by setting the blasting parameters, the surface roughness of the material to be galvanized can be set in a defined manner and thus a zinc layer with an increased zinc layer thickness can be applied.

Further attempts at hot-dip galvanizing using "Zn / Al melt" by

Steel surfaces with increased surface roughness

The substrates are first subjected to a mechanical surface treatment and then a hot-dip galvanizing process, the overall process comprising the following steps:

• sandblasting

• Degreasing

• Do the washing up

· Pickling

• Do the washing up

• Flux

• Dry

• Galvanizing

· To seal

Different substrates, namely sheet metal material and components are examined. For this purpose, the substrates are blasted with the help of a two-turbine continuous blasting system at three different intensities, but with the same blasting material:

1 . Low beam intensity: A4 / 10 minutes / 8V

2. Average beam intensity: A2 / 20 seconds / 5V

3. High beam intensity: A2 / 20 seconds / 8V Furthermore, 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 individual measured values determined, their mean ("x") and the respective standard deviations ("SD") are shown in the following table:

In the next step, all substrates (i.e. both the blasted and the reference or comparisons) go through the hot-dip galvanizing process. The layer thickness is then measured on each substrate in accordance with DIN EN ISO 2178. For this purpose, measurements are made at 6 measuring points on each sheet and at 8 measuring points on each of the components. A total of 5 series of measurements are recorded. The individual measured values determined, their mean ("x") and the respective standard deviations ("SD") are shown in the following tables:

Layer thicknesses - sheet metal

Low beam intensity

Medium beam intensity

High beam intensity

Without rays (reference or comparison)

Layer thickness - component

Low beam intensity

Medium beam intensity

High beam intensity

Without rays

The choice of beam intensity determines the surface roughness of the substrate, which directly influences the resulting zinc layer thickness. As the surface roughness increases, so does the zinc layer thickness. The results are summarized again in the following table:

The results confirm the relationships found in the first series of tests for real sheet metal as well as for real components.

Increase in the anti-corrosion effect

The corrosion protection effect of the zinc layers is checked by means of two short-term corrosion tests:

- Neutral salt spray test according to DIN EN ISO 9227

- Climate change test according to VDA 233-102

The neutral salt spray test does not represent a realistic corrosion exposure and therefore no determination of the absolute duration of protection of zinc coatings can be derived; however, this test can be used for a meaningful relative comparison of coatings and coatings.

For the neutral salt spray test, the coated substrate is placed in a test chamber and permanently sprayed with 5% sodium chloride solution. The time it takes for corrosion to appear on the substrate is recorded and used as an evaluation criterion.

Experience shows that substrates without surface treatment with a 6 μm thick Zn5AI layer achieve a service life of more than 720 hours in the neutral salt spray test until the occurrence of base material corrosion (red rust). If the zinc layer thickness is increased by 100% to 12 gm, a corresponding increase in the service life in the salt spray test to between 1,000 and 1,200 hours is achieved until the base material corrosion occurs. A further increase in the zinc layer thickness leads to a further increase in the corrosion protection effect. Tests have thus shown that the service life is significantly improved in the case of the substrates coated according to the invention.

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 various load intervals, which result in a total weekly cycle, which in turn is run through until signs of corrosion appear on the test body.

Experience shows that substrates without surface treatment with a 13 μm thick Zn5Al layer and subsequent sealing achieve 4 to 5 cycles without the occurrence of base material corrosion. Tests have shown that the number of cycles without the occurrence of base material corrosion increases to over 6 cycles in the case of the substrates coated according to the invention.

Tests for mechanical resistance

Zinc layers produced in the hot-dip galvanizing process are characterized by high resistance to mechanical influences due to the metallurgical connection between the zinc layer and the ferrous substrate. It is known, however, that the greater the thickness, the greater the risk that the zinc layer will flake off under load and / or have cracks. Various methods are used to test the mechanical resistance of the zinc layers produced by the method according to the invention.

In a first test, a technological bending test (folding test) according to DIN 501 11 is carried out on sample sheets. For this purpose, the sheets are mechanically pretreated with different blasting parameters and then galvanized, resulting in different zinc layer thicknesses according to the following overview.

The sheets are then checked and reshaped.

The result shows that a deformation of up to 180 ° is possible with all sample sheets without cracks in the zinc layer or flaking of the zinc layer.

In a further test, further sample sheets galvanized according to the invention are subjected to a tear-off test based on DIN EN 24624. A test stamp is glued to the coating and mechanically pulled off perpendicular to the substrate surface until the zinc layer fails. One measurement is made on the front and one on the back of the sheet, then the mean value is calculated. The parameters and the results achieved are shown below:

The tear-off stresses are within the scope of the usual scatter for this test at a consistently high level. The mechanical resistance is also measured in accordance with EN 438-2. For substrates without surface treatment with a homogeneous Zn5Al layer, the abrasion value is 0.01 pm / cycle. Tests have shown that the mechanical resistance also improves in the case of the substrates coated according to the invention.

With increasing zinc layer thickness, the number of bearable abrasion cycles increases in the same proportion. This is synonymous with an increase in the resistance of the zinc layer to mechanical friction.

For further testing, a stone chip test is carried out in accordance with DIN EN ISO 20567-1, in which a sample provided with a coating or metallic coating is loaded by many small, sharp-edged impacts accelerated by compressed air. The degree of damage to the coating (penetration of the layer to the base material) is assessed. 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 high ductility of the zinc layer absorbs the energy of the grains that hit it very well. In the case of conventional pure zinc layers with On the other hand, brittle phases according to the prior art (e.g. very pronounced in a high-temperature galvanized layer) lead to local flaking under stone chipping.

With a Zn / Al layer with a thickness of 10 μm, a characteristic value of 1.5 is achieved in the stone impact test, which corresponds to a damaged area of 2.5%. When the zinc layer thickness is increased to 15 μm, the proportion of penetrating test specimens is significantly reduced and a characteristic value of 0.5 - 1.0 (= maximum 0.2% or 1.0% damaged area) is achieved. At higher layer thicknesses of the zinc layers produced according to the invention in the range from 20 μm to 30 μm, the values are improved even further.

In sum, all tests show that the higher thicknesses of the Zn / Al layer produced by the use of the method according to the invention do not show any negative effects with regard to mechanical resistance, but on the contrary show an improvement in performance.

Further attempts at hot-dip galvanizing using "Zn / Al melt" by

Steel surfaces with increased surface roughness

The components are first subjected to a mechanical surface treatment (surface roughening) and then a hot-dip galvanizing process, the overall process comprising the following steps:

• sandblasting

• Degreasing

• Do the washing up

• Pickling

• Do the washing up

• Flux

• Dry

• Galvanizing

• To seal

First, the components are blasted with an angular blasting material (stainless steel) using a two-turbine continuous blasting system with medium blasting intensity.

Furthermore, reference substrates (comparison components) are passed through the hot-dip galvanizing process without mechanical surface treatment.

The recording of the characteristic values Ra, Rz and Rmax to describe the surface roughness achieved is carried out in accordance with DIN EN ISO 4288.

In the next step, 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.

The average characteristic values of the surface roughness and the layer thickness of the components according to the invention are listed below:

Ra: 9.8 pm

Rz: 60.4 pm

- Rmax: 77.1 pm

- Layer thickness: 24.2 pm

- Layer thickness reference: 1 1, 7 pm

The comparison components (ie without surface pretreatment), on the other hand, only have an average layer thickness of 11.7 μm. Increase in the anti-corrosion effect

- Neutral salt spray test according to DIN EN ISO 9227

- Climate change test according to VDA 233-102

Both the service life in the salt spray test and the number of cycles without the occurrence of base material corrosion in the alternating climate test improve significantly in the hot-dip galvanized components according to the invention compared to the hot-dip galvanized components without a roughened surface.

Measurement of mechanical resistance and adhesive strength

The mechanical resistance is measured in accordance with EN 438-2. In the case of the hot-dip galvanized components according to the invention, the number of bearable abrasion cycles is significantly increased in relation to the hot-dip galvanized reference components. This is synonymous with an increase in the resistance of the zinc layer to mechanical friction.

In the hot-dip galvanized components according to the invention, the adhesive strength, measured in accordance with DIN EN 24624, is unchanged compared to components without surface treatment. The load-bearing capacity as a result of shock or sudden effects also remains unchanged by the increase in the zinc layer thickness according to the invention.

For the test, a stone impact test is carried out in accordance with DIN EN ISO 20567-1, in which a hot-dip galvanized component is loaded by many small, sharp-edged impacts accelerated by compressed air. The degree of damage to the galvanized layer is significantly reduced in the hot-dip galvanized components according to the invention compared to hot-dip galvanized components without surface treatment.

REFERENCE SIGNS LIST: iron-based component (steel component)

'' iron-based component (steel component)

"iron-based component (steel component)

a original surface of the iron-based component (steel component) a 'original surface of the iron-based component (steel component) a "original surface of the roughened iron-based component (steel component)

Fe / Zn alloy phase

'' Fe / Al alloy phase (thin barrier layer / barrier layer)

"Fe / Al alloy phase (thin barrier layer / barrier layer)

pure zinc phase (pure zinc phase)

'' pure aluminum alloyed or aluminum containing zinc phase

"pure aluminum alloyed or aluminum-containing zinc phase

Galvanized layer (total galvanized layer)

'' Galvanized layer (total galvanized layer)

"Galvanized layer (total galvanized layer)

Claims

Patent claims:

1 . A method for producing an aluminum-alloyed and / or aluminum-containing zinc layer, in particular with an increased layer thickness, on an iron-based component, preferably a steel component, by means of hot-dip galvanizing (hot-dip galvanizing), in particular a method for increasing and / or setting, preferably increasing, the layer thickness of an aluminum alloy produced by hot-dip galvanizing and / or aluminum-containing zinc layer on an iron-based component,

(b) Hot-dip galvanizing of the iron-based component in an aluminum-alloyed and / or aluminum-containing zinc melt ("Zn / Al melt").

2. The method according to claim 1,

the increase and / or adjustment of the surface roughness in

Method step (a) is carried out on at least one surface of the iron-based component, preferably on several surfaces of the iron-based component.

3. The method according to claim 1 or claim 2,

the increase and / or adjustment of the surface roughness in

Method step (a) is carried out on the entire iron-based component, in particular on all surfaces of the iron-based component.

4. The method according to claim 1 or claim 2,

the increase and / or adjustment of the surface roughness in

Method step (a) is carried out only in regions, in particular only on one surface and / or not on all surfaces of the iron-based component. 5. The method according to any one of the preceding claims,

wherein the increase and / or adjustment of the surface roughness in method step (a) takes place by mechanical treatment, in particular by means of abrasion and / or by means of an abrasive method, preferably by means of compressed air blasting with solid blasting material ("sandblasting");

in particular wherein the blasting material (blasting media) used in process step (a) 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 ball blasting material; and or

in particular wherein the blasting material used in process step (a) has a round, spherical, angular or cylindrical grain shape, preferably an angular grain shape; and or

In particular, the blasting material used in process step (a) has an absolute grain size in the range from 30 to 5,000 mti, in particular in the range from 50 to 3,000 mti, preferably in the range from 60 to 1,500 mΐti, particularly preferably in the range from 70 to 1,000 mΐti , very particularly preferably in the range from 75 to 800 mΐti; and or

in particular where the blasting material used in process step (a) 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 of 250 up to 1,500 HV; and or

in particular where 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 in the range from 3.5 to 6,

5 Mohs; and or in particular wherein the blasting material 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, on the at least one surface of the iron-based component is allowed to act; and or

in particular wherein the blasting material is 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; and or

in particular wherein the blasting material is allowed to act on the at least one surface of the iron-based component with a blasting pressure of a maximum of 15 bar, in particular a maximum of 11 bar, preferably a maximum of 8 bar, particularly preferably a maximum of 5 bar; and or

in particular wherein the blasting material is allowed to act on the at least one surface of the iron-based component for a duration of 10 seconds to 30 minutes, in particular 15 seconds to 20 minutes, preferably 20 seconds to 10 minutes; and or

in particular wherein the blasting material is allowed to act on the at least one surface of the iron-based component for a duration of up to 30 minutes, in particular up to 20 minutes, preferably up to 10 minutes; and or

in particular wherein the blasting material is allowed to act on the at least one surface of the iron-based component for a duration of at least 10 seconds, in particular at least 15 seconds, preferably at least 20 seconds.

6. The method according to any one of the preceding claims,

wherein 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 roughness value Ra, in particular according to DIN EN ISO 4288: 1998-04, of at least 0.3 μm, in particular at least 0.6 pm, preferably at least 0.7 pm, particularly preferably at least 0.8 pm; and or 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 mean roughness value Ra, in particular according to DIN EN ISO 4288: 1998-04, in the range from 0.3 to 20 μm, in particular in the range from 0.6 to 15 gm, preferably in the range from 0.7 to 13 gm, particularly preferably in the range from 0.8 to 12 gm; and or

the increase and / or adjustment of the surface roughness in

Process step (a) is carried out in such a way that the in

Process step (a) the treated surface has an average roughness depth Rz, in particular according to DIN EN ISO 4288: 1998-04, of at least 2 gm, in particular at least 3 gm, preferably at least 4 gm; and or

the increase and / or adjustment of the surface roughness in

Process step (a) is carried out in such a way that the in

Process step (a) the treated surface has an average roughness depth Rz, in particular according to DIN EN ISO 4288: 1998-04, in the range from 2 to 75 gm, in particular in the range from 3 to 70 gm, preferably in the range from 3 to 65 gm; and or

the increase and / or adjustment of the surface roughness in

Process step (a) is carried out in such a way that the in

Process step (a) the treated surface has a maximum roughness depth Rmax, in particular according to DIN EN ISO 4288: 1998-04, of at least 3 μm, in particular at least 4 μm, preferably at least 5 μm; and or

the increase and / or adjustment of the surface roughness in

Process step (a) is carried out in such a way that the in

Process step (a) treated surface has a maximum roughness depth Rmax, in particular according to DIN EN ISO 4288: 1998-04, in the range from 3 to 95 μm, in particular in the range from 4 to 90 μm, preferably in the range from 5 to 85 μm.

7. The method according to any one of the preceding claims,

whereby the increase and / or adjustment of the surface roughness in process step (a) is carried out 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 process step (a) by 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%; and or

wherein the increase and / or adjustment of the surface roughness in process step (a) is carried out in such a way that the mean roughness depth Rz, in particular according to DIN EN ISO 4288: 1998-04, of the surface treated in process step (a) by 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%; and or

wherein the increase and / or adjustment of the surface roughness in process step (a) is carried out in such a way that the maximum roughness depth Rmax, in particular according to DIN EN ISO 4288: 1998-04, of the surface treated in process step (a) by 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%.

8. The method according to any one of the preceding claims,

wherein in method step (b) the iron-based component is provided and / or coated and / or coated with an aluminum-alloyed and / or aluminum-containing zinc layer and / or wherein, after performing the method according to one of the preceding claims, a zinc layer provided with an aluminum-alloyed and / or aluminum-containing zinc layer and / or coated and / or coated iron-based component is obtained; in particular where the aluminum-alloyed and / or aluminum-containing

Zinc layer, which is obtained by the method according to one of the preceding claims, a layer thickness in the range from 3 to 30 pm, in particular in the range from 4 to 28 pm, preferably in the range from 5 to 27 pm, particularly preferably in the range from 6 to 25 pm, has; and / or in particular where the aluminum-alloyed and / or aluminum-containing

Zinc layer, which is obtained by the method according to one of the preceding claims, has a layer thickness which is 1 10 to 300%, in particular 125 to 280%, preferably 130 to 250%, of that layer thickness which, after performing method step (b) below Omission of the preceding process step (a) is obtained; and or

in particular where the aluminum-alloyed and / or aluminum-containing

Zinc layer, which is obtained by the method according to one of the preceding claims, has a layer thickness which is 0.5 to 15 μm, in particular 1 to 12 μm, preferably 2 to 10 μm, greater than the layer thickness which is greater after implementation the process step (b) is obtained with the omission of the preceding process step (a); and the

in particular wherein the hot-dip galvanized iron-based component obtained by method steps (a) and (b) has an at least substantially homogeneous and / or uniform and / or continuous aluminum-alloyed and / or aluminum-containing zinc layer, in particular on its top or outside; and or

In particular, the surface with increased surface roughness resulting in process step (a) is at least substantially leveled and / or leveled in process step (b), in particular by the aluminum-alloyed and / or aluminum-containing zinc layer applied in process step (b).

9. The method according to any one of the preceding claims,

in the event that the increase and / or adjustment of the surface roughness in process step (a) is only carried out in certain areas, in particular only on one surface and / or not on all surfaces of the iron-based component, the aluminum alloy obtained in process step (b) and / or aluminum-containing zinc layer has different thickness ranges, in particular the layer thickness of the aluminum-alloyed and / or aluminum-containing zinc layer in the area of the surface (s) or surface areas previously treated in method step (a) compared to the layer thickness in the area of the untreated surface (s) or Surface areas is increased.

10. The method according to any one of the preceding claims,

the aluminum-alloyed and / or aluminum-containing zinc melt used in process step (b), based on the zinc melt, preferably at least 0.1% by weight, in particular at least 0.15% by weight, preferably at least 0.2% by weight Contains at least 0.5% by weight, particularly preferably at least 1% by weight, very particularly preferably at least 2% by weight, aluminum; and or

wherein the aluminum-alloyed and / or aluminum-containing zinc melt used in process step (b), based on the zinc melt, 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, contains aluminum; and or

wherein the aluminum-alloyed and / or aluminum-containing zinc melt used in process step (b), based on the zinc melt, 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% by weight to 12.5% by weight, very particularly preferably in the range from 2% by weight to 10% by weight.

1 1. Method according to one of the preceding claims,

wherein the aluminum-alloyed and / 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 from 390 to 680 ° C, even more preferably in the range from 395 to 675 ° C; and or

wherein in method step (b) the iron-based component is dipped into the aluminum-alloyed and / or aluminum-containing zinc melt, in particular is immersed and moved therein, in particular for a period of time which is sufficient to ensure effective hot-dip galvanizing (hot-dip galvanizing), in particular for a time in the range from 0.0001 to 60 minutes, preferably in the range from 0.001 to 45 minutes, preferably in the range from 0.01 to 30 minutes, even more preferably in the range from 0.1 to 15 minutes; and or

wherein the aluminum-alloyed and / or aluminum-containing zinc melt used in method step (b) is contacted and / or flushed or passed through with at least one inert gas, in particular nitrogen.

12. The method according to any one of the preceding claims,

wherein prior to the hot-dip galvanizing in process step (b), a pretreatment of the iron-based component obtained in process step (a) is carried out; in particular wherein the pretreatment comprises at least one flux treatment (fluxing).

13. Plant for producing an aluminum-alloyed and / or aluminum-containing zinc layer, in particular with increased layer thickness, on an iron-based component, preferably steel component, by means of hot-dip galvanizing (hot-dip galvanizing), in particular plant for increasing and / or setting, preferably increasing, the layer thickness of a hot-dip galvanizing produced aluminum-alloyed and / or aluminum-containing zinc layer on an iron-based component, preferably system for carrying out a method according to one of the preceding claims, the system comprising the following devices in the order listed below:

14. Plant according to claim 13,

wherein 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 media), or is designed as such.

15. Plant according to claim 13 or claim 14,

wherein 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; and or

wherein the blasting material used in device (A) and / or located 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 ball blasting material; and or

wherein the blasting material used in device (A) and / or located in the receptacle has a round, spherical, angular or cylindrical grain shape, preferably an angular grain shape; and or wherein the blasting material used in device (A) and / or located in the receptacle has an absolute grain size in the range from 30 to 5,000 mti, in particular in the range from 50 to 3,000 mΐti, preferably in the range from 60 to 1,500 mΐti, particularly preferably in the range of 70 to 1,000 mΐti, very particularly preferably in the range from 75 to 800 mΐti; and or

wherein 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 1,500 HV; and or

wherein the blasting material used in device (A) and / or located in the receptacle 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 of 3 to 7 Mohs, preferably in the range from 3.5 to 6.5 Mohs.

16. System according to one of the preceding claims,

wherein 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 such that the blasting material 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, is discharged and / or is allowed to act on the at least one surface of the iron-based component; and or

wherein 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 such that the blasting material is discharged with a blasting pressure of at least 1 bar, in particular at least 2 bar, preferably at least 3 bar, and / or onto the at least one surface the iron-based component is allowed to act; and or wherein 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 such that the blasting material with a blasting pressure of a maximum of 15 bar, in particular a maximum of 1 1 bar, preferably a maximum of 8 bar, particularly preferably a maximum of 5 bar, is discharged and / or on which at least one surface of the iron-based component is allowed to act.

17. Plant according to one of the preceding claims,

wherein the hot-dip galvanizing device (B) comprises a galvanizing bath containing an aluminum-alloyed and / or aluminum-containing zinc melt, in particular as defined in one of the preceding claims; and or

wherein the hot-dip galvanizing device (B) is designed for providing and / or coating and / or covering the iron-based component with an aluminum-alloyed and / or aluminum-containing zinc layer.

18. Hot-dip galvanized (hot-dip galvanized) iron-based component, preferably steel component, obtainable by a method according to one of the preceding claims or obtainable in a system according to one of the preceding claims.

19. Hot-dip galvanized (hot-dip galvanized) iron-based component, preferably steel component, in particular hot-dip galvanized iron-based component according to claim 18,

wherein the hot-dip galvanized iron-based component is obtainable by first applying the iron-based component to at least one surface of a treatment to increase and / or adjust the surface roughness and then the surface-treated iron-based component of hot-dip galvanizing in an aluminum-alloyed and / or aluminum-containing zinc melt ("Zn / Al-melt ").

20. Hot-dip galvanized iron-based component according to claim 18 or claim 19, wherein the hot-dip galvanized iron-based component is provided and / or coated and / or coated with an aluminum-alloyed and / or aluminum-containing zinc layer;

in particular wherein the aluminum-alloyed and / or aluminum-containing zinc layer has a layer thickness in the range from 3 to 30 μm, in particular in the range from 4 to 28 μm, preferably in the range from 5 to 27 μm, particularly preferably in the range from 6 to 25 μm; and or

in particular wherein the aluminum-alloyed and / or aluminum-containing zinc layer, which is obtained in particular by the method or in the system according to one of the preceding claims, has a layer thickness which is 1 10 to 300%, in particular 125 to 280%, preferably 130 to 250% , is that layer thickness which is obtained after performing process step (b) omitting the preceding process step (a); and or

in particular wherein the aluminum-alloyed and / or aluminum-containing zinc layer, which is obtained in particular by the method according to one of the preceding claims, has a layer thickness which is around 0.5 to 15 pm, in particular around 1 to 12 pm, preferably around 2 to 10 pm, is greater than that layer thickness which is obtained after performing process step (b) omitting the preceding process step (a); and the

in particular wherein the hot-dip galvanized iron-based component has an at least substantially homogeneous and / or uniform and / or continuous aluminum-alloyed and / or aluminum-containing zinc layer, in particular on its top or outside; and or

21. Hot-dip galvanized iron-based component according to one of the preceding claims,

the iron-based component being provided with an increased and / or adjusted surface roughness only in certain areas, in particular only on one surface and / or not on all surfaces of the iron-based component; and or

wherein the aluminum-alloyed and / or aluminum-containing zinc layer of the iron-based component has different thickness ranges in the event that the increase and / or adjustment of the surface roughness has only occurred in certain areas, in particular only on one surface and / or not on all surfaces of the iron-based component, In particular, the layer thickness of the aluminum-alloyed and / 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.

22. Use of a hot-dip galvanized (hot-dip galvanized) iron-based

Component, preferably steel component, according to one of the preceding

Claims for automobile production, in particular the manufacture of cars, trucks or commercial vehicles, or for the technical sector, in particular for the construction industry, mechanical engineering industry or electrical industry.

23. Use of a hot-dip galvanized (hot-dip galvanized) iron-based

Component, preferably steel component, according to one of the preceding

Demands as a component, material or component for automobile production, in particular passenger car, truck or commercial vehicle production.

24. Use of a hot-dip galvanized (hot-dip galvanized) iron-based

Component, preferably steel component, according to one of the preceding

Claims as a component, material or component for the technical

Area, especially for the construction industry, mechanical engineering industry or electrical industry.