DE102021111089A1 - Process, system and use of these in batch galvanizing - Google Patents

Abstract

The present invention relates to a method and a system for galvanizing components, in particular metallic components in discontinuous galvanizing, with at least one treatment of the component in a flux/wetting bath, flux bath, before zinc is applied to the surface of the components in a zinc bath and/or wetting bath, in which bismuth is deposited on the surface of the at least one component. Furthermore, the invention also relates to the use of such a method and the components produced with such a method.

Description

Summary of the Invention

The present invention relates to a method, a system and their use for galvanizing components, in particular metallic components.

The process and the system are used in particular in batch galvanizing, in which individual parts are treated in baths, in the so-called dipping process, and these undergo a surface treatment. This is referred to as discontinuous batch galvanizing or hot-dip galvanizing or hot-dip galvanizing. In contrast to this is strip galvanizing, which includes a continuous galvanizing process (DIN EN 10143 and DIN EN 10346).

In discontinuous piece galvanizing, which is regulated according to the DIN EN ISO 1461 standard, corrosion protection based on the applied layer thickness is generated with the help of a molten bath of ≥ 98.0% by weight zinc (Zn) and other accompanying elements. In some cases, this layer thickness can average several 100 µm (microns) thick. Known methods of batch galvanizing include chemical pretreatment in a degreasing bath, pickling bath and flux bath with intermediate rinsing baths, with the component surfaces being cleaned and/or pretreated in the individual baths to remove foreign substances. The intermediate rinsing baths have the task of avoiding or reducing the carryover of chemicals from the respective treatment bath into the next process step. After air drying or treatment in a drying oven (80°C to 120°C), a zinc surface is then applied, in which the component is immersed in a zinc bath with liquid zinc (≥ 98.0% by weight zinc (Zn); temperature from 440 to 460°C). In the subsequent outdoor weathering, the zinc surface applied to the component reacts with the components of the ambient air and forms a protective top layer, the zinc carbonate layer (ZnCO ₃ ).

In contrast to discontinuous piece galvanizing, the component in the continuous galvanizing process has a lower zinc layer thickness of around 7 µm to 25 µm, which is due to other processing techniques and as a result of the high throughput speed (up to 200 m/min) of the strip and thus a short reaction time between steel strip and molten zinc result. As a result, different protection periods are formed between the two processes of continuous and discontinuous galvanizing due to the zinc layers.

Another difference between the continuous and the discontinuous galvanizing process is the composition of the zinc bath melt due to the responsible standardization. While the zinc content in the bath melt must be ≥ 98% by weight in discontinuous hot-dip galvanizing, this is not the case in the continuous galvanizing process. For example, alloys with a higher proportion of aluminum (Al) have been developed in the continuous galvanizing process over the last few decades, which lead to thinner, more ductile and more corrosion-resistant zinc layers due to a different phase formation and layer structure. This includes in particular the zinc-aluminum alloy, ZnAl5 alloy (Zn = 95% by weight, Al = 5% by weight), which is known under the trade name "Galfan".

In the discontinuous hot-dip galvanizing process, referred to below as hot-dip galvanizing for the sake of simplicity, different alloy layers or alloy phases (Γ-, δ1-, ζ-, η-phase) are formed starting from the substrate of the component. Using the example of a steel component, these are layers or phases of zinc (Zn) and iron (Fe), such as that 1 a) can be removed. The iron content in the individual phases decreases in the direction of the zinc layer on the component surface (Γ phase = 21-28% Fe, δ1 phase = 7-11.5% Fe, ζ phase = 6-6.2% Fe, η-phase <0.08% Fe). Depending on the compactness of the δ1 phase, which acts as a diffusion barrier, the ζ phase above it can form extremely and grow through to the surface; an η-phase (pure zinc layer) is then hardly or not at all present. The layer formation, especially the δ1 and ζ phase, depends on the steel composition and develops differently depending on the Si and P content of the base material. Layer thicknesses > 150 µm can be produced. Furthermore, the formation of the zinc layer during hot-dip galvanizing depends on the immersion time or residence time within the zinc bath. The thickness of the layer increases with increasing immersion time.

In the continuous galvanizing process, an almost impurity-free component surface is necessary in order to coat the component with a zinc (Zn) - aluminum (AI) alloy, preferably ZnAI5, since aluminum has many substances on the component, as well as in the baths or can react with the intermediate products, as well as increasing the surface tension of the zinc melt. The layer obtained from this usually has a thickness of 7-25 µm (microns). The one formed by the continuous galvanizing process Zinc layer and surface has a different composition than that of hot-dip galvanizing due to the higher aluminum content and its mode of action in the layer structure. In particular, an iron-aluminum (FeAl) boundary layer forms directly on the steel base of the component, which prevents any further layer thickness growth. Above this boundary layer are eutectic structures made up of the components aluminum and zinc, mostly in a ratio of 5% aluminum to 95% zinc, whereby cells with a higher zinc content also form, such as the 1 b) can be found, regardless of the component, its steel composition and the residence time in the ZnAI5 melt. In contrast to hot-dip galvanizing, the aluminum present in the zinc layer acts as a catalyst, which forms the corresponding passive layers immediately after the galvanizing process. In addition, the zinc layer is not as brittle compared to the hot-dip galvanizing process and also allows for reshaping after galvanizing. The zinc layers produced by thin-layer galvanizing are therefore thinner, more ductile, more stable and more corrosion-resistant than those of hot-dip galvanizing. Due to the fact that the ZnAl5 alloy (melting point at 382 °C, working temperature: 410 °C to 430 °C) uses a lower melt temperature and a higher drying oven temperature (200-250 °C) than hot-dip galvanizing , the temperature difference between the component and the melt is reduced, which means that the component and the surface are not subjected to as much stress and the risk of warping and cracking due to the release of internal stresses is reduced.

A transfer of the procedures and compositions that are used within the continuous galvanizing process on a strip, in which a two-dimensional, precisely defined component is galvanized, to a discontinuous galvanizing process in which different three-dimensional components, different geometries, materials and/or processing states are galvanized, is in not been successful in practice.

Due to increasing visual demands as well as the desire for more functional, thinner and more corrosion-resistant zinc layers and/or increasingly difficult general conditions, such as more complex and difficult-to-remove input materials on the component surface, changes in steel production and steel composition, reduction of limit values, restrictions in the input materials and/or Environmental protection, improved zinc surfaces as well as methods and/or devices that can generate such surfaces are needed.

Hot-dip galvanizing processes are also known which use a zinc/aluminum bath, as described above for the continuous galvanizing process, for example in WO 2002/042512 A1 described, but such a method does not seem to reliably generate the required surface quality that can be used for all applications, since the galvanized surface structure with increasing complexity of the processing condition and geometry of the components due to the poorer wetting behavior causes disturbances in the layer structure, the galvanizing layer and the has galvanizing quality.

The object of the present invention is therefore to provide a method and a system which reduces or even solves the disadvantages of the prior art, in particular by subjecting the component surface to a preliminary treatment which enables a thin layer of zinc to be applied, preferably at Use of 5% by weight aluminum (AI) in the molten pool.

The present invention therefore relates to a method for galvanizing components, in particular metallic components in discontinuous galvanizing, in which prior to application of zinc to the surface of the components in a zinc bath, preferably a zinc-aluminum alloy such as ZnAl5 alloy, at least one The component is treated in a flux bath and/or wetting bath, in which bismuth is deposited on the surface of the at least one component.

In one aspect, the at least one component is immersed in the flux/wetting bath which has the following flux/wetting agent composition: (a) 80% by weight to 98% by weight ZnCl ₂ (zinc chloride), preferably 88% by weight ± 2 wt% ZnCl ₂ (zinc chloride); (b) 1% to 19% by weight NH ₄ Cl (ammonium chloride), preferably 12% ± 2% by weight NH ₄ Cl (ammonium chloride); and (c) 0.1 g/l to 4 g/l Bi ³⁺ , preferably 1 g/l ± 0.5 g/l Bi ³⁺ (bismuth ions), where the weight data are based on the flux/wetting agent and the The sum of all components of the composition is 100% by weight, the flow agent/wetting bath also having a pH of from pH 0.5 to pH 2.5, preferably ≦2.0, particularly preferably at pH≦1. In a preferred embodiment, the fluxing agent/wetting agent of the fluxing agent/wetting bath is present in an aqueous solution and the total salt content within the bath is in the range from 100 to 650 g/l, preferably in the range from 250 to 450 g/l.

1. a) Vorflux und Hauptflux, wobei das Vorflux ein Benetzungsbad umfasst, dass eine Prozesslösung umfassend Bismut in Form von Bi³⁺ im Bereich von 0,1 g/l bis 10 g/l und einen pH-Wert von ≤ 2,5, vorzugsweise von pH ≤ 2,0, besonders bevorzugt von pH ≤ 1,0 aufweist und eine Benetzung der Bauteiloberfläche mit Bismut (Bi) bewirkt; und wobei das Hauptflux ZnCl₂ (Zinkchlorid) im Bereich von 80 Gew.% bis 98 Gew.%, vorzugsweise 88 Gew.% ± 2 Gew.% umfasst, und NH₄Cl (Ammoniumchlorid) im Bereich von 1 Gew.% bis 19 Gew.%, vorzugsweise 12 Gew.% ± 2 Gew.%, wobei die Gewichtsangaben auf die Menge an ZnCl₂/NH₄Cl bezogen sind und die Summe dieser Bestandteile der Zusammensetzung 100 Gew.-% ergibt; wobei ferner der pH-Wert des Hauptfluxbades bei einem pH-Wert von 0,5 bis pH 6, vorzugsweise bei pH ≤ 5, besonders bevorzugt bei pH 4 liegt; und/oder
2. b) Vorflux und Hauptflux, wobei das Vorflux ein Benetzungsbad umfasst, dass eine Prozesslösung umfassend Bismut in Form von Bismutionen (Bi³⁺) im Bereich von 0,1 g/l bis 10 g/l; und NH₄Cl (Ammoniumchlorid) im Bereich von 100 g/l bis 350 g/l aufweist; und einen pH-Wert von ≤ 2,5, vorzugsweise von pH ≤ 2,0, besonders bevorzugt von pH ≤ 1,0 aufweist und eine Benetzung der Bauteiloberfläche mit Bismut (Bi) und NH₄Cl (Ammoniumchlorid) bewirkt; und wobei das Hauptflux ZnCl₂ (Zinkchlorid) im Bereich von 80 Gew. % bis 98 Gew.%, vorzugsweise 88 Gew.% ± 2 Gew; und NH₄Cl (Ammoniumchlorid) im Bereich von 1 Gew.% bis 19 Gew.%, vorzugsweise 12 Gew.% ± 2 Gew.%; wobei die Gewichtsangaben auf die Menge ZnCl₂/NH₄Cl bezogen sind und die Summe dieser Bestandteile der Zusammensetzung 100 Gew.-% ergibt; und wobei ferner der pH-Wert des Hauptfluxbades bei einem pH-Wert von 0,5 bis pH 6, vorzugsweise bei pH ≤ 5, besonders bevorzugt bei pH 4 liegt.

In one embodiment of the present invention, the flux/wetting bath, flux bath and/or wetting bath is divided into one or more steps, so that the individual steps within the process step of flux treatment and wetting can act individually on the surface of the at least one component, the steps of the process step of the fluxing/wetting treatment can be separated as follows:

1. a) Pre-flux and main flux, wherein the pre-flux comprises a wetting bath that contains a process solution comprising bismuth in the form of Bi ³⁺ in the range from 0.1 g/l to 10 g/l and a pH of ≦2.5, preferably of pH ≦2.0, particularly preferably of pH ≦1.0, and causes the component surface to be wetted with bismuth (Bi); and wherein the main flux comprises ZnCl ₂ (zinc chloride) in the range of 80 wt% to 98 wt%, preferably 88 wt% ± 2 wt%, and NH ₄ Cl (ammonium chloride) in the range of 1 wt% to 19 % by weight, preferably 12% by weight ± 2% by weight, the weight data being based on the amount of ZnCl ₂ /NH ₄ Cl and the sum of these components of the composition being 100% by weight; further wherein the pH of the main flux bath is at a pH of from 0.5 to pH 6, preferably at pH ≤ 5, particularly preferably at pH 4; and or
2. b) pre-flux and main flux, wherein the pre-flux comprises a wetting bath containing a process solution comprising bismuth in the form of bismuth ions (Bi ³⁺ ) in the range of 0.1 g/l to 10 g/l; and NH ₄ Cl (ammonium chloride) in the range of 100 g/l to 350 g/l; and has a pH value of ≦2.5, preferably pH ≦2.0, particularly preferably pH ≦1.0, and causes wetting of the component surface with bismuth (Bi) and NH ₄ Cl (ammonium chloride); and wherein the main flux comprises ZnCl ₂ (zinc chloride) in the range of 80 wt% to 98 wt%, preferably 88 wt% ± 2 wt; and NH ₄ Cl (ammonium chloride) in the range of 1 wt% to 19 wt%, preferably 12 wt% ± 2 wt%; where the weight data are based on the amount of ZnCl ₂ /NH ₄ Cl and the sum of these components of the composition is 100% by weight; and further wherein the pH of the main flux bath is at pH 0.5 to pH 6, preferably at pH ≤ 5, most preferably at pH 4.

1. a) Bismutionen (Bi3+) im Bereich von 0,1 g/l bis 10 g/l und einen pH-Wert von ≤ 2,5, vorzugsweise von pH ≤ 2,0, besonders bevorzugt von pH ≤ 1,0; oder
2. b) Bismutionen (Bi3+) im Bereich von 0,1 g/l bis 10 g/l; und NH4CI (Ammoniumchlorid) im Bereich von 100 g/l bis 350 g/l, behandelt wird;

wobei der pH-Wert der Prozesslösung bei ≤ 2,5, vorzugsweise bei pH ≤ 2,0, besonders bevorzugt bei pH ≤ 1,0 liegt.In a further aspect of the invention, the component is treated in a wetting bath upstream of the zinc bath, in which the component is treated with a process solution comprising the following composition

1. a) bismuth ions (Bi3+) in the range from 0.1 g/l to 10 g/l and a pH of ≦2.5, preferably pH ≦2.0, particularly preferably pH ≦1.0; or
2. b) bismuth ions (Bi3+) in the range from 0.1 g/l to 10 g/l; and NH4Cl (ammonium chloride) in the range of 100 g/l to 350 g/l;

wherein the pH of the process solution is ≦2.5, preferably at pH≦2.0, particularly preferably at pH≦1.0.

The bismuth (Bi) is preferably used in the process liquid of the at least one process bath in the form of bismuth chloride (BiCl ₃ ), bismuth oxide (Bi ₂ O ₃ ), bismuth carbonate ((BiO) ₂ CO ₃ ) and/or bismuth granules (metal basis).

In a preferred embodiment, the bath temperature of the flux/wetting bath, flux bath and/or wetting bath is also between 30°C and 60°C, preferably between 40°C and 50°C. In addition, a pretreatment time in the flux/wetting bath, flux and/or wetting bath of preferably 10 seconds (sec) to 2 minutes (min), particularly preferably 20 s to 45 s, is provided.

In one embodiment, the process solution within the flux/wetting bath, flux bath and/or wetting bath does not exceed a limit value of iron ions (Fe ^2+/3+ ) of 3 g/l to 10 g/l, particularly preferably ≦5 g/l .

In a further aspect of the method, at least one rinsing process in a rinsing bath is upstream, downstream or interposed between the at least one fluxing agent/wetting bath, fluxing agent bath and/or wetting bath.

1. a) während des laufenden Betrieb aufbereitet, indem ein Volumen an Prozessflüssigkeit aus dem Flussmittel-/Benetzungsbad, Flussmittelbades und/oder Benetzungsbades entnommen wird und in einem separaten Becken mit Ammoniak (NH₃) und Wasserstoffperoxid (H₂O₂) bei einem pH- Wert von 2,0 bis 6,0, vorzugsweise von pH 3,5 bis 4,2 behandelt und aufbereitet wird; oder
2. b) entnommen und in einem ersten separaten Becken mit Ammoniak (NH₃) und einem pH-Wert von über 2, vorzugsweise zwischen 2,0 und 2,5, behandelt, und wobei das Filtrat im weiteren Schritt in einem zweiten separaten Becken mit Ammoniak (NH₃) und Wasserstoffperoxid (H₂O₂) bei einem pH-Wert 3,0 bis 6,0, vorzugsweise von 3,5 bis 4,2 behandelt wird.

Furthermore, in a further embodiment of the method of the present invention, the process solution is processed within a process bath by means of at least one processing system and the process solution and/or components processed from impurities are returned to the process bath, such as the flux/wetting bath, flux bath and/or wetting bath . In the treatment plant, the part of the process liquid of the process bath is preferred

1. a) processed during ongoing operation by removing a volume of process liquid from the flux/wetting bath, fluxing bath and/or wetting bath is treated and processed in a separate tank with ammonia (NH ₃ ) and hydrogen peroxide (H ₂ O ₂ ) at a pH of 2.0 to 6.0, preferably from pH 3.5 to 4.2; or
2. b) removed and treated in a first separate tank with ammonia (NH ₃ ) and a pH above 2, preferably between 2.0 and 2.5, and the filtrate in a further step in a second separate tank with ammonia (NH ₃ ) and hydrogen peroxide (H ₂ O ₂ ) at a pH of from 3.0 to 6.0, preferably from 3.5 to 4.2.

In one aspect, the precipitation sludge within the at least one separate basin for processing is collected and disposed of in at least one downstream filter press, with the processed process liquid being returned to the process bath as filtrate and/or the components obtained in the processing being returned to the flux/wetting bath, flux bath and/or wetting bath is supplied again.

1. a) eine Entfettung der Bauteiloberfläche mittels mindestens eines Entfettungsbades, wobei das Entfettungsbad vorzugsweise ferner mindestens einen Regenerationskreislauf umfasst, in dem die Prozessflüssigkeit des Entfettungsbades aufbereitet wird;
2. b) einen Beizprozess, der in mindestens einem Beizbad erfolgt, wobei das Beizbad vorzugsweise ferner mindestens einen Regenerationskreislauf umfasst, in dem die Prozessflüssigkeit des Beizbades aufbereitet wird; und/oder
3. c) ein Spülen der Bauteiloberfläche mit einem oder mehreren Spülbädern, welche den Prozessbädern vorgeschaltet, zwischengeschaltet oder nachgeschaltet sind.

In one embodiment of the present invention, the flux/wetting treatment, flux bath and/or wetting bath are preceded by one or more process steps and/or process baths for cleaning the component, with the at least one process step preferably comprising:

1. a) degreasing of the component surface by means of at least one degreasing bath, the degreasing bath preferably also comprising at least one regeneration circuit in which the process liquid of the degreasing bath is prepared;
2. b) a pickling process that takes place in at least one pickling bath, the pickling bath preferably also comprising at least one regeneration circuit in which the process liquid of the pickling bath is treated; and or
3. c) rinsing of the component surface with one or more rinsing baths which are upstream, intermediate or downstream of the process baths.

In one aspect of the present invention, the process liquid of the process steps in the process baths is agitated in order to enable better cleaning of the component by this.

In one embodiment (i), the treatment of the component in the flux/wetting bath, flux bath and/or wetting bath is followed by one or more drying steps in the drying oven, with liquid residues on the component being dried at a temperature between 200-230 °C, preferably 225 °C ± 5 °C and a preferred residence time between 1 min and 30 min; and/or (ii) one or more galvanizing steps follow, the zinc bath (7) containing 2% by weight to 10% by weight aluminum (AI) and 90% by weight to 98% by weight zinc (Zn), with preferably 5 % by weight ±1% by weight Al and 95% by weight ±1% by weight Zn and the dwell time of the components in the zinc bath (7) is ≦10 minutes, preferably 5 minutes ±1 minutes at a temperature of 420°C ± 10 °C.

Furthermore, according to another aspect of the method, the at least one component can be cooled in at least one quenching bath and/or processed in at least one additional post-treatment step, with at least one additional protective layer preferably being applied to the component surface in the at least one post-treatment step.

• 88 Gew.% ± 2 Gew.% ZnCl₂ (Zinkchlorid);
• 12 Gew.% ± 2 Gew.% NH₄Cl (Ammoniumchlorid); und
• 1 g/l ± 0,5 g/l Bi³⁺ (Bismutionen);

wobei die Gewichtsangaben auf das Fluss-/Benetzungsmittel bezogen sind und die Summe aller Bestandteile der Zusammensetzung 100 Gew.-% ergibt, wobei ferner das Flussmittel-/Benetzungsbad einen pH-Wert ≤ 2,0, vorzugsweise von pH ≤ 1 aufweist.The present invention also relates to a flux/wetting composition for galvanizing components, in particular metallic components in discontinuous galvanizing, comprising the following composition:

• 88 wt% ± 2 wt% ZnCl ₂ (zinc chloride);
• 12 wt% ± 2 wt% NH ₄ Cl (ammonium chloride); and
• 1 g/l ± 0.5 g/l Bi ³⁺ (bismuth ions);

wherein the weight data are based on the flux/wetting agent and the sum of all components of the composition is 100% by weight, wherein the flux/wetting bath also has a pH value of ≦2.0, preferably pH ≦1.

• Bismut (Bi³⁺) im Bereich von 0,1 g/l bis 10 g/l; und
• NH4CI (Ammoniumchlorid) im Bereich von ≤ 350 g/l bei
• einen pH-Wert ≤ 2,5, vorzugsweise von pH ≤ 2,0, besonders bevorzugt von pH ≤ 1,0.

The invention also relates to a wetting agent composition for galvanizing components, in particular metallic components, comprising the following composition:

• bismuth (Bi ³⁺ ) in the range of 0.1 g/l to 10 g/l; and
• NH4CI (ammonium chloride) in the range of ≤ 350 g/l
• a pH ≦2.5, preferably pH ≦2.0, particularly preferably pH ≦1.0.

The invention also relates to a system for galvanizing components, in particular metallic components for discontinuous galvanizing, the system having at least one flux/wetting bath, flux bath and/or wetting bath that is upstream of the zinc bath and in which the surface of the at least one component bismuth is applied.

1. a) die folgende Flussmittel-/Benetzungszusammensetzung aufweist:
   • 80 Gew. % bis 98 Gew.% ZnCl₂ (Zinkchlorid), vorzugsweise 88 Gew.% ± 2 Gew.% ZnCl₂ (Zinkchlorid);
   • 1 Gew.% bis 19 Gew.% NH₄Cl (Ammoniumchlorid), 12 Gew.% ± 2 Gew.% NH₄Cl (Ammoniumchlorid); und
   • 0,1 g/l bis 4 g/l Bi³⁺ (Bismutionen), vorzugsweise 1 g/l ± 0,5 g/l Bi³⁺ (Bismutionen); wobei die Gewichtsangaben auf das Fluss-/Benetzungsmittel bezogen sind und die Summe aller Bestandteile der Zusammensetzung 100 Gew.-% ergibt, wobei ferner das Flussmittel-/Benetzungsbad einen pH-Wert von pH 0,5 bis pH 2,5, vorzugsweise ≤ 2,0, besonders bevorzugt bei pH ≤ 1 aufweist;
2. b) in wässriger Lösung vorliegt und der Gesamtsalzgehalt innerhalb des Bades im Bereich von 100 bis 650 g/l, bevorzugt im Bereich von 250 bis 450 g/l liegt;
3. c) in ein oder mehrere Schritte aufgeteilt sind, sodass die einzelnen Schritte innerhalb des Prozessschrittes der Flussmittelbehandlung und Benetzung einzeln auf die Oberfläche des mindestens einen Bauteils einwirken können, wobei das Flussmittel-/Benetzungsbad wie folgt aufgetrennt wird:
   • i) Vorflux und Hauptflux, wobei das Vorflux ein Benetzungsbad umfasst, dass eine Prozesslösung umfassend Bi³⁺ (Bismutionen) im Bereich von 0,1 g/l bis 10 g/l und einen pH-Wert von ≤ 2,5, vorzugsweise von pH ≤ 2,0, besonders bevorzugt von pH ≤ 1,0 aufweist und eine Benetzung der Bauteiloberfläche mit Bismut (Bi) bewirkt; und wobei das Hauptflux ZnCl₂ (Zinkchlorid) im Bereich von 80 Gew. % bis 98 Gew.%, vorzugsweise 88 Gew.% ± 2 Gew.%; und 1 Gew.% bis 19 Gew.% NH₄Cl (Ammoniumchlorid), vorzugsweise 12 Gew.% ± 2 Gew.% NH₄Cl (Ammoniumchlorid); und wobei die Gewichtsangaben auf die Menge ZnCl₂/NH₄Cl bezogen sind und die Summe dieser Bestandteile der Zusammensetzung 100 Gew.-% ergibt umfasst; und wobei ferner der pH-Wert des Hauptfluxbades bei einem pH-Wert von 0,5 bis pH 6, vorzugsweise bei pH ≤ 5, besonders bevorzugt bei pH 4 liegt;
   • ii) Vorflux und Hauptflux, wobei das Vorflux ein Benetzungsbad umfasst, dass eine Prozesslösung umfassend Bi³⁺ (Bismutionen) im Bereich von 0,1 g/l bis 10 g/l; und NH₄Cl (Ammoniumchlorid) im Bereich von 100 g/l bis 350 g/l aufweist; und einen pH-Wert von ≤ 2,5, vorzugsweise von pH ≤ 2,0, besonders bevorzugt von pH ≤ 1,0 aufweist und eine Benetzung der Bauteiloberfläche mit Bismut (Bi) und NH₄Cl (Ammoniumchlorid) bewirkt; und wobei das Hauptflux ZnCl₂ (Zinkchlorid) im Bereich von 80 Gew. % bis 98 Gew.%, vorzugsweise 88 Gew.% ± 2 Gew; und NH₄Cl (Ammoniumchlorid) im Bereich von 1 Gew.% bis 19 Gew.%, vorzugsweise 12 Gew.% ± 2 Gew.% umfasst; und wobei die Gewichtsangaben auf die Menge ZnCl₂/NH₄Cl bezogen sind und die Summe dieser Bestandteile der Zusammensetzung 100 Gew.-% ergibt; und wobei ferner der pH-Wert des Hauptfluxbades bei einem pH-Wert von 0,5 bis pH 6, vorzugsweise bei pH ≤ 5, besonders bevorzugt bei pH 4 liegt.

The system preferably has at least one flux/wetting bath that

1. a) has the following flux/wetting composition:
   • 80% to 98% by weight ZnCl ₂ (zinc chloride), preferably 88% ± 2% by weight ZnCl ₂ (zinc chloride);
   • 1 wt% to 19 wt% NH ₄ Cl (ammonium chloride), 12 wt% ± 2 wt% NH ₄ Cl (ammonium chloride); and
   • 0.1 g/l to 4 g/l Bi ³⁺ (bismuth ions), preferably 1 g/l ± 0.5 g/l Bi ³⁺ (bismuth ions); wherein the weight data are based on the flux/wetting agent and the sum of all components of the composition is 100% by weight, the flux/wetting bath also having a pH of pH 0.5 to pH 2.5, preferably ≤ 2 0, particularly preferably at pH ≤ 1;
2. b) is in an aqueous solution and the total salt content within the bath is in the range from 100 to 650 g/l, preferably in the range from 250 to 450 g/l;
3. c) are divided into one or more steps, so that the individual steps within the process step of flux treatment and wetting can act individually on the surface of at least one component, with the flux/wetting bath being separated as follows:
   • i) pre-flux and main flux, the pre-flux comprising a wetting bath containing a process solution comprising Bi ³⁺ (bismuth ions) in the range of 0.1 g/l to 10 g/l and a pH of ≤ 2.5, preferably of pH ≤ 2.0, particularly preferably pH ≤ 1.0, and causes wetting of the component surface with bismuth (Bi); and wherein the main flux comprises ZnCl ₂ (zinc chloride) in the range of 80 wt% to 98 wt%, preferably 88 wt% ± 2 wt%; and 1% to 19% by weight NH ₄ Cl (ammonium chloride), preferably 12% ± 2% by weight NH ₄ Cl (ammonium chloride); and wherein the weight data are based on the amount of ZnCl ₂ /NH ₄ Cl and the sum of these components of the composition is 100% by weight; and further wherein the pH of the main flux bath is at a pH of from 0.5 to pH 6, preferably at pH ≤ 5, more preferably at pH 4;
   • ii) pre-flux and main flux, wherein the pre-flux comprises a wetting bath containing a processing solution comprising Bi ³⁺ (bismuth ions) in the range of 0.1 g/l to 10 g/l; and NH ₄ Cl (ammonium chloride) in the range of 100 g/l to 350 g/l; and has a pH value of ≦2.5, preferably pH ≦2.0, particularly preferably pH ≦1.0, and causes wetting of the component surface with bismuth (Bi) and NH ₄ Cl (ammonium chloride); and wherein the main flux comprises ZnCl ₂ (zinc chloride) in the range of 80 wt% to 98 wt%, preferably 88 wt% ± 2 wt; and NH ₄ Cl (ammonium chloride) in the range of 1 wt% to 19 wt%, preferably 12 wt% ± 2 wt%; and where the weight data are based on the amount of ZnCl ₂ /NH ₄ Cl and the sum of these components of the composition is 100% by weight; and further wherein the pH of the main flux bath is at pH 0.5 to pH 6, preferably at pH ≤ 5, most preferably at pH 4.

1. a) Bismutionen (Bi³⁺) im Bereich von 0,1 g/l bis 10 g/l und einen pH-Wert von ≤ 2,5, vorzugsweise von pH ≤ 2,0, besonders bevorzugt von pH ≤ 1,0; oder
2. b) Bismutionen (Bi³⁺) im Bereich von 0,1 g/l bis 10 g/l; und NH₄Cl (Ammoniumchlorid) im Bereich von 100 g/l bis 350 g/l, aufweist, bei einem pH-Wert der Prozesslösung von ≤ 2,5, vorzugsweise von pH ≤ 2,0, besonders bevorzugt von pH ≤ 1,0,

behandelt wird.In one embodiment, the system includes a wetting bath upstream of the zinc bath, in which the component is treated with a process solution

1. a) bismuth ions (Bi ³⁺ ) in the range from 0.1 g/l to 10 g/l and a pH of ≦2.5, preferably pH ≦2.0, particularly preferably pH ≦1.0; or
2. b) bismuth ions (Bi ³⁺ ) in the range from 0.1 g/l to 10 g/l; and NH ₄ Cl (ammonium chloride) in the range from 100 g/l to 350 g/l, at a pH of the process solution of ≦2.5, preferably of pH ≦2.0, particularly preferably of pH ≦1, 0,

is treated.

In one aspect of the invention, at least one rinsing bath can be connected upstream, downstream or interposed between the at least one fluxing agent/wetting bath, fluxing agent bath and/or wetting bath.

1. a) die Prozessflüssigkeit des Prozessbades während des laufenden Betrieb aufbereitet wird, wobei ein Volumen an Prozessflüssigkeit aus dem Flussmittel-/Benetzungsbades, Flussmittelbades und/oder Benetzungsbades (5) entnommen wird und mit Ammoniak (NH₃) und Wasserstoffperoxid (H₂O₂) bei einem pH- Wert von 2,0 bis 6,0, vorzugsweise von pH 3,5 bis 4,2 behandelt und aufbereitet wird; oder
2. b) die Prozessflüssigkeit aufbereitet wird, wobei ein Volumen der Prozessflüssigkeit aus dem Flussmittel-/Benetzungsbades, Flussmittelbades und/oder Benetzungsbades (5) entnommen wird und in einem ersten separaten Becken mit Ammoniak (NH₃) und einem pH-Wert von über 2, vorzugsweise zwischen 2,0 und 2,5 behandelt wird, und wobei das Filtrat im weiteren Schritt in einem zweiten separaten Becken mit Ammoniak (NH₃) und Wasserstoffperoxid (H₂O₂) bei einem pH-Wert von 3,5 bis 4,2 behandelt wird.

In one embodiment, the system additionally comprises at least one treatment system, in which impurities or disruptive liquids in the process solution of the at least one process bath are reduced or removed within the at least one treatment system and the treated process solution and/or a treated component is returned to the respective process bath. In a preferred embodiment, the treatment plant comprises at least one separate bath by

1. a) the process liquid of the process bath is treated during ongoing operation, with a volume of process liquid from the flux/wetting bath, flow medium bath and/or wetting bath (5) is removed and treated with ammonia (NH ₃ ) and hydrogen peroxide (H ₂ O ₂ ) at a pH of 2.0 to 6.0, preferably of pH 3.5 to 4.2 and processed; or
2. b) the process liquid is treated, whereby a volume of the process liquid is taken from the flux/wetting bath, flux bath and/or wetting bath (5) and in a first separate tank with ammonia (NH ₃ ) and a pH value of more than 2, preferably between 2.0 and 2.5, and wherein the filtrate is further treated in a second separate tank with ammonia (NH ₃ ) and hydrogen peroxide (H ₂ O ₂ ) at a pH of 3.5 to 4, 2 is treated.

1. a) ein Entfettungsbad zur Entfettung der Bauteiloberfläche umfasst;
2. b) ein Beizbad zum Beizen der Bauteils; und/oder
3. c) ein oder mehrere vorgeschaltete, zwischengeschaltete oder nachgeschaltete Spülbäder zum Spülen der Bauteiloberfläche.

In a further aspect, the flux/wetting bath, flux bath and/or wetting bath of the system is preceded by one or more process steps and/or process baths for cleaning the component. In a preferred embodiment, the at least one process bath upstream of the flux/wetting bath, flux bath and/or wetting bath comprises:

1. a) comprises a degreasing bath for degreasing the component surface;
2. b) a pickling bath for pickling the component; and or
3. c) one or more upstream, intermediate or downstream rinsing baths for rinsing the component surface.

1. a) ein oder mehrere Trockenöfen zur Trocknung des Bauteils;
2. b) ein oder mehrere Verzinkungsbäder zur Verzinkung der Bauteiloberfläche;
3. c) mindestens einem Abschreckbad; und/oder
4. d) mindestens ein Nachbehandlungsbad, vorzugsweise zur Auftragung mindestens einer weiteren Schutzschicht auf der Bauteiloberfläche.

In a further aspect, the system can further comprise one or more treatment steps downstream of the fluxing/wetting bath, fluxing bath and/or wetting bath. These process steps preferably include

1. a) one or more drying ovens for drying the component;
2. b) one or more galvanizing baths for galvanizing the component surface;
3. c) at least one quench bath; and or
4. d) at least one post-treatment bath, preferably for applying at least one further protective layer to the component surface.

In addition, the present invention relates to the use of an above-described flux/wetting agent, flux and/or wetting agent in the above-described method and/or system and the use of the above-described method and/or system for galvanizing components, in particular metallic components in discontinuous galvanizing.

The invention also relates to components produced using the method described above.

The present invention is characterized by the embodiments in the claims and described in more detail by the statements in the following description, the examples and the drawings.

• 1 Darstellung der Legierungsschichten bzw. Legierungsphasen nach der diskontinuierlichen (a) und kontinuierlichen (b) Verzinkung an einem metallischen Bauteil.
• 2 Schematische Darstellung des bevorzugten Aufbaus einer erfindungsgemäßen Anlage mit den einzelnen Prozessbädern (1-8) und ihren Regenerationskreisläufen (unterhalb der Bäder dargestellt).
  • (1) Entfettungsbad mit alkalischer Heißentfettung, einer Badrotation, einer Temperatur ≥ 60°C; (2) Mindestens ein unbeheiztes Spülbad umfassend Stadtwasser, ohne Badbewegung; (3) Beizbad mit ≤ 70-105 g/l HCl, ≥ 110 -130 g/l Eisen (Fe) und Badrotation; (4) Mindestens ein unbeheiztes Spülbad umfassend Stadtwasser, ohne Badbewegung; (5) Flussmittel-/Benetzungsbad mit (5.1) Gemeinsamen Flussmittel-/Benetzungsbad umfassend 88 Gew.% ZnCl₂ (Zinkchlorid), 12 Gew.% NH₄Cl (Ammoniumchlorid), 1 g/l Bi³⁺ (Bismutionen), einer Temperatur von 40-50°C und einer Badrotation; (5.2.1) Benetzungsbad umfassend 0,1-10 g/l Bi³⁺ (Bismutionen) bei einer Temperatur von 40-50°C und einer Badrotation; (5.2.2) Benetzungsbad umfassend 0,1-10 g/l Bi³⁺ (Bismutionen) und 100-350 g/l NH₄Cl (Ammoniumchlorid) bei einer Temperatur von 40-50°C und einer Badrotation; (5.3) Getrenntes Flussmittel-/Benetzungsbad mit einem Vorflux bzw. Benetzungsbad umfassend 0,1-10 g/l Bi³⁺ (Bismutionen) und ≤ 350 g/l NH₄Cl (Ammoniumchlorid) bei einer Temperatur von 40-50°C und einer Badrotation sowie einem Hauptflux umfassend 88 Gew.% ZnCl₂ (Zinkchlorid), 12 Gew.% NH₄Cl (Ammoniumchlorid) bei einer Temperatur von 40-50°C und einer Badrotation; (6) Trocknungsofen mit einer Temperatur von 200-230°C; (7) Zinkbad umfassend eine ZnAl5-Schmelze umfassend 5 Gew% AI und 95 Gew.% Zn mit einer Temperatur von 410-430°C und ggf. Badrotation und Überlauf; (8) Abschreck- und/oder Nachbehandlungsbad;
  • Bauteilbewegung oberhalb der Bäder mittels Pfeilen dargestellt; Regenerationskreisläufe Pfeile und schematische Becken unterhalb der Prozessbäder; Badbewegung (gestrichelte Linie innerhalb der Prozessbäder)
• 3 Schematische Darstellung des bevorzugten Aufbaus eines Flussmittel-/Benetzungsbades, Flussmittelbad und/oder Benetzungsbad mit Aufbereitungsanlage.
• 4 Schematische Darstellung Fällungsprozesse innerhalb der Aufbereitung.
  • (a) Fällung von Bismut (Bi) und Eisen bzw. Eisenionen und Rückführung in das Flussmittel-/Benetzungsbad; (b) Getrennte Fällung von Bismut und Eisen bzw. Eisenionen in zwei separaten Bädern bzw. Becken nebst Rückführung der Prozessflüssigkeit und/der der Komponenten in das Flussmittel-/Benetzungsbad, Flussmittel- und/oder /Benetzungsbad.
• 5 Schematische Darstellung des bevorzugten Aufbaus eines Entfettungsbades mit alkalischer Heißentfettung mit Regenerationskreislauf.
• 6 Schematische Darstellung des bevorzugten Aufbaus eines Beizbades mit Regenerationskreislauf und Vorlagebehältern.

Description of the drawings

• 1 Representation of the alloy layers or alloy phases after discontinuous (a) and continuous (b) galvanizing on a metallic component.
• 2 Schematic representation of the preferred structure of a plant according to the invention with the individual process baths (1-8) and their regeneration circuits (shown below the baths).
  • (1) degreasing bath with alkaline hot degreasing, a bath rotation, a temperature ≥ 60°C; (2) At least one unheated rinse bath comprising city water, without bath agitation; (3) Pickling bath with ≤ 70-105 g/l HCl, ≥ 110-130 g/l iron (Fe) and bath rotation; (4) At least one unheated rinse bath comprising city water, without bath agitation; (5) Fluxing/wetting bath comprising (5.1) Common fluxing/wetting bath comprising 88% by weight ZnCl ₂ (zinc chloride), 12% by weight NH ₄ Cl (ammonium chloride), 1 g/l Bi ³⁺ (bismuth ions), a temperature of 40-50°C and a bath rotation; (5.2.1) wetting bath comprising 0.1-10 g/l Bi ³⁺ (bismuth ions) at a temperature of 40-50°C and bath rotation; (5.2.2) wetting bath comprising 0.1-10 g/l Bi ³⁺ (bismuth ions) and 100-350 g/l NH ₄ Cl (ammonium chloride) at a temperature of 40-50°C and bath rotation; (5.3) Separate flux/wetting bath with a pre-flux or wetting bath comprising 0.1-10 g/l Bi ³⁺ (bismuth ions) and ≤ 350 g/l NH ₄ Cl (ammonium chloride) at a temperature of 40-50°C and a bath rotation and a main flux comprising 88% by weight ZnCl ₂ (zinc chloride), 12% by weight NH ₄ Cl (ammonium chloride) at a temperature of 40-50°C and a bath rotation; (6) drying oven with a temperature of 200-230°C; (7) Zinc bath comprising a ZnAl5 melt comprising 5% by weight Al and 95% by weight Zn at a temperature of 410-430° C. and optionally bath rotation and overflow; (8) quench and/or post-treatment bath;
  • Component movement above the baths shown by arrows; regeneration circuits arrows and schematic basins below the process baths; Bath movement (dashed line within the process baths)
• 3 Schematic representation of the preferred structure of a flux/wetting bath, flux bath and/or wetting bath with treatment system.
• 4 Schematic representation of the precipitation processes within the preparation.
  • (a) precipitation of bismuth (Bi) and iron or iron ions and return to the fluxing/wetting bath; (b) Separate precipitation of bismuth and iron or iron ions in two separate baths or basins together with return of the process liquid and/or the components to the flux/wetting bath, flux and/or wetting bath.
• 5 Schematic representation of the preferred structure of a degreasing bath with alkaline hot degreasing with a regeneration cycle.
• 6 Schematic representation of the preferred structure of a pickling bath with regeneration circuit and storage tanks.

reference list

1

degreasing bath

2

rinse bath

3

pickling bath

4

rinse bath

5

Flux/wetting bath

6

drying oven

7

zinc melt

8th

Quenching/post-treatment bath

9

regeneration cycle

10

overflow

11

heating

12

reaction vessel

13

collection container

14

precipitation cycle

15

tranquilizer tank

Detailed description of the invention

The present invention relates to a method, a plant and their use for galvanizing components, in particular metallic components in discontinuous galvanizing.

Hereinafter, as used herein, the article “a” and all derivatives thereof should be understood generally as “one or more” unless otherwise indicated or clear from the context as a singular form.

To the extent that the terms "includes," "has," "possesses," and the like are used in the specification or claims, such terms should be construed as the terms "comprising" or "comprising," i.e., not exhaustive, unless is explicitly stated.

The term “bath” or “baths” used below generally refers to basins that can be filled with liquid, preferably process liquid, and into which a component can be embedded. For this reason, the pools or baths are mostly open at the top. Although several baths are generally spoken of, it can also be a basin or bath that is divided into individual sections that include the respective process liquid. In such a case, the individual sections would each correspond to a bath.

As stated above, discontinuous galvanizing is a process in which one or more components go through several process steps in the form of treatments in appropriate baths, with the result that a zinc layer is applied to the component(s). Discontinuous galvanizing is also commonly referred to as hot-dip galvanizing, batch galvanizing and/or hot-dip galvanizing.

The term "component(s)" used in the process or system refers to metallic components of any kind, preferably components made of ferrous or iron-based material, in particular components made of steel, such as blanks, sections, structures and/or finished workpieces. In the following, the term "component" also includes groupings and/or assemblies of components of different or the same type and/or different or the same material, which can undergo joint treatment in one or more process baths and/or steps. In some cases, these groupings can also be put together using suitable aids such as traverses, goods carriers or similar devices.

In order to be able to generate a surface that is as clean and trouble-free as possible for the galvanizing, the component is degreased, pickled and/or cleaned using known baths by transferring at least one component from one bath to the next, such as the 2 in numbers 1-4 to ent take is. These steps are used for holistic component cleaning.

The decisive process step in the pre-treatment of at least one component, which allows a thin galvanizing layer within the usual discontinuous galvanizing process, is the treatment of the component in the flux/wetting bath, flux bath and/or wetting bath (5), the so-called "fluxing". In the following, a distinction is also made between the main flux and the pre-flux in the case of “flux(es)”, whereby the component is wetted with bismuth and/or bismuth and NH ₄ Cl in the pre-flux or wetting bath and the actual wetting takes place in the main flux or flux bath Flux treatment with ZnCl ₂ /NH ₄ Cl of the surface takes place. For the sake of simplicity, if both steps take place in one bath at the same time, it is referred to as a flux/wetting bath. If only bismuth alone or bismuth and NH ₄ Cl are used in a process bath, this is referred to as a wetting bath, "preflux" or "wetting" for the sake of simplicity. In tests in connection with the pretreatment of component surfaces, it was accidentally determined that optimizing the flux/wetting bath, in particular the flux/wetting agent composition, flux composition and/or the wetting agent in combination with zinc alloys including aluminum, such as ZnAl5 alloys , high-quality surface coatings can be generated, which have a thinner layer thickness of the zinc coating compared to the usual hot-dip galvanizing and are nonetheless corrosion-resistant and malleable.

The process step of fluxing and/or wetting in the bath (5) can take place in one step or alternatively be separated in order to achieve better wetting of the surface. The possible variants of the fluxing and/or wetting process step are described in more detail below.

• 80 Gew. % bis 98 Gew.% ZnCl₂ (Zinkchlorid);
• 1 Gew.% bis 19 Gew.% NH₄Cl (Ammoniumchlorid); und
• 0,1 g/l bis 4 g/l Bi³⁺ (Bismutionen), wobei die Gewichtsangaben auf das Fluss-/Benetzungsmittel bezogen sind und die Summe aller Bestandteile der Zusammensetzung 100 Gew.-% ergibt.

In one embodiment of the present invention, the fluxing and wetting takes place in a flux/wetting bath (5), as in FIG 2 , No. 5.1. In such a case, the at least one component is immersed in the flux/wetting bath (5), which has the following flux/wetting agent composition:

• 80% to 98% by weight ZnCl ₂ (zinc chloride);
• 1% to 19% by weight NH ₄ Cl (ammonium chloride); and
• 0.1 g/l to 4 g/l Bi ³⁺ (bismuth ions), the weight data being based on the flow agent/wetting agent and the sum of all components of the composition being 100% by weight.

The pH of the flux/wetting bath (5) is also between pH 0.5 and pH 2.5.

• 88 Gew.% +/- 2 Gew.% ZnCl₂ (Zinkchlorid);
• 12 Gew.% +/- 2 Gew.% NH₄Cl (Ammoniumchlorid); und
• 1 g/l +/- 0,5 g/l Bi³⁺ (Bismutionen),

auf, wobei die Gewichtsangaben auf das Fluss-/Benetzungsmittel bezogen sind und die Summe aller Bestandteile der Zusammensetzung 100 Gew.-% ergibt.Examination of the surface of components after galvanizing, which were subjected to a pretreatment using the following composition of the fluxing/wetting bath (5), showed a surprisingly positive effect on the galvanizing layer, which showed reduced thickness, formability and improved quality compared to the galvanizing layers, which were generated according to the usual state-of-the-art hot-dip galvanizing processes. For this reason, in a preferred embodiment, the flow/wetting agent

• 88 wt% +/- 2 wt% ZnCl ₂ (zinc chloride);
• 12 wt% +/- 2 wt% NH ₄ Cl (ammonium chloride); and
• 1 g/l +/- 0.5 g/l Bi ³⁺ (bismuth ions),

on, the weights being based on the flow agent/wetting agent and the sum of all components of the composition being 100% by weight.

The pH of the fluxing agent/wetting bath (5) is preferably pH≦2.0, particularly preferably pH≦1. The fluxing agent/wetting bath (5) is operated continuously at a pH≦2.0, with this is adjusted using hydrochloric acid (HCl), preferably a dilute HCl solution. The pH value must be constantly below pH ≤ 2.5, otherwise the bismuth would precipitate. Due to the eutectic in the form of the NH ₄ Cl-ZnCl ₂ mixture and the bismuth (Bi), in the zinc melt process step that follows the flux/wetting bath, a fine pickling effect occurs as well as a bismuth wetting in the boundary layer area of the component surface, whereby the resulting Zinc coating has a high quality. Another advantage of the low pH value is that there is no formation of Fe ³⁺ (iron(III) ions) in the flux/wetting bath (5), which contribute to sludge sedimentation.

Due to the low pH value and the bath parameters, the bismuth is in the form of bismuth chloride (BiCl ₃ ). In addition to bismuth chloride (BiCl ₃ ), bismuth oxide (Bi ₂ O ₃ ), bismuth carbonate ((BiO) ₂ CO ₃ ) or bismuth granules (metal basis) can be used to adjust the bismuth content in the bath, which then convert due to the acidic pH value.

The fluxing agent/wetting agent is preferably present in an aqueous solution in the fluxing agent/wetting bath (5), the total salt content within the bath being in the range from 100 to 650 g/l, preferably in the range from 250 to 450 g/l. The total salt content includes the components NH ₄ Cl (ammonium chloride), and ZnCl ₂ (zinc chloride) and BiCl ₃ (bismuth chloride).

The bath temperature of the flux/wetting bath (5) is preferably between 30°C and 60°C, preferably between 40°C and 50°C.

In order to achieve an optimal treatment surface for the zinc melt, which brings with it a fine pickling effect and wetting, a pretreatment time in the flux/wetting bath (5) of 10 seconds (sec) to 2 minutes (min), preferably from 20 seconds to 45 sec, turned out to be beneficial.

In an alternative embodiment, the process step of the flux/wetting bath (5) is divided into one or more steps, so that the individual steps within the process step of flux treatment and wetting can have a better effect on the surface of the at least one component.

• 3 Fe → 3 Fe²⁺ + 6 e^- (Oxidation)
• 2 Bi³⁺ + 6 e^- → 2 Bi (Reduktion)
• Gesamtreaktion: 3 Fe + 2 Bi³⁺ → 3Fe²⁺ + 2 Bi

In one aspect of the invention, the fluxing/wetting bath previously described is replaced by a bath, hereinafter referred to as a "wetting bath", like that described above 2 No. 5.2.1 is shown. The wetting bath here comprises bismuth (Bi ³⁺ ) in the range from 0.1 g/l to 10 g/l. Here, too, bismuth chloride (BiCl ₃ ), bismuth oxide (Bi ₂ O ₃ ), bismuth carbonate ((BiO) ₂ CO ₃ ) and/or bismuth granules (metal basis) can be used to adjust the bismuth content. In order to be able to wet the component surface with bismuth, a pH value of pH ≦2.5, preferably pH ≦2.0, particularly preferably pH ≦1.0, is generated in the bath, with the adjustment of the pH Value preferably hydrochloric acid (HCl), more preferably dilute hydrochloric acid is used. In such a design, the components NH ₄ Cl (ammonium chloride) and ZnCl ₂ (zinc chloride) are not contained in the bath, which means that there is no fine pickling effect based on NH ₄ Cl-ZnCl ₂ in the subsequent zinc melt (ZnAl5). Nevertheless, investigations of the component surfaces treated in this way showed an improved zinc application, which shows a lower thickness as well as better functionality of the zinc layer. This is mainly attributed to the surprising effect of the bismuth (Bi) deposited on the component surface in elemental or metallic form, which due to its higher standard potential compared to the ferrous surface of the component is deposited on it and forms a layer that subsequently forms Galvanizing bath has a positive effect on the zinc layer that forms.

• 3 Fe → 3 Fe ²⁺ + 6 e ^- (oxidation)
• 2 Bi ³⁺ + 6 e ^- → 2 Bi (reduction)
• Total reaction: 3 Fe + 2 Bi ³⁺ → 3Fe ²⁺ + 2 Bi

• 0 g/l ZnCl₂ (Zinkchlorid);
• 100 g/l bis 350 g/l NH₄Cl (Ammoniumchlorid); und
• 0,1 g/l bis10 g/l Bismutionen (Bi³⁺).

In another embodiment, NH ₄ Cl (ammonium chloride) can be added or generated directly and/or indirectly to the wetting bath, which comprises only bismuth as a composition component, as in FIG 2 No. 5.2.2 is shown. In this case, ZnCl ₂ (zinc chloride) is not added. The composition of the wetting bath therefore includes the following composition:

• 0 g/l ZnCl ₂ (zinc chloride);
• 100 g/l to 350 g/l NH ₄ Cl (ammonium chloride); and
• 0.1 g/l to 10 g/l bismuth ions (Bi ³⁺ ).

The ammonium chloride can also be generated by possible precipitation reactions, which means that it does not have to be added directly to the bath. As in the previously described fluxing agent/wetting bath, the pH value is set at a pH value of pH ≤ 2.5, preferably pH ≤ 2.0, particularly preferably pH ≤ 1.0 in the bath, with the setting being the pH is preferably adjusted using hydrochloric acid (HCl), particularly preferably dilute hydrochloric acid (HCl). The proportion of iron ions is ≦10.0 g/l, preferably ≦8.0 g/l, particularly preferably ≦5.0 g/l Fe ^2+/3+ (iron ions). In the present case, a fine pickling effect based on NH ₄ Cl (ammonium chloride) and wetting of the component surface with bismuth takes place in the ZnAl5 melt, ie the zinc bath, which further improves the coating of the component surface with the zinc coating.

• 80 Gew. % bis 98 Gew.% ZnCl₂ (Zinkchlorid), besonders bevorzugt 88 Gew.% +/- 2 Gew.% ZnCl₂ (Zinkchlorid);
• 1 Gew.% bis 19 Gew.% NH₄Cl (Ammoniumchlorid), besonders bevorzugt 12 Gew.% +/- 2 Gew.% NH₄Cl (Ammoniumchlorid),

wobei die Gewichtsangaben auf die Menge ZnCl₂/NH₄Cl bezogen sind und die Summe dieser Bestandteile der Zusammensetzung 100 Gew.-% ergibt. Der pH-Wert des Hauptfluxbades liegt in der Regel bei einem pH-Wert von 0,5 bis pH 6, vorzugsweise bei pH ≤ 5, besonders bevorzugt bei pH 4. Der pH- Wert wird dabei wie zuvor zu den Bädern beschrieben eingestellt. Der Eisenionenanteil liegt bei ≤ 10,0 g/l, vorzugsweise bei ≤ 8,0 g/l, besonders bevorzugt bei ≤ 5,0 g/l Fe^2+/3+ (Eisen).In a further embodiment of the present invention, the process step within the flux/wetting bath (5) as in FIG 2 No. 5.3, separated in order to improve the respective effects of the individual chemical processes within the process step on the component surface. In such a preferred arrangement of the flux/wetting bath, the component surface is first wetted in the preflux or wetting bath with bismuth (Bi ³⁺ ) in the range from 0.1 g/l to 10 g/l, with the bismuth content in the bath being addition of bismuth chloride (BiCl ₃ ), bismuth oxide (Bi ₂ O ₃ ), bismuth carbonate ((BiO) ₂ CO ₃ ) and/or bismuth granules (metal basis). In order to ensure that the bismuth adheres to the component surface, as mentioned above, a pH value of pH ≦2.5, preferably pH ≦2.0, particularly preferably generated from pH ≦1.0 in the bath, which is preferably adjusted by hydrochloric acid (HCl), particularly preferably dilute hydrochloric acid (HCl). The wetting bath or preflux can also additionally include the direct and/or indirect addition and/or generation of NH ₄ Cl (ammonium chloride), so that the component surface is also wetted with NH ₄ Cl (ammonium chloride) in addition to the bismuth. When using ammonium chloride in the wetting bath, preferably 100-350 g/l NH ₄ Cl are used in this bath. Following the pre-flux bath, the component is further treated in the so-called main flux. The main flux preferably has the following composition:

• 80% by weight to 98% by weight ZnCl ₂ (zinc chloride), particularly preferably 88% by weight +/- 2% by weight ZnCl ₂ (zinc chloride);
• 1% by weight to 19% by weight NH ₄ Cl (ammonium chloride), particularly preferably 12% by weight +/- 2% by weight NH ₄ Cl (ammonium chloride),

where the weight data are based on the amount of ZnCl ₂ /NH ₄ Cl and the sum of these components of the composition is 100% by weight. The pH of the main flux bath is generally at a pH of 0.5 to pH 6, preferably at pH≦5, particularly preferably at pH 4. The pH is adjusted as described above for the baths. The proportion of iron ions is ≦10.0 g/l, preferably ≦8.0 g/l, particularly preferably ≦5.0 g/l Fe ^2+/3+ (iron).

Surprisingly, experimental investigations have shown that the metallic, elemental bismuth deposited on the component surface in the pre-flux or wetting bath is not washed off or rinsed off in the subsequent main flux and/or intermediate rinsing steps. As a result, improved wetting and cleaning of the component surface is achieved, which is essential for a thinner zinc application. Due to such a treatment in the pre-flux or wetting bath and the subsequent main flux, it was possible to generate high-quality zinc layers after the zinc bath, which, despite the low layer thickness, exhibited high corrosion resistance. The zinc coatings developed in this way exhibited the quality features of durability and flexibility that are particularly important in the automotive industry. A further advantage of such an arrangement is that bismuth is not present in the main flux, which is the case in the flux baths known in the prior art when bismuth is used.

In one embodiment, in addition to the baths, ie flux/wetting bath (5), 2 , No. 5.1, after the wetting bath 2 No. 5.2.1, after the wetting bath with ammonium chloride 2 No. 5.2.2, and/or the separate flux and wetting bath, the 2 No. 5.3, one or more rinsing baths can be connected in between, upstream and/or downstream in order to prevent or reduce the carryover of the chemicals, components and/or substances formed within the respective baths and to compensate for the carryover and/or evaporation losses.

In the process step of fluxing/wetting treatment, fluxing and/or wetting treatment (5), 2 No. 5.1, 5.2.1, 5.2.2 and/or 5.3, there may be an accumulation of impurities, such as iron ions (Fe ^2+/3+ ), which disrupt and/or influence the process flow. This accumulation of impurities can be remedied in one aspect by freshly preparing the respective bath. This should always be done when the concentration of the interfering substance has exceeded a limit. In the case of iron ions (Fe ^2+/3+ ), this is preferably a limit value of 3 g/l to 10 g/l, particularly preferably ≦5 g/l.

In one embodiment of the present invention, however, the baths comprise at least one treatment plant, which removes the impurities from the baths and recycles the process liquid and/or specific components. In the at least one fluxing agent/wetting bath (5) or the separate processes, the at least one treatment plant is used to separate iron, so that the baths can be in operation longer without having to be made up again. The process bath is set up in such a way that an overflow is arranged on at least one edge area of the respective bath. When using a heat exchanger and/or a heater in the bathroom, this overflow is preferably located on the opposite end of the latter. For the regeneration process, the overflow and/or the bath can be connected directly to a filter press, which is used to separate suspended matter/sludge. Due to the suspended matter/sludge separation in a separate compartment, the process in the flux bath and/or wetting bath is not disturbed by this. After the impurities have been separated, the process liquid can then be fed back into the process bath.

In a further aspect, in addition to the separation of the impurities, in particular the separation of suspended matter/sludge using the overflow and/or from the bath, the process liquid can also or alternatively be processed directly in the flux/wetting bath, flux bath and/or wetting bath (5), like in the 4 is executed. In processing find one or more precipitation variants application, for example in the 4 a) and b) are shown. In a first precipitation variant, under the 4 a) is shown, the process bath, ie the flux/wetting bath (5), 2 , No. 5.1-5.3, processed in batch operation, ie during ongoing operation. It is thus achieved that the impurities, such as iron ions (Fe ^2+/3+ ), are continuously removed from the bath. In this case, a specific volume of process liquid is removed from the respective bath and fed to a separate bath, basin and/or container or separate area. Depending on the volume of the bath, this so-called batch volume can include a different amount of the process liquid, but the amount is selected in such a way that the process in the bath is not disturbed by the removal of the process liquid. In a preferred embodiment, the amount of process liquid is ≦1 m ³ . In the separate basin, referred to below as precipitation bath 1, the process liquid is treated and prepared, with ammonia (NH3) and hydrogen peroxide (H ₂ O ₂ ) at a pH of 2.0 to 6.0, preferably pH 3 .5 to 4.2, until bismuth and/or iron precipitation can no longer be observed. Alternatively, the precipitation process can also take place over a defined period of time. Bismuth precipitation can usually already be observed at a pH value above 2. Iron (Fe) precipitates at a pH above 3. The iron(II) (Fe ²⁺ ) present in the process liquid, which is present as iron chloride (FeCl ₂ ), is oxidized using hydrogen peroxide (H ₂ O ₂ ) and converted to iron (III) Fe ³⁺ , in the form of filterable iron( III) hydroxide (Fe(OH) ₃ ). Bismuth and iron components are simultaneously precipitated in a precipitation bath and removed from the process liquid in a downstream filter press. The precipitation sludge occurring in the filter press is preferably collected and disposed of here. The filtrate is added to the process bath (step 5.1-5.3, 2 ) returned, whereby the high pH value and the bismuth deficits generated by the precipitation process are compensated for before the return, during the return and/or in the process bath itself. Here, the pH is again adjusted to a pH of below 2, preferably with the aid of dilute hydrochloric acid (HCl), and the bismuth concentration is adjusted to the target value, preferably ≧1.0 g/l of bismuth, by appropriate addition.

In a second precipitation variant, which under 4 b) is shown, as in the first precipitation variant, the process liquid of the flux/wetting bath, flux bath and/or wetting bath (5), 2 , No. 5.1-5.3, processed in batch operation. Here, the batch volume is further treated in separate baths. In contrast to the first precipitation variant, bismuth is first precipitated by adding ammonia (NH ₃ ) and preferably a pH of more than 2, preferably between 2.0 and 2.5. The suspension generated by the precipitation is passed through a filter press and the bismuth, which is then present in the form of bismuth sludge or bismuth filter cake, is separated in this and can be used as a recovered component in the process flow, such as the process bath of steps 5.1 to 5.3 ( 2 ) can be reused. The filtrate, ie the remaining liquid, is further treated in a further step, which preferably takes place in a further tank or separate area, in order to achieve separation of iron. In this step, the pH of the bath is raised to a preferred pH of 3.5 to 4.2, preferably using ammonia (NH ₃ ). The ammonia (NH ₃ ) and hydrogen peroxide (H ₂ O ₂ ) are then added alternately until the iron components in the remaining liquid have been precipitated. The iron(II) (Fe ²⁺ ) formed during the process, which is present in the form of iron chloride (FeCl ₂ ), is converted to iron(III) (Fe ³⁺ ) by means of hydrogen peroxide (H ₂ O ₂ ), in the form of iron(III) hydroxide (Fe(OH) ₃ ), which is passed through another filter press and separated as iron hydroxide sludge. The sludge formed can be disposed of. The resulting filtrate, which now consists of a cleaned process liquid, can be fed to the at least one process bath in accordance with precipitation variant 1. The advantage of such a precipitation variant is that the components are separated from each other separately from the "used" process liquid, which makes it possible to recycle the components.

Alternatively or in addition to the precipitation variants described above, the at least one process bath, in particular the fluxing agent/wetting bath (5), fluxing agent and/or wetting bath, can also be prepared by using two identical baths, with only one bath being active. In such a precipitation variant, the active bath does not necessarily have to be subject to a previously described variant of the treatment, which requires continuous removal. On the contrary, the active bath remains in use until the interference limit concentration of the impurities exceeds a certain range. In the case of the iron content in the process liquid, the limit would be more than 2 g/l, preferably 3.5 g/l, particularly preferably more than 5 g/l of iron or iron ions in the process bath. If the limit value is exceeded by suitable means, which can be automatic measurements or manual measurements, the bath is subjected to one of the precipitation processes listed above, 4 , switched on. the case The process is operated until there is a reduced concentration of impurities in the process bath. With regard to the iron and/or the iron ions, the concentration is below 5 g/l, preferably below 3 g/l, particularly preferably below 0.5 g/l. While the first bath is being prepared, the previously inactive second process bath is active and is operated until an impurity limit value is also exceeded in it. The change between the at least one active and one inactive process bath is preferably carried out continuously.

The aforementioned treatment processes of the process liquid in the fluxing/wetting bath (5), fluxing bath and/or wetting bath, have been described in terms of an exact number of baths or additional areas. However, the number of baths in the individual precipitation variants and/or active/inactive baths can vary, so that several baths or areas can also be available for each of the baths or areas specified above.

In the case of a separate wetting bath, such as this below 2 , No. 5.2.1 or 5.3, in which the component is only treated with bismuth itself, the impurity limit concentration is usually not reached or only after a long service life, especially with one or more upstream cleaning steps, such as at least one rinsing bath , this in 2 , No. 4 is shown. In such a case, the wetting bath is therefore preferably completely disposed of and made up again.

In a further embodiment of the present invention, the flux/wetting bath (5), flux bath and/or wetting bath can be preceded by one or more process steps and/or baths which improve the cleaning condition of the component surface for the subsequent galvanizing step and thus produce an improved zinc coating layer.

The at least one further process step preferably comprises at least one degreasing bath (1). In the at least one degreasing bath (1), which is schematically the 2 , No. 1 as well as the 5 shown, the surface of the component is freed from fats and/or oils by being treated with alkaline hot degreasing at preferably above 60 °C. Emulsifying (= oils/fats in solution) or demulsifying (= oils/fats floating) can be used here. The total treatment time in the at least one degreasing bath (1), depending on the oil and/or grease load on the component surface, is between 2 minutes and 60 minutes, preferably between 5 minutes and 20 minutes. The at least one degreasing bath (1) can in one aspect have an overflow which surrounds the pool and/or is arranged on at least one side of the pool. If a heat exchanger and/or a heater is used in the degreasing bath (1), the overflow is preferably arranged on the opposite side of the tank. In one aspect of the present invention, creaming oils and/or fats can be separated in the overflow itself and/or at least one settling tank connected to this or to the degreasing bath (1). This is done, for example, by means of bag filters and/or band filters, but other devices can also be used for this purpose. The stilling tank, the overflow and/or the process tank in the degreasing bath (1) itself can also be followed by a filter press for separating suspended matter/sludge, in which the aforementioned impurities are filtered, and the degreasing bath (1), 2 , Number 1; 5 a filtered and/or cleaned process liquid is supplied again. At least one rinsing bath (2) can be connected downstream of the degreasing bath (1).

In a further aspect, the system and/or the method comprise a pickling process which can take place in at least one pickling bath (3), such as that 2 , No. 3 and 6 is shown. Possible baths and processes that can be used in pickling are, for example, the European application EP3483304A1 refer to. For the removal of, inter alia, rust and scale in the pickling bath (3), preferably two to 8 pickling baths (3), particularly preferably four to six pickling baths (3), are used, all or only some of which can be active. Depending on the rusting state of the component surface and/or the degree of scale, the pickling time is between 5 minutes and 240 minutes, preferably between 10 minutes and 180 minutes, particularly preferably between 15 minutes and 120 minutes. The pickling process preferably takes place in a temperature range of 15°C to 40°C, preferably between 20-30°C. In order to increase the pickling effect and promote the formation of passive layers on the component surface, the formation of iron(III) ions in the pickling bath can be increased. This is preferably done by additionally introducing air, in particular oxygen, into the process bath. The air can be introduced here using common systems, such as, for example, but not limited to, air blowers, air pumps including hose or pipe distribution systems with corresponding outlet openings and/or using bath circulation or bath movement. With the help of this, the content of iron(III) ions (Fe ³⁺ ) can be increased to up to 5.0 g/l, whereby preferably 0.5 -1.5 g/l Fe ³⁺ should be achieved in the process liquid . Among other things, the Fe ³⁺ reduces hydrogen embrittlement and/or hydrogen storage on the components, which means that in the galvanizing process (step 7, 2 ) a reduction in hydrogen emissions can be observed, resulting in improved galvanizing layers (Zn-Al layers) that have reduced formation of, for example, voids and/or cracks. 2 FeCl ₃ + H ₂ → 2 FeCl ₂ + 2 HCl

The at least one pickling bath (3) can also include at least one overflow, which surrounds all side areas of the pool or only parts of it. This overflow is preferably located on the opposite side of the heat exchanger and/or the bath heater if one is in operation. In one aspect, each individual pickling bath (3) or the baths together can comprise an individual and/or a common regeneration circuit in which the process liquid is regenerated and is fed back to the at least one process bath. The composition of the at least one pickling bath (3) is preferably 70 g/l hydrochloric acid (HCl) and 200 g/l iron (Fe), preferably 105 g/l HCl and 110 g/l Fe. If the components fall below the concentrations of below 70 g/l HCl and above 130 g/l iron (Fe), the respective process liquid of the respective bath is disposed of or partially disposed of and prepared again. For the regeneration cycle of the pickling bath (3), the process bath itself and/or the overflow is connected to one or more settling tanks. Contaminants such as grease, oil or other contaminants that have been on the component surface can be removed from these settling tanks by suitable measures such as skimming and/or filters. In one aspect, a filter press is also installed downstream of the at least one settling tank, overflow and/or the at least one pickling process bath, which filter press is intended to serve for the separation of suspended matter/sludge. Due to the separation of the dirt and/or impurities in the regeneration circuit, the process liquid can be returned to the pickling bath, which means that a new make-up or partial make-up of the bath can be delayed or even prevented.

With the help of the continuous and/or discontinuous treatment and/or partial disposal and/or regeneration of the process liquid within the pickling, the condition of the bath remains almost the same, which, among other things, prevents or reduces saw number profiles and minimizes the use of chemicals within the baths.

Between the at least one degreasing bath (1), the at least one pickling bath (3) and/or the at least one fluxing/wetting bath, wetting bath and/or fluxing bath (5), as described above, one or more rinsing baths (2, 4) can be placed between be interposed between the individual process baths (1, 3, 5), which prevent the chemicals from the individual baths from being carried over into the next process step. Furthermore, the use of the at least one rinsing bath should compensate for possible evaporation and/or carry-over losses. The rinsing liquid of the at least one rinsing bath (2, 4) preferably comprises unheated water, in which case the respective city water can be used. Due to the fact that iron and/or iron ions in the fluxing/wetting bath (5), fluxing bath and/or wetting bath of step 5 ( 2 ) and/or the galvanizing bath (7) of step 7 ( 2 ) have a disruptive effect on the formation of the zinc layer, preferably at least two rinsing baths are used before the flux/wetting bath (5), flux bath and/or wetting bath, which have a maximum interference limit concentration of less than or equal to (≤) 10 g/l iron /iron ions, preferably ≦8 g/l iron/iron ions, particularly preferably ≦5 g/l iron/iron ions.

Each of the preceding process steps ( 1 , Nos. 1-5) can be carried out within a so-called standing pool. In such a process liquid is not moved in the respective baths. However, investigations of the component surface after cleaning and/or galvanizing have shown that in particular the movement of the process liquid within the steps of degreasing bath (1), pickling bath (3) and flux/wetting bath (5) ( 2 ), flux bath and/or wetting bath have contributed to an improved surface coating. For this reason, in a preferred aspect, a bath movement is generated by at least one pump in the at least previously named process steps of degreasing, pickling and flux treatment and wetting, with preferably a bath circulation according to the in the European patent application EP3483304A1 described procedure takes place. In this case, one or more pumps are used to form a laminar flow, which can preferably form a flow change, ie the reversal of the bath rotation. This can be achieved with two pumps that generate different directions of flow and are operated in alternation, or with pumps that can change the direction of flow in a reversing direction of rotation. Due to the movement of the bath, the process liquid in the area of the component surface is regularly exchanged, which means that there is no saturation or accumulation in the boundary layer area between the component surface (substrate) and the components of the process solution. Bath rotation, with or without changing the direction of flow, can be performed using pumps with or without rectifiers, placed inside or outside the bath. A combination of several variants is also possible here.

Is the pre-treatment, ie cleaning of the component surface after steps 1-5 ( 2 ) completed, so in one embodiment, the component is dried in a further step in the drying oven (6) to free the surface of liquid residues, like the 2 , No. 6 can be found. In this case, circulating air is preferably generated by radial and/or axial fans, the temperature in the oven being between 200 and 230° C., preferably 225° C.±5° C. The dwell time of the component in the drying oven (6) is between 1 minute and 60 minutes, preferably between 5 minutes and 30 minutes, depending on the liquid load on the component.

In a further aspect of the present invention, the component is treated in a zinc bath (7) after cleaning and, if necessary, drying. The zinc bath (7), which in 2 Step 7, comprises 2 wt% to 10 wt% aluminum (Al) and 90 wt% to 98 wt% zinc (Zn), with preferably 5 wt% ± 1 wt% Al and 95 wt% % ±1 wt% Zn can be used. However, the zinc bath (7) can also contain traces of other accompanying elements. As a rule, the dwell time of the components in the ZnAl5 melt, ie the galvanizing bath (7), is ≤10 minutes, preferably 5 minutes ±1 minute, at a temperature of 420°C ±10° to obtain an optimum galvanized layer C In order to avoid an accumulation of aluminum and/or aluminum compounds, such as iron-aluminum compounds, on the zinc bath surface, which can lead to quality losses such as pimples, additional circulation of the melt bath can take place using suitable pumps and/or overflows.

The galvanizing step (7) ( 2 ) In a further embodiment, at least one quenching bath (8) can be connected downstream, through which the components are cooled after galvanizing, and/or at least one additional post-treatment step (8), such as passivation and/or sealing, in which at least one another protective layer can be applied to increase corrosion protection. Like the previous steps, these optional steps after the actual galvanizing are preferably also carried out in a dipping process in which the component is dipped into a basin or bath. In addition, the at least one additional bath in the optional step can also have a bath circulating device, as described above for cleaning steps 1-5 ( 2 ) described.

In the at least one quenching bath (8), the components are cooled and any ash residues present, in particular chlorides, are rinsed out of the flux/wetting bath (5), flux bath and/or wetting bath. To avoid corrosion products on the surface of the component and/or to attack the zinc layer applied to the surface of the component, the quenching bath is replaced when the chloride content is ≧300 mg/l, preferably ≧250 mg/l, particularly preferably ≧200 mg/l. Alternatively, in one embodiment, the enriched process liquid of the quenching bath (8) can be used to compensate for the evaporation/entrainment losses in the flux/wetting bath (5) flux bath and/or wetting bath of the pretreatment. Here, the liquid of the quenching bath (8) can be filtered, for example, by means of suitable filters and one of steps 5 ( 2 , 3 ) are supplied.

In addition to the quenching bath (8), a further or alternative process step can be a passivation/sealing bath after galvanizing (7) ( 2 ) or after a quenching bath (8) which can be a chemical passivation, for example using chromium salts, an inorganic seal using for example silicates and/or an organic seal such as polymers. With chemical passivation, the passivating agent reacts with the surface of the galvanized component by forming a corresponding conversion layer. In contrast to this, with inorganic and organic sealing, an additional layer is applied to the already galvanized surface. The layers applied to the component surface within the passivation and/or sealing have a layer thickness of less than 5 μm, preferably less than 3 μm, particularly preferably ≦1 μm (micrometer). The process liquid of the passivation bath and/or sealing bath is preferably continuously filtered in a bypass using suitable filters, such as a candle filter. If a limit value required for the passivation bath and/or sealing bath is exceeded within the process liquid, the respective process liquid is (partially) disposed of and re-prepared.

In the individual process steps 1-8 ( 2 ), which are carried out in the system of the present invention, carryover into the subsequent process or processes can occur due to carryover of individual chemicals from the preceding processes and/or removal from the component surface, whereby the respective subsequent process step or the following process steps May contain traces of chemicals previously used. Furthermore, the rinsing baths as well as the evaporation and carry-over losses mean that small amounts of other components, ions, metals and/or salts can be found in the individual process baths due to the use of drinking water, which can have a different composition. However, these are negligible for the effect and/or the individual process steps.

The present invention also relates to the use of the flux/wetting process, the system comprising one or more process baths (1-8; 2 ) and/or the method for galvanizing in the coating of iron-based components, preferably using a zinc-aluminum alloy, particularly preferably a ZnAI5 alloy.

Furthermore, the invention also relates to components that have been treated with the flux/wetting process or the method described above.

These and other embodiments of the present invention are disclosed in, and are encompassed by, the specification and examples. Additional literature on a known one of the materials, methods and applications that can be used in accordance with the present invention can be retrieved from public libraries and databases, for example using electronic devices. A more complete understanding of the invention can be obtained by reference to the following examples, which are provided for the purpose of illustration and are not intended to limit the scope of the invention.

examples

Example: Preferred embodiment of a plant for galvanizing a component surface

In the 2 a plant for hot-dip galvanizing is shown, which includes a greasing process in a degreasing bath, 2 , Number 1; a pickling process in the pickling bath, 2 , No. 3; a flux treatment and/or wetting in a flux/wetting bath, 2 , No. 5; a drying step in the drying oven, 2 , No. 6; galvanizing in the zinc melt, 2 , No. 7; and optionally an additional step of quenching in the quenching bath (8) and/or passivation/sealing in the post-treatment bath (8). Between the individual pre-treatment steps prior to galvanizing, each process step (1, 3 and/or 5) is preferably provided with at least one rinsing bath (2, 4), which preferably comprises unheated water and is intended to prevent the previous process step from being carried over into the subsequent process step; 2 . The arrows above the process baths within the 2 characterize the course of the component within the system, ie the flow of goods.

In the process baths 1, 3, 5, 7 and/or 8, the bath is preferably circulated, with the respective process bath having at least one pump with which the process liquid can be moved. In one aspect, a regular rotation reversal of the process liquid should preferably be formed, which is formed by the reversing operation of the pumps and/or at least two pumps, which can form a reverse flow and are active in opposite directions. The corresponding bath circulation is indicated by the dashed arrows within the respective process baths in FIG 2 marked.

In addition, the process baths, in particular the at least one degreasing bath (1, 2 such as 5 ), the at least one pickling bath (2; 2 , 6 ), the at least one flux/wetting bath (5; 2 , 3 ), flux bath and/or wetting bath, and/or the additional quenching and/or post-treatment bath (8; 2 ) have a regeneration circuit that regenerates the respective process liquids of the respective bath and returns them to the corresponding process bath for reuse. The regeneration cycle within the 2 shown below the corresponding process baths.

In the preferred embodiment, alkaline hot degreasing is used in the degreasing bath (1), which has temperatures of over 60°C.

In pickling (3), the following parameters are used to further clean the component: ≤ 70-105 g/l HCl; ≥ 110 -130 g/l Fe; 20-30°C.

The flux/wetting bath (5) can be designed in different variants, in steps 5.1, 5.2.1, 5.2.2 and 5.3 of 2 are shown.

In variant 5.1 of the flux/wetting bath (5), this has the following composition: 88% by weight ZnCl ₂ (zinc chloride), 12% by weight NH ₄ Cl (ammonium chloride) and 1 g/lg/l Bi ³⁺ ( bismuth ions), at a temperature of 40-50°C.

Only a wetting with bismuth in a wetting bath follows 2 No. 5.2.1, the bath has the following composition: 0.1 g/l - 10 g/lg/l Bi ³⁺ (bismuth ions), at a temperature of 40-50°C.

In a further embodiment, 5.2.2, the wetting bath can also comprise ammonium chloride (NH ₄ Cl) in addition to the bismuth. In such a case, the bath has the following composition: 100-350 g/l NH ₄ Cl (ammonium chloride) and 0.1 g/l -10 g/l Bi ³⁺ (bismuth ions), at a temperature of 40-50 °C

Alternatively, the flux/wetting bath (5) can also include a pre-flux or wetting bath and a main flux, as can be seen in 5.3. The component is wetted with bismuth in a pre-flux, with the process liquid in the bath having the following composition: 0.1 g/l -10 g/l g/l Bi ³⁺ (bismuth ions), ≤ 350 g/l NH ₄ Cl (ammonium chloride ), at a temperature of 40-50°C. The downstream main flux then has the following composition: 88% by weight of ZnCl ₂ (zinc chloride) and 12% by weight of NH ₄ Cl (ammonium chloride), at a temperature of 40 to 50°C.

After the surface cleaning, a drying step (6) in the drying oven can be provided before the galvanizing, the drying oven preferably having a temperature of 200 to 230°C.

The subsequent galvanizing bath, also called molten zinc (7), has the following composition: 5% by weight Al and 95% by weight Zn, at a bath temperature of 410-430°C, which is also referred to as a ZnAl5 alloy bath.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2002/042512 A1 [0010]
• EP 3483304 A1 [0072, 0076]

Claims (18)

Method for galvanizing components, in particular metallic components, in discontinuous galvanizing, in which, before zinc is applied to the surface of the components in a zinc bath (7), at least one treatment of the component in a flux/wetting bath, flux bath and/or wetting bath ( 5) takes place, in which bismuth is deposited on the surface of the at least one component. procedure after claim 1 , wherein the at least one component is immersed in the flux/wetting bath (5), the flux/wetting agent of the flux/wetting bath (5) a) having the following composition: (i) 80% by weight to 98% by weight ZnCl ₂ (zinc chloride), preferably 88 wt% ± 2 wt% ZnCl ₂ (zinc chloride); (ii) 1 wt% to 19 wt% NH ₄ Cl (ammonium chloride), preferably 12 wt% ± 2 wt% NH ₄ Cl (ammonium chloride); and (iii) 0.1 g/l to 4 g/l Bi ³⁺ , preferably 1 g/l ± 0.5 g/l Bi ³⁺ (bismuth ions); where the weight data are based on the flow agent/wetting agent and the sum of all components of the composition is 100% by weight, b) a pH of pH 0.5 to pH 2.5, preferably ≦2.0, particularly preferred at pH ≤ 1; c) is in an aqueous solution and the total salt content within the bath (5) is in the range from 100 to 650 g/l, preferably in the range from 250 to 450 g/l. procedure after claim 1 , wherein the flux/wetting bath (5) is divided into one or more steps, so that the individual steps within the process step of flux treatment and wetting can act individually on the surface of the at least one component, the steps of the process step of flux and wetting treatment be separated as follows: c) pre-flux and main flux, the pre-flux comprising a wetting bath containing a process solution comprising bismuth in the form of Bi ³⁺ in the range from 0.1 g/l to 10 g/l and a pH value of ≤ 2.5, preferably pH ≦2.0, particularly preferably pH ≦1.0, and causes wetting of the component surface with bismuth (Bi); and wherein the main flux comprises ZnCl ₂ (zinc chloride) in the range of 80 wt% to 98 wt%, preferably 88 wt% ± 2 wt%, and NH ₄ Cl (ammonium chloride) in the range of 1 wt% to 19 wt% .%, preferably 12% by weight ± 2% by weight, the weight data being based on the amount of ZnCl ₂ /NH ₄ Cl and the sum of these components of the composition being 100% by weight; further wherein the pH of the main flux bath is at a pH of from 0.5 to pH 6, preferably at pH ≤ 5, particularly preferably at pH 4; and/or d) pre-flux and main flux, wherein the pre-flux comprises a wetting bath containing a process solution comprising bismuth in the form of bismuth ions (Bi ³⁺ ) in the range of 0.1 g/l to 10 g/l; and NH ₄ Cl (ammonium chloride) in the range of 100 g/l to 350 g/l; and has a pH value of ≦2.5, preferably pH ≦2.0, particularly preferably pH ≦1.0, and causes wetting of the component surface with bismuth (Bi) and NH ₄ Cl (ammonium chloride); and wherein the main flux comprises ZnCl ₂ (zinc chloride) in the range of 80 wt% to 98 wt%, preferably 88 wt% ± 2 wt; and NH ₄ Cl (ammonium chloride) in the range of 1 wt% to 19 wt%, preferably 12 wt% ± 2 wt%; where the weight data are based on the amount of ZnCl ₂ /NH ₄ Cl and the sum of these components of the composition is 100% by weight; and further wherein the pH of the main flux bath is at pH 0.5 to pH 6, preferably at pH ≤ 5, most preferably at pH 4. procedure after claim 1 , wherein the component is treated in a wetting bath upstream of the zinc bath (7), in which the component is treated with a process solution comprising a) bismuth ions (Bi ³⁺ ) in the range from 0.1 g/l to 10 g/l and a pH value of ≤ 2.5, preferably pH ≤ 2.0, particularly preferably pH ≤ 1.0; or b) bismuth ions (Bi ³⁺ ) in the range from 0.1 g/l to 10 g/l; and NH ₄ Cl (ammonium chloride) in the range of 100 g/l to 350 g/l; wherein the pH of the process solution is ≦2.5, preferably at pH≦2.0, particularly preferably at pH≦1.0. Procedure according to one of Claims 1 until 4 , wherein a) bismuth (Bi) in the form of bismuth chloride (BiCl ₃ ), bismuth oxide (Bi ₂ O ₃ ), bismuth carbonate ((BiO) ₂ CO ₃ ) and/or bismuth granules (metal basis) in the flux/wetting bath, flux bath and /or wetting bath (5) is used; b) the bath temperature of the fluxing/wetting bath, fluxing bath and/or wetting bath (5) is 30°C and 60°C, preferably between 40°C and 50°C; c) the pretreatment time in the flux/wetting bath, flux and/or wetting bath (5) is 10 seconds (sec) to 2 minutes (min), preferably 20 s to 45 s; d) between the at least one flux/wetting bath, flux bath and/or benet tion bath (5) at least one rinsing process in a rinsing bath is upstream, downstream or interposed; e) the process solution within the flux/wetting bath, flux bath and/or wetting bath (5) has a limit value of iron ions (Fe ^2+/3+ ) of 3 g/l to 10 g/l, particularly preferably 5 g/l, does not exceed; and/or f) the process solution within the flux/wetting bath, flux bath and/or wetting bath (5) is processed by means of at least one processing system and the processed process solution and/or component is returned to the flux/wetting bath, flux bath and/or wetting bath (5). is supplied. procedure after claim 5 , whereby in the treatment plant a) the process liquid of the process bath is treated during ongoing operation by removing a volume of process liquid from the flux/wetting bath, flux bath and/or wetting bath (5) and placing it in a separate basin with ammonia (NH ₃ ) and hydrogen peroxide (H ₂ O ₂ ) is treated and processed at a pH of 2.0 to 6.0, preferably from pH 3.5 to 4.2; or b) the process liquid is treated, whereby a volume of the process liquid is taken from the fluxing/wetting bath, fluxing bath and/or wetting bath (5) and placed in a first separate tank with ammonia (NH ₃ ) and a pH above 2 , preferably between 2.0 and 2.5, and wherein the filtrate is further treated in a second separate tank with ammonia (NH ₃ ) and hydrogen peroxide (H ₂ O ₂ ) at a pH of 3.5 to 4 ,2 is treated. procedure after claim 5 or 6 , wherein the precipitation sludge produced is disposed of in one of the at least one separate basins downstream filter press and the treated process liquid is returned to the process bath as filtrate and/or the components obtained in the treatment are returned to the flux/wetting bath, flux bath and/or wetting bath (5). becomes. Procedure according to one of Claims 1 until 7 , wherein the flux/wetting bath (5), flux bath and/or wetting bath is preceded by one or more process steps and/or process baths for cleaning the component, the at least one process step preferably comprising: a) degreasing of the component surface by means of at least one degreasing bath ( 1), wherein the degreasing bath (1) preferably further comprises at least one regeneration circuit in which the process liquid of the degreasing bath (1) is prepared; b) a pickling process that takes place in at least one pickling bath (3), the pickling bath (3) preferably also comprising at least one regeneration circuit in which the process liquid of the pickling bath (3) is prepared; and/or c) rinsing the component surface with one or more rinsing baths which are connected upstream, in between or downstream of the process baths (1, 3, 5). Procedure according to one of Claims 1 until 8th , wherein the flux/wetting bath (5), flux bath and/or wetting bath a) are followed by one or more drying steps in the drying oven (6), with liquid residues on the component at a temperature between 200-230 °C, preferably 225 °C ± 5 °C and a preferred residence time between 1 min and 30 min; and/or b) one or more galvanizing steps follow, the zinc bath (7) containing 2% by weight to 10% by weight of aluminum (Al) and 90% by weight to 98% by weight of zinc (Zn), with preferably 5% by weight .% ±1% by weight Al and 95% by weight ±1% by weight Zn and the dwell time of the components in the zinc bath (7) is ≦10 min, preferably 5 min ±1 min at a temperature of 420°C ± 10 °C. Flux/wetting composition for galvanizing components, in particular metallic components in discontinuous galvanizing, comprising the following composition: 88% by weight ± 2% by weight ZnCl ₂ (zinc chloride); 12 wt% ± 2 wt% NH ₄ Cl (ammonium chloride); and 1 g/l ± 0.5 g/l Bi ³⁺ (bismuth ions); wherein the weight data are based on the flux/wetting agent and the sum of all components of the composition is 100% by weight, wherein the flux/wetting bath also has a pH value of ≦2.0, preferably pH ≦1. Plant for galvanizing components, in particular metallic components, in discontinuous galvanizing, the plant having at least one flux/wetting bath, flux bath and/or wetting bath (5) that is upstream of the zinc bath (7) and in which the surface of the at least a component bismuth is applied. plant after claim 11 , wherein the at least one fluxing agent/wetting bath (5) a) has the following fluxing agent/wetting composition: 80% by weight to 98% by weight ZnCl ₂ (zinc chloride), preferably 88% by weight ± 2% by weight ZnCl ₂ ( zinc chloride); 1 wt% to 19 wt% NH ₄ Cl (ammonium chloride), 12 wt% ± 2 wt% NH ₄ Cl (ammonium chloride); and 0.1 g/l to 4 g/l Bi ³⁺ (bismuth ions), preferably 1 g/l ± 0.5 g/l Bi ³⁺ (bismuth ions); wherein the weight data are based on the flux/wetting agent and the sum of all components of the composition is 100% by weight, the flux/wetting bath (5) also having a pH of pH 0.5 to pH 2.5, preferably ≤ 2.0, particularly preferably at pH ≤ 1; b) is in an aqueous solution and the total salt content within the bath (5) is in the range from 100 to 650 g/l, preferably in the range from 250 to 450 g/l; c) are divided into one or more steps, so that the individual steps within the process step of flux treatment and wetting can act individually on the surface of the at least one component, with the flux/wetting bath (5) being separated as follows: i) preflux and Main flux, wherein the pre-flux comprises a wetting bath containing a process solution comprising Bi ³⁺ (bismuth ions) in the range from 0.1 g/l to 10 g/l and a pH value of ≤ 2.5, preferably pH ≤ 2, 0, particularly preferably pH ≦1.0, and causes the component surface to be wetted with bismuth (Bi); and wherein the main flux comprises ZnCl ₂ (zinc chloride) in the range of 80 wt% to 98 wt%, preferably 88 wt% ± 2 wt%; and 1 wt% to 19 wt% NH ₄ Cl (ammonium chloride), 12 wt% ± 2 wt% NH ₄ Cl (ammonium chloride); and wherein the weight data are based on the amount of ZnCl ₂ /NH ₄ Cl and the sum of these components of the composition is 100% by weight; and further wherein the pH of the main flux bath is at a pH of from 0.5 to pH 6, preferably at pH ≤ 5, more preferably at pH 4; ii) pre-flux and main flux, wherein the pre-flux comprises a wetting bath containing a processing solution comprising Bi ³⁺ (bismuth ions) in the range of 0.1 g/l to 10 g/l; and NH ₄ Cl (ammonium chloride) in the range of 100 g/l to 350 g/l; and has a pH value of ≦2.5, preferably pH ≦2.0, particularly preferably pH ≦1.0, and causes wetting of the component surface with bismuth (Bi) and NH ₄ Cl (ammonium chloride); and wherein the main flux comprises ZnCl ₂ (zinc chloride) in the range of 80 wt% to 98 wt%, preferably 88 wt% ± 2 wt; and NH ₄ Cl (ammonium chloride) in the range of 1 wt% to 19 wt%, preferably 12 wt% ± 2 wt%; and where the weight data are based on the amount of ZnCl ₂ /NH ₄ Cl and the sum of these components of the composition is 100% by weight; and further wherein the pH of the main flux bath is at pH 0.5 to pH 6, preferably at pH ≤ 5, most preferably at pH 4. plant after claim 11 , wherein the system comprises a wetting bath upstream of the zinc bath (7), in which the component is wetted with a process solution comprising a) bismuth ions (Bi ³⁺ ) in the range from 0.1 g/l to 10 g/l; or b) bismuth ions (Bi ³⁺ ) in the range from 0.1 g/l to 10 g/l; and NH ₄ Cl (ammonium chloride) in the range of 100 g/l to 350 g/l; wherein the pH of the process solution is ≦2.5, preferably at pH≦2.0, particularly preferably at pH≦1.0. Plant after one of Claims 11 until 13 , wherein a) at least one rinsing bath is connected upstream, downstream or interposed between the at least one flux/wetting bath, flux bath and/or wetting bath (5); b) impurities in the process solution of the at least one process bath (1, 3, 5) are reduced or removed within at least one treatment system and the treated process solution is returned to the respective process bath (1, 3, 5), the treatment system preferably having at least one separate bath by (i) the process liquid of the process bath being treated during ongoing operation, with a volume of process liquid being removed from the fluxing/wetting bath, fluxing bath and/or wetting bath (5) and treated with ammonia (NH ₃ ) and hydrogen peroxide (H ₂ O ₂ ) is treated and processed at a pH of 2.0 to 6.0, preferably from pH 3.5 to 4.2; or (ii) the process liquid is treated, whereby a volume of the process liquid is taken from the fluxing/wetting bath, fluxing bath and/or wetting bath (5) and placed in a first separate basin with ammonia (NH ₃ ) and a pH above 2, preferably between 2.0 and 2.5, and wherein the filtrate is treated in a further step in a second separate tank with ammonia (NH ₃ ) and hydrogen peroxide (H ₂ O ₂ ) at a pH of 3.5 to 4.2 is treated; Plant after one of Claims 11 until 14 , wherein a) the flux/wetting bath (5), flux bath and/or wetting bath are preceded by one or more process steps and/or process baths for cleaning the component, wherein the at least one process bath preferably comprises: (i) a degreasing bath (1) for degreasing of the component surface; (ii) a pickling bath (3) for pickling the component; and/or (iii) one or more upstream, intermediate or downstream rinsing baths for rinsing the component surface; and/or b) one or more process steps follow the flux/wetting bath (5), these steps comprising the following steps: (i) one or more drying ovens (6) for drying the component; (ii) one or more galvanizing baths (7) for galvanizing the component surface; (iii) at least one quench bath; and/or (iv) at least one after-treatment bath, preferably for applying at least one further protective layer to the component surface. Use of the method according to one of Claims 1 - 9 , the plant after one of Claims 11 until 15 for galvanizing components, in particular metallic components in discontinuous galvanizing and/or a zinc-aluminum alloy. Component manufactured by the method according to one of Claims 1 until 9 . Wetting composition for galvanizing components, in particular metallic components in discontinuous galvanizing, comprising the following composition: bismuth (Bi ³⁺ ) in the range from 0.1 g/l to 10 g/l; and NH ₄ Cl (ammonium chloride) in the range of ≦350 g/l and a pH of ≦2.5, preferably pH ≦2.0, particularly preferably pH ≦1.0.

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