Patent Application
20240271309
The invention relates to a method for producing an anodized aluminum article.
Corresponding methods for producing an anodized aluminum article are widely known, on their merits, from the prior art, and typically contain an anodizing step in which an aluminum substrate undergoes an electrochemical anodizing process, in order to form an aluminum article to be produced. The anodizing step is typically carried out in an anodizing bath which contains an anodizing solution that acts as an electrolyte.
Within the context of the anodizing step, the aluminum substrate is typically connected as the anode, ad a container receiving the anodizing solution is connected as the cathode, as a result of which, when corresponding electrical voltages are applied to the aluminum substrate forming the anode and the container forming the cathode, oxygen is produced at the surface of the aluminum substrate, which oxygen reacts, at the surface of the aluminum substrate, with aluminum ions, to form aluminum oxide, and thus forms an aluminum oxide layer on the surface of the aluminum substrate and/or converts the surface of the aluminum substrate into an aluminum oxide layer.
Even if anodized aluminum articles having properties that are in principle satisfactory can be produced using known anodizing methods, there is a need for a development of the anodizing methods with respect to efficient reproducible production of anodized aluminum articles having specific properties, such as having particularly matte and non-reflective surfaces.
The object of the invention is therefore that of specifying an improved method for producing an anodized aluminum article, by means of which anodized aluminum articles having specific properties, such as having particularly matte and non-reflective surfaces, can be produced in an efficiently reproducible manner.
The object is achieved by a method for producing an anodized aluminum article according to claim 1. The claims dependent thereon relate to possible embodiments of the method.
A first aspect of the invention relates to a method for producing at least one anodized aluminum article. The method and/or the individual method steps thus serve for producing at least one anodized aluminum article. An anodized aluminum article is in general to be understood as an aluminum article, e.g. in the form of a technical component, the surface of which is formed at least in portions, optionally completely, by an aluminum oxide layer formed in the context of an electromechanical anodizing process, or comprises such a layer. Of course, a plurality of anodized aluminum articles can be produced by means of the method, in particular in simultaneous or temporally staggered succession.
An anodized aluminum article that can be or is produced according to the method may be a semifinished product or a finished product; as a semifinished product, the anodized aluminum article can undergo one or more post-processing steps in order to convert the semifinished product into a finished product.
The essential steps of the method will be explained in detail in the following. It is significant in this case that the inventors have developed a particular succession or sequence of method or process steps, in particular having associated process parameters, which surprisingly makes it possible, in contrast to known anodizing processes, to produce anodized aluminum articles having particular properties, i.e. having particularly matte or non-reflective surfaces, in an efficiently reproducible manner. Thus, what is essential for the principle described herein is firstly the specific succession or sequence of different method or process steps in which certain method or process steps are carried out multiple times, which steps surprisingly result in the producibility of anodized aluminum articles having specific properties, i.e. in particular having particularly matte or non-reflective surfaces.
A first method step typically provides a pickling step or pickling process of a provided aluminum substrate in a pickling bath which contains a pickling solution, i.e. in particular an aqueous pickling solution. In a first method step, a continuously or discontinuously provided, e.g. strip-like or strip-shaped, aluminum substrate undergoes a pickling step or pickling process in a pickling bath containing a pickling solution. The result of carrying out the first method step is a pickled aluminum substrate. The pickling serves to prepare the aluminum substrate for the subsequent anodizing step or anodizing process. The first method step can be carried out in a pickling device which comprises a pickling bath containing a corresponding pickling solution.
Of course, a plurality of aluminum substrates can be provided in the first method step, which substrates undergo a pickling step or pickling process in a corresponding step of the method. It is the case in general that, even if the method is described in the following in connection with an aluminum substrate, similar of course also applies for a plurality of aluminum substrates. Therefore, a plurality of aluminum substrates can be treated or processed in each step of the method, in particular simultaneously.
A second method step provides a first rinsing step of the pickled aluminum substrate in a first rinsing bath which contains a first rinsing solution, i.e. in particular a first aqueous rinsing solution. In the second method step, typically immediately following the first method step, the pickled aluminum substrate accordingly undergoes a first rinsing step or rinsing process in a first rinsing bath containing a first rinsing solution. The result of carrying out the second method step is a rinsed aluminum substrate; the aluminum substrate is largely freed of the pickling solution after the first rinsing step or rinsing process, which pickling solution would have a negative effect on the following method or process steps. The second method step can be carried out in a first rinsing device which comprises a first rinsing bath containing a corresponding first rinsing solution.
A third method step provides a second rinsing step of the pickled aluminum substrate, rinsed in the first rinsing bath, in a second rinsing bath, which contains a second rinsing solution, i.e. in particular a second aqueous rinsing solution. In the third method step, typically immediately following the second method step, the pickled aluminum substrate, rinsed in the first rinsing bath, accordingly undergoes a second rinsing step or rinsing process in a second rinsing bath containing a second rinsing solution. The result of carrying out the third method step is a particularly thoroughly rinsed aluminum substrate; the aluminum substrate is typically (virtually) completely freed of the pickling solution after the third rinsing step or rinsing process, which pickling solution would, as mentioned, have a negative effect on the following method or process steps. The third method step can be carried out in a second rinsing device which comprises a second rinsing bath containing a corresponding second rinsing solution.
A fourth method step provides a descaling step of the aluminum substrate, rinsed in the second rinsing bath, in a descaling bath, which contains a descaling solution, i.e. in particular an aqueous descaling solution. In the fourth method step, typically immediately following the third method step, the pickled aluminum substrate, rinsed in the first and second rinsing bath, accordingly undergoes a descaling step or descaling process in a descaling bath containing a descaling solution. The result of carrying out the fourth method step is a descaled aluminum substrate. The descaling serves to prepare the aluminum substrate for the subsequent anodizing step or anodizing process. The fourth method step can be carried out in a descaling device which comprises a descaling bath containing a corresponding descaling solution.
A fifth method step provides a third rinsing step of the descaled aluminum substrate in a third rinsing bath which contains a third rinsing solution, i.e. in particular a third aqueous rinsing solution. In the fifth method step, typically immediately following the fourth method step, the descaled aluminum substrate accordingly undergoes a third rinsing step or rinsing process in a third rinsing bath containing a third rinsing solution. The result of carrying out the fifth method step is a rinsed descaled aluminum substrate; the aluminum substrate is largely freed of the descaling solution after the third rinsing step or rinsing process, which descaling solution would have a negative effect on the following method or process steps. The fifth method step can be carried out in a third rinsing device which comprises a third rinsing bath containing a corresponding third rinsing solution.
A sixth method step provides a fourth rinsing step of the descaled aluminum substrate, rinsed in the third rinsing bath, in a fourth rinsing bath which contains a fourth rinsing solution, i.e. in particular a fourth aqueous rinsing solution. In the sixth method step, typically immediately following the fifth method step, the descaled aluminum substrate, rinsed in the third rinsing bath, accordingly undergoes a fourth rinsing step or rinsing process in a fourth rinsing bath containing a fourth rinsing solution. The result of carrying out the sixth method step is a particularly thoroughly rinsed aluminum substrate; the aluminum substrate is typically (virtually) completely freed of the descaling solution after the fourth rinsing step or rinsing process, which descaling solution would, as mentioned, have a negative effect on the following method or process steps. The sixth method step can be carried out in a fourth rinsing device which comprises a fourth rinsing bath containing a corresponding fourth rinsing solution.
A seventh method step now provides at least one anodizing step in at least one anodizing bath which contains an anodizing solution, i.e. in particular an aqueous anodizing solution, as a result of which an anodized aluminum article is formed from the aluminum substrate. In the seventh method step, typically immediately following the sixth method step, the descaled aluminum substrate, rinsed in the third and fourth rinsing bath, accordingly undergoes an anodizing step or anodizing process in an anodizing bath containing an anodizing solution. The result of carrying out the seventh method step is an anodized aluminum article having a particularly matte and non-reflective surface. The seventh method step can be carried out in an anodizing device which comprises an anodizing bath containing a corresponding anodizing solution.
In the anodizing step or process, the aluminum substrate can be connected as the anode, and a, for example trough-like or trough-shaped, container receiving the anodizing solution, acting as the electrolyte, is connected as the cathode, as a result of which, when corresponding electrical voltages are applied to the aluminum substrate forming the anode and the container forming the cathode, oxygen is produced at the surface of the aluminum substrate, which oxygen reacts, at the surface of the aluminum substrate, with aluminum ions, to form aluminum oxide, and thus forms an aluminum oxide layer on the surface of the aluminum substrate and/or converts the surface of the aluminum substrate into an aluminum oxide layer. The anodizing step or process thus includes electrochemical procedures for forming a corresponding aluminum oxide layer.
An eighth method step provides at least one further rinsing step in at least one further rinsing bath which contains a further rinsing solution, i.e. in particular a further aqueous rinsing solution. In the eighth method step, typically immediately following the seventh method step, the anodized aluminum article accordingly undergoes at least one further rinsing step or rinsing process in at least one further rinsing bath containing a further rinsing solution. The result of carrying out the eighth method step is a rinsed anodized aluminum article; the anodized aluminum article is typically (largely) completely freed of the anodizing solution after the at least one further rinsing step or rinsing process. The eighth method step can be carried out in at least one further rinsing device which comprises a further rinsing bath containing a corresponding further rinsing solution.
It is thus notable that the aluminum substrate was rinsed, prior to the actual anodizing step or process, in a plurality of separate rinsing baths or rinsing solutions, such that substances possibly harmful for the anodizing step or process and the associated anodizing result were removed from the aluminum substrate. Furthermore, as emerges in the following, it is notable that the aluminum substrate can be anodized in a plurality of separate anodizing baths, which results in specific surface properties of the aluminum article that is to be produced or is produced.
The described succession or sequence of the method steps enables an efficient, reproducible production of anodized aluminum articles having specific properties, i.e. in particular having particularly matte and non-reflective surfaces. The anodized aluminum article produced according to the method thus comprises a matt, non-reflective surface.
Overall, an improved method for producing an anodized aluminum article is provided.
All the method steps can be carried out in an at least partially, optionally completely, automatable or automatic manner. A facility designed for carrying out the method can comprise devices for this purpose, i.e. in particular pickling devices, rinsing devices, descaling devices, and anodizing devices, which enable the method step to be carried out in an at least partially, optionally completely, automatable or automatic manner. The operation of respective devices can be controlled via a controller implemented in a hardware-based and/or software-based manner, which controller is designed for generating control information for controlling the operation of respective devices, and which communicates with the respective devices, i.e. in particular the control devices associated with the respective devices.
Before the pickling step in the pickling bath, a degreasing step of the provided aluminum substrate can be carried out for degreasing the aluminum substrate. The degreasing of the aluminum substrate typically leads to a better pickling result, since organic substances can be removed from the aluminum substrate at least in part, optionally completely.
The degreasing step can be carried out by means of dipping the provided aluminum substrate one or more times, at least in portions, in particular completely, into a degreasing bath which contains a degreasing solution. The aluminum substrate can thus be introduced into a corresponding degreasing bath, at least in portions, in particular completely, for example by means of dipping. The aluminum substrate that is introduced into the degreasing bath in a corresponding manner can be moved in the degreasing bath. Alternatively the aluminum substrate that is introduced into the degreasing bath in a corresponding manner cannot be moved in the degreasing bath.
A degreasing bath which contains an alkali degreasing solution can be used. On the basis of tests, it has been possible to demonstrate that an alkali degreasing solution is particularly expedient for the properties, sought according to the method, of the anodized aluminum article to be produced. An alkali degreasing solution can for example be a degreasing solution available under the trade name “Alficlean”, which is available for example from the company Alufinish GmbH & Co. KG, 56626 Andernach (DE). In particular, the degreasing solutions available under the trade names “Alficlean 150”, “Alficlean 154/4” or “Alficlean 155” are possible.
The degreasing step can be carried out for a time duration of between 1 and 60 min, in particular between 5 and 30 min. The degreasing step can thus be carried out for 1 min, for 2 min, for 3 min, for 4 min, for 5 min, for 6 min, for 7 min, for 8 min, for 9 min, for 10 min, for 11 min, for 12 min, for 13 min, for 14 min, for 15 min, for 16 min, for 17 min, for 18 min, for 19 min, for 20 min, for 21 min, for 22 min, for 23 min, for 24 min, for 25 min, for 26 min, for 27 min, for 28 min, for 29 min, for 30 min, for 31 min, for 32 min, for 33 min, for 34 min, for 35 min, for 36 min, for 37 min, for 38 min, for 39 min, for 40 min, for 41 min, for 42 min, for 43 min, for 44 min, for 45 min, for 46 min, for 47 min, for 48 min, for 49 min, for 50 min, for 51 min, for 52 min, for 53 min, for 54 min, for 55 min, for 56 min, for 57 min, for 58 min, for 59 min, for 60 min. Even if not explicitly listed, intermediate values, such as 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min or 1.9 min can also be used for each of the time durations listed above. In principle, it is also conceivable for the degreasing step to be carried out for a time duration of less than 1 min or more than 60 min. The specific selection of the time duration of the degreasing step results in particular from the chemical composition of the aluminum substrate provided, and its surface condition prior to the degreasing step. The term “surface condition” is to mean understood in particular to mean the presence of e.g. organic foreign substances of impurities on the surface of the aluminum substrate.
Alternatively or in addition to the chemical degreasing described above, in principle mechanical degreasing steps are also conceivable.
After the degreasing step, but before the pickling step, a pre-rinsing step of the degreased aluminum substrate can be carried out in the first rinsing bath which contains the first rinsing solution. The pre-rinsing step can be carried out by means of dipping the degreased aluminum substrate one or more times, at least in portions, in particular completely, into the first rinsing bath. The pre-rinsing step can thus be kept comparatively short, which is beneficial for the efficiency of the method.
According to the method, a pickling bath which contains an alkali pickling solution can be used. The pH of the pickling solution is thus typically, optionally significantly, above 7. On the basis of tests, it has been possible to demonstrate that an alkali pickling bath is particularly expedient for the properties, sought according to the method, of the anodized aluminum article to be produced.
The pickling step can in generally be carried out as a matte pickling step. A pickling step in the variant E6 or E0 according to DIN 17611 is also conceivable, for example. In particular, a pickling step in the variant E6 according to DIN EN 17611 takes place, since, depending on the treatment time and surface structure of the aluminum substrate, a very uniformly matte to satin-gloss surface can furthermore be achieved by this variant.
According to the variant, in particular an alkali pickling solution which contains caustic soda, aluminum, and at least one pickling additive can be used.
In particular, according to the method an alkali pickling solution can be used, which contains caustic soda in a concentration between 20 and 90 g/l, in particular between 30 and 80 g/l, more particularly between 40 and 70 g/l, more particularly between 50 and 60 g/l; aluminum in a concentration between 20 and 90 g/l, in particular between 30 and 80 g/l, more particularly between 40 and 70 g/l, more particularly between 50 and 60 g/l; and a pickling additive in a concentration between 1 and 20 g/l, in particular between 5 and 15 g/l.
An alkali pickling solution used according to the method can thus contain caustic soda in one of the following concentrations: 20 g/l, 21 g/l, 22 g/l, 23 g/l, 24 g/l, 25 g/l, 26 g/l, 27 g/l, 28 g/l, 29 g/l, 30 g/l, 31 g/l, 32 g/l, 33 g/l, 34 g/l, 35 g/l, 36 g/l, 37 g/l, 38 g/l, 39 g/l, 40 g/l, 41 g/l, 42 g/l, 43 g/l, 44 g/l, 45 g/l, 46 g/l, 47 g/l, 48 g/l, 49 g/l, 50 g/l, 51 g/l, 52 g/l, 53 g/l, 54 g/l, 55 g/l, 56 g/l, 57 g/l, 58 g/l, 59 g/l, 60 g/l, 61 g/l, 62 g/l, 63 g/l, 64 g/l, 65 g/l, 66 g/l, 67 g/l, 68 g/l, 69 g/l, 70 g/l, 71 g/l, 72 g/l, 73 g/l, 74 g/l, 75 g/l, 76 g/l, 77 g/l, 78 g/l, 79 g/l, 80 g/l, 81 g/l, 82 g/l, 83 g/l, 84 g/l, 85 g/l, 86 g/l, 87 g/l, 88 g/l, 89 g/l, 90 g/l. In principle, the caustic soda can also be present in a concentration of less than 20 g/l or over 90 g/l.
An alkali pickling solution used according to the method can thus contain aluminum, e.g. in the form of one or more aluminum salts, in one of the following concentrations: 20 g/l, 21 g/l, 22 g/l, 23 g/l, 24 g/l, 25 g/l, 26 g/l, 27 g/l, 28 g/l, 29 g/l, 30 g/l, 31 g/l, 32 g/l, 33 g/l, 34 g/l, 35 g/l, 36 g/l, 37 g/l, 38 g/l, 39 g/l, 40 g/l, 41 g/l, 42 g/l, 43 g/l, 44 g/l, 45 g/l, 46 g/l, 47 g/l, 48 g/l, 49 g/l, 50 g/l, 51 g/l, 52 g/l, 53 g/l, 54 g/l, 55 g/l, 56 g/l, 57 g/l, 58 g/l, 59 g/l, 60 g/l, 61 g/l, 62 g/l, 63 g/l, 64 g/l, 65 g/l, 66 g/l, 67 g/l, 68 g/l, 69 g/l, 70 g/l, 71 g/l, 72 g/l, 73 g/l, 74 g/l, 75 g/l, 76 g/l, 77 g/l, 78 g/l, 79 g/l, 80 g/l, 81 g/l, 82 g/l, 83 g/l, 84 g/l, 85 g/l, 86 g/l, 87 g/l, 88 g/l, 89 g/l, 90 g/l. In principle, the aluminum can also be present in a concentration of less than 20 g/l or over 90 g/l.
An alkali pickling solution used according to the method can thus contain a pickling additive in one of the following concentrations: 1 g/l, 2 g/1.3 g/l, 4 g/l, 5 g/l, 6 g/l, 7 g/l, 8 g/l, 9 g/l, 10 g/l, 11 g/l, 12 g/l, 13 g/l, 14 g/l, 15 g/l, 16 g/l, 17 g/l, 18 g/l, 19 g/l, 20 g/l. In principle, the pickling additive can also be present in a concentration of less than 1 g/l or over 20 g/l.
According to the method, a pickling additive can be used which reduces or prevents pickling process-related foaming; and/or a pickling additive is used which influences, i.e. in particular improves, the viscosity of the pickling solution; and/or a pickling additive is used which influences, i.e. in particular improves, the drag-out rate of the pickling solution. A corresponding pickling additive can for example be a pickling additive available under the trade name “Alfisatin”, which is available for example from the company Alufinish GmbH & Co. KG, 56626 Andernach (DE). In particular, pickling additives available under the trade names “Alfisatin 338”, “Alfisatin 339/4”, “Alfisatin 357” or “Alfisatin 358/1” are possible.
In all the embodiments the pickling step can be carried out for a time duration of between 1 and 60 min, in particular between 5 and 30 min. The pickling step can thus be carried out for 1 min, for 2 min, for 3 min, for 4 min, for 5 min, for 6 min, for 7 min, for 8 min, for 9 min, for 10 min, for 11 min, for 12 min, for 13 min, for 14 min, for 15 min, for 16 min, for 17 min, for 18 min, for 19 min, for 20 min, for 21 min, for 22 min, for 23 min, for 24 min, for 25 min, for 26 min, for 27 min, for 28 min, for 29 min, for 30 min, for 31 min, for 32 min, for 33 min, for 34 min, for 35 min, for 36 min, for 37 min, for 38 min, for 39 min, for 40 min, for 41 min, for 42 min, for 43 min, for 44 min, for 45 min, for 46 min, for 47 min, for 48 min, for 49 min, for 50 min, for 51 min, for 52 min, for 53 min, for 54 min, for 55 min, for 56 min, for 57 min, for 58 min, for 59 min, for 60 min. Even if not explicitly listed, intermediate values, such as 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min or 1.9 min can also be used for each of the time durations listed above. In principle, it is conceivable for the pickling step to also be carried out, in exceptional cases, for a time duration of less than 1 min or more than 60 min.
According to the method, a first second rinsing bath which contains process or fresh water as the rinsing solution can be used. The first rinsing step can be carried out by means of dipping the pickled aluminum substrate one or more times, at least in portions, in particular completely, into the first rinsing bath which contains the first rinsing solution. The aluminum substrate can thus be introduced into the first rinsing bath, at least in portions, in particular completely, for example by means of dipping. The aluminum substrate that is introduced into the first rinsing bath in a corresponding manner can be moved in the first rinsing bath. Alternatively the aluminum substrate that is introduced into the first rinsing bath in a corresponding manner cannot be moved in the first rinsing bath.
In an analogous manner, according to the method a second rinsing bath which contains process or fresh water as the rinsing solution can be used. The second rinsing step can be carried out by means of dipping the pickled aluminum substrate one or more times, at least in portions, in particular completely, into the second rinsing bath which contains the second rinsing solution. The aluminum substrate can thus be introduced into the second rinsing bath, at least in portions, in particular completely, for example by means of dipping. The aluminum substrate that is introduced into the second rinsing bath in a corresponding manner can be moved in the second rinsing bath. Alternatively the aluminum substrate that is introduced into the second rinsing bath in a corresponding manner cannot be moved in the second rinsing bath.
The first rinsing step and/or the second rinsing step can (in each case) be carried out for a time duration of between 1 and 90 sec, in particular between 5 and 30 sec. The first rinsing step and/or the second rinsing step can thus be carried out for 1 sec, for 2 sec, for 3 sec, for 4 sec, for 5 sec, for 6 sec, for 7 sec, for 8 sec, for 9 sec, for 10 sec, for 11 sec, for 12 sec, for 13 sec, for 14 sec, for 15 sec, for 16 sec, for 17 sec, for 18 sec, for 19 sec, for 20 sec, for 21 sec, for 22 sec, for 23 sec, for 24 sec, for 25 sec, for 26 sec, for 27 sec, for 28 sec, for 29 sec, for 30 sec, for 31 sec, for 32 sec, for 33 sec, for 34 sec, for 35 sec, for 36 sec, for 37 sec, for 38 sec, for 39 sec, for 40 sec, for 41 sec, for 42 sec, for 43 sec, for 44 sec, for 45 sec, for 46 sec, for 47 sec, for 48 sec, for 49 sec, for 50 sec, for 51 sec, for 52 sec, for 53 sec, for 54 sec, for 55 sec, for 56 sec, for 57 sec, for 58 sec, for 59 sec, for 60 sec, for 61 sec, for 62 sec, for 63 sec, for 64 sec, for 65 sec, for 66 sec, for 67 sec, for 68 sec, for 69 sec, for 70 sec, for 71 sec, for 72 sec, for 73 sec, for 74 sec, for 75 sec, for 76 sec, for 77 sec, for 78 sec, for 79 sec, for 80 sec, for 81 sec, for 82 sec, for 83 sec, for 84 sec, for 85 sec, for 86 sec, for 87 sec, for 88 sec, for 89 sec, for 90 sec. Even if not explicitly listed, intermediate values, such as 1.1 sec, 1.2 sec, 1.3 sec, 1.4 sec, 1.5 sec, 1.6 sec, 1.7 sec, 1.8 sec or 1.9 sec can also be used for each of the time durations listed above. In principle, it is conceivable for the first rinsing step and/or the second rinsing step to also be carried out, in exceptional cases, for a time duration of less than 1 sec or more than 90 sec.
According to the method, a descaling bath which contains an acidic descaling solution can be used. The pH of the descaling solution is thus typically, optionally significantly, below 7. On the basis of tests, it has been possible to demonstrate that an acidic descaling bath is particularly expedient for the properties, sought according to the method, of the anodized aluminum article to be produced.
According to the method, for example an acidic descaling solution which contains nitric acid, hydrochloric acid, or sulfuric acid can be used.
In particular, according to the method an acidic descaling solution is used, which contains nitric acid, hydrochloric acid, or sulfuric acid in a concentration between 50 and 400 g/l, in particular between 100 and 350 g/l, more particularly between 150 and 300 g/l, more particularly between 200 and 250 g/l.
An acidic descaling solution used according to the method can thus contain nitric acid or hydrochloric acid or sulfuric acid in one of the following concentrations: 51 g/l, 52 g/l, 53 g/l, 54 g/l, 55 g/l, 56 g/l, 57 g/l, 58 g/l, 59 g/l, 60 g/l, 61 g/l, 62 g/l, 63 g/l, 64/l, 65 g/l, 66 g/l, 67 g/l, 68 g/l, 69 g/l, 70 g/l, 71 g/l, 72 g/l, 73 g/l, 74 g/l, 75 g/l, 76 g/l, 77 g/l, 78/l, 79 g/l, 80 g/l, 81 g/l, 82 g/l, 83 g/l, 84 g/l, 85 g/l, 86 g/l, 87 g/l, 88 g/l, 89 g/l, 90 g/l, 91 g/l, 92/l, 93 g/l, 94 g/l, 95 g/l, 96 g/l, 97 g/l, 98 g/l, 99 g/l, 100 g/l, 101 g/l, 102 g/l, 103 g/l, 104 g/l, 105/l, 106 g/l, 107 g/l, 108 g/l, 109 g/l, 110 g/l, 111 g/l, 112 g/l, 113 g/l, 114 g/l, 115 g/l, 116 g/l, 117 g/l, 118 g/l, 119 g/l, 120 g/l, 121 g/l, 122 g/l, 123 g/l, 124 g/l, 125 g/l, 126 g/l, 127 g/l, 128/l, 129 g/l, 130 g/l, 131 g/l, 132 g/l, 133 g/l, 134 g/l, 135 g/l, 136 g/l, 137 g/l, 138 g/l, 139 g/l, 140 g/l, 141 g/l, 142 g/l, 143 g/l, 144 g/l, 145 g/l, 146 g/l, 147 g/l, 148 g/l, 149 g/l, 150 g/l, 151/l, 152 g/l, 153 g/l, 154 g/l, 155 g/l, 156 g/l, 157 g/l, 158 g/l, 159 g/l, 160 g/l, 161 g/l, 162 g/l, 163 g/l, 164 g/l, 165 g/l, 166 g/l, 167 g/l, 168 g/l, 169 g/l, 170 g/l, 171 g/l, 172 g/l, 173 g/l, 174/l, 175 g/l, 176 g/l, 177 g/l, 178 g/l, 179 g/l, 180 g/l, 181 g/l, 182 g/l, 183 g/l, 184 g/l, 185 g/l, 186 g/l, 187 g/l, 188 g/l, 189 g/l, 190 g/l, 191 g/l, 192 g/l, 193 g/l, 194 g/l, 195 g/l, 196 g/l, 197/l, 198 g/l, 199 g/l, 200 g/l, 201 g/l, 202 g/l, 203 g/l, 204 g/l, 205 g/l, 206 g/l, 207 g/l, 208 g/l, 209 g/l, 210 g/l, 211 g/l, 212 g/l, 213 g/l, 214 g/l, 215 g/l, 216 g/l, 217 g/l, 218 g/l, 219 g/l, 220/l, 221 g/l, 222 g/l, 223 g/l, 224 g/l, 225 g/l, 226 g/l, 227 g/l, 228 g/l, 229 g/l, 230 g/l, 231 g/l, 232 g/l, 233 g/l, 234 g/l, 235 g/l, 236 g/l, 237 g/l, 238 g/l, 239 g/l, 240 g/l, 241 g/l, 242 g/l, 243/l, 244 g/l, 245 g/l, 246 g/l, 247 g/l, 248 g/l, 249 g/l, 250 g/l, 251 g/l, 252 g/l, 253 g/l, 254 g/l, 255 g/l, 256 g/l, 257 g/l, 258 g/l, 259 g/l, 260 g/l, 261 g/l, 262 g/l, 263 g/l, 264 g/l, 265 g/l, 266/l, 267 g/l, 268 g/l, 269 g/l, 270 g/l, 271 g/l, 272 g/l, 273 g/l, 274 g/l, 275 g/l, 276 g/l, 277 g/l, 278 g/l, 279 g/l, 280 g/l, 281 g/l, 282 g/l, 283 g/l, 284 g/l, 285 g/l, 286 g/l, 287 g/l, 288 g/l, 289/l, 290 g/l, 291 g/l, 292 g/l, 293 g/l, 294 g/l, 295 g/l, 296 g/l, 297 g/l, 298 g/l, 299 g/l, 300 g/l, 301 g/l, 302 g/l, 303 g/l, 304 g/l, 305 g/l, 306 g/l, 307 g/l, 308 g/l, 309 g/1, 310 g/l, 311 g/l, 312/l, 313 g/l, 314 g/1, 315 g/1, 316 g/1, 317 g/1, 318 g/1, 319 g/l, 320 g/l, 321 g/l, 322 g/l, 323 g/l, 324 g/l, 325 g/l, 326 g/l, 327 g/l, 328 g/l, 329 g/l, 330 g/l, 331 g/l, 332 g/l, 333 g/l, 334 g/l, 335/l, 336 g/l, 337 g/l, 338 g/l, 339 g/l, 340 g/l, 341 g/l, 342 g/l, 343 g/l, 344 g/l, 345 g/l, 346 g/l, 347 g/l, 348 g/l, 349 g/l, 350 g/l, 351 g/l, 352 g/l, 353 g/l, 354 g/l, 355 g/l, 356 g/l, 357 g/l, 358/l, 359 g/l, 360 g/l, 361 g/l, 362 g/l, 363 g/l, 364 g/l, 365 g/l, 366 g/l, 367 g/l, 368 g/l, 369 g/l, 370 g/l, 371 g/l, 372 g/l, 373 g/l, 374 g/l, 375 g/l, 376 g/l, 377 g/l, 378 g/l, 379 g/l, 380 g/l, 381/l, 382 g/l, 383 g/l, 384 g/l, 385 g/l, 386 g/l, 387 g/l, 388 g/l, 389 g/l, 390 g/l, 391 g/l, 392 g/l, 393 g/l, 394 g/l, 395 g/l, 396 g/l, 397 g/l, 398 g/l, 399 g/l, 400 g/l. In principle, in exceptional cases, the nitric acid, hydrochloric acid or sulfuric acid can also be present in a concentration of less than 50 g/l or above 400 g/l.
According to the method, the descaling step can be carried out for a time duration of between 1 and 60 min, in particular between 5 and 30 min. The descaling step can thus be carried out for 1 min, for 2 min, for 3 min, for 4 min, for 5 min, for 6 min, for 7 min, for 8 min, for 9 min, for 10 min, for 11 min, for 12 min, for 13 min, for 14 min, for 15 min, for 16 min, for 17 min, for 18 min, for 19 min, for 20 min, for 21 min, for 22 min, for 23 min, for 24 min, for 25 min, for 26 min, for 27 min, for 28 min, for 29 min, for 30 min, for 31 min, for 32 min, for 33 min, for 34 min, for 35 min, for 36 min, for 37 min, for 38 min, for 39 min, for 40 min, for 41 min, for 42 min, for 43 min, for 44 min, for 45 min, for 46 min, for 47 min, for 48 min, for 49 min, for 50 min, for 51 min, for 52 min, for 53 min, for 54 min, for 55 min, for 56 min, for 57 min, for 58 min, for 59 min, for 60 min. Even if not explicitly listed, intermediate values, such as 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min or 1.9 min can also be used for each of the time durations listed above. In principle, it is conceivable for the descaling step to also be carried out, in exceptional cases, for a time duration of less than 1 min or more than 60 min.
According to the method, a third rinsing bath which contains process or fresh water as the rinsing solution can be used. The third rinsing step can be carried out by means of dipping the descaled aluminum substrate one or more times, at least in portions, in particular completely, into the third rinsing bath which contains the third rinsing solution. The aluminum substrate can thus be introduced into the third rinsing bath, at least in portions, in particular completely, for example by means of dipping. The aluminum substrate that is introduced into the third rinsing bath in a corresponding manner can be moved in the third rinsing bath. Alternatively the aluminum substrate that is introduced into the third rinsing bath in a corresponding manner cannot be moved in the third rinsing bath.
In an analogous manner, according to the method a fourth rinsing bath which contains process or fresh water as the rinsing solution can be used. The fourth rinsing step can be carried out by means of dipping the descaled aluminum substrate one or more times, at least in portions, in particular completely, into the fourth rinsing bath which contains the fourth rinsing solution. The aluminum substrate can thus be introduced into the fourth rinsing bath, at least in portions, in particular completely, for example by means of dipping. The aluminum substrate that is introduced into the fourth rinsing bath in a corresponding manner can be moved in the fourth rinsing bath. Alternatively the aluminum substrate that is introduced into the fourth rinsing bath in a corresponding manner cannot be moved in the fourth rinsing bath.
The third rinsing step and/or the fourth rinsing step can (in each case) be carried out for a time duration of between 1 and 90 sec, in particular between 5 and 30 sec. The third rinsing step and/or the fourth rinsing step can thus be carried out for 1 sec, for 2 sec, for 3 sec, for 4 sec, for 5 sec, for 6 sec, for 7 sec, for 8 sec, for 9 sec, for 10 sec, for 11 sec, for 12 sec, for 13 sec, for 14 sec, for 15 sec, for 16 sec, for 17 sec, for 18 sec, for 19 sec, for 20 sec, for 21 sec, for 22 sec, for 23 sec, for 24 sec, for 25 sec, for 26 sec, for 27 sec, for 28 sec, for 29 sec, for 30 sec, for 31 sec, for 32 sec, for 33 sec, for 34 sec, for 35 sec, for 36 sec, for 37 sec, for 38 sec, for 39 sec, for 40 sec, for 41 sec, for 42 sec, for 43 sec, for 44 sec, for 45 sec, for 46 sec, for 47 sec, for 48 sec, for 49 sec, for 50 sec, for 51 sec, for 52 sec, for 53 sec, for 54 sec, for 55 sec, for 56 sec, for 57 sec, for 58 sec, for 59 sec, for 60 sec, for 61 sec, for 62 sec, for 63 sec, for 64 sec, for 65 sec, for 66 sec, for 67 sec, for 68 sec, for 69 sec, for 70 sec, for 71 sec, for 72 sec, for 73 sec, for 74 sec, for 75 sec, for 76 sec, for 77 sec, for 78 sec, for 79 sec, for 80 sec, for 81 sec, for 82 sec, for 83 sec, for 84 sec, for 85 sec, for 86 sec, for 87 sec, for 88 sec, for 89 sec, for 90 sec. Even if not explicitly listed, intermediate values, such as 1.1 sec, 1.2 sec, 1.3 sec, 1.4 sec, 1.5 sec, 1.6 sec, 1.7 sec, 1.8 sec or 1.9 sec can also be used for each of the time durations listed above. In principle, it is conceivable for the third rinsing step and/or the fourth rinsing step to also be carried out, in exceptional cases, for a time duration of less than 1 sec or more than 90 sec.
According to the method, at least one anodizing bath which contains an acidic anodizing solution can be used. The pH of the anodizing solution is thus typically, optionally significantly, below 7. On the basis of tests, it has been possible to demonstrate that an acidic anodizing bath is particularly expedient for the properties, sought according to the method, of the anodized aluminum article to be produced.
According to the method, for example an acidic anodizing solution which contains aluminum, e.g. in the form of one or more aluminum salts, in particular aluminum sulphate, and sulfuric acid, can be used.
In particular, according to the method, an acidic anodizing solution which contains aluminum, e.g. in the form of one or more aluminum salts, such as aluminum sulphate (Al2(SO4)3 or Al2(SO4)2), and sulfuric acid, can be used. The sulfuric acid can be present in a concentration between 100 and 350 g/l, in particular the concentration of the sulfuric acid can be between 140 and 200 g/l, more particularly between 150 and 190 g/l. The aluminum or the aluminum salt can be present in a concentration between 10 and 80 g/l, in particular between 10 and 50 g/l, more particularly between 10 and 45 g/l, more particularly between 10 and 40 g/l, more particularly between 10 and 35 g/l, more particularly between 10 and 30 g/l.
An acidic anodizing solution used according to the method can thus contain sulfuric acid in one of the following concentrations: 51 g/l, 52 g/l, 53 g/l, 54 g/l, 55 g/l, 56 g/l, 57 g/l, 58 g/l, 59 g/l, 60 g/l, 61 g/l, 62 g/l, 63 g/l, 64/l, 65 g/l, 66 g/l, 67 g/l, 68 g/l, 69 g/l, 70 g/l, 71 g/l, 72 g/l, 73 g/l, 74 g/l, 75 g/l, 76 g/l, 77 g/l, 78/l, 79 g/l, 80 g/l, 81 g/l, 82 g/l, 83 g/l, 84 g/l, 85 g/l, 86 g/l, 87 g/l, 88 g/l, 89 g/l, 90 g/l, 91 g/l, 92/l, 93 g/l, 94 g/l, 95 g/l, 96 g/l, 97 g/l, 98 g/l, 99 g/l, 100 g/l, 101 g/l, 102 g/l, 103 g/l, 104 g/l, 105/l, 106 g/l, 107 g/l, 108 g/l, 109 g/l, 110 g/l, 111 g/l, 112 g/l, 113 g/l, 114 g/l, 115 g/l, 116 g/l, 117 g/l, 118 g/l, 119 g/l, 120 g/l, 121 g/l, 122 g/l, 123 g/l, 124 g/l, 125 g/l, 126 g/l, 127 g/l, 128/l, 129 g/l, 130 g/l, 131 g/l, 132 g/l, 133 g/l, 134 g/l, 135 g/l, 136 g/l, 137 g/l, 138 g/l, 139 g/l, 140 g/l, 141 g/l, 142 g/l, 143 g/l, 144 g/l, 145 g/l, 146 g/l, 147 g/l, 148 g/l, 149 g/l, 150 g/l, 151/l, 152 g/l, 153 g/l, 154 g/l, 155 g/l, 156 g/l, 157 g/l, 158 g/l, 159 g/l, 160 g/l, 161 g/l, 162 g/l, 163 g/l, 164 g/l, 165 g/l, 166 g/l, 167 g/l, 168 g/l, 169 g/l, 170 g/l, 171 g/l, 172 g/l, 173 g/l, 174/l, 175 g/l, 176 g/l, 177 g/l, 178 g/l, 179 g/l, 180 g/l, 181 g/l, 182 g/l, 183 g/l, 184 g/l, 185 g/l, 186 g/l, 187 g/l, 188 g/l, 189 g/l, 190 g/l, 191 g/l, 192 g/l, 193 g/l, 194 g/l, 195 g/l, 196 g/l, 197/l, 198 g/l, 199 g/l, 200 g/l, 201 g/l, 202 g/l, 203 g/l, 204 g/l, 205 g/l, 206 g/l, 207 g/l, 208 g/l, 209 g/l, 210 g/l, 211 g/l, 212 g/l, 213 g/l, 214 g/l, 215 g/l, 216 g/l, 217 g/l, 218 g/l, 219 g/l, 220/l, 221 g/l, 222 g/l, 223 g/l, 224 g/l, 225 g/l, 226 g/l, 227 g/l, 228 g/l, 229 g/l, 230 g/l, 231 g/l, 232 g/l, 233 g/l, 234 g/l, 235 g/l, 236 g/l, 237 g/l, 238 g/l, 239 g/l, 240 g/l, 241 g/l, 242 g/l, 243/l, 244 g/l, 245 g/l, 246 g/l, 247 g/l, 248 g/l, 249 g/l, 250 g/l, 251 g/l, 252 g/l, 253 g/l, 254 g/l, 255 g/l, 256 g/l, 257 g/l, 258 g/l, 259 g/l, 260 g/l, 261 g/l, 262 g/l, 263 g/l, 264 g/l, 265 g/l, 266/l, 267 g/l, 268 g/l, 269 g/l, 270 g/l, 271 g/l, 272 g/l, 273 g/l, 274 g/l, 275 g/l, 276 g/l, 277 g/l, 278 g/l, 279 g/l, 280 g/l, 281 g/l, 282 g/l, 283 g/l, 284 g/l, 285 g/l, 286 g/l, 287 g/l, 288 g/l, 289/l, 290 g/l, 291 g/l, 292 g/l, 293 g/l, 294 g/l, 295 g/l, 296 g/l, 297 g/l, 298 g/l, 299 g/l, 300 g/l, 301 g/l, 302 g/l, 303 g/l, 304 g/l, 305 g/l, 306 g/l, 307 g/l, 308 g/l, 309 g/l, 310 g/l, 311 g/l, 312/l, 313 g/l, 314 g/l, 315 g/l, 316 g/l, 317 g/l, 318 g/l, 319 g/l, 320 g/l, 321 g/l, 322 g/l, 323 g/l, 324 g/l, 325 g/l, 326 g/l, 327 g/l, 328 g/l, 329 g/l, 330 g/l, 331 g/l, 332 g/l, 333 g/l, 334 g/l, 335/l, 336 g/l, 337 g/l, 338 g/l, 339 g/l, 340 g/l, 341 g/l, 342 g/l, 343 g/l, 344 g/l, 345 g/l, 346 g/l, 347 g/l, 348 g/l, 349 g/l, 350 g/l, 351 g/l, 352 g/l, 353 g/l, 354 g/l, 355 g/l, 356 g/l, 357 g/l, 358/l, 359 g/l, 360 g/l, 361 g/l, 362 g/l, 363 g/l, 364 g/l, 365 g/l, 366 g/l, 367 g/l, 368 g/l, 369 g/l, 370 g/l, 371 g/l, 372 g/l, 373 g/l, 374 g/l, 375 g/l, 376 g/l, 377 g/l, 378 g/l, 379 g/l, 380 g/l, 381/l, 382 g/l, 383 g/l, 384 g/l, 385 g/l, 386 g/l, 387 g/l, 388 g/l, 389 g/l, 390 g/l, 391 g/l, 392 g/l, 393 g/l, 394 g/l, 395 g/l, 396 g/l, 397 g/l, 398 g/l, 399 g/l, 400 g/l. In principle, the sulfuric acid can, in exceptional cases, also be present in a concentration of less than 50 g/l or over 400 g/l.
An acidic anodizing solution used according to the method can thus contain aluminum, e.g. in the form of one or more aluminum salts, i.e. in particular aluminum sulphate (Al2(SO4)3 or Al2(SO4)2), in one of the following concentrations: 20 g/l, 21 g/l, 22 g/l, 23 g/l, 24 g/l, 25 g/l, 26 g/l, 27 g/l, 28 g/l, 29 g/l, 30 g/l, 31 g/l, 32 g/l, 33 g/l, 34 g/l, 35 g/l, 36 g/l, 37 g/l, 38 g/l, 39 g/l, 40 g/l, 41 g/l, 42 g/l, 43 g/l, 44 g/l, 45 g/l, 46 g/l, 47 g/l, 48 g/l, 49 g/l, 50 g/l, 51 g/l, 52 g/l, 53 g/l, 54 g/l, 55 g/l, 56 g/l, 57 g/l, 58 g/l, 59 g/l, 60 g/l, 61 g/l, 62 g/l, 63 g/l, 64 g/l, 65 g/l, 66 g/l, 67 g/l, 68 g/l, 69 g/l, 70 g/l, 71 g/l, 72 g/l, 73 g/l, 74 g/l, 75 g/l, 76 g/l, 77 g/l, 78 g/l, 79 g/l, 80 g/l, 81 g/l, 82 g/l, 83 g/l, 84 g/l, 85 g/l, 86 g/l, 87 g/l, 88 g/l, 89 g/l, 90 g/l. In principle, the aluminum can, in exceptional cases, also be present in a concentration of less than 20 g/l or over 90 g/l.
According to the method, the anodizing step can be carried out for a time duration of between 1 and 60 min, in particular between 5 and 30 min. The anodizing step can thus be carried out for 1 min, for 2 min, for 3 min, for 4 min, for 5 min, for 6 min, for 7 min, for 8 min, for 9 min, for 10 min, for 11 min, for 12 min, for 13 min, for 14 min, for 15 min, for 16 min, for 17 min, for 18 min, for 19 min, for 20 min, for 21 min, for 22 min, for 23 min, for 24 min, for 25 min, for 26 min, for 27 min, for 28 min, for 29 min, for 30 min, for 31 min, for 32 min, for 33 min, for 34 min, for 35 min, for 36 min, for 37 min, for 38 min, for 39 min, for 40 min, for 41 min, for 42 min, for 43 min, for 44 min, for 45 min, for 46 min, for 47 min, for 48 min, for 49 min, for 50 min, for 51 min, for 52 min, for 53 min, for 54 min, for 55 min, for 56 min, for 57 min, for 58 min, for 59 min, for 60 min. Even if not explicitly listed, intermediate values, such as 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min or 1.9 min can also be used for each of the time durations listed above. In principle, it is conceivable for the anodizing step to also be carried out, in exceptional cases, for a time duration of less than 1 min or more than 60 min.
According to the method, the anodizing step can contain a plurality of, i.e. in particular at least two, more particularly three or more, separate anodizing sub steps. Therefore, according to the method, the anodizing step can also be carried out in a plurality of separate anodizing baths, each containing an anodizing solution. For each anodizing sub step, the statements above in connection with the chemical composition of the respective anodizing baths, i.e. in particular the concentration of the respective components of the respective anodizing baths, and the time durations, apply analogously.
According to the method, the at least one rinsing step that follows the at least one anodizing step—similar applies for the explained performance of the at least one anodizing step over a plurality of anodizing sub steps—is carried out in at least one further rinsing bath which contains service or fresh water as the rinsing solution. The at least one further rinsing step can be carried out by means of dipping the anodized aluminum article one or more times, at least in portions, in particular completely, into the at least one rinsing bath which contains the at least one further rinsing solution. The anodized aluminum article can thus be introduced into the at least one further rinsing bath, at least in portions, in particular completely, for example by means of dipping. In a corresponding manner, the anodized aluminum article that is introduced into the at least one further rinsing bath in a corresponding manner can be moved in the at least one further rinsing bath. Alternatively, the anodized aluminum article that is introduced into the at least one further rinsing bath in a corresponding manner cannot be moved in the at least one further rinsing bath.
The at least one further rinsing step can be carried out for a time duration of between 1 and 90 sec, in particular between 5 and 30 sec. The at least one further rinsing step can thus be carried out for 1 sec, for 2 sec, for 3 sec, for 4 sec, for 5 sec, for 6 sec, for 7 sec, for 8 sec, for 9 sec, for 10 sec, for 11 sec, for 12 sec, for 13 sec, for 14 sec, for 15 sec, for 16 sec, for 17 sec, for 18 sec, for 19 sec, for 20 sec, for 21 sec, for 22 sec, for 23 sec, for 24 sec, for 25 sec, for 26 sec, for 27 sec, for 28 sec, for 29 sec, for 30 sec, for 31 sec, for 32 sec, for 33 sec, for 34 sec, for 35 sec, for 36 sec, for 37 sec, for 38 sec, for 39 sec, for 40 sec, for 41 sec, for 42 sec, for 43 sec, for 44 sec, for 45 sec, for 46 sec, for 47 sec, for 48 sec, for 49 sec, for 50 sec, for 51 sec, for 52 sec, for 53 sec, for 54 sec, for 55 sec, for 56 sec, for 57 sec, for 58 sec, for 59 sec, for 60 sec, for 61 sec, for 62 sec, for 63 sec, for 64 sec, for 65 sec, for 66 sec, for 67 sec, for 68 sec, for 69 sec, for 70 sec, for 71 sec, for 72 sec, for 73 sec, for 74 sec, for 75 sec, for 76 sec, for 77 sec, for 78 sec, for 79 sec, for 80 sec, for 81 sec, for 82 sec, for 83 sec, for 84 sec, for 85 sec, for 86 sec, for 87 sec, for 88 sec, for 89 sec, for 90 sec. Even if not explicitly listed, intermediate values, such as 1.1 sec, 1.2 sec, 1.3 sec, 1.4 sec, 1.5 sec, 1.6 sec, 1.7 sec, 1.8 sec or 1.9 sec can also be used for each of the time durations listed above. In principle, it is conceivable for the at least one further rinsing step to also be carried out, in exceptional cases, for a time duration of less than 1 sec or more than 90 sec.
In particular, it is expedient to carry out the at least one rinsing step after the anodizing step, i.e. the last rinsing step, in a plurality of, i.e. in particular in at least two, more particularly three, separate rinsing baths, which each contain a rinsing solution. In this case, a first rinsing bath can e.g. contain service or fresh water, in particular service water, as the rinsing solution. A second rinsing bath can also contain service or fresh water, in particular fresh water, as the rinsing solution. A third rinsing bath can contain circulation water, in particular circulation water having a conductivity of less than 50 μS/cm, in particular less than 30 μS/cm, as the rinsing solution.
Depending on the specific process control, the anodized aluminum article can have an aluminum oxide or anodized layer having a layer thickness in a range between 5 and 50 μm, in particular between 10 and 30 μm. Typically, the layer thickness of the aluminum oxide or anodized layer is at least 15 μm. For this purpose, it may be necessary to carry out the anodizing step over a time duration of at least 15 min, in particular at least 20 min, more particularly at least 25 min.
As mentioned, the anodized aluminum article, should this be a semi-finished product, can undergo at least one post-treatment step, in order to produce a finished product from the semi-finished product.
After the last rinsing step, optionally before or after a drying step following the last rinsing step, in which drying step the anodized aluminum article is age-hardened at an increased temperature, in particular a temperature in a range between 50 and 150° C., at least one compression step can be carried out, in which the anodized aluminum article, i.e. in particular the aluminum oxide layer formed by the anodizing step, is compressed in order to reduce any porosity of the aluminum oxide layer that is possibly present.
Alternatively or in addition, after the last rinsing step, optionally after a drying step following the last rinsing step, in which drying step the anodized aluminum article is age-hardened at an increased temperature, in particular a temperature in a range between 50 and 150° C., and/or after a corresponding compression step, at least one post-processing step is carried out, in which the anodized aluminum article is printed for example with alphanumeric symbols, coded or non-coded information, e.g. in the form of barcodes, QR codes, etc., and/or at least one post-processing step takes place, in which anodized aluminum bodies of a defined shaping are separated out of the anodized aluminum article, e.g. by punching or cutting.
It is the case for all the embodiments that, according to the method, an aluminum substrate made of pure aluminum or an aluminum alloy can be provided, and accordingly used as the starting material. The method can thus be carried out using aluminum substrates made of pure aluminum or an aluminum alloy.
If an aluminum substrate made of an aluminum ally is used, in particular an aluminum alloy is possible which, in addition to aluminum, contains at least one alloying element from the group: iron, silicon, copper, manganese, magnesium, chromium, tin or titanium.
In particular, an aluminum alloy can be used which has the following chemical composition, in mass percent: 0.70-1.0 wt. % iron, 0.30-0.50 wt. % silicon, 0.20-0.50 wt. % copper, 0.20-0.50 wt. % manganese, 0.50-1.10 wt. % magnesium, 0.10-0.50 wt. % chromium, 0.25-0.60 wt. % tin and 0-0.30 wt. % titanium. The remainder is made up in each case by aluminum and possible impurities; of course, the mass percentages add up to 100 wt. %.
The degreasing step can be carried out at a temperature in a range between 20 and 80° C., in particular in a range between 25 and 75° C., more particularly in a range between 30 and 70° C., more particularly in a range between 35° C. and 65° C., more particularly between 40° C. and 60° C., more particularly in a range between 45° C. and 55° C. Therefore, the temperature of the degreasing bath can be in a range between 20 and 80° C., in particular between 25 and 75° C., more particularly between 30 and 70° C., more particularly between 35° C. and 65° C., more particularly between 40° C. and 60° C., more particularly between 45° C. and 55° C.
The pickling step can be carried out at a temperature in a range between 30 and 90° C., in particular in a range between 35 and 85° C., more particularly in a range between 40 and 80° C., more particularly in a range between 45° C. and 75° C., more particularly between 50° C. and 70° C., more particularly in a range between 55° C. and 65° C. Therefore, the temperature of the pickling bath can be in a range between 30 and 90° C., in particular in a range between 35 and 85° C., more particularly in a range between 40 and 80° C., more particularly in a range between 45° C. and 75° C., more particularly between 50° C. and 70° C., more particularly in a range between 55° C. and 65° C.
The descaling step can be carried out at a temperature in a range between 0 and 50° C., in particular in a range between 5 and 45° C., more particularly in a range between 10 and 40° C., more particularly in a range between 15° C. and 35° C., more particularly between 15° C. and 30° C., more particularly between 15° C. and 25° C., more particularly between 15° C. and 20° C. Therefore, the temperature of the descaling bath can be in a range between 0 and 50° C., in particular in a range between 5 and 45° C., more particularly in a range between 10 and 40° C., more particularly in a range between 15° C. and 35° C., more particularly between 15° C. and 30° C., more particularly between 15° C. and 25° C., more particularly between 15° C. and 20° C.
The anodizing step can be carried out at a temperature in a range between 0 and 50° C., in particular in a range between 5 and 45° C., more particularly in a range between 10 and 40° C., more particularly in a range between 15° C. and 35° C., more particularly between 15° C. and 30° C., more particularly between 15° C. and 25° C., more particularly between 15° C. and 20° C. Therefore, the temperature of the anodizing bath can be in a range between 0 and 50° C., in particular in a range between 5 and 45° C., more particularly in a range between 10 and 40° C., more particularly in a range between 15° C. and 35° C., more particularly between 15° C. and 30° C., more particularly between 15° C. and 25° C., more particularly between 15° C. and 20° C. In particular, an upper limit temperature of the anodizing bath can be 15° C., 16° C., 17° C., 18° C., 19° C., 20° C., 21° C., 22° C., 23° C., 24° C., 25° C., 26° C., 27° C., 28° C., 29° C. or 30° C. A lower limit temperature of the anodizing bath can in particular be 5° C., 6° C., 7° C., 8° C., 9° C., 10° C., 11° C., 12° C., 13° C., 14° C., 15° C., 16° C., 17° C., 18° C., 19° C. or 20° C. If a plurality of anodizing baths is used, the above-mentioned temperatures or temperature ranges can relate to all the anodizing baths.
A second aspect of the invention relates to an anodized aluminum article produced according to the method according to the first aspect of the invention. All the statements in connection with the method according to the first aspect of the invention apply analogously for the anodized aluminum article according to the second aspect of the invention, and vice versa.
A third aspect of the invention relates to a facility for carrying out the method according to the method according to the first aspect of the invention. The facility comprises the devices described in connection with the method. The facility can further comprise a corresponding controller which is designed for generating control information for controlling the operation of respective devices, and which communicates with the respective devices, i.e. in particular the control devices associated with the respective devices. All the statements in connection with the method according to the first aspect of the invention apply analogously for the facility according to the third aspect of the invention, and vice versa.
The invention is explained again with reference to embodiments in the drawings, in which:
The method or the individual method steps serve for producing at least one anodized aluminum article 1, i.e. an aluminum article such as a technical component, the surface of which is formed at least in portions, optionally completely, by an aluminum oxide layer formed in the context of an electromechanical anodizing process, or comprises such a layer.
An anodized aluminum article 1 that can be or is produced according to the method may be a semifinished product or a finished product; as a semifinished product, the anodized aluminum article 1 can undergo one or more post-processing steps in order to convert the semifinished product into a finished product.
The essential steps of the method will be explained in detail in the following, with reference to an embodiment. It is significant in this case that the method comprises a particular succession or sequence of method or process steps, in particular having associated process parameters, which surprisingly makes it possible, in contrast to known anodizing processes, to produce anodized aluminum articles 1 having particular properties, i.e. having particularly matte or non-reflective surfaces, in an efficiently reproducible manner.
A first method step S1 provides a pickling step or pickling process of a provided aluminum substrate 1.1 in a pickling bath which contains a pickling solution, i.e. in particular an aqueous pickling solution. In the first method step S1, a continuously or discontinuously provided, e.g. strip-like or strip-shaped, aluminum substrate 1.1 undergoes a pickling step or pickling process in a pickling bath containing a pickling solution. The result of carrying out the first method step is a pickled aluminum substrate 1.1. The pickling serves to prepare the aluminum substrate 1.1 for the subsequent anodizing step or anodizing process. The first method step S1 can be carried out in a pickling device which comprises a pickling bath containing a corresponding pickling solution.
According to the method, a pickling bath which contains an alkali pickling solution can be used. The pH of the pickling solution is thus typically, optionally significantly, above 7. On the basis of tests, it has been possible to demonstrate that an alkali pickling bath is particularly expedient for the properties, sought according to the method, of the anodized aluminum article to be produced.
The pickling step can in generally be carried out as a matte pickling step. A pickling step in the variant E6 or E0 according to DIN 17611 is also conceivable, for example. In particular, a pickling step in the variant E6 according to DIN EN 17611 takes place, since, depending on the treatment time and surface structure of the aluminum substrate, a very uniformly matte to satin-gloss surface can furthermore be achieved by this variant.
According to the method, an alkali pickling solution can be used, which contains caustic soda in a concentration between 55 and 60 g/l; aluminum in a concentration between 50 and 55 g/l; and a pickling additive in a concentration between 10 and 15 g/l.
According to the method, a pickling additive can be used which reduces or prevents pickling process-related foaming; and/or a pickling additive is used which influences, i.e. in particular improves, the viscosity of the pickling solution; and/or a pickling additive is used which influences, i.e. in particular improves, the drag-out rate of the pickling solution. A corresponding pickling additive can for example be a pickling additive available under the trade name “Alfisatin”, which is available for example from the company Alufinish GmbH & Co. KG, 56626 Andernach (DE). In particular, pickling additives available under the trade names “Alfisatin 338”, “Alfisatin 339/4”, “Alfisatin 357” or “Alfisatin 358/1” are possible.
In all the embodiments the pickling step can be carried out for a time duration of between 1 and 60 min, in particular between 1 and 30 min.
Of course, a plurality of aluminum substrates 1.1 can be provided in the first method step S1 and can undergo a pickling step or pickling process in a corresponding manner. It is the case in general that, even if the method is described in the following in connection with an aluminum substrate 1.1, similar of course also applies for a plurality of aluminum substrates 1.1. Therefore, a plurality of aluminum substrates 1.1 can be treated or processed in each step of the method, in particular simultaneously.
A second method step S1 provides a first rinsing step of the pickled aluminum substrate in a first rinsing bath which contains a first rinsing solution, i.e. for example service water. In the second method step S2, typically immediately following the first method step S1, the pickled aluminum substrate accordingly undergoes a first rinsing step or rinsing process in a first rinsing bath containing a first rinsing solution. The result of carrying out the second method step S2 is a rinsed aluminum substrate; the aluminum substrate is largely freed of the pickling solution after the first rinsing step or rinsing process, which pickling solution would have a negative effect on the following method or process steps. The pickled aluminum substrate can be dipped into the first rinsing bath and rinsed in the first rinsing bath for a time duration of between 25 and 35 sec.
The second method step S2 can be carried out in a first rinsing device which comprises a first rinsing bath containing a corresponding first rinsing solution.
A third method step S3 provides a second rinsing step of the pickled aluminum substrate, rinsed in the first rinsing bath, in a second rinsing bath, which contains a second rinsing solution, i.e. for example service water. In the third method step S3, typically immediately following the second method step S2, the pickled aluminum substrate 1.1, rinsed in the first rinsing bath, accordingly undergoes a second rinsing step or rinsing process in a second rinsing bath containing a second rinsing solution. The result of carrying out the third method step S3 is a particularly thoroughly rinsed aluminum substrate 1.1; the aluminum substrate 1.1 is typically (virtually) completely freed of the pickling solution after the third rinsing step or rinsing process, which pickling solution would, as mentioned, have a negative effect on the following method or process steps. The pickled aluminum substrate 1.1 can be dipped into the second rinsing bath and rinsed in the second rinsing bath for a time duration of between 25 and 35 sec. The third method step S3 can be carried out in a second rinsing device which comprises a second rinsing bath containing a corresponding second rinsing solution.
A fourth method step S4 provides a descaling step of the aluminum substrate 1.1, rinsed in the second rinsing bath, in a descaling bath, which contains a descaling solution, i.e. in particular an aqueous descaling solution. In the fourth method step S4, typically immediately following the third method step S3, the pickled aluminum substrate 1.1, rinsed in the first and second rinsing bath, accordingly undergoes a descaling step or descaling process in a descaling bath containing a descaling solution. The result of carrying out the fourth method step S4 is a descaled aluminum substrate 1.1. The descaling serves to prepare the aluminum substrate 1.1 for the subsequent anodizing step or anodizing process. The fourth method step can be carried out in a descaling device which comprises a descaling bath containing a corresponding descaling solution.
According to the method, a descaling bath which contains an acidic descaling solution can be used. The pH of the descaling solution is thus typically, optionally significantly, below 7. On the basis of tests, it has been possible to demonstrate that an acidic descaling bath is particularly expedient for the properties, sought according to the method, of the anodized aluminum article 1 to be produced.
According to the method, for example an acidic descaling solution which contains nitric acid, hydrochloric acid, or sulfuric acid in a concentration between 200 and 250 g/l can be used.
According to the method, the descaling step can be carried out for a time duration of between 5 and 30 min.
A fifth method step S5 provides a third rinsing step of the descaled aluminum substrate in a third rinsing bath which contains a third rinsing solution, i.e. for example service water. In the fifth method step S5, typically immediately following the fourth method step S4, the descaled aluminum substrate 1.1 accordingly undergoes a third rinsing step or rinsing process in a third rinsing bath containing a third rinsing solution. The result of carrying out the fifth method step S5 is a rinsed descaled aluminum substrate 1.1; the aluminum substrate 1.1 is largely freed of the descaling solution after the third rinsing step or rinsing process, which descaling solution would have a negative effect on the following method or process steps. The descaled aluminum substrate 1.1 can be dipped into the third rinsing bath and rinsed in the third rinsing bath for a time duration of between 25 and 35 sec. The fifth method step S5 can be carried out in a third rinsing device which comprises a third rinsing bath containing a corresponding third rinsing solution.
A sixth method step S6 provides a fourth rinsing step of the descaled aluminum substrate 1.1, rinsed in the third rinsing bath, in a fourth rinsing bath which contains a fourth rinsing solution, i.e. for example service water. In the sixth method step S6, typically immediately following the fifth method step S5, the descaled aluminum substrate, rinsed in the third rinsing bath, accordingly undergoes a fourth rinsing step or rinsing process in a fourth rinsing bath containing a fourth rinsing solution. The result of carrying out the sixth method step is a particularly thoroughly rinsed aluminum substrate 1.1; the aluminum substrate 1.1 is typically (virtually) completely freed of the descaling solution after the fourth rinsing step or rinsing process, which descaling solution would, as mentioned, have a negative effect on the following method or process steps. The aluminum substrate 1.1 can be dipped into the fourth rinsing bath and rinsed in the fourth rinsing bath for a time duration of between 25 and 35 sec. The sixth method step S6 can be carried out in a fourth rinsing device which comprises a fourth rinsing bath containing a corresponding fourth rinsing solution.
A seventh method step S7 now provides at least one anodizing step in at least one anodizing bath which contains an anodizing solution, i.e. in particular an aqueous anodizing solution, as a result of which an anodized aluminum article 1 is formed from the aluminum substrate 1.1. In the seventh method step S7, typically immediately following the sixth method step S6, the descaled aluminum substrate 1.1, rinsed in the third and fourth rinsing bath, accordingly undergoes an anodizing step or anodizing process in an anodizing bath containing an anodizing solution. The result of carrying out the seventh method step S7 is an anodized aluminum article 1 having a particularly matte and non-reflective surface. The seventh method step S7 can be carried out in an anodizing device which comprises an anodizing bath containing a corresponding anodizing solution.
In the anodizing step or process, the aluminum substrate 1.1 is connected as the anode, and a, for example trough-like or trough-shaped, container receiving the anodizing solution, acting as the electrolyte, is connected as the cathode, as a result of which, when corresponding electrical voltages are applied to the aluminum substrate 1.1 forming the anode and the container forming the cathode, oxygen is produced at the surface of the aluminum substrate 1.1, which oxygen reacts, at the surface of the aluminum substrate 1.1, with aluminum ions, to form aluminum oxide, and thus forms an aluminum oxide layer 1.2 (cf.
According to the method, at least one anodizing bath which contains an acidic anodizing solution can be used. The pH of the anodizing solution is thus typically, optionally significantly, below 7. On the basis of tests, it has been possible to demonstrate that an acidic anodizing bath is particularly expedient for the properties, sought according to the method, of the anodized aluminum article to be produced.
According to the method, for example an acidic anodizing solution which contains aluminum, e.g. in the form of one or more aluminum salts, such as aluminum sulphate (Al2(SO4)3 or Al2(SO4)2), and sulfuric acid, can be used. The sulfuric acid can be present in a concentration between 100 and 350 g/l, in particular the concentration of the sulfuric acid can be between 140 and 200 g/l, more particularly between 150 and 190 g/l. The aluminum or the aluminum salt can be present in a concentration between 10 and 80 g/l, in particular between 10 and 50 g/l, more particularly between 10 and 45 g/l, more particularly between 10 and 40 g/l, more particularly between 10 and 35 g/l, more particularly between 10 and 30 g/l.
According to the method, the anodizing step can be carried out for a time duration of between 5 and 30 min.
The seventh method step S7 can comprise a plurality of, i.e. in particular three, anodizing processes (anodizing sub steps) carried out in succession in a plurality of anodizing baths, which baths each contain a corresponding anodizing solution. The respective anodizing processes can each be carried out for a time duration of between 5 and 30 min.
An eighth method step S8 provides at least one further rinsing step in at least one further rinsing bath which contains a further rinsing solution, i.e. in particular a further aqueous rinsing solution. In the eighth method step S8, typically immediately following the seventh method step S7, the anodized aluminum article 1 accordingly undergoes at least one further rinsing step or rinsing process in at least one further rinsing bath containing a further rinsing solution. The result of carrying out the eighth method step S8 is a rinsed anodized aluminum article 1; the anodized aluminum article 1 is typically (largely) completely freed of the anodizing solution after the at least one further rinsing step or rinsing process. The aluminum article 1 can be dipped into the at least one further rinsing bath and rinsed in the at least one further rinsing bath for a time duration of between 25 and 35 sec. The eighth method step S8 can be carried out in at least one further rinsing device which comprises a further rinsing bath containing a corresponding further rinsing solution.
In the context of the eighth method step S8, a plurality of rinsing steps (rinsing sub steps) can be carried out in a plurality of, i.e. in particular in three, separate rinsing baths, which each contain a rinsing solution. In this case, a first rinsing bath can e.g. contain service water as the rinsing solution. A second rinsing bath can e.g. contain fresh water as the rinsing solution. A third rinsing bath can contain circulation water, in particular circulation water having a conductivity of less than 50 μS/cm, in particular less than 30 μS/cm, as the rinsing solution.
It is thus notable that the aluminum substrate was rinsed, prior to the actual anodizing step or process, in a plurality of separate rinsing baths or rinsing solutions, such that substances possibly harmful for the anodizing step or process and the associated anodizing result were removed from the aluminum substrate 1.1. Furthermore, it is notable that the aluminum substrate 1.1 was anodized in a plurality of anodizing baths, which results in specific surface properties of the aluminum article 2 that is to be produced or is produced.
The described succession or sequence of the method steps enables an efficient, reproducible production of anodized aluminum articles having specific properties, i.e. in particular having particularly matte and non-reflective surfaces. The anodized aluminum article produced according to the method thus comprises a matt, non-reflective surface.
All the method steps can be carried out in an at least partially, optionally completely, automatable or automatic manner. A facility designed for carrying out the method can comprise devices for this purpose, i.e. in particular pickling devices, rinsing devices, descaling devices, and anodizing devices, which enable the method step to be carried out in an at least partially, optionally completely, automatable or automatic manner. The operation of respective devices can be controlled via a controller implemented in a hardware-based and/or software-based manner, which controller is designed for generating control information for controlling the operation of respective devices, and which communicates with the respective devices, i.e. in particular the control devices associated with the respective devices.
Depending on the specific process control, the anodized aluminum article 1 can have an aluminum oxide or anodized layer 1.2 having a layer thickness in a range between 5 and 50 μm, in particular between 10 and 30 μm. Typically, the layer thickness of the aluminum oxide or anodized layer is at least 15 μm. For this purpose, it may be necessary to carry out the anodizing step over a time duration of at least 15 min, in particular at least 20 min, more particularly at least 25 min.
As mentioned, the anodized aluminum article 1, should this be a semi-finished product, can undergo at least one post-treatment step, in order to produce a finished product from the semi-finished product.
After the last rinsing step, optionally before or after a drying step following the last rinsing step, in which drying step the anodized aluminum article 1 is age-hardened at an increased temperature, in particular a temperature in a range between 50 and 150° C., at least one compression step can be carried out, in which the anodized aluminum article 1, i.e. in particular the aluminum oxide layer 1.2 formed by the anodizing step, is compressed in order to reduce any porosity of the aluminum oxide layer 1.2 that is possibly present.
Alternatively or in addition, after the last rinsing step, optionally after a drying step following the last rinsing step, in which drying step the anodized aluminum article 1 is age-hardened at an increased temperature, in particular a temperature in a range between 50 and 150° C., and/or after a corresponding compression step, at least one post-processing step is carried out, in which the anodized aluminum article 1 is printed for example with alphanumeric symbols, coded or non-coded information, e.g. in the form of barcodes, QR codes, etc., and/or at least one post-processing step takes place, in which anodized aluminum bodies of a defined shaping are separated out of the anodized aluminum article 1, e.g. by punching or cutting.
The method can be carried out using aluminum substrates 1.1 made of pure aluminum or an aluminum alloy. If an aluminum substrate 1.1 made of an aluminum ally is used, in particular an aluminum alloy is possible which, in addition to aluminum, contains at least one alloying element from the group: iron, silicon, copper, manganese, magnesium, chromium, tin or titanium. In particular, an aluminum alloy can be used which has the following chemical composition, in mass percent: 0.70-1.0 wt. % iron, 0.30-0.50 wt. % silicon, 0.20-0.50 wt. % copper, 0.20-0.50 wt. % manganese, 0.50-1.10 wt. % magnesium, 0.10-0.50 wt. % chromium, 0.25-0.60 wt. % tin and 0-0.30 wt. % titanium. The remainder is made up in each case by aluminum and possible impurities; of course, the mass percentages add up to 100 wt. %.
Before the pickling step in the pickling bath, a degreasing step of the provided aluminum substrate 1.1 can be carried out for degreasing the aluminum substrate 1.1. The degreasing of the aluminum substrate 1.1 typically leads to a better pickling result, since organic substances can be removed from the aluminum substrate 1.1 at least in part, optionally completely.
The degreasing step can be carried out by means of dipping the aluminum substrate 1.1 one or more times, at least in portions, in particular completely, into a degreasing bath which contains a degreasing solution.
A degreasing bath which contains an alkali degreasing solution can be used. On the basis of tests, it has been possible to demonstrate that an alkali degreasing solution is particularly expedient for the properties, sought according to the method, of the anodized aluminum article 1 to be produced. An alkali degreasing solution can for example be a degreasing solution available under the trade name “Alficlean”, which is available for example from the company Alufinish GmbH & Co. KG, 56626 Andernach (DE). In particular, the degreasing solutions available under the trade names “Alficlean 150”, “Alficlean 154/4” or “Alficlean 155” are possible.
The degreasing step can be carried out for a time duration of between 1 and 60 min, in particular between 5 and 30 min. The specific selection of the time duration of the degreasing step (similar applies for every step of the method) results in particular from the chemical composition of the aluminum substrate provided, and its surface condition prior to the degreasing step. The term “surface condition” is to mean understood in particular to mean the presence of e.g. organic foreign substances of impurities on the surface of the aluminum substrate 1.1.
Alternatively or in addition to the chemical degreasing described above, in principle mechanical degreasing steps are also conceivable.
After the degreasing step, but before the pickling step, a pre-rinsing step of the degreased aluminum substrate 1.1 can be carried out in the first rinsing bath which contains the first rinsing solution. The pre-rinsing step can be carried out by means of dipping the degreased aluminum substrate 1.1 one or more times, at least in portions, in particular completely, into the first rinsing bath. The pre-rinsing step can thus be kept comparatively short, which is beneficial for the efficiency of the method.
The degreasing step can be carried out at a temperature in a range between 20 and 80° C., in particular in a range between 25 and 75° C., more particularly in a range between 30 and 70° C., more particularly in a range between 35° C. and 65° C., more particularly between 40° C. and 60° C., more particularly in a range between 45° C. and 55° C. Therefore, the temperature of the degreasing bath can be in a range between 20 and 80° C., in particular between 25 and 75° C., more particularly between 30 and 70° C., more particularly between 35° C. and 65° C., more particularly between 40° C. and 60° C., more particularly between 45° C. and 55° C.
The pickling step can be carried out at a temperature in a range between 30 and 90° C., in particular in a range between 35 and 85° C., more particularly in a range between 40 and 80° C., more particularly in a range between 45° C. and 75° C., more particularly between 50° C. and 70° C., more particularly in a range between 55° C. and 65° C. Therefore, the temperature of the pickling bath can be in a range between 30 and 90° C., in particular in a range between 35 and 85° C., more particularly in a range between 40 and 80° C., more particularly in a range between 45° C. and 75° C., more particularly between 50° C. and 70° C., more particularly in a range between 55° C. and 65° C.
The descaling step can be carried out at a temperature in a range between 0 and 50° C., in particular in a range between 5 and 45° C., more particularly in a range between 10 and 40° C., more particularly in a range between 15° C. and 35° C., more particularly between 15° C. and 30° C., more particularly between 15° C. and 25° C., more particularly between 15° C. and 20° C. Therefore, the temperature of the descaling bath can be in a range between 0 and 50° C., in particular in a range between 5 and 45° C., more particularly in a range between 10 and 40° C., more particularly in a range between 15° C. and 35° C., more particularly between 15° C. and 30° C., more particularly between 15° C. and 25° C., more particularly between 15° C. and 20° C.
The anodizing step can be carried out at a temperature in a range between 0 and 50° C., in particular in a range between 5 and 45° C., more particularly in a range between 10 and 40° C., more particularly in a range between 15° C. and 35° C., more particularly between 15° C. and 30° C., more particularly between 15° C. and 25° C., more particularly between 15° C. and 20° C. Therefore, the temperature of the anodizing bath can be in a range between 0 and 50° C., in particular in a range between 5 and 45° C., more particularly in a range between 10 and 40° C., more particularly in a range between 15° C. and 35° C., more particularly between 15° C. and 30° C., more particularly between 15° C. and 25° C., more particularly between 15° C. and 20° C. In particular, an upper limit temperature of the anodizing bath can be 15° C., 16° C., 17° C., 18° C., 19° C., 20° C., 21° C., 22° C., 23° C., 24° C., 25° C., 26° C., 27° C., 28° C., 29° C. or 30° C. A lower limit temperature of the anodizing bath can in particular be 5° C., 6° C., 7° C., 8° C., 9° C., 10° C., 11° C., 12° C., 13° C., 14° C., 15° C., 16° C., 17° C., 18° C., 19° C. or 20° C. If a plurality of anodizing baths is used, the above-mentioned temperatures or temperature ranges can relate to all the anodizing baths.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102021119472.5 | Jul 2021 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/068519 | 7/5/2022 | WO |
