Component for a porous structure, and method for producing a component for a porous structure

Abstract

The invention relates to a component (26) for a porous structure, in particular for use in a plant for an electrochemical process, which component is produced from a planar workpiece (22) made in particular from a metallic material, in particular from a metal sheet or a foil, the component having surface structures (24) on at least one surface (20) of the component (26), which surface structures have been formed in the surface (20) by material removal by means of a laser beam (12), wherein a through-opening (32) of the component (26) is formed at at least one intersection point (30) of the surface structures (24).

Description

[0001] COMPONENT FOR A POROUS STRUCTURE AND METHOD FOR PRODUCING A COMPONENT FOR A POROUS STRUCTURE

[0002] The invention relates to a component for a porous structure, in particular for use in a plant for an electrochemical process, and to a method for producing a component for a porous structure, in particular for use in a plant for an electrochemical process.

[0003] From EP 4265 358 A1 a method for producing a porous structure for transporting a fluid is known, which is in particular intended to form a heat exchanger and / or in contact with which a chemical reaction of the transported fluid can take place.

[0004] DE 44 26 347 A1 discloses a flat component with a grid of through holes. A V-shaped surface structure is first created on the component. However, due to this V-shaped surface structure, only a small contact area with the catalyst layer is formed, resulting in poor electrochemical performance.

[0005] The object of the present invention is to provide a solution by means of which a porous structure can be created whose porosity is adjusted with particular precision.

[0006] This problem is solved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are specified in the dependent claims, the description, and the drawings. Features, advantages, and possible embodiments set forth in the description for one of the subject matter of the independent claims are to be regarded, at least analogously, as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as of any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the dependent claims.

[0007] The invention relates to a component for a porous structure, particularly for use in an electrochemical process system. Alternatively, the component can be configured for use in a catalytic device or an osmosis device. Generally, the component is designed for use in a system that utilizes the transport of gaseous and / or liquid media through the porous structure, particularly for electrochemical processes. The component is thus intended to be used as part of the porous structure in the electrochemical system. The system is configured to carry out an electrochemical process. In an electrochemical process, a chemical reaction is linked to an electric current.In this process, either a redox reaction can be forced by an externally applied electrical voltage, or a measurable voltage can be generated by a chemical reaction of suitable substances.

[0008] The component is manufactured from a planar workpiece, in particular a sheet or foil, made of a metallic material. In other words, the workpiece is made of a metallic material comprising at least one metal. Specifically, the workpiece is designed to be plate-shaped, for example, in the form of a sheet or foil, depending on the workpiece's thickness. The component has surface structures on at least one surface, which were created by material removal using a laser beam. In other words, the surface structures are created by removing material from the workpiece. This can be achieved by vaporizing and / or melting the material.It is intended that the surface structures intersect at least once, and in particular several times, with a through-opening in the component being formed at at least one intersection point. Specifically, the at least one through-opening results from the intersecting surface structures. The material removal at the intersection point of the surface structures removes sufficient material from the component to create the at least one through-opening. By incorporating the respective surface structures, through-holes can be precisely, reproducibly, and uniformly introduced into the component and aligned with one another. The through-openings can thus be introduced into the component with exceptional precision.Furthermore, the surface structures enable the targeted and precise guidance of a fluid to the respective through-holes when the component is used as intended within the porous structure. The surface structures can be selectively applied to specific areas of the workpiece surface. In other words, the workpiece surface is only partially covered with the surface structures to manufacture the component. This allows the through-holes to be created precisely in these areas. The component is manufactured by applying the intersecting surface structures to the workpiece. It is possible to combine the component with several other components, each with its own through-hole, to form the porous structure.For example, several components, each with through-holes, can be stacked on top of each other in a stacking direction and bonded together, thus creating the porous structure. In particular, it is intended that at least one surface of each component remains at least partially free of surface structures. Thus, after stacking the multiple components, unprocessed surface areas, which can be described as "webs" and / or "columns," can remain between the introduced surface structures, especially without material removal and with a largely unchanged surface quality in the unprocessed surface area. In these unprocessed surface areas, the component largely retains the original material thickness of the workpiece. This promotes a bonded connection between the stacked components.

[0009] In a possible further development of the invention, the component is configured to be used as part of a porous transport layer and / or to be employed in a hydrogen electrolyzer, an electrodialyzer, a capacitive deionizer, an electroosmosis system, or a redox flow battery as the system for the electrochemical process. The porous transport layer is designed to transport a substance or a mixture of substances, particularly in gaseous or liquid form, especially towards an interface of the electrochemical system. For example, the porous transport layer can serve to distribute reaction gases uniformly across the interface. Alternatively or additionally, the porous transport layer can facilitate the removal of a reactant from the interface.An electrolyzer is a device that uses electric current to induce a chemical reaction, i.e., a chemical transformation. The electrolyzer is designed to carry out electrolysis. A hydrogen electrolyzer is designed to split water into hydrogen and oxygen. For example, a hydrogen electrolyzer might use a proton exchange membrane. An electrodialyzer is designed to implement an electrochemically driven membrane process by using ion exchange membranes in combination with an electrical potential difference to separate ionic species from uncharged solvents or impurities. A capacitive deionizer is designed to remove ions from an aqueous solution. Similarly, an electrodialyzer is designed to remove ions from an aqueous solution.The electroosmosis system is designed to perform electroosmosis. In electroosmosis, an electric field parallel to a surface is applied, causing an interfacial phenomenon between the capillary wall and an electrolyte solution. Thus, electroosmosis results in the movement of a liquid parallel to a surface by applying an electric field. The electroosmosis system can be used, for example, for electrophoresis. The redox flow battery—more commonly called a liquid battery or wet cell—is a type of accumulator. It stores electrical energy in chemical compounds, with the reactants being dissolved in a solvent. Two energy-storing electrolytes circulate in two separate circuits, between which ion exchange takes place in a galvanic cell via a membrane.In the galvanic cell, the dissolved substances are chemically reduced or oxidized, releasing electrical energy. The integration of the component into a porous transport layer in the hydrogen electrolyzer, electrodialyzer, capacitive deionizer, electroosmosis system, or redox flow battery enables a particularly uniform distribution of the reactant or a highly efficient removal of the reactant, allowing the respective electrochemical process to be carried out with exceptional effectiveness and reproducibility.

[0010] In a further possible embodiment of the invention, the metallic material comprises titanium and / or stainless steel and / or nickel. The metallic foil can thus be made of a titanium material, in particular a titanium alloy. Alternatively or additionally, the metallic foil can be made of stainless steel or a nickel-based material, in particular a nickel-iron alloy or a nickel-cobalt alloy. Manufacturing the foil from the metallic material, in particular titanium and / or stainless steel and / or nickel, enables particularly high foil stability and, furthermore, particularly high electrical conductivity.

[0011] In a further possible embodiment of the invention, the surface structures each comprise a regular pattern. It is possible that the respective surface structures exhibit regularity in their structure only in a partial area. Alternatively, it can be provided that the respective surface structures exhibit a regular pattern across their entire extent. A pattern is regular if it repeats at regular intervals. The regular pattern thus comprises structural elements of the respective surface structure that are repeated multiple times. This makes it possible to easily create a particularly large number of through-holes in the workpiece through the intersecting surface structures, with the through-holes having regular, and in particular uniform, spacing from one another.

[0012] In a further possible embodiment of the invention, at least one of the surface structures comprises a plurality of parallel lines. These lines are created in the surface of the workpiece, in particular by material removal. The surface structure thus comprises a plurality of linear depressions in the surface of the workpiece. These lines can be created in the surface of the workpiece particularly easily and with exceptionally high precision. A through-opening can then be formed in the area of ​​two intersecting lines.

[0013] In a further possible embodiment of the invention, the surface structures introduced into the workpiece (in particular the contact surface) are provided to occupy 30% to 100%, in particular 50% to 85%, of the at least one surface of the workpiece having the surface structures, and / or a sum of the narrowest cross-sections of all through-openings of 10% to 80%, in particular 15% to 50%, of the area spanned by the width and length of the workpiece. The surface structure can thus occupy either only a portion of the surface into which the surface structure is introduced, or the entire surface into which the surface structure is introduced.The statement that the narrowest cross-section of all through-openings occupies a total of 15% to 50% of the area defined by the width and length of the workpiece means that the flow cross-section of the component formed by the sum of the through-openings occupies 15% to 50% of the area defined by the component's width and length. The width and length are perpendicular to each other and also perpendicular to the thickness of the workpiece. Because the workpiece only has surface structures in a portion of its surface, the through-openings can only be incorporated into a portion of the workpiece, while another portion can remain free of through-openings.By ensuring that the narrowest cross-section of each through-hole occupies a maximum of 50% of the area defined by the width and length of the workpiece, it is possible to achieve particularly high stability of the workpiece and, at the same time, to guide a fluid with particular precision through the through-holes when used as intended.

[0014] In a further possible embodiment of the invention, the surface of the component, which has at least one surface structure, includes at least one sub-area that is free of the surface structure. This at least one sub-area preferably extends in a frame-like shape along the edge of the surface. Thus, only an inner area of ​​the surface enclosed by this sub-area can have the surface structuring.This ensures that, particularly when stacking multiple components in the stacking direction, the fluid can only flow through the porous structure in the stacking direction. Lateral outflow of the fluid from the porous structure in a direction oblique or perpendicular to the stacking direction is reliably prevented, as the section free of the surface structure allows the component to be positioned very close to another component. This results in the central area of ​​the surface being particularly tightly enclosed by the frame-shaped section free of the surface structure towards the sides of the porous structure. Furthermore, the section free of the surface structure enables edge reinforcement of the component.The surface structure is therefore only applied to the inner area of ​​the surface enclosed by the edge zone, thus achieving edge reinforcement for mechanical purposes, which also has a sealing function. The edge zone of the component's surface is left untreated. This allows for a particularly large-area, material-bonded connection between several components stacked on top of each other in the stacking direction.

[0015] In a further possible embodiment of the invention, a plurality of through-holes are provided in the workpiece, wherein all through-holes have a tolerance of less than 20% with respect to the cross-sectional area of ​​their narrowest cross-section and / or with respect to the distance of the narrowest cross-section to the at least one surface of the workpiece into which at least one surface structure is introduced. This refers in particular to the shortest distance of the respective narrowest cross-section of each of the through-holes to the original, unmachined surface of the workpiece. In other words, the respective cross-sectional areas of the narrowest cross-sections of the through-holes and / or the positions of the respective narrowest cross-sections of the through-holes with respect to the thickness direction of the workpiece are arranged within a tolerance band of 20%.The greatest distance in the thickness direction between any two narrowest cross-sections of two through-holes is therefore at most 20% of the workpiece thickness. The greatest difference between the cross-sectional areas of any two narrowest cross-sections of two through-holes in the workpiece is at most 20% of the larger of the two cross-sectional areas. Thus, within the specified tolerance range, the through-holes have a similar or identical cross-sectional area of ​​their narrowest cross-section, or an identical or similar arrangement with respect to their position in the thickness direction within the workpiece.This allows for a particularly uniform flow of the fluid, comprising gaseous and / or liquid components, through the respective openings within the component; in particular, it allows for at least a substantially uniform flow velocity of the fluid as it passes through the respective openings. Thus, the component enables a particularly uniform distribution of the fluid.

[0016] In a further possible embodiment of the invention, the ratio of the square of the workpiece thickness to the cross-sectional area of ​​the narrowest cross-section of at least one of the through-openings is less than or equal to 100 and greater than 1, in particular greater than 3. Thus, a minimal workpiece thickness can be achieved with respect to the cross-sectional area of ​​the respective narrowest cross-sections of the through-openings, thereby enabling a particularly small aspect ratio. An aspect ratio is understood as the height-to-width ratio of microstructures. In process engineering, the aspect ratio is understood as the ratio of the depth or height of a structure to its lateral extent. The larger the aspect ratio and the smaller the absolute size of the structure, the more difficult the manufacturing process.Such a design, in which the ratio of the square of the workpiece thickness to the cross-sectional area of ​​the narrowest cross-section of the respective through-opening is less than or equal to 100 and greater than 1, in particular greater than 3, makes it possible to achieve the particularly small aspect ratio and, consequently, to integrate the surface structure or the respective through-opening into the workpiece particularly easily. In this context, it can be provided, in particular, that the at least one surface structure is integrated into only one surface of the workpiece and all other surfaces of the component are free of surface structures.

[0017] In a further possible embodiment of the invention, the workpiece has a thickness of 20 to 200 micrometers and / or at least one of the through-holes has a cross-sectional area of ​​less than 2000 square micrometers, in particular less than 500 square micrometers, at its narrowest cross-section. The unmachined workpiece thus has a particularly small thickness of 20 to 200 micrometers. Consequently, the workpiece is exceptionally thin. As a result, only a very small amount of material is required to manufacture the component. Furthermore, due to the particularly small thickness of the workpiece, especially fine surface structures can be incorporated into at least one surface of the workpiece, with through-holes resulting at the intersections of these fine surface structures.The thinner the workpiece, the shallower the depth required for individual lines of the respective surface structures to create openings at their intersections. The shallower the lines, the narrower they can be in both the width and length directions of the workpiece. This means that very little material needs to be removed from the workpiece surface to create these openings. Furthermore, the exceptionally fine lines can be applied with very small spacing in both the width and length directions, resulting in openings with extremely close distances between them.This allows for a particularly fine perforation of the component. Because at least one of the through-holes, and in particular all of the through-holes, has a cross-sectional area of ​​less than 2000 square micrometers, and especially less than 500 square micrometers, at its narrowest point, the respective through-holes are exceptionally small. Therefore, when used as intended, the component allows for a particularly fine distribution of the fluid through the flow of fluid through these through-holes.

[0018] In a further possible embodiment of the invention, the at least two intersecting surface structures have different preferred directions and are incorporated into the surface on the same side of the workpiece. The preferred direction describes the principal direction of extension of the respective structures. For example, the preferred direction can run parallel to the longitudinal direction of extension of the respective lines of the surface structure. By having different preferred directions for the surface structures, it can be ensured that the surface structures intersect at least at one point where the through-opening is formed.If the preferred directions of the respective surface structures were parallel to each other and each surface structure comprised only parallel lines, then it could not be guaranteed that at least one intersection would result. If the surface structures are intended to be applied to the workpiece surface only on one side, then these surface structures can be produced particularly easily using a laser processing device that directs at least one laser beam onto the surface into which the surface structures are to be applied. Reorienting the workpiece relative to the laser processing device is unnecessary because the surface structures are applied only to one side of the workpiece. This allows the component to be manufactured particularly easily and quickly.

[0019] In a further possible embodiment of the invention, the surface structures are incorporated into the respective surfaces of the workpiece on opposite sides. The respective surface structures can intersect at their respective points of intersection in a projection extending in the thickness direction. Thus, material is removed from the opposite sides of the workpiece by means of at least one laser beam in order to inscribe the respective surface structures into the respective surfaces of the workpiece on those opposite sides.In areas where surface structures, particularly individual lines of surface structures, overlap in the thickness direction, material removal on opposite sides of the workpiece results in a total amount of material being removed at the intersection point to create a through-hole. Because the surface structures are incorporated into the respective surfaces of the workpiece on opposite sides, it may be sufficient for each surface structure to extend over only half the thickness of the workpiece in the thickness direction to reliably form through-holes at the respective intersection points.Furthermore, the elongated surface structures – particularly their lines – ensure intersection points and thus through-holes without requiring precise positioning of the surface structures relative to each other from both sides. The spacing between multiple through-holes, especially their period, can be adjusted solely by the spacing, and particularly the period, of the lines within the respective surface structures. The surface structures can therefore be applied to the workpiece particularly easily and with very low laser power, reliably creating at least one through-hole.

[0020] In a further possible embodiment of the invention, a cross-section of at least one surface structure is U-shaped. It is conceivable that a cross-section of each of the surface structures is also U-shaped. In particular, the surface structures (each) do not have a V-shaped cross-section. The contact area formed by the surface structures can be larger than the area of ​​the component for the porous structure outside the contact area, and in particular larger than the area formed by the through-holes. The ratio of the contact area to the area of ​​the component for the porous structure outside the contact area, and in particular to the area formed by the through-holes, can be equal to 1 or greater. This allows for the provision of the largest possible contact area with narrow through-holes.

[0021] The invention further relates to a method for producing a component for a porous structure, particularly for use in an electrochemical process. Specifically, the method produces a component as already described in connection with the component according to the invention. The method involves processing a planar workpiece, particularly a sheet or foil made of a metallic material, using a laser beam. This process involves creating surface structures in at least one surface of the workpiece by ablating material with the laser beam. This results in a through-opening for the component at at least one intersection of the surface structures.The surface structures can be formed, in particular, by a multitude of lines, especially a multitude of parallel lines, into which at least one surface of the workpiece is introduced. The individual lines of the respective surface structure can be straight or odd, and in particular, can have at least one curvature. The process can be carried out, in particular, using a flatbed laser machine as the laser processing device. Within the scope of the process, the component with at least one through-hole can be manufactured particularly easily.

[0022] In a possible further development of the invention, it is provided that for the introduction of each of the surface structures, a maximum of 80% of the workpiece thickness is removed. At at least one intersection of the surface structures, the sum of the material removed exceeds the thickness of the workpiece, thereby forming the through-opening at this intersection. Thus, in this method, it is not provided that one of the surface structures extends over 100% of the workpiece thickness and thereby creates the through-opening in a single step.Instead, the design allows each surface structure to extend only over a portion of the workpiece's thickness. At each intersection, enough material is removed to create a through-hole. This sum of material removal for the intersecting surface structures results in the through-hole at that intersection. Therefore, at least one through-hole can be reliably and precisely created with very little energy input into the workpiece, for example, using very low laser power.

[0023] In a further possible embodiment of the invention, the relative positions of the surface structures are selected such that the intersections of the surface structures result at predetermined points for the through-openings. Thus, depending on a predetermined porosity of the porous structure to be produced from the component, specific points on the workpiece are selected at which the respective through-openings are to be created. Depending on these predetermined points, the respective surface structures are selected in their design and position on the respective surface into which they are to be incorporated. This allows the respective through-openings to be introduced into the workpiece with particular precision at the predetermined positions in order to produce the component.

[0024] The surface structures, which are introduced into at least one surface of the workpiece by material removal, are designed to guide a fluid. The surface structures, and in particular the openings resulting from the intersection of these structures, enable precise mass transport or fluid guidance of a fluid comprising gaseous and / or liquid components within the porous structure.

[0025] In a further possible embodiment of the invention, the laser beam is pulsed in a range of 100 fs to 20 ps. Alternatively or additionally, the laser beam can have a diffraction coefficient in a range of 1 to 10, particularly in a range of 1 to 5, and especially in a range of 1 to 1.5.

[0026] Further features of the invention may become apparent from the following description of the figures and from the drawing. The features and combinations of features mentioned above in the description, as well as those shown below in the description of the figures and / or in the figures themselves, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention. The drawing shows:

[0027] Fig. 1 shows a schematic perspective view of a laser processing device by means of which a surface structure is introduced into the surface of a workpiece;

[0028] Fig. 2 shows a schematic top view of a component which has been manufactured by introducing intersecting surface structures into a surface of the workpiece, wherein the intersecting surface structures have been introduced into the same surface of the workpiece;

[0029] Fig. 3a, 3b the component with intersecting surface structures, wherein the surface structures have been introduced into opposite surfaces of the workpiece;

[0030] Figs. 4a, 4b show respective normal projections of the component in different configurations, for the production of which several intersecting surface structures have been introduced into the same surface of the workpiece, wherein the surface structures introduced into the surface differ in their geometry in the configurations shown in Figs. 4a and 4b;

[0031] Fig. 5a shows a normal projection of the component, wherein the component has been created by introducing surface structures into opposing surfaces of the workpiece;

[0032] Fig. 6 shows a normal projection of two components stacked on top of each other in one stacking direction, which have different surface structures; and

[0033] Fig. 7 schematically shows a cross-section of the surface structures according to a further embodiment. Identical or functionally equivalent elements are designated with the same reference numerals in the figures.

[0034] Figure 1 shows a laser processing device 10, by means of which at least one laser beam 12 is provided. The laser processing device 10 comprises a scanner optic 14 for deflecting an input laser beam 16 and a focusing device, in particular an anamorphic focusing device 18, by means of which the deflected input laser beam 16 can be focused to form the laser beam 12. The laser processing device 10 directs the laser beam 12 onto a surface 20 of a workpiece 22. The workpiece 22 is, in this case, a thin sheet or foil made of a metallic material. The metallic material can, in particular, comprise titanium and / or stainless steel and / or nickel. By directing the laser beam 12 onto the surface 20 of the workpiece 22, a surface structure 24 is introduced into the surface 20, thereby producing a component 26 from the workpiece 22.

[0035] The laser processing device 10 can be configured, as shown in Fig. 1, to introduce the surface structure 24 into the surface 20 of the workpiece 22 within a linear processing zone 28. During the introduction of the surface structure 24 into the surface 20, the workpiece 22 and the laser processing device 10 can be moved relative to each other. Material is removed from the surface 20 of the workpiece 22 by means of the laser beam 12. The surface structure 24 is thus introduced into the workpiece 22 by material removal. In this process, the material can be melted and / or vaporized.

[0036] In this case, a thin titanium foil is laser-processed to produce component 26. To produce component 26, intersecting surface structures 24 are introduced into at least one surface 20 of the workpiece 22, with through-openings 32 forming at each intersection point 30. For clarity, only some of the intersection points 30 and some of the through-openings 32 are labeled with their corresponding reference numerals. Each surface structure 24 comprises a plurality of lines 34. All lines 34 of a surface structure 24 are parallel to each other. Again, for clarity, only some of the lines 34 are labeled with their corresponding reference numerals.Component 26 is designed for use in a porous structure, particularly in an electrochemical process system. Alternatively, component 26 can be configured for use in a catalytic or osmotic system. For this purpose, several components 26 can be stacked on top of each other in a stacking direction and used as a porous transport layer in a hydrogen electrolyzer, an electrodialyzer, a capacitive deionizer, an electroosmosis system, or a redox flow battery as part of the electrochemical process system.

[0037] Figures 2 to 6 show individual components 26, each with a different surface structure 24. In each of the depicted embodiments, the respective surface structure 24 comprises a plurality of parallel straight lines 34. Each surface structure 24 exhibits a regular pattern. It is possible that the respective surface structure 24 incorporated into the workpiece 22 covers 30% to 100% of the area of ​​at least one surface 20 of the workpiece 22 that has the surface structure 24. This means that the surface structure 24 extends either over a portion of the surface 20 of the workpiece 22 or over the entire surface 20 of the workpiece 22 that has the surface structure 24.In this case, surface 20 refers only to that area of ​​the entire outer surface of the workpiece 22 which is assigned to one side of the workpiece 22. This means that each of the surfaces 20 of the workpiece 22 bounds the workpiece 22 on one side.

[0038] If the respective surface structure 24 extends only over a partial area of ​​the respective surface 20 of the workpiece 22, then this surface 20 additionally has a further partial area which is free of the surface structure 24. This further partial area can surround the partial area of ​​the surface 20 in which the surface 20 has the surface structure 24 in a frame-like manner.

[0039] It is provided that the narrowest cross-section of all through-openings 32 together occupy 15% to 50% of the area defined by the width (lateral direction B) and length (longitudinal direction L) of the workpiece 22. It is further provided that the workpiece 22 has a thickness (thickness direction D) of 20 to 200 micrometers. It is further provided that at least one of the through-openings 32 has a cross-sectional area of ​​less than 2000 square micrometers, in particular less than 500 square micrometers, at its narrowest cross-section. It is further provided that the ratio of the square of the thickness of the workpiece 22 to the cross-sectional area of ​​the narrowest cross-section of at least one of the through-openings 32 is less than or equal to 100 and greater than 1, in particular greater than 3.

[0040] Furthermore, it is provided that a plurality of through-openings 32 are provided in the workpiece 22, wherein all through-openings 32 have a tolerance of less than 20% with respect to the cross-sectional area of ​​their narrowest cross-section and with respect to the distance of the narrowest cross-section to the at least one surface 20 of the workpiece 22 into which the at least one surface structure 24 is provided. This ensures a uniform performance of the component 26 with respect to guiding a fluid during intended use.

[0041] Figure 2 shows a component 26 in which two surface structures 24 are incorporated into the same surface 20 of the workpiece 22, wherein the first lines 34 of a first surface structure 24 extend with their longitudinal direction perpendicular to the longitudinal direction of the second lines 34 of the second surface structure 24. In this context, this means that the first lines 34 extend with their longitudinal direction in the width direction and the second lines 34 extend with their longitudinal direction in the length direction. In the component 26 shown in Figures 3a and 3b, the component 26 was produced by incorporating a first surface structure 24 into a first surface 20 of the workpiece 22 and a second surface structure 24 into a second surface 20 of the workpiece 22 opposite the first surface 20.Figure 3a shows component 26 with a view to the first surface 20, and Figure 3b shows component 26 with a view to the second surface 20. It can be seen that the first lines 34 of the first surface structure 24 run in the longitudinal direction L, and the second lines 34 of the second surface structure 24 run in the transverse direction B. The surface structures 24 are thus incorporated into the respective surfaces 20 of the workpiece 22 on opposite sides for the production of component 26. At the respective intersection points 30, where the first surface structure 24 overlaps the second surface structure 24 in the thickness direction D, the respective through-openings 32 are formed.In the embodiments shown in Figures 2 to 3b, the respective lines 34 of the first surface structure 24 and the second surface structure 24 have the same cross-section perpendicular to the longitudinal direction. The lines 34 of the different surface structures 24 thus differ only in their position and in the orientation of their longitudinal direction. This results in through-openings 32 with a narrowest cross-section that is at least substantially circular.

[0042] In principle, non-perpendicular orientations of the lines 34 of the different surface structures 24 are conceivable - also for tolerance reasons, since the front and back of the workpiece 22 can be provided with the respective surface structures 24 in two separate work steps with reclamping.

[0043] Figures 4a to 6 show components 26 in different embodiments in their respective orthographic projections according to European representation. Figures 4a and 4b show components 26 in which the surface structures 24 have been introduced into the same surface 20 of the workpiece 22. As can be seen in the respective views in Figures 4a and 4b, the components 26 are produced by introducing lines 34 with mutually perpendicular longitudinal directions into the surface 20 of the workpiece 22, wherein the respective intersecting lines 34 have the same cross-section extending perpendicular to the longitudinal direction. The components 26 shown in Figures 4a and 4b differ only in the depth, in the thickness direction, of the lines 34 introduced into the surface 20 by material removal.

[0044] In Fig. 5, component 26 is shown in an embodiment in which the first surface structure 24 and the second surface structure 24 have been incorporated into opposing surfaces 20 of the workpiece 22 for the production of component 26. As can be seen in Fig. 5, the lines 34 incorporated into the first surface 20 and the lines 34 incorporated into the second surface 20 differ in their respective cross-sections perpendicular to the longitudinal direction. The longitudinal direction of the first lines 34 and the second lines 34 are perpendicular to each other. It is provided that the first lines 34 and the second lines 34 differ in their lateral extent perpendicular to the longitudinal direction and in their distance from the respective adjacent line 34 of the same surface structure 24.This means that in the first surface structure 24, the lines 34 have a smaller lateral distance to each other than the lines 34 of the second surface structure 24 have a smaller lateral extent perpendicular to the longitudinal direction than the lines 34 of the second surface structure 24. This ensures that, as can be seen particularly well in Fig. 5, the resulting through-openings 32 at the respective intersection points 30 have the shape of an ellipse in their narrowest cross-section.By selecting a design of the respective cross-sections and longitudinal extension directions of the lines 34 of the respective surface structures 24, as well as by selecting a relative position of the surface structures 24 to each other, the respective dimensions and positions of the through-openings 32 in the component 26 can be set particularly precisely.

[0045] Figure 6 shows how two differently designed components 26 are stacked on top of each other in a stacking direction. Both stacked components 26 have surface structures 24 on their opposing surfaces 20. The porous structure for the electrochemical process is produced by stacking several components 26 in the stacking direction. Figure 6 clearly shows that the through-openings 32 of the first component 26 and the through-openings 32 of the second stacked component 26 can at least partially overlap each other in the stacking direction. In this case, the stacking direction runs parallel to the thickness direction D.The respective surface structures 24 can provide channels within the porous structure, allowing the respective through-openings 32 to allow a fluid, and thus a gas or liquid, to flow through the porous structure in the stacking direction.

[0046] In particular, a relative position of the surface structures 24, which are in the same

[0047] The workpiece 22 is inserted, selected in such a way that the intersection points 30 of the surface structures 24 result at points specified for the through openings 32.

[0048] It is intended that, for the introduction of each of the surface structures 24, a maximum of 80% of the thickness of the workpiece 22 is removed, whereby at least at one of the intersection points 30 for forming the through-opening 32, the sum of the removals exceeds the thickness of the workpiece 22. This limited removal depth per introduced surface structure 24 avoids drilling with removal in one direction. Furthermore, it prevents material from being displaced into areas of the workpiece 22 already exposed by material removal from the first surface structure 24 when the intersecting surface structures 24 are introduced into the same surface 20 of the workpiece 22.

[0049] The described invention is based on the understanding that the production of porous titanium structures is complex and costly, and requires improvement with regard to material consumption, build volume, and / or performance. The component 26 described in connection with the figures, which in this case is a laser-processed titanium foil, enables the production of a particularly efficient porous transport layer with regard to material consumption and permeability. To produce the porous transport layer, several components 26 are manufactured and stacked on top of each other. The components 26 are perforated and structured by means of the laser beam 12, whereby the permeability of the porous structure can be adjusted by setting the number and size of the respective through-holes 32.To introduce the surface structures 24 into the surface 20 of the workpiece 22, laser radiation is directed onto the surface 20 using the scanner optics 14. This structuring of the surface 20 allows for the optimization of properties of the porous structure that are important for electrolysis. The porous structure, composed of several components 26, enables particularly efficient supply of water to a proton exchange membrane or a catalyst-coated membrane of the electrolyzer, as well as particularly efficient removal of gases produced during electrolysis. An ultrashort pulse laser, a short pulse laser, and / or a continuous wave laser can be used, in particular, to introduce the at least one surface structure 24.In the described method for manufacturing component 26, the surface structures 24 and the through-holes 32 can be created and aligned in a targeted, reproducible, directional, and uniform manner. This enables component 26 to exhibit particularly high stability of the porous structure, highly precise media management, and exceptionally high conductivity. Due to the tightly tolerable structure depths and high flatness achieved, the described method for manufacturing component 26 allows for a particularly thin proton exchange membrane in the electrolyzer, thereby requiring significantly less catalyst material, especially iridium oxide.

[0050] The component 26 may in particular have been produced by surface-selective machining of the surface 20 of the workpiece 22.

[0051] The choice of the surface area of ​​the through-holes 32 enables targeted water supply and oxygen removal through component 26 while maintaining sufficient contact area with a boundary layer of the electrochemical system, particularly the catalyst layer. In the case of lines 34, especially parallel ones, and / or through-holes 32, which together occupy 10% to 80%, particularly 15% to 50%, of the area outside the contact area, 50% to 85% of the surface structure remains unprocessed, providing for planar contact with the catalyst layer. A residual lattice remaining after material removal from the workpiece 22 determines the mechanical stability of component 26. By selecting a structured surface area of ​​the workpiece 22, a larger contact area between component 26 and the catalyst layer is achieved compared to an unstructured workpiece 22.

[0052] It can be provided that between adjacent through-openings 32, a residual grid with a cross-sectional area of ​​at least 10% remains compared to the cross-sectional area of ​​the unmachined workpiece 22, corresponding to a center-to-center distance of the adjacent through-openings 32. This defined residual grid enables a particularly high mechanical stability of the component 26 to be achieved.

[0053] The present design provides for the creation of more than one through-opening 32 by means of a line 34. This allows for a particularly uniform distribution of water during water supply or gas during gas removal when the water or gas is guided through the porous structure.

[0054] If the intersecting surface structures 24 are introduced into the same surface 20 of the workpiece 22, then machining access is only required from one side of the workpiece 22. Machining can therefore be performed in a single setup. Furthermore, it can be achieved that the surface opposite the surface 20 with the surface structures 24 remains unmachined except for the through-holes 32 and is flat except for the through-holes 32. This allows the component 26 to be applied to the interface layer, in particular to the catalyst layer of the electrochemical system, over a particularly large area.

[0055] By arranging the through-openings 32 at the intersections 30 of the surface structures 24, a media flow can be established transversely to and through the component 26. By superimposed material removal at the intersections 30, the through-openings 32 can be created in the workpiece 22 without a separate drilling process and without increased positioning requirements.

[0056] The structuring of the opposing surfaces 20 of the workpiece 22, in particular with different properties of the surface structures 24 with respect to the orientation of the longitudinal direction of the lines 34, lateral dimensions of the lines 34, depth of the lines 34, spacing of the lines 34, dimensions of substructures and / or other properties, enables particularly high process efficiency, since for trenches or bores with a large aspect ratio, the typical energy requirement for double material removal to approximately half the depth is lower than for material removal over the full thickness of the workpiece 22. Furthermore, the requirements for positioning accuracy are particularly low, especially in a scan direction, when the through-openings 32 result at the intersections 30 of trench structures on both sides and thus of surface structures 24 introduced into opposing surfaces 20.The different orientations of the surface structures 24 with respect to the longitudinal direction of the respective lines 34 allow the through-openings 32 to be created by means of crossed trenches and thus by means of the crossed lines 34. Furthermore, particularly good control of media management is possible because the through-openings 32 and the respective trenches formed by the lines 34 are precisely aligned. In a porous transport layer, fine structures on the surface facing the catalyst layer offer advantages, while coarser structures on the side of the porous transport layer facing a bipolar plate are more favorable. Providing different surface structures 24 on the opposing surfaces 20 of the workpiece 22 enables tightly toleranced scaling of structure sizes with small material thicknesses of the porous structure.

[0057] The surface structure 24 is designed such that the lines 34 have an aspect ratio, i.e., a ratio of maximum removal depth to the input-side width of this line 34 and thus lateral extent of this line 34, of at least 0.4 in the longitudinal direction. This aspect ratio enables the component 26 to be provided with a particularly large surface area.

[0058] It is possible to coat one side of component 26, in particular with a corrosion-inhibiting layer, such as platinum, and / or a catalyst layer, especially comprising iridium oxide. This corrosion-inhibiting layer reduces oxidation of the titanium contained in the material in the oxygen generation area of ​​the electrochemical system and prevents an increase in electronic conductivity at low catalyst loading. If the catalyst layer is applied directly to the finely structured and mechanically stable porous transport layer (compared to a proton exchange membrane), a porous transport electrode results, which facilitates a thin design of the proton exchange membrane and a low catalyst loading.

[0059] By selecting a gas atmosphere in which the workpiece 22 is positioned during the application of the surface structures 24 by means of the laser beam 12, the surface chemistry of component 26 can be specifically influenced. If component 26 is intended to be applied to a catalyst layer or a proton exchange membrane of the electrochemical system during normal use, it can have a pyramidal structure on the side facing the catalyst layer or the membrane, allowing the respective protrusions of the structure to be pressed into the membrane or the catalyst layer. In this case, the protrusions of the structure extend less than the thickness of the membrane or catalyst layer over a region of the surface surrounding them. In particular, the protrusions of the structure extend to a height of less than 20 percent of the thickness of the membrane or catalyst layer.the catalyst layer over an area of ​​the structure's surface surrounding the elevations.

[0060] Using component 26 to create the porous transport layer allows it to be made particularly thin in the stacking direction, thus saving material and costs. It is possible to additively build a component on top of component 26 to create the porous structure.

[0061] It is possible that, in addition to introducing the respective surface structure 24 into the surface 20 of the workpiece 22, an oxide layer and / or particles can be removed from the surface 20 of the workpiece 22 using the laser beam 12. The laser beam 12 can, for example, be provided with functional periodic microstructures by means of direct laser interference patterning (DLIP).

[0062] Overall, the invention shows how a component 26 can be perforated for a porous transport layer.

[0063] Figure 7 schematically shows a cross-section 36 of the surface structures 24 according to a further embodiment. In the illustrated embodiment, the surface structures 24 each have a U-shaped cross-section 36. The through-openings 32 are correspondingly narrow, or designed as narrow passages or tunnels. In this case, the cross-section 36 does not extend through the narrowest cross-sections of the through-openings 32, so that the through-openings 32 are shown as blind holes in Figure 7. REFERENCE SYMBOL LIST

[0064] 10 Laser processing device

[0065] 12 Laser beam

[0066] 14 Scanner optics

[0067] 16 Laser input beam

[0068] 18 anamorphic focusing devices

[0069] 20 surface

[0070] 22 workpieces

[0071] 24 Surface structure

[0072] 26 components

[0073] 28 linear machining area

[0074] 30 Intersection

[0075] 32 Passage opening

[0076] Line 34

[0077] 36 Cross-section of surface structures B Width direction D Thickness direction L Length direction

Claims

PATENT CLAIMS 1. Component (26) for a porous structure, in particular for use in a plant for an electrochemical process, wherein the component is made from a planar workpiece (22), in particular from a sheet or foil, made in particular from a metallic material, with surface structures (24) on at least one surface (20) of the component (26), which have been introduced into the surface (20) by means of a laser beam (12) by material removal, wherein a through-opening (32) of the component (26) is formed at at least one intersection point (30) of the surface structures (24).

2. Component (26) according to claim 1, characterized in that the component (26) is configured to be used as part of a porous transport layer and / or the component (26) is configured to be used in a hydrogen electrolyzer or an electrodialyzer or a capacitive deionizer or an electroosmosis system or in a redox flow battery as the apparatus for the electrochemical process.

3. Component (26) according to claim 1 or 2, characterized in that the metallic material comprises titanium and / or stainless steel and / or nickel.

4. Component (26) according to one of the preceding claims, characterized in that the surface structures (24) each comprise a regular pattern.

5. Component (26) according to one of the preceding claims, characterized in that at least one of the surface structures (24) comprises a plurality of parallel lines (34).

6. Component (26) according to one of the preceding claims, characterized in that the surface structures (24) introduced into the workpiece (22) occupy 30% to 100%, in particular 50% to 85%, of the at least one surface (20) of the workpiece (22) having the surface structures (24) and / or a narrowest cross-section of all through-openings (32) in total occupy 10% to 80%, in particular 15% to 50%, of the area which is spanned by the width and length of the workpiece (22).

7. Component (26) according to one of the preceding claims, characterized in that the surface (20) of the component (26) having at least one surface structure (24) has at least one partial area which is free of the surface structure (24), wherein the at least one partial area extends in a frame form in a border region of the surface (20).

8. Component (26) according to one of the preceding claims, characterized in that a plurality of through-openings (32) are provided in the workpiece (22), wherein all through-openings (32) have a tolerance of less than 20 percent with respect to the cross-sectional area of ​​their narrowest cross-section and / or with respect to the distance of the narrowest cross-section to the at least one surface (20) of the workpiece (22) into which at least one surface structure (24) is provided.

9. Component (26) according to one of the preceding claims, characterized in that a ratio of the square of the thickness of the workpiece (22) to the cross-sectional area of ​​the narrowest cross-section of at least one of the through-openings (32) is less than or equal to 100 and greater than 1, in particular greater than 3.

10. Component (26) according to one of the preceding claims, characterized in that the workpiece (22) has a thickness of 20 micrometers to 200 micrometers and / or at least one of the through-holes (32) at its narrowest cross-section has a cross-sectional area of ​​less than 2000 square micrometers, in particular less than 500 square micrometers.

11. Component (26) according to one of the preceding claims, characterized in that the at least two of the intersecting surface structures (24) have different preferred directions to each other and are incorporated into the surface (20) on the same side of the workpiece (22).

12. Component (26) according to one of the preceding claims, characterized in that the surface structures (24) are incorporated into respective surfaces (20) of the workpiece (22) on opposite sides of the workpiece (22).

13. Component (26) according to one of the preceding claims, characterized in that a cross-section (36) of at least one surface structure (24), in particular of all surface structures (24) in each case, is U-shaped.

14. Method for producing a component (26) for a porous structure, in particular for use in a plant for an electrochemical process, in which a planar workpiece (22), in particular a sheet or foil, made in particular of a metallic material, is processed by means of a laser beam (12) by means of the laser beam (12) by means of material removal surface structures (24) into at least one surface (20) of the workpiece (22), whereby a through-opening (32) of the component (26) is created at at least one intersection point (30) of the surface structures (24).

15. Method according to claim 14, characterized in that for the introduction of each of the surface structures (24) at most 80 percent of the thickness of the workpiece (22) is removed, wherein at at least one intersection point (30) of the surface structures (24) the sum of the removals exceeds the thickness of the workpiece (22), thereby forming the through opening (32) at this intersection point (30).

16. A method according to claim 14 or 15, characterized in that the relative position of the surface structures (24) is selected such that the intersection points (30) of the surface structures (24) result at points predetermined for the through-openings (32).

17. A method according to any one of claims 14 to 16, characterized in that the laser beam (12) is pulsed in a range of 100 fs to 20 ps and / or has a diffraction coefficient in a range of 1 to 10, in particular in a range of 1 to 5, and especially in a range of 1 to 1.5.

Images