Production of a component with a gas-tight ion-conducting functional layer, and component

Abstract

The invention relates to a method for producing a component (11) with a gas-tight ion-conducting ceramic functional layer (9) comprising the following steps: - pressing ceramic powder material with a sintering additive through a pressing tool (1) at a pressure of at least 50 MPa, - sintering the pressed ceramic powder material and the sintering additive. The invention also relates to a component that can be produced using the method.

Description

[0001] Production of a component with a gas-tight, ion-conducting functional layer and component

[0002] The invention relates to a method for producing a component with a gas-tight, ion-conducting ceramic functional layer and to a component produced according to the method.

[0003] An example of a component with a gas-tight, proton-conducting ceramic functional layer is a fuel cell, which comprises a ceramic electrolyte material as a proton conductor from anode to cathode. The anode can be mounted on one side of the electrolyte layer. The cathode can be mounted on the opposite side of the electrolyte layer.

[0004] A fuel cell with a gas-tight, proton-conducting ceramic electrolyte material oxidizes fuel, namely hydrogen or hydrocarbons, electrochemically at the hydrogen electrode. In the case of the fuel cell, the hydrogen electrode is the anode. Gaseous fuels are absorbed at the surface of the hydrogen electrode in the presence of water vapor, with carbon dioxide being the primary reaction product. Hydrogen atoms are converted into H + - ions, i.e., protons. The protons pass through the electrolyte and then react with oxygen at the oxygen electrode, which in the case of a fuel cell is the cathode. The reaction produces water, electricity, and heat. The generated heat can keep the fuel cell at a suitable operating temperature of, for example, 400°C to 700°C.

[0005] The electrolyte material may comprise or consist of a combination of BaZrOs and BaCeOs (BZCY).

[0006] The hydrogen electrode of the fuel cell can consist of a gas-permeable, porous ceramic-metal composite material (so-called cermet) and contain a proton-conducting material as the ceramic phase (e.g., BZCY) and nickel as the metallic phase. The conversion of the hydrogen atoms into H + -ions occurs preferentially at the three-phase boundary between the gas phase, nickel, and proton-conducting material. If the proton-conducting material also has electrical conductivity (so-called mixed conductivity) in addition to proton conduction, the conversion of the hydrogen atoms into H + -ions also take place on the surface of the mixed-conducting material, thereby increasing the electrochemical activity of the hydrogen electrode.

[0007] The fuel cell's oxygen electrode can be made of a gas-permeable, porous, mixed-conducting ceramic. One example is perovskites based on lanthanum-strontium-cobalt-iron oxide. Alternatively, the oxygen electrode can be made of a gas-permeable, porous, two-phase ceramic material, with one ceramic phase conducting protons and the other conducting electrons.

[0008] The fuel cell described above is also called a proton conducting fuel cell (PCFC).

[0009] The described electrode-electrolyte unit of a PCFC can also be part of an electrolysis cell, which is then called a proton conducting electrolysis cell (PCEC).

[0010] An electrolysis cell with a gas-tight, proton-conducting ceramic electrolyte material functions in reverse, converting water and electric current into hydrogen at the hydrogen electrode, which then serves as the cathode, and oxygen at the oxygen electrode, which then serves as the anode. The operating temperature can then also be 400°C to 700°C.

[0011] Powder-based manufacturing processes such as tape casting, screen printing, or wet powder spraying are not particularly suitable for the production of such components with a gas-tight, ion-conducting electrolyte, as high processing temperatures of more than 1350°C or inorganic sintering additives are required to achieve sufficient gas tightness. High processing temperatures and inorganic sintering additives cause problems that result in unsatisfactory electrochemical properties.

[0012] The object of the invention is to be able to produce components with a gas-tight, ion-conducting ceramic functional layer with improved properties. In particular, production should be possible with a comparatively low sintering temperature. Shrinkage of materials due to thermal treatments should preferably be avoided in order to prevent thermally induced mechanical stresses between the individual layers, which can lead to failure due to cracking or detachment of the layers. Sintering aids based on inorganic solids should preferably be avoided, since such sintering aids adversely affect electrochemical properties.

[0013] The object of the invention is achieved by a method having the features of the first claim and by a component having the features of the dependent claim. Advantageous embodiments are specified in the dependent claims.

[0014] To produce a component with a gas-tight, ion-conducting ceramic functional layer, ceramic powder material is first pressed together with a sintering additive through a pressing tool. The pressing pressure can be at least 50 MPa, at least 100 MPa, or at least 200 MPa. The pressed powder material and the sintering additive pressed with it are sintered.

[0015] By pressing the ceramic powder material together with the sintering additive, relatively low sintering temperatures are sufficient during the subsequent sintering process to achieve a high density. The density achieved after pressing with the sintering additive can be sufficient to achieve sufficiently high gas tightness even without a subsequent sintering step, for example, for the operation of a fuel cell or electrolysis cell.

[0016] The ceramic powder material for the production of proton-conducting electrolytes can comprise BaZrO 2 and / or BaCeCh 2 or consist of this combination. By varying the mixing ratio and adding additional oxides, the stoichiometry of proton-conducting materials can be varied within a wide range. Alloy systems for metal-supported PCFC / PCEC cells, such as BaZrO 2 - x - yCe 2 , can be used. x YyO3-d (BZCY), SrZri-x-yCe x YyO3-d (SZCY) and Lai- x Ca xNbO4-d (LCN) with variable x,y values ​​can be used as powder material; d denotes an optionally introduced substoichiometry of the oxygen atoms in the lattice, which can improve the electrochemical properties. Depending on the sintering additives used, the process can also be applied to other oxide-ceramic electrolyte materials such as Y2O3-doped ZrO2 (YSZ), Sc2O3-doped ZrO2 (ScSZ), Gd2O3-doped CeO2 (GDC)). The process can also be applied to oxide powder mixtures (e.g. NiO-BZCY, NiO-SZCY, NiO-LCN, NiO-YSZ, NiO-ScSZ, NiO-GDC). Another area of ​​application is mixed-conducting gas separation membranes (e.g. Lai). x Sr x Coi.yFeyO3-d (LSCF), Lai. x Sr x COyO3-d (LSC), Bai- x Sr x Coi.yFe y O3-d (BSCF), Lai. x Sr x Mn yC>3-d (LSM)). The average grain size of the powder material can be greater than 10 nanometers and / or less than 1 micrometer. The grain size distribution can be monomodal with a maximum grain size in the range of 30 nanometers and 800 nanometers. The layer thickness of the functional layer after sintering can be greater than 2 μm and / or less than 200 μm. 5-10 μm is ideal. The leakage rate of the functional layer can be below 10' 3 hPa-dm 3 -s' 1 -cm' 2 The leak rate is determined using the differential pressure test method (see https: / / www.drwiesner.de / produkte / dichtheitspruefgeraete / integra.html).

[0017] Electrodes can be applied to both sides of the functional layer to create an electrode-electrolyte unit that can be part of a fuel cell or part of an electrolysis cell. At least one electrode is gas-permeable. Preferably, both electrodes are gas-permeable.

[0018] The functional layer is in particular a proton-conducting ceramic.

[0019] In one embodiment, a gas-permeable substrate can be placed in the compression mold. The ceramic powder material and the sintering additive can then be placed in the compression mold, specifically onto the gas-permeable substrate. The gas-permeable substrate, with the ceramic powder material and the sintering additive on it, can then be pressed. Sintering can then take place. In this way, a composite for a component can be produced in just a few steps. This composite comprises the gas-tight, ceramic functional layer and a gas-permeable layer attached to it. A mixed-conducting gas separation membrane can be produced in this way.

[0020] In a further embodiment, a gas-permeable, porous electrode can be applied to the gas-permeable substrate. The pore size of the electrode can be smaller than the pore size of the gas-permeable substrate, thereby facilitating the deposition of the gas-tight functional layer. The gas-permeable, porous electrode can be produced by processes such as screen printing, spraying, or film casting with subsequent sintering. Alternatively, it is possible to use the process described above (pressing the powder with a sintering additive followed by sintering at a reduced temperature) for an electrode material as well. An electrochemical cell can preferably be produced using this embodiment.For the function of the electrochemical cell, the application of an additional electrode on the substrate is advantageous if a substrate itself either has no electrochemical properties (this is the case with an electrochemically inert substrate) or has electrochemical properties that are too poor for practical application.

[0021] The gas-permeable substrate consists, in particular, of an electrically conductive material. The gas-tight, ceramic functional layer is, in particular, electrically non-conductive. Such a component can be part of a fuel cell or an electrolysis cell. The gas-tight, ceramic functional layer can be the electrolyte layer of a fuel cell or an electrolysis cell. The electrically conductive, gas-permeable substrate can be an electrode of the fuel cell or the electrolysis cell.

[0022] The gas-permeable substrate can be manufactured using powder technology and pre-sintered, for example, at temperatures of more than 1000°C and / or less than 1400°C. The gas-permeable substrate can be made of metal. The gas-permeable substrate can therefore be a porous layer made of metal. The metal can be stainless steel. The stainless steel can have a high chromium content. The chromium content can be more than 16 wt.% and / or less than 30 wt.%. For example, the metal can be an ITM Fe-26% Cr alloy. Other ferritic iron-chromium alloys can also be suitable. Other metallic high-temperature alloys, such as nickel-based alloys, are possible.

[0023] Alternatively, the metallic substrate can consist of a sheet metal into which gas-permeable openings are introduced. The openings can be created mechanically (e.g., by punching, drilling, or stretching over an edge) or using a laser beam.

[0024] The gas-permeable substrate is preferably thicker than the functional layer, both before and / or after sintering, to achieve high-performance fuel cells or electrolysis cells. The thickness of the gas-permeable substrate can be at least 50 μm and / or no more than 1000 μm. The preferred thickness of the substrate is in the range of 200-300 μm.

[0025] Regularly, due to the pressing with a sintering additive,

[0026] Sintering temperatures of less than 1400°C or less than 1350°C are required to achieve a gas-tight, ceramic functional layer that can conduct ions such as protons. High-temperature alloys, in particular, are well-suited to these sintering temperatures. Thus, at sintering temperatures of less than 1400°C, less than 1350°C, or less than 1300°C, metal substrates can be pressed with the ceramic powder material in a single step and subsequently sintered.

[0027] After pressing and sintering, an electrode can be applied to the ceramic functional layer. The electrode material can be applied, for example, by screen printing, tape casting, or spraying. After the electrode material has been applied, the material can be sintered again. The sintering can advantageously be carried out at a temperature lower than that used during the initial sintering. The temperature for the sintering can be less than 1300 °C and / or more than 600 °C.

[0028] The electrode material can be an electrically conductive perovskite. The electrode material can be based on the alloy systems Lai-xSr x Coi-yFeyO3-d (LSCF), Lai. xSr x Co y O3-d (LSC), Lai- x Sr x Mn yO3-d (LSM) with varying x,y values. Alternatively, the lanthanum in these structures can be replaced with other elements such as samarium, barium, or praseodymium. Furthermore, it is possible to add the electrolyte material to the electrode to increase the number of three-phase boundaries in the electrode.

[0029] A sintering additive is preferably liquid to achieve particularly good results. The amount of sintering additive is preferably selected such that the powder grains are completely covered by the sintering additive. The sintering additive can be adsorbed onto the surfaces of the powder grains. There is then at least a monomolecular layer of sintering additive on the surfaces of the powder grains. To ensure this, an excess of sintering additive can be added. This is the case when more than one monomolecular layer of the sintering additive is present on the powder particles. The amount of sintering additive can be selected such that all pores in the powder material are completely filled with sintering additive. The amount of sintering additive can also be selected such that more sintering additive is added than the pore volume of the powder bed. In this case, part of the sintering additive is pressed out of the compression tool during compression.This variant can be advantageous for reorienting the powder particles at the beginning of the pressing process. The sintering additive can be added to the pressing tool before or after the ceramic powder grains. The sintering additive can be added to the pressing tool together with the ceramic powder grains. For this purpose, the sintering additive can be homogeneously mixed with the ceramic powder in an external mixing unit.

[0030] However, it is also possible to compact dry ceramic powder, for example, at a pressure of no more than 400 MPa and / or at a pressure of at least 50 MPa. Liquid sintering additive can then be added. Capillary forces then ensure that the sintering additive is evenly distributed throughout the powder layer.

[0031] The preferred sintering additive is a liquid in which components of the ceramic powder dissolve. One possible sintering additive is water. To increase solubility, the pH of the sintering additive can be specifically adjusted. Organic solvents can also be used as sintering additives. Alternatively, ceramic precursors can be used as sintering additives. Ceramic precursors are liquids that are typically used for powder synthesis. Examples include liquid metal nitrates, metal citrate complexes, or metal alkoxylates. As an alternative to liquid sintering additives, solid powders containing functional groups such as hydroxides can also be used as sintering additives. Examples are NaOH and KOH powder. These functional groups enable densification at moderate temperatures similar to that achieved with liquid sintering additives.

[0032] Pressing is preferably carried out at temperatures of at least 100 or 200 °C and / or at temperatures of no more than 600 °C or no more than 500 °C or no more than 400 °C. The temperature prevailing during pressing is preferably selected such that almost complete densification of the ceramic functional layer is achieved. During pressing, the powder material generally shrinks because the particles of the powder material compact and pore spaces are filled. The higher the density achieved during pressing with the sintering additive, the lower the shrinkage in the subsequent sintering step, which can be carried out at temperatures above 400 °C or above 500 °C or above 600 °C. In this way, a component with further improved desired properties can be obtained, in particular when a substrate is used that does not exhibit any sintering shrinkage at the sintering temperature.

[0033] The pressure used for pressing can be up to 600 MPa or up to 500 MPa, for example.

[0034] In one embodiment of the invention, the ceramic powder material is pressed together with the sintering additive to achieve a density of at least 80%, 90%, 95%, or 99% of the theoretical density. Such results are possible at high pressing pressures of at least 50 MPa due to the sintering additive. Such densities can, in principle, be achieved even when pressing at room temperature. If closed porosity is achieved through pressing, the layer can meet the gas-tightness specification immediately after pressing.

[0035] Generally, the sintering additive is selected so that it interacts with the ceramic. The sintering additive interacts with the ceramic, for example, when it can dissolve one or more elements from the ceramic and / or react with one or more elements of the ceramic.

[0036] Following compression, in an advantageous embodiment of the invention, the pre-compacted layer can obtain its final shape through a subsequent sintering step at temperatures of, for example, above 600°C. Residues of the sintering additive can be removed in this way. During the sintering step, the residues of the sintering additive on the grain boundaries can be removed, thereby improving the gas impermeability and ionic conductivity, and thus also the performance of the electrolyte. The higher the density of the layer after compression, the lower the resulting sintering shrinkage in the subsequent optional sintering step and the lower the sintering temperature required to achieve the final shape, if necessary.

[0037] In one embodiment of the invention, the layer to be sintered is preferably applied to a substrate that exhibits no or virtually no sintering shrinkage during the sintering step in order to avoid destructive stresses and the associated disadvantages. The substrate can be made of metal. The substrate can then serve as an electrode. The substrate can be made of a cermet or a ceramic. Reducing this sintering shrinkage to a minimum is advantageous if the layer exhibits no shrinkage or practically relevant shrinkage. This can be the case, for example, when using metallic substrates. A further advantage of the liquid sintering additive over inorganic sintering additives is its residue-free removal during the sintering step, thereby avoiding unwanted impurities and secondary phases in the electrolyte.

[0038] The process enables a component to be coated with a gas-tight, ion-conducting, ceramic functional layer with a leakage rate of less than 10' 3 hPa-dm 3 -s' 1 -cm' 2 and / or with an ionic conductivity of more than 10' 3 S-cnv 1 at 600°C and / or with a sintering additive that is completely removed during the final sintering step. A porous, gas-permeable, metal substrate can be attached to one side of the functional layer. The metal can be selected to withstand sintering temperatures of less than 1350°C or less than 1300°C. The metal can be a ferritic iron-chromium steel. The chromium content in the steel can be at least 16% by weight and / or no more than 30% by weight.

[0039] The invention enables an economically and technologically attractive design for creating metal-supported, proton-conducting fuel and electrolysis cells. The combination of a functional ceramic layer and a metallic substrate results in high electrochemical performance, mechanical stability, simple joining technology, and moderate material costs.

[0040] The invention enables a significant reduction in the sintering temperature, thus minimizing the risk of interfacial reactions and interdiffusion processes. The invention enables the production of gas-tight functional layers on porous metallic substrates that no longer exhibit sintering shrinkage during thermal treatment. The invention completely eliminates the need for sintering aids based on inorganic solids such as NiO, ZnO, and CO3O4, which can alter the chemical composition of the ceramic functional layers and thus alter their functional properties. Disadvantageous diffusion barriers between the metal substrate and the ceramic functional layer are eliminated. Such diffusion barriers are therefore fundamentally nonexistent. Interdiffusion and processing problems are eliminated.High ion conductivity can be achieved by sintering at comparatively low sintering temperatures. Sintering also ensures that any undesirable secondary phases that may still be present after pressing with the sintering additive are converted or completely removed, so that secondary phases do not adversely affect electrochemical properties.

[0041] The sintering additive can be introduced into the interior of the press tool via a dispensing system. A liquid sintering additive is generally selected specifically for the material. A liquid sintering additive fulfills the following functions during pressing and the associated compaction process: The liquid phase improves the compressibility of the powder by reducing friction between the powder particles and wall friction. The liquid phase modifies the interface between the powder particles, thereby changing the sintering kinetics so that, upon application of sufficiently high pressure (usually between 50 and 500 MPa), almost complete compaction of the powder is achieved at temperatures below 600°C, 500°C, or 400°C. At temperatures not exceeding 600°C, 500°C, or 400°C, the powder can be partially dissolved by the sintering additive.During further processing, the dissolved material reprecipitates at the grain boundaries. This occurs particularly when the proportion of the liquid phase of the sintering additive decreases with increasing temperature.

[0042] To enhance a beneficial dissolution / reprecipitation process, a ceramic precursor can be added to the liquid sintering additive.

[0043] Pores created by evaporation / desorption are removed from the functional layer by mechanical pressure. The functional layers produced by this process are characterized by a very high relative density of more than 90% of the theoretical density, but may still contain a residual portion of the generally amorphous interfacial phase. Through adapted thermal post-treatment, i.e., sintering, at significantly lower temperatures than conventional processes, for example, less than 1300°C, amorphous interfacial phases can be returned to their original phase, thus ensuring the full functionality of the functional layer material.

[0044] The processing temperature of the ceramic functional layers, and in particular of the electrolyte, can therefore be significantly reduced compared to processes known from the state of the art, so that the energy requirement for the heat treatment and thus the emission of greenhouse gases is reduced.

[0045] For the densification of the electrolyte, no inorganic, powder-based sintering additives such as NiO, ZnO, CO3O4 are required, which complicate the reproducible production of functional layers and can impair the electrochemical properties through secondary phase formation. The invention enables ceramic functional layers to be densified to a high density of more than 90% of the theoretical density at temperatures below 400°C. In this way, the sintering shrinkage of these layers during subsequent sintering is minimized, so that co-shrinkage of a metal substrate is not necessary to achieve gas-tightness of ceramic membranes. Furthermore, mechanical stresses induced in the layer composite are avoided. The significant reduction in the processing temperature reduces the occurrence of adverse interdiffusion effects and interfacial reactions.Material combinations and sintering temperatures can be selected so that diffusion barrier layers are not required. The use of liquid sintering additives, which can optionally also contain ceramic precursors, enables high densification (> 90%) of ceramic functional layers through a pressure-assisted densification process even at temperatures below 400°C. It is possible to produce gas-tight, ceramic functional layers on porous substrates. To achieve virtually complete gas impermeability, a further sintering step is carried out at higher temperatures. However, the temperature for this sintering step is significantly lower than for conventional sintering. Furthermore, shrinkage of the substrate during the heat treatment is no longer absolutely necessary to achieve gas impermeability of the functional layer.As a further advantage, the use of sintering additives based on inorganic solids can be dispensed with, which reliably prevents the formation of secondary phases.

[0046] The invention primarily relates to the production of metal-supported, proton-conducting electrochemical cells that can be operated in fuel cell and electrolysis mode (so-called proton-conducting fuel cells / proton-conducting electrolysis cells PCFCs / PCECs), but can also be applied to other ceramic functional materials and alternative substrate materials (e.g., all-ceramic layer systems). Depending on the application, suitable sintering additives can be selected that cover the surface of the powder particles with at least one monomolecular layer and exhibit dissolution / reprecipitation behavior in contact with the ceramic functional material at temperatures < 400°C.

[0047] Die beschriebenen Vorteile der Erfindung werden vor allem im Vergleich zu folgendem Stand der Technik erzielt:

[0048] • N. Sata, F. Han, H. Zheng, A.M. Dayaghi, T. Norby, M. Stange, R. Semerad, R.

[0049] Costa, Development of Proton Conducting Ceramic Cells in Metal Supported Architecture, ESC Meet. Abstr. MA2021-03 (2021) 95-95; https: / / doi.Org / 10.1149 / ma2021 -03195mtgabs;

[0050] • R. Wang, G.Y. Lau, D. Ding, T. Zhu, M.C. Tucker, Approaches for co-sintering metal-supported proton-conducting solid oxide cells with Ba(Zr,Ce,Y,Yb)O3-d electrolyte, Int J. Hydrogen Energy. 44 (2019) 13768 — 13776; https: / / doi.org / 10.1016 / jijhydene.2019.03.181 ;

[0051] • G.Y. Lau, M.C. Tucker, Development of Metal-Supported Proton-Conducting Solid Oxide Cells Via Co-Sintering, ECS Meet. Abstr. MA2021-03 (2021) 83-83; https: / / d0i.0rg / l 0.1149 / ma2021 -03183mtgabs ;

[0052] • MC Tucker, Progress in metal-supported solid oxide electrolysis cells: A review,

[0053] Int. J Hydrogen Energy. 45 (2020) 24203-24218; https: / / doi.Org / 10.1016 / i.iihydene.2020.06.300.

[0054] In the preferred embodiment, the sintering additive is liquid. Alternatively, the sintering additive can also be a suitable powder whose structure contains functional groups that enable densification at low temperatures. An example of this is metal hydroxide powder (e.g., NaOH or KOH). Pressing with the sintering additive is preferably carried out at temperatures of at least 20°C, at least 300°C, or at least 600°C. The pressing pressure can be applied before or during heating.

[0055] The sintering temperature during the sintering step, which is carried out after pressing, is preferably selected depending on the ceramic powder material and / or the particle size of the ceramic powder material and / or the impurities in the ceramic powder material and / or the densification achieved after pressing and / or the sintering atmosphere and / or other sintering parameters such as heating rate and holding time at sintering temperature. The sintering temperature is higher than the temperature used during pressing. The sintering temperature is higher than the subsequent operating temperature of the electrochemical cell if the component serves as an electrochemical cell, such as an electrolysis cell or fuel cell. The sintering temperature can generally be reduced by at least 100°C compared to the temperature at which the electrolyte is conventionally sintered.

[0056] The invention is explained in more detail below with reference to figures.

[0057] It shows

[0058] Figure 1 : Pressing tool;

[0059] Figure 2: Press tool with substrate and functional layer inside;

[0060] Figure 3: Electrode-electrolyte unit;

[0061] Figure 4: Fuel cell;

[0062] Figure 5: Electrolysis cell.

[0063] Figure 1 shows a pressing tool 1. The pressing tool 1 comprises side walls 2 which enclose an interior space 3. On the top side there is a pressing ram 4 which, as indicated by an arrow, can be moved downwards towards the interior space 3 of the pressing tool 1 and back again for pressing. On the underside there is a base 5, which can also be designed as a movable pressing ram. If the base 5 is designed as a movable pressing ram, the base 5 can be moved upwards for pressing, as indicated by an arrow, and thus into the interior space 3. The base 5 can then also be moved back again. The pressing tool 1 comprises a heating device 6, via which the interior of the pressing tool 1 can be heated.

[0064] To produce an electrode-electrolyte unit, the press ram 4 can first be moved upwards out of the interior 3 so that the interior 3 of the pressing tool 1 is accessible from above. A porous, gas-permeable substrate 7 made of metal can be brought into the interior 3 of the pressing tool 1 from above. The substrate 7 can either have electrode properties itself or optionally have a gas-permeable, porous electrode 8 with a pore size smaller than the pore size of the substrate 7 on its upper side. The gas-permeable, porous electrode 8 can be applied before the substrate 7 is inserted into the pressing mold 1 using the methods mentioned above. Alternatively, the electrode 8 can be processed analogously to the electrolyte 9.In this case, following the insertion of the substrate 7, a layer of the ceramic powder for the electrode 8 and a sintering additive is added, followed by a layer of the powder for the electrolyte 9 and a sintering additive. If the electrode 8 is already present on the top side of the substrate 7, there is no need to fill in the ceramic powder for the electrode 8. The opening of the interior 3 is closed again by the stamp 4. The interior 3 is brought to a temperature of 100°C to 600°C by the heating device 6. Once the interior 3 has been brought to a temperature of 100°C to 600°C, the stamp 4 is moved towards the interior 3 at a pressure of 50 to 500 MPa in order to press the materials 7, 8, and 9 introduced into the interior. The base 5 can be moved into the interior 3 in the same way, if necessary. Figure 3 shows the compressed state.

[0065] Following the pressing, a separate electrode layer 10 can be applied to the electrolyte layer 9 using the aforementioned methods. After pressing and applying the electrode layer 10, an electrode-electrolyte unit 11 shown in Figure 3 has been produced.

[0066] The electrolyte unit 11 can be part of a fuel cell, as outlined in Figure 4. Fuel such as hydrogen, i.e. H2, is supplied to the metal substrate 7. The hydrogen passes through the pores of the porous metal substrate 7 to the electrode layer 8. By releasing electrons e-, protons, i.e. H, are formed from the hydrogen at the anode 8. +, which then pass through the electrolyte 9 and thus reach the electrode 10. As shown, the electrons e- flow via an electrical conductor and an electrical load from the metallic substrate 7 to the electrode 10, which is thus a cathode of the fuel cell. The electrode layer 8 on the metallic substrate 7 is therefore the anode of the fuel cell. The electrode layer 8 can optionally be omitted if the substrate is made of the anode material (e.g., a ceramic-metal composite such as BZCY-Ni).

[0067] At the cathode 10, the protons, supplied oxygen, i.e. supplied O2, and the electrons form e-water, i.e. H2O.

[0068] The electrolyte unit 11 can be part of an electrolysis cell, as outlined in Figure 5. A voltage source is applied to the two electrodes 8 and 10 such that electrons flow from the electrode 10 via the metal substrate 7 to the porous, gas-permeable electrode 8. The electrode 8 is then the cathode and the electrode 10 the anode of the electrolysis cell. Water is supplied to the electrode 10. Oxygen is produced from the supplied water with the release of protons. The protons pass through the electrolyte layer 9 and recombine on the cathode side to form hydrogen with the absorption of electrons. The electrode layer 8 can optionally be omitted if the substrate is made of the electrode material (e.g., a ceramic-metal

[0069] composite material such as BZCY-Ni).

Claims

Claims 1. A method for producing a component (11) with a gas-tight, ion-conducting ceramic functional layer (8) comprising the steps: • ceramic powder material is pressed with a sintering additive through a pressing tool (1) with a pressure of at least 50 MPa, • the pressed ceramic powder material and the sintering additive are sintered.

2. Method according to the preceding claim, characterized in that a gas-permeable substrate (7) is brought into the pressing tool (1), subsequently the ceramic powder material and the sintering additive are brought into the pressing tool and specifically onto the gas-permeable substrate (7) and the gas-permeable substrate (7) with the ceramic powder material and the sintering additive located thereon is pressed.

3. Method according to the preceding claim, characterized in that the gas-permeable substrate (7) consists of metal.

4. Method according to the preceding claim, characterized in that the gas-permeable substrate (7) made of metal contains an electrode (8) on the upper side.

5. Method according to one of the preceding claims, characterized in that the gas-permeable substrate (7) consists of an electrode material.

6. Method according to one of the preceding claims, characterized in that sintering is carried out at temperatures of less than 1400 °C or less than 1350 °C or not more than 1300 °C and / or at temperatures of more than 600 °C.

7. Method according to one of the two preceding claims, characterized in that after sintering, an electrode (10) is applied to the functional layer (9).

8. Method according to the preceding claim, characterized in that after the application of the electrode (10) sintering is carried out at a temperature which is lower than the temperature at which sintering was carried out previously.

9. Method according to one of the preceding claims, characterized in that the sintering additive is introduced into the pressing tool (1) in liquid form.

10. Method according to one of the preceding claims, characterized in that a ceramic precursor is introduced into the pressing tool (1).

11. Method according to one of the preceding claims, characterized in that the sintering additive is selected from: water, a water-based solution with a defined pH value, organic solvents and / or that the ceramic precursor is selected from dissolved metal nitrates, metal citrates and metal alkoxylates.

12. Method according to one of the preceding claims, characterized in that the ceramic powder material is pre-pressed, the sintering additive is added to the pre-pressed ceramic powder material and subsequently the pre-pressed sintering material is pressed together with a substrate (7).

13. Method according to the preceding claim, characterized in that pre-pressing is carried out with a pressure of less than 500 MPa and / or more than 50.

14. Method of manufacturing a component according to one of the preceding claims, characterized in that pressing is carried out at temperatures of at least 100°C and / or at temperatures of not more than 600°C.

15. Method according to one of the preceding claims, characterized in that pressing is carried out at a pressure of less than 500 MPa.

16. Component producible by a method of one of the preceding claims, with a gas-tight, ion-conducting, ceramic functional layer (9) with a leakage rate of less than 10' 3 hPa-dm 3 -s' 1 -cm' 2 and / or with an ionic conductivity of more than 10' 3 S-cnv 1 at 600°C as and / or with a Sintering additive that is completely converted into the ceramic after sintering or removed without residue, and / or with a density greater than 95% of the theoretical density.

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