Method for manufacturing hybrid coating layer

Abstract

The present disclosure relates to a method for manufacturing a hybrid coating layer in which an oxide layer having a dense structure and reduced degradation can be produced on metal substrates having various shapes, such as a flat plate shape, a flow path pattern shape, a porous shape, a mesh shape, and a waffle shape, by first performing a sputtering process on the metal substrates to form a first coating layer, applying an electric field to the first coating layer to form a second coating layer, and then performing a heat treatment.

Description

Method for manufacturing a hybrid coating layer

[0001] The present disclosure relates to a method for manufacturing a hybrid coating layer, and more specifically, to a method for manufacturing a hybrid coating layer having a dense structure and no degradation on a metal substrate having various shapes such as a flat shape, a flow channel pattern shape, a porous shape, a mesh shape, and a waffle shape by forming a first coating layer by a sputtering process, forming a second coating layer on the first coating layer by a wet chemical coating process, and having an oxide layer having a dense structure and no degradation on a metal substrate having various shapes through a heat treatment process.

[0002] A Solid Oxide Fuel Cell (SOFC) stack is constructed by stacking multiple individual cells to maximize electricity production. Each cell consists of a fuel electrode (anode), an air electrode (anode), and a solid electrolyte, generating electricity through a chemical reaction between fuel and oxygen. SOFC stacks offer high energy efficiency and have the advantage of being able to use various fuels because they operate at high temperatures. Within the stack, each cell is connected by separators, which help ensure stable electricity production by separating electricity from gas. Separators provide a charge transfer path between cells and act as a barrier to prevent the mixing of oxygen from the anode and hydrogen from the cathode. These separators must possess excellent electrical conductivity and chemical stability, and metals are frequently used as separator materials due to their mechanical strength, ease of manufacturing, and cost-effectiveness. Metal separators require a protective coating layer that demands high electrical conductivity, a dense structure, the ability to prevent chromium volatilization, and chemical compatibility with the metal. However, stainless steel, which is mainly used as a separator, exhibits deterioration problems such as increased resistance due to oxidation when used for a long period at high temperatures of 600 to 1000°C, and electrochemical performance may be degraded due to the volatilization of chromium components. Korean Published Patent No. 10-2015-0138105 (April 7, 2017) disclosed a coating composition for a solid oxide fuel cell metal separator and a method for manufacturing the same, wherein a protective coating layer is prepared on a separator substrate by a spray coating method using metal materials such as copper (Cu), gold (Au), silver (Ag), nickel (Ni), palladium (Pd), platinum (Pt), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), and tantalum (Ta) to form a coating composition. However, the conventional method of manufacturing a protective coating layer by spray coating a metal-containing coating composition had the problem that the surface of the coating layer was prone to deterioration and it was difficult to produce an oxide layer with a dense structure.

[0003] In addition, separators in solid oxide fuel cell (SOFC) stacks play important roles such as electrical conductivity, gas separation, and mechanical support, so they can be designed in various shapes. The shape of the separator can have a significant impact on the efficiency and stability of the stack. For example, separators can be manufactured in various shapes such as flat shapes, flow channel pattern shapes, porous shapes, mesh shapes, and waffle shapes. Korean Patent Publication No. 10-2003-0060668 (July 16, 2003) disclosed a separator having microchannels and a method for manufacturing the same. The separator disclosed in the prior art was manufactured with a microchannel shape, and if a protective coating layer is formed on a separator having such a microchannel shape using a conventional wet chemical coating process, problems such as uniformity, pore formation, coating issues on inclined surfaces and edges, and cracking and delamination after heat treatment may occur. Therefore, for protective coating layers formed on separator plates having various shapes, there is a need for a coating method capable of producing a dense and uniform coating layer without the surface of the coating layer deteriorating.

[0004] This project was carried out with funding from the Ministry of Trade, Industry and Energy (MOTIE) and support from the Korea Energy Technology Evaluation Institute (KETEP) (Project No.: RS2025-06342968).

[0005] [Prior Art Literature]

[0006] [Patent Literature]

[0007] Korean Published Patent No. 10-2015-0138105 (April 7, 2017)

[0008] Korean Patent Publication No. 10-2003-0060668 (July 16, 2003)

[0009] Accordingly, the present disclosure is devised to solve the above-mentioned problems, and more specifically, it relates to a method for manufacturing a hybrid coating layer by forming a first coating layer on a metal substrate by a sputtering process to form an oxide layer having a dense structure and without degradation on a metal substrate having various shapes such as a flat shape, a flow path pattern shape, a porous shape, a mesh shape, or a waffle shape, applying an electric field to the first coating layer to form a second coating layer, and forming an oxide layer by a heat treatment process.

[0010] A method for manufacturing a hybrid coating layer according to the present disclosure comprises: a first coating layer forming step of forming a first coating layer by coating a first material on a metal substrate with a predetermined thickness; a second coating layer forming step of forming a second coating layer by applying an electric field to the first coating layer and coating a second material having a spinel structure; and a heat treatment step of heat-treating the metal substrate on which the first coating layer and the second coating layer are formed.

[0011] In addition, in the method for manufacturing a hybrid coating layer according to the present disclosure, the first coating layer formation step forms the first coating layer using any one of evaporation deposition, sputtering, chemical vapor deposition (CVD), physical vapor deposition (PVD), and atomic layer deposition (ALD).

[0012] In addition, in the method for manufacturing a hybrid coating layer according to the present disclosure, the first material is a transition metal, and the transition metal is selected from one or more of iron (Fe), nickel (Ni), chromium (Cr), vanadium (V), titanium (Ti), copper (Cu), manganese (Mn), and cobalt (Co).

[0013] In addition, in the method for manufacturing a hybrid coating layer according to the present disclosure, the predetermined thickness is formed to be 0.2㎛ to 2㎛.

[0014] In addition, in the method for manufacturing a hybrid coating layer according to the present disclosure, the second coating layer forming step further includes a mixed solution forming step of forming a mixed solution containing the second material by dispersing the second material in powder form in a solvent before applying the electric field.

[0015] In addition, in the method for manufacturing a hybrid coating layer according to the present disclosure, the solvent is selected from the group consisting of water, methanol, ethanol, propanol, butanol, toluene, acetone, and acetylacetone.

[0016] In addition, in the method for manufacturing a hybrid coating layer according to the present disclosure, the electric field is performed for 1 second to 300 seconds under a voltage of 10V to 80V.

[0017] In addition, in the method for manufacturing a hybrid coating layer according to the present disclosure, the second material is Mn x Cu 3-x O4, Mn x Co 3-x O4, Mg x Cr 3-x O4, Ni x Fe 3-x O4, Zn x Al 3-x O 4, , Li x Mn 3-x It is selected as one of O4.

[0018] In addition, in the method for manufacturing a hybrid coating layer according to the present disclosure, the heat treatment step includes a first heat treatment step, and the first heat treatment step is heat treated at 700°C to 1200°C in a reducing atmosphere.

[0019] In addition, in the method for manufacturing a hybrid coating layer according to the present disclosure, the heat treatment step further comprises a second heat treatment step, and the second heat treatment step is heat treated at 600°C to 1000°C in an air atmosphere.

[0020] In addition, in the method for manufacturing a hybrid coating layer according to the present disclosure, the method for manufacturing a hybrid coating layer further comprises, after the first heat treatment step, a stack assembly step in which a plurality of cells that convert fuel into electricity through an electrochemical reaction are assembled and stacked on the first heat-treated metal substrate, and after the stack assembly step, heat treatment is performed in the second heat treatment step.

[0021] According to the present disclosure, by mixing transition metals manganese (Mn) and cobalt (Co) and forming a first coating layer having a thickness of 0.2 μm to 2 μm by a sputtering process, it is possible to produce a coating layer that is very stable at high temperatures and has stable electrical conductivity and oxidation resistance.

[0022] Also. According to the present disclosure, Mn in the first coating layer 1.5 Co 1.5 By forming a second coating layer using an oxide having an O4 spinel structure oxide through a wet chemical coating process, the separator can be coated with a uniform thickness on a substrate having various shapes such as a flat plate shape, a flow channel pattern shape, a porous shape, a mesh shape, or a waffle shape, thereby having the effect of forming a coating layer that is evenly distributed over the entire surface regardless of the shape of the substrate.

[0023] In addition, according to the present disclosure, by forming a first coating layer by a sputtering process and a second coating layer by an electrophoretic method, and then proceeding with an air atmosphere heat treatment process excluding a reducing atmosphere heat treatment process, it is possible to produce an oxide layer having a low degradation rate and a simple manufacturing process.

[0024] FIG. 1 is a method for manufacturing a hybrid coating layer according to a first embodiment of the present disclosure.

[0025] FIG. 2 is a method for manufacturing a hybrid coating layer according to a second embodiment of the present disclosure.

[0026] FIG. 3 is a first coating layer coated on a metal substrate of the present disclosure.

[0027] FIG. 4 shows a second coating layer coated on a first coating layer formed on a metal substrate of the present disclosure.

[0028] FIG. 5 is an oxide layer produced by the heat treatment process of the first coating layer and the second coating layer of the present disclosure.

[0029] FIG. 6 is a method for manufacturing a hybrid coating layer according to a third embodiment of the present disclosure.

[0030] The present disclosure will be described in detail below with reference to the attached drawings. However, this is merely illustrative and the present disclosure is not limited to the specific embodiments described illustratively.

[0031] Unless otherwise defined, all technical and scientific terms have the same meaning as generally understood by one of the art to which the present invention pertains. Terms used for illustrative purposes in the present invention are merely for effectively describing specific embodiments and are not intended to limit the present invention.

[0032] Furthermore, the singular form used in the specification and the appended claims may be intended to include the plural form unless specifically indicated otherwise in the context. Additionally, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0033] In the present disclosure, Mn is used as a protective coating material for metal separator plates. 1.5 Co 1.5The aim is to fabricate a coating layer with a dense structure and no degradation on separator plates having various shapes, such as flat, flow channel pattern, porous, mesh, and waffle shapes, using O4 spinel material. At this time, the most common conventional method for forming a protective coating on separator plates involves coating a metal separator plate using wet chemical coating processes such as screen printing, spray coating, or dip coating, followed by heat treatment in a reducing atmosphere to create a dense structure, and then finishing by heat treatment in an air atmosphere; however, this method is insufficient for Mn on separator plates having various shapes 1.5 Co 1.5 It is difficult to produce a coating layer with a dense structure without degradation using O4 material. Therefore, in the present disclosure, a first coating layer is produced by first performing a sputtering process on a metal substrate, a second coating layer is produced by electrophoresis, and finally, an oxide layer is produced through a heat treatment process. When a first coating layer is formed by a sputtering process on a separator plate of various shapes, such as a flat plate, a flow channel pattern, a porous shape, a mesh shape, or a waffle shape, and a second coating layer is formed using electrophoresis, and then an oxide layer is produced, a uniform and dense coating is provided on the structure of the complex separator plate, and the effect of maintaining durability and electrical performance can be obtained. Accordingly, it is possible to prevent oxidation or chromium volatilization when the solid oxide fuel cell (SOFC) operates in a high-temperature environment, and the cell life can be extended.

[0034] FIG. 1 relates to a method for manufacturing a hybrid coating layer according to a first embodiment of the present disclosure. Referring to FIG. 1, the method for manufacturing a hybrid coating layer according to a first embodiment of the present disclosure includes a first coating layer forming step (S100), a second coating layer forming step (S110), and a heat treatment step. Additionally, the heat treatment step further includes a first heat treatment step (S120) and a second heat treatment step (S130).

[0035] The first coating layer formation step (S100) is a step of forming a first coating layer by coating a first material onto a metal substrate with a predetermined thickness. The metal substrate (100) may be selected as a stainless steel substrate. A stainless steel substrate has excellent corrosion resistance, so it does not corrode easily even in an oxidizing environment, allowing for long-term use, and has excellent mechanical strength, so no structural deformation occurs at high temperatures. In addition, it has a low coefficient of thermal expansion, so cracks or deformation due to thermal expansion do not easily occur, and it has the advantage of being easy to process and inexpensive, allowing for mass production. Furthermore, the metal substrate (100) is not limited to a stainless steel substrate, and various substrates such as stainless steel 300 series, stainless steel 400 series, Crofer 22 APU, Crofer 22 H, Inconel, ZMG232, 460FC, etc., may be selected. In addition, the first material is a transition metal, and the transition metal is selected from one or more of iron (Fe), nickel (Ni), chromium (Cr), vanadium (V), titanium (Ti), copper (Cu), manganese (Mn), and cobalt (Co).

[0036] FIG. 2 illustrates a schematic diagram of a first coating layer coated on a metal substrate according to the present disclosure. Referring to FIG. 2, the first coating layer formation step (S100) forms the first coating layer using any one of evaporation deposition, sputtering, chemical vapor deposition (CVD), physical vapor deposition (PVD), and atomic layer deposition (ALD). In the present disclosure, the first coating layer (200) is formed using a sputtering process. The sputtering process is one of the physical deposition techniques for forming a thin film, in which ions in a plasma collide with the surface of a target material to be deposited, transferring energy, and due to this energy transfer, atoms or molecules of the target material escape and are emitted in a gaseous state. The emitted atoms condense on the substrate to form a thin film. In the present disclosure, argon (Ar) was injected as an atmosphere gas during the sputtering process, with a gas flow rate of 30 cc / m and an applied power of 100 W. Additionally, in the present disclosure, a transition metal target was used as the target material. At this time, the transition metal is selected from one or more of iron (Fe), nickel (Ni), chromium (Cr), vanadium (V), titanium (Ti), copper (Cu), manganese (Mn), and cobalt (Co). Specifically, the transition metal of the present disclosure may be selected as manganese (Mn) and cobalt (Co). Manganese (Mn) and cobalt (Co) may be prepared as targets, either individually or in a mixed form. The manganese (Mn) and cobalt (Co) coating layer formed by the sputtering process is stable even at high temperatures, possesses excellent mechanical strength and chemical resistance, and maintains stability without decomposition even at high temperatures, thereby having a low degradation rate.

[0037] In this case, forming only a manganese (Mn) coating layer on a stainless steel substrate via a sputtering process can lead to various problems. Manganese can exist in various oxidation states (MnO, Mn₂O₃, Mn₃O₄) at high temperatures, and changes in these oxidation states can compromise the stability of the coating layer. In particular, these oxides become phase-unstable at high temperatures, which can easily cause the coating layer to break down. Furthermore, manganese oxides such as MnO and Mn₂O₃ have low electrical conductivity; however, since high electrical conductivity is essential for the separator coating layer in solid oxide fuel cells, the application of a manganese coating layer is consequently impossible.

[0038] In addition, if only a cobalt (Co) coating layer is formed on a stainless steel substrate using a sputtering process, the following problems may occur. Cobalt oxidizes easily at high temperatures to form oxides such as CoO and Co₃O₄. In particular, cobalt oxidized at high temperatures can volatilize, and the volatilized cobalt can recrystallize into other components within the solid oxide fuel cell, which can degrade electrochemical performance. Furthermore, cobalt oxides such as Co₃O₄ have low electrical conductivity, so if used alone as a coating layer for a separator in a solid oxide fuel cell, a problem of reduced electrical performance may occur. Therefore, by mixing manganese (Mn) and cobalt (Co) to form a first coating layer (200), manganese can provide oxidation stability and cobalt can improve electrical conductivity, thereby providing a coating layer that is very stable at high temperatures and has stable electrical conductivity and oxidation resistance.

[0039] Additionally, the thickness of the first coating layer (200) is formed to be 0.2㎛ to 2㎛. In detail, the thickness of the first coating layer (200) can be formed to be 0.5㎛ to 1.5㎛, and more specifically, to be formed to be 0.8㎛ to 1.2㎛. In the present disclosure, the thickness of the first coating layer (200), which is coated by mixing manganese (Mn) and cobalt (Co) using a sputtering process, is formed to be 1㎛. If the thickness of the first coating layer (200) is 0.2㎛ or less, the thickness of the first coating layer (200) is insufficient, making it easy for oxygen to penetrate from the outside, and it may not sufficiently function as a protective layer to prevent chromium volatilization, which may affect a high degradation rate.

[0040] In addition, if the thickness of the first coating layer (200) is 2㎛ or more, the time required to form the coating layer is long, and there is a problem that the quality of the coating layer is degraded.

[0041] FIG. 3 is a schematic diagram of a second coating layer coated on a first coating layer formed on a metal substrate of the present disclosure. Referring to FIG. 3, the second coating layer formation step (S110) is a step of coating a second coating layer by applying an electric field to the first coating layer and coating a second material having a spinel structure. The second material is Mn x Cu 3-x O4, Mn x Co 3-x O4, Mg x Cr 3-x O4, Ni x Fe 3-x O4, Zn x Al 3-x O 4, , Li x Mn 3-x It is selected as any one of O4. Specifically, the second material in the present disclosure has a spinel structure, and Mn 1.5 Co 1.5 Selected as O4. Mn 1.5 Co 1.5 O4 is It is a spinel-structured oxide containing manganese and cobalt, having the form AB₂O₄, where Mn and Co exist in a mixture at the A site. Mn 1.5 Co 1.5 O4 spinel structure oxides are conductive and can exhibit semiconductor properties at specific temperatures, making them suitable for use in energy storage devices such as lithium-ion batteries. Furthermore, they possess high thermal and chemical stability, maintaining stable characteristics even in high-temperature environments.

[0042] Additionally, the second coating layer formation step (S110) can be performed by applying an electric field to produce the coating layer. Specifically, the second coating layer can be formed by electrophoresis. Since charged particles move along the electric field and are uniformly coated on the metal surface, electrophoresis enables the formation of a coating layer on separator plates of various shapes.

[0043] At this time, the second coating layer formation step (S110) further includes a mixed solution formation step in which, before applying an electric field, a second material in powder form is dispersed in a solvent to form a mixed solution containing the second material. The mixed solution formation step is Mn having a spinel structure 1.5 Co 1.5 O4 The particles are ground into fine particles and uniformly dispersed in a solvent. At this time, the solvent is selected from one or more of the group consisting of water, methanol, ethanol, butanol, propanol, toluene, acetone, and acetylacetone. In the present disclosure, a mixed solution was formed using a solvent mixed with ethanol and acetone. Both ethanol and acetone are non-polar solvents and are effective for stably dispersing ceramic particles within the solution. Due to this effect, particles can move uniformly during coating and be deposited evenly on the substrate, and a uniform coating can be obtained by minimizing aggregation between particles. Furthermore, since acetone has very high volatility and a fast evaporation rate, while ethanol has a relatively slow evaporation rate, using the two solvents together allows the acetone to evaporate rapidly, thereby accelerating initial drying, while the ethanol evaporates gradually over the remaining time, allowing the ceramic particles to settle evenly. This has an effect that is advantageous for forming a uniform and dense coating layer and prevents the formation of bubbles or microcracks.

[0044] In addition, a stainless steel substrate on which a first coating layer is formed after the mixed solution formation step is used as the negative electrode, and the positive electrode is placed in a solvent to apply an electric field. At this time, an electric field is formed by applying a voltage of 10V to 80V between the two electrodes for 1 second to 300 seconds. Specifically, the voltage applied between the two electrodes may be 10V to 80V, specifically 20V to 60V, and more specifically 20V to 40V. Additionally, the time for which the voltage is applied between the two electrodes may be 1 second to 300 seconds, specifically 80 seconds to 180 seconds, and more specifically 100 seconds to 120 seconds. In the present disclosure, a voltage of 20V to 40V was applied between the two electrodes for 120 seconds, and the distance between the electrodes was 1cm. Due to the force of the electric field generated under the above conditions, charged Mn 1.5 Co1.5 O4 fine particles migrate to the surface of the first coating layer on a stainless steel substrate and are deposited on the surface to finally form a second coating layer. At this time, if a voltage of 10V or less is applied, the electric field weakens, causing the particle migration speed to slow down. Consequently, the coating speed becomes very slow, making it difficult to form a uniform coating layer. Furthermore, at voltages below 10V, particles cannot move sufficiently fast, which may lead to particle clustering. This makes it difficult to form a uniform film and results in the formation of a coating layer with many defects. Additionally, there is a problem where particles do not adhere sufficiently to the substrate or the coating becomes very thin, making it impossible to form a coating layer with desired characteristics. Moreover, if a voltage higher than 80V is applied, the particle migration speed becomes excessively fast, causing a thick, uneven coating, which may lead to cracking.

[0045] FIG. 4 is a schematic diagram of an oxide layer produced by a heat treatment process of the first coating layer and the second coating layer of the present disclosure, which can be formed by a heat treatment step. The heat treatment step is a step of heat-treating a metal substrate on which the first coating layer and the second coating layer are formed. At this time, the heat treatment step includes a first heat treatment step (S120) and a second heat treatment step (S130).

[0046] The first heat treatment step (S120) is heat-treated at 700°C to 1200°C in a reducing atmosphere, and the second heat treatment step (S130) is heat-treated at 600°C to 1000°C in an air atmosphere.

[0047] The first heat treatment step (S120) is performed in a reducing atmosphere at 700°C to 1200°C. Specifically, the temperature of the heat treatment in the reducing atmosphere of the first heat treatment step (S120) may be 800°C to 1200°C, and more specifically, 900°C to 1000°C. Through heat treatment in a reducing atmosphere, metal components (Mn, Co) are temporarily converted into metal or oxide states having a low oxidation state. During this process, the internal structure of the coating layer is realigned, reducing porosity and forming a denser microstructure. If the heat treatment temperature of the first heat treatment step (S120) is 700°C or lower, the reduction reaction may not occur sufficiently, and the metal ions may not be completely converted to the desired oxidation state. Consequently, the oxide may not be sufficiently reduced, or reduction may occur only on the surface while the interior remains in an oxidized state. Therefore, since the reaction rate is reduced, it may be impossible to produce a coating film with a dense structure. In addition, if the heat treatment temperature of the first heat treatment step (S120) is 1200°C or higher, there is a problem of particles aggregating due to the high heat treatment temperature. Consequently, the crystal structure of the metal or oxide may be deformed, or excessive grain growth may occur, which may lower mechanical properties such as the strength of the material, and the metal or oxide may volatilize, resulting in material loss of the coating film. In the present disclosure, the first heat treatment step (S120) was performed at 950°C, and the gas injected during reduction was hydrogen (H2) and argon (Ar), injected in a ratio of 4% H2 to 96% Ar or 50% H2 to 50% Ar.

[0048] Additionally, the heat treatment step further includes a second heat treatment step (S130). The second heat treatment step (S130) is performed in an air atmosphere at 600°C to 1000°C. Specifically, the heat treatment temperature of the second heat treatment step may be 800°C to 1200°C, and more specifically, 800°C to 1000°C. Through air atmosphere heat treatment, Mn again 1.5 Co1.5 As it is reconfigured into O4 spinel oxide, a coating film with a more stable and uniform structure can be formed, and accordingly, the overall density and mechanical strength of the coating layer can be increased, making it possible to manufacture a denser coating layer. The second heat treatment step (S130) in the present disclosure was carried out at 800°C.

[0049] That is, when heat treatment is performed in a reducing atmosphere, the reaction between the first coating layer (200) and the second coating layer (300) is promoted, thereby strengthening the bonding strength of the coating layer. The reduced metal components strengthen the chemical bond with the first coating layer (200) and can be fixed during subsequent heat treatment in an air atmosphere. Therefore, through these processes of heat treatment in a reducing atmosphere and heat treatment in an air atmosphere, the second coating layer (300) is more firmly bonded to the first coating layer (200), and a solid and dense oxide layer (400) can be formed.

[0050] Meanwhile, FIG. 5 relates to a method for manufacturing a hybrid coating layer according to a second embodiment of the present disclosure. Referring to FIG. 5, the method for manufacturing a hybrid coating layer (S2000) according to the second embodiment of the present disclosure includes a first coating layer formation step (S200), a second coating layer formation step (S210), and a second heat treatment step (S220). In the method for manufacturing a hybrid coating layer according to the second embodiment of the present disclosure, a first coating layer (200) is formed on a stainless steel substrate by a sputtering process, and a second coating layer is formed thereon. Subsequently, only an air atmosphere heat treatment process may be performed, excluding the reduction atmosphere heat treatment process. By forming the first coating layer (200) by a sputtering process, a low degradation rate can be achieved during a high-temperature degradation test. The reduction atmosphere heat treatment is performed under a hydrogen atmosphere during the heat treatment process, but there was a problem that the process preparation time was long because sealing and supplying hydrogen gas is very difficult. Therefore, if the reduction atmosphere heat treatment process is excluded, the manufacturing process of the oxide layer (400) can be made much simpler.

[0051] If heat treatment is performed in an air atmosphere following heat treatment in a reducing atmosphere, defects during the formation of the spinel structure can be reduced, and electrical conductivity can be improved. Spinel oxide is inherently a material with high electrical conductivity, and this heat treatment process eliminates unnecessary defects and optimizes ion migration pathways, making it possible to improve the electrical characteristics required for solid oxide fuel cells (SOFCs). Furthermore, Mn in solid oxide fuel cells (SOFCs) 1.5 Co 1.5 The O4 oxide layer (400) can prevent chromium volatilization from the separator. When subjected to heat treatment in a reducing atmosphere and heat treatment in an air atmosphere, the oxide layer (400) becomes denser and more uniform, thereby more effectively blocking the diffusion and volatilization of chromium. These characteristics can contribute to the long-term stability of the solid oxide fuel cell (SOFC).

[0052] FIG. 6 relates to a method for manufacturing a hybrid coating layer according to a third embodiment of the present disclosure. Referring to FIG. 6, the method for manufacturing a hybrid coating layer (S3000) according to the third embodiment of the present disclosure further includes a stack assembly step (S330) in which a plurality of cells that convert fuel into electricity through an electrochemical reaction are assembled and stacked on a metal substrate that has undergone the first heat treatment step (S320), and a second heat treatment step (S340) is performed after the stack assembly step (S330). Here, the cells serve to convert the chemical energy of fuel into electricity by bonding an electrolyte, a fuel electrode, and an air electrode to each other, and the stack assembly step (S330) is a step of forming a solid oxide fuel cell by stacking these multiple cells. One side of the metal separator plate is the part that comes into contact with hydrogen, and the other side is the part that comes into contact with air. Therefore, the protective coating must be formed only on the other side that comes into contact with air. Therefore, if a second heat treatment step (S340) is performed in an air atmosphere on a metal separator plate coated only on the air electrode side, the opposite surface may be significantly damaged. Therefore, if a first heat treatment step (S320) is performed in a reducing atmosphere where the metal separator plate is not significantly damaged, and then the cell is assembled and the second heat treatment (S340) is performed in an air atmosphere on the fuel electrode side during the startup stage, the performance of the separator plate is improved.

[0053] The above description is merely an example of applying the principles of the present disclosure, and other configurations may be included without departing from the scope of the present invention.

[0054]

[0055] [Explanation of the symbol]

[0056] 1000: Metal separator comprising a hybrid coating layer of the present disclosure

[0057] 100 : Metal substrate

[0058] 200 : First coating layer

[0059] 300 : Second coating layer

[0060] 400: Oxide layer

Claims

1. A first coating layer formation step of forming a first coating layer by coating a first material onto a metal substrate with a predetermined thickness; A second coating layer formation step of applying an electric field to the first coating layer to coat a second material having a spinel structure, thereby forming a second coating layer; A heat treatment step of heat-treating a metal substrate having the first coating layer and the second coating layer formed thereon; A method for manufacturing a hybrid coating layer including 2. In claim 1, the step of forming the first coating layer is, A method for manufacturing a hybrid coating layer, wherein a first coating layer is formed using any one of evaporation deposition, sputtering, chemical vapor deposition (CVD), physical vapor deposition (PVD), and atomic layer deposition (ALD).

3. In paragraph 1, the first material is, It is a transition metal, and The above transition metal is, A method for manufacturing a hybrid coating layer selected from one or more of iron (Fe), nickel (Ni), chromium (Cr), vanadium (V), titanium (Ti), copper (Cu), manganese (Mn), and cobalt (Co).

4. In paragraph 1, the above-mentioned preset thickness is, Method for manufacturing a hybrid coating layer having a thickness of 0.2㎛ to 2㎛.

5. In claim 1, the step of forming the second coating layer is, A method for manufacturing a hybrid coating layer, further comprising a mixing solution formation step of forming a mixing solution containing a second material by dispersing a second material in powder form in a solvent before applying the electric field.

6. In paragraph 5, the solvent is, A method for manufacturing a hybrid coating layer selected from the group consisting of water, methanol, ethanol, propanol, butanol, toluene, acetone, and acetylacetone.

7. In paragraph 1, the electric field A method for manufacturing a hybrid coating layer, performed for 1 second to 300 seconds under a voltage of 10V to 80V.

8. In paragraph 1, the second material is, Mn x Cu 3-x O4, Mn x Co 3-x O4, Mg x Cr 3-x O4, Ni x Fe 3-x O4, Zn x Al 3-x O 4, , Li x Mn 3-x A method for manufacturing a hybrid coating layer selected from any one of O4.

9. In paragraph 1, the heat treatment step is, It includes a first heat treatment step, A method for manufacturing a hybrid coating layer, wherein the first heat treatment step is heat-treated at 700°C to 1200°C in a reducing atmosphere.

10. In paragraph 1, the heat treatment step is, It further includes a second heat treatment step, A method for manufacturing a hybrid coating layer, wherein the second heat treatment step is heat-treated at 600°C to 1000°C in an air atmosphere.

11. In any one of claims 1 to 10, the method for manufacturing the hybrid coating layer is, After the first heat treatment step above, The method further includes a stack assembly step of assembling and stacking a plurality of cells that convert fuel into electricity through an electrochemical reaction on the first heat-treated metal substrate. A method for manufacturing a hybrid coating layer, wherein the heat treatment is performed in the second heat treatment step after the stack assembly step.

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