A planar SOFC anode support and a method of forming a green body thereof

Abstract

The application discloses a kind of flat plate SOFC anode support and its forming method, system, including the following steps: ceramic mud is extruded by ceramic extrusion tube machine, in extrusion process, blank is cut along the axial direction, and sheet blank is obtained;The sheet blank is crossed and added two by two, and the blank to be rolled is obtained, wherein the intersection angle of the sheet blank is 90°;The blank to be rolled is placed between the roll of film rolling machine and is rolled into film, and the rolling film strip is obtained;The rolling film strip is stamped into shape, and the anode support blank is obtained.The anode support prepared by the application has low shrinkage rate and is not easy to crack, thereby the safety of solid oxide fuel cell is high, and the service life is long.

Description

Technical Field

[0001] This invention belongs to the field of solid oxide fuel cell technology, specifically relating to a method and system for forming a planar SOFC anode support and its blank. Background Technology

[0002] Climate change has become a global environmental problem that has been widely studied and concerned by human society. Reducing emissions of greenhouse gases such as CO2 is an effective way to solve global warming, and reducing emissions of greenhouse gases such as CO2 requires the vigorous development of clean energy sources such as hydrogen energy. Solid oxide fuel cells (SOFCs) are highly efficient energy conversion devices that convert chemical energy into electrical energy. They have advantages such as high energy conversion efficiency (breaking through the limitations of the Carnot cycle, with a thermal efficiency of up to 85%), no environmental pollution, and low noise. SOFC technology has become an important technological support for building a "hydrogen society" and has already been put into practical use in industrial power plants, automotive power supplies, and portable power equipment.

[0003] SOFCs mainly come in two structural types: flat-plate and tubular. Flat-plate SOFCs have received widespread research attention due to their higher power density, ease of stacking, and ability to meet high-power output requirements when used in series. Currently, flat-plate SOFCs primarily employ anode support fabrication using a casting process, which offers advantages such as simple equipment and high production efficiency. However, the high binder content in the casting slurry leads to a shrinkage rate of 20%-21% during drying and firing. This excessive shrinkage rate causes the cast blank to crack easily during drying and firing, resulting in product failure. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method and system for forming a planar SOFC anode support and its preform, employing an extrusion molding process to prepare the anode support, thereby obtaining a safe and reliable planar solid oxide fuel cell.

[0005] First, the present invention provides a method for forming a flat SOFC anode support blank, comprising the following steps: extruding ceramic clay through a ceramic extruder, cutting the blank along the axial direction during the extrusion process to obtain a sheet blank; stacking the sheet blanks in pairs to obtain a blank to be rolled, wherein the cross angle of the sheet blanks is 90°; placing the blank to be rolled between the rolls of a rolling mill for rolling to obtain a rolled film strip; and stamping the rolled film strip to obtain the anode support blank.

[0006] Preferably, the blank to be rolled is subjected to at least two rolling processes. After each rolling process, the rolled film strip is rotated 90° before the next rolling process.

[0007] Preferably, the ceramic clay is prepared by the following steps: mixing NiO-YSZ powder, additives, and water; ball milling and granulating the resulting slurry to obtain granulated particles; and placing the granulated particles into a clay kneading machine for kneading to obtain the ceramic clay.

[0008] Preferably, the particle size of the NiO-YSZ powder is 0.2-1.0 μm.

[0009] Preferably, the moisture content of the granulated particles is 10wt% to 30wt%.

[0010] Secondly, the present invention also provides a forming system for a flat SOFC anode support blank, comprising: an extrusion unit for extruding ceramic clay through a ceramic tube extruder, wherein the blank is cut axially during the extrusion process to obtain a sheet-like blank; a stacking unit for receiving the sheet-like blanks and stacking them in pairs to obtain a blank to be rolled, wherein the cross angle of the sheet-like blanks is 90°; a rolling unit for receiving the blank to be rolled and placing it between the rolls of a rolling mill for rolling to obtain a rolled film strip; and a stamping unit for receiving the rolled film strip and stamping the rolled film strip to obtain an anode support blank.

[0011] Preferably, the ceramic tube extrusion machine includes a ceramic tube extrusion die, the ceramic tube extrusion die includes a die core and a die sleeve, and a cutting element is provided between the die core and the die sleeve.

[0012] Preferably, the cutting element is diamond wire.

[0013] Preferably, the cutting element is located at the outlet of the ceramic tube extrusion die.

[0014] Preferably, the rolling unit includes a film strip transfer module, which can transfer the rolled film strip from the discharge port to the feed port of the rolling mill.

[0015] Furthermore, the present invention also provides a flat SOFC anode support, which is obtained by debinding and sintering the anode support blank prepared above.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] Firstly, because the tape casting process itself requires high fluidity of the slurry, the slurry used for tape casting contains a high content of other reagents besides ceramic powder (such as binders, dispersants, and water), resulting in high shrinkage during drying and firing of the green body, making it prone to cracking. Therefore, this invention uses extrusion molding to prepare the anode support. The content of other reagents in the slurry used in extrusion molding is much lower than that in tape casting slurry. As a result, the green body obtained by this invention has a low shrinkage rate during drying and firing, is less prone to cracking, and consequently, the resulting solid oxide fuel cell has a high yield, high safety, and long service life.

[0018] Secondly, due to the uneven stress on the clay during the extrusion process, the clay at the edge of the die is affected by compressive stress and friction, resulting in a slower extrusion speed, while the clay in the middle is affected by axial pressure, resulting in a faster extrusion speed. This inconsistent extrusion speed leads to uneven density in the green body. However, in the process of preparing thin-walled ceramic tubes, the stress on each part of the tube blank is uniform, eliminating the problem of uneven stress during ceramic extrusion. Therefore, when preparing the anode support using the extrusion method in this invention, instead of directly extruding a flat green body, the ceramic tube extrusion die is improved. Specifically, a cutting component is set on the ceramic tube extrusion die, which can cut the round tube blank into sheet-like green bodies during the extrusion process.

[0019] Furthermore, due to the triaxial stress on the clay, the powder particles are oriented along the extrusion direction. During the drying and sintering process, the shrinkage perpendicular to the extrusion direction is greater than the shrinkage along the extrusion direction, making the green body prone to cracking during drying and sintering. Therefore, this invention involves overlapping two extruded sheet-like green bodies in pairs, followed by rolling and stamping, to finally obtain a uniformly dense anode support green body.

[0020] Therefore, this invention can avoid internal stress in the anode support, and the anode support has uniform density and is not prone to cracking, thus avoiding safety hazards such as gas leakage caused by cracking of the anode support during fuel cell operation. Simultaneously, this invention also designs a molding system to automate the molding of the anode support blank, reducing manual operation and labor intensity. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the preparation of a flat SOFC anode support blank according to Embodiment 1 of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of a ceramic tube extrusion die in Embodiment 1 of the present invention;

[0023] Figure 3 This is a schematic diagram of the arrangement of powder in a sheet-like preform according to Embodiment 1 of the present invention;

[0024] Figure 4 This is a schematic diagram of the arrangement of powder in a billet to be rolled according to Embodiment 1 of the present invention;

[0025] Figure 5 This is a schematic diagram of the structure of a film rolling mill in Embodiment 1 of the present invention.

[0026] 1-Ceramic tube extrusion die, 10-Die core, 11-Die sleeve, 12-Cut part, A-Extrusion direction, 21-Sheet blank, 22-Blank blank to be rolled, 3-Rolling mill, 31-Rolling roll, 32-Vacuum suction cup robot. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] This embodiment provides a method for forming a flat SOFC anode support blank, including the following steps:

[0030] S1. Prepare ceramic clay.

[0031] Specifically, NiO-YSZ powder, additives, and water are mixed, and the resulting slurry is ball-milled and granulated to obtain granulated particles with a water content of 10wt%-30wt%. These granulated particles are then placed in a clay kneader for kneading to obtain ceramic clay. The NiO-YSZ powder content in the ceramic clay is 50wt%-70wt%.

[0032] The particle size of the NiO-YSZ powder is 0.2-1.0 μm, preferably 3-8 YSZ.

[0033] The additives include binders selected from one or more of polyvinyl alcohol, butyl silicate, vinyl acetate resin, and hydroxypropyl methylcellulose.

[0034] The additives include dispersants, which are selected from one or two of ammonium polyacrylate and polyacrylic acid.

[0035] The additives include pore-forming agents, which are selected from one or more of carbon powder, soluble starch, and graphite powder.

[0036] In this embodiment, as a preferred embodiment, the additives also include plasticizers, such as one or two of tung oil and soybean oil.

[0037] In this embodiment, as a preferred embodiment, the auxiliary agent also includes a water-retaining agent, such as one or two of glycerin and ammonium chloride.

[0038] S2. The ceramic clay is extruded through a ceramic extruder. During the extrusion process, the green body is cut along the axial direction to obtain a sheet-like green body.

[0039] Specifically, the ceramic tube extrusion machine includes a ceramic tube extrusion die, which comprises a die core and a die sleeve, with a cutting element disposed between the die core and the die sleeve. The cutting element is a diamond wire and is located at the outlet of the ceramic tube extrusion die. The cutting element can axially cut the tubular preform, so that the tubular preform is cut into sheet-like preforms during extrusion.

[0040] Depending on actual needs, when the extruded billet reaches a certain length, it is cut using a pneumatic cutter to obtain a sheet-like billet of the required length. The obtained sheet-like billet is then placed on a billet receiving machine for the next process. In this embodiment, as a preferred solution, the sheet-like billet is a square billet, meaning that the length and width of the sheet-like billet are equal.

[0041] S3. The sheet-like blanks are stacked in pairs at a 90° intersection angle to obtain the blank to be rolled.

[0042] Specifically, a vacuum chuck robot is used to pick up the sheet-like billet from the receiving machine. Under the action of a cylinder, the vacuum chuck robot rises away from the receiving machine, maintaining a certain distance. Under the action of a rotary motor, the vacuum chuck robot rotates 90°, and the picked-up sheet-like billet rotates 90° accordingly. After the next sheet-like billet is cut and arrives at the receiving machine, the vacuum chuck robot is controlled to descend, placing the picked-up and rotated sheet-like billet on the upper surface of the sheet-like billet on the receiving machine. This allows the sheet-like billets to be stacked in pairs to obtain the billet to be rolled.

[0043] S4. The blank to be rolled is placed between the rolls of the rolling mill for rolling to obtain a rolled film strip.

[0044] In this embodiment, as a preferred solution, the blank to be rolled is subjected to at least two rolling processes. After each rolling process, the rolled film strip is rotated 90° before the next rolling process.

[0045] Specifically, a vacuum suction cup robot is installed. The vacuum suction cup robot can move back and forth between the discharge port and the feed port of the rolling mill to transfer the rolled film strip at the discharge port to the feed port for the next rolling.

[0046] It should be noted that the vacuum suction cup robot can rotate, which can also drive the film strip being sucked up to rotate; the gap between the rollers can be different each time the film is rolled. Preferably, the gap between the rollers is gradually reduced to obtain a film strip with the required thickness.

[0047] S5. The rolled film strip is stamped into shape to obtain the anode support blank. The shape and size of the green blank are determined according to the required shape and size of the anode support.

[0048] This embodiment also provides a forming system for a flat SOFC anode support preform, including:

[0049] An extrusion unit is used to extrude ceramic clay through a ceramic tube extruder. During the extrusion process, the green body is cut axially to obtain a sheet-like green body. The ceramic tube extruder includes a ceramic tube extrusion die, which includes a die core and a die sleeve. A cutting element is provided between the die core and the die sleeve. The cutting element is a diamond wire and is located at the outlet of the ceramic tube extrusion die.

[0050] The stacking unit is used to receive the sheet-like billets and stack the sheet-like billets in pairs to obtain the billet to be rolled, wherein the cross angle of the sheet-like billets is 90°.

[0051] The rolling unit receives the blank to be rolled and places it between the rolls of the rolling mill for rolling to obtain a rolled film strip. In this preferred embodiment, the rolling unit includes a film strip transfer module that can transfer the rolled film strip from the outlet to the inlet of the rolling mill.

[0052] A stamping unit is used to receive the rolled film strip and stamp the rolled film strip to obtain an anode support blank.

[0053] This embodiment also provides a flat SOFC anode support, which is obtained by debinding and sintering the anode support blank prepared above, with a sintering temperature of 1000-1200℃, preferably 1100℃.

[0054] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method of forming a planar SOFC anode support green body, characterized by, Includes the following steps: Ceramic clay is extruded through a ceramic tube extruder. During the extrusion process, the green body is cut along the axial direction to obtain a sheet-like green body. The sheet-like billets are stacked in pairs to obtain a billet to be rolled, wherein the cross angle of the sheet-like billets is 90°; The blank to be rolled is placed between the rolls of a rolling mill for rolling to obtain a rolled film strip; The rolled film strip is stamped to obtain the anode support blank. The ceramic clay is prepared through the following steps: NiO-YSZ powder, additives, and water are mixed, and the resulting slurry is ball-milled and granulated to obtain granulated particles. The granulated particles are placed into a clay kneading machine for kneading to obtain ceramic clay.

2. The method for forming a flat SOFC anode support blank according to claim 1, characterized in that, The blank to be rolled is subjected to at least two rolling processes. After each rolling process, the rolled film strip is rotated 90° before the next rolling process.

3. The method for forming a flat SOFC anode support blank according to claim 1, characterized in that, The particle size of the NiO-YSZ powder is 0.2-1.0 μm.

4. The forming method of a planar SOFC anode support green body according to claim 1, characterized by, The moisture content of the granulated particles is 10wt%~30wt%.

5. A forming system for green anode support bodies for planar SOFCs, produced according to the forming method according to any one of claims 1 to 4, characterized in that include: The extrusion unit is used to extrude ceramic clay through a ceramic tube extruder. During the extrusion process, the green body is cut along the axial direction to obtain a sheet-like green body. A stacking unit is used to receive the sheet-like billets and stack the sheet-like billets in pairs to obtain a billet to be rolled, wherein the crossing angle of the sheet-like billets is 90°; The rolling unit is used to receive the blank to be rolled and place the blank between the rolls of the rolling mill for rolling to obtain rolled film strip; A stamping unit is used to receive the rolled film strip and stamp the rolled film strip to obtain an anode support blank.

6. The forming system of green anode support bodies for planar SOFCs according to claim 5, characterized in that The ceramic tube extrusion machine includes a ceramic tube extrusion die, which includes a die core and a die sleeve, with a cutting element provided between the die core and the die sleeve.

7. The forming system of green anode support bodies for planar SOFCs according to claim 6, characterized in that The cutting element is a diamond wire, and / or the cutting element is located at the outlet of the ceramic tube extrusion die.

8. The forming system of claim 5, wherein the forming system is characterized by: The rolling unit includes a film strip transfer module, which can transfer the rolled film strip from the discharge port to the feed port of the rolling mill.

9. A planar SOFC anode support body, characterized by It is obtained by debinding and sintering the anode support blank prepared according to any one of claims 1 to 4.

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