A tensioning device suitable for high-temperature carbonization and graphitization and a method of using the same

Abstract

The present invention relates to the field of high-temperature treatment of carbon paper, and in particular to a tensioning device suitable for high-temperature carbonization and graphitization and a method for using the same; the tensioning device comprises: an inner tensioning tube, an inner tube cover, an inner tube pressure control assembly, an outer tensioning tube, an outer tube cover, and an outer tube pressure control assembly; a plurality of inner tensioning assemblies are arranged on the side wall of the inner tensioning tube; the outer tensioning tube comprises a first side wall and a second side wall; a plurality of outer tensioning assemblies are arranged on the first side wall of the outer tensioning tube; the tensioning device of the present invention can adjust the tensioning force of the carbon paper through the inner tensioning assembly and the outer tensioning assembly during the high-temperature carbonization and graphitization process, and can control different tensions on the surface of the carbon paper according to different temperature ranges, thereby preventing deformation of the carbon paper due to thermal shrinkage during the high-temperature carbonization and graphitization process, effectively improving the surface flatness and mechanical properties of the carbon paper, and further improving the power generation efficiency and service life of the hydrogen fuel cell.

Description

Technical Field

[0001] The invention relates to the field of high-temperature treatment of carbon paper, and in particular to a tensioning device suitable for high-temperature carbonization and graphitization and a use method thereof. Background Art

[0002] In the fields of fuel cells, water electrolysis to produce hydrogen, flow batteries, etc., carbon paper is used as a substrate for preparing gas diffusion layers. It plays the role of supporting the catalytic layer, collecting current, conducting gas, and discharging the reaction product water. It is an indispensable key basic material.

[0003] The main steps in the preparation of carbon paper are as follows: short-cut carbon fibers, papermaking and forming to prepare carbon fiber base paper, resin impregnation and molding, as well as carbonization and graphitization. In the process of preparing carbon paper, high-temperature carbonization and graphitization are indispensable processes. Among them, carbonization is usually carried out under inert conditions of 600-1200°C. At this stage, the volatile substances in the carbon paper are removed, and the most important change is that the resin is converted into amorphous carbon. Graphitization is a heat treatment of carbon-based materials under controlled conditions, and the temperature usually needs to reach above 2000°C to achieve effective graphitization.

[0004] During the high-temperature carbonization and graphitization process, two methods are usually used, namely continuous or intermittent. The first method is to cut the carbon paper to be carbonized into single sheets, stack them and apply a certain pressure on the surface, and then place them in a carbonization furnace for carbonization or graphitization. The carbonization and graphitization of a single sheet belongs to intermittent preparation, which is limited by the long heating and cooling cycle of the carbonization furnace and graphitization furnace equipment. In addition, the subsequent process cannot be continuous, so the carbon paper preparation efficiency is not high. The second method is to pass the rolled carbon paper to be carbonized through the high-temperature carbonization furnace and the high-temperature graphitization furnace in sequence, and rely on the tension applied in the front and back directions to achieve the flattening and operation of the carbon paper. That is, the rolled carbon paper cannot be directly placed in the intermittent carbonization and graphitization equipment during the high-temperature carbonization and graphitization process, and the continuous carbonization and graphitization of the coil is affected by the furnace mouth air seal and heating time. The equipment generally consumes a lot of energy, which invisibly increases the preparation cost.

[0005] During the high-temperature carbonization and graphitization process, the molecular bonds of carbon paper are broken, the hexagonal ring structure is reformed, and small molecular gases are released during the high-temperature treatment of carbon paper, and the paper surface will shrink naturally. During the carbonization and graphitization preparation of carbon paper, if effective tension cannot be provided in the width direction of the carbon paper and the carbon paper is allowed to shrink freely, the paper surface may wrinkle, deform, or even crack. No matter which carbonization and graphitization scheme is adopted, it is necessary to apply a certain tension to the material in the direction of the paper surface during the high-temperature reaction to maintain the paper surface. Summary of the invention

[0006] The object of the present invention is to provide a tensioning device suitable for high-temperature carbonization and graphitization of rolled carbon paper and a method of using the same in view of the deficiencies in the prior art.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention is to provide a tensioning device suitable for high-temperature carbonization and graphitization, comprising: an inner tensioning tube, an inner tube cover detachably connected to the top end of the inner tensioning tube, an inner tube pressure control assembly detachably connected to the inner tensioning tube, an outer tensioning tube sleeved outside the inner tensioning tube, an outer tube cover detachably connected to the top end of the outer tensioning tube, and an outer tube pressure control assembly arranged on the side wall of the outer tensioning tube;

[0009] A plurality of inner tensioning components are arranged on the side wall of the inner tensioning tube; the inner tensioning components include: an inner tensioning inner plate arranged in the inner tensioning tube, an inner tensioning outer plate arranged outside the inner tensioning tube, and an inner tensioning fixing bolt; one end of the inner tensioning fixing bolt passes through the inner tensioning inner plate, the side wall of the inner tensioning tube, and the inner tensioning outer plate in sequence to connect the inner tensioning component and the inner tensioning tube;

[0010] The outer tensioning tube includes a first side wall and a second side wall sleeved outside the first side wall, and a sandwich is formed between the first side wall and the second side wall; a plurality of outer tensioning components are arranged on the first side wall of the outer tensioning tube; the outer tensioning components include: an outer tensioning inner plate arranged inside the first side wall, an outer tensioning outer plate arranged outside the first side wall, and an outer tensioning fixing bolt; one end of the outer tensioning fixing bolt passes through the outer tensioning outer plate, the first side wall and the outer tensioning inner plate in sequence to connect the outer tensioning component and the outer tensioning tube.

[0011] Preferably, a plurality of partitions are provided in the inner tensioning cylinder, and the plurality of partitions divide the cavity in the inner tensioning cylinder into a first inner cavity, a second inner cavity, a third inner cavity, a fourth inner cavity and a fifth inner cavity which are arranged sequentially from top to bottom; and a partition opening is provided on the partition for the inner cylinder pressure control assembly to pass through.

[0012] More preferably, the inner cylinder pressure control assembly includes: a first inner cylinder pressure control pipeline, a second inner cylinder pressure control pipeline and a third inner cylinder pressure control pipeline; the first inner cylinder pressure control pipeline is connected to the third inner cavity; the second inner cylinder pressure control pipeline is connected to the second inner cavity and the fourth inner cavity; the third inner cylinder pressure control pipeline is connected to the first inner cavity and the fifth inner cavity.

[0013] More preferably, the top ends of the first inner cylinder pressure control pipeline, the second inner cylinder pressure control pipeline and the third inner cylinder pressure control pipeline all pass through the inner cylinder cover and are respectively connected to a flow meter and a pressure gauge.

[0014] Preferably, a plurality of groups of the inner tensioning components are provided on the side wall of the inner tensioning cylinder along the axial direction of the inner tensioning cylinder; the number of the inner tensioning components in each group is not less than three, and the plurality of the inner tensioning components in the same group are equidistantly arranged along the circumferential direction of the inner tensioning cylinder;

[0015] Several groups of the outer tensioning components are provided on the first side wall of the outer tensioning tube along the axial direction of the outer tensioning tube, the number of the outer tensioning components in each group is not less than three, and the several outer tensioning components in the same group are equidistantly arranged along the circumferential direction of the first side wall.

[0016] Preferably, an inner tube inner fixing groove matching the inner tension inner plate is formed on the inner wall of the inner tension tube, and an inner tube outer fixing groove matching the inner tension outer plate is formed on the outer wall of the inner tension tube.

[0017] Preferably, the outer tensioning cylinder includes along its axial direction: a first outer cylinder, a second outer cylinder, a third outer cylinder, a fourth outer cylinder and a fifth outer cylinder connected in sequence from top to bottom; the first outer cylinder, the second outer cylinder, the third outer cylinder, the fourth outer cylinder and the fifth outer cylinder all have an interlayer; the outer cylinder cover is connected to the top end of the first outer cylinder.

[0018] More preferably, the outer cylinder pressure control assembly includes: a first outer cylinder pressure control pipeline, a second outer cylinder pressure control pipeline and a third outer cylinder pressure control pipeline; the first outer cylinder pressure control pipeline is connected to the third outer cylinder, the second outer cylinder pressure control pipeline is connected to the second outer cylinder and the fourth outer cylinder, and the third outer cylinder pressure control pipeline is connected to the first outer cylinder and the fifth outer cylinder.

[0019] Preferably, an outer tube inner fixing groove matching the outer tension inner plate is formed inside the first side wall of the outer tension tube, and an outer tube outer fixing groove matching the outer tension outer plate is formed outside the first side wall.

[0020] Preferably, the tensioning device is made of high-density graphite with a density of not less than 1.85 g / cm 3 , Shore hardness is not less than 45, thermal expansion coefficient is not more than 2.0×10 -6 / K.

[0021] The second aspect of the present invention is to provide a method for using the tensioning device, the steps comprising:

[0022] S1. Roll the impregnated and cured carbon paper onto the inner tensioning cylinder to form a carbon paper coil of a certain thickness, assemble the inner cylinder cover and the inner cylinder pressure control assembly, and sleeve the outer tensioning cylinder onto the carbon paper coil, and then assemble the outer cylinder cover and the outer cylinder pressure control assembly;

[0023] S2. Place the assembled tensioning device vertically in a carbonization furnace or a graphitization furnace. The inner tube pressure control assembly and the outer tube pressure control assembly are respectively connected to an inert gas source and equipped with a flow meter and a pressure gauge. By introducing inert gas, the pressure of the inner tensioning assembly on the inner tensioning cylinder and the outer tensioning assembly on the outer tensioning cylinder on the carbon paper coil is controlled to achieve a certain controllable pressure difference.

[0024] Among them, the pressure difference between the third inner chamber and the furnace chamber is recorded as the tension pressure P 1 ;

[0025] The pressure difference between the second inner cavity, the fourth inner cavity and the furnace cavity is recorded as the tension pressure P 2 ;

[0026] The pressure difference between the first inner cavity, the fifth inner cavity and the furnace cavity is recorded as the tension pressure P 3 ;

[0027] The pressure difference between the third outer tube and the furnace chamber is recorded as the tension pressure P 4 ;

[0028] The pressure difference between the second outer tube, the fourth outer tube and the furnace chamber is recorded as the tension pressure P 5 ;

[0029] The pressure difference between the first outer tube, the fifth outer tube and the furnace chamber is recorded as the tension pressure P 6 ;

[0030] The total pressure difference between the inner tensioning tube and the carbon paper, and the outer tensioning tube 4 and the carbon paper is recorded as P;

[0031] P 1 =P 4 =0.6P; P 2 =P 5 =0.75P; P 3 =P 6 =P.

[0032] Preferably, the expansion pressure P is controlled at 0-50kPa at room temperature -400℃, 200-450kPa at 400-1000℃, 0-50kPa at 1000-1800℃, and 100-350kPa at above 1800℃; the expansion pressure should be controlled at 0-50kPa during the heating and cooling process.

[0033] Preferably, when the temperature is below 1800° C., the inert gas is nitrogen or argon; when the temperature is above 1800° C., the inert gas is argon.

[0034] The present invention adopts the above technical solution, and has the following technical effects compared with the prior art:

[0035] (1) The present invention can realize the batch carbonization and graphitization preparation of rolled carbon paper, which can not only realize the subsequent continuous preparation of gas diffusion layers, but also avoid the high equipment and energy consumption costs of high-temperature carbonization and graphitization, and effectively improve the preparation efficiency of carbon paper and gas diffusion layers.

[0036] (2) The tensioning device of the present invention can adjust the tension of the carbon paper through the internal tensioning component and the external tensioning component during the high-temperature carbonization and graphitization process, and can control the different tensions on the surface of the carbon paper according to different temperature ranges, thereby preventing the deformation of the carbon paper due to thermal shrinkage during the high-temperature carbonization and graphitization process, effectively improving the surface flatness and mechanical properties of the carbon paper, and further improving the power generation efficiency and service life of the hydrogen fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the coordination between the tensioning device and the carbon paper suitable for high-temperature carbonization and graphitization in one embodiment of the present invention;

[0038] Figure 2 A cross-sectional view of an inner tensioning tube in one embodiment of the present invention;

[0039] Figure 3 It is a schematic diagram of the basic structure of the inner tensioning tube in one embodiment of the present invention;

[0040] Figure 4 is a cross-sectional view of an inner tensioning assembly in one embodiment of the present invention;

[0041] Figure 5 It is a schematic diagram of the cooperation between the inner tensioning assembly and the inner tensioning cylinder in one embodiment of the present invention;

[0042] Figure 6 It is a cross-sectional view of the inner and outer tensioning cylinders in one embodiment of the present invention;

[0043] Figure 7 It is a basic structural schematic diagram of the inner and outer tensioning cylinders in one embodiment of the present invention;

[0044] Figure 8 A cross-sectional view of an inner and outer tensioning assembly in one embodiment of the present invention;

[0045] Fig. 9 It is a schematic diagram of the cooperation between the inner and outer tensioning components and the outer tensioning tube in one embodiment of the present invention.

[0046] Reference numerals in the figures include:

[0047] Inner tensioning cylinder 1; first inner cavity 11; second inner cavity 12; third inner cavity 13; fourth inner cavity 14; fifth inner cavity 15; inner fixing hole 16; inner cylinder inner fixing groove 17; inner cylinder outer fixing groove 18; partition 19; inner cylinder cover 2; inner cylinder pressure control assembly 3; first inner cylinder pressure control pipeline 31; second inner cylinder pressure control pipeline 32; third inner cylinder pressure control pipeline 33; outer tensioning cylinder 4; first outer cylinder 41; second outer cylinder 42; third outer cylinder 43; fourth outer cylinder 44 ; The fifth outer tube 45; The outer tube fixing hole 46; The outer tube inner fixing groove 47; The outer tube outer fixing groove 48; The outer tube cover 5; The outer tube pressure control assembly 6; The first outer tube pressure control pipeline 61; The second outer tube pressure control pipeline 62; The third outer tube pressure control pipeline 63; The inner tensioning assembly 7; The inner tensioning inner plate 71; The inner tensioning outer plate 72; The inner tensioning fixing bolt 73; The outer tensioning assembly 8; The outer tensioning inner plate 81; The outer tensioning outer plate 82; The outer tensioning fixing bolt 83; The carbon paper 9. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0050] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0051] Example 1

[0052] This embodiment provides a tensioning device suitable for high-temperature carbonization and graphitization. The tensioning device is made of high-density graphite with a density of not less than 1.85 g / cm 3 , Shore hardness is not less than 45, thermal expansion coefficient is not more than 2.0×10 -6 / K; the tensioning device comprises: an inner tensioning tube 1, an inner tube cover 2 detachably connected to the top end of the inner tensioning tube 1, an inner tube pressure control assembly 3 detachably connected to the inner tensioning tube 1, a plurality of outer tensioning tubes 4 sleeved outside the inner tensioning tube 1, an outer tube cover 5 detachably connected to the top end of the outer tensioning tube 4, and an outer tube pressure control assembly 6 arranged on the side wall of the outer tensioning tube 4;

[0053] The inner tensioning cylinder 1 is provided with a plurality of partitions 19, which divide the cavity in the inner tensioning cylinder 1 into a first inner cavity 11, a second inner cavity 12, a third inner cavity 13, a fourth inner cavity 14 and a fifth inner cavity 15 arranged in sequence from top to bottom; the partition 19 is provided with a partition opening for the inner cylinder pressure control assembly 3 to pass through;

[0054] The bottom end of the inner cylinder cover 2 is threadedly connected to the top end of the inner tension cylinder 1, and the inner cylinder cover 2 is provided with a plurality of through holes for the inner cylinder pressure control assembly 3 to pass through;

[0055] The inner cylinder pressure control assembly 3 includes: a first inner cylinder pressure control pipeline 31, a second inner cylinder pressure control pipeline 32 and a third inner cylinder pressure control pipeline 33; the first inner cylinder pressure control pipeline 31 is connected to the third inner cavity 13; the second inner cylinder pressure control pipeline 32 is connected to the second inner cavity 12 and the fourth inner cavity 14; the third inner cylinder pressure control pipeline 33 is connected to the first inner cavity 11 and the fifth inner cavity 15; the top ends of the first inner cylinder pressure control pipeline 31, the second inner cylinder pressure control pipeline 32 and the third inner cylinder pressure control pipeline 33 all pass through the inner cylinder cover 2 and are respectively connected to a flow meter and a pressure gauge;

[0056] A plurality of groups of inner tensioning components 7 are arranged on the side wall of the inner tensioning tube 1 along the axial direction of the inner tensioning tube 1; the number of the inner tensioning components 7 in each group is not less than three, and the plurality of inner tensioning components 7 in the same group are arranged equidistantly along the circumferential direction of the inner tensioning tube 1; the inner tensioning components 7 include: an inner tensioning inner plate 71 arranged in the inner tensioning tube 1, an inner tensioning outer plate 72 arranged outside the inner tensioning tube 1, and an inner tensioning fixing bolt 73; the inner tensioning inner plate 71 and the inner tensioning outer plate 72 are both arc-shaped; the inner tensioning tube 1 is opened on the side wall A plurality of inner fixing holes 16 are provided, an inner tube inner fixing groove 17 matching the inner tensioning inner plate 71 is provided on the inner wall of the inner tensioning tube 1, and an inner tube outer fixing groove 18 matching the inner tensioning outer plate 72 is provided on the outer wall of the inner tensioning tube 1; one end of the inner tensioning fixing bolt 73 passes through the inner tensioning inner plate 71, the side wall of the inner tensioning tube 1 and the inner tensioning outer plate 72 in sequence, connecting the inner tensioning assembly 7 and the inner tensioning tube 1; when the inner tensioning assembly 7 is subjected to the internal pressure of the inner tensioning tube 1, it will protrude outward to form tension on the carbon paper;

[0057] The outer tensioning tube 4 comprises a first side wall and a second side wall sleeved outside the first side wall, and an interlayer is formed between the first side wall and the second side wall; the outer tensioning tube 4 comprises, along its axial direction, a first outer tube 41, a second outer tube 42, a third outer tube 43, a fourth outer tube 44 and a fifth outer tube 45 connected in sequence from top to bottom; the first outer tube 41, the second outer tube 42, the third outer tube 43, the fourth outer tube 44 and the fifth outer tube 45 all have an interlayer; the outer tube cover 5 is connected to the top end of the first outer tube 41;

[0058] The outer cylinder pressure control assembly 6 includes: a first outer cylinder pressure control pipeline 61, a second outer cylinder pressure control pipeline 62 and a third outer cylinder pressure control pipeline 63; the first outer cylinder pressure control pipeline 61 is connected to the third outer cylinder 43, the second outer cylinder pressure control pipeline 62 is connected to the second outer cylinder 42 and the fourth outer cylinder 44, and the third outer cylinder pressure control pipeline 63 is connected to the first outer cylinder 41 and the fifth outer cylinder 45;

[0059] A plurality of outer tensioning components 8 are arranged on the first side wall of the outer tensioning tube 4; the outer tensioning components 8 include: an outer tensioning inner plate 81 arranged inside the first side wall, an outer tensioning outer plate 82 arranged outside the first side wall, and an outer tensioning fixing bolt 83; the outer tensioning inner plate 81 and the outer tensioning outer plate 82 are both arc-shaped; a plurality of outer tube fixing holes 46 are opened on the side wall of the outer tensioning tube 4; an outer tube inner fixing groove 47 matching the outer tensioning inner plate 81 is opened inside the first side wall of the outer tensioning tube 4, and an outer tube outer fixing groove 48 matching the outer tensioning outer plate 82 is opened outside the first side wall; one end of the outer tensioning fixing bolt 83 passes through the outer tensioning outer plate 82, the first side wall and the outer tensioning inner plate 81 in sequence to connect the outer tensioning component 8 and the outer tensioning tube 4. When the outer tensioning component 8 is subjected to the pressure of the outer tensioning tube 4, it will protrude inward to form tension on the carbon paper.

[0060] Example 2

[0061] This embodiment provides a method for using the tensioning device described in Embodiment 1, the steps comprising:

[0062] S1, after the impregnated and cured carbon paper is rolled up on the inner tensioning cylinder 1 to form a carbon paper coil of a certain thickness, the inner cylinder cover 2 and the inner cylinder pressure control assembly 3 are assembled according to the structure of Example 1, and the outer tensioning cylinder 4 is sleeved on the carbon paper coil, and then the outer cylinder cover 5 and the outer cylinder pressure control assembly 6 are assembled;

[0063] S2. Place the assembled tensioning device vertically in the graphitization furnace. The inner tube pressure control assembly 3 and the outer tube pressure control assembly 6 are connected to argon gas, respectively, and are equipped with flow meters and pressure gauges. After the argon gas is purged and replaced in the furnace cavity and the entire tensioning device, the graphitization furnace is turned on for heating and the temperature is raised from room temperature to 2360°C at a heating rate of 5°C / min. During this period, the flow rate of the introduced argon gas is adjusted so that the tensioning pressure of each part meets P 1 =P 4 =0.6P; P 2 =P 5 =0.75P; P 3 =P 6 =P;

[0064] According to this tensioning pressure setting, the tension in the middle of the carbon paper width direction is relatively uniform, and the thermal deformation amplitude is small under high temperature treatment, so the tensioning pressure P 1 , P 4 It should not be too large to provide tension for the carbon paper to keep the paper surface flat; however, the edge of the carbon paper in the width direction has no tension on one side, and the force is relatively uneven. During the high-temperature treatment, the deformation amplitude is large, which is easy to cause large shrinkage and wrinkles, so the tension pressure P should be appropriately increased. 3 , P 6 To keep the paper surface flat;

[0065] The pressure difference between the third inner chamber 13 and the furnace chamber is recorded as the tension pressure P 1 ;

[0066] The pressure difference between the second inner cavity 12, the fourth inner cavity 14 and the furnace cavity is recorded as the tension pressure P 2 ;

[0067] The pressure difference between the first inner cavity 11, the fifth inner cavity 15 and the furnace cavity is recorded as the tension pressure P 3 ;

[0068] The pressure difference between the third outer tube 43 and the furnace chamber is recorded as the tension pressure P 4 ;

[0069] The pressure difference between the second outer tube 42, the fourth outer tube 44 and the furnace chamber is recorded as the tension pressure P 5 ;

[0070] The pressure difference between the first outer tube 41, the fifth outer tube 45 and the furnace chamber is recorded as the tension pressure P 6 ;

[0071] The total pressure difference between the inner tensioning tube 1 and the carbon paper, and the outer tensioning tube 4 and the carbon paper is recorded as P;

[0072] At room temperature -400℃, the tightening pressure P is controlled to be 15kPa, at 400-1000℃, the tightening pressure P is controlled to be 350kPa, at 1000-1800℃, the tightening pressure P is controlled to be 15kPa, and at temperatures above 1800℃, the tightening pressure P is controlled to be 180kPa; after the temperature rise is completed and the temperature drop is ended, the tightening pressure should be controlled to be 35kPa;

[0073] The control is carried out according to the corresponding relationship between the tensioning temperature and the pressure. This is mainly because a large amount of organic structure of carbon paper completes thermal decomposition at 400-1000℃, and the material will shrink and deform. Increasing the tensioning force can effectively provide tension for the carbon paper coil and inhibit the influence of this thermal shrinkage on the carbon paper material. A certain tensioning force also needs to be maintained above 1800℃. This is mainly because during the graphitization process, the graphite-like hexagonal ring structure gradually transitions to a layered hexagonal lattice graphite structure, accompanied by a certain contraction of molecular bonds. It is also necessary to continuously provide carbon paper tension to maintain a smooth paper surface.

[0074] Comparative Example

[0075] This comparative example provides another tensioning device and a method for using the same. The tensioning device consists of an inner cylinder and an outer cylinder. The method for using the tensioning device is to place a rolled carbon paper between the inner cylinder and the outer cylinder, and to place the tensioning device in a graphitization furnace for graphitization.

[0076] Detection Example

[0077] The carbon paper prepared by the method described in Example 2 and the comparative example was subjected to performance tests, including the tensile strength, bending strength, and surface roughness of the carbon paper; the results are shown in Table 1;

[0078] Table 1

[0079] Tensile strength (MPa) Bending strength (MPa) Surface roughness (μm) Example 19.6 26.0 10 Comparative Example 7.6 9.3 203

[0080] Since the tensioning device of the embodiment has an inner tensioning component 7 and an outer tensioning component 8, the paper surface of the carbon paper can continuously provide tension during the high-temperature graphitization process, effectively reducing deformation, wrinkles, etc. caused by thermal shrinkage, and the surface roughness is only 10μm; while in the comparative example, not only does thermal shrinkage cause certain deformation and bending, with a roughness of more than 200μm, but the conversion of the graphitized structure into a hexagonal carbon ring layer is incomplete, with certain defects and pores, so the mechanical properties are also significantly reduced, only less than half of the mechanical properties of the carbon paper in the embodiment; as a gas diffusion layer substrate, these defects are bound to be introduced into the fuel cell, causing performance degradation and decreased stability.

[0081] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A tensioning device suitable for high temperature carbonization and graphitization, characterized in that: include: An inner tensioning tube (1), an inner tube cover (2) detachably connected to the top end of the inner tensioning tube (1), an inner tube pressure control assembly (3) detachably connected to the inner tensioning tube (1), an outer tensioning tube (4) sleeved outside the inner tensioning tube (1), an outer tube cover (5) detachably connected to the top end of the outer tensioning tube (4), and an outer tube pressure control assembly (6) arranged on the side wall of the outer tensioning tube (4); A plurality of inner tensioning components (7) are provided on the side wall of the inner tensioning tube (1); the inner tensioning components (7) comprise: an inner tensioning inner plate (71) provided inside the inner tensioning tube (1), an inner tensioning outer plate (72) provided outside the inner tensioning tube (1), and an inner tensioning fixing bolt (73); one end of the inner tensioning fixing bolt (73) passes through the inner tensioning inner plate (71), the side wall of the inner tensioning tube (1), and the inner tensioning outer plate (72) in sequence, so as to connect the inner tensioning component (7) and the inner tensioning tube (1); the inner tensioning The cavity in the tightening cylinder (1) is divided into a first inner cavity (11), a second inner cavity (12), a third inner cavity (13), a fourth inner cavity (14) and a fifth inner cavity (15) which are arranged in order from top to bottom; the pressure difference between the third inner cavity (13) and the furnace cavity of the high-temperature treatment equipment is recorded as the tightening pressure P1; the pressure difference between the second inner cavity (12), the fourth inner cavity (14) and the furnace cavity of the high-temperature treatment equipment is recorded as the tightening pressure P2; the pressure difference between the first inner cavity (11), the fifth inner cavity (15) and the furnace cavity of the high-temperature treatment equipment is recorded as the tightening pressure P3; The outer tensioning tube (4) comprises a first side wall and a second side wall sleeved outside the first side wall, and a sandwich is formed between the first side wall and the second side wall; a plurality of outer tensioning components (8) are arranged on the first side wall of the outer tensioning tube (4); the outer tensioning components (8) comprise: an outer tensioning inner plate (81) arranged inside the first side wall, an outer tensioning outer plate (82) arranged outside the first side wall, and an outer tensioning fixing bolt (83); one end of the outer tensioning fixing bolt (83) passes through the outer tensioning outer plate (82), the first side wall, and the outer tensioning inner plate (81) in sequence, and connects the outer tensioning The outer tensioning tube (4) comprises a first outer tube (41), a second outer tube (42), a third outer tube (43), a fourth outer tube (44) and a fifth outer tube (45) connected in sequence from top to bottom along its axial direction; the pressure difference between the third outer tube (43) and the furnace chamber of the high-temperature treatment equipment is recorded as a tensioning pressure P4; the pressure difference between the second outer tube (42), the fourth outer tube (44) and the furnace chamber of the high-temperature treatment equipment is recorded as a tensioning pressure P5; the pressure difference between the first outer tube (41), the fifth outer tube (45) and the furnace chamber of the high-temperature treatment equipment is recorded as a tensioning pressure P6; The total pressure difference between the inner tensioning tube (1) and the carbon paper, and between the outer tensioning tube (4) and the carbon paper is recorded as P; P1=P4=0.6P, P2=P5=0.75P, P3=P6=P.

2. The tensioning device according to claim 1, characterized in that: A plurality of partitions (19) are arranged in the inner tensioning cylinder (1), and the plurality of partitions (19) divide the cavity in the inner tensioning cylinder (1) into the first inner cavity (11), the second inner cavity (12), the third inner cavity (13), the fourth inner cavity (14) and the fifth inner cavity (15) which are arranged in sequence from top to bottom; and a partition opening is provided on the partition (19) for the inner cylinder pressure control assembly (3) to pass through.

3. The tensioning device according to claim 2, characterized in that: The inner cylinder pressure control assembly (3) comprises: a first inner cylinder pressure control pipeline (31), a second inner cylinder pressure control pipeline (32) and a third inner cylinder pressure control pipeline (33); the first inner cylinder pressure control pipeline (31) is in communication with the third inner cavity (13); the second inner cylinder pressure control pipeline (32) is in communication with the second inner cavity (12) and the fourth inner cavity (14); and the third inner cylinder pressure control pipeline (33) is in communication with the first inner cavity (11) and the fifth inner cavity (15).

4. The tensioning device according to claim 1, characterized in that: A plurality of groups of inner tensioning components (7) are arranged on the side wall of the inner tensioning tube (1) along the axial direction of the inner tensioning tube (1); the number of the inner tensioning components (7) in each group is not less than three, and the plurality of inner tensioning components (7) in the same group are arranged equidistantly along the circumferential direction of the inner tensioning tube (1); A plurality of groups of the outer tensioning components (8) are provided on the first side wall of the outer tensioning cylinder (4) along the axial direction of the outer tensioning cylinder (4), the number of the outer tensioning components (8) in each group is not less than three, and the plurality of outer tensioning components (8) in the same group are equidistantly arranged along the circumferential direction of the first side wall.

5. The tensioning device according to claim 1, characterized in that: An inner tube inner fixing groove (17) matching the inner tension inner plate (71) is formed on the inner wall of the inner tension tube (1), and an inner tube outer fixing groove (18) matching the inner tension outer plate (72) is formed on the outer wall of the inner tension tube (1).

6. The tensioning device according to claim 1, characterized in that: The first outer tube (41), the second outer tube (42), the third outer tube (43), the fourth outer tube (44) and the fifth outer tube (45) of the outer tensioning tube (4) all have an interlayer; the outer tube cover (5) is connected to the top end of the first outer tube (41).

7. The tensioning device according to claim 6, characterized in that: The outer cylinder pressure control assembly (6) comprises: a first outer cylinder pressure control pipeline (61), a second outer cylinder pressure control pipeline (62) and a third outer cylinder pressure control pipeline (63); the first outer cylinder pressure control pipeline (61) is connected to the third outer cylinder (43), the second outer cylinder pressure control pipeline (62) is connected to the second outer cylinder (42) and the fourth outer cylinder (44), and the third outer cylinder pressure control pipeline (63) is connected to the first outer cylinder (41) and the fifth outer cylinder (45).

8. The tensioning device according to claim 1, characterized in that: An outer tube inner fixing groove (47) matching the outer tube inner plate (81) is formed inside the first side wall of the outer tension tube (4), and an outer tube outer fixing groove (48) matching the outer tube outer plate (82) is formed outside the first side wall.

9. A method for using a tensioning device, using the tensioning device according to any one of claims 1 to 8, characterized in that the steps include: S1, rolling the carbon paper onto the inner tensioning cylinder (1) to form a carbon paper coil, assembling the inner cylinder cover (2) and the inner cylinder pressure control assembly (3), and sleeve the outer tensioning cylinder (4) onto the carbon paper coil, and then assembling the outer cylinder cover (5) and the outer cylinder pressure control assembly (6); S2. Place the assembled tensioning device vertically in the high-temperature treatment equipment. The inner tube pressure control assembly (3) and the outer tube pressure control assembly (6) are respectively connected to an inert gas source and are equipped with a flow meter and a pressure gauge. By introducing inert gas, the pressure of the inner tensioning assembly (7) on the inner tensioning tube (1) and the outer tensioning assembly (8) on the outer tensioning tube (4) on the carbon paper coil is controlled.

10. The method of use according to claim 9, characterized in that: The pressure difference between the third inner cavity (13) and the furnace cavity of the high temperature treatment equipment is recorded as the expansion pressure P1; the pressure difference between the second inner cavity (12), the fourth inner cavity (14) and the furnace cavity of the high temperature treatment equipment is recorded as the expansion pressure P2; the pressure difference between the first inner cavity (11), the fifth inner cavity (15) and the furnace cavity of the high temperature treatment equipment is recorded as the expansion pressure P3; the pressure difference between the third outer cylinder (43) and the furnace cavity of the high temperature treatment equipment is recorded as the expansion pressure P4; the pressure difference between the second outer cylinder (42), the fourth outer cylinder (44) and the furnace cavity of the high temperature treatment equipment is recorded as the expansion pressure P5; the pressure difference between the first outer cylinder (41), the fifth outer cylinder (45) and the furnace cavity of the high temperature treatment equipment is recorded as the expansion pressure P6; the total pressure difference between the inner expansion cylinder (1) and the carbon paper, and the outer expansion cylinder (4) and the carbon paper is recorded as P; P1=P4=0.6P, P2=P5=0.75P, P3=P6=P; During the heating process, at room temperature -400℃, control the expansion pressure P=0-50kPa, at 400-1000℃, control the expansion pressure P=200-450kPa, at 1000-1800℃, control the expansion pressure P=0-50kPa, above 1800℃, control the expansion pressure P=100-350kPa; when the heating is completed and the cooling process is ended, control the expansion pressure P=0-50kPa.

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