A cathode plate, its production process and application

Abstract

The present invention provides a cathode plate and its production process and application. The cathode plate includes a fiber core layer, a titanium carbide doped layer, a composite layer of titanium carbide and silicon carbide, and a surface layer, which are arranged in sequence from the inside to the outside. Through the design of the titanium carbide doped layer and the composite layer of titanium carbide and silicon carbide, the present invention significantly improves the electrical conductivity and mechanical strength of the cathode plate. At the same time, the design of the composite layer of titanium carbide and silicon carbide further enhances the high-temperature resistance and chemical stability of the material, enabling the cathode plate to still maintain excellent performance under harsh environments such as high temperature, acid and alkali.

Description

Technical Field

[0001] This application belongs to the technical field of electrode materials, and particularly relates to a cathode plate, its production process and application. Background Art

[0002] The cathode plate plays a crucial role in fuel cells. It is one of the key components in a fuel cell stack and is usually used in conjunction with the anode plate to jointly complete the electrochemical reaction. The cathode plate is mainly responsible for contacting with the oxidant (such as oxygen) and generating current and water through catalytic reactions.

[0003] Traditional cathode plates are mostly made of stainless steel or titanium, which have problems such as poor electrical conductivity and severe acid corrosion. At present, C / C composite cathode plates do have advantages over traditional copper cathodes in terms of high temperature resistance, chemical stability, acid and alkali corrosion resistance, etc., but some areas need to be improved and enhanced during operation: the resistivity of C / C composite cathode plates is generally 11 - 15 μΩ·m, and there will be relatively large resistance losses during the current transmission process, resulting in more electrical energy being converted into heat, reducing the electrical energy utilization efficiency and increasing the energy consumption cost. At the same time, the relatively high resistivity may affect the kinetic process of the electrode reaction. In electrochemical processes such as electrolysis, the resistance will cause uneven potential distribution on the electrode surface, making the electrode reaction unable to proceed uniformly, which may reduce the electrolysis efficiency and affect the consistency of product quality. At the same time, it may also increase the electrode polarization phenomenon, further reducing the efficiency of the electrochemical process and the energy utilization rate. Therefore, a cathode plate with low resistance is needed. Summary of the Invention

[0004] This application provides a cathode plate, its production process and application, aiming to solve the problem of high resistivity of the cathode plate to a certain extent.

[0005] The first aspect of the present invention provides a cathode plate, which includes a fiber core layer, a titanium carbide doped layer, a titanium carbide and silicon carbide composite layer, and a surface layer arranged in sequence from the inside out.

[0006] The second aspect of the present invention provides a production process of a cathode plate, including the following steps:

[0007] 1) Mix T800 fibers, chopped fibers and polyarylacetylene resin to form a fiber core layer;

[0008] 2) After hot pressing and curing the fiber core layer, introduce a carbon source, a titanium source, a silicon source and a carrier gas for microwave pulse deposition to respectively form a titanium carbide doped layer and a titanium carbide and silicon carbide composite layer on the surface of the fiber core layer, obtaining a deposited part;

[0009] 3) Impregnate and carbonize the deposited part to obtain the cathode plate.

[0010] Further, the mass ratio of the T800 fiber, the chopped fiber and the polyarylacetylene resin is 50:10 - 20:25 - 40.

[0011] Further, the hot pressing and curing is carried out under the condition of a pressure of 0.3 - 0.8 MPa. It is heated to 80 - 90 °C in 1.5 - 2 h, kept warm for 10 - 20 min, then heated to 150 - 160 °C in 2.5 - 3 h, kept warm for 10 - 20 min, and then heated to 210 - 230 °C in 1.5 - 2 h and kept warm for 10 - 20 min.

[0012] Further, the microwave pulse deposition includes a first deposition and a second deposition;

[0013] During the first deposition, a carbon source, a titanium source and a carrier gas are introduced;

[0014] The temperature of the first deposition is 1100 - 1300 °C, and the deposition time is 4 - 5 h;

[0015] During the second deposition, a carbon source, a silicon source, a titanium source and a carrier gas are introduced;

[0016] The temperature of the second deposition is 1000 - 1200 °C, and the deposition time is 6 - 7 h.

[0017] Further, the dosage of the silicon source during the second deposition is less than 0.5% of the total mass of the sum of the carbon source, the titanium source and the carrier gas.

[0018] Further, the microwave power of the microwave pulse deposition is 2.8 - 3.5 kW.

[0019] Further, the pressure of the impregnation for impregnating the deposited part is 30 - 40 MPa, the temperature is 200 - 220 °C, and the time is 4 - 5 h.

[0020] Further, the carbonization treatment includes heating the deposited part after impregnation treatment to 640 - 660 °C at a rate of 1 - 3 °C / min under N2 protection, keeping warm for 2 - 3 h for pre - carbonization treatment to obtain a pre - carbonized part;

[0021] Heating the pre - carbonized part to 1700 - 1850 °C at a rate of 8 - 10 °C / min under an Ar atmosphere and keeping warm for 3 - 4 h for graphitization treatment;

[0022] Continuing to heat to 2200 - 2300 °C under a He atmosphere and keeping warm for 1 - 2 h for high - temperature purification.

[0023] The content of the third aspect of the present invention provides an application of a cathode plate in an electrode material.

[0024] The present invention has the following beneficial effects:

[0025] (1) The cathode plate of the present invention includes a fiber core layer, a titanium carbide doped layer, a titanium carbide and silicon carbide composite layer, and a surface layer arranged in sequence from inside to outside. The design of the titanium carbide doped layer and the titanium carbide and silicon carbide composite layer significantly improves the conductivity and mechanical strength of the cathode plate. Titanium carbide, as a high-performance ceramic material, has excellent conductivity and high-temperature resistance. Doping it between the fiber core layer and the surface layer can effectively reduce the resistivity and improve the current transmission efficiency. At the same time, the design of the titanium carbide and silicon carbide composite layer further enhances the high-temperature resistance and chemical stability of the material, enabling the cathode plate to maintain excellent performance under harsh environments such as high temperature, acid, and alkali.

[0026] (2) The production process of the present invention uses hot pressing curing and microwave pulse deposition technologies, combined with impregnation and carbonization treatments, to achieve the efficient preparation of the cathode plate. The hot pressing curing process ensures the uniformity and denseness of the fiber core layer, providing a good foundation for subsequent microwave pulse deposition. The microwave pulse deposition technology has the advantages of high efficiency, uniformity, and controllability, and can achieve the deposition and modification of materials in a short time. The impregnation and carbonization treatments further improve the density and uniformity of the materials, ensuring the final performance of the cathode plate.

[0027] (3) The cathode plate of the present invention has broad application prospects in electrode materials. Due to its low resistivity, high conductivity, and high-temperature resistance, it can significantly improve the efficiency and stability of electrochemical devices such as fuel cells and electrolytic cells. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is the metallographic diagram provided in Embodiment 1;

[0030] Figure 2 It is the 500-fold field emission electron microscope scanning photo of Embodiment 1;

[0031] Figure 3 It is the CVI surface diagram provided in Embodiment 1;

[0032] Figure 4 It is the CVI layer polarization analysis diagram provided in Embodiment 1. Detailed Embodiments

[0033] In order to make the technical problems to be solved, technical solutions and beneficial effects of this application more clear and understandable, the following further details this application in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0034] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the front and back associated objects.

[0035] The terms used in the embodiments of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms "a", "the" and "said" used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0036] It should be understood that in various embodiments of this application, the magnitude of the sequence numbers of each process does not mean the order of execution. Some or all steps can be executed in parallel or successively. The execution order of each process should be determined by its function and internal logic and should not constitute any limitation to the implementation process of the embodiments of this application.

[0037] Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in this application can be obtained through the market or can be prepared by existing methods.

[0038] The following uses specific examples and comparative examples to illustrate the technical solutions of this application.

[0039] An embodiment of the first aspect of the present invention provides a cathode plate, which includes a fiber core layer, a titanium carbide doped layer, a titanium carbide and silicon carbide composite layer, and a surface layer arranged in sequence from the inside to the outside.

[0040] Among them, the design of the titanium carbide doped layer and the titanium carbide and silicon carbide composite layer significantly improves the conductivity and mechanical strength of the cathode plate. As a high-performance ceramic material, titanium carbide has excellent conductivity and high-temperature resistance. Doping it between the fiber core layer and the surface layer can effectively reduce the resistivity and improve the current transmission efficiency. At the same time, the design of the titanium carbide and silicon carbide composite layer further enhances the high-temperature resistance and chemical stability of the material, enabling the cathode plate to still maintain excellent performance in harsh environments such as high temperature, acid and alkali.

[0041] An embodiment of the second aspect of the present invention provides a production process of a cathode plate, including the following steps:

[0042] 1) Mix T800 fibers, chopped fibers and polyarylacetylene resin to form a fiber core layer;

[0043] 2) After hot pressing and curing the fiber core layer, introduce a carbon source, a titanium source, a silicon source and a carrier gas for microwave pulse deposition to form a titanium carbide doped layer and a composite layer of titanium carbide and silicon carbide on the surface of the fiber core layer respectively, obtaining a deposited part;

[0044] 3) Impregnate the deposited part and then perform carbonization treatment to obtain a cathode plate.

[0045] The raw materials of the present invention include T800 fibers, chopped fibers and polyarylacetylene resin. Among them, the T800 fibers and chopped fibers synergistically reinforce the polyarylacetylene resin matrix, significantly improving the overall mechanical properties and electrical conductivity of the material. The production process of the present invention adopts hot pressing and curing and microwave pulse deposition technologies, combined with impregnation and carbonization treatment, to achieve the efficient preparation of the cathode plate. The hot pressing and curing process ensures the uniformity and denseness of the fiber core layer, providing a good basis for subsequent microwave pulse deposition. The microwave pulse deposition technology has the advantages of high efficiency, uniformity, controllability, etc., and can achieve the deposition and modification of materials in a short time. The impregnation and carbonization treatment further improve the density and uniformity of the material, ensuring the final performance of the cathode plate, significantly enhancing the electrical conductivity and high-temperature resistance of the composite material, and the resistivity of the obtained cathode plate can reach as low as 6.3 μΩ·m, meeting the application requirements of high-performance materials.

[0046] In the embodiment of the present invention, the diameter of the T800 fiber is 7 μm, the diameter of the chopped fiber is 0.5 μm, and the length of the chopped fiber is 50 - 100 μm. The T800 fiber has excellent tensile strength and elastic modulus, while the chopped fiber provides good dispersibility and interfacial bonding performance. Their combined action significantly improves the mechanical properties and electrical conductivity of the composite material. Further, before use, the T800 fiber and chopped fiber are pretreated. Among them, the T800 carbon fiber is ultrasonically cleaned with acetone for 30 minutes, at a frequency of 40 kHz and a temperature of 80 °C to remove the surface sizing. The chopped carbon fiber is treated by ball milling at a rotation speed of 300 rpm for 2 h to control the length of the chopped carbon fiber within 50 - 100 μm.

[0047] In the embodiment of the present invention, the mass ratio of the T800 fiber, chopped fiber and polyarylacetylene resin is 50:10 - 20:25 - 40. Preferably, the mass ratio of the T800 fiber, chopped fiber and polyarylacetylene resin is 50:15:35. This ratio has been verified through multiple experiments and can obtain the best composite material performance, ensuring the quality and stability of the cathode plate.

[0048] In an embodiment of the present invention, the hot pressing and curing process involves pouring the fiber core layer into a graphite mold. Under the condition of a pressure of 0.3 - 0.8 MPa, it is heated to 80 - 90 °C in 1.5 - 2 h, kept warm for 10 - 20 min, then heated to 150 - 160 °C in 2.5 - 3 h, kept warm for 10 - 20 min, and then heated to 210 - 230 °C in 1.5 - 2 h, and kept warm for 10 - 20 min. After curing, it is cooled to 60 - 70 °C for demolding. Through the step - by - step heating and heat - preservation process, the internal stress of the material is ensured to be released evenly, avoiding structural defects caused by sudden temperature changes, and significantly improving the durability and reliability of the composite material.

[0049] In an embodiment of the present invention, the microwave power of the microwave pulse deposition is 2.8 - 3.5 kW, and the microwave pulse deposition includes a first deposition and a second deposition;

[0050] During the first deposition, a carbon source, a titanium source, and a carrier gas are introduced;

[0051] The temperature of the first deposition is 1100 - 1300 °C, and the deposition time is 4 - 5 h;

[0052] During the second deposition, a carbon source, a silicon source, a titanium source, and a carrier gas are introduced;

[0053] The temperature of the second deposition is 1000 - 1200 °C, and the deposition time is 6 - 7 h.

[0054] Specifically, the microwave pulse deposition includes introducing C3H6, TiCl4, and Ar into the microwave reactor at 800 - 900 °C, heating to a temperature of 1100 - 1300 °C, and depositing for 4 - 5 h to form a TiC doped layer; preferably, the microwave power is 3.5 kW, the temperature is 1200 °C, the pressure is 200 Pa, and the deposition time is 4 h. During the microwave pulse deposition process, the TiC doped layer uniformly covers the surface of the fiber core layer, enhancing the interfacial bonding force, effectively improving the wear resistance and oxidation resistance of the material, and further extending the service life of the cathode plate.

[0055] Then, C3H6, SiCl4, TiCl4, and Ar are introduced into the microwave reactor, and the temperature in the microwave reactor is controlled at 1000 - 1200 °C, and deposited for 6 - 7 h to form a SiC - TiC composite layer. Preferably, the microwave power is 2.8 kW, the temperature is 1100 °C, the pressure is 150 Pa, and the deposition time is 6 h. The SiC - TiC composite layer uniformly covers the surface of the TiC doped layer, enhancing the surface hardness and corrosion resistance of the material, and further improving the overall performance of the cathode plate.

[0056] The amount of silicon source used in the second deposition process is less than 0.5% of the total mass of the carbon source, titanium source, and carrier gas combined. Limiting the amount of SiCl4 to less than 0.5% of the total mass is because excessive silicon source will introduce more defects and reduce the conductivity of the material. By precisely controlling the amount of SiCl4, the uniform distribution of silicon carbide in the composite layer can be ensured while maintaining the excellent conductivity of the material. In addition, the microwave power of the microwave pulse deposition is controlled within the range of 2.8 - 3.5 kW. This power range can ensure the stability and efficiency of the deposition process and avoid the adverse effects of too high or too low power on the material properties.

[0057] After the microwave pulse deposition, the microwave is turned off, and the temperature is decreased to 500 °C at a rate of 5 °C / min under an Ar atmosphere to eliminate internal stress and ensure the stability of the material structure.

[0058] In the embodiment of the present invention, the pressure of the impregnation treatment for the deposition piece obtained in step 2) is 30 - 40 MPa, the temperature is 200 - 220 °C, and the time is 4 - 5 h.

[0059] Specifically, the deposition piece is subjected to impregnation treatment by injecting mesophase pitch (softening point 280 °C) into the deposition piece to 60% of its volume under the condition of a vacuum degree of 1×10 - ² Pa, and then introducing CO2 to make the impregnation pressure reach 30 - 40 MPa, while raising the temperature to 200 - 220 °C, maintaining the pressure for impregnation for 4 - 5 h, and slowly releasing the pressure to normal pressure (pressure release rate 0.5 MPa / min) to ensure that the pitch fully penetrates, forming a dense protective layer, enhancing the thermal shock resistance and chemical stability of the material, and ultimately realizing the long-term stable operation of the cathode plate in extreme environments.

[0060] In the embodiment of the present invention, the carbonization treatment includes heating the deposition piece subjected to impregnation treatment in a tubular furnace to 640 - 660 °C at a rate of 1 - 3 °C / min under N2 protection, and holding for 2 - 3 h for pre-carbonization treatment to obtain a pre-carbonized piece;

[0061] Transfer the pre-carbonized piece to a high-temperature graphitization furnace, and heat it to 1700 - 1850 °C at a rate of 8 - 10 °C / min under an Ar atmosphere, and hold for 3 - 4 h for graphitization treatment;

[0062] Continue to heat to 2200 - 2300 °C under a He atmosphere and hold for 1 - 2 h for high-temperature purification to remove impurities and ensure the purity of the material.

[0063] Finally, through multiple fine processes, a dense and uniform composite protective layer is formed on the surface of the cathode plate, significantly improving its durability and reliability in extreme environments such as high temperature and high pressure.

[0064] An embodiment of the third aspect of the present invention provides an application of a cathode plate in electrode materials.

[0065] Due to its unique structure and excellent performance, this cathode plate is particularly suitable as the electrode material for electrochemical devices such as fuel cells and electrolytic cells. Its high conductivity and high temperature resistance ensure the efficiency and stability of electrochemical devices during operation.

[0066] Example 1

[0067] A production process for a low-resistance cathode plate includes the following steps:

[0068] 1) Mix T800 fibers, chopped fibers, and polyarylacetylene resin in a ratio of 50:15:35, and stir to form a uniform slurry;

[0069] 2) Inject the fiber core layer into a graphite mold. Under the condition of a pressure of 0.5 MPa, heat it to 80 °C in 2 h, keep it warm for 10 min, then heat it to 150 °C in 2.5 h, keep it warm for 10 min, and then heat it to 220 °C in 1.5 h, keep it warm for 10 min; after curing, cool it to 60 °C and demold;

[0070] 3) Introduce C3H6, TiCl4, and Ar into the microwave reactor at 800 °C, heat it to a temperature of 1200 °C, with a microwave power of 3.5 kW, and deposit for 4 h to form a TiC doped layer; then introduce C3H6, SiCl4, TiCl4, and Ar into the microwave reactor, control the temperature in the microwave reactor to 1100 °C, with a microwave power of 2.8 kW, and deposit for 6 h to form a SiC-TiC composite layer, obtaining a deposited part;

[0071] 4) Immerse the deposited part, that is, under the condition of a vacuum degree of 1×10 - ² Pa, inject mesophase pitch into the deposited part, and then introduce CO2 to increase the vacuum degree to 35 MPa, while heating it to 200 °C and keeping the pressure for impregnation for 4 h;

[0072] 5) Heat the immersed deposited part to 650 °C at a rate of 2 °C / min under N2 protection, keep it warm for 2 h for pre-carbonization treatment to obtain a pre-carbonized part; heat the pre-carbonized part to 1800 °C at a rate of 9 °C / min under an Ar atmosphere, keep it warm for 3 h for graphitization treatment; continue to heat it to 2200 °C under a He atmosphere, keep it warm for 1 h for high-temperature purification, obtaining a low-resistance cathode plate.

[0073] The volume resistivity is measured by the four-point probe method. The resistance of the low-resistance cathode plate prepared under the conditions of this example is 6.3 μΩ·m. The three-point bending test is carried out using a universal testing machine, with a span of 100 mm and a loading rate of 1 mm / min, and the flexural strength is 165 MPa.

[0074] The metallographic diagram of the low-resistance cathode plate of this example is shown in Figure 1The metallographic image shows that the microstructure is uniform and dense with low porosity.

[0075] Figure 2 This is a 500-fold field emission electron microscope scanning photograph of the low-resistance cathode plate of this embodiment.

[0076] CVI surface diagram Figure 3 The CVI surface image shows that the material surface has good uniformity, without obvious cracks and holes, and the fine grain structure can be clearly identified. These grains are closely arranged, indicating the excellent density of the material.

[0077] CVI layer polarization analysis see Figure 4 ,The polarization image shows that the stress inside the CVI layer is evenly distributed without obvious ,stress concentration area, which further confirms the high stability of the material.

[0078] The process has passed ISO 9001 quality management system certification, with an annual production capacity of 5,000 pieces per line and a product qualification rate of 98.5%.

[0079] Example 2

[0080] The low resistance cathode plate was prepared by the process of Example 1, except that the T800 fiber, the chopped fiber and the polyarylacetylene resin were mixed in a ratio of 50:20:30.

[0081] The volume resistivity was tested using a four-point probe method, and the resistance of the low-resistance cathode plate prepared under the conditions of this embodiment was 8.5 μΩ·m. A three-point bending test was performed using a universal testing machine, with a span of 100 mm and a loading rate of 1 mm / min, and the bending strength was 143 MPa.

[0082] The reason why the flexural strength of Example 2 is lower than that of Example 1 is that the content of chopped fibers is increased. Although the dispersion and interfacial bonding properties of the material are enhanced, the density of the overall fiber structure is slightly decreased, resulting in a decrease in the flexural strength of the material when subjected to bending loads.

[0083] Example 3

[0084] The low resistance cathode plate was prepared by the process of Example 1, except that the T800 fiber, the chopped fiber and the polyarylacetylene resin were mixed in a ratio of 50:12:38.

[0085] The volume resistivity was tested using a four-point probe method, and the resistance of the low-resistance cathode plate prepared under the conditions of this embodiment was 7.5 μΩ·m. A three-point bending test was performed using a universal testing machine, with a span of 100 mm and a loading rate of 1 mm / min, and the bending strength was 124 MPa.

[0086] The reason why the flexural strength of Example 3 is lower than that of Example 1 is that the content of polyarylacetylene resin increases. Although the overall adhesion and processability of the material are improved, relatively, the content of fibers decreases, resulting in weakened mechanical support of the material, thus showing a lower flexural strength in the bending test.

[0087] Example 4

[0088] The low-resistance cathode plate was prepared by the process of Example 1, except that the fiber core layer was injected into a graphite mold. Under the condition of a pressure of 0.6 MPa, it was heated to 90 °C in 2 h, held for 20 min, then heated to 160 °C in 3 h, held for 20 min, and then heated to 230 °C in 2 h and held for 20 min.

[0089] The volume resistivity was measured by the four-point probe method. The resistance of the low-resistance cathode plate prepared under the conditions of this example was 7.1 μΩ·m. A three-point bending test was carried out using a universal testing machine, with a span of 100 mm and a loading rate of 1 mm / min. The flexural strength was 158 MPa.

[0090] Example 4 slightly adjusted the process time and temperature for hot pressing and curing the fiber core layer, and the flexural strength was relatively close to that of Example 1.

[0091] Example 5

[0092] The low-resistance cathode plate was prepared by the process of Example 1, except that C3H6, TiCl4 and Ar were introduced into a microwave reactor at 900 °C, heated to a temperature of 1300 °C, with a microwave power of 3.5 kW, and deposited for 5 h to form a TiC doped layer; then C3H6, SiCl4, TiCl4 and Ar were introduced into the microwave reactor, and the temperature in the microwave reactor was controlled at 1200 °C, with a microwave power of 2.8 kW, and deposited for 7 h to form a SiC-TiC composite layer, obtaining a deposited part.

[0093] The volume resistivity was measured by the four-point probe method. The resistance of the low-resistance cathode plate prepared under the conditions of this example was 9.6 μΩ·m. A three-point bending test was carried out using a universal testing machine, with a span of 100 mm and a loading rate of 1 mm / min. The flexural strength was 117 MPa.

[0094] Example 5 is compared with Example 1. The reason for the lower flexural strength is that the deposition time of microwave pulse is prolonged. Although the thickness and uniformity of the composite material are enhanced to a certain extent, the excessive deposition time also leads to the accumulation of internal stress in the material, resulting in a decrease in the flexural strength of the material in the bending test.

[0095] Example 6

[0096] The low-resistance cathode plate was prepared using the process of Example 1, except that the deposited part after impregnation treatment was heated to 660 °C at a rate of 3 °C / min under N2 protection and held for 3 h for pre-carbonization treatment to obtain a pre-carbonized part; the pre-carbonized part was heated to 1850 °C at a rate of 10 °C / min under an Ar atmosphere and held for 4 h for graphitization treatment; and it was further heated to 2300 °C under a He atmosphere and held for 2 h for high-temperature purification to obtain the low-resistance cathode plate.

[0097] The volume resistivity was measured using the four-point probe method. The resistance of the low-resistance cathode plate prepared under the conditions of this example was 10.2 μΩ·m. A three-point bending test was carried out using a universal testing machine with a span of 100 mm and a loading rate of 1 mm / min, and the flexural strength was 106 MPa.

[0098] Example 6 is in contrast to Example 1. The reason for the lower flexural strength may be that during the carbonization process, the temperature and time control of pre-carbonization, graphitization, and high-temperature purification are more stringent. Although such treatment conditions can further improve the purity and structural stability of the material, relatively speaking, they also increase the brittleness of the material, resulting in a decrease in the flexural strength of the material during the bending test.

[0099] Comparative Example 1

[0100] The low-resistance cathode plate was prepared using the process of Example 1, except that the T800 fiber, chopped fiber, and polyarylacetylene resin were replaced with graphite powder, phenolic resin, and chopped fiber.

[0101] The volume resistivity was measured using the four-point probe method. The resistance of the low-resistance cathode plate prepared under the conditions of this example was 16.4 μΩ·m. A three-point bending test was carried out using a universal testing machine with a span of 100 mm and a loading rate of 1 mm / min, and the flexural strength was 89 MPa.

[0102] This result shows that the combination of T800 fiber, chopped fiber, and polyarylacetylene resin can significantly reduce the resistivity of the cathode plate and improve the flexural strength compared with the traditional combination of graphite powder, phenolic resin, and chopped fiber. The high strength and modulus of the T800 fiber, as well as the excellent thermal stability and chemical inertness of the polyarylacetylene resin, jointly endow the cathode plate with excellent mechanical properties and weather resistance. In addition, the addition of chopped fiber further enhances the toughness and impact resistance of the material, enabling the cathode plate to maintain stability and durability in extreme environments.

[0103] Comparative Example 2

[0104] The low-resistance cathode plate was prepared using the process of Example 1, except that the microwave pulse deposition process was removed.

[0105] The volume resistivity was measured by the four-point probe method. The resistance of the low-resistance cathode plate prepared under the conditions of this example was 23.6 μΩ·m. The three-point bending test was carried out using a universal testing machine with a span of 100 mm and a loading rate of 1 mm / min, and the flexural strength was 68 MPa.

[0106] This result indicates that due to the lack of the microwave pulse deposition process, the internal structure of the material is uneven, the resistivity increases, and the flexural strength decreases. It can be seen that the microwave pulse deposition process has an important influence on the performance of the cathode plate.

[0107] Comparative Example 3

[0108] A low-resistance cathode plate was prepared using the process of Example 1, except that the mesophase pitch impregnation treatment was not used.

[0109] The volume resistivity was measured by the four-point probe method. The resistance of the low-resistance cathode plate prepared under the conditions of this example was 18.7 μΩ·m. The three-point bending test was carried out using a universal testing machine with a span of 100 mm and a loading rate of 1 mm / min, and the flexural strength was 76 MPa.

[0110] This result shows that the mesophase pitch impregnation treatment can significantly improve the uniformity of the internal structure of the cathode plate. The reason may be that the mesophase pitch can penetrate into the tiny pores of the material to form a continuous protective layer, effectively preventing the erosion of the external environment, and at the same time enhancing the internal bonding force of the material, thereby improving the overall mechanical and electrical properties.

[0111] Comparative Example 4

[0112] A low-resistance cathode plate was prepared using the process of Example 1, except that the heating rate of the pre-carbonized part in an Ar atmosphere was adjusted to 5 °C / min and graphitization treatment was carried out for 5 h.

[0113] The volume resistivity was measured by the four-point probe method. The resistance of the low-resistance cathode plate prepared under the conditions of this example was 9.8 μΩ·m. The three-point bending test was carried out using a universal testing machine with a span of 100 mm and a loading rate of 1 mm / min, and the flexural strength was 112 MPa.

[0114] This result indicates that too slow heating rate and too long holding time will lead to insufficient graphitization treatment, affect the graphitization degree of the material, and further increase the resistivity and decrease the flexural strength.

[0115] Comparative Example 5

[0116] A low-resistance cathode plate was prepared using the process of Example 1, except that the amount of silicon source used in the second deposition process was 10% of the total mass of the carbon source, titanium source and carrier gas.

[0117] The volume resistivity was tested using a four-point probe method, and the resistance of the low-resistance cathode plate prepared under the conditions of this embodiment was 17.5 μΩ·m. A three-point bending test was performed using a universal testing machine, with a span of 100 mm and a loading rate of 1 mm / min, and the bending strength was 84 MPa.

[0118] This result shows that excessive use of silicon source may lead to excessive SiC content in the SiC-TiC composite layer, destroying the balance between TiC and SiC, resulting in increased resistivity and decreased bending strength of the material. In addition, excessive silicon source may also cause uneven stress distribution inside the material, affecting its long-term stability.

[0119] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0120] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A production process of a cathode plate, characterized in that, It includes the following steps: 1) Mix T800 carbon fiber, chopped carbon fiber and polyarylacetylene resin to form a fiber core layer; 2) After hot pressing and curing the fiber core layer, introduce a carbon source, a titanium source, a silicon source and a carrier gas for microwave pulse deposition. The dosage of the silicon source is less than 0.5% of the total mass of the sum of the carbon source, the titanium source and the carrier gas. A titanium carbide doped layer and a composite layer of titanium carbide and silicon carbide are respectively formed on the surface of the fiber core layer to obtain a deposited part; 3) Inject the deposited part with mesophase pitch and then perform carbonization treatment. The carbonization treatment includes heating the deposited part after impregnation treatment to 640 - 660 °C at a rate of 1 - 3 °C / min under N2 protection, and holding for 2 - 3 h for pre-carbonization treatment to obtain a pre-carbonized part; Heat the pre-carbonized part to 1700 - 1850 °C at a rate of 8 - 10 °C / min under an Ar atmosphere, and hold for 3 - 4 h for graphitization treatment; Continue to heat to 2200 - 2300 °C under a He atmosphere and hold for 1 - 2 h for purification to obtain a cathode plate.

2. The production process of the cathode plate according to claim 1, characterized in that, The mass ratio of the T800 carbon fiber, chopped carbon fiber and polyarylacetylene resin is 50:10 - 20:25 - 40.

3. The production process of the cathode plate according to claim 1, characterized in that, The hot pressing and curing is carried out under a pressure of 0.3 - 0.8 MPa. It is heated to 80 - 90 °C in 1.5 - 2 h, held for 10 - 20 min, then heated to 150 - 160 °C in 2.5 - 3 h, held for 10 - 20 min, and then heated to 210 - 230 °C in 1.5 - 2 h, and held for 10 - 20 min.

4. The production process of the cathode plate according to claim 1, characterized in that, The microwave pulse deposition includes a first deposition and a second deposition; During the first deposition, a carbon source, a titanium source and a carrier gas are introduced; The temperature of the first deposition is 1100 - 1300 °C, and the deposition time is 4 - 5 h; During the second deposition, a carbon source, a silicon source, a titanium source and a carrier gas are introduced; The temperature of the second deposition is 1000 - 1200 °C, and the deposition time is 6 - 7 h.

5. The production process of the cathode plate according to claim 4, characterized in that, The microwave power of the microwave pulse deposition is 2.8 - 3.5 kW.

6. The production process of the cathode plate according to claim 1, characterized in that, The impregnation pressure for impregnating the deposited part is 30 - 40 MPa, the temperature is 200 - 220 °C, and the time is 4 - 5 h.

7. A cathode plate, characterized in that, Prepared by the production process of the cathode plate according to any one of claims 1 - 6, the cathode plate includes a fiber core layer, a titanium carbide doped layer, a composite layer of titanium carbide and silicon carbide, and a surface layer arranged in sequence from the inside to the outside.

8. Application of a cathode plate as claimed in claim 7 in an electrode material.

Images