Negative plate as well as production process and application thereof

Abstract

The invention provides a negative plate as well as a production process and application thereof. The negative plate comprises a fiber core layer, a titanium carbide doped layer, a titanium carbide and silicon carbide composite layer and a surface layer which are sequentially arranged from inside to outside. Through the design of the titanium carbide doping layer and the titanium carbide and silicon carbide composite layer, the conductivity and mechanical strength of the cathode plate are remarkably improved; meanwhile, due to the design of the titanium carbide and silicon carbide composite layer, the high temperature resistance and chemical stability of the material are further enhanced, and the cathode plate can still keep excellent performance in severe environments such as high temperature, acid and alkali.

Description

Technical Field

[0001] The present application belongs to the technical field of electrode materials, and in particular relates to a cathode plate and a production process and application thereof. Background Art

[0002] The cathode plate plays a vital 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 complete the electrochemical reaction. The cathode plate is mainly responsible for contacting with the oxidant (such as oxygen) and producing current and water through catalytic reactions.

[0003] Traditional cathode plates are mostly made of stainless steel or titanium, which have problems such as poor 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 for improvement and improvement have also been found during operation: the resistivity of C / C composite cathode plates is generally 11-15μΩ·m, and there will be relatively large resistance losses during current transmission, resulting in more electrical energy being converted into heat energy, reducing the efficiency of electrical energy utilization and increasing energy consumption costs. At the same time, higher resistivity may affect the kinetic process of electrode reactions. In electrochemical processes such as electrolysis, resistance will cause uneven potential distribution on the electrode surface, making the electrode reaction not uniform, which may reduce electrolysis efficiency and affect product quality consistency. At the same time, it may also increase electrode polarization, further reducing the efficiency and energy utilization of the electrochemical process. Therefore, a low-resistance cathode plate is required. Summary of the invention

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

[0005] A first aspect of the present invention provides a cathode plate, which includes a fiber core layer, a titanium carbide doping layer, a titanium carbide and silicon carbide composite layer, and a surface layer, which are sequentially arranged from the inside to the outside.

[0006] The second aspect of the present invention provides a cathode plate production process, comprising the following steps: 1) Mixing T800 fiber, chopped fiber and polyarylacetylene resin to form a fiber core layer; 2) After the fiber core layer is hot-pressed and solidified, a carbon source, a titanium source, a silicon source and a carrier gas are introduced to perform microwave pulse deposition to form a titanium carbide doped layer and a titanium carbide and silicon carbide composite layer on the surface of the fiber core layer to obtain a deposited part; 3) The deposited part is impregnated and then carbonized to obtain a cathode plate.

[0007] Furthermore, the mass ratio of the T800 fiber, the chopped fiber and the polyarylacetylene resin is 50:10-20:25-40.

[0008] Furthermore, the hot pressing curing is carried out under a pressure of 0.3-0.8 MPa, heating to 80-90°C for 1.5-2 hours, keeping warm for 10-20 minutes, heating to 150-160°C for 2.5-3 hours, keeping warm for 10-20 minutes, heating to 210-230°C for 1.5-2 hours, and keeping warm for 10-20 minutes.

[0009] Further, the microwave pulse deposition includes a first deposition and a second deposition; During the first deposition process, 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 hours; 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 hours.

[0010] Furthermore, the amount of silicon source used in the second deposition process is less than 0.5% of the total mass of the carbon source, the titanium source and the carrier gas.

[0011] Furthermore, the microwave power of the microwave pulse deposition is 2.8-3.5 kW.

[0012] Furthermore, the immersion treatment of the deposited part is carried out at a pressure of 30-40 MPa, a temperature of 200-220° C., and a time of 4-5 h.

[0013] Furthermore, the carbonization treatment includes subjecting the impregnated deposited part to N 2 Under protection, the temperature is raised to 640-660°C at 1-3°C / min, and kept at this temperature for 2-3 hours for pre-carbonization treatment to obtain a pre-carbonized part; The pre-carbonized part is heated to 1700-1850°C at 8-10°C / min in an Ar atmosphere and kept at this temperature for 3-4 hours for graphitization treatment; Continue to raise the temperature to 2200-2300°C under He atmosphere and keep it for 1-2 hours for high-temperature purification.

[0014] The third aspect of the present invention provides an application of a cathode plate in an electrode material.

[0015] The present invention has the following beneficial effects: (1) The cathode plate of the present invention includes a fiber core layer, a titanium carbide doping layer, a titanium carbide and silicon carbide composite layer, and a surface layer, which are arranged in sequence from the inside to the outside. The design of the titanium carbide doping 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, so that the cathode plate can still maintain excellent performance in harsh environments such as high temperature, acid and alkali.

[0016] (2) The production process of the present invention adopts hot pressing curing and microwave pulse deposition technology, combined with impregnation and carbonization treatment, to achieve efficient preparation of cathode plates. The hot pressing curing process ensures the uniformity and density of the fiber core layer, providing a good foundation for subsequent microwave pulse deposition. Microwave pulse deposition technology has the advantages of high efficiency, uniformity, and controllability, and can achieve material deposition and modification in a short time. Impregnation and carbonization treatment further improve the density and uniformity of the material, ensuring the final performance of the cathode plate.

[0017] (3) The cathode plate of the present invention has a wide range of 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 is the metallographic diagram provided in Example 1; Figure 2 This is a 500-fold field emission electron microscope scanning photograph of Example 1; Figure 3 is the CVI surface diagram provided in Example 1; Figure 4 This is a polarization analysis diagram of the CVI layer provided in Example 1. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0022] The terms used in the embodiments of the present application are only for the purpose of describing specific implementation rules, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the implementation rules of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0023] It should be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation regulations of this application.

[0024] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0025] The technical solution of the present application is illustrated below through specific embodiments and comparative examples.

[0026] An embodiment of the first aspect of the present invention provides a cathode plate, which includes a fiber core layer, a titanium carbide doping layer, a titanium carbide and silicon carbide composite layer, and a surface layer, which are arranged in sequence from the inside to the outside.

[0027] 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 material's high temperature resistance and chemical stability, allowing the cathode plate to maintain excellent performance in harsh environments such as high temperature, acid and alkali.

[0028] The embodiment of the second aspect of the present invention provides a cathode plate production process, comprising the following steps: 1) Mixing T800 fiber, chopped fiber and polyarylacetylene resin to form a fiber core layer; 2) After the fiber core layer is hot-pressed and solidified, a carbon source, a titanium source, a silicon source and a carrier gas are introduced to perform microwave pulse deposition to form a titanium carbide doped layer and a titanium carbide and silicon carbide composite layer on the surface of the fiber core layer to obtain a deposited part; 3) The deposited part is impregnated and then carbonized to obtain a cathode plate.

[0029] The raw materials of the present invention include T800 fiber, chopped fiber and polyarylacetylene resin, wherein the T800 fiber and the chopped fiber synergistically enhance the polyarylacetylene resin matrix, and significantly improve the overall mechanical properties and electrical conductivity of the material. The production process of the present invention adopts hot pressing curing and microwave pulse deposition technology, combined with impregnation and carbonization treatment, to achieve efficient preparation of the cathode plate. The hot pressing curing process ensures the uniformity and density of the fiber core layer, and provides a good foundation for subsequent microwave pulse deposition. Microwave pulse deposition technology has the advantages of high efficiency, uniformity, and controllability, and can achieve deposition and modification of materials in a short time. Impregnation and carbonization treatment further improve the density and uniformity of the material, ensure the final performance of the cathode plate, and significantly enhance the electrical conductivity and high temperature resistance of the composite material. The obtained cathode plate resistivity can reach as low as 6.3μΩ·m, which meets the application requirements of high-performance materials.

[0030] In an 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 properties, which together significantly improve the mechanical properties and conductivity of the composite material. Furthermore, before use, the T800 fiber and the 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 slurry. The chopped carbon fiber is ball-milled at a speed of 300 rpm for 2 hours to control the length of the chopped carbon fiber to 50-100 μm.

[0031] In an embodiment of the present invention, the mass ratio of the T800 fiber, the chopped fiber and the polyarylacetylene resin is 50:10-20:25-40. Preferably, the mass ratio of the T800 fiber, the chopped fiber and the polyarylacetylene resin is 50:15:35, which has been verified by multiple tests to obtain the best composite material performance and ensure the quality and stability of the cathode plate.

[0032] In an embodiment of the present invention, the hot pressing curing is to pour the fiber core layer into a graphite mold, and under a pressure of 0.3-0.8MPa, heat it to 80-90°C for 1.5-2h, keep it warm for 10-20min, heat it to 150-160°C for 2.5-3h, keep it warm for 10-20min, heat it to 210-230°C for 1.5-2h, keep it warm for 10-20min; cool it to 60-70°C and demould it after curing. Through the step-by-step heating and heat preservation process, the internal stress of the material is ensured to be evenly released, the structural defects caused by sudden temperature changes are avoided, and the durability and reliability of the composite material are significantly improved.

[0033] 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; During the first deposition process, 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 hours; 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 hours.

[0034] Specifically, the microwave pulse deposition comprises introducing C into a microwave reactor at 800-900°C. 3 H 6 、TiCl 4 and Ar, heating to 1100-1300°C, depositing for 4-5h to generate a TiC doped layer; preferably, microwave power 3.5kW, temperature 1200°C, pressure 200Pa, deposition for 4h. During the microwave pulse deposition process, the TiC doped layer is evenly covered on the surface of the fiber core layer, enhancing the interface bonding force, effectively improving the wear resistance and oxidation resistance of the material, and further extending the service life of the cathode plate.

[0035] Then, C 3 H 6 、SiCl 4 、TiCl 4 and Ar, control the temperature in the microwave reactor to 1000-1200°C, deposit for 6-7h, and generate a SiC-TiC composite layer. Preferably, the microwave power is 2.8kW, the temperature is 1100°C, the pressure is 150Pa, and the deposition is 6h. The SiC-TiC composite layer is evenly covered on 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.

[0036] 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. 4 The amount of SiCl is limited to less than 0.5% of the total mass because too much silicon source will introduce more defects and reduce the conductivity of the material. 4 The dosage can ensure the uniform distribution of silicon carbide in the composite layer while maintaining the excellent conductivity of the material. In addition, the microwave power of the microwave pulse deposition is controlled within the range of 2.8-3.5kW, which can ensure the stability and efficiency of the deposition process and avoid the adverse effects of excessive or low power on material properties.

[0037] After microwave pulse deposition, the microwave was turned off and the temperature was lowered to 500 °C at 5 °C / min in an Ar atmosphere to eliminate internal stress and ensure the stability of the material structure.

[0038] In an embodiment of the present invention, the immersion treatment of the deposited member obtained in step 2) is performed at a pressure of 30-40 MPa, a temperature of 200-220° C., and a time of 4-5 h.

[0039] Specifically, the deposited part is immersed in a vacuum of 1×10 - Under the condition of 2 Pa, the mesophase asphalt (softening point 280℃) was injected into the sediment to 60% of the volume, and then CO was introduced. 2 The immersion pressure reaches 30-40MPa, and the temperature is raised to 200-220℃ at the same time. The pressure is maintained for 4-5 hours, and the pressure is slowly released to normal pressure (pressure release rate 0.5MPa / min) to ensure that the asphalt is fully penetrated, forming a dense protective layer, enhancing the material's thermal shock resistance and chemical stability, and ultimately achieving long-term stable operation of the cathode plate in extreme environments.

[0040] In an embodiment of the present invention, the carbonization treatment comprises subjecting the impregnation treated deposited piece to a tube furnace, N 2 Under protection, the temperature is raised to 640-660°C at 1-3°C / min, and kept at this temperature for 2-3 hours for pre-carbonization treatment to obtain a pre-carbonized part; Transfer the pre-carbonized parts to a high-temperature graphitization furnace, heat to 1700-1850°C at 8-10°C / min in an Ar atmosphere, and keep the temperature for 3-4 hours for graphitization treatment; The temperature is continued to rise to 2200-2300°C in He atmosphere and kept at this temperature for 1-2 hours for high-temperature purification to remove impurities and ensure the purity of the material.

[0041] Finally, after multiple sophisticated processes, a dense and uniform composite protective layer is formed on the surface of the cathode plate, which significantly improves its durability and reliability in extreme environments such as high temperature and high pressure.

[0042] An embodiment of the third aspect of the present invention provides an application of a cathode plate in an electrode material.

[0043] Due to its unique structure and excellent performance, the cathode plate is particularly suitable as an electrode material for electrochemical devices such as fuel cells and electrolytic cells. Its high conductivity and high temperature resistance ensure the high efficiency and stability of the electrochemical device during operation.

[0044] Example 1 A production process for a low-resistance cathode plate comprises the following steps: 1) Mix T800 fiber, chopped fiber and polyarylacetylene resin in a ratio of 50:15:35 and stir to form a uniform slurry; 2) Inject the fiber core layer into the graphite mold, and under the condition of 0.5MPa pressure, heat it to 80℃ in 2h, keep it warm for 10min, then heat it to 150℃ in 2.5h, keep it warm for 10min, then heat it to 220℃ in 1.5h, keep it warm for 10min; after curing, cool it to 60℃ and demould; 3) C was introduced into the microwave reactor at 800 °C. 3 H 6 、TiCl 4 and Ar, heated to 1200°C, microwave power 3.5kW, deposition for 4h, to generate a TiC doped layer; then C was introduced into the microwave reactor. 3 H 6 、SiCl 4 and TiCl 4 and Ar, controlling the temperature in the microwave reactor to 1100°C, the microwave power to 2.8 kW, and the deposition time to 6 h to generate a SiC-TiC composite layer and obtain a deposited part; 4) The deposited part is immersed in a vacuum of 1×10 - 2Pa, the mesophase asphalt was injected into the sediment, and then CO 2 The vacuum degree was raised to 35 MPa, and the temperature was raised to 200°C, and the pressure was maintained for 4 hours; 5) Place the immersed deposited parts in N 2 Under protection, the temperature is increased to 650°C at 2°C / min and kept warm for 2 hours for pre-carbonization treatment to obtain a pre-carbonized part; the pre-carbonized part is heated to 1800°C at 9°C / min in an Ar atmosphere and kept warm for 3 hours for graphitization treatment; the temperature is further increased to 2200°C in a He atmosphere and kept warm for 1 hour for high-temperature purification to obtain a low-resistance cathode plate.

[0045] 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 6.3 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 165 MPa.

[0046] The metallographic diagram of the low resistance cathode plate of this embodiment is shown in Figure 1 The metallographic image shows that the microstructure is uniform and dense with low porosity.

[0047] Figure 2 This is a 500-fold field emission electron microscope scanning photograph of the low-resistance cathode plate of this embodiment.

[0048] 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.

[0049] 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.

[0050] 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%.

[0051] Example 2 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.

[0052] 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.

[0053] 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.

[0054] Example 3 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.

[0055] 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.

[0056] The reason why the flexural strength of Example 3 is lower than that of Example 1 is that the content of polyarylacetylene resin is increased. Although the overall adhesion and processability of the material are improved, the fiber content is relatively reduced, resulting in weakened mechanical support of the material, thereby showing lower flexural strength in the bending test.

[0057] Example 4 A low-resistance cathode plate was prepared using the process of Example 1, except that the fiber core layer was injected into a graphite mold, and the temperature was raised to 90°C for 2 hours under a pressure of 0.6 MPa, kept warm for 20 minutes, then raised to 160°C for 3 hours, kept warm for 20 minutes, then raised to 230°C for 2 hours, and kept warm for 20 minutes.

[0058] 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 7.1 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 158 MPa.

[0059] In Example 4, the process time and temperature of the hot pressing curing of the fiber core layer are slightly adjusted, and the bending strength is close to that of Example 1.

[0060] Example 5 The low-resistance cathode plate was prepared by the process of Example 1, except that C was introduced into the microwave reactor at 900°C. 3 H 6 、TiCl 4 and Ar, heated to 1300°C, microwave power 3.5kW, deposition for 5h, to generate a TiC doped layer; then C was introduced into the microwave reactor. 3 H 6 、SiCl 4 and TiCl 4 and Ar, controlling the temperature in the microwave reactor to 1200°C, the microwave power to 2.8 kW, the deposition time to 7 h, generating a SiC-TiC composite layer, and obtaining a deposited part.

[0061] 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 9.6 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 117 MPa.

[0062] Compared with Example 1, Example 5 has lower flexural strength because the time of microwave pulse deposition is prolonged. Although the thickness and uniformity of the composite material are enhanced to a certain extent, the excessively long deposition time also leads to the accumulation of internal stress in the material, which reduces the flexural strength of the material in the bending test.

[0063] Example 6 The low resistance cathode plate was prepared by the process of Example 1, except that the impregnated deposited piece was placed in N 2 Under protection, the temperature is increased to 660°C at 3°C / min and kept warm for 3 hours for pre-carbonization treatment to obtain a pre-carbonized part; the pre-carbonized part is heated to 1850°C at 10°C / min in an Ar atmosphere and kept warm for 4 hours for graphitization treatment; the temperature is further increased to 2300°C in a He atmosphere and kept warm for 2 hours for high-temperature purification to obtain a low-resistance cathode plate.

[0064] 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 10.2 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 106 MPa.

[0065] Compared with Example 1, the reason for the lower flexural strength of Example 6 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 processing conditions can further improve the purity and structural stability of the material, it also increases the brittleness of the material, resulting in a decrease in the flexural strength of the material in the bending test.

[0066] Comparative Example 1 The low resistance cathode plate was prepared by the process of Example 1, except that the T800 fiber, chopped fiber and polyarylacetylene resin were replaced by graphite powder, phenolic resin and chopped fiber.

[0067] 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 16.4 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 89 MPa.

[0068] 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 bending strength compared to the traditional combination of graphite powder, phenolic resin and chopped fiber. The high strength and modulus of T800 fiber and the excellent thermal stability and chemical inertness of polyarylacetylene resin together give the cathode plate excellent mechanical properties and weather resistance. In addition, the addition of chopped fiber further enhances the toughness and impact resistance of the material, allowing the cathode plate to maintain stability and durability in extreme environments.

[0069] Comparative Example 2 The low resistance cathode plate is prepared by the process of Example 1, except that the microwave pulse deposition step is removed.

[0070] 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 23.6 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 68 MPa.

[0071] This result shows that the lack of microwave pulse deposition process leads to uneven internal structure of the material, increased resistivity and decreased bending strength. It can be seen that microwave pulse deposition process has an important influence on the performance of the cathode plate.

[0072] Comparative Example 3 The low resistance cathode plate is prepared by the process of Example 1, except that the mesophase pitch impregnation treatment is not used.

[0073] 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 18.7 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 76 MPa.

[0074] This result shows that the mesophase asphalt impregnation treatment can significantly improve the uniformity of the internal structure of the cathode plate. The reason may be that the mesophase asphalt can penetrate into the tiny pores of the material to form a continuous protective layer, effectively preventing erosion from the external environment, while enhancing the internal bonding force of the material, thereby improving the overall mechanical and electrical properties.

[0075] Comparative Example 4 The low-resistance cathode plate was prepared by the process of Example 1, except that the heating rate of the pre-carbonized part in the Ar atmosphere was adjusted to 5° C. / min, and the graphitization treatment was carried out by keeping the temperature for 5 hours.

[0076] 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 9.8 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 112 MPa.

[0077] This result shows that a too slow heating rate and too long holding time will lead to insufficient graphitization treatment, affecting the graphitization degree of the material, thereby increasing the resistivity and reducing the flexural strength.

[0078] Comparative Example 5 The low resistance cathode plate was prepared by 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, the titanium source and the carrier gas.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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 cathode plate, characterized in that: The cathode plate comprises a fiber core layer, a titanium carbide doping layer, a titanium carbide and silicon carbide composite layer and a surface layer which are sequentially arranged from the inside to the outside.

2. A cathode plate production process, characterized in that: The following steps are involved: 1) Mixing T800 fiber, chopped fiber and polyarylacetylene resin to form a fiber core layer; 2) After the fiber core layer is hot-pressed and solidified, a carbon source, a titanium source, a silicon source and a carrier gas are introduced to perform microwave pulse deposition to form a titanium carbide doped layer and a titanium carbide and silicon carbide composite layer on the surface of the fiber core layer to obtain a deposited part; 3) The deposited part is impregnated and then carbonized to obtain a cathode plate.

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

4. The production process of the cathode plate according to claim 2, characterized in that: The hot pressing curing is carried out under the condition of a pressure of 0.3-0.8 MPa, heating to 80-90°C in 1.5-2 hours, keeping the temperature for 10-20 minutes, heating to 150-160°C in 2.5-3 hours, keeping the temperature for 10-20 minutes, heating to 210-230°C in 1.5-2 hours, and keeping the temperature for 10-20 minutes.

5. The production process of the cathode plate according to claim 2, characterized in that: The microwave pulse deposition includes a first deposition and a second deposition; During the first deposition process, 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 hours; 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 hours.

6. The production process of the cathode plate according to claim 5, characterized in that: The amount of silicon source used in the second deposition process is less than 0.5% of the total mass of the carbon source, the titanium source and the carrier gas.

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

8. The production process of the cathode plate according to claim 2, characterized in that: The immersion treatment of the deposited part has an immersion pressure of 30-40 MPa, a temperature of 200-220° C., and a time of 4-5 hours.

9. The production process of the cathode plate according to claim 2, characterized in that: The carbonization treatment includes heating the impregnated deposited part to 640-660°C at 1-3°C / min under N2 protection, and keeping the temperature for 2-3h to perform pre-carbonization treatment to obtain a pre-carbonized part; The pre-carbonized part is heated to 1700-1850°C at 8-10°C / min in an Ar atmosphere and kept at this temperature for 3-4 hours for graphitization treatment; Continue to raise the temperature to 2200-2300°C under He atmosphere and keep it for 1-2 hours for purification.

10. Use of the cathode plate according to claim 1 or the cathode plate obtained by the production process of the cathode plate according to any one of claims 2 to 9 in electrode materials.

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