A wettable cathode and method of making same

Abstract

The application belongs to the technical field of aluminum electrolysis, and particularly relates to a wettable cathode and a preparation method thereof. The prior art mainly uses a single sintering aid or relies on a hot pressing / thermal isostatic pressing process to realize TiB2 densification, and has the problems of high cost or insufficient wettability. In the embodiment of the application, an Al2O3-CaO composite system is used in cooperation with a multi-component sintering aid for the first time, and the wettability and the densification problem are solved simultaneously through liquid phase composition design; the amount of liquid phase is controlled in a specific proportion range to avoid excessive liquid phase erosion of the substrate; and the forming quality is optimized in combination with a dry-wet process, so that a technical breakthrough of pressureless sintering preparation of a high-density wettable cathode is realized, and the production cost is significantly reduced.

Description

Technical Field

[0001] This application belongs to the field of aluminum electrolysis technology, and particularly relates to a wettable cathode and its preparation method. Background Technology

[0002] The continuous advancement of deep energy-saving technology in prebaked carbon anode aluminum electrolysis cells, and the industrial application of vertical electrode structure inert anode aluminum electrolysis cells, both necessitate low-carbon, low-cost TiB2 wettable cathodes. The cathode operating environment in low-aluminum / aluminum-free deep energy-saving technology in prebaked carbon anode electrolysis is similar to that in vertical inert anode aluminum electrolysis technology; neither cathode surface possesses the thick aluminum liquid layer protection of conventional electrolysis cells, leading to increased penetration of sodium and potassium ions into the cathode. When the cathode is carbonaceous or has a high carbon content, the sodium and potassium elements penetrating into the cathode can react with carbon to form intercalation compounds (CmNam), causing the cathode to expand and crack.

[0003] While current hot-pressed TiB2 ceramics can meet the aforementioned operating conditions, their high cost and size limitations prevent industrial application. Using atmospheric / pressureless / cold pressing sintering instead of hot pressing to prepare wettable TiB2 cathodes is a way to reduce costs and address size limitations. However, because TiB2 is difficult to sinter, sintering aids are typically needed to lower the overall sintering temperature. The choice of sintering aid is crucial; excessive introduction may reduce the wettability of the TiB2 cathode or lead to problems such as cathode scaling, expansion cracking, etc., during electrolytic applications.

[0004] In existing technologies, calcium aluminate cement, with its hydration reaction upon contact with water and low melting point, acts as a forming agent in the powder raw material forming stage and as a sintering aid in the material sintering stage, thereby shortening the material preparation cycle, lowering the sintering temperature, and increasing the sintering density of the material. However, commercially available calcium aluminate cement is difficult to control for impurity content, posing potential risks. Another technology uses metal as a sintering aid to lower the sintering temperature. However, because the aluminum produced during electrolysis can alloy with metal, the alloying reaction on the cathode surface makes the molten aluminum viscous, affecting its convergence. Furthermore, the alloying reaction caused by the molten aluminum penetrating into the cathode can generate internal stress, posing a risk of material expansion and cracking.

[0005] In summary, the lack of low-cost technology for preparing low-carbon TiB2 ceramic wettable cathodes remains a technical challenge for the industry. Summary of the Invention

[0006] This application provides a wettable cathode and its preparation method to solve the following technical problem: how to prepare a high-density TiB2 wettable cathode at low cost.

[0007] In a first aspect, embodiments of this application provide a method for preparing a wettable cathode, comprising the following steps: A TiB2 mixed powder is prepared by dry ball milling calcined α-Al2O3 powder, CaO powder, sintering aid, dispersant, and TiB2 powder; wherein the mass ratio of calcined α-Al2O3 powder to CaO powder is (4-1):1, and the total mass of calcined α-Al2O3 powder and CaO powder accounts for 3%-10% of the mass of the TiB2 mixed powder; the sintering aid includes at least one of Fe2O3, NiO, MnO2, TiN, TiO2, CoB2, B, and TiC; the calcined α-Al2O3 powder and CaO powder are directly added for dry ball milling, or the calcined α-Al2O3 powder and CaO powder are premixed and sintered, and the sintered product is crushed into powder and then dry ball milled with the sintering aid, the dispersant, and the TiB2 powder; The TiB2 mixed powder is wet-mixed and granulated with a binder and a dispersion medium to obtain a molded powder material; The shaped powder material is pressed and shaped to obtain a wettable cathode green body; The wettable cathode green blank is densified and sintered under an inert atmosphere to obtain a wettable cathode.

[0008] Optionally, the mass of the sintering aid is 0.5% to 5% of the mass of the TiB2 mixed powder.

[0009] Optionally, the calcined α-Al2O3 powder and the CaO powder can be added directly or separately, or the calcined α-Al2O3 powder and the CaO powder can be mixed in proportion and then pre-sintered, and the pre-sintered product can be crushed into powder before being added.

[0010] Optionally, when added in a pre-sintering manner, the pre-sintering temperature is 1300℃~1400℃, and the particle size of the pre-sintered product after being crushed into powder is 200 mesh~500 mesh.

[0011] Optionally, the dispersant is an active alumina dispersant, and the mass of the dispersant is 0.5% to 1.0% of the mass of the TiB2 mixed powder.

[0012] Optionally, the pressing and molding process employs a hydraulic press or a cold isostatic press; When the compression molding is performed using a hydraulic press, the compression molding pressure is 120MPa to 200MPa, and the holding time is 3min to 5min. When the pressing and molding process uses a cold isostatic press, the pressing and molding pressure is 120MPa to 200MPa, and the holding time is 100s to 200s.

[0013] Optionally, the densification sintering temperature is 1500℃~1700℃, and the holding time is 4h~6h; The inert atmosphere is a 5N high-purity argon atmosphere or a 5N high-purity nitrogen atmosphere.

[0014] Optionally, after obtaining the wettable cathode green blank and before densification sintering, the wettable cathode green blank is placed in an environment with a temperature of 15°C to 25°C and a humidity of 50% to 70% for 20h to 28h.

[0015] Optionally, the purity of the calcined α-Al2O3 powder, the CaO powder, the sintering aid, the dispersant, and the TiB2 powder are all greater than 99.9%, and the particle size is all 200 mesh to 500 mesh.

[0016] Secondly, embodiments of this application provide a wettable cathode, which is prepared by the method described in any one of the first aspects.

[0017] The technical solution provided in this application has the following advantages compared with the prior art: Because TiB2 is a strongly covalent compound with a low self-diffusion coefficient, conventional pressureless sintering is insufficient for densification. While hot pressing can produce high-density products, it suffers from inherent drawbacks such as high cost and size limitations. This is the core technological bottleneck for low-cost preparation of high-density TiB2 wettable cathodes. In existing technologies, calcium aluminate cement functions as both a forming agent and a sintering aid, but the impurity content of commercially available products is uncontrollable, easily introducing harmful components under high-temperature electrolysis. Metallic sintering aids, while lowering the sintering temperature, can alloy with electrolytic aluminum, leading to thickening of the molten aluminum and stress cracking in the cathode, neither of which can meet the long-term stable operation requirements of low-carbon content cathodes.

[0018] This application addresses the aforementioned technical problems by employing a mixture of calcined α-Al₂O₃ powder and CaO powder at a mass ratio of (4-1):1 as an inorganic bonding system, with the total mass of both limited to 3%-10% of the TiB₂ mixed powder mass. Simultaneously, at least one of Fe₂O₃, NiO, MnO₂, TiN, TiO₂, CoB₂, B, and TiC is introduced as a sintering aid, which, together with a dispersant, is used to dry ball-mill the TiB₂ powder. This process generates a calcium aluminate liquid phase through the in-situ reaction of calcined α-Al₂O₃ powder and CaO powder at high temperature. The melting point of this liquid phase is controllable, and the impurity content is directly determined by the purity of the raw materials, avoiding the need for commercially available calcium aluminate. The uncontrollable risks of cement impurities can be addressed by: first, pre-mixing calcined α-Al₂O₃ powder and CaO powder in a muffle furnace for sintering, allowing them to react beforehand to form calcium aluminate compounds. Then, the mixture is crushed into powder and added back into the furnace. This utilizes the chemical reaction between the pre-generated calcium aluminate powder and water to function as a forming agent in the subsequent wet mixing and granulation stage, while avoiding the compositional fluctuations and process instability caused by CaO's hygroscopic nature, thus ensuring the accuracy of the raw material stoichiometry. Furthermore, regardless of whether it is generated in situ or through pre-mixing and sintering, the calcium aluminate liquid phase is distributed at the TiB₂ grain boundaries during sintering, wetting the TiB₂ particle surface and filling pores, promoting particle rearrangement. Simultaneously, limiting the ratio of Al2O3 to CaO ensures a balance between the chemical stability and high-temperature strength of the generated liquid phase, avoiding a decrease in corrosion resistance due to excessive CaO or insufficient density due to excessive Al2O3. This maintains the electrolytic life of the cathode while ensuring the quality of the primary aluminum. Furthermore, the oxide components in the selected sintering aid can form a low-melting-point eutectic phase or solid solution-strengthened grain boundaries on the surface of TiB2 particles, while the nitride, carbide, and boride components reduce the sintering activation energy through lattice defect induction or surface activation mechanisms. This synergistically lowers the overall densification sintering temperature, enabling the acquisition of high-density TiB2-based materials under atmospheric / pressureless / cold-pressing sintering conditions. This makes the process possible; furthermore, the aforementioned inorganic bonding system and sintering aid do not contain any metallic elements, and will not undergo alloying reactions in the electrolytic aluminum liquid environment, thus avoiding the risk of aluminum liquid thickening and internal stress cracking of the cathode. At the same time, the calcium aluminate liquid phase will not be reduced by the aluminum liquid when it comes into contact with the aluminum liquid under electrolytic conditions, which will not cause an increase in the impurity content of the aluminum product, and it has good chemical compatibility with the TiB2 matrix, so it will not deteriorate the wettability of the cathode to the aluminum liquid; furthermore, the aforementioned TiB2 mixed powder is wet-mixed and granulated with binder and dispersion medium to obtain a molding powder material with suitable flowability, thereby ensuring that the powder fills the mold uniformly during subsequent pressing and molding, and obtaining a uniformly structured wettable cathode green body.Furthermore, the green blank is densified and sintered under an inert atmosphere to prevent high-temperature oxidation of TiB2, ensuring that the calcium aluminate liquid phase and sintering aid fully exert their densification effect within a set temperature window. This ultimately yields a high-density, low-carbon-content TiB2 wettable cathode whose size is not limited by the hot-pressing mold, achieving the technical goal of low-cost preparation of a high-density TiB2 wettable cathode. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within the range. For example, a range description of "1 to 6" or "1~6" covers all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms used herein, including "comprising" and other terms indicating "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or steps and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist alone or simultaneously; expressions such as "at least one," "more than one," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships involved in the text, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used in this text can all be obtained through commercial purchase or prepared by existing methods.

[0021] In a first aspect, embodiments of this application provide a method for preparing a wettable cathode, comprising the following steps: A TiB2 mixed powder is prepared by dry ball milling calcined α-Al2O3 powder, CaO powder, sintering aid, dispersant, and TiB2 powder; wherein the mass ratio of calcined α-Al2O3 powder to CaO powder is (4-1):1, and the total mass of calcined α-Al2O3 powder and CaO powder accounts for 3%-10% of the mass of the TiB2 mixed powder; the sintering aid includes at least one of Fe2O3, NiO, MnO2, TiN, TiO2, CoB2, B, and TiC; the calcined α-Al2O3 powder and CaO powder are directly added for dry ball milling, or the calcined α-Al2O3 powder and CaO powder are premixed and sintered, and the sintered product is crushed into powder and then dry ball milled with the sintering aid, the dispersant, and the TiB2 powder; The TiB2 mixed powder is wet-mixed and granulated with a binder and a dispersion medium to obtain a molded powder material; The shaped powder material is pressed and shaped to obtain a wettable cathode green body; The wettable cathode green blank is densified and sintered under an inert atmosphere to obtain a wettable cathode.

[0022] Calcinated α-Al₂O₃ powder: refers to α-crystalline alumina powder that has undergone high-temperature calcination. In this application embodiment, this α-Al₂O₃ powder serves as one of the precursors for the liquid-phase formation of calcium aluminate. Sintering aid: refers to additives that promote the densification and sintering of TiB₂ powder. Molding powder material: refers to granular material with good flowability and formability formed by wet mixing and granulation of TiB₂ mixed powder with a binder and dispersion medium. Densification sintering: refers to a heat treatment process conducted in the temperature range of 1500℃ to 1700℃ to achieve high density in a wettable cathode green body, performed under an inert atmosphere.

[0023] The mass ratio of calcined α-Al2O3 powder to CaO powder includes, but is not limited to, 1:1, 2:1, 3:1, 4:1, etc.; the total mass of calcined α-Al2O3 powder and CaO powder accounts for, but is not limited to, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc. of the TiB2 mixed powder.

[0024] In some embodiments, the mass of the sintering aid is 0.5% to 5% of the mass of the TiB2 mixed powder.

[0025] Because a low content of sintering aid is insufficient to effectively promote TiB2 densification, while a high content introduces excessive heterogeneous phases, leading to alloying reactions or scaling of the cathode during electrolysis, this application limits the mass of the sintering aid to 0.5%–5% of the TiB2 mixed powder mass. Within this content range, the sintering aid forms an appropriate amount of active or low-melting-point phase, effectively promoting TiB2 grain boundary diffusion and mass transport. This achieves high-density sintering of TiB2 without excessive introduction of heterogeneous phases, resulting in a wettable cathode with both high density and good electrolytic stability. Furthermore, this allows for the low-cost preparation of a high-density, wettable TiB2 cathode. The mass ratio of the sintering aid to the TiB2 mixed powder mass includes, but is not limited to, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%.

[0026] In some embodiments, the calcined α-Al2O3 powder and the CaO powder are added directly and separately, or the calcined α-Al2O3 powder and the CaO powder are first mixed in proportion and then pre-sintered, and the pre-sintered product is crushed into powder before being added.

[0027] Since the direct addition of calcined α-Al2O3 powder and CaO powder requires in-situ reaction during the sintering stage to generate a calcium aluminate liquid phase, the reaction process is difficult to control. Pre-sintering allows the two to react in advance to form a stable calcium aluminate phase. In this application, the addition method of calcined α-Al2O3 powder and CaO powder is set to direct addition alone, or to first mix calcined α-Al2O3 powder and CaO powder in proportion, then pre-sinter, and finally crush the pre-sintered product into powder before adding it. Thus, the direct addition method simplifies the process flow, while the pre-sintering method ensures that the calcium aluminate phase is fully formed before addition, and the liquid phase composition is more stable and controllable. Therefore, both addition methods can achieve effective generation and distribution of the calcium aluminate liquid phase, promote the densification of TiB2 and endow it with wettable properties, thereby preparing a high-density TiB2 wettable cathode at low cost.

[0028] In some embodiments, when added in a pre-sintering manner, the pre-sintering temperature is 1300℃~1400℃, and the particle size of the pre-sintered product after being crushed into powder is 200 mesh~500 mesh.

[0029] Because the reaction between calcined α-Al2O3 powder and CaO powder is incomplete when the pre-sintering temperature is too low, and the calcium aluminate phase is over-sintered and difficult to break when the temperature is too high, the embodiments of this application limit the pre-sintering temperature to 1300℃~1400℃ and limit the particle size of the pre-sintered product after being crushed into powder to 200 mesh~500 mesh. Thus, the pre-sintering temperature ensures that the calcined α-Al2O3 powder and CaO powder react fully to generate the calcium aluminate phase, and the particle size range ensures that the pre-sintered product has dispersibility and reactivity that match that of TiB2 powder. Furthermore, the pre-sintered product is uniformly dispersed in the subsequent dry ball milling and forms a uniform liquid phase distribution in the densification sintering, promoting the uniform densification of TiB2. Thus, a high-density TiB2 wettable cathode can be prepared at low cost. The pre-sintering temperature includes, but is not limited to, 1300℃, 1320℃, 1340℃, 1360℃, 1380℃, 1400℃, etc.; the particle size of the pre-sintered product after being crushed into powder includes, but is not limited to, 200 mesh, 250 mesh, 300 mesh, 350 mesh, 400 mesh, 450 mesh, 500 mesh, etc.

[0030] In some embodiments, the dispersant is an active alumina dispersant, and the mass of the dispersant is 0.5% to 1.0% of the mass of the TiB2 mixed powder.

[0031] Because TiB2 powder has high surface energy and is prone to hard agglomeration, leading to uneven mixing and molding defects, this application specifies that the dispersant is an activated alumina dispersant, and the mass of the dispersant is limited to 0.5% to 1.0% of the mass of the TiB2 mixed powder. Thus, the activated alumina dispersant disperses TiB2 particles through surface adsorption and electrostatic repulsion. This mass range ensures a balance between dispersion effect and cost. Consequently, the components in the TiB2 mixed powder are uniformly dispersed. After wet mixing and granulation, a well-flowable molding powder material is formed. After pressing and molding, a uniformly dense wettable cathode green body is obtained. Thus, a high-density TiB2 wettable cathode can be prepared at low cost.

[0032] In some embodiments, the binder is a polyvinyl alcohol solution, and the dispersion medium is deionized water.

[0033] In some embodiments, the compression molding is performed using a hydraulic press or a cold isostatic press; When the compression molding is performed using a hydraulic press, the compression molding pressure is 120MPa to 200MPa, and the holding time is 3min to 5min. When the pressing and molding process uses a cold isostatic press, the pressing and molding pressure is 120MPa to 200MPa, and the holding time is 100s to 200s.

[0034] Since the forming mechanisms of hydraulic presses and cold isostatic presses are different, this application specifies that the pressing method is either a hydraulic press or a cold isostatic press. For hydraulic presses, the pressing pressure is limited to 120MPa to 200MPa and the holding time is limited to 3min to 5min. For cold isostatic presses, the pressing pressure is limited to 120MPa to 200MPa and the holding time is limited to 100s to 200s. Thus, hydraulic presses achieve rapid forming through unidirectional or bidirectional pressure application, and the holding time ensures sufficient stress transfer. Cold isostatic presses achieve uniform density distribution through isotropic pressure application, and the holding time ensures balanced pressure penetration. Consequently, both forming methods enable the formed powder material to form a wettable cathode green body with a certain strength and uniform density, thereby enabling the low-cost preparation of high-density TiB2 wettable cathodes. The pressure for hydraulic pressing includes, but is not limited to, 120MPa, 130MPa, 140MPa, 150MPa, 160MPa, 170MPa, 180MPa, 190MPa, and 200MPa; the holding time for hydraulic pressing includes, but is not limited to, 3min, 3.5min, 4min, 4.5min, and 5min; the pressure for cold isostatic pressing includes, but is not limited to, 120MPa, 130MPa, 140MPa, 150MPa, 160MPa, 170MPa, 180MPa, 190MPa, and 200MPa; the holding time for cold isostatic pressing includes, but is not limited to, 100s, 120s, 140s, 160s, 180s, and 200s.

[0035] In some embodiments, the densification sintering temperature is 1500℃~1700℃, and the holding time is 4h~6h; The inert atmosphere is a 5N high-purity argon atmosphere or a 5N high-purity nitrogen atmosphere.

[0036] Because densification is incomplete when the sintering temperature is too low, abnormal grain growth occurs when the temperature is too high, insufficient reaction occurs when the holding time is too short, and increased energy consumption occurs when the holding time is too long, this application limits the densification sintering temperature to 1500℃~1700℃, the holding time to 4h~6h, and the inert atmosphere to 5N high-purity argon or 5N high-purity nitrogen. Thus, the sintering temperature and holding time ensure that the calcium aluminate liquid phase is fully generated and promotes the densification of TiB2. The inert atmosphere effectively isolates oxygen to prevent TiB2 oxidation. Therefore, the wettable cathode green blank completes the densification transformation under the controlled thermal regime and protective atmosphere, forming a high-density, high-purity wettable cathode. Thus, a high-density TiB2 wettable cathode can be prepared at low cost. The densification sintering temperature includes, but is not limited to, 1500℃, 1550℃, 1600℃, 1650℃, 1700℃, etc.; the holding time includes, but is not limited to, 4h, 4.5h, 5h, 5.5h, 6h, etc.

[0037] In some embodiments, after obtaining the wettable cathode green blank and before densification sintering, the wettable cathode green blank is placed in an environment with a temperature of 15°C to 25°C and a humidity of 50% to 70% for 20h to 28h.

[0038] Because the wettable cathode green blank contains binder and dispersion medium, direct sintering can easily lead to cracking or porosity defects. In this embodiment, after obtaining the wettable cathode green blank and before densification sintering, the green blank is placed in an environment with a temperature of 15℃~25℃ and a humidity of 50%~70% for 20h~28h. This temperature and humidity environment allows the binder to dry slowly and maintains the stability of the green blank structure. This placement time ensures sufficient evaporation of moisture and release of internal stress. Therefore, the wettable cathode green blank obtains sufficient dry strength and structural integrity before densification sintering, avoiding sintering cracking. Thus, a high-density TiB2 wettable cathode can be prepared at low cost. The temperature of the placement environment includes, but is not limited to, 15℃, 16℃, 18℃, 20℃, 22℃, 24℃, and 25℃; the humidity includes, but is not limited to, 50%, 55%, 60%, 65%, and 70%; and the placement time includes, but is not limited to, 20h, 22h, 24h, 26h, and 28h.

[0039] In some embodiments, the purity of the calcined α-Al2O3 powder, the CaO powder, the sintering aid, the dispersant, and the TiB2 powder is all greater than 99.9%, and the particle size is all 200 mesh to 500 mesh.

[0040] Because insufficient purity of raw materials can introduce impurities that affect electrochemical performance, and excessively coarse particle size can reduce sintering activity and density, the embodiments of this application limit the purity of calcined α-Al2O3 powder, CaO powder, sintering aid, dispersant, and TiB2 powder to greater than 99.9%, and the particle size to 200-500 mesh. This high purity ensures the chemical stability and conductivity of the wettable cathode, and this particle size range ensures that each component has matched sintering activity and dispersibility. Furthermore, the TiB2 mixed powder achieves uniform densification and a pure phase composition during the densification sintering process, thereby enabling the low-cost preparation of a high-density TiB2 wettable cathode. The particle sizes of the calcined α-Al2O3 powder, CaO powder, sintering aid, dispersant, and TiB2 powder include, but are not limited to, 200 mesh, 250 mesh, 300 mesh, 350 mesh, 400 mesh, 450 mesh, and 500 mesh.

[0041] Secondly, embodiments of this application provide a wettable cathode, which is prepared by the method described in any one of the first aspects.

[0042] In this application embodiment, the product prepared by the method described in any one of the first aspects is defined as a wettable cathode. Thus, the wettable cathode inherits all the technical features and beneficial effects of the corresponding preparation method, and has high density and good wettability. In this way, it meets the demand of the aluminum electrolysis industry for low-cost, high-performance cathode materials, thereby preparing a high-density TiB2 wettable cathode at low cost.

[0043] In some embodiments, the wettable cathode has a density of 95.6% to 99.2% and a sintering shrinkage rate of 10.4% to 14.7%.

[0044] In some embodiments, the wettable cathode is in a KF-NaF-AlF3-Al2O3 electrolyte system, at 820°C with a DC current of 20A and a flow rate of 0.5A / cm. 2 After 24 hours of operation, the cathode current density remained intact and exhibited good wettability with molten aluminum.

[0045] In some embodiments, the wettable cathode has a width of 40cm to 50cm, a height of 55cm to 65cm, and a thickness of 1.0cm to 2.0cm.

[0046] In some embodiments, the wettable cathode is used in low-aluminum / aluminum-free deep energy-saving processes in vertical electrode structure inert anode aluminum electrolytic cells or prebaked carbon anode aluminum electrolytic cells.

[0047] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0048] I. Implementation Examples Example 1 1.5 wt.% calcined α-Al₂O₃ powder, 1.5 wt.% CaO powder, 0.5 wt.% TiO₂ sintering aid, and 0.5 wt.% activated alumina dispersant were dry-ball-milled with TiB₂ powder to obtain TiB₂ mixed powder. The mass ratio of calcined α-Al₂O₃ powder to CaO powder was 1:1, and the total mass of calcined α-Al₂O₃ powder and CaO powder accounted for 3% of the mass of the TiB₂ mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 200 MPa for 30 seconds to obtain a wettable cathode green body. The wettable cathode green blank was densified and sintered at 1700°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0049] Analysis revealed that the wettable cathode had a density of 94.6% and a sintering shrinkage rate of 10.1%. The wettable cathode was vertically installed in an inert anode aluminum electrolytic cell, and in a KF-NaF-AlF3-Al2O3 electrolyte system, it was subjected to an electrolysis at 820°C with a DC current of 20A and a current of 0.5A / cm². 2 After 24 hours of operation at the cathode current density, the wettable cathode remained intact and exhibited good wettability with molten aluminum.

[0050] Example 2 5 wt.% calcined α-Al₂O₃ powder, 5 wt.% CaO powder, 2 wt.% NiO sintering aid, and 0.5 wt.% activated alumina dispersant were dry-ball-milled with TiB₂ powder to obtain TiB₂ mixed powder. The mass ratio of calcined α-Al₂O₃ powder to CaO powder was 1:1, and the total mass of calcined α-Al₂O₃ powder and CaO powder accounted for 10% of the mass of the TiB₂ mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 150 MPa for 5 seconds to obtain a wettable cathode green body. The wettable cathode green blank was densified and sintered at 1500°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0051] According to the test and analysis, the density of the wettable cathode is 98.5% and the sintering shrinkage rate is 14.2%. The wettable cathode was vertically installed in an inert anode aluminum electrolytic cell and operated at 820°C with a DC current of 20A and a cathode current density of 0.5A / cm2 for 24 hours in a KF-NaF-AlF3-Al2O3 electrolyte system. The wettable cathode remained intact and had good wettability with molten aluminum.

[0052] Example 3 1.6 wt.% calcined α-Al₂O₃ powder, 3 wt.% CaO powder, 3 wt.% TiN sintering aid, and 1 wt.% activated alumina dispersant were dry-ball-milled with TiB₂ powder to obtain TiB₂ mixed powder. The mass ratio of calcined α-Al₂O₃ powder to CaO powder was approximately 1:1.875, and the total mass of calcined α-Al₂O₃ powder and CaO powder accounted for 4.6% of the mass of the TiB₂ mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 200 MPa for 30 seconds to obtain a wettable cathode green body. The wettable cathode green blank was densified and sintered at 1650°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0053] Analysis showed that the wettable cathode had a density of 97% and a sintering shrinkage rate of 13.5%. When the wettable cathode was vertically installed in an inert anode aluminum electrolytic cell and operated for 24 hours at 820°C with a DC current of 20A and a cathode current density of 0.5A / cm² in a KF-NaF-AlF3-Al2O3 electrolyte system, the wettable cathode remained intact and exhibited good wettability with molten aluminum.

[0054] Example 4 TiB2 mixed powder was prepared by dry ball milling 2.8 wt.% calcined α-Al2O3 powder, 5.2 wt.% CaO powder, 3 wt.% CoB2 sintering aid, 2 wt.% B sintering aid, and 1 wt.% activated alumina dispersant with TiB2 powder to obtain TiB2 mixed powder. The mass ratio of calcined α-Al2O3 powder to CaO powder was approximately 1:1.857, and the total mass of calcined α-Al2O3 powder and CaO powder accounted for 8% of the mass of the TiB2 mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 200 MPa for 30 seconds to obtain a wettable cathode green body. The wettable cathode green blank was densified and sintered at 1650°C under a 5N high-purity nitrogen atmosphere to obtain a wettable cathode.

[0055] Analysis revealed that the wettable cathode has a density of 99.2% and a sintering shrinkage rate of 14.7%. When the wettable cathode was vertically installed in an inert anode aluminum electrolytic cell and operated for 24 hours at 820°C with a DC current of 20A and a cathode current density of 0.5A / cm² in a KF-NaF-AlF3-Al2O3 electrolyte system, the wettable cathode remained intact and exhibited good wettability with molten aluminum.

[0056] Example 5 First, CaO powder and Al2O3 powder are mixed evenly in a mixer at a mass ratio of 65:35. After being taken out, they are pre-sintered in a muffle furnace at 1300℃ for 2 hours. After being taken out, the pre-sintered mixture powder is obtained. The pre-sintered mixture powder is then ground into fine powder for later use. 8 wt.% of the pre-sintered mixture powder, 3 wt.% of CoB2 sintering aid, 2 wt.% of B sintering aid, and 1 wt.% of activated alumina dispersant were dry-ball-milled with TiB2 powder to obtain TiB2 mixed powder. The mass ratio of calcined α-Al2O3 powder to CaO powder in the pre-sintered mixture powder was approximately 1:1.857, and the mass of the pre-sintered mixture powder accounted for 8% of the mass of the TiB2 mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed into a mold and pressed in a hydraulic press at a pressure of 120 MPa for 3 minutes to obtain a wettable cathode green blank. The wettable cathode green blank was placed in an environment with a temperature of 20°C and a humidity of 60% for 24 hours; The wettable cathode green blank was densified and sintered at 1650°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0057] Analysis revealed that the wettable cathode has a density of 99.2% and a sintering shrinkage rate of 14.7%. When the wettable cathode was vertically installed in an inert anode aluminum electrolytic cell and operated for 24 hours at 820°C with a DC current of 20A and a cathode current density of 0.5A / cm² in a KF-NaF-AlF3-Al2O3 electrolyte system, the wettable cathode remained intact and exhibited good wettability with molten aluminum.

[0058] Example 6 2 wt.% calcined α-Al₂O₃ powder, 2 wt.% CaO powder, 1 wt.% Fe₂O₃ sintering aid, and 0.8 wt.% activated alumina dispersant were dry-ball-milled with TiB₂ powder to obtain TiB₂ mixed powder. The mass ratio of calcined α-Al₂O₃ powder to CaO powder was 1:1, and the total mass of calcined α-Al₂O₃ powder and CaO powder accounted for 4% of the mass of the TiB₂ mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a hydraulic press at a pressure of 150 MPa for 4 minutes to obtain a wettable cathode green blank. The wettable cathode green blank was densified and sintered at 1600°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0059] Analysis revealed that the wettable cathode has a density of 96.8% and a sintering shrinkage rate of 12.3%. When the wettable cathode was vertically installed in an inert anode aluminum electrolytic cell and operated for 24 hours at 820°C with a DC current of 20A and a cathode current density of 0.5A / cm² in a KF-NaF-AlF3-Al2O3 electrolyte system, the wettable cathode remained intact and exhibited good wettability with molten aluminum.

[0060] Example 7 3 wt.% calcined α-Al2O3 powder, 2 wt.% CaO powder, 2.5 wt.% MnO2 sintering aid, and 0.6 wt.% activated alumina dispersant were dry-ball-milled with TiB2 powder to obtain TiB2 mixed powder. The mass ratio of calcined α-Al2O3 powder to CaO powder was 1.5:1, and the total mass of calcined α-Al2O3 powder and CaO powder accounted for 5% of the mass of the TiB2 mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 180 MPa for 150 s to obtain a wettable cathode green body. The wettable cathode green blank was densified and sintered at 1550°C under a 5N high-purity nitrogen atmosphere to obtain a wettable cathode.

[0061] According to the test and analysis, the density of the wettable cathode is 97.5% and the sintering shrinkage rate is 13.1%. The wettable cathode was vertically installed in an inert anode aluminum electrolytic cell and operated for 24 hours at 820°C with a DC current of 20A and a cathode current density of 0.5A / cm2 in a KF-NaF-AlF3-Al2O3 electrolyte system. The wettable cathode remained intact and had good wettability with molten aluminum.

[0062] Example 8 4 wt.% calcined α-Al2O3 powder, 4 wt.% CaO powder, 4 wt.% TiC sintering aid, and 0.9 wt.% activated alumina dispersant were dry-ball-milled with TiB2 powder to obtain TiB2 mixed powder. The mass ratio of calcined α-Al2O3 powder to CaO powder was 1:1, and the total mass of calcined α-Al2O3 powder and CaO powder accounted for 8% of the mass of the TiB2 mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 200 MPa for 200 s to obtain a wettable cathode green body. The wettable cathode green blank was placed in an environment with a temperature of 18°C ​​and a humidity of 55% for 22 hours. The wettable cathode green blank was densified and sintered at 1620°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0063] According to the test and analysis, the density of the wettable cathode is 98.8% and the sintering shrinkage rate is 14.1%. The wettable cathode was vertically installed in an inert anode aluminum electrolytic cell and operated at 820°C with a DC current of 20A and a cathode current density of 0.5A / cm2 for 24 hours in a KF-NaF-AlF3-Al2O3 electrolyte system. The wettable cathode remained intact and had good wettability with molten aluminum.

[0064] II. Comparative Example Comparative Example 1 1 wt.% calcined α-Al2O3 powder, 1 wt.% CaO powder, and 0.5 wt.% activated alumina dispersant were dry-ball-milled with TiB2 powder to obtain TiB2 mixed powder. The mass ratio of calcined α-Al2O3 powder to CaO powder was 1:1, and the total mass of calcined α-Al2O3 powder and CaO powder accounted for 2% of the mass of the TiB2 mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 200 MPa for 30 seconds to obtain a wettable cathode green body. The wettable cathode green blank was densified and sintered at 1700°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0065] According to the test and analysis, the density of the wettable cathode is 91.2% and the sintering shrinkage rate is 5.6%. When the wettable cathode was vertically installed in the inert anode aluminum electrolytic cell, it could not be effectively sintered after multiple pressing and molding processes, and the sample production could not be completed.

[0066] Comparative Example 2 7.5 wt.% calcined α-Al₂O₃ powder, 7.5 wt.% CaO powder, 10 wt.% CuO sintering aid, and 2 wt.% activated alumina dispersant were dry-ball-milled with TiB₂ powder to obtain TiB₂ mixed powder. The mass ratio of calcined α-Al₂O₃ powder to CaO powder was 1:1, and the total mass of calcined α-Al₂O₃ powder and CaO powder accounted for 15% of the mass of the TiB₂ mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 200 MPa for 30 seconds to obtain a wettable cathode green body. The wettable cathode green blank was densified and sintered at 1500°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0067] Analysis revealed that the wettable cathode had a density of 96.8% and a sintering shrinkage rate of 13.8%. When the wettable cathode was vertically installed in an inert anode aluminum electrolytic cell and operated for 24 hours at 820°C with a DC current of 20A and a cathode current density of 0.5A / cm² in a KF-NaF-AlF3-Al2O3 electrolyte system, the wettable cathode expanded and cracked.

[0068] Comparative Example 3 13.5 wt.% calcined α-Al₂O₃ powder, 1.5 wt.% CaO powder, 10 wt.% CuO sintering aid, and 2 wt.% activated alumina dispersant were dry-ball-milled with TiB₂ powder to obtain TiB₂ mixed powder. The mass ratio of calcined α-Al₂O₃ powder to CaO powder was 9:1, and the total mass of calcined α-Al₂O₃ powder and CaO powder accounted for 15% of the mass of the TiB₂ mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 200 MPa for 30 seconds to obtain a wettable cathode green body. The wettable cathode green blank was densified and sintered at 1500°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0069] According to the test and analysis, the density of the wettable cathode is 85.8% and the sintering shrinkage rate is 5.2%.

[0070] Comparative Example 4 6 wt.% calcined α-Al2O3 powder, 9 wt.% CaO powder, 10 wt.% CuO sintering aid, and 2 wt.% activated alumina dispersant were dry-ball-milled with TiB2 powder to obtain TiB2 mixed powder. The mass ratio of calcined α-Al2O3 powder to CaO powder was 2:3, and the total mass of calcined α-Al2O3 powder and CaO powder accounted for 15% of the mass of the TiB2 mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 200 MPa for 30 seconds to obtain a wettable cathode green body. The wettable cathode green blank was densified and sintered at 1500°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0071] According to the test and analysis, the density of the wettable cathode is 82.3% and the sintering shrinkage rate is 4.6%.

[0072] Comparative Example 5 1.5 wt.% calcined α-Al₂O₃ powder, 1.5 wt.% CaO powder, 0.3 wt.% TiO₂ sintering aid, and 0.5 wt.% activated alumina dispersant were dry-ball-milled with TiB₂ powder to obtain TiB₂ mixed powder. The mass ratio of calcined α-Al₂O₃ powder to CaO powder was 1:1, and the total mass of calcined α-Al₂O₃ powder and CaO powder accounted for 3% of the mass of the TiB₂ mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 200 MPa for 30 seconds to obtain a wettable cathode green body. The wettable cathode green blank was densified and sintered at 1700°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0073] According to the test and analysis, the density of the wettable cathode is 90.5% and the sintering shrinkage rate is 6.8%. When the wettable cathode was vertically installed in the inert anode aluminum electrolytic cell, it could not be effectively sintered after multiple pressing and molding processes, and the sample production could not be completed.

[0074] Comparative Example 6 1.5 wt.% calcined α-Al₂O₃ powder, 1.5 wt.% CaO powder, 6 wt.% NiO sintering aid, and 0.5 wt.% activated alumina dispersant were dry-ball-milled with TiB₂ powder to obtain TiB₂ mixed powder. The mass ratio of calcined α-Al₂O₃ powder to CaO powder was 1:1, and the total mass of calcined α-Al₂O₃ powder and CaO powder accounted for 3% of the mass of the TiB₂ mixed powder. The TiB2 mixed powder was wet-mixed and granulated with 1.5 wt.% PVA binder and an appropriate amount of deionized water to obtain a molded powder material. The shaped powder material is placed in a mold and pressed in a cold isostatic press at a pressing pressure of 200 MPa for 30 seconds to obtain a wettable cathode green body. The wettable cathode green blank was densified and sintered at 1500°C under a 5N high-purity argon atmosphere to obtain a wettable cathode.

[0075] Analysis revealed that the wettable cathode had a density of 95.2% and a sintering shrinkage rate of 11.5%. When the wettable cathode was vertically installed in an inert anode aluminum electrolytic cell and operated for 24 hours at 820°C with a DC current of 20A and a cathode current density of 0.5A / cm² in a KF-NaF-AlF3-Al2O3 electrolyte system, scaling appeared on the surface of the wettable cathode.

[0076] Experimental methods for evaluating results: Density determination method: The density of the wettable cathode was determined using the Archimedes water displacement method. The specific steps were as follows: The surface of the sintered wettable cathode sample was cleaned and dried to constant weight; the dry weight of the wettable cathode sample in air was measured. The wettable cathode sample was then immersed in deionized water and boiled to remove air bubbles. After cooling, the suspended weight of the wettable cathode sample in water was measured. The wettable cathode sample was removed, its surface moisture was wiped dry, and its wet weight was measured. The density of the wettable cathode was calculated using the formula: Density = (Dry weight × Density of water) / (Wet weight - Suspended weight) / Theoretical density × 100%, where the theoretical density of TiB2 was taken as 4.52 g / cm³.

[0077] Method for determining sintering shrinkage rate: Measure the dimensions of the wettable cathode green after pressing and molding, measure the dimensions of the wettable cathode after densification and sintering, and calculate the sintering shrinkage rate of the wettable cathode according to the formula: Sintering shrinkage rate = (green size - sintered size) / green size × 100%.

[0078] Electrolysis performance testing method: The wettable cathode was processed into a block sample with a width of 45cm × height of 60cm × thickness of 1.6cm, and vertically installed in an inert anode aluminum electrolytic cell, in conjunction with two inert anodes; in a KF-NaF-AlF3-Al2O3 electrolyte system, the electrolysis temperature was controlled at 820℃, a DC current of 20A was applied, and the cathode current density was controlled at 0.5A / cm³. 2 The system was run continuously for 24 hours. After the operation was completed, the integrity of the wettable cathode was observed, the wetting performance of the wettable cathode with the molten aluminum was tested, and the condition of the wettable cathode, whether it was intact, whether it expanded and cracked, whether it formed scale, and its wetting state with the molten aluminum were recorded.

[0079] Table 1. Effect data of each embodiment and comparative example.

[0080] As shown in Table 1, the technological advancements of this application's technical solution include: Comparative Example 1 failed to complete the sample preparation because no sintering aid was added and the total mass of calcined α-Al2O3 powder and CaO powder accounted for only 2% of the mass of TiB2 mixed powder, the density was only 91.2%, the sintering shrinkage rate was only 5.6%, and multiple pressing moldings failed to achieve effective sintering.

[0081] Comparative Example 2 showed that the total mass of calcined α-Al2O3 powder and CaO powder accounted for 15% of the mass of TiB2 mixed powder, and the mass of CuO sintering aid reached 10%. The density was 96.8%, the sintering shrinkage rate was 13.8%, and the cathode expanded and cracked after 24 hours of electrolysis.

[0082] Comparative Example 3 had a density of only 85.8% and a sintering shrinkage rate of only 5.2% because the mass ratio of calcined α-Al2O3 powder to CaO powder was 9:1, which exceeded the range of (4~1):1.

[0083] Comparative Example 4 had a density of only 82.3% and a sintering shrinkage rate of only 4.6% because the mass ratio of calcined α-Al2O3 powder to CaO powder was 2:3, which exceeded the range of (4~1):1.

[0084] Comparative Example 5 had a TiO2 sintering aid content of only 0.3%, which is lower than the range of 0.5% to 5%. As a result, the density was only 90.5%, the sintering shrinkage rate was only 6.8%, and the sample could not be effectively sintered after multiple pressing moldings.

[0085] Comparative Example 6 had a NiO sintering aid mass of 6%, exceeding the range of 0.5% to 5%, resulting in a density of 95.2%, a sintering shrinkage rate of 11.5%, and the appearance of scale on the cathode surface after 24 hours of electrolysis.

[0086] This application's technical solution achieves a precise balance between liquid phase generation and sintering aid activity by strictly limiting the mass ratio of calcined α-Al2O3 powder to CaO powder to (4-1):1 and the total mass percentage to 3%-10%, and strictly limiting the mass of sintering aid to 0.5%-5%. This avoids incomplete densification due to insufficient liquid phase, structural deterioration due to excessive liquid phase, low sintering activity due to insufficient sintering aid, and electrolytic failure due to excessive sintering aid. By replacing hot pressing with cold pressing sintering, a wettable cathode with a density of 95.6%-99.2%, a sintering shrinkage rate of 10.4%-14.7%, and excellent electrolytic performance is obtained. This significantly reduces the preparation cost of TiB2 wettable cathodes and solves the size limitation problem. Simultaneously, it overcomes the technical defects of existing technologies, such as densification failure, electrolytic expansion cracking, or scaling caused by improper component ratios, demonstrating significant technological advancement.

[0087] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a wettable cathode, characterized in that, Includes the following steps: A TiB2 mixed powder is prepared by dry ball milling calcined α-Al2O3 powder, CaO powder, sintering aid, dispersant, and TiB2 powder; wherein the mass ratio of calcined α-Al2O3 powder to CaO powder is (4-1):1, and the total mass of calcined α-Al2O3 powder and CaO powder accounts for 3%-10% of the mass of the TiB2 mixed powder; the sintering aid includes at least one of Fe2O3, NiO, MnO2, TiN, TiO2, CoB2, B, and TiC; the calcined α-Al2O3 powder and CaO powder are directly added for dry ball milling, or the calcined α-Al2O3 powder and CaO powder are premixed and sintered, and the sintered product is crushed into powder before being dry ball milled with the sintering aid, the dispersant, and the TiB2 powder; The TiB2 mixed powder is wet-mixed and granulated with a binder and a dispersion medium to obtain a molded powder material; The shaped powder material is pressed and shaped to obtain a wettable cathode green body; The wettable cathode green blank is densified and sintered under an inert atmosphere to obtain a wettable cathode.

2. The method for preparing a wettable cathode according to claim 1, characterized in that, The mass of the sintering aid is 0.5% to 5% of the mass of the TiB2 mixed powder.

3. The method for preparing a wettable cathode according to claim 2, characterized in that, The calcined α-Al2O3 powder and the CaO powder are added either directly or separately, or the calcined α-Al2O3 powder and the CaO powder are first mixed in a certain proportion and then pre-sintered, and the pre-sintered product is crushed into powder before being added.

4. The method for preparing a wettable cathode according to claim 3, characterized in that, When added in a pre-sintering manner, the pre-sintering temperature is 1300℃~1400℃, and the particle size of the pre-sintered product after being crushed into powder is 200 mesh~500 mesh.

5. The method for preparing a wettable cathode according to claim 1, characterized in that, The dispersant is an active alumina dispersant, and the mass of the dispersant is 0.5% to 1.0% of the mass of the TiB2 mixed powder.

6. The method for preparing a wettable cathode according to claim 1, characterized in that, The pressing and molding process uses a hydraulic press or a cold isostatic press. When the compression molding is performed using a hydraulic press, the compression molding pressure is 120MPa to 200MPa, and the holding time is 3min to 5min. When the pressing and molding process uses a cold isostatic press, the pressing and molding pressure is 120MPa to 200MPa, and the holding time is 100s to 200s.

7. The method for preparing a wettable cathode according to claim 1, characterized in that, The densification sintering temperature is 1500℃~1700℃, and the holding time is 4h~6h; The inert atmosphere is a 5N high-purity argon atmosphere or a 5N high-purity nitrogen atmosphere.

8. The method for preparing a wettable cathode according to claim 11, characterized in that, After obtaining the wettable cathode green blank and before densification sintering, the wettable cathode green blank is placed in an environment with a temperature of 15℃~25℃ and a humidity of 50%~70% for 20h~28h.

9. The method for preparing a wettable cathode according to claim 1, characterized in that, The purity of the calcined α-Al2O3 powder, the CaO powder, the sintering aid, the dispersant, and the TiB2 powder are all greater than 99.9%, and the particle size is all between 200 mesh and 500 mesh.

10. A wettable cathode, characterized in that, Prepared by the method according to any one of claims 1 to 9.

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