Tungsten-potassium arc striking electrode material and preparation method thereof

Abstract

The application provides a tungsten-potassium arc striking electrode material and a preparation method thereof, and belongs to the technical field of tungsten alloy materials, and comprises the following steps: uniformly mixing, stirring, low-pressure preforming, and preparing a porous green body by using pre-oxidized tungsten powder, titanium carbide powder and hafnium hydride powder; mixing potassium nitrate, polyvinylpyrrolidone and deionized water to form a dispersion liquid, pouring the dispersion liquid into the porous green body, and performing freeze solidification and sublimation drying treatment to prepare a composite green body; performing low-temperature heat treatment on the composite green body, and then performing hydrogen reduction to obtain a reduced green body; performing high-temperature sintering, rolling, swaging, electrolytic polishing and vacuum exhaust treatment on the reduced green body to obtain the tungsten-potassium arc striking electrode material. According to the application, the tungsten powder is pre-oxidized, the porous green body is penetrated, freeze solidification and sublimation drying are performed, the dispersion uniformity of the potassium source in the tungsten matrix is improved, and the synergistic strengthening effect of the titanium carbide and the hafnium hydride is utilized, so that the comprehensive performance of the tungsten-potassium arc striking electrode material is improved.

Description

Technical Field

[0001] This invention relates to the field of tungsten alloy materials technology, specifically to a tungsten-potassium arc-starting electrode material and its preparation method. Background Technology

[0002] Tungsten metal possesses advantages such as high melting point, low vapor pressure, high high-temperature strength, and excellent electron emission performance, making it suitable for applications in thermionic emission materials, electrode materials, and vacuum electronic devices. In specialized light source equipment, the arc-initiating electrode needs to withstand high temperatures, high currents, and complex discharge environments for extended periods. Therefore, the electrode material must not only have excellent electron emission capabilities but also good structural uniformity and mechanical properties to ensure the stable generation and continuous maintenance of the electric arc.

[0003] To improve the performance of tungsten electrode materials, rare earth oxides, carbon, potassium, or other reinforcing components are typically introduced into the tungsten matrix to enhance its properties through second-phase dispersion strengthening. Rare earth oxide-doped tungsten materials, in particular, can hinder grain boundary migration and improve structural stability, making them an important direction for improvement in traditional tungsten electrode materials. Meanwhile, tungsten-potassium materials utilize potassium to form potassium bubble structures within the tungsten matrix. These potassium bubbles pin grain boundaries, further improving the material's resistance to recrystallization and high-temperature service stability, thus finding applications in high-performance arc-starting electrodes.

[0004] For example, patent application CN115305399A discloses a rare earth tungsten electrode material and its preparation method, including the following steps: adding rare earth oxide powder to a ball mill for wet milling to obtain a rare earth oxide suspension; then adding blue tungsten powder and carbon powder to the suspension, mixing and drying to obtain a mixed powder, which is then subjected to hydrogen reduction, pressing and molding, and sintering to obtain the rare earth tungsten electrode material. This method, by mixing the rare earth oxides into a suspension and then mixing it with tungsten-based powder, makes it difficult to achieve a stable distribution of the rare earth oxides in the tungsten-based powder. In subsequent preparation processes, the rare earth oxides are prone to agglomeration, affecting the structural uniformity and mechanical properties of the electrode material.

[0005] In summary, there is a need to provide a tungsten-potassium arc-starting electrode material and its preparation method to solve the problems existing in the prior art. Summary of the Invention

[0006] In view of this, the present invention provides a tungsten-potassium arc-initiating electrode material and its preparation method.

[0007] To achieve the above objectives, a method for preparing a tungsten-potassium arc-initiating electrode material includes the following preparation steps:

[0008] S1. After pre-oxidizing tungsten powder, it is mixed and stirred evenly with titanium carbide powder and hafnium hydride powder, and then pre-formed under low pressure to produce a porous green body. S2. Potassium nitrate, polyvinylpyrrolidone and deionized water are mixed to form a dispersion, which is poured into a porous green body and then subjected to freeze curing and sublimation drying to obtain a composite green body. S3. After the composite green body is subjected to low-temperature heat treatment, it is then reduced with hydrogen to obtain a reduced green body. S4. The reduced green billet is subjected to high-temperature sintering, rolling, rotary forging, electrolytic polishing and vacuum degassing to obtain tungsten-potassium arc-starting electrode material.

[0009] This invention improves the structural uniformity and mechanical properties of tungsten-potassium electrode materials by pre-oxidizing tungsten powder, combined with a porous pre-formed structure, potassium source regulation, and dispersion strengthening with titanium carbide powder and hafnium hydride powder. Specifically, tungsten powder is first pre-oxidized to form an oxide layer on the surface of the tungsten particles, increasing their hydrophilicity and facilitating the uniform diffusion and adhesion of the dispersion in the tungsten-based powder. Then, the pre-oxidized tungsten powder, titanium carbide powder, and hafnium hydride powder are uniformly mixed and formed into a porous green body using a low-pressure preforming method. Under negative pressure, the dispersion is then infiltrated into the porous green body, allowing it to fully penetrate the internal pores. Simultaneously, the dispersion is solidified within the porous green body through low-temperature freezing to prevent migration during subsequent processing. Sublimation drying removes moisture from the dispersion, preventing localized enrichment and secondary agglomeration of potassium nitrate during drying and improving the uniformity of potassium dispersion in the porous green body. Subsequent heat treatment, reduction, and sintering promote the formation of a uniform and stable potassium bubble structure. The uniformly distributed potassium bubbles can pin tungsten grain boundary migration, limiting abnormal grain growth, improving the material's microstructure uniformity and grain stability, thereby enhancing the mechanical properties of the tungsten-potassium arc-starting electrode material.

[0010] In this invention, polyvinylpyrrolidone (PVP) is used to increase the viscosity of the dispersion, which helps the dispersion remain relatively stable after entering the porous green body. During subsequent low-temperature freezing and sublimation drying, PPVP can also temporarily fix potassium nitrate, allowing it to maintain its original distribution during moisture removal. In the subsequent low-temperature heat treatment, PPVP fully decomposes and escapes, thus avoiding the impact of residual organic components on the sintering process and material purity.

[0011] Optionally, the tungsten powder comprises a first tungsten powder with a particle size of 1.5~3μm and a second tungsten powder with a particle size of 0.3~0.8μm, wherein the mass ratio of the first tungsten powder to the second tungsten powder is (8.5~9.5):(0.5~1.5). In step S4, before the reduced green body is sintered at high temperature, it is subjected to a secondary pre-pressing treatment by cold isostatic pressing. The pressure of the cold isostatic pressing is 200~220MPa and the time is 5~10min.

[0012] In this invention, by using tungsten powders of different particle sizes in a compound, a more rational gradation structure is formed between the tungsten powder particles. The larger-sized first tungsten powder serves as the main powder to construct the basic framework, while the smaller-sized second tungsten powder fills the gaps between the first tungsten powder particles, improving the packing state between the powders and reducing structural defects caused by excessive interparticle voids during sintering. This is beneficial for improving the compactness of the green body. After low-temperature heat treatment (removal of polyvinylpyrrolidone) and hydrogen reduction, a secondary pre-pressing treatment is performed. This maintains a uniform potassium distribution while increasing the material's density, providing a good structural foundation for subsequent high-temperature sintering and other processes. Furthermore, this secondary pre-pressing treatment, performed after the removal of polyvinylpyrrolidone, allows the gases generated by the thermal decomposition of organic components to escape fully, avoiding obstruction of internal gas escape due to premature densification. This reduces the formation of pores and internal defects during sintering, further improving the material's density, hardness, and flexural strength.

[0013] Optionally, the pre-oxidation treatment is carried out at a temperature of 700~750℃ for a time of 50~80 min, and the pre-oxidation is carried out in an air atmosphere.

[0014] In this invention, tungsten powder is pre-oxidized to form an oxide layer on the surface of the tungsten powder particles, which improves the hydrophilicity of the surface and facilitates the uniform penetration of the dispersion into the porous green body. The heating oxidation temperature is controlled within the range of 700~750℃ and the time is controlled within 50~80min, which can obtain an appropriate degree of oxidation effect on the surface of the tungsten powder, avoid the impact of excessive oxidation on the subsequent hydrogen reduction process, and reduce the adverse effects of residual oxygen on the material properties during the reduction process.

[0015] Optionally, the particle size of the titanium carbide powder is 100~300nm, and the particle size of the hafnium hydride powder is 1~3μm.

[0016] In this invention, titanium carbide powder with a particle size of 100-300 nm is used as the reinforcing phase. The smaller particle size of titanium carbide helps to fill the pores between tungsten powder particles, thus hindering tungsten grain growth during sintering. Simultaneously, hafnium hydride powder with a particle size of 1-3 μm is used as an auxiliary reinforcing component, forming a stable strengthening effect with the tungsten matrix during subsequent sintering. The composite reinforcement system formed by titanium carbide and hafnium hydride improves grain stability during sintering, thereby enhancing the overall performance of the tungsten-potassium arc-starting electrode material.

[0017] Optionally, in step S1, the pressure of the low-pressure preforming is 20~30MPa, and the time is 5~10min.

[0018] In this invention, tungsten powder that has undergone pre-oxidation treatment is mixed evenly with titanium carbide powder and hafnium hydride powder, and then subjected to low-pressure pre-forming treatment. This process creates a preliminary connection between the powder particles, improving the overall forming stability of the porous green body, while retaining a certain amount of porosity so that the subsequent dispersion liquid can enter the interior of the porous green body.

[0019] Optionally, in step S2, the freeze-curing temperature is -60~-40℃ and the time is 30~50min; the sublimation drying treatment is carried out under vacuum conditions, the temperature of the sublimation drying treatment is -35~-25℃, the vacuum pressure is 5~10Pa, and the time is 8~10h.

[0020] In this invention, by freezing and solidifying the dispersion in the porous green body, potassium nitrate and polyvinylpyrrolidone maintain their original distribution within the porous structure, reducing potassium source segregation caused by liquid phase migration during subsequent drying. Secondly, by removing moisture through vacuum sublimation drying, the liquid phase flow generated during traditional evaporation drying is reduced, which helps maintain the uniform distribution of potassium source within the porous green body and facilitates the formation of a uniform potassium bubble structure, thereby improving the overall performance of the tungsten-potassium arc-starting electrode material.

[0021] Optionally, the temperature of the low-temperature heat treatment is 480~500℃, and the temperature of the hydrogen reduction is 800~820℃.

[0022] In this invention, the composite green body is subjected to low-temperature heat treatment at 480~500℃ to fully decompose and release organic components such as polyvinylpyrrolidone, thereby reducing the adverse effects of organic residues on the subsequent sintering process and avoiding structural changes in the composite green body due to excessively high heat treatment temperature. Subsequently, hydrogen reduction treatment at 800~820℃ is used to reduce the oxide layer on the surface of the pre-oxidized tungsten powder to tungsten, thereby reducing residual oxygen impurities.

[0023] Optionally, the high-temperature sintering temperature is 2330~2350℃ and the time is 5~7h.

[0024] The present invention also provides a tungsten-potassium arc-starting electrode material, which is prepared by the above-mentioned method for preparing tungsten-potassium arc-starting electrode material. The tungsten-potassium arc-starting electrode material comprises the following raw materials in parts by weight: 3000-3020 parts of tungsten powder, 8-12 parts of titanium carbide powder, 9-13 parts of hafnium hydride powder, and 53.5-70 parts of dispersion.

[0025] Optionally, the dispersion comprises the following raw materials in parts by weight: 1.5 to 7 parts potassium nitrate, 2 to 3 parts polyvinylpyrrolidone, and 50 to 60 parts deionized water.

[0026] The above-described technical solution of the present invention has at least the following beneficial effects: This invention improves the structural uniformity and mechanical properties of tungsten-potassium electrode materials by pre-oxidizing tungsten powder, combined with a porous pre-forming structure, potassium source regulation, and dispersion enhancement using titanium carbide powder and hafnium hydride. The pre-oxidation treatment forms an oxide layer on the surface of the tungsten powder, increasing surface hydrophilicity and facilitating the diffusion and adhesion of the dispersion in the tungsten-based powder. Subsequently, the pre-oxidized tungsten powder, titanium carbide powder, and hafnium hydride powder are uniformly mixed, and a porous green body is formed through low-pressure pre-forming. After the dispersion enters the pores of the porous green body, the water in the dispersion is removed by low-temperature freezing and sublimation drying, improving potassium source dispersibility. Subsequent heat treatment, reduction, and sintering promote the formation of a uniform potassium bubble structure, which pins tungsten grain boundary migration, restricts abnormal grain growth, improves material microstructure uniformity and grain stability, thereby enhancing the mechanical properties of the tungsten-potassium arc-starting electrode material.

[0027] In this invention, polyvinylpyrrolidone (PVP) is used to increase the viscosity of the dispersion, which helps the dispersion remain relatively stable after entering the porous green body. During subsequent low-temperature freezing and sublimation drying, PPVP can also temporarily fix potassium nitrate, allowing it to maintain its original distribution during moisture removal. In the subsequent low-temperature heat treatment, PPVP fully decomposes and escapes, thus avoiding the impact of residual organic components on the sintering process and material purity. Attached Figure Description

[0028] Figure 1 The image shows the metallographic structure of the tungsten-potassium arc-starting electrode material prepared in Example 2 of this invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0030] Example 1 3020 parts of tungsten powder (including first tungsten powder with a particle size of 1.5~3μm and second tungsten powder with a particle size of 0.3~0.8μm, with a mass ratio of first tungsten powder to second tungsten powder of 9.5:0.5) were placed in a high-temperature furnace and heated to 750℃ at a rate of 10℃ / min. The mixture was then oxidized in air for 80 min to obtain pre-oxidized tungsten powder. The pre-oxidized tungsten powder, 12 parts of titanium carbide powder (particle size of 100~300nm) and 13 parts of hafnium hydride powder (particle size of 1~3μm) were mixed and stirred at 400rpm for 60 min. The mixture was then poured into a mold and subjected to low-pressure preforming at 30MPa for 10 min to obtain a porous green body.

[0031] A dispersion was obtained by mixing 7 parts potassium nitrate, 3 parts polyvinylpyrrolidone (PVP-K30), and 60 parts deionized water. Under a pressure of -0.05 MPa, the dispersion was slowly and evenly poured onto a porous green body and allowed to stand for 20 minutes to allow the dispersion to fully penetrate the pores of the green body. The green body was then quickly placed in a vacuum freeze dryer at -40°C and frozen for 50 minutes to solidify the dispersion in the pores. The temperature was then adjusted to -25°C and a vacuum of 10 Pa was applied for sublimation drying for 10 hours to obtain a composite green body.

[0032] The composite green billet was placed in a heating furnace and heated to 500℃ at a rate of 4℃ / min, then held for 3 hours. It was then placed in a hydrogen furnace and reduced at 820℃ for 3 hours to obtain a reduced green billet. The reduced green billet was then fed into a cold isostatic press and pressurized to 220MPa for 10 minutes for a second pre-pressing treatment to obtain a billet strip. The billet strip was placed in a medium-frequency furnace under a hydrogen atmosphere and sintered at 2350℃ for 7 hours. Subsequently, it was hot-rolled using a three-roll Y-type mill at 1550℃ for 50 minutes, and then rounded using a rotary forging process. The rounded billet was electropolished with NaOH electrolyte for 20 minutes, and then subjected to vacuum treatment at 2100℃ for 5 hours (vacuum degree 10). -4 After exhausting the gas (Pa), the tungsten potassium arc-starting electrode material is obtained by ultrasonic cleaning.

[0033] Example 2 3010 parts of tungsten powder (including first tungsten powder with a particle size of 1.5~3μm and second tungsten powder with a particle size of 0.3~0.8μm, with a mass ratio of first tungsten powder to second tungsten powder of 9:1) were placed in a high-temperature furnace and heated to 720℃ at a rate of 8℃ / min. After being kept at this temperature for 60 min in an air atmosphere, pre-oxidized tungsten powder was obtained. The pre-oxidized tungsten powder, 10 parts of titanium carbide powder (particle size of 100~300nm) and 11 parts of hafnium hydride powder (particle size of 1~3μm) were mixed and stirred at 300rpm for 40 min. The mixture was then poured into a mold and subjected to low-pressure preforming at 25MPa for 8 min to obtain a porous green body.

[0034] Five parts potassium nitrate, 2.5 parts polyvinylpyrrolidone (PVP-K30), and 55 parts deionized water were stirred evenly to obtain a dispersion. Under a pressure of -0.07 MPa, the dispersion was slowly and evenly poured onto a porous green body and allowed to stand for 15 minutes to allow the dispersion to fully penetrate the pores of the green body. The green body was then quickly placed in a vacuum freeze dryer at -50°C and frozen for 40 minutes to solidify the dispersion in the pores. The temperature was then adjusted to -30°C and a vacuum of 7 Pa was applied for sublimation drying for 9 hours to obtain a composite green body.

[0035] The composite green billet was placed in a heating furnace and heated to 490℃ at a rate of 3℃ / min, then held for 2 hours. It was then placed in a hydrogen furnace and reduced at 810℃ for 2.5 hours to obtain a reduced green billet. The reduced green billet was then fed into a cold isostatic press and pressurized to 210MPa for 7 minutes for a second pre-pressing treatment to obtain a billet strip. The billet strip was placed in a medium-frequency furnace under a hydrogen atmosphere and sintered at 2340℃ for 6 hours. Subsequently, it was hot-rolled using a three-roll Y-type mill at 1520℃ for 45 minutes, and then rounded using a rotary forging process. The rounded billet was electropolished with NaOH electrolyte for 15 minutes, and then subjected to vacuum treatment at 2000℃ for 4 hours (vacuum degree 10). -4 After exhausting the gas (Pa), the tungsten potassium arc-starting electrode material is obtained by ultrasonic cleaning.

[0036] Example 3 3000 parts of tungsten powder (including first tungsten powder with a particle size of 1.5~3μm and second tungsten powder with a particle size of 0.3~0.8μm, with a mass ratio of first tungsten powder to second tungsten powder of 8.5:1.5) were placed in a high-temperature furnace and heated to 700℃ at a rate of 5℃ / min. The mixture was then oxidized in air for 50 min to obtain pre-oxidized tungsten powder. The pre-oxidized tungsten powder, 8 parts of titanium carbide powder (particle size of 100~300nm) and 9 parts of hafnium hydride powder (particle size of 1~3μm) were mixed and stirred at 200rpm for 30 min. The mixture was then poured into a mold and subjected to low-pressure preforming at 20MPa for 5 min to obtain a porous green body.

[0037] A dispersion was obtained by stirring 1.5 parts potassium nitrate, 2 parts polyvinylpyrrolidone (PVP-K30), and 50 parts deionized water until homogeneous. Under a pressure of -0.08 MPa, the dispersion was slowly and evenly poured onto a porous green body and allowed to stand for 10 minutes to allow the dispersion to fully penetrate the pores of the green body. The green body was then quickly placed in a vacuum freeze dryer at a temperature of -60℃ and subjected to low-temperature freezing treatment for 30 minutes to freeze and solidify the dispersion in the pores. The temperature was then adjusted to -35℃ and a vacuum of 5 Pa was applied for sublimation drying treatment for 8 hours to obtain a composite green body.

[0038] The composite green billet was placed in a heating furnace and heated to 480℃ at a rate of 2℃ / min, then held for 1 hour. It was then placed in a hydrogen furnace and reduced at 800℃ for 2 hours to obtain a reduced green billet. The reduced green billet was then fed into a cold isostatic press and pressurized to 200MPa for 5 minutes for a second pre-pressing treatment to obtain a billet strip. The billet strip was placed in a medium-frequency furnace under a hydrogen atmosphere and sintered at 2330℃ for 5 hours. Subsequently, it was hot-rolled using a three-roll Y-type mill at 1500℃ for 40 minutes, and then rounded using a rotary forging process. The rounded billet was electropolished with NaOH electrolyte for 10 minutes, and then subjected to vacuum treatment at 1900℃ for 3 hours (vacuum degree 10). -5 After exhausting the gas (Pa), the tungsten potassium arc-starting electrode material is obtained by ultrasonic cleaning.

[0039] Example 4 3015 parts of tungsten powder (including first tungsten powder with a particle size of 1.5~3μm and second tungsten powder with a particle size of 0.3~0.8μm, with a mass ratio of first tungsten powder to second tungsten powder of 9:1) were placed in a high-temperature furnace and heated to 720℃ at a rate of 6℃ / min. After being kept at this temperature for 65 min in an air atmosphere, pre-oxidized tungsten powder was obtained. The pre-oxidized tungsten powder, 11 parts of titanium carbide powder (particle size of 100~300nm) and 10 parts of hafnium hydride powder (particle size of 1~3μm) were mixed and stirred at 350rpm for 40 min. The mixture was then poured into a mold and subjected to low-pressure preforming at 30MPa for 5 min to obtain a porous green body.

[0040] A dispersion was obtained by stirring 4.5 parts potassium nitrate, 2.5 parts polyvinylpyrrolidone (PVP-K30), and 53 parts deionized water until homogeneous. Under a pressure of -0.06 MPa, the dispersion was slowly and evenly poured onto a porous green body and allowed to stand for 15 minutes to allow the dispersion to fully penetrate the pores of the green body. The green body was then quickly placed in a vacuum freeze dryer at -60°C and frozen for 35 minutes to solidify the dispersion in the pores. The temperature was then adjusted to -25°C and a vacuum of 5 Pa was applied for sublimation drying for 9 hours to obtain a composite green body.

[0041] The composite green billet was placed in a heating furnace and heated to 490℃ at a rate of 2℃ / min, then held for 1.5 hours. It was then placed in a hydrogen furnace and reduced at 815℃ for 2 hours to obtain a reduced green billet. The reduced green billet was then fed into a cold isostatic press and pressurized to 200MPa for 10 minutes for a second pre-pressing treatment to obtain a billet strip. The billet strip was placed in a medium-frequency furnace under a hydrogen atmosphere and sintered at 2340℃ for 5.5 hours. Subsequently, it was hot-rolled using a three-roll Y-type mill at 1550℃ for 40 minutes, and then rounded using a rotary forging process. The rounded billet was electropolished in NaOH electrolyte for 12 minutes, and then subjected to vacuum treatment (vacuum degree 10) at 1950℃ for 4.5 hours. -4 After exhausting the gas (Pa), the tungsten potassium arc-starting electrode material is obtained by ultrasonic cleaning.

[0042] Example 5 3015 parts of tungsten powder (including first tungsten powder with a particle size of 1.5~3μm and second tungsten powder with a particle size of 0.3~0.8μm, with a mass ratio of first tungsten powder to second tungsten powder of 8.5:1.5) were placed in a high-temperature furnace and heated to 740℃ at a rate of 8℃ / min. The mixture was then oxidized in air for 60 min to obtain pre-oxidized tungsten powder. The pre-oxidized tungsten powder, 10.5 parts of titanium carbide powder (particle size of 100~300nm) and 10 parts of hafnium hydride powder (particle size of 1~3μm) were mixed and stirred at 200rpm for 60 min. The mixture was then poured into a mold and subjected to low-pressure preforming at 28MPa for 6 min to obtain a porous green body.

[0043] A dispersion was obtained by stirring 3.5 parts potassium nitrate, 3 parts polyvinylpyrrolidone (PVP-K30), and 60 parts deionized water until homogeneous. Under a pressure of -0.08 MPa, the dispersion was slowly and evenly poured onto a porous green body and allowed to stand for 12 minutes to allow the dispersion to fully penetrate the pores of the green body. The green body was then quickly placed in a vacuum freeze dryer at -55℃ and frozen for 35 minutes to solidify the dispersion in the pores. The temperature was then adjusted to -25℃ and a vacuum of 7 Pa was applied for sublimation drying for 8.5 hours to obtain a composite green body.

[0044] The composite green billet was placed in a heating furnace and heated to 480℃ at a rate of 3℃ / min, then held for 2.5 hours. It was then placed in a hydrogen furnace and reduced at 820℃ for 2 hours to obtain a reduced green billet. The reduced green billet was then fed into a cold isostatic press and pressurized to 215MPa for 7 minutes for a second pre-pressing treatment to obtain a billet strip. The billet strip was placed in a medium-frequency furnace under a hydrogen atmosphere and sintered at 2330℃ for 6.5 hours. Subsequently, it was hot-rolled using a three-roll Y-type mill at 1530℃ for 45 minutes, and then rounded using a rotary forging process. The rounded billet was electropolished with NaOH electrolyte for 15 minutes, and then subjected to vacuum treatment (vacuum degree 10) at 2070℃ for 5 hours. -5 After exhausting the gas (Pa), the tungsten potassium arc-starting electrode material is obtained by ultrasonic cleaning.

[0045] Example 6 3020 parts of tungsten powder (particle size 1.5~3μm) were placed in a high-temperature furnace and heated to 750℃ at a rate of 10℃ / min. The mixture was then oxidized in air for 80 min to obtain pre-oxidized tungsten powder. The pre-oxidized tungsten powder, 12 parts of titanium carbide powder (particle size 100~300nm) and 13 parts of hafnium hydride powder (particle size 1~3μm) were mixed and stirred at 400rpm for 60 min. The mixture was then poured into a mold and subjected to low-pressure preforming at 30MPa for 10 min to obtain a porous green body.

[0046] A dispersion was obtained by mixing 7 parts potassium nitrate, 3 parts polyvinylpyrrolidone (PVP-K30), and 60 parts deionized water. Under a pressure of -0.05 MPa, the dispersion was slowly and evenly poured onto a porous green body and allowed to stand for 20 minutes to allow the dispersion to fully penetrate the pores of the green body. The green body was then quickly placed in a vacuum freeze dryer at -40°C and frozen for 50 minutes to solidify the dispersion in the pores. The temperature was then adjusted to -25°C and a vacuum of 10 Pa was applied for sublimation drying for 10 hours to obtain a composite green body.

[0047] The composite green billet was placed in a heating furnace and heated to 500℃ at a rate of 4℃ / min, then held for 3 hours. It was then placed in a hydrogen furnace and reduced at 820℃ for 3 hours to obtain a reduced green billet. The reduced green billet was then fed into a cold isostatic press and pressurized to 220MPa for 10 minutes for a second pre-pressing treatment to obtain a billet strip. The billet strip was placed in a medium-frequency furnace under a hydrogen atmosphere and sintered at 2350℃ for 7 hours. Subsequently, it was hot-rolled using a three-roll Y-type mill at 1550℃ for 50 minutes, and then rounded using a rotary forging process. The rounded billet was electropolished with NaOH electrolyte for 20 minutes, and then subjected to vacuum treatment at 2100℃ for 5 hours (vacuum degree 10). -4After exhausting the gas (Pa), the tungsten potassium arc-starting electrode material is obtained by ultrasonic cleaning.

[0048] The present invention also includes comparative examples and related experiments.

[0049] Comparative Example 1 The only difference from Example 1 is that polyvinylpyrrolidone was not used; all other components and preparation steps were exactly the same, resulting in a tungsten-potassium arc-starting electrode material.

[0050] Comparative Example 2 The only difference from Example 1 is that the "freeze-curing and sublimation drying" treatment was not performed. All other components and preparation steps were completely the same, and a tungsten-potassium arc-starting electrode material was obtained.

[0051] Comparative Example 3 The only difference from Example 1 is that the tungsten powder was not pre-oxidized; the other components and preparation steps were completely identical, resulting in a tungsten-potassium arc-starting electrode material.

[0052] Performance testing: The densities of the tungsten-potassium arc-starting electrode materials in Examples 1-6 and Comparative Examples 1-3 were tested with reference to standard GB / T 3850-2015, and the test results are shown in Table 1.

[0053] The mechanical properties of the tungsten-potassium arc-starting electrode materials in Examples 1-6 and Comparative Examples 1-3 were tested for hardness (HV0.2) according to standard GB / T 4340.1-2024 and for bending strength according to standard GB / T 10418-2002.

[0054] The thermal conductivity of the tungsten-potassium arc-starting electrode materials in Examples 1-6 and Comparative Examples 1-3 was tested with reference to standard GB / T 22588-2008; the potassium content in the tungsten-potassium arc-starting electrode materials in Examples 1-6 and Comparative Examples 1-3 was tested with reference to standard GB / T4324.18-2012; the grain size of the tungsten-potassium arc-starting electrode materials in Examples 1-6 and Comparative Examples 1-3 was tested with reference to standard GB / T 13298-2015. The test results are shown in Table 1.

[0055] Table 1

[0056] Based on the test results in Table 1, it can be seen that the tungsten-potassium arc-starting electrode materials prepared in Examples 1-6 have high density, hardness, bending strength, and thermal conductivity, and small average grain size, indicating that the preparation method provided by this invention has good repeatability (wherein, the metallographic image of the tungsten-potassium arc-starting electrode material prepared in Example 2 is shown in the figure). Figure 1 (As shown).

[0057] Compared to Examples 1-5, Example 6 uses tungsten powder of a single particle size (1.5-3 μm) to prepare tungsten-potassium arc-starting electrode material. Its density, hardness and bending strength are reduced, indicating that using tungsten powder of different particle sizes to form a more reasonable particle size distribution structure can improve the mechanical properties of tungsten-potassium arc-starting electrode material.

[0058] Compared to Example 1, Comparative Example 1, which did not add polyvinylpyrrolidone, resulted in an increased average grain size and decreased hardness, flexural strength, and thermal conductivity in the obtained tungsten-potassium arc-starting electrode material. This indicates that polyvinylpyrrolidone is beneficial for improving the dispersion uniformity of the potassium source in the tungsten matrix and improving the mechanical properties of the material. Compared to Example 1, Comparative Example 2, which did not undergo "freeze-curing and sublimation drying" treatment, resulted in a significantly increased average grain size and significantly decreased hardness and flexural strength in the obtained tungsten-potassium arc-starting electrode material. This indicates that the freeze-curing and sublimation drying treatment method in this invention is beneficial for maintaining the uniform distribution of the potassium source in the porous green body, thereby promoting the formation of a uniform potassium bubble structure and improving the material's microstructure uniformity and mechanical properties. Compared to Example 1, Comparative Example 3, which did not undergo pre-oxidation treatment of the tungsten powder, resulted in an increased average grain size in the obtained tungsten-potassium arc-starting electrode material. This indicates that the pre-oxidation treatment improves the penetration and wetting effect of the dispersion liquid on the tungsten powder, further improving the dispersion uniformity of the potassium source, inhibiting grain growth, and improving the material's microstructure uniformity.

[0059] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a tungsten-potassium arc-initiating electrode material, characterized in that, The preparation steps include the following: S1. After pre-oxidizing tungsten powder, it is mixed and stirred evenly with titanium carbide powder and hafnium hydride powder, and then pre-formed under low pressure to produce a porous green body. S2. Potassium nitrate, polyvinylpyrrolidone and deionized water are mixed to form a dispersion, which is poured into a porous green body and then subjected to freeze curing and sublimation drying to obtain a composite green body. S3. After the composite green body is subjected to low-temperature heat treatment, it is then reduced with hydrogen to obtain a reduced green body. S4. The reduced green billet is subjected to high-temperature sintering, rolling, rotary forging, electrolytic polishing and vacuum degassing to obtain tungsten-potassium arc-starting electrode material.

2. The method for preparing a tungsten-potassium arc-initiating electrode material according to claim 1, characterized in that, The tungsten powder comprises a first tungsten powder with a particle size of 1.5~3μm and a second tungsten powder with a particle size of 0.3~0.8μm, wherein the mass ratio of the first tungsten powder to the second tungsten powder is (8.5~9.5):(0.5~1.5). In step S4, before the reduced green body is sintered at high temperature, it is subjected to a secondary pre-pressing treatment by cold isostatic pressing. The pressure of the cold isostatic pressing is 200~220MPa and the time is 5~10min.

3. The method for preparing a tungsten-potassium arc-initiating electrode material according to claim 1, characterized in that, The pre-oxidation treatment is carried out at a temperature of 700~750℃ for 50~80 minutes; the pre-oxidation treatment is carried out in an air atmosphere.

4. The method for preparing a tungsten-potassium arc-initiating electrode material according to claim 2, characterized in that, The titanium carbide powder has a particle size of 100~300nm, and the hafnium hydride powder has a particle size of 1~3μm.

5. The method for preparing a tungsten-potassium arc-initiating electrode material according to claim 1, characterized in that, In step S1, the pressure of low-pressure preforming is 20~30MPa, and the time is 5~10min.

6. The method for preparing a tungsten-potassium arc-initiating electrode material according to claim 1, characterized in that, In step S2, the freeze-curing temperature is -60~-40℃ and the time is 30~50min; The sublimation drying process is carried out under vacuum conditions, with a temperature of -35 to -25°C, a vacuum pressure of 5 to 10 Pa, and a time of 8 to 10 hours.

7. The method for preparing a tungsten-potassium arc-initiating electrode material according to claim 6, characterized in that, The temperature of the low-temperature heat treatment is 480~500℃, and the temperature of the hydrogen reduction is 800~820℃.

8. The method for preparing a tungsten-potassium arc-initiating electrode material according to claim 1, characterized in that, The high-temperature sintering temperature is 2330~2350℃, and the time is 5~7h.

9. A tungsten-potassium arc-initiating electrode material, prepared by the method for preparing a tungsten-potassium arc-initiating electrode material according to any one of claims 1 to 8, characterized in that, The tungsten-potassium arc-starting electrode material comprises the following raw materials in parts by weight: 3000-3020 parts of tungsten powder, 8-12 parts of titanium carbide powder, 9-13 parts of hafnium hydride powder, and 53.5-70 parts of dispersion.

10. The tungsten-potassium arc-starting electrode material according to claim 9, characterized in that, The dispersion comprises the following raw materials in parts by weight: 1.5-7 parts potassium nitrate, 2-3 parts polyvinylpyrrolidone, and 50-60 parts deionized water.

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