A non-stoichiometric carbide-doped tungsten-based thermionic cathode material and a method of making the same

Abstract

The application relates to a non-stoichiometric carbide doped tungsten-based thermionic cathode material and a preparation method thereof, and belongs to the technical field of refractory metal cathode materials. Zirconium carbide, hafnium carbide and titanium carbide are respectively mixed with their respective hydrides or graphite by using a high-energy ball milling technology, and then mixed with tungsten powder to obtain non-stoichiometric carbide doped tungsten powder with C "vacancies" or non-stoichiometric carbide doped tungsten powder with metal element "vacancies", and then the non-stoichiometric carbide doped tungsten-based thermionic cathode is prepared by means of pressing, vacuum sintering at 1600-2100 DEG C. The thermionic cathode material has the advantages of simple preparation process, high cathode density of 99%, and the highest emission current density of 1.63 A / cm 2 at 1600 DEG C, which is about 30% higher than that of a standard stoichiometric carbide, and the thermionic emission performance is 3 times higher than that of a pure metal cathode.

Description

Technical Field

[0001] This invention relates to a non-stoichiometric carbide-doped tungsten-based thermal cathode material and its preparation method, belonging to the technical field of refractory metal cathode materials. Background Technology

[0002] Currently, a wide variety of hot cathodes are used in propulsion, each with varying emission performance. Tungsten cathodes are used in magneto-plasma dynamics (MPD) propulsion, but the harsh high-temperature operating environment makes it difficult for them to meet higher requirements. Oxide cathodes have high emission current densities but poor resistance to poisoning and ion bombardment. Reservoir cathodes have high emission current densities and resistance to poisoning and bombardment, but are not suitable for ultra-high-temperature operating environments. Commonly used MPD propulsion cathodes are barium-tungsten cathodes and lanthanum hexaboride cathodes. However, barium-tungsten cathodes are prone to failure due to the evaporation of active materials at high temperatures, while lanthanum hexaboride cathodes are limited by poor resistance to poisoning and stringent environmental requirements. Thorium oxide-tungsten cathodes, previously reported for use in propulsion, have had their application limited by the radioactivity of thorium.

[0003] Chinese patent CN 102184818 A discloses a lanthanum carbide-tungsten thermionic cathode material and its preparation method. This method involves adding lanthanum carbide to a tungsten matrix to create a novel lanthanum carbide-tungsten cathode material. While exhibiting good thermal emission performance, lanthanum carbide has a melting point of only 2360℃. During operation, it not only emits electrons but also withstands high-energy bombardment from cations, causing the temperature in the cathode working region to frequently exceed its melting point, leading to electrode failure and unstable performance. In contrast, titanium carbide (3140℃), zirconium carbide (3532℃), and hafnium carbide (2930℃) all have melting points significantly higher than lanthanum carbide, comparable to ThO2 (3390℃), and are stable in the atmosphere, less prone to deterioration and failure. Existing carbide-doped tungsten cathodes have emission current densities of less than 0.2 A / cm² at 1600℃. 2 This is insufficient to meet the needs of practical applications, thus requiring modification of the cathode.

[0004] The magnetic plasma thruster operates in a high-temperature environment (far exceeding the operating temperature of ordinary tungsten carbide-based cathodes), with relatively high sintering and testing temperatures. Its performance needs further improvement compared to existing tungsten carbide-based cathodes.

[0005] Currently, there are no methods for developing non-stoichiometric carbide-doped tungsten-based thermal cathode materials, especially for applications requiring high temperatures. This study utilizes specific non-stoichiometric carbides such as Zr... 1.2 C 0.8 A novel tungsten-based cathode material was prepared by incorporating it into a tungsten matrix. The process is simple and suitable for use in the high-temperature operating environment of magnetic plasma thrusters, with significantly improved emission performance. Summary of the Invention

[0006] This invention addresses the problems existing in the prior art by providing a non-stoichiometric carbide-doped tungsten-based thermal cathode material and its preparation method. Zirconium carbide, hafnium carbide, and titanium carbide are each mixed with their respective hydrides in a specific ratio using high-energy ball milling technology, and then mixed with tungsten powder to obtain non-stoichiometric carbide-doped tungsten powder with C "deficient". Simultaneously, zirconium carbide, hafnium carbide, and titanium carbide are each mixed with graphite in a specific ratio using high-energy ball milling technology, and then mixed with tungsten powder to obtain non-stoichiometric carbide-doped tungsten powder with metal element "deficient". The non-stoichiometric carbide-doped tungsten powder is then pressed and vacuum sintered to prepare a cathode with high density and high emission performance. Specifically, the method includes the following:

[0007] A non-stoichiometric carbide-doped tungsten-based thermal cathode material and its preparation method, the specific steps of which are as follows:

[0008] (1) Preparation of non-stoichiometric carbide powder: Zirconium carbide, hafnium carbide, and titanium carbide are mixed with their respective hydrides in a certain proportion to obtain non-stoichiometric carbide powder with C "absence"; Zirconium carbide, hafnium carbide, and titanium carbide are mixed with graphite in a certain proportion to obtain non-stoichiometric carbide powder with metal element "absence";

[0009] (2) Preparation of precursor powder: The non-stoichiometric carbide powder with C "absence" or the non-stoichiometric carbide powder with metal element "absence" prepared in step (1) is mechanically mixed with micron-sized tungsten powder to obtain non-stoichiometric carbide doped tungsten precursor powder.

[0010] (3) Molding: The precursor powder obtained in step (2) is placed into a mold and pressed into a green body;

[0011] (4) Vacuum sintering: The blank formed by molding in step (3) is subjected to vacuum high-temperature sintering to obtain a non-stoichiometric carbide-doped tungsten-based hot cathode.

[0012] In step (1), the molar ratio of Zr / Hf / Ti to C in the non-stoichiometric carbide powder with "C absence" is 1.3:0.7 to 1.1:0.9, and the molar ratio of Zr / Hf / Ti to C in the non-stoichiometric carbide powder with "metal element absence" is 0.7:1.3 to 0.9:1.1.

[0013] In step (1), the non-stoichiometric carbide powder is obtained by high-energy ball milling. The specific method is as follows: under the protection of argon atmosphere, the non-stoichiometric carbide powder with C "deficient" and the non-stoichiometric carbide powder with metal element "deficient" are respectively subjected to high-energy ball milling, with a ball-to-material ratio of 2:1 to 8:1, a ball milling time of 0.5 to 3 hours, and a rotation speed of 150 r / min.

[0014] In step (2) of the precursor powder preparation, non-stoichiometric carbides account for 10% to 40% of the total material, and the remainder is tungsten powder.

[0015] The precursor powder in step (2) is obtained by high-energy ball milling. The specific method is as follows: under the protection of argon atmosphere, non-stoichiometric carbide and tungsten powder are subjected to high-energy ball milling with a ball-to-material ratio of 2:1 to 8:1, a ball milling time of 4 to 10 hours, and a rotation speed of 350 r / min.

[0016] The molding method in step (3) is as follows: under the protection of argon atmosphere, a mold with a diameter of Φ3mm is selected to press the precursor powder into a green blank, with a pressure of 200MPa and a holding pressure of 3-5min.

[0017] The vacuum sintering method in step (4) is as follows: the compact is placed in a vacuum tungsten wire sintering furnace for matrix sintering at a temperature of 1600–2100℃ for 2–8 hours, followed by a 40-minute cooling process to 1000℃, and then cooled with the furnace. Throughout the sintering process, the vacuum level must be maintained at 5 × 10⁻⁶. -3 Pa or above.

[0018] The above preparation method is particularly suitable when the non-stoichiometric carbide powder is Zr. 1.2 C 0.8 The non-stoichiometric carbide-doped tungsten-based hot cathode material prepared when the molar ratio of Zr to C is 1.2:0.8 can be applied to magnetic plasma thrusters operating in the corresponding high-temperature environment and exhibits good emission performance, such as an emission current density of 1.63 A / cm³ at 1600℃. 2 .

[0019] The present invention relates to a non-stoichiometric carbide-doped tungsten-based hot cathode material, which has a simple preparation method and produces a dense cathode structure with excellent thermionic emission capability. The method involves mixing zirconium carbide and zirconium hydride in a Zr:C molar ratio of 1.2:0.8 (Zr... 1.2 C 0.8 When mixed, this stoichiometric ratio of carbide-doped tungsten-based thermal cathode (W-Zr) 1.2 C 0.8 It has the highest emission current density.

[0020] The fabrication process for this thermal cathode material is simple, and the cathode density reaches as high as 99%, especially when Zr is used. 1.2 C 0.8 At 1600℃, the emission current density reaches a maximum of 1.63 A / cm. 2 Compared to standard stoichiometric ratios, it is about 30% higher than that of carbides, and compared to pure metal cathodes, it has a 3-fold improvement in thermionic emission performance. Attached Figure Description

[0021] Figure 1 This is a flow chart of the cathode preparation process of the present invention;

[0022] Figure 2 In Example 2 of this invention, the non-stoichiometric ratio Zr 1.2 C 0.8 Scanning electron microscope image of the powder after mechanical mixing with tungsten powder;

[0023] Figure 3 The vacuum-sintered non-stoichiometric zirconium carbide-doped tungsten-based hot cathode substrate (W-Zr) in Example 2 of this invention 1.2 C 0.8 Scanning electron microscope image;

[0024] Figure 4 The vacuum-sintered non-stoichiometric zirconium carbide-doped tungsten-based thermionic cathode (W-Zr) in Example 2 of this invention 1.2 C 0.8 Emission LogU-LogI curves and zirconium carbide tungsten-based thermionic cathode emission LogU-LogI curves;

[0025] Figure 5 The density of non-stoichiometric carbide-doped tungsten-based thermal cathodes in various examples of this invention;

[0026] Table 1 shows the emission performance of non-stoichiometric carbide-doped tungsten-based thermionic cathodes in various examples of the present invention. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0028] Example 1

[0029] (1) Under an argon atmosphere, zirconium carbide, hafnium carbide, and titanium carbide were respectively mixed with their respective hydrides at a Zr / Hf / Ti to C molar ratio of 1.3:0.7 (denoted as Zr). 1.3 C 0.7 Hf 1.3 C 0.7 Ti 1.3 C 0.7 Place 10g of the mixture into a ball mill jar, and then add tungsten carbide grinding balls into the jar at a ball-to-material ratio of 2:1 to 8:1. Fix the ball mill jar onto a planetary ball mill, rotate at 150 r / min, and mill for 0.5 to 3 hours. Then stop the mill and collect the material under argon atmosphere.

[0030] (2) Under an argon atmosphere, 10%–40% of non-stoichiometric carbide powder (Zr) 1.3 C 0.7 Hf1.3 C 0.7 Ti 1.3 C 0.7 20g of tungsten powder (60%–90%) was placed in a ball mill jar, and tungsten carbide grinding balls were added to the jar at a ball-to-powder ratio of 2:1–8:1. The ball mill jar was then fixed on a planetary ball mill at a speed of 350 r / min for 4–10 hours. After milling, the mill was stopped, and the material was collected under argon atmosphere.

[0031] (3) The mixture prepared in step (2) is put into a mold for cold pressing. At room temperature, a mold with a diameter of Φ3mm is selected, the pressure is 200MPa, the pressure is held for 3 to 5 minutes, and then the pressure is released and the mold is demolded to prepare a blank.

[0032] (4) Place the billet prepared in step (3) into a vacuum sintering furnace, heat it to 1000°C for 30 minutes, then heat it to 1400°C for 40 minutes, hold it for 20-60 minutes, then heat it to 1600-2100°C for 90 minutes, hold it for 2-8 hours, and finally cool it to 1000°C for 40 minutes and cool it with the furnace.

[0033] (5) Polish with 800#, 1200#, and 2000# sandpaper respectively, ultrasonically wash with water, and air dry. Place the obtained cathode in a flat diode structure to test the DC current emission density.

[0034] Example 2

[0035] (1) Under an argon atmosphere, zirconium carbide, hafnium carbide, and titanium carbide were respectively mixed with their respective hydrides at a Zr / Hf / Ti to C molar ratio of 1.2:0.8 (denoted as Zr). 1.2 C 0.8 Hf 1.2 C 0.8 Ti 1.2 C 0.8 Place 10g of the mixture into a ball mill jar, and then add tungsten carbide grinding balls into the jar at a ball-to-material ratio of 2:1 to 8:1. Fix the ball mill jar onto a planetary ball mill, rotate at 150 r / min, and mill for 0.5 to 3 hours. Then stop the mill and collect the material under argon atmosphere.

[0036] (2) Under an argon atmosphere, 10%–40% of non-stoichiometric carbide powder (Zr) 1.2 C 0.8 Hf 1.2 C 0.8 Ti 1.2 C 0.820g of tungsten powder (60%–90%) was placed in a ball mill jar, and tungsten carbide grinding balls were added to the jar at a ball-to-powder ratio of 2:1–8:1. The ball mill jar was then fixed on a planetary ball mill at a speed of 350 r / min for 4–10 hours. After milling, the mill was stopped, and the material was collected under argon atmosphere.

[0037] (3) The mixture prepared in step (2) is put into a mold for cold pressing. At room temperature, a mold with a diameter of Φ3mm is selected, the pressure is 200MPa, the pressure is held for 3 to 5 minutes, and then the pressure is released and the mold is demolded to prepare a blank.

[0038] (4) Place the billet prepared in step (3) into a vacuum sintering furnace, heat it to 1000°C for 30 minutes, then heat it to 1400°C for 40 minutes, hold it for 20-60 minutes, then heat it to 1600-2100°C for 90 minutes, hold it for 2-8 hours, and finally cool it to 1000°C for 40 minutes and cool it with the furnace.

[0039] (5) Polish with 800#, 1200#, and 2000# sandpaper respectively, ultrasonically wash with water, and air dry. Place the obtained cathode in a flat diode structure to test the DC current emission density.

[0040] Example 3

[0041] (1) Under an argon atmosphere, zirconium carbide, hafnium carbide, and titanium carbide were respectively mixed with their respective hydrides at a Zr / Hf / Ti to C molar ratio of 1.1:0.9 (denoted as Zr). 1.1 C 0.9 Hf 1.1 C 0.9 Ti 1.1 C 0.9 Place 10g of the mixture into a ball mill jar, and then add tungsten carbide grinding balls into the jar at a ball-to-material ratio of 2:1 to 8:1. Fix the ball mill jar onto a planetary ball mill, rotate at 150 r / min, and mill for 0.5 to 3 hours. Then stop the mill and collect the material under argon atmosphere.

[0042] (2) Under an argon atmosphere, 10%–40% of non-stoichiometric carbide powder (Zr) 1.1 C 0.9 Hf 1.1 C 0.9 Ti 1.1 C 0.9 20g of tungsten powder (60%–90%) was placed in a ball mill jar, and tungsten carbide grinding balls were added to the jar at a ball-to-powder ratio of 2:1–8:1. The ball mill jar was then fixed on a planetary ball mill at a speed of 350 r / min for 4–10 hours. After milling, the mill was stopped, and the material was collected under argon atmosphere.

[0043] (3) The mixture prepared in step (2) is put into a mold for cold pressing. At room temperature, a mold with a diameter of Φ3mm is selected, the pressure is 200MPa, the pressure is held for 3 to 5 minutes, and then the pressure is released and the mold is demolded to prepare a blank.

[0044] (4) Place the billet prepared in step (3) into a vacuum sintering furnace, heat it to 1000°C for 30 minutes, then heat it to 1400°C for 40 minutes, hold it for 20-60 minutes, then heat it to 1600-2100°C for 90 minutes, hold it for 2-8 hours, and finally cool it to 1000°C for 40 minutes and cool it with the furnace.

[0045] (5) Polish with 800#, 1200#, and 2000# sandpaper respectively, ultrasonically wash with water, and air dry. Place the obtained cathode in a flat diode structure to test the DC current emission density.

[0046] Example 4

[0047] (1) Under an argon atmosphere, zirconium carbide, hafnium carbide, and titanium carbide were respectively mixed with graphite at a Zr / Hf / Ti to C molar ratio of 0.9:1.1 (denoted as Zr). 0.9 C 1.1 Hf 0.9 C 1.1 Ti 0.9 C 1.1 Place 10g of the mixture into a ball mill jar, and then add tungsten carbide grinding balls into the jar at a ball-to-material ratio of 2:1 to 8:1. Fix the ball mill jar onto a planetary ball mill, rotate at 150 r / min, and mill for 0.5 to 3 hours. Then stop the mill and collect the material under argon atmosphere.

[0048] (2) Under an argon atmosphere, 10%–40% of non-stoichiometric carbide powder (Zr) 0.9 C 1.1 Hf 0.9 C 1.1 Ti 0.9 C 1.1 20g of tungsten powder (60%–90%) was placed in a ball mill jar, and tungsten carbide grinding balls were added to the jar at a ball-to-powder ratio of 2:1–8:1. The ball mill jar was then fixed on a planetary ball mill at a speed of 350 r / min for 4–10 hours. After milling, the mill was stopped, and the material was collected under argon atmosphere.

[0049] (3) The mixture prepared in step (2) is put into a mold for cold pressing. At room temperature, a mold with a diameter of Φ3mm is selected, the pressure is 200MPa, the pressure is held for 3 to 5 minutes, and then the pressure is released and the mold is demolded to prepare a blank.

[0050] (4) Place the billet prepared in step (3) into a vacuum sintering furnace, heat it to 1000°C for 30 minutes, then heat it to 1400°C for 40 minutes, hold it for 20-60 minutes, then heat it to 1600-2100°C for 90 minutes, hold it for 2-8 hours, and finally cool it to 1000°C for 40 minutes and cool it with the furnace.

[0051] (5) Polish with 800#, 1200#, and 2000# sandpaper respectively, ultrasonically wash with water, and air dry. Place the obtained cathode in a flat diode structure to test the DC current emission density.

[0052] Example 5

[0053] (1) Under an argon atmosphere, zirconium carbide, hafnium carbide, and titanium carbide were respectively mixed with graphite at a Zr / Hf / Ti to C molar ratio of 0.8:1.2 (denoted as Zr). 0.8 C 1.2 Hf 0.8 C 1.2 Ti 0.8 C 1.2 Place 10g of the mixture into a ball mill jar, and then add tungsten carbide grinding balls into the jar at a ball-to-material ratio of 2:1 to 8:1. Fix the ball mill jar onto a planetary ball mill, rotate at 150 r / min, and mill for 0.5 to 3 hours. Then stop the mill and collect the material under argon atmosphere.

[0054] (2) Under an argon atmosphere, 10%–40% of non-stoichiometric carbide powder (Zr) 0.8 C 1.2 Hf 0.8 C 1.2 Ti 0.8 C 1.2 20g of tungsten powder (60%–90%) was placed in a ball mill jar, and tungsten carbide grinding balls were added to the jar at a ball-to-powder ratio of 2:1–8:1. The ball mill jar was then fixed on a planetary ball mill at a speed of 350 r / min for 4–10 hours. After milling, the mill was stopped, and the material was collected under argon atmosphere.

[0055] (3) The mixture prepared in step (2) is put into a mold for cold pressing. At room temperature, a mold with a diameter of Φ3mm is selected, the pressure is 200MPa, the pressure is held for 3 to 5 minutes, and then the pressure is released and the mold is demolded to prepare a blank.

[0056] (4) Place the billet prepared in step (3) into a vacuum sintering furnace, heat it to 1000°C for 30 minutes, then heat it to 1400°C for 40 minutes, hold it for 20-60 minutes, then heat it to 1600-2100°C for 90 minutes, hold it for 2-8 hours, and finally cool it to 1000°C for 40 minutes and cool it with the furnace.

[0057] (5) Polish with 800#, 1200#, and 2000# sandpaper respectively, ultrasonically wash with water, and air dry. Place the obtained cathode in a flat diode structure to test the DC current emission density.

[0058] Example 6

[0059] (1) Under an argon atmosphere, zirconium carbide, hafnium carbide, and titanium carbide were respectively mixed with graphite at a Zr / Hf / Ti to C molar ratio of 0.7:1.3 (denoted as Zr). 0.7 C 1.3 Hf 0.7 C 1.3 Ti 0.7 C 1.3 Place 10g of the mixture into a ball mill jar, and then add tungsten carbide grinding balls into the jar at a ball-to-material ratio of 2:1 to 8:1. Fix the ball mill jar onto a planetary ball mill, rotate at 150 r / min, and mill for 0.5 to 3 hours. Then stop the mill and collect the material under argon atmosphere.

[0060] (2) Under an argon atmosphere, 10%–40% of non-stoichiometric carbide powder (Zr) 0.7 C 1.3 Hf 0.7 C 1.3 Ti 0.7 C 1.3 20g of tungsten powder (60%–90%) was placed in a ball mill jar, and tungsten carbide grinding balls were added to the jar at a ball-to-powder ratio of 2:1–8:1. The ball mill jar was then fixed on a planetary ball mill at a speed of 350 r / min for 4–10 hours. After milling, the mill was stopped, and the material was collected under argon atmosphere.

[0061] (3) The mixture prepared in step (2) is put into a mold for cold pressing. At room temperature, a mold with a diameter of Φ3mm is selected, the pressure is 200MPa, the pressure is held for 3 to 5 minutes, and then the pressure is released and the mold is demolded to prepare a blank.

[0062] (4) Place the billet prepared in step (3) into a vacuum sintering furnace, heat it to 1000°C for 30 minutes, then heat it to 1400°C for 40 minutes, hold it for 20-60 minutes, then heat it to 1600-2100°C for 90 minutes, hold it for 2-8 hours, and finally cool it to 1000°C for 40 minutes and cool it with the furnace.

[0063] (5) Polish with 800#, 1200#, and 2000# sandpaper respectively, ultrasonically wash with water, and air dry. Place the obtained cathode in a flat diode structure to test the DC current emission density.

[0064] Comparative Example 1

[0065] (1) Under an argon atmosphere, 20g of 10%–40% zirconium carbide, hafnium carbide, titanium carbide, and 60%–90% tungsten powder are placed into a ball mill jar. Tungsten carbide grinding balls are then added to the jar at a ball-to-material ratio of 2:1–8:1. The ball mill jar is then fixed on a planetary ball mill at a speed of 350 r / min. After 4–10 hours of ball milling, the mill is stopped, and the material is collected under an argon atmosphere.

[0066] (2) The mixture prepared in step (1) is put into a mold for cold pressing. At room temperature, a mold with a diameter of Φ3mm is selected, the pressure is 200MPa, the pressure is held for 3 to 5 minutes, and then the pressure is released and the mold is demolded to prepare a blank.

[0067] (3) Place the billet prepared in step (2) into a vacuum sintering furnace, heat it to 1000℃ for 30 minutes, then raise it to 1400℃ for 40 minutes, hold it for 20-60 minutes, raise it to 1600-2100℃ for 90 minutes, hold it for 2-8 hours, and finally cool it down to 1000℃ for 40 minutes and cool it with the furnace.

[0068] (4) Polish with 800#, 1200# and 2000# sandpaper respectively, ultrasonically wash with water, and air dry. Place the obtained cathode in a flat diode structure to test the DC current emission density.

[0069] Table 1 shows the emission performance of non-stoichiometric carbide-doped tungsten-based thermionic cathodes in various examples of the present invention.

[0070]

Claims

1. A method for preparing a non-stoichiometric carbide-doped tungsten-based thermal cathode material, characterized in that, The specific steps are as follows: (1) Preparation of non-stoichiometric carbide powder: Zirconium carbide, hafnium carbide and titanium carbide are mixed with their respective hydrides in proportion to obtain C "deficient" non-stoichiometric carbide powder; Zirconium carbide, hafnium carbide and titanium carbide are mixed with graphite in proportion to obtain metal element "deficient" non-stoichiometric carbide powder; (2) Preparation of precursor powder: The non-stoichiometric carbide powder with C "deficient" or the non-stoichiometric carbide powder with metal element "deficient" prepared in step (1) is mechanically mixed with micron-sized tungsten powder to obtain non-stoichiometric carbide doped tungsten precursor powder. (3) Molding: The precursor powder obtained in step (2) is placed into a mold and pressed into a green body; (4) Vacuum sintering: The blank formed by molding in step (3) is subjected to vacuum high-temperature sintering to obtain a non-stoichiometric carbide-doped tungsten-based hot cathode; In step (1), the molar ratio of Zr / Hf / Ti to C in the non-stoichiometric carbide powder with "C absence" is 1.3:0.7~1.1:0.9, and the molar ratio of Zr / Hf / Ti to C in the non-stoichiometric carbide powder with "metal element absence" is 0.7:1.3~0.9:1.

1.

2. The method according to claim 1, characterized in that, In step (1), the non-stoichiometric carbide powder is obtained by high-energy ball milling. The specific method is as follows: under the protection of argon atmosphere, the non-stoichiometric carbide powder with C "deficient" and the non-stoichiometric carbide powder with metal element "deficient" are respectively subjected to high-energy ball milling, with a ball-to-material ratio of 2:1 to 8:1, a ball milling time of 0.5 to 3 hours, and a rotation speed of 150 r / min.

3. The method according to claim 1, characterized in that, In step (2) of the precursor powder preparation, non-stoichiometric carbides account for 10% to 40% of the total material, and the remainder is tungsten powder.

4. The method according to claim 1, characterized in that, The precursor powder in step (2) is obtained by high-energy ball milling. The specific method is as follows: under the protection of argon atmosphere, non-stoichiometric carbide and tungsten powder are subjected to high-energy ball milling with a ball-to-material ratio of 2:1 to 8:1, a ball milling time of 4 to 10 hours, and a rotation speed of 350 r / min.

5. The method according to claim 1, characterized in that, The molding method in step (3) is as follows: under the protection of argon atmosphere, a mold with a diameter of Φ3 mm is selected to press the precursor powder into a green blank, with a pressure of 200 MPa and a holding pressure of 3~5 min.

6. The method according to claim 1, characterized in that, The vacuum sintering method in step (4) is as follows: the compact is placed in a vacuum tungsten wire sintering furnace for matrix sintering at a temperature of 1600~2100 ℃, with a holding time of 2~8 h, and then cooled to 1000 ℃ for the last 40 min, followed by furnace cooling. The vacuum level must be maintained at 5×10⁻⁶ throughout the sintering process. -3 Pa or above.

7. The non-stoichiometric carbide-doped tungsten-based hot cathode material prepared by the method according to any one of claims 1-6.

8. The application of the non-stoichiometric carbide-doped tungsten-based thermal cathode material prepared by the method according to any one of claims 1-6, wherein the non-stoichiometric carbide powder is Zr 1.2 C 0.8 The non-stoichiometric carbide-doped tungsten-based hot cathode material prepared by this process was applied to a magnetic plasma thruster. Operating in the high-temperature environment of the corresponding magnetic plasma thruster, it exhibited good emission performance, with an emission current density of 1.63 A / cm² at 1600℃. 2 .

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