CN-121983481-A - Cathode assembly, preparation method thereof and electric thruster

CN121983481ACN 121983481 ACN121983481 ACN 121983481ACN-121983481-A

Abstract

The application provides a cathode assembly, a preparation method thereof and an electric thruster. The cathode assembly comprises a metal part, a boride ceramic part and a composite layer, wherein the metal part and the boride ceramic part are connected through the composite layer, the composite layer comprises a carbide ceramic transition layer and a brazing layer which are arranged in a laminated mode, the carbide ceramic transition layer is arranged between a connecting surface of the boride ceramic part and the brazing layer, and the brazing layer is arranged between the carbide ceramic transition layer and the connecting surface of the metal part. This can improve the service life and reliability of the cathode assembly.

Inventors

ZHAO RUISHAN
MA XIAOBO
HE CHUNHUA
ZOU ZEZHI
WANG ZHIJIAN
HU WENLONG
DENG YUEHUA
JIAO ZHAOLIN

Assignees

湖南稀土金属材料研究院有限责任公司

Dates

Publication Date: 20260505
Application Date: 20260212

Claims (10)

1. The cathode assembly is characterized by comprising a metal part, a boride ceramic part and a composite layer, wherein the metal part and the boride ceramic part are connected through the composite layer, the composite layer comprises a carbide ceramic transition layer and a brazing layer which are arranged in a stacked mode, the carbide ceramic transition layer is arranged between a connecting surface of the boride ceramic part and the brazing layer, and the brazing layer is arranged between the carbide ceramic transition layer and the connecting surface of the metal part.
2. The cathode assembly of claim 1, wherein the carbide ceramic material in the carbide ceramic transition layer comprises one or more of tantalum carbide, titanium carbide, zirconium carbide, hafnium carbide, and niobium carbide.
3. The cathode assembly of claim 1, wherein the carbide ceramic transition layer has a thickness of 10 μιη to 50 μιη.
4. A cathode assembly according to any one of claims 1 to 3, wherein the boride ceramic material in the boride ceramic part comprises one or more of cerium boride, lanthanum boride, yttrium boride, scandium boride, protactinium boride, niobium boride, zirconium boride, titanium boride, vanadium boride, chromium boride and hafnium boride.
5. The method for manufacturing a cathode assembly according to any one of claims 1 to 4, comprising the steps of: forming the carbide ceramic transition layer on the connecting surface of the boride ceramic part; forming a first brazing material layer on the surface of the carbide ceramic transition layer, which is far away from the boride ceramic part, and forming a second brazing material layer on the connecting surface of the metal part; and welding the metal part and the boride ceramic part through the first brazing material layer and the second brazing material layer.
6. The method of manufacturing of claim 5, wherein the carbide ceramic transition layer is formed by physical vapor deposition, the physical vapor deposition comprising the steps of: and placing the connecting surface of the boride ceramic part in a reaction chamber of physical vapor deposition, introducing working gas into the reaction chamber, reacting at least part of the working gas with metal atoms sputtered by a metal target to form carbide ceramic, and depositing the carbide ceramic on the connecting surface of the boride ceramic part to obtain the carbide ceramic transition layer.
7. The method of manufacturing of claim 6, wherein the physical vapor deposition satisfies one or more of the following conditions: (1) The temperature of the boride ceramic part is 200-300 ℃; (2) The vacuum degree of the reaction chamber is 5 multiplied by 10 -6 Pa~5×10 -3 Pa; (3) The bias voltage applied to the connecting surface of the boride ceramic part is-400V to-100V; (4) The flow rate of the working gas is 2 sccm-6 sccm; (5) The working gas comprises inert gas and carbon source gas, the carbon source gas comprises one or more of methane, ethylene, acetylene and ethane, and the flow ratio of the inert gas to the carbon source gas is 1:4-1:6.
8. The method of manufacturing as claimed in claim 5 or 6, wherein the method of welding the first brazing material layer and the second brazing material layer comprises vacuum brazing.
9. The method of manufacturing of claim 8, wherein the vacuum brazing satisfies one or more of the following conditions: (1) The vacuum degree of the vacuum brazing is 1 multiplied by 10 -3 Pa~10×10 -3 Pa; (2) The vacuum brazing adopts multistage heat treatment, and comprises a first heat treatment, a second heat treatment and a third heat treatment which are sequentially carried out; The first heat treatment is carried out at a rate of 3-8 ℃ to 350-500 ℃ for 20-40 min, the second heat treatment is carried out at a rate of 20-30 ℃ to 800-900 ℃ for 5-20 min, and the third heat treatment is carried out at a rate of 5-15 ℃ to 550-700 ℃ and then cooled to 0-30 ℃ along with the furnace.
10. An electric thruster comprising a cathode assembly according to any one of claims 1 to 4 or a cathode assembly produced by the method of any one of claims 5 to 9.

Description

Cathode assembly, preparation method thereof and electric thruster Technical Field The invention relates to the technical field of space electric thrust systems, in particular to a cathode assembly, a preparation method thereof and an electric thruster. Background The electric thruster ionizes the gas working medium and accelerates and sprays the plasma through the external strong electric field, and is widely applied to the fields of aviation, deep space exploration and the like. The cathode component is used as an electron source of the electric thruster and is an important component of the electric thruster, and the boride ceramic material has the advantages of high melting point, low electron work function, high chemical stability and the like and is often used as a cathode emission material. The boride ceramic cathode mainly faces some problems in the electric thruster, such as high brittleness and difficult processing of boride ceramic, when the boride ceramic cathode is independently used as a cathode component, serious ohmic loss can be generated through high current, the heat conductivity is limited, local hot spots and cold spots are easily formed in the cathode component, the electrothermal conversion efficiency is low, the problem of uneven and unstable electron emission and the like occur, reliable connection with metals with excellent electric conduction, heat conductivity and good plasticity such as tantalum, molybdenum and the like is needed, high-efficiency conversion of electric energy to heat energy is realized, uniform and stable working temperature of an emitter is ensured, and structural integrity is maintained. However, when the boride ceramic component and the metal component are welded together to form the cathode assembly, boron atoms can continuously diffuse to the metal component due to long-term service at a higher temperature, and a brittle phase of the metal boride is formed in the metal component, so that the cathode assembly is easy to generate brittle fracture and even failure, and the long service life and high reliability of the cathode assembly are limited. Disclosure of Invention Based on this, it is necessary to provide a cathode assembly, a method for manufacturing the same and an electric thruster aimed at improving the service life and reliability of the cathode assembly. In one aspect of the invention, a cathode assembly is provided that includes a metal component, a boride ceramic component, and a composite layer through which the metal component and the boride ceramic component are connected, the composite layer including a carbide ceramic transition layer and a braze layer disposed in a stacked arrangement, the carbide ceramic transition layer being disposed between a joining face of the boride ceramic component and the braze layer, the braze layer being disposed between the carbide ceramic transition layer and the joining face of the metal component. The cathode component is formed by connecting the metal component and the boride ceramic component together through the brazing layer, has the advantages of compatibility of emission function and heat and electric conductivity, and utilizes the high heat conductivity of the metal component to provide a low-resistance current and high heat conduction channel for the boride ceramic component, ensure the electrothermal conversion efficiency, help the boride ceramic component to quickly absorb partial generated thermal stress, optimize the thermal shock resistance of the cathode component and further improve the service life and reliability of the cathode component. In one embodiment, the carbide ceramic material in the carbide ceramic transition layer includes one or more of tantalum carbide, titanium carbide, zirconium carbide, hafnium carbide, and niobium carbide. In one embodiment, the carbide ceramic transition layer has a thickness of 10 μm to 50 μm. In one embodiment, the boride ceramic part includes one or more of cerium boride, lanthanum boride, yttrium boride, scandium boride, protactinium boride, niobium boride, zirconium boride, titanium boride, vanadium boride, chromium boride, and hafnium boride. In yet another aspect of the present invention, there is provided a method of manufacturing a cathode assembly, comprising the steps of: forming the carbide ceramic transition layer on the connecting surface of the boride ceramic part; forming a first brazing material layer on the surface of the carbide ceramic transition layer, which is far away from the boride ceramic part, and forming a second brazing material layer on the connecting surface of the metal part; and welding the metal part and the boride ceramic part through the first brazing material layer and the second brazing material layer. According to the preparation method of the cathode assembly, the formed carbide ceramic transition layer and the welded connection between the first brazing material layer and the second brazing material layer can form th