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CN-122013082-A - Heat treatment method of lanthanum-tungsten hollow cathode

CN122013082ACN 122013082 ACN122013082 ACN 122013082ACN-122013082-A

Abstract

The invention relates to a heat treatment method of a lanthanum-tungsten hollow cathode, which belongs to the technical field of tungsten alloy heat treatment, wherein the lanthanum-tungsten hollow cathode is firstly pretreated and cleaned, then is placed in a protective atmosphere to sequentially perform one-stage heat treatment and two-stage heat treatment, wherein the one-stage heat treatment adopts a heating rate of 1-10 ℃ per second to 15-35 ℃, the heat preservation is carried out for 15-30 min, the two-stage heat treatment adopts a heating rate of 1-10 ℃ per second to 200-800 ℃, the heat preservation is carried out for 1-24 hours, and finally air cooling is carried out to room temperature. The heat treatment of the invention ensures that the grain surface orientation in the lanthanum-tungsten cathode changes and tends to be consistent, thereby improving the plasma ablation resistance of the lanthanum-tungsten cathode, and having great market demands and wide application prospects in the aerospace fields such as a magnetic plasma power thruster (MPDT).

Inventors

  • WANG GE
  • ZHANG BO
  • LI YONG
  • ZHOU CHENG
  • YANG ZHIMAO
  • KONG CHUNCAI
  • ZHANG XINWEI
  • WU PENG
  • CONG YUNTIAN
  • WANG BAOJUN

Assignees

  • 北京控制工程研究所

Dates

Publication Date
20260512
Application Date
20260317

Claims (10)

  1. 1.A heat treatment method of a lanthanum-tungsten hollow cathode is characterized by comprising the following steps: (1) Polishing the surface of the lanthanum-tungsten hollow cathode; (2) Cleaning and drying the lanthanum-tungsten hollow cathode obtained in the step (1); (3) Carrying out one-stage heat treatment on the lanthanum-tungsten hollow cathode obtained in the step (2), raising the temperature to 15-35 ℃ by adopting the heating rate of 1-10 ℃ per second, and preserving the temperature to 15-30 min; (4) And (3) performing two-stage heat treatment on the lanthanum-tungsten hollow cathode obtained in the step (3), raising the temperature to 200-800 ℃ by adopting the heating rate of 1-10 ℃ per second, preserving heat for 1-24h, and air-cooling to room temperature.
  2. 2. The heat treatment method of a lanthanum-tungsten hollow cathode according to claim 1, wherein the lanthanum-tungsten hollow cathode is a single-hole hollow cathode, and the mass fraction of lanthanum oxide is 0.5-3%.
  3. 3. The method of claim 1, wherein in the step (3), the temperature rise rate of the one-stage heat treatment is 1-5 ℃.
  4. 4. The method of claim 1, wherein in the step (3), the one-stage heat treatment temperature is 15-25 ℃.
  5. 5. The method of claim 1, wherein in the step (4), the temperature rise rate of the two-stage heat treatment is 1-5 ℃.
  6. 6. The method of claim 1, wherein in the step (4), the two-stage heat treatment temperature is 200-600 ℃.
  7. 7. The method for heat treatment of lanthanum tungsten hollow cathode according to claim 1, wherein the first-stage heat treatment and the second-stage heat treatment are performed in a mixed atmosphere of hydrogen and argon, and the air flow is 100-400 ml/min.
  8. 8. The method for heat treatment of lanthanum tungsten hollow cathode according to claim 7, wherein the air flow is 100-250 ml/min.
  9. 9. The method for heat treatment of lanthanum tungsten hollow cathode according to claim 7, wherein the hydrogen-argon mixed atmosphere has a hydrogen volume fraction of 5-20%.
  10. 10. A lanthanum tungsten hollow cathode is characterized in that the heat treatment method is used for heat treatment according to one of claims 1-9.

Description

Heat treatment method of lanthanum-tungsten hollow cathode Technical Field The invention belongs to the technical field of tungsten alloy heat treatment, and particularly relates to a heat treatment method of a lanthanum-tungsten hollow cathode. Background The magnetic plasma power thruster (MPDT) generates high-temperature arc ionization propellant through high current, injects energy, accelerates plasma by using the Lorentz force of a magnetic field and the current, generates thrust, and has the advantages of higher than impulse, larger thrust, light weight, long-time on-orbit work and the like. However, high power MPDT cathode ablation is severe, leading to lifetime problems that limit its widespread use. Currently, tungsten-based cathodes are one of the mainstream cathode materials for magnetic plasma power thrusters. The extreme service environment ensures that the cathode is required to promote electron emission at high temperature due to higher work function when maintaining electron emission, thereby aggravating ablation and seriously affecting equipment practicability. The anti-ablation performance of the cathode can be improved by adding low-melting-point low-work-function rare earth oxide. Thorium tungsten cathode performs best but because radioactivity needs to find other alternatives, lanthanum tungsten cathode becomes one of the alternative materials. However, by changing the content of the oxide and other modes, the anti-ablation performance of the lanthanum-tungsten cathode is improved, the processing difficulty and the cost are improved, and the conductive performance is greatly reduced due to the excessively high content. Disclosure of Invention The invention aims to provide a heat treatment method of a lanthanum-tungsten hollow cathode, which is used for carrying out secondary heat treatment on the lanthanum-tungsten hollow cathode, wherein the orientations of the crystal grain surfaces inside the heat treated lanthanum-tungsten hollow cathode are changed and tend to be consistent, so that the plasma ablation resistance of the lanthanum-tungsten cathode is improved, and the heat treatment method has huge market demands and wide application prospects in the aerospace fields such as a magnetic plasma power thruster (MPDT). The above object of the present invention is mainly achieved by the following technical solutions: A heat treatment method of a lanthanum-tungsten hollow cathode comprises the following steps: (1) Polishing the surface of the lanthanum-tungsten hollow cathode; (2) Cleaning and drying the lanthanum-tungsten hollow cathode obtained in the step (1); (3) Carrying out one-stage heat treatment on the lanthanum-tungsten hollow cathode obtained in the step (2), raising the temperature to 15-35 ℃ by adopting the heating rate of 1-10 ℃ per second, and preserving the temperature to 15-30 min; (4) And (3) performing two-stage heat treatment on the lanthanum-tungsten hollow cathode obtained in the step (3), raising the temperature to 200-800 ℃ by adopting the heating rate of 1-10 ℃ per second, preserving heat for 1-24h, and air-cooling to room temperature. The lanthanum-tungsten hollow cathode is a single-hole hollow cathode, and the mass fraction of lanthanum oxide is 0.5-3%. In the step (3), the temperature rising rate of the one-stage heat treatment is 1-5 ℃. In the step (3), the temperature of the one-stage heat treatment is 15-25 ℃. In the step (4), the temperature rising rate of the two-stage heat treatment is 1-5 ℃. In the step (4), the two-stage heat treatment temperature is 200-600 ℃. The first-stage heat treatment and the second-stage heat treatment are carried out in a hydrogen-argon mixed atmosphere, and the air flow is 100-400 ml/min. The air flow is 100-250 ml/min. The volume fraction of hydrogen in the hydrogen-argon mixed atmosphere is 5-20%. A lanthanum tungsten hollow cathode is heat treated according to the heat treatment method. Compared with the prior art, the invention has at least the following beneficial effects: The invention pre-treats the lanthanum tungsten hollow cathode for cleaning, then places the lanthanum tungsten hollow cathode in a protective atmosphere for low-temperature heat treatment, and divides the lanthanum tungsten hollow cathode into one-stage heat treatment and two-stage heat treatment, and finally air-cools the lanthanum tungsten hollow cathode to room temperature, so that the orientation of the integral crystal face inside the lanthanum tungsten hollow cathode deviates to the <001> direction, and the plasma ablation resistance of the lanthanum tungsten hollow cathode is improved. The magnetic plasma power thruster has huge market demands and wide application prospects in the aerospace fields such as a magnetic plasma power thruster (MPDT). The heat treatment method of the lanthanum-tungsten hollow cathode provided by the invention has the advantages of simple process and easiness in realizing industrial production. Drawings FIG. 1 is a pr