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CN-121992532-A - PAN material efficient pre-oxidation method based on anode layer Hall ion source assistance and pre-oxidation wire

CN121992532ACN 121992532 ACN121992532 ACN 121992532ACN-121992532-A

Abstract

The invention provides an efficient pre-oxidation method and pre-oxidation wire of PAN material based on anode layer Hall ion source assistance, and relates to the technical field of carbon fiber preparation, wherein the method mainly comprises the steps of firstly placing PAN precursor or fabric in a vacuum chamber and heating to 180-270 ℃ for heat preservation; and finally starting an anode layer Hall ion source, and carrying out ion beam treatment on the PAN material for 5-60 minutes under the conditions that the ion source voltage is 100-1000V and the ion beam current is 0.5-3.0A. The invention realizes accurate injection of PAN molecular chain energy and obviously reduces the activation energy of cyclization reaction. Through the synergistic effect of heat energy and ion beam activation, the method not only greatly shortens the pre-oxidation time and reduces the energy consumption, but also effectively avoids the fiber etching damage easily caused by conventional plasmas through accurate energy level regulation.

Inventors

  • WANG SHAN
  • DAN MIN
  • JIN FANYA
  • WANG WENQIAN
  • HUAN HUAN
  • ZHANG HONG
  • CHEN LUNJIANG

Assignees

  • 核工业西南物理研究院

Dates

Publication Date
20260508
Application Date
20260309

Claims (10)

  1. 1. The efficient pre-oxidation method for the PAN material based on the assistance of the anode layer Hall ion source is characterized by comprising the following steps of: placing PAN material in a vacuum chamber, vacuumizing the vacuum chamber, and then heating to heat the PAN material to a pre-oxidation temperature which is 180-270 ℃ and preserving heat; introducing working gas into the vacuum chamber to maintain the pressure in the vacuum chamber at 0.5-5 Pa, wherein the working gas is inert gas or mixed gas of inert gas and reactive gas; Starting an anode layer Hall ion source, and treating the PAN material under the conditions that the ion source voltage is 100-1000V and the ion beam current is 0.5-3.0A, wherein the treatment time is 5-60 minutes.
  2. 2. The efficient pre-oxidation method for PAN materials based on anode layer hall ion source assistance according to claim 1, wherein the inert gas is one or a mixture of argon and helium.
  3. 3. The anode layer hall ion source assisted PAN material efficient pre-oxidation method according to claim 1, wherein the reactive gas is oxygen.
  4. 4. The efficient pre-oxidation method for PAN materials based on the assistance of the anode layer Hall ion source according to claim 3, wherein when the working gas contains oxygen, the anode layer Hall ion source works in a pulse mode, and the duty ratio is 5% -60%.
  5. 5. The efficient pre-oxidation method for PAN material based on the assistance of an anode layer Hall ion source according to claim 1, wherein the process of starting the anode layer Hall ion source to process the PAN material adopts a time sequence step method, and the method comprises the following steps: the method comprises the steps of performing first ion treatment under a first voltage in a pure inert gas atmosphere, wherein the first voltage is 400-1000V; And a second step of performing a second ion treatment under a second voltage in an oxygen-containing atmosphere, wherein the second voltage is 200-500V and the second voltage is lower than the first voltage.
  6. 6. The efficient pre-oxidation method for PAN material based on the assistance of an anode layer Hall ion source according to claim 1, wherein the process of starting the anode layer Hall ion source to process the PAN material adopts a time sequence step method, and the method comprises the following steps: the method comprises the steps of performing first ion treatment under a first voltage in a pure inert gas atmosphere, wherein the first voltage is 400-1000V; and secondly, in an oxygen-containing atmosphere, closing the ion source to perform thermal oxygen treatment.
  7. 7. The efficient pre-oxidation method for PAN materials based on the assistance of the anode layer Hall ion source according to claim 5 or 6, wherein the first ion treatment time of the first step is 10-30 minutes; And/or the treatment time of the second step is 10-30 minutes.
  8. 8. The efficient pre-oxidation method for PAN materials based on the assistance of the anode layer hall ion source according to claim 1, wherein after the anode layer hall ion source is started to process the PAN materials, the method further comprises: And closing the ion source, maintaining the temperature or adjusting the temperature to 200-280 ℃, and performing subsequent heat treatment in an oxygen-containing atmosphere under normal pressure or low vacuum environment for 10-120 minutes.
  9. 9. The efficient pre-oxidation method for PAN materials based on the assistance of the anode layer Hall ion source according to claim 1, wherein when the vacuum chamber is vacuumized, the vacuum is pumped until the background vacuum degree is lower than that Pa。
  10. 10. A pre-oxidized fiber prepared by the method of any one of claims 1 to 9.

Description

PAN material efficient pre-oxidation method based on anode layer Hall ion source assistance and pre-oxidation wire Technical Field The invention relates to the technical field of carbon fiber preparation, in particular to a PAN material efficient pre-oxidation method and pre-oxidation wire based on anode layer Hall ion source assistance. Background Polyacrylonitrile (PAN) -based carbon fiber has excellent properties such as high specific strength, high specific modulus, corrosion resistance, high temperature resistance and the like, and is an irreplaceable key material in the fields such as aerospace, national defense and military industry, sports equipment, high-end civil industry and the like. The preparation of the PAN-based carbon fiber mainly comprises the process links of precursor preparation, pre-oxidation, carbonization, graphitization and the like, wherein the pre-oxidation is taken as a key step from top to bottom, and the process control is closely related to the performance of the final carbon fiber. The nature of pre-oxidation is to convert linear PAN macromolecular chains into heat-resistant ladder-structured polymers by chemical reactions such as cyclization, dehydrogenation, oxidation, etc. The stable trapezoid structure can ensure that the fiber is not melted and decomposed in the subsequent carbonization process of up to thousands of DEG C, and maintains excellent mechanical properties and morphological structures. The pre-oxidation method commonly adopted in the industrial production at present is a hot air circulation heating method, wherein PAN materials are placed in a hot air environment of 200-300 ℃, and the pre-oxidation process is completed by precisely controlling a temperature rise program and residence time. Although this method is technically mature and widely used, its inherent limitations are also quite prominent. Firstly, the energy consumption is high, the efficiency is low, the pre-oxidation process is the most time-consuming link in the whole carbon fiber production chain, and a large amount of energy sources are required to be consumed for long-time heating maintenance, so that the production cost is high. Secondly, the reaction is severe and the control difficulty is high, the cyclization and oxidation reactions of PAN are strong exothermic reactions, the heat is transmitted from the surface of the fiber to the inside, the temperature difference between the inside and the outside of the fiber is easily caused, the reaction is not uniform, and if the heat cannot be timely led out, the local overheating is caused, and even the fiber is burnt or fused. In addition, the "sheath-core structure" is difficult to avoid, and because the diffusion rate of oxygen from the fiber surface to the core is far lower than the thermally induced cyclization reaction rate, a dense cyclization layer is often formed on the fiber surface layer and the oxygen is prevented from diffusing inwards, so that the core cyclization degree is insufficient, a remarkable "sheath-core structure" is formed, and the stress concentration point of the carbon fiber is formed and the mechanical property of the carbon fiber is seriously deteriorated. Finally, the process window is narrow, the process parameters such as temperature, time, tension and the like are mutually coupled and extremely fine to regulate and control, and the tiny deviation of any parameter can have obvious influence on the quality of the pre-oxidized fiber and the performance of the subsequent carbon fiber. To solve the above problems, a plasma-assisted pre-oxidation method may be employed. For example, PAN fibers are treated with radio frequency or microwave plasma at room temperature. However, these conventional plasma sources (such as rf plasma) have a wide ion energy distribution and poor directionality, and the bombardment effect of high-energy particles tends to be greater than that of chemical activation effects during PAN treatment, which easily causes damages such as fiber surface etching and excessive breakage of molecular chains, and conversely reduces the performance of the final carbon fiber. This etching effect is more pronounced, particularly in aerobic environments, and it is difficult to balance between efficiently initiating cyclization and maintaining the structural integrity of the fiber. In summary, the existing thermal oxidation technology has low efficiency and is easy to generate a sheath-core structure, while the conventional plasma assisted technology is difficult to avoid etching damage to the fiber due to the characteristics of the plasma source, and cannot achieve an ideal balance between efficient promotion of cyclization and perfect maintenance of the structural integrity of the fiber. Therefore, a novel plasma pre-oxidation technology which can realize accurate energy injection and has high-efficiency activation and mild treatment characteristics is developed, and the novel plasma pre-oxidation technology has