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Preparation method of silicon carbide fibers with silicon nitride surface layer

A technology of silicon carbide fiber and silicon nitride, which is applied in the field of preparation of silicon carbide fiber, can solve the problems of reducing the mechanical properties and absorbing ability of the fiber, the difficulty of uniform and continuous coating of deposited thickness, and incomplete coating of fiber coating, etc. Achieve the effects of convenient implementation, low manufacturing cost, high temperature resistance and good oxidation resistance

Active Publication Date: 2012-09-19
NAT UNIV OF DEFENSE TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But for the preparation of silicon nitride (Si 3 N 4 ) surface layer, the CVD process not only requires special process equipment, but also has difficulties in controlling the deposition thickness and ensuring uniform and continuous coating, which may lead to problems such as incomplete fiber coating coating inside the bundle, while the PIP process requires Cracking may cause greater damage to the fiber, and it is easy to form a strong interface bond, with an obvious skin-core structure, which may reduce the mechanical properties and wave-absorbing ability of the fiber

Method used

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  • Preparation method of silicon carbide fibers with silicon nitride surface layer
  • Preparation method of silicon carbide fibers with silicon nitride surface layer
  • Preparation method of silicon carbide fibers with silicon nitride surface layer

Examples

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Embodiment 1

[0020] This embodiment includes the following steps:

[0021] (1) Put the polysilane in the reaction kettle, vacuumize it five times, fill it with 99.999% high-purity nitrogen, heat it to 400°C for 2 hours, dissolve the crude product in toluene and filter it, then heat the filtrate to 300°C for reduction Pressure distillation, removal of solvent and low molecular substances, cooling to obtain polycarbosilane (PCS);

[0022] (2) Place the polycarbosilane obtained in step (1) in the melting drum of the melt spinning device, heat it to 300°C under the protection of high-purity nitrogen with a purity of 99.999%, and wait until it is completely melted into a uniform melt, then heat it at 280°C , under 0.4MPa, draw at a speed of 300m / min to obtain continuous PCS fibers;

[0023] (3) Place the continuous PCS fiber obtained in step (2) in a non-melting treatment device, vacuumize it, and fill it with high-purity nitrogen gas with a purity of 99.999%. After repeating three times, pass...

Embodiment 2

[0028] This embodiment includes the following steps:

[0029] Step (1) and (2) are operated with embodiment 1;

[0030](3) Place the continuous PCS fiber obtained in step (2) in a non-melting treatment device, heat it to 220 °C in an air atmosphere at a heating rate of 15 °C / hour, and heat-preserve and oxidize it for 4 hours to obtain a non-melting fiber;

[0031] (4) Place the non-melting fibers obtained in step (3) in a high-temperature atmosphere furnace, and raise the temperature to 1000°C at a rate of 150°C / hour in a mixed atmosphere of ammonia gas and nitrogen gas (volume ratio 1:1). Insulated at 1200°C for 2 hours to obtain Si 3 N 4 Surface SiC fiber.

[0032] The EDX analysis of the surface layer of the continuous SiC fiber obtained in this embodiment shows that the surface of the fiber is a silicon nitride structure, and the fiber diameter is 12 m, the tensile strength is 2.1GPa, the Young's modulus is 260GPa, the fiber oxygen content is 0.95wt%, the nitrogen con...

Embodiment 3

[0034] This embodiment includes the following steps:

[0035] Step (1) and (2) are operated with embodiment 1;

[0036] (3) The continuous PCS fiber obtained in step (2) is placed in an electron accelerator irradiation box, and after the irradiation dose reaches 10MGy, it is annealed to obtain an electron beam irradiation infusible fiber.

[0037] (4) Place the electron beam irradiated non-melting fibers obtained in step (3) in a high-temperature atmosphere furnace, and raise the temperature to 700 °C at a rate of 160 °C / hour in a mixed atmosphere of ammonia gas and argon gas (volume ratio 1:1). ℃, insulated at 1300℃ for 2h to obtain 3 N 4 Continuous SiC fibers on the surface.

[0038] The continuous SiC fiber that present embodiment makes, surface EDX analysis shows that fiber surface is silicon nitride structure, and fiber diameter is 11 m, the tensile strength is 2.6GPa, the Young's modulus is 285GPa, the fiber oxygen content is 0.62wt%, the nitrogen content is 4.36wt%...

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Abstract

The invention relates to a preparation method of silicon carbide fibers with a silicon nitride surface layer. The preparation method comprises the following steps of: using polycarbosilane (PCS) which is prepared by using organic silicon polymers through high-temperature cracking as raw materials, conducting melt-spinning to obtain continuous PCS polymer fibers, placing the continuous PCS polymerfibers in the atmosphere of air or activated gas for non-melting treatment, placing the non-melting fibers in a high-temperature atmosphere furnace for high-temperature nitration and decarbonization under the atmosphere of ammonia with certain concentration, and further sintering for densification at high temperature to obtain the silicon carbide fibers with the silicon nitride surface layer. Thepreparation method of the silicon carbide fibers with the silicon nitride surface layer has the advantages that the process and the equipment are simple, the cost of the prepared silicon carbide fibers is low and the resistivity is adjustable.

Description

technical field [0001] The present invention relates to a kind of preparation method of silicon carbide fiber, especially relate to a kind of 3 N 4 ) method for preparing silicon carbide (SiC) fibers on the surface. Background technique [0002] Silicon carbide (SiC) fiber is one of the important high-performance reinforced ceramic fibers, which has excellent strength, modulus, creep resistance, high temperature resistance and oxidation resistance, compatibility with ceramic matrix and high-frequency wave absorption. SiC fiber is an excellent functional structural material and has broad application prospects in many fields such as aerospace and atomic energy. The developed countries in the world have paid great attention to this. At present, Japan has realized the industrial production of SiC fiber and imposed a technical blockade on my country. In China, after more than 30 years of exploration and research, the National University of Defense Technology has independently ...

Claims

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Application Information

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IPC IPC(8): C04B35/565C04B35/622
Inventor 邵长伟王珊珊宋永才谢征芳王浩王军
Owner NAT UNIV OF DEFENSE TECH
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