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Spinning-grade polycarbosilane and preparation method thereof

A technology of polycarbosilane and spinning grade, which is applied in the field of preparing silicon carbide ceramic materials by the precursor conversion method, can solve the problems of increasing the complexity of the synthesis process and not being suitable for the spinning process, so as to promote full participation in the homogeneous reaction and avoid undesired Effect of uniform reaction and improvement of thermal conductivity

Active Publication Date: 2021-11-19
湖南希里肯科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, it fails to fundamentally solve the problems in the synthesis of PCS, increases the complexity of the synthesis process, and some of the obtained products are not suitable for the subsequent spinning process, so no engineering application reports have been seen.

Method used

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  • Spinning-grade polycarbosilane and preparation method thereof
  • Spinning-grade polycarbosilane and preparation method thereof
  • Spinning-grade polycarbosilane and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] S1: Dry 20kg of PDMS in vacuum at 180°C for 4h.

[0053] S2: Mix the dried PDMS and 5mm and 10mm copper balls according to the volume ratio of 4:1, wherein the volume ratio of the 5mm and 10mm copper balls is 2:1, then put them into an autoclave, and seal it.

[0054] S3: Vacuumize the autoclave, fill it with nitrogen, and repeat the process 3 times to complete the gas replacement in the autoclave, and then fill it with 3MPa nitrogen.

[0055] S4: In the first stage of reaction, start stirring at 60 rpm, raise the temperature to 430°C at 1°C / min, keep it warm for 3 hours, turn off the heating, and lower the temperature.

[0056] S5: When the temperature drops below 50°C, open the vent valve to release the gas in the kettle until the pressure in the kettle is equal to the ambient atmospheric pressure, and then refill the inert gas to 1MPa.

[0057] S6: Turn on stirring at a stirring speed of 300 rpm, raise the temperature to 480°C at 8°C / min, keep it warm for 8 hours, t...

Embodiment 2

[0063] S1: 20kg of PDMS was vacuum-dried at 150°C for 6h.

[0064] S2: Mix the dried PDMS and 10mm copper balls at a volume ratio of 2:1, then put them into an autoclave, and seal them.

[0065] S3: Vacuumize the autoclave, fill it with nitrogen, and repeat the process 3 times to complete the gas replacement in the autoclave, and then fill it with 2MPa nitrogen.

[0066] S4: In the first stage of reaction, start stirring at a stirring speed of 200 rpm, raise the temperature to 400°C at 5°C / min, keep it warm for 5 hours, turn off the heating, and lower the temperature.

[0067] S5: When the temperature drops below 50°C, open the vent valve, release the gas in the kettle until the pressure is equal to the ambient atmospheric pressure, and then refill nitrogen to 3MPa.

[0068] S6: Turn on stirring at 200 rpm, raise the temperature to 460°C at 10°C / min, keep it warm for 10 hours, turn off the heating, and lower the temperature.

[0069] S7: When the temperature drops below 50° ...

Embodiment 3

[0073] S1: Dry 20kg of PDMS in vacuum at 100°C for 8h.

[0074] S2: Mix the dried PDMS and 10mm aluminum balls at a volume ratio of 10:1, then put them into an autoclave, and seal them.

[0075] S3: Vacuumize the autoclave and fill it with nitrogen, repeating this process 3 times to complete the gas replacement in the autoclave, and then fill it with 0.5MPa nitrogen.

[0076] S4: In the first stage of reaction, start stirring at 300 rpm, raise the temperature to 440°C at 10°C / min, keep it warm for 1 hour, turn off the heating, and lower the temperature.

[0077] S5: When the temperature drops below 50°C, open the vent valve, release the gas in the kettle until the pressure is equal to the ambient atmospheric pressure, and then refill nitrogen to 0.5MPa.

[0078] S6: Turn on stirring at 60 rpm, raise the temperature to 500°C at 1°C / min, keep it warm for 1 hour, turn off the heating, and cool down.

[0079] S7: When the temperature drops below 50° C., open the vent valve to re...

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Abstract

The invention provides a synthetic method of spinning-grade polycarbosilane (PCS), metal balls with high thermal conductivity are mixed with polydimethylsilane (PDMS) according to a certain proportion, so that the thermal conductivity of materials in a reaction kettle is improved, the temperature gradient in the materials is reduced or eliminated, the reaction uniformity is improved, and coking caused by local overheating is avoided. According to the characteristics of the synthesis reaction process, the synthesis reaction process is divided into two stages of PDMS pyrolysis-structure rearrangement and low-molecular-weight PCS polycondensation, after the PDMS pyrolysis and rearrangement reaction process is completed, cooling is carried out, H2, CH4 and low-boiling-point silane generated in the reaction kettle are discharged, and forward reaction equilibrium of the second stage mainly including the polycondensation reaction is promoted. The method has the advantages of improving the softening point of spinning-grade PCS, inhibiting molecular weight distribution broadening and improving the synthesis yield, and is simple in process and suitable for engineering.

Description

technical field [0001] The invention generally relates to the technical field of preparing silicon carbide ceramic materials by a precursor conversion method, in particular to a spinning-grade polycarbosilane and a preparation method thereof. Background technique [0002] SiC fiber has the advantages of high temperature resistance, oxidation resistance, low chemical activity, high specific strength and specific modulus, etc. f It is an important component of SiC composite materials and is widely used in high-temperature components in aerospace, nuclear industry, cutting-edge weaponry and other fields. [0003] Currently, the only method that can achieve the preparation of commercial-grade continuous SiC fibers (fiber diameter ≤ 15 μm) is the precursor conversion method. The method was pioneered by Professor Yajima of Japan, and mainly includes four main processes of synthesis of the precursor polycarbosilane (PCS), melt spinning, non-melting treatment and high-temperature f...

Claims

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Application Information

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IPC IPC(8): C08G77/60
CPCC08G77/60Y02P70/62
Inventor 张城
Owner 湖南希里肯科技有限公司