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Preparation method of silicon nitride whisker and silicon nitride nanowire reinforced silicon nitride-based wave-transparent ceramics

A silicon nitride nanometer and silicon nitride whisker technology is applied in the field of preparing silicon nitride-based wave-transmitting ceramics, which can solve the problems of insufficient mechanical properties, difficult mechanical properties and wave-transmitting properties of silicon nitride materials, and achieve good enhancement. Effects, microstructure and properties can be designed with high, low scattering effects

Active Publication Date: 2021-04-02
NORTHWESTERN POLYTECHNICAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] In order to avoid the deficiencies of the prior art, the present invention proposes a method for preparing silicon nitride-based wave-transmissive ceramics reinforced by silicon nitride whiskers and silicon nitride nanowires. Due to the insufficient mechanical properties of silicon nitride ceramics and silicon nitride composite ceramics, and the difficulty in synergy between the mechanical properties of silicon nitride materials and wave-transmitting properties, a structure of silicon nitride whiskers and silicon nitride nanowire-reinforced wave-transmitting ceramics is proposed. Design ideas and preparation process methods to realize the synergistic optimization of the mechanical properties and wave-transmitting properties of silicon nitride ceramics, and finally meet the application requirements of high-performance radome wave-transmitting materials with high temperature resistance, high strength, and excellent wave-transmitting properties

Method used

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  • Preparation method of silicon nitride whisker and silicon nitride nanowire reinforced silicon nitride-based wave-transparent ceramics
  • Preparation method of silicon nitride whisker and silicon nitride nanowire reinforced silicon nitride-based wave-transparent ceramics
  • Preparation method of silicon nitride whisker and silicon nitride nanowire reinforced silicon nitride-based wave-transparent ceramics

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Embodiment 1

[0028] Embodiment 1: add 18g solvent (water) in ball mill jar, the dispersant (ammonium polyacrylate) of 0.5g, the monomer (acrylamide) of 3.0g, the crosslinking agent (methylenebisacrylamide) of 0.2g , using hydrochloric acid and tetramethylammonium hydroxide to adjust the pH to 10. Gradually add 40g Si in 3 steps 3 N 4w (the average aspect ratio is 8) and 2.4g Si (the average particle size is 20um), ball milled for 12 hours, and prepared into a mixed slurry. In the slurry, add the initiator (ammonium persulfate) of 0.13g, put into the vacuum stirring tank after stirring, in 2 * 10 4 After defoaming under the pressure of Pa for 10 minutes, pour it into a mold, put it in an oven at 80°C for 10 minutes, and then demold it to obtain Si 3 N 4w - Si green body, dried at room temperature for 48 hours before use. Si 3 N 4w - Place the Si green body in a high-temperature box furnace, raise the temperature to 600 °C at a rate of 1 °C / min in an air atmosphere, keep it for 2 hour...

Embodiment 2

[0029] Embodiment 2: add 24.6g solvent (water) in ball mill jar, the dispersant (ammonium polyacrylate) of 0.3g, the monomer (acrylamide) of 4.2g, the crosslinking agent (methylenebisacrylamide) of 0.28g ), adjust the pH to 10 with hydrochloric acid and tetramethylammonium hydroxide. Add 38.4g Si gradually in 3 steps 3 N 4w (the average aspect ratio is 8) and 2.3g Si (the average particle size is 20um), and ball milled for 12 hours to prepare a mixed slurry. In the slurry, add the initiator (ammonium persulfate) of 0.2g, put into the vacuum stirring tank after stirring evenly, in 2 * 10 4 After defoaming under the pressure of Pa for 10 minutes, pour it into a mold, put it in an oven at 80°C for 10 minutes, and then demold it to obtain Si 3 N 4w - Si green body, dried at room temperature for 48 hours before use. Si 3 N 4w - Place the Si green body in a high-temperature box furnace, raise the temperature to 600 °C at a rate of 1 °C / min in an air atmosphere, keep it for 2 ...

Embodiment 3

[0030] Embodiment 3: add 24.6g solvent (water) in ball mill jar, the dispersant (ammonium polyacrylate) of 0.3g, the monomer (acrylamide) of 4.2g, the crosslinking agent (methylenebisacrylamide) of 0.28g ), adjust the pH to 10 with hydrochloric acid and tetramethylammonium hydroxide. Add 38.4g Si gradually in 3 steps 3 N 4w (the average aspect ratio is 8) and 6.9g Si (the average particle size is 12um), and ball milled for 12 hours to prepare a mixed slurry. In the slurry, add the initiator (ammonium persulfate) of 0.2g, put into the vacuum stirring tank after stirring evenly, in 2 * 10 4 After defoaming under the pressure of Pa for 10 minutes, pour it into a mold, put it in an oven at 80°C for 10 minutes, and then demold it to obtain Si 3 N 4w - Si green body, dried at room temperature for 48 hours before use. Si 3 N 4w - Place the Si green body in a high-temperature box furnace, raise the temperature to 600 °C at a rate of 1 °C / min in an air atmosphere, keep it for 2 ...

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Abstract

The invention relates to a preparation method for silicon nitride whisker and silicon nitride nanowire enhanced silicon nitride base wave-transparent ceramics. The preparation method comprises the following steps: firstly, adopting a gel injection molding technology to prepare an Si3N4w-Si green body, through oxidization adhesive removal, carrying out high-temperature nitridation under nitrogen atmosphere to enable Si powder to be converted into Si3N4nw to obtain an Si3N4w-Si3N4nw enhanced body prefabricating body; then, adopting a PIP (Polymer Infiltration and Pyrolysis) technology to preparean Si3N4 matrix in the prefabricating body; finally, obtaining the silicon nitride whisker and silicon nitride nanowire enhanced silicon nitride base wave-transparent ceramics. According to the preparation method, the solid phase volume fraction of slurry and the relative content of Si3N4w and Si powder in the slurry are respectively regulated and controlled to select different Si3N4w and Si powder, Si powder nitridation technologies are regulated and controlled, and therefore, the design and the optimization of the total volume fraction of the enhanced body, the relative content of Si3N4w and Si3N4nw in the enhanced body and the size and the morphology of Si3N4w and Si3N4nw can be realized. Therefore, the microscopic structure and the performance designability of the prepared silicon nitride wave-transparent material are good.

Description

technical field [0001] The invention belongs to a method for preparing silicon nitride-based wave-transparent ceramics, and relates to a method for preparing silicon nitride-based wave-transparent ceramics reinforced by silicon nitride whiskers and silicon nitride nanowires. Background technique [0002] The radome is an important component to protect the aircraft's radar antenna from working normally in the service environment. It uses wave-transparent materials to realize electromagnetic signal transmission. With the development of high-speed aircraft, the ever-increasing flight speed and harsh service environment put forward strict requirements on the thermal protection performance, mechanical performance and environmental performance of wave-transparent materials. The development of high-temperature wave-transparent materials with excellent comprehensive properties has become the difficulty and focus of research. [0003] Among the many high-temperature wave-transparent...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/80C04B35/81C04B35/584C04B35/622
CPCC04B35/589C04B35/622C04B2235/6562C04B2235/6567C04B2235/524C04B2235/5276C04B2235/616
Inventor 成来飞李明星叶昉刘永胜张立同
Owner NORTHWESTERN POLYTECHNICAL UNIV