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Preparation method of homogenized large-size silicon nitride ceramic plate

A technology of homogenization and large size is applied in the field of preparation of homogenized large size silicon nitride ceramic plates, which can solve the problems of inability to prepare dense materials and so on.

Pending Publication Date: 2021-12-17
AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The published patent CN105198475A only discloses a method for preparing porous materials, but cannot prepare dense materials

Method used

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  • Preparation method of homogenized large-size silicon nitride ceramic plate
  • Preparation method of homogenized large-size silicon nitride ceramic plate
  • Preparation method of homogenized large-size silicon nitride ceramic plate

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preparation example Construction

[0025] A method for preparing a homogenized large-scale silicon nitride-based ceramic flat plate, comprising the following steps:

[0026] (1) Slurry preparation: Mix silica sol, water-soluble macromolecular organic matter, sintering aid and pickled silicon nitride ceramic powder in sequence, and then ball mill to obtain slurry. The proportion of the slurry components is: silica sol 20-30wt% (can be any value within this range, such as 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt% %, 29wt%, 30wt%), water-soluble macromolecular organic matter 2.1 ~ 4.0wt% (can be any value within this range, such as 2.1wt%, 2.5wt%, 3.0wt%, 3.5wt%, 4.0wt%) , 3.5-6.4wt% sintering aid (can be any value within this range, such as 3.5wt%, 3.6wt%, 3.7wt%, 3.8wt%, 3.9wt%, 4.0wt%), acid-washed silicon nitride Ceramic powder 70-80wt% (can be any value within this range, such as 70wt%, 71wt%, 72wt%, 73wt%, 74wt%, 75wt%, 76wt%, 77wt%, 78wt%, 79wt%, 80wt% ).

[0027]Wherein, the pH of si...

Embodiment 1

[0032] Step 1: Slurry preparation, polyvinyl alcohol, silica sol with a pH of 5.0 at a concentration of 20 wt%, acid-washed silicon nitride ceramic powder, and a sintering aid (alumina:yttrium oxide=1:3) are mixed according to a mass ratio of 4 :28:100:8: Mix evenly and ball mill to obtain silicon nitride ceramic slurry; the silicon nitride ceramic powder contains 20wt% of 0.5-0.8μm particles, 80wt% of 1-2μm particles, and the ball milling time is 60h .

[0033] Step 2: Preparation of homogeneous silicon nitride ceramics. The above slurry is vacuum degassed for 20 minutes and poured into an aluminum mold with a bottom thickness of 3 mm (pouring time is 5 minutes), so that it is rapidly suspended in liquid nitrogen (using a liquid nitrogen tank Fix the support with a network structure and suspend) fully solidify for 1 hour and then demould to obtain a green body; dry the green body at 40°C and a humidity of 70% for 60 hours, and sinter at 1750°C for 6 hours to prepare homogeneo...

Embodiment 2

[0035] Step 1: Slurry preparation, polyvinyl alcohol and polyglycerol, silica sol with a pH of 5.5 at a concentration of 25 wt%, acid-washed silicon nitride ceramic powder, and sintering aid (aluminum oxide) in a mass ratio of 5:28:100 :6: Mix evenly and perform ball milling to obtain silicon nitride ceramic slurry; wherein the silicon nitride ceramic powder contains 15 wt% of particles of 0.5-0.8 μm, 85 wt% of particles of 1-2 μm, and the ball milling time is 96 hours.

[0036] Step 2: Preparation of silicon nitride ceramics. The above-mentioned slurry is vacuum degassed for 40 minutes and poured into an aluminum mold with a bottom thickness of 4 mm (pouring time is 8 minutes), so that it is quickly suspended in liquid nitrogen and fully solidified for 2 hours before demolding to obtain a blank body; the green body was dried at 35°C and humidity 65% ​​for 96 hours, and then sintered at 1800°C for 5 hours to prepare a homogeneous silicon nitride ceramic material.

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Abstract

The invention discloses a preparation method of a homogenized large-size silicon nitride-based ceramic plate, which belongs to the technical field of functional ceramic preparation, and is characterized in that silica sol, a water-soluble macromolecular organic matter, a sintering aid and acid-washed silicon nitride ceramic powder are uniformly mixed, the acid-washed silicon nitride ceramic powder comprises 0.5-0.8 [mu] m particles and 1-2 [mu] m particles, and ball milling is carried out to obtain slurry; and vacuum degassing is performed on the slurry and then injected into a mold, the slurry is enabled to suspend in liquid nitrogen for full curing molding, then demolding is conducted to obtain a green body, and the green body is dried and sintered to obtain the homogenized silicon nitride-based ceramic plate material.

Description

technical field [0001] The invention belongs to the technical field of preparation of functional ceramics, in particular to a method for preparing a homogenized large-size silicon nitride ceramic flat plate. Background technique [0002] With the development of new missiles towards supersonic speed, hypersonic speed and long-duration flight, more stringent requirements are put forward for the selection of antenna window materials. Research on the material system found that silicon nitride-based ceramic materials have excellent mechanical, thermal, and electrical properties, and at the same time, the decomposition temperature is above 1850 ° C, which is very suitable for use as antenna window materials for hypersonic tactical missiles. Therefore, this type of ceramic material has been is the focus of research in recent years. [0003] The antenna window of a hypersonic vehicle has a special-shaped structure and a complex shape. It is usually prepared by finishing a large-siz...

Claims

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Application Information

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IPC IPC(8): C04B35/584C04B35/622C04B35/64
CPCC04B35/584C04B35/622C04B35/64C04B2235/3418C04B2235/3217C04B2235/3225C04B2235/3224C04B2235/606C04B2235/96
Inventor 董衡李淑琴韩耀余娟丽张剑吕毅张昊
Owner AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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