Method for preparing oriented porous structure of precursor conversion type ceramic

A technology of precursor transformation and porous structure, which is applied in ceramic products, ceramic molding machines, manufacturing tools, etc., can solve the problems of different ceramic sizes and poor green body strength, and achieve low cost, low preparation temperature, and minimal material defects effect

Active Publication Date: 2019-03-29
CENT SOUTH UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Aiming at the defects of cracks of different sizes and poor green body strength in the ceramics prepared by the existing freez...

Method used

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  • Method for preparing oriented porous structure of precursor conversion type ceramic
  • Method for preparing oriented porous structure of precursor conversion type ceramic
  • Method for preparing oriented porous structure of precursor conversion type ceramic

Examples

Experimental program
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Effect test

example 1

[0055] Oriented porous silicon carbide fiber composite ceramics were prepared by freeze casting method using polycarbosilane as ceramic precursor.

[0056] Taking camphene as a solvent, adding the quality of the ceramic precursor powder / (the quality of the ceramic precursor powder+solvent quality)=0.2, adding carbon fibers with a length of 10-20 μm, the addition is 10wt% of the precursor powder, and Add 0.1wt.% organic dispersant (relative to the precursor powder), and stir magnetically at 60°C for 3h until a uniform and stable slurry is obtained.

[0057] Pour the slurry into a mold (aluminum mold) with a set temperature, and freeze and solidify under the control of the temperature field. The freezing rate was 20°C / min, respectively.

[0058] The solvent in the sample was removed by freeze drying to obtain a green body. The vacuum used in the freeze-drying process is 1 Pa, and the freezing and heating conditions are: -50-30°C, with an interval of 5°C as a temperature sectio...

example 2

[0064] Other conditions are uniform and identical to Example 1, the difference is that, when freezing and pouring, the mold used is a silicone mold. The compressive strength of the resulting product is higher than that of the sample obtained in Comparative Example 1, but lower than that of the sample obtained in Example 1. This exceeded experimental expectations.

example 3

[0066] Oriented porous silicon carbide ceramics were prepared by freeze-casting method using polycarbosilane as ceramic precursor.

[0067] Take camphene as solvent respectively, add the quality of ceramic precursor powder / (the quality of ceramic precursor powder+solvent quality)=0.1, add the silicon carbide micropowder of 0.5 μm, its addition is the ceramic precursor powder used 5wt.%, and 0.3wt% Texaphor 963 dispersant (relative to the ceramic precursor powder) was added, and magnetically stirred at 60°C for 3h until a uniform and stable slurry was obtained.

[0068] Pour the slurry into a mold (silicone mold) with a set temperature, and freeze and solidify under the control of the temperature field. The freezing rate was 20°C / min, respectively.

[0069] The solvent in the sample was removed by freeze drying to obtain a green body. The vacuum used in the freeze-drying process is 1 Pa, and the freezing conditions are: -50-30°C, with an interval of 5°C as a temperature secti...

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Abstract

The invention relates to a novel method for preparing porous ceramic by freeze casting, and belongs to the field of porous structure material preparation. The method includes the following steps: freeze-casting organic slurry containing ceramic precursors to obtain a body in a set temperature field, and freeze-drying the body to remove organic solvents to obtain a spare body; according to whetheror not the used organic slurry contains a crosslinking agent, using different crosslinking processed to obtain a to-be-cracked body; and finally, under the protective atmosphere, the to-be-cracked body obtained in the step two is cracked at 900 DEG C-160 DEG C until the ceramic precursors are completely converted into ceramic to obtain a finished product. The method adopts the ceramic precursor conversion mode to prepare the ceramic material, which greatly reduces the sintering temperature, reduces the energy consumption and significantly improves the performance of the obtained product, and has wide application biological materials, filter materials and microwave absorbing materials.

Description

technical field [0001] The method relates to a new preparation method of freezing and pouring porous ceramics. The invention belongs to the field of porous structure material preparation. Background technique [0002] In 2006, Deville et al. reported a method for preparing porous materials with a shell-like structure—frozen pouring (frozen pouring, also known as ice template method). The method is to add ceramic powder particles into water, camphene and other solvents to form a uniform and stable suspension. This approach allows the regulation of porous morphology and structure. But the problem is that the green body has poor strength after sintering, and the sintering temperature is as high as that of traditional powder. The mixing time course during the preparation of the slurry and the air present in the solution will remain in the green body during the pouring process and greatly affect the material properties. Moreover, the sintered green body has poor strength and ...

Claims

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Application Information

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IPC IPC(8): C04B35/565C04B35/584C04B35/80C04B38/06C04B38/10C04B35/622B28B1/00
CPCC04B35/565C04B35/584C04B35/622C04B35/80C04B38/10B28B1/007C04B2235/602C04B2235/6562C04B38/06
Inventor 周科朝薛凤丹张斗王小锋陈何昊
Owner CENT SOUTH UNIV
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