Method for preparing foamed ceramic through hydrophobic flocculation

A technology of foam ceramics and water flocculation, which is applied to ceramic products, other household utensils, household utensils, etc. It can solve the problems of complicated process operation and many types of organic matter addition, and achieve the effect of simple process, good fluidity and low viscosity

Active Publication Date: 2017-01-11
SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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AI-Extracted Technical Summary

Problems solved by technology

[0005] In view of the many problems in the preparation of foam ceramics by the existing mechanical foaming method, especially the need to add different organic substances to stabilize and solidify the foam re...
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Method used

[0037] A water-based ceramic slurry was prepared. The powders for preparing the water-based ceramic slurry can be oxide ceramic powders such as alumina, silicon oxide, and zirconia, or non-oxide ceramic powders such as silicon carbide and silicon nitride, or composite ceramic powders, and the solvent is water. The solid content of the water-based ceramic slurry is 15-50 vol.%, preferably 20-40%. The particle size of the ceramic powder can be 200-2000nm, and the foamed ceramics prepared in this range have a higher porosity an...
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Abstract

The invention relates to a method for preparing foamed ceramic through hydrophobic flocculation. The method comprises the steps that the solid content is controlled to be 15-50 vol.%, the pH value of water-based ceramic slurry is regulated to enable the surface of ceramic powder to be electrically charged so as to be uniformly dispersed in an electrostatic repulsion mode; surfactant of which an electric charge type is opposite to that of the ceramic powder surface is added into the water-based ceramic slurry, stirring or ball-mill mixing is conducted to enable the surfactant to be uniformly dispersed or adsorbed on the ceramic powder surface, and surfactant modified partially-hydrophobic ceramic slurry is obtained; the partially-hydrophobic ceramic slurry is subjected to mechanical stirring foaming, foam slurry is directly injected into a mold, the room-temperature in-situ solidification, then demoulding and drying are conducted, and after sintering is conducted, the foam ceramic is obtained. According to the method, by means of electrostatic repulsion, ceramic particles in the slurry reach a good dispersion effect, and the water based ceramic slurry which is low in viscosity and good in flowability is obtained.

Application Domain

Technology Topic

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  • Method for preparing foamed ceramic through hydrophobic flocculation
  • Method for preparing foamed ceramic through hydrophobic flocculation
  • Method for preparing foamed ceramic through hydrophobic flocculation

Examples

  • Experimental program(12)

Example Embodiment

[0041] Preparation of foam slurry. Specifically, the water-based ceramic slurry uniformly dispersed with the surfactant is mechanically stirred and foamed to obtain a foamed slurry. Wherein, the mechanical foaming is stirring for 1 to 5 minutes at a rotation speed of 600 to 2000 revolutions/minute. In the present invention, the hydrophobically modified particles can act as a particle stabilizer to stabilize foam.
[0042] Preparation of foam body. Specifically, the above-mentioned foam slurry is injected into a mold for forming, and cured (in-situ curing at room temperature), demolded, and dried to obtain a foam body. In the present invention, the foam slurry after mechanical stirring and foaming is injected into a porous vented mold and placed at room temperature. Under the mutual hydrophobic interaction between the hydrophobic particles, flocculation and coagulation are generated, and the mold can be demolded after 24 hours, thereby obtaining a certain strength Ceramic foam green body. The selected mold can be a porous and gas-permeable mold.
[0043] Sintering of ceramic foam. The invention sinters the foam body at high temperature to obtain foam ceramics. The invention utilizes the process of preparing foam ceramics by hydrophobic flocculation, and successfully prepares foam ceramics of different materials. For foam ceramics of different materials, the sintering temperature and sintering time are also different.
[0044] In general, the present invention utilizes the characteristic adsorption of surfactants on the surface of ceramic particles to partially hydrophobicize the particles. Without any gel curing system, the hydrophobicized particles achieve hydrophobic flocculation and combination under hydrophobic action, and the resulting foam ceramic The blank has a complete shape, no structural collapse and good workability. After the green body is sintered, the microstructure is uniform, the pores are basically closed pores, the pore walls are dense without windows, and the compressive strength is high. The foamed ceramics prepared by the method of the present invention only need to add a surfactant to achieve the effect of stabilizing and curing the foam. Through the Archimedes principle to measure the volume density and the scanning electron microscope to observe the microstructure, it can be seen that the porosity of the foamed ceramic prepared by the present invention is 50-95%, the pore diameter is 10-200μm, and the pore wall structure is complete and dense. The number of windows is small, and the structure is basically closed pores.

Example Embodiment

[0046] Example 1
[0047] (1) Preparation of slurry: use alumina powder with median particle size D50=450nm as raw material, use ultrapure water as solvent, and use 1mol/L HCl to adjust the pH value of the slurry (pH=5); prepare dispersion by ball milling Uniform ceramic slurry with a solid content of 30vol.%;
[0048] (2) Hydrophobic modification: add 0.1 wt.% (relative to the mass of the powder) dodecyl sulfate triethanolamine to the slurry, and continue ball milling for 10 minutes;
[0049] (3) Stirring and foaming: transfer the above hydrophobically modified ceramic powder slurry to a measuring cup, adjust the speed of the stirrer to 1000 rpm, and mechanically stir and foam for 2 minutes;
[0050] (4) Injection molding and curing: Inject the foam slurry into a porous metal mold lined with paper, leave it for 24 hours, demold, and dry at room temperature for 48 hours;
[0051] (5) Sintering: the foam ceramic green body is kept at 1550°C for 2 hours, and then cooled with the furnace to obtain alumina foam ceramic.

Example Embodiment

[0052] Example 2
[0053] The preparation process is similar to that of Example 1, except that 0.17 wt.% (relative to the mass of the powder) dodecyl sulfate triethanolamine is added to the slurry.
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PUM

PropertyMeasurementUnit
Aperture10.0 ~ 200.0µm
Median particle size450.0nm
Aperture size10.0 ~ 200.0µm
tensileMPa
Particle sizePa
strength10

Description & Claims & Application Information

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