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Alpha crystal form nano alumina porous ceramic with high apparent porosity and preparation method thereof

A technology of nano-alumina and porous ceramics, which is applied in the field of nano-porous materials, can solve the problems of lower mechanical properties of products at high temperature, low decomposition temperature or combustion temperature, and a large amount of ash left by combustibles. The effect of small scale and low cost of raw materials

Inactive Publication Date: 2015-11-18
HUBEI UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

If using porous templates or adding pore-forming agents to form pores, not only the preparation process is more complicated, but also the combustibles may leave a large amount of ash after burning; in addition, due to the low decomposition temperature or combustion temperature of most pore-forming agents, some Pores will collapse during porogen removal
The pore structure of the partial sintering method is mainly supported by the sintered neck between the raw material particles. The bonding strength of this porous skeleton structure decreases significantly with the increase of temperature during use, resulting in the mechanical properties of the product, especially the mechanical properties at high temperature. and the preparation process needs to be carefully controlled, too low temperature will easily cause the collapse of pores, and too high temperature will greatly reduce the porosity and form a large number of closed pores

Method used

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  • Alpha crystal form nano alumina porous ceramic with high apparent porosity and preparation method thereof
  • Alpha crystal form nano alumina porous ceramic with high apparent porosity and preparation method thereof
  • Alpha crystal form nano alumina porous ceramic with high apparent porosity and preparation method thereof

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Experimental program
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Effect test

Embodiment 1

[0027] (1) Weigh γ-Al 2 o 3 1.5 g of powder, without any further treatment, was filled into a graphite mold with an inner diameter of 12 mm.

[0028] (2) Place the filled graphite mold in a spark plasma sintering furnace, vacuum sinter at 1100°C under an axial load pressure of 100MPa, and hold for 3 minutes to obtain alumina porous ceramics.

[0029] Carrying out X-ray diffraction analysis test to the obtained sintered product shows that ( figure 1 ), γ-Al 2 o 3 The powder is completely transformed into α-Al at 1100°C 2 o 3 . Mercury porosimetry was used to characterize the pores of the sintered body obtained by sintering at 1100°C and sintering at 700°C under the same conditions. The results showed that: γ-Al 2 o 3 The pore diameter of the powder accumulation is enlarged after the phase transformation is completed, and the pore diameter of the alumina porous ceramic obtained by sintering at 1100°C is 40-130nm ( figure 2 ), and the open porosity is 98.5%. The sinter...

Embodiment 2

[0031] (1) Weigh γ-Al 2 o 3 1.5 g of powder, without any further treatment, was filled into a graphite mold with an inner diameter of 12 mm.

[0032] (2) Place the filled graphite mold in a spark plasma sintering furnace, vacuum sinter at 1250°C under an axial load pressure of 100MPa, and hold for 3 minutes to obtain alumina porous ceramics.

[0033] Mercury porosimetry was used to characterize the pores of the sintered body. The results showed that the open porosity of the prepared alumina porous ceramics was 96.8%, and the pore diameter of the porous ceramics was 50-120nm. The porosity of the prepared alumina porous ceramics was measured to be 38% by drainage method. The strength test shows that the prepared alumina porous ceramics has a flexural strength of 185MPa. The observation results of the sintered products by scanning electron microscopy showed that ( Figure 4 ): α-Al 2 o 3 The average grain size of the alumina is 80-150nm. Even at 1250°C and 100MPa pressure, ...

Embodiment 3

[0035] (1) Weigh γ-Al 2 o 3 1.5 g of powder, without any further treatment, was filled into a graphite mold with an inner diameter of 12 mm.

[0036] (2) Place the filled graphite mold in a spark plasma sintering furnace, vacuum sinter at 1100°C under an axial load pressure of 30MPa, and hold for 3 minutes to obtain alumina porous ceramics.

[0037] Mercury intrusion porosity was used to characterize the pores of the sintered body. The results showed that the open porosity of the prepared alumina porous ceramics was 98.7%, and the pore diameter of the porous ceramics was 20-140nm. The sintered product was observed by scanning electron microscope, and the results showed that the worm-like α-Al was formed in the sintered body. 2 o 3 Pore ​​framework, α-Al 2 o 3 The average grain size is 30~120nm. The porosity of the prepared alumina porous ceramics was measured to be 62% by drainage method. The strength test shows that the prepared alumina porous ceramics has a flexural str...

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Abstract

The invention discloses an alpha crystal form nano alumina porous ceramic with a high apparent porosity and a preparation method thereof, and belongs to the field of nano porous materials. The preparation method comprises the following steps: filling gamma-Al2O3 powder into a graphite mould, placing the mould into a discharging plasma sintering furnace, loading an axial load pressure of 30 to 100 MPa, sintering the powder in vacuum at a temperature of 1100 to 1250 DEG C, maintaining the temperature for 3 to 5 minutes; or placing a gamma-Al2O3 blank in a conventional air furnace, sintering the blank under zero pressure at a temperature of 1350 to 1450 DEG C, and maintaining the temperature for 30 to 120 minutes to obtain the alpha crystal form nano alumina porous ceramic with a high apparent porosity; wherein the average particle size of the porous ceramic is smaller than 160 nm, and the apparent porosity is more than 95%. The provided preparation method has the advantages of low cost and good repeatability. The porous structure is formed without any sintering aid or pore forming agent. The prepared alumina porous ceramic has the advantages of evenly-distributed pores, small pore diameter, high apparent porosity (more than 95%), and excellent mechanical properties.

Description

technical field [0001] The invention belongs to the field of nanoporous materials, and in particular relates to a high open porosity α crystal form nano-alumina porous ceramic and a preparation method thereof. Background technique [0002] Porous alumina ceramics refers to a type of ceramic material that uses alumina as the aggregate and forms a large number of interconnected or closed pores inside during the material molding and high-temperature sintering process. Due to the wide range of sources and low price of alumina, porous alumina ceramics are widely used in many fields such as gas and liquid filtration, purification and separation, chemical catalyst carriers, biological implant materials, sound absorption and shock absorption, and sensor materials. [0003] Porous α-Al 2 o 3 The preparation of ceramics mainly includes the molding of the green body, the formation of the pore structure and the sintering of the green body. Currently about porous α-Al 2 o 3 The meth...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B38/00C04B35/10
Inventor 熊焰刘冲王玲
Owner HUBEI UNIV OF TECH
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