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A method for preparing high-strength mullite ceramics at low temperature

A mullite and high-strength technology, used in the field of low-temperature preparation of high-strength mullite ceramics, can solve the problems of poor mechanical properties and high sintering temperature of dense mullite, and achieve the advantages of low cost, small sintering shrinkage and lower reaction temperature. Effect

Active Publication Date: 2020-06-30
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Aiming at the shortcomings of high sintering temperature and poor mechanical properties of dense mullite, the present invention adopts a technical solution to provide a method for preparing high-strength mullite ceramics at low temperature, which includes the following steps:

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] A method for preparing high-strength mullite ceramics at low temperature provided in this embodiment comprises the following steps:

[0030] The first step: put kaolin, alumina, and industrial aluminum sol (solid phase content 24%) with masses of 100g, 52g, and 154g respectively in the mixing tank, and add 18.90g of mineralizer anhydrous aluminum fluoride at the same time and molybdenum trioxide as a sintering aid with a mass of 22.68g, and then add 400g of alumina balls and 150ml of absolute ethanol as grinding media, after continuous mixing for 24 hours, dry in an oven at 60°C and sieve to obtain a mixed Powder;

[0031] The second step: put the mixed powder described in the first step in a mold, press and form it in an isostatic pressing equipment, the pressure is 200 MPa, keep the pressure for 2 minutes, demould after the pressing is completed, and obtain a ceramic green body;

[0032] The third step: the ceramic green body described in the second step is placed in...

Embodiment 2

[0040] The difference between this example and Example 1 is that the inorganic aluminum salt in the fourth step is aluminum chloride hexahydrate.

[0041] The porous mullite prepared in this example has a porosity of 10%, a flexural strength of 140MPa, and a fracture toughness of 2.3MPa m 1 / 2 , heat-resistant temperature up to 1500 ℃.

Embodiment 3

[0043] The difference between this example and Example 1 is that the masses of the kaolin, the alumina powder, and the industrial aluminum sol (solid phase content: 27%) in the first step are 100g, 20g, and 309g, respectively;

[0044] The molding pressure described in the second step is 100MPa, and the holding time is 3min;

[0045] The process condition of the sintering in the third step is to raise the temperature to 900° C. at a rate of 3° C. / min and keep the temperature for 3 hours.

[0046] The porous mullite ceramic prepared in this example has a porosity of 30%, a flexural strength of 67MPa, and a fracture toughness of 1.1MPa m 1 / 2 , heat-resistant temperature up to 1500 ℃.

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Abstract

The invention provides a low-temperature preparation method of high-strength mullite ceramic. Kaolin, aluminum sol and aluminum oxide are taken as raw materials, under the action of a mineralizing agent and sintering aids, mullite porous ceramic with needle-shaped crystal whiskers is firstly synthesized under low temperature, space is provided for the growth of the crystal whiskers by using internal pores of the materials to allow the crystal whiskers grow fully, mullite precursors with higher reaction activities are soaked, and finally the high-strength mullite ceramic is obtained through secondary low-temperature sintering. The method has the advantages that the prices of the raw materials are cheap, sources of the raw materials are extensive and easy to obtain, the costs are lower, andthe preparation temperature is lower, so that production consumption is greatly reduced, the process is simple, equipment demands are low, the improvement of material strength and toughness are achieved simultaneously by the in-situ growing crystal whiskers, during the sintering process, the shrinkage of products is less, and net size shaping can be achieved.

Description

technical field [0001] The invention relates to the technical field of ceramic material preparation, in particular to a method for preparing high-strength mullite ceramics at low temperature. Background technique [0002] Mullite (3Al 2 o 3 2SiO2 2 ) is Al 2 o 3 -SiO 2 A binary compound that is stable in the system, has the advantages of high melting point (1830°C), low thermal conductivity, small thermal expansion coefficient, good chemical stability and good thermal stability. Dense mullite ceramics has outstanding mechanical properties and can maintain high strength at high temperatures, making it an excellent high-temperature structural material. [0003] At present, no matter what kind of material system is used, the mullite reaction temperature in the sintering process is often lower than its densification temperature, and the difficulty of sintering of mullite leads to the preparation of dense mullite ceramics requires extremely high sintering temperature, and t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/185C04B35/81C04B35/84
CPCC04B35/185C04B35/803C04B2235/3217C04B2235/3256C04B2235/349C04B2235/443C04B2235/444C04B2235/445C04B2235/96
Inventor 叶枫马杰张标叶健刘强高晔
Owner HARBIN INST OF TECH
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