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Low-temperature preparation method of high-strength mullite ceramic

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: 2018-09-11
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] The method for preparing high-strength mullite ceramics at low temperature provided in this embodiment includes the following steps:

[0030] Step 1: Put kaolin, alumina, and industrial aluminum sol (solid content 24%) with masses of 100g, 52g, and 154g in the mixing tank, and add 18.90g of mineralizer anhydrous aluminum fluoride And 22.68g of sintering aid molybdenum trioxide, 400g of alumina grinding balls and 150ml of absolute ethanol were added as grinding media, and after continuous mixing for 24 hours, they were dried in an oven at 60℃ and sieved to obtain a mixture Powder

[0031] Step 2: Place the mixed powder described in the first step in a mold, press and shape it in an isostatic pressing equipment, with a pressure of 200 MPa, hold the pressure for 2 minutes, and demold after the pressing is completed to obtain a ceramic green body;

[0032] The third step: the ceramic green body of the second step is placed in a sealed alumina crucible and sintered in an air furna...

Embodiment 2

[0040] This embodiment is different from Embodiment 1 in 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 , The heat-resistant temperature reaches 1500℃.

Embodiment 3

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

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

[0045] The sintering process conditions in the third step are as follows: the temperature is increased to 900° C. at a rate of 3° C. / min, and the temperature is maintained for 3 hours.

[0046] The porous mullite ceramic prepared in this example has a porosity of 30%, a flexural strength of 67 MPa, and a fracture toughness of 1.1 MPa·m 1 / 2 , The heat-resistant temperature reaches 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 ·2SiO 2 ) Is Al 2 O 3 -SiO 2 A stable binary compound in the system, which 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 have outstanding mechanical properties and can maintain high strength at high temperatures. It is an excellent high-temperature structural material. [0003] At present, no matter what material system is used, the reaction temperature of mullite in the sintering process is often lower than its densification temperature, and the difficulty of sintering of mullite causes the preparation of dense mullite ceramics to require extremely high sintering temperature and energy consumption in pro...

Claims

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Application Information

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Patent Type & Authority Applications(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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