Method for preparing beta-SiAlON multiphase material by using fly ash
A technology for fly ash and carbon powder is applied in the field of preparing β-SiAlON composite materials, which can solve the problems of inability to synthesize β-SiAlON in large quantities, low temperature range, large energy consumption, etc., so as to optimize the synthesis process of carbothermal reduction and nitridation. , the effect of increasing added value and reducing harm to the environment
Active Publication Date: 2015-06-17
PEKING UNIV
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Problems solved by technology
[0026] The disadvantages of this patent: (1) fly ash microbeads contain magnetic beads, and the content of Fe and its oxides reaches 1-5%, which is not conducive to the synthesis of sialon and needs to be removed; (2) the content of carbon powder in the formula is too high , it is easy to generate carbides in the synthesis, and the heat preservation and carbon removal in the later stage consume a lot of energy, which is not environmentally friendly
(3) The temperature range of 1300°C-1500°C in this method is low, and β-SiAlON cannot be synthesized in large quantities at 1300-1400°C
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Embodiment 1
[0056] 1. The β-SiAlON composite material was prepared by using the fly ash of Shanxi Shuozhou Shentou Power Plant. The chemical composition of the fly ash was obtained by X-ray fluorescence spectroscopic analysis (XRF), as shown in Table 1.
[0057] Table 1: Chemical composition of fly ash
[0058] raw material
SiO 2
al 2 o 3
C
CaO
Fe 2 o 3
MgO
K 2 o
Fly ash fine powder (%)
49.6
42.5
1.28
2.36
2.17
0.37
0.8
[0059] 2. Preparation method:
[0060] The z value of β-SiAlON is designed to be 3, that is, the molar ratio of Si and Al elements in the raw material is 1:1. The specific preparation method is as follows (the process flow chart is shown in figure 1 ):
[0061] 1) Remove iron from fly ash by magnetic separation in advance, that is, prepare fly ash slurry with water and fly ash at a mass ratio of 1.5:1, and separate it by magnetic separation with a strong magnetic field of 8000Gs...
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Abstract
The present invention relates to a method for preparing a beta-SiAlON multiphase material by using fly ash. The method comprises: 1) carrying out magnetic separation and iron removing on fly ash, respectively crushing the obtained fly ash and carbon powder to achieve a particle size of less than or equal to 48 mum, mixing the fly ash fine powder and the carbon powder fine powder according to a mass ratio of 1:(0.1-0.25), adding water, and carrying out wet grinding; and 2) drying at a temperature of 100-120 DEG C, adding an adhesive to the dried mixture, carrying out pre-pressing molding under a pressure of 50-100 Mpa, sintering for 4-6 h at a temperature of 1450-1550 DEG C under a nitrogen atmosphere, and cooling to obtain the beta-SiAlON multiphase material. The method has characteristics of simpleness, wide raw material source, low cost and environmental protection, and provides important significance for development of waste utilization methods and increase of the added value of fly ash.
Description
technical field [0001] The invention relates to the field of recycling of industrial solid waste resources and preparation of new refractory materials, in particular to a method for preparing β-SiAlON composite materials by using fly ash. Background technique [0002] β-SiAlON is β-Si 3 N 4 with AlN, Al 2 0 3 solid solution of Si 6-z al z o z N 8-z Represents, where z represents the number of atoms replaced by Al. At 1750°C, Si 6-z al z o z N 8-z The composition ranges from z=0 to z=4.2. The properties of β-SiAlON are related to the z value. As the z value increases, the unit cell size increases, resulting in weakened bond strength and loose structure, thereby reducing the density, Young's modulus, flexural strength, and thermal expansion coefficient. In addition, the β-SiAlON phase grains are usually long columnar, and have the highest room temperature fracture toughness among various single-phase SiAlON. And the thermal expansion coefficient of β-SiAlON (2.7×...
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IPC IPC(8): C04B35/599C04B35/622
Inventor 王习东王博赵大伟王昊张作泰刘丽丽
Owner PEKING UNIV