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Method for preparing porous silicon carbide ceramics by reaction sintering and micro-oxidation treatment

A porous silicon carbide and micro-oxidation technology, applied in the field of structural ceramics manufacturing, can solve problems such as unfavorable mass production, high sintering temperature, low production efficiency, etc., and achieve the effects of low cost, uniform pore size distribution, and improved strength

Active Publication Date: 2017-06-27
江西源瓷科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This method has a wide range of raw materials and good economy, but the pore size and pore size distribution of the porous silicon carbide material obtained by this method are controlled by the structure and properties of the original material.
Chinese patent 201110149191.4 discloses "a method for preparing high-strength porous silicon carbide ceramics". The precursor powder of silicon-resin core-shell structure is prepared by inclusion mixing process, and then molded, carbonized, and sintered at high temperature to obtain an average pore size of 100-300 μm , a porous silicon carbide ceramic with a porosity of about 80% and a strength of 10-30 MPa, but the process is complicated and the sintering temperature is too high
This method is a preparation method of porous silicon carbide used for automobile exhaust purification, high-temperature filtration and heat exchange, etc., but the process is complicated, the production efficiency is low, and the sintering temperature is too high, which is not conducive to large-scale production.
So far, there is no report at home and abroad on the method of preparing high-strength porous silicon carbide by reaction sintering combined with micro-oxidation treatment.

Method used

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  • Method for preparing porous silicon carbide ceramics by reaction sintering and micro-oxidation treatment
  • Method for preparing porous silicon carbide ceramics by reaction sintering and micro-oxidation treatment

Examples

Experimental program
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Effect test

example 1

[0025] (1) Weigh the molar ratio of Si: MCMB=1:1, mix the weighed two powders with absolute ethanol in a volume ratio of 1:3, ball mill for 24 hours, at 80°C Dry for 24 hours and pass through a 200-mesh sieve;

[0026] (2) molding the powder after ball milling under a pressure of 200MPa to obtain a green body;

[0027] (3) Place the obtained green body in a graphite crucible, and then place them together in an atmosphere sintering furnace, and raise the temperature to 1100° C. at a rate of 300° C. / h under the condition of flowing argon;

[0028] (4) Introduce a small amount of air into the furnace cavity to make it at a slight positive pressure of 0.01MPa, continue to heat up to 1450°C at a heating rate of 300°C, and keep it for 1h.

[0029] (5) Porous silicon carbide ceramics are obtained by cooling with the furnace.

[0030] The physical performance test and microstructure analysis of the porous silicon carbide ceramics obtained in this embodiment showed that the bending s...

example 2

[0032] (1) Weigh according to the molar ratio Si:MCMB=0.6:1, mix the weighed powder with absolute ethanol in a volume ratio of 1:2, ball mill for 12 hours, and dry at 100°C for 18 hours , through a 200-mesh sieve;

[0033] (2) molding the powder after ball milling under a pressure of 80 MPa to obtain a green body;

[0034] (3) Place the obtained green body in a graphite crucible, and then place them together in an atmosphere sintering furnace, and raise the temperature to 1000° C. at a rate of 300° C. / h under the condition of flowing argon;

[0035] (4) Introduce a small amount of air into the furnace cavity to make it at a slight positive pressure of 0.005MPa, continue to heat up to 1450°C at a heating rate of 200°C / h, and keep it warm for 2h.

[0036] (5) Porous silicon carbide ceramics are obtained by cooling with the furnace.

[0037] The bending strength of the porous silicon carbide ceramic obtained in this example is 160 MPa, and the corresponding porosity is 37%.

example 3

[0039] (1) Weigh the molar ratio of Si:MCMB=0.8:1, mix the weighed powder with absolute ethanol at a volume ratio of 1:1.5, ball mill for 18 hours, and dry at 90°C for 20 hours, through a 200-mesh sieve;

[0040] (2) The ball-milled powder is molded under a pressure of 75 MPa to obtain a green body.

[0041] (3) Place the obtained green body in a graphite crucible, and then place them together in an atmosphere sintering furnace, and raise the temperature to 1200° C. at a rate of 250° C. / h under the condition of flowing argon;

[0042] (4) Introduce a small amount of air into the furnace cavity to make it at a slight positive pressure of 0.015MPa, continue to heat up to 1450°C at a heating rate of 200°C / h, and keep it warm for 1.5h

[0043] (5) Obtain high-strength porous silicon carbide ceramics with furnace cooling.

[0044] The bending strength of the porous silicon carbide obtained in this example is 170 MPa, and the corresponding porosity is 34%.

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Abstract

The invention discloses a method for preparing porous silicon carbide ceramics by reaction sintering and micro-oxidation treatment. First, a certain amount of mesocarbon microspheres and silicon powder are wet ball-milled to obtain mixed powder, and then dry-pressed at room temperature to prepare a green body. , and finally sintered at high temperature under micro-oxidation treatment to obtain porous silicon carbide ceramics. Under the micro-oxidation treatment, a large number of silicon carbide whiskers were generated in situ; at the same time, SiO 2 The glassy phase promotes sintering and forms sintering necks between SiC particles. The invention has simple operation and high production efficiency, and the porous silicon carbide ceramic prepared by the method has uniform pore size distribution and high bending strength, and the strength reaches 176 MPa when the porosity is 32%.

Description

technical field [0001] The invention relates to the manufacture of structural ceramics, in particular to a method for preparing porous carbide ceramics. Background technique [0002] Porous SiC has high temperature strength, good thermal and chemical stability, high thermal shock resistance, low thermal conductivity, thermal expansion coefficient and other excellent properties, so it is widely used in aerospace, metallurgy, nuclear energy, space science , environment and other fields. [0003] At present, there are various methods for preparing porous SiC ceramics, including lost foam method, oxide bonding method, shape memory method, coating method and multi-pass extrusion method, etc. The properties of materials prepared by different methods are different. The document "Journal of European ceramics society, 2014, 34, 837-840" reported that C powder, Si 3 N 4 is the original material, Y 2 o 3 and Al 2 o 3 As an additive, a dense SiC / C composite material was obtained ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B38/06C04B35/565
Inventor 夏鸿雁杨少辉王红洁史忠旗王继平乔冠军张阔杨建锋
Owner 江西源瓷科技有限公司
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