Novel wave-transmission and thermal-insulation combined SiO2-Si3N4 composite material and preparation method thereof

A sio2-si3n4, composite material technology, applied in the direction of the radiation unit cover, can solve the problems of narrow application fields, and achieve the effects of good sand erosion performance, high porosity, and heat insulation effect

Inactive Publication Date: 2013-01-02
ZHENGZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The application fields of porous silicon nitride ceramics and their composite materials are relatively narrow, and many research units and scholars focus on the military field, while the application research in civil, industrial and other fields is still blank

Method used

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  • Novel wave-transmission and thermal-insulation combined SiO2-Si3N4 composite material and preparation method thereof
  • Novel wave-transmission and thermal-insulation combined SiO2-Si3N4 composite material and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Mix 23ml of tetraethyl orthosilicate, 35ml of ethanol, and 3ml of water in a 200ml beaker, and stir vigorously on a magnetic stirrer, and then follow the formula of silicon nitride: magnesium oxide: aluminum oxide (weight ratio, the same below) = 33 :2:5 Add 1.7gMgO, 4.3gAl in turn 2 o 3 , 28.6gSi 3 N 4 , stir until uniform; adjust the pH value to 9, put it in a constant temperature water bath with an initial temperature of 30°C, and then heat up and dry the gel after freezing at -40°C for 2 hours, from -20°C to 80°C Dry for 60 minutes, dry at 80°C for 9 hours; after drying, sinter under normal pressure, rise from 0°C to 300°C for 3 hours, and then rise from 300°C to 1200°C for 3 hours, keep warm for 1 hour, and cool in the furnace to get the block SiO 2 -Si 3 N 4 base composite material.

[0021] The thermal conductivity of the composite material is 0.08W / m·K, the dielectric constant ε=3, and the dielectric loss tgδ=2.5×10 -3 . The density is 0.5g / cm 3 .

[...

Embodiment 2

[0024] Mix 23ml of tetraethyl orthosilicate, 35ml of ethanol, and 3ml of water in a 200ml beaker, and stir vigorously on a magnetic stirrer, and then add 1.96 g MgO, 4.91 g Al 2 o 3 , 39.31g Si 3 N 4 , stir until uniform; adjust the pH value to 9, put it into a test tube and place it in a constant temperature water bath with an initial temperature of 30°C, and then heat and dry the obtained gel after freezing at -40°C for 2 hours, from -20°C to 80°C ℃ drying for 60 minutes, 80 ℃ constant temperature drying for 9 hours; after drying, sintering under normal pressure, 3 hours from 0 ℃ to 300 ℃, and then 3 hours from 300 ℃ to 1200 ℃, heat preservation for 1 hour and then cool in the furnace to get this product Invented bulk SiO 2 -Si 3 N 4 base composite material.

[0025] The thermal conductivity of the composite material is 0.09W / m·K, the dielectric constant ε=4, and the dielectric loss tgδ=2.2×10 -3 . The density is 0.7g / cm 3 , the porosity is about 70%.

Embodiment 3

[0027]Mix 23ml of tetraethyl orthosilicate, 35ml of ethanol, and 3ml of water in a 200ml beaker, and stir vigorously on a magnetic stirrer, and then add 2.42 gMgO, 6.06gAl 2 o 3 , 60.56Si 3 N 4 , stir until uniform; adjust the PH value to 9 and put it into a test tube in a constant temperature water bath with an initial temperature of 30°C. The resulting gel is frozen at -40°C for 2 hours and then dried for 10 hours: from -20°C to 80°C Dry for 60 minutes, dry at a constant temperature of 80°C for 9 hours; after drying, sinter under normal pressure, rise from 0°C to 300°C for 3 hours, and then rise from 300°C to 1200°C for 3 hours, keep warm for 1 hour and then cool with the furnace to obtain the present invention Bulk SiO 2 -Si 3 N 4 base composite material.

[0028] The thermal conductivity of the composite material is 0.1W / m·K, the dielectric constant ε=3, and the dielectric loss tgδ=2.8×10 -3 . The density is 0.8g / cm 3 , the porosity is about 65%.

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Abstract

The invention belongs to the field of composite materials and particularly relates to a novel wave-transmission and thermal-insulation combined SiO2-Si3N4 composite material. The coefficient of thermal conductivity of the composite material is 0.08 to 0.1W / m.K, the dielectric constant epsilon is between 2.5 and 8, and the dielectric loss tg delta is 3*10<-3>. In the invention, sol-gel and freeze-drying combined technology is used for the first time to prepare porous ceramic, and the prepared Si3N4-based composite material has thermal-insulation and wave-transmission double effects and has a bright application prospect in fields of aerospace, military and national defense.

Description

technical field [0001] The invention belongs to the field of composite materials, in particular to a novel integrated SiO with wave-transmitting and heat-insulating functions 2 -Si 3 N 4 Composite materials and methods for their preparation. Background technique [0002] Porous ceramic is a new type of ceramic material, known as green functional material, which is a ceramic material that has been fired at high temperature and has a large number of interconnected or closed pores in the body. It has uniform distribution of micropores or pores, high porosity, small bulk density, large specific surface area and unique surface physical properties, selective permeability to liquid and gas media, and good energy absorption and damping properties. Material-specific high temperature resistance, corrosion resistance, thermal shock resistance, high chemical stability. The above characteristics make porous ceramics, a green material, widely used in many aspects such as filtration, s...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/596C04B35/14C04B35/622H01Q1/42
Inventor 王海龙陈建宝赵笑统冯伦张锐陈德良卢红霞许红亮范冰冰
Owner ZHENGZHOU UNIV
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