Low-resistivity linear-resistance silicon carbide and graphite composite and preparation method thereof

A composite material, silicon carbide technology, applied in the field of composite materials, can solve the problems of low density, low electrical conductivity, reduced electrical and thermal properties of materials, etc., and achieve the effect of low resistivity and high thermal conductivity

Active Publication Date: 2016-10-26
SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Moreover, the electrical conductivity of the carbon phase is lower than that of graphite, and the low density leads to the existence of a large number of pores in the material. The combination of the two will reduce the electrical and thermal properties of the material.

Method used

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  • Low-resistivity linear-resistance silicon carbide and graphite composite and preparation method thereof
  • Low-resistivity linear-resistance silicon carbide and graphite composite and preparation method thereof
  • Low-resistivity linear-resistance silicon carbide and graphite composite and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] Raw materials such as 90g of silicon carbide, 7g of amorphous carbon and 10ml of thermosetting phenolic resin (its pyrolysis carbon content is 3.0wt% of the total amount of powder) are fully mixed in absolute ethanol by a planetary ball mill to prepare a slurry, and Dry in an oven at 60°C for 12h. After grinding, pass through a 60-mesh sieve, dry-press at 40MPa, and then isostatically press at 200MPa to prepare a green body of composite material. The prepared green body of the composite material is debonded at 800° C. under vacuum condition, and the debonded green body is fired at 2150° C. for 1 hour under the condition of argon. The prepared composite material (No. 10C90SiC, see figure 2 Middle mark "1") dense, uniform microstructure, flexural strength of 446.8±83.1MPa, relative density of 99.5%, thermal conductivity of 154.02W m -1 ·K -1 , the DC resistivity is 705Ω·cm, and the AC resistance modulus is 45Ω. Specific appearance see figure 1 , AC impedance spectru...

Embodiment 2

[0047] Raw materials such as 85g of silicon carbide, 12g of amorphous carbon and 10ml of thermosetting phenolic resin (its pyrolysis carbon content is 3.0wt% of the total amount of powder) are fully mixed in absolute ethanol by a planetary ball mill to prepare a slurry, and Dry in an oven at 60°C for 12h. After grinding, pass through a 60-mesh sieve, dry-press at 40MPa, and then isostatically press at 200MPa to prepare a green body of composite material. The prepared green body of the composite material is debonded at 900° C. under vacuum condition, and the debonded green body is fired at 2200° C. for 1 hour under the condition of argon. The prepared composite material (No. 15C85SiC, see figure 2 Mark "2") dense, uniform microstructure, flexural strength of 368.1±79.6MPa, relative density of 93.6%, thermal conductivity of 132.20W m -1 ·K -1 , the DC resistivity is 63.04Ω·cm, and the AC resistance modulus is 1.76Ω. Specific appearance see image 3 , AC impedance spectrum ...

Embodiment 3

[0049] Raw materials such as 80g of silicon carbide, 17g of amorphous carbon and 10ml of thermosetting phenolic resin (its pyrolysis carbon content is 3.0wt% of the total amount of powder) are fully mixed in dehydrated alcohol by a planetary ball mill to prepare a slurry, and Dry in an oven at 60°C for 12h. After grinding, pass through a 60-mesh sieve, dry-press at 40MPa, and then isostatically press at 200MPa to prepare a green body of composite material. The prepared green body of the composite material is debonded at 1000° C. under vacuum condition, and the debonded green body is fired at 2200° C. for 1 hour under the condition of argon. The prepared composite material (No. 3R17C80SiC) is dense, uniform in microstructure, with a flexural strength of 306.2±60.1MPa, a relative density of 90.7%, a thermal conductivity of 110.80W·m-1·K-1, and a DC resistivity of 30Ω· cm, the AC resistance modulus is 1.10Ω. Specific appearance see Figure 4 , AC impedance spectrum Bode diagra...

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Abstract

The invention relates to a low-resistivity linear-resistance silicon carbide and graphite composite and a preparation method thereof. The silicon carbide and graphite composite is composed of silicon carbide phase and a graphite phase converted from carbon phase during sintering and is free of third-phase substances, the graphite phase is 10-20% by weight, and the silicon carbide / graphite composite is 110-160 W / m<-1> / K<-1> in heat conductivity, 10-750 Omega / cm in direct-current resistivity that never changes with voltage, and 0.5-45 Omega in alternating-current resistivity modulus that never changes with frequency. The composite of the invention comprises only silicon carbide and graphite and is free of third-phase substances, and by adjusting the content of graphite, it is possible to obtain the silicon carbide / graphite composite with high heat conductivity, low resistance and linear resistance.

Description

technical field [0001] The invention relates to a preparation method of a silicon carbide / graphite composite material with low resistivity and linear resistance characteristics, belonging to the field of composite materials. Background technique [0002] Silicon carbide ceramics can be used for radioactive, corrosive , explosive, high temperature and many other complex working conditions. At the same time, it is expected to become an electronic component that operates in a harsh environment. [0003] However, SiC sintered at atmospheric pressure has semiconductor characteristics, which limits its application. Studies have shown that: high-purity SiC has 10 12 High resistivity on the order of Ω·cm, but when there are impurities such as iron and nitrogen, the resistivity will be reduced to a few tenths of Ω·cm, and the range of resistivity change is closely related to the type and amount of impurities. In order to meet the applications in different fields, it is necessary ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/565C04B35/622C04B35/634
CPCC04B35/565C04B35/622C04B35/63476C04B2235/425C04B2235/77C04B2235/96C04B2235/9607
Inventor 姚秀敏黄政仁蒋金弟刘学建
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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