Silicon carbide ceramic with adjustable resistance and preparation method thereof

A technology for silicon carbide ceramics and silicon carbide slurry is applied in the field of silicon carbide ceramics and their preparation, and can solve the problems of affecting the electrical properties of silicon carbide ceramics, decreasing the density of silicon carbide ceramics, affecting the strength and toughness of silicon carbide ceramics, and the like.

Inactive Publication Date: 2018-11-30
NINGBO VULCAN TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, due to the excessive addition of organic carbon (10% to 20%), the density of silicon carbide ceramics will decrease (less than 3.0g / cm 3 ), which in turn affects the strength and toughness of silicon carbide ceramics
The main purpose of this patent is to improve the mechanical properties of silicon carbide ceramics by adding graphene nanosheets, and the process of preparing silicon carbide ceramics by reaction sintering will consume almost all graphene and add excess free silicon, which will Seriously affect the electrical properties of silicon carbide ceramics
At the same time, due to the presence of free silicon in silicon carbide ceramics prepared by reaction sintering, the maximum permitted temperature is 1700°C, which limits its application in harsh environments such as high temperature, high frequency and high power.

Method used

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  • Silicon carbide ceramic with adjustable resistance and preparation method thereof

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Effect test

Embodiment 1

[0038] A silicon carbide ceramic with adjustable resistance, wherein, the content of silicon carbide phase is 90wt%, the content of boron carbide phase is 0.1%, the content of carbon phase is 9.8wt%, and the content of impurities is 0.1%. The prepared silicon carbide ceramics have a density of 3.01g / cm 3 , the resistivity is 3.52×10 -2 Ω·cm.

[0039] It is prepared as follows:

[0040] 89.9g of silicon carbide, 0.1g of boron carbide micropowder, 10.0g of graphene powder and other raw materials were fully ball milled and mixed for 24 hours in an ethanol solution containing 1g of dispersant PVP. The prepared slurry was dried in an oven at 70 °C for 24 h. After grinding and pulverizing, pass through a 120-mesh sieve, press molding at 15 MPa, and isostatic pressing at 200 MPa to obtain a silicon carbide ceramic green body. The green body is subjected to degreasing treatment under nitrogen at 1200°C, and then pressureless sintered at 1900°C for 24 hours to obtain the finished p...

Embodiment 2

[0042] A silicon carbide ceramic with adjustable resistance, wherein, the content of silicon carbide phase is 95% by weight; the content of boron carbide phase is 0.45%; the content of carbon phase is 4.5% by weight; and the content of impurities is 0.05%. The prepared silicon carbide ceramics have good density, with a density of 3.10g / cm 3 , the resistivity is 1.1×10 2 Ω·cm.

[0043] It is prepared as follows:

[0044] 94.5g of silicon carbide, 0.5g of boron carbide micropowder, 5.0g of graphene powder, etc. were used as raw materials in a methanol solution containing 1.0g of dispersant CMC and fully ball milled and mixed for 12 hours, and the raw material powder was prepared by spray granulation. Silicon carbide ceramic green bodies were prepared by dry pressing at 15 MPa and isostatic pressing at 200 MPa. The prepared green body was degreased at 1300°C under argon gas, and then the green body was kept at 2150°C for 24 hours for pressureless sintering.

Embodiment 3

[0046] A silicon carbide ceramic with adjustable resistance, wherein the content of silicon carbide phase is 99.35% by weight; the content of boron carbide phase is 0.45%; the content of carbon phase is 0.15% by weight; and the content of impurities is 0.05%. The prepared silicon carbide ceramics have good density, with a density of 3.15g / cm 3 , the resistivity is 4.2×10 4 Ω·cm.

[0047] It is prepared as follows:

[0048] 99.4g of silicon carbide, 0.5g of boron carbide micropowder, 0.1g of graphene powder, etc. were used as raw materials in a methanol solution containing 0.5g of dispersant CMC for 48 hours, and the raw material powder was prepared by spray granulation. Silicon carbide ceramic green bodies were prepared by dry pressing at 10MPa and isostatic pressing at 200MPa. The prepared green body was degreased at 1000° C. under nitrogen condition, and then the green body was kept at 2000° C. for 48 hours for pressureless sintering.

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Abstract

The invention discloses silicon carbide ceramic with adjustable resistance and a preparation method thereof. The ceramic material mainly comprises a silicon carbide phase as a main phase, boron carbide as a sintering aid phase, and a carbon phase as a conductive phase, and the ceramic material can be prepared and has the bulk resistivity adjustable from 10<-2> to 10<8> Omega.cm. The silicon carbide ceramic has a density of 3.00 to 3.20 g/cm<3>. The core of the method is to coat the surface of silicon carbide raw material powder with a graphene-based material layer, and to adjust the content ofthe conductive phase in the silicon carbide ceramic to obtain the silicon carbide ceramic with adjustable bulk resistivity.

Description

technical field [0001] The invention relates to the field of preparation of inorganic non-metallic materials, in particular to a silicon carbide ceramic with adjustable resistance and a preparation method thereof. Background technique [0002] Silicon carbide ceramics have excellent physical and chemical properties such as high strength, high hardness, high temperature resistance, oxidation resistance, and good chemical stability; at the same time, silicon carbide ceramics have high saturated electron mobility and high thermal conductivity, which can be applied Due to radioactive, corrosive, explosive, high temperature and many other complex working conditions, it is expected to become a material that can be applied under harsh conditions. However, as silicon carbide ceramics with semiconducting properties, the adjustable range of resistivity is very narrow, which limits its application in wider fields (especially in the fields of electromagnetics, electronics, etc.). At pr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/565C04B35/622C04B35/64
CPCC04B35/565C04B35/622C04B35/64C04B2235/3821C04B2235/425C04B2235/5436C04B2235/77
Inventor 蔡宁宁邬国平郭岱东谢方民
Owner NINGBO VULCAN TECH CO LTD
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