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Silicon nitride sintered body and preparation method thereof

A technology of silicon nitride and sintered body, applied in the field of materials, can solve the problems of stress concentration, lifting, low elastic modulus, etc., achieve good bending strength, promote mass transfer, and improve the effect of morphology

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

AI Technical Summary

Problems solved by technology

However, these silicides themselves often have relatively high thermal expansion coefficients, and are prone to cracks due to excessive shrinkage during the cooling process after sintering the silicon nitride body, and they have a relatively low elastic modulus, which is likely to cause stress concentration effects and microcracks and stress concentration are likely to cause a decrease in the strength of silicon nitride, and an excessively high thermal expansion coefficient is also not conducive to the thermal shock resistance of silicon nitride sintered body
[0004] Nitrides such as W, Mo, Ti, V, etc. often have the characteristics of low thermal expansion coefficient and high elastic modulus. Adding them alone to silicon nitride can improve the fracture toughness of silicon nitride within a certain range, but the high elastic modulus is also It is easy to cause stress concentration, which is not conducive to the improvement of the flexural strength of silicon nitride

Method used

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  • Silicon nitride sintered body and preparation method thereof
  • Silicon nitride sintered body and preparation method thereof
  • Silicon nitride sintered body and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] Weigh phase tungsten powder and silicon powder according to W:Si=1:2 (atomic ratio) and take 100g altogether, place in silicon nitride ball mill tank;

[0046] Add 100g of silicon nitride grinding balls, 150g of absolute ethanol, and mix in a planetary ball mill (rpm=300) for 1h;

[0047] The slurry was dried in an oven at 80°C for 5 hours, and passed through an 80-mesh sieve to obtain a powder;

[0048] The powder was heat-treated at 1400°C for 2 hours under an argon atmosphere to obtain WSi 2 Powder;

[0049] According to Fe:Si=1:2 (atomic ratio), take corresponding iron powder and silicon powder altogether 100g, the WSi that above-mentioned method obtains 2 Powder 100g, placed in a silicon nitride ball mill jar;

[0050] Add 200g of silicon nitride grinding balls, 300g of absolute ethanol, and mix in a planetary ball mill (rpm=300) for 2h;

[0051] The slurry was dried in an oven at 60°C for 5 hours, and passed through an 80-mesh sieve to obtain a powder;

[005...

Embodiment 2

[0061] Prepare CuSi with reference to Example 1 2 / WSi 2 =1:1 (mass ratio) polymetallic silicide powder;

[0062] Weigh CuSi 2 / WSi 2 =1:1 (mass ratio) polymetallic silicide powder 5g, magnesium oxide powder 3g, yttrium oxide powder 5g, silicon nitride powder 92g are placed in the silicon nitride ball mill jar, add 150g dehydrated alcohol, 200g of silicon nitride grinding balls were ball-milled, dried and sieved to obtain powder raw materials. After the powder is formed, it is sintered at 1860°C for 3h under 5MPa nitrogen pressure.

Embodiment 3

[0064] Prepare FeSi with reference to embodiment 1 2 / MoSi 2 =10:1 (mass ratio) polymetallic silicide powder;

[0065] Weigh FeSi 2 / MoSi 2 =10:1 (mass ratio) polymetallic silicide powder 1g, aluminum oxide powder 4g, lanthanum oxide powder 11g, silicon nitride powder 85g are placed in the silicon nitride ball mill jar, add 150g dehydrated alcohol, 200g of silicon nitride grinding balls were ball-milled, dried and sieved to obtain powder raw materials. After the powder is formed, it is sintered at 1750°C for 5h under 0.2MPa nitrogen pressure.

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Abstract

The invention relates to a silicon nitride sintered body and a preparation method thereof. The silicon nitride sintered body comprises a silicon nitride phase and a grain boundary phase. The grain boundary phase comprises metal silicide and metal nitride, wherein at least part of the metal silicide and the metal nitride exist in the form of adjoining or / and mutual wrapping, the total mass of the metal silicide and the metal nitride accounts for 0.1-10 wt%, preferably 0.1-5 wt%, of the total mass of silicon nitride and sintering aids. The silicon nitride sintered body has good bending strength, fracture toughness and thermal shock resistance and can be applied to the fields of machinery, metallurgy, aviation and the like.

Description

technical field [0001] The invention relates to a silicon nitride sintered body and a preparation method thereof, belonging to the field of materials. Background technique [0002] Silicon nitride is widely used in machinery, metallurgy, aviation and other fields due to its high strength, high toughness, and thermal shock resistance. Its performance depends on the density, grain size distribution and aspect ratio of silicon nitride, and the nature of the reinforcing phase. [0003] The silicides of Fe, Mn, Cu, Ni, Co, Cr, etc. have lower melting points, which can promote the mass transfer of silicon nitride, accelerate densification, increase the aspect ratio of grains, etc., which is beneficial to the improvement of the performance of silicon nitride improve. However, these silicides themselves often have relatively high thermal expansion coefficients, and are prone to cracks due to excessive shrinkage during the cooling process after sintering the silicon nitride body, a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B35/622C04B35/58C04B35/626
CPCC04B35/58085C04B35/58092C04B35/584C04B35/622C04B35/6265C04B35/62675C04B35/6268C04B2235/3206C04B2235/3217C04B2235/3225C04B2235/3227C04B2235/3229C04B2235/658C04B2235/96
Inventor 刘学建王鲁杰杨晓姚秀敏黄政仁
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI