Method for preparing high-heat-conductivity silicon nitride ceramic through normal pressure sintering

A technology of silicon nitride ceramics and normal pressure sintering, applied in the field of non-oxide ceramic preparation, can solve related properties (decreased mechanical properties and thermal properties, low thermal conductivity of normal pressure sintered silicon nitride ceramics, limited nitriding Development and application of silicon ceramics, etc., to achieve the effect of improving mechanical properties, easy control of conditions, and excellent mechanical properties

Active Publication Date: 2019-02-05
浙江多面体新材料有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although this technology has good thermal conductivity, the cost is high, which limits the further development and application of silicon nitride ceramics
Generally, low-temperature liquid phase sintering technology requires a higher content of sintering aids, which leads to a decrease in the relevant properties (mechanical properties and thermal properties, etc.) of the material. The performance of silicon ceramics is very important, and there are not many reports on the thermal conductivity of silicon nitride ceramics sintered at atmospheric pressure.

Method used

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  • Method for preparing high-heat-conductivity silicon nitride ceramic through normal pressure sintering
  • Method for preparing high-heat-conductivity silicon nitride ceramic through normal pressure sintering
  • Method for preparing high-heat-conductivity silicon nitride ceramic through normal pressure sintering

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0046] 19.0g of silicon nitride powder and 1.0g of composite sintering aids (MgO and TiO 2 The molar ratio is 1:2) powder as raw material, absolute ethanol as solvent, placed in a ball mill tank for ball milling for 4 hours, then the dried and sieved mixture was placed in a mold, and dry-pressed at 30MPa to form the obtained biscuit Carry out cold isostatic pressing with a pressure of 200 MPa, place the final ceramic green body in a carbon tube furnace, use nitrogen as a protective atmosphere, and heat up to 1700°C, keep warm for 2 hours, then cool down with the furnace. A density of 3.14g cm can be obtained -3 , The relative density is 97%.

Embodiment 2

[0048] 18.6g of silicon nitride powder and 1.4g of composite sintering aids (MgO and TiO 2 The molar ratio is 1:1) powder as raw material, absolute ethanol as solvent, put it in a ball mill tank for ball milling for 4 hours, then put the dried and sieved mixture in a mold, dry press molding at 30MPa, and the obtained biscuit Carry out cold isostatic pressing with a pressure of 200 MPa, place the final ceramic green body in a carbon tube furnace, use nitrogen as a protective atmosphere, and heat up to 1780°C, keep warm for 1h, then cool down with the furnace. After another 6 hours of heat preservation at 1600 ° C, the material density, relative density, thermal conductivity, fracture toughness and Vickers hardness are 3.21 g cm -3 , 99.1%, 58.57W / (m·K), 5.28MPa·m 1 / 2 and 15.32GPa. figure 1 To obtain the SEM image of the sample. from figure 1 It can be seen that the material has distinct long columnar grains.

Embodiment 3

[0050] 18.0g of silicon nitride powder and 2.0g of composite sintering aids (MgO and TiO 2 The molar ratio is 2:1) powder as raw material, absolute ethanol as solvent, placed in a ball mill tank for ball milling for 4 hours, then the dried and sieved mixture was placed in a mold, and dry-pressed at 30MPa to form the obtained biscuit Carry out cold isostatic pressing with a pressure of 200 MPa, place the final ceramic green body in a carbon tube furnace, use nitrogen as a protective atmosphere, and heat up to 1780°C, keep warm for 2 hours, then cool down with the furnace. After 6 hours of heat preservation at 1600 ° C, the material density, relative density, thermal conductivity, fracture toughness, flexural strength and Vickers hardness are 3.20 g cm -3 , 98.8%, 59.84W / (m·K), 5.13MPa·m 1 / 2 , 668MPa and 15.06GPa. figure 2 To obtain the SEM image of the sample. from figure 2 It can be seen that the material has a larger grain size.

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Abstract

The invention relates to a method for preparing high-heat-conductivity silicon nitride ceramic through normal pressure sintering. The method includes the steps that with the total material mass being100%, 95-70% of silicon nitride powder and 5-30% of sintering aids are evenly mixed to obtain ceramic mixed powder, and the sintering aids are a mixture with TiO2 as a main sintering aid and at leastone of Y2O3, Sc2O3, Sm2O3, Lu2O3, Er2O3, MgO, Mg2Si and MgSiN2 as an auxiliary sintering aid; the obtained ceramic mixed powder is molded to obtain a ceramic biscuit; the obtained ceramic biscuit is subjected to normal pressure sintering under 1600-1800 DEG C, so that dense silicon nitride ceramic is obtained. The method can be used for obtaining the dense silicon nitride ceramic with a certain heat conductivity level and excellent mechanical properties.

Description

technical field [0001] The invention relates to a method for preparing silicon nitride ceramics with high thermal conductivity by normal pressure sintering, more precisely, TiO 2 As the main sintering aid, different auxiliary sintering aids are preferred, and the method for preparing silicon nitride ceramic material with high thermal conductivity by normal pressure sintering belongs to the technical field of non-oxide ceramic preparation. Background technique [0002] Silicon nitride ceramics have excellent mechanical properties, including high flexural strength and fracture toughness, good thermal shock resistance, low high temperature creep, and good wear resistance and corrosion resistance. They are widely used in Structural ceramics fields such as automotive, aerospace and electronics etc. [0003] The crystal structure of silicon nitride consists of strong covalent bonds, which makes it difficult to sinter the material, so liquid phase sintering is usually used to prep...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B35/64
CPCC04B35/584C04B35/64C04B2235/3232C04B2235/3206C04B2235/3224C04B2235/3225C04B2235/3886C04B2235/3891C04B2235/96C04B2235/9607C04B2235/77C04B2235/6562C04B2235/5436C04B2235/5445
Inventor 张景贤段于森李晓光
Owner 浙江多面体新材料有限公司
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