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High-heat-conductivity silicon nitride ceramic and preparation method thereof

A technology of silicon nitride ceramics and high thermal conductivity, which is applied in the field of ceramic material preparation, can solve the problems affecting the improvement of mechanical properties and thermal conductivity, the low thermal conductivity of polycrystalline silicon nitride ceramics, and the difficulty of industrialization. Achieve the effects of avoiding phonon scattering, safe use, and high thermal conductivity

Inactive Publication Date: 2018-09-28
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Before the mid-1990s, the thermal conductivity of polycrystalline silicon nitride ceramics reported in the literature at room temperature was very low, only 20-70W / m K, far lower than other non-oxide ceramics (SiC is 270W / m K, AlN is 320W / m K)
The silicon nitride ceramic substrate prepared by this method will have low dielectric properties due to the residual silicon left in the nitriding process. At the same time, residual pores will remain in the sintered material after the silicon powder is nitrided, and the density is low, which affects the mechanical properties. Improved performance and thermal conductivity
Another method is to directly use silicon nitride powder as a raw material, mix it with sintering aids, press it into a green body, and sinter at high temperature (1700-2000°C) and 0.9-1MPa nitrogen pressure for 2-60h. Using high-purity silicon nitride powder, the cost is high and the industrialization is difficult

Method used

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  • High-heat-conductivity silicon nitride ceramic and preparation method thereof
  • High-heat-conductivity silicon nitride ceramic and preparation method thereof

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Embodiment 1

[0027] This embodiment provides a method for preparing silicon nitride ceramics with high thermal conductivity, which includes the following steps:

[0028] In the first step, the silicon nitride powder and the carbon powder are respectively placed in a boron nitride crucible, placed in an alumina tube furnace, and heated at a rate of 5-10°C / min in a nitrogen reaction atmosphere. Treat at 1200°C-1400°C for 4-8h, after the reaction is completed, the furnace temperature is naturally cooled, and the treated powder is ground and sieved;

[0029] In the second step, the silicon nitride powder and the sintering aid described in the first step are mixed under the action of the mixing medium, and after the mixing is completed, they are dried and sieved to obtain a powder; wherein the sintering aid is a binary composite A sintering aid, and the binary composite sintering aid includes a rare earth oxide and an alkaline earth metal compound, and the rare earth oxide is Y 2 o 3 , Yb 2 ...

Embodiment 2

[0039]The difference between this example and Example 1 is that the nitrogen reaction atmosphere in the first step is replaced by an ammonia reaction atmosphere, and the others are the same as in Example 1. Ammonia treatment can also deoxidize the silicon nitride powder, and ammonia reacts with the silicon dioxide layer on the surface of the silicon nitride powder. Thermal conductivity of sintered silicon nitride.

Embodiment 3

[0041] This embodiment provides a method for preparing silicon nitride ceramics with high thermal conductivity, which includes the following steps:

[0042] In the first step, the silicon nitride powder and the carbon powder are put into boron nitride crucibles respectively, placed in an alumina tube furnace, and heated at 1200°C in a nitrogen reaction atmosphere at a heating rate of 5°C / min. Process at ℃ for 4 hours, after the reaction is completed, the furnace temperature is naturally cooled, and the treated powder is ground and sieved;

[0043] In the second step, the silicon nitride powder and the sintering aid described in the first step are mixed under the action of the mixing medium, and after the mixing is completed, they are dried and sieved to obtain a powder; wherein the sintering aid is a binary composite A sintering aid, and the binary composite sintering aid includes a rare earth oxide and an alkaline earth metal compound, and the rare earth oxide is Y 2 o 3 , ...

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Abstract

The invention provides high-heat-conductivity silicon nitride ceramic and a preparation method thereof, which are used for solving the technical problem that the existing heat conductivity is low. Thepreparation method comprises the following steps: performing deoxygenation treatment on silicon nitride powder, naturally cooling the silicon nitride powder, and grinding and sieving the obtained silicon nitride powder; mixing the powder and a sintering aid under the action of a mixed medium, and drying and sieving after mixing to obtain powder; performing pressing formation to obtain a silicon nitride ceramic green body; and performing gas pressure sintering to obtain the silicon nitride ceramic material. Compared with the prior art, the high-heat-conductivity silicon nitride ceramic and thepreparation method thereof have the following advantages: the silicon nitride powder is subjected to deoxygenation treatment, the oxygen content of the original powder is low, the degree of reducingthe lattice oxygen content in the sintering process is higher, and phonon scattering is avoided, so that the heat conductivity of the silicon nitride ceramic is improved; and the prepared silicon nitride ceramic has high heat conductivity, high thermal shock resistance and high-temperature resistance, is safe to use and is a silicon nitride ceramic substrate material with excellent mechanical, thermal and electric comprehensive performance.

Description

technical field [0001] The invention relates to the technical field of ceramic material preparation, in particular to a silicon nitride ceramic with high thermal conductivity and a preparation method thereof. Background technique [0002] Silicon nitride (Si3N4) has high strength, good toughness, thermal shock resistance, corrosion resistance and wear resistance, and is widely used in aerospace, machinery, nuclear energy, chemical industry, marine engineering, armor protection and other fields. Before the mid-1990s, the thermal conductivity of polycrystalline silicon nitride ceramics reported in the literature at room temperature was very low, only 20-70W / m K, far lower than other non-oxide ceramics (SiC 270W / m·K, AlN is 320W / m·K). In 1995, Haggerty et al. predicted that the thermal conductivity of β-Si3N4 ceramics could reach 200-320W / m K. This discovery expanded the application of silicon nitride ceramics in electric vehicles, integrated circuits and applications requirin...

Claims

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Application Information

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IPC IPC(8): C04B35/584C04B35/64
CPCC04B35/584C04B35/64C04B2235/422C04B2235/6562C04B2235/658C04B2235/96C04B2235/9607
Inventor 叶枫杨春萍张标叶健刘强高晔叶凯
Owner HARBIN INST OF TECH
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