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High-thermal-conductivity silicon nitride ceramic material and preparation method thereof

A technology of silicon nitride ceramics and raw materials, which is applied in the field of high thermal conductivity silicon nitride ceramic materials and its preparation, can solve the problems of high oxygen content, reduce energy consumption and cost, and be difficult to densify, and achieve low amorphous phase content , reduce lattice defects, and promote densification

Active Publication Date: 2020-05-26
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

Obviously, this method is not conducive to reducing energy consumption and cost
However, it is difficult to densify silicon nitride ceramics sintered at low temperature under normal pressure, and it is usually necessary to add more sintering aids
Too high content of sintering aid will make the oxygen content in the sintering system too high, which is not conducive to the purification of crystal grains through the dissolution process in the liquid phase
On the other hand, a large amount of liquid phase remains in the sintered body in the form of glass phase after cooling, which reduces the mechanical and thermal properties of silicon nitride ceramics.

Method used

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  • High-thermal-conductivity silicon nitride ceramic material and preparation method thereof
  • High-thermal-conductivity silicon nitride ceramic material and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0046] With 1wt% TiH 2 and 4wt% MgO as a sintering aid, and 95wt% α-Si 3 N 4 The powder is mixed by ball milling, dried and sieved to obtain a uniformly mixed powder; then it is dry-pressed under a pressure of 20MPa, and then subjected to cold isostatic pressing under a pressure of 250MPa; the green body obtained is put into a BN crucible , held at 510°C for 2 hours in an Ar atmosphere, then raised to 1000°C and held for 4 hours for pre-sintering; then the pre-sintered green body was sintered at 1780°C, the heating rate was 10°C / min, and the holding time was 4h; the sintering was completed Afterwards, cool to 1200°C at a cooling rate of 10°C / min, and then cool to room temperature with the furnace.

[0047] The density of the silicon nitride ceramic material prepared in Example 1 is 97.3%, the three-point bending strength is 449MPa, and the fracture toughness is 4.56MPa m 1 / 2 , the thermal conductivity is 55.6W / (m·K).

Embodiment 2

[0049] With 6wt% TiH 2 and 2wt% MgO as a sintering aid, and 92wt% α-Si 3 N 4 The powder is mixed by ball milling, dried and sieved to obtain a uniformly mixed powder; then dry-pressed under a pressure of 20MPa, and then subjected to cold isostatic pressing under a pressure of 300MPa; the green body obtained is put into a BN crucible , in an Ar atmosphere at 600°C for 2h, then heat up to 1200°C for 4h for pre-sintering; then sinter the pre-sintered green body at 1800°C for 1.5h, with a heating rate of 10°C / min; after sintering , cooled to 1550°C at a cooling rate of 2°C / min and held for 8 hours, and then cooled to room temperature with the furnace.

[0050] The density of the silicon nitride ceramic material prepared in Example 2 is 97.9%, the thermal conductivity is 62W / (m·K), the three-point bending strength is 508MPa, and the fracture toughness is 4.75MPa·m 1 / 2 .

Embodiment 3

[0052] With 5wt% TiH 2 and 7wt% MgO as a sintering aid, and 88wt% α-Si 3 N 4 The powder is mixed by ball milling, dried and sieved to obtain a uniformly mixed powder; then it is dry-pressed under a pressure of 30MPa, and then subjected to cold isostatic pressing under a pressure of 300MPa; the green body obtained is put into a BN crucible , after holding at 600°C for 2h under vacuum, the temperature was raised to 1300°C for 4h for pre-sintering; then the pre-sintered green body was sintered at 1780°C for 4h, and the heating rate was 5°C / min; then, at 1°C / min Cool down to 1580°C at a cooling rate of min and hold for 12 hours, then cool to room temperature with the furnace.

[0053] The density of the silicon nitride ceramic material prepared in Example 3 is 98.7%, the thermal conductivity is 78.90W / (m·K), the three-point bending strength is 510MPa, and the fracture toughness is 5.59MPa·m 1 / 2 . The cross-sectional microscopic topography figure of the silicon nitride ceramic ...

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Abstract

The invention relates to a high-thermal-conductivity silicon nitride ceramic material and a preparation method thereof. The silicon nitride ceramic material is prepared from the following raw materials: alpha-Si3N4 and a sintering aid, wherein the sintering aid is metal hydride and alkaline earth metal oxide, and the total content of the sintering aid is 5-20wt%; the metal hydride is TiH2; and thealkaline earth metal oxide is preferably MgO.

Description

technical field [0001] The invention relates to a silicon nitride ceramic material with high thermal conductivity and a preparation method thereof, in particular to a metal hydride TiH 2 and alkaline earth metal oxides as sintering aids to prepare Si with high thermal conductivity 3 N 4 The ceramic material method belongs to the field of inorganic non-metallic materials. Background technique [0002] With the rapid development of my country's aerospace, high-speed rail, new energy vehicles and other fields, the demand for high-power power electronic devices will also increase in the future. In order to adapt to more demanding application conditions, high-power power electronic devices are developing towards high temperature, high frequency, low power consumption, intelligence, modularization, and systematization, which poses a severe challenge to the heat dissipation of the entire device, and power devices It mainly relies on the heat dissipation substrate to absorb the h...

Claims

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Application Information

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IPC IPC(8): C04B35/584C04B35/622C04B35/64
CPCC04B35/584C04B35/622C04B35/64C04B2235/3878C04B2235/3206C04B2235/44C04B2235/6562C04B2235/6565C04B2235/6567C04B2235/658C04B2235/6581C04B2235/668C04B2235/96C04B2235/9607
Inventor 曾宇平王为得左开慧夏咏锋姚冬旭尹金伟梁汉琴
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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