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Method for preparing high-thermal-conductivity silicon nitride ceramic

A technology of silicon nitride ceramics and silicides, which is applied in the field of preparation of silicon nitride ceramic materials with high thermal conductivity, and can solve the problems of difficult preparation, high cost, harmful fluoride gas, etc.

Active Publication Date: 2019-06-07
江西中科上宇科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the sintering aids used such as: MgSiN 2 , Y 2 Si 4 N 6 Although C can improve the thermal conductivity, it needs to be self-made, the preparation is difficult and the cost is high; adding YF 3 During the sintering process, fluoride gas which is harmful to the human body and the environment will be produced

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  • Method for preparing high-thermal-conductivity silicon nitride ceramic
  • Method for preparing high-thermal-conductivity silicon nitride ceramic
  • Method for preparing high-thermal-conductivity silicon nitride ceramic

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preparation example Construction

[0033] The invention provides a method for preparing silicon nitride ceramics with high thermal conductivity. The silicon nitride ceramics with high thermal conductivity are prepared by adopting a pressure sintering method and using silicides and alkaline earth metal oxides as sintering aids. The method includes: the α-Si 3 N 4 Mix the powder and sintering aids uniformly in proportion; then press molding (for example, dry pressing molding and isostatic pressing treatment in sequence) to obtain a silicon nitride ceramic green body; finally, sinter by air pressure at 1780°C-1950°C under an inert atmosphere; Cool to room temperature after sintering, for example, cool to 1000°C-1400°C (eg 1200°C) at a cooling rate of 5-15°C / min, and then cool to room temperature with the furnace. Using silicide as a sintering aid makes less oxygen introduced through the aid and adjusts the liquid phase composition, thereby reducing the lattice oxygen content and avoiding phonon scattering; and us...

Embodiment 1

[0049] With 5mol% TiSi 2 and 5mol% MgO as a sintering aid, and 90mol% α-Si 3 N 4 The powder is mixed by ball milling, dried and sieved to obtain a uniformly mixed powder of 50g; then it is dry-pressed under 20MPa pressure, and then cold isostatic pressed under 250MPa pressure; the green body obtained is put into BN Crucible, and then into the graphite crucible, at 3MPaN 2 Under the atmosphere, the temperature was raised to 1900°C at a rate of 3°C / min for 4 hours under pressure sintering; after the sintering was completed, it was cooled to 1200°C at a rate of 10°C / min, and then cooled to room temperature with the furnace.

[0050] The thermal conductivity of the silicon nitride ceramics prepared in this example is 98.6W / (m·K), the three-point bending strength is 860MPa, and the fracture toughness is 6.29MPa·m 1 / 2 . The XRD pattern of the ceramic material is shown in figure 1 shown. Depend on figure 1 It can be seen that the sintered sample β-Si 3 N 4 It is the main p...

Embodiment 2

[0052] With 5mol% MoSi 2 and 5mol% MgO as a sintering aid, and 90mol% α-Si 3 N 4 The powder is mixed by ball milling, dried and sieved to obtain a uniformly mixed powder of 50g; then it is dry-pressed under 20MPa pressure, and then cold isostatic pressed under 250MPa pressure; the green body obtained is put into BN Crucible, and then into the graphite crucible, at 5MPa N 2 Under the atmosphere, sinter under pressure at 1900°C (heating rate 5°C / min) for 6 hours; after sintering, cool to 1200°C at a cooling rate of 10°C / min, and then cool to room temperature with the furnace.

[0053] The thermal conductivity of the silicon nitride ceramics prepared in this example is 108.2W / (m·K), the three-point bending strength is 875MPa, and the fracture toughness is 6.53MPa·m 1 / 2 . The XRD pattern of the ceramic material is shown in figure 2 shown. Depend on figure 2 It can be seen that the sintered sample β-Si 3 N 4 It is the main phase, indicating that the phase transformation ...

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Abstract

The invention relates to a method for preparing silicon nitride ceramic with high thermal conductivity, which comprises the following steps: uniformly mixing alpha-Si3N4 powder with a sintering aid, and carrying out compression molding to obtain a green body; and carrying out gas pressure sintering on the green body at the temperature of 1780-1950 DEG C in an inert atmosphere, and then cooling thesintered product to room temperature to obtain the silicon nitride ceramic; wherein the sintering aid is composed of silicide and alkaline earth metal oxide, the ratio of the alpha-Si3N4 powder to the sintering aid being (90mol%) : (10mol%) - (99mol%) : (1mol%).

Description

technical field [0001] The invention relates to a preparation method of a silicon nitride ceramic material with high thermal conductivity, belonging to the field of inorganic non-metallic materials. Background technique [0002] With the development of semiconductor devices in the direction of integration, miniaturization, and high power, device heat dissipation has become one of its important technical bottlenecks. Solving the heat dissipation problem largely depends on the performance of the ceramic substrate in the device. Currently commonly used ceramic heat dissipation substrates are alumina (Al 2 o 3 ), aluminum nitride (AlN), silicon carbide (SiC), beryllium oxide (BeO), etc. where Al 2 o 3 The thermal conductivity of ceramics is the lowest, and its expansion coefficient is greatly different from that of silicon components; AlN and BeO have the best thermal conductivity, but BeO powder is highly toxic; AlN has poor mechanical properties; SiC ceramics have low ins...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B35/645
Inventor 曾宇平王为得左开慧夏咏锋姚冬旭尹金伟梁汉琴
Owner 江西中科上宇科技有限公司
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