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High-strength and high-heat-conductive Si3N4 ceramic material and preparation method thereof

A technology of ceramic materials and raw materials, applied in the field of Si3N4 ceramic materials and its preparation, can solve the problems of reducing thermal conductivity, reducing phonon mean free path, and low thermal conductivity second equivalence, so as to improve thermal conductivity and facilitate liquid phase Effect of mass transfer and strength improvement

Active Publication Date: 2020-03-31
江西中科上宇科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since Si 3 N 4 There are vacancies, dislocations, impurity atoms, interstitial atoms, low thermal conductivity second phases, pores, grain boundaries, etc. in the ceramic grains. The actual thermal conductivity is far lower than the theoretical value and needs to be further improved.
Moreover, it is generally believed that Si 3 N 4 The presence of oxygen atoms in the crystal lattice leads to silicon vacancies, which scatter phonons and reduce the phonon mean free path, thereby reducing its thermal conductivity

Method used

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  • High-strength and high-heat-conductive Si3N4 ceramic material and preparation method thereof
  • High-strength and high-heat-conductive Si3N4 ceramic material and preparation method thereof
  • High-strength and high-heat-conductive Si3N4 ceramic material and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Weigh LaB 6 Powder 4.44g, with 94.41g Si 3 N 4 Mix the powder with 1.16g MgO powder, add 66.7g alcohol as solvent, 100g Si 3 N 4 The ball is the ball milling medium, milled at 300rpm for 12h, then baked in an 80°C constant temperature oven for 18h, ground, and passed through a 100-mesh sieve; the obtained powder was dry-pressed and preformed under a pressure of 30MPa and then loaded into a graphite hot-pressing mold. Place the sample in a carbon tube furnace and fill it with N 2 As a protective gas, sintering at 1550°C and 60MPa pressure for 60 minutes, the thermal conductivity is 24.8w / (m·K), the bending strength is 649.4±24.2MPa, and the fracture toughness is 6.96±0.21MPa·m 1 / 2 , Si with a Vickers hardness of 19.35±0.18GPa 3 N 4 ceramics.

[0037] For the Si obtained in Example 1 3 N 4 Ceramic cross-section observation, the results are as follows figure 1 As shown, due to the lower sintering temperature, Si 3 N 4 The phase transition does not occur obvious...

Embodiment 2

[0039] Weigh LaB 6 Powder 4.44g, with 94.41g Si 3 N 4 Mix the powder with 1.16g MgO powder, add 66.7g alcohol as solvent, 100g Si 3 N 4 The ball is the ball milling medium, milled at 300rpm for 12h, then baked in an 80°C constant temperature oven for 18h, ground, and passed through a 100-mesh sieve; the obtained powder was dry-pressed and preformed under a pressure of 30MPa and then loaded into a graphite hot-pressing mold. Place the sample in a carbon tube furnace and fill it with N 2 As protective gas, sinter at 1550°C, 60MPa pressure for 60 minutes, then at 1900°C, 2MPa N 2 Treated under air pressure for 1h, the thermal conductivity is 69.8w / (m·K), the bending strength is 893.3±36.3MPa, and the fracture toughness is 8.43±0.27MPa·m 1 / 2 , Si with a Vickers hardness of 14.94±0.12GPa 3 N 4 ceramics.

[0040] For the Si obtained in Example 2 3 N 4 Ceramic cross-section observation, the results are as follows figure 2 As shown, Si 3 N 4 The grains in ceramics have c...

Embodiment 3

[0042] Weigh LaB 6 Powder 4.44g, with 94.41g Si 3 N 4 Mix the powder with 1.16g MgO powder, add 100g alcohol as solvent, 200g Si 3 N 4 The ball is the ball milling medium, milled at 200rpm for 16h, then baked in a 90°C constant temperature oven for 16h, ground, and passed through a 200-mesh sieve; the obtained powder was dry-pressed and preformed under a pressure of 50MPa and then loaded into a graphite hot-pressing mold. Place the sample in a carbon tube furnace and fill it with N 2 As a protective gas, sintering at 1650°C and 60MPa pressure for 120 minutes, the thermal conductivity is 48.3w / (m·K), the bending strength is 986.5±43.9MPa, and the fracture toughness is 7.43±0.19MPa·m 1 / 2 , Si with a Vickers hardness of 16.21±0.15GPa 3 N 4 ceramics.

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Abstract

The invention relates to a high-strength and high-heat-conductive Si3N4 ceramic material and a preparation method thereof. The Si3N4 ceramic material includes, by weight, 94.41-96.7% of Si3N4, 1.52-4.44% of LaB6, and 1.15-1.78% of MgO; the Si3N4 ceramic material has properties that heat-conductivity is 20.3-85.1 W / m*K, bending strength is 583.2-1218.8 MPa, breaking toughness is 6.12-8.99 MPa*m<1 / 2> and Vickers hardness is 14.11-19.53 GPa.

Description

technical field [0001] The invention relates to a Si with high strength and high thermal conductivity 3 N 4 Ceramic material and preparation method thereof, specifically relate to a kind of Si 3 N 4 Main phase, LaB 6 and MgO as sintering aids to prepare Si with high strength, high toughness, high hardness and high thermal conductivity 3 N 4 Ceramic materials and methods thereof, belonging to Si 3 N 4 The field of ceramic preparation. Background technique [0002] Since Si 3 N 4 The Si-N covalent bond in ceramics is very strong, so Si 3 N 4 It has a series of excellent properties, such as high strength and high hardness at room temperature and high temperature, good corrosion resistance, oxidation resistance and thermal shock resistance, etc. Besides, since Haggerty and Lightfoot predicted β-Si 3 N 4 With up to 200 ~ 320W m -1 K -1 After the theoretical thermal conductivity, it has been known as high thermal conductivity ceramics. Therefore, Si 3 N 4 Cerami...

Claims

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Application Information

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IPC IPC(8): C04B35/593
CPCC04B35/593C04B2235/3206C04B2235/3813C04B2235/96C04B2235/9607
Inventor 曾宇平梁汉琴王为得左开慧夏咏锋姚冬旭尹金伟
Owner 江西中科上宇科技有限公司
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