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Self-spread high-temp synthesis process for preparing beta-silicon nitride whisker

A self-propagating high-temperature, whisker technology, which is applied in the preparation of β-Si3N4 whiskers and self-propagating high-temperature synthesis to prepare β-Si3N4 whiskers, which achieves the effects of convenient operation, low energy consumption and high yield

Inactive Publication Date: 2002-02-06
SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, people have applied the SHS method to prepare a variety of materials and their powders, such as carbide TiC, ZrC, SiC, WC, silicide MoSi 2 、TaSi 2 , ZrSi 2 , Nitride TiN, BN, AlN, α-Si 3 N 4 , β-Si 3 N 4 Wait, but there is no self-propagating method to prepare β-Si 3 N 4 whiskers report

Method used

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  • Self-spread high-temp synthesis process for preparing beta-silicon nitride whisker
  • Self-spread high-temp synthesis process for preparing beta-silicon nitride whisker
  • Self-spread high-temp synthesis process for preparing beta-silicon nitride whisker

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Experimental program
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Effect test

Embodiment 1

[0026] Silicon fume and α-Si 3 N 4 powder in a ratio of 1:1, then add Whisker Growth Aid Y 2 o 3 , the addition amount is Si powder and α-Si 3 N 4 5wt% of the total weight of the powder, the powder is evenly mixed and loosely packed in a porous graphite crucible with an outer diameter of φ60mm x an inner diameter of φ55mm x a height of φ60mm and the inner wall is coated with boron nitride, and the bulk density is 0.71g / cm 3 , and placed in a high-pressure container, filled with 5MPa nitrogen gas (purity 99.9%) after vacuuming, and self-propagating high-temperature synthesis of β-Si by energizing and igniting 3 N 4 For whiskers, the reaction time is no more than 5 minutes, and natural cooling is adopted after synthesis.

[0027] β-Si prepared by the above process 3 N 4 The yield of the whiskers is close to 100%, the length is 10-20 μm, the diameter is 1-2 μm, the average length-to-diameter ratio is ~10, the crystal structure is complete, and the surface is smooth and fr...

Embodiment 2

[0029] Silicon fume and α-Si 3 N 4 Powder mixed in a ratio of 7:3, then add the whisker growth aid La 2 o 3 , the addition amount is Si powder and α-Si 3 N 4 0.5wt% of the total weight of the powder, the powder is evenly mixed and loosely packed in a porous graphite crucible with an outer diameter of φ60mm x an inner diameter of φ55mm x a height of φ60mm and an inner wall coated with boron nitride, and the bulk density is 0.70g / cm 3 , and placed in a high-pressure container, filled with 5MPa nitrogen gas (purity 99.9%) after vacuuming, and self-propagating high-temperature synthesis of β-Si by energizing and igniting 3 N 4 For whiskers, the reaction time should not exceed 8 minutes, and natural cooling should be adopted after synthesis.

[0030] β-Si prepared by the above process 3 N 4 The yield of whiskers is close to 100%, the length is 8-13 μm, the diameter is between 0.7-1.5 μm, and the average aspect ratio is ~10. Its crystal structure is complete and its surface...

Embodiment approach 3-

[0031] Embodiment 3 - Self-propagating high-temperature synthesis of β-Si3 N 4 whiskers

[0032] Silicon fume and α-Si 3 N 4 Powder mixed in a ratio of 9:5, then add the whisker growth aid Gd 2 o 3 , the addition amount is Si powder and α-Si 3 N 4 3wt% of the total weight of the powder, the powder is evenly mixed and loosely packed in a porous graphite crucible with an outer diameter of φ60mm x an inner diameter of φ55mm x a height of φ60mm and the inner wall is coated with boron nitride, and the bulk density is 0.68g / cm 3 , and placed in a high-pressure container, filled with 5MPa nitrogen (purity 99.9%) after vacuuming, ignited and self-propagating combustion, and β-Si synthesized by igniting and self-propagating at high temperature 3 N 4 For whiskers, the reaction time is no more than 5 minutes, and natural cooling is adopted after synthesis.

[0033] β-Si prepared by the above process 3 N 4 The whisker yield is close to 100%, the length is 5-10 μm, the diameter i...

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Abstract

A process for preparing beta-Si3N4 whisker by high-temp self-spread synthesis includes mixing Si powder with alpha-Si3N4 powder in a ratio of (5-9):(1-5), adding whisker growing aid, loading in porous graphite crucible with inner surface coated with boron nitride, igniting the raw materials, and reaction in nitrogen atmosphere under 3-10 MPa for 2-10 min. Its advantages are 7-10 of length / diameter ratio, complete structure and smooth surface of crystal, no environmental pollution, and high yield (near 100%).

Description

technical field [0001] The present invention relates to β-Si 3 N 4 Method for the preparation of whiskers, especially β-Si by self-propagating high-temperature synthesis (SHS) 3 N 4 The whisker method belongs to the field of ceramic powder preparation. Background technique [0002] Due to its high temperature strength, high temperature resistance, wear resistance, corrosion resistance, light weight and other advantages, ceramic materials have been successfully applied in aerospace, metallurgy, electronics, automotive engine parts and other fields, but the brittleness of ceramic materials It is an Achilles' heel, and once a crack is generated, it is easy to expand, resulting in catastrophic fracture. In order to improve the toughness of ceramic materials, researchers at home and abroad have done a lot of work in this area, such as particle dispersion toughening, phase transformation toughening, fiber or whisker reinforcement and toughening. Among them, the effect of whis...

Claims

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Application Information

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IPC IPC(8): C30B29/38C30B29/62
Inventor 陈殿营张宝林庄汉锐李文兰
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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