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Silicon nitride ceramic with directionally grown surface crystal grains and preparation method of silicon nitride ceramic

A silicon nitride ceramic and grain orientation technology, applied in the field of non-oxide ceramic preparation, can solve problems such as high interfacial stress, and achieve the effects of improved mechanical strength, simple and stable process, and excellent hydrophobicity

Active Publication Date: 2021-03-05
中国科学院上海硅酸盐研究所苏州研究院 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the method of surface modification of materials is often to prepare a layer of hydrophobic film on the surface of materials by coating and deposition. The above methods have high interfacial stress due to the existence of interfaces.

Method used

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  • Silicon nitride ceramic with directionally grown surface crystal grains and preparation method of silicon nitride ceramic
  • Silicon nitride ceramic with directionally grown surface crystal grains and preparation method of silicon nitride ceramic
  • Silicon nitride ceramic with directionally grown surface crystal grains and preparation method of silicon nitride ceramic

Examples

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Effect test

Embodiment 1

[0052] 31.13g of silicon nitride powder and 2.20g of composite sintering aid (Y 2 o 3 , MgO and TiO 2 The molar ratio is 2:5:3) powder as raw material, absolute ethanol as solvent, placed in a ball mill tank for ball milling for 4 hours, then the dried and sieved mixture was placed in a mold, and dry-pressed at 30MPa to form the obtained The green body was formed by cold isostatic pressing at a pressure of 300 MPa. The obtained ceramic green body was placed in a carbon tube furnace, and the temperature was raised to 900° C. under vacuum conditions, and kept for 2 hours to obtain a silicon nitride ceramic body. Then, the temperature was raised to 1800° C. at a heating rate of 10° C. / min, kept for 2 hours, and then the temperature was lowered with the furnace to obtain a silicon nitride ceramic matrix material. The surface of the obtained sample (silicon nitride ceramic base material) was polished (mirror polishing), and further annealed at 1700°C for 2 hours. The density and ...

Embodiment 2

[0054] 31.07g of silicon nitride powder and 2.26g of composite sintering aid (Y 2 o 3 , MgO and Sc 2 o 3 The molar ratio is 2:5:2) powder as raw material, absolute ethanol as solvent, placed in a ball mill tank for ball milling for 4 hours, then the dried and sieved mixture was placed in a mold, and dry-pressed at 30MPa to form the obtained The green body was formed by cold isostatic pressing at a pressure of 300 MPa. The obtained ceramic green body was placed in a carbon tube furnace, and the temperature was raised to 900° C. under vacuum conditions, and kept for 2 hours to obtain a silicon nitride ceramic body. Then, the temperature was raised to 1900°C at a heating rate of 10°C / min, held for 2 hours, and the nitrogen pressure was 0.6MPa, and then the temperature was lowered with the furnace to obtain a silicon nitride ceramic matrix material. The surface of the obtained sample was polished (mirror polishing), and further annealed at 1800°C for 2h, the material density an...

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Abstract

The invention relates to a silicon nitride ceramic with directionally grown surface crystal grains and a preparation method of the silicon nitride ceramic. The silicon nitride ceramic with directionally grown surface crystal grains comprises a silicon nitride ceramic matrix with beta-Si3N4 as a main phase, and a film layer which is formed by long rod-like beta-Si3N4 crystal grains and is directionally grown on the surface of the silicon nitride ceramic matrix in situ, the diameter of the long-rod-shaped beta-Si3N4 crystal grains is 200 nanometers to 2 micrometers, and the length is 2-5 micrometers.

Description

technical field [0001] The invention relates to a preparation method for directional growth of homogeneous crystal grains on the surface of silicon nitride ceramics, belonging to the technical field of non-oxide ceramic preparation. Background technique [0002] Silicon nitride ceramics have excellent mechanical properties, including high flexural strength and fracture toughness, good thermal shock resistance, low high temperature creep, and good wear resistance and corrosion resistance. It is used in the field of structural ceramics, such as automobiles, aerospace, deep-sea equipment, and electrical and electronic. [0003] Although silicon nitride itself has good corrosion resistance, there will be more or less corrosion, which will reduce the service life of the material. Especially when used in moisture-rich environments. Therefore, the hydrophobicity of the material can be improved by modifying its surface, and the service life of the material can be extended. The cu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/584C04B35/622C04B35/64
CPCC04B35/584C04B35/622C04B35/64C04B41/009C04B41/5066C04B2235/6562C04B2235/6567C04B2235/662
Inventor 张景贤段于森刘宁
Owner 中国科学院上海硅酸盐研究所苏州研究院