Near shape preparation method of multiphase ceramic Si3N4-SiC

A technology of complex phase ceramics and close dimensions, which is applied in the direction of ceramic forming machines and manufacturing tools, which can solve the problems of composition and morphology differences of deposition products, affect the densification process, increase the preparation cost, etc., and achieve good uniformity and no impurities , The effect of stable absorbing performance

Active Publication Date: 2014-06-04
NORTHWESTERN POLYTECHNICAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the CVI process equipment is complex and difficult to control, and the reaction produces many intermediate products. Small changes in deposition conditions often lead to significant differences in the composition and morphology of deposition products, and at the same time affect the densification process, resulting in a long production cycle.
[0007] Traditional preparation of Si 3 N 4 -Due to the limitation of the mold for SiC components, the shape of the prepared test piece is simple, and if the shape of the component changes slightly, the mold needs to be prepared again, which increases the production cost

Method used

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  • Near shape preparation method of multiphase ceramic Si3N4-SiC
  • Near shape preparation method of multiphase ceramic Si3N4-SiC
  • Near shape preparation method of multiphase ceramic Si3N4-SiC

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Embodiment 1: Si 3 N 4 Powder and sintering aid Lu 2 o 3 Mix at 97:3 by weight, add 5% dextrin as a binder, and use distilled water as a medium for ball milling for 96 hours to fully mix to obtain a slurry. The slurry was put into a freeze dryer to freeze for 10 hours, the freezing temperature was -80° C., and vacuum dried for 10 hours. The absolute pressure in the freeze dryer was 5 Pa, and the drying temperature was 70° C. The dried powder is sieved, and the sifted powder is put into a three-dimensional printer (Z510) to print in a size of 27mm×14mm×4mm, and the thickness of the printed layer is about 0.05mm. The printed samples were dried for more than 1 hour and taken out. The formed body was oxidized in air at 600°C for 5h, and the Si 3 N 4 The preform is sintered at 1700°C for 3 hours under a nitrogen atmosphere, and the pressure is 0.35MPa, which is Si 3 N 4 porous ceramics. The sintered Si 3 N 4 The preform was vacuum impregnated in polysiloxane for 3...

Embodiment 2

[0032] Embodiment 2: Si 3 N 4 Powder and sintering aid Lu 2 o 3 Mix by weight percentage 93:7, add 15% dextrin as a binder, and use distilled water as a medium for ball milling for 48 hours to make it fully mixed to obtain a slurry. The slurry was put into a freeze dryer to freeze for 6 hours, the freezing temperature was -60° C., and vacuum dried for 15 hours. The absolute pressure in the freeze dryer was 10 Pa, and the drying temperature was 60° C. The dried powder is sieved, and the sifted powder is put into a three-dimensional printer (Z510) to print in a size of 27mm×12mm×4mm, and the thickness of the printed layer is about 0.085mm. The printed samples were dried for more than 1 hour and taken out. The formed green body was oxidized in air at 750°C for 3h, and the Si 3 N 4 The preform is sintered at 1900°C for 1h under a nitrogen atmosphere, and the pressure is 0.3MPa, which is Si 3 N 4 porous ceramics. Add 7wt% ferrocene into polysiloxane, and mix for 15 minutes...

Embodiment 3

[0034] Embodiment 3: Si 3 N 4 Powder and sintering aid Lu 2 o 3 Mix by weight percentage 93:7, add 15% dextrin as a binder, and use distilled water as a medium for ball milling for 48 hours to make it fully mixed to obtain a slurry. The slurry was put into a freeze dryer to freeze for 6 hours, the freezing temperature was -60° C., and vacuum dried for 15 hours. The absolute pressure in the freeze dryer was 10 Pa, and the drying temperature was 60° C. The dried powder is sieved, and the sifted powder is put into a three-dimensional printer (Z510) to print in a size of 20mm×14mm×4mm, and the thickness of the printed layer is about 0.5mm. The printed samples were dried for more than 1 hour and taken out. The formed body was oxidized in air at 800°C for 2h, and the Si 3 N 4 The preform is sintered at 1900°C for 1h under a nitrogen atmosphere, and the pressure is 0.25MPa, which is Si 3 N 4 porous ceramics. Add 2wt% ferrocene into polysiloxane, and mix for 15 minutes at 80°...

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Abstract

The invention relates to a near shape preparation method of multiphase ceramic Si3N4-SiC, which completes component molding directly by bonding between particles through a three-dimensional printing method, needs no dies, and is capable of molding components with complex shapes. The Si3N4-SiC multiphase ceramic prepared by 3DP combined with PIP methods solves the problem of nonuniformity of CVI methods, and SiC nanocrystallines and SiC nanowires are uniformly distributed in a Si3N4 substrate. The Si3N4-SiC composite ceramic which is continuous, compact, free of impurities, good in uniformity and stable in wave absorbing property is obtained by using Si3N4 powder and polycarbosilane as raw materials through steps of three-dimensional printing, sintering, dipping, curing, cracking and heat treatment.

Description

technical field [0001] The invention relates to a composite phase ceramic Si 3 N 4 - Near-scale fabrication of SiC. In particular, it involves three-dimensional printing (hereinafter referred to as 3DP) to prepare silicon nitride ceramic substrates and polymer impregnation pyrolysis (hereinafter referred to as PIP) to synthesize Si 3 N 4 -SiC near-scale preparation method. Background technique [0002] Si 3 N 4 And SiC ceramics have outstanding advantages such as low density, good oxidation resistance, high temperature resistance, high specific strength, high specific modulus, good thermal conductivity, and corrosion resistance. They have great application prospects as structural materials and functional materials. Si 3 N 4 -SiC composite phase ceramics overcome the shortcomings of low fracture toughness and grain growth during sintering of single-phase ceramics, and show higher strength at high temperatures. Porous Si 3 N 4 The dielectric constant and dielectric ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/596C04B35/622B28B1/00C04B41/87
Inventor 殷小玮段文艳李权张立同成来飞
Owner NORTHWESTERN POLYTECHNICAL UNIV
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