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A kind of preparation method of high-performance silicon nitride porous ceramics

A technology of porous ceramics and silicon nitride, applied in the field of ceramic materials, can solve the problems of low bending strength, complicated preparation process, and low bending strength of porous ceramics

Active Publication Date: 2021-05-11
GUANGDONG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Currently, the Si 3 N 4 The research of porous ceramics mainly focuses on improving its flexural strength while maintaining a certain porosity. For example, Han et al. used slurry injection method and silica gel circulation infiltration method to prepare fused silica fiber reinforced porous Si under the reaction condition of 750 °C. 3 N 4 The results show that the addition of fused silica fibers can effectively improve the flexural strength of the material. At such a low sintering temperature, the flexural strength of the material can reach 57MPa. At high test frequencies, the dielectric constant is 2.8~3.1, but this Si 3 N 4 The flexural strength of porous ceramics is still low
Ding et al prepared Si by reaction and sintering in an oxidizing atmosphere at a temperature between 1200°C and 1500°C. 3 N 4 Porous low dielectric ceramic material, Si 3 N 4 In a high-temperature oxidative atmosphere, it is easy to generate silica and adhere to the surface of the powder, and the powders are connected together by silica, and the gaps exist between the powders. The prepared porous Si 3 N 4 The bending strength of ceramics reaches 136MPa, and the dielectric constant reaches 3.1; however, the preparation process of this method is complicated and the bending strength is low

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] A preparation of high-performance silicon nitride porous ceramics, the specific method is as follows:

[0029] (1) Using Si powder as the base material, MgO-Yb 2 o 3 、TiO 2 -B is a sintering aid according to Si:MgO-Yb 2 o 3 : TiO 2 - The volume fraction ratio of B is 87%: 5%: 8%. After mixing and drying, Si-MgO-Re 2 o 3 -TiO 2 The mixed powder of -B; said MgO-Yb 2 o 3 MgO:Yb 2 o 3 The volume fraction ratio is 60%: 40%; the TiO 2 -TiO in B 2 : B volume fraction ratio is 70%: 30%. in TiO 2 Generate TiB with B according to reaction (1) 2 After that, the reaction product B 2 o 3 It can be used as a pore-forming agent and volatilizes above 1000°C, TiO 2 It can be used as Si powder nitriding catalyst.

[0030] 3TiO 2 +10B→3TiB 2 +2B 2 o 3 (2)

[0031] (2) Si-MgO-Yb 2 o 3 -TiO 2 -B The mixed powder is put into a metal mold for molding, and then a green body with a diameter of 30mm is obtained after cold isostatic pressing at 50MPa.

[0032] (3) Put ...

Embodiment 2

[0035] According to Si powder (particle size2 o 3 The volume fraction is 2%, ZrO 2 The volume fraction of B is 5.6%, and the volume fraction of B is 2.4%. After mixing and drying, Si-MgO-Yb 2 o 3 -ZrO 2 - the mixed powder of B; and prepare high-performance silicon nitride porous ceramic material according to the method described in Example 1.

[0036] The porosity of the high-performance silicon nitride porous ceramic material prepared in this example is 65%, the pore diameter is about 80 μm, the hardness is 4 GPa, and the fracture toughness is 3 MPa m 1 / 2 , The flexural strength is 280MPa.

Embodiment 3

[0038] According to Si powder (particle size2 The volume fraction is 2%, HfO 2 The volume fraction of B is 6%, and the volume fraction of B is 2%. After mixing and drying, Si-MgO-CeO 2 -HfO 2 - the mixed powder of B; after obtaining the green body with a diameter of 40mm according to the method described in Example 1, put the green body into the graphite crucible of the tube furnace, and raise the temperature at a heating rate of 10°C / min in a vacuum state to 950°C, and keep it warm for 2 hours; then raise the temperature to 1250°C at a rate of 8°C / min under vacuum, and then introduce 0.2MPa flowing N 2 , and the temperature was raised to 1380°C at a heating rate of 5°C / min, and kept for 2 hours; the temperature was raised to 1500°C at a heating rate of 3°C / min, and kept for 4 hours, thereby obtaining a high-performance nitrogen with a three-dimensional interlocking network structure silicon porous ceramic material.

[0039] The high-performance silicon nitride porous ceram...

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Abstract

The invention discloses a preparation method of high-performance silicon nitride porous ceramics, which uses Si powder as the base material and MgO‑Re 2 o 3 As a sintering aid, MO‑B is used as a sintering aid and a nitriding catalyst. After mixing and drying, Si‑MgO‑Re 2 o 3 ‑MO‑B mixed powder, and then obtained a green body by cold isostatic pressing; then the green body was subjected to temperature programming to obtain a high-performance silicon nitride porous ceramic with a three-dimensional network interlocking structure. The porous ceramic prepared by the invention has high porosity, high bending strength and simple preparation process.

Description

technical field [0001] The invention relates to the field of ceramic materials, in particular to a preparation method of high-performance silicon nitride porous ceramics. Background technique [0002] Silicon nitride (Si 3 N 4 ) Ceramic materials have the characteristics of high mechanical strength, high temperature resistance, corrosion resistance, low dielectric constant (5.6) and low dielectric loss, and are regarded as future aviation materials, such as missile radomes and military GPS antennas. Currently, the Si 3 N 4 The research of porous ceramics mainly focuses on improving its flexural strength while maintaining a certain porosity. For example, Han et al. used slurry injection method and silica gel circulation infiltration method to prepare fused silica fiber reinforced porous Si under the reaction condition of 750 °C. 3 N 4 The results show that the addition of fused silica fibers can effectively improve the flexural strength of the material. At such a low sin...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B38/00C04B35/591C04B35/622C04B35/626C04B35/64
Inventor 于俊杰魏万鑫郭伟明林华泰
Owner GUANGDONG UNIV OF TECH