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Tech. for degassing-free gel injecting moulding shaping of mullite-base precision ceramic component

A technology of gel injection molding and precision ceramics, applied in ceramic molding machines, manufacturing tools, applications, etc., can solve problems affecting the uniformity of the molded body, affecting the rheological properties of the slurry, and affecting the performance of ceramic devices, etc., to achieve Non-toxic and side effects, beneficial to environmental protection, accurate size effect

Inactive Publication Date: 2007-05-30
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In the previous gel injection molding process, it is usually necessary to add organic dispersants, such as polypropylene ammonia, ammonium citrate, etc., to increase the solid phase volume fraction of the ceramic slurry, and to use organic monomers and Coagulation agents such as acrylamide, natural gel substances such as gelatin, protein, etc. realize the in-situ solidification of the slurry, but these organic substances have a certain surface activity, and a large number of stable air bubbles will be introduced during the high-speed ball milling and stirring dispersion of the slurry ; At the same time, the solid content of the slurry is high, and the slurry has a relatively high viscosity (~1.0Pa·s). The degassing treatment of the slurry is a crucial step for forming a high-quality green body, but the degassing treatment time should not be too long. Long, otherwise the particles in the highly dispersed slurry will settle unevenly, which will affect the uniformity of the formed body, and the moisture in the slurry will evaporate during the long-term vacuum degassing process, which will affect the rheological properties of the slurry; degassing treatment time It should not be too short, otherwise the air bubbles will not be completely eliminated, and there will be irreparable defects in the formed green body during the sintering process, which will affect the performance of the ceramic device

Method used

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  • Tech. for degassing-free gel injecting moulding shaping of mullite-base precision ceramic component

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Example 1: Forming of mullite-corundum composite ceramic parts

[0021] α-Al 2 O 3 Micro-powder, produced by Henan Zhengzhou Zhongtian Special Alumina Plant, d 50 = 1.68 μm, d 90 = 6.31 μm; silica sol, NS-30 type, produced by Zhejiang Shangyu Yuda Chemical Co., Ltd., the concentration of silica sol is 30%.

[0022] Add 265g of alumina micropowder to 100ml of silica sol, and after stirring evenly, ball mill in a planetary ball mill for 2 hours to obtain a ceramic slurry with a solid phase volume fraction of about 50%, and then add 3.6MNH while stirring. 4 Cl solution to control NH in slurry 4 The Cl concentration is 0.10M, the slurry after stirring is injected into the plastic mold, and placed at 15°C for about 10 minutes. After the slurry is basically solidified, it is demolded after another 30 minutes to obtain a complex-shaped ceramic body with a smooth surface, as shown in the attached picture. 1. The microstructure of the obtained ceramic green body is shown i...

Embodiment 2

[0023] Example 2: Forming of Mullite Ceramic Parts

[0024] α-Al 2 O 3 Micro-powder, produced by Henan Zhengzhou Zhongtian Special Alumina Plant, d 50 = 1.68 μm, d 90 = 6.31 μm; silica sol, NS-30 type, produced by Zhejiang Shangyu Yuda Chemical Co., Ltd., the concentration of silica sol is 30%. 93.5g of alumina micropowder was added to 100ml of silica sol to prepare a silica sol-dispersed alumina slurry conforming to the stoichiometric composition of mullite, and the solid phase volume fraction was only 28.5%. In order to prepare a slurry with a high solid volume fraction, the slurry prepared by direct dispersion is heated at 80°C while stirring to evaporate part of the free water. When the viscosity is about 500mPa·s, stop heating and continue stirring until the slurry is reached. After the material is cooled, it is dispersed in a planetary mill for 5 hours, and the viscosity of the slurry is measured. At the same time, a small amount of slurry is taken to measure the fre...

Embodiment 3

[0025] Example 3: Forming of Mullite / Zirconium Dioxide Composite Ceramic Parts

[0026] α-Al 2 O 3 Micro-powder, produced by Henan Zhengzhou Zhongtian Special Alumina Plant, d 50 = 1.68 μm, d 90 = 6.31 μm; silica sol, NS-30 type, produced by Zhejiang Shangyu Yuda Chemical Co., Ltd., the concentration of silica sol is 30%. Imported zircon powder, made in Australia, 325 mesh, purchased from Changxing Ceramics Raw Material Company.

[0027] Add 211.6g of alumina micropowder and 142.9g of zircon powder to 100ml of silica sol. After stirring evenly, ball-mill in a planetary ball mill for 24h to obtain a ceramic slurry with a solid phase volume fraction of about 50%. Then add while stirring. 3.6MNH 4 Cl solution to control NH in slurry 4 The Cl concentration is 0.06M, the slurry after stirring is injected into the plastic mold, and placed at 60 °C for about 30 minutes. After the slurry is cured, it is demolded after another 30 minutes to obtain a complex-shaped ceramic body wi...

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Abstract

The invention discloses an undegassing gel injection molding technology for mullite based precise ceramic component. It disperses ceramic powder into silica sol solution to make ceramic slime; taking ball grinding; whisking and adding NH4Cl solution, controlling the thickness of NH4Cl and solidification temperature; directly injecting into molding, the ceramic component would be gained after de-mouding. By using the invention, the ceramic component would has smooth surface, accurate size and decrease energy consumption and lower cost.

Description

technical field [0001] The invention relates to material forming technology, in particular to a degassing-free gel injection molding process for mullite-based precision ceramic parts. Background technique [0002] In the past ten years, people have gradually realized that to prepare high-performance ceramic products, green body forming is also one of the key technologies. , such as gel injection molding, direct solidification molding, temperature-induced molding, etc., for the molding of high-performance ceramics, with simple process, low cost, and the ability to form complex shapes of ceramic products in net size, less defects in the green body, and reliable sintered body good sex characteristics. [0003] In the previous gel injection molding process, it is usually necessary to add organic dispersants, such as polyacrylamide, ammonium citrate, etc., during the preparation of the slurry to increase the solid volume fraction of the ceramic slurry, and use organic monomers a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/185C04B35/624C04B33/28B28B1/14
Inventor 孔德玉杨辉
Owner ZHEJIANG UNIV