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Method for improving ceramic mold precision with vacuum freeze-drying technology

A vacuum freeze-drying and ceramic casting technology, which is applied in the field of precision casting, can solve the problems of reducing drying shrinkage, reducing drying shrinkage, and filling capacity constraints, achieving the effects of small drying shrinkage, increased strength, and guaranteed integrity

Active Publication Date: 2015-04-22
XI AN JIAOTONG UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In terms of freeze-drying shrinkage control, the pre-freezing temperature can be reduced to reduce the size of the ice crystals, thereby reducing the drying shrinkage rate, but there is a phenomenon that the mold is too low-temperature frozen to be brittle and cracked; it can also increase the solid phase content of the ceramic slurry to reduce the drying shrinkage. Minimize the porosity of the green body after drying and reduce drying shrinkage, but it is restricted by the flow of slurry and filling ability

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0031] A method for controlling the accuracy of ceramic molds by adopting vacuum freeze-drying technology, comprising the following steps:

[0032] 1) Prepare a water-based alumina ceramic slurry with a solid phase volume fraction of 60% and a premixed liquid fraction of 40%, wherein the solid phase contains alumina fibers with a volume fraction of 2%, and the average length of the alumina fibers is 1000μm, the average diameter is 10μm, the viscosity of the water-based alumina ceramic slurry is 260mPa.s, which meets the pouring requirements;

[0033] Among them, the water-based alumina ceramic slurry is prepared by dry-milling the ceramic powder and alumina fiber in a ball mill tank for 20 minutes without balls, and then adding the premix and balls to wet-mill for 15 minutes;

[0034] The premix is ​​a mixed solution composed of deionized water, acrylamide, and N,N'-methylenebisacrylamide; and acrylamide and N,N'-methylenebisacrylamide account for 15% of the mass of the premix...

Embodiment 2

[0042] A method for controlling the accuracy of ceramic molds by adopting vacuum freeze-drying technology, comprising the following steps:

[0043] 1) Prepare a water-based alumina ceramic slurry with a solid phase volume fraction of 58% and a premixed liquid volume fraction of 42%, wherein the solid phase contains 3.5% volume fraction of carbon fibers, the average length of the carbon fibers is 500 μm, and the average diameter is 7 μm. The viscosity of the carbon fiber ceramic slurry is 305mPa.s, which meets the pouring requirements;

[0044] Among them, the water-based alumina ceramic slurry is obtained by dry-milling ceramic powder and alumina fiber in a ball mill tank for 25 minutes without balls, and then adding a premix solution and balls for wet grinding for 25 minutes. A mixed solution composed of ionic water, acrylamide, and N,N'-methylenebisacrylamide; among them, acrylamide and N,N'-methylenebisacrylamide account for 18% of the mass of the premixed solution, and acr...

Embodiment 3

[0052] A method for controlling the accuracy of ceramic molds by adopting vacuum freeze-drying technology, comprising the following steps:

[0053] 1) Prepare a water-based silica ceramic slurry with a solid phase volume fraction of 60% and a premixed liquid volume fraction of 40%, wherein the solid phase contains 1.5% volume fraction of zirconia fibers, the average length of the zirconia fibers is 800 μm, and the average diameter The viscosity of the water-based silica ceramic slurry is 210mPa.s, which meets the pouring requirements;

[0054] Among them, the water-based zirconia ceramic slurry is obtained by dry-milling ceramic powder and zirconia fiber in a ball mill tank for 15 minutes without balls, and then adding a premix solution and balls to wet mill for 20 minutes. A mixed solution composed of ionic water, acrylamide, and N,N'-methylenebisacrylamide; among them, acrylamide and N,N'-methylenebisacrylamide account for 20% of the mass of the premixed solution, and acryla...

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Abstract

The invention discloses a method for improving ceramic mold precision with a vacuum freeze-drying technology, and relates to the technical field of precision casting. According to the invention, a water-based ceramic slurry containing solid-phase fiber is first prepared based on a gel injection molding technology; the water-based ceramic slurry is cast into a resin mold; when a ceramic mold blank is completely gel-solidified, the blank is placed into a vacuum freeze-drying machine and is subjected to pre-freezing; after a period of time, water in the ceramic mold blank is completely crystallized, vacuuming is carried out, and material temperature is controlled, such that water is directly sublimated from ice into vapor, and is pumped away. When the ceramic mold is thoroughly dried, compared to a ceramic mold blank without fiber, the ceramic mold provided by the invention has lower drying shrinkage, improved strength, and higher precision.

Description

technical field [0001] The invention belongs to the technical field of precision casting, and in particular relates to a method for improving the precision of ceramic molds by adopting vacuum freeze-drying technology. Background technique [0002] Gel injection molding is a ceramic molding technology that combines ceramic preparation technology with polymer chemistry and is widely used for near-net shape of ceramic parts. Gel injection molding technology is suitable for forming complex structural ceramic parts. The composition and density of the molded parts are uniform, the shape and size precision are high, and the green body after drying has high strength and can be directly machined. Green body drying is one of the main process stages of gel injection molding technology, and the drying method directly affects the green body drying accuracy, efficiency and yield. The traditional drying methods are: (1) evaporation, which includes convection, radiation, microwave and othe...

Claims

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Application Information

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IPC IPC(8): C04B35/80C04B35/10C04B35/14C04B35/622B28B1/52
Inventor 李涤尘鲁中良吉喆苗恺田国强
Owner XI AN JIAOTONG UNIV
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