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Vacuum freezing and drying process for ceramic cast blank

A vacuum freeze-drying and ceramic casting technology, which is applied in the field of precision casting, can solve the problems of large drying shrinkage, low dimensional accuracy, easy deformation and cracking of the green body, and achieve the goals of reducing deformation and cracking, improving dimensional accuracy, and reducing shrinkage. Effect

Active Publication Date: 2009-01-07
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the shortcomings of large drying shrinkage, low dimensional accuracy, and easy deformation and cracking of the green body when the ceramic casting mold body is formed by wet method, and to provide a method that can make the green body dry during drying without increasing the viscosity of the slurry. Vacuum freeze-drying process for reducing shrinkage, improving dimensional accuracy, and reducing deformation and cracking of ceramic casting blanks

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] Example 1, making a cuboid sample of 4mm×10mm×60mm, using a wet molding method to prepare a ceramic slurry with a solid phase volume fraction of 55% and a water content of 17%, and pour the slurry into a 4mm×10mm×60mm In the resin mold, the slurry solidifies after about 10 minutes; first pre-freeze the freezer to -46°C, then put the water-based ceramic casting body into the freezer, and freeze for 2 hours to make the water-based ceramic casting blank The moisture in the body completely freezes into ice crystals; vacuumize to keep the pressure in the vacuum chamber at about 10Pa; raise the temperature of the body from freezing to -6°C at a heating rate of 5°C / hour, and then stabilize at -6°C until it is completely dry; after it is completely dry, open the inflation valve, turn off the vacuum pump, and take out the sample to obtain a ceramic casting green body with little shrinkage and no cracks. After comparing the green body obtained in the present invention with the gr...

Embodiment 2

[0014] Example 2, making a complex ceramic mold for a gas turbine blade, using a wet molding method to prepare a ceramic slurry with a solid phase volume fraction of 50% and a water content of 22%, and using a light curing molding machine to manufacture a slurry pouring system The complex ceramic casting resin mold, pour the slurry into the resin mold, and the slurry will solidify after about 10 minutes; first pre-freeze the freezer to -50°C, and then put the water-based ceramic casting body into the freezer , frozen for 4 hours, so that the water in the water-based ceramic casting body completely freezes into ice crystals; vacuumize to keep the pressure in the vacuum chamber at about 10Pa; use a heating rate of 5°C / hour to make the green body from frozen The temperature rises to -6°C, and then stabilizes at -6°C until it is completely dry; after drying, finally, open the inflation valve, turn off the vacuum pump, and take out the sample to obtain a ceramic casting body with li...

Embodiment 3

[0015] Example 3: Prepare a ceramic slurry with a solid phase volume fraction of 58% and a water mass fraction of 16% by wet molding, then pour the slurry into the mold to be prepared and solidify the slurry; first prefreeze the freezer to -75°C, then put the water-based ceramic casting body into the freezer and freeze for 3 hours, so that the water in the water-based ceramic casting body will completely form ice crystals; vacuumize to maintain the pressure in the vacuum chamber At about 10Pa; with a heating rate of 2°C / hour, the temperature of the green body is raised from the frozen temperature to -10°C, and then stabilized at -10°C until it is completely dry; after drying, ceramics with small shrinkage and no cracks can be obtained Cast blank.

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Abstract

The invention relates to a vacuum freeze drying process for a ceramic mould body. The vacuum freeze drying process comprises the steps of putting a water based ceramic mould body moulded by using the wet method in a vacuum freeze drier for prefreezing; after the water in the body is completely crystallized; the vacuum freeze drier is vacuumized while the temperature of the material is controlled so that the water is directly sublimed into water vapor and is pumped away; after the material is completely dry, the ceramic mould body with small drying shrinkage without crack. By applying the vacuum freeze drier in the preparation of the ceramic mould body, the shrinkage of the ceramic mould at the dry stage is significantly reduced; the dimensional accuracy is improved; the probability of distortion and crack is reduced. The vacuum freeze drying process is in particular applicable for drying ceramic mould bodies in complicated shapes.

Description

technical field [0001] The invention belongs to the field of precision casting, and in particular relates to a vacuum freeze-drying process for a ceramic casting mold body. Background technique [0002] The preparation of ceramic casting blank is the basis of precision casting production. At present, in order to manufacture ceramic molds with complex shapes, people mainly use wet molding to make ceramic mold blanks, that is, first add water and dispersant to the powder to make slurry, and then pour the slurry into the mold to form body. [0003] After the green body is formed, it must be dried before it can be sintered. The traditional drying methods are: (1) evaporation, which includes convection, radiation, microwave and other drying methods; (2) using liquid desiccants, such as ethanol, polyethylene glycol, etc.; The capillary exits while the solid phase remains in the mold. Such as plaster mold, porous material mold. When drying with the above drying methods, the wa...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/622
Inventor 李涤尘崔锋录吴海华郭楠楠
Owner XI AN JIAOTONG UNIV
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