JPH0543300A - Drying method for ceramics blank body - Google Patents

Abstract

PURPOSE:To provide a drying method capable of drying a thick-wall ceramics blank body in a short period without leaving a crack and a strain. CONSTITUTION:The hot air circulation pipes 31, 32 are provided so that the hot air of a circulating device 30 is passed through the internal hole 11 of a ceramics blank body 10 formed into a prescribed shape. Furthermore the ceramics blank body 10 is surrounded with cloth 40 having moisture permeability. Then the hot air circulating device is actuated and hot air is circulated and the ceramics blank body 10 is dried thereby.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drying a ceramic body.

[0002]

2. Description of the Related Art Conventionally, a so-called casting method has been widely used as a method for molding ceramic materials such as refractory materials and ceramics by pouring slurry raw material powder into a molding die. Since the ceramic body molded by such a method contains a large amount of water, it is necessary to once dry it to reduce the water content before firing.

[0003]

When water is lost from the ceramic body containing water, shrinkage occurs at that part. When water is uniformly lost from each part of the ceramic body, shrinkage occurs in the same direction, and no strain remains in the body.
However, when the drying speed of the ceramic body is increased, the evaporation of water becomes remarkable at the surface portion, resulting in a large difference in water concentration from the inside of the body. As a result, the contraction of the surface portion occurs earlier than in the inside of the element body, the surface portion is distorted, and the crack is easily generated. Further, even after the surface portion is dried and solidified, the moisture remaining inside may contract when the moisture dries, and cracks may occur inside the element body.

For this reason, when drying a ceramic body, especially a thick ceramic body, for example, natural drying is performed so that the difference in water concentration between the surface portion and the inside does not become large.
It is done by a very slow drying method. However, in such a method, it is necessary to spend a long period of time to dry the element body, and it is difficult to efficiently dry the element body.

An object of the present invention is to provide a method for drying a ceramic body which does not leave cracks or strains in the ceramic body and can be dried in a short period of time.

[0006]

As a result of various studies, the inventor of the present invention suppresses the evaporation of water from the surface of a ceramic body and accelerates the diffusion rate of water inside the body. The inventors have found that the above object can be achieved and propose the present invention.

That is, the method for drying a ceramic body according to the present invention is characterized in that the ceramic body formed into a predetermined shape is surrounded by a cloth having moisture permeability, and then the ceramic body is heated and dried. And

[0008]

In the method for drying a ceramic body of the present invention, by heating the ceramic body, the diffusion rate of water from the inside of the body to the surface portion is increased, and the evaporation rate of water from the surface is increased. .. For this reason, the amount of water vaporized from the ceramic body increases, but when it becomes equal to the moisture permeability of the entire cloth, that is, when the space surrounded by the cloth and the ceramic body becomes a vapor pressure saturated atmosphere, Evaporation of water from the body surface is suppressed. As a result, the water concentration in each part inside the element body becomes substantially uniform, and the shrinkage of the ceramic element body proceeds in the same direction. When the ceramic body is dried and the amount of water vapor is reduced to fall below the moisture permeability of the entire cloth, the surface portion is dried more than the inside of the body, causing a moisture concentration gradient. At this time, the contraction of the element body is almost completed, and the distortion due to the difference in water concentration does not occur.

In the method for drying a ceramic body of the present invention, any cloth can be used as long as it has moisture permeability. The evaporation rate of water from the surface of the ceramic body is limited by the moisture permeability of the cloth,
The moisture vapor transmission capacity of the fabric can be adjusted, for example, by covering a portion of the fabric with a non-moisture permeable fabric.

If a layer reflecting far infrared rays is formed on the surface of the cloth surrounding the ceramic body by coating or the like, the heating energy given to the ceramic body is mainly used for evaporation of water, and Since the temperature decrease on the surface of the ceramic body due to the evaporation of water can be suppressed, the drying can be efficiently performed.

In the method for drying a ceramic body according to the present invention, various methods can be applied as a method for heating the body.
A method of circulating moist warm air between the element body and the cloth is preferable because the ceramic element body can be efficiently heated. In the case of an element body having a hollow portion, a method of circulating moist warm air in the hollow portion is particularly effective.

[0012]

EXAMPLE A method for drying a ceramic body of the present invention will be described below with reference to FIG. In the figure, 10 is a ceramic body, 20 is a mounting table, 30 is a warm air circulation device, and 40 is a cloth.

First, a cylindrical ceramic body 10 having a wall thickness of 50 mm, a length of 2000 mm, a diameter of 370 mm and a weight of 250 kg was manufactured by casting. The water content of the ceramic body 10 was about 13 wt%.

Next, the ceramic body 10 is placed on the mounting table 20.
After mounting on top, the warm air circulation pipes 31 and 32 were installed so that the warm air from the warm air circulation device 30 could pass through the inner hole 11 of the ceramic body 10. Further, the ceramic body 10 was subjected to a moisture permeability of 0.6 g H ₂ O / min. Wrapped in a cloth 40 of / m ² . The ceramic body 10 and the cloth 4
A spacer (not shown) was interposed between the two and 0, and a space of about 20 mm was provided between them.

When the warm air circulation device was operated in this state to dry the ceramic body 10, 10
By drying for one day, the ceramic body 10 could be made into a calcinable state (water content of about 4 wt%). Further, no cracks were observed in the ceramic body 10. The temperature of the hot air to be circulated was maintained at 45 to 50 ° C., and the circulation circuit of the hot air had a closed structure so as to maintain the saturated steam pressure.

For comparison, when the ceramic body produced in the same manner as above was naturally dried, it took about 3 months until it could be fired.

[0017]

As described above, according to the method for drying a ceramic body of the present invention, it is possible to dry the ceramic body in a short period of time without leaving any distortion or cracks. It is suitable for drying thick ceramic bodies.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

[Explanation of symbols]

 10 Ceramics body 30 Warm air circulation device 40 Cloth

Claims (2)

[Claims] 1. A method for drying a ceramics body, comprising enclosing a ceramics body molded in a predetermined shape with a moisture-permeable cloth and then heating and drying the ceramics body. 2. The method for drying a ceramic body according to claim 1, wherein the moisture-permeable cloth has a layer that reflects far infrared rays on at least a part of a surface surrounding the ceramic body. ..