JPH06305841A - Refractory slab for burning ceramic - Google Patents

Abstract

PURPOSE:To keep a coloring substance in a material to be burned so as not to diffuse onto a refractory slab and prevent the refractory slab from occurrence of discoloration by including same substance as a diffusible coloring substance contained in the material to be burned in the refractory slab. CONSTITUTION:This refractory slab is produced by forming and burning a mixture obtained by adding a coloring substance [e.g. iron(III) oxide] contained in a material to be burned to an inorganic fiber and refractory powder used as main components. By this refractory slab, the coloring substance is diffused through a contact face of the material to be burned containing a diffusible coloring substance therein with the refractory slab and occurrence of discoloration is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic baking shelf for placing a material to be fired in a firing process for producing ceramics.

[0002]

2. Description of the Related Art A plate-shaped support material on which a material to be fired is placed in a ceramics firing process is called a shelf board, and refractory materials having various compositions are used. In recent years, heat-resistant inorganic fibers and refractory powders have been used. Light weight refractories made by molding and sintering a mixture (for example, alumina powder) have become widely used because of their excellent heat insulation and thermal shock resistance.

However, when a shelf plate made of this kind of lightweight refractory is used in a ceramics firing process, the raw material of the ceramics is a coloring substance such as ferric oxide added as an impurity (or added for coloring or other purposes). If it is contained as a small amount of substance), the coloring of the product by the coloring substance becomes light only in the portion in contact with the shelf plate, and uneven coloring occurs as a whole. A typical example in which such a phenomenon is observed is when a clay mineral containing iron as an impurity is used as a raw material in the production of mullite ceramics, cordierite ceramics and the like. The color unevenness often causes no inconvenience in practical use, but reduces the commercial value.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lightweight refractory material which is improved so as not to cause the above-mentioned color unevenness even when used for supporting an object to be fired containing a coloring substance. To provide a shelf board.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to a ceramics baking shelf for an object to be baked containing a diffusible coloring material, wherein the shelf comprises a mixture containing inorganic fibers and refractory powder as main components. It is characterized by being formed and fired and containing the same substance as the diffusible coloring substance.

In the case of manufacturing a ceramic product which is likely to cause color unevenness, color unevenness does not occur if the shelf plate is made to contain the same substance as the coloring substance contained in the ceramic raw material. The reason is considered as follows. The composition of the ceramic baking shelf has been devised so that it will not react with the material to be baked when it is used for baking, but the composition of the material to be baked is still through the contact surface between the object and the shelf. Some of the ingredients may diffuse into the shelf. When a part of such easily diffused components diffuses to the side of the shelf, the composition to be fired changes only in the vicinity of the contact surface with the shelf. When the constituent components of the ceramic are basically white or light-colored, if the diffused substance is a colored substance, it causes color unevenness. In the above example, a part of the ferric oxide in the clay mineral as the raw material diffuses to the shelf plate, which causes color unevenness (in this specification, the coloring substance that easily diffuses is referred to as a diffusible coloring substance). . However, when the same substance as the diffusible coloring substance in the fired product is contained in the shelf plate according to the present invention, there is no difference in the concentration of the coloring substance at the boundary of the contact surface between the fired product and the shelf plate. However, the amount is so small that diffusion does not substantially occur, the diffusion of the coloring substance is prevented, and the product does not have uneven color.

In the shelf board of the present invention, a small amount of a substance capable of finally leaving the same coloring material as the diffusible coloring material contained in the material to be fired placed on the shelf board is added to the shelf board manufacturing raw material, It can be produced by any method using any raw material. The usable coloring substance-forming additive is the same substance as the diffusible coloring substance contained in the baking object to be placed on the shelf plate, or the same as the diffusible coloring substance in the manufacturing process of the shelf plate. It is a substance that is converted into the substance.

A typical method for manufacturing the shelf board of the present invention will be described in detail. Ceramic fibers such as alumina fibers and silica / alumina fibers and refractory powder such as alumina are contained in a weight ratio of about 15 to 50:50. The mixture is mixed at a ratio of 85, and an appropriate amount of an inorganic binder (corridal silica or the like), a coloring substance-forming additive and water are added, and the obtained slurry mixture is dehydrated and then calcined at about 1400 to 1600 ° C. When the diffusible coloring substance contained in the material to be fired is ferric oxide,
The substances that can be added to the raw materials for producing shelves as the coloring substance-forming additive are ferric sulfate, ferric chloride, ferric oxide, fine iron powder and the like. In that case, it is appropriate that the addition amount be 0.5 to 2.0% by weight in terms of ferric oxide based on the product.

[0009]

【Example】

Example 1, Comparative Example 1 When a cordierite-based ceramic is manufactured by firing a molded product made of a mixture of kaolin, talc, alumina, etc., the raw material kaolin or clay containing kaolin as a main component has Fe ₂ Fe ₂ as an impurity. It contains about 1% in terms of O _3. Therefore, the product obtained through the firing step is colored pale yellow. The color tone of this coloring slightly changes depending on the content of iron oxide.

A shelf plate (bulk density 1.0 g / cm ³ ) obtained by press-molding a slurry obtained by adding water to the following raw materials into a plate and firing the molded product at 1550 ° C. It was used as a shelf plate for firing the above cordierite ceramics. High alumina fiber 30 parts by weight Silica / alumina fiber 20 〃 Alumina powder 50 〃 Colloidal silica 10 〃

The obtained ceramic had a whitish color tone on the surface in contact with the shelf plate as compared with the other portions.
Also, when the content of ferric oxide was examined, it was found that the content of ferric oxide at a position sufficiently distant from the contact surface with the shelf was 0.6% by weight, whereas 0 on the contact surface.
It was 4% by weight.

In producing the shelf board by the same method as above, 1 part by weight of ferric sulfate in terms of ferric oxide was added to produce the shelf board of the present invention, which was produced in the same manner as above. It was used for firing cordierite ceramics. The obtained ceramic had a uniform color tone throughout, and no lightening was observed on the contact surface with the shelf plate. When the content of ferric oxide at the contact surface with the shelf plate and at a position sufficiently distant from the contact surface was examined, both were 0.6% by weight, and there was no difference.

[0014]

As described above, when the shelf board of the present invention is used for firing ceramics containing a diffusible coloring substance, it is possible to prevent uneven coloring of the ceramics. Also,
Since the means for preventing color unevenness only includes a small amount of the same substance as the diffusible coloring substance in the shelf board, the lightweight and thermal shock resistance of the shelf board base material made of inorganic fibers and refractory powder are impaired. Nor.

Claims (1)

[Claims] 1. A shelf for firing ceramics for a material to be fired containing a diffusible coloring material, which is obtained by molding and firing a mixture containing inorganic fibers and refractory powder as main components. A shelf plate for firing ceramics, which is present and contains the same substance as the diffusible coloring substance.