JPS5898427A - Preparation of molded article from ceramic fiber - Google Patents

Abstract

PURPOSE:To obtain a molded article of ceramic fibers capable of reducing the shrinkage thereof in use, by impregnating the ceramic fibers with a small amount of an organic binder, heat-treating the impregnated ceramic fibers at a specific temperature to burn the organic binder and crystallize the ceramic fibers. CONSTITUTION:Ceramic fibers are impregnated with an organic binder, e.g. phenolic resin and compressed to give bulky ceramic fibers. The resultant bulky ceramic fibers are then packed in a mold, and high-temperature air at 200- 900 deg.C is passed through the fibers to burn the organic binder and give the aimed molded article of the partially or wholly crystallized ceramic fibers. The resultant molded article is they preferably impregnated with an aqueous solution a chromium salt, e.g. chromium acetate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a Tough Eye Bar molded article.

In recent years, due to the demand for energy conservation, the adoption of ceramic and tough eyeper molded bodies for the furnace walls has become widespread in various industrial furnaces.

Cerasa and Tough Eye Bar are made by melting a raw material mixture of alumina and silica in a weight ratio of approximately 1:1, and blowing compressed gas as a blowing medium onto this melt to form fibers. −
41! Laminate and tough eye bars are kept in a glass state due to rapid cooling during the O-blowing process.

By the way, conventionally, ceramic fiber molded bodies are manufactured as described above by impregnating ceramic fibers with mainly an inorganic binder, compressing them into a bulk shape, and then drying and heating them to harden the binder. There is.

When the ceramic or tough eye bar molded body produced as described above is used for example on a furnace wall, it is a ceramic.

There are drawbacks such as large shrinkage of the Tough Iver molded product, which may cause delamination of the furnace wall, opening of joints, and cracking.

The cause of the shrinkage of the ceramic fiber molded body is that the glassy state of Ceramic fiber crystallizes at about 1000° C., producing mullite and shrinking the twill lines.

Therefore, if the ceramic fiber is heat-treated at too high a temperature in advance to induce shrinkage below 1000°C, it is thought that the shrinkage rate during use will be reduced even if it is used as a molded body for furnace walls, etc. ↓ .

However, ceramic fiber is a heat insulating material and has a
Heat treatment at a high temperature of 0° C. consumes a large amount of energy, and the strength of the heat-treated fibers decreases, making it difficult to handle them, so there are very few cases in which this method is actually practiced.

The present invention was made in view of the above-mentioned circumstances, and it is said that the ceramic fiber is impregnated with a small amount of organic binder, and then heat treated at a temperature lower than the crystallization temperature to burn off the organic binder. The purpose of the present invention is to provide a method for producing a ceramic fiber molded article that can reduce the shrinkage rate during use.

That is, the first invention of the present application is a glue-like material impregnated with an organic binder and compressed.
The method is characterized in that the organic binder is brought into contact with ~900 CO high temperature air to burn the organic binder, thereby crystallizing part or all of the bulk ceramic.

Also, wish j#! The invention of item 2 is to crystallize a part or all of Tough Eye Perfiber, which is a bulk ceramic impregnated with an organic binder and compressed, and further impregnated with an aqueous solution of aluminum salt to form a mold. .

Examples of the organic binder in the present invention include 7! Examples include norresin. It is desirable to set the relationship between the impregnation ratio of an organic binder such as Koshi97 and Knoll Resin, the bulk specific gravity of the compressed body, and the thickness of the compressed body through which air passes, i. If the impregnated amount of 5-1 is 200'C12 atm of air,
The bulk specific gravity of the compressed body O must be 0.1 or more, and the thickness of the compressed body through which the air passes must be 50 mm or more. If these conditions are not met, the combustion heat of the 7 enol resin will be exhausted together with the air passing through. When heated, it is impossible to crystallize the 7 eyelids, similarly when the impregnated amount of 1 phenol resin is 1
In the case of 0-, the bulk specific gravity of the compressed body must be 0.1 or more, and the thickness of the compressed body through which air passes must be 30- or more.

In the present invention, the reason for setting the air temperature in the range of 200 to 900°C is because if the temperature of the air is not dropped at 200°C, the organic binder cannot be burned and the ceramic fibers will not crystallize. This is because energy consumption increases.

Examples of the chromium salt in the second invention of the present application include chromium acetate and chromium carbonate.

As a means for converting such chromium salt into chromium oxide, a method of drying and heating after impregnation, or a method of converting into chromium oxide in a furnace or the like during use can be adopted. Chromium oxide converted from these chromium salts can prevent sintering that occurs at the contact points between fibers, which is another cause of shrinkage in ceramic, 7-eye and f- molded bodies. It can significantly reduce the rate. Also, Ryuran,
It is necessary that the chromium oxide content in the fiber molded body is in the range of 1 to B-. This is because if less than 1 inch drops, there is little effect in preventing sintering between fibers during use, and if it exceeds 8 seconds, chromium oxide tends to separate from the ceramic fiber molded body, which is inconvenient in use.

According to the present invention, by impregnating tough eyewear with a small amount of organic binder and heat-treating it at a low temperature (lower than the crystallization temperature) to burn out the organic binder, ceramic fiber, which is a heat insulating material, can be used. Since it can be crystallized in the air, energy consumption is small and #! Difficulties in handling may occur due to a decrease in the strength of the fibers.9.Since crystallization begins from the center of the bulk ceramic or Tough Eyeper compressed body, the range of crystallization can be controlled by changing the temperature or passing time of the air passing through it. It is also possible to prevent crystallization near the outer periphery of the molded object by controlling the outer periphery of the molded object. Such a molded object that is not crystallized near the outer periphery is easy to handle because flexibility is maintained near the outer periphery, and the furnace wall When carrying out construction, the molded bodies are brought into close contact sufficiently to prevent joint opening, and furthermore, the molded bodies obtained can be cut into any shape and used for various purposes.

The present invention will be explained in detail below.

Example 1 A bulk fiber was impregnated with 78nol resin and compressed to produce a bulk fiber. The bulk specific gravity of the compressed body was 0.1, and the thickness of the compressed body through which air passed was 50 cm. Continuing,
This bulk ceramic and Tough Eye Bar were filled into a mold, and high-temperature air at 200° C. and 2 atm was passed between the fibers. At this time, the phenol resin hardens as air passes through it for several minutes to obtain a block-shaped molded product, and as air continues to pass through it, it hardens and becomes skin-like.

Example 2 Norresin was combusted to a temperature of about 1000°C, and a partially crystallized CEL fiber molded body was obtained. Impregnated with chromium aqueous solution. Thereafter, the mixture was dried and heated to convert it into chromium acetate t-chromium oxide, thereby obtaining a ceramic and tough eye bar molded body having a chromium oxide content of 4-.

The ceramic/tough eye bar molded body used first in Example 2 has a partially crystallized surface, so the surface is not smooth and can be sufficiently impregnated with the chromium acetate aqueous solution.
Chromium oxide converted from tarom acetate after heating produces ceramic,
Evenly distributed on the surface of the tough eye bar.

The ceramic fiber molded bodies obtained in Examples 1 and 2 were kept at various temperatures for 24 hours, and their linear shrinkage rates were measured and are shown in the table below. For comparison, the table below also shows the linear shrinkage percentages of molded products made using conventional methods under the same conditions.

Table Unit - As is clear from the above table, the partially crystallized ceramic fiber molded body obtained in Example 1 had a 4M shrinkage rate lower than that of the nine ceramic fiber molded body obtained by the conventional method. The linear shrinkage rate of the ceramic/tough eye bar molded article containing oxide obtained in Example 2 was 4 times lower than that of the ceramic/tough eye bar molded article of Example 1.

As detailed above, according to the present invention, ceramics and tough eye bars can reduce the shrinkage rate through simple heat treatment, and can prevent delamination, joint opening, and cracking on the furnace wall when used in a furnace. It is possible to provide a method for producing a molded article and a method for producing a ceramic or tough eye bar molded article whose shrinkage rate can be further reduced by incorporating chromium oxide.

Claims (2)

[Claims] (1) High-temperature air at 200 to 900°C is applied to bulk fibers impregnated with an organic binder and compressed.
- A method for producing a ceramic fiber molded article, which comprises bringing the organic binder into contact with the material to burn it, and crystallizing part or all of the bulk ceramic or tough eye bar. (2) Bulk ceramic or tough fiber impregnated with an organic binder and compressed is brought into contact with high-temperature air at a temperature of 200 to 900°C to burn the organic binder, and a portion of the bulk ceramic fiber is also burned. Cef? is characterized by crystallizing the entire product and further impregnating it with an aqueous chromium salt solution.
A method for producing a molded article.