JPH0547511B2 - - Google Patents

Description

[Detailed description of the invention]

The development of fiberization of inorganic heat-resistant materials, which began with the fiberization of inorganic glass, has progressed significantly, and
Aluminum silicate fibers that can withstand the above high humidity have also started to appear on the general market, and are attracting attention as heat-insulating and fire-resistant materials for high temperatures. Accordingly, there are great expectations for the emergence of heat-insulating, refractory ceramics with arbitrary shapes and porosity that use ceramic fiber as a skeleton material. The present invention satisfies this need, and its features include the ability to select any shape and size, and the porosity within a fairly wide range. Currently, Ceramic fiber is available in bulk,
It is available in the form of blankets, felt, paper, etc., and you can choose one that is suitable for the item you are trying to make. First, the first step of the manufacturing method shown in claim 1 will be described. As shown in claim 1, a mixture of fine alumina cement powder in a weight ratio of 50 to 100 of methyl alcohol was placed in a ball mill and milled for several hours. A uniform dispersion is prepared by processing. The concentration of alumina cement in this dispersion was approximately 33% by weight. This dispersion is impregnated into a blanket or felt to form a mixture of ceramic fibers and alumina cement, but before we do that, we would like to add some explanation about the blanket. In general ceramic fiber blankets, the true specific gravity of the fibers that make up the blanket is about 2.7 (particularly high alumina ones are about 3.3), the diameter is about 2 to 3 μm, and the bulk specific gravity of the blanket is Since it is 0.1 to 0.13, 1 kg of blanket is approximately
It has an apparent volume of 7.5 to 10. Therefore, a blanket with length and width of 600 mm and thickness of 25 mm has a volume of about 9, and if its bulk specific gravity is 0.11, its weight is about 1 kg. The mixing ratio of fiber material and alumina cement can be used in a wide range, but in this case, if the ratio is 100 parts fiber material to 40 parts alumina cement, the above 1 kg blanket can be mixed. On the other hand, since alumina cement weighs 0.4 kg, approximately 1.2 kg of 33% dispersion is required. To ensure smooth impregnation, 0.4 kg of methyl alcohol may be added to 1.2 kg of the dispersion and mixed to form an impregnating liquid. Sprinkle 1/2 of this impregnating liquid onto one side of the blanket spread out on a flat plate as evenly as possible using a mist-like device to impregnate it, then turn the blanket over and pour the remaining The impregnating liquid is impregnated in a similar manner, and roller treatment is further performed to ensure uniform impregnation. After the impregnation process is completed, the material is dried in a sealed drying room at around 70°C, and if necessary, methyl alcohol is recovered. The above description is based on a blanket with a thickness of 25 mm, but the same applies to blankets of different thicknesses, as well as felt or bulk materials.
A dry mixture with cement is obtained. The material in this state will be referred to as a dry molding material. What has been described above is the first step of the manufacturing method. Dry molded materials are stored in moisture-resistant containers or bags to prevent them from absorbing moisture. Take out the dry molded material from the storage container, cut it into the required size, uniformly absorb water equivalent to about 60% of its weight using a mist-like device, and then cut it into the required size. For example, by applying roller treatment,
It is a water-containing molding material. In the description below,
The water-containing molding material will be simply referred to as a molding material. Thickness of the blanket prepared as above
We will describe the molding procedure when using a dry molding material with a diameter of 12.5 mm and an alumina/cement content of 33%. First, a dry molding material is cut to fit the mold and is soaked in water to make up about 60% of its weight to form a molding material. Three sheets of the above-mentioned molding material are placed in a flat mold, compressed to a thickness of 10 mm using a lid template, the mold is set, and heated at 70°C to 90°C.
By immersing it in hot water for about 20 minutes, it will harden to a sufficient strength to withstand mold release operations. This is removed from the mold, dried in a dryer at around 90°C for several hours, and then fired in a furnace. Firing temperature conditions vary depending on the ceramic fiber and alumina cement used. In this example, the safe use temperature is 1300
Ceramic fiber with Al ₂ O ₃ content of 70 °C
% or more alumina cement was used, so 1300
It was fired under the firing conditions of holding at °C for 1 hour. The dimensions of fired products hardly change during molding, that is, the shrinkage during firing is close to zero, and the bulk specific gravity is
0.65, and the porosity was 75%. This example was designated as No. 1, and as No. 2, it was carried out under the same conditions and methods as in No. 1, except that the thickness of compression molding in No. 1 was changed from 10 mm to 15 mm. The cases are as follows. In the case of No. 2 fired product, the firing shrinkage was close to zero, but its bulk specific gravity was 0.42 and the water absorption rate was 84%. From these two examples, it can be understood that the product of the present invention has a small shrinkage during firing, that is, a low firing shrinkage rate, so it can provide an insulating refractory with accurate dimensions and accurate porosity. I think so. The above is an example of a flat plate type, but both a box type and a cylindrical type can be manufactured using the same method, and the method will be described below. For a box shape, cut the molding material into a square shape, compression mold it with a corresponding mold so that the top, bottom, left and right protrusions correspond to the depth of the box, and after the curing process, it is made into a flat plate shape. You can do it in the same way as when you did it. In the case of a cylindrical shape, wrap the cut-out molding material to the required thickness around a core mold with an outer diameter corresponding to the inner diameter of the cylinder, and hold it with a 2-split or 3-split outer mold made of a thin iron plate. Then, compression molding is performed to the specified dimensions using a ring-shaped mold with both ends attached in advance.
All you have to do is compression mold it to a predetermined size and proceed with the curing process and subsequent steps in the same way as for the flat plate shape. The cases of flat, box, and cylindrical shapes have been explained above, so next we will discuss the case of complex structures. In this case, a bulk ceramic fiber is used as the framework material, and an atomized dispersion of alumina cement is used in the same manner as in the case of the blanket, but the bulk is bulkier than the blanket. Therefore, the concentration of the impregnating solution is lowered. An example will be shown below. For 1 kg of bulk, add 1.2 kg of alumina cement dispersion with a concentration of 33% and 0.8 kg of methyl alcohol.
The impregnating liquid is obtained by adding This impregnation liquid is sprinkled onto the bulk spread out on a flat plate using a device that releases it in the form of a mist.
Bulk is constantly turned inside out over and over again. After the impregnation process, the material is dried in the same manner as for blankets to form a bulk dry material. A dry molding material impregnated with 40% to 50% water is used as a molding material. The required amount of this molding material is filled into the required places in the mold, the upper mold is inserted, and compression molding is performed. The mold is set, and the curing process and subsequent steps are completed in the same manner as described above. This concludes the explanation of the manufacturing procedure, and next we will discuss materials. Ceramic fiber and alumina cement are the main materials, and the oxide and silicon salt powder materials shown in claim 2 are subsidiary materials. The main materials, ceramic fiber and alumina cement, each have heat resistance depending on their composition, so they must be used in a rational combination. Table 1 shows the combinations based on heat resistance.

[Table] Auxiliary materials help the hardening reaction of alumina cement to make a stronger hardened product, and also react with alumina cement during high-temperature heat treatment to create more stable ceramics.
For example, silicates (zircon, mullite, siyamoto) and silicon oxide react with CaO, a component of alumina cement, to stabilize it, and alumina and magnesia have the effect of improving the heat resistance of this ceramic. There is. From the above, it can be understood that the present invention is novel and exhibits desirable effects both industrially and in general society.

Claims (1)

[Scope of Claims] 1. When an inorganic fiber material called ceramic fiber is used as a skeleton material and alumina cement is mixed therein to serve as a molding material and a binding material, the mixing method is to use alumina cement. A ceramic fiber blanket, felt, woven fabric, bulk material, etc. is impregnated with the fine powder dispersed at the required concentration in a volatile organic solvent that does not harden it, and if necessary, The first step in the manufacturing method is to heat and dry the material to release an organic solvent to form a homogeneous dry material consisting of ceramic fiber and fine powder of alumina cement. The dry material obtained in the first step is made into the required size and shape, impregnated with the required amount of water, and used as a molding material, taking into account the porosity of the product to be obtained. A fixed amount of molding material, a fixed volume,
A method for producing heat-insulating and fire-resistant ceramics, which is characterized by compression molding, curing and releasing from the mold in that state, and subjecting the resulting molded product to heat treatment to produce a product. 2. A ceramic fiber mixed with powder of one or more of alumina, magnesia, zircon, mullite, siyamoto, and silicon oxide is used as a skeleton material, and alumina cement is mixed with it, and the method shown in paragraph 1 is carried out. A method for producing heat-insulating, fire-resistant ceramics.