JPH0796470B2 - Method for manufacturing ceramic sinter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a siding tile that is used by being attached to a wall surface of a building such as a building with nails or screws, or by being attached with an adhesive, in particular, The present invention relates to a method for producing a relatively large siding tile, or a ceramic sinter that is suitable as a building material, a structural material, a heat-resistant material, or the like.

<Prior Art> Ceramic sinters are generally produced by using feldspar, porcelain stone and silica stone as main raw materials, adding clay to this to form an arbitrary shape, drying and firing. . However, according to such a method, there is a problem that the dimensional accuracy of the sintered body is significantly reduced due to shrinkage of clay in the drying step and the firing step after molding. Further, since the shrinkage of clay brings a large latent strain to the molded body and the sintered body, not only cracks and deformations easily occur in the molded body and the sintered body, but also their machinability and sintered body There is also a problem that the strength of the is reduced. In order to obtain a high-strength sintered body, it is sufficient to perform firing at a high temperature for a long time to perform high-density sintering. However, this not only increases the manufacturing cost but also increases shrinkage during sintering. As a result, the dimensional accuracy is further reduced.

On the other hand, JP-A-62-72551 and JP-A-63-182
Japanese Patent No. 272 proposes to incorporate a glassy metallurgical slag as a main raw material. If you use a metallurgical slag,
The expansion serves to offset the shrinkage of the clay during the firing process, thus alleviating the above-mentioned problems to some extent. However, it is still not sufficient.

<Problems to be Solved by the Invention> An object of the present invention is to solve the above-mentioned problems of the conventional method and produce a ceramic sinter excellent in various characteristics such as dimensional accuracy, machinability and strength. There is a way to provide.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a step of molding a mixture containing at least the following a and b, a step of drying a molded body, and a molded body after drying. And a step of firing in the range of 1250 ° C.

a. A high silica-zeolite blended with a metallurgical slag having a glass phase of at least 80% by weight in the range of 20 to 50% by weight: 50 to 90% by weight b. Clay molding a mixture containing a, b and c, and drying the molded body,
And a step of firing the dried molded body in the range of 1050-1250 ° C.

a. High silica zeolite mixed with metallurgical slag having a glass phase of at least 80% by weight in a range of 20 to 50% by weight: 50 to 90% by weight b. Wollastonite: 5 to 20% by weight c .Clay The high silica zeolite, metallurgical slag, wollastonite and clay used in the present invention are all in the form of particles. The fineness is 0.25 to 5 mm mesh or less in high silica zeolite, 0.03 to 1 mm mesh or less in metallurgical slag, and 0.05 in wollastonite.
.About.0.5 mm mesh or less, and for clay, 0.01 to 1 mm mesh or less.

High-silica zeolite is a porous material with a three-dimensional network structure formed by diagenetic alteration of pseudo-olivine. Then,
The high silica zeolite used in this invention is characterized by Al: Si in the range of 1: 3 to 1: 6, when impurities are excluded. As a typical example, almost (Na, K, C
a) Clinoptilolite, which is represented by ₄ (Si ₃₀ Al ₆ ) O ₇₂・ 24H ₂ O, and Mordenite, which is almost represented by (Na ₂ , K ₂ , Ca) Al ₂ Si ₁₀ O ₂₄・ 7H ₂ O .

Now, the main raw materials used in the present invention include high silica zeolite and metallurgical slag.

High silica zeolite forms the aggregate of the sintered body. Then,
As mentioned above, high-silica zeolites include clinoptilolite and mordenite, which are plate-like crystalline clay minerals and are soft and soft, but when fired they become hard with shrinkage at about 1000 ° C or higher. The sintering proceeds while the internal pores become smaller. A large amount of glass phase is generated at about 1200 ° C or higher, but internal pores remain even when in a molten state, resulting in a multi-layer glass state. Bound water has a unique property as a so-called ceramic raw material, in that it begins to be expelled from about 200 ° C and continues until around 700 ° C. Then, such a property of the high silica zeolite is utilized in each step until a sintered body is obtained.

That is, due to its softness, the high-silica-zeolite acts so as to absorb the internal stress generated by the shrinkage of the clay due to dehydration when the molded body is dried. In addition, water adhering to water, which is usually used in the molding process, is about 20
Although it evaporates up to 0 ° C, the crystal water is supplied from the high silica zeolite even if the temperature rises above 0 ° C, so that the dry and wet balance is maintained and the internal strain of the molded body is significantly reduced, It is possible to prevent cracking and deformation of the sintered body. When the firing temperature rises further, the internal pores become smaller, but they do not disappear as described above, but remain in the sintered body, which reduces the resistance to machining and reduces the machinability of the sintered body. Is improved.

On the other hand, metallurgical slag is produced during the smelting of metal,
In the present invention, it is obtained by quenching from a molten state,
Use one in which the glass phase is at least 80% by weight.
Such metallurgical slags include blast furnace slag, converter slag,
Cast slag etc.

These metallurgical slags with a glass phase of at least 80% by weight are crystallized with an exothermic reaction from around 700 ° C in the firing process, and the volume expands to offset the contraction of high silica zeolite and clay. It is possible to obtain a sintered body that acts, has few cracks and deformations, and has excellent dimensional accuracy. Glass phase 80
If it is less than wt%, the effect of the above-mentioned crystallization reaction cannot be sufficiently expected.

In addition, since the metallurgical slag is a high calcareous glass, it easily reacts with high silica zeolite and clay, and can form a strong bonded phase structure. Therefore, the strength of the sintered body is improved.

In other words, a state in which high-silica-zeolite is surrounded by finer metallurgical slag and finer clay is created. Then, as the sintering progresses in the firing process, the metallurgical slag reacts with the surface of the high silica zeolite at a relatively low temperature and SiO ₂ -Al.
₂ O ₃ -CaO-K ₂ O, Na ₂ O-based glass phase is generated, the surface structure of high silica zeolite is strengthened with the sintering of clay to form a strong binder phase, and the strength of the sintered body is improved. It will improve.

On the other hand, apatite is a plate-like natural crystalline mineral with a large aspect ratio represented by βCaO · SiO ₂ . Then, when this wollastonite is used, not only the structure of the binder phase is strengthened and the strength of the sintered body is improved, but also the shrinkage of the molded body in the drying and firing steps is suppressed, and the molded body and sintered body are suppressed. It will prevent the body from cracking or deforming. Further, resistance to machining is reduced, so that machinability is improved.

On the other hand, clay, as is well known, is mainly composed of kaolinite minerals, has high plasticity, and acts as a binder for maintaining a desired molded body shape. So
It is preferable to select and use one having a high bond strength when dried. In addition, clay is about 600
Releases water of crystallization from ° C and shows high reaction activity,
Effectively reacts with the metallurgical slag to form a strong engagement structure,
Improves the strength of the sintered body.

Now, the main raw material is high silica zeolite mixed with metallurgical slag in the range of 20 to 50% by weight. If the metallurgical slag content is less than 20% by weight, it is impossible to expect the above-described actions, in particular, improvement in strength and the like due to formation of a strong binder phase and improvement in dimensional accuracy due to suppression of shrinkage. Also, if it exceeds 50% by weight,
Since the metallurgical slag has poor formability and high fire resistance, the firing temperature must be raised, which is not practical.

The main raw material is contained in the mixture in the range of 50 to 90% by weight. If it is less than 50% by weight, the above-described action of the high-silica-zeolite itself and the action of the combination of the high-silica-zeolitic stone and the metallurgical slag cannot be expected. On the other hand, if it exceeds 90% by weight, the viscosity and, when wollastonite is used in combination, the wollastonite becomes too small, and the strength and machinability of the sintered body deteriorate.

On the other hand, when wollastonite is also used, it is contained in the mixture in an amount of 5 to 20% by weight. Below 5% by weight,
The above-mentioned action cannot be expected. On the other hand, if it exceeds 20% by weight, tongue ring (entanglement) occurs and the formability and sinterability deteriorate.

Now, the mixture is formed into a desired shape. This molding can be performed by a known molding method such as a dry press molding method, an extrusion molding method, and a casting molding method. However, in order to facilitate the molding, the water content is 5 to 5 in the dry press molding method.
It is preferable to add water in an amount of 15% by weight, 15-22% by weight in the extrusion molding method, and 20-30% by weight in the casting method.

The molded body obtained by molding is naturally or forcibly dried. When forcedly drying, although it depends on the amount of clay and the like, it is preferable to raise the temperature at a rate of about 10 ° C./min or less and dry at a temperature of about 500 ° C. or less.

The firing is performed in the range of 1050-1250 ° C. At temperatures below 1050 ° C, sintering does not proceed. Further, if the firing temperature is higher than 1250 ° C., warping or sagging due to softening occurs, or sintering progresses so as to cause remarkable shrinkage, so that dimensional accuracy, machining, etc. are significantly deteriorated. Further, when wollastonite is used in combination, it may undergo α-transformation, and may change from plate-like to granular and the strength of the sintered body may decrease. The heating rate varies depending on the thickness and shape of the molded product, but is 50 ° C
/ Min or less is preferable.

<Examples and Comparative Examples> Clinoptilolite with a fineness of 0.5 mm or less containing about 45% by weight of impurities mainly composed of quartz, and a blast furnace with a glass phase of 98% by weight and a fineness of 0.05 mm or less. A slag, an aspect ratio of about 20 and wollastonite with a fineness of 0.25 mm or less and Motoyama Kibushi clay with a fineness of 0.01 mm or less are blended as shown in the table, and the water content is about 9 After adding water to the weight%, use a hydraulic press machine to make the width 100 mm, length 2
A plate having a thickness of 00 mm and a thickness of 10 mm was formed and dried at 150 ° C. The pressure during molding was 150 kgf / cm ² .

Next, the molded body was subjected to drilling with a steel drill having a nominal diameter of 5 mm, and the occurrence of cracks and chipping around the hole was examined. The results are shown in the table.

On the other hand, using a roller hearth kiln for the above molded body
It was fired at 1100 ° C. for 1 hour to obtain a sintered body.

The machinability of the above sintered body was examined. Further, the shrinkage ratio in the length direction, the specific gravity, and the bending strength were examined.
The machinability was examined by drilling with the above-mentioned drill and cutting with a diamond round blade.
The results are shown in the table.

From the above table, it can be seen that the sintered body according to the present invention is superior to the sintered body not according to the present invention, that is, the sintered bodies of Nos. 1, 6, 7, 15, and 19 in the comprehensive evaluation. .

That is, the No. 1 sintered body has a large resistance to cutting, and has a large shrinkage ratio and a large specific gravity. The bending strength of the No. 6 sintered body is considerably low. Further, the No. 7 sintered body has poor machinability, and has a large shrinkage ratio and specific gravity. The machinability of the molded product is also poor. In addition, the sintered bodies of Nos. 15 and 19 have extremely low bending strength.

<Effects of the Invention> The present invention is applicable to at least 80 high silica zeolite.
The main raw material is 50 to 90 wt% and clay, or the above main raw material, 5 to 20 wt% wollastonite, and clay, which is prepared by mixing the metallurgical slag whose weight% is a glass phase in the range of 20 to 50 wt%. Since it includes a step of molding the mixture, a step of drying the molded body, and a step of firing the molded body after drying in the range of 1050 to 1250 ° C., as shown in Examples, dimensional accuracy and strength. In terms of comprehensive evaluation of machinability, specific gravity, etc., an excellent ceramic sinter can be obtained. Since cracks and deformation are less likely to occur and the dimensional accuracy is excellent, of course, the yield is also greatly improved. Moreover, since the specific gravity is low, a lightweight sintered body can be obtained.

Further, according to the present invention, it is possible to obtain a sintered body having excellent machinability such as drilling and cutting. This is because porous high-silica zeolite and wollastonite with plate crystals reduce the resistance to machining.

Further, according to the present invention, since the dimensional change in the firing step can be reduced, there is no problem even if processing according to the product shape is performed before the firing step.

Furthermore, according to the present invention, even a molded product having a large wall thickness of up to 40 mm or a molded product having a wall thickness that is several times different from each other can be molded into a flat plate with a thin wall thickness of about 10 mm. The same drying and firing conditions as in the case of the body can be adopted, and furthermore, a sintered body can be obtained which is hardly cracked or deformed by such drying and firing conditions. This is because the action of the high silica zeolite can suppress an increase in internal strain of the molded body during drying and firing.

Claims (2)

[Claims] 1. A method comprising molding a mixture containing at least the following a and b, drying the molded body, and firing the dried molded body in a temperature range of 1050 to 1250 ° C. A method for producing a ceramic sinter. Main raw material consisting of high silica-zeolite and metallurgical slag having a glass phase of at least 80% by weight in the range of 20 to 50% by weight: 50 to 90% by weight b. Clay 2. A step of molding a mixture containing at least the following a, b and c, a step of drying the molded body, and a step of firing the dried molded body in the range of 1050 to 1250 ° C. A method for producing a ceramic sinter, which is characterized. a. High silica zeolite mixed with metallurgical slag having a glass phase of at least 80% by weight in a range of 20 to 50% by weight: 50 to 90% by weight b. Wollastonite: 5 to 20% by weight c .clay