JP2652006B2 - Ceramic molded product and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a ceramic molded product used for architectural stones and various mechanical members.

[0002]

2. Description of the Related Art Recently, crystallized glass in which crystals are precipitated in a glass body has been widely used as architectural stones and various mechanical materials. Crystallized glass has been widely used in that it has superior mechanical strength and chemical corrosion resistance as compared with natural stone materials, and can be used for mass production of homogeneous products.

[0003] The material of conventional crystallized glass building materials can be divided into β-wallastonite [β-CaO · SiO
_2], Fuorusu Te light [2MgO · _SiO 2], enstatite [MgO · _SiO 2], diopside [C
aO.MgO.2SiO ₂ ] and phlogopite [KMg
₃ (AlSi ₃ O ₁₀ ) F ₂ ] and the like are known.

[0004] The production method of these crystallized glasses is roughly classified into a roll-out method and an integration method. The roll-out method is a method in which a glass obtained by melting a raw material mixture at a temperature of 1350 ° C. or more is formed by a roll-out method, and then heat-treated at a predetermined temperature condition to precipitate crystals and gradually cooled to obtain a product. In the integration method, a glass obtained by melting a raw material mixture at a temperature of 1350 ° C. or more is cooled and pulverized with water or a water-cooled roll under supercooling conditions in which precipitation of crystals is suppressed, to obtain a powder. After accumulating in the refractory mold of the required shape, heating in a heating furnace, fusing and integrating the glass powder, further heat treating under predetermined temperature conditions to precipitate crystals, gradually cooling, and further polishing How to get a product.

[0005]

Although such conventional crystallized glass building materials have technical properties and characteristics to be evaluated, they require specific equipment and advanced technology. That is, the melting step of the raw material mixture at a high temperature as described above,
It requires a glass crushing step by supercooling and a complicated crystallization step, and cannot be performed by general ceramic technology, for example, means for producing ceramics and refractories.

[0006] Further, in terms of product characteristics, there is a demand for a material capable of withstanding acid rain. In this regard, conventional forsterite or fluorine mica having a single crystal phase inevitably has an alkali content due to its composition. Therefore, it has poor acid resistance and is susceptible to changes over time due to acid rain.

In order to solve the above-mentioned problems of the conventional crystallized glass, the present invention is to remarkably improve the method for producing the crystallized glass and to provide a ceramic molded article having chemical corrosion resistance and a method for producing the same. is there.

[0008]

The present inventors have conducted a study on ceramics having a coexisting crystal phase of diopside and forsterite, which had been impossible in the past, and a study for enabling the production thereof. Thus, the present invention has been achieved.

[0009] The component composition of the ceramic molded article of the first invention of the present invention (referred to the invention of claim 1) is SiO _{2 by} weight.
_{30~75%, Al 2 O 3 3~20} %, MgO 5~
35%, CaO 2-15%, K ₂ O and / or BaO
3 to 15%, Na ₂ O _{2 to} 12%, F 0 to less than 2%. The structure formed by this composition is MgO-S
Ceramics mainly composed of diopside crystal and forsterite crystal having iO ₂ as a common essential component, and the remainder is occupied by a chemically stable glass phase in which alkali and acid components are neutralized. is there. This main crystal phase is Ca
_{O, K 2 O, Na 2} O, diopside [CaO · MgO · a requirement SiO 2, MgO in the amount and the combination
2 SiO ₂ ] crystal and forsterite [2MgOS
The amount of deposited [iO ₂ ] crystal and the ratio of the amount of deposited crystal are determined.

Most of these main crystals are almost uniformly precipitated in a microcrystalline glass matrix having a diameter of 10 μm or less, and 5 to 55% by weight of a ceramic molded product is precipitated and formed.
The ratio of diopside crystal / forsterite crystal is about 10/90 to 70/30, preferably 20/80 to 60/40, depending on the mixing ratio of the raw material components. This ceramic molded product is formed by sintering, using a crystal component of fine particles, glass, clay, etc. as a molding raw material by a manufacturing method described below, and sintering. The crystal precipitation state is not oriented, and the molded product is homogeneous, A polycrystalline structure without striae is formed.
With such a composition and structure, the ceramic molded product is a chemically neutralized stable structure, has acid resistance, and exhibits a bending strength of 450 to 700 kg / cm ² .

The second invention (referred to as the second invention) of the present invention is that 30 to 75% by weight of SiO ₂ and Al ₂ O ₃ 3
-20%, MgO 5-35%, CaO 2-15%,
K ₂ O and / or BaO 3 to 15%, Na ₂ O 2 to 2
After fine powder of a raw material mixture having a composition of 12% and F of less than 0 to 2% is directly molded or heat-treated to obtain a calcined body, the calcined body is reground. A method for producing a ceramic molded product, which comprises molding the fine powder thus obtained and then sintering it by heating to precipitate a symbiotic crystal of diopside crystal and forsterite crystal, and a third invention of the present invention ( The invention according to claim 3) is based on Si by weight.
_{O 2 30~75%, Al 2 O} 3 3~20%, MgO
5 to 35%, CaO 2 to 15%, K ₂ O and / or BaO 3 to 15%, Na ₂ O 2 to 12%, F 0
Fine powder of glass and / or clay is added to the fine powder of the raw material blend having a composition of less than about 2%, or the fine powder of the raw material blend is heat-treated into a calcined body and then re-ground. This is a method for producing a ceramic molded product, which comprises blending and molding, and then heating and sintering to precipitate a symbiotic crystal of diopside crystal and forsterite crystal.

The raw materials forming the ceramics of the present invention include industrial materials such as silica, alumina, magnesia, carbonates thereof, potassium fluorosilicate, sodium fluorosilicate and ceramic minerals such as talc, pyrophyllite, natural mica, Feldspar, nepheline, kaolin, fluorite, perovskite, glass and the like are blended and used so as to correspond to the composition of the ceramic glass of the present invention.

According to a second aspect of the present invention, the above-mentioned raw material mixture is pulverized to an average particle diameter of 10 μm or less and molded as it is, or this fine powder compound is heat-treated to form a calcined body and then re-pulverized. Mold the powder. In this case, the heat treatment is performed by charging the fine powder of the raw material mixture into a refractory container, heating the mixture in a heating furnace at 600 to 1100 ° C. for 1 to 5 hours, and volatilizing crystallization water and carbonic acid in the mixture. Activation and agglomeration of the fine powder are performed, and a solid phase reaction is advanced to form a calcined body in which initial fine crystals of a main crystal described later are formed. As a mode of molding, in the case of press molding of a relatively small-sized molded product, it is molded using water or an organic binder generally used such as CMC, polyvinyl alcohol, acrylic, or the like, and a molded product having a long dimension is used. In the case of press molding or extrusion molding for obtaining, the slurry is formed by adding the above-mentioned organic binder, which is a usual method of the ceramic industry, and then formed as a secondary granule by a dry spray method.

The molded article molded by the above molding step is then moved to a crystallization step of firing and sintering. In this crystallization step, the molded product is sufficiently dried at a temperature of room temperature to 200 ° C., then housed in a refractory container, charged into a heating furnace and fired. Heating is performed at a predetermined temperature (900 to 1200) from room temperature.
℃) at a heating rate of 150 to 200 ℃ / hr,
Then, the sintering and the crystallization are simultaneously completed by holding at a predetermined temperature for 1 to 5 hours. In the sintering process, the bonding between the particles of the molded product proceeds from around 600 ° C., and the solid phase sintering (solid phase reaction) is performed sequentially.
And initial crystals are precipitated and grown at 900 ° C. or higher.

In this way, a ceramic having a composition of a single crystal component is obtained. This composition is a ceramic composition in which the composition of diopside and forsterite is combined, that is, a crystal component composition, which is a basic substance of the present invention.

In addition to the above-mentioned ceramic having a simple composition of the crystal component, glass and / or clay can be added to the crystal component or the heat-treated (calcined) crystal component to produce a ceramic. In this case, glass contributes to cost reduction of raw materials and improvement of sinterability, and clay contributes to improvement of moldability. The composition of the raw material mixture of the third invention is intended to lower the sintering temperature, diffuse components, neutralize alkali components, and the like by adding glass, and general glass and bottle glass are used as glass materials. Fluoride-based opalescent glass or the like can be used, and if the properties of the product are not hindered, it can be added at around 50% by weight, which can contribute to glass recycling.

In the third invention, clay (SiO ₂ —Al ₂ O ₃ ) is added to the crystal component as a plasticizer. This is because in the case where the product ceramics are formed in a long dimension by press molding or in the case of extruding a long dimension rod, tube, hollow, etc. Since the fluidity is small and the molding pressure transmission is poor, the moldability is improved by adding clay to thicken the calcined raw material mixture, and the clay is added within 25% by weight. Then, water is added and kneaded to prepare a defoamed viscous kneaded product, which is molded. Molding is performed under pressure of 200 to 500 kg / cm ² in the case of press molding, and 15 to 50 kg / cm ² in the case of extrusion molding.

In the present invention, when a small-sized thin plate (having a thickness of about 10 mm or less) in which the amount of a crystal component is blended in the composition of the product ceramic of 70% or more and the molding is performed uniformly and densely is required. In addition, a heat treatment for converting the crystal component into a calcined body can be omitted.

In the third invention, the compounding ratio of each component of the raw material mixture to be molded prior to the heating and baking is 40 to 95% by weight of the crystal component, glass (a) 0 to 60, and clay (b).
0 to 25, (a) + (b) 5 to 60, and coloring pigments and crystal nuclei 0 to 5 with respect to the raw material mixture.

The molding operation according to the third aspect of the invention is applicable to the molding operation according to the second aspect of the invention, and the sintering and crystallization treatment can be performed under the conditions described in the second aspect of the invention.

The amount of crystal precipitation in the ceramic molded articles of the second and third inventions according to the present invention is 30 to 80% of the blended crystal component depending on the amount of crystal component, crystal composition, firing temperature and holding time. , In ceramics 5-
At 55%, the ratio of diopside / forsterite crystals is about 10/90 to 7 depending on the blending ratio of the raw material blend.
0/30, preferably 20/80 to 60/40.
In addition, a by-product crystal of 1/5 or less of the total crystal amount, that is, a crystal other than a coexisting crystal of a diopside crystal and a forsterite crystal, for example, a small amount of clienoenstatite, richterite, fluorine mica, etc. None of the crystals has any effect on the properties of the ceramics of the present invention.

The ceramics according to the present invention in which the coexisting crystals of diopside crystals and forsterite crystals are precipitated are systematically suppressed in the amount of alkali components and are neutralized. The glass matrix that bonds between them is neutral and chemically stable, compared to conventional mica powder sintered products, alkali compositions such as mica or forsterite crystallized glass by the melting method or the accumulation method. Ceramics with excellent acid resistance.

In the above ceramic composition, SiO ₂ ,
MgO is a common essential component of diopside and forsterite, and in order to secure the crystal precipitation of both, SiOO
₂ requires at least 30% (wt%, the same applies hereinafter). If it is more than 75%, the sinterability is deteriorated. If it is less than 5%, the precipitation of two crystals is sharply reduced, and If the amount is too large, the alkali content becomes excessive, and the sinterability deteriorates. The preferred amount of MgO is 8-32%. CaO is an essential component of only diopside, and the generation ratio of both diopside and foresterite crystals is determined by controlling the precipitation of diopside by varying CaO. Precipitation of the side is recognized, and thereafter the amount of precipitation gradually increases up to 15%. However, if it exceeds 15%, the alkali content becomes excessive and the chemical corrosion resistance is deteriorated. The preferred amount of CaO is 3 to 12%.

Al ₂ O ₃ is Ca in the range of ₃ to 20%.
It is blended in order to neutralize excess alkali components such as O and MgO in relation to SiO ₂ . If it is less than 3%, it does not contribute to neutralization, and if it is more than 20%, the sintering temperature is increased. Na
₂ O is in the range of 2 to 12%, and K ₂ O and / or BaO is in the range of 3 to 15%, which is a common solvent component for promoting the solid solubility of each component and lowering the sintering temperature. is there. F lowers the melting point of the composition and is used as an accelerator for sintering. However, when the amount of F increases, fluorine mica is formed as a by-product. . By doing so, the deposition of fluorine mica is significantly reduced or eliminated. Crystal nuclei, for example, TiO ₂ , Zr, in the range of 5% or less based on the above ceramic composition
O ₂ and pigments, for example, no problem Fe, Ni, Mn, Ti, even with the addition of metal oxides such as Co.

The structure of the ceramics of the present invention may be obtained by sintering and crystallizing by heating and sintering a molded product of the raw material mixture, or by sintering by heating and sintering the raw material mixture prior to the sintering. It is formed by performing sintering and crystallization by a solid phase reaction in combination with the calcination treatment. The requirements for promoting the solid phase reaction in this case are (1) a good reactive composition, (2) a high crystal component content, and (3) fine particles of the fine powder raw material composition having a high degree of filling. To a high degree, the fine powder raw material formulations according to the invention fulfill all of these requirements. Then, sintering and crystallization are promoted by the action of lowering the melting point of the fluoride during sintering, the action of crystal formation by the component exchange performed by evaporation and condensation, and the like. This is different from the conventional method for producing crystallized glass by a melting method.

The baked product is cut into a predetermined size and polished according to a desired external appearance, or is made into an unpolished product. The product is comparable to conventional crystallized glass and tile, has physical properties of water absorption of 0 to 0.5%, flexural strength of 500 kg / cm ² or more at a crystal precipitation of 20%, and a crystal precipitation of 40%. It reaches 700 kg / cm ² at ５０50%. Chemical properties are excellent in acid resistance and alkali resistance. In addition, the appearance of the product ceramics has various appearances depending on the crystal precipitation state and the colorant.

Hereinafter, the present invention will be described with reference to examples.

Example 1 This example describes the preparation of a crystal component and an example of the production of ceramics using only the crystal component. Table 1 shows the composition, processing conditions and physical properties of the crystal components. According to the composition shown in Table 1, the raw material (K ₂ O
As potassium carbonate, MgO as magnesite, N
sodium carbonate as a ₂ O, silica stone as SiO ₂ , A
Alumina as l ₂ O ₃ and fluorite CaF ₂ ) as CaO and F were mixed and pulverized in a dry ball mill to give an average particle size of 10
μm powder. Of the obtained powder, sample No. 3 and No. 3 Sample No. 4 is the same as Sample No. 1 and No. 1 No. 2 puts the fine powder of the raw material mixture into an alumina crucible, heat-treats it at 900 ° C. for 3 hours in an electric furnace, and then re-pulverizes it to an average particle size of 5 μm. Raw materials. Sample No. 1
And No. 2 As a result of X-ray diffraction of each raw material for production, initial crystals of diopside-forsterite were found.

[0029]

[Table 1]

The overheat-treated sample No. 1 and No. 2 and the non-superheat-treated sample No. 2 3 and No. 4 each crystal component 1
With respect to 00 parts by weight, 0.5 parts by weight of CMC and 8 parts by weight of water were added and kneaded to obtain a raw material for molding. Press molding at 300 kg / cm ² by press molding, 95 × 95 × 8 (m
m) was obtained. Further, the molded body is heated at 110 ° C. for 1 hour.
After drying for 2 hours, 180-200 ° C / Hr in an electric furnace
The temperature was raised to the sintering temperature shown in Table 1 at the speed described above, and the temperature was maintained for a predetermined time, followed by cooling to obtain a product. As shown in Table 1, the obtained product had a structure having a diopside-forsterite symbiotic crystal phase, and had a bending strength of about 655 to 67.
At 0 kg / cm ² , all the samples show the same acid resistance and alkali resistance as those of conventional commercially available stone materials, for example, β-wallastonite building material, which is a typical crystallized glass obtained by a melting method or an accumulation method.

Example 2 This example relates to the mixing of the raw materials, that is, the sample No. obtained in Example 1. 1 to No. Each crystal component and glass powder and / or
Or, a molding example in which two-component and three-component systems of clay are prepared, and furthermore, press molding and extrusion molding are performed by using them.
Material No. up to molding. 1 to No. The process 4 is the same as that of the first embodiment.

Table 2 shows the raw material composition, and Table 3 shows the characteristics of the product ceramic. Material No. 1 to No. The crystal components of 4 are the same as those of Table 1. The glass powder is a general-purpose float glass [composition (% by weight): SiO ₂ 73.1, A
l ₂ O ₃ 1.7, CaO 10.3, MgO 0.2,
K ₂ O 1.3, Na ₂ O 13.4], and the clay is kaolin-based clay [composition (% by weight): SiO ₂ 52, Al
₂ O ₃ 34, lg. Loss14], and these components were mixed and pulverized to obtain a powder having an average particle size of 5 μm.

[0033]

[Table 2]

[0034]

[Table 3]

In the press molding, 1 part by weight of an organic binder (PVA) and 100 parts by weight of water were added to 100 parts by weight of the raw material compound (sample No. 1, No. 3, No. 4) according to Table 2, and wet After mixing into a slurry, the mixture is dried with a spray drier and granulated. The granules are molded with a press molding machine at a pressure of 300 to 500 kg / cm ² ,
A flat molded body of 00 × 600 × 12 mm,
After drying at 2 ° C. for 2 hours, it was charged into an electric furnace,
Each sample was heated and baked at a heating rate of 2 ° C./Hr according to the predetermined calcination temperature and holding time shown in Table 2 for each sample, and then cooled (200 to 25
(0 ° C / Hr) to obtain a product.

In the extrusion molding, 20 to 25 parts by weight of water and 1 part by weight of an organic binder (CMC) are added to 100 parts by weight of the raw material composition (sample No. 2) shown in Table 2, and the extruding pressure is set to 20 by a kneader. ~35kg / cm ^2, subjected to extrusion molding at an extrusion rate 200~300mm / min,
A pipe-shaped molded body having an outer diameter of 100 mm, a wall thickness of 8 mm, and a length of 310 mm was cut out and cut into 310 × 310 ×
An 8 mm flat molded body was formed, and the thickness was adjusted and flattened with a rolling roller to finally obtain a 320 x 320 x 6 mm flat molded body.

This is heated at 80 to 120 ° C. by a hot air drier.
After drying for 5-7 hours, put it in an electric furnace,
Each sample was heated to a predetermined firing temperature shown in Table 2 at a heating rate of 00 ° C./Hr, kept at this temperature for a predetermined time, overheated, cooled (200 to 250 ° C./Hr), and cooled to a product (about 300 × 30
0 × 5 mm, 78% shrinkage).

Table 3 shows the characteristics of the products obtained by the above-mentioned molding methods.

[0039]

The present invention does not depend on the specific equipment and technology for the production of the conventional crystallized glass, but has the same physical and chemical properties as the crystallized glass by the ordinary ceramic technology, The fluorinated mica-based or forsterite-based crystallized glass has a large amount of alkali components, and can obtain a ceramic in which diopside crystals and forsterite crystals are co-precipitated, which can improve the defect of poor acid resistance. An energy-saving manufacturing method can be achieved by manufacturing long-sized products, firing at low temperatures, and using low-cost raw materials.

Claims (3)

(57) [Claims] 1. A _SiO 2. 30 to by weight as essential components
_{75%, Al 2 O 3 3~20} %, 5~35% MgO,
CaO 2~15%, _{K 2} O and or BaO 3 to 15
%, Na ₂ O 2 to 12%, F 0 to less than 2%, and a ceramic molded product in which a symbiotic crystal of diopside crystal and forsterite crystal is precipitated. _2. 30% to 75% by weight of SiO ₂ , Al _{2
O 3 3~20%, 5~35% MgO} , CaO 2
１５15%, K ₂ O and / or BaO 3-15%,
Na ₂ O 2 to 12%, the after fine powder directly or molding, or further heat treated to calcined body a fine powder of a raw material blend of the raw material blend of the composition of F less than 0-2% A method for producing a molded ceramic article, comprising: forming a fine powder obtained by re-grinding a calcined body, followed by heat sintering to precipitate a symbiotic crystal of a diopside crystal and a forslite crystal. 3. 30% to 75% by weight of SiO ₂ , A1 ₂ O
_{3 3~20%, 5~35% MgO,} CaO 2~1
_{5%, K} 2 O and / or BaO 3~15%, Na ₂
Fine powder of a raw material blend having a composition of O 2 to 12% and F of less than 0 to 2%, or a fine powder of the raw material blend, which is heat-treated to form a calcined body and then reground to a fine powder, A method for producing a ceramic molded product, which comprises molding a mixture containing fine powder of clay and / or clay, followed by heat sintering to precipitate a symbiotic crystal of diopside crystal and forsterite crystal.