JPH0587466B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a process for producing efflorescence consisting essentially of vitrifiable material powder, hydraulic cement, magnesium silicate mineral, and activated silicate mineral and/or aluminum silicate mineral. Regarding new ceramic products and their manufacturing method. By the manufacturing method of the present invention,
The efflorescence phenomenon caused by the vitrifying components of the ceramic product is substantially prevented, and the strength tends to be improved mainly due to the side effect of the magnesium silicate mineral. In addition, the hydraulic cement component greatly improves the ease of molding and shape retention of the green material, as well as the shrinkage deformability during firing.

[Prior Art] Conventional ceramic products are manufactured by adding water to a clay-based material, shaping it, and firing it. Therefore, there were serious problems in the strength and shape retention of the green material, as well as shrinkage and deformation during firing, but these problems were considered to be unavoidable.

The present inventor first formed an aqueous kneaded material consisting of a flux component such as glass powder, hydraulic cement, and other aggregate powder, and after the cement component had substantially hydrated and hardened, the mixture was heated to about 900 to 1050°C. Invented a method for manufacturing ceramic products by firing (patent application 1986-
331776). As a result, the above-mentioned problems with ceramic products have been substantially solved. However, efflorescence caused by glass powder and the like poses a problem in the appearance of the product. Furthermore, it was also a desirable issue to further improve the strength of the product.

In addition, a method for manufacturing cement products in which a pre-hydrated hardened product consisting of hydraulic cement and aggregate is fired at 900°C or less and then rehydrated (Japanese Patent Application Laid-Open No. 41916/1983).
However, the bending strength of this cement product is approximately 130 kgf/cm2, and there are large differences in strength and composition.

[Means for Solving the Problems] The main object of the present invention is to provide a method for manufacturing a ceramic product and a ceramic product that substantially eliminates the above problems.

That is, according to the present invention, hydraulic cement, melt-vitrifying material powder, magnesium silicate mineral powder,
A mixture consisting essentially of activated silicate mineral powder and/or aluminum silicate mineral powder and water is molded; the molded product is preliminarily hydrated and hardened; then the molded product is fired to a maximum temperature of 1100° C. or higher. A method of manufacturing a ceramic product is provided that substantially prevents efflorescence, which is characterized by a process. The resulting product is substantially prevented (ie, small) from firing shrinkage deformation and has high strength (eg, bending strength of 200 kgf/cm2 or more).

In the above manufacturing method, the magnesium silicate mineral is preferably serpentine mineral powder, talcum powder, or a mixture thereof, so that the high-temperature reaction product of the magnesium silicate mineral and calcium oxide is present in the ceramic product. A ceramic product that is easily formed and has further improved strength (for example, a bending strength of 220 kgf/cm2 or more) is advantageously obtained.

[Detailed description of the invention] (1) Raw materials As the hydraulic cement, any of Portland cement, alumina cement, mixed Portland cement, etc. can be used. As for the optional aggregate, it is preferable to use a stable material that does not undergo rapid expansion or contraction during the firing process (for example, ceramic shamotsu), and river sand, sea sand, silica sand, andesite, basalt, hard sandstone, etc. can also be used. .

Vitrifying material powder (so-called flux component)
produces a flux such as a glassy melt during firing, and specific examples include various glass powders, commercially available frits, feldspar, shirasu, volcanic ash, and other vitrifying igneous rock powders. Usually glass powder or frit is used.

Examples of the magnesium silicate mineral powder include powders of talc, serpentine minerals, chlorite, and the like. Usually serpentine powder, talcum powder or mixtures thereof are advantageously employed.

Examples of active silicate mineral powder or aluminum silicate mineral powder include amorphous silica, finely powdered silica sand (coarse silica sand for aggregates has poor effect), pyrophyllite powder, and clay mineral powders such as kaolin. .
Typically, waxite, finely divided silica sand, amorphous silica or mixtures thereof are advantageously used.

(2) The table below shows the preferred weight range of raw materials. This is mixed with the amount of water necessary for shaping and hydration of the cement to form a green body.
These compounding amounts indicate preferred effective amounts of each raw material to achieve the effects of the present invention.

Amount of raw materials (parts by weight) Hydraulic cement (e.g. Portland cement)
100 parts Magnesium silicate mineral (e.g. serpentine) 50-200
parts (e.g. around 100 parts) Glass powder 50-200 parts (e.g. around 100 parts) Silicate minerals and/or aluminum silicate minerals (e.g. waxite) 5-150 parts (usually 10-100 parts) (e.g. around 50 parts) Other aggregates: 300 to 0 parts (for example, around 150 parts) In general, the total amount of other components is 600 parts or less with respect to 100 parts of cement.

(3) Forming the green base material The mixture obtained by adding water to the above base material and kneading it is shaped. When making a mixture, admixtures such as a binder, a water reducing agent, a plasticizer, a fluidizer, a dispersant, and the like can be appropriately selected and added as necessary. Note that it is also possible to mix heat-resistant reinforcing inorganic short fibers into the mixture, which improves the strength.

Molding methods include cast molding, press molding, vibration press molding, extrusion molding, which are used in the production of ordinary ceramics, and pressure dehydration molding, paper-making, and spraying methods, which are used in the production of cement products. Various molding methods such as roll molding can be employed. Generally, a method using pressure dehydration is preferred in terms of strength, and an extrusion method is preferred in terms of efficiency.

After shaping, the green body is cured in a humidified state or left to stand (for example, for several hours to several days) to preliminarily harden the cement components by hydration. Next, it is fired under the following firing conditions. Incidentally, a glazed ceramic product can be advantageously obtained by applying a glaze suitable for the firing conditions to the required surface of the hydration-hardened base and firing.

(4) Firing Between the cement-based hardened material dehydrated by firing
Then, the vitrified melt of the vitrifiable material substantially penetrates to form a fired ceramic body. During the firing process, the cementitious hardened material forms a skeleton of the substrate, substantially preventing shrinkage that was thought to be inevitable during sintering (for example, compared to the conventional sintered material shrinkage rate of about 10%). In the present invention, it is around 1%). In addition,
The cement component dehydrated by calcination substantially acts as aggregate without being rehydrated. That is, unlike the case of the prior art, the cement components are
Since it is fired at a high temperature and has virtually no rehydration ability, and is surrounded by glass components, it is not substantially rehydrated.

In the present invention, it has been found that in addition to the presence of the above-mentioned magnesium silicate mineral component, a maximum firing temperature of about 1100° C. or higher is necessary to prevent efflorescence caused by glassy components and the like.

Therefore, the firing in the present invention is carried out at a maximum firing temperature of about 1100°C or higher (generally about 1100 to 1250°C), and the maximum temperature holding time is about 20°C at 1100°C.
minutes or more, preferably about 30 minutes or more, and
At 1200°C, it is about 7 minutes or more, preferably about 10 minutes or more. Such firing conditions can be easily carried out, for example, in a roller hearth kiln or a tunnel kiln. By the way, the maximum firing temperature is 1000-1050
At temperatures around ℃, it is difficult to prevent efflorescence.

Specific Example 1: The following mixture (parts by weight) was used as a raw material.

Ordinary Portland cement 100 parts Serpentine (less than 150 mesh) 50 parts Glass powder (less than 100 mesh) 125 parts Rockstone (less than 200 mesh) 25 parts Colored aggregate (less than 16 mesh) 200 parts Water and methyl cellulose in the above mixture was added, kneaded, extruded to a width of 50 mm and a thickness of 10 mm, and cut to a length of 100 mm to prepare a sample. The samples were pre-hydrated and air dried at 105°C. The sample plate was fired in a roller hearth kiln at a maximum temperature of 1200° C. for 20 minutes.

No efflorescence was visually observed in the ceramic plate obtained, the bending strength was 260 kgf/cm2, and the shrinkage rate was 0.8%. The bending strength was measured using JIS at a span interval of 90 mm and a loading rate of 2 mm/min.
I followed A5209.

Example 2: The upper surface of the pre-hydrated and dried sample plate of Example 1 above was coated with feldspar in % dry weight.
A slurry of glaze consisting of 10% of calcium carbonate, 5% of zinc white, 25% of talc, 10% of silica sand, and 10% of frog's eye clay was spray applied at a dry weight of about 50 mg/cm 2 . This was fired in the same manner as in Example 1 to obtain a glazed ceramic board free of efflorescence.

Example 3 (Reference example for comparison): The same procedure as in Example 1 was carried out using 20 parts of waxite powder (aluminum silicate mineral), 20 parts of ordinary Portland cement, 20 parts of glass powder, and 40 parts of colored siyamoto aggregate as raw materials. .

The amount of efflorescence on the obtained ceramic plate was approximately 2% of the total surface area when visually observed. The bending strength is
The firing shrinkage rate was 224 kgf/cm2 and 0.8%.

Example 4 (Reference Example for Comparison): The same procedure as in Example 3 was carried out except that 20 parts of serpentine powder (magnesium silicate mineral) was used in place of the waxite powder in Example 3 above.

The amount of efflorescence on the obtained ceramic plate was approximately 2.5% of the total surface area when visually observed. The bending strength was 242 kgf/cm2, and the firing shrinkage rate was 1.0%.

Example 5 (Reference example for comparison): 30 parts of ordinary Portland cement and 30 parts of glass powder without using wax stone powder or serpentine powder as raw materials.
Example 3 was carried out using 40 parts of colored Shamotsu aggregate.

The amount of efflorescence on the obtained ceramic plate was approximately 20% of the total surface area when visually observed. The bending strength is
The firing shrinkage rate was 217 kgf/cm2 and 0.9%.

Actions and Effects The efflorescence phenomenon of ceramic products whose main components are hydraulic cement and vitrifying material powder (so-called flux component) is caused by () the presence of a water-soluble base component in the vitrifying material (flux component);
() The base component in the vitrifying material and the acid (sulfuric acid radical) in the cement react to form a salt, which remains as an alkali metal oxide, and () the cement is decomposed and activated during firing to form CaO, etc. This is the main cause.

In the present invention, active silicate minerals (or aluminum silicate minerals) and magnesium silicate minerals are made to coexist and fired at a temperature of 1100°C or higher. By combining these structures, the above factors for efflorescence (),
It has been found that (), () can be advantageously resolved.

That is, it is considered that the above cause () is resolved because the water-soluble base component in the glass component reacts with the high temperature firing at 1100° C. or higher and is practically fixed in the glass. The solution to the above cause () is that, for example, sodium sulfate produced from vitrifying materials and cement reacts with active silicic acid produced from active silicate minerals or aluminum silicate minerals at high temperatures, resulting in stable Na It is thought that this is to form ₂ O.nSiO ₂ . The solution to the above cause () is that activated decomposition of CaO, etc. reacts at high temperatures, and aluminum silicate minerals, such as CaO.
_mAl2O3・_{nSiO2 is} formed and stabilized, and magnesium silicate minerals are, for example, CaO・mMgO・
It is thought that this is to form nSiO ₂ and stabilize it.
Furthermore, since the high-temperature reaction product of CaO or the like and magnesium silicate mineral has high strength, it improves the strength of the ceramic product of the present invention. By combining these structures and effects, the present invention can advantageously achieve the prevention of efflorescence, increase in strength, prevention of firing shrinkage deformation, etc.

Claims (1)

[Claims] 1. Molding a mixture consisting essentially of hydraulic cement, molten vitrifiable material powder, magnesium silicate mineral powder, activated silicate mineral powder and/or aluminum silicate mineral powder, and water; Preliminary hydration hardening of the molding; then the molding at a maximum temperature of 1100 °C
A method for producing ceramic products that substantially prevents efflorescence, which is characterized by a process of firing at temperatures above ℃. 2. The magnesium silicate mineral is selected from serpentinite minerals, talc, and mixtures thereof, and the activated silicate mineral and/or aluminum silicate mineral is selected from waxite, finely powdered silica sand, amorphous silica, and mixtures thereof. The manufacturing method according to claim 1. 3. The manufacturing method according to claim 1 or 2, wherein a glaze is applied to a required surface of the molded product which has been preliminarily hydrated and hardened, and then fired. 4 Hydraulic cement; Melting vitrifying material powder; Magnesium silicate mineral powder selected from serpentinite minerals, talc, and mixtures thereof; and Mineral powder selected from waxite, finely powdered silica sand, amorphous silica, and mixtures thereof. becomes essential. A high temperature fired ceramic product; a high temperature reaction product of calcium oxide and the magnesium silicate mineral is formed in the ceramic; the cement component essentially acts as an aggregate and substantially prevents firing shrinkage deformation. death;
And a ceramic product characterized by substantially no efflorescence of the ceramic. 5. The ceramic product according to claim 4, which has a glaze layer on a required surface of the ceramic product.