JPH0234901B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing ceramic materials, and more particularly to a method for producing ceramic materials, and more particularly, a method for producing ceramic materials.
The present invention relates to a method for producing ceramic materials with excellent formability using melted phosphorous as the main raw material.

Both calcined phosphorus fertilizer and dissolved phosphorus fertilizer are widely used industrially as phosphoric acid or lime fertilizers. Calcined phosphorus fertilizer contains Ca ₃ (PO ₄ ) ₂ and
It is a solid solution of CaNaPO ₄ , and among these, magnesia heavy phosphorus fertilizer has MgO and SiO ₂ components dissolved in it. On the other hand, dissolved phosphorus fertilizer is CaO―MgO―P ₂ O ₅ ―
It is made of glass whose main component is F.
Phosphate ion is present as a single ion.

Conventionally, calcined phosphorus fertilizer and dissolved phosphorus fertilizer have been industrially produced and used mainly as fertilizers, but no attempt has been made to utilize them as ceramic materials.

An object of the present invention is to provide a method for producing a ceramic material having stable quality and good formability using calcined phosphorous fertilizer or melted phosphorous fertilizer as a raw material.

The present inventors focused on the fact that both calcined phosphorous fertilizer and fused phosphorous fertilizer can be produced industrially in large quantities under stable quality control, and can be obtained at low cost.
We investigated the use of this material as a raw material for ceramic materials. As a result, the main crystal structure of calcined phosphorous fertilizer or melted phosphorous fertilizer is apatite-based,
The crystal has a scale-like shape with a comparative hardness of about 5 on the Mohs scale, so if it is formed and fired, it can be machined with a carbide tool, and has extremely excellent properties as a ceramic material that requires forming. They discovered this and arrived at the present invention.

The present invention is characterized by using at least one of calcined phosphorous fertilizer or melted phosphorous fertilizer as the main raw material, adding a plastic clay material or an organic paste to this to form a prepared composition, and firing the composition. It is.

The calcined phosphorus fertilizer or melted phosphorus fertilizer used as a raw material in the present invention is usually preferably a commercially available product. can be used as raw materials.

The raw materials are used as a powder, but in the case of calcined phosphorus fertilizer, it is sometimes dry-pulverized because it contains phosphoric acid that is soluble in water, but in the case of molten phosphorus fertilizer, it is sparingly soluble in water. Therefore, in addition to dry grinding, wet grinding is also possible. In order to produce the cementing effect of phosphoric acid during wet pulverization, an aqueous citric acid solution may be added during pulverization to elute phosphate ions in the soluble phosphorus fertilizer.

In the present invention, calcined phosphorous fertilizer or soluble phosphorous fertilizer includes zinc (Zn), magnesium (Mg), aluminum (Al), zirconium (Zr), barium (Ba), titanium ( Oxides, hydroxides, fluorides, etc. of Ti), potassium (K), sodium (Na), lithium (Li), and silicon (Si) can be added. These additives adjust the particle size of apatite crystals in the resulting ceramic material, and react with excess phosphoric acid in the phosphorus fertilizer to release phosphorus at room temperature or low temperature (approximately 400°C or less). It produces an acidic cement-like substance, exhibits self-hardening properties during molding, and has the effect of increasing the density and strength of the resulting ceramic material. Furthermore, Zn in the additive,
Oxides, hydroxides, and fluorides such as Ba, K, Na, and Li have the effect of reducing high-temperature viscosity, promoting apatite crystal growth, and lowering the firing temperature.
In particular, ZnO, which is known as zinc phosphate cement, exhibits strong self-hardening properties, so it can be applied to molding such as when making cement concrete products. Also ZrO ₂ , Al ₂ O ₃ C, SiO ₂ ,
It was found that MgO, TiO _2, etc. are effective in increasing high-temperature viscosity and making the product have a microcrystalline structure.

The amount of the above-mentioned additives added is generally in the range of 1 to 30% (based on weight, the same applies hereinafter). 30 for _SiO2 etc.
(on a weight basis, the same applies hereinafter), but for alkali oxides such as K ₂ O and NaO, a range of 1 to 5% is appropriate, and experiments have shown that it is generally preferable to mix two or more types. Approved by.

The composition consisting of the above-mentioned phosphorous fertilizer and the above-mentioned additives added as necessary is subjected to viscosity adjustment by adding water and, if desired, an organic paste, and then subjected to casting molding, injection molding, powder pressure molding, hot press molding, etc. It is molded and fired using ordinary ceramic molding methods such as . In the case of the above-mentioned powder pressure molding, organic glue such as CMC (carboxymethyl cellulose) or PVA (polyvinyl alcohol) is added at 1 to 3%, and the moisture is 5 to 10% and placed in a mold, generally at a rate of 300 kg/ ^cm2.
A molded body is obtained by pressure molding at a pressure above, but in the case of injection molding or cast molding, plastic clay is
Formability can be improved by adding 10%. In addition, during molding, by adding 0.5 to 2.0% of sol of silica, alumina, lithium, zirconia, etc. and water glass, etc., the composition becomes viscous due to the reaction between these and the phosphate ions in the composition. obtained, and can be easily molded.

In the present invention, when soluble phosphorous fertilizer is used as a raw material, the soluble phosphorous fertilizer is heated to 1100°C or higher to form fluoroapatite crystals in advance, and then the above-mentioned additives are added to adjust the composition. , molding,
By firing, a ceramic material with particularly excellent machinability can be obtained. When the thus pretreated composition is molded by a method such as cast molding or injection molding, a structure in which apatite crystals are layered and oriented within the molded body is obtained, resulting in a ceramic product with excellent machinability and strength. be able to.

In addition, instead of reheating the soluble phosphorus fertilizer at a temperature of 1100℃ or higher, by processing approximately 200 mesh powder of soluble phosphorus fertilizer in an autoclave at 180℃ or higher in pressurized steam. It was found that fluoroapatite crystals were precipitated on the particle surface, indicating that the material was obtained from a material with excellent machinability, similar to the above. These heat-treated crystallized products can be used as is, or they can be used again.
It may be used after heating to 1100°C to form even larger crystals.

As described above, according to the present invention, a composition prepared by using calcined phosphorous fertilizer or (and) soluble phosphorous fertilizer as raw materials and adding metal oxides, organic glue, and water as necessary is molded and fired. As a result, ceramic materials with excellent moldability, mechanical properties, etc. can be manufactured.

Next, the present invention will be specifically explained with reference to Examples.

Example 1 100 parts of soluble phosphorus fertilizer (commercially available "Yorin", manufactured by Shin-Etsu Kasei Co., Ltd.) (based on weight, the same applies hereinafter), 5 parts of bentonite, and 5 parts of zinc oxide to 1:1 water.
It is added at a ratio of
2% of silica sol was added and kneaded to obtain a plastic composition. This composition was injected at an injection pressure of 50Kg/cm ²
It was injection molded into a pipe shape with an outer diameter of 100 mmφ and a wall thickness of 10 mm using an injection molding machine, and then the pipe was cut into a plate-like molded product. This molded body was irradiated with far infrared rays to dry it to a moisture content of 8%, and then dried with hot air, and then placed in a roller hearth kiln at a firing temperature of 1160°C and fired for 2 hours to obtain a sintered body. The obtained sintered body had a dense structure with an absorption rate of 0.8% and a Mohs hardness of 6, and could be ground with a carbide tool, and its bending strength was 850 kg/cm ² or more.

Example 2 70 parts of soluble phosphorus fertilizer (same as Example 1), heavy burnt phosphorus
A molding composition was prepared consisting of 30 parts of aluminum hydroxide and 5 parts of aluminum hydroxide. Soluble phosphorus fertilizer was wet-pulverized, and heavy-burning phosphorus was dry-pulverized. Powders of 200 meshes or less were used for each, and commercially available powders of 325 meshes or less of aluminum hydroxide were used.
These dry powders were mixed in a mixer for 30 minutes, and 5% water was added to obtain a powder for molding. Fill a mold with this molding powder and use a hydraulic press to
It was molded into a plate-shaped body of 100 mm x 200 mm x 10 mm under a pressure of 450 Kg/cm ² , and after drying, it was fired for 90 minutes in a roller hearth kiln at 1200° C. to obtain a sintered body. The physical properties of this sintered body are a water absorption rate of 1.5% and a Mohs hardness of 5.
Its bending strength was 750Kg/cm ² . Moreover, it was possible to drill holes in this sintered body using a carbide drill.

Example 3 A commercially available soluble phosphorous fertilizer (same as in Example 1) was pulverized to 200 mesh or less and treated in an autoclave at 10 atm for 5 hours, and then further heated at 1100°C.
It was baked for about 3 hours. The obtained fired product was a weak sintered product in which large fluoroapatite crystals were formed. This sintered material was further refined into powder with a size of 200 mesh or less.

After mixing 100 parts of the above-mentioned soluble phosphorous fertilizer, 5 parts of titanium oxide, 5 parts of zinc oxide (ZnO), and 5 parts of sericite clay powder in an amount of 200 mesh or less each in a mixer, 25 parts of a 17% phosphoric acid solution was added. was added and stirred and kneaded to obtain a viscous plastic composition. After kneading this plastic composition for 20 minutes, it was heated and concentrated to bring the water content to 15%. This composition was injected at a pressure of 50Kg/
^cm2 injection molding machine, diameter 100mm, wall thickness 10mm
This was then formed into a plate-like molded product. Far infrared rays are applied to this plate-shaped molded body.
After irradiating for 20 minutes and further drying in a dryer at 100°C, it was supplied to a roller hearth kiln with a firing temperature of 1160°C and fired for 90 minutes to obtain a sintered body. The obtained sintered body has a Mohs hardness of 5 to 6, a water absorption rate of 0.6%, a bending strength of 800 kg/cm2 ^or more, and has excellent machinability, allowing drilling with a carbide drill and threading. The material was hot.

Example 4 Alumina sol ( When 10 parts of (manufactured by Nissan Chemical Co., Ltd.) are added and stirred, thermosetting aluminum phosphate is produced by reacting with the phosphoric acid component dissolved in the water, forming a viscous paste.

After vacuum degassing these pastes, the thickness
The mixture was injected into a wooden mold for making a 10 mm plate, dried and hardened, and then cured under far infrared rays at temperatures above 250°C, followed by firing at 1100°C to obtain a dense sintered body.

The obtained sintered body has a Mohs hardness of 6 and can be easily drilled with a carbide tool, and its bending strength is
It was 450Kg/ ^cm2 .

As mentioned above, the present invention uses at least one of calcined phosphorous fertilizer and soluble phosphorous fertilizer as the main raw material,
By utilizing the crystallinity of these raw materials, new ceramic materials with excellent moldability and machinability can be obtained. In addition, the raw materials, calcined phosphorus fertilizer and soluble phosphorus fertilizer, are mass-produced as commercially available fertilizers, are easy to obtain, and have stable quality, so the resulting ceramic materials can also be mass-produced with stable quality. It is possible to make it a product.

Claims (1)

[Scope of Claims] 1. A method for producing a ceramic material, which comprises molding and firing a composition prepared by adding additives to the main raw material, using at least one type of calcined phosphorous fertilizer or melted phosphorous fertilizer. . 2 In claim 1, it is provided that the melted phosphorous fertilizer is preheated to 1100°C or higher, or
A method for producing a ceramic material, characterized in that the raw material is a material treated under pressurized steam at a temperature of ℃ or higher.