JPH1135317A - Production of pollucite composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a vitrified compsn. having little impurities, high heat resistance and low thermal expansion by subjecting a source material which can produce a pollucite compsn. to arc melting in an atmosphere of Ar, He or Ne in the specified concentration in an arc melting electric furnace and the rapidly cooling the molten material. SOLUTION: A source material (e.g. cesium carbonate, low sodium alumina and high purity silica sand) is mixed preferably in a specified molar ratio (Cs2 O: Al2 O3 :SiO2 =1:1:4), heat treated at 1000 to 1200 deg.C, subjected to arc melting in an arc melting electric furnace, and then rapidly cooled. The electric furnace used is preferably lined with a hot-melt cast refractory material which can be used preferably even at 2000 deg.C (such as alumina-zirconia) and arc melting is preferably performed in an atmosphere of >=80 vol.% inert gas comprising one or more gases of Ar, He and Ne formed by blowing through a penetrating hole 5 formed in the longitudinal direction in the center of a graphic electrode 4. The obtd. compsn. is preferably cesium aluminosilicate expressed by Cs2 O:xAl2 O3 :ySiO2 , wherein (x) is 0.5 to 1 and (y) is 2 to 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a porucite composition.

[0002]

2. Description of the Related Art High-temperature refractory ceramic materials require extremely high temperatures in order to synthesize and shape them from the conflicting uses of fire resistance. It was difficult to synthesize products made of these highly refractory materials using standard equipment, and it was too uneconomical at the production stage. Such a situation is often seen in refractories such as steel kilns and glass kilns, but the same can be said for porusite. Polucite is stoichiometric in Cs ₂ O.Al ₂ O ₃ .4SiO
_{2 is} an aluminosilicate oxide material. Its melting point is 1900 to 2000 ° C., which is the highest refractory silicate. In addition to this high heat resistance, a low modulus of elasticity and a low coefficient of thermal expansion (2 to 3 × 10
^-6 / ° C). Therefore, the material is resistant to thermal shock and can withstand use under severe conditions of high temperature. Despite having such excellent physical properties, the reason why it does not lead to practical use is that it is difficult to synthesize and melt to obtain a glass composition by a general method because of its high heat resistance. . U.S. Pat. No. 3,723,140 discloses a method of making glass ceramics with porusite as the main crystal. According to this, a rhodium crucible was used for the production of glass as a precursor thereof, and a zirconia heating element was used as an electrode.
Melted at a temperature of 800 to 2000 ° C. In such a synthesis method, it is difficult to quench rapidly and it is difficult to obtain a good amorphous body. In particular, it is almost impossible to synthesize in large quantities at the production stage. Japanese Patent Laid-Open No. 5-
155657 discloses a method of substituting cesium ions in zeolite containing potassium ions and the like, calcining the glass at a low temperature, and then manufacturing a ceramic. However, although it is possible to obtain an amorphous body at a low temperature by such a synthesis method, there is a problem that the number of manufacturing steps is large and complicated.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to easily prepare and provide a glass composition having a porucite composition on the basis of these conventional techniques.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve various problems of the prior art and to easily provide a vitrified composition having a porucite composition.

The present invention has been made in order to solve the above-mentioned problems. A first invention is to provide a raw material capable of producing a porucite composition in an arc melting electric furnace in which 80% by volume or more of Ar, He or A method for producing a porusite composition, which comprises arc-melting in any atmosphere of Ne, followed by quenching. In the furnace, 80% by volume or more of Ar, He, or Ne is blown through a hollow formed in the longitudinal direction of the central portion of the graphite electrode through an inert gas composed of at least one of Ar, He, and Ne, followed by arc melting and quenching. It is intended to provide a method for producing a porucite composition.

As described above, according to the present invention, a raw material of porusite is placed in an arc melting electric furnace in a general method as follows.
The melting may be performed in an atmosphere of at least one of Ar, He, and Ne of 0% by volume or more. As a preferable specific means, a graphite electrode having a hollow portion is used. The arc melting may be performed while blowing an inert gas containing 80% by volume or more of any one of Ar, He and Ne.

In these inventions, one of the desirable embodiments is to discharge the arc-melted composition into water and quench it, and this is possible.

Another desirable embodiment is to use a hot-melt cast refractory as a lining refractory of an electric furnace for melting an arc, whereby a high-purity porusite composition having a small amount of impurity components is obtained. Things are obtained.

As described above, in a preferred embodiment of the arc melting electric furnace employed in the present invention, the lining of the arc melting electric furnace is formed of a molten cast refractory.

First, the electric furnace of the present invention will be described with reference to the cross-sectional view of the electric arc melting furnace shown in FIG. In FIG. 1, the single-phase arc melting electric furnace is configured such that a refractory 3 is lined inside an iron kiln 1 provided with a water cooling tube 2. Graphite electrode 4 of the arc melting furnace
There is a through-hole 5 in the vertical direction (longitudinal direction) at the center of the hole, and O filled in the gas cylinder 10 from above the through-hole 5.
_{2. The} structure is such that a gas 6 such as Ar, He, Ne or the like of 20% by volume or less can be blown. The graphite electrode 4 can be moved up and down, left and right by changing the molten metal surface position of the glass as the molten composition, and the arc melting electric furnace is not shown but can be tilted so that the contents can flow out.

The refractory used in the present invention is preferably an alumina-based, alumina-silica-based, alumina-zirconia-based, or zirconia-based refractory which can be used even at a high temperature. However, in the case of a sintered brick, when the temperature becomes high as 2000 ° C., a large amount of the composition is mixed in from the furnace material, and the desired porucite composition aimed at by the present invention having both high heat resistance and low expansion coefficient is obtained. 2000 ℃
However, it is preferable to use a hot-melt cast refractory of the same type that can be used.

In the raw material powder, it is preferable to use a cesium salt such as cesium carbonate or cesium nitrate as a cesium source. The alumina and silica sources may be naturally occurring corundum, silica sand, or the like, and it is preferable to use any raw material having a purity of 95% or more. 9 purity
It is preferable that the content be 5% or more because the purity is 9%.
If the number is less than 5, the heat resistance of the porusite decreases due to impurities contained in the raw material. The cesium salt to be used has a high water absorption, and is sufficiently dried and mixed, or after mixing a predetermined amount of each type of powder as a raw material, once from 1000 to 120
It is preferable to heat-treat at a low temperature of about 0 ° C. and use it as a raw material. The stoichiometric ratio of porusite is Cs ₂ O: Al in molar ratio.
₂ O ₃ : SiO ₂ = 1: 1: 4. The porusite composition produced according to the present invention comprises Cs ₂ O, Al ₂ O ₃ , SiO
_{2 in} a molar ratio of Cs ₂ O: xAl ₂ O
₃ : It is preferable that x = 0.5 to 1 and y = 2 to 8 in ySiO ₂ . The reason for limiting the chemical composition ratio as described above is that when x <0.5, y <2 or x> 1, y> 8, other than the target porusite, other cesium aluminum silicates such as CsAlSiO ₄ and mullite, or This is because alumina and silica as starting materials are obtained as a mixed phase, which impairs high heat resistance and low coefficient of thermal expansion, which are advantages of porucite.

As for the melting method, the raw material 7 is charged into the above-described arc melting electric furnace from the raw material charging port, and in the initial stage, the graphite electrodes are brought into contact with each other and melted by arc discharge heating. Then, as the generated molten glass increases, the interval between the graphite electrodes is gradually increased. The graphite electrode can be melted even when it is in contact with the molten glass, but it is preferably separated from the surface of the molten glass by 20 to 30 mm above the molten liquid surface. And O ₂ 20 from the center of the graphite electrode
Blowing a gas such as Ar, He, Ne, etc., by volume
A temperature of tens of thousands of degrees can be easily obtained from the discharge heating by the gasification of the gas, and a vitrified material having a porucite composition can be obtained.

In the present invention, the arc melting may be carried out under an atmosphere of the above-mentioned inert gas as the atmosphere during melting. Specifically, it can be desirably achieved by using a hollow electrode as a graphite electrode.

The diameter of the through hole provided at the center of the graphite electrode may be 1/2 to 1/3 of the diameter of the graphite electrode, and it is sufficient if gas is released at or near the electrode tip. . In order to stably convert the supplied gas into plasma, the structure must be such that the gas does not leak. In this regard, the gas supply should be controlled at the tip of the electrode. easy. The gas blown from the holes of the graphite electrode is preferably Ar, He, or Ne having a high concentration.
N ₂ and O ₂ are not preferred. The reason is that when the concentration of N ₂ gas is high, nitrides are formed in the porucite composition,
High heat resistance, because low expansion is impaired, also O ₂
This is because if the gas concentration is high, the amount of CO generated by reacting with the graphite electrode increases, and the contact with the molten composition impairs the high heat resistance and the low expansion property as well as the influence of N ₂ gas. In particular, when a mixed gas of Ar and O ₂ is used, the higher the proportion of O ₂ , the higher the degree of oxidation can be obtained, but the generated plasma becomes unstable, and it is difficult to obtain a high temperature. Absent.

From this viewpoint, the gas introduced under arc melting in the present invention has a purity of 80% by volume.
Above, it is necessary to use one or more of Ar, He and Ne, and it is particularly desirable to use one having a purity of 90% by volume or more. The graphite electrode is disposed in a state of being in contact with the glass surface by arc discharge in a state where the graphite electrode is in contact at the initial stage of melting of the vitrification raw material. At this stage, graphite is slightly contaminated by the carbon component of the molten glass composition, but if a glass melt is generated, the graphite electrodes are raised, the electrodes are widened, and gases such as Ar, He, Ne, etc. are blown into plasma, By heating, glass with less impurities and coloring can be obtained. When the glass is melted, the flow rate of gas required for generating plasma ions needs to be about 10 liter / min. If the flow rate is small, the arc discharge increases, and if the flow rate is large, the plasma becomes unstable, which is not preferable.

The glass which provides the porusite composition which has been sufficiently melted by the above-mentioned method can be glass cullet obtained by tilting the arc melting furnace and discharging the water into the water from the tap hole 9.

As described above, the arc melting method of the present invention can easily obtain a high temperature, and can be rapidly cooled by a method such as water cooling. Therefore, it becomes possible to easily and in large quantities obtain a glass having a porousite composition requiring a temperature of 2000 ° C.

[0019]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 In order to synthesize a porucite glass composition, cesium carbonate, low soda alumina, and high-purity silica sand were melted as raw materials and then mixed in a molar ratio of 1: 1: 4. did. This is shown in FIG. 1 by an arc melting electric furnace of an alumina-silica-based fused cast refractory (a refractory CB-M manufactured by Asahi Glass Co., Ltd. composed of 79% of alumina, 16% of silica, and 5% of others by weight analysis). The furnace was charged. In the initial stage of dissolution, the graphite electrode was brought into contact and melted by the contact arc discharge. After a certain amount of melt is generated, the electrode is gradually spread and raised, and Ar gas (concentration of 95% or more) is caused to flow by plasma discharge while flowing 10 liter / min from the hole (inner diameter 50 mm) of the graphite electrode (outer diameter 150 mm). It melted completely. The melt was poured into a water tank by tilting the electric furnace to obtain a glass cullet.

The obtained glass of porusite composition was colorless and transparent. Glass composition after melting Cs ₂ O: Al ₂ O
_3: SiO ₂ is 1: 1.1: has been a 4.5. The glass was crystallized at 1400 ° C., pulverized, and identified by powder X-ray diffraction. As a result, it was found to be a single phase of porusite. This powder was molded at 1000 kg / cm ² ,
After heat treatment at 0 ° C., the thermal expansion coefficient was measured.
^The expansion was as low as ^-6 / ° C.

Example 2 In order to synthesize a porucite glass composition, cesium carbonate, low soda alumina, and high-purity silica sand were melted as raw materials, and the molar ratio was 1.1: 1:
4 and mixed. This was once subjected to a heat treatment at 1200 ° C. using a resistance heating electric furnace to be crushed. The powder was lined with an alumina-zirconia-based molten cast refractory (46% alumina, zirconia 4 by weight analysis) as shown in FIG.
The refractory ZB-1711 manufactured by Asahi Glass Co., Ltd. consisting of 1%, silica 12% and other 1% was charged into an electric arc melting furnace. In the initial stage of dissolution, the graphite electrode was brought into contact and melted by the contact arc discharge. After a certain amount of melt is generated, the electrode is gradually spread and raised, and Ar gas (concentration of 95% or more) is caused to flow by plasma discharge while flowing 10 liter / min from the hole (inner diameter 50 mm) of the graphite electrode (outer diameter 150 mm). It melted completely. The melt was poured into a water tank by tilting the electric furnace to obtain a glass cullet.

The resulting glass with porusite composition was slightly yellowish but transparent. The glass composition after melting was almost stoichiometric. The amount of zirconia mixed in the glass was 0.5 wt% or less. The glass was crystallized at 1400 ° C. The crystallized glass was pulverized and identified by powder X-ray diffraction. As a result, it was found to be a single phase of porusite. 1000 kg / c of this powder
After molding at m ² and heat treatment at 1500 ° C., the coefficient of thermal expansion was measured. The result was a low expansion of 2.5 × 10 ⁻⁶ / ° C.

Comparative Example In order to synthesize a porucite glass composition, cesium carbonate, low soda alumina, and high-purity silica sand were melted as raw materials and mixed at a molar ratio of 1: 1: 4. . This is shown in FIG. 1 by an arc melting electric furnace of an alumina-silica-based fused cast refractory (a refractory CB-M manufactured by Asahi Glass Co., Ltd. composed of 79% of alumina, 16% of silica, and 5% of others by weight analysis). The furnace was charged. In the initial stage of dissolution, the graphite electrode was brought into contact and melted by the contact arc discharge. After a certain amount of melt is generated, the electrode is gradually spread and raised, and O ₂ 30% by volume Ar gas (concentration: 955 or more) is supplied to a graphite electrode (outer diameter: 150%).
mm) from the hole (inner diameter 50 mm)
It melted completely while flowing. The melt was poured into a water tank by tilting the electric furnace to obtain a glass cullet.

The obtained glass of porusite composition had a dark tint. Glass composition after melting Cs ₂ O: Al ₂ O
₃ : SiO ₂ was 1: 1.1: 4.3, and 0.5% of carbon component was mixed as an impurity. The glass was crystallized at 1400 ° C., pulverized, and identified by powder X-ray diffraction. As a result, it was found to be a single phase of porusite. This powder was molded at 1000 kg / cm ² , heat-treated at 1500 ° C., and the coefficient of thermal expansion was measured. As a result, it was 3.7 × 10 ⁻⁶ / ° C. In addition, many bubbles were confirmed in the obtained sintered body.

[0026]

According to the present invention, a large amount of a porusite composition having high heat resistance and low thermal expansion can be easily obtained without impairing its properties.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of an arc melting electric furnace used in the method of the present invention.

[Explanation of symbols]

 1: kiln 2: water cooling tube 3: refractory 4: graphite electrode 5: through hole 6: gas 7: glass raw material 8: molten glass 9: tap hole 10: gas cylinder

Claims (5)

[Claims] A raw material capable of producing a porousite composition is arc-melted in an arc-melting electric furnace under an atmosphere of at least one of Ar, He, and Ne of 80% by volume or more, and then rapidly cooled. A method for producing a porucite composition. 2. A raw material capable of producing a porucite composition,
In an arc melting electric furnace equipped with a graphite electrode, an arc is blown by blowing an inert gas containing 80% by volume or more of any one of Ar, He, and Ne through a central hole formed in a longitudinal direction of a central portion of the graphite electrode. A method for producing a porucite composition, which comprises melting and then quenching. 3. The method of claim 1, wherein the porusite composition is Cs ₂ O: xAl.
₂ O ₃ : ySiO ₂ (where x = 0.5 to 1, y = 2 to 2)
The method for producing a porusite composition according to claim 1 or 2, which is a cesium aluminosilicate consisting of 8). 4. The method for producing a porusite composition according to claim 1, wherein the molten metal is poured into water after the arc melting and quenched. 5. The method for producing a porousite composition according to claim 1, wherein the arc melting is performed in an electric furnace lined with a hot-melt cast refractory.