JP2771416B2 - Beta alumina tube firing 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 firing a beta alumina tube in a sodium-sulfur battery.

[0002]

2. Description of the Related Art Generally, when a beta-alumina tube of this type is formed using a molding aid such as an organic binder, when the beta-alumina tube is fired without degreasing when firing, Pores increased in the structure of the fired article after the main firing , resulting in a decrease in strength and density.

For this reason, in a conventional method for firing a beta alumina tube, degreasing and main firing are performed in separate firing furnaces.
It was done in the process.

[0004]

However, in this conventional method, since the degreasing and the main baking are performed in two steps, there is a problem that the working steps become complicated and unsuitable for mass production. . Further, in the conventional method, during the transition from the degreasing step to the main firing step, since the degreased fired product is once cooled, there is a problem that cracks due to heat shrinkage occur in the fired product after the main firing. Was. In addition, in the degreasing process, since a sheath pot having a partially open side surface is used, silicic acid (SiO ₂ ) in the furnace wall brick adheres to the surface of the molded product, and the composition of the portion changes, so that beta alumina is used. There has been a problem that the tube becomes unsuitable or a so-called white spot occurs to cause poor appearance.

[0005] The present invention has been made in view of the problems existing in such prior art, and an object thereof is to continuously perform degreasing and main firing in one operation process. It is possible to perform mass production, and between the degreasing and the main baking, the fired product after the degreasing is not cooled, and cracks or the like occur in the fired product after the main baking. An object of the present invention is to provide a method for firing a beta-alumina tube, which can surely prevent the possibility of deterioration in performance and appearance defects such as white spots.

[0006]

To achieve the above object, according to the solution to ## in the firing method of the beta-alumina tube according to claim 1, containing a molded article of the beta-alumina tube sintering vessel, the firing container Of the opening that connects the inside and outside of the
And parts, between the possible lid closing the same opening 700-1
000 interposed a gap forming material to decompose burned in ° C., by heating the whole up to 700 to 1000 ° C. In this state, the edge of the opening
Decompose gas by releasing decomposition gas from the gap between the part and the lid,
Thereafter, the whole is heated to 1000 ° C. or more to decompose and burn the gap forming material, and the main firing is performed in a state where the gap between the edge of the opening and the lid is sealed. It is assumed that. The method for firing a beta alumina tube according to claim 2.
The beta-alternator in a firing vessel with an opening at the top.
The molded product of the mina tube is housed in the opening of the firing vessel,
And a closing plate having a plurality of recesses on the upper surface, and
The gap forming material is accommodated in the
A gap is formed between the chain plate and the top lid, and in this state the entire
Heating, releasing decomposed gas from the gap to perform degreasing,
When the heating temperature exceeds the specified temperature, the gap forming material shrinks
The gap is closed and the inside of the firing vessel is sealed
The main firing is performed.

[0007]

In the method for firing a beta-alumina tube according to claim 1, the molded product of the beta-alumina tube is accommodated in the firing container, and the firing container is placed in the firing container.
A gap forming material is interposed between the edge of the opening and the lid. Then, when the whole is heated to 700 to 1000 ° C. in this state, the decomposed gas is released from the gap between the edge of the opening and the lid to perform degreasing. Thereafter, when heating the entire above 1000 ° C., the gap forming material is decomposed combustion openings
The gap between the edge of the lid and the lid is sealed , preventing the scattering of sodium.
The main baking is performed in an atmosphere where the baking is prevented . Claim 2
In the method for sintering beta alumina tubes described above, the sintering vessel
Closure having a through hole in the opening and a plurality of recesses on the top surface
Place the plate. Then, a gap forming material is accommodated in the recess.
And place the top lid, and place a gap between the closing plate and the top lid.
Is formed. Heat the whole in this state, and
Decomposed gas is released to perform degreasing, and the heating temperature is
The gap is closed by the contraction of the gap forming material when exceeding
Is done. As a result, the gap between the closing plate and the top lid is sealed,
Main firing is performed in an atmosphere where sodium is prevented from scattering.
It is.

Therefore, according to the method for firing a beta-alumina pipe according to the first or second aspect, the degreasing and the main firing can be continuously performed in one operation step, thereby enabling mass production. Can be. In addition, since the degreasing and the main firing are continuously performed in one step, and during this time, the fired product after the degreasing is not cooled, so that there is a possibility that cracks may occur in the fired product after the main firing. Can be prevented. Further, it is possible to effectively prevent the performance from being deteriorated due to the composition fluctuation due to the adhesion of silicic acid or the like, and the possibility of causing poor appearance such as white spots.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for firing a beta-alumina tube embodying the present invention will be described below in detail with reference to FIGS.

In the firing method of this embodiment, the firing table 1
The setter 2 is placed on the top, and the beta alumina tube molded article 3 is supported on the setter 2. Further, the firing container 4 is placed on the firing table 1 and the molded article 3 is accommodated in the firing container 4. Then, the closing plate 5 is placed on the upper opening of the firing container 4, and an upper lid 8 as a lid is disposed on the upper edge of the opening of the through hole 6 provided at the center thereof via a plurality of gap forming materials 7. . What
In this embodiment, a through hole 6 provided in the closing plate 5 is used.
Opening is formed.

In this embodiment, the gap forming material 7 is formed of a non-reactive material such as carbon or graphite, and the gap forming material 7 is interposed between the upper lid 8 and the closing plate 5. A gap having a height of 2 to 10 mm is formed. When heated to a predetermined temperature of 700 to 1000 ° C. in an oxidizing atmosphere, the gap forming material 7 made of carbon, graphite, or the like is decomposed and burned and disappears, and the gap between the upper lid 8 and the closing plate 5 is closed. It is supposed to be.

Then, in this state, the whole is inserted into a firing furnace or the like, and the molded article 3 is heated to a predetermined temperature of 700 to 1000 ° C. in accordance with the temperature characteristics shown in FIG. Then, the decomposed gas or water vapor generated from the molded article 3 due to the heating is released to the outside from the gap between the upper lid 8 and the closing plate 5 to perform degreasing.

When the heating temperature is in the range of 700 to 1000 ° C., the gap forming material 7 is decomposed and burned. When the heating temperature is higher than 1000 ° C., the gap forming material 7 completely disappears, and the gap between the upper lid 8 and the closing plate 5 is closed. Then, the firing container 4 is sealed. In this state, according to the temperature characteristics shown in FIG.
Heat to the above temperature and heat at 1600 ° C. for 1 hour.
Then, in an atmosphere that prevents scattering of sodium are Ingredients of beta-alumina, the sintering of the molded article 3 is performed.

Therefore, according to the method for firing a beta-alumina tube of this embodiment, degreasing and main firing can be continuously performed in one operation step, thereby enabling mass production. In addition, since the degreasing and the main baking are performed continuously in one step without transferring the molded article 3 between different steps, the molded article 3 is not cooled between the degreasing and the main baking. In addition, it is possible to reliably prevent the molded article 3 after the main firing from cracking due to heat shrinkage. In addition, it is possible to effectively prevent a decrease in performance such that the tube cannot be used as a beta-alumina tube due to a composition change due to adhesion of silicic acid, and it is also possible to effectively prevent a possibility of occurrence of poor appearance due to white spots.

[0015]

Next, another embodiment of the method for firing a beta-alumina tube according to the present invention will be described with reference to FIGS.

First, in the second embodiment shown in FIGS. 4 and 5, the firing container 4 is formed in a closed cylindrical shape. A plurality of gap forming members 7 made of the same material as in the first embodiment are interposed between the lower opening edge of the firing container 4 and the firing table 1 as a lid. In the second embodiment,
The opening is constituted by the lower opening edge of the firing container 4.
I have.

Therefore, also in the second embodiment, the first
As in the case of the embodiment, the molded product 3 is heated to a predetermined temperature of 70%.
During heating to 0 to 1000 ° C., decomposed gas is released from the gap between the lower opening edge of the baking container 4 and the baking table 1 to perform degreasing. Thereafter, when the heating temperature exceeds 1 000 ° C., the gap formation member 7 disappears completely decomposed combustion gap between the lower end opening edge and Shodai 1 of firing vessel 4 is sealed. Then, by heating the molded article 3 at a high temperature of 1600 ° C. in this state, sodium
The main firing of the molded article 3 is performed in an atmosphere in which scattering is prevented .

Next, in a third embodiment shown in FIG.
In a configuration substantially similar to that of the first embodiment described above, a plurality of recesses 10 are formed on the upper surface of the closing plate 5. And
The gap forming material 7 is accommodated in the recess 10, whereby a gap is formed between the closing plate 5 and the upper lid 8.

In this embodiment, the gap forming material 7 is formed of a non-reactive material such as aluminum hydroxide, spinel (magnesium aluminum oxide), and magnesium oxide. When the gap forming material 7 made of aluminum hydroxide or the like is heated to a predetermined temperature, the gap forming material 7 contracts and sinks into the concave portion 10 so that the gap between the upper lid 8 and the closing plate 5 is closed. I have. Note that this implementation
In the example, the opening is formed by a through hole 6 provided in the closing plate 5.
Has been established.

Therefore, in this embodiment, as in the case of the first embodiment, while the molded article 3 is heated to a predetermined temperature, decomposed gas is released from the gap to perform degreasing. Then, when the heating temperature exceeds a predetermined temperature, the gap is sealed and sodium beta, a component of beta alumina , is sealed.
The main firing of the molded article 3 is performed in an atmosphere in which the scattering of the film is prevented .

The present invention is not limited to the configuration of the above-described embodiment. For example, in the configuration of the second embodiment, the gap forming material 7 made of the same material as that of the third embodiment may be used, Changing the number of interposed portions of the forming material 7,
The configuration of each part may be arbitrarily changed and embodied without departing from the spirit of the present invention, such as by changing the material and thickness of the gap forming member 7.

[0022]

Since the present invention is configured as described above , degreasing and main firing can be continuously performed in one operation process for a molded product of a beta-alumina tube , and mass production is achieved. And between the degreasing and the main firing, the fired product after the degreasing is not cooled, and the fired product after the main firing has cracks, reduced performance, white spots, etc. This provides an excellent effect that the possibility of occurrence of poor appearance can be reliably prevented. In addition, Nat
Baking after degreasing in an atmosphere in which
The excellent effect that the final firing of the product can be performed is achieved.
I do.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a method for firing a beta alumina tube embodying the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a graph showing temperature characteristics in the firing method of this example.

FIG. 4 is a sectional view showing a second embodiment of a method for firing a beta alumina tube embodying the present invention.

FIG. 5 is a sectional view taken along line BB in FIG. 4;

FIG. 6 is a partial sectional view showing a third embodiment of a method for firing a beta alumina tube embodying the present invention.

[Explanation of symbols]

DESCRIPTION OF REFERENCE NUMERALS 1: a baking table as a lid, 3: a molded product of a beta-alumina tube, 4: a baking vessel, 5: a closing plate, 6: a through hole, 7: a gap forming material, 8: an upper lid as a lid.

Claims (2)

(57) [Claims] 1. An opening for accommodating a beta-alumina tube molded article in a firing vessel and communicating between the inside and the outside of the firing vessel.
700 between the edge of the opening and the lid that can close the opening.
Interposed a gap forming material to decompose combusted to 1000 ° C., by heating the whole up to 700 to 1000 ° C. In this state, the opening
The decomposed gas is released from the gap between the edge of the opening and the lid to perform degreasing, and then the whole is heated to 1000 ° C. or higher to decompose and burn the gap forming material, and the gap between the edge of the opening and the lid is removed. The gap is tight
A method for firing a beta-alumina tube, wherein main firing is performed in a sealed state. (2) In a firing vessel with an opening at the top,
The opening of the baking container containing the molded product of the ta alumina tube
Place a closing plate having a through hole and a plurality of recesses on the upper surface,
The gap forming material is accommodated in the recess and the upper lid is placed.
To form a gap between the closing plate and the top lid.
Heat the body and release decomposed gas from the gap to degrease
When the heating temperature exceeds a predetermined temperature, the gap forming material
The gap is closed by shrinkage, and the inside of the firing vessel is sealed.
Beta-alumina characterized by performing main firing in a heated state
Tube firing method.