JPH0646984Y2 - Bottomed ceramic sintered tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to the structure of a bottomed ceramic sintered tube having one end closed, and particularly β- for sodium (Na) -sulfur (S) secondary batteries. The present invention relates to a shape of a bottomed ceramic sintered tube suitable for reducing the yield during firing of a solid electrolyte tube such as alumina [Na ₂ O · χ Al ₂ O ₃ (5 ≦ χ ≦ 11)].

[Prior Art] Conventionally, a β-alumina-based solid electrolyte tube (ceramic bottomed ceramic tube) with one end closed is manufactured by AMTEC (Alkali Metal).
It is widely used in applications such as solid electrolyte tubes with NA ⁺ ion conductivity for thermoelectric converters called Thermo-Electric Converters, solid electrolyte tubes for SOx sensors, solid electrolyte tubes for sodium-sulfur secondary batteries, and crucibles. ing.

As shown in FIGS. 3 to 5, the bottomed ceramic sintered tube has a hemispherical portion 500 having a radius R (FIG. 3) and a round bottom 600 having a radius Rχ (R ≠ Rχ) (fourth portion). (Fig.) Or a flat-bottomed cylinder 700 (Fig. 5), and then fired.

The radius of curvature of the inner circumference of the connecting portion from the pipe wall to the bottom wall is B,
The diameter of the inner diameter is 2A, the diameter of the circular plane formed on the outer wall of the bottom is
2D, the outer diameter of the pipe is 2C, the B / A is 1 and the D / C is 0, as shown in Fig. 3 (bottom hemisphere).

[Problems to be solved by the invention] However, when the bottom of the bottomed ceramic sintered tube has a hemispherical shape of 500 or a round bottom of 600, it is necessary to invert or lay it down during firing, resulting in poor warpage and poor mouth end deformation. Prone to
Further, in the case of the flat-bottomed cylinder 700, cracks, chips, and peeling defects are likely to occur during molding, and defects such as cracks due to a decrease in thermal shock resistance are likely to occur even during firing, resulting in a poor yield rate.

In particular, when the bottomed ceramic sintered tube is a solid electrolyte tube, the tube wall and the bottom wall are thinly formed so that specific ions can easily move in the solid, and problems are likely to occur. Was being pressed.

An object of the present invention is to provide a bottomed ceramic sinter tube that is designed to reduce cracking, chipping, peeling failure rate during molding and firing, and to improve thermal shock resistance.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configurations.

(1) In a cylindrical bottomed ceramic sintered tube in which one end is closed and the other end is open, a circular flat surface is formed on the bottom outer wall, and the inner bottom is hemispherical, the bottom wall thickness is Greater than the wall thickness of the side surface portion, and with the thickness of the connecting portion from the bottom portion to the side surface portion of the pipe set to be larger than the wall thickness of the bottom portion, the diameter 2D of the plane with respect to the diameter 2C of the outer diameter of the pipe. 1 /
It was set to 3 ≦ D / C ≦ 11/12.

(2) The bottomed ceramic sintered tube having the configuration of (1) above is a β-alumina-based solid electrolyte tube.

[Operation and Effect of Invention] The bottomed ceramic sintered tube of the present invention has the following operation and effects.

<Effect of Claim 1> A circular flat surface is formed on the outer wall of the bottom. For this reason, it becomes possible to perform firing of the bottomed ceramic sintered tube in an upright state, and it is possible to reduce warp defects and other end (mouth end) deformation defects during firing.

Since the wall thickness of the bottom portion is larger than the wall thickness of the pipe side surface portion, the influence of the load due to the gravity generated at the time of contraction during firing can be reduced, and the deformation of the bottom portion can be prevented. Further, since the wall thickness of the connecting portion is set larger than the wall thickness of the bottom portion, it is possible to prevent the deformation of the connecting portion due to the shearing force applied by the weight of the pipe side surface portion and the reaction force of the bottom portion.

The inner bottom has a hemispherical shape and a circular flat surface is formed on the outer wall of the bottom, and the diameter 2D of the flat surface is 1/3 ≤ D / C for the diameter 2C of the outer diameter of the pipe.
It is set to ≦ 11/12. For this reason, the change in shape from the side surface portion to the bottom portion of the pipe becomes gentle, and the thermal shock resistance can be improved. In addition, the pressure distribution generated during molding becomes constant, and a molded product having a uniform density can be obtained, and the defect rate such as cracks, chips, and peeling during molding or firing can be reduced.

The reason for the numerical limitation is that if D / C <1/3, it becomes unstable during upright firing, so warp defects are likely to occur, and if D / C> 11/12, cracks and chips occur during molding and firing. This is because peeling easily occurs and the thermal shock resistance is reduced.

<Effects of Claim 2> When the configuration of Claim 1 is applied to a β-alumina-based solid electrolyte tube having a thin tube wall and a bottom wall, the above-mentioned effect is remarkably exerted.

[Embodiment] Next, an embodiment of the present invention (corresponding to claims 1 and 2) will be described below.
It will be described with reference to FIG. 2 and FIG.

A sodium-sulfur secondary battery is composed of molten sulfur or molten Na ₂ Sχ as the positive electrode active material, molten sodium as the negative electrode active material, and β- which is selectively conductive to sodium ions in the electrolyte. using an alumina-based solid electrolyte tube, the cell was operated at about 30 ° C., the reaction _{is, 2Na + χS → Na 2 Sχ} ( _{discharge) 2Na + χS ← Na 2 Sχ} ( charging), and the open circuit voltage is 2.08V, the energy 200Whkg ^{- I} have taken out about ¹ .

The β-alumina solid electrolyte tube E of the present invention is a cylindrical β
It is made of a fired body of alumina and has one end closed to form a bottom portion 1 and the other end opened to form a mouth end portion 2. here,
The respective dimensions before firing are the inner radius of curvature B of the connecting portion 3 from the pipe wall 21 to the bottom wall 11, the inner diameter of 2A, and the outer diameter of the pipe.
2C, the diameter of the circular plane 12 formed on the outer wall of the bottom wall 11 is 2D
I am trying.

In the bottom portion 1, the bottom wall 11 becomes a part of an arc having a dimension of the inner circumference curvature radius B of the connecting portion 3, and the thickness of the bottom portion 1 is formed to be slightly thicker than the thickness of the mouth end portion 2.

The mouth end 2 has an opening 22 at the tip.

The connecting portion 3 has an inner radius of curvature B and an inner diameter of the bottom portion 1.
The relationship with 2A is B / A = 1, and the relationship D / C between the diameter 2D of the flat surface 12 of the bottom 1 and the diameter 2C of the outer diameter of the pipe at the mouth end 2 is 1/2 in this embodiment. And 2/3 respectively. The wall thickness of the connecting portion 3 is formed to be slightly thicker than the wall thickness of the bottom portion 1.

In this example, an unsintered β-alumina-based solid electrolyte tube E was used.
Block the opening 22 and embed it in a powder having a similar composition.
Firing was performed at a temperature around 1600 ° C. for 30 minutes, and 20 pieces each, 160 pieces in total were manufactured for each test shown in Tables 1 to 4. In addition,
After firing, the volume of the β-alumina-based solid electrolyte tube E becomes about 1/2 due to contraction, but the relationship between B / A and D / C does not change.

<Table 1> The results of the warp defect during firing, the number of defects at the mouth end deformation (the number of lines), and the defect rate (%) are shown. For comparison, the results of the conventional bottom hemisphere (Fig. 3 product) are shown. 20 pieces each are manufactured by the above method (the same applies up to Table 4 below)
did.

In the β-alumina-based solid electrolyte tube E of the present example, the defective rate of warp failure and mouth end deformation during firing was reduced.

On the other hand, the bottom hemispherical type (conventional example) has a high defect rate (9
Book). This is because there is no flat surface on the outside of the bottom, so it cannot stand upright during firing, and the crucible is placed against the crucible, which is believed to cause warpage and deformation due to shrinkage.

<Table 2> The results of the number of cracks, chips and peeling during molding and the defect rate are shown.

In the case of this example, the defective rate of cracks, chips, and peeling during molding was reduced.

The flat-bottomed cylinder (conventional example) showed a high defect rate (16 pieces). It is considered that this is because the shape is drastically changed from the side surface portion to the bottom portion, so that it is difficult to uniformly apply pressure during molding, and cracks, chips, and peeling are likely to occur.

<Table 3> The results of the number of cracks, chips and peeling when firing the molded body and the defect rate are shown.

In the case of this example, the defective rate of cracking, chipping and peeling during firing was reduced.

The flat-bottomed cylinder (conventional example) showed a high defect rate (11 pieces). This was a shape that was difficult to pressurize uniformly during molding, so although it did not become defective during molding, residual stress remains inside and cracks, chips, and peeling easily occur during the shrinking process during firing. It seems to be.

<Table 4> The results of the 800 ° C thermal shock test performed on the fired tube are shown below.

The material of this example has improved thermal shock resistance.

The flat-bottomed cylinder (conventional example) showed a high failure rate (15 pieces). It is considered that, like cracking, chipping, and peeling failure during molding and firing, a rapid change in shape from the side surface portion to the bottom portion causes stress concentration due to thermal shock and is easily broken.

The present invention includes the following embodiments in addition to the above embodiments.

For the ceramic sintered tube, in the case of a solid electrolyte, the following may be used depending on the type of ion movement during fixation.

^{_{H + ...... H 3 PW 12 0}} 40 · 29H 2 O, HUO 2 PO 2 · 4H 2 O Li + ... Li 3 N, _{Rishikon; Li 14 Zn (GeO 4)} 4 Na + ... NASICON; Na ₃ Zr ₂ Si ₂ PO ₁₂ Cu ⁺ … 7CuBr ・ C ₆ H ₁₂ N ₄ CH ₂ Br, RbCu ₄ Cl ₃ I ₂ Ag ⁺ … RbAg ₄ I ₅ , Ag ₆ I ₄ (WO ₄ ) K ⁺ …… K ₂ O ・ 5.2Fe ₂ O ₃・ 0.8 ZnO Tl ⁺ … Tl _1.8 Ta _1.8 W _0.2 O ₆・ nH ₂ O Sr ⁺ … Sr−β ″ -alumina Cd ⁺⁺ … Cd−β ″ -alumina Ba ⁺⁺ … Ba−β ″ -alumina ^{_{F - ...... PbF 2 Cl - ...}} PbCl 2, SnCl 2 O - ...... stabilized _{zirconia; (ZrO 2) 0.9 (Y} 2 O 3) 0.1 or (B
iO ₃ ) _0.75 (Y ₂ O ₃ ) _0.25 b. The ceramic material of the ceramic sintered tube is α-alumina, beryllia (BeO), calcia (CaO), magnesia (MgO), quartz glass (SiO ₂ ), thoria ( ThO ₂ ), titania (TiO ₂ ), urania (UO ₂ ), zirconia, (Zr
O ₂ ), mullite (3Al ₂ O ₃・ 2SiO ₂ ), spinel (MgO ・ Al ₂
O ₃ ), forsterite (2MgO ・ SiO ₂ ), zircon (Zr
O ₂ · SiO ₂ ) or the like may be used.

[Brief description of drawings]

FIG. 1 is a lateral sectional view of an embodiment of the β-alumina-based solid electrolyte tube of the present invention, and FIG. 2 is a bottom view thereof. 3 to 5 are transverse sectional views of a conventional β-alumina-based solid electrolyte tube. In the figure, E ... β-alumina-based solid electrolyte tube (bottomed ceramic sintered tube), 1 ... bottom part (one end), 2 ... mouth end part (other end),
2C… Outer diameter of pipe, 2D… Plane diameter, 3… Connection, 11
... bottom wall, 12 ... plane, 21 ... tube wall

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kozo Soga 14-18 Takatsuji-cho, Mizuho-ku, Aichi Prefecture Nihon Special Ceramics Co., Ltd. (72) Hisao Hirota 14-takatsuji-cho, Mizuho-ku, Aichi No.18 Nihon Special Ceramics Co., Ltd. (56) References

Claims (2)

[Scope of utility model registration request] 1. One end is closed and the other end is open,
In a cylindrical bottomed ceramic sintered tube having a circular flat surface on the bottom and outer walls and a hemispherical inner bottom, the thickness of the bottom is greater than the thickness of the side of the tube, and The wall thickness of the connecting part to the side surface is set larger than the wall thickness of the bottom part, and the diameter 2D of the plane is 1/3 ≤ D / C ≤ the outer diameter 2C of the pipe.
A bottomed ceramic sintered tube characterized by being set to 11/12. 2. The bottomed ceramic sintered tube according to claim 1, wherein the bottomed ceramic sintered tube is a β-alumina-based solid electrolyte tube.