JPH0526841A - Sodium/sulfur sensor - Google Patents

Abstract

PURPOSE:To provide a sodium/sulfur sensor responding to both of sodium and sulfur, capable of discriminating between sodium and sulfur on the basis of the polarity of generated electromotive force and detecting the degree of leakage or leak place of molten sodium or molten sulfur in the state arranged in a sodium-sulfur battery or a fast neutron breeder reactor. CONSTITUTION:A sodium/sulfur sensor contains a sodium ion conductive solid electrolyte 1 and the detection electrode 3 formed in contact with one end part 1a of the sodium ion conductive solid electrolyte 1 and further contains the oxygen ion conductive solid electrolyte 2 arranged so that one end part 2a thereof is bonded to the other end part 1b of the sodium ion conductive solid electrolyte 1 and the reference electrode 4 formed in contact with the other end part 2b of the oxygen ion conductive solid electrolyte 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a sodium / sulfur sensor.

[0002]

2. Description of the Related Art A sodium-sulfur battery has a structure in which molten sodium (cathode active material) and molten sulfur (anode active material) are separated by a partition wall of a sodium ion (Na ⁺ ) conductive solid electrolyte such as β ″ -alumina. The secondary battery is usually charged and discharged at a temperature of 300 to 350 ° C.

Since this battery can store a relatively large amount of electric power when the unit batteries are integrated, its use as a means for storing electric power that can replace pumped-storage power generation or as a power source for electric vehicles and the like is being considered. ing. However, if charging and discharging of this battery is repeated over a long period of time, cracks and peeling between members occur in the heat-pressure welded parts of the members that make up the unit battery, the welded parts of the cathode, etc. May be leaked to.

Therefore, in the case where the unit battery is damaged and molten sodium or molten sulfur leaks out of the battery during the repeated charging / discharging process, this is immediately detected and the unit battery is repaired. It is necessary to prevent the entire battery from being destroyed in advance. However, to date, sodium-sulfur batteries have no means for detecting leakage with respect to molten sodium, and a galvanic SO _x sensor has been tried with respect to molten sulfur, but there is a problem in reliability. There is.

On the other hand, in the fast neutron breeder reactor, molten sodium is used as a coolant in order to remove the high heat generated by the conversion of uranium into plutonium. From this fast neutron breeder reactor, if for some reason the molten sodium leaks out of the reactor even in trace amounts,
Since a serious accident will occur, it will be necessary to monitor the leakage of molten sodium.

Therefore, at present, the fast breeder reactor "Monju" which is experimentally operated in Japan is equipped with a sodium ionization type detector and a radiation ionization type detector (RID). However, none of these detectors described above is a means for detecting leaked sodium, which is large-sized and expensive, and is simple and highly sensitive. Therefore, even a small amount of leaked sodium can be detected with high sensitivity,
Moreover, there is an increasing demand for detectors that are small and inexpensive and require little maintenance and management.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sodium / sulfur sensor which is sensitive to both sodium and sulfur, has a small shape, and can be manufactured at low cost. is there.

[0008]

In order to achieve the above object, in the present invention, a sodium ion (Na ⁺ ) conductive solid electrolyte is contacted with one end of the Na ⁺ conductive solid electrolyte. The formed sensing electrode, the oxygen ion (O ²⁻ ) conductive solid electrolyte disposed by bonding one end to the other end of the Na ⁺ conductive solid electrolyte, and the O ² -conductive material. And a sulfur sensor, which comprises a reference electrode formed in contact with the other end of the organic solid electrolyte.

[0009]

Operation The sodium / sulfur sensor of the present invention has about 200
Used in the temperature range from ℃ to about 900 ℃. When this sensor is placed in an atmosphere of sodium or sulfur in which oxygen coexists, an electromotive force is generated between the detection electrode and the reference electrode in the above temperature range. If the temperature is below about 200 ° C, Na
⁺ The impedances of the conductive solid electrolyte and the O ² -conductive solid electrolyte increase, and the measurement accuracy of the electromotive force deteriorates. Also, when the temperature is higher than about 900 ℃, mainly gold (A
The sensing electrode and the reference electrode configured in u) change over time, and a stable electromotive force cannot be obtained, and the measurement accuracy thereof also deteriorates.

This sodium / sulfur sensor is considered to operate as follows. First, leakage of sodium is detected as follows. The leaking metallic sodium reacts with oxygen in the atmosphere to become particulate sodium oxide (Na ₂ O), which adheres to the detection electrode. As a result, on the sensing electrode side, an electrode reaction represented by the following formula: Na ₂ O-→ 2Na ⁺ + 2e ⁻ +1/2 O ₂ (1) occurs.

On the other hand, on the side of the reference electrode, an electrode reaction represented by the following formula: 2Na ⁺ + 2e ⁻ +1/2 O _2- → Na ₂ O (2) occurs. Since the oxygen partial pressure is the same on both the detection electrode side and the reference electrode side, the overall reaction in this sensor is expressed by the following formula: Na ₂ O (detection electrode side)-→ Na ₂ O (reference electrode side) ) ……… It will be represented by (3).

Now, let the activity of Na ₂ O on the sensing electrode side be a ₁ ,
When the activity of Na ₂ O on the reference electrode side is represented by a ₂ , (3)
The equilibrium constant K ₁ in the equilibrium reaction represented by the equation is represented by the following equation: K ₁ = a ₂ / a ₁ (4) Therefore, based on the equation of change in free energy, the electromotive force E ₁ of this sensor becomes the following equation: E ₁ = E ₀ − (RT / 2F) ln (a ₂ / a ₁ ) ... (5) Here, E ₀ is a standard electromotive force, R is a gas constant, T
Represents absolute temperature, and F represents Faraday constant.

Here, when metallic sodium is leaking, in the above equation (5), a ₁ increases and a ₂ increases.
Holds a constant value, so that a ₁ > a ₂ . Therefore, E ₁ > 0. That is, when metallic sodium is leaking, a positive electromotive force is generated in the sensor of the present invention.

On the other hand, the molten sulfur is detected as follows. The leaked molten sulfur reacts with oxygen in the atmosphere to form gaseous sulfur oxide (SO ₃ ), which adheres to the detection electrode and produces Na ₂ SO ₄ . As a result, the detection electrode side has the _{formula: Na 2 SO 4 ── → SO} 3 + 2Na + + 2e - +1/2 O 2 ......... (6) electrode reaction to occur represented by.

On the other hand, on the side of the reference electrode, the electrode reaction represented by the equation (2) occurs. Since the oxygen partial pressure is the same on both the sensing electrode side and the reference electrode side, the overall reaction in this sensor is expressed by the following formula: Na ₂ SO ₄ ─ → Na ₂ O + SO ₃ ……… (7) Will be represented.

The equilibrium constant of the equilibrium reaction in Eq.
₂ , the activity of Na ₂ SO ₄ on the sensing electrode side is a ₃ , SO
_When the gas partial pressure of ₃ is P, K ₂ is represented by the following equation: K ₂ = a ₂ · P / a ₃ (8) Therefore, the electromotive force E ₂ of this sensor is
The following formula: E ₂ = E ₀ − (RT / 2F) ln (a ₂ · P / a ₃ ) ... (9)

Here, since a ₃ can be regarded as 1, when molten sulfur leaks, P increases in the equation (9),
Since a ₂ and a ₃ maintain a constant value, E ₂ becomes E ₂ <
It becomes 0. That is, when molten sulfur is leaking, a negative electromotive force is generated in the sensor of the present invention.

As described above, the sensor of the present invention is sensitive to both molten sodium and molten sulfur, and depending on the polarity of the electromotive force, molten sodium (positive electromotive force) and molten sulfur (negative electromotive force). ) Can be identified. And,
The degree of leakage is detected as the magnitude of electromotive force based on the equations (5) and (9), and can be measured by a voltmeter with an analog display or a digital display.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Each embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a side view showing the sodium / sulfur sensor of the first embodiment. In the case of this sensor, the sensing electrode 3 is formed by contacting one end 1a of the Na ⁺ conductive solid electrolyte 1 having a cylindrical shape, and
At the other end 1b of the Na ⁺ conductive solid electrolyte 1, one end ^{2 of} the O ² -conductive solid electrolyte ² having the same cylindrical shape is formed.
a is joined and arranged, and the reference electrode 4 is formed in contact with the other end 2b of the O ² -conductive solid electrolyte 2.
The lead wires 3a and 4a are attached to the detection electrode 3 and the reference electrode 4, respectively.

In this case, the shape of the Na ⁺ conductive solid electrolyte 1 may be a prismatic shape having a polygonal cross section, or may be a disc shape or a square plate shape. The Na ⁺ conductive solid electrolyte 1 having such a shape is obtained by molding a predetermined raw material powder,
It can be manufactured by sintering the obtained molded body and then cutting the sintered body into a shape described above with a processing machine such as a diamond cutter or a lathe.

Also, for the O ² -conductive solid electrolyte 3, a predetermined raw material powder is molded, the obtained molded body is sintered, and then the sintered body is processed by a processing machine such as a diamond cutter or a lathe. It can be manufactured by cutting it into the above shape. Examples of the Na ⁺ conductive solid electrolyte include the following. NASICON represented by the following formula: Na _{1 + x} Zr ₂ SiP _3-x O ₁₂ (0 ≦ x ≦ 3); β− represented by the following formula: Na ₂ O · xAl ₂ O ₃ (5 ≦ x ≦ 11) Alumina; The following formula: Na _{1 + x} M _x Al _11-x O ₁₇ (M is monovalent cation Li ⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , C
represents a divalent cation of o ²⁺ , Ni ²⁺ , Cu ²⁺ , and 0 ≦ x ≦
Β) -alumina represented by 2); the following formula: Na _{1 + x} Zr _2-x M _x P ₃ O ₁₂ (M is Fe ³⁺ ,
In ³⁺ , Sc ³⁺ , Y ³⁺ , Sm ³⁺ , Eu ³⁺ , Gd ³⁺ , Tb
³⁺ , Dy ³⁺ , Ho ³⁺ , Er ³⁺ , Tm ³⁺ , Yb ³⁺ , Lu ³⁺
Represented by the formula: 0 ≦ x ≦ 2); the following formula: Na _{1 + 2x} Zr _2-x M _x P ₃ O ₁₂ (M is Mg ²⁺ ,
2 of Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺
A compound that represents a valent cation and is represented by 0 ≦ x ≦ 2; the following formula: NaMSi ₄ O ₁₂ (M is Fe ³⁺ , In ³⁺ , S)
c ³⁺ , Y ³⁺ , Sm ³⁺ , Eu ³⁺ , Gd ³⁺ , Tb ³⁺ , D
y ³⁺ , Ho ³⁺ , Er ³⁺ , Tm ³⁺ , Yb ³⁺ , Lu ³⁺ trivalent cation), and NMS-NASICON
Compound represented by the following formula: Na ₃ MSi ₄ O ₁₂ (M is Fe ³⁺ , In ³⁺ , S
c ³⁺ , Y ³⁺ , Sm ³⁺ , Eu ³⁺ , Gd ³⁺ , Tb ³⁺ , D
y ³⁺ , Ho ³⁺ , Er ³⁺ , Tm ³⁺ , Yb ³⁺ , represents a trivalent cation of Lu ³⁺ ); a compound represented by the following formula: Na _1.7 Al _1.7 Si _0.3 O ₄ or Formula: Na ₃
A compound represented by ScP ₃ O ₁₂ ; and the like.

Further, Japanese Patent Application Laid-Open No. 57-135714,
JP-A-59-213609, European Patent Publication No. 006
7 274 No. etc. and Na ⁺ conducting solid electrolyte which is proposed in Japanese, the following _{equation: Na 2 O · Al 2 O} 3 · xSiO 2 ( wherein, x is 2, 4, 6, 8) a compound represented by Also 200
Since the conductivity of Na ⁺ is relatively high, that is, the internal impedance is low at a relatively low temperature of ˜700 ° C., these can also be used as the Na ⁺ conductive solid electrolyte according to the present invention. Furthermore, the following formulas: (PEO) xNaSCN, (PPO) x
NaSCN, (PEO) xNaI, (PPO) xNa
_{I, (PEO) xNaCF 3 SO} 3, (PPO) xNaC
F ₃ SO ₃ (wherein PEO is (CH ₂ CH ₂ O) _n , PPO is (C
H ₂ CH (CH ₃ ) O) _n , where x represents the number of oxygen atoms per cation), the conductivity of Na ⁺ at low temperature is also high. ⁺
It can be used as a conductive solid electrolyte.

Since the Na ⁺ conductive solid electrolytes have slightly different Na ⁺ concentrations and internal impedances, the electromotive force and the response speed of the obtained sensors also differ. However, regarding this point, for example, regarding electromotive force, the difference in performance as a sensor can be eliminated by creating a calibration curve specific to each sensor in advance, and the response speed is Since all the compounds show high Na ⁺ conductivity, the performance as a sensor will not be impaired in practical use.

Examples of the O ² -conductive solid electrolyte include the followings. The following formula: (MO ₂ ) _1-x (R _y O _z ) _x (M is Zr ⁴⁺ , T
h ⁴⁺ , Hf ⁴⁺ , Ce ⁴⁺ represents a tetravalent cation, and R is
Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Co ²⁺ , Ni ²⁺ , C
u ²⁺ divalent cation or Fe ³⁺ , In ³⁺ , Sc ³⁺ ,
Y ³⁺ , Sm ³⁺ , Eu ³⁺ , Gd ³⁺ , Tb ³⁺ , Dy ³⁺ , Ho
³⁺ , Er ³⁺ , Tm ³⁺ , Yb ³⁺ , and Lu ³⁺ trivalent cations, and 0.05 ≦ x ≦ 0.3, and y and z are (R _y O _z ).
A number represented by the formula: (Bi ₂ O ₃ ) _1-x (R _y O _z ) _x (R is M
g ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Co ²⁺ , Ni ²⁺ , Cu
²⁺ , Pb ²⁺ divalent cation, Fe ³⁺ , In ³⁺ , Sc ³⁺ ,
Y ³⁺ , Sm ³⁺ , Eu ³⁺ , Gd ³⁺ , Tb ³⁺ , Dy ³⁺ , Ho
³⁺ , Er ³⁺ , Tm ³⁺ , Yb ³⁺ , a trivalent cation of Lu ³⁺ or W ⁶⁺ , where 0.05 ≦ x ≦ 0.3 and y and z are (R _y O _z A compound represented by the number) which electrically neutralizes);

The sensing electrode 3 formed on one end 1a of the Na ⁺ conductive solid electrolyte 1 and the reference electrode 4 formed on the other end 2b of the O ² -conductive solid electrolyte 3 are
Both are porous gas diffusion electrodes. These electrodes can be formed by a sputtering method, a vapor deposition method, or the like, but a paste containing fine powder of each electrode material is used.
a ⁺ A paste coating pyrolysis method in which one end 1a of the conductive solid electrolyte 1 and the other end 2b of the O ² -conductive solid electrolyte 2 are applied respectively, and then baked and baked at a predetermined temperature. Is easy to operate,
It is preferable because the electrodes can be surely formed.

The material used for forming the detection electrode 3 is
Na ⁺ and oxygen do not form a solid solution even at high temperatures,
Gold (Au) is preferable because it does not easily change over time. The material used for forming the reference electrode 4 may be gold as in the case of the detection electrode, but is a material that does not form a solid solution with the constituent elements of the O ² -conductive solid electrolyte and oxygen even at high temperatures. In addition, platinum (Pt) is a preferable material because it is a material that exerts a catalytic effect on the dissociation reaction of oxygen.

As the material of the reference electrode 4, the following materials, which are known as oxide electrode materials and have a small difference in thermal expansion from the stabilized zirconia, can be used. The following formula: La _1-X Sr _x MO ₃ (M is Co ²⁺ , Mn ²⁺ , F
represents a divalent cations e ^2+, a compound represented by 0 ≦ x <1); the _{formula: La 1-x Sr X M} 1 1-y M 2 y O 3 (M 1 is Mn
^Represents cations such as ²⁺ , Fe ³⁺ , Ca ²⁺ , Mg ²⁺ , M
² represents a cation such as Co ²⁺ , Cr ³⁺ and Al ³⁺ ,
x and y are compounds represented by 0 ≦ x <1 and 0 ≦ y <1), respectively.

Lead wires 3a and 4a are attached to the detection electrode 3 and the reference electrode 4, respectively, from which electromotive force signals at the time of measuring molten sodium and molten sulfur are taken out. These lead wires 3a and 4a are preferably made of the same material as the detection electrode 3 and the reference electrode 4. For example, a gold paste or a platinum paste is used to form these electrodes before or at the same time when both electrodes are formed. It is preferable to mount it fixedly.

In addition, the Na ⁺ conductive solid electrolyte and the O ² -conductive solid electrolyte are bonded to each other after bonding them with a gold paste.
A baking method or a method of fusing a Na ⁺ conductive solid electrolyte having a relatively low melting point may be used. FIG. 2 is a plan view showing another embodiment. In the sodium / sulfur sensor of this embodiment, a thin plate-shaped Na ⁺ conductive solid electrolyte 1 and one end 1a of this Na ⁺ conductive solid electrolyte 1 are contacted on an electrically insulating support substrate 5. A thin plate-shaped O ² -conductive solid electrolyte, which is arranged by joining one end 2a to the other end 1b of the Na ⁺ conductive solid electrolyte 1 formed by 2 and a reference electrode 4 formed in contact with the other end 2b of the O ² -conductive solid electrolyte 2 are integrally formed.

In order to form the thin plate-shaped Na ⁺ conductive solid electrolyte 1 or O ² -conductive solid electrolyte 2 on the support substrate 5, for example, a powder mixing method or a coprecipitation method, a hydrolysis method,
A raw material powder of a predetermined composition synthesized by a wet synthesis method using an alkoxide method, etc., is sufficiently finely pulverized by a pulverizer such as a ball mill, and the obtained fine powder is supported by heat-resistant electrical insulation by screen printing or the like. After patterning on the substrate 5, it is preferable to apply a coating and baking method in which the whole is heated to the sintering temperature of each fine powder and the print pattern of the fine powder is baked on the supporting substrate 5. At this time, by changing the coating amount at the time of patterning, each solid electrolyte can be formed into a thick film or a thin film, in the form of a column or a column of a column or a prism, or in the form of a plate. Can be formed on. In addition, a sintered block of each solid electrolyte is manufactured in advance,
It is also possible to cut a columnar body and a plate body from these blocks and bond them to the supporting substrate 5 with an inorganic adhesive containing alumina as a main component.

For this reason, the supporting substrate 5 needs to have heat resistance sufficient to withstand the sintering temperature of each of the fine powders, and the detection formed on the supporting substrate 5 is required. It must be electrically insulating in order to prevent a short circuit between the electrode 3 and the reference electrode 4. Examples of materials that satisfy such characteristics include alumina, zirconia, silicon nitride, and aluminum nitride. Further, the supporting substrate may be a substrate obtained by coating the surface of another substrate with the above-mentioned material by the coating and baking method, the vapor deposition method, the CVD method, the sputtering method, the plasma spraying method or the like.

In addition to the above-mentioned coating and baking method, a predetermined masking is applied to the support substrate 5, and then a Na ⁺ conductive solid having a predetermined composition is deposited thereon by a vapor deposition method, a CVD method, a sputtering method, a plasma spraying method or the like. It is also possible to form the electrolyte 1 or the O ^2- conductive solid electrolyte 2. The detection electrode 3, the reference electrode 4, the lead wire 3a, and the lead wire 4a are all
It is formed at each location in the same manner as in the first embodiment.

3 and 4 are a plan view and a side view, respectively, showing another embodiment. The sodium / sulfur sensor of this embodiment is of a type in which a heating element is mounted on the sensor itself. As described above, the sensor of the present invention exerts its sensor function in the temperature range of 200 to 900 ° C., but the one equipped with a heating element such as this type can improve the accuracy of temperature control.

In FIG. 3, heating elements 6 are formed in a zigzag pattern on the back surface of the electrically insulating support substrate 5 in the sensor shown in FIG. 2, and heating element lead wires 6a and 6b are attached to the heating elements 6. ing. The heating element 6 can be formed, for example, by patterning a paste prepared by dispersing fine platinum powder in turpentine oil or the like on the back surface of the support substrate 5 by a method such as screen printing, and then baking this. In addition to the above platinum, rhodium, platinum-rhodium alloy, tungsten, nickel-chromium alloy can be used as the material at that time. In addition to the baking method, the back surface of the substrate 5 may be masked and the heating element 6 may be formed by applying a vapor deposition method, a CVD method, a sputtering method, a plasma spraying method, or the like.

[0035]

【Example】

Example 1 The sodium / sulfur sensor shown in FIG. 1 was manufactured as follows. That is, first, Na ₃ PO with a purity of 99.9%
₄ reagent (anhydrous) and ZrSiO ₄ reagent in a molar ratio of 1:
After weighing so as to be 2, both were mixed. The obtained mixed powder was heat-treated at 1147 ° C. for 48 hours to cause a solid-phase reaction to homogenize, and then pulverized by a ball mill for 24 hours. The obtained powder was press-molded into a cylindrical shape with a pressure of 1 ton / cm ² , and the molded body was
It heat-processed at 7 degreeC for 12 hours. Diameter about 2mm, length about 4mm
Thus, a cylindrical NASICON sintered body 1 was obtained.

Next, yttrium oxide (Y ₂ O), which is a special grade reagent, is used.
₃ ) powder and zirconium oxide (ZrO ₂ ) powder of the special grade reagent,
Both were mixed after weighing so that the molar ratio was 8:92. The obtained mixed powder is heated to 1000 ° C in the atmosphere.
After heat treatment for 2 hours to cause a solid-phase reaction to homogenize, homogenization was carried out for 24 hours with a ball mill. The obtained powder was rubber press-molded at a pressure of 1 ton / cm ² , and the molded body was heat-treated at 1750 ° C. for 2 hours.
A sintered block of yttria-stabilized zirconia (hereinafter referred to as YSZ) was obtained. This YSZ block is processed with a diamond cutter and a lathe, and has a diameter of 4 mm and a thickness of 0.
I made a 5mm disc 2.

On one end face of the NASICON sintered body 1, N
ASIC powder is attached, YSZ disk 2 is placed here, and the whole is placed on a ceramic heater at 1350 ° C.
And heat one end 2a of the YSZ disk 2 to N
The one end face 1b of the ASIC sintered body 1 was fused and integrated with each other. Another end 1a of the NASICON sintered body 1
A gold wire 3a having a diameter of 0.2 mm is wound around the outer periphery of the disk, gold paste is applied to the winding part of the gold wire, and a gold wire having a diameter of 0.2 mm is applied to the end surface of the other end 2b of the YSZ disk 2. A wire was attached and a gold paste was applied on the wire. Then, the whole is baked at 700 ° C. for 1 hour to detect the sensing electrode 3 and the reference electrode 4.
Formed.

The obtained sensor was set in the electromotive force measuring system shown in FIG. That is, the sensor 9 was set in the quartz tube 8 placed in the electric furnace 7, and the lead wires 9a and 9b of the sensor were sealed with the seals 8b and connected to the pen recorder 10. In this measurement system, electric furnace 7
Was operated and the temperature in the vicinity of the sensor 9 was maintained at 300 ° C. by controlling the temperature with the thermocouple 11.

In this state, a small sample piece 12 of metallic sodium or sulfur set in the upper branch pipe 8a of the quartz pipe 8.
Was dropped into the quartz tube 8 and burned at the bottom of the tube. At this time, the electromotive force indicated by the sensor 9 was recorded by the pen coder 10. The results are shown in Table 1.

[0040]

[Table 1] Example 2 The Na ⁺ solid electrolyte is the same as the NASICON in Example 1.
Instead of the above, a sensor was manufactured in the same manner as in Example 1 except that β-alumina manufactured by the following method was used.

Reagent grade anhydrous sodium carbonate and purity 9
9.99% aluminum oxide and Na ₂ O: Al ₂ O
Weigh them so as to be 1: 6 (molar ratio) in terms of ₃ and mix them. The resulting mixture is heat treated at 1200 ° C. for 3 hours to cause a solid phase reaction and homogenize, and then a ball mill. The crushing treatment was performed for 24 hours. 1 to 1 of the obtained powder
Rubber press molding with a pressure of n / cm ²
Heat treatment was performed at 00 ° C. for 30 minutes to form a β-alumina block.

For this type of sensor, the electromotive forces for metallic sodium and sulfur were measured under the same conditions as in Example 1. The results are shown in Table 2.

[0043]

[Table 2] Example 3 The sodium / sulfur sensor shown in FIGS. 3 and 4 was manufactured as follows. That is, first, YSZ fine powder manufactured by the method of Example 1 was patterned on the alumina substrate 5 having a purity of 99.9% by a screen printing method, and then the whole was baked at a temperature of 1600 ° C. for 2 hours. A YSZ film having a length of 4 mm, a width of 2 mm and a thickness of 0.5 mm was formed.

Next, the NAS manufactured by the method of Example 1
The fine powder of ICON was patterned on the alumina substrate 5 by a screen printing method so as to be in contact with the YSZ film, and then the whole was baked at a temperature of 1247 ° C. for 12 hours to form a fine powder on the alumina substrate 5. Length 4 mm, width 2 mm, thickness 0.
A 5 mm NASICON film was formed. A platinum paste was patterned on the back surface of the alumina substrate 5 by a screen printing method, and then the whole body was heat-treated at 1000 ° C. for 1 hour to form the heating element 6. At this time, the platinum wires 6a and 6b, which are the lead wires of the heating element 6, were also baked together with the platinum paste. After that, a gold wire with a diameter of 0.2 mm is attached to one end of the NASICON film and the other end of the YSZ film, and then gold paste is applied on the gold wire.
After drying, the whole is baked at 700 ° C for 1 hour,
A sensing electrode and a reference electrode were formed.

This sensor was set in the measurement system shown in FIG. In this measuring system, the lead wires 6a and 6b of the heating element mounted on the sensor 9 are connected to the temperature control device 13 so that the temperature of the sensor 9 can be controlled by itself. The electric furnace 10 was not operated, the heating element mounted in the sensor was operated to control the sensor temperature to 300 ° C., and the electromotive force for metallic sodium and sulfur was measured. The results are shown in Table 3.

[0046]

[Table 3]

[0047]

As is apparent from the above description, the sensor of the present invention is sensitive to both sodium and sulfur in the environment. The polarity of the electromotive force makes it possible to identify whether it is sodium or sulfur that is being measured. Moreover, the electromotive force value measured by the sensor of the present invention is stable and highly accurate. Since the shape is small and the manufacturing is simple, it has a high industrial value as a general-purpose sodium / sulfur sensor.

The sodium / sulfur sensor of the present invention is housed in a closed container of a sodium-sulfur battery and used as a sensor for detecting molten sodium or molten sulfur leaked from the battery, or a fast neutron breeder reactor. By arranging a plurality of them in a container and assembling a sensing network, the sensor can be used as a sensor for detecting the leakage location of molten sodium and the degree of leakage.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of the present invention.

FIG. 2 is a plan view showing a second embodiment of the present invention.

FIG. 3 is a plan view showing a third embodiment of the present invention.

FIG. 4 is a side view showing a third embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing an electromotive force measurement system.

FIG. 6 is a schematic configuration diagram showing another electromotive force measurement system.

[Explanation of symbols]

1 Sodium Ion Conducting Solid Electrolyte 1a One End of Sodium Ion Conducting Solid Electrolyte 1b Other End of Sodium Ion Conducting Solid Electrolyte 1 2 Oxygen Ion Conducting Solid Electrolyte 2a One of Oxygen Ion Conducting Solid Electrolyte 2 End 2b of the oxygen ion conductive solid electrolyte 2 the other end 3 sensing electrode 3a lead wire 4 reference electrode 4a lead wire 5 supporting substrate 6 heating element 6a, 6b heating element 6 lead wire 7 electric furnace 8 quartz tube 8a Upper branch pipe 8b Seal 9 Sodium / sulfur sensor 9a, 9b Lead wire 10 Pen recorder 11 Thermocouple 12 Sample piece 13 Temperature controller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kuwajima 1-1-1, Sonoyama, Otsu-shi, Shiga Toray Co., Ltd. Shiga Plant No. Tokyo Electric Power Co., Inc.

Claims (1)

Claims: 1. A sodium ion conductive solid electrolyte;
A sensing electrode formed in contact with one end of the sodium ion conductive solid electrolyte, and oxygen ions arranged by joining one end to the other end of the sodium ion conductive solid electrolyte. A sodium / sulfur sensor comprising a conductive solid electrolyte and a reference electrode formed in contact with the other end of the oxygen ion conductive solid electrolyte.