JPH0829380A - Sensor for measuring quantity of hydrogen dissolved in molten metal - Google Patents

Abstract

PURPOSE:To provide a sensor for measuring quantity of hydrogen dissolved in molten metal capable of preventing decreasing of the life of a sensor element and deterioration of measurement accuracy due to a floating material on the surface of the molten metal and of avoiding damage due to heat shock. CONSTITUTION:A solid electrolyte member 1 is formed to be a pipe of which one end is closed with a proton-conductive ceramics or a glass. Porous electrodes 2a, 2b are provided on the outer and inner surfaces of the solid electrolyte member 1 as a measuring electrode and a reference electrode, respectively. A sleeve 3 is fitted to the opening side of the solid electrolyte member 1. The sleeve 3 is filled with ceramic powder 12. A ceramic pipe 4 is fitted to the closed side of the solid electrolyte member 1. A ceramics coating film 14 and a metallic coating film 13 are applied on the outer surfaces of the pipe 4 and sleeve 3. The metallic coating film 13 covers a tip portion of the sleeve 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for measuring the amount of hydrogen dissolved in molten metal, which uses a solid electrolyte member having proton conductivity to measure the hydrogen concentration in the molten metal.

[0002]

2. Description of the Related Art Conventionally, there have been the following methods for measuring the hydrogen concentration in molten metal.

Initial Bubble Method First, molten metal is sampled, and the molten metal is placed in a measuring chamber containing a heater. Then, the amount of hydrogen is calculated from the temperature and pressure inside the measurement chamber when the bubbles are first generated from the surface of the molten metal by reducing the pressure inside the measurement chamber.

Decompression solidification method The sampled molten metal is solidified under reduced pressure, the state of bubbles in the sample after solidification is observed, comparison with the specific gravity of the standard sample, and the amount of hydrogen gas is determined from the state of bubbles in the cross section of the sample.

Partial pressure equilibrium method A small amount of an inert gas is injected into a molten metal and circulated, and when the hydrogen gas diffuses into the inert gas and reaches an equilibrium state, the inert gas is recovered to obtain a thermal conductivity. The hydrogen concentration in the inert gas is analyzed by a gas detector, gas chromatograph, mass spectrometer or the like, and the hydrogen concentration in the molten metal is determined from the analysis result and the temperature of the molten metal.

Vacuum Extraction Method A sample obtained by sampling molten metal, quenching and solidifying is heated in a vacuum, and the amount of hydrogen gas released from the sample is measured by a thermal conductivity type detector, gas chromatograph, mass spectrometer. Alternatively, quantify using an infrared analyzer or the like.

However, these conventional methods for measuring the hydrogen concentration in molten metal have the drawbacks that it takes a long time for measurement, that the measurement accuracy is poor, and that expensive measuring devices are required. Neither is suitable for measuring the amount of dissolved hydrogen in actual casting sites.

As a measuring method developed to solve these problems, there is a gas concentration battery type hydrogen sensor using a proton conductive solid electrolyte. In this type of sensor, a reference electrode made of a porous conductor and a reference substance serving as a reference for the electromotive force of the concentration battery are arranged on one side of a member made of a solid electrolyte having proton conductivity and in contact with the reference electrode. The other surface (measurement electrode) is brought into contact with the molten metal, and the electromotive force generated by the difference in hydrogen activity between the hydrogen partial pressure on the reference electrode side and the hydrogen concentration in the molten metal causes It detects the hydrogen concentration. This sensor has an advantage that it can directly measure the hydrogen concentration in the molten metal, has a high response speed, and can obtain high accuracy.

[0009]

However, the sensor using the conventional proton conductive solid electrolyte described above is
Since the surface of the measuring electrode is oxidized by the contact with the molten metal, it is difficult to measure for a long time. Further, in the conventional sensor, when the sensor is immersed in the molten metal, floating substances such as oxides, non-oxides, flux for molten metal treatment and slag floating on the surface of the molten metal are deposited on the tip of the sensor. May adhere to the measurement electrode and corrode the surface of the measurement electrode, or an insulating film may be formed between the measurement electrode and the molten metal to make measurement impossible. Furthermore, there is a problem in that the transfer of hydrogen between the sensor and the molten metal is hindered by the diffusion-controlling film made of the oxide or non-oxide attached to the tip of the sensor, and the response characteristic of the sensor deteriorates. .

A heat-resistant ceramic sleeve is attached to the solid electrolyte member, and the gas (gas phase) present in the space inside the sleeve is interposed between the molten metal and the measuring electrode so that the molten metal and the measuring electrode are directly connected to each other. It is possible to prevent them from coming into contact with each other, but in this case as well, when the sensor is immersed in the molten metal, the oxide or non-oxide film attached to the sleeve tip becomes the diffusion-controlling film and becomes the molten metal and the sensor. There is a problem that the transfer characteristics of the hydrogen are hindered and the response characteristics of the sensor deteriorate. Further, in this case, since the wettability of the ceramic sleeve to the molten metal is poor, air from the outside air diffuses at the interface between the sleeve and the molten metal, enters the sleeve, and reacts with hydrogen in the sleeve, There is also a problem that the measured value of the hydrogen concentration becomes lower than the actual hydrogen concentration. Furthermore, if a ceramic member is used in a portion that comes into direct contact with the molten metal, the ceramic member may be damaged by heat shock.

The present invention has been made in view of the above problems, and it is possible to avoid corrosion of a measuring electrode, formation of an insulating film, and deterioration of response characteristics due to suspended matter on the surface of molten metal.
Another object of the present invention is to provide a sensor for measuring the amount of hydrogen dissolved in a molten metal, which can prevent a decrease in measurement accuracy due to diffusion of air at the interface between the sensor and the molten metal and can prevent damage to the sensor due to heat shock. And

[0012]

A sensor for measuring the amount of dissolved hydrogen in molten metal according to the present invention is provided with a solid electrolyte member formed of a solid electrolyte material having proton conductivity and provided on the solid electrolyte member. A reference electrode and a measurement electrode, a reference substance that gives a reference of electromotive force of a concentration battery to the reference electrode, a sleeve fixed to the solid electrolyte member to form a space connected to the measurement electrode, and in the space. Ceramic powder or fibers filled, a ceramic film adhered to the outer surface of the sleeve, and a distal end portion of the sleeve is closed and a part of it extends onto the ceramic film and adheres to the ceramic film. And a metal film, the metal film being formed of a material that melts at the temperature of the molten metal to be measured.

[0013]

In the present invention, the sleeve is fixed to the solid electrolyte member, and the space in the sleeve is filled with ceramic powder or fibers. The ceramic powder or fiber filled in this sleeve prevents molten metal from entering the sleeve,
The gas (gas phase) existing between the ceramic powder or fibers in the sleeve is interposed between the measuring electrode and the molten metal to prevent the solid electrolyte member from directly contacting the molten metal. This can prevent the measurement electrode from oxidizing due to contact with the molten metal.

In the sensor for measuring the amount of dissolved hydrogen according to the present invention, a ceramic film is adhered to the outer surface of the sleeve, and the ceramic film is adhered to the metal film. Further, the tip of the sleeve is closed by this metal film. Since this metal film melts at the temperature of the molten metal at the time of measurement, when the sensor is immersed in the molten metal, the suspended matter on the surface of the molten metal adheres to this metal film, but when the metal film dissolves in the molten metal. The deposit attached to the metal film separates from the sensor, and the deposit does not exist at the tip of the sensor after the metal film is completely dissolved in the molten metal. Thereby, it is possible to prevent the formation of an oxide or non-oxide film that inhibits the movement of hydrogen between the molten metal and the gas phase in the sleeve, and it is possible to avoid the deterioration of the response characteristics of the sensor,
The sensor life is extended.

Further, when the sensor is immersed in the molten metal, the latent heat of melting is taken from the molten metal in the vicinity of the sensor when the metal film is melted, so that the rapid temperature change of the sensor is moderated. Therefore, damage to the sensor due to heat shock can be avoided.

Furthermore, for example, if the sensor after the formation of the ceramic film is dipped in a molten metal or alloy to form the metal film, both react at the interface between the metal film and the ceramic film and firmly adhere to each other. . Then, after the metal film is dissolved in the molten metal, the wettability when the surface of the ceramic film is wet with the molten metal is improved, and the molten metal is uniformly attached to the surface of the ceramic film. As a result, it is possible to prevent air from the outside from diffusing at the interface between the surface of the ceramic film and the molten metal and entering the inside of the sleeve, thereby deteriorating the measurement accuracy of the sensor.

The metal film is a metal or alloy selected from the group consisting of aluminum, copper, zinc, magnesium, silicon, titanium, zirconium, manganese, iron and lithium, depending on the components of the molten metal to be measured. It is preferably formed by That is, the metal film has the same or substantially the same composition as the molten metal to be measured,
It is preferable that the sensor is made of a material that dissolves in a short time when immersed in the molten metal and does not affect the composition of the molten metal. In addition, the total amount of metals forming the metal film is preferably an amount that does not affect the composition of the molten metal.

Further, the ceramic film is preferably formed of at least one selected from the group consisting of alumina, magnesia, water glass, zirconia and calcia. These ceramics can react with the metal film formed on the surface thereof to form a strong adhesion layer, and the wettability with respect to the molten metal is significantly improved. As a result, it is possible to prevent air from diffusing through the interface between the sensor and the molten metal and entering the sleeve.

[0019]

Embodiments of the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a sectional view showing a sensor for measuring the amount of dissolved hydrogen in molten metal according to the first embodiment of the present invention. The solid electrolyte member 1 is made of CaZr _0.9 In _0.1 O _3-x.
(However, x is 0 to _0.05 ), SrCe _0.95 Yb _0.05 O
_3-x and BaCe _0.9 Nd _0.1 O _{3-x and} the like are formed in a tubular shape with one end closed by ceramics or glass having a composition having proton conductivity, and the inner and outer surfaces of the solid electrolyte member 1 are As the measuring electrode and the reference electrode,
For example, the porous electrodes 2a and 2b made of Pt, Ni or an oxide conductor are formed by baking.

A ceramic pipe 4 is fitted to the end of the solid electrolyte member 1 on the closed end side, and the pipe 4 and the solid electrolyte member 1 are joined by an inorganic adhesive. Further, the joint portion between the solid electrolyte member 1 and the pipe 4 is hermetically sealed by the glass sealing material 6.
The glass sealing material 6 has a coefficient of thermal expansion close to the coefficient of thermal expansion of the solid electrolyte member 1 in the temperature range of use of the sensor of 300 to 1000 ° C., and further has a pour point equal to or higher than the use temperature of the sensor. It is preferably a sealing material.

The glass sealing material 6 is coated with a coating material 7 made of ceramics. The coating material 7 is for preventing the reaction between the glass sealing material 6 and the molten metal.

A metal pipe 9 made of stainless steel is inserted inside the ceramic pipe 4, and the tip of the metal pipe 9 is joined to the porous electrode 2b. Through the metal pipe 9, the solid electrolyte member 1
Then, as the reference substance, the reference gas 8 whose hydrogen gas partial pressure is adjusted to be constant is supplied. Also, this metal pipe 9
It also functions as a lead for the porous electrode 2b.

On the other hand, a conductive sleeve 3 is fitted on the open end side of the solid electrolyte member 1. The sleeve 3 is formed of a material having a low reactivity with the flux or the molten metal under the sensor use condition. For example, the conductive sleeve 3 is formed of graphite or a mixture of graphite and alumina, silicon carbide, silicon nitride, zirconium oxide, metal boride, metal carbide or other metal oxide. .

The solid electrolyte member 1 on the inner surface of the sleeve 3
An extraction electrode 2c electrically connected to the porous electrode 2a is provided near the open end of the extraction electrode 2
The porous electrode 2a and the conductive sleeve 3 are electrically connected to each other via c. The inside of the solid electrolyte member 1 is filled with a ceramic powder 12 such as alumina, zirconia, magnesia or silicon carbide.

On the outer surfaces of the sleeve 3 and the pipe 4, a ceramic coating film 14 formed of at least one of alumina, silica, magnesia, water glass, zirconia and calcia is provided. Also,
A metal coating film 13 is formed on the ceramic coating film 14 on the sensor tip side, and the sleeve 3
The tip of the is closed by the metal coating film 13. The metal coating film 13 is made of, for example, aluminum, copper, zinc, magnesium, silicon, titanium,
It is formed of at least one metal or alloy selected from the group consisting of zirconium, manganese, iron and lithium. The material of the metal coating film 13 is
It is appropriately set according to the molten metal to be measured. That is, the metal coating film 13 can be dissolved in the molten metal at the temperature of the molten metal at the time of measurement, and its composition and thickness are set so as not to affect the composition of the molten metal to be measured. .

The metal coating film 13 chemically reacts with the ceramic coating film 14 and has a strong physical adhesiveness, so that the metal coating film 13 is adhered to the interface between the metal coating film 13 and the ceramic coating film 14 so that gas does not diffuse. The metal coating film 1
The method of forming No. 3 is not particularly limited.

In the sensor for measuring the amount of dissolved hydrogen according to this embodiment, the sleeve 3 side is immersed in molten metal. At this time, oxides, non-oxides, flux for melt processing, slag, and the like float on the surface of the molten metal, and these floating substances adhere to the surface of the metal coating film 13. However, as the metal coating film 13 dissolves in the molten metal,
The deposits attached to the surface of the metal coating film 13 are separated from the sensor. Therefore, when the metal coating film 13 is completely dissolved, it is possible to avoid the inclusion of oxides, non-oxides, flux for melt processing, slag, etc. between the tip of the sensor and the molten metal. In addition, since the sleeve 3 is filled with the ceramic powder 12, it is possible to prevent molten metal from entering the sleeve 3,
The inside of the chamber becomes a gas chamber, and the molten metal and the solid electrolyte member 1
Direct contact with and can be prevented. Further, the porous electrode 2a, which is the measurement electrode, is electrically connected to the molten metal via the extraction electrode 2c and the conductive sleeve 3.

Next, a gas containing hydrogen or water vapor of a predetermined concentration is supplied as the reference gas 8 to the porous electrode 2b side of the solid electrolyte member 1 through the metal pipe 9. Then, due to the difference in hydrogen activity between the molten metal and the reference gas 8, an electromotive force is generated between the porous electrodes 2a and 2b on both sides of the solid electrolyte member 1. The hydrogen concentration in the molten metal is measured by measuring this electromotive force. This measurement principle is performed by measuring the electromotive force of a gas concentration battery using a proton conductive solid electrolyte substance.

A gas concentration cell type hydrogen sensor using a solid electrolyte exhibiting proton conductivity operates stably at high temperatures and exhibits an electromotive force close to the theoretical value given by the following mathematical formula 1.

[0030]

## EQU1 ## E = (RT / 2F) ln [P _H1 (1) / P _H2 (2)] where E is electromotive force (V), R is gas constant, F is Faraday constant, T is absolute temperature, P _H1 (1) and P _H2 (2) are hydrogen partial pressures on the measurement electrode side and the reference electrode side, respectively.

An equilibrium relationship is established between the hydrogen concentration in the molten metal and the hydrogen partial pressure on the molten metal, which follows the Sieverts rule of the following mathematical formula 2.

[0032]

## EQU2 ## S = K (P _H2 ) ^1/2 where S is the equilibrium solubility of hydrogen, K is a constant, and P _H2 is the partial pressure of hydrogen on the melt.

As can be seen from the equation (2), if the hydrogen partial pressure in the gas phase in contact with the molten metal can be measured, the concentration of hydrogen dissolved in the molten metal can be obtained.

Generally, the hydrogen concentration in the molten metal depends on the hydrogen partial pressure and the melt temperature in the vapor phase in contact with the melt, and the hydrogen partial pressure and the melt temperature depend on the Sievert's law and Henry's law. Follow the (Henry) rule. For this reason, the hydrogen concentration S can be expressed by the following equation (3).

[0035]

Equation 3] logS = A- (B / T) + (1/2) log (P H2) where, A and B are constants which depend on the composition of the metal.

Therefore, the sleeve 3 side of the sensor shown in FIG. 1 is immersed in molten metal to measure the hydrogen concentration in the molten metal. That is, from the electromotive force generated between the reference electrode and the measurement electrode, the hydrogen partial pressure P _H2 is obtained by using the above-mentioned formula 1, and this hydrogen partial pressure is substituted into the formula 3 to obtain the hydrogen concentration S in the molten metal. Can be asked.

For example, a carbon rod is inserted into the molten metal, the potential difference between the carbon rod and the metal pipe 9 is measured, and the amount of hydrogen dissolved in the molten metal is detected based on the result. be able to.

In this case, in this embodiment, when the sensor is immersed in the molten metal, the suspended matter attached to the metal coating film 13 at the tip of the sensor is the metal coating film 13.
When the metal coating film 13 is completely dissolved in the molten metal, oxides, non-oxides, fluxes, slags, etc. are formed between the sensor tip and the molten metal. It is possible to avoid measurement failure and deterioration of response characteristics without intervening. In addition, sleeve 3
Since the ceramic powder 12 filled inside can prevent the molten metal from directly contacting the porous electrode 2a which is the measurement electrode, the porous electrode 2 can be contacted with the molten metal.
It is possible to prevent the formation of an insulating film on the surface of a. Further, when the metal coating film 13 is melted, the latent heat of melting is taken from the molten metal in the vicinity of the sensor, so that the temperature of the molten metal in the vicinity of the sensor is lowered, and the heat shock received by the sensor is mitigated, which can prevent the sensor from being damaged. . Therefore, the sensor for measuring the amount of dissolved hydrogen according to the present embodiment has a long sensor life and can measure the amount of dissolved hydrogen in molten metal for a long period of time. Furthermore, since the metal coating film 13 reacts with the ceramic coating film 14 at the interface and firmly adheres to each other, after the metal coating film 13 is dissolved, the surface of the ceramic coating film 14 is wet with molten metal. Property is improved, air can be prevented from diffusing at the interface between the surface of the ceramic coating film 14 and the molten metal, and the measurement accuracy is improved.

FIG. 2 is a sectional view showing a sensor for measuring the amount of hydrogen dissolved in molten metal according to the second embodiment of the present invention. The present embodiment is different from the first embodiment in that the solid reference material 18 is used as the reference material, and other configurations are basically the same as those in the first embodiment. The same parts as those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this embodiment, inside the ceramic pipe 4 fitted to the closed end side of the solid electrolyte member 1,
As the solid reference material 18, for example, a mixture of aluminum phosphate and an electronically conductive oxide, a mixture of a metal and a metal hydride, or the like is charged. These substances have the property that the activity of hydrogen or steam is always kept constant. At the end of the pipe 4 opposite to the solid electrolyte member 1, the alumina cement 11 and the ceramic filler 15 are provided.
Are filled in this order from the outside, and the solid reference material 18
Is sealed with these alumina cement 11 and filler 15. The lead 16 is electrically connected to the porous electrode 2b, which is a reference electrode, and the solid reference material 18,
The filler 15 and the alumina cement 11 are inserted and led out to the outside. Also in this embodiment, the same effect as that of the first embodiment can be obtained.

The result of actually manufacturing the sensor for measuring the amount of dissolved hydrogen in molten metal according to the first embodiment of the present invention and examining its initial response characteristics will be described below.

First, CaZr _0.9 In _0.1 O _{3 -x} (where x is 0 to 0) which is a perovskite type proton conductive oxide.
0.05), a tubular solid electrolyte member 1 having one end closed was formed. Then, on the inner and outer surfaces of the solid electrolyte member 1, porous electrodes 2a and 2b made of Pt were baked at a temperature of 900 ° C. as a measurement electrode and a reference electrode, respectively.

Next, on the closed end side of the solid electrolyte member 1, a pipe 4 made of alumina (outer diameter 6.5 mm, inner diameter 4.
5 mm and a length of 500 mm) were fixed using an alumina-based ceramic adhesive, and the bonded portion was hermetically sealed with a glass sealing material 6. Further, the glass sealing material 6 was covered with an alumina ceramic coating material 7. Further, a conductive sleeve 3 made of carbon was fitted and fixed to the open end side of the solid electrolyte member 1. And
An extraction electrode 2c is formed on the inner surface of the sleeve 3 so as to be in electrical contact with the porous electrode 2a.

Then, as the ceramic powder 12 for preventing the invasion of the molten metal inside the solid electrolyte member 1,
Filled with alumina powder. Then, the ceramic coating film 14 was formed on the sleeve 3 and the surface of the pipe 4 on the sensor tip side. Next, about 1 from the sensor tip
A range of up to 5 cm is immersed in molten aluminum, and the aluminum and the ceramic coating film 14 are about 3
After reacting for 0 minutes, it was taken out from the molten metal and a metal coating film 13 was formed to cover the ceramic powder 12 and the ceramic coating film 14 at the tip of the sleeve 3.

Then, a stainless steel pipe 9 was inserted inside the alumina pipe 4, and the tip of this pipe 9 was electrically contacted with and fixed to the porous electrode 2b.

The sensor thus manufactured was inserted into an aluminum alloy having a temperature of 700 ° C. melted in a graphite crucible, and the electromotive force response of the sensor was measured. At the time of measurement, an argon gas containing 1% by volume of hydrogen was introduced to the reference electrode side through a stainless pipe 9. The hydrogen concentration in the molten metal was adjusted by changing the hydrogen gas concentration in the vapor phase on the aluminum alloy melted in the graphite crucible. Further, by inserting a carbon rod into the molten metal and measuring the potential difference between the carbon rod and the stainless pipe 9, the electromotive force between the reference electrode and the measurement electrode of the solid electrolyte member 1 is measured. The measurement was performed. The temperature in the molten metal is chromel-alumel thermocouple (K thermocouple).
It was measured at.

As a result, the sensor according to the present invention was able to avoid a sudden deterioration of the initial characteristics when the sensor was inserted into the molten metal and measurement was started, and the response characteristics of the sensor were good. Further, it is possible to avoid the diffusion of air at the interface between the surface of the ceramic coating film and the molten metal, and the measurement accuracy is improved. Furthermore, even when the flux component floats on the surface of the molten metal, the measuring electrode does not deteriorate in a short time,
The sensor life has been significantly extended. Furthermore, when the metal coating film is melted, the latent heat of melting is taken from the molten metal in the vicinity of the sensor, so that damage to the sensor due to heat shock could be prevented.

In each of the above-described embodiments, the case where the ceramic pipe is previously attached to the solid electrolyte member has been described, but the ceramic pipe is fixed to the solid electrolyte member by an inorganic adhesive at the time of use. Good. In this case, as a sealing material that seals the joint portion between the solid electrolyte member and the ceramic pipe, a dense glass sealing material having a softening point below the operating temperature of the sensor and a pour point above the operating temperature of the sensor is used. Preference is given to using.

[0049]

As described above, in the sensor for measuring the amount of dissolved hydrogen in molten metal according to the present invention, the metal film is adhered to the surface of the ceramic film and the tip of the sleeve is covered with this metal film. Since the metal film dissolves in the molten metal when inserted into the molten metal, the initial characteristics of the sensor are significantly deteriorated by oxides, non-oxides, flux, slag, etc. floating on the surface of the molten metal. Can be avoided, the life of the sensor can be remarkably extended, and deterioration of response characteristics can be avoided.

Further, in the sensor for measuring the amount of dissolved hydrogen in molten metal according to the present invention, when the metal film is melted, the latent heat of melting is removed from the molten metal in the vicinity of the sensor, so that the heat shock applied to the sensor is alleviated. It Therefore, damage to the sensor due to heat shock can be prevented.

Further, in the sensor for measuring the amount of dissolved hydrogen in molten metal according to the present invention, it is possible to prevent the outside air from diffusing at the interface between the ceramic film and the molten metal, so that the measurement accuracy is improved. There is also.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a sensor for measuring an amount of dissolved hydrogen in molten metal according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a sensor for measuring an amount of dissolved hydrogen in molten metal according to a second embodiment of the present invention.

[Explanation of symbols]

 1; solid electrolyte member 2a, 2b; porous electrode 2c; extraction electrode 3; conductive sleeve 4; ceramic pipe 6; glass sealing material 7; coating material 8; reference gas 9; metal pipe 11; alumina cement 12; Ceramic powder 13; Metal coating film 14; Ceramic coating film 15; Ceramic filler 16; Lead 18; Solid reference material

Claims (5)

[Claims] 1. A solid electrolyte member formed of a solid electrolyte material having proton conductivity, a reference electrode and a measurement electrode provided on the solid electrolyte member, and a reference of an electromotive force of a concentration battery with respect to the reference electrode. , A sleeve forming a space fixed to the solid electrolyte member and connected to the measuring electrode, a ceramic powder or fiber filled in the space, and a ceramic adhered to the outer surface of the sleeve. A film, and a metal film that covers the ceramic film and covers the tip of the sleeve, and a part of the film extends onto the ceramic film, and the metal film is a temperature of the molten metal to be measured. A sensor for measuring the amount of hydrogen dissolved in a molten metal, which is formed of a material that dissolves in. 2. A solid electrolyte member formed in a tubular shape, one end of which is closed by a solid electrolyte material having proton conductivity, a reference electrode provided on an outer surface of the solid electrolyte member, and a reference electrode with respect to the reference electrode. A reference substance which gives a reference for electromotive force of the concentration cell, a measuring electrode provided on the inner surface of the solid electrolyte member, a sleeve for fitting the open end side of the solid electrolyte member, and a sleeve filled with the sleeve. Ceramic powder or fibers, a ceramic film adhered to the outer surface of the sleeve, and a metal film that covers the tip of the sleeve and extends a part of the sleeve onto the ceramic film and adheres to the ceramic film. And the metal film is formed of a material that melts at the temperature of the molten metal to be measured, the sensor for measuring the amount of dissolved hydrogen in the molten metal. 3. The metal film comprises aluminum, copper, zinc, magnesium, silicon, titanium, zirconium,
The sensor for measuring the amount of hydrogen dissolved in molten metal according to claim 1 or 2, which is formed of at least one metal or alloy selected from the group consisting of manganese, iron and lithium. 4. The amount of hydrogen dissolved in the molten metal according to claim 1, wherein the metal film reacts with an interface with the ceramic film and adheres to each other. Measuring sensor. 5. The ceramic film is formed by at least one selected from the group consisting of alumina, silica, magnesia, water glass, zirconia and calcia. The sensor for measuring the amount of dissolved hydrogen in the molten metal according to any one of items.