JP2010066063A - Solid electrolyte element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte element capable of measuring an oxygen region extremely lower in concentration than a molten metal in the prior art, and excellent in electromotive force characteristics and heat shock resistance. <P>SOLUTION: The solid electrolyte element includes a zirconium oxide sintered compact containing 6-12 mol% of magnesium oxide, 0.3-1.5 mol% of calcium oxide, 0.5-2 mol% of aluminum oxide, 0.4-2 mol% of silicon oxide and 0.1-0.5 mol% of yttrium oxide. The deposition speed of monoclinic zirconia can be delayed by adding calcium oxide to a structure stabilized by magnesium oxide, the formation of cracks or voids in a grain boundary is accelerated by silicon oxide, the heat shock properties of the sintered compact can be enhanced, the abnormal growth of grains and the particle size of a crystal are suppressed by aluminum oxide and a silicic acid compound is formed by reaction with silicon oxide to enhance the heat shock properties of the sintered compact. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to refining of a molten metal such as iron refining, steel refining, or refining of a casting, and when refining from a raw material to reduce the dissolved oxygen very much, the oxygen in the molten metal The present invention relates to a solid electrolyte suitable for an oxygen sensor required to measure the amount more accurately and more quickly.

In recent years, it has been found that it is necessary to control the state of the hot metal in order to stabilize the state of the molten steel, and attempts have been made to measure the amount of oxygen at a very low concentration in the hot metal. In addition, control of oxygen concentration has been considered important when producing high quality castings, and measurement of oxygen concentration has been tried. Although there are technologies described in Patent Documents 1 to 5 as conventional technologies, these technologies are excellent in thermal shock resistance of the sensors used, but are not capable of measuring extremely low concentrations of oxygen such as hot metal and castings. It was. In addition, a technique for coating a material having high ion conductivity on the inside or the entire surface of a Tamman tube-shaped oxygen sensor is known (Patent Documents 6 and 7). However, it has not been commercialized because there is a problem that the coat does not stick well during firing. In addition, oxygen sensors for low melting point metals (Patent Documents 8 and 9) and automobile sensors (Patent Document 10) have been developed, but no sensor for measuring extremely low oxygen concentration in molten steel has been developed. is there.
Japanese Patent No. 1693548 Japanese Patent No. 1807849 JP 2002-228627 A JP 2002-338348 A JP 2003-034575 A JP-A-10-213563 JP 2001-281212 A Japanese Patent Laid-Open No. 11-240755 JP 2006-250577 A JP 2006-226966 A

  An object of the present invention is to provide a solid electrolyte element having an electromotive force characteristic capable of measuring an oxygen region having a concentration much lower than that of a conventional molten metal such as hot metal or casting.

  In order to solve this problem, the present invention has the following configuration. That is, 6 to 12 mol% magnesium oxide, 0.3 to 1.5 mol% calcium oxide, 0.5 to 2 mol% aluminum oxide, 0.4 to 2 mol% silicon oxide and 0.1 to 0.1 mol yttrium oxide A solid electrolyte element comprising a zirconium oxide sintered body containing 0.5 mol%.

  According to the present invention, there is provided a solid electrolyte element capable of measuring oxygen in the field of extremely low oxygen concentration such as hot metal or casting, which has been difficult to measure conventionally.

  The solid electrolyte element of the present invention has the following configuration. That is, 6 to 12 mol% magnesium oxide, 0.3 to 1.5 mol% calcium oxide, 0.5 to 2 mol% aluminum oxide, 0.4 to 2 mol% silicon oxide and 0.1 to 0.1 mol yttrium oxide A solid electrolyte element comprising a zirconium oxide sintered body containing 0.5 mol%.

  It is important that the zirconium oxide sintered body used in the solid electrolyte element of the present invention is a zirconium oxide sintered body containing 6 to 12 mol% of magnesium oxide.

  In general, zirconium oxide stabilized with yttrium oxide is very good as a solid electrolyte, but becomes a problem in use because it dissolves in molten metal.

  Therefore, it is necessary to have a structure stabilized with magnesium oxide, and stabilization is achieved by setting the content of magnesium oxide to 6 to 12 mol%. When the content of magnesium oxide is less than 6 mol%, the state of zirconium oxide becomes unstable and a problem occurs in the electromotive force characteristics. When magnesium oxide exceeds 12 mol%, a magnesium oxide layer is deposited at the grain boundary. Therefore, even if magnesium oxide is added, it is not a stabilizer for zirconium oxide, and thermal shock resistance is inferior.

  It is important that the zirconium oxide sintered body used for the solid electrolyte element of the present invention contains not only the magnesium oxide but also 0.3 to 1.5 mol% of calcium oxide. When calcium oxide is contained in the range of 0.3 to 1.5 mol%, the precipitation rate of monoclinic zirconia can be slowed and the amount of precipitation can be easily controlled.

  Further, it is necessary to further contain 0.4 to 2 mol% of silicon oxide. Silicon oxide reacts with magnesium oxide to produce a silicic acid compound (magnesium silicate), but this reaction occurs at the grain boundary. Therefore, by containing 0.4 to 2 mol% of silicon oxide, cracks and pores are formed at the grain boundary. Generation | occurrence | production can be accelerated | stimulated and the thermal shock property of a sintered compact can be improved. The thermal shock resistance is also improved by the difference in thermal expansion coefficient between the silicate compound and the matrix. If it is less than 0.4 mol%, a sufficient effect cannot be obtained, and if it exceeds 2 mol%, there are too many cracks and pores, and the mechanical strength and hermeticity of the sintered body are reduced. The composite silicate of magnesium oxide and calcium oxide, which is a stabilizer, becomes too much at the grain boundary, which inhibits stabilization of zirconium oxide. Preferably, the range of 0.5 to 1.5 mol% is good. It is also preferable to use fine particles such as aerosil when adding silicon oxide.

  Further, it is necessary to contain 0.5 to 2 mol% of aluminum oxide. Thereby, abnormal grain growth can be suppressed and the crystal grain size can be suppressed. Moreover, it reacts with silicon oxide to produce a silicate compound, thereby improving the thermal shock resistance of the sintered body. When aluminum oxide exceeds 2 mol%, a compound of aluminum oxide and stabilizers magnesium oxide and calcium oxide is formed at the grain boundary, and the stabilization of zirconium oxide is inhibited.

  Zirconium oxide sintered bodies containing magnesium oxide, calcium oxide, aluminum oxide and silicon oxide as described above are known as molten steel sensors. In the present invention, however, yttrium oxide is further added in an amount of 0.1 to 0.5 mol%. It is very important to contain a small amount. As described above, yttrium oxide-stabilized zirconium oxide is eroded in molten steel and cannot be used as a sensor. Magnesium oxide-stabilized zirconium oxide is excellent in thermal shock resistance but has poor electromotive force characteristics as a solid electrolyte. However, when the above-described magnesium oxide-stabilized zirconium oxide contains 0.1 to 0.5 mol% of yttrium oxide, it exhibits thermal shock resistance and electromotive force characteristics capable of measuring an extremely low oxygen concentration region. When the yttrium oxide content is less than 0.1 mol%, there is no effect of improving the electromotive force characteristics, and when it exceeds 0.5 mol%, the thermal shock resistance is inferior. Preferably 0.2-0.4 mol% is desirable.

  The solid electrolyte element of the present invention preferably has a one-end closed tube (hereinafter referred to as Tamman tube) shape. In order to measure the oxygen concentration by immersing the zirconium oxide sintered body in the molten metal, it can be sealed with a standard substance inside, so that the internal oxygen partial pressure is always kept constant. This is because it can be maintained and is preferable for measuring an accurate oxygen concentration. When the thickness is reduced in the Tamman tube shape, the responsiveness is improved. However, since the possibility of breakage due to a decrease in electromotive force value, a decrease in mechanical strength and the erosion of molten metal increases, the thickness on the sealed side is 0. About 4 to 1.2 mm is preferable. If the thickness on the sealed side is less than 0.4 mm, the molten metal may enter or break while measuring the oxygen concentration, which is not preferable. If it exceeds 1.2 mm, the thermal shock resistance is inferior and the response may be delayed, which is not preferable.

The solid electrolyte element of the present invention preferably has a helium leak amount of ² to 90 m ³ / m ² · s · Pa. The amount of helium leak is an index of airtightness, and the denseness of the element structure can be determined. If the amount of helium leak is less than ² m ³ / m ² · s · Pa, the thermal shock may be inferior, such being undesirable. If the amount of helium leak exceeds 90 m ³ / m ² · s · Pa, the electromotive force characteristics may be deteriorated, which is not preferable. Preferably 3-60 m < ³ > / m < ² > * s * Pa is desirable.

  The average crystal particle size of the solid electrolyte element of the present invention is preferably 10 to 100 μm. The average crystal particle diameter can be obtained by taking a photograph of a secondary electron image on the surface of the sintered body using an electron microscope. An average crystal particle size of 10 μm or less is not preferable because electromotive force characteristics are poor. An average particle size of 100 μm or more is not preferable because the solid electrolyte becomes too dense and the thermal shock resistance is poor. The average particle diameter is preferably 20 to 80 μm.

The manufacturing method of the solid electrolyte element of this invention is demonstrated. The starting material may be any of chloride, oxide, carbonate and the like. The composition of the powder is adjusted so that the magnesium oxide is 6 to 12 mol%. The powder can be synthesized by any of a hydrolysis method, a coprecipitation method, a thermal decomposition method, or an oxide mixing method. The synthesized powder is added so that the calcium oxide content is 0.3 to 1.5 mol% and the aluminum oxide content is 0.5 to 2 mol%, and pulverized and mixed. For the pulverization / mixing, a wet pulverizer such as a ball mill or a medium stirring mill, or a dry mixer such as a Henschel mixer can be used. When wet pulverized and mixed, the prepared slurry is dried with a spray dryer or the like. The resulting powder was fired at 900 ° C. to 1200 ° C. and added thereto so that the content of silicon oxide was 0.4 to 2 mol% and the content of yttrium oxide was 0.1 to 0.5 mol%, Wet pulverize and make a slurry, and granulate the prepared slurry to obtain a raw material powder.
General molding methods include press molding and injection molding. When press molding is performed, a granulated powder is prepared by adding a binder to the slurry. The granulated body is press-molded to form a molded body. After that, the dimensional shape is adjusted and a processed body is created.

  When injection molding is performed, a granulated powder is produced without adding a binder to the slurry. An injection binder is added to the granulated body to produce a compound, which is then injection molded to form a molded body. Thereafter, the molded body is degreased to produce a degreased body.

  The fabricated processed bodies and degreased bodies are set one by one on a dedicated setter, placed in a mortar, covered with a lid, and sintered. The setter should be made of a common material and structured to minimize contact. Sintering is held at a maximum temperature of 1700 to 1800 ° C. for a certain time, rapidly cooled to about 1400 ° C., held for a certain time, and then cooled to room temperature.

  The sintered body thus produced provides a solid electrolyte element that is particularly excellent in electromotive force characteristics and excellent in thermal shock resistance.

  Hereinafter, the present invention will be described in more detail with reference to examples.

  The physical properties of the examples were measured and evaluated as follows.

(1) Quantitative analysis of magnesium oxide, calcium oxide, silicon oxide, aluminum oxide and yttrium oxide About 0.1 g of a sample was weighed into a platinum crucible and melted with potassium hydrogen sulfate. This was dissolved in dilute nitric acid and fixed, and each element was quantified by ICP emission spectrometry. This quantitative value was converted to oxide. An SPS1200VR type manufactured by Seiko Denshi Kogyo was used as the ICP emission spectroscopic analyzer.

(2) Helium leak amount The helium leak amount is an index of hermeticity of the sintered body.

The sintered body was thoroughly cleaned by ultrasonic cleaning using water and then dried at 250 ° C. Next, the outside of the sintered body was held in a helium gas atmosphere adjusted to 1013 hPa, and the inside was drawn with a vacuum pump. When the degree of decompression did not change, the sintered body was separated from the decompression system, the open end was sealed, and the time required for the degree of decompression from 1 torr (133.322 Pa) to 5 torr (666.61 Pa) was read.
The helium leak amount L was determined by the following equation.

L = 5.333 × V / (T × A)
V: Internal volume inside sintered body (m ³ )
T: Time (seconds) during which the degree of decompression changes from 1 torr to 5 torr
A: A simple average area between the surface area of the sintered body in contact with the helium gas and the surface of the sintered body in contact with the reduced pressure atmosphere. (M ² )
(3) Average crystal particle diameter Using a scanning electron microscope, take a photo of the secondary electron image on the surface of the sintered body, read the size of each crystal particle in terms of area, and convert it into a circle. Is the average of the values calculated. First, photographs were taken at 200 magnifications at 10 arbitrary points on the surface of the sintered body with an electron microscope. Using an image processing apparatus, the average equivalent circle diameter of the crystal grains of the photographed photograph was determined. The average equivalent circle diameter obtained from each photograph was averaged to obtain the average crystal particle diameter.

(4) Thermal shock resistance It was immersed in molten steel at 1700 ° C., held for 15 seconds, and pulled up. After raising, it was cooled to room temperature. First, the state of erosion of iron was confirmed as it was, and then the Tamman tube was immersed in a color check solution and washed with water. Since the color check solution penetrates into the crack if there is a crack, the crack was visually inspected. The cross cracks (those with two or more cracks combined) were evaluated as x, those having one or two cross cracks were evaluated as Δ, and those where no cross cracks were observed were evaluated as ○. Even when observed as it is, if there is iron erosion, iron remains in the form of cracks, so the number of cross-shaped erosions was counted to make a similar evaluation. The worse of both results was taken as the evaluation result.

(5) Electromotive force characteristics (electromotive force value and responsiveness)
For this patented product and the conventional product, as a reference electrode, insert a mixture of metallic chromium powder and chromium oxide powder inside, put a lead wire made of Fe, and then fix it with aluminum oxide powder, and further above it Was fixed with a commercially available aluminum oxide cement (manufactured by Sumitomo Chemical Co., Ltd.) to prepare a probe with two sensor elements. As the counter electrode, Fe wire was used. It was immersed in molten steel, the waveforms of both electromotive forces were recorded on a recorder chart, and the time until a stable measurement value was obtained and the electromotive force value when stable were measured. The value was an average of 10 pieces. When this time was within 10 seconds, ◯ and 10 seconds or more were marked with ×. The electromotive force value was judged by the difference between the value of this patent product and the conventional product. The calculation was according to the following formula. Here, the conventional product refers to a product that does not contain the yttrium oxide of Example 1 of this patent.
Electromotive force value difference = | (electromotive force value when using the zirconium oxide sintered body of the example or comparative example) | − | (electromotive force value when using a conventional product) |
Since the electromotive force value shows a negative value in the low oxygen region, the absolute values of the electromotive force values are compared. The larger the absolute value of the electromotive force value, the higher the electromotive force characteristic and the better the electromotive force characteristic. The larger the electromotive force value difference, the better the electromotive force characteristic.
The molten steel was charged with 10 kg of pure iron in an aluminum oxide crucible and melted using a high-frequency furnace, and deoxygenated by adding carbon to adjust the oxygen level.

Example 1
Zirconium oxide powder, magnesium oxide powder, calcium oxide powder and aluminum oxide powder were mixed with a Henschel mixer so as to have the amounts shown in Example 1 in Table 1, and baked at 1050 ° C. for 2 hours to obtain raw material powder.

  Next, yttrium oxide powder and silicon oxide powder are added to the raw material powder in the amounts shown in Example 1 of Table 1, pulverized with a medium stirring mill, 2% polyvinyl alcohol solution is added, and spray dried with a spray dryer. A granulated powder was obtained.

The granulated powder was molded by a rubber press method into an end-closed cylinder having an outer diameter of 7 mm, an inner diameter of 3.8 mm, and a length of 45 mm. The press pressure was 1 ton / cm ² .

  The obtained molded body was processed into an outer diameter of 5.7 mm and a length of 45 mm with an NC lathe and sintered at 1700 ° C. to 1800 ° C. for 3 hours to obtain a sintered body. Sintering was performed by setting the workpieces one by one on a dedicated setter, placing them in a mortar and capping the lid. The setter used common material. The sintered body had an outer diameter of 4.5 mm, an inner diameter of 3.0 mm, and a length of 35 mm. The sintered body thus obtained was measured for magnesium oxide, calcium oxide, silicon oxide, aluminum oxide, yttrium oxide amount, He leak amount, thermal shock resistance, and electromotive force characteristics. The evaluation results are shown in Table 2.

Example 2
Zirconium oxide powder, magnesium oxide powder, calcium oxide powder, and aluminum oxide powder were pulverized with a medium stirring mill so as to have the amounts shown in Example 2 of Table 1, dried with a spray dryer, and fired at 1000 ° C. for 2 hours. A raw material powder was obtained.

  Next, yttrium oxide powder and silicon oxide powder are added to the raw material powder in the amounts shown in Example 2 in Table 1, ground with a medium stirring mill, 2% polyvinyl alcohol solution is added, and spray dried with a spray dryer. A granulated powder was obtained.

The granulated powder was molded by a rubber press method into an end-closed cylinder having an outer diameter of 7 mm, an inner diameter of 3.8 mm, and a length of 45 mm. The press pressure was 1 ton / cm ² .

  The obtained molded body was processed into an outer diameter of 5.7 mm and a length of 45 mm with an NC lathe and sintered at 1700 ° C. to 1800 ° C. for 3 hours to obtain a sintered body. Sintering was performed by setting the workpieces one by one on a dedicated setter, placing them in a mortar and capping the lid. The setter used common material. The sintered body had an outer diameter of 4.5 mm, an inner diameter of 3.0 mm, and a length of 35 mm. The sintered body thus obtained was measured for magnesium oxide, calcium oxide, silicon oxide, aluminum oxide, yttrium oxide amount, He leak amount, thermal shock resistance, and electromotive force characteristics. The evaluation results are shown in Table 2.

Example 3
Zirconium oxide powder, magnesium oxide powder, calcium oxide powder, and aluminum oxide powder were mixed with a Henschel mixer so as to have the amounts shown in Example 3 of Table 1, and fired at 950 ° C. for 2 hours to obtain raw material powder.

  Next, yttrium oxide powder and silicon oxide powder are added to the raw material powder in the amounts shown in Example 3 in Table 1, ground with a medium stirring mill, 2% polyvinyl alcohol solution is added, and spray dried with a spray dryer. A granulated powder was obtained.

The granulated powder was molded into a cylinder with one closed end having an outer diameter of 6 mm, an inner diameter of 2.9 mm, and a length of 40 mm by a rubber press method. The press pressure was 1 ton / cm ² .

  The obtained molded body was processed into an outer diameter of 4.6 mm and a length of 40 mm with an NC lathe and sintered at 1700 ° C. to 1800 ° C. for 3 hours to obtain a sintered body. Sintering was performed by setting the workpieces one by one on a dedicated setter, placing them in a mortar and capping the lid. The setter used common material. The sintered body had an outer diameter of 3.6 mm, an inner diameter of 2.3 mm, and a length of 30 mm. The sintered body thus obtained was measured for magnesium oxide, calcium oxide, silicon oxide, aluminum oxide, yttrium oxide amount, He leak amount, thermal shock resistance, and electromotive force characteristics. The evaluation results are shown in Table 2.

Comparative Example 1
Zirconium oxide powder, magnesium oxide powder, calcium oxide powder, and aluminum oxide powder were mixed so as to have the amounts shown in Comparative Example 1 in Table 1, and fired at 1000 ° C. for 2 hours to obtain raw material powder.

  Next, the raw material powder was pulverized with a medium stirring mill, a 2% polyvinyl alcohol solution was added, and the mixture was spray-dried with a spray dryer to obtain a granulated powder.

The granulated powder was molded by a rubber press method into an end-closed cylinder having an outer diameter of 7 mm, an inner diameter of 3.8 mm, and a length of 45 mm. The press pressure was 1 ton / cm ² .

  The obtained molded body was processed into an outer diameter of 5.7 mm and a length of 45 mm with an NC lathe and sintered at 1700 ° C. to 1800 ° C. for 3 hours to obtain a sintered body. Sintering was performed by setting the workpieces one by one on a dedicated setter, placing them in a mortar and capping the lid. The setter used common material. The sintered body had an outer diameter of 4.5 mm, an inner diameter of 3.0 mm, and a length of 35 mm. Table 2 shows the evaluation results obtained by measuring magnesium oxide, calcium oxide, silicon oxide, aluminum oxide, yttrium oxide amount, He leak amount, thermal shock resistance, and electromotive force characteristics of the types of sintered bodies thus obtained. Shown in

Comparative Example 2
Zirconium oxide powder, magnesium oxide powder, calcium oxide powder, and aluminum oxide powder were mixed so as to have the amounts shown in Comparative Example 2 in Table 1, and fired at 1000 ° C. for 2 hours to obtain raw material powder.

  Next, the raw material powder was pulverized with a medium stirring mill, a 2% polyvinyl alcohol solution was added, and the mixture was spray-dried with a spray dryer to obtain a granulated powder.

The granulated powder was molded into a cylinder with one closed end having an outer diameter of 6 mm, an inner diameter of 2.9 mm, and a length of 40 mm by a rubber press method. The press pressure was 1 ton / cm ² .

  The obtained molded body was processed into an outer diameter of 4.6 mm and a length of 40 mm with an NC lathe and sintered at 1700 ° C. to 1800 ° C. for 3 hours to obtain a sintered body. Sintering was performed by setting the workpieces one by one on a dedicated setter, placing them in a mortar and capping the lid. The setter used common material. The sintered body had an outer diameter of 3.6 mm, an inner diameter of 2.3 mm, and a length of 30 mm. The sintered body thus obtained was measured for magnesium oxide, calcium oxide, silicon oxide, aluminum oxide, yttrium oxide amount, He leak amount, thermal shock resistance, and electromotive force characteristics. The evaluation results are shown in Table 2.

Comparative Example 3
Zirconium oxide powder, magnesium oxide powder, calcium oxide powder, and aluminum oxide powder were mixed so as to have the amounts shown in Comparative Example 3 of Table 1, and fired at 1000 ° C. for 2 hours to obtain raw material powder.

  Next, the raw material powder was pulverized with a medium stirring mill, a 2% polyvinyl alcohol solution was added, and the mixture was spray-dried with a spray dryer to obtain a granulated powder.

The granulated powder was molded into a cylinder with one closed end having an outer diameter of 6 mm, an inner diameter of 2.9 mm, and a length of 40 mm by a rubber press method. The press pressure was 1 ton / cm ² .

  The obtained molded body was processed into an outer diameter of 4.6 mm and a length of 40 mm with an NC lathe and sintered at 1700 ° C. to 1800 ° C. for 3 hours to obtain a sintered body. Sintering was performed by setting the workpieces one by one on a dedicated setter, placing them in a mortar and capping the lid. The setter used common material. The sintered body had an outer diameter of 3.6 mm, an inner diameter of 2.3 mm, and a length of 30 mm. The sintered body thus obtained was measured for magnesium oxide, calcium oxide, silicon oxide, aluminum oxide, yttrium oxide amount, He leak amount, thermal shock resistance, and electromotive force characteristics. The evaluation results are shown in Table 2.

Comparative Example 4
Zirconium oxide powder, magnesium oxide powder, calcium oxide powder, and aluminum oxide powder were mixed so as to have the amounts shown in Comparative Example 4 in Table 1, and fired at 1000 ° C. for 2 hours to obtain raw material powder.

  Next, the raw material powder was pulverized with a medium stirring mill, a 2% polyvinyl alcohol solution was added, and the mixture was spray-dried with a spray dryer to obtain a granulated powder.

The granulated powder was molded into a cylinder with one closed end having an outer diameter of 6 mm, an inner diameter of 2.9 mm, and a length of 40 mm by a rubber press method. The press pressure was 1 ton / cm ² .

The obtained molded body was processed into an outer diameter of 4.6 mm and a length of 40 mm with an NC lathe and sintered at 1700 ° C. to 1800 ° C. for 3 hours to obtain a sintered body. Sintering was performed by setting the workpieces one by one on a dedicated setter, placing them in a mortar and capping the lid. The setter used common material. The sintered body had an outer diameter of 3.6 mm, an inner diameter of 2.3 mm, and a length of 30 mm. The sintered body thus obtained was measured for magnesium oxide, calcium oxide, silicon oxide, aluminum oxide, yttrium oxide amount, He leak amount, thermal shock resistance, and electromotive force characteristics. The evaluation results are shown in Table 2.
As is apparent from Table 2, Examples 1 to 3, that is, magnesium oxide 6 to 12 mol%, calcium oxide 0.3 to 1.5 mol%, aluminum oxide 0.5 to 2 mol%, silicon oxide 0.4 A solid electrolyte element comprising a zirconium oxide sintered body containing ˜2 mol%, containing yttrium oxide in an amount of 0.1 to 0.5 mol%, and a He leak amount of ² to 90 m ³ / m ² · s · Pa. Those having a crystal particle diameter of 10 to 100 μm are excellent in thermal shock resistance and electromotive force characteristics. On the other hand, Comparative Examples 1 to 3, that is, those having an amount of yttrium oxide or magnesium oxide outside the above range resulted in poor thermal shock resistance and electromotive force characteristics.

Claims (3)

Magnesium oxide 6-12 mol%, calcium oxide 0.3-1.5 mol%, aluminum oxide 0.5-2 mol%, silicon oxide 0.4-2 mol% and yttrium oxide 0.1-0. A solid electrolyte element comprising a sintered zirconium oxide containing 5 mol%. ^2. The solid electrolyte element according to claim 1, which has a shape of a one-end closed tube and has a helium leak amount of ² to 90 m ³ / m ² · s · Pa. The solid electrolyte element according to claim 1, wherein the zirconium oxide has an average crystal particle diameter of 10 to 100 μm.