KR102680263B1 - Method for producing reaction-reducing sintered body for high temperature furnace, reaction-reducing sintered body and high temperature furnace including the same - Google Patents

Abstract

The present invention relates to a method for producing a reaction-reducing sintered body for a high-temperature furnace, a reaction-reducing sintered body, and a high-temperature furnace containing the same. Specifically, it has excellent reaction reduction performance at high temperatures and can effectively suppress the generation of impurities in a high-temperature furnace. It relates to a method of manufacturing a LaYO ₃ ceramic sintered body for a reaction crucible.

Description

Method for producing reaction-reducing sintered body for high temperature furnace, reaction-reducing sintered body and high temperature furnace including the same {Method for producing reaction-reducing sintered body for high temperature furnace, reaction-reducing sintered body and high temperature furnace including the same}

The present invention relates to a method for producing a reaction-reducing sintered body for a high-temperature furnace, a reaction-reducing sintered body, and a high-temperature furnace containing the same. Specifically, it has excellent reaction reduction performance at high temperatures and can effectively suppress the generation of impurities in a high-temperature furnace. It relates to a method of manufacturing a LaYO ₃ ceramic sintered body for a reaction crucible.

Generally, a melting crucible for induction melting is made of graphite. At this time, the inner wall of the molten crucible for dissolving the high-temperature/highly reactive material needs to have minimal reactivity with the highly reactive material at high temperature. Therefore, technologies have been developed such as using a ceramic material in the form of a liner inside a graphite crucible or using a liner crucible to melt metals.

In particular, ceramic materials coated on the surface of the induction melting crucible include BN, Al ₂ O ₃ , MgO, ZrO ₂ , Y ₂ O ₃ , AlN, cordierite, mullite, and steatite ( Steatite) or kaolinite (forsterite) have been used.

However, induction melting requires continuously maintaining a high-temperature environment sufficient to dissolve metals with high melting points, so it is necessary to develop surface coating materials with better reaction reduction performance than these.

JP Patent Publication 2019-156653 (published on 2019.09.19.)

The present invention was created to solve the above-mentioned problems, and the object to be solved by the present invention is to provide a lanthanum-yttrium oxide sintered body with excellent reaction reduction ability so that it is suitable for use on the wall of a melting furnace of high temperature/highly reactive materials. .

In order to solve the above-described problem, the present invention 1) prepares a mixture by mixing lanthanum (La, Lanthanum) oxide powder and yttrium (Y, Yttrium) oxide powder with a solvent and then mixing them in a granular form, and then mixing the mixture. Manufacturing a molded body by molding; and

2) sintering the molded body to produce a lanthanum-yttrium oxide sintered body; providing a method of manufacturing a sintered body for reducing reaction in a high temperature furnace including the step.

When the lanthanum-yttrium oxide sintered body according to the present invention is used in a melting furnace, it has the advantage of effectively preventing the reaction between the melting furnace and the melt or improving the degree of contamination of the melt, thereby improving the purity of the melt and enabling recycling of the melt. Not only that, the sintered body can also be recycled.

Figure 1 is a diagram showing an X-ray diffraction pattern of a sintered body manufactured using a powder mixture of La ₂ O ₃ and Y ₂ O ₃ powder at a molar ratio of 1:0.7.
Figure _{2 is a} diagram _{showing an}

As described above, among the melting furnaces manufactured according to the prior art, there were some that used yttrium oxide, but there was a problem in that it did not effectively prevent reaction with highly reactive substances, such as rare earth metals, at high temperature/high pressure.

Accordingly, in order to solve the above-mentioned problems, the present inventors

1) preparing a mixture by mixing lanthanum (La) oxide powder and yttrium (Y) oxide powder with a solvent, and then molding the mixture to produce a molded body; and

2) sintering the molded body to produce a lanthanum-yttrium oxide sintered body; This problem was solved by providing a method for manufacturing a reaction-reduced sintered body for a high temperature furnace, including the step.

The sintered body manufactured in this way contains lanthanum-yttrium oxide, and lanthanum-yttrium oxide shows high phase stability not only at low temperatures but also at high temperatures compared to lanthanum oxide and yttrium oxide, and has excellent reaction reduction properties at high temperature/high pressure. When used in a melting furnace that handles high-temperature melt, such as a crucible or induction melting furnace, reaction with the melt is suppressed and it can be used as an excellent refractory material.

Before step 1), the lanthanum oxide powder and yttrium oxide powder may undergo a pre-heating step to remove impurities. Preferably, the pre-heating may be performed at a temperature of about 400 to 1100° C. for 10 minutes to 2 hours.

More preferably, the heating temperature may be 700 to 1000°C, and the heating time may be 10 minutes or more and 1 hour or less. At this time, the minimum heating temperature refers to the minimum temperature at which impurities can be removed, and the maximum heating temperature refers to the maximum temperature that does not affect the phase stability of the powder. It is desirable to adjust the heating temperature and heating time according to the type and content of impurities in the powder, and the heating environment.

Preferably, the lanthanum oxide powder and yttrium oxide powder provided for mixing in step 1) may have a purity of 99.9% or more by removing impurities through the pre-heating step.

In a preferred embodiment of the present invention, in step 1), lanthanum oxide powder and yttrium oxide powder may be mixed so that the molar ratio of lanthanum to yttrium satisfies the following condition equation 1.

[Conditional expression 1]

1.0≤N _Y /N _La≤1.5

In Condition Equation 1, N _Y represents the number of moles of yttrium and N _La represents the number of moles of lanthanum.

If _NY /N _La is less than 1.0, the ratio of lanthanum becomes too high and another phase occurs, and conversely, if _NY /N _La exceeds 1.5, the ratio of yttrium becomes too high and LaYO ₃ oxide may not be formed. there is.

More preferably, N _Y /N _La may be 1.0 to 1.3.

In this way, the N _Y / N _La ratio is preferably 1.0 to 1.3 because yttrium is lost due to volatilization during the formation of the sintered body, so the optimal ratio for forming the final La:Y ratio of 1:1 is about 1:1. This is because it becomes 1.0 to 1.3. In addition, when the ratio is less than 1.0, LaYO ₃ oxide is not formed, but when it is more than 1.0, the formation of LaYO ₃ phase is possible.

Figures 1 and 2 show a sintered body manufactured using a powder mixture of La ₂ O ₃ powder and Y ₂ O ₃ powder at a molar ratio of 1:0.7 and 1:1.3, respectively, and an X-ray diffraction experiment of each sintered body. This is a diagram showing the diffraction pattern.

_Referring to Figure 1 _, when mixing the La ₂ O ₃ powder so that the molar ratio is greater than that of _the Y ₂ O ₃ powder, _{in the} It was confirmed that the purity of LaYO ₃ in the sintered body was low, as the diffraction pattern of was observed together.

In Figure 2, on the contrary, the molar ratio of the La ₂ O ₃ powder was smaller than the molar ratio of the Y ₂ O ₃ powder, and as a result of mixing so that the ratio was 1:1.3, a pattern of almost only LaYO ₃ was observed in the X-ray diffraction pattern of the sintered body. Therefore, as described above, in order to form the LaYO ₃ phase, it is desirable to control the ratio of _NY and N _La .

In a preferred embodiment of the present invention, the lanthanum oxide may be La ₂ O ₃ and the yttrium oxide may be Y ₂ O ₃ . LaYO ₃ compound sintered body, which is lanthanum-yttrium oxide, can be manufactured by mixing and sintering La ₂ O ₃ and Y ₂ O ₃ powder. In this case, the composition of the lanthanum-yttrium oxide may be represented by the following formula (1): there is.

[Formula 1]

La _a Y _b O ₃

In Formula 1, 1.8≤a+b≤2.3, and a/b is 0.7 to 1.0. a/b may be more preferably 0.9 to 1.0.

In Formula 1, a and b correspond to N _La and _NY defined above, respectively.

Lanthanum-yttrium oxide may form a perovskite structure of LaYO ₃ , and its chemical formula may be LaYO ₃ . Additionally, oxides that do not form a perovskite structure may have a form in which the La or Y element is partially substituted in the La ₂ O ₃ or Y ₂ O ₃ structure. Meanwhile, a+b that can be formed during the mixing and sintering process can be determined in the range of 1.8 to 2.3 depending on the incorporation of impurities and changes in the ternary oxide formation process.

When a/b is 1.0 or more, the ratio of lanthanum is too high, so there is a very high possibility that another phase is formed, and when a/b is less than 0.7, the ratio of yttrium is too high, so there is a very high possibility that Y ₂ O ₃ coexists.

The lanthanum oxide powder and yttrium oxide powder may each independently have an average particle diameter of 0.5 to 20 μm. Preferably, the lanthanum oxide powder and yttrium oxide powder may each independently have an average particle diameter of 0.5 to 10 μm.

The lanthanum oxide powder may preferably have an average particle diameter of 0.5 to 10 μm. If the average particle diameter of the lanthanum oxide powder is less than 0.5㎛, the unit price of the powder increases and mixing problems may occur due to fluidity issues. If the average particle diameter is more than 10㎛, the particles have a small surface area, so after sintering, the lanthanum oxide powder has a small surface area. The content of unreacted lanthanum oxide may increase. In particular, if the lanthanum oxide powder contains particles exceeding 20㎛, the particles have a small surface area, so the content of lanthanum oxide remaining after sintering may increase. This is the same for yttrium oxide powder.

In addition, the yttrium oxide powder may also preferably have an average particle diameter of 0.5 to 10 μm. If the average particle diameter of the yttrium oxide powder is less than 0.5㎛, the unit price of the powder will be high and there may be problems with mixing due to fluidity issues. The particles exceeding 10㎛ have a small surface area, so the yttrium oxide that has not reacted after sintering may be damaged. The content may increase.

In addition, the yttrium oxide powder preferably has a particle size of 20 μm or less. If particles exceeding 20㎛ are included, the particles have a small surface area, so the content of yttrium oxide remaining after sintering may increase.

Step 1) is preferably performed by mixing the lanthanum oxide powder and the yttrium oxide powder, performing a primary heat treatment at 400 to 1,100°C to remove impurities, and then crushing the heat-treated mixture again to produce a powder. It is advantageous. This is because there is a high possibility that impurities such as moisture will be contained during the storage process of the raw materials, and in this case, impurities may have a negative effect on the density and purity of the sintered body.

According to a preferred embodiment of the present invention, the reaction-reduced sintered body is a sintered body made of LaYO ₃ compound by molding and sintering the crushed powder mixture, and the molded body is dried and molded after mixing with the powder mixture solvent. It could be.

In addition, step 1) preferably involves mixing the lanthanum oxide powder and the yttrium oxide powder by milling them with a solvent, drying the mixed mixture to form granules, and molding the granules to form a molded body. It can also be performed using this method.

In this case, the solvent may preferably be water, but is not necessarily limited thereto. When water is used as a solvent, it can be advantageous for powder granulation and reduce manufacturing costs due to the low volatilization temperature and wettability of water. Additionally, when water is used as a solvent, water may be mixed in an amount of 30 to 60 parts by weight based on 100 parts by weight of the oxide powder mixture. If less than 30 parts by weight of water is mixed, the viscosity of the mixture may increase and mixing may not be done properly. If it exceeds 60 parts by weight, it may take a long time in the subsequent drying step, which may have the disadvantage of lowering productivity.

Milling can preferably be performed by ball milling. However, this is not necessarily the case, and any milling method commonly used in the industry can be adopted without limitation as it is advantageous for stirring lanthanum oxide powder and yttrium oxide powder.

A mixture can be prepared by milling for about 24 hours in the same manner as above, and then dried to remove the solvent.

Drying may preferably be by spray drying. By spray drying, the mixture can be prepared in the form of granules with an average diameter of about 30 to 100 μm.

When manufactured in the form of granules, it can be advantageous in producing molded bodies from a homogeneous mixture compared to directly molding the mixture in a slurry state. If the average diameter of the granules is less than 30㎛, there may be a problem with the homogeneity of the mixture. , if it exceeds 100㎛, there may be problems in manufacturing the molded body with the desired density, so it is preferable to form it to have a diameter within the above range.

More preferably, the average diameter of the granules may be 30㎛ to 70㎛.

According to a preferred embodiment of the present invention, the reaction-reduced sintered body uses water as a solvent, and the mixture is a mixture of lanthanum oxide powder, yttrium oxide powder, and water mixed by milling, and the molded body is formed by milling. The mixed mixture may be dried to form granules with an average diameter of 30 to 100 ㎛, and the granules may be molded.

Specifically, the molding can be performed by putting the mixture or granules obtained by drying the mixture into a mold shaped like a melting furnace to be manufactured and applying pressure.

In addition, the molding in step 1) may be performed by one-way pressure molding at a pressure of 50 MPa or more, two-way pressure molding, cold isostatic pressing (CIP), or hot isostatic pressing (HIP). Preferably, it may be cold isostatic pressing.

If the molding pressure is less than 50 MPa, the pores between powder particles or between granules are not sufficiently filled, so the density of the manufactured molded body decreases, which may lead to problems such as cracks at high temperatures.

The upper limit of the molding pressure is not particularly limited, but if a pressure exceeding 500 MPa is applied, manufacturing costs increase, so it is desirable to adjust it to 500 MPa or less.

In a preferred embodiment of the present invention, the sintering in step 2) is performed at a temperature of 900 to 1530°C, and is divided into two steps in which the temperature is first raised to the first temperature, and then the temperature is raised a second time to the second temperature for sintering. It can be done.

In addition, the sintering is preferably performed at normal pressure in an air atmosphere, and there is no need to apply an inert gas atmosphere or high pressure conditions.

Sintering can be performed under normal sintering conditions, and the method can also be performed by a typical ceramic powder sintering method. Preferably, the first temperature is 900 to 1330°C and the second temperature is 1380°C to 1530°C. It can be.

Therefore, a preferred sintering method is to increase the temperature of the molded body from room temperature to the first temperature at 0.5°C/min to 5°C/min, maintain the molded body at the first temperature for about 1 to 10 hours, and then heat the molded body again to the second temperature by 0.1°C/min. Secondary sintering may be performed by raising the temperature to ~1.0°C/min and maintaining it for 3 to 12 hours, and then cooling to room temperature at 1°C/min to 20°C/min.

Alternatively, according to another embodiment, the sintering in step 2) is performed in a single step at a temperature of 1380°C to 1530°C, but sintering may be performed by raising the temperature to the sintering temperature at a rate of 0.1°C/min to 10°C/min. there is.

The present invention also provides a reaction-reducing sintered body for a high-temperature furnace containing lanthanum-yttrium oxide having the composition of the following formula (1) in order to solve the above-mentioned problems.

[Formula 1]

La _a Y _b O ₃

In Formula 1, 1.8<a+b<2.3, and a/b is 0.7 to 1.0.

The reaction-reducing sintered body may be manufactured by the manufacturing method described above.

In a preferred embodiment of the present invention, the reaction-reduced sintered body may include lanthanum-yttrium oxide represented by Chemical Formula 1 in an amount of 50% by weight or more. If the content of lanthanum-yttrium oxide is less than 50% by weight, there may be a problem of deterioration of reaction reduction.

The reaction-reduced sintered body may have a density of 5.0 to 5.9 g/cm3. If the density is less than 5.0g/cm3, pores were not sufficiently removed during molding, and there may be a problem with the inherent characteristics of the molded body. If the density exceeds 5.9g/cm3, the molded body is highly contaminated with other elements. There may be a problem with the inherent properties of the molded body.

Additionally, the present invention provides a melting furnace containing the reaction-reducing sintered body as a refractory material.

The reaction-reduced sintered body contains lanthanum-yttrium oxide, so it is suitable for use as a melting furnace for melting high-temperature/high-reactivity materials because almost no reaction with the melt occurs even if high-temperature molten metal is included in the melting furnace. .

The melting furnace according to a preferred embodiment of the present invention includes the reaction-reducing sintered body as a liner of the melting furnace. In another form, the sintered body may be included as the body of the melting furnace, but considering manufacturing cost, it may be included as a body material of a conventional melting furnace such as graphite, and the sintered body may be a liner coated on the inner wall.

Hereinafter, the configuration and effects of the present invention will be described in more detail through examples. However, the scope of the present invention is not limited to the following examples, and the examples described below are only illustrative embodiments to enable a detailed understanding of the present invention, and parts that are not core components of the present invention may be explained by those skilled in the art. It can be easily implemented by adding, omitting, and substituting, and such modified embodiments are also naturally included in the technical spirit of the present invention.

<Example>

Example 1

La ₂ O ₃ powder (average particle diameter of about 4-10㎛) and Y ₂ O ₃ powder (average particle diameter of 0.8㎛) were each prepared by pre-heating at 1,000°C for 30 minutes to remove impurities.

The La ₂ O ₃ powder and Y ₂ O ₃ powder that had undergone the above preheating process were mixed at a ratio of 1:0.7 based on mole ratio, and the mixed powder and distilled water were mixed again at a weight ratio of 2:1 to form a slurry, which was then milled through a ball mill. A powder mixture was produced by mixing for 24 hours.

The mixture sufficiently mixed through milling was spray-dried using a typical spray dryer to form granules. The average diameter of the granules was about 50 μm.

The granules were put into a cylindrical rubber mold, and cold isostatic molding was performed by applying a pressure of about 100 MPa. Molding was performed for about 1 hour to produce a La ₂ O ₃ +Y ₂ O ₃ ceramic molded body.

The molded body was heated at a temperature increase rate of 1°C/min to 1,000°C in an air atmosphere at normal pressure, and then maintained at the temperature for 10 hours. Afterwards, the temperature was again raised to 1,500°C at a temperature increase rate of 0.5°C/min, and sintering was performed for 6 hours.

After sintering, the LaYO ₃ sintered body was manufactured by cooling to room temperature at a rate of 2°C/min.

However, as a result of the experiment in Example 1, a sintered body of LaYO ₃ was not obtained, as shown in the X-ray diffraction analysis results of FIG. 1.

Examples 2 to 4

A sintered body was manufactured in the same manner as in Example 1, except that the ratio of La ₂ O ₃ powder and Y ₂ O ₃ powder was changed as shown in Table 1 below. As a result of the experiments of Examples 2 to 4, a sintered body of LaYO ₃ was obtained.

Examples 5 to 8

A sintered body was manufactured in the same manner as in Example 1, except that the maximum value of the second temperature during the second sintering was changed as shown in Table 1 below.

Comparative Example 1

Y ₂ O ₃ material is a commercially available material that reduces the reaction of U-Zr-based melts and was selected as the first comparative material. Y ₂ O ₃ was prepared by granulating Y ₂ O ₃ powder with a particle diameter of 10 μm to 100 μm and having a purity of 95% or more in the same manner as in Example 1 to prepare a granular powder with a diameter of about 50 μm. The prepared Y ₂ O ₃ powder was manufactured into a molded body of the desired shape using cold isostatic pressing in the same manner as in Example 1. Afterwards, it is sintered at a temperature of 1600℃ or higher. At this time, under molding conditions of 1600℃, the general Y ₂ O ₃ sintered body has a relative density of about 97% (actual density relative to the theoretical density value of the Y ₂ O ₃ sintered body without defects). ratio). If it is necessary to manufacture densified Y ₂ O ₃ sintered body, a sintering temperature of 1600°C or higher is used. General sintering conditions utilize a temperature increase rate of 5°C/min or lower than the above temperature increase rate, and the sintering time is maintained for at least 3 hours. There are no special restrictions on the cooling rate when cooling after sintering.

division La ₂ O ₃ powder Y ₂ O ₃ powder La ₂ O ₃ , Y ₂ O ₃
mass ratio La ₂ O ₃ , Y ₂ O ₃ mixture and solvent weight ratio Molding method
(Method/Conditions) highest sintering temperature Example 1 4~10㎛ 0.8㎛ 1:0.7 2:1 CIP/100MPa 1,500℃ Example 2 4~10㎛ 0.8㎛ 1:1.1 2:1 CIP/100MPa 1,500℃ Example 3 4~10㎛ 0.8㎛ 1:1.2 2:1 CIP/100MPa 1,500℃ Example 4 4~10㎛ 0.8㎛ 1:1.3 2:1 CIP/100MPa 1,500℃ Example 5 4~10㎛ 0.8㎛ 1:1.3 2:1 CIP/100MPa 1,370℃ Example 6 4~10㎛ 0.8㎛ 1:1.3 2:1 CIP/100MPa 1,435℃ Example 7 4~10㎛ 0.8㎛ 1:1.3 2:1 CIP/100MPa 1,530℃ Example 8 4~10㎛ 0.8㎛ 1:1.3 2:1 CIP/100MPa 1,570℃ Comparative Example 1 - 10~100㎛ - 2:1 CIP/100MPa 1,600℃

<Experimental example>

Experimental Example 1: Elemental analysis and density of lanthanum-yttrium sintered body

The surface of each lanthanum-yttrium sintered body and lanthanum oxide sintered body prepared according to Examples 1 to 4 was cut and polished, and then the image of the sintered body was analyzed by X-ray diffraction analysis. As a result of the analysis, the LaYO ₃ perovskite structure could not be obtained in the sintered body of Example 1, and on the contrary, the LaYO ₃ perovskite structure could be obtained in the sintered body of Examples 2 to 4.

In Comparative Example 1, Y ₂ O ₃ sintered body could be obtained.

Experimental Example 2: Analysis of phase formation results

The phase formation results of each lanthanum-yttrium oxide sintered body prepared according to Examples 4 to 8 were analyzed using X-ray diffraction analysis.

As a result of the analysis, it was confirmed that a perovskite structure of LaYO ₃ was formed in Examples 4, 6, and 7. However, in the results of Example 5, sintering was not completed completely, so the phases of La ₂ O ₃ and Y ₂ O ₃ were formed, respectively. It was observed, and in Example 8, it was confirmed that a phase transformation occurred into a phase other than the perovskite structure of LaYO ₃ .

Experimental Example 3: Responsiveness evaluation results

Example 4, after placing the U-Zr-RE specimen on each sintered body manufactured according to Comparative Example 1 and Comparative Example 2, the U-Zr-RE specimen was melted in a melting furnace at 1500°C to confirm the reactivity with each sintered body. did. The results are shown in Table 2 below.

division Substrate sintered body melt Responsiveness Test Results Example 4 LaYO ₃ U-Zr-RE Very weak reaction between substrate and melt (almost no reaction) Comparative Example 1 Y ₂ O ₃ U-Zr-RE There is a weak reaction between the substrate and the melt.

As a result of the experiment, when the LaYO ₃ sintered body of Example 4 was used as a substrate and reacted with the U-Zr-RE melt, a very weak reaction was confirmed, so it was confirmed that almost no reaction occurred and the reaction reduction was excellent. On the other hand, it was confirmed that the Y ₂ O ₃ substrate of Comparative Example 1 caused a weak reaction with the melt. Therefore, it was found that when manufacturing a sintered body for a high-temperature furnace according to the present invention, the reaction with the melt on the wall of the high-temperature furnace is greatly reduced, making it advantageous to obtain a high-purity melt.

Claims (10)

1) preparing a mixture by mixing lanthanum (La) oxide powder and yttrium (Y) oxide powder with a solvent, and then molding the mixture to produce a molded body; and
2) sintering the molded body to produce a lanthanum-yttrium oxide sintered body;
In step 1), the lanthanum oxide powder and the yttrium oxide powder are mixed so that the molar ratio of lanthanum and yttrium satisfies the following condition equation 1: Method for producing a low-reaction sintered body for a high temperature furnace:
[Conditional expression 1]
1.0≤N _Y /N _La≤1.5
In Condition Equation 1, N _La represents the number of moles of lanthanum, and N _Y represents the number of moles of yttrium.
delete According to paragraph 1,
A method for producing a reaction-reducing sintered body for a high temperature furnace, characterized in that the lanthanum oxide powder and the yttrium oxide powder each independently have an average particle diameter of 0.5 to 20㎛.
According to paragraph 1,
The lanthanum-yttrium oxide has the chemical formula LaYO ₃ and is a compound having the composition of the following formula 1:
[Formula 1]
La _a Y _b O ₃
In Formula 1, 1.8≤a+b≤2.3, and a/b is 0.7 to 1.0.
According to paragraph 1,
In step 1), the mixture is heat-treated at a temperature of 400°C to 1,100°C, crushed to produce a powder, and then molded to form a molded body. A low-reaction sintered body for a high-temperature furnace. Manufacturing method.
According to clause 5,
In step 1), the powder is A method for producing a low-reaction sintered body for a high-temperature furnace, characterized by mixing with water and drying to form a granular phase with an average diameter of 30㎛ to 100㎛, and molding the granular phase.
According to paragraph 1,
The sintering in step 2) is performed at a first temperature in the range of 1380°C to 1530°C and a second temperature higher than the first temperature, and the temperature is first raised to the first temperature and primary sintering is performed at the first temperature, A method for producing a reaction-reduced sintered body for a high temperature furnace, characterized in that it is carried out in two steps: secondary heating to a second temperature and secondary sintering at the second temperature.
A low-reaction sintered body for a high-temperature furnace containing lanthanum-yttrium oxide having the chemical formula LaYO ₃ and the composition of the following formula 1:
[Formula 1]
La _a Y _b O ₃
In Formula 1, 1.8≤a+b≤2.3, and a/b is 0.7 to 1.0.
According to clause 8,
The reaction-reducing sintered body is a reaction-reducing sintered body for a high temperature furnace, characterized in that it contains 50% by weight or more of lanthanum-yttrium oxide represented by the formula (1).
According to clause 8,
The reaction-reduced sintered body is a reaction-reduced sintered body for a high-temperature furnace, characterized in that the density is 5.0 to 5.9 g/cm3.