JPH0859345A - Ziroconia combined sintered compact and its production - Google Patents

Abstract

PURPOSE: To obtain a zirconia combined sintered compact consisting of a rare earth metal oxide stabilized zirconia compsn. (Z) excellent in thermal shock resistance, especially resistance to shock by rapid heating to 1,800 deg.C, thermal stability and corrosion resistance to a molten metal and having high mechanical characteristics and chromi, etc., excellent in corrosion resistance to a molten metal as a component (M) to be combined. CONSTITUTION: This zirconia combined sintered compact consists of a zirconia compsn. (Z) made of baddeleyite, based on ZrO2 and contg. rare earth metal oxides (R2 O3 ), Al2 O3 and SiO2 , and chromi, magnesiachromia, magnesia-alumina and/or alumina-silica as a component (M) to be combined. The molar ratio of R2 O3 :ZrO2 in the compsn. Z is 1:99 to 5:95 and the compsn. Z has 0.05-20mol% Al2 O3 , content and 0.05-10mol% SiO2 content. The weight ratio of M:Z is 5:95 to 90:10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is mainly applied to dies and rolls.
TECHNICAL FIELD The present invention relates to a zirconia-based composite sintered body intended for ceramics heat-resistant parts such as lars and crucibles and refractories, and a method for producing the same. Further, the present invention is a "rare earth metal oxide-stabilized zirconia" having excellent thermal shock resistance, especially rapid thermal shock resistance up to 1800 ° C, excellent thermal stability, excellent corrosion resistance to molten metal, and high mechanical properties. TECHNICAL FIELD The present invention relates to a composite sintered body comprising a high quality component (Z) and a composite component (M) ″ having excellent corrosion resistance against molten metal, and a method for producing the same.

[0002]

_2. Description of the Related Art Sintered zirconia (ZrO ₂ ) materials have various mechanical properties, such as excellent heat resistance and corrosion resistance, low thermal conductivity, and excellent heat insulation. It is a material with advantages. On the other hand, chromia (especially Cr ₂ O ₃ composition), magnesia-chromia (especially MgCr ₂ O ₄ composition), magnesia-alumina (especially MgAl ₂ O ₄ , MgAl ₆ O ₁₀ and Mg ₂ Al ₂
Each of the O ₅ composition) and the alumina-silica (especially Al ₆ Si ₂ O ₁₃ composition) fired body is a material having excellent corrosion resistance to molten metal such as molten steel.

[0003]

Currently, the zirconia-based refractory material which has been industrially put into practical use is generally an electrofused zirconia prepared by electrofusing a stabilizer in a predetermined amount. Even if the crushed powder is molded and fired, fused zirconia can only be obtained with porosity having a porosity of about 20%, and mechanical properties such as bending strength are not necessarily satisfactory, and thermal shock resistance It could not be used for the one that required the property. Also known is a calcined zirconia obtained by calcining and stabilizing a zirconia raw material containing a stabilizer, but a zirconia-based refractory obtained by sintering the zirconia-based refractory is unlikely to have a high density and is also resistant to thermal shock. It was inferior. This is one of the causes that prevent widespread use
It has become one.

As a countermeasure against this, the present inventors have found, prior to the present invention, that "ZrO ₂ composed of baddelite is the main component, and Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ and Dy ₂ within a predetermined range are contained. O ₃ , Y ₂ O ₃ , Ho ₂ O ₃ , Er ₂
A zirconia-based sintered body containing one or more rare earth metal oxides selected from the group consisting of O ₃ and Yb ₂ O ₃ , and a predetermined range of Al ₂ O ₃ , SiO ₂ , and a boron compound, and a method for producing the same. . The invention according to "is proposed and applied for.

According to the invention of the above-mentioned application, thermal shock resistance
(Especially resistance to rapid heating shock up to 1800 ° C) and 150
A material having excellent long-term thermal stability at about 300 ° C and high mechanical properties can be obtained. However, this material has corrosion resistance to molten metals such as molten steel,
"Chromia (especially Cr ₂
O ₃ composition), magnesia-chromia (especially MgCr ₂ O ₄ composition),
Magnesia-alumina (especially MgAl ₂ O ₄ , MgAl ₆ O ₁₀ and Mg
₂ Al ₂ O ₅ composition) and alumina-silica (especially Al ₆ Si ₂ O ₁₃ composition) calcined products ”.

On the other hand, the above-mentioned chromia and magnesia
Each of the chromia, magnesia-alumina and alumina-silica fired bodies is a material that has excellent corrosion resistance to molten metals such as molten steel, but has particularly low thermal shock resistance and poor mechanical properties. Chromia and magnesia-chromia have a problem that it is difficult to obtain a dense fired product even when fired at a high temperature of 1700 ° C. or higher.

The present invention has been made in view of the above drawbacks and problems, and the purpose thereof is as follows.
With a "rare earth metal oxide-stabilized zirconia component (Z)", which has excellent thermal shock resistance, especially rapid heating shock resistance up to 1800 ° C, excellent corrosion resistance to molten metal, and thermal stability and high mechanical properties. To provide a composite sintered body "comprising a composite component (M) having excellent corrosion resistance against molten metal", and secondly, having a porosity of 25% or less, 150 to 3
The third object is to provide the above composite sintered body, which has the characteristic that deterioration of the sintered body does not easily occur even if it is used in the air, water and steam at a temperature of 00 ° C for a long time. It is an object of the present invention to provide a method capable of easily manufacturing a composite sintered body having the above-mentioned structure with simple steps.

[0008]

A zirconia-based sintered body according to the present invention comprises: ZrO ₂ composed of badderite as a main component,
Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O ₃ , Y ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ and
A zirconia component (Z) containing one or more rare earth metal oxides selected from the group consisting of Yb ₂ O ₃ and a predetermined range of Al ₂ O ₃ , SiO ₂ (or a boron compound); Chromia, magnesia-chromia, magnesia-
One or more composite components (M) selected from the group consisting of alumina and alumina-silica are mixed and sintered, whereby the first and second objects are achieved. To provide a composite sintered body.

Further, the method for producing a zirconia-based composite sintered body according to the present invention comprises: a zirconia-based component (Z) prepared by compounding, kneading, calcining and crushing so as to obtain a predetermined raw material composition. Raw powder prepared by kneading powder and composite component (M) powder at a predetermined ratio
After molding the (raw material mixture), or-to directly mix the raw material powder of the zirconia component (Z) prepared by blending and kneading so as to have a predetermined raw material composition (M)
The raw material mixture prepared by kneading the powder in a predetermined ratio is molded and then sintered at a predetermined temperature (1400 to 1800 ° C.), thereby achieving the third object.

That is, the zirconia-based sintered body according to the present invention is characterized in that "the main component is ZrO ₂ composed of badderite, and Nd
₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O ₃ , Y ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ and Yb
One or more rare earth metal oxide selected from the group consisting of _{2 O 3 (R 2 O 3} ) and containing Al ₂ O ₃ and SiO ₂ (or, further comprising a boron compound) zirconia component (Z ) And chromia, magnesia-chromia, magnesia-alumina and alumina-silica.
A composite sintered body comprising one or more composite components (M), wherein the molar ratio of the rare earth metal oxide (R ₂ O ₃ ) to ZrO ₂ is
(R ₂ O ₃ / ZrO ₂ ) is 1/99 to 5/95, and the content of Al ₂ O ₃ is 0.05 to 20 mol% and the content of SiO ₂ is 0.05 to 10 mol%.
(Or, further, the content of the boron compound is 0.05 to 10 mol% in terms of boron (B)) and is a zirconia component (Z).
And the weight ratio (M / Z) of the composite component (M) is 5/95 to 90.
A zirconia-based composite sintered body characterized by being / 10. (Claims 1 and 2) is the main point.

Further, the method for producing a zirconia-based sintered body according to the present invention is described as follows: "ZrO ₂ composed of badderite is used as a main component, and Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ as a stabilizer, Dy ₂ O ₃ , Y ₂
1 selected from the group consisting of O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ and Yb ₂ O ₃
Or two or more rare earth metal oxides (R ₂ O ₃ ) and Al ₂ O ₃ and S
A zirconia component (Z) containing iO ₂ (or further containing a boron compound) and one or more selected from the group consisting of chromia, magnesia-chromia, magnesia-alumina and alumina-silica. Complex component (M)
(1) The rare earth metal oxide (R ₂ O ₃ ) and ZrO ₂ have a molar ratio (R ₂ O ₃ / ZrO ₂ ) of
1/99 to 5/95, said Al ₂ O ₃ is 0.05 to 20 mol%, said SiO ₂
Is 0.05 to 10 mol% (or further, the boron compound is 0.05 to 10 mol% in terms of boron (B)),
A step of preparing a powder composed of a zirconia component (Z) by kneading, calcination and crushing, (2) a powder of the composite component (M) to the zirconia component (Z) powder and a weight ratio (M / Z) is 5/95
A step of preparing a raw material mixture by kneading at a ratio of 90/10,
Alternatively, (3) the molar ratio of the rare earth metal oxide (R ₂ O ₃ ) and ZrO ₂ (R ₂ O ₃ / ZrO ₂ ) is 1/99 to 5/95, and the Al ₂ O ₃ is 0.05 to 20.
Mol%, the zirconia component (Z) raw material powder blended so that the SiO ₂ is 0.05 to 10 mol% (or further the boron compound is 0.05 to 10 mol% in terms of boron (B)), The weight ratio (M / Z) of the powder of the composite component (M) is 5 directly.
/ 95 to 90/10, a step of preparing a raw material mixture by kneading, (4) a step of molding the raw material mixture of (2) or (3),
(5) A method for producing a zirconia-based composite sintered body, comprising the step of firing the above-mentioned formed body at 1400 to 1800 ° C. (Claim 5).

The zirconia-based composite sintered body of the present invention and the method for producing the same will be described in detail below. First, the composite sintered body “comprising the zirconia component (Z) and the composite component (M)” according to the present invention will be described. As the zirconia component (Z) in the present invention, Zr composed of badderite is used.
O ₂ as a main component, Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O ₃ , Y ₂ O ₃ ,
One or more rare earth metal oxides (R ₂ O ₃ ) selected from the group consisting of Ho ₂ O ₃ , Er ₂ O ₃ and Yb ₂ O ₃ are used as a stabilizer.

Regarding the compounding ratio of the stabilizer (R ₂ O ₃ ), the molar ratio with ZrO ₂ (R ₂ O ₃ / ZrO ₂ ) is 1/99 to 5/95, and the preferable range is It is 1.5 / 98.5 to 4/96. R ₂ O ₃ /
When the ZrO ₂ molar ratio is less than 1/99, cracks occur in the obtained composite sintered body (see composition No. 8 in Tables 1 and 4 below), and conversely 5/95.
If it exceeds, the composite sintered body having a sufficient mechanical strength cannot be obtained (see composition No. 13 in Tables 1 and 4 below), which is not preferable.

As a stabilizer for the zirconia component, a rare earth metal oxide having an ionic radius smaller than Nd is used.
When La ₂ O ₃ and Pr ₆ O ₁₁ were used alone or as a mixture thereof, microcracks were generated during firing, and a composite sintered body having sufficient mechanical properties could not be obtained. However, the stabilizers used in the present invention (Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O
₃ , Y ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O _3, and one or more rare earth metal oxides selected from the group consisting of Yb ₂ O ₃ ) 30 mol%
When the following were replaced with La ₂ O ₃ and Pr ₆ O _11, etc., no problem of deterioration in mechanical properties was observed. Therefore, this case is also included in the present invention.

Further, Eu ₂ O ₃ , Tb ₂ O ₃ , Tm ₂ O ₃ , Lu ₂ O ₃ and Sc ₂ O
Even when using a rare earth metal oxide such as ₃ as a stabilizer, an effect equivalent to that of the composite sintered body according to the present invention is recognized, but such a rare earth metal oxide is industrially expensive. It is not preferable because it is difficult to use.

The "baddelite" used as a raw material for zirconia is the name of zirconium oxide minerals and is produced with zircon and the like. One example of the analysis value is CaO; 0.06, Fe. ₂ O ₃ ; 0.82, SiO ₂ ; 0.19,
ZrO ₂ ; 98.90. In addition, when high-purity zirconia separated and refined from ores such as baddelite and zircon (a method of forming an aqueous solution and removing impurities, etc.) is used, excellent thermal shock resistance characteristics which are the objectives of the present invention cannot be obtained. It turns out.

In the zirconia component (Z) of the present invention,
The addition of Al ₂ O ₃ and SiO ₂ facilitates the sintering of the raw material mixture, enables firing at low temperatures, and contributes greatly to the improvement of thermal shock resistance and mechanical properties. It is also possible to reduce the amount.

The addition amount of Al ₂ O ₃ (content) decreases the strength exceeds 20 mol% (see the composition of the following Table l, 4 No.17), whereas it is less than 0.05 mol%, Al ₂ O The effect of addition of ₃ cannot be obtained (see composition No. 14 in Tables 1 and 4 below). Further, when the content of SiO ₂ exceeds 10 mol%, the strength is remarkably reduced (see composition No. 21 in Tables 1 and 4 below), while when it is less than 0.05 mol%, the effect of adding SiO ₂ is obtained. No (Composition N in Tables 1 and 4 below)
o.18).

Therefore, in the zirconia component (Z) of the present invention, Al ₂ O ₃ : 0.05 to 20 mol% and SiO ₂ : 0.05 to 10 mol% are preferable, and Al ₂ O ₃ is more preferably 0.1 to 10 mol%. Mol%, SiO ₂ is 0.05 to 5 mol%. These additives are
In addition to oxides of additional components (Al, Si), similar effects can be obtained by adding nitrides, carbides, hydroxides, etc., and use of such raw materials is also included in the present invention. Is.

Further, the zirconia component (Z) of the present invention preferably contains a boron compound in its raw material composition. Explaining this boron compound, 20
As a result of observing the bending strength and the surface structure of the sample subjected to the underwater test at 0 ° C for 250 hours, a large decrease in strength was observed in the sintered body containing no boron compound, and many microcracks were also observed on the sample surface. Was observed. On the other hand, in the sintered body to which the boron compound was added, the above cracking phenomenon was not observed, and the strength of the sample before the test was different depending on whether the boron compound was added or not. The improvement in strength was clearly recognized.

From these test results, it was found that the thermal stability of the sintered body can be improved by adding the boron compound. Therefore, in the sintered body according to the present invention,
Particularly when heat stability is required, it is preferable to add a boron compound.

However, even when a boron compound is contained, if the content thereof is less than 0.05 mol% in terms of boron (B), the effect of the addition of the boron compound is not observed, and conversely 10 mol% If it is added over the range, the initial bending strength tends to be lowered (see composition No. 25 in Tables 2 and 5 below). From this, in the zirconia component (Z) of the present invention, the addition amount of the boron compound is preferably 0.05 to 10 mol% in terms of boron (B), more preferably 0.05 to
5 mol%.

As the above-mentioned boron compound, boron oxide,
Boron nitride, boron carbide, or Nd, Sm, Gd, Dy,
A metal boride other than Y, Ho, Er and Yb (for example, a metal boride composed of Zr as a main component or Al as an additional component) can be used. Incidentally, in the zirconia component (Z) of the present invention, such a boron compound is not an essential additive component. The reason is that the zirconia component (Z) defined in the present invention is excellent in thermal shock resistance and mechanical properties, even if it does not contain a boron compound, and is excellent in industrial properties. This is because it can be a high-value product (composition No. in Tables 1 and 5 below).
22).

The composite sintered body according to the present invention is selected from the group consisting of chromia, magnesia-chromia, magnesia-alumina and alumina-silica as the zirconia component (Z) having the above-mentioned specific composition. One or two or more composite components (M) are mixed and fired, and the mixing ratio of the zirconia component (Z) and the composite component (M) is 5 by weight ratio (M / Z). / 95 to 90/10 (preferably 20 /
80-70 / 30).

If this ratio exceeds 90/10, a dense sintered body cannot be obtained and the thermal shock resistance and mechanical strength are poor (composition Nos. 26 and 27 in Tables 2 and 3 and Tables 5 and 6 below). , 35, 36, 46, 4
7, 55, 56) and less than 5/95, the corrosion resistance to molten metal is poor (composition Nos. In Tables 2 and 3 and Tables 5 and 6 below).
33, 34, 43, 54, 63)), which is not preferable. The composite component (M) used in the present invention includes, for example, chromium oxide (Cr ₂ O ₃ ) as a raw material for the chromic component, and electrofused picromchromite (M as a raw material for the magnesia-chromia component.
gCr ₂ O ₄ ), magnesia-sintered spinel (MgAl ₂ O ₄ , MgAl ₆ O ₁₀ and Mg ₂ Al ₂ O ₅ ) as a raw material for the alumina component, and natural and synthetic mullite (A as a raw material for the alumina-siliceous component).
l ₆ Si ₂ O ₁₃ ) is preferred, but the invention is not limited to the use of these raw materials.

The zirconia-based composite sintered body according to the present invention is
It has a porosity of 25% or less, and has a property that deterioration of the sintered body is unlikely to occur during long-term use in air, water or steam at a temperature of 150 to 300 ° C.

The zirconia-based composite sintered body according to the present invention will be described in detail later, but the zirconia-based component (Z) is used.
A sintered body having a microstructure in which crystal grains of "a component mainly composed of ZrO ₂ and a rare earth metal oxide (R ₂ O ₃ )" and crystal grains of a composite component (M) are present in a matrix form. .

Next, the method for producing the zirconia-based composite sintered body according to the present invention will be described. First, a raw material mixture is prepared. The preparation method is as follows: As the zirconia component (Z), blended and kneaded so as to have the above-mentioned predetermined raw material composition, calcined and crushed to obtain a powder composed of the zirconia component (Z) in advance. A method of preparing and kneading the powder and the composite component (M) powder in a predetermined ratio to prepare: a zirconia component (Z) blended so as to have a predetermined raw material composition without calcination as described above The raw material mixed powder can be directly kneaded with the powder of the composite component (M) at a predetermined ratio to prepare.

Next, the obtained raw material mixture is molded, and the molded body is molded in a temperature range of 1400 to 1800 ° C. (preferably 1500 to 170).
Sintering is performed within a temperature range of 0 ° C.) to produce a target composite sintered body. If the sintering temperature is less than 1400 ° C, densification will not proceed
(Refer to “1350 ° C.” of Composition Nos. 11 and 39 in Tables 4 and 5 below). On the other hand, when the temperature exceeds 1800 ° C., a high-strength sintered body cannot be obtained due to abnormal grain growth of crystal grains. This is not preferable (see “1850 ° C.” in Composition Nos. 11 and 39 of Tables 4 and 5 below).

The zirconia-based composite sintered body according to the present invention obtained by the above composition and manufacturing method has a porosity of 25%.
It has the following characteristics, and it is difficult for deterioration of the sintered body to occur during long-term use in air, water or water vapor at a temperature of 150 to 300 ° C. When the porosity exceeds 25%, not only the penetration of molten metal and the reaction therewith increase, but also the bending strength decreases.

The zirconia-based composite sintered body according to the present invention is
As a result of observation by a scanning electron microscope and analysis by electron probe microanalysis, zirconia component (Z)
It was confirmed that the crystal particles composed of "mainly ZrO ₂ and rare earth metal oxide (R ₂ O ₃ ) component" and the crystal particles composed of composite component (M) have a microstructure in which they are present in a matrix form. .

As an example, a composite sintered body sample “composite component (M)” obtained by firing at 1600 ° C. with the composition “No. 11” shown in Table 1 below, which is an example of the present invention, was used as a fusion component. An electron micrograph showing the crystal structure (microstructure) of "a mixture of chromochromite (MgCr ₂ O ₄ )" is shown in FIG. In the photograph of FIG. 1, the whitish part is zirconia, and the dark part is picrochromite.

FIG. 2 shows a powder X-ray diffraction pattern for the composite sintered body sample having the microstructure shown in FIG. In FIG. 2, ● indicates a peak attributed to the zirconia component, and ∘ indicates a peak attributed to the picrochromite component. The main peaks observed in Fig. 2 are the zirconia component and the fused picrochromite (MgCr
_The main peaks attributed to the ₂ O ₄ ) component and attributed to other solid solutions were not observed.

Furthermore, as another example, a composite sintered body sample "composite component (M)" obtained by firing at 1600 ° C. with the composition "No. 39" of Table 2 below, which is also an example of the present invention. FIG. 3 shows an electron micrograph showing the crystal structure (microstructure) of "a mixture of sintered spinel (MgAl ₂ O ₄ )". In the photograph of FIG. 3, the whitish part is zirconia and the dark part is spinel.

FIG. 4 shows a powder X-ray diffraction pattern for the composite sintered body sample having the microstructure shown in FIG. In FIG. 4, ● indicates a peak attributed to the zirconia component, and ○ indicates a peak attributed to the spinel component. The main peaks observed in FIG. 4 are, as described above, attributed to the zirconia component and the sintered spinel (MgAl ₂ O ₄ ) component, and to the respective other solid solutions.
Ku was not recognized.

[0036]

The composite sintered body according to the present invention has a zirconia component.
(Z) "a rare earth metal oxide-stabilized zirconia-based component composed of baddeleyite containing a predetermined amount of Al ₂ O ₃ and SiO ₂ (or Al ₂ O ₃ and SiO ₂ and a boron compound)", and chromia,
One or two selected from the group consisting of magnesia-chromia, magnesia-alumina and alumina-silica.
It is composed of one or more kinds of composite components (M), and has excellent thermal shock resistance (especially resistance to rapid heating shock up to 1800 ° C) and thermal stability, and also has excellent corrosion resistance against molten metal and high mechanical properties. A composite sintered body having characteristics can be provided.

[0037]

Next, examples of the present invention will be described together with comparative examples.
The present invention will be described more specifically, but the present invention is not limited to the following examples unless it exceeds the gist.

(Examples, Comparative Examples) Compositions shown in Tables 1 to 3
(Composition No. 1 to 70) so that the baddelite (ZrO ₂ ) having a purity of 98% or more, various rare earth metal oxides (R ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), silicon dioxide ( SiO ₂ ), boron oxide (B ₂ O ₃ ) are weighed (Al ₂ O _{3 in} baddelite, SiO ₂ are also included in the composition values in Tables 1 to 3), ion-exchanged water is used as a solvent, and a rubber lining -Kneading with a ZrO ₂ quality medium in a rumill, drying and calcination at 1000 ° C to prepare a powder consisting of a zirconia component.

This zirconia-based powder was mixed with electrofused picrochromite (MgCr ₂ O ₄ ) and sintered spinel (MgAl ₂ O) shown in Tables 1 to 3.
₄ , MgAl ₆ O ₁₀ and Mg ₂ Al ₂ O ₅ ), chromium oxide (Cr ₂ O ₃ ), and synthetic mullite (Al ₆ Si ₂ O ₁₃ ). After blending and kneading in the proportions shown in (3), 3% by weight of an acrylic copolymer resin was added for spray granulation to prepare a raw material granulated powder.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

The raw material granulated powder was subjected to C at a pressure of 1000 Kgf / cm ^2.
IP molding was performed and main firing was performed at the temperatures shown in Tables 4 to 6.
"Porosity" and "3-point bending strength" of each composite sintered body obtained (testing method for bending strength of fine ceramics: JIS R 1
Tables 4 to 6 show "values measured based on 601", "thermal stability", "heat shock resistance" and "molten steel penetration resistance".

The "porosity" of the sintered body was measured using a three-point bending strength measurement sample with reference to JIS R 2205. In addition, the "thermal stability" of the sintered body is the deterioration of the sintered body after the sintered body was placed in an autoclave and subjected to an aging test for 250 hours in hot water at 200 ° C. It was judged by observing the condition.

The "heat shock resistance" of the sintered body is 1800
It was put in an acetylene burner flame maintained at 0 ° C from the room temperature state directly and kept for 30 seconds, after which the state of cracking of the sintered body was observed and judged. The "melting steel penetration resistance" of the sintered body is 20
mm, outer diameter: 40 mm, height: 40 mm, bottom thickness: 10 mm, make a crucible, put steel material (JIS standard: S45C) in it, and set it to 1600 ° C.
After being held for 2 hours, the penetration depth from the surface of the molten steel was measured.

[0046]

[Table 4]

[0047]

[Table 5]

[0048]

[Table 6]

From Tables 4 to 6, in Examples containing the zirconia component and the composite component specified in the present invention within a predetermined range,
It can be understood that a composite sintered body having excellent thermal shock resistance, excellent molten steel penetration resistance (corrosion resistance to molten metal), thermal stability and high mechanical properties can be obtained. On the other hand, even if one of the predetermined ranges defined by the present invention is deviated, the sintered body of the present invention cannot be obtained.

For example, “R ₂ O ₃ / ZrO ₂ : 1 defined in the present invention is used.
Composition No. 8 (Y ₂ O ₃ / ZrO ₂ : 0.
In the comparative example of 5 / 99.5), the stabilizer Y ₂ O ₃ was present in a small amount, so cracks occurred, and in the comparative example of composition No. 13 (Y ₂ O ₃ / ZrO ₂ : 6/94) as well, Since the strength is low, the thermal shock resistance and the molten steel penetration resistance are poor, a desired sintered body cannot be obtained.

Even within the range of the R ₂ O ₃ / ZrO ₂ molar ratio specified in the present invention, composition Nos. 14, 17, 18, 21 in which Al ₂ O ₃ and SiO ₂ are out of the predetermined ranges. In this case, the bending strength is low, the thermal shock resistance or the molten steel penetration resistance is poor, and a desired sintered body cannot be obtained. Furthermore, in the composition No. 25 (B ₂ O ₃ content: 15 mol%) in which the boron compound (B ₂ O ₃ ) is out of the predetermined range, not only the thermal stability is poor, but also the bending strength is 3.4 Kgf / mm. ^It was extremely low at ^2, and was inferior in thermal shock resistance and molten steel penetration resistance. The composition No. 22 does not contain B ₂ O ₃ , and therefore has high strength although inferior in thermal stability,
The thermal shock resistance and molten steel penetration resistance were good.

On the other hand, the composition N in which the weight ratio of the zirconia component and the composite component is outside the predetermined range (5/95 to 90/10) of the present invention.
o.33, 34, 43, 54, 63 are inferior in molten steel penetration resistance and have composition N
Nos. 26, 27, 35, 36, 46, 47, 55, and 56 are inferior in thermal shock resistance, and a desired sintered body cannot be obtained.

Further, the molar ratio of the stabilizer R ₂ O ₃ and ZrO ₂ is within the predetermined range of the present invention and within the predetermined range of Al ₂ O ₃ , SiO ₂ and the boron compound (B ₂ O ₃ ). Using the raw material mixture prepared as described above, and even if the weight ratio of the zirconia component and the composite component is within the predetermined range of the present invention, under conditions outside the range of 1400 to 1800 ° C. under the firing conditions. However, the desired sintered body cannot be obtained. That is, outside the range specified in the present invention
Comparative Example (composition No. 11 in Table 4,
In the composition No. 39) of Table 5, the bending strength is low, the thermal stability and the resistance to molten steel penetration are poor, and a desired sintered body cannot be obtained.

The above examples were prepared by kneading the powder of the zirconia component prepared by compounding, kneading, calcining and crushing and the composite component powder at a predetermined ratio so as to obtain the predetermined raw material composition. After molding with the raw material powder
It is about the composite sintered body obtained by sintering at ~ 1800 ℃), the zirconia component and the composite component were directly blended and kneaded so as to have a predetermined raw material composition, and prepared. The same result (physical property value, microstructure and powder X-ray) was obtained for the composite sintered body obtained by sintering the zirconia component-composite component raw material powder and then sintering it at a predetermined temperature (1400 to 1800 ° C). (Diffraction) was obtained.

[0055]

As described in detail above, the present invention is based on Al ₂ O ₃
Rare earth metal oxide-stabilized zirconia component consisting of "badderite" containing SiO ₂ (or Al ₂ O ₃ , SiO ₂ and boron compound) and "chromia, magnesia-chromia, magnesia-alumina and alumina" -One or more composite components selected from the group consisting of siliceous materials "
It is a composite sintered body consisting of, and this sintered body has excellent thermal shock resistance and thermal stability, excellent corrosion resistance to molten metal, and high mechanical properties. it can.

In particular, it has resistance to rapid heating shock up to 1800 ° C. and excellent corrosion resistance against molten metal, and is mainly applied to ceramics heat-resistant parts such as dies, rollers, crucibles and refractories. A suitable zirconia-based composite sintered body can be provided, and its industrial utility is extremely large.

[Brief description of drawings]

FIG. 1 is an electron micrograph showing a crystal structure of a composite sintered body sample “mixed with electrofused picrochromite (MgCr ₂ O ₄ ) as a composite component (M)” which is one example of the present invention.

FIG. 2 is a view showing a powder X-ray diffraction pattern of the composite sintered body sample of FIG.

FIG. 3 is an electron micrograph showing a crystal structure of a composite sintered body sample “a mixture of sintered spinel (MgAl ₂ O ₄ ) as a composite component (M)” which is another embodiment of the present invention.

FIG. 4 is a view showing a powder X-ray diffraction pattern of the composite sintered body sample of FIG.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C04B 35/42 101 35/443 C04B 35/18 C 35/44 101

Claims (5)

[Claims] 1. A main component is ZrO ₂ composed of badderite, and Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O ₃ , Y ₂ O ₃ , Ho ₂ O ₃ and Er ₂ O _{3 are} contained.
And one or more rare earth metal oxides (R ₂ O ₃ ) selected from the group consisting of Yb ₂ O ₃ and a zirconia component (Z) containing Al ₂ O ₃ and SiO ₂ , and chromia, magnesia -One or more composite components (M) selected from the group consisting of chromia, magnesia-alumina and alumina-silica
A rare earth metal oxide
The molar ratio (R ₂ O ₃ / ZrO ₂ ) of (R ₂ O ₃ ) and ZrO ₂ is 1/99 to 5/95, and the content of Al ₂ O ₃ is 0.05 to 20 mol%, SiO ₂ A zirconia component (Z) having a content of 0.05 to 10 mol%,
The weight ratio (M / Z) of the composite component (M) is 5/95 to 90/10.
A zirconia-based composite sintered body characterized by: _{2. A} main component is ZrO ₂ composed of badderite, and Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O ₃ , Y ₂ O ₃ , Ho ₂ O ₃ and Er ₂ O _{3 are} contained.
And one or more rare earth metal oxides (R ₂ O ₃ ) selected from the group consisting of Yb ₂ O ₃ and a zirconia component (Z) containing Al ₂ O ₃ , SiO ₂ and a boron compound, and chromia Of a rare earth metal oxide, which is a composite sintered body comprising one or more composite components (M) selected from the group consisting of quality, magnesia-chromia, magnesia-alumina and alumina-silica. The molar ratio (R ₂ O ₃ / ZrO ₂ ) of (R ₂ O ₃ ) and ZrO ₂ is
1/99 to 5/95, and the content of Al ₂ O ₃ is 0.05 to 20 mol%, the content of SiO ₂ is 0.05 to 10 mol%, and the content of boron compound is converted to boron (B). The weight ratio of the zirconia component (Z), which is 0.05 to 10 mol% in total, to the above composite component (M)
A zirconia-based composite sintered body characterized in that (M / Z) is 5/95 to 90/10. 3. The composite sintered body has a porosity of 25% or less, and deterioration of the sintered body does not easily occur even when used for a long time in the air, water and steam at a temperature of 150 to 300 ° C. The zirconia-based composite sintered body according to claim 1 or 2, which has characteristics. 4. The zirconia component (Z) "mainly Zr
It is characterized in that it has a microstructure in which crystal grains consisting of a component "comprising O ₂ and a rare earth metal oxide (R ₂ O ₃ )" and crystal grains consisting of the above composite component (M) are present in a matrix form. The zirconia-based composite sintered body according to claim 1, 2 or 3. 5. Nd ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O ₃ and Y ₂ as a stabilizer containing ZrO ₂ composed of badderite as a main component.
1 selected from the group consisting of O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ and Yb ₂ O ₃
Or two or more rare earth metal oxides (R ₂ O ₃ ) and Al ₂ O ₃ and S
A zirconia component (Z) containing iO ₂ (or further containing a boron compound) and one or more selected from the group consisting of chromia, magnesia-chromia, magnesia-alumina and alumina-silica. Complex component (M)
(1) The rare earth metal oxide (R ₂ O ₃ ) and ZrO ₂ have a molar ratio (R ₂ O ₃ / ZrO ₂ ) of
1/99 to 5/95, said Al ₂ O ₃ is 0.05 to 20 mol%, said SiO ₂
Is 0.05 to 10 mol% (or further, the boron compound is 0.05 to 10 mol% in terms of boron (B)),
A step of preparing a powder composed of a zirconia component (Z) by kneading, calcination and crushing, (2) a powder of the composite component (M) to the zirconia component (Z) powder and a weight ratio (M / Z) is 5/95
A step of preparing a raw material mixture by kneading at a ratio of 90 to 90/10, or (3) a molar ratio of the rare earth metal oxide (R ₂ O ₃ ) and ZrO ₂ (R ₂ O ₃ / ZrO ₂ ). Is 1/99 to 5/95, the Al ₂ O ₃ is 0.05 to 20
Mol%, the zirconia component (Z) raw material powder blended so that the SiO ₂ is 0.05 to 10 mol% (or further the boron compound is 0.05 to 10 mol% in terms of boron (B)), The weight ratio (M / Z) of the powder of the composite component (M) is 5 directly.
/ 95 to 90/10, a step of preparing a raw material mixture by kneading, (4) a step of molding the raw material mixture of (2) or (3),
(5) A method for producing a zirconia-based composite sintered body, comprising the step of firing the above-mentioned formed body at 1400 to 1800 ° C.