JP2001294480A - Ceramic composite materials - Google Patents

Abstract

(57) [Problem] To provide a ceramic composite material having a bending strength of 700 MPa or more at a temperature of 1700 ° C. SOLUTION: A) aluminum oxide, B) composite oxide of aluminum oxide and rare earth metal oxide, or composite oxide of aluminum oxide, rare earth metal oxide and zirconium oxide, C) zirconium oxide or oxidation It is a melt-solidified body composed of three oxide crystal phases of a composite oxide of zirconium and a rare earth metal oxide, and has a chemical composition of 55 to 80 mol% as aluminum oxide, rare earth metal oxide and zirconium oxide, respectively. , 10
A ceramic composite material in the range of 35 mol% and 10-35 mol%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to maintain mechanical strength over a wide temperature range from room temperature to high temperature, and to provide 1500
The present invention relates to a ceramic composite material that can be used as a structural material or a functional material even in an environment exposed to a high temperature of not less than ° C.

[0002]

2. Description of the Related Art SiC or Si ₃ N ₄ is expected as a ceramic material that can be used at a high temperature, and many studies have been made toward its use. However, these materials do not exhibit sufficient high-temperature properties, and their practical application is not yet advanced. One of the solutions is to use SiC / SiC by chemical vapor impregnation method developed by SEP.
Composite materials have been spotlighted as the world's highest temperature materials at the present time, and research and development on their use is underway. However, since this material is a non-oxide material, its oxidation resistance is limited, and its use temperature is 1400.
C. or less, and it is essentially difficult to overcome this disadvantage.

On the other hand, materials having excellent oxidation resistance include:
There are oxide-based ceramics. However, oxide-based ceramics are generally considered to have a drawback that they cannot be used as a structural material under an environment where a high load acts, since they are easily deformed at high temperatures. However, oxide-based ceramics, on the other hand, can be considered to be expected to have a wide range of applications as high-temperature structural materials if mechanical properties are improved and this disadvantage is overcome.

The present inventors have been developing oxide ceramics having improved mechanical properties at high temperatures, and have already developed an aluminum oxide phase and a composite oxide composed of aluminum oxide and a rare earth metal oxide. A ceramic composite material comprising a solidified body of a composite phase with a solid phase has been proposed (for example, JP-A-7-149597, JP-A-7-14997).
187893, JP-A-8-81257, and JP-A-9-67194. These ceramic composite materials are epoch-making in that they overcome the drawback of conventional sintered materials, namely, the reduction in strength at high temperatures.
However, one of the materials disclosed therein, Al ₂
O ₃ -Y ₃ Al ₅ O _12, the bending strength at high temperature (1600 ° C.) is 410 MPa, considering the application to a gas turbine blade, it is necessary to further improve the strength. Similarly, the strength of Al ₂ O ₃ —Er ₃ Al ₅ O ₁₂ also needs to be improved. On the other hand, Al ₂ O ₃
-Gd ₂ O ₃ composite ceramic exhibits excellent flexural strength even at 1600 ° C., the material melting point 1760
° C, there is a problem that it cannot be used at a temperature of 1700 ° C or higher.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a ceramic composite material exhibiting a higher high-temperature strength than the above-mentioned conventional products. Specifically, 1600 ° C.-1
An object of the present invention is to develop a ceramic composite material having a bending strength of, for example, 700 MPa or more at a temperature of 700 ° C.

[0006]

Means for Solving the Problems The present inventors have developed a composite material in which aluminum oxide, rare earth metal oxide and zirconium oxide are present as a solidified solid or composite oxide phase.
The present inventors have found that a ceramic composite material has been achieved which has solved the above problems, and has completed the present invention. That is, the present invention provides: A) aluminum oxide (A phase); B) a composite oxide of aluminum oxide and a rare earth metal oxide; or a composite oxide of aluminum oxide, a rare earth metal oxide and zirconium oxide (B phase). ), C) zirconium oxide or a composite oxide (C phase) of zirconium oxide and a rare earth metal oxide, which is a melt-solidified body composed of three oxide crystal phases, which are composed of aluminum oxide and rare earth metal 55 to 80 mol% as oxide and zirconium oxide, respectively,
The present invention relates to a ceramic composite material characterized by being in the range of 0 to 35 mol% and 10 to 35 mol%. Hereinafter, the present invention will be described in detail.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The ceramic composite material of the present invention comprises aluminum oxide, a rare earth metal oxide and zirconium oxide as chemical components, and structurally, these oxides are used alone and / or in other oxides. A solidified material that forms a composite oxide with a substance and is dispersed and present as a single crystal phase or a polycrystalline phase without forming a colony or a grain boundary phase. The present inventors comprise a solidified body composed of two or three or more oxide crystal phases including an aluminum oxide phase and a rare earth metal oxide or a composite oxide phase of aluminum oxide and a rare earth metal oxide. In the process of studying ceramic composites, unexpectedly, zirconium oxide or zirconium oxide and rare earth metal oxides, together with an aluminum oxide phase and a phase of a rare earth metal oxide or a composite oxide of aluminum oxide and a rare earth metal oxide, were unexpectedly discovered. The coexistence of the composite oxide phase in an amount within a specific range provides a crystal structure that is significantly finer than the conventional solidified ceramic composite material,
The present inventors have found that the high-temperature strength at 0 ° C. can be significantly improved, and have completed the present invention. In a solidified body composed of two phases of an aluminum oxide phase and a rare earth metal oxide or a composite oxide phase of aluminum oxide and a rare earth metal oxide, each crystal phase generally has a size of 10 μm to 250 μm.
On the other hand, in the three-phase system of the present invention, a fine structure having a size of 0.1 to 10 μm is generally obtained. ) And FIG.
It is clear from comparison of the micrographs of (conventional example). According to the study of the present inventors, although the reason is not clear, the amount of zirconium oxide within a specific range with respect to the aluminum oxide phase and the phase of the rare earth metal oxide or the composite oxide of aluminum oxide and the rare earth metal oxide is determined. Alternatively, the crystal structure of the solidified body was remarkably refined by adding a phase of a composite oxide of zirconium oxide and a rare earth metal oxide. Specifically, in order to obtain such a fine crystal structure, the chemical component composition of the solidified body is aluminum oxide,
55 to 80 mol%, 10 to 35 mol% and 10 to 35 mol% as the rare earth metal oxide and zirconium oxide, respectively.
It needs to be in the range of mol%. If the ratio is outside the above range, a coarse crystal portion composed of one phase or two phases is generated, and a uniform fine crystal structure cannot be obtained. As the chemical composition of the ceramic composite material of the present invention, a ternary eutectic composition of aluminum oxide, a rare earth metal oxide and zirconium oxide is most preferable because the generation of coarse crystal parts can be more easily suppressed. Further, if the composition of each component is within this range, even if the composition deviates from the ternary eutectic composition, it is possible to obtain a uniform structure by changing the production conditions. Since it becomes more difficult to secure the structure, the composition of each component is preferably within the range of ± 5 mol% from the ternary eutectic composition, and particularly preferably the ternary eutectic composition. The ceramic composite material of the present invention can have a uniform crystal structure without colonies and voids by controlling the production conditions. Further, there is no grain boundary phase present in a general sintered body. Further, by controlling the manufacturing conditions, the three crystal phases of the oxide and the composite oxide constituting the ceramic composite material are all single crystal, two phases are single crystal, and the other phase is polycrystalline, A ceramic material can be obtained in which each phase is a single crystal, the other phase is polycrystalline, and all phases are polycrystals. Both give sufficient characteristics, but from the viewpoint of strength, it is desirable that at least one phase exists as a single crystal,
More preferably, two or more phases are present in a single crystal. In the present invention, “single crystal” means a crystal structure in which only a diffraction peak from a specific crystal plane is observed in X-ray diffraction analysis. In the solidified body of the ceramic composite material of the present invention, the phase A is a crystal phase composed of α-aluminum oxide alone. The B phase is a crystal phase composed of a composite oxide of aluminum oxide and a rare earth metal oxide, or a composite oxide of aluminum oxide, a rare earth metal oxide and zirconium oxide. Rare earth metal oxides include Y ₂ O ₃ , Er ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ ,
Yb ₂ O ₃ , Gd ₂ O ₃ , Sm ₂ O ₃ , La ₂ O ₃ , C
such as _{e 2 O 3, Nd 2 O} 3, Eu 2 O 3, Pr 6 O 11 and the like. Aluminum oxide and rare earth metal oxide
A composite oxide having a structure such as a garnet structure or a perovskite structure is generated according to the type of the rare earth metal. For example, yttrium oxide and erbium oxide form a complex oxide having a garnet structure, and gadolinium oxide forms a complex oxide having a perovskite structure. Each of them is a ceramic composite material excellent in strength, but a composite oxide having a garnet structure is particularly excellent in heat resistance. The composite oxide of B-phase aluminum oxide and rare earth metal oxide is relatively easy to dissolve other metal oxides (including substitution)
And exist as a ternary composite oxide in which zirconium oxide is dissolved. The C phase is composed of a zirconium oxide single phase or a composite oxide of zirconium oxide and a rare earth metal oxide. In particular, zirconium oxide forms a solid solution with rare earth metal oxides such as yttrium oxide and cerium oxide (however, Pr and Lu are said to have a small stabilizing effect) and is stabilized according to the amount of solid solution. Therefore, composite oxides with these rare earth metal oxides are suitable. When the zirconium oxide is stabilized by the rare earth metal oxide, the mechanical strength is improved. Therefore, it is preferable that the ceramic composite material of the present invention contains a rare earth metal oxide in a relative amount sufficient to stabilize zirconium oxide. In particular, compositions called partially stabilized zirconia and completely stabilized zirconia are particularly preferred. However, it is not limited to these. Further, the ceramic composite material of the present invention is obtained by adding an oxide other than the constituent oxide to form at least one of the oxides constituting the ceramic composite material of the present invention.
It is also possible to change the mechanical properties and the thermal properties by forming a solid solution or a precipitate or existing at the phase interface. In particular, calcium oxide, magnesium oxide, etc. have the effect of stabilizing by dissolving in zirconium oxide,
It is a suitable additive.

Since the form of each metal in the final product is an oxide, and the production passes through a high-temperature step in air under reduced pressure, various metal salts are used as raw materials for the composite material of the present invention. Although oxides can be used, oxides are naturally the most preferable starting material because of various factors such as low weight loss, no harmful substances, and availability.

The mixing of the raw material oxides can be performed by a commonly used powder mixing method irrespective of a dry method or a wet method.
The ball mill method using alcohol as a medium is the most preferable mixing method.

[0010] The mixed raw material powder is subjected to a solvent removal / drying treatment, if necessary, and then transferred to a crucible and melted. The crucible can be made of molybdenum. Although the melting temperature varies depending on the composition, for example, Al ₂ O ₃ , Y ₂ O ₃ , ZrO
_In the case of ₂ , it is 1900-2000 degreeC. The heating may be performed in the air, but the pressure of the atmosphere is preferably reduced pressure, and is preferably 300 Torr or less, more preferably 10 Torr or less. Melting can be carried out using a known heating method, for example, an arc melting furnace, if the heating can be performed up to a predetermined temperature. However, it is also preferable to use a unidirectional solidifying device which will be described later.

The obtained raw material solid is set in a unidirectional solidification device, melted again, and subjected to a unidirectional solidification treatment for cooling and solidifying the melt while moving it downward from a heat source. At this time, if the relative movement of the melt from the heat source is possible, the aggregate used in the present invention can be obtained by using the apparatus used for the raw material melting as it is, and subsequently applying the unidirectional solidification treatment. After the melt has been spontaneously solidified, it can be taken out once, transferred to an apparatus for unidirectional solidification, melted again, and then subjected to a unidirectional solidification treatment. In this case, the solidified body taken out of the melting device is subjected to a pulverizing process,
The pulverized material may be charged again into a coagulation crucible and solidified in one direction.

In unidirectional solidification, for example, a crucible containing a melt is condensed while moving away from the heat source at a constant speed, but the movement of the melt relative to the heat source is relatively high. Alternatively, the heat source may be fixed and the crucible may be moved downward. Movement can also be performed left and right. If the rate of relative movement of the crucible to the heat source in one-way setting, that is, the growth rate of the ceramic composite, is too high, bubbles or voids are generated, and a ceramic composite excellent in mechanical properties at high temperatures cannot be obtained. If it is too slow, there is a problem that the productivity is lowered.
In the range of mm / hour, it is set according to the component composition.

The directional solidification is preferably performed under reduced pressure. This is because it is possible to suppress the generation of colonies and bubbles in the solidified body, which adversely affect the strength development. 1
An atmosphere of 0 ^-3 Torr or less is particularly preferable, and the formation of colonies and bubbles in the coagulated body can be suppressed to such an extent that it is no longer observed with an electron microscope.

The directional solidification can be performed using a known method / apparatus. A method and apparatus for heating with a metal crucible using a high-frequency induction coil can be suitably used, but at least one of the crucible and the heater is made movable in the vertical direction or the horizontal direction. Further, it is preferable that the pressure sensor be connected to a vacuum pump so that the atmosphere in which the crucible is placed can be reduced to a predetermined pressure. Only the crucible may be placed in a cylindrical container connected to the exhaust line, and a structure capable of heating from the outside of the container may be adopted, or the whole may be set in a chamber capable of reducing the pressure in the system. The method of controlling the conditions in the directional solidification, that is, the adjustment of the atmospheric pressure and temperature, and the moving speed of the crucible can be performed by a known method.

Each phase takes a complex shape in the solidified body. A,
Each of the phases B and C may exist in an island shape, but can generally form a three-dimensional continuous structure, and is likely to have a substantially three-dimensional continuous structure. From the observation result of the coagulated body by an electron microscope, it is considered that at least the B phase is oriented and developed in the coagulated direction in the coagulated body.
Further, with respect to the B phase, development in a direction perpendicular to the solidification direction is also observed depending on the composition and conditions. In this case, it is considered that a three-dimensional net is formed by the B phase. At this time, the shape of the A and C phases existing in the gap between the B phases is not clear, but the A phase develops in the solidification direction or in the solidification direction and the direction perpendicular to the solidification direction similarly to the B phase, and is a three-dimensional net. And a matrix that fills the gap between the B and C phases. The C phase appears to be developing in the solidification direction like the B phase. The structure of the crystal phase in such a solidified body can be controlled by the type of constituent oxides, solidification conditions, and the like. Incidentally, the solidification direction referred to in the present invention means the moving direction of the melt, that is, the crucible with respect to the heat source in the unidirectional solidification step.

In the present invention, the ceramic composite material obtained in a solidified form can be used as it is for use. In the present invention, the ceramic composite material obtained in a solidified body shape has a size corresponding to a use object,
After being processed into a shape, it can be used as a member and, if necessary, in combination with other members. Further, it can be made into a fibrous or powdery form and used as a dispersion strengthening material for superalloys or various ceramics.

[0017]

Now, the present invention will be described in further detail with reference to specific examples. Example 1 α-Al ₂ O ₃ powder (purity: 99.99%), Y ₂ O ₃
Powder (purity: 99.999%), ZrO ₂ powder (purity:
(99.99%) in an ethanol medium for 24 hours in a wet ball mill, and then ethanol was removed to obtain a mixed powder of the raw material oxide. The mixing ratio is Al ₂ O ₃ / Y ₂ O ₃ / Z
rO ₂ = 65.8 / 15.6 / 18.6 mol%.
The mixed powder was charged into a molybdenum crucible, and the crucible was set in a heating furnace. The heating furnace is composed of a high-frequency induction coil and a crucible support that can move up and down through the coil, and the whole is installed in a chamber connected to a vacuum pump and capable of creating a reduced-pressure atmosphere in the system. Have been.

The melting was performed under reduced pressure. Using a vacuum pump, induction heating was performed using a high-frequency coil while maintaining the inside of the chamber at 10 ⁻⁵ Torr, thereby melting the mixed powder in the crucible. The temperature of the melt in the crucible measured with a pyrometer was 1900 ° C. In the unidirectional solidification, the crucible was unidirectionally solidified while the crucible was lowered at a speed of 50 mm / hour under the same atmosphere as the melting, without taking out the above-mentioned melt from the chamber, to obtain a desired solidified body.

FIG. 1 shows an electron micrograph of a cross-sectional structure perpendicular to the solidification direction of the obtained solidified body. FIG. 1A shows 200
FIG. 1 (A) is a photograph at a magnification of 5,000 times. FIG.
(A) In (A), the black part is the α-alumina phase, the gray part is the YAG (Y ₃ Al ₅ O ₁₂ ) phase, and the white part is the zirconia phase containing yttria. The white part is mainly Y
It is observed as islands around the AG phase and in the alumina phase. In addition, as far as observed by an electron micrograph, this coagulated body does not have a colony or a grain boundary phase in any phase, and further has no bubbles or voids, that is, it is composed of a structure having no structural defect. I have.

FIG. 2 shows an X-ray diffraction pattern of the powder obtained by pulverizing the coagulated body. From this figure, it is confirmed that the constituent phase of the aggregate is composed of a zirconia phase containing α-alumina, YAG and yttria. FIG. 3 shows an X-ray diffraction result of a plane perpendicular to the solidification direction of the solidified body. α-alumina phase (300) plane, YAG (400) plane, (8)
(00) plane, (20) of the zirconia phase in which yttria was dissolved.
The existence of the (0), (220), and (400) planes is confirmed.
From this result, it can be seen that the α-alumina phase and the YAG phase are single crystals, and the yttria solid solution zirconia phase exists as a polycrystal.

The pulverized product was further subjected to X-ray diffraction using a high-temperature X-ray diffractometer manufactured by Mac Science Inc. while raising the temperature, and the phase change in a high-temperature region was examined. FIG. 4 shows the result. Room temperature (RT) and 1500 ° C
No difference was recognized, and the constituent phases of the solidified body were from room temperature to
In the temperature range of 1500 ° C., no phase change occurs. Usually, in zirconia ceramics, a transition from a monoclinic system to a tetragonal system occurs at a high temperature, causing a problem of a decrease in mechanical properties.However, in the solidified body of the present invention, zirconia is stabilized by the presence of yttria, It is considered that the problem of the zirconia phase transition has been solved.

A 3 mm × 4 mm × 36 mm test piece was cut out from the solidified body, and the three-point bending strength at a high temperature was measured using an ultra-high temperature material physical property evaluation system manufactured by Instron. Table 1 shows the measurement results. This material is 17
It can be seen that even at 00 ° C., it has a bending strength of 720 MPa. The three-point bending strength measurement was performed on the other samples in the same manner as described here.

[0023]

[Table 1]

Comparative Example 1 Here, an example in which the amount of zirconia was set outside the range of the present invention.
Is shown. Erbium oxide used as rare earth oxide
Here is an example. α-Al_TwoO_Three/ Y_TwoO_Three/ ZrO _TwoFormula of
Except that the ratio was 74.4 / 17.6 / 8.0 mol%,
A coagulated body was obtained in the same manner as in Example 1. The resulting solid
Fig. 5 shows an electron micrograph of the cross-sectional structure perpendicular to the solidification direction of
Show. In the coagulated structure, coarse particles of 50 to 200 μm are observed.
It can be seen that the coarse grains_TwoO_ThreePhase and YAG
ZrO_Two(Or ZrO_Two/ Y_TwoO _Three
(Composite oxide) phase. this
Table 1 shows the results of measuring the three-point bending strength of the composite material. 160
It shows only 350 MPa strength even at 0 ° C.
It is clear that this material is inferior in characteristics to material 1
You.

Embodiment 2 Here, an example in which erbium oxide is used as a rare earth oxide will be described. Erbium oxide (Er ₂
O ₃ , purity: 99.999%) and α-Al ₂ O
The mixing ratio of ₃ / Er ₂ O ₃ / ZrO ₂ was 65.9 / 15.
A coagulated body was obtained in the same manner as in Example 1, except that the rate was 4 / 18.7 mol% and the crucible descent speed in the unidirectional solidification step was 20 mm / hour. FIG. 6 shows an electron micrograph of a cross-sectional structure perpendicular to the solidification direction of the obtained solidified body. In FIG. 6, the black portion is the α-alumina phase,
Erbium aluminum garnet whose large white portion has a composition of Er ₃ Al ₅ O ₁₂ (hereinafter referred to as EAG)
Phase. The white portion present around the EAG phase or appearing as small dots is the zirconia phase containing erbium oxide. In this coagulated body, similarly to the coagulated body of Example 1, the presence of colonies and grain boundary phases was not confirmed, the presence of bubbles and voids was not confirmed, and the coagulated body had a structurally defect-free structure. I understand.

FIG. 7 shows the results of X-ray diffraction pattern measurement on a plane perpendicular to the solidification direction of the solidified body. The diffraction peaks observed were (006) plane of α-alumina phase and (40) of EAG.
The (0) plane and the (800) plane, and the (200) plane of the zirconia phase in which erbium oxide was dissolved were measured. This indicates that the α-alumina phase, the EAG phase, and the erbium oxide solid solution zirconia phase exist as single crystals. 3 of the material
Table 1 shows the results of the point bending strength measurement. Even at 1700 ° C., it has a strength of 760 MPa or more.

Comparative Example 2 Here, the case where no rare earth oxide was contained as a constituent
Here is an example. Α-alumina / di
The charge ratio of Luconia was set to 62.0 / 38.0 mol%.
Except for the above, a coagulated body was obtained in the same manner as in Example 1. This
X-ray diffraction is also performed on solids while raising the temperature.
The phase change in the region was discussed. The results are shown in FIG.
You. Table 1 shows the three-point bending strength measurement results of the solidified body.
Even at 1600 ° C., it shows only a strength of 380 MPa,
It can be seen that this material is inferior in characteristics to the material of the example.
Call In this comparative example, zirconia was converted to rare earth oxide.
Is not stabilized at 800 ° C.
Diffraction peaks begin to be observed, causing the zirconia phase transition
Was confirmed. Comparative Example 3 Here, alumina and yttria as rare earth oxides
(Y_TwoO_Three, Purity: 99.999%) and α
-Al_TwoO_Three/ Y_TwoO_ThreeOf 82.0 / 18.0
Mol% and the rate of crucible descent in the unidirectional solidification process
The same as in Example 1 except that the degree was set to 20 mm / hour.
A coagulated body was obtained by the method. Perpendicular to the solidification direction of the resulting solid
An electron micrograph of the cross-sectional structure is shown in FIG. FIG.
In (A), the black portion is the α-alumina phase,
The bright white part is Y _ThreeAl_FiveO₁₂With the composition of
Aluminum garnet (YAG) phase. Each conclusion
The size of the crystal phase is 10 μm to 100 μm.
The photograph of FIG. 1 showing the example is shown at the same scale as FIG.
Compared with FIG. 9 (a), the microstructure of the solidified body of the present invention
It is clear. Measurement of the three-point bending strength of this solidified body
The results are also shown in Table 1.

[0028]

Industrial Applicability The ceramic composite material of the present invention has a remarkably improved high-temperature strength and thermal stability, and has a high bending strength of about 700 MPa or more even at a high temperature of 1700 ° C. in the atmosphere. It is possible. This does not exist before. It has a great improvement effect as various high-temperature materials exposed to severe atmospheres, including turbine blades for jet engines and power generation turbines.

[Brief description of the drawings]

FIG. 1 is an electron micrograph instead of a drawing showing the structure of a cross section perpendicular to the solidification direction of an example of a composite material according to the present invention.

FIG. 2 is a powder X-ray diffraction pattern of the same material at room temperature.

FIG. 3 is an X-ray diffraction pattern of a plane perpendicular to the solidification direction of the same material.

FIG. 4 is a powder X-ray diffraction pattern of the same material in a high-temperature region.

FIG. 5 is an electron micrograph instead of a drawing showing the structure of a cross section perpendicular to the solidification direction of a composite material example not belonging to the present invention.

FIG. 6 is an electron micrograph instead of a drawing showing the structure of a cross section perpendicular to the solidification direction of a solidified body of another example of the composite material of the present invention.

FIG. 7 is an X-ray diffraction pattern of a plane perpendicular to the solidification direction of the same material.

FIG. 8 is a powder X-ray diffraction pattern in a high temperature region of another example of a composite material not belonging to the present invention.

FIG. 9 is an electron micrograph instead of a drawing showing a structure of a cross section perpendicular to the solidification direction of a composite material example of a comparative example and an example.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinichi Sakata 573 Uki, Ube City, Yamaguchi Prefecture Three ultra-high-temperature materials research institute, Yamaguchi Laboratory (72) Inventor, Kazutoshi Shimizu, Ube City, Yamaguchi Prefecture Ultra-high-temperature materials research laboratory, Yamaguchi Laboratory, Ltd. at 573 Okibe (72) Inventor Atsushi Mitani, 573 ultra-high temperature materials laboratory, Yamaguchi Laboratory, Oki-Ube, Ube-shi, Yamaguchi, Japan (72) Invention Person: Nakagawa Naruto, 1978 Kogushi, Ube City, Ube City, Yamaguchi Prefecture Ube Industries, Ltd. Ube Research Laboratory F-term (reference) 4G030 AA11 AA17 AA36 BA20 CA01 CA04 GA09

Claims (5)

[Claims] 1. A) aluminum oxide (A phase), B) a composite oxide of aluminum oxide and a rare earth metal oxide, or a composite oxide of aluminum oxide, a rare earth metal oxide and zirconium oxide (B phase) , C) zirconium oxide or a composite oxide (C phase) of zirconium oxide and a rare earth metal oxide, which is a melt-solidified body composed of three oxide crystal phases, and has a chemical composition of aluminum oxide, rare earth A ceramic composite material comprising metal oxides and zirconium oxide in the range of 55 to 80 mol%, 10 to 35 mol%, and 10 to 35 mol%, respectively. 2. The method according to claim 1, wherein the three crystal phases are uniformly distributed, and there is no coarse crystal part composed of one or two crystal phases.
2. The ceramic composite material according to item 1. 3. The ceramic composite material according to claim 1, wherein there are no colonies and no voids in the solidified body. 4. The ceramic composite material according to claim 1, wherein at least one crystal phase is composed of a single crystal. 5. The ceramic composite material according to claim 1, wherein the zirconium oxide in the C phase is stabilized by an oxide of a rare earth metal or another metal.