JP2016132577A - Alumina-zirconia sintered body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alumina-zirconia sintered body having excellent thermal shock resistance and little degradation of strength in repeated use.SOLUTION: An alumina-zirconia sintered body is characterized by having both a tetragonal or cubic crystal zirconia crystal phase and a monoclinic zirconia crystal phase defined in X-ray diffraction. The sintered body has a crack connecting a grain boundary of a zirconia crystal phase and a grain boundary of another zirconia crystal phase or a pore in an alumina grain. The ratio of the total area of the crack to the area of the alumina grain is preferably 0.3%-3.0%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an alumina / zirconia sintered body, and more particularly, to an alumina / zirconia sintered body suitable for a firing jig for firing electronic parts such as dielectrics, multilayer capacitors, thermistors, varistors, and chip inductors. .

Alumina / zirconia sintered bodies are excellent in strength and thermal shock resistance, and are used in various fields.
For example, it is used for firing jigs for firing electronic components such as multilayer capacitors, thermistors, varistors, chip inductors, etc., and in Patent Document 1 below, the raw material composition is coarse-grained alumina having an average particle diameter of 30 to 500 μm and an average An alumina / zirconia firing jig comprising alumina particles made of fine alumina having a particle size of 0.1 to 20 μm and zirconia particles, and bonding coarse alumina by cooling from the alumina / zirconia partially molten phase A thermal shock resistant alumina / zirconia firing jig characterized by finely dispersing zirconia particles in alumina is disclosed.

  In Patent Document 2 below, 20 to 70 wt% of coarse alumina having an average particle size of 30 to 200 μm, 20 to 70 wt% of fine alumina having an average particle size of 1 to 5 μm, and an average particle size of 5 to 5 wt. 30 μm zirconia particles are mixed with 5 to 30 wt% to form a molded body, and the molded body is fired to finely disperse the zirconia particles in alumina that binds coarse alumina. A method for producing a thermal shock-resistant alumina / zirconia firing jig is disclosed.

  In addition, in Patent Document 3 below, it is used for structural member applications such as cutting tools, dies, nozzles, bearings, and decorative items, and contains 50 to 95% by weight of zirconia containing 2 to 4 mol% of yttria and 5 to 50% of alumina. A zirconia-alumina composite sintered body composed of wt%, wherein the relative density of the zirconia-alumina composite sintered body is 98% or more, and the average particle diameter of the mixed particles composed of zirconia crystal particles and alumina crystal particles is 0.4 μm. Hereinafter, the number of coarse alumina polycrystalline particles having a tetragonal crystal ratio of zirconia crystal phase of 83 wt% or more and 20 or more alumina crystal particles is in a field of view of 240 μm × 180 μm by a field emission scanning electron microscope. One or less zirconia-alumina composite sintered body is disclosed, which has excellent hydrothermal deterioration resistance.

Others are used for semiconductor substrates. Patent Document 4 listed below discloses a mixture of Al ₂ O ₃ powder, ZrO ₂ powder and Y ₂ O ₃ powder, or Al ₂ O ₃ powder and ZrO ₂ —Y ₂ O _3. ZrO ₂ : 2 to 15% by weight, Y ₂ O ₃ : 0.01 to 1% by weight, obtained by firing a raw material composition which is made of a mixture with powder and to which no sintering aid is added And Al ₂ O ₃ : composed of the remaining sintered body, the average crystal particle diameter of Al ₂ O ₃ is larger than 2 μm and 7 μm or less, and Al ₂ O ₃ particles are in direct contact with each other. Characterized in that the grain boundary length is 60% or more of the total grain boundary length, the thermal conductivity is 30 W / m · K or more, and the bending strength is 500 MPa or more. An alumina zirconia sintered substrate for equipment is disclosed, which has excellent strength and thermal conductivity. It is.

  The other is used as a material for structural parts, and in Patent Document 5 below, a ceramic sintered body having a composite structure of zirconium oxide and aluminum oxide is a polycrystal composed of zirconium oxide and its stabilizer. It has a composite structure with a region of zirconium oxide particles and a region of polycrystalline aluminum oxide / zirconium particles that is composed of zirconium oxide and aluminum oxide and, optionally, a stabilizer, and was obtained from a two-dimensional section. Zirconium oxide / aluminum oxide composite ceramics sintered characterized by having a microstructure in which an aluminum oxide / zirconium oxide particle group having an average diameter represented by an equivalent circular diameter of 10 μm or more and 100 μm or less is dispersed in a matrix of the zirconium oxide particle group The body is disclosed, which is high strength and high toughness In addition to this, it has an even better resistance to fracture growth.

Japanese Patent No. 3949951 Japanese Patent No. 3949950 JP 2014-139123 A JP 2013-32265 A JP-A-8-67557

As shown in Patent Document 1 or 2, zirconia particles are dispersed in alumina that binds coarse alumina, and pores are provided by combining coarse alumina and fine alumina to relieve thermal stress. Thus, an alumina / zirconia sintered body for a firing jig having improved thermal shock resistance has been developed.
However, even if the alumina / zirconia sintered body is excellent in thermal shock resistance, the strength may be reduced and damaged in repeated use, and it is necessary to improve this point.

  Accordingly, an object of the present invention is to provide an alumina / zirconia sintered body that is excellent in thermal shock resistance but has a small decrease in strength in repeated use.

  One aspect of the present invention is an alumina-zirconia sintered body characterized by having both a tetragonal or cubic zirconia crystal phase and a monoclinic zirconia crystal phase.

The alumina / zirconia sintered body having the above-described form has an X-ray diffraction peak intensity ratio defined by the following (formula 1) of 0.02 to 0.60 and is defined by the following (formula 2). The X-ray diffraction peak intensity ratio is preferably 0.003 to 0.75.
(Formula 1) ... I ₂ cubic or tetragonal zirconia phase (111) peak intensity / {I ₁ α alumina phase (116) peak intensity + I ₂ cubic or tetragonal zirconia phase (111) peak intensity + I ₃ 2θ Is the peak intensity of the monoclinic zirconia phase (111) around 28 °}
(Equation 2) ... peak intensity of monoclinic zirconia phase (111) with I ₃ 2θ around 28 ° / {I1α alumina phase (116) peak intensity + I peak intensity of ₂ cubic or tetragonal zirconia phase (111) + I ₃ peak intensity of monoclinic zirconia (111) with 2θ around 28 °}

  Further, the alumina / zirconia sintered body of the above-mentioned form is an alumina / zirconia sintered body in which alumina particles are bonded with a zirconia crystal phase, and other zirconia from the grain boundary with the zirconia crystal phase in the alumina particles. It is preferable to have a crack connecting the crystal phase or the grain boundary with the pores, and a value obtained by dividing the total extension of the crack by the alumina particle area is 0.3% to 3.0%.

  The alumina / zirconia sintered body of the above form preferably has a porosity of 10% to 40%.

The alumina / zirconia sintered body of the above form is at least one selected from Y ₂ O ₃ and Yb ₂ O ₃ and at least one selected from CaO, MgO, SrO, CeO ₂ and BaO. It is preferable to contain the zirconia stabilized by the above.

The alumina / zirconia sintered body of the above-mentioned form contains 0.05% by mass of at least one element selected from 60% by mass to 98% by mass of Al ₂ O ₃ , Y ₂ O ₃ , and Yb ₂ O _3. ˜1.95% by mass, at least one element selected from CaO, MgO, SrO, CeO ₂ and BaO is composed of 0.05% by mass to 1.3% by mass, and the rest is composed of ZrO _2. Preferably it is.

  The alumina / zirconia sintered body having the above-described form is excellent in thermal shock resistance, but has a small decrease in strength in repeated use. It is considered that this is because the tetragonal or cubic zirconia crystal phase prevents the strength from being reduced by repeated use, and the monoclinic zirconia crystal phase can improve the thermal shock resistance.

It is the reference electron micrograph which showed the crystal structure of the alumina zirconia sintered compact of one Embodiment of this invention. 6 is an X-ray diffraction pattern of an alumina / zirconia sintered body of Example 5. FIG. 5 is an X-ray diffraction diagram of an alumina / zirconia sintered body of Comparative Example 2. FIG. 6 is an X-ray diffraction diagram of an alumina / zirconia sintered body of Comparative Example 5. FIG. It is the electron micrograph which image | photographed the crystal structure of Example 8 by 500 time. 6 is an electron micrograph of the crystal structure of Comparative Example 2 taken at 500 times. It is the electron micrograph which image | photographed the crystal structure of the comparative example 8 by 500 time.

  Hereinafter, the alumina-zirconia sintered body of one embodiment of the present invention will be described. The scope of the present invention is not limited to this embodiment.

The alumina-zirconia sintered body of one embodiment of the present invention is characterized by having both a tetragonal or cubic zirconia crystal phase defined by X-ray diffraction and a monoclinic zirconia crystal phase.
By having such a crystal structure, the thermal shock resistance is improved, and the strength deterioration in repeated use is reduced.
X-ray diffraction can be performed by, for example, an electron diffraction method or a neutron diffraction method.

The alumina / zirconia sintered body of this embodiment preferably has an X-ray diffraction peak intensity ratio defined by (Equation 1) below of 0.02 to 0.60. By being a high value of 0.02 or more, it becomes possible to suppress strength deterioration in repeated use while maintaining excellent thermal shock resistance. On the other hand, if it exceeds 0.60, the amount of zirconia added becomes large, which is not preferable from the viewpoint of cost. The peak intensity ratio is more preferably 0.05 to 0.60, further preferably 0.09 to 0.60.
(Formula 1) ... I ₂ cubic or tetragonal zirconia phase (111) peak intensity / {I ₁ α alumina phase (116) peak intensity + I ₂ cubic or tetragonal zirconia phase (111) peak intensity + I ₃ 2θ Is the peak intensity of the monoclinic zirconia phase (111) around 28 °}

In the present invention, I _{1 to} I ₃ indicate the diffraction intensity of the zirconia crystal phase.

The alumina / zirconia sintered body of this embodiment preferably has an X-ray diffraction peak intensity ratio defined by (Equation 2) below of 0.003 to 0.75. When the value is larger than 0.003, the thermal shock resistance can be improved while suppressing the strength deterioration in repeated use. On the other hand, if it exceeds 0.75, the amount of zirconia added becomes large, which is not preferable from the viewpoint of cost. The peak intensity ratio is more preferably 0.01 to 0.75, and even more preferably 0.05 to 0.75.
(Formula 2) ... peak intensity of monoclinic zirconia phase (111) with I ₃ 2θ around 28 ° / {I ₁ α alumina phase (116) peak intensity + I ₂ cubic or tetragonal zirconia phase (111) peak Intensity + I ₃ 2θ peak intensity of monoclinic zirconia (111) near 28 °}

The alumina / zirconia sintered body of this embodiment has an Al ₂ O ₃ content of 60% by mass to 98% by mass, and at least one element selected from Y ₂ O ₃ and Yb ₂ O ₃ is 0.05% by mass. ˜1.95 mass%, at least one element selected from CaO, MgO, SrO, CeO ₂ , and BaO is composed of 0.05 mass% to 1.3 mass%, and the remainder is composed of ZrO ₂ . It is preferable. By adopting such a configuration, it is possible to obtain a material having excellent thermal shock resistance and less strength deterioration in repeated use. A trace amount of impurities is included.
Al ₂ O ₃ is more preferably 60% by mass to 97% by mass, and further preferably 75% by mass to 95% by mass.

The alumina / zirconia sintered body of this embodiment preferably has a porosity of 10% to 40%. Within this range, excellent thermal shock resistance can be imparted. The porosity is more preferably 10% to 35%, further preferably 13.5% to 35%.
The porosity can be measured by, for example, the Archimedes method.

The alumina / zirconia sintered body of this embodiment is at least one selected from Y ₂ O ₃ and Yb ₂ O ₃ and at least one selected from CaO, MgO, SrO, CeO ₂ and BaO. It is preferable to use zirconia stabilized as described above.
By selecting zirconia stabilized with these materials, it is possible to obtain a material having excellent thermal shock resistance and less strength deterioration in repeated use. Among the above stabilizers, at least one selected from Y ₂ O ₃ and Yb ₂ O ₃ contributes to the stabilization of zirconia, and together with the stabilization of zirconia, CaO, MgO, SrO, CeO ₂ and BaO. At least one selected from the above serves as a starting point for cracks in the alumina particles connecting from the grain boundary with the zirconia crystal phase to the grain boundary with another zirconia crystal phase or pore. In particular, it is preferable to select zirconia stabilized with Y ₂ O ₃ and CaO or MgO.
Zirconia stabilized with at least one element selected from Y ₂ O ₃ and Yb ₂ O ₃ is preferably 0.5% by mass to 20% by mass in the sintered body, and more preferably 1% by mass to 10%. More preferred is mass%. Zirconia stabilized with at least one element selected from CaO, MgO, SrO, CeO ₂ and BaO is more preferably 0.05% by mass to 25% by mass in the sintered body. 1% by mass to 20% by mass is more preferable.

When the crystal structure is observed, the alumina / zirconia sintered body of this embodiment is an alumina / zirconia sintered body in which alumina particles are bonded together by a zirconia crystal phase. From the grain boundary with the zirconia crystal phase in the alumina particles. It has cracks that connect to the grain boundaries with other zirconia crystal phases or pores, and the value obtained by dividing the total extension of the cracks by the alumina particle area is 0.3% to 3.0%.
It is considered that cracks are generated in the alumina particles from the grain boundaries of the alumina particles adjacent to the zirconia crystal phase due to the difference in volume expansion coefficient between the tetragonal or cubic zirconia crystal phase and the monoclinic zirconia crystal phase.

  The alumina / zirconia sintered body of this embodiment preferably has a total crack extension of 110 μm to 1000 μm. By being in this range, it is possible to obtain excellent thermal shock resistance. The total extension of cracks is more preferably 150 μm to 1000 μm, and further preferably 200 μm to 950 μm.

The crack referred to in the present invention runs in the alumina particles and connects from the grain boundary with the zirconia crystal phase to the grain boundary with another zirconia crystal phase or pores, that is, the longitudinal or crossing of the alumina particles. is there. The crack may merge with other cracks on the way, or may be branched into a plurality on the way. It does not include cracks in which cracks are interrupted in the middle, and cracks in which the start or end portions are within alumina particles and cracks in which both the start and end portions are grain boundaries with pores are not included. For example, as indicated by an arrow in FIG. 1, a crack connecting a grain boundary with a zirconia crystal phase to a grain boundary with another zirconia crystal phase or pores corresponds. In addition, the white location in FIG. 1 is a zirconia crystal phase, the location surrounded by the white fine line is a pore, and the remainder is an alumina particle.
The total extension of cracks can be measured using, for example, a scanning electron microscope, and specifically, as shown in the following examples.

  The alumina / zirconia sintered body of this embodiment preferably has a total crack extension (crack ratio) of 0.3% to 3.0% with respect to the area of the alumina particles. By being in this range, it becomes possible to obtain excellent thermal shock resistance. The crack ratio is more preferably 0.5% to 2.5%, and further preferably 0.85% to 2.4%.

The alumina / zirconia sintered body of this embodiment can be manufactured, for example, by the following manufacturing method. Hereinafter, although the method to manufacture a sheet-like sintered compact is shown, it is not limited to this.
As a raw material alumina, a blend of 30 mass% to 90 mass% of coarse alumina having an average particle diameter of 30 μm to 300 μm and 5 mass% to 60 mass% of fine alumina having an average particle diameter of 0.1 μm to 5 μm is used. Can do. Thus, by using coarse-grained alumina and fine-grained alumina, the porosity can be adjusted, and the thermal shock resistance is improved.
The coarse-grained alumina preferably has an average particle size of 40 μm to 250 μm, and more preferably an average particle size of 50 μm to 200 μm. Moreover, 35 mass%-85 mass% are more preferable, and 40 mass%-80 mass% are further more preferable.
The fine alumina preferably has an average particle size of 0.5 to 4 μm, and more preferably an average particle size of 1 to 3 μm. Moreover, 7 mass%-55 mass% are more preferable, and 10 mass%-50 mass% are further more preferable.

As a raw material zirconia, 3% by mass to 40% by mass of zirconia having an average particle diameter of 0.1 μm to 100 μm can be used. As this zirconia, any of unstabilized zirconia, partially stabilized zirconia and stabilized zirconia may be used, but it is selected from Y ₂ O ₃ , Yb ₂ O ₃ , CaO, MgO, SrO, CeO ₂ and BaO. Zirconia stabilized with at least one selected from the group consisting of at least one selected from Y ₂ O ₃ and Yb ₂ O ₃ and at least selected from CaO, MgO, SrO, CeO ₂ and BaO. Zirconia stabilized with one or more is more preferred.
The raw material zirconia preferably has an average particle size of 0.5 μm to 50 μm, more preferably an average particle size of 1 μm to 30 μm. Moreover, 4 mass%-30 mass% are more preferable, and 5 mass%-25 mass% are further more preferable.
In addition, the average particle diameter of the raw material alumina and zirconia can be measured by, for example, a laser diffraction method.

Further, as an additive element, at least one selected from Y ₂ O ₃ , Yb ₂ O ₃ , CaO, MgO, SrO, CeO ₂ and BaO is used in an amount of 5.0% by mass to the zirconia raw material. You may mix | blend 10.5 mass%. This additive element is more preferably blended in an amount of 5.3% by mass to 10% by mass, and further preferably in an amount of 5.5% by mass to 10% by mass.

  Binders such as metrose, dextrin, methylcellulose, glycerin and the like are blended in an amount of 3% by mass to 15% by mass with respect to alumina and zirconia, and further, an appropriate amount of water is added, followed by stirring and mixing using a high speed mixer or the like.

Next, the agitated and mixed raw materials are uniformly dispersed and mixed using a three roll or the like. These blends are formed into a sheet or the like using an extrusion molding machine and dried. These sheets can be fired at 1400 ° C. to 1850 ° C. for 0.5 to 24 hours to produce the alumina / zirconia sintered body of this embodiment.
Firing is more preferably 1500 ° C to 1800 ° C, and further preferably 1550 ° C to 1800 ° C. Moreover, 1 hour-20 hours are more preferable, and 2 hours-15 hours are still more preferable.

  The alumina / zirconia sintered body of this embodiment has a thermal shock resistance of ΔT 500 ° C. to 900 ° C., a strength deterioration rate after 80 cycles of 0 to 35%, excellent thermal shock resistance, and strength by repeated use. Is difficult to decrease. The measuring method of the thermal shock resistance and the strength deterioration rate after 80 cycles is as shown in the following examples. The thermal shock resistance is more preferably ΔT650 ° C to 800 ° C. Further, the strength deterioration rate is more preferably 0% to 29%, further preferably 0% to 14%.

  The alumina / zirconia sintered body of this embodiment can be used in various fields, but is particularly suitable for firing jigs for firing electronic parts such as dielectrics, multilayer capacitors, thermistors, varistors, and chip inductors. It is a thing.

  Hereinafter, an alumina / zirconia sintered body according to an embodiment of the present invention will be described. The scope of the present invention is not limited to this example.

(Production of Examples and Comparative Examples)
The alumina zirconia sintered bodies of Examples 1 to 12 and Comparative Examples 1 to 7 were produced.
For each alumina / zirconia sintered body, coarse-grained alumina, fine-grained alumina, and zirconia were used as raw materials. These average particle diameters, blending ratios, and the like are as shown in the blending composition of Table 1 below. The average particle size was measured by a laser diffraction method.
Further, this was formulated in proportions shown an additive element such as _Y 2 _O 3, CaO in the following Table 1.
Binders such as metrose, dextrin, methylcellulose, glycerin and water were added to these raw materials, and the mixture was stirred and mixed with a high speed mixer.
Next, this was uniformly dispersed and mixed using three rolls, and this blend was formed into a sheet having a thickness of 3 mm using an extrusion molding machine and dried. This sheet was fired at 1700 ° C. for 8 hours to obtain each alumina / zirconia sintered body.

(Physical property value)
Each physical property value of each alumina / zirconia sintered body was measured.

(Porosity)
The porosity of each alumina / zirconia sintered body was measured by the Archimedes method.
The results are shown in Table 1 above.

(Peak intensity)
X-ray diffraction was performed to measure the peak intensity of each alumina / zirconia sintered body. The X-ray diffraction at this time is measured with XD-D1 (manufactured by Shimadzu Corporation). The measurement conditions are CuKα (λ = 1.541Å) as the X-ray source, voltage: 40 kV, current: 30 mA, scan. The speed was 4 ° / min, the sampling width was 0.02 °, the divergence slit was 1 °, the divergence vertical slit was 10 mm, and the light receiving slit was 0.3 mm. For reference, X-ray diffraction diagrams of Example 5, Comparative Example 2, and Comparative Example 5 are shown in FIGS.
Each peak intensity and peak intensity ratio calculated from these X-ray diffraction diagrams are shown in Table 1 above.

(Crack ratio)
The crack ratio of each alumina / zirconia sintered body was measured with a scanning electron microscope (JSM-6380A, manufactured by JEOL) by taking a 500-fold photomicrograph and measuring the area of the alumina particles by the following method. The total crack extension was calculated by adding the lengths of cracks that can be visually observed, and the crack ratio (%) in the alumina particles was measured by the following formula 3. For reference, micrographs of Example 8, Comparative Example 2, and Comparative Example 8 are shown in FIGS. Using these values, the crack ratio was calculated by dividing the total extension of cracks by the alumina particle area. The results are shown in “Crack ratio in alumina particles” in Table 1 above.
Alumina particle area calculation method: The field of view at an arbitrary magnification at the time of SEM observation is defined as S (μm ² ), two diagonal lines forming a straight line in an electron microscope (SEM) are defined, and the length of the diagonal line is defined as When the length of alumina particles existing on the two diagonals is L ₁ (μm) and L ₂ (μm), the alumina particle ratio (%) in the field of view at an arbitrary magnification is ( L ₁ + L ₂ ) / (2 × L), and the area Sa (μm ² ) of the alumina particles was defined as S × (L ₁ + L ₂ ) / (2 × L).
The length of the crack connecting the grain boundary with the zirconia crystal phase to another zirconia crystal phase or void existing in the alumina crystal particle in the micrograph is defined as the sum Lc that linearly connects the crack start and end points. To do.
“Crack ratio in alumina particles (%)” = Lc / Sa × 100 (Formula 3)

(test)
Using the alumina / zirconia sintered bodies of Examples 1 to 12 and Comparative Examples 1 to 7, a thermal shock resistance test and a bending strength test were performed.

(Thermal shock resistance test)
In the thermal shock test, four alumina / zirconia fired bodies processed to 90 mm □ × 2.5 mm in thickness were prepared, and these were placed on a ceramic base plate with a length of 10 mm × width 5 mm × height 5 mm. Four columns were stacked with four columns arranged. Next, after raising the temperature of the electric furnace to a predetermined temperature and holding it for 30 minutes, the test specimen was put into the furnace. After holding at that temperature for 30 minutes, the test specimen was taken out of the furnace and allowed to cool, and it was visually confirmed whether the specimen was cracked. The above operation was performed by increasing the temperature by 10 ° C. from 300 ° C., and the upper limit of the temperature at which no cracks occurred was defined as thermal shock resistance ΔT. The results are shown in Table 1 above.

(Bending strength test)
The bending strength test was performed by a three-point bending test based on JIS R1601. The test piece was heated from 600 ° C. to 1400 ° C. at a heating rate of 200 ° C./hr, kept at 1400 ° C. for 3 hours, and cooled to 600 ° C. at a cooling rate of 200 ° C./hr for 80 cycles. After that, the bending strength was measured in the same manner. The strength deterioration rate after 80 cycles was calculated from these values. The results are shown in Table 1 above. The rate of temperature increase up to 600 ° C. in the first cycle was 200 ° C./hr, and the rate of cooling from 600 ° C. to room temperature after the cycle was natural cooling.

(result)
In the thermal shock test, ΔT was 500 ° C. or higher, and in the bending strength test, the strength deterioration rate after 80 cycles was 35% or less.
In each of Examples 1 to 12, the thermal shock resistance ΔT is 500 ° C. or more, the strength deterioration rate after 80 cycles is 35% or less, the thermal shock resistance is excellent, and the strength decrease in repeated use is small. Met. Here, for Examples 1 to 12 in which the X-ray diffraction peak intensity ratio defined by (Equation 1) is in the range of 0.02 to 0.60, the intensity deterioration rate after 80 cycles is 35 at the maximum. %, And particularly excellent in strength after thermal cycling. Furthermore, they have an X-ray diffraction peak intensity ratio defined by (Equation 2) of 0.003 to 0.75.
About Examples 1-10 and 12, all were 650 degreeC or more in (DELTA) T, and it turned out that it has the characteristic which was especially excellent in the thermal shock resistance.
On the other hand, Comparative Examples 1, 3, 5, and 6 had a strength deterioration rate after 80 cycles of more than 85%, and were excellent in thermal shock resistance, but had a large decrease in strength in repeated use. . In particular, in Comparative Examples 1, 3, and 6 containing no tetragonal ZrO ₂ , the strength deterioration rate after 80 cycles was remarkably inferior to 96% or 97%. Similarly, Comparative Example 5 having a high porosity of 42% also showed a low value of 88% after 80 cycles.
In Comparative Examples 2, 4, and 7, the thermal shock resistance ΔT was less than 500 ° C., and the thermal shock resistance was inferior although the strength decrease during repeated use was small.

  From these results, the alumina / zirconia sintered body having both a tetragonal or cubic zirconia crystal phase and a monoclinic zirconia crystal phase has excellent thermal shock resistance and a small decrease in bending strength in repeated use. .

Claims (6)

  An alumina / zirconia sintered body having both a tetragonal or cubic zirconia crystal phase and a monoclinic zirconia crystal phase. The X-ray diffraction peak intensity ratio defined below (Formula 1) is 0.02 to 0.60, and the X-ray diffraction peak intensity ratio defined below (Formula 2) is 0.003 to 0. The alumina / zirconia sintered body according to claim 1, which is .75.
(Formula 1) ... I ₂ cubic or tetragonal zirconia phase (111) peak intensity / {I ₁ α alumina phase (116) peak intensity + I ₂ cubic or tetragonal zirconia phase (111) peak intensity + I ₃ 2θ Is the peak intensity of the monoclinic zirconia phase (111) near 28 °}
(Formula 2) ... peak intensity of monoclinic zirconia phase (111) with I ₃ 2θ around 28 ° / {I ₁ α alumina phase (116) peak intensity + I ₂ cubic or tetragonal zirconia phase (111) peak Intensity + I ₃ 2θ peak intensity of monoclinic zirconia (111) near 28 °}   The alumina / zirconia sintered body according to claim 1 or 2, which has a porosity of 10% to 40%. A zirconia stabilized with at least one selected from Y ₂ O ₃ and Yb ₂ O ₃ and at least one selected from CaO, MgO, SrO, CeO ₂ and BaO. The alumina / zirconia sintered body according to any one of? Al ₂ O ₃ is 60% by mass to 98% by mass, Y ₂ O ₃ , Yb ₂ O ₃ is at least one element selected from 0.05% by mass to 1.95% by mass, CaO, MgO, SrO The element according to claim 1, wherein at least one element selected from CeO ₂ and BaO is composed of 0.05% by mass to 1.3% by mass, and the rest is composed of ZrO ₂ . The alumina / zirconia sintered body according to any one of the above. An alumina / zirconia sintered body in which alumina particles are bonded with a zirconia crystal phase, and the alumina particles have cracks that connect from the grain boundary with the zirconia crystal phase to the grain boundary with another zirconia crystal phase or pores. The ratio of the total extension of the cracks is 0.3% to 3.0% with respect to the alumina particle area, The alumina / zirconia sintered body according to any one of claims 1 to 5, .

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