JPH10167802A - Ceramic sintered compact and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a ceramic sintered compact widely applicable as a structural material, etc. SOLUTION: When a ceramic sintered compact contg. a solid allowed to enter into solid soln. in ceramics for mother crystals is produced, plural clusters 5 not interfering with each other are formed and dispersed in the mother crystals by regulating the total amt. of the constituent elements of the solid allowed to enter into solid soln. to <=2at.% of the amt. of a prescribed constituent element of the ceramics. The solid is allowed to enter into solid soln. only by substitution. The ceramics is Al2 O3 and the solid is Cr2 O3 as their composition formulas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ceramic sintered body and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, there has been known a ceramic sintered body in which a solid solution solid is dissolved in a mother crystal ceramic.
As such a ceramic sintered body, for example, there is a ceramic in which a predetermined amount of Cr ₂ O ₃ is dissolved in Al ₂ O ₃ forming a mother crystal.

It has been reported that Al ₂ O ₃ and Cr ₂ O ₃ completely dissolve in the entire composition at high temperatures (for example, RMS Priggs and SLBender, J. Am. Ceram. Soc., 53).
(1962) p506). Since both Al ₂ O ₃ and Cr ₂ O ₃ have a corundum structure, and their ionic radii are relatively close to 0.53 ° for Al ³⁺ and 0.62 ° for Cr ³⁺ , the substitution-type solid solution To form

[0004] use wherein the Al ₂ O ₃ is known to when the solid solution of Cr ₂ O ₃ traces Al ₂ O ₃ is cured, such ceramic sintered as an abrasive Have been.

[0005]

However, in a ceramic sintered body obtained by dissolving a small amount of a solid for solid solution in a ceramic for a mother crystal as described above, studies on mechanical properties have been sufficiently conducted. No, the mechanism of the increase in hardness has not been elucidated. Therefore, there is a problem that the range of application of the ceramic sintered body as a structural material or the like is limited.

The present invention has been made in view of the above circumstances and problems, and has as its object to provide a ceramic sintered body having a wide range of applications as a structural material and the like, and a method of manufacturing the same.

[0007]

Means for solving the problems The means for the ceramic sintered body of claim 1 for achieving the above object is as follows.
In a ceramic sintered body in which a solid solution solid is solid-dissolved in a ceramic for a mother crystal, the total amount of constituent elements of the solid solution for a solid solution is set to 2 atm for a predetermined constituent element of the ceramic for a mother crystal. % Or less, a plurality of clusters that do not interfere with each other are formed and dispersed in the mother crystal.

[0008] The means of claim 2 is that the solid solution is only a substitution type solid solution.

According to a third aspect of the present invention, both the mother crystal ceramic and the solid solution solid are oxide ceramics.

According to a fourth aspect of the present invention, the ceramic for a mother crystal is an oxide ceramic and the solid for solid solution is a non-oxide ceramic.

According to a fifth aspect of the present invention, the ceramic for the mother crystal is a non-oxide ceramic and the solid for solid solution contains at least an oxide ceramic.

According to a sixth aspect of the present invention, the ceramic for a mother crystal is a non-oxide ceramic and the solid for solid solution contains a non-oxide ceramic and / or an intermetallic compound. .

According to a seventh aspect of the present invention, the ceramic for a mother crystal is represented by a composition formula Al ₂ O ₃ .

According to an eighth aspect of the present invention, the solid solution solid is represented by a composition formula Cr ₂ O ₃ .

According to a ninth aspect of the present invention, there is provided a method for manufacturing a ceramic sintered body, comprising: sintering a powder mixture obtained by mixing a ceramic for a mother crystal and a solid for solid solution at a predetermined ratio; In the method for manufacturing a ceramic sintered body in which a solid solution solid is dissolved, a mixing ratio of the solid solution solid is adjusted by adjusting a total amount of constituent elements of the solid solution solid to be a predetermined amount of the mother crystal ceramic. 2a for the constituent elements of
An object of the present invention is to form and disperse a plurality of clusters in the mother crystal that do not interfere with each other by controlling the content to be t% or less.

According to a tenth aspect of the present invention, the powder mixture is obtained by stirring and mixing ceramic powder for a mother crystal and solid powder for a solid solution by mechanical milling.

According to the eleventh aspect, the powdery mixture is obtained by stirring and mixing a ceramic powder for a mother crystal and a solid sol for a solid solution by mechanical milling.

According to a twelfth aspect of the present invention, the powdery mixture is obtained by previously mixing a solid solution solid during preparation of the mother crystal ceramic powder.

A thirteenth aspect of the present invention resides in that the solid solution is only a substitution type solid solution.

According to a fourteenth aspect, both the mother crystal ceramic and the solid solution solid are oxide ceramics.

According to a fifteenth aspect, the ceramic for the mother crystal is an oxide ceramic and the solid for solid solution is a non-oxide ceramic.

According to a sixteenth aspect of the present invention, the ceramic for a mother crystal is a non-oxide ceramic and the solid for solid solution contains at least an oxide ceramic.

According to a seventeenth aspect of the present invention, the ceramic for a mother crystal is a non-oxide ceramic and the solid for solid solution is a non-oxide ceramic and / or a non-oxide ceramic.
Or it may contain an intermetallic compound.

The means of claim 18 is that the ceramic for a mother crystal is represented by a composition formula Al ₂ O ₃ .

According to a nineteenth aspect, the solid solution solid is represented by a composition formula Cr ₂ O ₃ .

[0026]

Embodiments of the present invention will be described below. The ceramic sintered body according to this embodiment is:
In a ceramic sintered body in which a solid solution solid is solid-dissolved in a ceramic for a mother crystal, the total amount of constituent elements of the solid solution for a solid solution is set to 2 atm for a predetermined constituent element of the ceramic for a mother crystal. % Or less, a plurality of clusters that do not interfere with each other are formed and dispersed in the mother crystal.

As the ceramic for the mother crystal, an oxide ceramic or a non-oxide ceramic can be used. As the oxide ceramics, for example, A
l ₂ O ₃ , MgO, BaTiO ₃ , Y ₂ O _{3 and the} like. Examples of the non-oxide ceramics include S
nitride ceramics such as i ₃ N ₄ , carbide ceramics such as SiC, boride ceramics such as TiB ₂ ,
Silicide-based ceramics such as MoSi ₂ may be used.

Examples of the solid solution solid include oxide ceramics, non-oxide ceramics, intermetallic compounds, oxide ceramics and non-oxide ceramics, or non-oxide ceramics. Those containing an intermetallic compound can be used. Examples of the oxide ceramics include Cr ₂ O ₃ , Al ₂ O ₃ , Z
rO ₂ , Na ₂ O, SiO _{2 and the} like. As the non-oxide ceramics, for example, AlN, Zr
B ₂ , WSi _{2 and the} like. Examples of the intermetallic compound include MoAl _{2 and the} like.

The ceramic for the mother crystal and the solid for solid solution
Various combinations are possible for the mother crystal.
A ceramic obtained as A for ceramics and B for solid solution
When the Mick sintered body is represented as AB, for example, Al_Two
O_Three−Cr_TwoO_Three, MgO-Al _TwoO_Three, BaTiO_Three-Zr
O_Two, Y_TwoO_Three-ZrO_Two, Al_TwoO_Three-Na_TwoO, Al_TwoO_Three
-AlN, Si_ThreeN_Four-SiO_Two, SiC- (Al_TwoO_Three,
AlN), Si_ThreeN_Four− (Al_TwoO_Three, AlN), TiB_Two
-ZrB_Two, MoSi_Two-WSi_Two, MoSi_Two-MoAl
_Two, MoSi_Two− (WSi_Two, MoAl_Two) Etc.
You.

Examples of the type of solid solution include substitutional solid solution, interstitial solid solution, and substitutional solid solution accompanied by interstitial solid solution.

The substitutional solid solution is, for example, Al_TwoO_Three-C
r_TwoO_Three, Al_TwoO_Three-AlN, Si_ThreeN_Four-SiO_Two, Si
C- (Al_TwoO_Three, AlN), Si_ThreeN_Four− (Al_TwoO_Three, A
1N), TiB_Two-ZrB_Two, MoSi_Two-WSi_Two, Mo
Si_Two-MoAl_Two, MoSi _Two− (WSi_Two, MoA
l_Two) Etc.

That is, in the case of Al ₂ O ₃ —Cr ₂ O ₃ , a predetermined amount of Al sites is replaced with Cr. Al ₂ O ₃ -Al
In the case of N, the O site is replaced with N. Si ₃ N ₄ −
In the case of SiO ₂ , the N site is replaced with O. Si
In the case of C- (Al ₂ O ₃ , AlN), the Si site is A
At 1, the C site is replaced with O and / or N, respectively. Si ₃ N ₄ - in the case of (Al ₂ O _3, AlN) is, Si
The site is replaced by Al and the N site is replaced by O.
In the case of TiB ₂ -ZrB ₂ , the Ti site is replaced with Zr. In the case of MoSi ₂ —WSi ₂ , the Mo site is replaced with W. In the case of MoSi ₂ -MoAl ₂ , S
The i site is replaced with Al. MoSi ₂ − (WSi ₂ ,
In the case of MoAl ₂ ), the Mo site is replaced by W and the Si site is replaced by Al.

The interstitial solid solution is, for example, Al ₂ O ₃ —N
Occurs in a ₂ O and the like. That is, in this case, Na ⁺ penetrates between lattices of the mother crystal.

The substitutional solid solution accompanied by the interstitial solid solution is, for example,
For example, MgO-Al_TwoO_Three, BaTiO _Three-ZrO_Two, Y_TwoO_Three
-ZrO_TwoAnd so on. That is, Y_TwoO_Three-ZrO_TwoIn the case of
Means that the Y site is replaced with Zr,³⁺Is Zr⁴⁺so
Is replaced, so that the mother crystal
O between lattices^2-Invades. MgO-Al_TwoO_ThreeAnd BaTi
O_Three-ZrO_TwoThe same applies to the case of.

The constituent elements of the solid solution solid are:
The substitutional solid solution replaces any one of the constituent elements of the mother crystal ceramic, and the interstitial solid solution penetrates between lattices of the mother crystal. Therefore, the total amount is
It is a combination of one or both of the constituent elements that are substituted for solid solution and the constituent elements that are for interstitial solid solution. For example, when both the Si site and the N site are respectively replaced by the constituent elements of the solid for solid solution as in the above Si ₃ N ₄ — (Al ₂ O ₃ , AlN), the total amount becomes The amounts of the respective constituent elements of the solid-solution solid to be substituted and formed into a solid solution are combined. Also, as in the above Y ₂ O ₃ -ZrO ₂ ,
Y ³⁺ is replaced by Zr ⁴⁺ and O
^In the case of substitutional solid solution accompanied by interstitial solid solution in which ^2-
The total amount is Z, which is a constituent element of the solid solution solid which is dissolved.
r ⁴⁺ and O ²⁻ are combined.

Here, the criterion for determining the total amount is a predetermined constituent element of the ceramic for a mother crystal. That is, in the case of a substitution type solid solution in which only one of the constituent elements of the ceramic for a mother crystal is replaced, the replaced constituent element is used as a reference. In the case of a substitution type solid solution in which two or more types of constituent elements of the ceramic for the mother crystal are respectively substituted, when a metal element is included in the constituent elements of the ceramic for the mother crystal, the metal element is used as a reference,
When a metalloid element such as Si is contained without a metal element, it is desirable to use the metalloid element as a reference. In the case of interstitial solid solution in which constituent elements of the solid for solid solution enter between lattices of the mother crystal, the metal element of the ceramic for the mother crystal is used as a reference. In the case of the substitutional solid solution accompanied by the interstitial solid solution, it is preferable that the substitutional element of the ceramic for the mother crystal be used as a reference.

In the ceramic sintered body, since the total amount of the constituent elements of the solid solution for solid solution is 2 at% or less with respect to the predetermined constituent elements of the ceramic for the mother crystal as described above. A predetermined range including a solid-solution solid constituent element in which one of the constituent elements of the mother crystal ceramics is irregularly substituted, or a predetermined range including a solid-solution solid constituent element that randomly enters between lattices of the mother crystal. The ranges can be clusters that do not interfere with each other. By forming and dispersing a plurality of clusters in the mother crystal that do not interfere with each other, there is an advantage that the fracture strength can be increased in addition to the hardness and Young's modulus of the ceramic sintered body.

Next, such improvement in mechanical properties will be described with reference to a model shown below, taking, for example, Al ₂ O ₃ -Cr ₂ O ₃ as an example.

As shown in FIGS. 1 and 2, Al ^{3 +} 1 and C ³
r ³⁺ 2 are both present is surrounded by six O ^2-3. This octahedron is considered as one cluster, and is represented as [AlO ₆ ] cluster 4 and [CrO ₆ ] cluster 5, respectively.

Here, the ionic radius of each constituent element is 0.53 ° for Al ^{3 +} 1, 0.62 ° for Cr ^{3 +} 2,
Since at 1.40Å ^2-3, [AlO _6] radius of the cluster 4 1.93A, the radius of [CrO _6] cluster 5 is 2.02A, slightly greater in [CrO _6] cluster 5 .

When Al ^{3 +} 1 is replaced by Cr ³⁺ 2 by the substitutional solid solution, [AlO ₆ ] cluster 4 is replaced by [CrO ₆ ] cluster 5 as shown in FIG. Become. Therefore, around the [CrO ₆ ] cluster 5,
A lattice level compressive stress CS and a tensile stress TS occur.
It is known that the compressive stress CS is twice the tensile stress TS. Therefore, it is considered that the compressive stress CS exists around the [CrO ₆ ] cluster 5.

Here, in a system in which alumina particles are dispersed in glass, it is known that a compressive stress (residual stress) is generated around the alumina particles because glass has a larger coefficient of thermal expansion ( Yutaka Kagawa, Hiroshi Hatta, “Ceramic-Based Composite Materials,” Agune Shofusha, p198). As shown in FIG. 3, the magnitude of the compressive stress (residual stress) is uniform inside the alumina particles, and affects up to two to three times the radius of the alumina particles in the glass.

It is considered that the compressive stress field around the [CrO ₆ ] cluster 5 also influences up to two to three times the radius of the [CrO ₆ ] cluster 5 as described above. Since the stress is given by the vector, their overlap cancels out and the effect is reduced. From this, the compression stress fields do not overlap [Cr
The content of [O ₆ ] cluster 5 can be calculated as follows.

Here, all the particles have the same radius a,
It is known that the distance 2b between particles under the condition of non-uniform dispersion can be expressed by the following equation (1)
Ardell, Act. Metal., 20 (1972) p61).

[0045]

(Equation 1)

[0046] Formula 1 number above, the radius a of the [CrO _6] clusters 5, [CrO _6] can be applied to the calculation of the distance 2b between clusters 5, it was calculated from the equation of this number 1 [CrO ₆ ] cluster 5 content V _f (vol
%) And a / b are shown in FIG.

FIG. 4 shows that the magnitude of the compressive stress field is [CrO
₆] If the radius is twice the radius of cluster 5, its inclusion
The amount is 1.2 vol%, and if it is 3 times, 0.4 vol
%. Therefore, [CrO₆] Content of Cluster 5
Is greater than 1.2 vol%, the compressive stress fields overlap
Will fit. In addition, Cr_TwoO_ThreePer volume [Cr
O ₆] Since two volumes of cluster 5 are generated, this is
l_TwoO_Three0.53mol% of solid solution
If more, the compressive stress fields will overlap. Reverse
And Cr_TwoO_ThreeIs 0.53 mol% or less, that is,
Al³⁺Dissolves in Cr³⁺0.53
at% or less, the CrO₆] Cluster 5
Without being affected by the compressive stress CS
It is thought to grow. The effect of this compressive stress CS
Which increase hardness, Young's modulus, and breaking strength
it is conceivable that.

From the above, the total amount of constituent elements in the solid solution solid is 2 at% or less, preferably 1 at% or less.
t% or less, more preferably 0.6 at% or less. If the total amount is more than 2 at%, the densification is hindered, that is, the progress of sintering is delayed, the Young's modulus is reduced due to a decrease in the atomic bonding force, or the fracture toughness is reduced due to the decrease in the Young's modulus. Is not desirable.
In the above, Al ₂ O ₃ —Cr ₂ where substitution type solid solution occurs
The case of O ₃ has been described, but the same applies to the case of interstitial solid solution or substitutional solid solution accompanied by interstitial solid solution.

Further, for example, the above Al ₂ O ₃ —Cr ₂ O ₃
And TiB ₂ -ZrB as _2, etc., wherein when the solid solution is only substituted solid solution, interstitial solid solution and, or crystals themselves seen in the case of a substitutional solid solution with interstitial solid solution There is an advantage that embrittlement and changes in basic physical properties such as electrical conductivity are unlikely to appear.

When both the mother crystal ceramic and the solid solution solid are oxide ceramics, a large amount of easily sinterable, high quality and inexpensive powder is supplied. There is an advantage that a ceramic sintered body can be easily and inexpensively manufactured.

When the mother crystal ceramic is an oxide ceramic and the solid solution solid is a non-oxide ceramic, the heat resistance and the thermal shock resistance can be improved in addition to the above effects. There is an advantage.

When the mother crystal ceramic is a non-oxide ceramic and the solid solution solid contains at least an oxide ceramic, it has excellent heat resistance, corrosion resistance, hardness, mechanical strength and the like. There is an advantage that oxidation resistance and the like can be improved.

In the case where the mother crystal ceramic is a non-oxide ceramic and the solid solution solid contains a non-oxide ceramic and / or an intermetallic compound,
There is an advantage that it is excellent in heat resistance, corrosion resistance, hardness, mechanical strength and the like.

The ceramic for the mother crystal has a composition formula of Al ₂
When represented by O ₃ , there is an advantage that it has high hardness and is excellent in wear resistance, corrosion resistance, and the like. In this case, particularly when the solid solution solid is represented by the composition formula Cr ₂ O ₃ , there is an advantage that only substitutional solid solution occurs. Moreover, Al
And Cr have the same valence, so that almost no lattice vacancies are generated, and therefore, there is an advantage that the mother crystal does not become brittle.

Next, a method of manufacturing the ceramic sintered body will be described. The method for manufacturing a ceramic sintered body according to this embodiment includes sintering a powder mixture obtained by mixing a mother crystal ceramic and a solid solution solid at a predetermined ratio, and solidifying the solid solution solid in the mother crystal ceramic. Is to dissolve.

At this time, the mixing ratio of the solid solution solid is adjusted so that the total amount of constituent elements of the solid solution solid is 2 at% or less with respect to a predetermined constituent element of the mother crystal ceramic. Thus, a plurality of clusters that do not interfere with each other are formed and dispersed in the mother crystal.

The powder mixture is prepared in advance by stirring and mixing the ceramic powder for the mother crystal and the solid powder for the solid solution by mechanical milling.

Then, this powdery mixture is subjected to a normal pressure sintering method, a hot press (HP) method, a vacuum hot press (VHP), depending on the product use of the obtained ceramic sintered body.
And an appropriate sintering method selected from hot isostatic pressing (HIP), injection molding and the like.
At this time, the powdered mixture may be formed into a desired product shape before sintering, or the forming and sintering may be performed simultaneously.

The mixing ratio of the solid solution solid is, for example, A
In the case of l ₂ O ₃ -Cr ₂ O ₃ , the atomic ratio of Al to Cr is 1: 1, and the substitutional solid solution of Cr ³⁺ is less than 2 at% with respect to Al ³⁺ . Al ₂ O ₃
Should be mixed with ₂ mol% or less of Cr ₂ O ₃ .

In the case of Y ₂ O ₃ —ZrO ₂ , as described above, Y ³⁺ is replaced by Zr ⁴⁺ and O ²⁻ enters between lattices of the mother crystal. Since one Y ³⁺ is replaced with Zr ⁴⁺ , O ²⁻ is reduced to １ ／ to maintain electrical neutrality.
Therefore, a total of 1.5 constituent elements of the solid solution solid are dissolved in each Y ³⁺ . Furthermore, Y and Zr
Since the atomic ratio of ZrO ₂ is 2: 1 with respect to Y ³⁺ , the atomic ratio of ZrO ₂ is set to 2 at% or less with respect to Y ³⁺ . 8/3 (mol%) That is, ZrO ₂ of about 2.67 mol% or less may be mixed.

Similarly, MoSi _2- (WSi ₂ , MoAl
_In case ₂ ), the Mo site is W and the Si site is Al
Respectively, and the atomic ratio of Mo to W and Si and Al
Are all 1: 1 and therefore WSi ₂ and Mo
In order to make the total amount of constituent elements of the solid solution solid containing Al ₂ into 2 at% with respect to Mo, WSi ₂ and Mo
The Al ₂ may be mixed so that less 2 mol% in total.

As described above, the solid for solid solution may be mixed in an appropriate amount in combination with the ceramic for the mother crystal to prepare a powdery mixture.

Here, when a powder mixture is prepared by stirring and mixing the ceramic powder for the mother crystal and the solid powder for solid solution by mechanical milling, the ceramic powder for the mother crystal and the solid powder for solid solution are uniformly mixed. There is an advantage that it can be mixed and sufficiently miniaturized.

The mechanical milling includes a ball mill,
It may be carried out for several hours to several tens of hours using an appropriate milling device such as a vibration mill and an attritor.

In the above mechanical milling, when a solid sol for solid solution is used, there is an advantage that mixing can be performed more uniformly.

The solid solution solid may be coated on the surface of the mother crystal ceramic by a sol-gel method, a coprecipitation method, or by applying a solid solution solid nitrate solution or the like to the mother crystal ceramic. When the solid for solid solution is previously mixed during the preparation of the ceramic powder for the mother crystal, there is an advantage that the mixture can be more uniformly mixed and further refined.

Next, by sintering a powder mixture obtained by mixing the ceramic for the mother crystal and the solid for solid solution at the above ratio, a plurality of clusters which do not interfere with each other are formed in the mother crystal as described above. Can be dispersed.

[0068]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0069] Example _{1 (Al 2 O 3 -Cr 2} O 3) Al 2 O 3 as a host crystal ceramics were selected Cr ₂ O ₃ solid solution solids. As a starting material, α-Al ₂ O ₃ manufactured by Sumitomo Chemical Co., Ltd. (AKP-30, <0.4 μm,
Purity 99.99%) and Cr ₂ O manufactured by Kojundo Chemical Laboratory
₃ (98778C, 3 μm, purity 99.98%) was used. The chemical composition of these raw material powders is as shown in Table 1 below.

[0070]

[Table 1]

When the mixing ratio of Cr ₂ O ₃ is 0.26, 0.4
3 and 0.88 mol% (total solid solution, at%), respectively, and weighed to prepare a sample of a ceramic sintered body in the process shown in FIG. That is, a diameter of 0.5 in ethanol
Wet ball mill mixing was performed for 24 hours using alumina balls having a diameter of 2 cm. After drying with microwaves, dry ball mill mixing was performed using alumina balls having a diameter of 1 cm for 24 hours, followed by sufficient pulverization to prepare a powdery mixture. The obtained powdery mixture was subjected to hot press sintering for 1 hour at 1400 to 1600 ° C. and 30 MPa in an argon atmosphere using a carbon die. After cutting the obtained ceramic sintered body with a diamond cutter, mirror polishing is performed using a diamond slurry (9, 3, 1/2 μm),
Approximately 10 3 × 4 × 36 mm sample pieces were prepared. In the same manner, a sample of Al ₂ O ₃ single phase was prepared.

Using the obtained sample, 1400 ° C. and 1
For those sintered at 500 ° C, hardness (Vickers hardness), Young's modulus (resonance method), fracture toughness (microindenter press-in fracture method (IF method)), fracture strength (in air, three-point bending test,
Span = 30mm, crosshead speed = 0.5mm
/ Min). These results are shown in FIGS. 6 to 9, respectively.

As shown in FIGS. 6 to 9, a small amount of Cr was added to Al ₂ O _3.
By dissolving ₂ O ₃ , hardness, Young's modulus, and breaking strength were each increased. The fracture toughness is Al ₂ O ₃
It was almost the same as the single phase.

The material sintered at 1400 ° C. was subjected to thermal etching under the same conditions, and the surface was observed by SEM (scanning electron microscope). As a result, as shown in FIG. There is almost no difference in
The shape and particle size distribution of the particles were almost the same. Further, those sintered at 1500 ° C. had the same tendency.

[0075] As a result of observation by SEM of the fracture surface of the sample piece after breaking strength measurement, but Al ₂ O ₃ grain boundary fracture and transgranular fracture is a single phase had coexisted, the mixing amount of Cr ₂ O ₃ The fracture mode changed to intragranular fracture with increasing.

Example 2 (Al ₂ O ₃ —AlN) Al ₂ O ₃ was selected as a ceramic for a mother crystal, and AlN was selected as a solid solution solid. A ceramic sintered body was produced in the same manner as in Example 1.

Example 3 (Si ₃ N ₄ —SiO ₂ ) Si ₃ N ₄ was selected as the ceramic for the mother crystal and SiO ₂ was selected as the solid solution solid, and a ceramic sintered body was produced in the same manner as in Example 1. did.

[0078] Example _{4 (MoSi 2 -WSi 2) MoSi} 2 as host crystals for ceramics, select the WSi ₂ solid solution for a solid, to produce a ceramic sintered body in the same manner as in Example 1.

[0079] Comparative Example _{1~6 (Al 2 O 3 -Cr 2} O 3) and for Al ₂ O ₃ host crystal ceramics, select the Cr ₂ O ₃ solid solution for a solid, the Cr ₂ O _3, respectively 4 .4mo
1% (Comparative Example 1), 8.9 mol% (Comparative Example 2), 1
8.0 mol% (Comparative Example 3), 27.3 mol% (Comparative Example 4), 36.9 mol% (Comparative Example 5), 46.7 mol
A ceramic sintered body was manufactured in the same manner as in Example 1 except that 1% (Comparative Example 6) was mixed.

In Examples 2 to 4, hardness, Young's modulus, fracture toughness, and fracture strength were measured in the same manner as in Example 1 except that the total amount of solid solution sintered at 1500 ° C. was 0.43 at%. . The results are shown in Example 1 and Comparative Examples 1 to
Table 2 below shows the results together with the results of Example 6.

[0081]

[Table 2]

In Comparative Examples 1 to 6, 1500 ° C.
In for thermal etching in the same manner as in Example 1 for those sintered, result of the surface thereof an SEM, as shown in FIG. 11, the mixing amount of the average particle diameter of the mother crystal grains Cr ₂ O ₃ is It decreased as it increased. From this, C
The reason why the breaking strength increased in the region where the mixing amount of r ₂ O ₃ was large is that
It is considered that the decrease in the average grain size of the mother crystal grains also reduced the size of the fracture source. The hardness is also increased, which is considered to be because the dislocation movement is suppressed by the solid solution of Cr ₂ O ₃ in addition to the decrease in the average particle size of the mother crystal particles. On the other hand, the Young's modulus is Cr
_It decreased as the mixing amount of ₂ O ₃ increased. This is A
Al ³⁺ in the l ₂ O ₃ lattice is Cr ^{3+ having} a larger ionic radius.
This is considered to be due to the fact that the average interatomic distance was increased and the bonding force between the atoms was weakened. Also,
It is considered that the fracture toughness was also reduced due to the decrease in Young's modulus.

[0083]

As described above, according to the first and ninth aspects of the present invention, in a ceramic sintered body in which a solid solution solid is dissolved in a ceramic for a mother crystal, the solid solution solid is formed. By setting the total amount of the dissolved constituent elements to 2 at% or less with respect to a predetermined constituent element of the ceramic for the mother crystal, a plurality of clusters that do not interfere with each other are formed and dispersed in the mother crystal. A predetermined range including a solid-solution solid constituent element in which one of the constituent elements of the mother crystal ceramics is irregularly substituted, or a predetermined range including a solid-solution solid constituent element that randomly enters between lattices of the mother crystal. The ranges can be clusters that do not interfere with each other. Therefore, it is possible to increase the Young's modulus and the fracture strength in addition to the hardness of the ceramic sintered body, and there is no decrease in the fracture toughness, so that the applicable range of the ceramic sintered body as a structural material can be widened. There are advantages.

According to the second and thirteenth aspects,
Since the solid solution is only a substitution type solid solution,
Alternatively, there is an advantage that embrittlement of the crystal itself and a change in basic physical properties such as electric conductivity do not appear in the case of the substitutional solid solution accompanied by the interstitial solid solution.

According to the third and fourteenth aspects of the present invention,
Since both the mother crystal ceramic and the solid solution solid are oxide ceramics, a large amount of high-quality and inexpensive powder is supplied with easy sintering properties. There is an advantage that it can be manufactured at low cost.

According to the fourth and fifteenth aspects of the present invention,
Since the ceramic for the mother crystal is an oxide ceramic and the solid for solid solution is a non-oxide ceramic, the heat resistance and the thermal shock resistance can be improved in addition to the effects of claims 3 and 14. There is an advantage.

According to the fifth and sixteenth aspects of the present invention,
Since the mother crystal ceramic is a non-oxide ceramic and the solid solution solid contains at least an oxide ceramic, it has excellent heat resistance, corrosion resistance, hardness, mechanical strength, and oxidation resistance. There is an advantage that it can be improved.

According to the invention of claims 6 and 17,
Since the mother crystal ceramic is a non-oxide ceramic and the solid solution solid contains a non-oxide ceramic and / or an intermetallic compound, heat resistance, corrosion resistance,
There is an advantage of being excellent in hardness, mechanical strength, and the like.

According to the invention of claims 7 and 18,
Since the ceramic for a mother crystal is represented by the composition formula Al ₂ O ₃ , there is an advantage that it has high hardness and is excellent in abrasion resistance and corrosion resistance.

According to the eighth and nineteenth aspects,
Since the solid solution solid is represented by the composition formula Cr ₂ O ₃ , when the mother crystal ceramic is Al ₂ O ₃ , there is an advantage that only substitutional solid solution occurs. Moreover, Al and Cr
Have the same valence, there is almost no generation of lattice vacancies, and therefore, there is an advantage that the mother crystal does not become brittle.

According to the tenth aspect of the present invention, since the powdery mixture is obtained by stirring and mixing the ceramic powder for mother crystal and the solid powder for solid solution by mechanical milling, There is an advantage that the solid powder for use can be uniformly mixed and can be sufficiently refined.

According to the eleventh aspect of the present invention, the powdery mixture is obtained by stirring and mixing a ceramic powder for a mother crystal and a solid sol for a solid solution by mechanical milling. Thus, there is an advantage that mixing can be performed more uniformly.

According to the twelfth aspect of the present invention, the powdery mixture is prepared by previously mixing a solid solution solid during the preparation of the mother crystal ceramic powder. In addition, there is an advantage that the mixture can be more effectively and uniformly mixed, and the size can be further reduced.

[Brief description of the drawings]

FIG. 1 is a model diagram showing a coordination state of Al ³⁺ and Cr ³⁺ .

FIG. 2 is a model diagram of compressive stress generated by cluster replacement.

FIG. 3 is a graph of compressive stress (residual stress) generated by dispersing alumina particles in glass.

FIG. 4. [CrO ₆ ] cluster content and adjacent [C
[rO ₆ ] is a graph showing the relationship between distances between clusters.

FIG. 5 is a process chart of Example 1.

FIG. 6 is a graph showing the relationship between the mixing amount of Cr ₂ O ₃ and hardness in the obtained Al ₂ O ₃ —Cr ₂ O ₃ ceramic sintered body.

FIG. 7 is a graph showing the relationship between the mixed amount of Cr ₂ O ₃ and the Young's modulus in the obtained Al ₂ O ₃ —Cr ₂ O ₃ ceramic sintered body.

FIG. 8 is a graph showing the relationship between the mixing amount of Cr ₂ O ₃ and the fracture toughness in the obtained Al ₂ O ₃ —Cr ₂ O ₃ ceramic sintered body.

FIG. 9 is a graph showing the relationship between the amount of Cr ₂ O ₃ mixed and the fracture strength in the obtained Al ₂ O ₃ —Cr ₂ O ₃ ceramic sintered body.

FIG. 10 is a graph showing the relationship between the mixed amount of Cr ₂ O ₃ and the average particle size in the obtained Al ₂ O ₃ —Cr ₂ O ₃ ceramic sintered body.

FIG. 11 shows the obtained Al ₂ O ₃ − in Comparative Examples 1 to 6.
4 is a graph showing the relationship between the mixed amount of Cr ₂ O ₃ and the average particle size in a Cr ₂ O ₃ ceramic sintered body.

[Explanation of symbols]

1 Al ³⁺ 2 Cr ³⁺ 3 O ^2-4 [AlO ₆ ] cluster 5 [CrO ₆ ] cluster

Claims (19)

[Claims] 1. In a ceramic sintered body in which a solid solution solid is dissolved in a ceramic for a mother crystal, a total amount of constituent elements of the solid solution for a solid solution is determined by a predetermined configuration of the ceramic for the mother crystal. 2at% for element
A ceramic sintered body characterized in that a plurality of clusters that do not interfere with each other are formed and dispersed in a mother crystal by the following. 2. The ceramic sintered body according to claim 1, wherein the solid solution is only a substitution type solid solution. 3. The ceramic sintered body according to claim 1, wherein the ceramic for the mother crystal and the solid for solid solution are both oxide ceramics. 4. The ceramic sintered body according to claim 1, wherein said mother crystal ceramic is an oxide ceramic, and said solid solution solid is a non-oxide ceramic. 5. The ceramic sintered body according to claim 1, wherein the ceramic for the mother crystal is a non-oxide ceramic and the solid for solid solution contains at least an oxide ceramic. 6. The ceramic for a host crystal is a non-oxide ceramic and the solid for solid solution contains a non-oxide ceramic and / or an intermetallic compound. Ceramic sintered body. 7. The ceramic for a mother crystal according to claim 1, wherein the composition formula is Al.
Ceramic sintered body according to any one of claims 1 to 4, characterized by being represented by ₂ O _3. 8. The ceramic sintered body according to claim 7, wherein said solid for solid solution is represented by a composition formula: Cr ₂ O ₃ . 9. A method for producing a ceramic sintered body, comprising sintering a powdery mixture obtained by mixing a ceramic for a mother crystal and a solid for solid solution at a predetermined ratio, and forming a solid solution for the solid for solid solution in the ceramic for a mother crystal. In the above, the mixing ratio of the solid solution solid is adjusted so that the total amount of constituent elements of the solid solution solid is 2 at% or less with respect to a predetermined constituent element of the ceramic for a mother crystal. Forming and dispersing a plurality of clusters in a mother crystal that do not interfere with each other. 10. The powdery mixture obtained by stirring and mixing ceramic powder for a mother crystal and solid powder for a solid solution by mechanical milling.
A method for producing the ceramic sintered body described in the above. 11. The powdery mixture obtained by stirring and mixing a ceramic powder for a mother crystal and a solid sol for a solid solution by mechanical milling.
A method for producing the ceramic sintered body described in the above. 12. The method for producing a ceramic sintered body according to claim 9, wherein said powdery mixture is obtained by previously mixing a solid solution solid during preparation of a ceramic powder for a mother crystal. 13. The method for producing a ceramic sintered body according to claim 9, wherein said solid solution is only a substitution type solid solution. 14. The method for producing a ceramic sintered body according to claim 9, wherein both the mother crystal ceramic and the solid solution solid are oxide ceramics. 15. The ceramic for a mother crystal is an oxide ceramic and the solid for solid solution is a non-oxide ceramic.
4. The method for producing a ceramic sintered body according to any one of the above items 3. 16. The ceramic firing method according to claim 9, wherein the ceramic for the mother crystal is a non-oxide ceramic and the solid for solid solution contains at least an oxide ceramic. The method of manufacturing the aggregate. 17. The method according to claim 9, wherein the ceramic for the mother crystal is a non-oxide ceramic and the solid for solid solution contains a non-oxide ceramic and / or an intermetallic compound. The method for producing a ceramic sintered body according to any one of the above. 18. The ceramic for a mother crystal according to claim 1, wherein
method for producing a ceramic sintered body according to any one of claims 9 to 15, characterized by being represented by l ₂ O _3. 19. The method for producing a ceramic sintered body according to claim 18, wherein said solid solution solid is represented by a composition formula: Cr ₂ O ₃ .