JP2001080971A - Production of ceramic composite sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a ceramic composite sintered compact, which is capable of preventing lowering in strength of the sintered compact by uniformly dispersing at least two kinds of particles and eliminating heterogeneous aggregate parts. SOLUTION: In a method for producing a ceramic composite sintered compact, which comprises drying a slurry containing at least two kinds of ceramic particles different in the density and/or the particle size to obtain dried particles, thereafter forming the dried particles and sintering the formed green body, the ceramic particles are allowed to previously and uniformly aggregate in the slurry by controlling the absolute value of zeta potential of the ceramic particles to be not more than 50 mV, preferably 25 mV. Thereby, it becomes possible to allow the ceramics different in the density or the particle size to uniformly complex, and the heterogeneous aggregate parts in the texture of the sintered compact are avoided. Accordingly, the strength of the ceramic composite sintered compact can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a ceramic composite sintered body produced using two or more types of ceramic particles having different specific gravities and / or particle sizes as raw materials. The ceramic composite sintered body produced by the production method of the present invention can be suitably used for sliding parts used in a high-temperature, high-stress environment, such as a jig for steel rolling and a cutting tool.

[0002]

2. Description of the Related Art In order to improve the material properties of ceramics, components such as particles, whiskers or fibers are mixed,
Making a ceramic composite sintered body has been widely performed conventionally. In such a ceramic composite sintered body,
In order to prevent a decrease in strength, it is desirable that the structure of the sintered body be as uniform as possible. Then, in order to achieve a uniform structure of the sintered body, it is necessary to uniformly disperse each ceramic particle as a raw material. Therefore, it is important how to control the behavior of the ceramic particles having different specific gravities or particle diameters during the production of the ceramic composite sintered body.

[0003] In order to make the structure of the sintered body uniform, a method of preparing a slurry containing ceramic particles as a raw material in a manufacturing process and improving the dispersibility of each ceramic particle in the slurry has conventionally been proposed. Was used. As a method of improving dispersibility, a method of controlling the zeta potential of each ceramic particle at the time of mixing the raw materials or at the stage of slurry after the mixing is known. For example, in the production of Si ₃ N ₄ / SiC ceramics,
When the absolute value of the zeta potential is increased by the same sign by adjusting the pH, the dispersibility of each ceramic particle in the slurry can be improved, and the slurry is spray-dried while applying ultrasonic vibration, and the obtained base powder is subjected to normal pressure. After sintering,
It is known that a sintered body having high toughness and high hardness can be obtained (Japanese Patent Laid-Open No. 22179/1990). In addition, a method for producing a short fiber reinforced ceramics sintered body performed by the same production method (Japanese Patent Application Laid-Open Nos. 2-97469 and 1-230)
484) is also known.

However, in each of the above documents, the dispersibility of each ceramic particle in the slurry is increased by increasing the absolute value of the zeta potential of each ceramic particle in the slurry to increase the electrostatic repulsion between the particles. Is limited to those that improve.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made by dispersing two or more types of ceramic particles having different specific gravities and / or particle sizes uniformly in a slurry to obtain a non-uniform ceramic particle. It is an object of the present invention to provide a method of manufacturing a ceramic composite sintered body that can eliminate an agglomerated portion and prevent a reduction in strength of the sintered body.

[0006]

Means for Solving the Problems Particles having a large specific gravity difference,
Alternatively, when ceramic particles having greatly different particle diameters are compounded, even if the dispersibility of each ceramic particle is improved in the slurry, the ceramic particles are separated in the slurry drying step (spray drying) and become non-uniform. (See FIGS. 4B and 4C). This is because small ceramic particles move to the surface as water evaporates, or heavy ceramic particles move to the surface under the influence of centrifugal force due to the rotation of droplets. And as a result of the obtained sintered body structure becoming non-uniform due to this separation,
There is a possibility that the strength of the sintered body may be reduced due to the non-uniform aggregation portion.

In view of the above circumstances, the present inventors have studied a method for manufacturing a ceramic composite sintered body. As a result, in order to suppress the movement of ceramic particles during spray drying, the dispersibility of each ceramic particle in the slurry was reduced. Contrary to the conventional technology of improving, it is found that a ceramic composite sintered body in which two or more types of ceramic particles are uniformly dispersed can be obtained by uniformly aggregating each ceramic particle in the slurry immediately before spray drying. The present invention has been completed.

[0008] The method for producing a ceramic composite sintered body of the first invention is characterized in that a slurry containing two or more types of ceramic particles having different specific gravities and / or particle diameters is dried, and then the dried ceramic particles are used. A method of manufacturing and sintering a ceramic composite sintered body is characterized in that the ceramic particles are uniformly agglomerated in advance in a slurry, and then dried by spray drying.

The ceramic composite sintered body produced in the first invention comprises two or more kinds of the above "ceramic particles". The “ceramic particles” are not particularly limited, and various types, shapes, and particle diameters can be used depending on the ceramic composite sintered body to be produced. Here, in the first invention, ceramic particles having a particularly large difference in density of ceramic particles, specifically, a density ratio of usually 1.5 or more, preferably 1.5 to 5.
0, more preferably 1.5 to 4.0, or a composite of ceramic particles, or when the particle diameters of the ceramic particles are significantly different, specifically in a particle size ratio of usually 0.02 to 1, It is suitable when the ceramic particles having a particle size of preferably 0.02 to 0.5, more preferably 0.03 to 0.3 are compounded. The specific gravity ratio and the particle size ratio are values calculated by the following equations. Density ratio: (density of one particle) / (density of the other particle) where the denominator is the particle with the smaller density. Particle size ratio: (particle size of one particle) / (particle size of the other particle) where the denominator is the particle having the larger particle size. Then, a known sintering aid is added to the raw material, mixed by a known method, and a dispersion medium such as water is added to form a slurry.

Then, before performing the step of drying the slurry by spray drying, the ceramic particles are uniformly agglomerated in advance in the slurry. There is no particular limitation on the method for uniformly aggregating the ceramic particles in advance in the slurry, but usually, by reducing the zeta potential of each ceramic particle, the electrostatic repulsion between the ceramic particles is reduced, Each ceramic particle is previously uniformly agglomerated in the slurry. When the zeta potential of each ceramic particle is reduced in this way, as shown in the schematic diagram of [A] of FIG. 4, particles close to each other occur due to a decrease in electrostatic repulsion, and each ceramic particle is uniformly mixed. Agglomerates are formed.

The absolute value of the zeta potential of each ceramic particle is generally adjusted to 50 mV or less, preferably 30 mV or less, more preferably 25 mV or less, as shown in the second invention. If the absolute value of the zeta potential exceeds 50 mV, the electrostatic repulsion between the ceramic particles in the slurry becomes large, and it is not preferable because the ceramic particles cannot be uniformly aggregated.

In the above case, since the zeta potential of each ceramic particle in the slurry is greatly affected by the pH of the slurry, the zeta potential of each ceramic particle is controlled to a preferable range by adjusting the pH of the slurry. be able to. For example, as ceramic particles Si
₃ in the case of using the N ₄ and TiN, pH of the slurry is usually from 8.5 to 11.5, preferably 9.0 to 11.0, in the case of using Si ₃ N ₄ and SiC, usually 7 0.5-1
1.0, preferably 8.0-10.5.

Furthermore, in the above case, the zeta potential of each ceramic particle in the slurry is affected by the dispersant added to the slurry. The dispersant applicable to the present invention is not particularly limited as long as the zeta potential can be controlled within a predetermined range, and examples thereof include a polycarboxylate such as ammonium polycarboxylate.

After the ceramic particles are uniformly agglomerated in advance in the slurry, the slurry is dried by a spray-drying method, a binder is added and molded, and then sintering is performed. To manufacture. As described above, when the ceramic particles are uniformly agglomerated in advance in the slurry, the movement of the particles is remarkably suppressed, so that the separation of the ceramic particles during spray drying does not occur. As a result, the sintered body structure of the manufactured ceramic composite sintered body becomes uniform.

As used herein, the term “uniform sintered body structure” refers to an arbitrary 300 μm × 300 μm field of view (FIG. 5) from an electron microscope photograph of 200 times or more, as shown in FIG. The worst part of the dispersion state is 2
It is picked up in a square visual field (approximately 3000 times) of 0 μm × 20 μm (FIG. 5), and the area ratio A of the other ceramic particle to one ceramic particle serving as a matrix by image analysis (total area of the other ceramic particle / the entire visual field) Area), and the dispersibility index obtained by the following equation is 0.7 or more. Dispersibility index = A / addition ratio of the other ceramic particle (however, A <addition ratio of the other ceramic particle)

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described with reference to Examples and
This will be specifically described with reference to Comparative Examples and Comparative Examples. (1) Examples 1 to 3 and Comparative Examples 1 and 2 Two types of cells having a specific gravity ratio of 1.73 and a particle size ratio of 0.25.
Lamix particles (Si _ThreeN_FourAnd TiN).

Production of Ceramic Composite Sintered Material As a raw material, particles A (Si ₃ N ₄ powder, density 3.19 g /
cm ³ , average particle size 0.3 μm), particle B (TiN powder,
A density of 5.53 g / cm ³ , an average particle size of 1.2 μm) and a sintering aid (CeO ₂ , MgO, Al ₂ O ₃ , ZrO ₂ ) were used. The particles A, B and the sintering aid were transferred to a ball mill to obtain a raw material powder (particles A: 62 vol.
%, Particles B: 33 vol%, sintering aid: 5 vol% [C
eO ₂ , MgO, Al ₂ O ₃ , ZrO ₂ were each 1.25 vol.
%)]). To 200 g of the raw material powder, 300 ml of water as a dispersion medium was added, and the dispersant shown below was added thereto.
To the total of 100 parts by weight of the particles A, B and the sintering aid, a solid content of 0.55% was added, followed by mixing for 50 hours, and then a binder (microwax emulsion, acrylic (Resin emulsion) was added in an amount of 8 parts by weight based on a total of 100 parts by weight of the particles A, the particles B and the sintering aid, followed by ball milling for 1 hour to prepare a slurry. The added dispersants are as follows. [1] Dispersant A: ammonium polycarboxylate (manufactured by San Nopco, trade name "SN Dispersant 5468") [2] Dispersant B: quaternary ammonium salt (manufactured by San Nopco, trade name "SN Dispersant 7347-C") ")

The slurry obtained as described above is
After adjusting to the respective pHs shown in Table 1 using an H adjuster (nitric acid, aqueous ammonia), it was dried by spray drying under the conditions of a drying temperature of 100 to 140 ° C., a disk rotation speed of 5,000 rpm, and a feed rate of 100 ml / min. Granules were obtained. This was molded under the conditions of uniaxial preliminary pressurization (200 kg / cm ² or less) and isostatic pressing (CIP): ² ton / cm ² . Next, the molded body is placed in a nitrogen atmosphere for 1
After pre-sintering at 550 ° C. and 1 atm for 4 hours, a high-temperature isostatic press (hereinafter referred to as “HIP”) is performed under a nitrogen atmosphere at 1550 ° C. and 1000 atm for 2 hours. The ceramic composite sintered bodies of Examples 1 to 3 and Comparative Examples 1 and 2 were produced.

Measurement of pH of Slurry and Zeta Potential of Each Particle in Slurry The method of measuring pH of slurry and zeta potential of each particle in slurry is described below. The relationship between the pH of the particles and the zeta potential was separately examined for Si ₃ N ₄ and TiN. The Si ₃ N ₄ powder and the above sintering aid were blended (the blending ratio was Si ₃ N ₄ powder: 95 vol%, sintering aid: 5 vol%), and the dispersants shown in the table were further mixed with Si ₃ N ₄ powder. And a total of 1
A slurry composed of Si ₃ N ₄ was prepared by adding the solid content to 0.55% by weight with respect to 00 parts by weight, and
The slurry is diluted to such an extent that the slurry concentration can be measured (there is a single particle in the measurement field and no interference from nearby particles). Thereafter, the pH of the slurry is adjusted using a pH adjuster (nitric acid, aqueous ammonia), and then the zeta potential of the Si ₃ N ₄ powder is measured from the migration speed of the particles when a voltage of 150 V is applied to the slurry. did.
As a measuring device, a zeta potential measuring device LASER ZEE Model 501 (laser / rotating prism type) manufactured by PEN KEM was used. The zeta potential of TiN was also measured by preparing a slurry of TiN and using the same method as described above.

Evaluation of Performance of Ceramic Composite Sintered Examples 1-3 and Comparative Examples 1 produced by the above method
With respect to each of the ceramic composite sintered bodies of No. 2, the performance of the ceramic composite sintered body was evaluated by observing the structure of the sintered body and measuring the strength. In this performance evaluation, the structure was observed by SEM, and the strength was measured according to JIS160.
It was measured by the JIS three-point bending strength method according to 1.
The results of this performance evaluation are shown in Table 1 below. Incidentally, in the section of “structure observation” in Table 1, “◎” indicates that Si ₃ N ₄ component and T
This shows a state where the iN component is uniformly dispersed. Further, “○” indicates a state in which a small amount of agglomerated portions are observed, but the particles are substantially uniformly dispersed. Further, “x” indicates a state in which Si ₃ N ₄ is aggregated at the center and a structure in which TiN is aggregated appears around the entire sintered body. [A] SEM of the cross section of the aggregate of each ceramic particle in each slurry in Example 1, Comparative Example 1 and Comparative Example 2
The image and [B] secondary electron image are shown in FIGS. FIG.
3 [B] In the secondary electron image, the glowing white is the TiN component, and the others are Si ₃ N ₄ and the sintering aid.

[0021]

[Table 1]

(2) Examples 4 to 5 and Comparative Example 3 The specific gravity ratio is the same as in Examples 1 to 3 and Comparative Examples 1 and 2 (1.73), but the particle ratio is small (0.15). A ceramic composite sintered body using the ceramic particles (Si ₃ N ₄ and TiN) was manufactured and its performance was evaluated.

Production of Ceramic Composite Sintered Material As a raw material, particles A (Si ₃ N ₄ powder, density 3.19 g /
cm ³ , average particle size 0.3 μm), particle B (TiN powder,
A density of 5.53 g / cm ³ , an average particle size of 2.0 μm) and a sintering aid (CeO ₂ , MgO, Al ₂ O ₃ , ZrO ₂ ) were used. The particles A, B and the sintering aid were transferred to a ball mill to obtain a raw material powder (particles A: 62 vol.
%, Particles B: 33 vol%, sintering aid: 5 vol% [C
eO ₂ , MgO, Al ₂ O ₃ , ZrO ₂ were each 1.25 vol.
%)]). To 200 g of the raw material powder, 200 ml of water as a dispersion medium was added, and the dispersant A was added thereto in a solid content of 1 part by weight based on 100 parts by weight of the particles A, the particles B and the sintering aid in total. 0.0% and then 50%
Mixing is carried out for a time, and then 8 parts by weight of a binder (microwax emulsion, acrylic resin emulsion) is added to the total of 100 parts by weight of the particles A, B and the sintering aid, followed by ball milling for 1 hour. To prepare a slurry.

The slurry obtained as described above is
After adjusting to each pH shown in Table 2 by using an H adjuster (nitric acid, ammonia water), it was dried by spray drying under the conditions of a drying temperature of 100 to 140 ° C., a disk rotation speed of 5,000 rpm, and a liquid sending amount of 100 ml / min. Granules were obtained. Then, this is uniaxially pre-pressurized (200 kg / cm ² or less), C
Molding was performed under the condition of IP: ² ton / cm ² . Next, the molded body was placed in a nitrogen atmosphere at 1550 ° C. and 1 atm.
After pre-sintering for 4 hours under the conditions described above, HIP was performed for 2 hours at 1550 ° C. and 1000 atm under a nitrogen atmosphere, and each ceramic composite sintering of Examples 4 to 5 and Comparative Example 3 was performed. Body manufactured.

Measurement of pH of Slurry and Zeta Potential of Each Particle in Slurry Measurement of pH of slurry and zeta potential of each particle in slurry was performed in the same manner as in Examples 1-3 and Comparative Examples 1-2. Made by the way. Incidentally, the dispersing agent is Si ₃ N ₄ powder or T
It is added so that the solid content is 1.0% with respect to a total of 100 parts by weight of iN and the sintering aid.

Evaluation of Performance of Ceramic Composite Sintered Products The ceramic composite sintered products of Examples 4 to 5 and Comparative Example 3 produced by the above method were used in Examples 1 to 3 above.
The structure observation and strength measurement of each sintered body were performed in the same manner as in Comparative Examples 1 and 2, and the performance of the ceramic composite sintered body was evaluated. The results of the performance evaluation are shown in Table 2 below. In the section of “Tissue observation” in Table 2, “２”,
“O” and “X” have the same meaning as in Table 1.

[0027]

[Table 2]

(3) Examples 6 and 7 and Comparative Examples 4 and 5 Two types of ceramic particles having substantially the same specific gravity (specific gravity ratio: 1.01), but having a remarkably small particle size ratio (0.028). A ceramic composite sintered body using (Si ₃ N ₄ and SiC) was manufactured and its performance was evaluated.

Production of Ceramic Composite Sintered Material As a raw material, particles A (Si ₃ N ₄ powder, density 3.19 g /
cm ³ , average particle size 1.07 μm), particle B (SiC powder, density 3.21 g / cm ³ average particle size 0.03 μm)
And sintering aid _{(Yb 2 O 3, V 2} O 5, WO 3, Cr 2 O 3)
Was used. The particles A, B and the sintering aid were transferred to a ball mill to obtain a raw material powder (particles A: 65 v
ol%, particle B; 30 vol%, sintering aid; 5 vol%
[Yb ₂ O ₃ = ₂ vol%, V ₂ O ₅ = 1 vol%, WO ₃
= 1 vol%, Cr ₂ O ₃ = 1 vol%]). To 200 g of the raw material powder, 300 ml of water as a dispersion medium was added, and the dispersing agent A was added thereto in a solid content of 1 part by weight based on 100 parts by weight of the total of the particles A, the particles B and the sintering aid. 0%, followed by mixing for 50 hours. Further, a binder (microwax emulsion, acrylic resin emulsion) was added in an amount of 8 parts per 100 parts by weight of the total of the particles A, B and the sintering aid. A slurry was prepared by adding parts by weight and mixing with a ball mill for 1 hour.

The slurry obtained as described above is converted into p
After adjusting to each pH shown in Table 3 using an H adjuster (nitric acid, ammonia water), the mixture was dried by spray drying under the conditions of a drying temperature of 100 to 140 ° C., a disk rotation speed of 5,000 rpm, and a liquid sending amount of 100 ml / min. Granules were obtained. Then, this is uniaxially pre-pressurized (200 kg / cm ² or less), C
Molding was performed under the condition of IP: ² ton / cm ² . Next, the molded body was placed in a nitrogen atmosphere at 1900 ° C. and 1 atm.
After pre-sintering for 4 hours under the conditions described above, HIP was performed for 2 hours at 1800 ° C. and 1000 atm under a nitrogen atmosphere to obtain each ceramic composite of Examples 6 to 7 and Comparative Examples 4 to 5. A sintered body was manufactured.

Measurement of pH of Slurry and Zeta Potential of Each Particle in Slurry Measurement of pH of slurry and zeta potential of each particle in slurry was performed in the same manner as in Examples 1-3 and Comparative Examples 1-2. Made by the way. Incidentally, the dispersing agent is Si ₃ N ₄ powder or S
It is added so that the solid content is 1.0% with respect to a total of 100 parts by weight of iC and the sintering aid.

Evaluation of Performance of Ceramic Composite Sintered Examples 6 to 7 and Comparative Examples 4 to 7 manufactured by the above method
Example 5 for each ceramic composite sintered body of Example 5
-3 and Comparative Examples 1-2, the structure observation and strength measurement of each sintered body were performed, and the performance of the ceramic composite sintered body was evaluated. The results of this performance evaluation are shown in Table 3 below. In the section of “Tissue observation” in Table 2, “２”,
“O” and “X” have the same meaning as in Table 1.

[0033]

[Table 3]

(4) Effects of the Examples Regarding Examples 1 to 3 and Comparative Examples 1 and 2, Examples 1 to 3 in which two types of ceramic particles having a large specific gravity ratio of ceramic particles of 1.73 were used. In comparison with Comparative Examples 1 and 2, from Table 1, Examples 1 and 2 are shown.
In No. ₃ , the absolute value of the zeta potential of the Si ₃ N ₄ powder and the TiN powder was 50 mV or less. as a result,
Even if the specific gravity ratio of the two types of ceramic particles is large,
₃ N ₄ and TiN are uniformly dispersed in the tissue, also, the strength of the sintered body indicates a large value of 1000～1200MPa. In particular, in Example 1 in which the absolute value of the zeta potential of each of the Si ₃ N ₄ powder and the TiN powder was 25 mV or less, in the sintered body structure, Si ₃ N ₄ and TiN
Are uniformly dispersed, and the strength of the sintered body is 1200 MPa.
It is understood that both are the most excellent in the examples as compared with the other examples.

On the other hand, in Comparative Example 1, the absolute value of the zeta potential of the TiN powder was as large as 85 mV,
In Comparative Example 2, the absolute value of the zeta potential of the Si ₃ N ₄ powder was 6
It shows a large value of 5 mV. As a result, in the sintered body structure, Si ₃ N ₄ aggregates at the center, and T 3
A heterogeneous tissue in which iN is aggregated appears throughout,
The strength of the sintered body was 750 MPa (Comparative Example 1) and 800 M
It can be seen that it has decreased to Pa (Comparative Example 2).

Examples 4 to 5 and Comparative Example 3 The specific gravity ratio of the ceramic particles used in the raw materials was as in Examples 1 to 3.
And Examples 4 to 5 using two kinds of ceramic particles having the same particle diameter ratio of 1.73 as those of Comparative Examples 1 and 2, but smaller than those of Examples 1 to 3 and Comparative Examples 1 and 2 having a particle size ratio of 0.15. In comparison with Comparative Example 3, from Table 2, in Examples 4 and 5,
In each case, the absolute value of the zeta potential of the Si ₃ N ₄ powder and the TiN powder is 50 mV or less. As a result, even if the particle size ratio of the two types of ceramic particles is small, Si ₃ N ₄ and TiN are uniformly dispersed in the structure, and the strength of the sintered body is 1100 MPa (Example 4) and 1000 MPa (Example Example 5) shows a large value. In particular, the absolute value of the zeta potential of each of the Si ₃ N ₄ powder and the TiN powder is 25
It can be seen that in Example 4 in which the voltage was not more than mV, both the uniform dispersibility in the structure of the sintered body and the strength of the sintered body were superior to those in Example 5.

On the other hand, in Comparative Example 3, the absolute value of the zeta potential of the Si ₃ N ₄ powder was as large as 70 mV. As a result, in the structure of the sintered body, a non-uniform structure in which Si ₃ N ₄ is agglomerated at the center and TiN is agglomerated therearound appears on the whole, and the strength of the sintered body is 800 MPa.
It can be seen that it has decreased.

Examples 6 to 7 and Comparative Examples 4 to 5 Examples 6 to 7 and Comparative Examples 4 to 5 in which two types of ceramic particles having a remarkably small particle size ratio of 0.028 of the ceramic particles used as the raw material were used. In comparison with Table 5, from Table 3, in Examples 6 and 7, both of Si ₃ N ₄ powder and Si
The absolute value of the zeta potential of the C powder is 50 mV or less. As a result, despite the extremely small particle size ratio,
In the structure of the sintered body, the Si ₃ N ₄ powder and the SiC powder are dispersed uniformly, and the strength of the sintered body shows large values of 1000 (Example 6) MPa and 900 (Example 7) MPa. . In particular, Example 6 in which the absolute value of the zeta potential of both the Si ₃ N ₄ powder and the SiC powder is 25 mV
It can be seen from the results that both the uniform dispersibility of the structure and the strength of the sintered body are superior to those of Example 7.

On the other hand, in Comparative Example 4, the absolute value of the zeta potential of the Si ₃ N ₄ powder was 55 mV.
Then, the absolute value of the zeta potential of the Si ₃ N ₄ powder is 70 mV,
The absolute value of the zeta potential of SiC is 55 mV.
As a result, in the structure of the sintered body, a non-uniform structure in which Si ₃ N ₄ is agglomerated at the center and TiN is agglomerated therearound appears on the whole, and the strength of the sintered body is 700 MPa (Comparative Example 4). ) And 650 MPa (Comparative Example 5).

It should be noted that the present invention is not limited to the specific embodiments described above, but can be variously modified within the scope of the present invention according to the purpose and application. For example, as a raw material of a ceramic composite sintered body, Si ₃ N ₄
Not limited to powder and TiN powder, specific gravity difference,
It is effective when compounding ceramic particles having different particle diameters and spray drying.

[0041]

According to the method for producing a ceramic composite sintered body of the present invention, contrary to the prior art, the absolute value of the zeta potential of each ceramic particle is reduced immediately before the drying step by spray drying. By uniformly aggregating the respective ceramic particles in advance in the slurry, it is possible to uniformly combine two or more types of ceramic particles having different specific gravities and / or particle sizes. As a result, non-uniform aggregated portions are eliminated in the structure of the sintered body, and the strength of the ceramic composite sintered body can be improved.

[Brief description of the drawings]

FIG. 1 is an [A] SEM image and [B] a secondary electron image of a cross section of an aggregate of each ceramic particle in a slurry in Example 1.

FIG. 2 is an [A] SEM image and [B] a secondary electron image of an aggregate cross section of each ceramic particle in a slurry in Comparative Example 1.

FIG. 3 is an [A] SEM image and [B] a secondary electron image of a cross section of an aggregate of each ceramic particle in a slurry in Comparative Example 2.

FIG. 4 is a conceptual diagram of a state of each ceramic particle in a slurry depending on a level of a zeta potential and an aggregate obtained by spray drying from the slurry.

FIG. 5 is a schematic view showing a method of obtaining a dispersibility index of the other added ceramic particles.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuhiro Urashima 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Inside Japan Special Ceramics Co., Ltd. Incorporated F term (reference) 4G001 BA03 BA06 BA08 BA11 BA12 BA14 BA22 BA24 BA32 BA37 BA38 BA48 BB03 BB06 BB08 BB11 BB12 BB14 BB22 BB24 BB32 BB37 BB38 BC01 BC11 BC13 BC21 BC43 BD14 BD18

Claims (3)

[Claims] 1. A slurry containing two or more types of ceramic particles having different specific gravities and / or particle sizes is dried, and then molded using the dried ceramic particles.
In a method of manufacturing a ceramic composite sintered body to be sintered,
A method for manufacturing a ceramic composite sintered body, comprising: aggregating the ceramic particles uniformly in advance in a slurry; and then drying the particles by spray drying. 2. The method for producing a ceramic composite sintered body according to claim 1, wherein the absolute value of each zeta potential of the two or more types of ceramic particles in the slurry is adjusted to 50 mV or less. 3. The group comprising at least two types of ceramic particles comprising Si ₃ N ₄ , SiC, Al ₂ O ₃ , ZrO ₂ , TiN, and carbides, nitrides or silicides of IVa, Va, VIa group transition metals. The method for producing a ceramic composite sintered body according to claim 1 or 2, wherein the ceramic composite sintered body is at least two kinds selected from the group consisting of: