JP2006001765A - Forming process of ceramic formed body with three-dimensional network structure and ceramic formed body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for forming a ceramic formed body capable of obtaining the ceramic formed body enhanced in uniformity of cell sizes and their distribution states, and to provide the ceramic formed body. <P>SOLUTION: This process is for forming the ceramic formed body provided with a three-dimensional network structure having a plurality of cells and a plurality of communicating holes, and comprises a first step of preparing a coated particles-ceramic slurry arranged body where a plurality of organic particles, the surfaces of which are coated with SiC particles, are arranged in a predetermined manner, and ceramic slurry containing a gelling agent fills the space between the coated particles, a second step of gelling the gelling agent, a third step of drying the coated particles-ceramic slurry arranged body after gelling, and a fourth step of forming a plurality of cells and a plurality of communicating holes by heating the coated particles-ceramic slurry arranged body and gasifying the organic particles. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a ceramic molded body having a three-dimensional network structure and a ceramic molded body.

Conventionally, methods for producing a ceramic molded body (also called a preform) having a three-dimensional network structure include impregnation of ceramic slurry into foam plastic, dry operation of ceramic slurry, thermal decomposition of foam plastic, and ceramic particle A method of sequentially performing sintering is known (see Patent Document 1).
JP-A-5-50182 (0016-0027)

  However, since the conventional ceramic molded body has non-uniform cell size and cell distribution, when used as a reinforcing material for a metal matrix composite member, the strength, sliding characteristics, etc. of the metal matrix composite member There has been a problem that physical properties such as mechanical properties, cooling performance, and coefficient of thermal expansion may be partially different.

  Accordingly, the present invention provides a method for producing a ceramic molded body capable of obtaining a ceramic molded body with improved cell size and uniformity of the distribution state, and a ceramic molded body, in order to solve the above problems. This is the issue.

  In order to solve the above-mentioned problems, the inventors of the present application have made extensive studies and, as a result, coated particles formed by coating spherical synthetic resin particles with a plurality of ceramic particles are arranged in a mold, and a ceramic slurry is filled between the coated particles. After that, the coated particles are pyrolyzed to form a plurality of cells and communication holes, thereby making it possible to produce a ceramic molded body in which cells of the same size are uniformly distributed. “Ceramic molding with a three-dimensional network structure” The invention which concerns on "the manufacturing method of a body" was discovered (unpublished, Japanese Patent Application No. 2003-390666).

  In view of such knowledge, as a means for solving the above-mentioned problem, the invention according to claim 1 is a three-dimensional network having a plurality of cells and a plurality of communication holes existing in a partition wall separating adjacent cells. A method for producing a ceramic molded body having a structure, wherein a plurality of coated particles obtained by coating the surfaces of a plurality of first particles gasified by heating with a plurality of ceramic particles are uniformly arranged, and the arrangement A first step of producing a coated particle-ceramic slurry array in which a ceramic slurry containing a gelling agent is filled between the coated particles, a second step of gelling the gelling agent, and after the gelation A third step of drying the coated particle-ceramic slurry array, and heating the coated particle-ceramic slurry array to gasify the first particles, thereby allowing the plurality of cells and the plurality of cells to be gasified. A method of manufacturing the ceramic formed body having a three-dimensional network structure, characterized in that it comprises a fourth step of forming a through hole, a.

According to such a method of manufacturing a ceramic molded body, the ceramic slurry loses fluidity by gelling the gelling agent in the second step. Therefore, for example, even when coated particles having different specific gravities are used, it is possible to prevent the coated particles from being segregated and segregated while the coated particle-ceramic slurry array is dried (third step). Moreover, since the gelatinized coated particle-ceramic slurry array has appropriate flexibility, it is difficult for cracks and warpage to occur.
And the ceramic molded body with which the cell was distributed uniformly can be obtained by gasifying the 1st particle (4th process). That is, the strength is not partially different, and a high-strength ceramic molded body can be obtained.

  Here, the uniform arrangement of the coated particles means, for example, a case where the coated particles are arranged in a close-packed form, or a case where other large and small coated particles are randomly arranged, as will be described in the embodiments described later. means.

  In the invention according to claim 2, the ratio of the average radius R1 of the coated particles to the average radius R2 of the particles forming the ceramic slurry is R1: R2 = 30 to 70: 1, 2. The ratio of the volume V1 to the volume V2 of the ceramic slurry is set to V1: V2 = 6: 4 to 9: 1 to reduce the porosity of the coated particle-ceramic slurry array. A method for producing a ceramic molded body having the three-dimensional network structure described in 1.

According to such a method for producing a ceramic molded body, a plurality of coated particles are arranged in a close-packed form such as 6-coordinate, 8-coordinate, and 12-coordinate, and a ceramic slurry is filled between the arranged coated particles. Thus, the porosity (porosity) of the coated particle-ceramic slurry array can be reduced.
That is, it is possible to obtain a ceramic molded body in which the cells formed by gasifying the first particles are uniformly distributed at a high density and the partition walls separating the cells are more dense.

  According to a third aspect of the present invention, the ceramic slurry includes SiC as a main component, and the first particles include at least one selected from the group consisting of PMMA, PS, PE, inorganic carbon, and silicon-based inorganic compound particles. 3. The method for producing a ceramic molded body having a three-dimensional network structure according to claim 1, wherein the ceramic particles contain SiC as a main component, and the ceramic particles contain SiC as a main component.

According to such a method for producing a ceramic molded body, a ceramic molded body mainly composed of SiC can be obtained. In addition, when the first particles are mainly composed of polymethyl methacrylate (PMMA), PMMA gasifies in a narrow temperature range (280 to 390 ° C.). Therefore, in the fourth step, for example, a temperature increase rate is set to a predetermined value. Thus, the size of the cell and the communication hole can be easily controlled.
Furthermore, in the first step, after mixing a plurality of coated particles and the ceramic slurry at a pH of 8.0 to 10.0, when a coated particle-ceramic slurry array is prepared, the pH is adjusted to 8.0 to 10.0. By adjusting, the zeta potential of the SiC particles in the ceramic slurry containing SiC as the main component, the first particles containing PMMA as the main component, and the covering particles becomes largely negative. Therefore, they are preferably dispersed and the coated particles are easily arranged in a close packed manner. Therefore, a ceramic molded body in which the cells are more densely and uniformly distributed can be obtained.

  According to a fourth aspect of the present invention, the ceramic slurry in the first step includes a first substance that is a raw material of the ceramic molded body, and the plurality of the plurality of the plurality of the plurality of the plurality of the plurality of the plurality of the plurality of ceramics without reacting the first substance. The plurality of cells and the plurality of communication holes, and after the fourth step, the plurality of cells and the plurality of communication holes are filled with a metal that reacts with the first substance to generate a ceramic, The method further comprises: a fifth step of sintering while producing a ceramic by reacting a part with the first substance; and a sixth step of removing the unreacted metal. It is a manufacturing method of the ceramic molded body provided with the three-dimensional network structure of any one of Claim 3.

  According to such a method of manufacturing a ceramic molded body, in the fifth step, the first substance and the metal are reacted, and the adjacent cells are separated by sintering (reactive sintering) while producing the ceramic. The partition wall becomes dense. Therefore, the ceramic molded body is difficult to shrink, and secondary processing such as near-net adjustment is not necessary.

  Here, the ceramic formed by the reaction between the first substance and the metal, the ceramic in the ceramic slurry, and the ceramic particles covering the first particles are included in the manufactured ceramic molded body. It selects suitably so that the purity of may increase. For example, when manufacturing a ceramic molded body mainly composed of SiC, the first substance is carbon and the metal is Si.

  According to a fifth aspect of the present invention, there is provided a three-dimensional network structure manufactured by the method for manufacturing a ceramic molded body having the three-dimensional network structure according to any one of the first to fourth aspects. A ceramic molded body provided.

  According to such a ceramic molded body, since the cell size and the uniformity of the distribution state are high and the strength is high, for example, it can be suitably used as a reinforcing material for a metal matrix composite member.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the ceramic molded body which can obtain the ceramic molded body which improved the magnitude | size of the cell and its distribution state, and a ceramic molded body can be provided.
That is, according to the first aspect of the present invention, a ceramic molded body in which cells are uniformly distributed can be obtained.
According to the second aspect of the invention, the cells can be distributed more uniformly.
According to the third aspect of the invention, it is possible to obtain a ceramic molded body in which the cells are more uniformly distributed and the main component is SiC.
According to the invention which concerns on Claim 4, the high intensity | strength ceramic molded object which is hard to shrink | contract can be obtained.
According to the invention which concerns on Claim 5, it can be used conveniently as a reinforcing material of a metal matrix composite member, for example.

  Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

≪Ceramic molded body≫
First, the ceramic molded body manufactured by the manufacturing method of the ceramic molded body provided with the three-dimensional network structure concerning this invention is demonstrated with reference to FIG. 1, FIG. In the drawings to be referred to, FIG. 1 is a perspective view of a ceramic molded body. FIG. 2 is an enlarged cross-sectional view of a main part showing an enlarged cross section of the ceramic molded body shown in FIG.

  As shown in FIG. 1, in this embodiment, the ceramic molded body 1 has a rectangular parallelepiped shape and has a network structure in a three-dimensional direction (see FIG. 2). More specifically, the ceramic molded body 1 exists in a plurality of cells C, which are spherical spaces arranged in a close-packed form in a three-dimensional direction, and partition walls 1a separating adjacent cells C, and the adjacent cells C A plurality of communication holes H (also referred to as windows).

As will be described later, the median M _d of the inner diameter of the communication hole H is M _d ≧ 1 μm so that the metal M is suitably filled when the ceramic molded body 1 is filled with a predetermined metal M (see FIG. 4). Is set to Also, the median M _d of the communication hole H, the ratio of the median M _D of the inner diameter of the cell C, M _d / M _D is set to _{0.1 <M d / M D <} 0.5, ceramic The strength of the molded body 1 can be ensured. This is because in the range of M _d / M _D ≦ 0.1, stress concentrates on the edge of the communication hole H, and the strength of the ceramic molded body 1 decreases. Further, in the range of M _d / M _D ≧ 0.5, the amount of the partition wall 1a is reduced, so that the strength and rigidity of the ceramic molded body 1 are lowered.
Note that the median M _D of the inner diameter of the cell C and the median M _d of the inner diameter of the communication hole H are obtained by, for example, three-dimensional CT analysis, a mercury intrusion method, or the like.

  Examples of the material forming the ceramic molded body 1 include various engineering ceramics such as SiC and TiC. In the present embodiment, the case where the ceramic molded body 1 includes SiC as a main component will be described.

≪Metal matrix composite material≫
Next, the metal matrix composite member MC in which the ceramic molded body 1 is filled with a predetermined metal M will be described with reference to FIGS. 3 and 4. In the drawings to be referred to, FIG. 3 is a perspective view of a metal matrix composite member in which the ceramic molded body shown in FIG. 1 is filled with metal. FIG. 4 is an enlarged cross-sectional view of a main part showing an enlarged cross section of the metal matrix composite member shown in FIG. The metal matrix composite member MC may be referred to as a metal matrix composite material (MMC: Metal Matrix Composites).

  As shown in FIG. 3, the metal matrix composite member MC is a member in which the cell C and the communication hole H (see FIG. 2) of the ceramic molded body 1 are filled with a predetermined metal M, and in this embodiment, a rectangular parallelepiped. It has a shape. As shown in FIG. 4, the filled metal M spreads in a three-dimensional direction and forms a matrix (matrix, mold) of the metal matrix composite member MC. The metal M is also referred to as a metal matrix. Examples of the metal M include Al, Al alloy, Si, Si alloy, Cu, Cu alloy, Mg, and Mg alloy.

  Since such a metal matrix composite member MC has a high mechanical strength and a low coefficient of thermal expansion, its application range is very wide. For example, in the field of automobiles, the cylinder block can be suitably applied to a cylinder bore (cylinder sleeve), a cylinder head gasket surface, a bolt fastening seat surface, a journal bearing and the like. Further, the cylinder head can be suitably applied to a cylinder head gasket surface, a bolt fastening seat surface, a cam journal bearing, a valve seat press-fitting portion, a valve guide press-fitting portion, and the like. In addition, it can apply suitably for a bolt fastening seat surface, a mating surface, etc. about the case and cover of an engine.

≪Method for manufacturing ceramic molded body≫
Then, the manufacturing method of the ceramic molded body 1 provided with the three-dimensional network structure based on this invention is demonstrated with reference mainly to FIG. FIG. 5 is a process diagram of a method for producing a ceramic molded body.

The method for producing the ceramic molded body 1 is to produce a ceramic slurry 16 (see FIG. 8) containing carbon particles 15 (hereinafter referred to as C particles, see FIG. 8) and a gelling agent mainly composed of carbon (first substance). 1A process, using a predetermined mold, coated particles 13 (see FIG. 6) are arranged in a close-packed form (see FIG. 8), and a ceramic slurry 16 is filled between the coated particles 13-coated particles-ceramics A first step B for producing the array 17 of particles, a second step of gelling the coated particle-ceramic array 17, a third step of drying the coated particle-ceramic array 17, and an organic system A fourth step (see FIG. 9) in which the particles 11 (first particles) are gasified to form the cells C and the communication holes H, and the metal Si 19 is filled in the cells C and the communication holes H (see FIG. 11). One It has and the fifth step of sintering (reactive sintering) while reacting C particles 15, and a sixth step of removing the metal Si19 unreacted.
In this embodiment, the first substance in the claims is carbon, the ceramic particles constituting the coated particles 13 are SiC particles 12 (see FIG. 6), the metal is metal Si19 (see FIG. 11), and carbon and metal A case will be described in which SiC is produced by reacting with Si 19 to produce ceramic molded body 1 containing SiC as a main component.
Hereinafter, each step will be described in detail.

<Step 1A: Production of ceramic slurry>
SiC powder that is an aggregate of SiC particles 14 (see FIG. 8), carbon powder (C powder) that is an aggregate of C particles 15 (see FIG. 8), a pH adjusting agent, a peptizer, Then, distilled water as a solvent is mixed in a predetermined manner by a mixer such as a ball mill (S101).

The SiC powder is a ceramic powder mainly composed of SiC. For example, GC-2000F (α-SiC, average particle diameter 5 μm) manufactured by Yakushima Electric Works, Ltd. can be used.
As the C powder, for example, carbon black (CB: average particle diameter 0.07 μm) manufactured by Mitsubishi Chemical Corporation can be used.
As the pH adjusting agent, NaOH, NH ₃ or the like can be used, and as the peptizer, acrylic acid oligomer, monoethylamine or the like can be used. Specifically, as such a pH adjuster, for example, SN-7347C manufactured by San Nopco can be used as a quaternary ammonium salt.

  The mixing ratio of SiC powder, C powder, pH adjuster and distilled water is determined as appropriate. Of these, the SiC powder and the C powder preferably have a composition ratio of C / SiC = 0.1 to 0.5 and a mass ratio of C / SiC = 0.03 to 0.15.

  Then, a mixture of SiC powder, C powder, pH adjusting agent and distilled water (S101), a gelling agent is further added and mixed, and then vacuum degassing is performed (S102), thereby carbon is added. The ceramic slurry 16 contained is obtained. Since the ceramic slurry 16 obtained in this way contains SiC and C as main components, it may be referred to as “SiC + C slurry”.

  As the gelling agent, for example, β-1, 3 glucan, agar, gelatin, hydraulic urethane, alumina sol, silica sol and the like can be appropriately selected and used. Specifically, curdlan or the like can be used as β-1, 3 glucan. In addition, since the main component of a gelatinizer remains in the manufactured ceramic molded object 1, it is made to respond | correspond to the material of the ceramic molded object 1 manufactured. In the present embodiment, agar or the like is selected as the gelling agent in order to increase the purity of the ceramic molded body 1 mainly composed of SiC to be manufactured.

  The viscosity η of the ceramic slurry 16 is suitably 0.05 Pa · s ≦ η ≦ 5 Pa · s. When η <0.05 Pa · s, the amount of water becomes excessive, and the amount of deformation / shrinkage of the ceramic molded body 1 after drying and firing becomes large. On the other hand, when η> 5 Pa · s, the viscosity of the ceramic slurry 16 is too high, and will be described later. This is because the ceramic slurry 16 is hardly filled between the coated particles 13 in the second step (see FIG. 8). In addition, by setting the viscosity η of the ceramic slurry 16 in such a range, the inner diameter of the communication hole H can be controlled in the fourth step described later.

<Step 1B: Production of coated particle-ceramic slurry array>
Next, the 1B step will be described. First, the production of the coated particles 13 (see FIG. 6) used in the 1B step will be described.

[Preparation of coated particles]
As shown in FIG. 6, an aggregate of synthetic resin organic particles 11 (first particles) that is gasified by heating, SiC powder that is an aggregate of SiC particles 12 (ceramic particles), and organic particles 11 and a binder for adhering SiC particles 12 are mixed by a mixer (coating machine) with a predetermined composition, and a plurality of SiC particles 12 densely coat the surface of organic particles 11. A plurality of 13 are produced (S103).

The material for forming the organic particles 11 is not particularly limited as long as it can be gasified by heating, that is, gas can be generated. Specifically, at least one selected from the group consisting of polymethyl methacrylate (PMMA), polystyrene (PS), inorganic carbon (for example, carbon powder), and silicon-based inorganic compound particles (for example, dimethylpolysiloxane) is selected. Can be used. In the present embodiment, the case where the organic particles 11 are made of PMMA will be described. As the organic particles 11 made of PMMA, for example, MR-90G manufactured by Soken Chemical Co., Ltd. can be used.
Moreover, since the organic particle 11 is gasified and forms a cell C as described later, the size of the organic particle 11 is preferably set according to the inner diameter of the cell C. For example, the median D _M of the diameter of the organic particles 11 (hereinafter, referred to as a median diameter D _M) is set to 10 [mu] m ≦ D _M ≦ 1000 .mu.m.
Further, the particle size distribution of the aggregate of the organic particles 11 is preferably narrow, and when the particle size distribution is narrow, the coated particles 13 are easily arranged in a close-packed form.

  Since the SiC particles 12 are mainly configured with the ceramic molded body 1 after manufacturing, the SiC particles 12 correspond to the material of the ceramic molded body 1 to be manufactured. That is, in this embodiment, in order to manufacture the ceramic molded body 1 having SiC as a main component, SiC particles 12 having SiC as a main component are selected as ceramic particles.

The size of the SiC particles 12 is set to, for example, 1/100 to 1/10 relative to the size of the organic particles 11. That is, when the median diameter D _M of the organic particles 11 is in the above range, the median d _M of the SiC particles 12 (hereinafter referred to as the median diameter d _M ) is 0.1 μm ≦ d _M ≦ 100 μm. Is preferred. The volume ratio of the ceramic molded body 1 in the metal matrix composite member MC is controlled by the size and the coating thickness of the SiC particles 12 that coat the organic particles 11.

  The blending mass ratio of the aggregate of organic particles 11 and the aggregate of SiC particles 12 (SiC powder) is such that the mass of 11 aggregates of organic particles is W1, and the mass of the aggregate of SiC particles 12 is W2. Is preferably within the range of 0.1 ≦ W1 / W2 ≦ 10. When W1 / W2> 10, the amount of SiC particles 12 is insufficient with respect to the amount of organic particles 11, so that the entire surface of organic particles 11 cannot be covered with SiC particles 12, while W1 / W2 <0. This is because the amount of the SiC particles 12 is excessive with respect to the amount of the organic particles 11 and the surface of the organic particles 11 is not covered and the remaining SiC particles 12 increase.

  As the binder, for example, polyvinyl alcohol (PVA-217S) manufactured by Kuraray Co., Ltd. can be used. Moreover, in order to enhance the coating effect of the SiC particles 12 on the organic particles 11 made of PMMA, surface modification may be performed to control the angle of repose of the SiC particles 12.

  As the mixer, for example, AM-15F manufactured by Hosokawa Micron (see Japanese Patent Application Laid-Open No. 2003-160330) can be used. When this mixer is used, the rotational speed RS is set to 500 rpm ≦ RS ≦ 2500 rpm, the processing time t is set to 0.25 h ≦ t ≦ 1.0 h, and the inner piece distance is adjusted to 1 mm.

  In addition, the ratio between the average radius R1 of the coated particles 13 thus prepared and the average radius R2 of the particles forming the ceramic slurry 16 prepared in the first step is set to R1: R2 = 30 to 70: 1. .

[Production of coated particle-ceramic slurry array]
And the aggregate | assembly of the covering particle | grains 13 and the ceramic slurry 16 produced at the 1st process are mixed by predetermined mixing with a predetermined container, and a covering particle-ceramic slurry mixture is produced (S104).

Here, the predetermined composition is set so that the ratio between the volume V1 of the aggregate of the coated particles 13 and the volume V2 of the ceramic slurry 16 is V1: V2 = 6: 4 to 9: 1.
By setting the composition in this way and setting the ratio of the average radius R1 of the coated particles 13 and the average radius R2 of the ceramic slurry 16 to R1: R2 = 30 to 70: 1 as described above, In the production of the next coated particle-ceramic slurry array 17, the coated particles 13 are uniformly arranged in a close-packed form such as six-coordinate, eight-coordinate, and twelve-coordinate, and between the arranged coated particles 13. It is possible to reduce the porosity (porosity) of the coated particle-ceramic slurry array 17 by suitably filling the ceramic slurry 16 (see Ceramic Materials for Furnace, Gihodo Publishing, p. 46). As a result, it is possible to obtain the ceramic molded body 1 in which the cells C (see FIG. 2) are uniformly distributed with high density and the partition walls 1a (FIG. 1) are dense. Specific examples in the case of R1: R2 = 50: 1 are shown in Table 1 below.
In addition, FIG. 8 etc. are the figures which drew the case where the covering particle | grains 13 were ideally arranged in the 12-coordinate close-packing form.

  In addition, the pH of the coated particle-ceramic slurry mixture is adjusted to pH 8 to 10 with a pH adjuster or the like in the first step. Accordingly, as shown in FIG. 7, the coated particles 13 (including organic particles 11 and SiC particles 12 made of PMMA) constituting the coated particle-ceramic slurry mixture, the SiC particles 14 and the C particles 15 constituting the ceramic slurry 16 are included. The zeta potentials of each are greatly negative. Therefore, the SiC particles 14 and the C particles 15 constituting the coated particles 13 and the ceramic slurry 16 repel each other, and as a result, are suitably dispersed (S104).

  Then, this coated particle-ceramic slurry mixture is poured into a mold having a predetermined shape, exposed to a reduced pressure, and subjected to appropriate vibration, whereby a plurality of coated particles 13 are packed in the close-packed form as shown in FIG. A coated particle-ceramic slurry array 17 is prepared by filling the ceramic slurry 16 in the gaps between the coated particles 13 arranged in (S105).

  Here, as a mold, for example, a mold formed of a porous material such as gypsum, a mold made of various metals or PTFE, or the like is used, and a vacuum filtration system or a system in which the inside of the mold is pressurized from the opening side of the mold. You may employ | adopt suitably.

<Second step: gelation>
Then, the gelling agent in the coated particle-ceramic slurry array 17 (see FIG. 8) is gelled to lose the fluidity of the ceramic slurry 16 (S106). As a method for gelation, for example, a method of changing the temperature or adding a predetermined polymerization initiator is employed. More specifically, for example, when the curdlan is used as a gelling agent, it can be gelled by changing the temperature from room temperature RT → 60 ° C. → room temperature RT.

<Third step: drying / release>
Subsequently, the coated particle-ceramic slurry array 17 after gelation is dried at a predetermined drying temperature and a predetermined drying time using an appropriate dryer to produce a sintered compact (S107). The drying temperature and drying time may be appropriately determined. For example, a method of drying at 20 ° C. for 5 hours and further drying at 90 ° C. for 1 hour is employed.

In this drying, since the ceramic slurry 16 has lost fluidity due to the gelation, for example, even if there is a difference in specific gravity of the coated particles 13, the coated particles 13 do not shift during drying, and the cells C are uniform. A distributed ceramic molded body 1 can be obtained.
Further, due to the gelation, the coated particle-ceramic slurry array 17 takes in an appropriate amount of moisture and has appropriate flexibility, so that cracking and warping are less likely to occur during drying.
After a predetermined time has elapsed, the sintered compact is released from the mold (S107). Even in this mold release, since it has appropriate flexibility and shape retention, it is difficult to break.

<Step 4: Gasification of organic particles>
Next, this sintered compact is placed in a sintering furnace in an inert atmosphere, depressurized to a predetermined furnace pressure, and heated to a temperature at which the organic particles 11 are thermally decomposed at a predetermined heating rate. The temperature is raised and the temperature is maintained for a predetermined time (S108). Then, the organic particles 11 are pyrolyzed and gasified, that is, gas is generated, and as shown in FIG. 9, a plurality of spherical cells C are formed, and the pressure at which the generated gas is released, A communication hole H for communicating adjacent cells C is formed.

In the formation of the cell C and the communication hole H, the ceramic slurry 16 is gelled as described above. Therefore, the excessively gasification pressure due to the gasification of the organic particles 11 causes the destruction of the ceramic molded body 1 or the cell C. Deformation can be prevented.
Further, as shown in FIG. 10, for example, the Al ₂ O ₃ gel exhibits a gradual mass change with respect to the temperature with respect to the organic particles 11 made of PMMA, and even after the gasification of PMMA, the Al ₂ O ₃ gel A part remains, and the remaining Al ₂ O ₃ gel prevents the ceramic molded body 1 from being broken and the cell C shape from being deformed. FIG. 10 is a TG (Thermo Gravimetry) curve of PMMA and Al ₂ O ₃ gel in air.

The inert atmosphere in the furnace is formed by an inert gas such as nitrogen (N ₂ ) or argon (Ar). Thus, by making the inside of the furnace an inert atmosphere, it is possible to prevent the C particles 15 in the ceramic slurry 16 filled between the coated particles 13 from reacting with oxygen.

The furnace pressure P, the heating rate Hr, the heating temperature T, and the heating time t (after heating, the maintenance time at the heating temperature T) depend on the material of the organic particles 11, and in particular the heating rate Hr is the communication hole H Is closely related to the size of In this embodiment, the furnace pressure P is 1 Pa ≦ P ≦ 1 MPa, the heating rate Hr is 5 ° C./h≦Hr≦120° C./h, the heating temperature T is 300 ° C. ≦ T ≦ 600 ° C., and the heating time t Are set to 0.5 ≦ t ≦ 10 h, respectively.
This is because when P <1 Pa, the pressure difference from the gas generated by the thermal decomposition of the organic particles 11 becomes large, and the communication hole H becomes too large. On the other hand, when P> 1 MPa, the pressure difference with the gas becomes small, and the communication hole H is not preferably formed. Further, when Hr <5 ° C./h, the generated gas pressure becomes too low, whereas when Hr> 120 ° C./h, the generated gas pressure becomes too high. Furthermore, when T <300 ° C., the organic particles 11 may not be completely gasified and may remain. On the other hand, when T> 600 ° C., the surface of the sintered compact (coated particles-ceramic slurry array 17) is inactive. This is because it is affected by the atmosphere. Furthermore, when t <0.5h, the organic particles 11 may remain, whereas when t> 10h, the above-described influence is exerted.

Thus, the furnace pressure P, Atsushi Nobori rate Hr, the heating temperature T and the heating time t is set to a predetermined, the median diameter D _M of the organic particles 11 in the above-specified range, the inner diameter of the communication hole H The ratio of the median M _d to the median M _D of the inner diameter of the cell C, M _d / M _D can be 0.1 <M _d / M _D <0.5.

  More specifically, in the case of organic particles 11 made of PMMA, the furnace pressure is set to 0.1 MPa, the temperature is increased to 500 ° C. at a temperature increase rate of 10 ° C./h, and heat treatment is performed at 500 ° C. for 3 hours. Thus, the organic particles 11 can be gasified well, and the cells C and the communication holes H can be suitably formed.

<Fifth step: reactive sintering>
Then, using an appropriate sintering furnace, as shown in FIG. 11, the cells C and the communication holes H of the sintered compact are filled with metal Si19 and the furnace pressure is reduced to a predetermined value (for example, 1 Pa). The SiC particles 14 are sintered (reactively sintered) while reacting a part of the metal Si 19 and the C particles 15 (carbon) at a predetermined sintering temperature (for example, 1500 ° C.) and a predetermined sintering time (2 h). (S109).

  The method of filling the cell C and the communication hole H with the metal Si 19 is not particularly limited in the present invention. For example, the sintered compact in which the cell C and the communication hole H are formed in the molten liquid metal Si 19. Alternatively, after filling the cell C and the communication hole H with the powder metal Si19, the powder metal Si19 may be melted at a predetermined temperature. The amount of metal Si 19 to be filled is preferably Si / C> 7/3 as a composition ratio with respect to the C particles 15.

  When the metal Si 19 is filled and heated in this manner, a part of the molten metal Si 19 penetrates into the gaps between the SiC particles 14 surrounding the cell C and reacts with the C particles 15 to generate SiC (ceramic). Here, as described above, in order to reduce the pressure in the furnace to 1 Pa or less, the metal Si 19 suitably permeates the gap. Further, the generated SiC is integrated with the SiC particles 12 surrounding and sintering the cell C and the SiC particles 14 in the ceramic slurry 16. As a result, the partition walls 1a separating the cells C of the ceramic molded body 1 to be manufactured are dense, and the ceramic molded body 1 is less likely to shrink during reaction sintering, and cracks and the like do not occur.

  In addition, since reaction sintering is performed under reduced pressure in this way, it can be sintered (fired) at a temperature lower by 300 to 500 ° C. than general sintering under normal pressure.

<Sixth step: removal of unreacted metal Si>
Thereafter, under a predetermined condition (for example, 1600 ° C., 133 Pa or less, 2 h), the unreacted metal Si 19 remaining in the cell C and the communication hole H is melted and removed (S110), thereby having a three-dimensional network structure. A ceramic molded body 1 can be obtained (see FIG. 2). Further, after the treatment in S110, the unreacted metal Si19 can be completely removed by performing a hydrofluoric acid treatment with hydrofluoric acid (HF).

According to such a method of manufacturing a ceramic molded body, C particles 15 (first substance) are present between the adjacent coated particles 13 in the second B step (process for producing the coated particle-ceramic slurry array 17). In the fifth step (reaction sintering step), the SiC particles 14 and the SiC particles 14 in the ceramic slurry 16 are produced by reaction sintering while reacting the C particles 15 with the metal Si 19 to produce SiC. And the SiC particle 12 which comprises the covering particle | grains 13 is integrated, As a result, the partition 1a which these form becomes dense.
Therefore, the ceramic molded body 1 is less likely to shrink during sintering, the near net adjustment of the ceramic molded body 1 is possible, and secondary processing is not necessary. Further, such as Al ₂ O ₃ and B ₄ C, because it does not use a sintering aid comprising an impurity of the ceramic molded body 1, it is possible to increase the purity of the ceramic molded body 1.

  As mentioned above, although an example was described about suitable embodiment of this invention, this invention is not limited to the said embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably.

Instead of the coated particles 13 (see FIG. 6) in the above-described embodiment, as shown in FIG. 12, coated particles 13A in which a part of the SiC particles 12 are replaced with organic small particles 21 that can be gasified by heating are used. May be used. According to such coated particles 13A, by the gasification of organic-based fine particles 21, or to promote the formation of the communication hole H, it is possible to control the median M _d of the inner diameter of the communication hole H.

In the above-described embodiment, the gelling agent is added before the vacuum degassing (S102) shown in FIG. 5, but the timing of adding the gelling agent is not limited to this, and the ceramic slurry 16 and the coated particles 13 It may be added in the mixing step (S104).
The same applies to the pH adjuster, and it may be added in the mixing step (S104).

  In the above-described embodiment, in the step 1B, the ceramic slurry 16 and the aggregate of the coated particles 13 are mixed and then poured into a predetermined mold. However, in the gap between the coated particles 13 arranged in the close-packed form. As long as the coated particle-ceramic slurry array 17 formed by filling the ceramic slurry 16 can be produced, the present invention is not limited to this procedure. For example, after the coated particles 13 are arranged in a predetermined mold, the ceramic slurry 16 may be filled by a pressurizing method or the like, and it goes without saying that such an order belongs to the technical scope of the present invention.

  In the fourth step according to the above-described embodiment, the inside of the sintering furnace is under reduced pressure and under an inert atmosphere, but it may be at least one of under reduced pressure and under an inert atmosphere.

  In the above-described embodiment, the case where the ceramic molded body 1 containing SiC as a main component has been described. However, the application of the present invention is not limited to the production of a ceramic molded body made of SiC. You may apply, when manufacturing the ceramic molded body which has other carbide ceramics (engineering ceramic) as a main component.

  In the above-described embodiment, as shown in FIG. 1, the ceramic molded body having a rectangular parallelepiped shape has been described. However, the shape of the ceramic molded body is not limited to this, and is complicated depending on the shape of the metal matrix composite member MC. May be.

  In the above-described embodiment, the case where the coated particles 13 are arranged in the close-packed form has been described. However, the arrangement method of the coated particles is not limited to this, and may be arranged at random if uniform.

It is a perspective view which shows an example of the ceramic molded body which concerns on this embodiment. It is a principal part expanded sectional view of the ceramic molded body shown in FIG. It is a perspective view which shows an example of the metal matrix composite member formed by filling the ceramic forming body shown in FIG. 1 with metal. It is a principal part expanded sectional view of the metal matrix composite member shown in FIG. It is process drawing of the manufacturing method of the ceramic molded body which concerns on this embodiment. It is an expanded sectional view of a covering particle. It is a graph which shows the relationship between pH value and zeta potential. It is an expanded sectional view which shows the state with which the ceramic slurry was filled with the clearance gap between the coating particles arranged in the close-packing form. FIG. 9 is an enlarged cross-sectional view showing a state in which the organic particles shown in FIG. 8 are gasified to form cells and communication holes. A TG curve of PMMA and Al ₂ O ₃ gel. It is an expanded sectional view which shows the state with which the cell and communication hole shown in FIG. 9 were filled with metal Si. It is an expanded sectional view of the covering particle which replaced a part of SiC particle with organic system small particles.

Explanation of symbols

1 Ceramic compact 11 Organic particles (first particles)
12 SiC particles (ceramic particles)
13, 13A Coated particles 14 SiC particles 15 C particles (first substance)
16 Ceramic slurry 17 Coated particle-ceramic slurry array 19 Metal Si (metal)
C cell H communication hole

Claims (5)

A method for producing a ceramic molded body having a three-dimensional network structure having a plurality of cells and a plurality of communicating holes in partition walls separating adjacent cells,
A plurality of coated particles formed by coating the surfaces of a plurality of first particles gasified by heating with a plurality of ceramic particles are arranged, and a ceramic slurry containing a gelling agent is filled between the arranged coated particles. A first step of producing a coated particle-ceramic slurry array;
A second step of gelling the gelling agent;
A third step of drying the gelled coated particle-ceramic slurry array;
A fourth step of forming the plurality of cells and the plurality of communication holes by heating the coated particle-ceramic slurry array to gasify the first particles;
A method for producing a ceramic molded body having a three-dimensional network structure characterized by comprising: The ratio of the average radius R1 of the coated particles and the average radius R2 of the particles forming the ceramic slurry is R1: R2 = 30 to 70: 1,
The ratio of the volume V1 of the plurality of coated particles and the volume V2 of the ceramic slurry is V1: V2 = 6: 4 to 9: 1,
The method for producing a ceramic molded body having a three-dimensional network structure according to claim 1, wherein the porosity of the coated particle-ceramic slurry array is lowered.   The ceramic slurry is mainly composed of SiC, and the first particles are mainly composed of at least one selected from the group consisting of PMMA, PS, PE, inorganic carbon, and silicon-based inorganic compound particles. The method for producing a ceramic molded body having a three-dimensional network structure according to claim 1 or 2, wherein SiC is a main component. The ceramic slurry in the first step contains a first substance that is a raw material of the ceramic molded body,
In the fourth step, without reacting the first substance, the plurality of cells and the plurality of communication holes are formed,
After the fourth step,
The plurality of cells and the plurality of communication holes are filled with a metal that reacts with the first substance to produce a ceramic, and a part of the metal reacts with the first substance to sinter while producing the ceramic. And a fifth step to
A sixth step of removing the unreacted metal;
The method for producing a ceramic molded body having a three-dimensional network structure according to any one of claims 1 to 3, further comprising:   A ceramic molded body having a three-dimensional network structure, which is manufactured by the method for manufacturing a ceramic molded body having a three-dimensional network structure according to any one of claims 1 to 4.

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