JP2001294490A - Method of producing ceramic porous body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a ceramic porous body, by which the ceramic porous body uniform in density and high in dimensional precision can be produced in various forms even when the ceramic porous body has partially projecting or recessed parts or different thicknesses. SOLUTION: In the method of producing the ceramic porous body having partially projecting or recessed parts or different thicknesses, the partially projecting or recessed parts or the part having different thicknesses are formed in such a manner that the forms of these parts are larger than the final forms, and at the stage when a formed body or a calcined body is produced and before firing, the formed body or the calcined body is subjected to cutting processing so as to make it a final form, and thereafter fired. For example, a thick part or bottom part of the formed body is worked so as to make it a final form using a lathe 15, or the like. A final product is obtained by firing the formed body subjected to the working in an electric furnace or a gas furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a porous ceramic body, and more particularly to a method for manufacturing a porous ceramic body having good dimensional accuracy.

[0002]

2. Description of the Related Art As a ceramic filter for removing dust and the like contained in exhaust gas discharged from various combustion equipment,
There is a bottomed cylindrical body as disclosed in Japanese Patent Application Laid-Open No. 55-119413, in which a partition wall near an opening end forms an annular thick portion that is thicker than other partition walls. In this filter, an annular thick portion near the opening end is used as a suspension support.

[0003] This filter is composed of a porous ceramic having a large number of continuous fine pores, and has an average pore diameter of 1 μm.
A material having a porosity of about 0 to 100 μm and a porosity of about 25 to 60% is used.

The following two methods are mainly used as a method for manufacturing such a ceramic filter. (1) Rammer molding This is a method of gradually filling the lower part of a molding die with a molding material as described in JP-B-63-56816, and simultaneously moving the rammer up and down to compression-mold to a constant pressure density. . (2) CIP molding A raw material powder is filled in a deformable mold (such as a rubber mold),
On the other hand, based on Pascal's principle, a method is used in which a liquid such as water or oil is used as a pressurized medium and the mold is compressed under hydrostatic pressure to form the liquid.

[0005] In order to obtain the above pore diameter and porosity, the porous body has a particle size of 50 μm to
000 μm aggregate particles, and a particle-bonded porous body composed of a ceramic-based or glass-based fusion material that binds the aggregate particles; the above-described pore diameter and porosity are determined by using a sintering reaction in a firing process. The reaction-sintered porous body to be obtained.

[0006]

The above-mentioned molding methods have the following problems. (1) Rammer molding Since the operation of gradually filling the molding raw material and consolidating is repeated, it takes time until the molding is completed, and the production cost increases. Since the operations of material filling and consolidation are repeated, non-uniformity and uneven density of the boundary surface occur in each consolidation operation, resulting in deformation, drying cracks, and firing cracks, which lowers the yield. In the conventional molding method, the shape of the annular thick portion near the opening end needs to be an inclined surface shape that expands outward toward the opening end, such as the filter 11 shown in FIG. This is because the conventional molding method is liable to cause non-uniform density due to the difference in the thickness of the molded body. Particularly, in the case of the shape such as the filter 12 of FIG. The density of the thick wall partition was lower than that of the other thick wall partitions, and molding was impossible.

As described above, the conventional rammer molding method has a disadvantage that the shape that can be molded is limited in order to avoid unevenness in the density of the molded body.

(2) CIP molding (Cold Isostatic Pre
(Ssing: cold isostatic pressing) CIP molding is a molding method superior to the rammer molding in that a molded article having a uniform density can be obtained.

However, in this CIP molding method, the shape of the annular thick portion near the opening end is limited to the deformable shape of the rubber mold because molding is performed by utilizing the deformation of the mold. The shape was rounded like the filter 13 shown in FIG. 3, and it was difficult to form a sharp filter shape as shown in FIG.

Regarding the shape of the bottom portion of the filter, since the molding of portions having different wall thicknesses has different compression degrees, it takes a lot of time and effort to design the rubber mold to obtain the final shape. Even if a shape close to that shown in FIG. 2 is obtained, it is necessary to use a different mold if the type and properties of the raw material powder (especially the average particle size and compression ratio) change, which causes an increase in cost. Had become.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a method for manufacturing a ceramic porous body capable of manufacturing a ceramic porous body having a partially convex portion with high dimensional accuracy. I do.

[0012]

According to the method for producing a porous ceramic body of the present invention, at least a portion is formed into a larger shape than the final shape, and is cut at the stage of a formed body before firing or a calcined body. It is characterized in that it is shaped and then fired.

In the method for producing a porous ceramic body according to the present invention, for example, the convex portion, the concave portion, or the portion where the thickness changes are formed to be larger or shallower than the final shape, Since it is cut into the final shape, a molded body with good dimensional accuracy can be obtained.

In the case of a porous ceramic body, when processing is performed with the final fired body, shavings generated during the processing enter the porous portion of the product and cause clogging, and the original function as a porous filter can be obtained. On the other hand, in the case of processing with a molded body or a calcined body before firing, a reaction sintered type porous body that develops porosity due to a reaction at the time of firing (Japanese Patent No. 2823140, Japanese Patent No. 2800134, In the case of the porous body described in Japanese Patent Publication No. Hei 2-12899), even if the shavings enter the molded body, the effect of the shavings is very small because the reaction at the time of firing develops porosity. Therefore, the present invention is suitable for application to a method for producing a porous body of a reaction sintered body.

[0015] In the case of a particle-bound type porous body, particularly 100
When obtaining a porous body having a large pore diameter of μm or more, the pore diameter of the compact and the pore diameter after firing hardly change, so when processing at the stage of the compact, the shaving powder that closed the pores of the compact was fired. After the baking, problems such as clogging occur as in the case of processing after firing, and when coarse particles of 500 μm or more are used for the aggregate, the strength of the molded body is weak and processing is difficult, Since the surface condition may be deteriorated due to the peeling of the aggregate particles, the pore size may be reduced to less than 100 μm or the aggregate particles may be reduced to 5 μm.
Preferably it is less than 00 μm.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a ceramic filter having the shape shown in FIG. 2 is formed. This molded body has a shape in which one end is open, the other end is closed, and the other end side has a thick flange or flange.

(1) First, a raw material powder is filled in a mold as shown in FIG. The mold filled with the raw material (FIG. 5 (2)) is inserted into a molding machine and molded (FIG. 5 (3)). In this case, the molded body after the completion of the molding is similar to the molded body 14 shown in FIG.
Finally, the opening end thick portion and the bottom portion are formed so as to be larger than the final shape.

In FIG. 5A, the core 4 is coaxially inserted into the rubber mold 5, and the lower part between the two is the lower lid 1.
b. The upper lid 1a has been removed,
Raw material powder is supplied from the raw material hopper 2 between the metal core 4 and the rubber mold 5. After filling the raw materials, FIG.
The upper lid 1a is attached as shown in FIG. 5, and this is set in the holding case 6 of the pressing tool 22 as shown in FIG.
7b sandwich it from above and below. The pressurizing tool 22 has the pressurized cylindrical body 9 fitted inside the holding case 6. The holding case 6 includes a rigid outer cylinder 23 and an inner cylinder 21 for backing up the pressure cylinder 9, and an annular pressure chamber 24 is formed between the outer cylinder 23 and the inner cylinder 21. Then, the pressurized liquid 8 is supplied between the pressurized cylinder 9 and the inner cylinder 21 via the pressurized liquid supply port 10. With the inflow of the pressurized liquid 8, the rubber mold 5 is strongly pressurized from the outside via the pressurized cylindrical body 9 to perform CIP molding.

(2) The molded body obtained by the CIP molding as described above is processed into a thick part and a bottom part of the final shape by processing with a lathe 15, as shown in FIG. In this process, in FIG. 6, both ends of the molded body 14 are held by holders 15a and 15b, and the molded body 14 is rotated around its axis to remove unnecessary portions 14a and 14b.
Cutting is removed by c. Depending on the strength of the compact,
It may be performed after calcining at a temperature lower than the final firing temperature.

(3) The formed product is fired in an electric furnace or a gas furnace to obtain a final product.

[0021]

Embodiments Hereinafter, specific embodiments will be described.

Example 1 Reactive sintered porous body Silica-bearing stone, limestone and clay adjusted to a predetermined particle size are divided by weight.
In a ratio of 70.2: 22.1: 7.7 in total (CaO
 14.0% by weight, SiO₂74% by weight, Al ₂O₃1
2% by weight) and 80% by weight of water
Add about 5% powder and mix, mix with ball milling,
PVA (polyvinyl alcohol) as an organic binder
), Dried and granulated with a spray drier
Powder was obtained. After filling this into the rubber mold shown in FIG.
Insert the mold into the molding machine and press the molding pressure 200kgf / cm³
At a pressure of Obtained molded product (the shape of FIG.
of. (Length 1500mm) by lathe processing into the shape of Fig. 2
Then, this is kept in a firing furnace at a maximum temperature of 1200 ° C. for one hour.
And fired. This makes the main crystal phase quartz (quartz)
(SiO₂), Partly transferred to cristobalite), average fine
A porous filter having a pore size of 40 μm and a porosity of 35% can be obtained.
Was. This filter has no cracks and is fired.
The deformation was very good.

Example 2 A raw material was prepared in the same manner as in Example 1 except that the reaction sintering type porous material was synthetic mullite, talc (talc), and silica stone, and the weight ratio thereof was 53: 39: 8. The molded and processed product was held in a firing furnace at a maximum temperature of 1420 ° C. for 1 hour and fired. The obtained fired body is a porous filter whose main crystal is cordierite and is partially composed of mullite and has an average pore diameter of 30 μm and a porosity of 35%. Was less favorable.

Example 3 The same as Example 1 except that the fused alumina (average particle size 50 μm) and silica (average particle size 1 μm) were used as raw materials and the weight ratio thereof was 95: 5. The raw material was prepared, molded and processed, and was fired at a maximum temperature of 1600 ° C. for 1 hour in a firing furnace. In the obtained fired body, the main crystal was made of corundum and partly made of mullite, the average pore diameter was 15 μm, and the porosity was 40.
% Of the porous filter. In this case as well, no crack was generated and the deformation due to firing was very small.

[0025]

As described above, according to the method for manufacturing a porous ceramic body of the present invention, the following effects can be obtained. (1) With respect to a method of forming a porous ceramic body having a convex portion, a concave portion, or a portion where the thickness changes, a product having better dimensional accuracy and uniform density can be obtained as compared with a conventional forming method. (2) Even if the shape of the thick portion or the bottom of the opening end changes or the type or properties of the raw material change, it is possible to respond to an arbitrary shape by processing the molded body without changing the mold, which is advantageous in cost. It is. (3) For example, it is possible to manufacture even the shape of the thick portion at the opening end as shown in FIG. 3 which is impossible by the conventional molding method.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a ceramic filter as a ceramic porous body.

FIG. 2 is a sectional view showing an example of a ceramic filter as a ceramic porous body.

FIG. 3 is a sectional view showing an example of a ceramic filter as a ceramic porous body.

FIG. 4 is a sectional view of a CIP molded body (before processing).

FIG. 5 is a sectional view showing a CIP molding method.

FIG. 6 is a cross-sectional view illustrating a method for processing a molded body.

[Explanation of symbols]

 11, 12, 13 Ceramics filter 14 Molded product 15 Lathe

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yasuhito Nakajima 5-1-1 Koiehonmachi, Tokoname-shi, Aichi Prefecture Inax Corporation (72) Inventor Hirokazu Matsumoto 5-1-1 Koiehonmachi, Tokoname-city, Aichi Prefecture Inax Corporation F term (reference) 4D019 AA01 BA05 BA06 BA07 BB06 CA03 CB06 4G019 GA01 4G030 AA08 AA36 AA37 CA09 GA05 GA14 GA16 HA05 HA06 HA25

Claims (4)

[Claims] In a method of manufacturing a porous ceramic body, at least a part is formed into a larger shape than a final shape, and is cut into a final shape by cutting at a stage of a green body before calcining or a calcined body, and then calcined. A method for producing a porous ceramic body, comprising: 2. The method according to claim 1, wherein the step of forming the convex portion is made larger than the final shape, and the forming is performed before firing. A method for producing a porous ceramic body, comprising cutting at the stage of a body or a calcined body to obtain a final shape, followed by firing. 3. The method according to claim 1, wherein the porous ceramic body has a partially recessed concave portion, wherein the concave portion is formed to be shallower than a final shape.
A method for producing a porous ceramic body, comprising cutting a molded body or a calcined body before firing into a final shape, and then firing. 4. The method for producing a porous ceramic body according to claim 1, wherein the ceramic body has a portion having a partially changed thickness, wherein the portion is formed to be larger than a final shape, Alternatively, a method for producing a porous ceramic body, characterized in that a cutting process is performed at a stage of a calcined body to obtain a final shape, and thereafter, a firing is performed.