JP2009179517A - Ceramic joined body for gas jetting port and gas distribution plate, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic joined body providing stable flow rate when used as a gas jetting port of a gas distribution plate, and to provide the gas distribution plate using the same and a method of manufacturing the gas distribution plate with high yield. <P>SOLUTION: The ceramic joined body for the gas jetting port is obtained by directly joining a porous ceramic obtained by pressure sintering and having a necking structure of a ceramic coarse granule to a circular dense ceramic without interposing a joining layer. The pressure sintering is discharge plasma sintering. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a ceramic bonded body for a gas outlet, a gas dispersion plate, and a manufacturing method thereof.

Conventionally, a joined body obtained by joining porous ceramics and dense ceramics is used for the gas dispersion plate. As an example of such a joined body, Patent Document 1 is fitted with a hollow ceramic calcined body having an inner circumference that substantially surrounds the outer circumference of the porous ceramic, and is fired at a temperature higher than the calcining temperature. The resulting bonded body is disclosed. In Patent Document 2, the dense portion is formed by sintering ceramic fine particles, and the porous portion is formed by sintering ceramic coarse particles, and the ceramic fine particles and ceramic coarse particles are added together. A pressure-sintered ceramic joined body is disclosed.
JP 2003-238267 A JP 2002-338334 A

In the method of forming porous ceramics by stirring and foaming as in Patent Document 1, most of the closed cells that do not communicate with the outside are unsuitable for a gas dispersion plate that requires air permeability. Further, in the method of integrating the dense portion and the porous portion by pressure sintering as in Patent Document 2, the problem that the outer diameter of the porous portion changes depending on the pressing condition, There is a problem that the pressed dense portion is not uniformly densified, and the porous portion is deformed accordingly. If there is such a problem, the porous portion becomes inhomogeneous and the dimensional accuracy also deteriorates, so that the gas cannot be uniformly dispersed and practical use is difficult.

As shown in Patent Document 1, when porous ceramics and dense ceramics are joined, a method is employed in which the firing shrinkage rate of the ceramics is adjusted so that the shapes after joining coincide with each other. Since it is necessary not only to match the shape after shrinkage but also to match the shrinkage time, it is very difficult to completely integrate them. When the contraction time is different, there is a problem that the dense ceramic or the porous ceramic is cracked or inclined and joined to form a gap at the joint.

Further, in a gas dispersion plate having a large number of gas outlets, the gas cannot be evenly distributed unless the gas flow rates of the individual gas outlets are equal. For this reason, it is necessary to make the bonding state such as the pore diameter and the porosity of the porous ceramics fitted in each gas ejection port, and the presence or absence of gaps, and it is very difficult to achieve this. In particular, even if it is possible to make the pore diameter and porosity of porous ceramics uniformly, it is difficult to equalize the joining state when fitted into the gas outlet, resulting in variations in gas flow rate was there. Further, since the gas flow rate of each gas dispersion plate also varies, there is a problem that the gas pressure must be adjusted for each gas dispersion plate, and the operation becomes complicated.

Furthermore, when gaps or the like are generated in some gas ejection ports and the variation in flow rate becomes large, the performance as a gas dispersion plate cannot be exhibited due to only a part of the gaps. Therefore, there is a problem that the yield of the gas dispersion plate is poor and the cost is high.

The present invention has been found in view of these problems, and can obtain a stable flow rate when porous ceramics and dense ceramics are directly joined without gaps and used as a gas outlet of a gas dispersion plate. The present invention provides a ceramic joined body that can be manufactured and a gas dispersion plate using the same, and a method that can manufacture the gas dispersion plate with a high yield.

In order to solve the above-mentioned problems, the present invention provides a porous ceramic having a necking structure of coarse ceramic grains obtained by pressure sintering, and a ring-shaped dense ceramic directly bonded without a bonding layer. A ceramic joined body for a gas outlet is provided.

The porous ceramic of the present invention is preferably one produced by spark plasma sintering among pressure sintering. In the case of the discharge plasma sintering, since the sintering proceeds by the heat generated by the discharge plasma between the particles, a homogeneous porous ceramic can be obtained. In the discharge plasma sintering, the discharge plasma concentrates on a portion where a bond between the ceramic coarse grains is to be formed, and necking is formed. Necking is locally generated by the discharge plasma between the ceramic coarse particles, and melts and vaporizes and proceeds. Therefore, since the sintering of the particle surface is proceeding more than normal sintering, sintering shrinkage during subsequent joining with the annular dense ceramics and joining with the main body of the gas dispersion plate is suppressed. .

The present invention provides a gas dispersion plate in which a ceramic bonded body for a gas ejection port and a main body of a gas dispersion plate are directly joined without using a joining layer. Since the annular dense ceramic of the ceramic bonded body for a gas outlet is dense, it does not cause sintering shrinkage when bonded to the main body. Therefore, there is no inclination or cracking due to a shift in contraction timing. Furthermore, since the ceramic dense body for gas jets is joined with an annular dense ceramic, the gas flow rate can be confirmed before joining. In addition, since the pore diameter and the porosity do not change before and after joining the gas dispersion plate to the main body, the gas dispersion plate having the same characteristics as the gas flow rate characteristics of the ceramic joined body for the gas orifice confirmed before joining is used. Can be formed.

Furthermore, the present invention provides a first sintering step of pressure-sintering a ceramic coarse-grained compact to obtain porous ceramics, and inserting the porous ceramic into a ring-shaped ceramic fine-molded compact, and the annular compacted compact And a method for manufacturing a ceramic bonded body for a gas outlet including a second sintering step of directly bonding an annular dense ceramic and the porous ceramic.

By combining porous ceramics obtained by pressure sintering of ceramic coarse particles and an annular molded body of ceramic fine particles, a joined body joined without a gap without a joining layer can be obtained. Further, as described above, in the discharge plasma sintering, the discharge plasma concentrates on a portion where a bond between ceramic coarse grains is to be formed, and necking is formed. Necking is locally generated by the discharge plasma between the ceramic coarse particles, and melts and vaporizes and proceeds. Therefore, since the sintering of the particle surface proceeds more than normal sintering, sintering shrinkage at the time of subsequent bonding with the dense ceramic and the bonding with the main body of the gas dispersion plate is suppressed.

The annular molded body is designed so that the inner diameter when sintered without fitting the porous ceramic is 1 to 7% smaller than the outer diameter of the porous ceramic. By setting the baking rate within this range, bonding can be performed without any gaps or cracks.

Furthermore, the step of fitting the obtained ceramic bonded body for gas outlet into a hole provided in the ceramic molded body that becomes the main body of the gas dispersion plate after sintering, densifying the ceramic molded body, and gas A method for producing a gas dispersion plate is provided, which includes a third sintering step in which a main body of the dispersion plate and the ceramic bonded body for a gas ejection port are directly joined. Moreover, the hole part of the ceramic molded body used as the main body has an inner diameter when sintered without fitting the ceramic joined body for gas ejection port, which is 1 to 7 than the outer diameter of the ceramic joined body for gas ejection port. Designed to be% smaller.

Here, before the third sintering step for joining the main body of the gas dispersion plate and the ceramic bonded body for the gas ejection port, a gas flow rate measurement is performed on the gas ejection ceramic bonded body and a predetermined condition is used. It is desirable. As described above, since the annular dense ceramics are joined to the gas spout ceramic joined body, the gas flow rate can be confirmed before joining. In addition, since the pore diameter and the porosity do not change before and after joining the gas dispersion plate to the main body, the gas dispersion plate having the same characteristics as the gas flow rate characteristics of the ceramic joined body for the gas orifice confirmed before joining is used. Can be formed. Therefore, the entire gas flow rate of the gas dispersion plate can be reliably adjusted, and the uniformity of gas dispersion can be secured. Furthermore, the yield of the gas dispersion plate can be significantly increased.

As described above, according to the present invention, a ceramic joined body capable of obtaining a stable flow rate and a gas dispersion plate using the ceramic joined body can be provided, and a method capable of producing a gas dispersion plate with a high yield can be provided. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view of a ceramic bonded body 10 for a gas outlet. The porous ceramics 11 and the annular dense ceramics 12 are joined without a gap without a joining layer.

The porous ceramic 11 is composed of a necking structure by pressure sintering of ceramic coarse particles. Here, various ceramics such as alumina, silicon carbide, silicon nitride, aluminum nitride, and zirconia can be used as the ceramic coarse particles. The average particle diameter (D50 by laser diffraction particle size distribution measurement. The same applies to the ceramic raw material particle diameter) is preferably 10 to 50 μm. By using such a raw material, the porosity and pore diameter of the porous ceramic can be adjusted, and a porous ceramic suitable for the present invention can be obtained.

The average particle size after sintering of the porous ceramic of the present invention (measured by the optical microscope particle size observation intercept method; the same applies to the particle size after sintering) is equal to the average particle size of the raw ceramic coarse particles. is there. This is because since discharge plasma sintering is performed, only sintering by necking of the particle surface proceeds, and grain growth hardly occurs. The average pore diameter (mercury intrusion method) of the porous ceramic is preferably 2 to 25 μm and the porosity is preferably 10 to 50%. By adjusting within the above range, it is suitable for the gas dispersion plate.

The annular dense ceramic 12 is a sintered body of ceramic fine particles. As ceramic fine particles, various ceramics such as alumina, silicon carbide, silicon nitride, aluminum nitride, and zirconia can be used. However, the same kind of material as the ceramic used for the porous ceramic is desirable in terms of thermal expansion matching. The average particle size of the ceramic fine particles is preferably 0.1 to 1 μm. The ceramic fine particles are used because it is necessary to use a powder having higher sinterability than the ceramic coarse particles in order to obtain dense ceramics. It should be noted that by setting the porosity of the annular dense ceramic to 0.1% or less, gas leakage from the portion surrounding the porous ceramic in an annular shape can be suppressed.

The thickness (difference between the outer radius and the inner radius) of the annular dense ceramic is preferably 0.5 to 3 mm. This is because if the wall thickness is less than 0.5 mm, cracks may occur during processing and handling, and if it is more than 3 mm, there is no merit in that raw material costs and processing costs are increased or simplicity is reduced. It is.

FIG. 2 is a schematic sectional view of the gas dispersion plate 20 of the present invention. The ceramic bonded body for the gas ejection port composed of the porous ceramic 21 and the annular dense ceramic 22 described above is fitted into the main body 23 of the gas dispersion plate, and the porous ceramic as the gas ejection port is inserted into the gas hole 24. Communicates.

The main body 23 of the gas dispersion plate is made of dense ceramics. As the ceramic material, various ceramics such as alumina, silicon carbide, silicon nitride, aluminum nitride, zirconia, and the like can be used. However, the same type of material as the ceramic used for the gas outlet is desirable in terms of thermal expansion matching, and it is preferable to use a material that is equivalent to or easier to sinter than that used for the annular dense ceramic. This is because the main body sinters and shrinks when the ceramic bonded body for gas jets and the main body are joined (third sintering step), but the joined body does not shrink. Therefore, it is desirable to use a ceramic powder having a sinterability at least equivalent to that of the annular dense ceramic.

FIG. 2 is a schematic view of only one gas outlet, but actually a plurality of gas outlets are provided. Various arrangements such as radial and concentric circles can be employed, and the number is not particularly limited. In the present invention, even in the case of a gas dispersion plate having a large number of gas ejection ports, the gas flow rate of the ceramic bonded body for gas ejection ports is uniform, and the gas flow rate after bonding does not change, so that the production is easy. Yes, it can be manufactured with good yield.

Next, the manufacturing method of the ceramic joined body for gas jets of this invention and a gas dispersion plate is demonstrated.

The porous ceramic is obtained by pressure sintering (first sintering step) of ceramic coarse particles having an average particle size of 10 to 50 μm. The particle size distribution of the ceramic coarse particles is preferably sharp with little variation. This is to reduce the uniformity in the porous ceramic and the variation in the gas flow rate between the gas outlets.

Molding is performed by filling a carbon jig with powder and pressing it. The powder is uniformly filled so that the press is not biased. The carbon jig is adjusted by inserting a spacer so that porous ceramics having a predetermined porosity can be obtained.

Next, the ceramic coarse particles are subjected to pressure sintering. As the pressure sintering method, hot pressing is preferable, and among these, discharge plasma sintering is most preferable. In the discharge plasma sintering, a pulse current is passed through a carbon jig while applying pressure to generate plasma between particles, and necking can be formed between particles. Therefore, the sintering of the particle surface has progressed more than normal sintering, and porous ceramics are less likely to cause shrinkage during subsequent bonding with dense ceramics or with the gas dispersion plate body. It is possible to obtain a bonded body closely adhered without a gap. Moreover, after processing a porous ceramic as needed and adjusting a shape, it is good to join with a cyclic | annular dense ceramic.

Ceramic fine particles can be used as the raw material for the annular dense ceramic, and a general method such as CIP can be adopted as the forming method. Here, since a large number of ceramic bonded bodies for gas ejection ports of the present invention are required for one gas dispersion plate, it is preferable that they can be produced in large quantities at a time. Therefore, for example, it is possible to employ a method in which a large number of annular portions are formed in an island shape on a flat plate molded body of ceramics, and porous ceramics are fitted into the annular portions and joined, and then the flat plate portions are cut off.

The annular molded body (annular portion) of the ceramic is designed such that the inner diameter when sintered without fitting the porous ceramic is 1 to 7% smaller than the outer diameter of the porous ceramic. If the baking rate is within this range, a gap is not formed between the annular dense ceramic and the porous ceramic, and it is possible to produce the ceramic without cracking.

The sintering temperature in the second sintering step can be equal to or higher than that in the first sintering step. This is because the spark plasma sintering in the first sintering process generates large energy locally between the particles and the sintering proceeds, so even if the sintering temperature is increased in the second process, the sintering shrinkage, etc. This is because the inconvenience does not occur. The first sintering step is pressure sintering, while the second sintering step is atmospheric pressure sintering. In this way, if the first sintering step is pressure sintering and the second sintering step is atmospheric pressure sintering, it is possible to easily join without defects such as cracks.

The gas flow rate can be confirmed after the ceramic bonded body for the gas outlet is obtained and before the bonding with the main body. At this time, even if a desired gas flow rate cannot be obtained, it can be removed before joining, so that the yield of the gas dispersion plate can be significantly improved. Since the gas flow rate of the ceramic bonded body is equal to the gas flow rate after bonding to the main body, the gas flow rate of the gas dispersion plate as a whole can be adjusted, and the flow rate variation of each gas jet port can be reliably suppressed. .

FIG. 3 is a schematic cross-sectional view of the hole of the ceramic molded body that becomes the main body of the gas dispersion plate after sintering. By fitting the ceramic joined body for gas ejection port obtained as described above into a hole 34a provided in the ceramic molded body 33 and sintering, the ceramic molded body is densified and the gas dispersion plate The main body and the ceramic bonded body for the gas outlet are directly bonded. As in the case of the annular molded body, the hole 34a of the ceramic molded body 33 serving as the main body has an inner diameter when sintered without fitting the ceramic bonded body for the gas outlet, and the ceramic bonded body for the gas outlet. It is designed to be 1 to 7% smaller than the outer diameter. If the baking rate is within this range, a gap cannot be formed between the ceramic spout for gas ejection port and the main body of the gas dispersion plate, and it can be produced without causing cracks.

The sintering temperature in the third sintering step is preferably equal to or lower than that in the second sintering step. This is because the second sintering step and the third sintering step are normal atmospheric pressure sintering, and if heated to a high temperature in the third sintering step, the dense ring-shaped ceramics may shrink. is there.

Hereinafter, the present invention will be described in detail with reference to examples.

First, ceramic bonded bodies for gas jets were produced (Table 1 Test Nos. 1 to 16). For spark plasma sintering indicated as SPS in Table 1, coarse alumina particles (average particle size 20 μm, purity 99.5%) were packed in a carbon die having an inner diameter of φ100 mm, temporarily pressed at 60 MPa, and a temperature increase rate of 30 ° C. / Spark plasma sintering was performed by applying a pressure of 60 MPa for 30 minutes at 1550 ° C. for min. For hot press sintering indicated as HP in Table 1, using similar alumina coarse particles and carbon dies, temporary pressing was performed at 0.1 MPa, the heating rate was 300 ° C./min, 1625 ° C. for 180 minutes, and 8 MPa. Hot press sintering was performed under pressure. The porosity of the obtained porous ceramic measured by the Archimedes method was 21%, and the pore diameter measured by the mercury intrusion method was 3 μm. Moreover, when the average particle diameter after sintering was observed by an optical microscope and measured by the intercept method, it was 20 μm, which is equivalent to the average particle diameter of the raw material coarse particles. The obtained porous ceramic was processed into a cylindrical shape having an outer diameter and a thickness of 5 mm shown in Table 1.

Next, an annular molded body (a flat molded body formed with a large number of annular portions) was produced. A molding binder was added to alumina fine particles (average particle size 1 μm, purity 99.5%), granulated, and CIP, followed by raw processing. The dimensions of the annular molded body (annular portion) were designed such that the inner diameter after sintering was smaller than the outer diameter of the porous ceramic at a predetermined ratio (baking rate (%)) shown in Table 1. Porous ceramics was put inside the annular portion, and the temperature was increased at 10 ° C./h and held at 1600 ° C. for 3 hours to perform sintering (second sintering step). After the sintering, the flat plate portion and the like were removed by processing to obtain a ceramic bonded body for a gas outlet. Among the joined bodies, the porosity of the annular dense ceramics was 0.1% or less.

For comparison, a joined body was similarly produced for porous ceramics obtained by CIP molding using alumina granules containing a molding binder and then pressureless sintering (Production No. 16).

The gas flow rates of the 20 ceramic bonded bodies for gas ejection ports thus obtained were measured. The gas flow rate is measured by placing a suction cup having a larger diameter than the porous ceramic provided at the tip of the intake pipe on one surface of the porous ceramic of the ceramic bonded body for the gas outlet, and a vacuum pump with a predetermined displacement The gas (atmosphere) flow rate flowing through the porous ceramics was measured when connected to and vacuum suctioned, and the variation (standard deviation / average value × 100 (%)) was calculated. The results are shown in Table 1.

Production No. 1 which is a ceramic joined body for a gas outlet of the present invention. The variation in the gas flow rate of 1 to 13 was smaller than 5%, and the flow rate was stable. Production No. with a design value of the baking rate smaller than the range of the present invention. In No. 14, since a gap was generated at the joint, the variation in gas flow rate was large. In addition, the production No. in which the design value of the baking rate is larger than the range of the present invention. In No. 15, since the annular dense ceramic was cracked, a joined body could not be obtained. Production No. 1 using porous ceramics sintered at atmospheric pressure In No. 16, since the sintering contracted in the second sintering step and a gap was generated in part, the variation in gas flow rate became large.

Next, the ceramic bonded body for gas jet nozzles was bonded to the main body of the gas dispersion plate. The ceramic molded body as the main body was prepared by adding a molding binder to alumina fine particles (average particle size 1 μm, purity 99.5%), granulating and CIP, and then raw processing. The size of the ceramic molded body as the main body is a predetermined ratio (baked and tightened) as shown in Table 2, in which the inner diameter after sintering of the hole portion into which the ceramic bonded body for gas outlets is fitted is larger than the outer diameter of the dense ceramic with annular shape. It was designed to be smaller at a rate (%). The ceramic bonded body for gas outlets was put in the hole, and sintering was performed by holding at a heating rate of 10 ° C./h and 1600 ° C. for 3 hours (third sintering step). In addition, production No. which did not use annular dense ceramics. About 41-43 (Table 2), it designed so that the internal diameter of a hole part might become smaller in a predetermined ratio than the outer diameter of porous ceramics. The gas dispersion plate was disc-shaped and had an outer diameter of 200 mm, and the holes into which the gas jet ceramics were fitted were arranged in a radial pattern, with 20 holes. The porosity of the sintered main body was 0.1% or less. The gas flow rate test was measured in the same manner as in the case of the joined body, with a suction cup in close contact with each gas outlet. The results are shown in Table 2.

Preparation No. which is a gas dispersion plate of the present invention. The variation in the gas flow rate of 21 to 27, 29 to 32, and 34 to 39 was smaller than 5% as in the joined body, and the flow rate was stable. Further, the gas flow rate at each gas outlet was almost the same as the flow rate of the joined body. On the other hand, the design value of the baking rate of the main body of the gas dispersion plate is smaller than the range of the present invention. In No. 28, a gap was generated in the joint portion, so that the variation in the gas flow rate was large. In addition, the production No. in which the design value of the baking rate is larger than the range of the present invention. In No. 33, since a crack was generated in the annular dense ceramic, a gas dispersion plate could not be obtained. Production No. 1 using porous ceramics sintered at atmospheric pressure In No. 40, since the sintering contracted further in the third sintering step and a gap was formed in part, the variation in gas flow rate became large. Production No. without using an annular dense ceramic In 41-43, since the clearance gap produced between porous ceramics and a main body, the flow volume from a part of gas hole became large, and the dispersion | variation became large.

In the above production example, an example in which the gas outlets of the gas dispersion plate are evenly adjusted has been shown. However, the present invention is not limited to this, and the gas outlets may have an arbitrary gas flow rate. Needless to say, a gas dispersion plate having a desired dispersibility can be produced.

It is a schematic sectional drawing of the ceramic joined body for gas jet nozzles of this invention. It is a schematic sectional drawing of the gas dispersion plate of this invention. It is a schematic sectional drawing of the hole of a ceramic molded body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Ceramic joined body 11 for gas outlets, 21: Porous ceramics 12, 22: Dense ceramics 20 annular: Gas dispersion plate 23: Main body 24: Gas hole 33: Ceramic compact 34a: Hole

Claims (9)

A ceramic bonded body for gas jets, characterized in that a porous ceramic having a necking structure of coarse ceramic grains obtained by pressure sintering and an annular dense ceramic are directly bonded without a bonding layer. . 2. The ceramic bonded body for a gas outlet according to claim 1, wherein the pressure sintering is spark plasma sintering. 3. A gas dispersion plate, wherein the gas spout ceramic bonded body according to claim 1 and the gas dispersion plate main body are directly joined without a joining layer. A first sintering step of pressure-sintering the ceramic coarse-grained compact to obtain porous ceramics;
A second sintering step in which the porous ceramic is fitted into an annular molded body of ceramic fine particles, the annular molded body is densified, and the annular dense ceramic and the porous ceramic are directly joined;
A method for producing a ceramic bonded body for a gas outlet comprising: The method for producing a ceramic bonded body for a gas jet according to claim 4, wherein the first sintering step is discharge plasma sintering. 6. The annular molded body is designed such that the inner diameter when sintered without fitting the porous ceramic is 1 to 7% smaller than the outer diameter of the porous ceramic. The manufacturing method of the ceramic joined body for gas ejection outlets of description. A step of fitting the ceramic bonded body for a gas nozzle obtained by the manufacturing method according to claim 4 into a hole provided in a ceramic molded body that becomes a main body of a gas dispersion plate after sintering;
A third sintering step of densifying the ceramic molded body and directly bonding the main body of the gas dispersion plate and the ceramic bonded body for the gas outlet;
The manufacturing method of the gas dispersion plate containing this. The hole part of the ceramic molded body is designed such that the inner diameter when sintered without fitting the ceramic joint for gas outlet is 1 to 7% smaller than the outer diameter of the ceramic joint for gas outlet. The method of manufacturing a gas dispersion plate according to claim 7. The method for manufacturing a gas dispersion plate according to claim 7 or 8, wherein a gas flow rate measurement is performed on the ceramic bonded body for a gas outlet and a predetermined condition is used.

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