JP6612817B2 - Mold, mold manufacturing method and ceramic molded body manufacturing method - Google Patents

Description

  The technology disclosed in this specification relates to a mold.

  As a method for manufacturing a ceramic molded body (molding method), a ceramic molded body is formed by pouring a mixture (slurry) of ceramic powder, a dispersant, and water as a solvent into a mold while applying pressure, and allowing the mold to absorb the solvent. Pressure casting is known for manufacturing.

  For pressure casting, for example, a gypsum mold is used as a mold. However, if a gypsum mold is used for pressure casting, ions (calcium ions and sulfate ions) may diffuse from the gypsum mold to the ceramic molded body. If diffusion of ions from the gypsum mold to the ceramic molded body occurs, it is necessary to raise the firing temperature when firing the ceramic molded body thereafter, which may cause abnormal grain growth and reduce the strength of the ceramic sintered body. There is. Moreover, since the gypsum mold has a relatively low strength, there is a risk of cracking when used repeatedly.

  Then, the technique using the shaping | molding die (henceforth "alumina porous body type | mold") formed with the alumina porous body instead of the gypsum mold is known (for example, refer patent document 1). If an alumina porous body mold is used for pressure casting, it is possible to avoid the diffusion of ions from the mold to the ceramic molded body, and to suppress the occurrence of cracks in the mold.

JP 2004-315313 A

  However, the conventional alumina porous body type contains not a few impurities. Therefore, when pressure casting is performed using such a conventional alumina porous body mold that contains impurities, impurities are mixed into the produced ceramic body as in the case of using a gypsum mold. There exists a subject that the quality of a molded object may fall. Moreover, the conventional alumina porous body type has a large variation in pore diameter. This is because, for example, during the manufacturing (firing) of the mold, the sinterability varies due to abnormal grain growth due to the presence of impurities contained in the material, or the sintered part and the unfired mold are formed on the mold. This is because the tie part coexists. Therefore, when pressure casting is performed using a conventional alumina porous body mold having a large variation in pore diameter, the solvent in the slurry cannot be uniformly absorbed by the mold, and the ceramic molded body is locally There is a problem in that there is a risk that deterioration in quality (solidity, denseness, etc.) may occur.

  In this specification, the technique which can solve the subject mentioned above is disclosed.

  The technology disclosed in the present specification can be realized as, for example, the following forms.

(1) A mold disclosed in the present specification is a ceramic molded body obtained by pouring a mixture of ceramic powder, a dispersant, and water as a solvent into a mold while applying pressure, and allowing the mold to absorb the solvent. In the molding die used for manufacturing, the alumina has a purity of 99 wt% or more and a porosity of 15% or more and 60% or less. As described above, the mold is formed of an alumina porous body having an extremely high purity (that is, an extremely small impurity content). Therefore, according to the present mold, when a ceramic molded body is produced by pressure casting using the mold, impurities can be prevented from being mixed into the produced ceramic molded body. It is possible to suppress the deterioration of quality. In addition, since this mold is formed of an alumina porous body having a purity of 99 wt% or more, the sinterability varies due to the presence of impurities contained in the material during the manufacture (firing) of the mold. As a result, the variation in pore diameter is reduced. Therefore, according to the present mold, when producing a ceramic molded body by pressure casting using the mold, it is possible to suppress variations in solvent absorbability, and as a result, the produced ceramic molded body. The deterioration of local quality (solidity, denseness, etc.) can be suppressed. In addition, according to the present mold, since the porosity can be suppressed from being excessively low, the water absorption of the mold is excessively low, so that the thickness of the mold during pressure casting using the mold is increased. It can suppress that property falls.

(2) The said shaping | molding die WHEREIN: The average pore diameter of the said alumina porous body is good also as a structure which is 0.09 micrometer or more and 0.54 micrometer or less. As described above, in the present mold, the average pore diameter of the alumina porous body constituting the mold is not excessively small as 0.09 μm or more. Therefore, when the ceramic molded body is manufactured by pressure casting using the mold. Moreover, it can suppress that the absorptivity of a solvent falls too much and a fleshiness falls. Further, in the present mold, since the average pore diameter of the alumina porous body constituting the mold is not excessively large as 0.54 μm or less, when producing a ceramic molded body by pressure casting using the mold, It can suppress that the raw material powder of a ceramic molded body penetrate | invades in the pore of a shaping | molding die, and clogging generate | occur | produces, and it can suppress that productivity falls resulting from this clogging.

(3) In the above mold, the average value of the ratio of the major axis to the minor axis of the particles of the alumina porous body may be 2.5 or less. According to the present mold, since the average value of the ratio of the major axis to the minor axis of the particles of the porous alumina body is 2.5 or less, the alumina particles become nearly spherical, so that the packing property of the alumina particles is increased, The alumina porous body constituting the mold becomes a dense body having a small pore diameter. Therefore, when producing a ceramic molded body by pressure casting using a mold, the pore diameter of the alumina porous body constituting the mold is likely to be smaller than the particle diameter of the raw material powder particles of the ceramic molded body, It can suppress that the raw material powder of a ceramic molded body penetrate | invades in the pore of a shaping | molding die, and clogging generate | occur | produces, and it can suppress that productivity falls resulting from this clogging.

(4) The manufacturing method of the shaping | molding die disclosed by this specification is poured into a shaping | molding die, pressing the mixture of ceramic powder, a dispersing agent, and water as a solvent, and making the said shaping | molding absorb the said solvent. In the method for producing a mold used for producing a ceramic molded body, a step of preparing an alumina raw material powder having a purity of 99 wt% or more, a step of molding the alumina raw material powder to produce an alumina molded body, And firing the alumina molded body to produce the mold. According to the manufacturing method of the present mold, the alumina porous body constituting the manufactured mold is an alumina porous body having a purity of 99 wt% or more. Therefore, according to the manufacturing method of the present mold, it is possible to prevent impurities from being mixed into the ceramic molded body manufactured by pressure casting using the mold, and to be manufactured. It is possible to manufacture a mold that can suppress a decrease in local quality (solidity, denseness, etc.) of the body.

(5) In the method for producing a mold, the alumina raw material powder may have an average particle size of 2 μm or less. According to the method for producing the mold, the average pore diameter of the alumina porous body constituting the mold to be produced can be made relatively small, and the pore size can be determined during pressure casting using the mold. A mold that can prevent clogging can be manufactured.

(6) The method for producing a ceramic molded body disclosed in the present specification includes a first step in which a mixture of ceramic powder, a dispersant, and water as a solvent is poured into the molding die while pressing, And a step of taking out the ceramic molded body formed in the mold. According to the method for producing a ceramic molded body, it is possible to produce a ceramic molded body in which mixing of impurities is suppressed and deterioration in local quality (solidity, denseness, etc.) is suppressed.

(7) In the method for producing a ceramic molded body, the ceramic powder may have an average particle diameter of 0.2 μm or less and a purity of 99.99% or more. In the method for producing a ceramic molded body, since the average particle size of the ceramic powder as a raw material is relatively small and the purity is relatively high, the produced ceramic molded body is fired to produce a ceramic sintered body. As a result, a high-performance ceramic sintered body can be obtained with respect to denseness, strength, and withstand voltage. Therefore, according to the method for manufacturing a ceramic molded body, a ceramic molded body (for example, a ceramic molded body for a part for a semiconductor manufacturing apparatus) that requires such high performance can be manufactured.

(8) In the method for manufacturing a ceramic molded body, the ceramic powder may be an alumina powder. According to the method for producing a ceramic molded body, a ceramic sintered body is produced by firing the produced ceramic molded body, thereby producing a ceramic sintered body having an extremely high withstand voltage (for example, withstand voltage of 250 kV / mm or more). A ligation can be obtained. Therefore, according to the method for manufacturing a ceramic molded body, a ceramic molded body (for example, a ceramic molded body for a part for a semiconductor manufacturing apparatus) that requires such a high withstand voltage can be manufactured.

(9) In the method for manufacturing a ceramic molded body, the ceramic molded body may be a molded body for a component for a semiconductor manufacturing apparatus. According to the method for manufacturing a ceramic molded body, a manufactured ceramic molded body is fired to produce a ceramic sintered body, thereby producing a semiconductor having an extremely high withstand voltage (for example, withstand voltage of 250 kV / mm or more). Device parts can be obtained.

  The technology disclosed in the present specification can be realized in various forms, for example, in the form of a forming die, a ceramic forming body, a forming die, a method for manufacturing a ceramic forming body, or the like. Is possible.

It is explanatory drawing which shows schematically the structure of the shaping | molding die 100 in this embodiment. It is a flowchart which shows an example of the manufacturing method of the shaping | molding die 100 in this embodiment. It is a flowchart which shows an example of the manufacturing method of a ceramic sintered compact. It is explanatory drawing which shows typically an example of the manufacturing method of a ceramic sintered compact. It is explanatory drawing which shows a performance evaluation result.

A. Embodiment:
A-1. Configuration of mold 100:
FIG. 1 is an explanatory diagram schematically showing the configuration of a mold 100 in the present embodiment. The mold 100 according to the present embodiment is a mold used for pressure casting molding, which is one of the ceramic molded body manufacturing methods (molding methods). In the pressure casting molding, a mixture (slurry) of raw material powder (ceramic powder in the case of manufacturing a ceramic molded body), a dispersant, and water as a solvent is poured into the molding die 100 while being pressurized. In this method, a molded body is produced (molded) by absorbing a solvent. Pressure casting is a secondary process because it can form a complex shape compared to other molding methods (for example, injection molding, press molding (CIP molding, etc.), gel cast molding, etc.). Since the organic component is extremely small and the solvent is absorbed, the drying step and the degreasing step can be shortened or omitted.

  In addition, the ceramic molded body manufactured using the shaping | molding die 100 of this embodiment becomes a ceramic sintered compact by baking after that. Such a ceramic sintered body is used, for example, as a component for a semiconductor manufacturing apparatus or an electronic component. That is, the ceramic molded body manufactured using the molding die 100 of the present embodiment is, for example, a molded body for a semiconductor manufacturing apparatus component or an electronic component. Examples of the semiconductor manufacturing apparatus component include a shaft, a tube, a susceptor ring, a ring, an arm, a dome, an electrostatic chuck, and a heater. Such a component for a semiconductor manufacturing apparatus is required to have high density, high strength, and high withstand voltage in order to withstand, for example, plasma used in the semiconductor manufacturing apparatus.

  As shown in FIG. 1, the mold 100 of the present embodiment includes an upper mold 110 and a lower mold 120. In a state where the upper mold 110 and the lower mold 120 are combined, a space SP is formed inside the mold 100. The lower mold 120 is formed with a through-hole 122 that allows communication between the outside of the mold 100 and the internal space SP. The through hole 122 is used as a slurry charging hole, as will be described later. In addition, it is preferable that the opening width on the inner side (space SP side) in the through hole 122 is wider than the opening width on the outer side (external side). With such a configuration, when the upper mold 110 and the lower mold 120 are removed and the ceramic molded body is taken out, the ceramic molded body can be prevented from being damaged at the portion of the through hole 122. Further, the shape of the space SP of the mold 100 is determined according to the shape of the ceramic molded body to be manufactured. For example, when manufacturing a disk-shaped ceramic molded body, the shape of the space SP of the mold 100 is also disk-shaped.

  The mold 100 of this embodiment is an alumina porous body mold formed of an alumina porous body. In the present embodiment, the mold 100 is formed of a highly porous alumina body having a purity of 99 wt% or more (that is, the content of impurities is extremely small).

  In addition, since the mold 100 of the present embodiment is formed of an alumina porous body having a purity of 99 wt% or more, as will be described later, the presence of impurities contained in the material when the mold 100 is manufactured (fired) As a result, the variation in pore diameter of the mold 100 is suppressed. For this reason, in the mold 100 of the present embodiment, the variation in pore diameter is small.

  Moreover, in this embodiment, the average pore diameter of the alumina porous body constituting the mold 100 is 0.09 μm or more and 0.54 μm or less. That is, in this embodiment, the average pore diameter of the alumina porous body constituting the mold 100 is neither too small nor too large. In this embodiment, the average value of the ratio of the major axis to the minor axis of the alumina porous body particles constituting the mold 100 is 2.5 or less. That is, in this embodiment, the alumina porous body particles constituting the mold 100 are not excessively elongated. Moreover, in this embodiment, the porosity of the alumina porous body which comprises the shaping | molding die 100 is 15% or more and 60% or less. Note that the porosity of the alumina porous body constituting the mold 100 is more preferably 40% or more and 60% or less.

A-2. Manufacturing method of mold 100:
Next, a method for manufacturing the mold 100 will be described. FIG. 2 is a flowchart showing an example of a method for manufacturing the mold 100 in the present embodiment.

  First, an alumina raw material powder having a purity of 99 wt% or more is prepared (S110). Examples of such extremely high-purity alumina raw material powder include TM-DAR manufactured by Daimei Chemical, AKP-30 manufactured by Sumitomo Chemical, AL-160SG-3 manufactured by Showa Denko, LS-11 manufactured by Nippon Light Metal, and the like. Can be used. The average particle size of the alumina raw material powder used is 2 μm or less, and the average value of the ratio of the major axis to the minor axis of the alumina raw material powder particles used is 2.5 or less.

  Next, the alumina raw material powder is molded to produce an alumina molded body for the mold 100 (S120). The alumina raw material powder is molded by, for example, a cold isostatic pressing method (CIP molding method).

  Next, the alumina molded body for the mold 100 is fired to produce the mold 100 which is an alumina sintered body (S130). The firing temperature at this time is set to 1200 ° C to 1500 ° C.

  By the above manufacturing method, the mold 100 having the above-described configuration is manufactured. As described above, since the alumina raw material powder having a purity of 99 wt% or higher is used in the present manufacturing method, the alumina porous body constituting the mold 100 to be manufactured is an alumina porous body having a purity of 99 wt% or higher. Moreover, in this manufacturing method, since alumina raw material powder with a purity of 99 wt% or more is used, a reduction in uniformity of sintering due to the presence of impurities contained in the material is suppressed during firing (S130), and molding is performed. Variation in the pore diameter of the mold 100 is suppressed.

  Moreover, in this manufacturing method, since the average particle diameter of the alumina raw material powder is 2 μm or less, the average pore diameter of the alumina porous body constituting the mold 100 to be manufactured is relatively small (for example, 0.54 μm or less). Become). Further, in this production method, since the average value of the ratio of the major axis to the minor axis of the alumina raw material powder particles is 2.5 or less, the major axis to the minor axis of the alumina porous body particles constituting the mold 100 to be produced The average value of the ratio is 2.5 or less.

A-3. Manufacturing method of ceramic sintered body:
Next, a method for manufacturing a ceramic sintered body will be described. FIG. 3 is a flowchart showing an example of a method for producing a ceramic sintered body. Also. FIG. 4 is an explanatory view schematically showing an example of a method for producing a ceramic sintered body. In the method for manufacturing a ceramic sintered body according to the present embodiment, a ceramic molded body (more specifically, an alumina molded body) is manufactured using a molding die 100, and then the ceramic molded body is fired to obtain a ceramic sintered body ( More specifically, this is a method for producing an alumina sintered body. That is, the method for producing a ceramic sintered body includes a method for producing a ceramic molded body (molding method).

  First, alumina powder (an example of ceramic powder), a dispersant, and a solvent (water) are stirred and mixed to produce a slurry SL that is a mixture of these (S210). As the alumina powder, for example, one having an average particle diameter (primary particle diameter) of 0.2 μm or less and a purity of 99.99% or more is used. As such alumina powder, for example, TM-DAR manufactured by Daimei Chemical Industry can be used. As the dispersant, for example, A-6114 manufactured by Toagosei Co., Ltd. can be used.

  Next, the slurry SL is poured into the mold 100 while being pressurized (S220). In the upper part of FIG. 4, the state where the slurry SL flows from the container 210 containing the slurry SL into the space SP in the molding die 100 through the pipe 220 and the through hole 122 formed in the lower die 120. It is shown. The pressurizing pressure at this time is, for example, about 0.1 MPa to 1.0 MPa. Further, after completion of pouring, the pressurized state is maintained for a predetermined time. The predetermined time at this time is set according to the size of the molded body, and is, for example, about 1 minute to 1 hour.

  After the predetermined time has elapsed, the ceramic molded body 310 formed in the mold 100 is taken out from the mold 100 (S230). Thereafter, if necessary, a portion (not shown) corresponding to the through hole 122 is removed from the ceramic molded body 310 to adjust the shape. The middle part of FIG. 4 shows a ceramic molded body 310 from the mold 100. The ceramic molded body 310 is manufactured by the manufacturing method so far.

  Next, the manufactured ceramic molded body 310 is fired to produce a ceramic sintered body 320 (S240). The ceramic sintered body 320 is manufactured by the above manufacturing method. The ceramic sintered body 320 is, for example, a semiconductor manufacturing apparatus component or an electronic component. The middle part of FIG. 4 shows a ceramic sintered body 320 obtained by firing the ceramic molded body 310. In general, due to shrinkage due to firing, the size of the ceramic sintered body 320 is smaller than that of the ceramic molded body 310.

A-4. Effects of this embodiment:
(Regarding the mold 100)
As described above, the mold 100 of the present embodiment causes the mold 100 to absorb the solvent by pouring the mixture (slurry SL) of ceramic powder, a dispersant, and water as a solvent into the mold 100 while applying pressure. Thus, the ceramic molded body 310 is used for manufacturing. The mold 100 is formed of an alumina porous body having an alumina purity of 99 wt% or more and a porosity of 15% or more and 60% or less. That is, the mold 100 is formed of an alumina porous body having an extremely high purity (that is, an impurity content is extremely small). Therefore, according to the mold 100 of the present embodiment, when the ceramic molded body 310 is manufactured by pressure casting using the mold 100, impurities are prevented from being mixed into the manufactured ceramic molded body 310. It can suppress that the quality of the ceramic compact 310 falls. In addition, according to the mold 100 of the present embodiment, it is possible to suppress the porosity from becoming excessively low, so that the water absorption of the mold 100 becomes excessively low and pressure casting using the mold 100 is performed. It can suppress that the inking property in the case of shaping | molding falls.

  In addition, since the mold 100 of the present embodiment is formed of an alumina porous body having a purity of 99 wt% or more, it is caused by the presence of impurities contained in the material when the mold 100 is manufactured (fired). Occurrence of variation in sinterability is suppressed, and as a result, variation in pore diameter is reduced. Therefore, according to the mold 100 of the present embodiment, when the ceramic molded body 310 is manufactured by pressure casting using the mold 100, variation in the absorbability of the solvent in the slurry SL can be suppressed. As a result, it is possible to suppress a decrease in local quality (solidity, denseness, etc.) of the ceramic molded body 310 to be manufactured.

  Moreover, in the shaping | molding die 100 of this embodiment, the average pore diameter of the alumina porous body which comprises the shaping | molding die 100 is 0.09 micrometer or more and 0.54 micrometer or less. As described above, in the mold 100 of the present embodiment, the average pore diameter of the alumina porous body constituting the mold 100 is not excessively small as 0.09 μm or more. Therefore, the ceramic is obtained by pressure casting using the mold 100. When manufacturing the molded object 310, it can suppress that the absorptivity of the solvent in slurry SL falls too much, and a fleshiness falls. Further, in the molding die 100 of the present embodiment, the average pore diameter of the alumina porous body constituting the molding die 100 is not excessively large, 0.54 μm or less. Therefore, the ceramic molded body is formed by pressure casting using the molding die 100. When manufacturing 310, it can suppress that the raw material powder of the ceramic molded object 310 penetrate | invades in the pore of the shaping | molding die 100, and clogging generate | occur | produces, Productivity falls resulting from this clogging. This can be suppressed.

  In the mold 100 of this embodiment, the average value of the ratio of the major axis to the minor axis of the alumina porous body particles constituting the mold 100 is 2.5 or less. Therefore, according to the molding die 100 of the present embodiment, since the average value of the ratio of the major axis to the minor axis of the alumina porous body particles is 2.5 or less, the alumina particles become nearly spherical. Fillability becomes high, and the pore diameter of the alumina porous body constituting the mold 100 can be made relatively small (for example, 0.54 μm or less). Therefore, when the ceramic molded body 310 is manufactured by pressure casting using the molding die 100, the pore diameter of the porous alumina body constituting the molding die 100 is determined from the particle diameter of the raw material powder particles of the ceramic molded body 310. The material powder of the ceramic compact 310 can be prevented from entering the pores of the mold 100 and causing clogging, and the productivity is prevented from being reduced due to the clogging. can do.

(Regarding the manufacturing method of the mold 100)
Further, as described above, the method for manufacturing the mold 100 according to the present embodiment is to pour a mixture (slurry SL) of ceramic powder, a dispersant, and water as a solvent into the mold 100 while applying pressure to the mold 100. It is a manufacturing method of the shaping | molding die 100 used in order to manufacture the ceramic molded object 310 by making a solvent absorb. This manufacturing method includes a step of preparing an alumina raw material powder having a purity of 99 wt% or more (S110), a step of forming an alumina raw material powder to produce an alumina molded body for the molding die 100, and a molding die 100 A step (S130) of firing the alumina molded body and producing the mold 100. Therefore, according to the method for manufacturing the mold 100 of the present embodiment, the alumina porous body constituting the mold 100 to be manufactured becomes an alumina porous body having a purity of 99 wt% or more. Therefore, according to the method for manufacturing the mold 100 of the present embodiment, it is possible to prevent impurities from being mixed into the ceramic molded body 310 manufactured by pressure casting using the mold 100, and Thus, it is possible to manufacture the mold 100 that can suppress the deterioration of local quality (solidity, denseness, etc.) of the ceramic molded body 310 to be manufactured.

  Moreover, in the manufacturing method of the shaping | molding die 100 of this embodiment, the average particle diameter of an alumina raw material powder is 2 micrometers or less. Therefore, according to the method for manufacturing the mold 100 of the present embodiment, the average pore diameter of the porous alumina body constituting the mold 100 to be manufactured can be made relatively small (for example, 0.54 μm or less). it can. Therefore, according to the method for manufacturing the mold 100 of the present embodiment, it is possible to manufacture the mold 100 in which the occurrence of clogging of pores is suppressed during the pressure casting using the mold 100. .

  As described above, in the method for manufacturing the mold 100 of the present embodiment, the firing temperature is 1200 ° C. or higher. Therefore, it can suppress that a non-sintered part generate | occur | produces resulting from baking temperature becoming low too much. As a result, in the manufactured mold 100, the presence of the sintered portion and the unsintered portion can prevent the strength from decreasing and the variation in pore diameter from increasing. Moreover, as mentioned above, in the manufacturing method of the shaping | molding die 100 of this embodiment, a calcination temperature shall be 1500 degrees C or less. Therefore, generation | occurrence | production of the oversintered part (part which abnormally grain-growth) resulting from baking temperature becoming high too much can be suppressed. As a result, in the manufactured mold 100, the (suitable) sintered portion and the oversintered portion coexist to suppress a decrease in porosity and a large variation in pore diameter. be able to. Therefore, according to the manufacturing method of the molding die 100 of the present embodiment, the molding die 100 having a small variation in pore diameter can be manufactured, and the ceramic molded body 310 is manufactured by pressure casting using the molding die 100. In this case, it is possible to suppress the variation in the absorbability of the solvent in the slurry SL, and as a result, it is possible to suppress a decrease in local quality (solidity, denseness, etc.) of the produced ceramic molded body 310. Can do.

(Regarding the method for producing the ceramic molded body 310)
As described above, the method for manufacturing the ceramic molded body 310 according to the present embodiment pressurizes a mixture (slurry SL) of ceramic powder, a dispersant, and water as a solvent to the mold 100 according to the present embodiment. A pouring step (S220), and a step (S230) for removing the ceramic molded body 310 formed in the mold 100 after the step S220. Therefore, according to the method for manufacturing the ceramic molded body 310 of the present embodiment, the ceramic molded body 310 in which the mixing of impurities is suppressed and the deterioration of local quality (solidity, denseness, etc.) is suppressed. Can be manufactured.

  In the method for manufacturing the ceramic molded body 310 of the present embodiment, the ceramic powder as the raw material has an average particle size of 0.2 μm or less and a purity of 99.99% or more. Thus, in the manufacturing method of the ceramic molded body 310 of this embodiment, since the average particle diameter of the ceramic powder as a raw material is relatively small and the purity is relatively high, the manufactured ceramic molded body 310 is fired. By manufacturing the ceramic sintered body 320, a high-performance ceramic sintered body 320 can be obtained with respect to denseness, strength, and withstand voltage. Therefore, according to the manufacturing method of the ceramic molded body 310 of the present embodiment, such a ceramic molded body 310 (for example, a ceramic molded body for a semiconductor manufacturing apparatus or an electronic component) that requires high performance is manufactured. can do.

  In the method for manufacturing the ceramic molded body 310 of the present embodiment, the ceramic powder as the raw material is an alumina powder. Therefore, according to the method for manufacturing the ceramic molded body 310 of the present embodiment, the ceramic molded body 310 is fired to produce the ceramic sintered body 320, so that the withstand voltage is extremely high (for example, the withstand voltage is high). A ceramic sintered body 320 (250 kV / mm or more) can be obtained. Therefore, according to the method for manufacturing the ceramic molded body 310 of the present embodiment, such a ceramic molded body 310 (for example, a ceramic molded body for a semiconductor manufacturing apparatus or an electronic component) that requires a high withstand voltage is used. Can be manufactured.

A-5. Performance evaluation:
Performance evaluation was performed about the shaping | molding die used for manufacture of the ceramic molded object by pressure casting. FIG. 5 is an explanatory diagram showing the performance evaluation results.

(About each sample)
As shown in FIG. 5, the molds of 15 samples (samples S1 to S15) were used for performance evaluation. The molding dies of the samples are different from each other in forming material and manufacturing method, and as a result, characteristics such as average pore diameter and porosity are different from each other.

  In samples S1 to S3, a hydrophilic resin material was used as a forming material for the mold. More specifically, the hydrophilic resin material was cut into a prismatic shape having a size of 60 mm × 60 mm × thickness 20 mm, and a concave portion having a size of 18 mm × 18 mm × depth 2.5 mm was provided at the center to produce a molding die. In sample S1, phenol resin (FL-FLE manufactured by Phutamura Chemical) is used as the hydrophilic resin material, and in sample S2, polyamide resin (TPS N66 manufactured by Toray Plastic Seiko Co., Ltd.) is used as the hydrophilic resin material. Then, PVA (polyvinyl alcohol) resin (Aion Beleater A) was used as the hydrophilic resin material.

  In sample S4, a porous metal material (Excelpore manufactured by Nippon Seisen) was used as the forming material of the mold. More specifically, a porous metal material was cut into 60 mm × 60 mm, and a concave portion having a size of 18 mm × 18 mm × depth 2.5 mm was provided in the center portion to produce a molding die.

  In sample S5, gypsum (special grade made by Yoshino gypsum) was used as the forming material of the mold. More specifically, 67 parts by weight of water is added to 100 parts by weight of gypsum, mixed for 9 minutes, poured into a container containing the original mold (18 mm × 18 mm × 2.5 mm thick prism), and left for 5 minutes. After being cured by this, by removing the original mold, a mold having a recess of 18 mm × 18 mm × depth 2.5 mm was produced.

  In samples S6 to S15, alumina was used as a forming material for the mold. More specifically, 150 g of alumina powder is weighed, and the weighed alumina powder is put into a mold (made of carbon) and pressed (pressure: 25 kN) by a press machine, and is a prismatic shape having a size of 60 mm × 60 mm × thickness 20 mm. Then, cold isostatic pressing (CIP molding) (pressure: 1.5 ton) was further performed. The produced molded body was put in an alumina sheath and fired (firing temperature: a temperature shown in FIG. 5 within a range of 1200 to 1500 ° C.) to produce a mold.

  In sample S6, TM-DAR (average particle size: 0.1 μm, purity 99.99% or more) manufactured by Daimei Chemical Industry was used as the alumina (referred to as “alumina (A)” in FIG. 5). In S7, AKP-30 manufactured by Sumitomo Chemical Co., Ltd. (average particle size: 0.3 μm, purity 99.99% or more) is used as alumina (indicated as “alumina (B)” in FIG. 5), and in samples S8 to S11, As an alumina, Showa Denko AL-160SG-3 (average particle size: 0.5 μm, purity: 99.5%) is used (referred to as “alumina (C)” in FIG. 5), and in samples S12 to S14, LS-11 (average particle diameter: 2 μm, purity: 99.8%) manufactured by Nippon Light Metal Co., Ltd. was used as alumina (referred to as “alumina (D)” in FIG. 5). In sample S15, AL-7 (average particle size: 0.5 μm, purity: 99.5%) manufactured by Sumitomo Chemical was used as the alumina as a raw material, and sintering aid was compared with 95.0 wt% of AL-7. As an agent, alumina having a purity of 95% to which 2.5 wt% of silica, 0.2 wt% of magnesia, 2.3 wt% of barium carbonate, and 5.0 wt% in total were added was used (referred to as "alumina (E)" in FIG. 5). .

  Thus, in samples S6 to S15, the average particle diameter of the alumina raw material powder used for the production of the mold was 2 μm or less. The average particle size of the alumina raw material powder is the smallest for the sample S6 (alumina (A)), the second for the sample S7 (alumina (B)), and the samples S8 to S11. The one used (alumina (C)) and the one used for sample S15 (alumina (E)) are the third smallest, and the one used for samples S12 to S14 (alumina (D)) is the largest. In addition, what was used for sample S12-S14 (alumina (D)) is the most excellent in terms of cost.

  Further, as shown in FIG. 5, the average pore diameter and the porosity of sample S5 using gypsum as a forming material of the mold and samples S6 to S15 using alumina as the forming material of the forming die are shown. It was measured. The average pore diameter is measured using a mercury porosimeter (Autopore IV manufactured by Shimadzu Corporation), and the porosity is measured by a sintered density by the Archimedes method, and the ratio of the difference between the relative density and the sintered density to the relative density. (Porosity calculation formula: (relative density−sintered density) / (relative density) × 100 (%)).

  In the samples S6 to S15 using alumina as the forming material of the mold, the average pore diameter and the porosity were generally low as compared with the sample S5 using gypsum as the forming material of the mold. . In samples S6 to S15, the average pore diameter of the alumina porous body constituting the mold was in the range of 0.09 μm to 0.54 μm. Further, among the samples S6 to S15 using alumina powder as the forming material of the mold, the average pore diameter was smaller and the porosity was lower as the average particle diameter of the alumina powder was smaller. Further, when samples of the same kind of alumina powder to be used were compared, the higher the firing temperature, the lower the porosity.

(Evaluation items and evaluation methods)
In this performance evaluation, a ceramic molded body is produced by performing pressure casting using a molding die of each sample, and evaluation is performed on the inking property, demolding property, resistance to cracking, and the degree of impurity contamination. went. In addition, the slurry as a forming material of the ceramic molded body was alumina powder (TM-DAR (average particle size: 0.1 μm, purity: 99.99% or more) of Daimei Chemical Industries: 500 g, ion-exchanged water: 206.79 g. The dispersant (A-6114 manufactured by Toa Gosei Co., Ltd.) was obtained by weighing 12.5 g, stirring and mixing, and the pressure casting was a recess provided in the center of the mold of each sample. This was performed by pouring the prepared slurry into (18 mm × 18 mm × depth 2.5 mm), where the pressure of pressurization was 0.3 MPa and the pressurization time was 5 minutes. The ceramic molded body produced from the mold was taken out.

  Regarding the inking property evaluation, a ceramic molded body could not be obtained, for example, when it was determined that the ceramic molded body had a shape by pressure casting and was judged to be acceptable (◯) and remained in slurry. The case was judged as rejected (x). In addition, when it was determined to be acceptable, the thickness of the flesh was measured using calipers.

  For demolding evaluation, it was determined that the ceramic molded body could be taken out from the mold (O), and the ceramic molded body could not be taken out from the mold. Judged. In addition, when the evaluation of the inking property was unacceptable (x), the demoldability evaluation was not possible (−).

  For the evaluation of resistance to cracking, press casting was performed 50 times, and when the mold was not cracked, it was judged as acceptable (O), and when the mold was cracked, it was rejected (X). Judged.

  For the impurity contamination evaluation, the appearance of the ceramic molded body taken out from the mold was visually observed, and the presence / absence of an impurity contamination location (colored location different from the ceramic ground color) from the mold was examined. Also, the location where impurities are mixed from the mold (location where elements contained in the mold are detected) is observed by SEM image observation or SEM-EDS analysis of the cross section of the ceramic sintered body obtained by firing the ceramic molded body. ) Was examined. When there was no impurity-contaminated portion, it was judged as acceptable (◯), and when there was an impurity-contaminated portion, it was judged as unacceptable (x).

  Samples judged as acceptable (◯) for all evaluation items are comprehensively judged as acceptable (○), and samples judged as failed (×) for at least one evaluation item are totally rejected. (X) was determined.

  For the sample S5 using gypsum as the forming material of the mold and the sample S13 using alumina as the forming material of the forming die, the ceramic formed body was fired (firing temperature: 1400 ° C.) to produce ceramics. A sintered body was prepared, and the withstand voltage was measured in accordance with the test method of “JIS C 2110 Dielectric strength of solid electrical material”.

(Evaluation results)
As shown in FIG. 5, in the evaluation of the inking property, the samples S1 to S3 and S11 were determined to be rejected (x). In Samples S1 to S3, although the normal resin is hydrophobic, a hydrophilic resin was used as the forming material of the mold, but it is considered that the mold did not absorb water and did not sink. In sample S11, alumina is used as the forming material of the mold, but its porosity is excessively low (7.1%), so that the mold has low water absorption and is not fleshed. Conceivable. On the other hand, the other samples (S4 to S10, S12 to S15) were determined to be acceptable (◯) for the inking property. Moreover, in these samples (S4 to S10, S12 to S15), the demoldability was also determined to be acceptable (◯). Thus, among the samples (S6 to S15) in which alumina is used as the forming material of the mold, the samples S6 to S10 and S12 to S15 that are determined to be acceptable (◯) for the inking property and the demolding property are used. The porosity of alumina was 15% or more and 60% or less.

  In addition, regarding the thickness of the sample, the samples S6 to S15 using alumina as the forming material of the mold were equal to or more than the sample S5 using gypsum as the forming material of the mold. In particular, the sample S7 had a very thick wall thickness even when compared with the sample S9 having the same porosity, and the pressure casting molding was possible in a short time. In this sample S7, since the average particle diameter (0.3 μm) of the alumina powder as the forming material of the mold is relatively small, the average pore diameter (0.09 μm) of the mold is relatively small. Therefore, in this sample S7, it is considered that the occurrence of clogging of the molding die is suppressed, the water absorption is increased, and good inking properties are obtained. On the other hand, among the samples using alumina as the forming material for the mold, the average particle diameter (2.0 μm) of the alumina powder as the forming material for the forming mold is relatively large. As a result, the average pore diameter (0.54 μm) In the samples S12 to S14 having a relatively large size, it is considered that the occurrence of clogging of the mold was not sufficiently suppressed as compared with the sample S7 and the like. When clogging occurs in the mold, there is a difference in density between the clogged part and the part that is not clogged. Therefore, the strength of the ceramic sintered body obtained by firing the produced ceramic compact In addition, the withstand voltage is considered to decrease, which is not preferable.

  Further, in the evaluation of the difficulty of cracking, the sample S5 was determined to be rejected (x). In this sample S5, it is considered that plaster with low strength is used as the forming material of the mold. On the other hand, in the other samples (S1 to S4, S6 to S14), it was determined that the cracking resistance was acceptable (◯).

  Further, in the impurity contamination evaluation, in sample S4, since a gray colored portion was observed by visual observation of the appearance of the ceramic molded body, it was determined as rejected (x) because an impurity contamination portion was present. In this sample S4, since a porous metal is used as a forming material of the mold, it is considered that the surface of the porous metal was peeled off and mixed into the ceramic molded body during pressure casting. Further, in sample S5, in the SEM image of the cross section of the ceramic sintered body, the presence of acicular particles having different components was recognized instead of a homogeneous structure. Moreover, it was confirmed by SEM-EDS analysis that the acicular particles contain calcium. Therefore, in sample S5, it was determined that the sample was rejected (x) because there was a portion where impurities were mixed. In this sample S5, since gypsum is used as the forming material of the mold, it is considered that calcium contained in the gypsum is mixed into the ceramic molded body during pressure casting. In sample S15, magnesium was confirmed by SEM-EDS analysis. In sample S15, there is a mixed crystal of unsintered alumina and a sintering aid, which is considered to be mixed in the ceramic. On the other hand, in the other samples (S6 to S14), it was determined that the impurity contamination was acceptable (◯).

  Moreover, in the withstand voltage evaluation, the sample S13 using alumina as the forming material of the mold showed a higher withstand voltage (withstand voltage of 250 kV / mm or more) than the sample S5 using plaster as the forming material of the forming mold. . In sample S13, since the mixing of impurities from the mold was effectively suppressed, it is considered that the withstand voltage was higher than that of sample S5 in which the mixing of impurities (such as calcium) from the mold occurred. In addition, when the ceramic sintered body formed by baking the ceramic molded body produced with the shaping | molding die of sample S13 was analyzed, it was confirmed that it is a favorable dense body whose maximum pore diameter is 2 micrometers.

  According to the performance evaluation described above, if the mold is formed of an alumina porous body having an alumina purity of 99 wt% or more and a porosity of 15% or more and 60% or less, the mold was used. When manufacturing a ceramic molded body by pressure casting, it is possible to prevent impurities from being mixed into the manufactured ceramic molded body, and to improve the local quality (solidity, It was confirmed that the reduction in the density and the like) can be suppressed.

  Moreover, by said performance evaluation, if the average pore diameter of the alumina porous body which comprises a shaping | molding die is 0.09 micrometer or more and 0.54 micrometer or less, it can suppress that the moldability of a shaping | molding die falls. At the same time, it has been confirmed that clogging of the mold can be suppressed.

  Moreover, if the average particle diameter of the alumina raw material powder used for manufacture of a shaping | molding die is 2 micrometers or less by said performance evaluation, the average pore diameter of the alumina porous body which comprises the shaping | molding die manufactured is made comparatively small ( For example, it was confirmed that the thickness could be 0.54 μm or less.

  Further, according to the above performance evaluation, if the firing temperature at the time of producing the mold is 1200 ° C. or more and 1500 ° C. or less, the variation in the pore diameter of the mold can be reduced, and pressurization using the mold It is possible to suppress variations in the absorbability of the solvent in the slurry when producing a ceramic body by casting, and as a result, local quality (solidity, denseness, etc.) of the produced ceramic body. It was confirmed that the decrease in the resistance can be suppressed.

  Further, according to the above performance evaluation, if the average particle size of the ceramic powder as a raw material of the ceramic molded body is 0.2 μm or less and the purity is 99.99% or more, the denseness, strength, and withstand voltage will be increased. It was confirmed that a ceramic molded body capable of obtaining a high-performance ceramic sintered body can be produced.

  Further, according to the above performance evaluation, if alumina powder is used as the ceramic powder that is a raw material of the ceramic molded body, a ceramic molded body capable of obtaining a ceramic sintered body having an extremely high withstand voltage can be manufactured. confirmed.

B. Variation:
The technology disclosed in the present specification is not limited to the above-described embodiment, and can be modified into various forms without departing from the gist thereof. For example, the following modifications are possible.

  The structure of the shaping | molding die 100 in the said embodiment is an illustration to the last, and can deform | transform variously. For example, in the above embodiment, the mold 100 is composed of two parts, the upper mold 110 and the lower mold 120, but the number of components of the mold 100 can be arbitrarily changed.

  In addition, characteristics of the alumina porous body constituting the mold 100 described in the above embodiment (average porosity, average value of ratio of major axis to minor axis of particles, etc.) and characteristics of the manufacturing method of the mold 100 ( The average particle size of alumina raw material powder, firing temperature, etc.) and the characteristics of the ceramic molded body 310 manufacturing method (type of raw material, average particle size, purity, etc.) are preferably provided, but not necessarily provided. .

  Moreover, the manufacturing method of the shaping | molding die 100 in the said embodiment and the manufacturing method of the ceramic molded object 310 are an example to the last, and can deform | transform variously.

100: Mold 110: Upper mold 120: Lower mold 122: Through hole 210: Container 220: Piping 310: Ceramic molded body 320: Ceramic sintered body

Claims (10)

In the molding die used for producing a ceramic molded body by pouring a mixture of ceramic powder, a dispersant and water as a solvent into a molding die while pressing, and absorbing the solvent in the molding die,
The alumina has a purity of 99 wt% or more and is formed of an alumina porous body having a porosity of 40% or more and 60% or less ,
The alumina porous body has an average pore diameter of 0.09 μm or more and 0.54 μm or less . The mold according to claim 1 , wherein
The average value of the ratio of the major axis to the minor axis of the particles of the alumina porous body is 2.5 or less. A method for producing a mold used for producing a ceramic molded body by pouring a mixture of ceramic powder, a dispersant and water as a solvent into a mold while pressurizing the mixture, and absorbing the solvent in the mold In
A step of preparing an alumina raw material powder having a purity of 99 wt% or more;
Forming the alumina raw material powder to produce an alumina compact,
Firing the alumina molded body to produce the mold; and
Equipped with a,
In the mold,
The alumina has a purity of 99 wt% or more, and is formed of an alumina porous body having a porosity of 40% or more and 60% or less,
An average pore diameter of the alumina porous body is 0.09 μm or more and 0.54 μm or less . In the manufacturing method of the shaping die according to claim 3 ,
The method for producing a mold, wherein the alumina raw material powder has an average particle size of 2 μm or less. In the method for producing a ceramic molded body,
A first step of pouring a mixture of ceramic powder, a dispersant and water as a solvent into the mold according to claim 1 or 2 while applying pressure;
After the first step, a step of taking out the ceramic molded body formed in the mold;
A method for producing a ceramic molded body, comprising: In the manufacturing method of the ceramic forming object according to claim 5 ,
The ceramic powder has an average particle size of 0.2 μm or less and a purity of 99.99% or more. In the manufacturing method of the ceramic molded body according to claim 5 or 6 ,
The method for producing a ceramic molded body, wherein the ceramic powder is an alumina powder. In the manufacturing method of the ceramic forming body according to any one of claims 5 to 7,
In the first step, the mixture is poured while being pressurized at 0.1 MPa to 1.0 MPa,
In the step of taking out the ceramic molded body formed in the mold, the ceramic molded body is taken out after holding the pressurized state for a predetermined time after the first step. Production method. In the manufacturing method of the ceramic molded body according to any one of claims 5 to 8,
The method for manufacturing a ceramic molded body, wherein the ceramic molded body is a molded body for a component for a semiconductor manufacturing apparatus. In the manufacturing method of the ceramic compact according to any one of claims 5 to 9,
The method for producing a ceramic molded body, wherein the ceramic molded body is a solid molded body.

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