JP2016175795A - Method for producing powder raw material, method for forming molded body, and molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a powder raw material which can reduce a difference between average particle diameters in a power raw material obtained from plural kinds of raw material powders and can improve a yield of a molded body obtained from the powder raw material, and to provide a method for forming a molded body and a molded body.SOLUTION: A method for producing a powder raw material includes: a raw material powder pulverizing step ST11 of individually pulverizing plural kinds of raw material powders to obtain plural kinds of the pulverized raw material powders; and a mixing step ST13 of mixing the plural kinds of the pulverized raw material powders to obtain a mixture of the plural kinds of the raw material powders.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a powder raw material manufacturing method, a molded body molding method, and a molded body. For example, a powder raw material manufacturing method and a molded body molding method capable of suitably molding a solid electrolyte cell used in a hydrogen sensor or the like. And a molded body.

Conventionally, a method of manufacturing a solid oxide fuel cell using nitrates of lanthanum (La), chromium (Cr) and calcium (Ca) has been proposed (see, for example, Patent Document 1). In this method of manufacturing a solid oxide fuel cell, a raw material powder slurry dissolved and mixed in water is dried and solidified, and the dried and solidified solid is pulverized by a ball mill. Then, the raw material powder obtained by pulverization is pyrolyzed to remove the nitric acid content, and the obtained pyrolyzed powder is pulverized and crystallized, and then a Si ₃ N ₄ ball mill is used. By controlling the particle size, the powder raw material of the interconnect portion of the solid oxide fuel cell is adjusted.

JP-A-5-166524

  However, when the raw material powders of a plurality of types of molding materials are mixed as in the method for manufacturing a solid oxide fuel cell described in Patent Document 1, the specific gravity and hardness differ for each raw material powder. In some cases, the average particle diameters of the raw materials do not fall within a predetermined range, and uniform mixing of the raw material powders is difficult. And when the raw material powder is not uniformly mixed and pulverized, the composition of the molded body obtained using the raw material powder is not uniform, and the crystal structure becomes the starting point of cracking of the molded body at the time of molding and after firing Defects may occur and the yield of the molded body may decrease.

  The present invention has been made in view of such circumstances, can reduce the difference in the average particle diameter in the powder raw material obtained from a plurality of types of raw material powder, the yield of compacts obtained from the powder raw material It is an object of the present invention to provide a powder raw material molding method, a molded body manufacturing method, and a molded body that can be improved.

  The powder raw material manufacturing method of the present invention includes a raw material powder pulverization step for individually pulverizing a plurality of types of raw material powders to obtain a plurality of types of raw material powders, and mixing the plurality of types of raw material powders after pulverization And a mixing step of obtaining a mixture of the plurality of types of raw material powders.

  According to the method for producing a powder raw material of the present invention, a plurality of types of raw material powders having different hardness and specific gravity are pulverized individually, so that the difference in average particle size of a plurality of types of raw material powders obtained from a plurality of types of raw material powders It is possible to reduce the defects of the crystal structure, which is the starting point of cracking after molding of the powder raw material and after firing, and to prevent cracking and cracking of the molded body. Further, since plural types of raw material powders having different hardness and specific gravity are individually pulverized, the mixing time of the pulverized raw material powders can be shortened. Thereby, the manufacturing method of a powder raw material can reduce the difference of the average particle diameter in the powder raw material obtained from multiple types of raw material powder, and can improve the yield of the compacts obtained from the powder raw material.

  In the powder raw material manufacturing method of the present invention, in the raw material powder pulverization step, it is preferable that the difference between the average particle sizes of the plurality of types of raw material powders after the pulverization is 50% or less. According to this method, the powder raw material manufacturing method has a difference of 50% or less in the average particle size of a plurality of types of raw material powders, so that the yield of compacts obtained from the powder raw material is further improved.

  In the method for producing a powder raw material of the present invention, a plurality of types of the pulverized raw material powders pulverized in the raw material powder pulverization step are classified, and the raw material powders having a difference in average particle size of 50% or less It is preferable to include a classification step. According to this method, the powder raw material manufacturing method has a difference of 50% or less in the average particle size of a plurality of types of raw material powders, so that the yield of compacts obtained from the powder raw material is further improved.

  In the method for producing a powder raw material of the present invention, in the raw material powder pulverization step, the plural types of raw material powders are obtained by using a pulverizing jig formed of the same raw material as the raw material powders. It is preferable to grind each. With this method, the powder raw material manufacturing method uses the same material as the raw material powder for the pulverizing jig used for pulverizing the raw material powder, so that foreign substances can be prevented from being mixed into the powder raw material.

  In the powder raw material manufacturing method of the present invention, in the mixing step, the plural types of raw material powders are mixed using a pulverizing jig formed of the raw material having the highest hardness among the plural types of raw material powders. It is preferable. According to this method, the powder raw material manufacturing method can efficiently mix the raw material powders, so that the mixing time of a plurality of types of raw material powders can be shortened.

  In the method for producing a powder raw material of the present invention, a first drying step for drying the mixture, a crushing step for crushing the mixture after drying, and a calcining step for calcining the mixture after crushing A pulverizing step of pulverizing the mixture after calcination, a second drying step of drying the pulverized mixture, and a classification step of classifying the mixture after pulverization and drying to obtain a powder raw material. It is preferable to include. By this method, the powder raw material manufacturing method reduces the difference in the average particle size of the raw material powder in the mixture after calcination, so the time required for pulverization of the mixture after calcination can be shortened, and the powder raw material It becomes possible to shorten the manufacturing time.

  The molding method of the molded body of the present invention is characterized in that the molded body is molded using the powder raw material obtained by the above-described method for producing a powder raw material.

  According to this molding method, a plurality of types of raw material powders having different hardness and specific gravity are individually pulverized, and the powder raw material in which the difference in the average particle diameter of each raw material powder is reduced is used. It is possible to reduce the defects of the crystal structure that becomes the starting point such as cracks at the time of molding and after firing, thereby preventing cracks and cracks in the molded body. Thereby, the shaping | molding method of a molded object can improve the yield of the molded object obtained from a powder raw material.

  The molded body of the present invention is obtained by the molding method of the molded body.

  According to this molded body, a plurality of types of raw material powders having different hardness and specific gravity are individually pulverized, and the powder raw material in which the difference in the average particle diameter of each raw material powder is reduced is used. Defects in the crystal structure that serve as starting points such as cracks during molding and after firing can be reduced, and cracks and cracks in the molded product can be prevented.

  According to the present invention, a method for producing a powder raw material that can reduce the difference in average particle diameter in the powder raw material obtained from a plurality of types of raw material powder, and that can improve the yield of the molded body obtained from the powder raw material, A molding method and a molded body of the molded body can be realized.

FIG. 1 is a flowchart of a method for producing a powder raw material according to an embodiment of the present invention. FIG. 2 is a flowchart showing an example of a method for producing a powder raw material according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a molding jig used in the molding method for a molded body according to an embodiment of the present invention. FIG. 4A is an explanatory diagram of the molding method of the molded body according to the present embodiment. FIG. 4B is an explanatory diagram of the molding method of the molded body according to the present embodiment. FIG. 4C is an explanatory diagram of the molding method of the molded body according to the present embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, it is not limited to each following embodiment, It can implement by changing suitably. Also, the following embodiments can be implemented in combination as appropriate. Moreover, the same code | symbol is attached | subjected to the component which is common in each embodiment, and duplication of description is avoided.

  FIG. 1 is a flowchart of a method for producing a powder raw material according to an embodiment of the present invention. As shown in FIG. 1, the powder raw material manufacturing method according to one embodiment of the present invention is pulverized in a raw material powder pulverization step ST11 and a raw material powder pulverization step ST11. A plurality of types of raw material powders, and a raw material powder classification step ST12 for obtaining a plurality of types of raw material powders after classification in which the difference in average particle diameter is set to a predetermined value (for example, 50% or less); A mixing step ST13 in which a plurality of types of raw material powders are mixed to obtain a mixed powder. The raw material powder classification step ST12 is not necessarily performed if the difference between the average particle diameters of the plurality of types of raw material powders obtained in the raw material powder grinding step ST11 is a predetermined value (for example, 50% or less). .

In the raw material powder pulverization step ST11, a plurality of types of raw material powders are individually pulverized by a pulverizer such as a ball mill to obtain a predetermined average particle size. The raw material powder is not particularly limited as long as it can be pulverized by a pulverizer, and examples thereof include SrCO ₃ , ZrO ₂ and YbO ₃ . In this raw material powder crushing step ST11, since plural types of raw material powders having different hardness and specific gravity are individually pulverized, the plural types of raw material powders can be pulverized and the mixing time can be shortened. It is possible to reduce the difference in the average particle diameter of the raw material powders as compared with the case of previously mixing and pulverizing.

  In the raw material powder pulverization step ST11, it is preferable to pulverize the plurality of types of raw material powders so that the difference between the average particle sizes of the plurality of types of raw material powders is 50% or less. Thereby, in the method for producing a powder raw material according to the present embodiment, the difference between the average particle diameters of a plurality of types of raw material powders is 50% or less, so that cracks at the time of molding the powder raw material and after firing, etc. The defects of the crystal structure that is the starting point of the above are further reduced to prevent cracking and cracking of the molded body, and the yield of the molded body obtained from the powder raw material is further improved. It is more preferable to grind so that the difference in the average particle diameters of the plural types of raw material powders is 25% or less, and it is more desirable to grind so that the difference is 10% or less. Further, in the raw material powder pulverization step ST11, plural types of raw material powders are pulverized using a pulverizer such as a ball mill having balls (grinding jigs) each formed of the same raw material as the raw material powder. It is preferable to do. Thereby, since the material of the crushing jig used for crushing the raw material powder is the same as that of the raw material powder, it is possible to prevent foreign matters from being mixed into the powder raw material. The pulverizing jig is not limited to a ball, and various pulverizing jigs capable of pulverizing the raw material powder are applicable. Moreover, in this invention, an average particle diameter is a value of a 50% diameter measured by the light diffraction scattering method by the laser beam based on JISZ8825 using a particle size distribution measuring apparatus.

  In the raw material powder classification step ST12, the plurality of types of raw material powders pulverized in the raw material powder pulverization step ST11 are each classified by a classifier such as a sieve, and the difference between the average particle sizes of the raw material powders is less than a predetermined value (for example, 50% or less). By carrying out the raw material powder classification step ST12 in this way, the difference in the average particle diameters of the plural types of raw material powders is 50% or less, so that the yield of compacts obtained from the powder raw material is further improved. .

  In the mixing step ST13, the pulverized raw material powders are mixed with a pulverizer such as a ball mill to obtain a mixed powder of the raw material powders having a difference in average particle size of 50% or less. In this mixing step ST13, it is preferable to mix a plurality of types of raw material powders using a ball (grinding jig) formed of a raw material having the highest hardness among the plurality of types of raw material powders. Thereby, since it becomes possible to mix raw material powder efficiently, the mixing time of multiple types of raw material powder can be shortened. The pulverizing jig is not limited to a ball, and various pulverizing jigs capable of pulverizing the raw material powder are applicable. Hereinafter, specific examples of the powder raw material manufacturing method according to the present embodiment will be described in detail.

  FIG. 2 is a flowchart showing an example of a method for producing a powder raw material according to an embodiment of the present invention. As shown in FIG. 2, in the method for producing a powder raw material according to the present embodiment, a first raw material powder pulverizing step ST111 for pulverizing a first raw material powder, and a second raw material powder pulverizing step ST112 for pulverizing a second raw material powder. And a raw material powder grinding step ST11 including a third raw material powder grinding step ST113 for grinding the third raw material powder, a first raw material powder classification step ST121 for classifying the ground first raw material powder, and the ground second raw material powder. The second raw material powder classification step ST122 for classifying and the raw material powder classification step ST12 including the third raw material powder classification step ST123 for classifying the pulverized third raw material powder, and the average particle size was classified so as to have a predetermined value, respectively. Mixing step ST13 in which the first raw material powder, the second raw material powder, and the third raw material powder are mixed to form a mixture, the first drying step ST14 for drying the mixture, and the mixture after drying Crushing step ST15 for crushing, calcining step ST16 for calcining the mixture after crushing, crushing step ST17 for crushing the mixture after calcining, and second drying step ST18 for drying the mixture after crushing And a classification step ST19 for classifying the dried mixture to obtain a powder raw material.

The powder material produced by the production method of the powder raw material according to the present embodiment, for _{example, SrZr 0.95 Yb 0.05 O 3,} CaZr 0.95 Yb 0.05 O 3, SrZr 0.95 _{Yb 0.05 O 3, CaZr 0.95 Al} 0.05 O 3, SrZr 0.95 Al 0.05 O 3, SrZr 0.95 In 0.05 O 3 and _SrZr 0.95 _{Sm 0.05} O ₃ Powder raw materials having various compositions can be obtained depending on the ratio of the first raw material powder, the second raw material powder, and the third raw material powder to be used, such as a compound obtained by doping Yb with a SrZrO ₃ perovskite type compound. In the present embodiment, an example will be described in which SrCO ₃ is used as the first raw material powder, ZrO ₂ is used as the second raw material powder, and YbO ₃ is used as the third raw material powder.

In the raw material powder pulverization step ST11, the first raw material powder pulverization step ST111 for pulverizing the first raw material powder SrCO ₃ with a pulverizer such as a ball mill for a predetermined time (for example, 5 hours) and the second raw material powder ZrO ₂ are performed. Second raw material powder pulverization step ST112 for pulverizing with a pulverizer such as a ball mill for a predetermined time (for example, 15 hours), and YbO ₃ as the third raw material powder is pulverized for a predetermined time (for example, 8 hours) with a pulverizer such as a ball mill. The third raw material powder grinding step ST113 is performed in parallel. In this way, the first raw material powder pulverization step ST111, the second raw material powder pulverization step ST112, and the third raw material powder pulverization step ST113 are carried out in parallel, so that the first raw material powder pulverization step ST111 and the second raw material powder pulverization step ST113 are performed. In contrast to the case where ST112 and the third raw material powder grinding step ST113 are sequentially performed, the working time of the raw material powder grinding step ST11 can be shortened according to the grinding time of ZrO ₂ having the highest hardness of the raw material powder. In the first raw material powder pulverization step ST111, it is preferable to pulverize the first raw material powder SrCO ₃ with a ball mill equipped with SrCO ₃ balls. In the second raw material powder pulverization step ST112, ZrO balls are used. preferably grinding the ZrO ₂ is a ball mill in the second raw material powder having, in the third raw material powder grinding step ST113, grinding the YbO ₃ is a third raw material powder by a ball mill having a ball made of YbO ₃ Is preferred. Accordingly, it is possible to prevent foreign matters from being mixed into the powder raw material obtained from the first raw material powder, the second raw material powder, and the third raw material powder.

In the raw material powder classification step ST12, the first raw powder SrCO ₃ is classified by a classifier such as a sieve so that the average particle diameter becomes a predetermined value (for example, 18.6 μm: 50% diameter). The raw material powder classifying step ST121 and the second raw material powder ZrO ₂ that has been pulverized are classified by a classifier such as a sieve so that the average particle diameter becomes a predetermined value (for example, 24.7 μm: 50% diameter). Raw material powder classification step ST122 and third raw material powder classification in which the average particle diameter is classified to a predetermined value (for example, 22.8 μm: 50% diameter) with a classifier such as a sieve of YbO ₃ as the third raw material powder. The process ST123 is performed in parallel. Thereby, the difference of the average particle diameter of a 1st raw material powder, a 2nd raw material powder, and a 3rd raw material powder can be made into predetermined value (for example, 50% or less). In the raw material powder classification step ST12, if the first raw material powder, the second raw material powder, and the third raw material powder can be pulverized into raw material powders each having an average particle size of a predetermined value or less in the above-described raw material powder pulverization step ST11, It is not always necessary to implement it.

  The range of the average particle diameter (50% diameter) of each raw material powder of the first raw material powder, the second raw material powder and the third raw material powder obtained after the raw material powder grinding step ST11 and the raw material powder classification step ST12 is, for example, 10 m or more The thickness is preferably 50 μm or less. By setting the average particle diameter (50% diameter) of each raw material powder in the range of 10 m to 50 μm, the average particle diameter in the powder raw material obtained from the first raw material powder, the second raw material powder, and the third raw material powder The difference can be reduced, and the yield of the molded body obtained from the powder raw material can be improved. The range of the average particle diameter (50% diameter) of each raw material powder is more preferably 12.5 m or more and 40 μm or less, and further preferably 15 m or more and 30 μm or less.

In the mixing step ST13, SrCO ₃ that is the first raw material powder, ZrO ₂ that is the second raw material powder, and the third raw material powder that are pulverized so that the difference in average particle diameter is equal to or less than a predetermined value in the raw material powder pulverizing step ST11. A slurry obtained by mixing YbO ₃ , an alcohol solvent such as ethanol, and a dispersant is mixed with a pulverizer such as a ball mill for a predetermined time (for example, 1 hour). In the mixing step ST13, the first raw material powder, the second raw material powder, and the third raw material powder whose difference in average particle size is equal to or less than a predetermined value are mixed in advance, so that the mixing operation can be completed in a short time. it can. Further, in this mixing step ST13, the raw material powder grinding step ST11 is not performed, and the first raw material powder SrCO ₃ , the second raw material powder ZrO ₂ , and the third raw material powder YbO ₃ are mixed with a ball mill or the like. Compared with the case of mixing while pulverizing with a pulverizer, it can be completed in a short time. Thereby, not only can the time be shortened (for example, 10 hours), but also the difference in the average particle diameter of the raw material powders can be efficiently reduced to a predetermined value or less.

In the mixing step ST13, it is preferable to use a ball mill including a ZrO ₂ ball having the highest hardness among the first raw material powder, the second raw material powder, and the third raw material powder. As a result, not only the first raw material powder, the second raw material powder and the third raw material powder can be mixed efficiently, but also the mixing of the ball components during the mixing of the first raw material powder, the second raw material powder and the third raw material powder is prevented. It is possible to prevent foreign substances from being mixed into the powder raw material and change in the composition of the raw material powder mixture.

  In the first drying step ST14, the mixture of the first raw material powder, the second raw material powder, and the third raw material powder is dried with a dryer such as an evaporator. In the crushing step ST15, the mixture dried in the first drying step ST14 is crushed with a mortar or the like. In the calcination step ST16, the mixture of the first raw material powder, the second raw material powder, and the third raw material powder crushed in the crushing step ST15 is held at a predetermined temperature (for example, 1250 ° C.) for a predetermined time (for example, 5 hours). And calcine it.

In the pulverization step ST17, a slurry obtained by adding an alcohol solvent such as ethanol and a dispersant to the mixture of the first raw material powder, the second raw material powder, and the third raw material powder calcined in the calcining step ST16, for example, a ball mill or the like. Pulverize for a predetermined time (for example, 1 hour). In this pulverization step ST17, since the mixture of the first raw material powder, the second raw material powder, and the third raw material powder whose difference in average particle size is equal to or less than a predetermined value is used in advance, the raw material powder pulverization step ST11 is performed. Compared with the case where the mixture is pulverized without shortening, it can be completed in a short time, and the time can be shortened (for example, 10 hours). In the pulverization step ST17, it is preferable to use a ball mill including balls of ZrO ₂ having the highest hardness among the first raw material powder, the second raw material powder, and the third raw material powder. As a result, not only the first raw material powder, the second raw material powder and the third raw material powder can be mixed efficiently, but also the mixing of the ball components during the mixing of the first raw material powder, the second raw material powder and the third raw material powder is prevented. It is possible to prevent foreign matters from being mixed into the powder raw material and a change in the composition of the obtained powder raw material.

  In the second drying step ST18, for example, a mixture of the first raw material powder, the second raw material powder, and the third raw material powder that has been pulverized after calcination by a dryer such as an evaporator is dried. In the classification step ST19, the mixed powder of the first raw material powder, the second raw material powder and the third raw material powder after drying is classified by a classifier such as a sieve so that the average particle diameter becomes a predetermined value to obtain a powder raw material. .

  Next, a method for forming a molded body using the powder raw material obtained as described above will be described. FIG. 3 is a schematic cross-sectional view of a molding jig 1 used in the molding method of the molded body according to the present embodiment, and FIGS. 4A to 4C illustrate the molding method of the molded body according to the present embodiment. FIG. As shown in FIG. 3, the forming jig 1 according to the present embodiment includes a substantially cylindrical outer die 11 and a substantially cylindrical core 12 a formed so as to be able to be inserted into and removed from the outer die 11. A silicon rubber mold 13 provided between the inner mold 12 and the outer mold 11 and the core 12a of the inner mold 12 and provided with a powder inlet 13a for feeding a powder raw material as a raw material powder to be molded; And a silicon rubber lid 14 for closing the powder inlet 13a of the silicon rubber mold 13.

As shown in FIGS. 4A to 4C, in the molding method of the molded body according to the present embodiment, the silicon rubber lid 14 is removed and the powder raw material is fed into the silicon rubber mold 13 and the inner mold 12 from the powder inlet 13a. After filling the gap with the child part 12a, the silicon rubber cover 14 is used to cover it. Then, a powder raw material compact 10 is formed by firing a powder raw material that is molded by applying a predetermined water pressure (for example, 1.5 t / cm ² ) from the outside of the outer mold 11 at room temperature. Is obtained. Here, since the difference in average particle size of the first raw material powder, the second raw material powder, and the third raw material powder of the raw material powder to be used is a predetermined value or less, cracks and cracks in the molded body 10 during and after firing. Etc. can be prevented. Finally, the outer mold 11, the silicon rubber mold 13 and the silicon rubber lid 14 are removed from the molded body 10, and then the inner mold 12 is removed from the molded body 10, whereby the powder raw material molded body 10 is obtained. As the powder raw material molded body 10 obtained, for example, a solid electrolyte cell of a hydrogen sensor and a catalyst of a mixed material made of ceramics such as a denitration catalyst are obtained.

  As described above, according to the above-described embodiment, since multiple types of raw material powders having different hardness and specific gravity are individually pulverized, the average particle size of the multiple types of raw material powders obtained from the multiple types of raw material powders is reduced. It becomes possible to reduce the difference, and it is possible to reduce cracks and cracks in the molded body by reducing defects in the crystal structure that are the starting points such as cracks at the time of molding the powder raw material and after firing. Further, since plural types of raw material powders having different hardness and specific gravity are individually pulverized, the mixing time of the pulverized raw material powders can be shortened. Thereby, according to the said embodiment, the difference of the average particle diameter in the powder raw material obtained from multiple types of raw material powder can be reduced, and the improvement of the yield of the molded object obtained from a powder raw material is attained.

DESCRIPTION OF SYMBOLS 1 Molding tool 10 Molded body 11 Outer mold 12 Inner mold 12a Core part 13 Silicon rubber mold 13a Powder inlet 14 Silicon rubber lid

Claims (8)

A raw material powder grinding step for individually grinding a plurality of types of raw material powders to obtain a plurality of types of raw material powders after grinding,
And a mixing step of mixing the pulverized raw material powders to obtain a mixture of the raw material powders.   2. The method for producing a powder raw material according to claim 1, wherein in the raw material powder pulverization step, the difference between the average particle diameters of the plurality of types of raw material powders is adjusted to 50% or less.   2. The powder according to claim 1, further comprising a raw material powder classification step of classifying the plurality of types of raw powders after pulverization pulverized in the raw material powder pulverization step so that the difference in average particle diameter is 50% or less. A method for producing body materials.   The said raw material powder grinding | pulverization process WHEREIN: The said multiple types of raw material powder is each grind | pulverized using the grinding | pulverization jig | tool formed with the said raw material powder and the said multiple types of raw material powder, respectively. The manufacturing method of the powder raw material of any one.   The said mixing process WHEREIN: The said multiple types of raw material powder is mixed using the grinding jig | tool formed with the raw material with the highest hardness among the said multiple types of raw material powder. The manufacturing method of the powder raw material of description. A first drying step of drying the mixture;
A crushing step of crushing the mixture after drying;
A calcining step of calcining the mixture after pulverization;
Crushing step of crushing the mixture after calcination;
A second drying step of drying the mixture after pulverization;
A method for producing a powder material according to any one of claims 1 to 4, further comprising a classification step of classifying the mixture after pulverization and drying to obtain a powder material.   A method for molding a molded body, comprising molding a molded body using the powder raw material obtained by the method for producing a powder raw material according to any one of claims 1 to 6.   A molded product obtained by the molding method of the molded product according to claim 7.

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