JP2841177B2 - Method for producing uniform mixed powder, porous compact and powder impregnated compact by sublimation drying of slurry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a homogeneous mixed powder, a porous compact and a powder impregnated compact by solidifying a slurry of a powder and an organic solvent and then sublimating the organic solvent. .

[0002]

2. Description of the Related Art Conventionally, when producing a homogeneous mixture of two or more powders having different specific gravities, a high-viscosity polymer or the like is used as a slurry medium and the sedimentation speed of high specific gravity powder particles during wet mixing is controlled. I try to lower it. In addition, an evaporation method by heating is used as a removing agent for the slurry medium.
Further, when producing a porous molded body, mixing soluble particles or flammable particles in the raw material powder, kneading and molding,
It is known that finally, soluble particles or combustible particles are removed by an appropriate method.

Japanese Patent Application Laid-Open No. 60-51675 discloses that a pre-compressed fine metal wire mat is filled with molding powder in a space inside the mat, compression-molded, heated, sintered, and sintered. There is described a method for producing a porous molded body suitable for a bearing material having open pores by melting and flowing out a mat without lowering the strength of the molded body.

[0004]

When the particles having a high specific gravity are mixed by wet mixing, and the slurry medium is evaporated and removed after kneading, if the slurry is allowed to stand still, the concentration of the particles due to the difference in the sedimentation speed of the particles is reduced. Non-uniform precipitation occurs and the resulting dry powder is non-uniform. In addition, when casting is performed using a slurry of high specific gravity particles and the slurry medium is removed by evaporation, the particles settle, and a molded product having a uniform particle distribution (particle size distribution) cannot be obtained. Further, when the slurry is impregnated into a porous preform (preformed body) and the slurry medium is removed by evaporation after the impregnation, the impregnated slurry flows out of the preform, and impregnation efficiency is significantly reduced.

The present invention has been made in view of the above points. An object of the present invention is to use an organic solvent having a melting point near room temperature and having sublimability, such as α-terpineol, as a slurry medium liquid. Utilizing these properties of liquid,
After kneading the slurry at a temperature equal to or higher than the melting point of the organic solvent, the slurry is cooled to a temperature lower than the melting point of the organic solvent and solidified to freeze the distribution state of the particles (powder). It is an object of the present invention to provide a method for producing a homogeneous mixed powder, a porous compact, and a powder-impregnated compact by sublimating a slurry medium liquid while maintaining a reduced pressure atmosphere according to the above conditions.

[0006]

In order to achieve the above object, a method for producing a homogeneous mixed powder by sublimation drying of a slurry according to the present invention comprises the following steps (a) to (d), namely, (a) ) Melting point 10-60 ° C, boiling point 100-30
A step of kneading an organic solvent at 0 ° C. and at least two kinds of powders having different specific gravities at a temperature equal to or higher than the melting point of the organic solvent to prepare a uniform slurry; (b) mixing the organic solvent while kneading the uniform slurry; (C) charging the solidified slurry into a drier, maintaining the temperature below the melting point of the organic solvent, sublimating and removing the organic solvent, and agglomerated powder The process,
(D) a step of pulverizing the agglomerated powder into a uniform mixed powder. In the above method, it is preferable that the organic solvent is sublimated and removed under reduced pressure by using a dryer as a vacuum dryer in that the sublimation can be performed in a short time.

[0007] Of the above steps, the sublimation step is desirably performed at around room temperature.
° C, desirably 25 to 40 ° C, and the boiling point is 100 to 300.
° C, desirably 150 to 250 ° C, and vapor pressure is 100 to 4
00 mmHg, and the constituent elements are C, H, and O. As an organic solvent which is a slurry medium, α-terpineol (C ₁₀ H
₁₈ O, melting point 38-40 ° C, boiling point 219-221 ° C), 4
-Methoxybenzoic acid methyl ester (C ₉
H ₁₀ O _3), 2,6- di -tert- butyl-4-methylphenol _{(C 15 H 24 O),} 2,4- diisopropylphenol _{(C 12 H 18 O),} 1,1- diacetoxy ethane ( C ₆ H ₁₀ O ₄ ), octanoic acid (C ₈ H
₁₆ O ₂ ), dodecyl alcohol (C ₁₂ H ₂₆ O), 2-ethyl-2-butylpropane-1,3-diol (C ₉ H
₂₀ O ₂ ), oleic acid ethyl ester (C ₂₀ H
₃₈ O ₂ ), ethanol (C ₂ H ₆ O), 2,6-dimethylphenol (C ₈ H ₁₀ O), 4-propylphenol (C ₉ H ₁₂ O), 2-isopropylphenol (C ₉ H
₁₂ O), 4-ethylphenol _{(C 8 H 10 O),} 4- methylphenol _{(C 7 H 8 O),} 3,4- dimethylphenol (C ₈ H ₁₀ O), phenol (C ₆ H ₆ O) , cyclohexanol _{(C 6 H 12 O),} 2,4- dimethylphenol (C ₈ H ₁₀ O), propane-1,2,3-triol _{(C 3 H 8 O 3)} , 1- phenyl - propane -1
-One (C ₉ H ₁₀ O), 2-methoxyphenol (C ₇
H ₈ O _2), 2- methylphenol _{(C 7 H 8 O),} 3
- it can be exemplified methylphenol (C ₇ H ₈ O), and the like.

The method for producing a porous molded body by sublimation drying of a slurry according to the present invention comprises the following steps (a) to (c): (a) a melting point of 10 to 60 ° C. and a boiling point of 100 to 100 ° C.
Preparing a uniform slurry by kneading the organic solvent at 300 ° C. and the powder at a temperature equal to or higher than the melting point of the organic solvent;
(B) pouring a uniform slurry into a mold, cooling the mold to a temperature lower than the melting point of the organic solvent to solidify the slurry, and (c) taking out the solidified compact and mounting it in a dryer. And maintaining the temperature at or below the melting point of the organic solvent and sublimating and removing the organic solvent to form a porous molded body.

Further, as another example of the method for producing a porous molded body, the following steps (a) to (e), namely, (a)
A step of kneading an organic solvent having a melting point of 10 to 60 ° C. and a boiling point of 100 to 300 ° C. with a powder at a temperature equal to or higher than the melting point of the organic solvent to prepare a uniform slurry; (b) kneading the uniform slurry (C) a step of pulverizing the solidified slurry by cooling to a temperature equal to or lower than the melting point of the organic solvent, (d) a step of filling the pulverized solidified slurry into a mold, and press-forming ( e) removing the press-molded product from the mold, loading it into a dryer, maintaining the temperature below the melting point of the organic solvent, and sublimating and removing the organic solvent to form a porous molded body. is there. In these methods, it is preferable that the organic solvent is sublimated and removed under reduced pressure by using a dryer as a vacuum dryer in that the sublimation can be performed in a short time.

Further, the method for producing a powder-impregnated molded article by sublimation drying of the slurry of the present invention comprises the following steps (a) to (g):
(A) a step of kneading an organic solvent having a melting point of 10 to 60 ° C. and a boiling point of 100 to 300 ° C. and a powder at a temperature equal to or higher than the melting point of the organic solvent to prepare a uniform slurry; b) a step of solidifying the slurry by cooling to a temperature below the melting point of the organic solvent while kneading the uniform slurry, and (c) a step of pulverizing the solidified slurry.
(D) storing the pulverized solidified slurry together with the porous preform in a bag to form a package, and (e) charging the package in a heatable pressure vessel and heating it under pressure. (C) liquefying the solidified slurry again and impregnating the slurry in the preform, (f) after the impregnation, the package is rapidly cooled to a temperature equal to or lower than the melting point of the organic solvent, and the slurry impregnated in the preform is formed. Solidifying again,
(G) removing the pre-formed body from the bag, charging the pre-formed body into a drier, maintaining the temperature below the melting point of the organic solvent, and sublimating and removing the organic solvent to obtain a powder-impregnated formed body. And

In this method, it is preferable that the organic solvent is sublimated and removed under reduced pressure by using the dryer as a vacuum dryer in that the sublimation can be performed in a short time. Further, it is preferable that the pulverized solidified slurry be wrapped in a rubber sheet together with the porous preform, and then sealed in a vinyl bag to form a package.

[0012]

FIG. 1 shows an example of a method for uniformly mixing particles having a high specific gravity by solidifying a slurry medium and removing sublimation. For example, a metal powder and a ceramic powder are charged into an organic solvent, for example, α-terpineol (melting point: 38 to 40 ° C.) having a melting point of about 50 to 60 ° C., and using a kneading machine such as a pot mill 10 to obtain 50 to 60 ° C. The mixture is kneaded while maintaining the temperature before and after to prepare a uniform slurry. While kneading, the slurry is cooled to the melting point of α-terpineol or lower, preferably 30 ° C. or lower, to solidify the slurry. Next, the solidified slurry is charged into a vacuum dryer 12, heated to about 30 ° C. under reduced pressure by a heater 14 and left for several hours to obtain α.
-Sublimation and removal of terpineol. Pot mill 1
The powder solidified and agglomerated within 0 is pulverized to produce a uniform mixed powder. Although FIG. 1 shows a case where two kinds of powders having different specific gravities are uniformly mixed, it is of course possible to uniformly mix three or more kinds of powders having different specific gravities. In the method shown in FIG. 1, even if the difference in specific gravity of the powder is considerably large, the powder can be uniformly mixed. The aggregate obtained by sublimating and removing α-terpineol from the solidified slurry is extremely porous, and thus is very easily crushed.

FIG. 2 shows an example of a method for producing a porous compact by solidifying and molding a slurry and removing sublimation of a slurry medium. The powder is mixed with an organic solvent, for example, having a melting point of 5 or more.
The mixture is charged into α-terpineol at about 0 to 60 ° C. and kneaded using a kneader such as a pot mill 10 while maintaining the temperature at about 50 to 60 ° C. to produce a uniform slurry.
The slurry is poured into a casting mold 16, and the mold 16 is immediately cooled to a temperature lower than the melting point of α-terpineol, preferably lower than 30 ° C., to solidify the slurry. Then
The solidified molded body 18 is taken out, placed in the vacuum dryer 12, heated to about 30 ° C. under reduced pressure by the heater 14 and left for several hours to remove α-terpineol by sublimation to remove the porous molded body 18a. Is prepared. FIG. 2 shows the case where one type of powder is used, but it is of course possible to use two or more types of powder.

FIG. 3 shows another example of a method for producing a porous molded body. The powder is charged into an organic solvent, for example, α-terpineol at about 50 to 60 ° C. which is equal to or higher than the melting point, and is kneaded using a kneader such as a pot mill 10 while maintaining the temperature at about 50 to 60 ° C. Make a slurry. While kneading, the slurry is cooled to the melting point of α-terpineol or lower, preferably 30 ° C. or lower, to solidify the slurry.
Next, after the solidified slurry is pulverized, the pulverized solidified slurry is filled in a mold 20 and press-formed by a press 22. The press-formed body 24 is taken out of the mold 20, placed in the vacuum dryer 12, and heated to about 30 ° C. under reduced pressure.
And left for several hours to sublimate and remove α-terpineol to produce a porous molded body 24a. In FIG.
Although the case where one type of powder is used is shown, it is of course possible to use two or more types of powder. According to the method shown in FIGS. 2 and 3, a green molded body having a uniform pore distribution can be obtained. Further, the porosity and the pore distribution can be controlled by changing the amount and the concentration of α-terpineol.

FIG. 4 shows an example of a high efficiency impregnation method by slurry impregnation molding and sublimation removal of a slurry medium. The powder is charged into an organic solvent, for example, α-terpineol at about 50 to 60 ° C. which is equal to or higher than the melting point, and is kneaded using a kneader such as a pot mill 10 while maintaining the temperature at about 50 to 60 ° C. Make a slurry. While kneading, the slurry is cooled to the melting point of α-terpineol or lower, preferably 30 ° C. or lower, to solidify the slurry. Then, after the solidified slurry is pulverized, the pulverized solidified slurry 26 is wrapped in a plastic sheet such as a rubber sheet 30 together with a porous preform (preformed body) 28, and is vacuum-sealed in a plastic bag such as a vinyl bag 32. To form a vacuum package 34. This vacuum package 34 is charged into a heatable pressure vessel 36, and N ₂ gas or the like is supplied to supply ₂ to 20 kg /
cm ² G or so, preferably heating temperature, for example, about 50 to 100 ° C. between the melting point and the boiling point of the pressurized while α- terpineol about 5～15Kg / cm ² G, solidified slurry was again liquefied, The slurry is impregnated in the porous preform 28. Reference numeral 38 denotes a heater, and reference numeral 40 denotes a liquid (for example, water) for isostatic pressing. After completion of the impregnation, the package 34a is taken out of the pressure vessel 36 and the isostatic pressing liquid 40, and
The slurry is rapidly cooled to 0 ° C. or less, preferably to about 20 ° C., and the slurry impregnated in the porous preform 28 is solidified again. Next, the porous preform 28 is taken out of the vinyl bag and the rubber sheet, placed in the vacuum dryer 12, heated to about 30 ° C. under reduced pressure by the heater 14 and left for several hours to sublime α-terpineol. Then, the powder-impregnated molded body 28a is taken out. Since the powder 42 adheres to the surface of the powder-impregnated molded body 28a, the powder-impregnated molded body 28a is obtained by removing the powder 40.

In the method shown in FIG. 4, since the solidified and pulverized slurry is used, vacuum deaeration of the preform becomes possible, and the impregnation efficiency is improved. When immersing in a liquid slurry, the porous preform cannot be degassed. Also, by sublimating and removing the solidified slurry medium,
The outflow of the slurry from the preform is eliminated, and the impregnation efficiency is improved. When the slurry medium of the liquid slurry is removed by evaporation, the impregnated slurry flows out of the porous preform. By the method shown in FIG. 4, a ceramic composite suitable for a lining material of a gas turbine combustion chamber, a heat-resistant tile, and the like can be manufactured. FIG. 4 shows the case where one type of powder is used, but it is of course possible to use two or more types of powder.

[0017]

As described above, the present invention has the following effects. (1) In the method of claim 1 or 2, even if two or more powder slurries having a large specific gravity difference are used, a mixed powder having a uniform particle distribution can be obtained by sublimation removal of the slurry medium. (2) According to the method of the third, fourth and fifth aspects, a porous molded body having a uniform pore distribution can be obtained by sublimation removal of the slurry medium. (3) According to the method of the sixth, seventh and eighth aspects, a powder impregnated preform having a high powder impregnation rate can be obtained by sublimation removal of the slurry medium.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an example of a method for producing a homogeneous mixed powder by sublimation drying of a slurry of the present invention.

FIG. 2 is a system diagram showing an example of a method for producing a porous formed body by sublimation drying of a slurry of the present invention.

FIG. 3 is a system diagram showing another example of the method for producing a porous formed body by sublimation drying of the slurry of the present invention.

FIG. 4 is a system diagram showing an example of a method for producing a powder-impregnated molded body by sublimation drying of a slurry of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pot mill 12 Vacuum dryer 14 Heater 16 Casting mold 18 Solidified molded body 18a Porous molded body 20 Mold 22 Press 24 Press molded body 24a Porous molded body 26 Solidified slurry 28 Porous preform (preformed body) 28a Powder impregnated molded body 30 Rubber sheet 32 Vinyl bag 34 Vacuum package 36 Pressure vessel 38 Heater 40 Liquid for isostatic pressing 42 Powder

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shozo Okazaki 1-1, Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries, Ltd. Inside the Akashi factory (56) References JP-A-63-222081 (JP, A) JP-A-2-9432 (JP, A) Special Table 2-50303013 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 38/00 302 C04B 38/00 304 B01F 3 / 18 B28B 1/00 C04B 38/04

Claims (8)

(57) [Claims] 1. The following steps (a) to (d): (a) a melting point of 10 to 60 ° C. and a boiling point of 100 to 30;
A step of kneading an organic solvent at 0 ° C. and at least two kinds of powders having different specific gravities at a temperature equal to or higher than the melting point of the organic solvent to prepare a uniform slurry; (b) mixing the organic solvent while kneading the uniform slurry; (C) charging the solidified slurry into a drier, maintaining the temperature below the melting point of the organic solvent, sublimating and removing the organic solvent, and agglomerated powder The process,
(D) a step of pulverizing the agglomerated powder into a uniform mixed powder, the method comprising the steps of: 2. The method for producing a homogeneous mixed powder by sublimation drying of a slurry according to claim 1, wherein the dryer is a vacuum dryer, and the organic solvent is sublimated and removed under reduced pressure. 3. The following steps (a) to (c): (a) a melting point of 10 to 60 ° C. and a boiling point of 100 to 30;
(B) a step of kneading the organic solvent at 0 ° C. and the powder at a temperature equal to or higher than the melting point of the organic solvent to prepare a uniform slurry;
A step of injecting a uniform slurry into a mold, cooling the mold to a temperature equal to or lower than the melting point of the organic solvent to solidify the slurry, Maintaining the temperature below the melting point of the organic solvent and sublimating and removing the organic solvent to form a porous molded body. 4. The following steps (a) to (e): (a) a melting point of 10 to 60 ° C. and a boiling point of 100 to 30;
A step of kneading the organic solvent at 0 ° C. and the powder at a temperature equal to or higher than the melting point of the organic solvent to prepare a uniform slurry, (b)
Cooling the organic solvent to a temperature below the melting point of the organic solvent while kneading the uniform slurry to solidify the slurry; (c)
A step of pulverizing the solidified slurry, (d) a step of filling the pulverized solidified slurry in a mold and press-molding the mold,
(E) removing the press-formed product from the mold, charging the same in a dryer, maintaining the temperature at or below the melting point of the organic solvent, and removing the organic solvent by sublimation to form a porous molded body. A method for producing a porous molded body by sublimation drying of a slurry. 5. The method according to claim 3, wherein the dryer is a vacuum dryer, and the organic solvent is sublimated and removed under reduced pressure. 6. The following steps (a) to (g): (a) a melting point of 10 to 60 ° C. and a boiling point of 100 to 30;
A step of kneading the organic solvent at 0 ° C. and the powder at a temperature equal to or higher than the melting point of the organic solvent to prepare a uniform slurry, (b)
Cooling the organic solvent to a temperature below the melting point of the organic solvent while kneading the uniform slurry to solidify the slurry; (c)
A step of pulverizing the solidified slurry, (d) a step of storing the pulverized solidified slurry together with the porous preform in a bag to form a package, and (e) charging the package in a heatable pressure vessel. And heating under pressure to liquefy the solidified slurry again and impregnate the slurry into the preform. (F) After the impregnation, the package is rapidly cooled to a temperature equal to or lower than the melting point of the organic solvent. (G) taking out the preformed body from the bag, loading the preformed body in a dryer, maintaining the temperature below the melting point of the organic solvent, and sublimating and removing the organic solvent. A method for producing a powder-impregnated molded body by sublimation drying of a slurry, which comprises the step of forming a powder-impregnated molded body. 7. The method for producing a powder-impregnated compact by sublimation drying of a slurry according to claim 6, wherein the dryer is a vacuum dryer, and the organic solvent is sublimated and removed under reduced pressure. 8. The powder impregnation by sublimation drying of the slurry according to claim 6 or 7, wherein the pulverized solidified slurry is wrapped with a rubber sheet together with a porous preform, and is vacuum-sealed in a vinyl bag to form a package. A method for producing a molded article.