JP2000279796A - Powder manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a droplet discharging device by which fine droplets of uniform size can efficiently be discharged. SOLUTION: A micro pump method wherein on the upper surface of a pressurizing chamber 7, a piezoelectric/electrostrictive element 10 is provided, and deformation of the piezoelectric/electrostrictive element 10 is utilized to cause a change in the pressure in the pressurizing chamber 7, and by this change in the pressure, liquid introduced into the pressurizing chamber 7 from an introducing port 8 can be discharged from a discharge port 9 constituted of plural nozzles 9a, 9a is adopted. The pressurizing chamber 7 is shaped into a long- length cavity, and to the longitudinal direction in the long-length cavity shape, an introducing port 8 is installed in one end part, and the discharge port 9 consisting of the plural nozzles 9a is installed in the end part on the opposite side to the introducing port 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder manufacturing apparatus for obtaining, for example, a ceramic powder having a uniform particle size distribution by forming a liquid into fine droplets, and a droplet discharging apparatus for forming a liquid into fine droplets. . In the present invention, the term "ceramic powder" is a general term including a powder of a metal compound.

[0002]

2. Description of the Related Art For industrial mass production of ceramic powder, a wet or dry pulverizer or a spray-drying apparatus is known. A crusher is a device that crushes a lump of raw material into fine powders, and a spray drying device is a device that dries a sprayed liquid to form a solid having a size corresponding to the size of a droplet. is there.

[0003]

The powder produced by using a pulverizer has a large variation in particle size distribution. To obtain a uniform particle size within a desired range, the powder must be sieved after production. No. In spray drying equipment,
It is difficult to make droplets uniform with a sprayer of the spray type. Therefore, it is conceivable to make the particle size distribution uniform by using a droplet discharging means that always discharges a constant droplet. When the droplet discharging means is used, a plurality of droplet means are used in order to enhance the discharge capability of an appropriate amount of liquid, but the number is limited due to the space for mounting. Since the size of the droplets is fixed in the structure of the droplet discharging means, the droplets are operated at a high speed in order to increase the number of discharges. In addition, there is a case where liquid enemies that are continuously discharged are not separated from each other and are discharged as large droplets, so that there is a limit in increasing the operation speed. or,
In particular, when it is necessary to obtain a small particle size of several tens of μm or less, the ejection amount per droplet is reduced, and the ejection capability is significantly reduced.

[0004]

SUMMARY OF THE INVENTION The present invention aims at improving the discharge capability without impairing the uniformity of the particle size of droplets to be discharged, particularly the fine particle size.
A droplet discharging means having a plurality of nozzles; and a heat treatment means for heating micro droplets discharged from the droplet discharging means, wherein a liquid serving as a precursor of the ceramic material is minutely discharged by the droplet discharging means. A powder manufacturing apparatus for manufacturing ceramic powder by subjecting the liquid to droplets and then performing heat treatment by the heat treatment means, a pressurized chamber having an inlet for liquid introduction and a discharge outlet for liquid discharge, Pressurizing means for intermittently applying pressure to the chamber to cause a volume change, wherein the discharge port is provided in a droplet discharge device in which a plurality of nozzles are set for one pressurized chamber. .

The droplet discharging means includes a pressurizing chamber having an inlet for introducing a liquid, a discharging port for discharging the liquid, a liquid introducing chamber into the pressurizing chamber, and a pressurizing chamber. In order to discharge the liquid in the chamber, a micropump having pressure means for applying intermittent pressure to the pressure chamber to cause a change in volume can be employed. A micropump that causes a pressure change in the pressurized chamber by utilizing the distortion of a piezoelectric / electrostrictive element provided on a part of a wall in the chamber, and discharges the liquid in the pressurized chamber from a nozzle by the pressure change. Thus, the pressure chamber and the nozzle can be formed of zirconia ceramics.

Further, the pressurizing chamber has a long cavity shape, and has an inlet at one end with respect to the longitudinal direction, and a discharge port comprising a plurality of nozzles at the other end. Or an extrusion chamber that communicates with the pressurized chamber,
All the nozzles are connected at their centers in a concentric area equal to half the radius of the bottom surface of the extrusion chamber, or form an elongated cavity, and are introduced at the center in the longitudinal direction. Mouth, or provided with a discharge port consisting of a plurality of nozzles at both ends, consisting of a long cavity, a discharge port provided with a plurality of nozzles at the center in the longitudinal direction,
An inlet can be provided at each end.
The nozzle sets the sum of the cross-sectional areas of the openings so as to be in a range of 1.5 to 0.67 times the area of the inlet opening, and connects the inlet and the outlet with the liquid flow. It is desirable to have a tapered shape whose sectional area gradually decreases in the direction.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A powder producing apparatus and a droplet discharging apparatus according to the present invention will be described with reference to the drawings. FIG. 1 shows a powder production apparatus, and 1 is an external heater 1a, 1 for heating.
The heating furnace 1 is connected to an air inlet 2 at an upper portion of the heating furnace 1 and to an air outlet 3 at a lower portion thereof. Is provided with a powder recovery box 4, and a plurality of liquids for intermittently discharging droplets into the heating furnace 1 via electromagnetic shutters 5 and 5 near the connection with the air introduction port 2. Droplet discharging devices 6 and 6 as drop discharging means are provided.

As shown in FIG. 2, the droplet discharge device 6 is formed by stacking green sheets made of zirconia ceramics in three layers and integrally firing them, and forms a window formed by cutting out an intermediate sheet. A pressurizing chamber 7 is formed, and an inlet 8 and a discharge port 9 are provided on the lower surface of the pressurizing chamber 7, and by mounting a voltage / electrostrictive element 10 on the upper surface, the piezoelectric / electrostrictive A micro-pump is constructed in which a pressure change is induced in the pressurizing chamber 7 by using the distortion of the element 10, and the liquid introduced into the pressurizing chamber 7 from the inlet 8 can be discharged from the discharge port 9 by the pressure change. Have been.

The pressurizing chamber 7 has a long cavity shape, the inlet 8 is at one end in the longitudinal direction of the long cavity shape, and the discharge port 9 is a long cavity. The discharge port 9 is located at the other end with respect to the longitudinal direction of the cavity shape, and has two nozzles 9a, 9a.

Next, an embodiment in which a powder of zirconia ceramics is formed using the powder manufacturing apparatus formed as described above will be described. The inlet 8 of the droplet discharge device 6 is connected to a tank (not shown) of an ethyl alcohol solution of zirconium chloride, which is a precursor of zirconia ceramics,
A voltage is intermittently applied to the voltage / electrostrictive element 10, and the deformation of the voltage / electrostrictive element 10 causes a pressure change in the pressurizing chamber 7. The pressure change causes the zirconium chloride ethyl alcohol in the tank to change. The solution is introduced into the pressure chamber 7, and the introduced ethyl alcohol solution of zirconium chloride is ejected from the nozzles 9 a and 9 a as minute droplets, and the ejected droplets are intermittently passed through the electromagnetic shutter 5. It is sent into the heating furnace 1. The water droplets sent into the heating furnace 1 are instantaneously evaporated in the heating furnace 1 and remain as zirconia ceramic powders. Collect in 4.

As described above, since innumerable fine droplets are ejected through the two nozzles 9a, 9a, zirconia ceramic powder, which is a fine and uniform particle size ceramic powder, can be efficiently and in a short time. Can be obtained in large quantities. By the way, the powder obtained by using the present apparatus in which the droplet discharging means is constituted by a micropump has a particle size of 10 to 180 μm.
m, it was confirmed that the particle size distribution was within ± 10% of the average particle size.

The droplet discharge device used in the above-mentioned powder production apparatus is formed by stacking green sheets made of zirconia ceramics in three stages and integrally firing, so that the pressure chamber and the nozzle are also made of zirconia ceramics. It is excellent in chemical resistance, heat resistance, toughness and the like, and can be applied even when a liquid such as an acetone-based or hydrochloric acid-based liquid is used. Also, the pressurizing chamber has a long cavity shape,
The introduction port is provided at one end with respect to the longitudinal direction in the elongated cavity shape, and the ejection port composed of a plurality of nozzles is provided at the other end, so that the introduction port, the pressure chamber, and the ejection port are liquid. In combination with the use of zirconia ceramics with good wettability, the liquid can smoothly pass from the introduction port to the discharge port, causing bubbles to adhere on the way, resulting in poor discharge. Can be avoided.

The droplet discharge device used in the above-mentioned powder production apparatus has a discharge port formed of two nozzles.
As shown in FIG. 3, the discharge port 9 has three nozzles 9a, 9a,
9a or more nozzles, and as shown in FIG.
a, 8a (The drawing shows a case composed of three through holes)
Can also be configured. Increasing the number of nozzles increases the discharge amount. If the introduction port is formed of a plurality of through holes, the introduction amount increases, and the discharge efficiency also improves.

As shown in FIG. 5, the discharge port 9 is provided with an extruding chamber 11 communicating with the pressurizing chamber 7, and the center of each nozzle 9a, 9a with respect to the bottom surface in the extruding chamber 11. It is possible to form a structure (see FIG. 6) connected in a concentric region equal to a half of the radius on the bottom surface of the eleventh embodiment. By doing so, the liquid that has passed through the central portion of the extrusion chamber 11 that is not easily affected by the viscous resistance is sent to the nozzles 9a, 9a, so that the droplets are smoothly discharged. Further, the introduction port and the discharge port are not only separately arranged at both ends in the longitudinal direction of the elongated cavity shape, but also, as shown in FIG. May be provided with discharge ports 9, 9 each having one nozzle 9a at each end, and conversely, as shown in FIG. 8, a plurality of nozzles 9a, 9a. It is also possible to provide the discharge port 9 provided with the inlet port 8 at both ends. In addition, when the introduction port is disposed at the center and the discharge ports are disposed at both ends as shown in FIG. 7, since the distance between each nozzle can be increased,
That the ejected droplets can be prevented from interfering with each other,
This has the advantage that the liquid can be smoothly introduced into the pressurized chamber. Further, as shown in FIG. 8, when a discharge port including a plurality of nozzles is formed at the center and inlets are formed at both ends, there is an advantage that a pressure change in the pressurized chamber can be efficiently used for discharge.

In the case where neither the discharge port nor the introduction port has a shutoff mechanism such as a valve, the liquid tends to be discharged from both the discharge port and the introduction port due to a change in the pressure of the pressurizing chamber.
At the time of discharge, it is necessary to efficiently discharge from the discharge port, and at the time of introduction, the liquid must be introduced only from the introduction port. Therefore, the introduction port and the discharge port, the sum of the cross-sectional area of the nozzle opening according to the arrangement of the introduction port and the discharge port, the number of through-holes constituting the introduction port and the number of nozzles constituting the discharge port, etc. 1.5 to 0.6 with respect to the area of the opening
The discharge efficiency can be optimized by setting the range to be seven times as large. Further, as shown in FIG. 9, if the inlet 8 and the nozzles 9a constituting the discharge port 9 are tapered so that the cross-sectional area gradually decreases in the flow direction of the liquid, The fluid resistance in the flowing direction decreases and increases in the reverse direction, so that not only the efficiency of liquid introduction and discharge can be increased, but also a backflow prevention effect can be expected.

The above-mentioned powder production apparatus heats the discharged liquid as it is to produce a ceramic powder. However, the discharged liquid is once subjected to a reaction treatment in a reaction tank and then heated. Can also be. Next, an example thereof will be described. FIG. 10 shows a part of another powder manufacturing apparatus,
Reference numeral 12 denotes a reaction tank, and reference numerals 13 and 14 denote droplet discharge devices. The reaction tank 12 has a reaction liquid inlet 15 at an upper part and an outlet 16 at a lower part. An ethyl alcohol solution of sodium hydroxide is stored in the reaction tank 12. The droplet discharge device 13 discharges different droplets such as an ethyl ethoxide solution of aluminum ethoxide and the droplet discharge device 14 discharges an ethyl alcohol solution of zirconium chloride. Each ejected droplet is reacted with an ethyl alcohol solution of sodium hydroxide in the reaction tank 12, and a product obtained by the reaction is taken out from the take-out port 16, and is thermally decomposed, so that zirconia particles and alumina particles are formed. Can be obtained. Also in this example, it was confirmed that both the zirconia and alumina powders had uniform particle diameters.

The droplet discharging means used in the powder producing apparatus of the present invention is not limited to the micropump system, and even if the micropump system is used, the electric device represented by a voltage / electrostrictive element is used. In addition to the mechanical conversion method, the charge control method,
An electrothermal conversion method, an electrostatic suction method, or the like can be employed. In the droplet discharge device, the form of the pressure chamber, the positions of the inlet and the outlet, and the like may be appropriately changed without departing from the spirit of the present invention. Further, the liquid to be used is appropriately selected according to the type of the ceramic powder to be produced.

[0018]

According to the powder production apparatus of the present invention, ceramic powder having a uniform particle size can be efficiently obtained.
Further, according to the droplet discharge device of the present invention, a large amount of minute droplets can be reliably discharged, and the utility value in fields other than the powder production device is high. In particular, the pressurizing chamber may have a long cavity shape, the inlet and the discharge port may be separately arranged at both ends with respect to the long cavity shape, or the discharge port may be configured with a plurality of nozzles, The inlet is composed of a plurality of holes, each nozzle is tapered, the opening area ratio between the inlet and the outlet is limited, the nozzle and the pressurizing chamber are connected via a pressure chamber, If the position where the nozzle is connected to the chamber is limited, the discharge efficiency can be further improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a powder production apparatus according to the present invention.

FIG. 2 shows an embodiment of a droplet discharge device according to the present invention,
(A) is a sectional explanatory view, and (b) is an explanatory view showing a positional relationship between an introduction port and a discharge port.

FIG. 3 is an explanatory diagram showing an example of a position change of an introduction port and a discharge port with respect to a pressurizing chamber.

FIG. 4 is an explanatory diagram showing an example of changing the positions of an introduction port and a discharge port with respect to a pressurizing chamber.

5A and 5B show a modified example of a droplet discharge device having an extrusion chamber, wherein FIG. 5A is an explanatory cross-sectional view, and FIG. 5B is an explanatory diagram showing a positional relationship between an introduction port and a discharge port.

FIG. 6 is an explanatory diagram showing a connection relationship of a nozzle to an extrusion chamber.

FIG. 7 is an explanatory diagram showing an example of changing the positions of the introduction port and the discharge port with respect to the pressurizing chamber.

FIG. 8 is an explanatory diagram showing an example of changing the positions of the introduction port and the discharge port with respect to the pressurizing chamber.

FIG. 9 is an explanatory view showing a modified embodiment of the droplet discharge device.

FIG. 10 is an explanatory view showing a modified embodiment of the powder manufacturing apparatus.

[Explanation of symbols]

1. Heating furnace, 1a. External heater for heating, 2. Air inlet, 3. Air outlet, 4, Powder recovery box,
5 ··· Electromagnetic shutter, 6 ··· Drop discharge device, 7 ·· Pressure chamber, 8 ··· Inlet, 8a ··· through hole, 9 ··· Discharge port, 9a
··· Nozzles, 10 ·· Piezoelectric / electrostrictive elements, 11 ··· Extrusion chambers, 12 ·· Reaction tanks, 13, 14 ·· Drop discharge devices,
15 ··· Reaction liquid inlet, 16 ··· Removal port.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F033 AA14 BA03 CA07 DA03 EA01 NA01 QB03X 4G004 EA02 EA06 4G030 AA17 AA36 GA01 4G068 AA02 AA03 AB11 AC01 AD21 BA04 BB10 BC01 BC17 BD01

Claims (9)

[Claims] A plurality of nozzles provided with a plurality of nozzles; and a heat treatment unit configured to heat fine droplets discharged from the plurality of nozzles. A powder production apparatus for producing ceramic powder by subjecting the droplets to small droplets by the droplet discharge means and then performing heat treatment by the heat treatment means. 2. A pressurizing chamber having an inlet for introducing a liquid and an outlet for discharging a liquid, wherein the liquid droplet discharging means introduces the liquid into the pressurizing chamber and pressurizes the liquid. The powder manufacturing apparatus according to claim 1, wherein the micropump is provided with a pressurizing means for applying intermittent pressure to the pressurizing chamber to cause a volume change in order to discharge the liquid in the chamber. 3. The pressurizing means uses a strain of a piezoelectric / electrostrictive element provided on a part of a wall in the pressurizing chamber to cause a pressure change in the pressurizing chamber. A micropump that discharges the liquid from the nozzle,
3. The powder production apparatus according to claim 1, wherein the pressurizing chamber and the nozzle are formed of zirconia ceramics. 4. The pressurizing chamber has an elongated cavity shape, and has an inlet at one end and a discharge port comprising a plurality of nozzles at the other end in the longitudinal direction. ~ 3
A powder production apparatus according to any one of the above. 5. The pressurizing chamber has an extrusion chamber communicating with the pressurizing chamber, and all the nozzles have a concentric area whose center is equal to half the radius of the bottom surface of the extrusion chamber. The powder production apparatus according to any one of claims 1 to 4, wherein the apparatus is connected to the inside. 6. The pressure chamber according to claim 1, wherein the pressure chamber forms a long cavity, and an introduction port is provided at a central portion in the longitudinal direction, and a discharge port including a plurality of nozzles is provided at both ends. The powder production apparatus according to item 1. 7. The pressurizing chamber comprises a long cavity,
The powder production apparatus according to any one of claims 1 to 5, wherein a discharge port provided with a plurality of nozzles at a central portion with respect to the longitudinal direction, and inlets at both ends are provided. 8. The sum of the cross-sectional areas of the nozzle openings is set to be in a range of 1.5 to 0.67 times the area of the inlet opening, and the inlet and the outlet are connected to each other by the liquid. A tapered shape in which a cross-sectional area gradually decreases in a flow direction.
7. The powder production apparatus according to any one of 6. 9. A pressurizing chamber having an inlet for introducing a liquid and an outlet for discharging a liquid, and pressurizing means for intermittently applying pressure to the pressurizing chamber to cause a volume change. With
A droplet discharge device in which the discharge port is provided with a plurality of nozzles for one pressure chamber.