JPH05105918A - Method and device for producing finely dispersed composite powder - Google Patents

Abstract

PURPOSE:To produce a finely dispersed composite powder with high productivity and without segregating a ceramic powder. CONSTITUTION:A ceramic powder 4 is finely dispersed in a molten metallic material 6 and reinforced to produce a finely dispersed composite powder 7 for the composite material by atomization process with high productivity. The molten metallic material 6 is split into a thin film at the end of a molten metal tube 1 by utilizing a gas vortex formed at an atomizer nozzle, and the ceramic powder 4 is supplied to the thin film to produce a composite powder 7 wherein the ceramic powder is finely dispersed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a fine dispersion composite powder suitable for use as a raw material in the production of a dispersion-strengthened composite metal material for improving high temperature strength or wear resistance. More specifically,
The present invention collides a metal material (including an alloy material in the present specification) in a molten state with a spray fluid such as a gas or a fluid at a high flow rate, and at the same time, a powder material having a high melting point and a light material such as ceramics. The present invention relates to a method and an apparatus for producing a finely dispersed composite powder, which produces a finely dispersed composite powder in which, for example, ceramic is complexed to a metal material by supplying the molten metal material to the flow field.

[0002]

2. Description of the Related Art In order to manufacture sintered parts by powder metallurgy,
As is well known, a method of compressing and molding powder in a die to make a powder compact of a certain shape and heating the powder compact in a reducing atmosphere to sinter, filling the powder into a capsule and sealing it Then
Methods such as cold or hot isotropic compression molding or hot extrusion molding have been carried out.

In particular, the following method is known as a method for producing a raw material powder which can be applied in producing a dispersion-strengthened composite metal material capable of improving the high temperature strength or abrasion resistance of a product.

(I) MA (Mechanical Alloying) Method A raw material powder is dry-processed by kneading a powder of a metal material which is a matrix of a molded material and a ceramic powder for dispersion strengthening with a high energy ball mill. Is a method of generating. After encapsulating this raw material powder in a can,
A composite material is obtained by densifying by hot extrusion, rolling, hot pressing, HIP, or the like.

(Ii) Spray Deposit Method A metal material in a high temperature molten state is made to flow down through a small hole at the bottom of a container to inject a gas medium, and at the same time a ceramic powder for strengthening dispersion is injected into the gas medium injected. After spraying, a mixture of droplets of the metallic material in a molten state and the ceramic powder is deposited on the base material, and if necessary, it is densified by rolling, hot pressing, HIP or the like to obtain a composite material.

(Iii) Atomizing method A metal material in a molten state at a high temperature is made to flow down from a small hole (spray nozzle) at the bottom of a container, and a spray fluid such as gas or liquid is jetted, and at the same time, ceramic powder for strengthening dispersion. Is a method of producing a raw material powder by mixing ceramic powder with droplets of a metallic material in a molten state by supplying the sprayed fluid to the sprayed fluid. Like the raw material powder produced by the above-mentioned MA method, this raw material powder is enclosed in a can and then densified by hot extrusion, rolling, hot pressing, HIP or the like to obtain a composite material. For example, JP-A-62-109905 discloses a method for producing a finely dispersed composite powder in which the ceramic powder is finely and uniformly distributed by supplying the ceramic powder from above the center hole of the spray nozzle in the atomizing method. Proposed.

[0007]

However, each of the conventional methods for producing the raw material powder of the dispersion-strengthening type composite metal material has the following problems. In the MA method, since the metal material powder and the ceramic powder are kneaded by a high-energy ball mill, the raw material powder is manufactured, for example, by 10 to 100 hr.
It takes a long time and the productivity is low, and cross contamination by the ball mill container is also a problem.

The spray deposit method is a method of simultaneously depositing a droplet of a metal material in a semi-molten state and a ceramic powder on a base material to form a composite material, and therefore, a ceramic powder for dispersion strengthening. Was easily segregated, and it was difficult to impart predetermined performance to the product.

Further, in the atomizing method, a metal material in a molten state at a high temperature is sprayed, and at the same time, a powder for strengthening is sprayed to be entrained in the metal material in a semi-molten state and mixed and dispersed. There is a problem that the amount of the ceramic powder that can be formed cannot be increased so much and that the reinforcing powder in the composite powder easily causes segregation.

As described above, according to the conventional technique, it was not easy to produce the finely dispersed composite powder with high productivity without causing segregation of the ceramic powder. An object of the present invention is to provide a manufacturing method and a manufacturing apparatus for finely dispersed composite powder that can solve the above problems.

[0011]

As a result of various studies to solve the above problems, the present inventors have found an atomizing method for supplying ceramic powder for dispersion strengthening at the same time as spraying a metal material in a molten state. It is desirable to use the ceramic powder from the viewpoint of preventing the productivity from decreasing, and the supplying / compositing of the ceramic powder may be performed in a stage before being sprayed into a droplet, that is, in a stage in which the metal material is deformed. From the viewpoint of preventing the segregation of ceramic powder, it was found to be effective.

Based on such knowledge, the inventors of the present invention have conducted further studies, and as a result, in order to realize the above and, in order to realize the above and The present invention has been completed by finding that ceramic powder for dispersion strengthening may be supplied to and mixed with a molten metal flow that spreads in a thin film shape in the outer peripheral direction of the tube by the action of pressure.

Here, the gist of the present invention is to provide a molten metal pipe for supplying the molten metal material to the spray fluid when the powder is produced by an atomizing method in which the molten metal material is made to flow down into the spray fluid to produce the powder. A powder material different from the molten metal material is supplied into the atomizing fluid from the periphery of the above.

Specifically, the powder material is disposed in the spray fluid sprayed in an inverted conical shape having an axis coinciding with the center axis of the circular molten metal tube, and is spaced apart from the molten metal tube and its periphery. The intersecting line of the sprayed fluid sprayed in a sheet shape from the annular slit formed between the molten metal pipe and the rectangular slit is formed along the long side of the molten metal pipe. It is possible to exemplify a mode in which each is supplied from a rectangular slit formed between the molten metal pipe and an outer pipe spaced apart from the molten metal in the spray fluid coinciding with the center line of the side.

In the present invention described above, the long side and the short side have different lengths, and the horizontal cross-sectional shape of the molten metal and the outer tube is rectangular, or the long side and the short side have the same length. This includes the case where the horizontal cross-sectional shape is square.

[0016] From still another aspect, the present invention is an apparatus for producing a finely dispersed composite powder having a molten metal pipe for flowing a molten metal material into an atomizing fluid, the device comprising: (i) a space around the molten metal pipe. And (ii) the outer tube is made of metal, and at least a part of the outer surface of the outer tube is provided with a ceramic coating. ..

[0017]

The operation of the present invention will be described in detail below. In order to produce a metal material powder in which ceramic powder, which is a dispersion-strengthening powder, is composited by the atomizing method with high productivity, it is necessary to simultaneously compound the ceramic powder when the metal material powder is produced.

In the metal-based finely dispersed composite powder, it is common to use ceramics or intermetallic compounds as the reinforcing powder, but these powders have physical properties (particularly, specific gravity and particle size). It is remarkably different from the powder of the metallic material used as the matrix. Therefore, in the atomizing process,
In order to finely mix, when the metal material powder is in a molten state and in a substantially stationary state, it is necessary to jet and supply the ceramic powder to completely mix it, and then immediately quench and solidify it. ..

As is well known, the atomization method is a method for producing a rapidly cooled powder material, in which molten metal material particles are rapidly cooled and fly at high speed by a high-speed atomizing fluid. Therefore, in order to finely and uniformly compound the ceramic particles in the metal material powder, it is necessary to mix the powder for dispersion strengthening just before the molten metal material collides with the high-speed atomizing fluid and starts to fly at high speed. Is.

Therefore, in the present invention, as shown in FIG. 1, which is a schematic explanatory view of one embodiment of the molten metal pipe used in the present invention, from around the molten metal pipe 1 for supplying the molten metal material to the flow field of the spray fluid. The molten metal material is moved in the form of a thin film in the outer peripheral direction of the molten metal pipe 1 by the action of negative pressure due to the swirling flow 3 of the gas generated at the tip of the molten metal pipe 1 by injecting the high-speed atomizing fluid 2 and strengthening the dispersion. The ceramic powder 4 for use is supplied to the thin film molten metal material from the annular slit 20 provided between the outer pipe 5a provided on the outer peripheral portion 5 of the molten metal pipe and the molten metal pipe 1, and the molten metal material 6 is sprayed. Immediately before the mixing, the ceramic powder 4 for dispersion strengthening is mixed, and then sprayed with the spray fluid 2 to produce the finely dispersed composite powder 7.

The cross-sectional shape of the molten metal pipe 1 may be circular as shown in FIG. 1 or rectangular as shown in FIG. The reference numerals in FIG. 3 are the same as those in FIG. In the case of a rectangular cross-sectional shape, in the spray fluid in which the intersecting line of the spray fluid 2 sprayed in a sheet form from the long side of the melt tube 1 coincides with the short side center line along the long side of the melt tube,
A rectangular slit 20 having a rectangular horizontal cross section formed between the molten metal pipe 1 and an outer pipe 5a arranged around the molten metal pipe 1 at a distance.
Supplied from.

At this time, by appropriately selecting the spray angle θ of the spray fluid and the distance between the spray hole of the spray medium and the powdering point, an inverted conical shape as shown in FIG. 1 or a V-shape as shown in FIG. The jet of the atomizing medium injected into the cross-sectional shape of the mold adjusts the size and strength of the gas vortex flow formed above the intersecting region, and the molten metal material flowing out from the molten metal pipe outlet flows from the molten metal pipe. The shape when flowing out and moving the outlet end can be made into an appropriate thin film shape. According to the knowledge of the present inventors, in order to make the shape of the molten metal material flowing out from the molten metal pipe into an appropriate thin film shape, the injection pressure and the injection angle of the spray fluid are set as shown in FIGS. It should be set appropriately. FIG. 4 shows the case of the inverted conical jet shown in FIG.
FIG. 5 shows the case of a V-shaped jet. It is preferable that the outer tube is made of metal, and at least a part of the outer surface thereof is ceramic-coated. If the outer tube is made of metal, high-pressure gas is injected, so it is possible to prevent breakage and erosion due to the injection pressure of the gas, and by applying a ceramic coating, the molten metal port is clogged and atomization becomes impossible. At the same time, it becomes possible to prevent the powder from being unable to be supplied from the slit and the fine dispersion composite powder from being unable to be manufactured.
The range of the ceramic coating can be exemplified by coating at least a part of the outer surface, for example, the entire circumference of the tip portion by 2 mm or more, but the range is not particularly limited. Furthermore, the coating means does not need to be limited at all.

Further, the present invention will be described in detail with reference to the embodiments embodied by the accompanying drawings, but this is an example of the present invention and the present invention is not limited thereto.

[0024]

EXAMPLE 1 FIG. 2 is a schematic explanatory view of an apparatus for producing a finely dispersed composite powder according to the present invention. In the figure, reference numeral 8 is an atomizing tank, and an atomizing nozzle 9 is installed above the atomizing tank 8. The structure of the molten metal pipe 12 provided in the atomizing nozzle 9 is as shown in FIG. The powder 16 for dispersion strengthening is piped from the powder feeder 10.
It is supplied to the outer peripheral portion of the molten metal by 11. The molten metal pipe 12 is connected to the bottom of a molten material container 13, and the molten material container 13 is installed in a closed container 14. A molten metal material is supplied to the closed container 14 from a melting device (not shown). The molten metal material is fed from the bottom of the molten material container 13 through the molten metal pipe 12 to the atomizing nozzle 9. Atomize nozzle 9
High-pressure inert gas is supplied to the atomizing nozzle 9
A high-velocity gas jet flow is generated from the injection hole 15 and collides with the flowing molten material to pulverize and pulverize the molten material and cool it to produce powder. At this time, the dispersion-strengthening powder 16 is supplied to the gas flow field through the annular gap 18 between the refractory tube through which the molten metal flows and the slit tube 17 installed on the outer peripheral portion thereof, and becomes a thin film shape and the outer periphery of the molten metal tube The finely divided composite powder is produced by being mixed with the molten metal material spread in the direction.
The produced finely dispersed composite powder is collected by the bottom of the atomizing tank 8 and the cyclone 19 connected thereto. The slit tube 17 is made of carbon steel (JIS SS41), and the portion 5 mm from the tip is covered with zirconia-based ceramics over the entire circumference.

The alloy material having the alloy composition shown in Table 1 was supplied to the preheated molten material container 13 by using the apparatus for producing the finely dispersed composite powder according to the present invention having the above-mentioned structure. In addition,
The composition ratio in Table 1 shows the composition ratio in the final product. On the other hand, as the powder for dispersion strengthening, yttria powder having the characteristics shown in Table 2 was fed to the outer periphery of the molten metal pipe by the powder feeding device 10 through the pipe 11. As the powder supply device 10, a commercially available device for a thermal spraying device was generally used, and the yttria powder was conveyed by nitrogen gas.

[0026]

[Table 1]

[0027]

[Table 2]

A high pressure argon gas was fed to the atomizing nozzle 9, and composite powder was produced by gas atomizing under the conditions shown in Table 3.

[0029]

[Table 3]

As a result, the resulting 13Cr-based composite powder had an average particle size of about 85 μm, and its cross section was observed.
It was found that the yttria particles were uniformly dispersed in the matrix of the Cr alloy. This powder was filled in a stainless steel can container, evacuated, and sealed, heated to 1473K in an electric heating furnace, and then hot extruded by a vertical hydraulic press to form a bar with an outer diameter of about 22 mm. I made it. The bar was subjected to a predetermined heat treatment and then the tensile strength at high temperature was measured.

On the other hand, for comparison, a powder was produced by a mechanical alloying method, an extruded rod material was manufactured by the above-mentioned molding method, and the tensile strength at high temperature was similarly measured. That is, Cr having the composition shown in Table 4 and having the composition shown in Table 5
The alloy powder, pure iron, and yttria powder were inserted into a high energy ball mill and kneaded for 50 hours in an atmosphere purged with argon gas to recover the powder. The method of molding the recovered powder is the same as that of the atomized composite powder described above.

[0032]

[Table 4]

Table 6 shows the evaluation results of the test materials prepared by the method described above. The composite material produced according to the present invention was comparable to the material produced by the mechanical alloying method which requires a long kneading operation.

[0034]

[Table 6]

[0035]

Example 2 Using the apparatus for producing finely dispersed composite powder according to the present invention shown in FIG. 2 having the molten metal tube 1 shown in FIG. 3,
A finely dispersed composite powder was produced. In the present embodiment, the molten metal material is supplied through the molten metal pipe 12 having a rectangular cross section, the spray fluid is sprayed in a sheet form from the long sides on both sides of the molten metal pipe 12, and The intersection line coincides with the center line along the major axis of the molten metal pipe. It should be noted that a slit tube in which the ceramic powder for compounding is installed on the outer periphery of the molten metal pipe 1 with its inner surface separated from the outer periphery of the molten metal pipe 1.
The method of supplying from the thin plate-shaped gap with 17 is the same as in the first embodiment.

The alloy material having the chemical components shown in Table 7 was supplied to the preheated molten material container 13 by using the above-described apparatus for producing the finely dispersed composite powder having the structure shown in FIG. On the other hand, as the ceramic powder as the particles for strengthening dispersion, the yttria powder having the characteristics shown in Table 2 was fed to the outer peripheral portion of the molten metal pipe through the pipe 11 by the powder feeding device 10.

[0037]

[Table 7]

High-pressure argon gas was fed to the atomizing nozzle, and composite powder was produced by gas atomizing under the conditions shown in Table 8. In this example, the supply amount of the molten alloy material was reduced as compared with the above examples, and more fine powder was generated.

[0039]

[Table 8]

As a result, the resulting 13Cr-based composite powder had an average particle diameter of 45 μm, and its cross section was observed.
As in the case of Example 1, it was found that yttria particles were uniformly finely dispersed in the matrix of the Cr alloy. After filling this powder in a stainless steel can container, evacuating it, sealing it, and heating it to 1473K in an electric heating furnace,
It is hot extruded by a vertical hydraulic press and has an outer diameter of about 22.
I made a mm bar. After subjecting this bar material to a predetermined heat treatment, the tensile strength at high temperature was measured.

Table 9 shows the evaluation results of the test materials thus obtained and the powder molding materials by the MA method given as a comparative example in the above Examples. As is clear from Table 9, the composite material obtained by the method of the present invention was comparable to the material obtained by the mechanical alloying method, which requires a long kneading operation, again. Also, it can be seen that the amount of the powder material to be sprayed can be increased as compared with the conventional atomizing method.

[0042]

[Table 9]

[0043]

[Third Embodiment] In the first embodiment, as a material of the slit pipe installed on the outer periphery of the molten metal pipe, ordinary carbon steel (SS41) is used.
Table 9 shows the comparison results of the stability of the driving operation in the powder production in the case of applying ceramic spraying to the outer surface, that is, the clogging of the molten metal pipe due to the adhesion of the sprayed molten droplet-shaped metal material powder. Shown in. From this result, it is apparent that the ceramic spraying applied to the outer circumference of the slit tube eliminates the blockage of the molten metal tube and contributes to stable operation and improvement in yield.

[0044]

[Table 10]

[0045]

As described in detail above, according to the present invention, a finely dispersed composite powder finely dispersed without causing segregation of a ceramic powder which is a dispersion strengthening powder is produced by an atomizing method with high productivity and low cost. can do. The significance of the present invention having such effects is remarkable.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an example of a molten metal tube used in an apparatus for producing a finely dispersed composite powder according to the present invention.

FIG. 2 is a schematic explanatory view of an example of an apparatus for producing a finely dispersed composite powder according to the present invention.

FIG. 3 is a schematic explanatory view of an example of a molten metal pipe used in the apparatus for producing a finely dispersed composite powder according to the present invention, which is different from the molten metal pipe shown in FIG.

FIG. 4 is a graph showing an appropriate range of the relationship between the injection pressure and the injection angle of the molten metal material flowing out of the molten metal pipe, which has the configuration shown in FIG. 1.

FIG. 5 is a graph showing an appropriate range in the relationship between the injection pressure and the injection angle of the molten metal material flowing out of the molten metal pipe with the molten metal pipe having the configuration shown in FIG.

[Explanation of symbols]

 1: Melt pipe 2: Spraying fluid 3: Gas vortex flow 4: Ceramic powder 5: Molten pipe outer peripheral part 5a: Outer pipe 6: Molten metal material 7: Fine dispersion composite powder 8: Atomizing tank 9: Atomizing nozzle 10: Powder Supply device 11: Piping 12: Molten metal pipe 13: Molten material container 14: Closed container 15: Injection hole 16: Dispersion strengthening powder 17: Slit tube 18: Annular gap 19: Cyclone 20: Annular slit

Claims (4)

[Claims] 1. When producing a powder by an atomizing method of producing a powder by flowing a molten metal material into an atomizing fluid,
A method for producing a finely dispersed composite powder, characterized in that a powder material different from the molten metal material is supplied into the spray fluid from around the molten metal pipe for supplying the molten metal material to the spray fluid. 2. The molten metal and the outer periphery of the powder material are spaced apart from each other in the spray fluid injected in an inverted conical shape having an axis coinciding with the center axis of the circular molten metal tube. The method for producing a finely dispersed composite powder according to claim 1, wherein the fine powder is supplied from an annular slit formed between the tube and the tube. 3. The powder material is 2 of the rectangular molten metal pipe.
The intersecting lines of the spray fluid sprayed in the form of sheets from the two long sides coincide with the center line of the short side along the long side of the melt pipe, and the melt pipe and the periphery thereof are spaced apart from each other. The method for producing a finely dispersed composite powder according to claim 1, wherein the fine powder is supplied from a rectangular slit formed between the outer tube and the outer tube. 4. An apparatus for producing a finely dispersed composite powder having a molten metal pipe for flowing a molten metal material into an atomizing fluid, comprising: (i) an outer pipe arranged around the molten metal pipe at a distance. And (ii) the apparatus for producing finely dispersed composite powder, wherein the outer tube is made of metal, and at least a part of the outer surface thereof is ceramic-coated.