KR102178435B1 - METHOD FOR MANUFACTURING Ti64 POWDER HAVING HIGH PURITY BY USING RF PLASMA APPARATUS - Google Patents

Abstract

A method of manufacturing high purity Ti64 powder using an RF plasma device is provided.
The present invention, the plasma torch body; A power injection probe formed on an upper portion of the torch body to supply a prismatic Ti metal or Ti64 alloy powder having a size of 10 to 150 μm into the torch by a carrier gas; An intermediate tube configured to surround the upper and outer sides of the power injection probe at a distance; A ceramic insulating tube configured to form an inner surface of a side wall of the torch body; And an induction coil formed on a sidewall of the main body and configured to form a plasma inside the main body, wherein the power injection probe is multiplexed on the upper portion of the plasma torch main body. Forming and supplying the Ti or Ti64 alloy powder into the plasma torch body through such multiple power injection probes; After generating plasma in the plasma torch body, the surface of the supplied Ti metal or Ti64 alloy powder Dissolving at high temperature and then solidifying into a sphere; And a process of collecting the solidified spheroidized powder.

Description

Method for manufacturing high purity Ti64 powder using RF plasma device {METHOD FOR MANUFACTURING Ti64 POWDER HAVING HIGH PURITY BY USING RF PLASMA APPARATUS}

The present invention relates to a method of manufacturing high-purity Ti64 powder using an RF plasma device, and more particularly, by installing a multiple raw material supply probe in an RF plasma device to supply raw materials to the inside, and then producing a spherical powder by plasma treatment. It relates to a method of manufacturing high purity Ti64 powder that can improve both productivity and yield.

Due to the recent active technology development for 3D printing manufacturing, the demand for spherical powders of 10 to 120 μm is increasing, and in particular, the demand for Ti64 alloy spherical powders required for aviation, medical, and military products is expected to increase significantly.

In the case of conventional Ti64 alloy spherical powder, a technique of directly weighing the material according to its composition and dissolving it and then atomizing it with plasma, or manufacturing a Ti64 alloy wire and melting it with plasma to atomize is used. However, this method has the advantage of being able to produce high-purity Ti64 spherical powders with an oxygen concentration of 1000 ppm or less, but the production cost is very high due to the use of expensive raw materials, and the yield is very high in producing fine powders of 30 µm or less. There are low drawbacks.

As another technology, after crushing inexpensive Ti64 alloy scrap by hydrogenation and dehydrogenation processes, prismatic powders that have undergone a deoxidation process are first prepared and spheronized using an RF plasma device to produce spherical powders with low oxygen concentration. The process is being developed. However, even in this technological process, it is not smooth to block the inflow of oxygen to Ti with high oxygen affinity, and when Ca oxide remains on the surface of the prismatic powder that has undergone the deoxidation process, the oxygen concentration is 3000 when the powder is spheronized by the RF plasma process. There are many cases that exist above ppm. It is reported that this oxygen-concentrated spherical powder is unsuitable for use as a 3D printing powder. In addition, even if a spherical powder for 3D is manufactured by controlling the oxygen concentration to 1000 ppm or less using an existing RF plasma device, the yield is very low, and the production cost is having difficulty increasing.

In addition, when the prepared square powder is spheronized using an RF plasma device, the square powder is supplied to the inside of the plasma torch using one nozzle through a feeder and spheroidized to produce 3D powder. However, in this case, since it is possible to produce 1 to 2 kg of spherical powder per hour, there is a disadvantage in that the productivity decreases and the operating cost increases, thereby increasing the selling price.

Therefore, in recent years, as the demand for spherical powder for 3D is greatly increased, the demand for technology development to lower the selling price by mass production continues.

Japanese patent application JP2008-143111 (applied on May 30, 2008)

Therefore, the present invention can improve productivity by supplying raw materials using multiple probes, unlike the prior art in which a square-shaped Ti or Ti64 alloy powder is supplied with one power injection probe inside an RF plasma torch. It is an object of the present invention to provide a method for manufacturing high purity Ti64 powder using an RF plasma device capable of lowering the unit cost.

In addition, the technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned are clearly understood by those of ordinary skill in the technical field to which the present invention belongs from the following description. Can be.

The present invention for achieving the above object,

Plasma torch body; A power injection probe formed on the torch body to supply a square Ti metal or Ti64 alloy powder having a size ranging from 10 to 150 μm into the torch body by a carrier gas; An intermediate tube configured to surround the upper and outer sides of the power injection probe at a distance; A ceramic insulating tube configured to form an inner surface of a side wall of the torch body; And an induction coil formed on a sidewall of the main body and configured to form a plasma inside the main body, wherein the method of manufacturing a high-purity Ti64 powder using an RF plasma device comprising:

Forming a plurality of the power injection probes on the plasma torch body, and supplying the Ti or Ti64 alloy powder into the plasma torch body through the multiple power injection probes;

Generating plasma inside the plasma torch body, dissolving the surface of the supplied Ti metal or Ti64 alloy powder at a high temperature and then solidifying it into a spherical shape; And

The present invention relates to a method for producing high-purity Ti64 powder using an RF plasma device including a process of collecting the solidified spheroidized powder.

After the plasma generation, the inside of the plasma torch body is made into an inert gas atmosphere,

As the carrier gas, an inert gas is supplied in the range of 5-120 slpm,

As the sheath gas supplied from the top of the body to the inside of the body through the spaced space between the intermediate tube and the ceramic insulating tube, an inert gas and hydrogen or helium gas are mixed and the amount of the inert gas is 10-120 slpm, and Supplying an amount of hydrogen or helium gas in the range of 10-50 slpm, and

An inert gas may be supplied in the range of 5-90 slpm as the central gas supplied from the top of the body to the inside of the body.

It is preferable to adjust the height distance between the lower end of the metallic nozzle of the power injection probe and the center of the induction coil within 3 cm above and below.

The multiple power injection probe may be a multiple power injection probe having one in the center and four probe nozzles in the upper, lower, left, and right sides.

The present invention having the configuration as described above can manufacture a large amount of spherical Ti or Ti64 powder that can be used when manufacturing a component requiring a low oxygen concentration using a 3D printer, so that the spherical Ti or Ti64 spherical powder There is an effect that can greatly reduce the production cost.

1 is a schematic cross-sectional view showing a plasma torch constituting an RF plasma device according to an embodiment of the present invention.
2(ab) is a cross-sectional view of a multiple power injection probe according to an embodiment of the present invention, and is a diagram showing a comparison with the prior art having a single power injection probe.
3 is a photograph showing a spherical Ti64 powder subjected to plasma treatment using a manufacturing method according to an embodiment of the present invention.

Hereinafter, the present invention will be described.

When processing the prismatic powder into a spheronized powder with an RF plasma device, it is possible with a lower heat source than when manufacturing nano powders. Therefore, spheronization treatment can be performed even if a large amount of raw material powder is added while the existing high heat source is supplied. The inventors of the present invention have focused on this point, through research and experiments, that when a single raw material supply power injection probe used in an RF plasma device is configured in multiples, a large amount of prismatic powder can be spheronized within the same time. Confirmed. However, if a large amount of raw material powder is supplied, there is a limit to increasing the amount of input by taking away the raw material powder itself from the plasma heat source, but the appropriate amount of input maintains the temperature distribution in the chamber and the melting temperature of the alloy powder through computer simulation. It is to examine whether it is possible and confirm that the input and input can be determined, and to present the present invention.

The method of manufacturing a high-purity Ti64 powder using such an RF plasma device includes: a plasma torch body; A power injection probe formed on the torch body to supply a square Ti metal or Ti64 alloy powder having a size ranging from 10 to 150 μm into the torch body by a carrier gas; An intermediate tube configured to surround the upper and outer sides of the power injection probe at a distance; A ceramic insulating tube configured to form an inner surface of a side wall of the torch body; And an induction coil formed on a sidewall of the main body and configured to form a plasma inside the main body, wherein the power injection probe is multiplexed on the upper part of the plasma torch main body. Forming and supplying the Ti or Ti64 alloy powder into the plasma torch body through the multiple power injection probes; Generating plasma inside the plasma torch body, dissolving the surface of the supplied Ti metal or Ti64 alloy powder at a high temperature and then solidifying it into a spherical shape; And a process of collecting the solidified spheroidized powder.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic cross-sectional view showing a plasma torch constituting an RF plasma device of the present invention.

The RF plasma apparatus of the present invention comprises: a plasma torch body 100; A power injection probe 110 formed on the torch body 100 to supply a prismatic Ti metal or Ti64 alloy powder having a size of 10 to 150 µm into the torch body by a carrier gas; An intermediate tube 130 configured to surround the upper outside of the power injection probe 110 at a distance; A ceramic insulating tube 150 configured to form an inner surface of the sidewall of the torch body; And an induction coil 170 formed on a sidewall of the main body and configured to form a plasma inside the main body. In addition, a cooling water channel pipe 190 is formed on a side wall of the plasma torch body. The ceramic insulating tube 150 serves to protect the appearance of the induction coil 170 by side arc (discharge).

In the present invention, first, the power injection probe 110 is multiplely formed on the plasma torch body 100, and the Ti or Ti64 alloy powder is transferred to the plasma torch body 100 through the multiple power injection probes 110. ) It is supplied inside.

Figure 2 (a-b) is a cross-sectional view of a power injection probe, Figure 2 (a) is a conventional single power injection probe, and Figure 2 (b) is a cross-sectional schematic diagram of a multiple power injection probe of the present invention. As shown in Fig. 2(b), the power injection probe 110 of the present invention is composed of multiple, preferably, a multi-probe having one in the center and four probe nozzles on the top, bottom, left and right based on this. . By having such a cross-sectional structure, a large amount of Ti or Ti64 alloy powder can be supplied into the plasma torch body in a short period of time, so that it can be spheroidized by plasma treatment.

In the present invention, using such a multi-power injection probe 110, a square Ti metal or Ti64 alloy powder having a size in the range of 10 to 150 μm is supplied into the torch body 100 by a carrier gas, which is an inert gas.

At this time, sheath gas is blown into the main body to suppress the rise of the supplied prismatic powder.

Subsequently, in the present invention, after generating plasma in the plasma torch body 100, the surface of the supplied Ti metal or Ti64 alloy powder is dissolved at a high temperature and then solidified into a spherical shape.

That is, when RF plasma power is applied to the plasma torch body 100 using the RF plasma apparatus having the structure as described above, high-frequency thermal plasma is formed inside the plasma torch. In addition, the high-frequency thermal plasma thus formed has the advantage that it does not require chemical fuel or oxygen as a heat source of high temperature and high heat capacity generated and maintained by inductive coupling. In addition, spheronization of high-frequency thermal plasma powder is useful as a method of reducing the size of the powder or obtaining a spherical powder by dissolving or vaporizing the powder by injecting the raw material powder into a high-frequency thermal plasma having a high temperature (6000K or higher) high heat capacity. The prismatic Ti or Ti64 micro powders injected into the thermal plasma are heated from room temperature to a molten state of 2000 K or higher for a short flight time of several to tens of ms, and then rapidly cooled in a spherical droplet state (up to about 10 ⁶ K/s) to convert to spherical powder. do.

At this time, in the present invention, after the plasma is generated, the inside of the plasma torch body is made into an inert gas atmosphere, and an inert gas is supplied as the carrier gas in the range of 5-120 slpm, and between the intermediate tube and the ceramic insulating tube at the top of the body. As the sheath gas supplied into the main body through the spaced space, an inert gas and hydrogen or helium gas are mixed and used, and the amount of the inert gas is 10-120 slpm, and the amount of hydrogen or helium gas is in the range of 10-50 slpm. It is preferable to supply an inert gas in the range of 5-90 slpm as the central gas supplied from the top of the body to the inside of the body. In the present invention, the sheath gas, central gas, and carrier gas should be added in a larger amount than when a single probe nozzle is used.

In this case, it is preferable to adjust the height distance between the lower end of the metallic nozzle of the power injection pro 110 and the center of the induction coil 170 to within 3 cm of the top and bottom.

In addition, in the present invention, in order to reduce the oxygen concentration of the powder to be spheronized, an element having a higher oxygen affinity than Ti is vaporized inside the plasma torch body 100 to capture oxygen separated from the alloy and move to a lower oxygen content. Ti or Ti64 spheroidized powder can be obtained. In detail, Ca vaporized by a low-pressure airflow formed when Ti or Ti64 injected into the plasma torch body 100 descends at high speed, moves to its movement trajectory according to Bernoulli's principle, and meets and deoxidizes Ti or Ti64 spherical powder It will work.

Subsequently, in the present invention, the solidified spheroidized powder is collected. The powder obtained from the spherical powder collection container through this collection process has Ca oxide attached to the surface, and if this is removed, Ti or Ti64 spherical powder containing less than 1300 ppm of oxygen can be effectively obtained.

Hereinafter, the present invention will be described in detail through examples.

(Example 1)

As a precursor for synthesizing a spherical Ti or Ti64 powder using an RF plasma apparatus, square Ti or Ti64 powder having sizes of 10 to 40 μm, 40 to 75 μm, and 75 to 120 μm were used.

In addition, the Ti or Ti64 powder is charged into a powder feeder, and the feeding rate is adjusted to 1 to 7 kg/hr, and the inside of the RF plasma torch using a multiple nozzle as shown in Fig. 2(b). Was supplied to.

The variables that determine the particle size of the spherical Ti or Ti64 powder are RF plasma power, the metallic nozzle of the power injection probe that supplies the precursor to the inside of the torch, and the induction coil that generates RF. coil), the radius of multiple metallic nozzles, and the amount and speed of the precursor.

Therefore, in this experiment, RF plasma power was adjusted to 10-60kW to generate plasma, and then the flow rate, speed, and type of each gas to be introduced were adjusted.

That is, whether or not the spherical powder is accurately formed and whether impurities are formed through plasma treatment are three types of gases that are introduced into the atmosphere gas and the plasma torch. Sheath gas, central gas, and carrier gas gas).

Table 1 below shows the above-described synthesis conditions for preparing spherical Ti or Ti64 powder.

Condition Plasma power 15~60kW
gas

Sheath Ar:10-120 slpm
H ₂ :10~40 slpm Central Ar:5~90 slpm Carrier Ar:5~120 slpm Quench Ar:20-50 slpm

At this time, the height distance between the lower end of the metallic nozzle of the power injection probe and the center of the induction coil generating RF was adjusted to within 3 cm up and down.

The prismatic Ti or Ti64 powder introduced under the above synthesis conditions was plasma-treated, and the powder was dissolved and vaporized by a high-temperature plasma, and the final spheroidized powder could be collected. As a result of measuring the flow rate, apparent density, tap density, and sphericity of the collected powder, which are suitable conditions for use with a 3D printer, the measured values were 24.3 seconds, 2.47 g/cm3, 2.59 g/cm3, and 97.4%, respectively. Able to know.

3 is a photograph showing a plasma-treated spherical Ti64 powder manufactured using the manufacturing method of this embodiment.

(Example 2)

Table 2 shows the oxygen concentration of the spherical Ti or Ti64 powder by controlling the feeding rate under plasma power of 60 kW.

In this embodiment, in order to reduce the oxygen concentration of the powder to be spheronized, Ca having a higher oxygen affinity than Ti is vaporized inside the body of the plasma torch to capture oxygen that is separated from the alloy and moves, thereby reducing the oxygen content of Ti or Ti64. A spheronized powder was obtained.

As shown in Table 2, it can be seen that a spherical powder having an oxygen concentration of 1100 ppm or less can be obtained up to 12 kg per hour.

Psalter Feed rate (kg/h) Oxygen concentration before test (ppm) Oxygen concentration after spheronization (ppm) One 1.2
1500
980 2 2.0 960 3 4.5 1005 4 7.5
1700

1100 5 10.0 1050 6 11.0 975 7 12.0 1020

Whether the collected powder had a phase formation and whether the second phase was present was confirmed through XRD, and Ti or Ti64 spherical powder could be obtained as desired.

In addition, Ti or Ti64 powder having a sphericity of 97% containing a low oxygen concentration could be obtained through a mass production process.

As described above, in the detailed description of the present invention, preferred embodiments of the present invention have been described, but those of ordinary skill in the art to which the present invention pertains, various modifications within the limit not departing from the scope of the present invention. Of course this is possible. Therefore, the scope of the present invention is limited to the described embodiments and should not be determined, and should not be determined by the claims to be described later, as well as those equivalent thereto.

100......Plasma torch body
110......Power injection probe
130......Middle tube
150.......Ceramic insulation tube
170.......Induction coil
190.......Cooling channel pipe

Claims (4)

Plasma torch body; A power injection probe formed on an upper portion of the torch body to supply a prismatic Ti metal or Ti64 alloy powder having a size of 10 to 150 μm into the torch by a carrier gas; An intermediate tube configured to surround the upper and outer sides of the power injection probe at a distance; A ceramic insulating tube configured to form an inner surface of a side wall of the torch body; And an induction coil formed on a sidewall of the main body and configured to form a plasma inside the main body, wherein the method of manufacturing a high-purity Ti64 powder comprising:
A first process of forming multiple power injection probes on the plasma torch body and supplying the Ti or Ti64 alloy powder into the plasma torch body through the multiple power injection probes;
A second process of generating plasma in the plasma torch body, dissolving the surface of the supplied Ti metal or Ti64 alloy powder at high temperature and then solidifying it into a sphere; And
Including; a third process of collecting the solidified spheroidized powder,
In the second process, a spherically solidified Ti metal or Ti64 alloy powder is deoxidized by vaporizing Ca inside the plasma torch body, and Ca adhered to the surface of the Ti metal or Ti64 alloy powder deoxidized in the third process A method for producing high-purity Ti64 powder using an RF plasma device, comprising preparing a Ti metal or Ti64 spherical powder containing less than 1300 ppm of oxygen by removing the oxide.
The method of claim 1, wherein after the plasma is generated, the inside of the plasma torch body is made into an inert gas atmosphere,
As the carrier gas, an inert gas is supplied in the range of 5-120 slpm,
As the sheath gas supplied from the top of the body to the inside of the body through the spaced space between the intermediate tube and the ceramic insulating tube, an inert gas and hydrogen or helium gas are mixed and the amount of the inert gas is 10-120 slpm, and Supplying an amount of hydrogen or helium gas in the range of 10-50 slpm, and
High purity Ti64 powder manufacturing method using an RF plasma device, characterized in that an inert gas is supplied in a range of 5-90 slpm as a central gas supplied from the upper portion of the body to the inside of the body.
The method of claim 1, wherein the height distance between the lower end of the metallic nozzle of the power injection probe and the center of the induction coil is adjusted to within 3 cm of the upper and lower ends.
The method of claim 1, wherein the multi-power injection probe is a multi-power injection probe having one at a center and four probe nozzles at the top, bottom, left, and right with respect to the multiple power injection probes.

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