TW201938810A - Titanium powder and method for producing same - Google Patents

Abstract

Provided is a titanium powder which is reduced in pores in titanium particles. A titanium powder that is characterized in that the pore area ratio, which is the value obtained by dividing the cross-sectional area of pores in a cross-section of the titanium powder by the area of the cross-section, is 0.3% or less. A method for producing a titanium powder, which is a hydrogenation-dehydrogenation method comprising a hydrogenation step, a pulverization step and a dehydrogenation step to be performed on a titanium starting material, and which is characterized in that the concentration of all MgCl2 contained in the titanium starting material is 1.0 mass% or less, while the internal MgCl2 concentration is 0.1 mass% or less.

Description

Titanium powder and manufacturing method thereof

The present invention relates to titanium-based powder, and details relate to the production of a new and unprecedented titanium-based powder by a hydrodehydrogenation method (hereinafter referred to as HDH method) and a method for producing the same.

In the past, the pores in titanium-based powders have received little attention in the industry, and there are few documents such as literatures that study the pore generation mechanism in detail. In recent years, with the increase in the density of sintered bodies using titanium-based powders or the increase in the quality requirements for titanium products made from titanium-based powders, the requirements for reducing pores in titanium-based powders have increased.

Although investigations have been conducted on the prior art literature that discloses techniques for reducing the pores of titanium-based powders, no findings have been found. As prior art documents on the production of titanium-based powder, there are Patent Document 1 and Patent Document 2. In this specification, titanium powder and titanium alloy powder are referred to as titanium-based powder.

『Patent Literature』
"Patent Document 1" Japanese Patent Publication No. H5-247503 "Patent Document 2" Japanese Patent Publication No. H7-278601

The present invention aims to solve the above problems, that is, to provide a titanium-based powder having reduced pores in the titanium-based powder.

In order to achieve the production of the titanium-based powder with few pores as described above, the structure of the pores or the mechanical rotation are analyzed in detail in the present invention. As a result, it was found that by adjusting the raw materials and manufacturing methods of the titanium-based powder, the number of pores generated would be greatly changed. At the same time, it was noted that the generation of the pores was caused by the existence (or existence) of gas in the titanium-based powder. Analysis results of pores with a slightly circular (spherical) cross-sectional shape.

According to an embodiment of the present invention, a titanium-based powder is provided, characterized in that the ratio of the pore area of the cross-section area occupied by the pores in the cross-section of the titanium-based powder to the area of the cross-section of the aforementioned titanium-based powder is 0.3% or less.

The titanium-based powder may be an HDH powder.

According to one embodiment of the present invention, there is provided a method for producing a titanium-based powder, which is a method for producing a titanium-based powder through a hydrogenation and dehydrogenation method including a hydrogenation process, a pulverization process, and a dehydrogenation process using a titanium-based raw material. This is because the total MgCl ₂ concentration contained in the titanium-based raw material is 1.0 mass% or less, and the internal MgCl ₂ concentration is 0.1 mass% or less.

The maximum thickness of titanium-based materials can also be 20 mm or less.

In the pulverizing step, the titanium hydride-based powder may be pulverized to a D95 particle size of 300 μm or less.

In the hydrogenation step, the titanium-based raw material may be hydrogenated for a period of 90 minutes or more within the range of 716 ° C to 1050 ° C.

The generation of pores in titanium-based powders is closely related to the gas. By not entraining the gas in the titanium-based powder or generating gas inside the titanium-based powder, or by rapidly eliminating the generated gas from the inside of the titanium-based powder, the number of pores of the titanium-based powder can be greatly reduced. number.

Almost all titanium powders use sponge titanium produced by the Kroll method as a raw material. In addition, in terms of economy and resource protection, there are cases where scrap is used as a raw material.

[Explanation of the Kroll Act]

The so-called Kroll method is a method in which titanium tetrachloride (TiCl ₄ ) obtained by chlorinating titanium ore with magnesium (Mg) is reduced to obtain metallic titanium.

In the Kroll method, since MgCl ₂ generated in the reduction step (TiCl ₄ + 2Mg → Ti + 2MgCl ₂ ) coexists with the sponge titanium, sponge titanium after the MgCl ₂ is removed in the separation step is used. However, if the sponge titanium is examined carefully, it can be seen that there are ₂ remaining MgCl ₂ (surface MgCl ₂ ) attached to the surface of the sponge titanium and MgCl ₂ (internal MgCl ₂ ) trapped inside the sponge titanium and isolated from the outside. This method does not completely remove MgCl ₂ .

MgCl ₂ (surface MgCl ₂ ) remaining on the surface of the sponge titanium without being fully removed in the separation step can be removed by heating again under reduced pressure. On the other hand, the sponge titanium after being heated under reduced pressure is cut and the interior is examined. It can be seen that MgCl ₂ (internal MgCl ₂ ) trapped inside the sponge titanium cannot be eliminated by this method.

[Explanation of Manufacturing Method of Titanium Powder by Atomization Method]

The manufacturing methods of titanium powder are roughly divided into atomization method and HDH method. In the atomization method, after the titanium raw material is melted, the liquefied titanium is made into fine liquid particles in an Ar gas, and then rapidly cooled to solidify, thereby manufacturing titanium powder.

In the research and investigation of the present inventors, the following conclusions can be drawn: In the atomization method, there are two mechanisms for generating pores in the titanium powder. The first MgCl ₂ (internal MgCl ₂ ) existing inside the titanium raw material was gasified at once and rapidly cooled, so the gasified MgCl ₂ was trapped inside the liquefied titanium particles, and the titanium powder Mechanism of fine pores. The second is a mechanism in which liquefied titanium particles entrain Ar gas or vaporized MgCl ₂ gas to solidify, thereby generating pores in the titanium powder. It is concluded that the HDH method is appropriate for the purpose of cost invention.

[Explanation of the manufacturing method of HDH titanium powder]

The so-called HDH method is a method in which titanium raw material is first hydrogenated to form brittle TiH ₂ , and then pulverized and dehydrogenated to obtain titanium powder. That is, it is a method for producing titanium powder (HDH powder) through the steps of hydrogenation-pulverization-dehydrogenation-disintegration. The above-mentioned disintegration step is arbitrary, but it is preferable to perform the disintegration step in the production of titanium powder (HDH powder).

At this time, in the hydrogenation process, the titanium raw material is charged into a hydrogenation furnace capable of being vacuum-replaced, and hydrogenated in a hydrogen gas environment at a temperature of 400 ° C or higher, thereby replacing the hydrogen gas environment with an Ar gas gas environment, thereby obtaining A block of titanium hydride. The titanium raw material is hydrogen-embrittled by the hydrogenation process.

The second step is the crushing process. In the pulverizing step, the titanium hydride block is mechanically pulverized to make a titanium hydride powder having a mechanically broken surface (that is, a pulverized surface). The obtained titanium hydride powder is classified and / or screened to remove fine powder of titanium hydride. For mechanical pulverization of titanium hydride, a pulverizing device such as a ball mill and a vibrating mill can be used, and the particle size adjustment of the titanium hydride powder can also be performed. A screening device such as a circular vibrating screen and an air classifier can also be used.

In the dehydrogenation step, the above-mentioned titanium hydride powder is filled in a container, put into a vacuum heating type dehydrogenation furnace, and heated to a temperature of 450 ° C or higher in a vacuum of 10 ^-3 Torr (0.13 Pa) or less for dehydrogenation. This was made into dehydrogenated titanium powder. Also, insert Ar gas as required.

In the disintegration step, the pseudo-sintered portion of the dehydrogenated titanium bulk that has been pseudo-sintered in the dehydrogenation step is loosened and restored to a titanium powder shape having a crushed surface or a crushed surface.

[Explanation of the pore generation mechanism in the HDH method]

From the viewpoint of pores, the present inventors have studied in detail the conditions in each manufacturing process of the HDH method, and found out how to prevent the generation of pores. In the HDH method, if there is no titanium melt liquefaction in each manufacturing process, Ar gas in the gas environment will not cause pores. Since the heat treatment in the HDH method is a two-step process of hydrogenation and dehydrogenation, it may be performed below the melting point. However, because stainless steel is generally used as a container for placing titanium materials, if the iron and titanium contained in the stainless steel are in contact, the temperature of the two is above the eutectic temperature of iron and titanium, the titanium will be in a liquid state and will not meet the above requirements. purpose. Therefore, the present inventors have found that in order to prevent the generation of pores, titanium must be controlled below the eutectic temperature of iron and titanium to prevent the liquefaction of titanium. That is, controlling the upper limit temperature becomes an important constituent element of the present invention.

For example, Patent Literature 1 and Patent Literature 2 only describe "the temperature is raised to 650 ° C in a vacuum gas environment", and there is no description about the temperature control of the titanium material after the introduction of hydrogen gas. Since the hydrogenation reaction of hydrogenating titanium is an exothermic reaction, although the hydrogen absorption is performed at 650 ° C. in a vacuum furnace at first, the temperature rises spontaneously thereafter. It is necessary to constantly observe the manner in which the titanium material is put into the container, the amount of hydrogen and Ar to be placed, the time and temperature of each part, and at the same time, to control the temperature rise and perform fine control such as cooling, so as to include local tasks. All are below eutectic temperature.

The boiling point of MgCl ₂ at normal pressure is 1412 ° C. At this temperature, MgCl ₂ (internal MgCl ₂ ) trapped inside the titanium raw material will gasify. On the other hand, the melting point of titanium is 1668 ° C, so at 1412 ° C, titanium will exist in a solid state. The volume of the gasified MgCl ₂ will be larger than that in the solid state. For this reason, a very high pressure state will be formed inside the titanium. The high-pressure state caused by the gasified internal MgCl ₂ will cause cracking of the titanium hydride that is brittle by hydrogenation, and MgCl ₂ can be discharged to the outside of the titanium hydride from here.

However, as mentioned earlier, in the HDH method, the container in which the titanium material is placed is stainless steel, and the temperature does not rise above the eutectic temperature of iron and titanium (1085 ° C). In the present invention, it has been found that a control method that has not been seen before is to observe the temperature restricted by this limitation and eliminate the pores of MgCl ₂ , and then complete the present invention. Briefly, the most low-temperature titaniferous material to a melting point of MgCl ₂ (714 deg.] C) temperature above the MgCl ₂ liquid phase to make the volume of MgCl ₂ as compared to the expansion in the solid state. At this time, because titanium exists in a solid state, the volume of the internal MgCl ₂ in the liquid state becomes larger than that in the solid state. For this reason, a very high-pressure state is formed inside the titanium. The high-pressure state caused by the internal MgCl _{2 in the} liquid phase may cause cracking of the titanium hydride that becomes brittle by hydrogenation. The liquid phase MgCl ₂ exposed to the outside of the titanium due to cracking is such that it can be gasified by slow evaporation. In this case, the control of the temperature in the furnace and the heating time (temperature maintaining time) can also be determined by considering the thickness or hydrogenation time of the hydrogenated titanium raw material. For example, if the pressure inside the titanium increases due to the evaporated MgCl ₂ before the titanium is embrittled, the titanium will be easily deformed due to softening at high temperature, which will result in the formation of spherical pores inside the titanium. This is in the opposite direction to the present invention. For example, in the present invention, by spending more than 90 minutes in the range of 716 ° C to 1050 ° C, the MgCl ₂ existing in the titanium raw material can be evaporated from the crack of titanium, and the hydrogenation of titanium is also Together. Theoretically, although the temperature of the titanium raw material can be set in the range of the melting point (714 ° C) or more of the MgCl _{2 to} the eutectic temperature (1085 ° C) of iron and titanium, the temperature range can be further improved by setting the temperature range as described above. True temperature control.

In addition, in the HDH method according to the embodiment, the titanium of the raw material is not melted by controlling the temperature. However, in the case where MgCl ₂ is adhered to the surface of the titanium raw material, it is preferable that a high vacuum is used to eliminate MgCl _{2 on the} surface in order to vaporize MgCl ₂ in the HDH process. In the HDH method related to this embodiment, it is important to optimize the temperature, time, vacuum, Ar replacement, and cost while reducing the amount of MgCl ₂ attached to the surface brought with the titanium raw material. .

In the hydrogenation step related to this embodiment mode, in order to prevent pores from being generated and remove MgCl ₂ (internal MgCl ₂ ) existing in the titanium, a hydrogenation step embodying the above-mentioned mechanism discovered in the present invention is completed. If it takes sufficient time to perform embrittlement by hydrogenation, MgCl ₂ can be discharged, but it is not suitable for productivity and cost in industry.

Investigation results showed that: because of the amount of MgCl ₂ is attached to the surface of the titanium material of the control, the amount of MgCl ₂ is present inside the titanium raw materials for the production control and cost concerning large influence. Various experiments have been carried out, and the results show that the total MgCl ₂ concentration of the titanium raw material must be suppressed below 1.0 mass%. In addition, the total MgCl ₂ concentration of the titanium raw material is preferably less than 0.05 mass%, and more preferably less than 0.001 mass%. In particular, it can be seen that if the MgCl ₂ concentration (internal MgCl ₂ concentration) existing in the titanium raw material is 0.5 mass% or less, the temperature of the titanium raw material is maintained at the melting point of MgCl ₂ (714 ° C) in the HDH method. The above time, which does not reach the eutectic temperature (1085 ° C) range of iron and titanium, is 90 minutes, and can still effectively eliminate the pores of MgCl ₂ . By setting the MgCl ₂ concentration (internal MgCl ₂ concentration) existing in the titanium raw material to 0.1 mass% or less, the effect performance is more clear. In the present invention, the MgCl ₂ concentration (internal MgCl ₂ concentration) trapped inside the titanium raw material is preferably 0.1 mass% or less, and more preferably 0.001 mass% or less.

[Method for suppressing pores in raw materials]

In addition, in the HDH method of the present invention, since titanium does not melt, pores due to the entrainment of Ar gas or the like are not generated.

As a method of reducing the total MgCl ₂ concentration of the titanium raw material to less than 1.0 mass%, and further suppressing the MgCl ₂ concentration (internal MgCl ₂ concentration) trapped inside the titanium raw material to less than 0.1 mass%, although it costs cost, It is also effective to further refine the titanium sponge and heat-treat it in a vacuum again.

In addition, the maximum thickness of the titanium raw material may be 20 mm or less, and preferably 10 mm or less. This is because the maximum thickness of the titanium raw material is 20 mm or less. During hydrogenation, hydrogen will sufficiently spread inside the raw material, embrittle the titanium, and rapidly crack.

[Definition of total MgCl ₂ concentration]

The measurement method of the total MgCl ₂ concentration is explained below. The chlorine concentration of the target titanium raw material was measured by the silver nitrate titration method (JIS H 1615), and the value of the chlorine concentration was converted into the MgCl ₂ concentration, which was determined as the MgCl ₂ concentration (total MgCl ₂ ) contained in the titanium raw material. concentration).

[Definition of internal MgCl ₂ concentration]

The measurement method of the internal MgCl ₂ concentration is described below. First, the target titanium raw material was subjected to a heat treatment at a reduced pressure (50 Pa or less) at about 750 ° C. for 1 hour, thereby dissipating the surface MgCl ₂ . Thereafter, by silver nitrate titration chlorine concentration (JIS H 1615) of measuring this material, whereby the value of the chlorine concentration in terms of the concentration of MgCl _2, MgCl will be trapped as the raw materials into the titanium _{concentration} exists inside ( Internal MgCl ₂ concentration).

[Explanation of the size of titanium powder]

By forming a titanium hydride powder having a pulverized surface, the probability that the pores remaining in the titanium hydride become cracked and opened will be further increased. The titanium hydride powder is pulverized and finely pulverized by passing through the pulverization process. Into a person. The finer the particle size of the titanium hydride powder, the higher the probability of pore opening. However, due to industrial cost and time constraints, the particle size of the titanium hydride powder is preferably 300 μm or less, and preferably 150 μm or less. Here, the particle diameter of the pulverized titanium hydride powder produced in the HDH method has a distribution, as long as 95% or more of the particle diameter of the perhydrogen titanium powder is the above value or less. That is, if the D95 particle diameter of the titanium hydride powder is reduced to 300 μm or less, and preferably 150 μm or less, a further effect is obtained. The lower limit side of the particle size of D95 is not particularly limited, but to give an example, it can be made to be 70 μm or more, or 80 μm or more. In the present invention, D95 means that in the particle size distribution measurement obtained by the laser diffraction / scattering method, the volume-based integral distribution has a particle size of 95%, respectively. Specifically, it is measured in accordance with JIS Z8825: 2013.

In addition, 95% or more of the total titanium particle diameter of the disintegrated titanium powder produced in the HDH method may be 150 μm or less.

[Application to spheroidization process]

In the titanium powder produced by the HDH method described above, the residue of MgCl ₂ is small. The titanium powder produced in the HDH method of the present invention is suitable as "to melt the surface of the titanium powder (for example, plasma melting), and to make the surface of the pulverized or disintegrated surface with an angular surface spherical. Into a spherical powder ". The disintegrated titanium powder produced by the HDH method has a pulverized surface or a disintegrated surface having a "concavo-convex structure". Therefore, its large surface area can promote the melting when it is introduced into the plasma. In addition, even if the surface of the titanium powder is melted for spheroidization, no plasma gas such as Ar is involved, and new pores can be suppressed.

The above findings: In order to suppress the generation of pores in the HDH method, the temperature, time, amount of hydrogen injection, material shape, and the amount of MgCl ₂ taken in (the total amount and the amount of MgCl ₂ enclosed) can be appropriately controlled as described above ) To achieve the present invention.

In this embodiment, titanium powder has been described. However, in titanium alloy powders in which titanium contains elements such as Al or V in an amount of 50% by mass or less, the titanium alloy of the raw material cannot be melted by controlling the temperature in the HDH method, and the same effect as that of titanium powder can be obtained. . The element contained in titanium is preferably 20% by mass or less, and more preferably 15% by mass or less. The titanium alloy powder may also contain various elements. For example, titanium alloy powder can also be made of Ti-Al-V alloy powder. In this case, the Ti-Al-V alloy powder may have an Al content of 5.5 to 7.5% by mass and a V content of 3.5 to 4.5% by mass.

[Explanation of pore area ratio of cross section]

With the manufacturing method of the titanium-based powder according to this embodiment, the following can be achieved: the cross-sectional area of the enclosed pores (hereinafter, the internal pores) appearing when an arbitrary cross section of the titanium-based powder is observed is divided by titanium The value of the cross-sectional area of the powder (cross-sectional area ratio of pores) is 0.3% or less. In addition, in the titanium-based powder produced in the present invention, it is preferable that the number of internal pores appearing when an arbitrary cross section of the titanium-based powder is observed is 20 per unit area / mm ² or less. Here, the so-called pore area ratio of the cross section of the titanium-based powder is 0.3% or less, which means that after the titanium-based powder is buried in the resin and polished, the cross-section can be observed at an optical microscope at a magnification of 500 μm × 500 μm. In the case of 16 positions, the cross-sectional area of the internal pores observed by making an image in the range of brightness of 90 to 250 by image processing, divided by the total cross-sectional area of the powder is 0.3% or less. The number of internal pores means the number of internal pores observed when the above-mentioned observation is performed by making an image in the range of brightness of 90 to 250 by image processing. In addition, in any observation, powders with a long diameter of 10 μm or less due to image processing were excluded. In addition, in the image processing, even if the internal pores appear to be open from the original image, the pores (Figure 1 is a picture before the image processing, and Figure 2 is a picture after the image processing) are excluded. In addition, even if it is shown that two pores are connected, as long as one internal pore is connected during image processing, it is still counted as one. In the present invention, the pore area ratio of the above-mentioned cross section is 0.3% or less. Therefore, the titanium powder manufactured in the manufacturing method related to the present invention is used in a technical field where the pores have to be small (such as aviation vehicle materials). As appropriate. On the other hand, if the pore area ratio of the cross-section exceeds 0.3%, it indicates that it is difficult to use it in this technical field.

『Examples』

[Example 1]

Sponge titanium was used as the titanium raw material. The titanium raw materials used are those whose total MgCl ₂ concentration and internal MgCl ₂ concentration are both 0.05 mass% or less and the diameter is 1/2 inch or less.

After 300 kg of the raw material was evacuated to 5 Pa or less, the gas environment was heated to 650 ° C with a heater and held for 120 minutes. After that, hydrogen was supplied and the reaction of hydrogen storage and exotherm was initiated. At the same time, the control of the heater or the Ar gas insertion and cooling device was operated, and the temperature of the titanium raw material was controlled to 1000 ° C or lower, and hydrogenation was performed for 120 minutes. The temperature range at this time is 716 ° C or higher and 1000 ° C or lower.

The bulk density of the titanium raw material at the time of hydrogenation was 1.2 g / cm ³ .

Thereafter, the titanium hydride bulk was pulverized by a pulverizer / classifier to obtain a titanium hydride powder having a particle diameter of 10 μm to 150 μm.

After the dehydrogenation treatment is performed in a vacuum heat treatment furnace, the dehydrogenated titanium bulk is subjected to a disintegration treatment. The D95 particle diameter of the obtained titanium powder was 100 μm.

An optical microscope photograph of the obtained titanium powder is shown in FIG. 3. After the titanium powder was embedded in the resin and the cross section of the sample was ground, 16 positions at any position of a size of 700 μm × 500 μm were observed with an optical microscope at a magnification of 500 times. As a result of analyzing the ratio of the number of pores to the area, the number of pores detected was 20 per unit area / mm ² . The pore area ratio was 0.11%.

[Example 2]

The chip powder of "a total MgCl ₂ concentration of 0.0002 mass% or less and a maximum thickness of 7 mm produced using a sponge titanium raw material having a total MgCl ₂ concentration of 0.1 mass% or less" was used as the titanium raw material. That is, the internal MgCl ₂ concentration of the titanium raw material is also 0.0002 mass% or less. After 300 kg of the raw material was evacuated to 5 Pa or less, the gas environment was heated to 650 ° C with a heater and held for 120 minutes. After that, hydrogen was supplied and a reaction for exothermic hydrogen storage was initiated. At the same time, the heater control or the Ar gas insertion and cooling device was operated, and the temperature of the titanium raw material was controlled to 1000 ° C. or lower, and hydrogenation was performed for 120 minutes. The temperature range at this time is 716 ° C or higher and 1000 ° C or lower.

The bulk density upon hydrogenation was 1.2 g / cm ³ . Thereafter, the titanium hydride bulk was pulverized with a pulverizer / classifier to obtain a titanium hydride powder having a particle diameter of 10 μm to 150 μm. After that, after performing dehydrogenation treatment in a vacuum heat treatment furnace condition, the dehydrogenated titanium bulk is subjected to disintegration treatment. The D95 particle diameter of the obtained titanium powder was 100 μm.

After the obtained titanium powder was buried in the resin and the cross section of the sample was ground, the optical microscope was used to observe 16 positions at any position of a size of 700 μm × 500 μm at a magnification of 500 times. The pores detected were per unit area. 8 pieces / mm ² . The pore area ratio was 0.02%.

Furthermore, in Example 2 described above, titanium powder was produced by using two kinds of iron concentrations of impurities in the titanium raw material as 200 mass ppm or less and more than 200 mass ppm and 500 mass ppm or less. In any case, the pores detected were 8 to 10 per unit area / mm ² . In any case, the pore area ratio was 0.02%. It is considered that it is the amount of iron in impurities, in other words, the purity of titanium, and it has nothing to do with the action of pores.

[Example 3]

90% Ti-6% Al-4% V (mass%) crumb powder manufactured using a sponge titanium raw material with a total MgCl ₂ concentration of 0.1 mass% or less and 60% Al-40% V alloy is used as the raw material. The titanium alloy chip powder used as a raw material has a total MgCl ₂ concentration of 0.0002 mass% or less, and a maximum thickness of 7 mm. That is, the internal MgCl ₂ concentration of the titanium alloy chip powder is also 0.0002 mass% or less. After 300 kg of the raw material was evacuated to 5 Pa or less, the gas environment was heated to 650 ° C with a heater and held for 120 minutes. After that, hydrogen is supplied and a reaction for exothermic hydrogen storage is initiated. At the same time, the heater control or the Ar gas insertion and cooling device is operated, and the hydrogenation is performed for 120 minutes while controlling the temperature of the titanium alloy chip powder to 1000 ° C or lower. The temperature range at this time is 716 ° C or higher and 1000 ° C or lower.

The bulk density upon hydrogenation was 1.2 g / cm ³ . Thereafter, the bulk of the titanium hydride was pulverized by a pulverizer / classifier to obtain a powder of 10 μm to 150 μm. After that, a dehydrogenation treatment is performed under a vacuum heat treatment furnace condition, and the dehydrogenated titanium bulk is subjected to a disintegration treatment. The D95 particle diameter of the obtained titanium powder was 100 μm.

After the obtained titanium alloy powder was buried in the resin and the cross section of the sample was ground, the optical microscope was used to observe 16 positions at any position of a size of 700 μm × 500 μm at a magnification of 500 times. The pores detected were per unit. Area 9 pcs / mm ² . The pore area ratio was 0.03%.

The titanium alloy powder obtained above was spheroidized by melting the surface with Ar gas as the plasma gas using a high-frequency thermal induction plasma device. The conditions for spheroidization are as shown in Table 1. An optical microscope photograph of the obtained titanium alloy powder is disclosed in FIG. 4. Titanium alloy powder was embedded in the resin, and the magnification of the cross section of the sample was set to 500 times with an optical microscope to observe 16 positions at any position of a size of 700 μm × 500 μm. As a result of analyzing the ratio of the number of pores to the area, the number of pores detected was 3 per unit area / mm ² . The pore area ratio was 0.01%. It is confirmed that the disintegrated titanium alloy powder produced by the HDH method is useful for the raw material powder of the spherical powder.

"Table 1"

[Example 4]

89% Ti-7% Al-4% V (mass%) crumb powder made from an alloy of sponge titanium raw material with a total MgCl ₂ concentration of 0.1 mass% or less and 70% Al-40% V is used as the raw material. The titanium alloy chip powder used as a raw material has a total MgCl ₂ concentration of 0.0002 mass% or less and a maximum thickness of 2 mm. That is, the internal MgCl ₂ concentration of the titanium alloy chip powder is also 0.0002 mass% or less. After 300 kg of the raw material was evacuated to 5 Pa or less, the gas environment was heated to 650 ° C with a heater and held for 120 minutes. After that, hydrogen is supplied and a reaction for exothermic hydrogen storage is initiated. At the same time, the heater control or the Ar gas insertion and cooling device is operated, and the hydrogenation is performed for 120 minutes while controlling the temperature of the titanium alloy chip powder to 1000 ° C or lower. The temperature range at this time is 716 ° C or higher and 1000 ° C or lower.

The bulk density upon hydrogenation was 1.2 g / cm ³ . Thereafter, the bulk of the titanium hydride was pulverized by a pulverizer / classifier to obtain a powder of 10 μm to 150 μm. After that, a dehydrogenation treatment is performed under a vacuum heat treatment furnace condition, and the dehydrogenated titanium bulk is subjected to a disintegration treatment. The D95 particle diameter of the obtained titanium powder was 100 μm.

After the obtained titanium alloy powder was buried in the resin and the cross section of the sample was ground, the optical microscope was used to observe 16 positions at any position of a size of 700 μm × 500 μm at a magnification of 500 times. The pores detected were per unit. The area is 9 pieces / mm ² . The pore area ratio was 0.03%.

Compared with the results of using the titanium shavings powder of Example 2, the results of using Ti—Al—V alloy and shavings powder of Examples 3 and 4 are equivalent. It is considered that the manufacturing method of the titanium powder related to this embodiment mode is also considered to be suitable for the manufacturing of titanium alloy powder.

[Comparative Example 1]

Titanium sponge having an internal MgCl ₂ concentration of 0.2 mass% was used as a titanium raw material, and titanium powder was produced under the same conditions as in Example 1. In addition, the total MgCl ₂ concentration of the sponge titanium was 0.3 mass%. After the obtained titanium powder was buried in the resin and the cross section of the sample was ground, the magnification was set to 500 times with an optical microscope to observe 16 positions at any position of a size of 700 μm × 500 μm. As a result of analyzing the number of pores and the area ratio, the number of pores detected was 85 per unit area / mm ² . The pore area ratio was 0.7%.

[Comparative Example 2]

The titanium powder manufactured in the gas atomization method with the same particle diameter as in Example 1 was purchased, and the cross section of the sample was buried in the resin, and then the magnification was set to 500 times with an optical microscope. 16 positions. As a result of analyzing the number of pores and the area ratio, the number of pores detected was 130 per unit area / mm ² . The pore area ratio was 1.0% (Fig. 5).

no.

<Fig. 1> is a diagram showing a method of image processing, especially a diagram showing pores in an inner package.

<Fig. 2> is a diagram showing a method of image processing, especially a diagram showing open fine holes.

<Fig. 3> is an optical microscope photograph of the titanium powder according to Example 1.

<Fig. 4> is an optical microscope photograph of the titanium powder according to Example 3.

<Fig. 5> is a photograph when image processing is performed on an optical microscope photograph of the titanium powder according to Comparative Example 2.

Claims (7)

A titanium-based powder in which a pore area ratio of a cross-sectional area occupied by pores in a cross-section of the titanium-based powder divided by an area of a cross-section of the titanium-based powder is 0.3% or less. The titanium-based powder according to claim 1, wherein the titanium-based powder is HDH powder. A method for producing a titanium-based powder, which is a method for producing a titanium-based powder by using a hydrogen-dehydrogenation method including a hydrogenation step, a pulverization step, and a dehydrogenation step, and a concentration of the total MgCl ₂ contained in the titanium-based raw material. It is 1.0 mass% or less, and the internal MgCl ₂ concentration is 0.1 mass% or less. The method for manufacturing a titanium-based powder according to claim 3, wherein a maximum thickness of the aforementioned titanium-based raw material is 20 mm or less. The method for producing a titanium-based powder according to claim 3, wherein in the aforementioned pulverizing step, the titanium hydride-based powder is pulverized to a D95 particle size of 300 μm or less. The method for producing a titanium-based powder according to claim 4, wherein in the aforementioned pulverizing step, the titanium hydride-based powder is pulverized to a D95 particle size of 300 μm or less. The method for producing a titanium-based powder according to any one of claim 3 to claim 6, wherein in the aforementioned hydrogenation step, it costs to adjust the temperature of the aforementioned titanium-based raw material to a range of 716 ° C to 1050 ° C. It was hydrogenated for more than 90 minutes.