METHOD FOR MANUFACTURING TITANIUM METAL POWDER OR TITANIUM ALLOY POWDER

Abstract

Provided is a method for producing highly pure titanium metal powder or titanium alloy powder which may be used in various fields. The method includes steps of: a) partially reducing each of at least one metal oxide and a titanium oxide; b) preparing a first mixture by mixing the partially reduced metal oxide and titanium oxide together; c) preparing a second mixture by mixing the first mixture with calcium hydride; and d) producing titanium metal or a titanium alloy by completely reducing the second mixture.

Claims

1.-13. (canceled)

14. A method for producing titanium metal powder or titanium alloy powder, the method comprising steps of: a) partially reducing each of at least one metal oxide and a titanium oxide; b) preparing a first mixture by mixing the partially reduced metal oxide and titanium oxide together; c) preparing a second mixture by mixing the first mixture with calcium hydride; and d) producing titanium metal or a titanium alloy by completely reducing the second mixture.

15. The method of claim 14, further comprising a step of partially reducing the first mixture, after step b) and before step c).

16. The method of claim 14, wherein the partial reduction in step a) and the complete reduction in step d) are performed by heat treatment at a temperature of 1,000° C. to 1,500° C. under a hydrogen atmosphere for 1 to 10 hours.

17. The method of claim 15, wherein the partial reduction in step a) and the complete reduction in step d) are performed by heat treatment at a temperature of 1,000° C. to 1,500° C. under a hydrogen atmosphere for 1 to 10 hours.

18. The method of claim 14, further comprising step of e) crushing and powdering the produced titanium metal or titanium alloy.

19. The method of claim 14, wherein the metal oxide is selected from the group consisting of CaO, V.sub.2O.sub.5, Cr.sub.2O.sub.3, Nb.sub.2O.sub.5, MoO.sub.3, WO.sub.3, Y.sub.2O.sub.3 and ZrO.sub.2.

20. The method of claim 14, wherein a stoichiometric ratio between the first mixture and the calcium hydride is 1:1.1 to 1.25.

21. The method of claim 14, wherein the second mixture further contains aluminum and vanadium oxide (V.sub.2O.sub.5) powders.

22. The method of claim 21, wherein the titanium alloy is Ti-6Al-4V.

23. The method of claim 14, wherein the titanium metal and the titanium alloy have an oxygen content of less than 0.3 wt % and a particle size distribution of less than 50 μm.

24. Titanium metal powder or titanium alloy powder produced by the method of claim 14 and having an oxygen content of less than 0.3 wt % and a particle size distribution of less than 50 μm.

25. A method for producing titanium metal powder or titanium alloy powder, the method comprising steps of: a) partially reducing one of at least one metal oxide and a titanium oxide; b) preparing a first mixture by mixing the partially reduced one with the other of the metal oxide and the titanium oxide; c) preparing a second mixture by mixing the first mixture with calcium hydride; and d) producing titanium metal or a titanium alloy by completely reducing the second mixture.

26. The method of claim 25, further comprising a step of partially reducing the first mixture, after step b) and before step c).

27. The method of claim 25, wherein the partial reduction in step a) and the complete reduction in step d) are performed by heat treatment at a temperature of 1,000° C. to 1,500° C. under a hydrogen atmosphere for 1 to 10 hours.

28. The method of claim 26, wherein the partial reduction in step a) and the complete reduction in step d) are performed by heat treatment at a temperature of 1,000° C. to 1,500° C. under a hydrogen atmosphere for 1 to 10 hours.

29. The method of claim 25, further comprising step of e) crushing and powdering the produced titanium metal or titanium alloy.

30. The method of claim 25, wherein the metal oxide is selected from the group consisting of CaO, V.sub.2O.sub.5, Cr.sub.2O.sub.3, Nb.sub.2O.sub.5, MoO.sub.3, WO.sub.3, Y.sub.2O.sub.3 and ZrO.sub.2.

31. The method of claim 25, wherein a stoichiometric ratio between the first mixture and the calcium hydride is 1:1.1 to 1.25.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0022] FIG. 1 depicts scanning electron micrograph showing the morphology of the titanium metal powder produced according to the present invention.

[0023] FIG. 2 is an X-ray diffraction pattern showing the material phase of the titanium metal powder produced according to the present invention.

[0024] FIG. 3 is a view showing the particle size distribution of the titanium metal powder produced according to the present invention.

[0025] FIG. 4 depicts scanning electron micrographs showing the morphology of the titanium alloy (Ti-6Al-4V) powder produced according to the present invention.

[0026] FIG. 5 is a view showing the particle size distribution of the titanium alloy (Ti-6Al-4V) powder product produced according to the present invention.

MODE FOR INVENTION

[0027] All technical terms used in the present invention have the following definitions, unless otherwise defined, and have the same meanings as commonly understood by those skilled in the art to which the present invention pertains. In addition, although preferred methods or samples are described in the present specification, those similar or equivalent thereto are also included within the scope of the present invention.

[0028] The term “about” refers to an amount, level, value, number, frequency, percentage, dimension, size, weight, or length that varies by as much as 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2 or 1% to a reference amount, level, value, number, frequency, percentage, dimension, size, weight, or length.

[0029] Throughout this specification, unless the context requires otherwise, the terms “comprise,” “comprises” and “comprising” will be understood to imply the inclusion of a stated step or component or group of steps or components but not the exclusion of any other step or component or group of steps or components.

[0030] The method for producing titanium metal powder or titanium alloy powder in any form according to the present invention is characterized by comprising multiple reduction steps. Preferably, the method is characterized by comprising two reduction steps. More preferably, the method comprises the following steps:

[0031] a) partially reducing each of at least one metal oxide and a titanium oxide (first reduction step);

[0032] b) preparing a first mixture by mixing the partially reduced metal oxide and titanium oxide together (first mixing step);

[0033] c) preparing a second mixture by mixing the first mixture with calcium hydride (second mixing step); and

[0034] d) producing titanium metal or a titanium alloy by completely reducing the second mixture (second reduction step).

[0035] According to one embodiment of the present invention, the method further comprises step e) of crushing and powdering the produced titanium metal or titanium alloy (powdering step).

[0036] Hereinafter, each step will be described in detail.

[0037] First, each of at least one metal oxide and a titanium oxide is partially reduced (first reduction step).

[0038] The first reduction step may be performed by heat-treating each of the metal oxide and the titanium oxide as raw materials at a temperature of 1,000° C. to 1,500° C. under a hydrogen atmosphere for 1 to 10 hours. The heat-treatment temperature may preferably be 1,100° C. to 1,300° C., more preferably 1,100° C. to 1,200° C. The heat-treatment time may preferably be 2 to 4 hours. The hydrogen atmosphere may be provided by a hydrogen gas flow of 1.5 l/min or more, preferably 1.5 l/min to 5 l/min, which may vary depending on the size of a heat-treatment furnace and the amounts of the raw materials.

[0039] In the first reduction step, the metal oxide or the titanium oxide is placed in a semicircular cross-sectional crucible made of stainless steel and is heated in the heat treatment zone of a furnace. The heat treatment furnace used may be a tube furnace. The heat treatment furnace that is used in the present invention may have two separate heat treatment zones for the first reduction step and the second reduction step. It is preferable to use any type of heating furnace that is operated under a gas atmosphere capable of promoting the reduction reaction occurring at a temperature of up to 1,500° C. The heat treatment furnace should be suitable for work using a gas such as hydrogen or argon.

[0040] Each of the heat treatment zones may individually form a hydrogen gas flow.

[0041] In this step, the oxygen contents of the metal oxide and the titanium oxide as raw materials may be decreased by heat treatment, and oxides that may be easily reduced in the second reduction step may be formed.

[0042] The metal oxide may be at least one selected from the group consisting of CaO, V.sub.2O.sub.5, Cr.sub.2O.sub.3, Nb.sub.2O.sub.5, MoO.sub.3, WO.sub.3, Y.sub.2O.sub.3 and ZrO.sub.2, and is preferably CaO. The titanium oxide may be TiO.sub.2 or TiO, and is more preferably TiO.sub.2.

[0043] According to one embodiment of the present invention, in the case in which titanium alloy powder is to be produced, the metal oxide may be CaO and V.sub.2O.sub.5, and aluminum or aluminum oxide may further be used together with the metal oxide. In this case, the titanium alloy powder may be Ti-6Al-4V.

[0044] The metal oxide and the titanium oxide are preferably in a powder form.

[0045] According to one embodiment of the present invention, the first reduction step may consist of: a1) a first partial reduction step of partially reducing each of calcium oxide and titanium oxide; and a2) a second partial reduction step of partially reducing a first mixture obtained by mixing the partially reduced calcium oxide and titanium oxide together.

[0046] By dividing the first reduction step into two steps as described above, it is possible to obtain a mixture of uniformly reduced calcium oxide and titanium oxide.

[0047] According to another embodiment of the present invention, only one of the metal oxide and the titanium oxide may be partially reduced in the first reduction step.

[0048] Thereafter, a first mixture is prepared by mixing the partially reduced metal oxide and titanium oxide together (first mixing step), and a second mixture is prepared by mixing the first mixture with calcium hydride (second mixing step).

[0049] In this step, the first mixture and calcium hydride are preferably mixed together in a stoichiometric ratio of 1:1.1 to 1.25.

[0050] The calcium hydride may be in a powder or granule form, and the particle size thereof may preferably be 0.02 to 2 mm. The calcium hydride that is used in the present invention may be a commercially available product, but it is preferable that the calcium hydride that is used in the present invention be calcium hydride shavings or granules obtained by heating calcium metal shavings or calcium metal granules at a temperature of 550 to 750° C. under a hydrogen gas atmosphere for 1 to 10 hours.

[0051] Next, a step (second reduction step) of producing titanium metal or a titanium alloy by completely reducing the second mixture by heat treatment is performed.

[0052] The heat treatment may be performed at a temperature of 1,000° C. to 1,500° C. under a hydrogen atmosphere for 1 to 10 hours. The heat-treatment temperature may preferably be 1,100° C. to 1,300° C., more preferably, 1,100° C. to 1,200° C. The heat-treatment time may preferably be 2 to 4 hours. The hydrogen atmosphere may be provided by a hydrogen gas flow of 1.5 l/min or more, preferably 1.5 l/min to 5 l/min, which may vary depending on the size of a heat-treatment furnace and the amount of the mixture. The heat treatment furnace that is used in the second reduction step is as described above with respect to the first reduction step.

[0053] In this step, a mixture of the partially reduced metal oxide and titanium oxide may react with calcium hydride as a reducing agent under a hydrogen atmosphere to form titanium metal or a titanium alloy. The titanium metal or titanium alloy thus formed is recovered.

[0054] Finally, the powder obtained in recovery step e) may be powdered following a washing and drying step. According to one embodiment of the present invention, the recovered titanium metal or titanium alloy is in a bulk form, and thus may be crushed using a high-energy ball milling device before the washing and drying step.

[0055] In the washing and drying step, the crushed powder may be mixed with water to form a slurry which may then be washed with agitation. In order to improve the washing effect, a solvent such as acetic acid may be added to the slurry.

[0056] In the drying step after washing, the powder may be dried in an open low-temperature oven at a temperature of 80 to 90° C.

[0057] The titanium metal or titanium alloy produced in the present invention is in the form of powder, has a particle size distribution of 50 μm or less, preferably 10 to 50 μm, and an oxygen content of less than 0.3 wt %.

[0058] As used herein, the term “powder” refers to one having a particle size of less than 1 mm.

[0059] As used herein, “X50” refers to the particle size distribution of the final powder, and indicates the median diameter or the median value of the particle size distribution. Preferably, X50 indicates a particle size distribution of 50 μm or less, or 40 μm or less, more preferably 20 μm or less.

[0060] Hereinafter, the present invention will be detail with reference to examples, but the scope of the present invention is not limited by these examples.

EXAMPLES

[0061] The starting materials used in the Examples of the present invention are shown in Table 1 below.

TABLE-US-00001 TABLE 1 Starting material Purity Manufacturer TiO.sub.2 (rutile) 99% 325 mesh Beijing Toodudu Ltd- China powder or less Aluminum 99.5% 325 mesh Xinkang Advanced Materials powder or less Co. ltd- China Calcium oxide 99.5% 325 mesh Ganzhou Wanfeng Advanced powder or less Materials Tech Co. ltd- China CaH.sub.2 powder 99% 325 mesh NAP Co. Ltd. or less V.sub.2O.sub.5 99.6% 325 mesh Ganzhou Wanfeng Advanced or less Materials Tech. Co. ltd- China

[0062] Instruments used to analyze the titanium metal powder and titanium alloy powder finally produced in the present invention are shown in Table 2 below.

TABLE-US-00002 TABLE 2 Manufacturer and Instrument name model Remarks Inductively Coupled Perkin Elmer, Optima Analysis of chemical Plasma Atomic 3300DV composition Emission Spectrometry (ICP) X-Ray Diffraction Rigaku, DMAX 2200 X-ray diffraction test Machine Particle Size Beckman Coulter, Analysis of particle Analyzer LS230 size distribution ONH Analyzer ELTRA GmbH, Gas analysis ELTRA ONH-2000 SEM JEOL, JSM-6380 Scanning electron microscopy

Example 1: Production of Titanium Metal Powder

[0063] Each of 50 g of 99.5% pure CaO powder and 50 g of 99% pure TiO.sub.2 powder was placed in a SUS310S crucible and partially reduced in the heat-treatment zone of a tube furnace at 1,100° C. under a hydrogen gas atmosphere with 2 to 3 L/min for 2 hours. 100 g of a first mixture obtained by mixing the partially reduced CaO and TiO.sub.2 together was completely mixed with 130 g of calcium hydride powder (particle size: 0.02 to 2 mm), thus preparing a second mixture. The stoichiometric ratio of the calcium hydride to the first mixture was 1.1 to 1.25x. Then, the second mixture was placed in a SUS310S crucible and completely reduced in the heat treatment zone of a tube furnace at 1,100° C. under a hydrogen gas atmosphere with 2 to 3 l/min for 2 hours. The obtained bulk material was placed in a ball milling device, crushed, mixed with water and acetic acid, washed with agitation, and completely dried at 90° C. The physical properties of the metal powder were measured using the instruments shown in Table 2 above. Scanning electron micrographs of the produced powder are shown in FIG. 1. In addition, to examine the material phase of the produced powder, the X-ray diffraction pattern of the produced powder was measured, and the results are shown in FIG. 2. The particle size distribution of the powder was measured and the results are shown in FIG. 3 and Table 3 below. Referring to FIG. 2, it can be confirmed that the produced powder is titanium (Ti) metal. In addition, referring to FIG. 3 and Table 3 below, it can be confirmed that the particle size distribution range of the produced powder is 10 to 50 μm. In addition, it was confirmed that the residual oxygen content of the produced powder was 0.19 wt %. The residual oxygen content of the titanium metal powder produced in the present invention is significantly lower than that of the titanium metal powder produced by a known method.

TABLE-US-00003 TABLE 3 Diameter Particle size 1 Diameter at X10  2.86 μm 2 Diameter at X50  9.07 μm 3 Diameter at X90 20.20 μm 4 Mean diameter 10.45 m

Example 2: Production of Titanium Alloy (Ti-6Al-4V) Powder

[0064] 150 g of a mixture of 99.5% pure CaO powder and 99% pure TiO.sub.2 powder was placed in a SUS310S crucible and partially reduced in the heat treatment zone of a tube furnace at 1,100° C. under a hydrogen gas atmosphere with 2 to 3 L/min for 2 hours. A first mixture obtained by mixing the partially reduced CaO and TiO.sub.2, 7.13 g of 99.6% pure V.sub.2O.sub.5 powder and 6 g of 99.5% pure aluminum metal powder was completely mixed with 207 g of calcium hydride powder (particle size: 0.02 to 2 mm), thus preparing a second mixture. The stoichiometric ratio of the calcium hydride to the first mixture was 1.1 to 1.25x. Then, the second mixture was placed in a SUS310S crucible and completely reduced in the heat treatment zone of a tube furnace at 1,100° C. under a hydrogen gas atmosphere with 2 to 3 l/min for 2 hours. The obtained bulk material was placed in a ball milling device, crushed, mixed with water and acetic acid, washed with agitation, and completely dried at 90° C. The physical properties of the metal powder were measured using the instruments shown in Table 2 above. Scanning electron micrographs of the produced powder are shown in FIG. 4. In addition, the particle size distribution of the produced powder was measured and the results are shown in FIG. 5 and Table 4 below. Referring to FIG. 5 and Table 4 below, it can be confirmed that the particle size distribution range of the produced powder is 10 to 50 μm. In addition, it was confirmed that the residual oxygen content of the produced powder was 0.28 wt %. The residual oxygen content of the titanium metal powder produced in the present invention is significantly lower than that of the titanium metal powder produced by a known method.

TABLE-US-00004 TABLE 4 Diameter Particle size 1 Diameter at X10  3.69 μm 2 Diameter at X50 13.48 μm 3 Diameter at X90 39.48 μm 4 Mean diameter 17.95 m

Example 3: Production of Titanium Alloy (Ti-6Al-4V) Powder

[0065] 150 g of a mixture of 99.5% pure CaO powder and 99% pure TiO.sub.2 powder was placed in a SUS310S crucible and partially reduced in the heat treatment zone of a tube furnace at 1,100° C. under a hydrogen gas atmosphere with 2 to 3 L/min for 2 hours. A first mixture obtained by mixing the partially reduced CaO and TiO.sub.2, 7.13 g of 99.6% pure V.sub.2O.sub.5 powder and 7.1 g of 99.5% pure aluminum oxide powder was completely mixed with 207 g of calcium hydride powder (particle size: 0.02 to 2 mm), thus preparing a second mixture. The stoichiometric ratio of the calcium hydride to the first mixture was 1.1 to 1.25x. Then, the second mixture was placed in a SUS310S crucible and completely reduced in the heat treatment zone of a tube furnace at 1,100° C. under a hydrogen gas atmosphere with 2 to 3 l/min for 2 hours. The obtained bulk material was placed in a ball milling device, crushed, mixed with water and acetic acid, washed with agitation, and completely dried at 90° C. to obtain titanium alloy (Ti-6Al-4V) powder.

[0066] Although the present invention has been described in detail with reference to the specific features, it will be apparent to those skilled in the art that this detailed description is only of a preferred embodiment thereof, and does not limit the scope of the present invention. Thus, the substantial scope of the present invention will be defined by the appended claims and equivalents thereto.