WO2019088007A1 - Method for purifying titanium material - Google Patents

Method for purifying titanium material Download PDF

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Publication number
WO2019088007A1
WO2019088007A1 PCT/JP2018/040049 JP2018040049W WO2019088007A1 WO 2019088007 A1 WO2019088007 A1 WO 2019088007A1 JP 2018040049 W JP2018040049 W JP 2018040049W WO 2019088007 A1 WO2019088007 A1 WO 2019088007A1
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Prior art keywords
titanium
titanium material
hydrogen
melting
dissolution
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PCT/JP2018/040049
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French (fr)
Japanese (ja)
Inventor
大介 松若
尚之 成島
恭介 上田
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株式会社神戸製鋼所
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Application filed by 株式会社神戸製鋼所 filed Critical 株式会社神戸製鋼所
Priority to RU2020114609A priority Critical patent/RU2738280C1/en
Priority to US16/755,358 priority patent/US20200239979A1/en
Priority to EP18874635.8A priority patent/EP3705588B1/en
Priority to CN201880068865.8A priority patent/CN111279000B/en
Publication of WO2019088007A1 publication Critical patent/WO2019088007A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B34/00—Obtaining refractory metals
    • C22B34/10—Obtaining titanium, zirconium or hafnium
    • C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B34/00—Obtaining refractory metals
    • C22B34/10—Obtaining titanium, zirconium or hafnium
    • C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
    • C22B34/1295—Refining, melting, remelting, working up of titanium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/04—Refining by applying a vacuum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/05—Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/16—Remelting metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/02—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working in inert or controlled atmosphere or vacuum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
    • C22F1/18—High-melting or refractory metals or alloys based thereon
    • C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon

Definitions

  • the present invention relates to a method of purifying titanium material that removes oxygen and hydrogen contained in titanium material from titanium material consisting of pure titanium, titanium alloy, or intermetallic compound containing titanium as one of main components. It is about
  • titanium such as pure titanium and titanium alloy
  • properties such as light weight, high corrosion resistance and high specific strength.
  • titanium is active, it is also called an active metal, and is very easily associated with light elements such as oxygen and nitrogen, and once it is combined with these light elements, removal becomes very difficult.
  • titanium has excellent properties, but such a problem that removal of light elements once bonded is difficult, and further a problem that it is expensive compared to conventionally used steel materials and aluminum materials. In the current situation, it has not spread to the market.
  • Non-Patent Document 1 and Non-Patent Document 2 are technical documents describing a method of removing oxygen contained in a titanium material such as pure titanium or titanium alloy using hydrogen.
  • Non-Patent Document 1 describes that oxygen can be reduced by arc melting sponge titanium or a Ti-6Al-4V alloy in an Ar- (1 to 30) volume% H 2 atmosphere.
  • sponge titanium when sponge titanium is used as a raw material, it is described that an oxygen concentration falls from 0.04 mass% to 0.016 mass%.
  • Ti-6Al-4V When Ti-6Al-4V is used as a raw material, the oxygen concentration decreases from 0.12% by mass to 0.028% by mass, and the oxygen concentration is 1.6% by mass to 0.3% by mass It is described that it decreases.
  • Non-Patent Document 2 describes that oxygen can be reduced by plasma arc melting pure titanium in an Ar-20 volume% H 2 atmosphere. Also, it is described that the oxygen concentration decreases from the initial oxygen concentration of 0.23% by mass to 0.09% by mass.
  • Non-Patent Document 1 describes the use of ICP analysis as an oxygen analysis method, but does not specifically describe under what experiment conditions data were obtained.
  • ICP analysis it is difficult to accurately analyze the oxygen concentration in a sample due to the presence of oxygen atoms contained in water molecules used in preparing a solution for quantitative analysis.
  • the graph which shows a time-dependent change of the oxygen concentration in a sample is also described by the nonpatent literature 2, the oxygen reduction effect beyond this is hard to be anticipated from the inclination of the described graph.
  • the present invention has been made in view of the above-mentioned conventional circumstances, and it is possible to contain oxygen, and hydrogen contained from titanium material consisting of pure titanium, titanium alloy or an intermetallic compound containing titanium as one of the main components.
  • An object of the present invention is to provide a method of purifying a titanium material which can be reliably removed.
  • the method for purifying a titanium material according to the present invention is a titanium material for removing oxygen contained in the titanium material from a titanium material consisting of pure titanium, a titanium alloy, or an intermetallic compound containing titanium as one of its main components.
  • each of the first dissolution step and the second dissolution step is performed one or more times.
  • a vacuum degree is 1 ⁇ 10 ⁇ 2 to 1 ⁇ 10 ⁇ 4 Pa and a holding temperature is 600 to 1200 ° C. for 15 minutes or more after completion of the second melting step. It is preferable to further have a heat treatment step of removing hydrogen from the titanium material by holding.
  • the method for purifying a titanium material of the present invention it is possible to reliably remove oxygen and hydrogen contained in titanium material consisting of pure titanium, titanium alloy or an intermetallic compound containing titanium as one of the main components. Can.
  • the present inventors have purified a titanium material that can reliably remove the light element contained in the titanium material, particularly oxygen, from a titanium material whose main component is titanium, which is very easily combined with light elements such as oxygen and nitrogen.
  • the first melting step of introducing hydrogen by dissolving the titanium material in a rare gas atmosphere containing a certain amount of hydrogen, and subsequently dissolving the titanium material in a rare gas atmosphere By carrying out the second dissolution step of removing the contained oxygen together with the hydrogen introduced in one step, it was found that the oxygen contained in the titanium material can be reliably removed, and the present invention has been completed.
  • the reason why the oxygen contained in the titanium material can be removed from the titanium material together with the hydrogen introduced in the first dissolution step in the second dissolution step is considered to be because the introduced hydrogen functions as a deoxidizer.
  • the titanium material used in the method of purifying titanium material according to the present invention has either pure titanium, a titanium alloy, or an intermetallic compound of titanium (an intermetallic compound containing titanium as one of its main components) .
  • pure titanium JIS1 class, JIS class 2, JIS class 3, JIS class 4 industrial pure titanium can be illustrated, and as an alloy element which titanium alloy contains, Al, V, Mo, Cr, Zr, Sn, Si, Cu, Nb, Fe, Ni, Ta, Ag, Pd, C, N can be exemplified, and TiAl and NiTi can be exemplified as the intermetallic compound.
  • the titanium content of these titanium materials is preferably 45% by mass or more.
  • the lower limit of the titanium content of the titanium material is about this level, and when the titanium content is too small, it can not be called a titanium material.
  • the purification method of titanium of the present invention at least includes a first dissolution step and a second dissolution step.
  • the first dissolution step and the second dissolution step are each performed one or more times.
  • it divides into a 1st melt
  • the first melting step is a step for introducing hydrogen into the titanium material, and is a pretreatment step for removing oxygen from the titanium material.
  • oxygen can be reduced by carrying out the step corresponding to the first dissolution step.
  • oxygen can not be removed from the titanium material only by the first melting step. Although it describes as a comparative example in the column of a subsequent Example, oxygen can not fully be removed from a titanium raw material only by implementing this 1st melt
  • hydrogen is introduced into the titanium material melt by melting the titanium material in a rare gas atmosphere containing 5 to 70% by volume of hydrogen using, for example, a plasma arc melting furnace.
  • the melting in the first melting step is preferably performed by plasma arc melting.
  • heating and hydrogen introduction can be simultaneously performed by mixing hydrogen in the plasma gas.
  • dissolution the apparatus etc. which introduce hydrogen gas separately from a heat source will be needed, and it will lead to the rise of manufacturing cost.
  • the reason for setting the atmosphere of the first melting step to a rare gas atmosphere containing 5 to 70% by volume of hydrogen (5% to 70% by volume) is that the hydrogen concentration is 70 volumes, especially in the case of plasma arc melting. If it exceeds 10%, the energy required for ionization will rise, and the arc loss will be frequent with the rise in voltage, making it difficult to generate a plasma arc. On the other hand, if the hydrogen concentration is less than 5% by volume, hydrogen can not be sufficiently introduced into the titanium melt.
  • the lower limit of the hydrogen content is preferably 10% by volume or more, more preferably 15% by volume or more.
  • the upper limit of the hydrogen content is preferably 60% by volume or less, more preferably 50% by volume or less.
  • the atmosphere in the first melting step is a rare gas atmosphere containing 5 to 70% by volume of hydrogen, but an Ar atmosphere can be exemplified as the rare gas atmosphere.
  • the atmosphere of the first melting step is He atmosphere, Ne atmosphere, etc., deoxidation is theoretically possible.
  • the amount of heat input in the first melting step is not particularly specified, but is preferably in the range of 15 to 200 kW / kg (15 kW / kg or more and 200 kW / kg or less). If the amount of heat input is less than 15 kW / kg, the amount of heat necessary to dissolve titanium can not be secured. On the other hand, if the heat input exceeds 200 kW / kg, volatilization loss of titanium will occur.
  • the dissolution holding time in the first dissolution step is not particularly specified, but is preferably in the range of 0.3 to 3.6 ks (5 to 60 minutes).
  • the lower limit of the dissolution holding time is more preferably 0.6 ks (10 minutes) and the upper limit is 1.8 ks (30 minutes). If the solution retention time is less than 0.3 ks (5 minutes), sufficient hydrogen introduction for deacidification can not be achieved. On the other hand, even if the solution holding time exceeds 3.6 ks (60 minutes), the heat and the volatilization of titanium only increase the loss.
  • This first dissolution step is usually carried out only once, but may be carried out again after the second dissolution step.
  • the first dissolution step may be repeated twice or more continuously. It should be noted that whether the operation is performed only once or performed plural times can be based on the fact that the oxygen concentration is reduced to 80% or less compared to that before the treatment.
  • the second melting step is a step of removing oxygen contained in the titanium material from the melt of the titanium material together with hydrogen introduced into the titanium material in the first melting step.
  • the dissolution in the first dissolution step is desirably performed by plasma arc dissolution
  • the dissolution in the second dissolution step is also preferably performed by plasma arc dissolution.
  • the first melting step by performing plasma arc melting of the titanium material, it is possible to raise the temperature of the melt above other processes.
  • dissolution it is estimated that deoxidation efficiency declines slightly with temperature fall.
  • the atmosphere in the second melting step is a rare gas atmosphere such as Ar, He, or Ne.
  • the atmosphere in the first melting step is an Ar atmosphere containing 5 to 70% by volume of hydrogen
  • the second melting step may be an Ar atmosphere using the same kind of rare gas as the first melting step. Preferred for efficiency.
  • the atmosphere in the second melting step may be another rare gas such as He or Ne as in the first melting step.
  • the oxygen contained in the titanium material is reliably removed from the melt of the titanium material together with the hydrogen introduced into the titanium material in the first melting step by setting it to a rare gas atmosphere not containing hydrogen. can do.
  • a rare gas atmosphere not containing hydrogen hydrogen is contained in a very small amount (less than 5% by volume) if it does not affect the removal of hydrogen and oxygen from the melt of titanium material. It does not matter.
  • the amount of heat input in the second melting step is preferably in the range of 15 to 200 kW / kg as in the first melting step. If the amount of heat input is less than 15 kW / kg, the amount of heat necessary to dissolve titanium can not be secured. On the other hand, if the heat input exceeds 200 kW / kg, volatilization loss of titanium will occur.
  • the dissolution holding time in the second dissolution step is not particularly specified as in the dissolution holding time in the first dissolution step, but is in the range of 0.3 to 3.6 ks (5 to 60 minutes).
  • the lower limit is preferably 0.6 ks (10 minutes) and the upper limit is preferably 1.8 ks (30 minutes). If the dissolution holding time is less than 0.3 ks (5 minutes), sufficient time for deoxidation can not be secured. On the other hand, even if the solution holding time exceeds 3.6 ks (60 minutes), the heat and the volatilization of titanium only increase the loss.
  • This second dissolution step is usually performed only once as in the first dissolution step, but may be performed a plurality of times as in the first dissolution step.
  • the second dissolving step may be carried out repeatedly in combination with the first dissolving step a plurality of times, or even if only the second dissolving step is carried out a plurality of times after the first dissolving step is completed. I do not care.
  • whether the hydrogen concentration is reduced to 5.0 ⁇ 10 ⁇ 2 mass% or less can be used as a judgment standard whether the operation is performed only once or plural times.
  • the vacuum degree is maintained at 0.9 ks (15 minutes) or more under the conditions of 1 ⁇ 10 ⁇ 2 to 1 ⁇ 10 4 Pa and the holding temperature of 600 to 1200 ° C. carry out.
  • this heat treatment step does not necessarily need to be carried out, by carrying out the heat treatment step, it is possible to surely remove hydrogen which could not be removed in the second dissolution step.
  • the heat treatment step is carried out using a vacuum heat treatment furnace or the like, and the degree of vacuum at that time is in the range of 1 ⁇ 10 ⁇ 2 to 1 ⁇ 10 ⁇ 4 Pa.
  • the upper limit of the degree of vacuum is set to 1 ⁇ 10 -4 Pa because a degree of vacuum exceeding 1 ⁇ 10 -4 Pa is preferable for the purpose of dehydrogenation, but for exhausting to the above-mentioned degree of vacuum It is because it has a long time and the efficiency is bad.
  • the reason why the lower limit of the vacuum degree is 1 ⁇ 10 -2 Pa is that at a vacuum degree of less than 1 ⁇ 10 -2 Pa, an oxide film is formed on the titanium surface and hydrogen removal is inhibited by the oxide film. It is because it
  • the holding temperature in the heat treatment step is set to 600 to 1200 ° C.
  • the lower limit of the holding temperature is set to 600 ° C., because if the holding temperature is lower than that, the diffusion rate of hydrogen in the solid titanium material becomes slow and dehydrogenation takes a long time and the efficiency is poor.
  • the reason for setting the upper limit of the holding temperature to 1200 ° C. is that if the holding temperature is higher than that, the formation of the oxide film on the titanium surface becomes active and the time required for cooling becomes long.
  • the holding time in the heat treatment step is set to 0.9 ks (15 minutes) or more. If the retention time is less than 0.9ks (15 minutes), there is a high possibility that the hydrogen in the titanium material that could not be removed in the second dissolution step can not be removed, and the retention time is 0.9ks (15 minutes) By the above, it is possible to reliably remove the hydrogen in the titanium material which could not be removed in the second dissolving step.
  • the first melting step and the second melting step in a plasma arc melting furnace and the heat treatment step in a vacuum heat treatment furnace under test conditions. It carried out according to the order.
  • the hearth used for melting the titanium material was a hemispherical shape with a diameter of 80 mm.
  • a titanium material is added so that the height is about 25 mm in the case of 250 g of titanium melt mass (sample mass), and the height is about 40 mm in the case of 500 g of titanium melt mass (sample mass) I put the titanium material like.
  • the dissolution output by plasma arc in the first dissolution step is 70 V, 500 A
  • the dissolution output in the second dissolution step is 50 V, 450 A
  • the dissolution time in the first dissolution step is 0.3 to 3.6 ks ( In the range of 5 to 60 minutes, the flow rate was 30 L / min
  • the dissolution time in the second dissolution step was in the range of 0.3 to 3.6 ks (5 to 60 minutes)
  • the flow rate was 20 L / min.
  • the amount of heat input in the first melting step and the second melting step is 114 kW / kg
  • the pressure in the furnace is 1 atm.
  • the titanium raw material was used as a dissolution raw material, and the first dissolution step and the second dissolution step were sequentially performed one or more times as a dissolution step, and a heat treatment step was performed as needed.
  • the first melting step was carried out as the melting step using the titanium material as the melting raw material, and the heat treatment step was carried out as needed.
  • the atmosphere in the first dissolution step was an Ar atmosphere in which 30 volume% of hydrogen was mixed
  • the atmosphere in the second dissolution step was an Ar atmosphere (pure Ar atmosphere) in which hydrogen was not mixed.
  • the sample after the melting step was placed on an Al 2 O 3 boat covered with a Ti sheet, and vacuum was applied by a vacuum pump until it reached 7.0 ⁇ 10 ⁇ 3 Pa. Thereafter, the temperature was raised to 1023 K (750 ° C.) while keeping the vacuum state (7.0 ⁇ 10 ⁇ 3 Pa), and the holding time was maintained for 3.6 ks (60 minutes).
  • the outermost surface of the titanium material (sample) before the test and the sample after finishing the final process may be the first dissolution process, the second dissolution process, or the heat treatment process depending on the test conditions).
  • a sample was taken from the surface, and the oxygen concentration of the sample before the test and the oxygen concentration and hydrogen concentration of the sample after the final step were measured by the inert gas melting infrared absorption method and evaluated. Hydrogen analysis is a semi-quantitative method. The test results are shown in Table 1.
  • the hydrogen introduced into the titanium material in the first dissolution step functions as a deoxidizing agent in the second dissolution step, and the oxygen contained in the titanium material is removed from the titanium material together with the hydrogen.

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Abstract

This method for purifying a titanium material is a deoxidization method for removing oxygen contained in a titanium material from the titanium material that is formed from pure titanium, a titanium alloy or an intermetallic compound that contains titanium as one of the main components. This method for purifying a titanium material comprises: a first melting step wherein hydrogen is introduced into the titanium material in a molten state by melting the titanium material in a rare gas atmosphere containing 5-70% by volume of hydrogen; and a second melting step wherein oxygen contained in the titanium material is removed together with hydrogen from the titanium material in a molten state by melting the titanium material, into which hydrogen has been introduced during the first melting step, in a rare gas atmosphere. The first melting step and the second melting step are carried out one or more times, respectively.

Description

チタン素材の精製方法Purification method of titanium material
　本発明は、純チタン、チタン合金、或いはチタンを主成分の１つとして含有する金属間化合物でなるチタン素材から前記チタン素材中に含有される酸素、更には水素を除去するチタン素材の精製方法に関するものである。 The present invention relates to a method of purifying titanium material that removes oxygen and hydrogen contained in titanium material from titanium material consisting of pure titanium, titanium alloy, or intermetallic compound containing titanium as one of main components. It is about
　近年、軽量、高耐食性、高比強度といった特性を活かし、特に航空機や自動車などの輸送機用の金属素材として純チタンやチタン合金などのチタンの需要が増加している。 In recent years, the demand for titanium, such as pure titanium and titanium alloy, has been increasing as a metal material for transportation machines such as aircrafts and automobiles, taking advantage of properties such as light weight, high corrosion resistance and high specific strength.
　チタンは活性であるため活性金属とも呼ばれ、酸素や窒素などの軽元素と非常に結びつきやすく、一度これら軽元素と結合してしまうと除去が非常に困難となる。前記したようにチタンは優れた特性を有するが、このように一度結合した軽元素の除去が困難という問題、更には従来から汎用されている鉄鋼素材やアルミニウム素材などと比べて高価であるという問題も有しており、市場への普及が進んでいないのが現状である。 Since titanium is active, it is also called an active metal, and is very easily associated with light elements such as oxygen and nitrogen, and once it is combined with these light elements, removal becomes very difficult. As described above, titanium has excellent properties, but such a problem that removal of light elements once bonded is difficult, and further a problem that it is expensive compared to conventionally used steel materials and aluminum materials. In the current situation, it has not spread to the market.
　そのような現状に鑑みて、低コスト化・省資源化を図るため、チタンスクラップのリサイクルや劣質原料の利用が、過去幾度となく検討されてきたが、チタンスクラップや劣質原料は特に多量の軽元素を含有しており、その中でも含有する酸素（以下、単に含有酸素とも述べる。）が障害となり、未だに工業レベルでの実用化に至っていないという課題がある。 In view of such current situation, recycling of titanium scrap and utilization of inferior raw materials have been studied several times in the past to reduce costs and save resources, but titanium scrap and inferior raw materials are particularly light in large quantities There is a problem that the element is contained, among which the contained oxygen (hereinafter, also simply referred to as contained oxygen) is an obstacle and has not yet been put to practical use at the industrial level.
　また、最近では、電子ビームやプラズマアークを熱源とし水冷銅鋳型を用いて鋳塊を製造するハース溶解や、粉末を活用した積層造形の適用が盛んに研究開発されている。 Recently, research and development has been actively conducted on the application of hearth melting in which an ingot is produced using a water-cooled copper mold with an electron beam or plasma arc as a heat source, and layered modeling using powder.
　純チタン或いはチタン合金などのチタン素材から含有酸素を、水素を用いて除去する方法が記載された技術文献としては、非特許文献１や非特許文献２がある。 Non-Patent Document 1 and Non-Patent Document 2 are technical documents describing a method of removing oxygen contained in a titanium material such as pure titanium or titanium alloy using hydrogen.
　非特許文献１には、スポンジチタンやＴｉ－６Ａｌ－４Ｖ合金をＡｒ－（１～３０）体積％Ｈ２雰囲気下において、アーク溶解することで酸素を低減し得ることが記載されている。例えば、原料としてスポンジチタンを使用した場合には、酸素濃度が０．０４質量％から０．０１６質量％まで低下することが記載されている。また、原料としてＴｉ－６Ａｌ－４Ｖを使用した場合には、酸素濃度が０．１２質量％から０．０２８質量％まで低下することや、酸素濃度が１．６質量％から０．３質量％まで低下することが記載されている。 Non-Patent Document 1 describes that oxygen can be reduced by arc melting sponge titanium or a Ti-6Al-4V alloy in an Ar- (1 to 30) volume% H 2 atmosphere. For example, when sponge titanium is used as a raw material, it is described that an oxygen concentration falls from 0.04 mass% to 0.016 mass%. When Ti-6Al-4V is used as a raw material, the oxygen concentration decreases from 0.12% by mass to 0.028% by mass, and the oxygen concentration is 1.6% by mass to 0.3% by mass It is described that it decreases.
　また、非特許文献２には、純チタンをＡｒ－２０体積％Ｈ２ 雰囲気下において、プラズマアーク溶解することで酸素を低減し得ると記載されている。また、酸素濃度は初期酸素濃度０．２３質量％から０．０９質量％まで低下することが記載されている。 Non-Patent Document 2 describes that oxygen can be reduced by plasma arc melting pure titanium in an Ar-20 volume% H 2 atmosphere. Also, it is described that the oxygen concentration decreases from the initial oxygen concentration of 0.23% by mass to 0.09% by mass.
　しかしながら、非特許文献１には酸素分析法としてＩＣＰ分析法を用いることが記載されているが、具体的にどのような実験条件でデータを得たのかが記載されていない。一般にＩＣＰ分析法では、定量分析用の溶液を作製する際に使用する水分子に含有される酸素原子の存在により試料中の酸素濃度を正確に分析することは困難である。
　また、非特許文献２には試料中の酸素濃度の経時変化を示すグラフも記載されているが、記載されたグラフの傾きから、これ以上の酸素低減効果は期待し難い。 However, Non-Patent Document 1 describes the use of ICP analysis as an oxygen analysis method, but does not specifically describe under what experiment conditions data were obtained. Generally, in ICP analysis, it is difficult to accurately analyze the oxygen concentration in a sample due to the presence of oxygen atoms contained in water molecules used in preparing a solution for quantitative analysis.
Moreover, although the graph which shows a time-dependent change of the oxygen concentration in a sample is also described by the nonpatent literature 2, the oxygen reduction effect beyond this is hard to be anticipated from the inclination of the described graph.
　本発明は、上記従来の実情に鑑みてなされたもので、純チタン、チタン合金、或いはチタンを主成分の１つとして含有する金属間化合物でなるチタン素材から含有される酸素、更には水素を確実に除去することができるチタン素材の精製方法を提供することを課題とするものである。 The present invention has been made in view of the above-mentioned conventional circumstances, and it is possible to contain oxygen, and hydrogen contained from titanium material consisting of pure titanium, titanium alloy or an intermetallic compound containing titanium as one of the main components. An object of the present invention is to provide a method of purifying a titanium material which can be reliably removed.
　本発明のチタン素材の精製方法は、純チタン、チタン合金、或いはチタンを主成分の１つとして含有する金属間化合物でなるチタン素材から、前記チタン素材中に含有される酸素を除去するチタン素材の精製方法であって、前記チタン素材を、水素を５～７０体積％含有する希ガス雰囲気下で溶解することで、前記チタン素材の融体中に水素を導入する第一溶解工程と、前記第一溶解工程で水素が導入された前記チタン素材を、希ガス雰囲気下で溶解することで、前記チタン素材が含有する酸素を前記水素と共に前記チタン素材の融体から除去する第二溶解工程と、を有し、前記第一溶解工程および前記第二溶解工程を、それぞれ１回以上実施することを特徴とする。 The method for purifying a titanium material according to the present invention is a titanium material for removing oxygen contained in the titanium material from a titanium material consisting of pure titanium, a titanium alloy, or an intermetallic compound containing titanium as one of its main components. A first melting step of introducing hydrogen into the melt of the titanium material by dissolving the titanium material in a rare gas atmosphere containing 5 to 70% by volume of hydrogen; A second melting step of removing oxygen contained in the titanium material together with the hydrogen from the melt of the titanium material by dissolving the titanium material into which hydrogen has been introduced in the first melting step under a rare gas atmosphere; , And each of the first dissolution step and the second dissolution step is performed one or more times.
　また、本発明のチタン素材の精製方法は、前記第二溶解工程終了後に、真空度が１×１０－２～１×１０－４Ｐａ、保持温度が６００～１２００℃の条件で、１５分以上保持することで、前記チタン素材から水素を除去する熱処理工程を、更に有することが好ましい。 In the method for purifying a titanium material according to the present invention, a vacuum degree is 1 × 10 −2 to 1 × 10 −4 Pa and a holding temperature is 600 to 1200 ° C. for 15 minutes or more after completion of the second melting step. It is preferable to further have a heat treatment step of removing hydrogen from the titanium material by holding.
　本発明のチタン素材の精製方法によると、純チタン、チタン合金、或いはチタンを主成分の１つとして含有する金属間化合物でなるチタン素材から含有される酸素、更には水素を確実に除去することができる。 According to the method for purifying a titanium material of the present invention, it is possible to reliably remove oxygen and hydrogen contained in titanium material consisting of pure titanium, titanium alloy or an intermetallic compound containing titanium as one of the main components. Can.
　本発明者らは、酸素や窒素などの軽元素と非常に結びつきやすいチタンを主成分とするチタン素材から、このチタン素材に含有される軽元素、特に酸素を確実に除去できるチタン素材の精製方法を見出すため、鋭意検討を行った。 The present inventors have purified a titanium material that can reliably remove the light element contained in the titanium material, particularly oxygen, from a titanium material whose main component is titanium, which is very easily combined with light elements such as oxygen and nitrogen. We conducted intensive studies to find out
　その結果、水素を一定量含有する希ガス雰囲気下でチタン素材を溶解することで水素を導入する第一溶解工程、続いてそのチタン素材を希ガス雰囲気下で溶解することで前記チタン素材から第一工程で導入された水素と共に含有酸素を除去する第二溶解工程、を実施することで、チタン素材が含有する酸素を確実に除去できることを見出し、本発明を完成させるに至った。 As a result, the first melting step of introducing hydrogen by dissolving the titanium material in a rare gas atmosphere containing a certain amount of hydrogen, and subsequently dissolving the titanium material in a rare gas atmosphere, By carrying out the second dissolution step of removing the contained oxygen together with the hydrogen introduced in one step, it was found that the oxygen contained in the titanium material can be reliably removed, and the present invention has been completed.
　また、前記第二溶解工程後に、一定の条件で保持する熱処理工程を実施することで、含有酸素を除去するためにチタン素材に導入した水素を確実に除去できることも併せて確認した。この熱処理工程を実施することで、第二溶解工程で除去しきれなかった水素を確実に除去できると考えられる。 In addition, it was also confirmed that hydrogen introduced into the titanium material can be reliably removed in order to remove the contained oxygen by carrying out a heat treatment step of holding under a constant condition after the second dissolution step. By carrying out this heat treatment step, it is considered that hydrogen which could not be removed in the second dissolution step can be surely removed.
　第二溶解工程で、チタン素材が含有する酸素を、第一溶解工程で導入した水素と共にチタン素材から除去できる理由は、導入された水素が脱酸剤として機能するためと考えられる。 The reason why the oxygen contained in the titanium material can be removed from the titanium material together with the hydrogen introduced in the first dissolution step in the second dissolution step is considered to be because the introduced hydrogen functions as a deoxidizer.
　以下、本発明を実施形態に基づいて更に詳細に説明する。 Hereinafter, the present invention will be described in more detail based on the embodiments.
（チタン素材）
　本発明のチタン素材の精製方法に用いられるチタン素材は、純チタン、チタン合金、或いはチタンの金属間化合物（チタンを主成分の１つとして含有する金属間化合物）のいずれかを有している。純チタンとしては、ＪＩＳ１種、ＪＩＳ２種、ＪＩＳ３種、ＪＩＳ４種の工業用純チタンを例示することができ、チタン合金が含有する合金元素としては、Ａｌ、Ｖ、Ｍｏ、Ｃｒ、Ｚｒ、Ｓｎ、Ｓｉ、Ｃｕ、Ｎｂ、Ｆｅ、Ｎｉ、Ｔａ、Ａｇ、Ｐｄ、Ｃ、Ｎを例示することができ、また金属間化合物としては、ＴｉＡｌやＮｉＴｉを例示することができる。 (Titanium material)
The titanium material used in the method of purifying titanium material according to the present invention has either pure titanium, a titanium alloy, or an intermetallic compound of titanium (an intermetallic compound containing titanium as one of its main components) . As pure titanium, JIS1 class, JIS class 2, JIS class 3, JIS class 4 industrial pure titanium can be illustrated, and as an alloy element which titanium alloy contains, Al, V, Mo, Cr, Zr, Sn, Si, Cu, Nb, Fe, Ni, Ta, Ag, Pd, C, N can be exemplified, and TiAl and NiTi can be exemplified as the intermetallic compound.
　これらチタン素材のチタン含有量は４５質量％以上であることが好ましい。一般的にチタン素材のチタン含有量の下限はこの程度であり、チタン含有量が少なすぎるとチタン素材ということができなくなる。 The titanium content of these titanium materials is preferably 45% by mass or more. In general, the lower limit of the titanium content of the titanium material is about this level, and when the titanium content is too small, it can not be called a titanium material.
（精製方法）
　本発明のチタンの精製方法は、第一溶解工程と、第二溶解工程とを少なくとも有する。第一溶解工程および第二溶解工程は、それぞれ１～複数回実施される。また、第二溶解工程終了後に、熱処理工程を実施しても良い。以下、第一溶解工程、第二溶解工程、熱処理工程に分け、これら各工程を詳細に説明する。 (Purification method)
The purification method of titanium of the present invention at least includes a first dissolution step and a second dissolution step. The first dissolution step and the second dissolution step are each performed one or more times. Moreover, you may implement a heat treatment process after completion | finish of a 2nd melt | dissolution process. Hereinafter, it divides into a 1st melt | dissolution process, a 2nd melt | dissolution process, and a heat treatment process, and demonstrates each of these processes in detail.
（第一溶解工程）
　第一溶解工程は、チタン素材に水素を導入するための工程であり、チタン素材から酸素を除去するための前処理工程である。尚、先に示した非特許文献１および非特許文献２に示す技術では、この第一溶解工程に相当する工程を実施することで、酸素を低減し得るとされている。 (First dissolution process)
The first melting step is a step for introducing hydrogen into the titanium material, and is a pretreatment step for removing oxygen from the titanium material. In the techniques shown in Non-Patent Document 1 and Non-Patent Document 2 described above, it is said that oxygen can be reduced by carrying out the step corresponding to the first dissolution step.
　しかし、本発明においてはこの第一溶解工程だけでは、チタン素材から酸素を除去することはできない。後の実施例の欄で比較例として記載するが、この第一溶解工程を実施するだけではチタン素材から酸素を十分に除去することはできない。 However, in the present invention, oxygen can not be removed from the titanium material only by the first melting step. Although it describes as a comparative example in the column of a subsequent Example, oxygen can not fully be removed from a titanium raw material only by implementing this 1st melt | dissolution process.
　第一溶解工程では、例えばプラズマアーク溶解炉を用い、チタン素材を、水素を５～７０体積％含有する希ガス雰囲気下で溶解することで、チタン素材の融体中に水素を導入する。 In the first melting step, hydrogen is introduced into the titanium material melt by melting the titanium material in a rare gas atmosphere containing 5 to 70% by volume of hydrogen using, for example, a plasma arc melting furnace.
　第一溶解工程での溶解は、プラズマアーク溶解で行うことが望ましい。プラズマアーク溶解でチタン素材の溶解を行うことにより、プラズマガス中に水素を混入しておくことで、加熱と水素導入を同時に行うことができる。尚、プラズマアーク溶解以外の溶解であれば、熱源とは別に水素ガスを導入する装置などが必要となり、製造コストの高騰に繋がる。 The melting in the first melting step is preferably performed by plasma arc melting. By melting the titanium material by plasma arc melting, heating and hydrogen introduction can be simultaneously performed by mixing hydrogen in the plasma gas. In addition, if it is melt | dissolution other than plasma arc melt | dissolution, the apparatus etc. which introduce hydrogen gas separately from a heat source will be needed, and it will lead to the rise of manufacturing cost.
　また、第一溶解工程の雰囲気を、水素を５～７０体積％（５体積％以上かつ７０体積％以下）含有する希ガス雰囲気とした理由は、特にプラズマアーク溶解の場合、水素濃度が７０体積％を超えた場合、電離の際に必要なエネルギーが上昇し、電圧上昇に伴うアーク消失が頻発し、プラズマアークの発生が困難となるためである。一方、水素濃度が５体積％未満であれば、チタン融体中に水素を十分に導入できない。
　なお、水素の含有量の下限は、好ましくは１０体積％以上、より好ましくは１５体積％以上であるのが良い。また、水素含有量の上限は、好ましくは６０体積％以下、より好ましくは５０体積％以下であるのが良い。 The reason for setting the atmosphere of the first melting step to a rare gas atmosphere containing 5 to 70% by volume of hydrogen (5% to 70% by volume) is that the hydrogen concentration is 70 volumes, especially in the case of plasma arc melting. If it exceeds 10%, the energy required for ionization will rise, and the arc loss will be frequent with the rise in voltage, making it difficult to generate a plasma arc. On the other hand, if the hydrogen concentration is less than 5% by volume, hydrogen can not be sufficiently introduced into the titanium melt.
The lower limit of the hydrogen content is preferably 10% by volume or more, more preferably 15% by volume or more. The upper limit of the hydrogen content is preferably 60% by volume or less, more preferably 50% by volume or less.
　また、第一溶解工程の雰囲気は、水素を５～７０体積％含有する希ガス雰囲気としたが、希ガス雰囲気としてはＡｒ雰囲気を例示することができる。また、第一溶解工程の雰囲気が、Ｈｅ雰囲気、Ｎｅ雰囲気等であっても原理的に脱酸は可能である。 The atmosphere in the first melting step is a rare gas atmosphere containing 5 to 70% by volume of hydrogen, but an Ar atmosphere can be exemplified as the rare gas atmosphere. In addition, even if the atmosphere of the first melting step is He atmosphere, Ne atmosphere, etc., deoxidation is theoretically possible.
　尚、本発明では第一溶解工程での投入熱量については特に規定しないが、１５～２００ｋＷ／ｋｇ（１５ｋＷ／ｋｇ以上かつ２００ｋＷ／ｋｇ以下）の範囲とすることが好ましい。投入熱量が１５ｋＷ／ｋｇ未満である場合は、チタンの溶解に必要な熱量を確保できない。一方、投入熱量が２００ｋＷ／ｋｇを超える場合は、チタンの揮発ロスが生じてしまう。 In the present invention, the amount of heat input in the first melting step is not particularly specified, but is preferably in the range of 15 to 200 kW / kg (15 kW / kg or more and 200 kW / kg or less). If the amount of heat input is less than 15 kW / kg, the amount of heat necessary to dissolve titanium can not be secured. On the other hand, if the heat input exceeds 200 kW / kg, volatilization loss of titanium will occur.
　また、第一溶解工程での溶解保持時間についても特に規定しないが、０．３～３．６ｋｓ（５～６０分）の範囲とすることが好ましい。なお、溶解保持時間の下限は０．６ｋｓ（１０分）、上限は１．８ｋｓ（３０分）とすることがより好ましい。溶解保持時間が０．３ｋｓ（５分）未満である場合は、脱酸のための十分な水素導入ができない。一方、溶解保持時間が３．６ｋｓ（６０分）を超えても、熱・チタン揮発ともにロスが多くなるだけである。 Further, the dissolution holding time in the first dissolution step is not particularly specified, but is preferably in the range of 0.3 to 3.6 ks (5 to 60 minutes). The lower limit of the dissolution holding time is more preferably 0.6 ks (10 minutes) and the upper limit is 1.8 ks (30 minutes). If the solution retention time is less than 0.3 ks (5 minutes), sufficient hydrogen introduction for deacidification can not be achieved. On the other hand, even if the solution holding time exceeds 3.6 ks (60 minutes), the heat and the volatilization of titanium only increase the loss.
　この第一溶解工程は通常１度のみ実施するが、第二溶解工程実施後に再度実施しても構わない。また、第一溶解工程は連続して２回以上繰り返して実施しても構わない。尚、１回のみの実施にするのか、複数回実施するのかは、酸素濃度が処理前に比べて８０％以下に低下していることを判断基準にすることができる。 This first dissolution step is usually carried out only once, but may be carried out again after the second dissolution step. In addition, the first dissolution step may be repeated twice or more continuously. It should be noted that whether the operation is performed only once or performed plural times can be based on the fact that the oxygen concentration is reduced to 80% or less compared to that before the treatment.
（第二溶解工程）
　第二溶解工程は、チタン素材中に含有される酸素を、第一溶解工程でチタン素材に導入した水素と共に、チタン素材の融体中から除去する工程である。 (Second dissolution process)
The second melting step is a step of removing oxygen contained in the titanium material from the melt of the titanium material together with hydrogen introduced into the titanium material in the first melting step.
　第一溶解工程での溶解は、プラズマアーク溶解で行うことが望ましいとしたが、第二溶解工程での溶解も、プラズマアーク溶解で行うことが望ましい。第一溶解工程と同様に、チタン素材のプラズマアーク溶解を行うことにより、融体の温度を他のプロセス以上に上昇させることが可能となる。尚、プラズマアーク溶解以外の溶解であれば、温度低下に伴い脱酸効率が僅かながら低下することが予想される。 Although the dissolution in the first dissolution step is desirably performed by plasma arc dissolution, the dissolution in the second dissolution step is also preferably performed by plasma arc dissolution. As in the first melting step, by performing plasma arc melting of the titanium material, it is possible to raise the temperature of the melt above other processes. In addition, if it is melt | dissolution other than plasma arc melt | dissolution, it is estimated that deoxidation efficiency declines slightly with temperature fall.
　また、第二溶解工程での雰囲気は、Ａｒ、Ｈｅ、Ｎｅなどの希ガス雰囲気とする。例えば、第一溶解工程での雰囲気を、水素を５～７０体積％含有するＡｒ雰囲気とした場合は、第二溶解工程は第一溶解工程と同種の希ガスを用いたＡｒ雰囲気とすることが効率上好ましい。但し、第二溶解工程での雰囲気も、第一溶解工程と同様にＨｅ、Ｎｅなどの他の希ガスを用いても構わない。 Further, the atmosphere in the second melting step is a rare gas atmosphere such as Ar, He, or Ne. For example, when the atmosphere in the first melting step is an Ar atmosphere containing 5 to 70% by volume of hydrogen, the second melting step may be an Ar atmosphere using the same kind of rare gas as the first melting step. Preferred for efficiency. However, the atmosphere in the second melting step may be another rare gas such as He or Ne as in the first melting step.
　第二溶解工程では水素を含有しない希ガス雰囲気とすることで、チタン素材中に含有される酸素を、第一溶解工程でチタン素材に導入した水素と共に、チタン素材の融体中から確実に除去することができる。尚、水素を含有しない希ガス雰囲気と記載したが、チタン素材の融体からの水素と酸素の除去に影響を与えない程度であれば、水素は極微量（５体積％未満）に含有していても構わない。 In the second melting step, the oxygen contained in the titanium material is reliably removed from the melt of the titanium material together with the hydrogen introduced into the titanium material in the first melting step by setting it to a rare gas atmosphere not containing hydrogen. can do. Although it is described as a rare gas atmosphere not containing hydrogen, hydrogen is contained in a very small amount (less than 5% by volume) if it does not affect the removal of hydrogen and oxygen from the melt of titanium material. It does not matter.
　尚、第二溶解工程での投入熱量も第一溶解工程と同様に１５～２００ｋＷ／ｋｇの範囲とすることが好ましい。投入熱量が１５ｋＷ／ｋｇ未満である場合は、チタンの溶解に必要な熱量を確保できない。一方、投入熱量が２００ｋＷ／ｋｇを超える場合は、チタンの揮発ロスが生じてしまう。 The amount of heat input in the second melting step is preferably in the range of 15 to 200 kW / kg as in the first melting step. If the amount of heat input is less than 15 kW / kg, the amount of heat necessary to dissolve titanium can not be secured. On the other hand, if the heat input exceeds 200 kW / kg, volatilization loss of titanium will occur.
　また、本発明では第二溶解工程での溶解保持時間についても第一溶解工程での溶解保持時間と同様に特に規定しないが、０．３～３．６ｋｓ（５～６０分）の範囲とすることが好ましく、下限は０．６ｋｓ（１０分）、上限は１．８ｋｓ（３０分）とすることがより好ましい。溶解保持時間が０．３ｋｓ（５分）未満である場合は、脱酸のための十分な時間が確保できない。一方、溶解保持時間が３．６ｋｓ（６０分）を超えても、熱・チタン揮発ともにロスが多くなるだけである。 In the present invention, the dissolution holding time in the second dissolution step is not particularly specified as in the dissolution holding time in the first dissolution step, but is in the range of 0.3 to 3.6 ks (5 to 60 minutes). The lower limit is preferably 0.6 ks (10 minutes) and the upper limit is preferably 1.8 ks (30 minutes). If the dissolution holding time is less than 0.3 ks (5 minutes), sufficient time for deoxidation can not be secured. On the other hand, even if the solution holding time exceeds 3.6 ks (60 minutes), the heat and the volatilization of titanium only increase the loss.
　この第二溶解工程も第一溶解工程と同様に通常は１度のみ実施するが、第一溶解工程同様に複数回実施しても構わない。第二溶解工程を複数回実施する場合は、第一溶解工程と組み合わせてセットで複数回繰り返して実施しても構わないし、第一溶解工程終了後に第二溶解工程のみを複数回実施しても構わない。尚、１回のみの実施にするのか、複数回実施するのかは、水素濃度が５．０×１０－２質量％以下に低下していることを判断基準にすることができる。 This second dissolution step is usually performed only once as in the first dissolution step, but may be performed a plurality of times as in the first dissolution step. When the second dissolving step is carried out a plurality of times, it may be carried out repeatedly in combination with the first dissolving step a plurality of times, or even if only the second dissolving step is carried out a plurality of times after the first dissolving step is completed. I do not care. In addition, whether the hydrogen concentration is reduced to 5.0 × 10 −2 mass% or less can be used as a judgment standard whether the operation is performed only once or plural times.
（熱処理工程）
　熱処理工程は、第二溶解工程終了後に、真空度が１×１０－２～１×１０－４Ｐａ、保持温度が６００～１２００℃の条件で、０．９ｋｓ（１５分）以上保持することで実施する。 (Heat treatment process)
In the heat treatment step, after the completion of the second melting step, the vacuum degree is maintained at 0.9 ks (15 minutes) or more under the conditions of 1 × 10 −2 to 1 × 10 4 Pa and the holding temperature of 600 to 1200 ° C. carry out.
　この熱処理工程は必ずしも実施する必要はないが、熱処理工程を実施することで、第二溶解工程で除去しきれなかった水素を確実に除去できる。 Although this heat treatment step does not necessarily need to be carried out, by carrying out the heat treatment step, it is possible to surely remove hydrogen which could not be removed in the second dissolution step.
　熱処理工程は真空熱処理炉などを用いて実施されるが、その際の真空度は１×１０－２～１×１０－４Ｐａの範囲とする。真空度の上限を１×１０－４Ｐａとした理由は、１×１０－４Ｐａを超える真空度とすることは脱水素の目的だけであれば好ましいが、上述した真空度まで排気するのに長時間を有し効率が悪いためである。一方、真空度の下限を１×１０－２Ｐａとした理由は、１×１０－２Ｐａ未満の真空度ではチタン表面に酸化皮膜が形成されてしまい、その酸化皮膜により水素除去が阻害されてしまうためである。 The heat treatment step is carried out using a vacuum heat treatment furnace or the like, and the degree of vacuum at that time is in the range of 1 × 10 −2 to 1 × 10 −4 Pa. The upper limit of the degree of vacuum is set to 1 × 10 -4 Pa because a degree of vacuum exceeding 1 × 10 -4 Pa is preferable for the purpose of dehydrogenation, but for exhausting to the above-mentioned degree of vacuum It is because it has a long time and the efficiency is bad. On the other hand, the reason why the lower limit of the vacuum degree is 1 × 10 -2 Pa is that at a vacuum degree of less than 1 × 10 -2 Pa, an oxide film is formed on the titanium surface and hydrogen removal is inhibited by the oxide film. It is because it
　また、熱処理工程での保持温度は６００～１２００℃とする。保持温度の下限を６００℃とした理由は、保持温度がそれより低い場合は、固体チタン素材中の水素の拡散速度が遅くなり、脱水素に長時間を有し効率が悪いためである。一方、保持温度の上限を１２００℃とした理由は、保持温度がそれより高い場合は、チタン表面における酸化皮膜形成を活発にするとともに、冷却までに要する時間が長くなるためである。 Further, the holding temperature in the heat treatment step is set to 600 to 1200 ° C. The lower limit of the holding temperature is set to 600 ° C., because if the holding temperature is lower than that, the diffusion rate of hydrogen in the solid titanium material becomes slow and dehydrogenation takes a long time and the efficiency is poor. On the other hand, the reason for setting the upper limit of the holding temperature to 1200 ° C. is that if the holding temperature is higher than that, the formation of the oxide film on the titanium surface becomes active and the time required for cooling becomes long.
　また、熱処理工程での保持時間は０．９ｋｓ（１５分）以上とする。保持時間が０．９ｋｓ（１５分）未満であれば、第二溶解工程で除去しきれなかったチタン素材中の水素を除去することができない可能性が高く、保持時間を０．９ｋｓ（１５分）以上とすることで、第二溶解工程で除去しきれなかったチタン素材中の水素を確実に除去することができる。 In addition, the holding time in the heat treatment step is set to 0.9 ks (15 minutes) or more. If the retention time is less than 0.9ks (15 minutes), there is a high possibility that the hydrogen in the titanium material that could not be removed in the second dissolution step can not be removed, and the retention time is 0.9ks (15 minutes) By the above, it is possible to reliably remove the hydrogen in the titanium material which could not be removed in the second dissolving step.
　尚、保持時間が長いほどより確実にチタン素材中の水素を除去できるが、３．６ｋｓ（６０分）程度要すればチタン素材中の水素はほぼ全て除去できると考えられる。 The longer the holding time, the more surely the hydrogen in the titanium material can be removed, but it is considered that almost all the hydrogen in the titanium material can be removed if about 3.6 ks (60 minutes) is required.
　以下、実施例を挙げて本発明をより具体的に説明するが、本発明はもとより下記実施例によって制限を受けるものではなく、本発明の趣旨に適合し得る範囲で適宜変更を加えて実施することも可能であり、それらは何れも本発明の技術的範囲に含まれる。 EXAMPLES Hereinafter, the present invention will be more specifically described by way of examples. However, the present invention is of course not limited by the following examples, and the present invention is implemented by adding appropriate changes as long as they can conform to the spirit of the present invention. It is also possible that they are all included in the technical scope of the present invention.
　本実施例では、チタン素材（工業用純チタン：ＣＰチタン製の溶解原料）を用い、プラズマアーク溶解炉で第一溶解工程および第二溶解工程を、真空熱処理炉で熱処理工程を、試験条件に応じ順次実施した。チタン素材の溶解に用いるハースは、サイズが直径８０ｍｍの半球状の形状とした。このハースに、チタン融体質量（サンプル質量）２５０ｇの場合には高さ約２５ｍｍとなるようにチタン素材を入れ、またチタン融体質量（サンプル質量）５００ｇの場合には高さ約４０ｍｍとなるようにチタン素材を入れた。 In this example, using a titanium material (industrial grade pure titanium: melting material made of CP titanium), the first melting step and the second melting step in a plasma arc melting furnace and the heat treatment step in a vacuum heat treatment furnace under test conditions. It carried out according to the order. The hearth used for melting the titanium material was a hemispherical shape with a diameter of 80 mm. In this hearth, a titanium material is added so that the height is about 25 mm in the case of 250 g of titanium melt mass (sample mass), and the height is about 40 mm in the case of 500 g of titanium melt mass (sample mass) I put the titanium material like.
　また、第一溶解工程でのプラズマアークによる溶解出力は７０Ｖ、５００Ａ、第二溶解工程での溶解出力は５０Ｖ、４５０Ａであり、第一溶解工程での溶解時間は０．３～３．６ｋｓ（５～６０分）の範囲内、流量は３０Ｌ／分、第二溶解工程での溶解時間は０．３～３．６ｋｓ（５～６０分）の範囲内、流量は２０Ｌ／分とした。第一溶解工程および第二溶解工程での投入熱量は１１４ｋＷ／ｋｇ、炉内圧力は１ａｔｍである。 In addition, the dissolution output by plasma arc in the first dissolution step is 70 V, 500 A, the dissolution output in the second dissolution step is 50 V, 450 A, and the dissolution time in the first dissolution step is 0.3 to 3.6 ks ( In the range of 5 to 60 minutes, the flow rate was 30 L / min, the dissolution time in the second dissolution step was in the range of 0.3 to 3.6 ks (5 to 60 minutes), and the flow rate was 20 L / min. The amount of heat input in the first melting step and the second melting step is 114 kW / kg, and the pressure in the furnace is 1 atm.
　実施例（発明例）の試験では、前記チタン素材を溶解原料として用い、溶解工程として第一溶解工程および第二溶解工程を順に１～複数回実施し、必要に応じて熱処理工程を実施した。一方、比較例の試験では、前記チタン素材を溶解原料として用い、溶解工程として第一溶解工程のみを実施し、必要に応じて熱処理工程を実施した。 In the tests of the example (inventive example), the titanium raw material was used as a dissolution raw material, and the first dissolution step and the second dissolution step were sequentially performed one or more times as a dissolution step, and a heat treatment step was performed as needed. On the other hand, in the test of the comparative example, only the first melting step was carried out as the melting step using the titanium material as the melting raw material, and the heat treatment step was carried out as needed.
　第一溶解工程の雰囲気は、水素を３０体積％混合したＡｒ雰囲気とし、第二溶解工程の雰囲気は、水素を混合していないＡｒ雰囲気（純Ａｒ雰囲気）とした。また、熱処理工程では、Ｔｉシートを敷いたＡｌ２Ｏ３ボートに、溶解工程を終えた試料を置き、真空ポンプで７．０×１０－３Ｐａになるまで真空に引いた。その後、真空状態（７．０×１０－３Ｐａ）を保持したまま１０２３Ｋ（７５０℃）まで昇温し、保持時間３．６ｋｓ（６０分）の間保持した。 The atmosphere in the first dissolution step was an Ar atmosphere in which 30 volume% of hydrogen was mixed, and the atmosphere in the second dissolution step was an Ar atmosphere (pure Ar atmosphere) in which hydrogen was not mixed. In the heat treatment step, the sample after the melting step was placed on an Al 2 O 3 boat covered with a Ti sheet, and vacuum was applied by a vacuum pump until it reached 7.0 × 10 −3 Pa. Thereafter, the temperature was raised to 1023 K (750 ° C.) while keeping the vacuum state (7.0 × 10 −3 Pa), and the holding time was maintained for 3.6 ks (60 minutes).
　この試験では、試験実施前のチタン素材（試料）の最表面と、最終工程（試験条件により第一溶解工程、第二溶解工程、熱処理工程の場合がある。）を終えた後の試料の最表面からサンプルを採取し、試験実施前の試料の酸素濃度、最終工程を終えた試料の酸素濃度および水素濃度の測定を不活性ガス融解赤外線吸収法により行い、評価を行った。尚、水素分析は半定量法である。試験結果を表１に示す。 In this test, the outermost surface of the titanium material (sample) before the test and the sample after finishing the final process (may be the first dissolution process, the second dissolution process, or the heat treatment process depending on the test conditions). A sample was taken from the surface, and the oxygen concentration of the sample before the test and the oxygen concentration and hydrogen concentration of the sample after the final step were measured by the inert gas melting infrared absorption method and evaluated. Hydrogen analysis is a semi-quantitative method. The test results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　本発明の要件を満足する条件でチタン素材の精製を行った各実施例（発明例）では、脱酸が順調に進行しているのに対し、各比較例では精製が進行していないことが分かる。 In each of the Examples (Invention Examples) in which the titanium material was purified under the conditions satisfying the requirements of the present invention, while deacidification proceeds smoothly, in each Comparative Example, purification did not proceed. I understand.
　この結果から、水素を５～７０体積％含有するＡｒ雰囲気下で溶解することで、チタン素材に水素を導入する溶解工程（第一溶解工程）だけでは、精製は十分に進行しないが、第一溶解工程に続いてチタン素材を、水素が含有されないＡｒ雰囲気下で溶解する第二溶解工程を実施することで、精製が進行することが分かる。 From this result, by dissolving in an Ar atmosphere containing 5 to 70% by volume of hydrogen, purification does not sufficiently proceed only with the dissolving step (first dissolving step) of introducing hydrogen into the titanium material, but It can be understood that the purification proceeds by performing the second dissolution step of dissolving the titanium material under an Ar atmosphere containing no hydrogen following the dissolution step.
　第一溶解工程でチタン素材中に導入された水素が、第二溶解工程で脱酸剤として機能し、チタン素材が含有する酸素が、その水素と共にチタン素材から除去されるためと考えることができる。 It can be considered that the hydrogen introduced into the titanium material in the first dissolution step functions as a deoxidizing agent in the second dissolution step, and the oxygen contained in the titanium material is removed from the titanium material together with the hydrogen. .
　なお、今回開示された実施形態はすべての点で例示であって制限的なものではないと考えられるべきである。特に、今回開示された実施形態において、明示的に開示されていない事項、例えば、運転条件や操業条件、各種パラメータ、構成物の寸法、重量、体積などは、当業者が通常実施する範囲を逸脱するものではなく、通常の当業者であれば、容易に想定することが可能な値を採用している。 It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. In particular, in the embodiment disclosed this time, matters not explicitly disclosed, such as operating conditions and conditions, various parameters, dimensions of components, weights, volumes, etc., deviate from the range normally practiced by those skilled in the art. It is not necessary for the person skilled in the art to use values that can easily be assumed.
　本出願は、２０１７年１０月３１日出願の日本特許出願（特願２０１７－２１０１２９）に基づくものであり、その内容はここに参照として取り込まれる。 This application is based on Japanese Patent Application (Application No. 2017-210129) filed on October 31, 2017, the contents of which are incorporated herein by reference.
　本発明によれば、チタンスクラップのリサイクルや劣質原料の利用が可能になる。 According to the present invention, it is possible to recycle titanium scrap and use inferior raw materials.

Claims (2)

  1. 　純チタン、チタン合金、或いはチタンを主成分の１つとして含有する金属間化合物でなるチタン素材から、前記チタン素材中に含有される酸素を除去するチタン素材の精製方法であって、
    　前記チタン素材を、水素を５～７０体積％含有する希ガス雰囲気下で溶解することで、前記チタン素材の融体中に水素を導入する第一溶解工程と、
    　前記第一溶解工程で水素が導入された前記チタン素材を、希ガス雰囲気下で溶解することで、前記チタン素材が含有する酸素を前記水素と共に前記チタン素材の融体から除去する第二溶解工程と、を有し、
    　前記第一溶解工程および前記第二溶解工程を、それぞれ１回以上実施することを特徴とするチタン素材の精製方法。     A method of purifying a titanium material for removing oxygen contained in the titanium material from a titanium material consisting of pure titanium, a titanium alloy, or an intermetallic compound containing titanium as one of main components,
    A first melting step of introducing hydrogen into the melt of the titanium material by dissolving the titanium material in a rare gas atmosphere containing 5 to 70% by volume of hydrogen;
    A second melting process of removing oxygen contained in the titanium material together with the hydrogen from the melt of the titanium material by dissolving the titanium material into which hydrogen is introduced in the first melting step in a rare gas atmosphere. And
    A method of purifying a titanium material, wherein the first melting step and the second melting step are each performed once or more.
  2. 　前記第二溶解工程終了後のチタン素材を、真空度が１×１０－２～１×１０－４Ｐａ、保持温度が６００～１２００℃の条件で、１５分以上保持することで、前記チタン素材から水素を除去する熱処理工程を、更に有することを特徴とする請求項１記載のチタン素材の精製方法。 The titanium material after the completion of the second melting step is held for 15 minutes or longer under the conditions of a vacuum degree of 1 × 10 -2 to 1 × 10 -4 Pa and a holding temperature of 600 to 1200 ° C. The method of purifying titanium material according to claim 1, further comprising a heat treatment step of removing hydrogen from hydrogen.
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