JP6699209B2 - Aggregate of sponge titanium particles for producing titanium powder and method for producing the same - Google Patents
Aggregate of sponge titanium particles for producing titanium powder and method for producing the same Download PDFInfo
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Description
本発明は、チタン粉末製造用スポンジチタン粒の集合体およびその製造法に関する。 The present invention relates to an aggregate of titanium sponge particles for producing titanium powder and a method for producing the same.
粉末冶金用チタン粉末は、原料であるスポンジチタンを水素化して脆化させた後に粉砕し、その後に脱水素する、いわゆる水素化脱水素法により、製造される。 Titanium powder for powder metallurgy is produced by a so-called hydrodehydrogenation method in which titanium sponge as a raw material is hydrogenated to embrittle it, and then pulverized and then dehydrogenated.
スポンジチタンを水素脆化させる場合、高温炉に水素を導入して金属を水素化物に変えて脆化させてから粉砕する。クロール法の場合、TiCl4を液体のMg上に滴下することにより約９００℃で（１）式で示す気液反応により反応が進行する。
TiCl４（気体）＋2Mg（液体）→Ti（固体）＋2MgCl2（液体） ・・・・・（１）
In the case where titanium sponge is embrittled with hydrogen, hydrogen is introduced into a high temperature furnace to change a metal into a hydride to embrittle the metal and then crushed. In the case of the Kroll method, TiCl 4 is dropped onto liquid Mg, so that the reaction proceeds at about 900° C. by a gas-liquid reaction represented by the formula (1).
TiCl 4 (gas) + 2Mg (liquid) → Ti (solid) + 2MgCl 2 (liquid) ・・・・・ (1)
スポンジチタンは、そもそもその名の示す通り、海綿状の外見と海綿状の内部組織を有する。海綿状の外見と内部組織は、基本的にはこの気液反応により形成される。このMg還元プロセスが終了すると、引続き９００〜９６０℃付近において真空中で加熱され、スポンジの内部構造中に残留しているMgやMgCl2を気体として取り出すという工程を辿る。この工程によって得られたスポンジチタンは、一般的に、全量３〜８トンの大きな塊であるため、スポンジチタンはその後の用途に応じて最適な粒度に機械的に破砕されるが、通常は１／２インチ〜２０メッシュが標準とされている。 Titanium sponge, as the name implies, has a spongy appearance and a spongy internal tissue. The spongy appearance and internal tissues are basically formed by this gas-liquid reaction. After the completion of this Mg reduction process, the process of heating in vacuum at about 900 to 960° C. and taking out Mg or MgCl 2 remaining in the internal structure of the sponge as a gas is followed. The sponge titanium obtained by this step is generally a large lump with a total amount of 3 to 8 tons, so the sponge titanium is mechanically crushed to an optimum particle size depending on the subsequent application, but usually 1 1/2 inch to 20 mesh is standard.
このように得られたスポンジチタン粒は、再結晶温度を超える９００〜９６０℃において長時間加熱された履歴を有しており、スポンジチタン粒の末端部のミクロ組織は、微細で金属組織は焼結・再結晶組織と呼ばれる。 The thus-obtained titanium sponge particles have a history of being heated for a long time at 900 to 960° C., which is higher than the recrystallization temperature, and the microstructure of the end portion of the titanium sponge particles is fine and the metal structure is burnt. It is called a crystallized/recrystallized structure.
このような粉末冶金用チタン粉末の製造では、粉末冶金用チタン粉末の粒度をより細かく、かつ均一にすることが求められている。粉末冶金用チタン粉末の粒度をより細かく、かつ均一にすれば、機械的な破砕の作業効率が向上し、粉末冶金用チタン粉末の歩留まりと品質を向上できるからである。 In the production of such titanium powder for powder metallurgy, it is required to make the particle size of the titanium powder for powder metallurgy finer and more uniform. This is because if the particle size of the titanium powder for powder metallurgy is made finer and uniform, the work efficiency of mechanical crushing is improved, and the yield and quality of the titanium powder for powder metallurgy can be improved.
特許文献１には、水素化脱水素法によるチタン粉の製造プロセスにおいて、中間原料となる水素化チタン粉から発生する水素ガスまたは水素ガスを含む不活性ガス雰囲気中で脱水素処理を行うことによって、脱水素処理工程における昇温速度と均熱性を向上させて試料の焼結ならびに飛散現象を効果的に抑制し、かつ脱水素時間を短縮化する工業的なチタン粉の製造方法が開示されている。 Patent Document 1 discloses that in a manufacturing process of titanium powder by a hydrodehydrogenation method, dehydrogenation treatment is performed in a hydrogen gas generated from titanium hydride powder as an intermediate raw material or in an inert gas atmosphere containing hydrogen gas. , An industrial method for producing titanium powder is disclosed, which effectively suppresses the sintering and scattering phenomena of the sample by improving the temperature rising rate and the soaking property in the dehydrogenation treatment step, and shortens the dehydrogenation time. There is.
特許文献２には、クロール法によって製造されたスポンジチタンを水素脆化させる工程を経て生成される水素化チタン粉末であって、平均粒径が３０μｍ以下、粒径が５μｍ以下の粉末割合が１０質量％以下、酸素含有量が０．１５質量％以下、塩素含有量が０．０５質量％以下である水素化チタン粉末が開示される。この水素化チタン粉末は、粉末冶金法による焼結チタン製品製造用チタン粉末の原料として好適であり、製品歩留りを犠牲にせず、低コストでかつ簡便な操作で、酸素含有量と塩素含有量が低減される。 Patent Document 2 discloses a titanium hydride powder produced through a process of hydrogen embrittlement of titanium sponge produced by the Kroll method, wherein a powder ratio of an average particle diameter of 30 μm or less and a particle diameter of 5 μm or less is 10 Disclosed is a titanium hydride powder having a mass% or less, an oxygen content of 0.15 mass% or less, and a chlorine content of 0.05 mass% or less. This titanium hydride powder is suitable as a raw material for a titanium powder for producing a sintered titanium product by powder metallurgy, does not sacrifice product yield, is low in cost and is a simple operation, and has an oxygen content and a chlorine content. Will be reduced.
特許文献３には、チタンまたはチタン合金を水素脆化させる工程を経て生成される最大粒径が実質的に１５０μｍ以下の水素化チタン粉末であって、粒径１０μｍ以下の粉末割合が８質量％以下、酸素含有量が０．１５質量％以下、塩素含有量が０．０６質量％以下である水素化チタン粉末が開示される。この水素化チタン粉末は、酸素含有量と塩素含有量が低減され、優れた流動性および成形性を兼備し、粉末冶金法による焼結チタンまたはチタン合金製品の製造用原料として好適である。 Patent Document 3 discloses a titanium hydride powder having a maximum particle size of substantially 150 μm or less, which is produced through a process of hydrogen embrittlement of titanium or a titanium alloy, and a powder ratio of the particle size of 10 μm or less is 8% by mass. Hereinafter, a titanium hydride powder having an oxygen content of 0.15 mass% or less and a chlorine content of 0.06 mass% or less is disclosed. This titanium hydride powder has reduced oxygen content and chlorine content, has excellent fluidity and moldability, and is suitable as a raw material for producing a sintered titanium or titanium alloy product by powder metallurgy.
さらに、特許文献４には、水素化脱水素法におけるチタンまたはチタン合金粉末の製造プロセスにおいて、水素化工程後に粉砕した水素化チタンまたは水素化合金粉末の粒度分布を予め粒径６３μｍ以下の粉体割合が３０質量％以下になるように調整し、この水素化チタンまたは水素化チタン合金粉末を脱水素処理することにより、水素化チタンまたは水素化チタン合金粉末を製造する方法が開示される。 Further, in Patent Document 4, in the production process of titanium or titanium alloy powder in the hydrodehydrogenation method, the particle size distribution of titanium hydride or hydrogenated alloy powder crushed after the hydrogenation step is a powder having a particle size of 63 μm or less in advance. Disclosed is a method of producing titanium hydride or titanium hydride alloy powder by adjusting the proportion to 30% by mass or less and subjecting the titanium hydride or titanium hydride alloy powder to dehydrogenation treatment.
特許文献１により開示された発明は、水素化脱水素法によるチタン粉の製造プロセスにおいて、脱水素処理を中間原料となる水素化チタン粉から発生する水素ガス雰囲気中で行うことを特徴とし、脱水素処理工程における昇温速度と均熱性を向上させて試料の焼結ならびに飛散現象を効果的に抑制するとしている。 The invention disclosed in Patent Document 1 is characterized in that in the production process of titanium powder by the hydrodehydrogenation method, dehydrogenation treatment is performed in a hydrogen gas atmosphere generated from titanium hydride powder as an intermediate raw material. It is said that the rate of temperature rise and soaking in the elementary treatment process are improved to effectively suppress the sintering and scattering phenomena of the sample.
しかし、水素脆化した部分は、水素化による体積膨張のために歪みが入り、そこを起点として亀裂が入り微細に粉砕される。脱水素過程を水素ガス雰囲気中で行うと水素脆化した部分と周囲の水素ガス相との間の界面での水素の移動が緩慢なものになるため、粉砕された部分が焼結により修復される。すなわち、脱水素過程と焼結が同時に起き易いため、一旦細粒化したものが合体するために細粒化が進み難く、細粒化が不十分になり、焼結も進行するので粒径分布も不均一になる。このため、特許文献１により開示された発明では、粉末冶金用チタン粉末の粒度をより細かく、かつ均一にすることはできない。 However, the hydrogen-embrittled portion is distorted due to volume expansion due to hydrogenation, and cracks are generated from that portion as a starting point to be finely pulverized. When the dehydrogenation process is carried out in a hydrogen gas atmosphere, the migration of hydrogen at the interface between the hydrogen embrittled part and the surrounding hydrogen gas phase becomes slow, so the crushed part is restored by sintering. It That is, since the dehydrogenation process and the sintering are likely to occur at the same time, it is difficult for the particles that have been once made into fine particles to coalesce, and it is difficult to make the particles fine. Also becomes uneven. Therefore, in the invention disclosed in Patent Document 1, it is not possible to make the particle size of the titanium powder for powder metallurgy finer and more uniform.
特許文献２により開示された発明による水素化チタン粉末および水素化チタン粉末を原料として製造されるチタン粉末は、粉末全体に対する特定粒径範囲の粉末割合を調整する。平均粒径は３０μｍ以下であるが、粒径が５μｍ以下の粉末：０〜１０質量％、粒径が５μｍ超の粉末：９０〜１００質量％であり、必然的に不均一な分布を製品中に導入するために均一な分布を得ることができない。特許文献２により開示された発明によると、粒径５μｍ以下の粉末の割合が１０質量％を越えると、微粉末の粉体割合が多くなるため酸素含有量が多くなり、流動性や成形性も低下し易く、粉末冶金法により製造された焼結チタン製品の機械的特性を十分に満足できることができない。したがって、粉末の粒径をさらに細かくすることはできないため、粉末冶金用チタン粉末の粒度をより細かく、かつ均一にすることはできない。 The titanium hydride powder according to the invention disclosed in Patent Document 2 and the titanium powder manufactured using the titanium hydride powder as a raw material adjust the ratio of the powder in the specific particle size range to the entire powder. The average particle size is 30 μm or less, but the powder having a particle size of 5 μm or less: 0 to 10% by mass, and the powder having a particle size of more than 5 μm: 90 to 100% by mass, which inevitably has a non-uniform distribution in the product. Therefore, it is not possible to obtain a uniform distribution due to the introduction. According to the invention disclosed in Patent Document 2, when the ratio of the powder having a particle size of 5 μm or less exceeds 10% by mass, the powder ratio of the fine powder increases, the oxygen content increases, and the fluidity and moldability also increase. It tends to deteriorate, and the mechanical properties of the sintered titanium product manufactured by powder metallurgy cannot be sufficiently satisfied. Therefore, since the particle size of the powder cannot be made finer, the particle size of the titanium powder for powder metallurgy cannot be made finer and uniform.
特許文献３により開示された発明における粒度の分布は、１０μｍ超：０〜８％，１０μｍ以上１５０μｍ未満：９０〜１００％である。チタン系粉末は、粒径が小さい微細な粉末が多くなるほど粉末全体の酸素含有量が増加し、不純物としての塩素が粒径１０μｍ以下の微粉末中に偏向して含有されている。こうすることにより最終製品である焼結チタン部材の空孔を拡大、増加させ、疲労強度の低下を招く原因を減らし、焼結チタン製品または焼結チタン合金製品の伸びなどの機械的特性を十分に満足させるとしている。このため、この発明の構成上、粒度を細かくすることはできず、またその分布は、１０μｍ超のものと、１０μｍ以上１５０μｍ未満のもの予め導入する必要があるため、均一な分布とすることはできない。このため、粉末冶金用チタン粉末の粒度をより細かく、かつ均一にすることはできない。 The particle size distribution in the invention disclosed by Patent Document 3 is more than 10 μm: 0 to 8%, 10 μm or more and less than 150 μm: 90 to 100%. In the titanium-based powder, the oxygen content of the entire powder increases as the amount of fine powder having a small particle diameter increases, and chlorine as an impurity is biased and contained in the fine powder having a particle diameter of 10 μm or less. By doing so, the pores of the final product, the sintered titanium member, can be expanded and increased, reducing the cause of the decrease in fatigue strength and ensuring sufficient mechanical properties such as elongation of the sintered titanium product or sintered titanium alloy product. Is trying to satisfy. Therefore, because of the constitution of the present invention, it is not possible to make the particle size fine, and the distribution thereof is more than 10 μm and that of 10 μm or more and less than 150 μm needs to be introduced in advance. Can not. Therefore, the particle size of the titanium powder for powder metallurgy cannot be made finer and uniform.
さらに、特許文献４により開示された発明による水素化チタンまたは水素化合金粉末およびこの水素化チタン粉末を原料として製造されるチタン粉末は、粉末全体に対する特定粒径の範囲の粉末割合を調整する。粒径が６３μｍ（好ましくは４５μｍ）以下の粉末の割合が０〜３０％で、粒径が６３μｍ（好ましくは４５μｍ）超の粉末の割合が７０〜１００％となり、必然的に均一な分布を得ることはできない。 Further, the titanium hydride or hydrogenated alloy powder according to the invention disclosed in Patent Document 4 and the titanium powder produced using this titanium hydride powder as a raw material adjust the ratio of the powder in the range of a specific particle size to the entire powder. The proportion of powder having a particle size of 63 μm (preferably 45 μm) or less is 0 to 30%, and the proportion of powder having a particle size of more than 63 μm (preferably 45 μm) is 70 to 100%, thus inevitably obtaining a uniform distribution. It is not possible.
さらに、特許文献４により開示された発明では、粒径６３μｍ（好ましくは４５μｍ）以下の粉末割合が３０％を越えると、脱水素時における焼結化の進行を緩和、抑制することが困難になり、酸素量も著しく増加するとしている。しかしながら、水素脆化した部分は、水素化による体積膨張のために歪みが入り、そこを起点として亀裂が入り微細に粉砕される。粉砕された粉末は角ばった形状を呈しており、そもそも焼結が進み難い形状である。水素化後の粒径は、水素化処理温度と粉砕処理条件により制御可能である。さらに、脱水素温度を適正化することにより焼結の進行を抑制できる。したがって、粒径６３μｍ（好ましくは４５μｍ）以下の粉末の割合を制御するだけでは細粒化に十分に有効ではない。このため、粉末冶金用チタン粉末の粒度をより細かく、かつ均一にすることはできない。 Further, in the invention disclosed in Patent Document 4, when the powder ratio of the particle size of 63 μm (preferably 45 μm) or less exceeds 30%, it becomes difficult to mitigate or suppress the progress of sintering during dehydrogenation. However, the amount of oxygen will also increase significantly. However, the hydrogen-embrittled portion is distorted due to volume expansion due to hydrogenation, and cracks are generated from the origin and finely pulverized. The crushed powder has a square shape, and the sintering is difficult to proceed in the first place. The particle size after hydrogenation can be controlled by the hydrogenation temperature and the pulverization conditions. Further, the progress of sintering can be suppressed by optimizing the dehydrogenation temperature. Therefore, only controlling the ratio of the powder having a particle size of 63 μm (preferably 45 μm) or less is not sufficiently effective for making the particles fine. Therefore, the particle size of the titanium powder for powder metallurgy cannot be made finer and uniform.
本発明は、従来の技術が有する上記課題に鑑みてなされたものであり、粉末冶金用チタン粉末の粒度をより細かく、かつ均一にすることができ、これにより、粉末冶金用チタン粉末の歩留まりと品質を向上できる技術を提供することを目的とする。 The present invention has been made in view of the above problems that the conventional technology has, and the particle size of the titanium powder for powder metallurgy can be made finer, and can be made uniform, whereby the yield of the titanium powder for powder metallurgy and The purpose is to provide technology that can improve quality.
本発明者は、上記課題を解決するために鋭意検討を重ね、スポンジチタン粒の内部組織がマクロ的に見ると一見連続的ではあるが、その内部組織は連続的につながった空隙により区画されるとともに、互いにそれらの区画が組み合って形成される複数の領域を有することに着目した。 The present inventor has conducted extensive studies in order to solve the above-mentioned problems, and although the internal structure of sponge titanium particles is seemingly continuous when viewed macroscopically, the internal structure is partitioned by continuously connected voids. together, we focused on the Turkey of having a plurality of regions formed Kumia' the compartment thereof with each other.
すなわち、スポンジチタン粒は、初めから一体構造ではなく、より微細な多孔質体の区画領域が組み合ったものである。このため、本発明者は、この区画領域の大きさに着目して、粗大な区画領域が存在しないスポンジチタン粒を選別し、選別したスポンジチタン粒の集合体を水素化脱水素法によるチタン粉製造用スポンジチタンとして用いることにより、水素化粉末の水素化処理速度や粉砕後の水素化粉末および脱水素化した製品粉末の粒度をより細かく、かつ均一にすることができ、これにより、粉末冶金用チタン粉末の歩留まりと品質を向上できることを知見し、さらに検討を重ねて本発明を完成した。 That is, the sponge titanium particles do not have a one-piece structure from the beginning, but are a combination of finer partitioned regions of the porous body. For this reason, the present inventor pays attention to the size of this partitioned region to select sponge titanium particles having no coarse partitioned region, and collects the selected aggregate of sponge titanium particles into titanium powder by a hydrodehydrogenation method. By using it as a titanium sponge for production, it is possible to make the hydrogenation rate of the hydrogenated powder and the particle size of the hydrogenated powder after grinding and the dehydrogenated product powder finer and more uniform, which allows powder metallurgy. The inventors have found that the yield and quality of the titanium powder for use can be improved, and conducted further studies to complete the present invention.
本発明は、空隙を有する本体を備え、該本体に、つながった空隙により区画されるとともに互いに組み合う複数の領域を有する粒度が２０メッシュ以上のスポンジチタン粒の集合体であって、前記スポンジチタン粒の任意の断面において、前記つながった空隙により周囲を囲まれて区画された各領域の面積が４．４９ｍｍ２未満であり、前記つながった空隙により周囲を囲まれて区画された領域の面積が１．５０ｍｍ ２ 超であるものの合計が前記スポンジチタン粒全体の面積の４２％以下である、水素化脱水素法によるチタン粉末の製造用のスポンジチタン粒の集合体である。 The present invention comprises a body having a void, the body is an aggregate of a particle size of 20 mesh or more titanium sponge particles having a plurality of regions mating with each other while being partitioned by an air gap that led, the titanium sponge particles and have you in any cross-section of the area of each region partitioned is surrounded by the connected voids is Ri der than 4.49Mm 2, the connected voids by regions of the compartment surrounded An aggregate of titanium sponge particles for production of titanium powder by the hydrodehydrogenation method, wherein the total of those having an area of more than 1.50 mm 2 is 42% or less of the total area of the titanium sponge particles .
別の観点からは、本発明は、粒度が２０メッシュ以上のスポンジチタン粒の任意の断面における金属組織を光学顕微鏡で観察し、前記断面において、つながった空隙により周囲を囲まれて区画された各領域の面積が４．４９ｍｍ２未満であり、かつ前記つながった空隙により周囲を囲まれて区画化された領域の面積が１．５０ｍｍ ２ 超であるものの合計が前記スポンジチタン粒全体の面積の４２％以下であるスポンジチタン粒を選別し、選別した当該スポンジチタン粒により集合体を構成する、本発明に係るスポンジチタン粒の集合体の製造法である。 From another aspect, the present invention, the particle size is observed metal structure in any cross-section of 20 mesh or more titanium sponge particles with an optical microscope, in the cross section, one by Do wants voids surrounded compartment Ri area 4.49Mm 2 below der of each region, and the whole sum the titanium sponge particles in those areas of the regions which are partitioned is surrounded by a gap that led is 1.50 mm 2 greater and sorting the 42% or less der Ru sponge titanium particles of area, constituting the aggregate by the sponge titanium particles having been selected, a process for producing sponge titanium particles of assembly according to the present invention.
なお、以降の説明では、本発明における「連続的に区画化された閉じた領域」を「単連結領域」ともいう。すなわち、スポンジチタン粒中のチタン部分及び空隙部分は、多くの単連結領域によって構成される。これら単連結領域の面積は、画像の二値化等の画像処理技術を用いることにより、求めることが可能である。 In addition, in the following description, the “continuously partitioned closed region” in the present invention is also referred to as a “single connected region”. That is, titanium portion and the gap portion of the titanium sponge particles in is constituted by a number of simply connected region. The area of these single connected regions can be obtained by using an image processing technique such as binarization of an image.
これらの本発明では、スポンジチタン粒の集合体は、水素化脱水素法によるチタン粉末の製造用であることが好ましく、この場合、チタン粉末は粉末冶金用であることが好ましい。 In these inventions, the aggregate of titanium sponge particles is preferably for producing titanium powder by a hydrodehydrogenation method, and in this case, the titanium powder is preferably for powder metallurgy.
本発明により、例えば粉末冶金用のチタン粉末の粒度をより細かく、かつ均一にすることができ、これにより、チタン粉末の歩留まりと品質を向上できる。 According to the present invention, for example, the particle size of titanium powder for powder metallurgy can be made finer and more uniform, whereby the yield and quality of titanium powder can be improved.
添付図面を参照しながら本発明を説明する。 The present invention will be described with reference to the accompanying drawings.
本発明者は、予め篩いによりその粒径を１１．２ｍｍ＜粒径＜１３．２ｍｍに揃えた通常品位のスポンジチタン粒を用意し、それらのスポンジチタン粒の任意の１断面で切断して樹脂に埋め込み、通常の光学顕微鏡観察試料として調製し、観察した。 The present inventor prepares normal-grade sponge titanium particles having a particle size of 11.2 mm<particle size<13.2 mm prepared beforehand by sieving, and cutting the sponge titanium particles at any one cross section to form a resin. The sample was embedded in the sample and prepared as a normal optical microscope observation sample for observation.
海綿状組織の金属部分は金属光沢を示し、それ以外の空隙部分は樹脂が充填されているために黒く見える。本発明者は、光学顕微鏡観察により、つながった空隙により区画されるとともに互いに組み合う複数の領域を有するスポンジチタン粒の任意の断面における、前記空隙により区画される領域の面積を計測した。 The metal part of the spongy tissue has a metallic luster, and the other voids appear black because they are filled with resin. The present inventor measured the area of a region partitioned by the voids in an arbitrary cross section of titanium sponge particles having a plurality of regions bounded by voids connected to each other and observed by an optical microscope.
図１は、比較的小さい複数の区画から構成されるスポンジチタン粒を示す説明図であり、光学顕微鏡像を元に画像処理を行い、画素が連結している領域（単連結領域）を明示するために濃淡を付けたものである。 FIG. 1 is an explanatory view showing a titanium sponge particle composed of a plurality of relatively small sections, and image processing is performed based on an optical microscope image to clearly show a region where pixels are connected (single connection region). For this reason, it is shaded.
また、図２は、比較的大きい複数の区画から構成されるスポンジチタン粒を示す説明図であり、光学顕微鏡像を元に画像処理を行い、画素が連結している領域（単連結領域）を明示するために濃淡を付けたものである。 In addition, FIG. 2 is an explanatory diagram showing a sponge titanium particle composed of a plurality of relatively large sections, and image processing is performed based on an optical microscope image to determine a region where pixels are connected (single connection region). It is shaded for clarity.
その結果、比較的小さい複数の区画から構成されるスポンジチタン粒（図１）と、巨大な１つの区画とその周囲に微細な多数の区画を伴うスポンジチタン粒（図２）と大きく２種類に分類されることが判明した。 As a result, there are two major types of sponge titanium particles (Fig. 1), which are composed of a plurality of relatively small compartments, and a sponge titanium particle (Fig. 2) with one huge compartment and many fine compartments around it. It turned out to be classified.
しかし、上記の２種類の区画に含まれる海綿状の組織の内部の微細組織の特徴、例えば、金属チタン自体の結晶粒径は互いに類似しており、統計的にも大きな差が認められなかった。 However, the features of the fine structure inside the spongy structure contained in the above two types of compartments, for example, the crystal grain size of metallic titanium itself are similar to each other, and no statistically significant difference was observed. ..
金属と気体水素との反応は、主として、その反応温度とその反応面積によって左右される。しかし、反応はスポンジチタン粒全体として起こるのではなく、水素ガスと直接触れるスポンジチタン粒の外表面はもとより、スポンジチタン粒の内部で観察される連続的な空隙やそれらが多く集まった空洞部や割れ目部を通じてスポンジチタン粒内部に進入し、ついで金属部分に接触して拡散・浸透することにより、金属チタンが水素化する。 The reaction between a metal and gaseous hydrogen depends mainly on its reaction temperature and its reaction area. However, the reaction is not happen as a whole sponge titanium particles, the outer surface of the titanium sponge particles in direct contact with hydrogen gas, as well as Ya continuous voids and they often gathered cavity observed in the interior of the sponge titanium particles The metal titanium is hydrogenated by entering the titanium sponge particles through the cracks and then contacting and diffusing and penetrating the metal part.
その際の進入経路こそが連続した空隙部分に相当する。したがって、つながった空隙部分が多く、かつそれらで区画された領域の大きさが小さければ、水素は容易にスポンジチタン粒内部に進入できるので速やかに金属チタンを水素化物に変えることができる。 The approach route at that time corresponds to the continuous void portion. Therefore, if there are many connected voids and the size of the region partitioned by them is small, hydrogen can easily enter the titanium sponge particles, and therefore metallic titanium can be quickly converted into a hydride.
つながった空隙部分が少なく、かつそれらで区画された領域の大きさが大きければ、水素のスポンジチタン粒への進入は遅くなり、水素の進入は主として樹枝状のスポンジ組織の金属チタン部分を通じての拡散に依存することになる。スポンジチタン粒の内部に存在する無数の閉じた空隙部分は内部が真空になっており、そこに到達した水素は希釈されるため、水素の内部への移動を抑制する働きがある。つまり、大きな区画領域内では水素化の速度が低下する。 If the number of connected voids is small and the size of the region partitioned by them is large, hydrogen will enter the sponge titanium particles slowly, and hydrogen will diffuse mainly through the metallic titanium part of the dendritic sponge tissue. Will depend on. The innumerable closed voids existing inside the titanium sponge particles have a vacuum inside, and the hydrogen that has reached there is diluted, so that it has the function of suppressing the migration of hydrogen into the interior. That is, the hydrogenation rate decreases in a large compartment area.
スポンジチタン粒の水素化をコントロールするためには、この区画領域の大きさとともにその表面積を求めることが望ましいが、区画領域は複雑に組み合っていることや、海綿状の微細構造は非常に微細でフラクタル的様相を有するため、現状ではその表面積の定量的評価は極めて難しい。 In order to control the hydrogenation of titanium sponge particles , it is desirable to determine the surface area as well as the size of this partitioned area, but the partitioned areas are intricately combined and the spongy microstructure is extremely fine. Since it has a fractal aspect, it is extremely difficult to quantitatively evaluate its surface area at present.
そこで、本発明者は、１つのスポンジチタン粒に含まれるつながった空隙部分が多く、かつそれらで区分された領域の数が多いほど、スポンジチタン粒は内部で細かく分断されているので水素化を加速するものと考えた。 Therefore, the inventor of the present invention conducts hydrogenation because the sponge titanium particles are finely divided inside as the number of voids connected to one sponge titanium particle increases and the number of regions divided by them increases. I thought it would accelerate.
図１，２に示すスポンジチタン粒における区画の数は、図１に示すものが４，２４５個であり、図２に示すものが２７，３５７個と、区画の数の上では図２に示すもののほうが多い。これは、巨大な一つの区画の周囲に微細な区画が多数存在しているからである。本発明では、この点に着目し、この巨大な区画が存在するようなスポンジチタン粒では、水素化の処理速度が著しく遅延し、また粉砕後の水素化粉末および脱水素化した製品粉末の粒度が粗く、かつ不均一になることを確認した。 The number of compartments in the titanium sponge particles shown in FIGS. 1 and 2 is 4,245 as shown in FIG. 1 and 27,357 as shown in FIG. 2, which is shown in FIG. 2 in terms of the number of compartments. There are more things. This is because there are many fine sections around one huge section. In the present invention, paying attention to this point, with sponge titanium particles having such huge compartments, the hydrogenation treatment rate is significantly delayed, and the particle size of the hydrogenated powder and the dehydrogenated product powder after pulverization It was confirmed that the roughness was rough and non-uniform.
すなわち、１１．２ｍｍ＜粒径＜１３．２ｍｍに揃えた通常品位のスポンジチタン粒５０個を真空水素加熱炉に装入し、真空引きしながら３７０℃まで昇温した後約３時間保持して、スポンジチタン粒の表面を活性化した後、大気圧で水素ガスを導入しさらに３時間保持した後５０℃まで冷却した。導入した水素ガス量は、装入したスポンジチタン粒の全量がＴｉＨ２に完全に変化するに必要な理論ガス量である。 That is, 50 normal-grade sponge titanium particles having a particle size of 11.2 mm<particle size<13.2 mm were placed in a vacuum hydrogen heating furnace, heated to 370° C. while drawing a vacuum, and then held for about 3 hours. After activating the surface of titanium sponge particles, hydrogen gas was introduced at atmospheric pressure, and the mixture was kept for 3 hours and then cooled to 50°C. The amount of introduced hydrogen gas is the theoretical amount of gas required for completely changing the total amount of titanium sponge particles charged into TiH 2 .
この処理を通じて、５０個のスポンジチタン粒は個別に識別できるように石英ガラス皿上に配列した。石英ガラスは水素化による脆化でスポンジチタン粒の形状が崩れても水素化後の重量を計量できるようにするためである。 Through this process, 50 titanium sponge particles were arranged on a quartz glass dish so that they could be individually identified. This is because quartz glass enables the weight after hydrogenation to be measured even if the shape of titanium sponge particles is broken due to embrittlement due to hydrogenation.
水素化処理後はそのままの状態で取り出して、精密天秤で１／１００００ｇ単位で水素化処理前後の重量を軽量し、ここの粒の水素化による増量を測定した。さらに、５０個のスポンジチタン粒を任意の面で切断し、スポンジチタン粒内部のミクロ組織を現出させて区画の大きさを計測した。 After the hydrogenation treatment, it was taken out as it was, and the weight before and after the hydrogenation treatment was reduced by a precision balance in units of 1/10000 g, and the increase in the amount of the grains due to the hydrogenation was measured. Further, 50 pieces of titanium sponge particles were cut on an arbitrary surface, the microstructure inside the titanium sponge particles was exposed, and the size of the section was measured.
その結果、区画の面積Ｄが４．４９ｍｍ２以上で、かつそれらの区画のｍｍ２数の合計が全体のスポンジチタン粒の画総数の４２％以上の場合、区画中央部での水素化が不十分な部分が存在していた。 As a result, when the area D of the compartments is 4.49 mm 2 or more and the total number of mm 2 of these compartments is 42% or more of the total number of the sponge titanium particles , the hydrogenation in the central part of the compartment is performed. There was an inadequate part.
また、面積Ｄが４．４９ｍｍ２未満の場合、スポンジチタン粒でその一部の表面部の形状が崩れていることが確認された。これは、スポンジチタン粒中のＴｉがＴｉＨ２に変わる時、約２０％の体積膨張があるために、水素化物に変化した部分ではその膨張歪により自発的に亀裂を生じて崩壊しているのである。 In addition, it was confirmed that when the area D was less than 4.49 mm 2 , the shape of the surface part of the titanium sponge particles was broken. This is because when Ti in the sponge titanium particles changes to TiH 2 , there is a volume expansion of about 20%, so the expansion strain causes spontaneous cracking and collapse due to the expansion strain. is there.
このように、スポンジチタン粒の水素化処理に当たっては，その処理速度の目安として、スポンジチタン粒の表面積の代わりに、区画の大きさを代替して使用できる。 Thus, when the hydrogenation process of the sponge titanium grains, as a measure of the processing speed, instead of the surface area of the titanium sponge particles, can be used to substitute the magnitude of the compartment.
すなわち、空隙を有する本体を備え、この本体に、つながった空隙により区画されるとともに互いに組み合う複数の領域を有するスポンジチタン粒の集合体であって、スポンジチタン粒の任意の断面における、空隙により区画される領域の面積が４．４９ｍｍ２未満である、スポンジチタン粒の集合体を、水素化脱水素法によるチタン粉末、特に粉末冶金用チタン粉末の製造用として用いれば、例えば粉末冶金用のチタン粉末の粒度をより細かく、かつ均一にすることができ、これにより、チタン粉末の歩留まりと品質を向上できる。 That is, an aggregate of sponge titanium particles having a main body having a void, and having a plurality of regions which are partitioned by the voids connected to each other and interlock with each other, and are partitioned by the void in an arbitrary cross section of the titanium sponge grain. If an aggregate of sponge titanium particles having an area of less than 4.49 mm 2 is used for the production of titanium powder by hydrodehydrogenation, especially titanium powder for powder metallurgy, for example titanium for powder metallurgy The particle size of the powder can be made finer and more uniform, which improves the yield and quality of the titanium powder.
このスポンジチタン粒の集合体は、スポンジチタン粒の任意の断面における金属組織を光学顕微鏡で観察し、海綿状の組織のうちでつながった空隙により連続的に区画化された閉じた領域の面積が４．４９ｍｍ２未満であるスポンジチタン粒を選別し、選別した当該スポンジチタン粒により集合体を構成することにより、簡単かつ確実に製造できる。 This collection of titanium sponge particles observes the metal structure in any cross-section of the sponge titanium particles with an optical microscope, the area of continuously compartmentalized enclosed area by an air gap which led among the spongy tissue screened titanium sponge particles is less than 4.49mm 2, by configuring the aggregate by sorted the titanium sponge particles, it can be easily and reliably manufactured.
この場合、スポンジチタン粒の任意の断面における、空隙により区画される領域の面積が１．５０ｍｍ２超であるものの合計が該スポンジチタン粒全体の面積の４２％以下であることが好ましい。 In this case, it is preferable that the total area of the regions defined by the voids in the arbitrary section of the titanium sponge particles is more than 1.50 mm 2 and 42% or less of the area of the entire titanium sponge particles .
５種類のスポンジチタン区画サイズを有する、１１．２ｍｍ＜粒径＜１３．２ｍｍに揃えた通常品位のスポンジチタン粒約１Ｋｇずつを水素反応容器に装入し、一旦、１０−４ｔｏｒｒまで減圧した後、次いで炉内温度を５００℃に保持し、スポンジチタン粒重量に対する理論水素ガス量を１気圧になるように導入した後に供給を停止し、反応容器内の圧力の変化を記録した。５種類のスポンジチタン粒とは，以下の通りである。 Approximately 1 kg each of normal grade sponge titanium particles having 11.2 mm<particle size<13.2 mm having 5 kinds of titanium sponge compartment size were charged into a hydrogen reaction vessel, and the pressure was once reduced to 10 −4 torr. Then, the temperature inside the furnace was maintained at 500° C., the theoretical hydrogen gas amount relative to the weight of titanium sponge particles was introduced so as to be 1 atm, the supply was stopped, and the change in the pressure inside the reaction vessel was recorded. The five types of sponge titanium particles are as follows.
(i)1.5ｘ10２mm2≦面積D：比較例
(ii)3.0 mm2≦面積D＜1.5ｘ10２mm2：比較例
(iii)4.5mm2≦面積D＜3.0mm2：比較例
(iv)1.5ｘ10-1mm2≦面積D＜4.5ｘ10-1mm2：本発明例
(v)面積D＜1.5ｘ10-1mm2：本発明例
(i) 1.5x10 2 mm 2 ≤ area D: Comparative example
(ii) 3.0 mm 2 ≦ area D <1.5×10 2 mm 2 : Comparative example
(iii) 4.5 mm 2 ≤ area D <3.0 mm 2 : Comparative example
(iv) 1.5x10 -1 mm 2 ≦ area D <4.5x10 -1 mm 2: Inventive Example
(v) Area D<1.5×10 -1 mm 2 : Example of the present invention
反応容器炉内圧力比率と反応時間との関係を図３のグラフに示す。 The relationship between the reactor pressure ratio in the reactor and the reaction time is shown in the graph of FIG.
反応容器の圧力の変化は、炉内容器内での水素化の進行を示している。 The change in the pressure of the reaction vessel indicates the progress of hydrogenation in the furnace vessel.
図３のグラフに示すように、分類（ｉ）の場合は，約５時間ほどは圧力の低下が起きず、それ以降７０％程度まで低下するが８時間経ってもなかなか下がらない。これは、分類（ｉｉ）でもほぼ同じ傾向を示す。 As shown in the graph of FIG. 3, in the case of classification (i), the pressure did not decrease for about 5 hours, and after that, it decreased to about 70%, but it did not decrease even after 8 hours. This shows almost the same tendency in the classification (ii).
一方、分類（ｉｉｉ）〜（ｖ）の場合は，停滞せず単調に圧力は低下する。これらの場合も、調査した条件下では完全に水素化は完了しない。 On the other hand, in the cases of classifications (iii) to (v), the pressure does not drop and the pressure decreases monotonously. In these cases too, the hydrogenation is not completely complete under the conditions investigated.
生産効率的な観点から、約６時間での反応容器内の圧力比率が４０％程度であるようなスポンジチタン粒を選択し使用することが好ましい。 From the viewpoint of production efficiency, it is preferable to select and use sponge titanium particles such that the pressure ratio in the reaction vessel in about 6 hours is about 40%.
４種類のスポンジチタン区画サイズを有する、１１．２ｍｍ＜粒径＜１３．２ｍｍに揃えた通常品位のスポンジチタン粒１個を熱天秤に装入し、一旦、１０−５ｔｏｒｒまで減圧した。次いで、炉内温度を４００℃に保持した後、水素ガス量を１気圧で９リットル／分の割合で流し、試料の重量変化を測定した。 One normal-grade sponge titanium particle having 11.4 mm<particle size<13.2 mm having four kinds of titanium sponge partition size was charged into a thermobalance and the pressure was once reduced to 10 −5 torr. Then, after the temperature inside the furnace was maintained at 400° C., the amount of hydrogen gas was flowed at 1 atm at a rate of 9 liters/minute to measure the weight change of the sample.
４種類のスポンジチタン粒とは、以下の通りである。 The four types of sponge titanium particles are as follows.
(i)3ｘ10１mm2≦D：比較例
(ii)4.5mm2≦D＜3ｘ101mm2：比較例
(iii)1.5x10-1mm2≦D＜4.5mm2：本発明例
(iv)D＜1.5x10-1mm2：本発明例
(i) 3×10 1 mm 2 ≦D: Comparative example
(ii) 4.5 mm 2 ≤ D <3 x 10 1 mm 2 : Comparative example
(iii) 1.5x10 -1 mm 2 ≤ D <4.5 mm 2 : Example of the present invention
(iv) D<1.5x10 -1 mm 2 : Example of the present invention
水素化反応比率と反応時間の関係を図４のグラフに示す。 The relationship between the hydrogenation reaction ratio and the reaction time is shown in the graph of FIG.
図４のグラフに示すように、分類（ｉ）では１１０時間経過しても水素化反応比率は６０％程度であるが、分類（ｉｉ）〜（ｉｖ）の場合は１に達し、水素化は完了する。しかし、分類（ｉｉ）の場合は５０時間までの水素化速度は分類（ｉ）の場合に近い。分類（ｉｉｉ）〜（ｉＶ）の場合は５０時間の段階で水素化反応比率は０．８を超す。 As shown in the graph of FIG. 4, in the classification (i), the hydrogenation reaction ratio is about 60% even after 110 hours, but in the cases of the classifications (ii) to (iv), the hydrogenation reaction ratio reaches 1 and the hydrogenation is Complete. However, in the case of classification (ii), the hydrogenation rate up to 50 hours is close to that of classification (i). In the case of classification (iii) to (iV), the hydrogenation reaction ratio exceeds 0.8 at the stage of 50 hours.
スポンジチタン粒径が１１．２ｍｍ＜粒径＜１３．２ｍｍで種々のスポンジチタンの区画サイズに分類した粒１０個ずつを水素反応容器に装入し、一旦、１０−４ｔｏｒｒまで減圧した後、次いで炉内温度を８００℃に保持した後、水素ガス量を１気圧で９リットル／分の割合で流しスポンジチタン粒の形状変化を観察し、水素化物生成による形状崩壊の度合いを観察した。 Titanium sponge having a particle size of 11.2 mm <particle size <13.2 mm and classified into various partition sizes of titanium sponge was charged into a hydrogen reaction vessel, and the pressure was once reduced to 10 −4 torr. Then, after keeping the temperature in the furnace at 800° C., hydrogen gas amount was flown at 1 atm at a rate of 9 liters/minute, and the shape change of titanium sponge particles was observed, and the degree of shape collapse due to hydride formation was observed.
結果を表１にまとめて示す。 The results are summarized in Table 1.
区画サイズが４．５ｍｍ２超のもの（Ｎｏ．３，７〜９）では形状崩壊の程度は軽微であった。また、区画サイズが４．５ｍｍ２未満であっても１．５ｍｍ２以上の区画領域の面積合計がスポンジチタン粒全体の面積の４２％を超えるもの（Ｎｏ．６）では形状崩壊の程度は軽微であった。 The degree of shape collapse was slight in the case where the partition size was more than 4.5 mm 2 (No. 3, 7 to 9). In addition, even if the partition size is less than 4.5 mm 2 , if the total area of the partition regions of 1.5 mm 2 or more exceeds 42% of the total area of titanium sponge particles (No. 6), the degree of shape collapse is slight. Met.
表１に示すように、区画サイズが４．５ｍｍ２超のものでは形状崩壊の程度は軽微であった。また、区画サイズが４．５ｍｍ２未満であっても１．５ｍｍ２以上の区画領域の面積合計がスポンジチタン粒全体の面積の４２％を超えるものでは形状崩壊の程度は軽微であった。 As shown in Table 1, the degree of shape collapse was slight when the partition size was more than 4.5 mm 2 . Further, even if the partition size was less than 4.5 mm 2 , if the total area of the partitioned regions of 1.5 mm 2 or more exceeded 42% of the total area of the titanium sponge particles , the degree of shape collapse was slight.
実施例３で水素化したスポンジチタン粒をＲＥＴＳＣＨ社製遊星ミルで粉砕した。粉砕ジャーは２５ｍＬ，硬質鋼球１０ｍｍφを１００個用いてＡｒ雰囲気中で行った。粉砕途中の差異を明らかにするため、粉砕時間は５分間で実施した（３００ｒｐｍ）。粉砕した水素化チタン粉末を真空炉中において８００℃で２４時間の脱水素処理を行った。脱水素処理後の粉末を調査した。結果を表２にまとめて示す。
The titanium sponge particles hydrogenated in Example 3 were ground with a planet mill manufactured by RETSCH. The grinding jar was performed in an Ar atmosphere using 25 mL and 100 hard steel balls 10 mmφ. The grinding time was 5 minutes (300 rpm) to clarify the difference during the grinding. The crushed titanium hydride powder was subjected to dehydrogenation treatment at 800° C. for 24 hours in a vacuum furnace. The powder after the dehydrogenation treatment was investigated. The results are summarized in Table 2.
表２に示すように、本発明例では、平均粒径は５０μｍ未満の細粒が得られたが、比較例では５０μｍを大きく超える結果となった。粉砕時間を長くすれば本発明例と比較例との差は減少するものの、本発明例ではより短時間で粉砕が進むことが分かる。粉砕時間が短くて済むことは、粉砕ジャーや鋼球との凝着による汚染や粉砕中における酸化の程度を少なくすることができることを意味する。 As shown in Table 2, in the examples of the present invention, fine particles having an average particle size of less than 50 μm were obtained, but in the comparative example, the result was significantly larger than 50 μm. It can be seen that although the difference between the example of the present invention and the comparative example is reduced by increasing the pulverization time, the pulverization proceeds in a shorter time in the example of the present invention. The short grinding time means that the contamination due to the adhesion with the grinding jar or the steel balls and the degree of oxidation during the grinding can be reduced.
Claims (4)
前記スポンジチタン粒の任意の断面において、
前記つながった空隙により周囲を囲まれて区画された各領域の面積が４．４９ｍｍ２未満であり、
前記つながった空隙により周囲を囲まれて区画された領域の面積が１．５０ｍｍ ２ 超であるものの合計が前記スポンジチタン粒全体の面積の４２％以下である、
水素化脱水素法によるチタン粉末の製造用のスポンジチタン粒の集合体。 An aggregate of sponge titanium particles having a particle size of 20 mesh or more, which comprises a main body having voids, and which has a plurality of regions which are defined by continuous voids and which interlock with each other,
And have you in any of the cross-section of the sponge titanium particles,
Area of each region partitioned is surrounded by the connected voids is Ri der less than 4.49mm 2,
The total area of the areas surrounded by the connected voids and partitioned by more than 1.50 mm 2 is 42% or less of the total area of the titanium sponge particles,
Aggregate of titanium sponge particles for production of titanium powder by hydrodehydrogenation method .
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