JP2017160504A - SURFACE TREATMENT METHOD OF Ti-Al-BASED ALLOY - Google Patents
SURFACE TREATMENT METHOD OF Ti-Al-BASED ALLOY Download PDFInfo
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本発明は、表面に酸化物層あるいは酸素濃化層が形成されたＴｉ−Ａｌ系合金をＣａＣｌ２から成る溶融塩に浸漬させて、酸化物層あるいは酸素濃化層をＴｉ−Ａｌ系合金の表面から除去するＴｉ−Ａｌ系合金の表面処理方法に関するものである。 In the present invention, a Ti—Al based alloy having an oxide layer or oxygen enriched layer formed on the surface thereof is immersed in a molten salt made of CaCl 2 , and the oxide layer or oxygen enriched layer is made of Ti—Al based alloy. The present invention relates to a surface treatment method for a Ti—Al alloy to be removed from the surface.
近年、軽量・高耐食性・高比強度といった特徴を活かし、航空機などの輸送機用素材としてＴｉ−Ａｌ系合金の需要が増加している。Ｔｉ−Ａｌ系合金の製造工程である鋳造、鍛造、切削等の工程では、大量のスクラップが発生するが、これら各工程においては、スクラップの表面に主に酸化物あるいは酸素濃化層から構成される汚染層が形成される。ここで、酸化物濃化層とは、高濃度の酸素が溶存しているＴｉ−Ａｌ系合金のことを指し、その溶存酸素濃度は０．１〜５．０質量％の範囲内のものをいう。 In recent years, taking advantage of features such as light weight, high corrosion resistance, and high specific strength, demand for Ti-Al alloys as materials for transport aircraft such as aircraft has been increasing. A large amount of scrap is generated in processes such as casting, forging, and cutting, which are Ti-Al alloy manufacturing processes. In each of these processes, the surface of the scrap is mainly composed of an oxide or oxygen-enriched layer. A contaminated layer is formed. Here, the oxide concentrated layer refers to a Ti-Al alloy in which high concentration of oxygen is dissolved, and the dissolved oxygen concentration is within the range of 0.1 to 5.0 mass%. Say.
このような酸化物などから成る汚染層（酸化物層あるいは酸素濃化層）が表面に形成されたスクラップは、介在物の混入や不純物濃度の増加等といった品質上の懸念があり、再生原料としての利用は制限されているという課題がある。 Scraps with a contaminated layer (oxide layer or oxygen-enriched layer) formed of such oxides on the surface have quality concerns such as inclusion inclusions and an increase in impurity concentration. There is a problem that the use of is restricted.
このように、Ｔｉ−Ａｌ系合金スクラップは再生原料として利用されることは殆どないのが現状であるが、Ｔｉ合金などのスクラップの再生利用法としては、例えば、特許文献１〜３に記載された技術が提案されている。 Thus, the present situation is that Ti-Al alloy scrap is rarely used as a recycled raw material. However, as a method of recycling scrap of Ti alloy or the like, it is described in, for example, Patent Documents 1 to 3. Technologies have been proposed.
特許文献１に記載された提案は、表面に不純物が付着したチタン溶解用原料等の金属スクラップを５００℃以上に加熱した後これを水槽に浸して急冷することにより該不純物に亀裂を生じさせ、その後これにショットピーニングをして該不純物を金属スクラップから離脱させようという金属スクラップの前処理方法に関する提案である。 In the proposal described in Patent Document 1, a metal scrap such as a titanium melting raw material with impurities attached to the surface is heated to 500 ° C. or higher, and then immersed in a water bath to rapidly cool the impurities, This is a proposal concerning a pretreatment method for metal scrap in which the impurities are removed from the metal scrap by shot peening.
しかし、ショットピーニングにより表面に付着したガラス層から成る不純物を離脱させようという方法であるため、ショット（鋼球）噴射時にガラス層のみならず、母材のチタン合金まで離脱してしまう可能性が極めて高く、材料ロスが懸念される。 However, because it is a method to remove impurities consisting of the glass layer adhering to the surface by shot peening, there is a possibility that not only the glass layer but also the titanium alloy of the base material will be detached at the time of shot (steel ball) injection. There is concern about material loss.
特許文献２に記載された提案は、低融点金属が付着しているチタン含有スクラップを該低融点金属の融点以上に加熱して溶融除去する工程、ブラスト処理又は切削によりチタン表面のチタン化合物を除去する工程、酸洗する工程及び真空溶解する工程からなるチタン含有スクラップからのチタンの回収方法に関する提案である。 The proposal described in Patent Document 2 removes the titanium compound on the surface of titanium by blasting or cutting, in which the titanium-containing scrap to which the low-melting-point metal is attached is heated to a melting point of the low-melting-point metal or higher. It is a proposal regarding the recovery method of titanium from the titanium containing scrap which consists of the process to perform, the process to pickling, and the process to melt | dissolve in a vacuum.
しかしながら、チタン表面のチタン化合物の除去は、例えば、アルミナ系のサンドブラストで除去するという工程で行われている。この方法も、チタン化合物の除去に伴い、母材のチタンまでが脱落する可能性が極めて高い方法であり、同様に材料ロスが懸念される。 However, the removal of the titanium compound on the titanium surface is performed, for example, in a process of removing with an alumina-based sandblast. This method is also a method with a very high possibility that even the titanium of the base material will fall off with the removal of the titanium compound, and there is a concern about material loss as well.
特許文献３に記載された提案は、チタンまたはチタン合金からなるインゴットの少なくとも両端面に酸化防止剤を塗布する工程と、そのインゴットを加熱する工程と、その加熱されたインゴットを熱間分塊圧延する工程と、その熱間分塊圧延により得られたブルームまたはビレットの両端部を切断する工程と、その切断により得られたスクラップを細かく裁断しチタン原料片とする工程を含むチタンスクラップの再利用方法に関する提案である。 The proposal described in Patent Document 3 includes a step of applying an antioxidant to at least both end faces of an ingot made of titanium or a titanium alloy, a step of heating the ingot, and hot block rolling of the heated ingot. Recycling of titanium scrap, including the step of cutting, the step of cutting both ends of the bloom or billet obtained by the hot block rolling, and the step of finely cutting the scrap obtained by the cutting into a titanium raw material piece It is a proposal regarding the method.
しかしながら、この方法はインゴットにホウ酸およびケイ酸の混合物でなる酸化防止剤を塗布する工程を含む方法であり、事前処理による酸化防止が必要な方法で、また、塗布した酸化防止剤が混入してスクラップを汚染してしまう可能性が懸念される方法である。 However, this method includes a step of applying an antioxidant made of a mixture of boric acid and silicic acid to an ingot, and is a method that requires anti-oxidation by pretreatment, and the applied antioxidant is mixed. This is a method that is concerned about the possibility of contaminating scrap.
また、本発明ではＴｉ−Ａｌ系合金の表層からのＡｌの溶出抑制と脱酸の両立が必要であるが、Ｔｉ−Ａｌ系合金の脱酸に関する技術としては、特許文献４や非特許文献１に記載された技術が知られている。 Further, in the present invention, it is necessary to suppress both elution of Al from the surface layer of the Ti—Al-based alloy and deoxidation. As techniques relating to deoxidation of the Ti—Al-based alloy, Patent Document 4 and Non-Patent Document 1 The technique described in is known.
本発明は、上記従来の問題を解決せんとしてなされたもので、Ｔｉ−Ａｌ系合金の表面に形成される酸化物層あるいは酸素濃化層を、母材の材料ロスや、汚染の影響を受けることなく、除去することができるＴｉ−Ａｌ系合金の表面処理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 as a solution to the above-mentioned conventional problems, and the oxide layer or oxygen-enriched layer formed on the surface of the Ti—Al alloy is affected by material loss of the base material and contamination. It is an object of the present invention to provide a surface treatment method for a Ti—Al alloy that can be removed without any problems.
本発明のＴｉ−Ａｌ系合金の表面処理方法は、表面に酸化物層あるいは酸素濃化層が形成されたＴｉ−Ａｌ系合金をＣａＣｌ２から成る溶融塩に浸漬させて、前記酸化物層あるいは酸素濃化層を前記Ｔｉ−Ａｌ系合金の表面から除去するＴｉ−Ａｌ系合金の表面処理方法であって、前記Ｔｉ−Ａｌ系合金は、Ａｌを３０．０〜３６．０質量％、Ｎｂを４．０〜６．０質量％、Ｃｒを２．０〜４．０質量％含有し、残部がＴｉおよび不可避的不純物からなり、前記ＣａＣｌ２から成る溶融塩には、還元剤および脱酸剤としてＡｌ濃度が１０．０〜１５．０質量％のＣａＡｌ合金を、前記溶融塩中のＣａＡｌ合金濃度が１０．０質量％以上になるようにして添加することを特徴とする。 The surface treatment method for a Ti—Al based alloy according to the present invention comprises immersing a Ti—Al based alloy having an oxide layer or oxygen-concentrated layer formed on a surface thereof in a molten salt composed of CaCl 2 , and the oxide layer or A surface treatment method for a Ti—Al based alloy that removes an oxygen-enriched layer from the surface of the Ti—Al based alloy, wherein the Ti—Al based alloy comprises 30.0 to 36.0% by mass of Al, Nb 4.0 to 6.0 mass%, Cr 2.0 to 4.0 mass%, with the balance being Ti and inevitable impurities, and the molten salt composed of CaCl 2 includes a reducing agent and deoxidation. A CaAl alloy having an Al concentration of 10.0 to 15.0 mass% is added as an agent so that the CaAl alloy concentration in the molten salt is 10.0 mass% or more.
本発明のＴｉ−Ａｌ系合金の表面処理方法によると、Ｔｉ−Ａｌ系合金の表面に形成される酸化物層あるいは酸素濃化層を、母材の材料ロスや、溶融塩や還元剤および脱酸剤による汚染の影響を受けることなく、確実に除去することができる。また併せて、Ｔｉ−Ａｌ系合金の表層からのＡｌの溶出抑制と脱酸を両立することができる。その結果、Ｔｉ−Ａｌ系合金スクラップを再生原料として利用することが可能になる。 According to the surface treatment method for a Ti—Al based alloy of the present invention, the oxide layer or oxygen enriched layer formed on the surface of the Ti—Al based alloy is treated with material loss, molten salt, reducing agent and desorption of the base material. It can be reliably removed without being affected by the contamination with the acid agent. In addition, it is possible to achieve both suppression of elution of Al from the surface layer of the Ti—Al alloy and deoxidation. As a result, Ti—Al alloy scrap can be used as a recycled raw material.
本発明者らは、Ｔｉ−Ａｌ系合金スクラップを再生原料として利用するために、Ｔｉ−Ａｌ系合金の表面に形成される酸化物層あるいは酸素濃化層、詳しくはＴｉＯＸとＡｌＯＸから成る複合酸化物層あるいは酸素濃化層を、母材の材料ロスや、汚染の影響を受けることなく、確実に除去することができる表面処理方法を見出すため、鋭意検討を行った。 In order to use Ti—Al based alloy scrap as a recycled raw material, the present inventors consist of an oxide layer or an oxygen enriched layer formed on the surface of the Ti—Al based alloy, specifically TiO X and AlO X. In order to find a surface treatment method that can reliably remove the composite oxide layer or the oxygen-enriched layer without being affected by material loss or contamination of the base material, intensive studies were conducted.
その結果、表面に酸化物層あるいは酸素濃化層が形成されたＴｉ−Ａｌ系合金をＣａＣｌ２から成る溶融塩に浸漬させることで、前記酸化物層あるいは酸素濃化層をＴｉ−Ａｌ合金の表面から除去することとし、また、溶融塩に添加する還元剤および脱酸剤をＣａＡｌ合金とし、そのＣａＡｌ合金のＡｌ濃度、溶融塩中のＣａＡｌ合金濃度を、適正な範囲とすることで、所望の目的を達成することが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, by immersing a Ti—Al alloy having an oxide layer or oxygen enriched layer on the surface thereof in a molten salt made of CaCl 2 , the oxide layer or oxygen enriched layer is made of Ti—Al alloy. Desirable to remove from the surface, and to make the reducing agent and deoxidizing agent added to the molten salt a CaAl alloy, and by setting the Al concentration of the CaAl alloy and the CaAl alloy concentration in the molten salt within an appropriate range. The inventors have found that the object can be achieved and have completed the present invention.
尚、本明細書ではＣａＡｌ合金などを還元剤および脱酸剤として説明するが、本明細書で説明する還元剤と脱酸剤は実質同じ材料を示す。 In this specification, a CaAl alloy or the like will be described as a reducing agent and a deoxidizing agent, but the reducing agent and the deoxidizing agent described in this specification indicate substantially the same material.
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 embodiments.
本発明は、表面に酸化物層あるいは酸素濃化層が形成されたＴｉ−Ａｌ系合金をＣａＣｌ２から成る溶融塩に浸漬させて、前記酸化物層あるいは酸素濃化層を前記Ｔｉ−Ａｌ系合金の表面から除去するＴｉ−Ａｌ系合金の表面処理方法に係る発明であるが、以下、発明の対象として用いられるＴｉ−Ａｌ系合金の成分組成、溶融塩に添加する還元剤および脱酸剤、溶融塩中の還元剤および脱酸剤の濃度、表面処理を行う際の処理温度および処理時間について、順を追って説明する。 In the present invention, a Ti—Al based alloy having an oxide layer or an oxygen enriched layer formed on the surface thereof is immersed in a molten salt made of CaCl 2 , and the oxide layer or the oxygen enriched layer is made into the Ti—Al based alloy. The invention relates to a surface treatment method for a Ti-Al alloy to be removed from the surface of the alloy. Hereinafter, the component composition of the Ti-Al alloy used as the subject of the invention, the reducing agent and deoxidizing agent added to the molten salt The concentration of the reducing agent and deoxidizing agent in the molten salt, the treatment temperature and the treatment time when performing the surface treatment will be described in order.
（Ｔｉ−Ａｌ系合金の成分組成）
本発明が対象とするＴｉ−Ａｌ系合金は、通称ＧＥ合金と呼称され、主に航空機用ＴｉＡｌ材料として幅広く用いられる合金材料である。詳しくは、Ａｌを３０．０〜３６．０質量％、Ｎｂを４．０〜６．０質量％、Ｃｒを２．０〜４．０質量％含有し、残部がＴｉおよび不可避的不純物からなるＴｉ−Ａｌ系合金である。
(Component composition of Ti-Al alloy)
The Ti—Al-based alloy targeted by the present invention is commonly called a GE alloy, and is an alloy material that is widely used mainly as an aircraft TiAl material. Specifically, Al is contained in an amount of 30.0 to 36.0% by mass, Nb is contained in an amount of 4.0 to 6.0% by mass, Cr is contained in an amount of 2.0 to 4.0% by mass, and the balance is made of Ti and inevitable impurities. Ti-Al alloy.
（溶融塩に添加する還元剤および脱酸剤）
この成分組成のＴｉ−Ａｌ系合金をＣａＣｌ２から成る溶融塩に浸漬することで、表面に形成されたＴｉＯＸとＡｌＯＸから成る複合酸化物層あるいは酸素濃化層が除去されるが、その際、溶融塩には還元剤および脱酸剤としてＣａＡｌ合金を添加する必要がある。
(Reducing agent and deoxidizing agent added to molten salt)
By immersing the Ti—Al based alloy having this component composition in a molten salt composed of CaCl 2, the composite oxide layer or oxygen enriched layer composed of TiO X and AlO X formed on the surface is removed. At this time, it is necessary to add a CaAl alloy to the molten salt as a reducing agent and a deoxidizing agent.
添加するＣａＡｌ合金中のＡｌ濃度は、１０．０〜１５．０質量％の範囲とする。ＣａＡｌ合金中のＡｌ濃度が１０．０質量％未満であると、表面処理時にＴｉ−Ａｌ系合金の表層からＡｌが溶出してしまうため、ＣａＡｌ合金中のＡｌ濃度は、Ｔｉ−Ａｌ系合金の表層からのＡｌの溶出が発生しない１０．０質量％以上とする。 The Al concentration in the CaAl alloy to be added is in the range of 10.0 to 15.0 mass%. When the Al concentration in the CaAl alloy is less than 10.0% by mass, Al elutes from the surface layer of the Ti—Al based alloy during the surface treatment, so the Al concentration in the CaAl alloy is the same as that of the Ti—Al based alloy. It is set to 10.0% by mass or more at which Al elution does not occur from the surface layer.
一方、ＣａＡｌ合金中のＡｌ濃度が高くなると、Ｃａの活量が低下し、還元剤および脱酸剤としての能力が低下する。還元剤および脱酸剤によって、表面処理前のＴｉ−Ａｌ系合金の表層付近の溶存酸素濃度から、少なくとも酸素濃度を２０．０％は低減させる必要があるが、ＣａＡｌ合金中のＡｌ濃度が１５．０質量％を超えると、酸素濃度の低減率は２０．０％未満となり脱酸は不十分となってしまう。よって、ＣａＡｌ合金中のＡｌ濃度の上限は１５．０質量％とする。 On the other hand, when the Al concentration in the CaAl alloy increases, the activity of Ca decreases, and the ability as a reducing agent and a deoxidizing agent decreases. Although it is necessary to reduce the oxygen concentration by at least 20.0% from the dissolved oxygen concentration in the vicinity of the surface layer of the Ti—Al based alloy before the surface treatment by the reducing agent and the deoxidizing agent, the Al concentration in the CaAl alloy is 15%. If it exceeds 0.0 mass%, the oxygen concentration reduction rate is less than 20.0%, and deoxidation becomes insufficient. Therefore, the upper limit of the Al concentration in the CaAl alloy is 15.0% by mass.
（溶融塩中の還元剤および脱酸剤の濃度）
還元剤および脱酸剤が有効に機能するためには、還元剤および脱酸剤を溶融塩中において飽和する濃度以上添加することが必要である。溶融塩中のＣａＡｌ合金濃度が１０．０質量％未満の場合は、ＣａＡｌ合金が全て溶融塩中に溶け込んでしまい、還元剤および脱酸剤として機能しなくなるため、溶融塩中のＣａＡｌ合金の濃度は１０．０質量％以上とする。
(Concentration of reducing agent and deoxidizing agent in molten salt)
In order for the reducing agent and the deoxidizing agent to function effectively, it is necessary to add the reducing agent and the deoxidizing agent at a concentration that saturates in the molten salt. When the concentration of CaAl alloy in the molten salt is less than 10.0% by mass, all the CaAl alloy dissolves in the molten salt and does not function as a reducing agent and a deoxidizing agent. Therefore, the concentration of CaAl alloy in the molten salt Is 10.0 mass% or more.
尚、本発明では溶融塩中のＣａＡｌ合金濃度の上限は特に規定しないが、その濃度が４０．０質量％を超えると還元剤および脱酸剤としての効果が飽和すると共に、溶融塩の絶対量も減少してしまうので、４０．０質量％以下とすることが好ましい。 In the present invention, the upper limit of the CaAl alloy concentration in the molten salt is not particularly specified, but when the concentration exceeds 40.0% by mass, the effect as a reducing agent and a deoxidizing agent is saturated, and the absolute amount of the molten salt. Is also preferably 40.0 mass% or less.
（表面処理を行う際の処理温度および処理時間）
本発明では、Ｔｉ−Ａｌ系合金の表面処理を行う際の処理温度および処理時間は特に規定しないが、処理温度は７５０〜１２００℃の範囲、処理時間は１〜５４０分の範囲とすることが好ましい。
(Processing temperature and processing time for surface treatment)
In the present invention, the treatment temperature and treatment time when performing the surface treatment of the Ti—Al based alloy are not particularly specified, but the treatment temperature is in the range of 750 to 1200 ° C., and the treatment time is in the range of 1 to 540 minutes. preferable.
処理温度が７５０℃未満、処理時間が１分未満の場合は、Ｔｉ−Ａｌ系合金の表面に形成される酸化物層あるいは酸素濃化層の除去が不十分となる可能性がある。一方、処理温度が１２００℃を超えると、処理に用いる容器の酸化或いは減肉が発生するおそれがあるため、処理温度の上限は１２００℃とすることが好ましい。また、酸化物層あるいは酸素濃化層の除去に要する時間は５４０分あれば十分であるため、処理時間の上限は５４０分とすることが好ましい。 When the treatment temperature is less than 750 ° C. and the treatment time is less than 1 minute, there is a possibility that the removal of the oxide layer or the oxygen enriched layer formed on the surface of the Ti—Al-based alloy may be insufficient. On the other hand, if the treatment temperature exceeds 1200 ° C, oxidation or thinning of the container used for the treatment may occur, so the upper limit of the treatment temperature is preferably 1200 ° C. In addition, since the time required for removing the oxide layer or the oxygen-enriched layer is 540 minutes, the upper limit of the treatment time is preferably 540 minutes.
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 described more specifically with reference to examples. However, the present invention is not limited by the following examples, and the present invention is implemented with appropriate modifications within a range that can meet the gist of the present invention. These are all included in the technical scope of the present invention.
（表面に形成された酸化物層あるいは酸素濃化層の除去に対する有効性）
表面にＴｉＯＸとＡｌＯＸから成る複合酸化物層が形成されたＴｉ−３３質量％Ａｌ−４．８質量％Ｎｂ−２．７質量％Ｃｒ合金サンプル（５ｍｍ×５ｍｍ×３０ｍｍ）を、純チタン製の内容器（φ５０ｍｍ×５０ｍｍ）とＳＵＳ製の外容器（φ７６ｍｍ×１００ｍｍ）から成る２重容器内に装入した。
(Effectiveness for removing oxide layer or oxygen-enriched layer formed on the surface)
A Ti-33 mass% Al-4.8 mass% Nb-2.7 mass% Cr alloy sample (5 mm × 5 mm × 30 mm) with a composite oxide layer made of TiO X and AlO X formed on the surface is made of pure titanium. A double container consisting of an inner container (φ50 mm × 50 mm) made of SUS and an outer container (φ76 mm × 100 mm) made of SUS was charged.
その後、前記２重容器の内部に、表１に示す各成分組成の還元剤および脱酸剤：５４ｇと、溶融塩としてＣａＣｌ２：１６０ｇをそれぞれ追装し、ＳＵＳ製の蓋で閉じて溶接することで密閉し、処理温度９００℃、処理時間１８０分（大気下）の条件で、前記合金サンプルの表面処理をそれぞれ実施した。 Thereafter, 54 g of reducing agent and deoxidizing agent of each component composition shown in Table 1 and CaCl 2 : 160 g as a molten salt are respectively added to the inside of the double container, and closed with a SUS lid and welded. Then, the alloy samples were subjected to a surface treatment under the conditions of a treatment temperature of 900 ° C. and a treatment time of 180 minutes (in the atmosphere).
Ｎｏ．１〜３では、それぞれ異なる成分組成の還元剤および脱酸剤を用いており、Ｎｏ．１ではＣａ単独の還元剤および脱酸剤を、Ｎｏ．２では前記非特許文献１の記載に基づいて求めた成分組成の還元剤および脱酸剤を、Ｎｏ．３では本発明の成分組成を満足する還元剤および脱酸剤を、それぞれ用いて合金サンプルの表面処理を実施した。 No. 1 to 3 use a reducing agent and a deoxidizing agent having different component compositions, respectively. In No. 1, a reducing agent and a deoxidizing agent containing only Ca were used. In No. 2, the reducing agent and the deoxidizing agent having the component composition obtained based on the description of Non-Patent Document 1 are No. In No. 3, the surface treatment of the alloy sample was performed using a reducing agent and a deoxidizing agent that satisfy the composition of the present invention.
還元剤および脱酸剤の成分組成ごとに、各合金サンプルの表面処理後の複合酸化物層の除去状況を表１に示す。また、Ｎｏ．２については、表面処理前後の合金サンプルのＳＥＭ−ＥＤＸ：Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ− Ｅｎｅｒｇｙ Ｄｉｓｐｅｒｓｉｖｅ Ｘ−ｒａｙ Ｓｐｅｃｔｒｏｓｃｏｐ（走査型電子顕微鏡）による断面写真を、図１および図２にそれぞれ示す。 Table 1 shows the removal status of the composite oxide layer after the surface treatment of each alloy sample for each component composition of the reducing agent and the deoxidizing agent. No. 2, cross-sectional photographs of the alloy samples before and after the surface treatment by SEM-EDX: Scanning Electron Microscope- Energy Dispersive X-ray Spectroscope (scanning electron microscope) are shown in FIGS. 1 and 2, respectively.
図１および図２によると、表面処理前には合金サンプルの表面に厚さ７５μｍ程度の複合酸化物層が形成されていたが、表面処理後にはその複合酸化物層が消失していることが分かる。また、同時に複合酸化物層以外のメタル部の材料ロスは確認されず、また、ＳＥＭ−ＥＤＸによる観察の結果、還元剤および脱酸剤と溶融塩からのＣａやＣｌによる汚染も確認できなかった。尚、Ｎｏ．１およびＮｏ．３については特に断面写真を示さないが、Ｎｏ．２と同様に表面処理後には複合酸化物層が消失した。 According to FIGS. 1 and 2, a complex oxide layer having a thickness of about 75 μm was formed on the surface of the alloy sample before the surface treatment, but the complex oxide layer disappeared after the surface treatment. I understand. At the same time, no material loss of the metal part other than the composite oxide layer was confirmed, and as a result of observation by SEM-EDX, contamination by Ca and Cl from the reducing agent, deoxidizing agent and molten salt could not be confirmed. . No. 1 and no. No particular cross-sectional photograph is shown for No. 3, but no. Similar to 2, the composite oxide layer disappeared after the surface treatment.
（表層からのＡｌの溶出抑制と脱酸に対する有効性）
酸化物層の除去に対する有効性を確認した前記合金サンプルと同じ３種の合金サンプルを用いて、各合金サンプルの表面から５０μｍの領域で、表面処理前後でＡｌおよび酸素（Ｏ）の濃度がどのように変化したか確認した。成分分析はＳＥＭ−ＥＤＸを用いて行った。結果を表２に示す。
(Suppression of Al elution from surface layer and effectiveness against deoxidation)
Using the same three types of alloy samples as the above-described alloy samples that have been confirmed to be effective for removing the oxide layer, the concentration of Al and oxygen (O) before and after the surface treatment is determined in the region of 50 μm from the surface of each alloy sample. It was confirmed whether it changed. Component analysis was performed using SEM-EDX. The results are shown in Table 2.
まず、Ａｌ濃度について比較した。表面処理前の母合金のＡｌ濃度と、表面処理後のＮｏ．１〜３のＡｌ濃度を比較すると、Ｎｏ．１ではＡｌ濃度が３３質量％から１９質量％に低下しているのに対し、Ｎｏ．２とＮｏ．３では濃度変化がない。 First, the Al concentration was compared. The Al concentration of the mother alloy before the surface treatment and the No. after the surface treatment. When the Al concentrations of 1 to 3 are compared, In No. 1, the Al concentration decreased from 33% by mass to 19% by mass. 2 and No. In 3, there is no change in density.
この結果は、Ｎｏ．１では表層付近のＡｌが溶出してしまっていることを示している。これに対し、Ｎｏ．２とＮｏ．３では、溶解塩に還元剤および脱酸剤としてＡｌ濃度が１０．０質量％以上のＣａＡｌ合金を添加しているため、合金サンプルの表層からのＡｌの溶出が抑止された。 This result is shown in No. 1 indicates that Al in the vicinity of the surface layer has eluted. In contrast, no. 2 and No. In No. 3, since a CaAl alloy having an Al concentration of 10.0% by mass or more was added as a reducing agent and a deoxidizing agent to the dissolved salt, elution of Al from the surface layer of the alloy sample was suppressed.
尚、合金サンプル（Ｔｉ−Ａｌ系合金）からのＡｌ溶出反応は下記の式で示すことができる。
Ａｌ（ｉｎ ＴｉＡｌ）＋Ｃａ（ｉｎ ｓａｌｔ）＝ＣａＡｌ（ｉｎ ｓａｌｔ）
The Al elution reaction from the alloy sample (Ti-Al alloy) can be expressed by the following equation.
Al (in TiAl) + Ca (in salt) = CaAl (in salt)
次に、酸素（Ｏ）濃度について比較した。溶解塩にＣａ単独の還元剤および脱酸剤を添加したＮｏ．１では、溶存酸素濃度が表面処理前の母合金の０．１５質量％から０．０８質量％まで低下しているのに対し、溶解塩に還元剤および脱酸剤としてＡｌ濃度が１６．４質量％のＣａＡｌ合金を添加したＮｏ．２では、溶存酸素濃度が０．１３質量％までしか低下しておらず、酸素濃度の低減率は２０．０％未満である。 Next, the oxygen (O) concentration was compared. No. 1 in which a reducing agent and a deoxidizing agent containing Ca alone were added to the dissolved salt. 1, the dissolved oxygen concentration decreased from 0.15% by mass to 0.08% by mass of the mother alloy before the surface treatment, whereas the dissolved salt had an Al concentration of 16.4 as a reducing agent and a deoxidizing agent. No. with a mass% CaAl alloy added. In 2, the dissolved oxygen concentration is reduced only to 0.13% by mass, and the reduction rate of the oxygen concentration is less than 20.0%.
一方、溶解塩に還元剤および脱酸剤としてＡｌ濃度が１１．５質量％のＣａＡｌ合金を添加したＮｏ．３では、溶存酸素濃度が０．１０質量％まで低下しており、Ｎｏ．１の低減率には及ばないものの、酸素濃度の低減率２０．０％以上を達成することができた。この結果は、ＣａＡｌ合金中のＡｌ濃度を１５．０質量％以下とすることで、Ｃａ活量の低下を脱酸反応に問題がない程度に抑制することができていることを示している。 On the other hand, No. 1 was prepared by adding a CaAl alloy having an Al concentration of 11.5% by mass as a reducing agent and a deoxidizing agent to the dissolved salt. In No. 3, the dissolved oxygen concentration is reduced to 0.10% by mass. Although the reduction rate of 1 was not reached, a reduction rate of oxygen concentration of 20.0% or more could be achieved. This result has shown that the fall of Ca activity can be suppressed to such an extent that there is no problem in a deoxidation reaction by making Al concentration in a CaAl alloy into 15.0 mass% or less.
尚、合金サンプル（Ｔｉ−Ａｌ系合金）の脱酸反応は下記の式で示すことができる。
Ｏ（ｉｎ ＴｉＡｌ）＋Ｃａ（ｉｎ ｓａｌｔ）＝ＣａＯ（ｉｎ ｓａｌｔ）
The deoxidation reaction of the alloy sample (Ti-Al alloy) can be expressed by the following formula.
O (in TiAl) + Ca (in salt) = CaO (in salt)
以上の結果から、溶解塩に添加する還元剤および脱酸剤としてＡｌ濃度が１０．０〜１５．０質量％のＣａＡｌ合金を用いることで、Ｔｉ−Ａｌ系合金の表層からのＡｌの溶出抑制と脱酸を両立することができることが確認できた。 From the above results, by using a CaAl alloy having an Al concentration of 10.0 to 15.0% by mass as a reducing agent and a deoxidizing agent to be added to the dissolved salt, suppression of elution of Al from the surface layer of the Ti—Al-based alloy is achieved. It was confirmed that it was possible to achieve both deoxidation and deoxidation.
Claims (1)
前記Ｔｉ−Ａｌ系合金は、Ａｌを３０．０〜３６．０質量％、Ｎｂを４．０〜６．０質量％、Ｃｒを２．０〜４．０質量％含有し、残部がＴｉおよび不可避的不純物からなり、
前記ＣａＣｌ２から成る溶融塩には、還元剤および脱酸剤としてＡｌ濃度が１０．０〜１５．０質量％のＣａＡｌ合金を、前記溶融塩中のＣａＡｌ合金濃度が１０．０質量％以上になるようにして添加することを特徴とするＴｉ−Ａｌ系合金の表面処理方法。 A Ti—Al based alloy having an oxide layer or oxygen enriched layer formed on the surface is immersed in a molten salt made of CaCl 2 , and the oxide layer or oxygen enriched layer is exposed from the surface of the Ti—Al based alloy. A surface treatment method of a Ti-Al alloy to be removed,
The Ti-Al alloy contains 30.0 to 36.0% by mass of Al, 4.0 to 6.0% by mass of Nb, and 2.0 to 4.0% by mass of Cr, with the balance being Ti and Consisting of inevitable impurities,
In the molten salt composed of CaCl 2, a CaAl alloy having an Al concentration of 10.0 to 15.0% by mass as a reducing agent and a deoxidizing agent, and a CaAl alloy concentration in the molten salt of 10.0% by mass or more. A surface treatment method for a Ti—Al alloy, characterized by comprising adding in such a manner.
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| CN112575221A (en) * | 2020-11-24 | 2021-03-30 | 钢铁研究总院 | TiAl alloy powder and preparation method and application thereof |
| JP7403135B2 (en) | 2021-08-31 | 2023-12-22 | トーホーテック株式会社 | Method for producing TiAl intermetallic compound powder, TiAl intermetallic compound powder, and spherical TiAl intermetallic compound powder |
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| CN112575221A (en) * | 2020-11-24 | 2021-03-30 | 钢铁研究总院 | TiAl alloy powder and preparation method and application thereof |
| CN112575221B (en) * | 2020-11-24 | 2021-11-02 | 钢铁研究总院 | TiAl alloy powder and preparation method and application thereof |
| JP7403135B2 (en) | 2021-08-31 | 2023-12-22 | トーホーテック株式会社 | Method for producing TiAl intermetallic compound powder, TiAl intermetallic compound powder, and spherical TiAl intermetallic compound powder |
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