JPH0570930A - Crevice corrosion resistant surface modified ti or ti base alloy member - Google Patents
Crevice corrosion resistant surface modified ti or ti base alloy memberInfo
- Publication number
- JPH0570930A JPH0570930A JP25973391A JP25973391A JPH0570930A JP H0570930 A JPH0570930 A JP H0570930A JP 25973391 A JP25973391 A JP 25973391A JP 25973391 A JP25973391 A JP 25973391A JP H0570930 A JPH0570930 A JP H0570930A
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- Prior art keywords
- layer
- base alloy
- alloy member
- corrosion resistance
- forming
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Other Surface Treatments For Metallic Materials (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、耐隙間腐食性の改善さ
れたＴｉまたはＴｉ基合金部材に関し、特に非酸化性酸
溶液や高温高濃度塩化物溶液を使用する化学プラントや
原子力プラントの構成部材として利用できる様にしたＴ
ｉまたはＴｉ基合金部材に関するものである。尚以下の
説明ではＴｉ（純Ｔｉ）を代表的にとりあげるが、本発
明で対象とする部材は純Ｔｉに限らず、例えばＴｉ−６
Ａｌ−４Ｖ，Ｔｉ−１５Ｍｏ−５Ｚｒ，Ｔｉ−１５Ｍｏ
−５Ｚｒ−３Ａｌ等の種々のＴｉ基合金に対して同様に
適用することができる。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Ti or Ti-based alloy member having improved crevice corrosion resistance, and particularly to the construction of a chemical plant or a nuclear plant using a non-oxidizing acid solution or a high temperature high concentration chloride solution. T that can be used as a member
The present invention relates to an i- or Ti-based alloy member. In the following description, Ti (pure Ti) will be taken up as a representative, but the member targeted by the present invention is not limited to pure Ti, and for example, Ti-6
Al-4V, Ti-15Mo-5Zr, Ti-15Mo
It can be similarly applied to various Ti-based alloys such as -5Zr-3Al.
【０００２】[0002]
【従来の技術】Ｔｉは、高融点，軽量，高強度等の特長
を有すると共に耐腐食性にも優れており、一部の化学プ
ラントや原子力プラント等の分野において使用されてい
る。しかしながらＴｉの耐食性にも限界があり、腐食事
故例がこれまで数多く報告されている。その多くは、高
温高濃度塩化物中における隙間腐食事故である。またＴ
ｉは硝酸のような酸化性の環境においては卓越した耐食
性を示すと言われていたが、この様な環境下においても
応力腐食割れや粒界腐食による部材の損傷が報告されて
いる。更にＴｉの耐食性は不動態化皮膜の保護作用によ
って達成されるものであるから、塩酸や硫酸の様な非酸
化性環境においては活性腐食を起こし耐食性が著しく劣
化する。こうしたことから、Ｔｉは極く限られた工業分
野においてしか適用されていないのが実情である。2. Description of the Related Art Ti has characteristics such as high melting point, light weight, and high strength, and is also excellent in corrosion resistance, and is used in some fields such as chemical plants and nuclear plants. However, Ti has a limited corrosion resistance, and many cases of corrosion accidents have been reported so far. Most of them are crevice corrosion accidents in high temperature and high concentration chloride. Also T
Although i was said to exhibit excellent corrosion resistance in an oxidizing environment such as nitric acid, damage to the member due to stress corrosion cracking and intergranular corrosion was also reported under such an environment. Further, since the corrosion resistance of Ti is achieved by the protective action of the passivation film, active corrosion occurs in a non-oxidizing environment such as hydrochloric acid or sulfuric acid, and the corrosion resistance is significantly deteriorated. For these reasons, the fact is that Ti is applied only in a very limited industrial field.
【０００３】そこでＴｉの耐食性を改善するという観点
から、Ｔｉの合金化法や表面処理法が検討されてきた
が、いずれも十分なものとは言えなかった。まず合金化
法では、これまでにＰｄやＮｉ等の元素を添加して耐食
性改善を図ってきたが、これら合金の耐食性は純Ｔｉよ
りも改善されるとはいうものの、次の様な実用上の問題
を有している。 (1) コスト高であること。 (2) 高温での機械的強度が保たれる反面、機械加工性が
悪い。 (3) 上記(1),(2) の問題点を回避するためには、合金化
元素の濃度を希望量まで高めることができず、十分な耐
食性を発揮するには至らない。Therefore, from the viewpoint of improving the corrosion resistance of Ti, alloying methods and surface treatment methods of Ti have been studied, but none of them was sufficient. First, in the alloying method, elements such as Pd and Ni have been added so far to improve the corrosion resistance. However, although the corrosion resistance of these alloys is improved as compared with pure Ti, the following practical use is required. Have a problem. (1) High cost. (2) The mechanical strength at high temperature is maintained, but the machinability is poor. (3) In order to avoid the problems of (1) and (2) above, the concentration of alloying elements cannot be increased to a desired amount, and sufficient corrosion resistance cannot be exhibited.
【０００４】一方表面処理法による耐食性改善として
は、パラジウム酸化皮膜の付与等が挙げられ、一部実用
化されているが、耐食性能の改善には限界があり、ごく
限られた範囲内でしか適用されていない。これは次に挙
げる様な事項に起因していると考えられる。 (1) 基本的に耐食性皮膜の密着性が悪く、密着性を少し
でも改善する為には前処理工程として酸洗や脱脂等を行
なう必要があり、且つ汚れ防止のために十分留意する必
要がある。これによって工程が煩雑になるが、それでも
尚皮膜の剥離が起こりやすい。 (2) 形成された皮膜の均一性が悪く且つピンホール等の
欠陥が発生すること等によって、十分な耐食性能が得ら
れない。On the other hand, examples of the improvement of corrosion resistance by the surface treatment method include the addition of a palladium oxide film and the like, which has been partially put into practical use. However, there is a limit to the improvement of corrosion resistance and it is only within a very limited range. Not applicable It is considered that this is due to the following items. (1) Basically, the adhesion of the corrosion-resistant film is poor, and in order to improve the adhesion even a little, it is necessary to perform pickling and degreasing as a pretreatment step, and it is necessary to pay sufficient attention to prevent stains. is there. Although this complicates the process, the film is still likely to peel off. (2) Sufficient corrosion resistance cannot be obtained due to poor uniformity of the formed film and generation of defects such as pinholes.
【０００５】[0005]
【発明が解決しようとする課題】本発明はこうした事情
に着目してなされたものであって、機械加工性を損なう
ことなく、しかもＴｉ素地との密着性の問題を本質的に
含まない表面処理層を簡素な工程で形成することができ
るような技術、殊にそのような表面処理層を形成するこ
とによって得られる耐食性、特に耐隙間腐食性に優れた
ＴｉまたはＴｉ基合金部材を提供することを目的とする
ものである。The present invention has been made in view of these circumstances, and is a surface treatment that does not impair the machinability and essentially does not include the problem of adhesion to the Ti substrate. To provide a technique by which a layer can be formed by a simple process, in particular, a Ti or Ti-based alloy member excellent in corrosion resistance obtained by forming such a surface-treated layer, particularly excellent in crevice corrosion resistance. The purpose is.
【０００６】[0006]
【課題を解決するための手段】しかして上記目的を達成
した本発明のＴｉ部材は、Ｔｉ（またはＴｉ基合金）部
材の表面にＴａをイオン注入して、ＴｉまたはＴｉ基合
金の表層部にＴａの濃度富化層すると共に、高温酸化処
理によって、Ｔａの濃度富化層にＴｉの酸化層を重畳し
て形成したものである点に要旨を有するものである。The Ti member of the present invention, which has achieved the above object, is obtained by ion-implanting Ta into the surface of a Ti (or Ti-based alloy) member to form a surface layer portion of Ti or a Ti-based alloy. It has a gist in that it is formed by superposing a Ti concentration-enriched layer on a Ta concentration-enriched layer and a Ti concentration-enriched layer by a high temperature oxidation treatment.
【０００７】[0007]
【作用】本発明で利用されるイオン注入の手法は、加速
された高エネルギーのイオンを目的深さまで打ち込んで
Ｔｉ部材の表面を改質するものであり、半導体分野にお
ける不純物ドーピング手段として利用されている他、鋼
を中心とする金属材料の表面改質にもその適用が進めら
れているが、半導体分野を除けばこれまでのところ実用
化はあまり進んでいない。The ion implantation method used in the present invention is to implant accelerated high-energy ions to a target depth to modify the surface of a Ti member, and is used as an impurity doping means in the semiconductor field. In addition to its application, it is being applied to the surface modification of metallic materials such as steel, but it has not been put to practical use so far except in the semiconductor field.
【０００８】本発明に係るＴｉ部材は、このようなイオ
ン注入の手法をＴｉ部材の表面改質に利用したものであ
り、Ｔｉ部材表層部にはイオン注入によって非熱平衡物
質層が形成される。即ちこれまで行なわれてきた熱プロ
セスによる合金化や表面処理では、熱的平衡状態にある
合金層あるいは表面皮膜が形成され、該合金層は熱平衡
物質層であるが故にその物性改造にも自ずから限度があ
った。これに対し本発明では非熱平衡物質層を形成する
ことにより、従来からは予測できない特性を得ることが
できる。換言すればイオン注入される元素と同じ元素を
添加したＴｉ合金を形成しても本発明のＴｉ部材のよう
な耐摩耗性の発揮は期待することができないのである。The Ti member according to the present invention uses such an ion implantation technique for surface modification of the Ti member, and a non-thermal equilibrium substance layer is formed on the surface layer of the Ti member by ion implantation. That is, in the alloying or surface treatment by the thermal process that has been performed so far, an alloy layer or a surface film in a thermal equilibrium state is formed, and since the alloy layer is a thermal equilibrium substance layer, its physical properties are naturally limited. was there. On the other hand, in the present invention, by forming the non-thermal equilibrium material layer, it is possible to obtain characteristics that cannot be predicted conventionally. In other words, even if a Ti alloy containing the same element as the ion-implanted element is formed, it cannot be expected that the Ti member of the present invention exhibits wear resistance.
【０００９】ところでＴｉ部材の特性を改善するに当た
っては、Ｔｉ部材にイオン注入を行ないさえすれば良い
と言うものではなく、改善しようとする特性に合せて特
定の元素イオンを選び、且つその注入量および注入エネ
ルギーを適当に設定する必要がある。本発明において
は、種々の元素イオンについてイオン注入実験を重ねた
結果、Ｔｉ部材の耐食性を改善する為には、Ｔａをイオ
ン注入してＴｉ部材の表層部にＴａ濃度富化層を形成す
ればよいことを知った。また高温酸化処理によって、前
記Ｔａ濃度富化層にＴｉの酸化層を重畳して形成すれ
ば、Ｔｉ部材の耐食性が飛躍的に改善されることを知っ
た。Ｔａ濃度富化層若しくはＴｉ酸化層のいずれかを単
独に形成しても、Ｔｉ部材の耐食性はある程度改善され
るが、これらのいずれかを単独に形成するよりも複合的
に形成することによってその耐食性改善は飛躍的に達成
されたのである。In order to improve the characteristics of the Ti member, it is not necessary to implant ions into the Ti member, but a specific element ion is selected according to the characteristics to be improved, and the amount of implantation thereof. And it is necessary to set the implantation energy appropriately. In the present invention, as a result of repeated ion implantation experiments for various elemental ions, in order to improve the corrosion resistance of the Ti member, Ta is ion-implanted to form a Ta concentration-enriched layer on the surface layer of the Ti member. I found it good. Further, it has been found that the corrosion resistance of the Ti member is dramatically improved by forming a Ti oxide layer on the Ta concentration-enriched layer by the high temperature oxidation treatment. The formation of either the Ta concentration-enriched layer or the Ti oxide layer alone improves the corrosion resistance of the Ti member to some extent. However, by forming any one of them in a composite manner, The improvement in corrosion resistance has been achieved dramatically.
【００１０】またイオン注入では高エネルギーイオンを
Ｔｉ部材の表層部に強制的に添加するが、表面層に別物
質層が形成される訳ではないので、注入層と基材層はマ
トリックス構造が同じである。従ってめっき等の表面処
理のように基材と異なる材質の皮膜を密着させる場合と
異なり、イオン注入表層部の基材層との一体性は極めて
良好であり、剥離の問題は生じない。In ion implantation, high-energy ions are forcibly added to the surface layer of the Ti member, but since a separate material layer is not formed on the surface layer, the implantation layer and the base material layer have the same matrix structure. Is. Therefore, unlike the case where a film made of a material different from that of the base material is brought into close contact as in the case of surface treatment such as plating, the integrity of the ion-implanted surface layer portion with the base material layer is extremely good, and no peeling problem occurs.
【００１１】本発明に係るＴｉ部材は上記作用効果を奏
するものであるが、これらの効果を得るにはＴａイオン
を１×1015イオン／cm2 以上注入することが望まれる。
一方過剰に注入すると注入エネルギーに応じてスパッタ
現象による表面切削現象が顕著になるので、注入エネル
ギーおよび注入量は慎重に決定する必要がある。こうし
た観点からすれば、注入エネルギーは５ＫｅＶ以上と
し、且つ注入量は夫々１×1018イオン／cm2 以下に抑え
ることが望ましい。またＴａ濃度富化層とＴｉ酸化層の
深さや広がりがずれていると、単一イオンを注入した場
合と同様の効果しか得られないので、Ｔａ濃度富化層と
Ｔｉ酸化層が重畳して形成される必要があり、その為に
も注入角度，注入エネルギーおよび注入量を適切に選定
する必要がある。The Ti member according to the present invention has the above-mentioned effects, and in order to obtain these effects, it is desirable to inject Ta ions at 1 × 10 15 ions / cm 2 or more.
On the other hand, if the implantation is excessive, the surface cutting phenomenon due to the spattering phenomenon becomes remarkable depending on the implantation energy. Therefore, it is necessary to carefully determine the implantation energy and the implantation amount. From this point of view, it is desirable that the implantation energy is 5 KeV or more and the implantation amount is suppressed to 1 × 10 18 ions / cm 2 or less. Further, if the depth and the spread of the Ta concentration-enriched layer and the Ti oxide layer are different, only the same effect as in the case of implanting a single ion can be obtained. Therefore, it is necessary to properly select the implantation angle, the implantation energy and the implantation amount.
【００１２】尚Ｔｉ酸化層を形成するための高温酸化処
理の具体的方法については特に限定されるものではな
く、例えば高温焼鈍，陽極酸化等が挙げられる。また高
温酸化処理条件についても特に限定されるものではな
く、例えば５００℃，３０分程度でも十分な効果を有す
るものである。The specific method of the high temperature oxidation treatment for forming the Ti oxide layer is not particularly limited, and examples thereof include high temperature annealing and anodic oxidation. Further, the high temperature oxidation treatment condition is not particularly limited, and a sufficient effect can be obtained even at about 500 ° C. for about 30 minutes.
【００１３】[0013]
実験１ 表１に示す各種イオン注入Ｔｉ部材（実施例はＴａのイ
オン注入と酸化処理）について、耐隙間腐食試験を行な
ったところ、表１に併記する結果が得られた。尚耐隙間
腐食試験は、マルチクレビス法を用いた沸騰４２％塩化
マグネシウム溶液中に１００時間浸漬した場合の隙間腐
食発生確率によって評価し、この値が小さいほど良好な
耐食性を有することを示している。Experiment 1 Various ion-implanted Ti members shown in Table 1 (Ta ion-implanted and oxidized in the examples) were subjected to a crevice corrosion resistance test, and the results shown in Table 1 were obtained. The crevice corrosion resistance test was evaluated by the probability of crevice corrosion occurring when immersed in a boiling 42% magnesium chloride solution using the multi-clevis method for 100 hours. The smaller this value, the better the corrosion resistance. ..
【００１４】表１から明らかな様に、Ｔａを単独でイオ
ン注入した場合でも耐隙間腐食性の改善は認められる
が、Ｔａ濃度富化層およびＴｉ酸化層を重畳して形成し
てたＴｉ部材が最も隙間腐食発生確率が小さく、耐隙間
腐食性に優れていることがわかる。As is clear from Table 1, even when Ta is ion-implanted alone, the crevice corrosion resistance is improved, but a Ti member formed by overlapping the Ta concentration-enriched layer and the Ti oxide layer is formed. Indicates that the probability of occurrence of crevice corrosion is the smallest and the crevice corrosion resistance is excellent.
【００１５】[0015]
【表１】 [Table 1]
【００１６】実験２ 表２に示す各種イオン注入Ｔｉ部材（実施例はＴａのイ
オン注入と酸化処理）について、沸騰１０％硫酸中にお
ける腐食試験を行ない、均一腐食速度を比較したとこ
ろ、表２に併記する結果が得られた。尚相対的均一腐食
速度は、非注入材の値を１とした場合の相対量で示し
た。Experiment 2 Various ion-implanted Ti members shown in Table 2 (in the example, Ta ion-implanted and oxidized) were subjected to a corrosion test in boiling 10% sulfuric acid to compare the uniform corrosion rates. The results described together were obtained. The relative uniform corrosion rate is shown as a relative amount when the value of the non-injection material is 1.
【００１７】表２から明らかな様に、Ｔａ濃度富化層お
よびＴｉ酸化層を重畳して形成したＴｉ部材が最も均一
腐食速度が小さく、著しい耐食性改善効果を示している
ことがわかる。またＴａを単独にイオン注入してもある
程度の耐食性改善効果は認められるが、Ｔａ濃度富化層
とＴｉ酸化層を重畳して形成したＴｉ部材の腐食性改善
効果には遥かに及ばない。As is clear from Table 2, the Ti member formed by superposing the Ta concentration-enriched layer and the Ti oxide layer has the lowest uniform corrosion rate and shows a remarkable effect of improving the corrosion resistance. Even if Ta is ion-implanted alone, a certain degree of corrosion resistance improving effect is recognized, but it is far inferior to the corrosiveness improving effect of the Ti member formed by overlapping the Ta concentration-enriched layer and the Ti oxide layer.
【００１８】[0018]
【表２】 [Table 2]
【００１９】[0019]
【発明の効果】本発明は以上のように構成されており、
機械加工性を損なうことなく、しかもＴｉ素地との密着
性の問題を本質的に含まない表面処理層を簡単な工程で
形成することができ、この表面処理層の形成によって優
れた耐隙間腐食性を示すＴｉ（またはＴｉ基合金）部材
を得ることができた。かくして従来では使用が困難であ
った腐食性環境下においても、好適に使用することがで
き、ＴｉおよびＴｉ基合金部材の適用範囲が大きく拡が
ることが期待される。The present invention is configured as described above,
It is possible to form a surface treatment layer in a simple process that does not impair the machinability and is essentially free from the problem of adhesion with the Ti substrate. The formation of this surface treatment layer provides excellent crevice corrosion resistance. It was possible to obtain a Ti (or Ti-based alloy) member showing Thus, it can be suitably used even in a corrosive environment, which has been difficult to use conventionally, and it is expected that the applicable range of Ti and Ti-based alloy members will be greatly expanded.
Claims (1)
をイオン注入して、ＴｉまたはＴｉ基合金の表層部にＴ
ａの濃度富化層を形成すると共に、高温酸化処理によっ
て、Ｔａの濃度富化層にＴｉの酸化層を重畳して形成し
たものであることを特徴とする耐隙間腐食性表面改質Ｔ
ｉまたはＴｉ基合金部材。1. The surface of a Ti or Ti-based alloy member is Ta.
Is ion-implanted into the surface layer of Ti or Ti-based alloy
a crevice corrosion-resistant surface-modified T characterized by forming a concentration-enriched layer of a and an oxide layer of Ti superimposed on the concentration-enriched layer of Ta by high-temperature oxidation treatment.
i or Ti-based alloy member.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3259733A JP3064562B2 (en) | 1991-09-10 | 1991-09-10 | Crevice corrosion resistant surface-modified Ti or Ti-based alloy member |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3259733A JP3064562B2 (en) | 1991-09-10 | 1991-09-10 | Crevice corrosion resistant surface-modified Ti or Ti-based alloy member |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0570930A true JPH0570930A (en) | 1993-03-23 |
| JP3064562B2 JP3064562B2 (en) | 2000-07-12 |
Family
ID=17338193
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3259733A Expired - Fee Related JP3064562B2 (en) | 1991-09-10 | 1991-09-10 | Crevice corrosion resistant surface-modified Ti or Ti-based alloy member |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3064562B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07288191A (en) * | 1994-12-05 | 1995-10-31 | Hitachi Ltd | Plasma treatment method and apparatus therefor |
| US5562952A (en) * | 1993-11-11 | 1996-10-08 | Nissin Electric Co., Ltd. | Plasma-CVD method and apparatus |
| US6110287A (en) * | 1993-03-31 | 2000-08-29 | Tokyo Electron Limited | Plasma processing method and plasma processing apparatus |
-
1991
- 1991-09-10 JP JP3259733A patent/JP3064562B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6110287A (en) * | 1993-03-31 | 2000-08-29 | Tokyo Electron Limited | Plasma processing method and plasma processing apparatus |
| US5562952A (en) * | 1993-11-11 | 1996-10-08 | Nissin Electric Co., Ltd. | Plasma-CVD method and apparatus |
| JPH07288191A (en) * | 1994-12-05 | 1995-10-31 | Hitachi Ltd | Plasma treatment method and apparatus therefor |
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| Publication number | Publication date |
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| JP3064562B2 (en) | 2000-07-12 |
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