JP6077439B2 - Hydrogen intrusion prevention method - Google Patents

Hydrogen intrusion prevention method Download PDF

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JP6077439B2
JP6077439B2 JP2013264897A JP2013264897A JP6077439B2 JP 6077439 B2 JP6077439 B2 JP 6077439B2 JP 2013264897 A JP2013264897 A JP 2013264897A JP 2013264897 A JP2013264897 A JP 2013264897A JP 6077439 B2 JP6077439 B2 JP 6077439B2
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齋藤　博之
博之 齋藤
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Nippon Telegraph and Telephone Corp
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本発明は、建築物に用いられている鉄鋼などの鋼材における、水素脆化の原因となる水素の侵入を防止する水素侵入防止方法に関するものである。   The present invention relates to a hydrogen intrusion prevention method for preventing intrusion of hydrogen that causes hydrogen embrittlement in steel materials such as steel used in buildings.

建造物などの構造物では、遅れ破壊が問題となることがある。遅れ破壊とは、静的な負荷を受けているある条件下（自然界）で使用している鋼材などが、ある時間の経過後、外見上ではほぼ塑性変形を伴うことなく、突然脆性的に破壊する現象である。この遅れ破壊のメカニズムは十分に解明されていないが、水素が金属に侵入して延性が失われることによる水素脆性によるものと考えられている（特許文献１参照）。このような水素脆化を防ぐために、様々な技術が開発されている。   In structures such as buildings, delayed fracture can be a problem. Delayed fracture means that steel materials used under certain conditions (natural world) under static load suddenly break brittlely with almost no plastic deformation after a certain amount of time. It is a phenomenon. Although the mechanism of this delayed fracture has not been fully elucidated, it is thought to be due to hydrogen embrittlement due to the penetration of hydrogen into the metal and loss of ductility (see Patent Document 1). In order to prevent such hydrogen embrittlement, various techniques have been developed.

特許文献１に示された技術では、予め所定の処理をした鋼材を用いるようにしている。しかしながらこのような技術は、既設の建造物に用いられている鋼材には適用できない。これに対し、塗装などにより、対象となる鋼材を外界より遮断することで、水素の侵入を防止し、水素脆化を防ごうとする技術がある。このような技術により、既設の建造物に用いられている鋼材に対しても、水素侵入の防止について一定の効果が得られている。   In the technique disclosed in Patent Document 1, a steel material that has been subjected to a predetermined treatment is used. However, such a technique cannot be applied to steel materials used in existing buildings. On the other hand, there is a technique for preventing hydrogen intrusion and preventing hydrogen embrittlement by shielding a target steel material from the outside by painting or the like. With such a technique, a certain effect is obtained with respect to prevention of hydrogen intrusion even for steel materials used in existing buildings.

特開２０１１−２５６４２２号公報JP 2011-256422 A

ところで、建造物によっては、水没した状態で用いられる場合もある。このように屋外で水に接触している状態では、特に、水素イオンや水の還元によって水素が発生し易い環境であり、水素が侵入し易い状態である。しかしながら、水没するなどの状態では、塗装などを施すことができないため、水素の侵入を防止することが容易ではないという問題があった。   By the way, depending on the building, it may be used in a submerged state. Thus, in the state where it is in contact with water outdoors, it is an environment in which hydrogen is likely to be generated due to reduction of hydrogen ions or water, and hydrogen is likely to enter. However, there is a problem that it is not easy to prevent the invasion of hydrogen because it cannot be painted in a state where it is submerged.

本発明は、以上のような問題点を解消するためになされたものであり、屋外で水に接触している鋼材に対する水素の侵入が、抑制できるようにすることを目的とする。   The present invention has been made to solve the above-described problems, and an object of the present invention is to prevent hydrogen from entering a steel material that is in contact with water outdoors.

本発明に係る水素侵入防止方法は、屋外で水に接触している鋼材に、Ｆｅより貴な電位を示す所定の金属から構成された電極を接続する第１工程と、鋼材に接触している水に電極を接触させて鋼材と電極との間の電位差により鋼材に対する水素の侵入を抑制する第２工程とを備え、電極は、第２工程における鋼材の電位が、Ｆｅの電位−ｐＨ図において水中でＦｅ（ＯＨ）3が安定に存在する範囲となる金属から構成する。例えば、電極は、Ｃｕから構成すればよい。 The hydrogen intrusion prevention method according to the present invention is in contact with a steel material, a first step of connecting an electrode made of a predetermined metal exhibiting a potential nobler than Fe to a steel material in contact with water outdoors. And a second step of suppressing hydrogen intrusion into the steel material by a potential difference between the steel material and the electrode by contacting the electrode with water, and the electrode has a potential of the steel material in the second step in the Fe potential-pH diagram. It is made of a metal in a range where Fe (OH) 3 is stably present in water. For example, the electrode may be made of Cu.

以上説明したことにより、本発明によれば、屋外で水に接触している鋼材に対する水素の侵入が、抑制できるようになるという優れた効果が得られる。   As described above, according to the present invention, it is possible to obtain an excellent effect that hydrogen can be prevented from entering a steel material that is in contact with water outdoors.

図１は、本発明の実施の形態における水素侵入防止方法を説明するための説明図である。FIG. 1 is an explanatory diagram for explaining a hydrogen intrusion prevention method according to an embodiment of the present invention. 図２は、Ｆｅの電位−ｐＨ図である。FIG. 2 is a potential-pH diagram of Fe.

以下、本発明の実施の形態について図を参照して説明する。図１は、本発明の実施の形態における水素侵入防止方法を説明するための説明図である。図１では、水素侵入防止方法が実施される状態を示している。   Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram for explaining a hydrogen intrusion prevention method according to an embodiment of the present invention. FIG. 1 shows a state where the hydrogen intrusion prevention method is implemented.

この方法では、まず、屋外で水１０２に接触している鋼材１０１に、鉄（Ｆｅ）より貴な電位を示す所定の金属から構成された電極１０３を接続する（第１工程）。鋼材１０１は、既設の建造物を構成するものである。例えば、リード線１０４により、鋼材１０１と電極１０３とを接続すればよい。   In this method, first, an electrode 103 made of a predetermined metal having a potential nobler than iron (Fe) is connected to a steel material 101 that is in contact with water 102 outdoors (first step). The steel material 101 constitutes an existing building. For example, the steel material 101 and the electrode 103 may be connected by the lead wire 104.

次に、図１に示すように、鋼材１０１に接触している水１０２に電極１０３を接触させる（第２工程）。水１０２に電極１０３を接触させることで、鋼材１０１と電極１０３との間の電位差により鋼材１０１に対する水素の侵入を抑制する。ここで、電極１０３は、第２工程における鋼材１０１の電位が、Ｆｅの電位−ｐＨ図において水１０２中でＦｅ（ＯＨ）3が安定に存在する範囲となる状態の金属から構成することが重要となる。例えば、電極１０３は、銅（Ｃｕ）から構成すればよい。 Next, as shown in FIG. 1, the electrode 103 is brought into contact with water 102 in contact with the steel material 101 (second step). By bringing the electrode 103 into contact with the water 102, entry of hydrogen into the steel material 101 is suppressed by a potential difference between the steel material 101 and the electrode 103. Here, it is important that the electrode 103 is made of a metal in a state where the potential of the steel material 101 in the second step is in a range where Fe (OH) 3 stably exists in the water 102 in the Fe potential-pH diagram. It becomes. For example, the electrode 103 may be made of copper (Cu).

屋外における水１０２は、例えば、雨水がもととなるものであり、中性から弱酸性を示す。このとき、図２に示すＦｅの電位−ｐＨ図（Pourbaix Diagram）より、鋼材の主成分であるＦｅは、水と共存するとイオン化し、図２に示す「水素発生腐食域」で水素を発生する。このようにして発生する水素の一部が、鋼材に侵入してしまう。   The outdoor water 102 is based on rainwater, for example, and exhibits neutral to weak acidity. At this time, from the potential-pH diagram (Pourbaix Diagram) of Fe shown in FIG. 2, Fe, which is the main component of the steel material, ionizes when coexisting with water, and generates hydrogen in the “hydrogen generation corrosion zone” shown in FIG. . Part of the hydrogen generated in this way enters the steel material.

上述した状態に対し、Ｆｅより貴な電位を示す所定の金属から構成された電極１０３を鋼材１０１に電気的に接続し、電極１０３も水１０２に接触させると、雨水などの水１０２中では，電極１０３がカソードとなり、鋼材１０１はアノードとなる。この結果、水素は電極１０３で発生するようになり、鋼材１０１の表面における水素の発生が防止できるようになる。   In contrast to the above-described state, when the electrode 103 made of a predetermined metal having a potential nobler than Fe is electrically connected to the steel material 101 and the electrode 103 is also brought into contact with the water 102, in the water 102 such as rainwater, The electrode 103 becomes a cathode, and the steel material 101 becomes an anode. As a result, hydrogen is generated at the electrode 103, and generation of hydrogen on the surface of the steel material 101 can be prevented.

ここで、水１０２に接触して鋼材１０１と電極１０３との間に電位差が生じている状態で、鋼材１０１の電位が図２のＦｅ（ＯＨ）3が安定な領域に入るように、電極１０３の金属を選択すればよい。鋼材１０１の電位が図２のＦｅ（ＯＨ）3が安定な領域に入る状態とするためには、上記電位差が０．４Ｖ程度であることが好ましい。鋼材１０１の主成分はＦｅであるので、電極１０３は、例えばＣｕから構成すればよい。なお、鋼材１０１と電極１０３の間隔は、近づけすぎると、電極１０３で発生した水素が、鋼材１０１に拡散して到達することが考えられる。このため、鋼材１０１と電極１０３との間隔は、１ｍｍ以上とし、電極１０３で発生した水素を、鋼材１０１に到達する前に水１０２より外気中に拡散させることが好ましい。 Here, in a state where a potential difference is generated between the steel material 101 and the electrode 103 in contact with the water 102, the electrode 103 is set so that the potential of the steel material 101 enters the region where Fe (OH) 3 in FIG. 2 is stable. You can select any metal. In order for the potential of the steel material 101 to be in a state where the Fe (OH) 3 in FIG. 2 enters a stable region, the potential difference is preferably about 0.4V. Since the main component of the steel material 101 is Fe, the electrode 103 may be made of Cu, for example. Note that if the distance between the steel material 101 and the electrode 103 is too close, hydrogen generated at the electrode 103 may be diffused and reach the steel material 101. For this reason, it is preferable that the distance between the steel material 101 and the electrode 103 is 1 mm or more, and the hydrogen generated at the electrode 103 is diffused into the outside air from the water 102 before reaching the steel material 101.

ところで、鋼材１０１が水没すると、電極１０３も同様に水没することが重要となる。ここで、一部の領域の鋼材１０１の近傍に電極１０３を配置した状態では、他の一部の領域の鋼材１０１が水没した状態では、電極１０３が水没しない場合が発生する。このため、電極１０３は、対象となる鋼材１０１の周囲に、一様に設けられているとよい。例えば、網状の形状とした電極１０３を、鋼材１０１の周囲に一様に配置すればよい。   By the way, when the steel material 101 is submerged, it is important that the electrode 103 is submerged as well. Here, in a state where the electrode 103 is arranged in the vicinity of the steel material 101 in a part of the region, the electrode 103 may not be submerged in a state where the steel material 101 in the other part of the region is submerged. For this reason, the electrode 103 is good to be provided uniformly around the steel material 101 used as object. For example, the net-like electrode 103 may be uniformly arranged around the steel material 101.

上述した実施の形態によれば、鋼材１０１は、アノードとして電流を流失するが、水素の侵入を免れることになる。アノードとして流失する電流についても、実際にはＦｅ（ＯＨ）3が安定な被膜となるので、値としての電流は極めて小さい。電極１０３をＣｕから構成した場合、実験上、鋼材１０１において流失する電流は、０．１μＡ・ｃｍ-2以下であり，平均的には年に１μｍ程度以下の腐食速度であった。 According to the above-described embodiment, the steel material 101 loses current as an anode, but escapes hydrogen intrusion. Regarding the current that flows away as the anode, since the Fe (OH) 3 is actually a stable film, the current as a value is extremely small. When the electrode 103 is made of Cu, the current flowing through the steel material 101 is 0.1 μA · cm −2 or less experimentally, and the average corrosion rate is about 1 μm or less per year.

Ｃｕから構成した電極１０３を用い、既設の建造物を構成している鋼材１０１に対して本発明の水素侵入防止を実施した実験で、７２時間経過した段階で、鋼材１０１に含まれる水素を分析した。この結果、鋼材１０１と同じ新品の比較材と同じ値であり、鋼材１０１中の水素量は全く増加していなかった。   In the experiment in which hydrogen intrusion prevention according to the present invention was performed on the steel material 101 constituting the existing building using the electrode 103 made of Cu, the hydrogen contained in the steel material 101 was analyzed after 72 hours had passed. did. As a result, it was the same value as the new comparison material same as the steel material 101, and the amount of hydrogen in the steel material 101 did not increase at all.

以上に説明したように、本発明によれば、屋外で水に接触している鋼材に、Ｆｅより貴な電位を示す所定の金属から構成された電極を接続するようにしたので、屋外で水に接触している鋼材に対する水素の侵入が、抑制できるようになる。特に、鋼材が、既設の建造物を構成しているものである場合であっても、上記電極を接続すればよいので、非常に簡便に実施することができる。   As described above, according to the present invention, an electrode made of a predetermined metal having a noble potential than Fe is connected to a steel material in contact with water outdoors. Intrusion of hydrogen into the steel material in contact with the steel can be suppressed. In particular, even when the steel material constitutes an existing building, it is only necessary to connect the above electrodes, and therefore, it can be carried out very simply.

なお、本発明は以上に説明した実施の形態に限定されるものではなく、本発明の技術的思想内で、当分野において通常の知識を有する者により、多くの変形および組み合わせが実施可能であることは明白である。   The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious.

１０１…鋼材、１０２…水、１０３…電極、１０４…リード線。   101 ... Steel, 102 ... Water, 103 ... Electrode, 104 ... Lead wire.

Claims (2)

屋外で水に接触している鋼材に、Ｆｅより貴な電位を示す所定の金属から構成された電極を接続する第１工程と、
前記鋼材に接触している前記水に前記電極を接触させて前記鋼材と前記電極との間の電位差により前記鋼材に対する水素の侵入を抑制する第２工程と
を備え、
前記電極は、前記第２工程における前記鋼材の電位が、Ｆｅの電位−ｐＨ図において水中でＦｅ（ＯＨ）3が安定に存在する範囲となる金属から構成する
ことを特徴とする水素侵入防止方法。 A first step of connecting an electrode made of a predetermined metal exhibiting a potential nobler than Fe to a steel material in contact with water outdoors;
A second step of bringing the electrode into contact with the water in contact with the steel material and suppressing hydrogen intrusion into the steel material due to a potential difference between the steel material and the electrode, and
The electrode is made of a metal in which the electric potential of the steel material in the second step is in a range where Fe (OH) 3 stably exists in water in the Fe electric potential-pH diagram. . 請求項１記載の水素侵入防止方法において、
前記電極は、Ｃｕから構成することを特徴とする水素侵入防止方法。 In the hydrogen intrusion prevention method according to claim 1,
The method for preventing hydrogen intrusion, wherein the electrode is made of Cu.
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