JP3381621B2 - Corrosion sensor - Google Patents
Corrosion sensorInfo
- Publication number
- JP3381621B2 JP3381621B2 JP11707898A JP11707898A JP3381621B2 JP 3381621 B2 JP3381621 B2 JP 3381621B2 JP 11707898 A JP11707898 A JP 11707898A JP 11707898 A JP11707898 A JP 11707898A JP 3381621 B2 JP3381621 B2 JP 3381621B2
- Authority
- JP
- Japan
- Prior art keywords
- corrosion
- corrosion sensor
- oxide film
- sensor
- evaluation surface
- 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.)
- Expired - Lifetime
Links
- 230000007797 corrosion Effects 0.000 title claims description 133
- 238000005260 corrosion Methods 0.000 title claims description 133
- 238000011156 evaluation Methods 0.000 claims description 37
- 230000001681 protective effect Effects 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 6
- 239000002253 acid Substances 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims 1
- 230000008018 melting Effects 0.000 claims 1
- 230000001590 oxidative effect Effects 0.000 claims 1
- 238000012360 testing method Methods 0.000 description 23
- 230000010287 polarization Effects 0.000 description 15
- 239000000463 material Substances 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 12
- 229910000831 Steel Inorganic materials 0.000 description 11
- 239000010959 steel Substances 0.000 description 11
- 238000002474 experimental method Methods 0.000 description 9
- 239000011248 coating agent Substances 0.000 description 8
- 238000000576 coating method Methods 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- 238000002848 electrochemical method Methods 0.000 description 6
- 239000003973 paint Substances 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 239000004809 Teflon Substances 0.000 description 4
- 229920006362 Teflon® Polymers 0.000 description 4
- 229920005989 resin Polymers 0.000 description 4
- 239000011347 resin Substances 0.000 description 4
- 238000005530 etching Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 229910001651 emery Inorganic materials 0.000 description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 239000011253 protective coating Substances 0.000 description 2
- 229920002050 silicone resin Polymers 0.000 description 2
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229910052755 nonmetal Inorganic materials 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000011410 subtraction method Methods 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、腐食センサーに関
する。さらに詳しくは、本発明は、腐食の評価を行うに
際して、評価面以外のすき間腐食などの発生を防止し、
正しく腐食の度合いを評価することができる腐食センサ
ーに関する。TECHNICAL FIELD The present invention relates to a corrosion sensor. More specifically, the present invention prevents the occurrence of crevice corrosion other than the evaluation surface when evaluating corrosion,
The present invention relates to a corrosion sensor that can accurately evaluate the degree of corrosion.
【０００２】[0002]
【従来の技術】工場設備を長年にわたってその性能を維
持しつつ安全に運転するためには、設備の設計段階から
適切な防食の施策をとって腐食の進行を抑えるととも
に、設備の腐食の度合いをモニターして、すき間腐食や
孔食の発生を予知し、操業停止などの不測の事態を未然
に防止する必要がある。腐食の度合いのモニタリングに
は対象となる設備の材料と同質の金属からなる腐食セン
サーが用いられる。従来より、水中に腐食センサーを浸
漬して腐食の評価を行う場合、腐食の評価面以外の部分
の腐食の発生を防止するために、塗料や樹脂などを塗布
するか、あるいは非金属系のもので被覆する手段が用い
られてきた。例えば、特許第２５３６３６４号公報に
は、孔食モニタリング用のテストピースとして、評価面
に溝を設けることにより、表面の酸化皮膜を部分的に除
去したテストピースが提案されているが、このテストピ
ースも、溝部以外の表面には、樹脂の被覆層が設けられ
ている。このような塗料や樹脂などを塗布する方法は、
常温などの比較的低温での測定においては有効な手段で
ある。しかし、比較的高温の腐食環境下では、塗料や樹
脂などの劣化が生じやすく、鋼材への密着性が低下し、
極端な場合にははがれ落ちて、本来の防食の役割を果た
さなくなる。また、熱収縮チューブやテフロンチューブ
などの非金属系の材料で被覆した場合には、被覆した部
分と被覆をしていない部分の境目に段差を生じたり、密
着性が悪く鋼材と被覆材料との間にすき間が生じ、すき
間腐食などの局部的な腐食が生じてしまうという問題が
あった。このために、高温域においても劣化が生ずるこ
とがなく、鋼材と被覆材料との間にすき間腐食が生ずる
こともなく、高温の環境下においても正しく腐食の評価
を実施することができる腐食センサーが求められてい
る。2. Description of the Related Art In order to safely operate factory equipment for many years while maintaining its performance, appropriate corrosion protection measures should be taken from the equipment design stage to suppress the progress of corrosion and to control the degree of corrosion of equipment. It is necessary to monitor and predict the occurrence of crevice corrosion and pitting corrosion, and prevent unforeseen circumstances such as operation shutdown. To monitor the degree of corrosion, a corrosion sensor made of the same metal as the material of the target equipment is used. Conventionally, when immersing a corrosion sensor in water to evaluate corrosion, paint or resin is applied or non-metal type is used to prevent the occurrence of corrosion on parts other than the corrosion evaluation surface. Have been used. For example, Japanese Patent No. 2536364 proposes, as a test piece for monitoring pitting corrosion, a test piece in which an oxide film on the surface is partially removed by providing a groove on an evaluation surface. Also, a resin coating layer is provided on the surface other than the groove. The method of applying such paints and resins is
It is an effective means for measurement at relatively low temperatures such as room temperature. However, in a relatively high temperature corrosive environment, the paint, resin, etc. are likely to deteriorate, and the adhesion to the steel material decreases,
In extreme cases, it peels off and does not play its original role of anticorrosion. When coated with a non-metallic material such as a heat-shrinkable tube or Teflon tube, a step may occur at the boundary between the covered portion and the uncoated portion, and the adhesion is poor and the steel material and the coating material There is a problem that a gap is generated in the gap and localized corrosion such as crevice corrosion occurs. For this reason, there is no deterioration even in the high temperature region, no crevice corrosion occurs between the steel material and the coating material, and there is a corrosion sensor that can accurately evaluate corrosion even in a high temperature environment. It has been demanded.
【０００３】[0003]
【発明が解決しようとする課題】本発明は、腐食の評価
を行うに際して、評価面以外のすき間腐食などの発生を
防止し、正しく腐食の度合いを評価することができる腐
食センサーを提供することを目的としてなされたもので
ある。SUMMARY OF THE INVENTION The present invention provides a corrosion sensor capable of preventing the occurrence of crevice corrosion other than the evaluation surface and evaluating the degree of corrosion correctly when evaluating corrosion. It was done for the purpose.
【０００４】[0004]
【課題を解決するための手段】本発明者らは、上記の課
題を解決すべく鋭意研究を重ねた結果、腐食センサーの
非評価面を酸化皮膜で覆うことにより、高温で使用して
も皮膜が剥落することがなく、皮膜と鋼材の間にすき間
を生ずることもないことを見いだし、この知見に基づい
て本発明を完成するに至った。すなわち、本発明は、
（１）腐食の評価面となる露出部と非評価面となる保護
皮膜部を有する腐食センサーであって、保護皮膜が加熱
によって形成された酸化皮膜であることを特徴とする腐
食センサー、
（２）腐食センサーが高温用である第１項に記載の腐食
センサー、
（３）保護皮膜が、３００〜４００℃に加熱されて形成
されたことを特徴とする第１項又は第２項に記載の腐食
センサー、
（４）露出部が、酸化皮膜を酸によって化学的に溶解し
て除去することにより形成されてなることを特徴とする
第１項、第２項及び第３項のいずれかに記載の腐食セン
サー、及び、
（５）腐食の評価面となる露出部が、エッチング処理に
より活性化されてなることを特徴とする第１項、第２
項、第３項及び第４項のいずれかに記載の腐食センサ
ー、を提供するものである。Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that by coating the non-evaluation surface of a corrosion sensor with an oxide film, the film can be used even at high temperatures. It has been found that there is no peeling off and there is no gap between the coating and the steel material, and the present invention has been completed based on this finding. That is, the present invention is: (1) A corrosion sensor having an exposed portion serving as a corrosion evaluation surface and a protective coating portion serving as a non-evaluation surface, wherein the protective coating is an oxide coating formed by heating. (2) The corrosion sensor according to item 1, wherein the corrosion sensor is for high temperature, (3) The protective film is formed by heating at 300 to 400 ° C., or The corrosion sensor according to item 2, (4) the exposed portion is formed by chemically dissolving an oxide film with an acid to remove the oxide film. (1) The corrosion sensor according to any one of (1) to (5), and (5) the exposed portion which is a corrosion evaluation surface is activated by an etching treatment,
The present invention provides a corrosion sensor according to any one of items 1, 3, and 4.
【０００５】[0005]
【発明の実施の形態】本発明の腐食センサーは、腐食の
評価面となる露出部と非評価面となる保護皮膜部を有
し、保護皮膜が酸化皮膜からなるものである。本発明の
腐食センサーには、必要に応じて、電気化学測定信号出
力用露出部を設けることができる。本発明の腐食センサ
ーの形状に特に制限はなく、例えば、棒状、板状などと
することができる。図１は、本発明の腐食センサーの一
態様の斜視図である。本態様の腐食センサーは、棒状の
鋼材からなり、その一端に評価面となる露出部１を有
し、他端に電気化学測定信号出力用露出部２を有し、中
央が酸化皮膜で覆われた保護皮膜部３となっている。本
発明の腐食センサーは、腐食の度合いを評価する対象と
なる設備と同一の鋼材から作製することが好ましく、こ
のような鋼材としては、例えば、軟鋼、半硬鋼、硬鋼、
鋳鋼、鋳鉄などを挙げることができる。本発明の腐食セ
ンサーの製造方法に特に制限はなく、例えば、次の工程
により製造することができる。すなわち、腐食の度合い
を評価する対象となる設備と同一の鋼材からなる試験片
の表面を、エメリー紙などの研磨紙を用いて研磨し、ト
ルエンなどの溶剤を用いて脱脂、乾燥を行う。使用する
研磨材の粒度は、＃３２０〜５００程度であることが好
ましい。表面の研磨と脱脂を行った試験片は、電気炉に
入れて、３００〜４００℃において、約２４時間加熱す
ることにより酸化皮膜を形成する。加熱温度は、４００
℃に近い方が、よりしっかりした酸化皮膜が形成される
ので好ましい。加熱により酸化皮膜の形成を終えた試験
片は、電気炉の電源を切って、そのまま電気炉の中で放
冷することが好ましい。BEST MODE FOR CARRYING OUT THE INVENTION The corrosion sensor of the present invention has an exposed portion which becomes a corrosion evaluation surface and a protective film portion which becomes a non-evaluation surface, and the protective film is an oxide film. The corrosion sensor of the present invention can be provided with an exposed portion for outputting an electrochemical measurement signal, if necessary. The shape of the corrosion sensor of the present invention is not particularly limited, and may be, for example, a rod shape or a plate shape. FIG. 1 is a perspective view of one embodiment of the corrosion sensor of the present invention. The corrosion sensor of this embodiment is made of a rod-shaped steel material, has an exposed portion 1 serving as an evaluation surface at one end, an exposed portion 2 for outputting an electrochemical measurement signal at the other end, and the center is covered with an oxide film. It is the protective film part 3. The corrosion sensor of the present invention is preferably made from the same steel material as the equipment to be evaluated for the degree of corrosion, such steel materials include, for example, mild steel, semi-hard steel, hard steel,
Examples include cast steel and cast iron. The method for producing the corrosion sensor of the present invention is not particularly limited, and can be produced, for example, by the following steps. That is, the surface of a test piece made of the same steel material as the equipment for which the degree of corrosion is evaluated is polished with abrasive paper such as emery paper, and degreased and dried with a solvent such as toluene. The grain size of the abrasive used is preferably about # 320-500. The test piece whose surface has been polished and degreased is placed in an electric furnace and heated at 300 to 400 ° C. for about 24 hours to form an oxide film. The heating temperature is 400
It is preferable that the temperature is close to 0 ° C. because a more stable oxide film is formed. It is preferable to turn off the power of the electric furnace and let the test piece as it is to cool in the electric furnace as it is after the formation of the oxide film by heating.
【０００６】表面全体に酸化皮膜を形成した試験片は、
次いで酸化皮膜の一部を除去し、腐食の評価面となる露
出部を形成する。酸化皮膜の除去方法に特に制限はな
く、例えば、酸などにより酸化皮膜を化学的に溶解して
除去することができ、あるいは、研磨などにより酸化皮
膜を機械的に除去することもできる。酸化皮膜の一部を
除去し、腐食の評価面となる露出部を形成した試験片
は、そのまま腐食センサーとして使用することができる
が、さらに評価面となる露出部を、硝酸、硫酸などを用
いてエッチング処理することにより、評価面が活性化さ
れて、腐食の評価が容易となる。本発明の腐食センサー
は、非評価面となる保護皮膜部が酸化皮膜で形成されて
いるので、塗料などの塗布や、プラスチックチューブな
どの被覆により保護皮膜部を形成した従来の腐食センサ
ーと異なり、高温で使用しても、保護皮膜に、はがれ、
割れ、膨れなどを生ずることがない。その結果、評価面
以外の部分にすき間腐食などの腐食が発生することがな
く、また、評価面となる露出部は均一な表面状態を保持
しているので、露出部のみについて評価を行い、腐食の
度合いを正しく評価することができる。A test piece having an oxide film formed on the entire surface is
Next, a part of the oxide film is removed to form an exposed portion which becomes a corrosion evaluation surface. The method for removing the oxide film is not particularly limited. For example, the oxide film can be chemically dissolved and removed with an acid or the like, or the oxide film can be mechanically removed by polishing or the like. A test piece with a part of the oxide film removed to form an exposed part that becomes the corrosion evaluation surface can be used as it is as a corrosion sensor. The etching process is activated to activate the evaluation surface, which facilitates the evaluation of corrosion. Corrosion sensor of the present invention, since the protective film portion to be the non-evaluation surface is formed of an oxide film, coating of paint or the like, unlike the conventional corrosion sensor formed a protective film portion by coating a plastic tube, Even when used at high temperatures, the protective film peels off,
No cracking or swelling. As a result, corrosion such as crevice corrosion does not occur in parts other than the evaluation surface, and since the exposed part that becomes the evaluation surface maintains a uniform surface condition, only the exposed part is evaluated and corrosion The degree of can be evaluated correctly.
【０００７】本発明の腐食センサーにすき間腐食が発生
することなく、腐食の度合いの正確な評価が可能になる
作用は、以下のように考えられる。すなわち、試験片の
表面に形成された酸化皮膜は、テフロンチューブなどの
被覆材に比べてかなり薄く、評価面の露出部との境目に
段差を生じないために、境目近傍に局部的な腐食を生じ
にくい。また、酸化皮膜は、試験片自身の化学変化によ
り形成された皮膜であるために、密着性が良好であり、
すき間腐食を生じない。さらに、高温の電気炉中で形成
された皮膜であるために、比較的高い温度環境において
も安定で、皮膜の変化やはがれが生じにくい。形成され
た酸化皮膜をＸ線回折分析すると、マグネタイト（Ｆｅ
3Ｏ4）とヘマタイト（α−Ｆｅ2Ｏ3）であることが分か
る。本発明の腐食センサーにおいては、マグネタイトが
緻密に試験片表面を覆うことにより、被覆された部分の
腐食が生じにくくなる。本発明の腐食センサーにおい
て、酸化皮膜は絶縁性を示すので、評価面となる露出部
と酸化皮膜で被覆された保護皮膜部の境目に、異種金属
接触腐食を生ずることもない。The action that enables the corrosion sensor of the present invention to accurately evaluate the degree of corrosion without causing crevice corrosion is considered as follows. That is, the oxide film formed on the surface of the test piece is much thinner than the covering material such as Teflon tube, and there is no step at the boundary with the exposed portion of the evaluation surface, so local corrosion is generated near the boundary. Unlikely to occur. Further, since the oxide film is a film formed by the chemical change of the test piece itself, the adhesion is good,
No crevice corrosion occurs. Further, since it is a film formed in a high temperature electric furnace, it is stable even in a relatively high temperature environment, and changes and peeling of the film are unlikely to occur. When the formed oxide film is analyzed by X-ray diffraction, magnetite (Fe
It can be seen that they are 3 O 4 ) and hematite (α-Fe 2 O 3 ). In the corrosion sensor of the present invention, the magnetite densely covers the surface of the test piece, so that corrosion of the covered portion is less likely to occur. In the corrosion sensor of the present invention, since the oxide film has an insulating property, different metal contact corrosion does not occur at the boundary between the exposed part which is the evaluation surface and the protective film part covered with the oxide film.
【０００８】本発明の腐食センサーは、必要に応じて、
評価面となる露出部と反対側の端の酸化皮膜の一部を除
去して、電気化学測定信号出力用露出部を設けることが
できる。酸化皮膜の除去方法に特に制限はなく、例え
ば、酸などにより酸化皮膜を化学的に溶解して除去する
ことができ、あるいは、研磨などにより酸化皮膜を機械
的に除去することもできる。本発明の腐食センサーの使
用方法に特に制限はなく、例えば、質量減法や分極抵抗
法などにおける腐食センサーとして用いることができ
る。質量減法においては、腐食センサーを配管又は機器
などの中に絶縁して固定し、一定の試験期間後に腐食セ
ンサーの腐食状態を観察するとともに、腐食減量を測定
して試験期間中における平均的な腐食速度を求めること
ができる。分極抵抗法においては、腐食センサーと照合
極と対極を用いる３電極方式又は腐食センサーと対極を
用いる２電極方式により、腐食センサーに微少電流を流
し、電位又は電流の変化より分極抵抗を求め、腐食電流
密度と等価の腐食速度を求めることができる。本発明の
腐食センサーは、水中における腐食評価に利用する以外
にも、形成された酸化皮膜が絶縁性を有するという特徴
を利用して、電気的な絶縁が必要な用途にも使用するこ
とができる。The corrosion sensor of the present invention, if necessary,
An exposed portion for electrochemical measurement signal output can be provided by removing a part of the oxide film at the end opposite to the exposed portion to be the evaluation surface. The method for removing the oxide film is not particularly limited. For example, the oxide film can be chemically dissolved and removed with an acid or the like, or the oxide film can be mechanically removed by polishing or the like. The method of using the corrosion sensor of the present invention is not particularly limited, and for example, it can be used as a corrosion sensor in the mass subtraction method or the polarization resistance method. In the mass reduction method, the corrosion sensor is insulated and fixed in piping or equipment, the corrosion state of the corrosion sensor is observed after a certain test period, and the corrosion weight loss is measured to determine the average corrosion during the test period. The speed can be calculated. In the polarization resistance method, a minute current is applied to the corrosion sensor by a three-electrode method that uses a corrosion sensor, a reference electrode, and a counter electrode, or a two-electrode method that uses a corrosion sensor and a counter electrode. The corrosion rate equivalent to the current density can be obtained. The corrosion sensor of the present invention can be used not only for evaluation of corrosion in water, but also for applications requiring electrical insulation by utilizing the characteristic that the formed oxide film has insulating properties. .
【０００９】[0009]
【実施例】以下に、実施例を挙げて本発明をさらに詳細
に説明するが、本発明はこれらの実施例によりなんら限
定されるものではない。
実施例１
直径６mmのＪＩＳ Ｇ ３１０１に規定されるＳＳ４００
棒鋼を、長さ８０mmに切断して丸棒状の試験片を作製し
た。この試験片の表面を、＃４００のエメリー紙で研磨
し、トルエンを用いて脱脂した。次いで、試験片を電気
炉中４００℃で２４時間加熱し、表面に酸化皮膜を形成
させた。試験片の評価面露出部となる一端１２mmを、塩
酸に浸漬して酸化皮膜を溶解して除去し、さらに２０重
量％硝酸と１０重量％硫酸を用いてエッチング処理を施
した。また、試験片の電気化学測定信号出力用露出部と
なる他端１４mmを、塩酸に浸漬して酸化皮膜を溶解除去
し、図１に示す形状を有する腐食センサーを完成した。
この腐食センサーを用い、pH１１.５、塩化物イオン
（Ｃｌ-）１００mg／リットル、硫酸イオン（ＳＯ4 2-）
２００mg／リットル、シリカ（ＳｉＯ2）２５０mg／リ
ットル、溶存酸素（ＤＯ）０.１mg／リットルの水質を
有する試験水を用い、試験水温度を９０℃として、２４
時間の腐食実験を行った。２４時間後の分極抵抗は、４
５ｋΩであった。また、外観観察の結果、評価面以外に
は腐食は認められなかった。
比較例１
酸化皮膜を形成する代わりに、非評価面をテフロンテー
プで被覆した以外は、実施例１と同様にして腐食センサ
ーを作製し、腐食実験を行った。２４時間後の分極抵抗
は、５ｋΩであった。また、テフロンテープの端部が浮
いて、非評価面の一部が腐食していた。
比較例２
酸化皮膜を形成する代わりに、非評価面に耐熱塗料を塗
布した以外は、実施例１と同様にして腐食センサーを作
製し、腐食実験を行った。２４時間後の分極抵抗は、４
ｋΩであった。また、耐熱塗料の一部が剥離して、非評
価面が腐食していた。
比較例３
酸化皮膜を形成する代わりに、非評価面を熱収縮チュー
ブで被覆した以外は、実施例１と同様にして腐食センサ
ーを作製し、腐食実験を行った。２４時間後の分極抵抗
は、１８ｋΩであった。また、熱収縮チューブに大きな
外観上の変化はなかったが、熱収縮チューブの端部の内
側の非評価面に、わずかに腐食が認められた。
比較例４
酸化皮膜を形成する代わりに、非評価面にマニキュアト
ップコートを塗布した以外は、実施例１と同様にして腐
食センサーを作製し、腐食実験を行った。２４時間後の
分極抵抗は、３ｋΩであった。また、マニキュアトップ
コートの相当部分が剥離して、非評価面が腐食してい
た。
比較例５
酸化皮膜を形成する代わりに、非評価面に油性インクを
塗布した以外は、実施例１と同様にして腐食センサーを
作製し、腐食実験を行った。２４時間後の分極抵抗は、
３ｋΩであった。また、油性インクの相当部分が剥離し
て、非評価面が腐食していた。
比較例６
酸化皮膜を形成する代わりに、非評価面にシリコーン系
樹脂を塗布した以外は、実施例１と同様にして腐食セン
サーを作製し、腐食実験を行った。２４時間後の分極抵
抗は、５ｋΩであった。また、シリコーン系樹脂の一部
が剥離して、非評価面が腐食していた。実施例１及び比
較例１〜６の結果を、第１表に示す。The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Example 1 SS400 specified in JIS G 3101 having a diameter of 6 mm
A steel bar was cut into a length of 80 mm to prepare a round bar-shaped test piece. The surface of this test piece was polished with # 400 emery paper and degreased with toluene. Then, the test piece was heated in an electric furnace at 400 ° C. for 24 hours to form an oxide film on the surface. One end 12 mm, which is the exposed portion of the evaluation surface of the test piece, was immersed in hydrochloric acid to dissolve and remove the oxide film, and etching treatment was further performed using 20 wt% nitric acid and 10 wt% sulfuric acid. Further, the other end 14 mm which is an exposed portion for outputting an electrochemical measurement signal of the test piece was immersed in hydrochloric acid to dissolve and remove the oxide film, thereby completing a corrosion sensor having a shape shown in FIG.
Using this corrosion sensor, pH 11.5, chloride ion (Cl -) 100mg / l, sulfate ion (SO 4 2-)
Test water having a water quality of 200 mg / liter, silica (SiO 2 ) 250 mg / liter, and dissolved oxygen (DO) 0.1 mg / liter was used, and the test water temperature was 90 ° C.
A time corrosion experiment was conducted. The polarization resistance after 24 hours is 4
It was 5 kΩ. In addition, as a result of external appearance observation, no corrosion was observed except on the evaluation surface. Comparative Example 1 A corrosion sensor was produced in the same manner as in Example 1 except that the non-evaluation surface was covered with Teflon tape instead of forming an oxide film, and a corrosion experiment was conducted. The polarization resistance after 24 hours was 5 kΩ. In addition, the end of the Teflon tape floated and part of the non-evaluation surface was corroded. Comparative Example 2 A corrosion sensor was prepared in the same manner as in Example 1 except that a heat resistant coating was applied to the non-evaluation surface instead of forming an oxide film, and a corrosion experiment was conducted. The polarization resistance after 24 hours is 4
It was kΩ. Further, a part of the heat resistant paint was peeled off and the non-evaluated surface was corroded. Comparative Example 3 A corrosion sensor was produced in the same manner as in Example 1 except that the non-evaluated surface was covered with a heat-shrinkable tube instead of forming an oxide film, and a corrosion experiment was conducted. The polarization resistance after 24 hours was 18 kΩ. Although the heat-shrinkable tube did not change significantly in appearance, slight corrosion was observed on the non-evaluated surface inside the end of the heat-shrinkable tube. Comparative Example 4 A corrosion sensor was prepared in the same manner as in Example 1 except that the nail polish top coat was applied to the non-evaluated surface instead of forming the oxide film, and the corrosion experiment was conducted. The polarization resistance after 24 hours was 3 kΩ. Also, a considerable portion of the nail polish top coat was peeled off, and the non-evaluated surface was corroded. Comparative Example 5 A corrosion sensor was prepared and a corrosion experiment was conducted in the same manner as in Example 1 except that the non-evaluation surface was coated with the oil-based ink instead of forming the oxide film. The polarization resistance after 24 hours is
It was 3 kΩ. Further, a considerable portion of the oil-based ink was peeled off, and the non-evaluated surface was corroded. Comparative Example 6 A corrosion sensor was produced in the same manner as in Example 1 except that a silicone resin was applied to the non-evaluation surface instead of forming an oxide film, and a corrosion experiment was conducted. The polarization resistance after 24 hours was 5 kΩ. In addition, a part of the silicone resin was peeled off and the non-evaluated surface was corroded. The results of Example 1 and Comparative Examples 1 to 6 are shown in Table 1.
【００１０】[0010]
【表１】 [Table 1]
【００１１】第１表に見られるように、本発明の腐食セ
ンサーは、高温における腐食実験においても、酸化皮膜
のはがれや、すき間腐食の発生がなく、評価面以外の部
分には腐食が生じていない。また、分極抵抗も高い値を
保っている。この結果から、本発明の腐食センサーを用
いることにより、高温においても、正しく腐食の度合い
を評価することが可能となることが分かる。これに対し
て、比較例１〜６の従来の腐食センサーは、いずれも評
価面以外の部分にも腐食が発生し、分極抵抗も低いこと
から、高温における使用には適していないことが分か
る。
実施例２、比較例７
実施例１で作製した腐食センサー及び比較例１で作製し
た腐食センサーを用いて、腐食センサーとしての実用性
について試験を行った。上記２種の腐食センサーと、テ
ストピース（材質：ＳＳ４００、寸法：５０×１５×
１.６mm）を、pH１１.５、塩化物イオン（Ｃｌ-）１０
０mg／リットル、硫酸イオン（ＳＯ4 2-）２００mg／リ
ットル、シリカ（ＳｉＯ2）２５０mg／リットルであ
り、溶存酸素（ＤＯ）が０.１〜８.３mg／リットルであ
る１０種類の試験水に浸漬し、試験水温度を９０℃とし
て、２４時間の腐食実験を行った。テストピースの腐食
速度ｍｄｄ（mg／dm2／day）と、腐食センサーの分極抵
抗Ｒp（ｋΩ）とを測定し、得られた結果を両対数グラ
フにプロットした。図２は、分極抵抗と腐食速度の関係
を示すグラフである。図２より、実施例１で作製した本
発明の腐食センサーについては、腐食速度の対数と分極
抵抗の対数が負の直線関係にあり、
ｍｄｄ＝Ｋ／Ｒp
の関係が満足されていることが分かる。ただし、Ｋは定
数である。これに対して、比較例１で作製した腐食セン
サーについては、この関係が満足されていない。この結
果から、実施例１で作製した本発明の腐食センサーは、
高温においても腐食センサーとして実用することができ
るが、比較例１で作製した腐食センサーは、高温におい
ては腐食センサーとして使用できないことが分かる。As can be seen from Table 1, the corrosion sensor of the present invention has no peeling of the oxide film or crevice corrosion even in the corrosion experiment at high temperature, and corrosion does not occur on the portion other than the evaluation surface. Absent. In addition, the polarization resistance maintains a high value. From these results, it is understood that the corrosion sensor of the present invention can be used to correctly evaluate the degree of corrosion even at high temperatures. On the other hand, the conventional corrosion sensors of Comparative Examples 1 to 6 are not suitable for use at high temperatures because corrosion occurs in the portions other than the evaluation surface and the polarization resistance is low. Example 2 and Comparative Example 7 The corrosion sensor manufactured in Example 1 and the corrosion sensor manufactured in Comparative Example 1 were used to test the practicality as a corrosion sensor. The above two types of corrosion sensors and a test piece (material: SS400, dimensions: 50 x 15 x
The 1.6 mm), pH 11.5, chloride ion (Cl -) 10
0 mg / liter, sulfate ion (SO 4 2− ) 200 mg / liter, silica (SiO 2 ) 250 mg / liter, dissolved oxygen (DO) in 0.1 to 8.3 mg / liter After immersion, the test water temperature was set to 90 ° C. and a 24-hour corrosion experiment was performed. The corrosion rate mdd (mg / dm 2 / day) of the test piece and the polarization resistance Rp (kΩ) of the corrosion sensor were measured, and the obtained results were plotted on a log-log graph. FIG. 2 is a graph showing the relationship between polarization resistance and corrosion rate. It can be seen from FIG. 2 that the corrosion sensor of the present invention manufactured in Example 1 has a negative linear relationship between the logarithm of the corrosion rate and the logarithm of the polarization resistance, and the relationship of mdd = K / Rp is satisfied. . However, K is a constant. On the other hand, the relationship is not satisfied for the corrosion sensor manufactured in Comparative Example 1. From this result, the corrosion sensor of the present invention manufactured in Example 1
Although it can be used as a corrosion sensor even at high temperatures, it can be seen that the corrosion sensor produced in Comparative Example 1 cannot be used as a corrosion sensor at high temperatures.
【００１２】[0012]
【発明の効果】本発明の腐食センサーによれば、高温水
中でもすき間腐食などが発生せず、評価面の面積を正確
に制御して、腐食の度合いを正しく評価することができ
る。また、本発明の腐食センサーは、センサー材料の加
熱により酸化皮膜を形成するので、一度に多数のセンサ
ーを作製することが可能である。本発明の腐食センサー
を用することにより、電気化学測定など、表面状態によ
って大きく結果の値が変動する評価方法においても、再
現性が良好で、精度の高い測定を行うことができる。According to the corrosion sensor of the present invention, crevice corrosion does not occur even in high temperature water, the area of the evaluation surface can be accurately controlled, and the degree of corrosion can be evaluated correctly. In addition, since the corrosion sensor of the present invention forms an oxide film by heating the sensor material, it is possible to manufacture many sensors at once. By using the corrosion sensor of the present invention, it is possible to perform highly accurate measurement with high reproducibility even in an evaluation method such as an electrochemical measurement in which the value of the result largely varies depending on the surface condition.
【図１】図１は、本発明の腐食センサーの一態様の斜視
図である。FIG. 1 is a perspective view of one embodiment of a corrosion sensor of the present invention.
【図２】図２は、分極抵抗と腐食速度の関係を示すグラ
フである。FIG. 2 is a graph showing the relationship between polarization resistance and corrosion rate.
１ 評価面となる露出部 ２ 電気化学測定信号出力用露出部 ３ 酸化皮膜で覆われた保護皮膜部 1 Exposed part to be the evaluation surface 2 Exposed part for electrochemical measurement signal output 3 Protective film part covered with oxide film
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平５−322831（ＪＰ，Ａ) 特開 平３−242546（ＪＰ，Ａ) 特開 平５−126776（ＪＰ，Ａ) 特開 平６−186196（ＪＰ，Ａ) 実開 平１−144856（ＪＰ，Ｕ) 米国特許5977782（ＵＳ，Ａ) 米国特許5310470（ＵＳ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) G01N 27/26 351 G01N 17/04 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-322831 (JP, A) JP-A-3-242546 (JP, A) JP-A-5-126776 (JP, A) JP-A-6- 186196 (JP, A) Actual Kaihei 1-144856 (JP, U) US Patent 5977782 (US, A) US Patent 5310470 (US, A) (58) Fields investigated (Int.Cl. 7 , DB name) G01N 27/26 351 G01N 17/04
Claims (5)
る保護皮膜部を有する腐食センサーであって、保護皮膜
が加熱によって形成された酸化皮膜であることを特徴と
する腐食センサー。1. A corrosion sensor having an exposed portion serving as a corrosion evaluation surface and a protective film portion serving as a non-evaluation surface, wherein the protective film is an oxide film formed by heating .
載の腐食センサー。 2. The corrosion sensor according to claim 1, which is for high temperature.
Corrosion sensor on board.
て形成されたことを特徴とする請求項１又は２に記載の
腐食センサー。 3. The protective film is heated to 300 to 400 ° C.
It is formed by the following.
Corrosion sensor.
溶解して除去することにより形成されてなることを特徴
とする請求項１〜３のいずれかに記載の腐食センサー。 4. The exposed portion is formed by chemically oxidizing the oxide film with an acid.
Characterized by being formed by melting and removing
The corrosion sensor according to any one of claims 1 to 3.
処理により活性化されてなることを特徴とする請求項１
〜４のいずれかに記載の腐食センサー。 5. The exposed portion, which is a corrosion evaluation surface, is etched.
2. The method according to claim 1, which is activated by processing.
The corrosion sensor according to any one of to 4.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11707898A JP3381621B2 (en) | 1998-04-27 | 1998-04-27 | Corrosion sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11707898A JP3381621B2 (en) | 1998-04-27 | 1998-04-27 | Corrosion sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11304747A JPH11304747A (en) | 1999-11-05 |
| JP3381621B2 true JP3381621B2 (en) | 2003-03-04 |
Family
ID=14702861
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11707898A Expired - Lifetime JP3381621B2 (en) | 1998-04-27 | 1998-04-27 | Corrosion sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3381621B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4765906B2 (en) * | 2006-11-17 | 2011-09-07 | 栗田工業株式会社 | Corrosion monitoring device |
| JP4821574B2 (en) * | 2006-11-20 | 2011-11-24 | 栗田工業株式会社 | Boiler condensate corrosion monitor |
| JP5466113B2 (en) * | 2010-08-26 | 2014-04-09 | 日本電信電話株式会社 | Potential measuring jig and potential measuring method |
| US20130280044A1 (en) * | 2012-04-20 | 2013-10-24 | General Electric Company | Corrosion monitoring device |
| JP6621611B2 (en) * | 2015-03-27 | 2019-12-18 | 太平洋セメント株式会社 | Corrosion detection method |
-
1998
- 1998-04-27 JP JP11707898A patent/JP3381621B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH11304747A (en) | 1999-11-05 |
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