JPH036978B2 - - Google Patents
Info
- Publication number
- JPH036978B2 JPH036978B2 JP30300388A JP30300388A JPH036978B2 JP H036978 B2 JPH036978 B2 JP H036978B2 JP 30300388 A JP30300388 A JP 30300388A JP 30300388 A JP30300388 A JP 30300388A JP H036978 B2 JPH036978 B2 JP H036978B2
- Authority
- JP
- Japan
- Prior art keywords
- alloy
- amount
- effect
- corrosion
- weight
- 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
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- 229910000838 Al alloy Inorganic materials 0.000 claims description 8
- 239000012535 impurity Substances 0.000 claims description 2
- 238000005260 corrosion Methods 0.000 description 15
- 230000000694 effects Effects 0.000 description 14
- 230000005611 electricity Effects 0.000 description 13
- 230000007797 corrosion Effects 0.000 description 11
- 239000000463 material Substances 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 229910000676 Si alloy Inorganic materials 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 229910000846 In alloy Inorganic materials 0.000 description 3
- 238000004210 cathodic protection Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 229910052738 indium Inorganic materials 0.000 description 3
- 239000013535 sea water Substances 0.000 description 3
- 229910052725 zinc Inorganic materials 0.000 description 3
- 230000003213 activating effect Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910007610 Zn—Sn Inorganic materials 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
Description
〔産業上の利用分野〕
本発明は、鉄系材料の陰極防食に使用される流
電陽極用アルミニウム合金に関する。
〔従来の技術〕
流電陽極用材料としては、陽極電位が出来るだ
け卑であり、発生電気量が大きく、且つ耐用年数
を満足させるために溶け残りを生じることなく、
陽極表面からむらなく一様に溶解することが要求
される。
上記の要件を満足する材料として、Alは、単
位重量当たりの発生電気量がZn、Mg等に比して
大きく、陽極電位も本来は極めて卑であつて、大
きな防食電流を取り出すことが出来るが、Alは
そのまゝの状態では酸化被覆に覆われているた
め、海水中での陽極電位は−0.7〜−0.9Vvs.、S.
C.E.（飽和甘汞電極基準、以下陽極電位は同じ）
しか示さず、海水中でそのまゝ使用した場合、鉄
鋼を防食することは困難である。
このため、流電陽極としては、陽極電位を−
1.0V程度とする目的で、AlにZn、Sn、In、Zn−
Sn、Zn−Sn、In−Sn等さまざまの元素を各種の
配合比率で添加したものが提案又は実用化されて
いる。
その中で例えば、Al−Zn−In−Si系合金は陽
極電位が−1.0Vvs.、S.C.E.より卑電位を示し、
電気量も2.65A・hr／ｇを安定して維持できるも
のの、腐食、溶解が均一に進行せず、溶解表面の
平滑性も乏しいため、孔食や溝腐食（腐食が溝状
で両側が残る）等による自己腐食や実使用環境中
における合金の部分的脱落を引き起こし実用上の
寿命が短くなるという欠点があつた。
〔発明が解決しようとする課題〕
本発明の課題は、上記の問題点を解決し、鉄系
材料を陰極防食にするに充分なる陽極電位と電気
量を示し、且つ溶解表面の均一性の平滑性を備え
た流電陽極用Al合金を提供することを課題とす
る。
〔課題を解決するための手段〕
この課題を解決するために、本発明者等は種々
研究を行つた結果、Al−Zn−In−Si合金にTi、
Ｂ及びMgの３種類の元素を添加することによ
り、鉄系材料を陰極防食するのに充分なる電位と
電気量を維持し、且つ溶解表面の均一性と平滑性
が著しく改善されることを見いだし本発明に到達
した。
即ち、本発明は、Zn0.5〜6.0重量％、In0.01〜
0.05重量％、Si0.05〜0.3重量％、Ti0.005〜0.1重
量％、B0.001〜0.02重量％、Mg0.1〜3.0重量％を
含み、残部が実用的にAl及び不可避不純物から
なる流電陽極用アルミニウム合金を課題解決の手
段とする。
〔作用〕
本発明における各成分の作用を以下に説明す
る。
(1) Zn0.5〜6.0％（重量％以下同じ）
Alを主体とする合金において、Alを活性に
する効果については、ZnはInに比較すると小
さいが、InをAl中に均一に分散させる作用を
有し、均一な溶解表面を形成するのに有効に働
く。
更にZnの添加はAl合金の水素過電圧を増大
させる効果があり、均一な溶解表面を形成する
効果と共に局部アノード、局部カソードの形成
による自己腐食を抑制し、発生有効電気量を増
大させる効果がある。しかしZnの含有量が0.5
％未満ではInを合金中に均一に分散させる作用
が不充分であり、6.0％を超えると、逆に電気
量が減少するのでZnは0.5〜6.0％とした。
(2) In0.01〜0.05％
InはAl合金を活性化し、陽極電位を大きく
卑にする作用を有するが、Znが0.5〜6.0％の範
囲において、Inが0.01％未満ではその作用が弱
く陽極電位が充分卑にならない。又、0.05％を
超えて含有すると、陽極電位は卑になるが、In
自体不均一に分散し、そのために局部腐食を生
じて電気量が低下する。よつてInの添加量は
0.01〜0.05％とした。
(3) Si0.05〜0.3％
SiはZn0.5〜6.0％、In0.01〜0.05％を含有し
たAl合金において、0.05〜0.3％含有させると、
その電気量が増大する。Siが0.05％より少ない
と、その効果はなく、又0.3％を超えると再び
その効果がなくなると共に陽極電位が上昇し防
食機能が低下する。よつてSiの添加量は0.05〜
0.3％とした。
(4) Ti0.005〜0.1％、B0.001〜0.02％
上記のAl−Zn−In−Si合金にTi0.005〜0.1％
及びB0.001〜0.02％を添加すると、結晶組織が
粗大な柱状晶から微細な粒状晶へと変化し、そ
れに伴なつて合金の溶出が均一となり、孔食、
溝腐食並びに腐食生成物の付着を防止する。そ
の結果、溶解表面の均一性と平滑性が向上す
る。
Tiは0.005％未満、Ｂは0.001％未満ではその
効果は充分ではなく、Tiは0.1％を超え、Ｂは
0.02％を超えると、有効発生電気量の低下を招
く。従つてTi及びＢの添加量はTi0.005〜0.1
％、B0.001〜0.02％とした。
(5) Mg0.1〜3.0％
MgはAl−Zn−In系合金において、Siとの相
乗効果により、その電気量を更に増大させる効
果がある。即ちAl−Zn−In合金にSiを加えた
Al−Zn−In−Si合金は、電気量2.65A・hr／ｇ
以上を有するが、更にMgを0.1〜3.0％添加し
たAl−Zn−In−Si合金は、2.70A・hr／ｇ以上
を有する。しかし、その添加量が0.1％未満で
はその効果はなく、3.0％を超えると陽極電位
の上昇を招く。
〔実施例〕
実施試験は日本学術振興会第97委員会の電気防
食第12分科会の「流電陽極試験」に基ずいて以下
に説明する方法で行つた。
容量１のガラス製ビーカーに、第１表に示し
た組成の入工海水1000mlを入れた電解槽に、第２
表に示すそれぞれの組成の直径20mmの棒状試料の
一部を露出面積20cm2になるようにビニールテープ
でシールしたものを陽極として槽内の中央部に吊
し、陰極は槽の内壁に沿つたステンレス鋼の円筒
を用いた。
試料を直流電源の＋極に、又陰極板（円筒）を
その一極に結線し、可変抵抗及び電量計を回路内
に直列につないで通電し、陽極電流密度１ｍＡ／
cm2、液温25℃として240時間電解試験を行い、毎
日１回照合電極と電圧計を用いて陽極の電位を測
定し、同時に電気量を測定した。
電解試験時間を経過後、液中より試料を取り出
し、ブラシで水洗後60％濃硝酸溶液に、３〜５分
間浸漬して水洗し、乾燥して試料の表面状態を調
査した。
得られた結果を第２表に示す。
[Industrial Application Field] The present invention relates to an aluminum alloy for galvanic anodes used for cathodic protection of ferrous materials. [Prior Art] As a material for galvanic anodes, the anode potential is as base as possible, the amount of electricity generated is large, and in order to satisfy the service life, it is necessary to use materials that do not leave melted residue.
It is required to dissolve evenly and uniformly from the anode surface. As a material that satisfies the above requirements, Al generates a larger amount of electricity per unit weight than Zn, Mg, etc., and its anode potential is originally extremely base, so it can extract a large anti-corrosion current. , Al is covered with an oxide coating in its original state, so the anode potential in seawater is −0.7 to −0.9V vs., S.
CE (Saturated Amane electrode standard, hereinafter the anode potential is the same)
However, it is difficult to protect steel from corrosion if it is used directly in seawater. Therefore, as a galvanic anode, the anode potential is -
Zn, Sn, In, and Zn− are added to Al for the purpose of approximately 1.0V.
Products in which various elements such as Sn, Zn-Sn, and In-Sn are added in various blending ratios have been proposed or put into practical use. Among them, for example, Al-Zn-In-Si alloy has an anode potential of -1.0V vs., which is less noble than SCE.
Although the amount of electricity can be stably maintained at 2.65A・hr/g, corrosion and dissolution do not proceed uniformly, and the melting surface is not smooth, resulting in pitting corrosion and groove corrosion (corrosion remains in the form of grooves on both sides). ), etc., and the alloy partially falls off in the actual usage environment, resulting in a shortened practical life. [Problems to be Solved by the Invention] An object of the present invention is to solve the above-mentioned problems, to provide sufficient anode potential and electricity to provide cathodic protection to iron-based materials, and to provide a uniform and smooth melted surface. The purpose of the present invention is to provide an Al alloy for galvanic anodes with high properties. [Means for Solving the Problem] In order to solve this problem, the present inventors conducted various studies and found that Ti, Ti,
It was discovered that by adding three types of elements, B and Mg, it was possible to maintain sufficient potential and quantity of electricity to cathodicly protect iron-based materials, and to significantly improve the uniformity and smoothness of the melted surface. We have arrived at the present invention. That is, the present invention has Zn of 0.5 to 6.0% by weight and In of 0.01 to 6.0% by weight.
0.05% by weight, 0.05-0.3% by weight of Si, 0.005-0.1% by weight of Ti, 0.001-0.02% by weight of B, 0.1-3.0% by weight of Mg, and the balance practically consists of Al and inevitable impurities. Aluminum alloy for electrode anode is used as a means to solve the problem. [Action] The action of each component in the present invention will be explained below. (1) Zn0.5 to 6.0% (same as below weight%) In alloys mainly composed of Al, Zn has a smaller effect on activating Al than In, but it disperses In uniformly in Al. It works effectively to form a uniform melting surface. Furthermore, the addition of Zn has the effect of increasing the hydrogen overvoltage of the Al alloy, has the effect of forming a uniform melting surface, suppresses self-corrosion due to the formation of local anodes and local cathodes, and has the effect of increasing the amount of effective electricity generated. . However, the Zn content is 0.5
If it is less than 6.0%, the effect of uniformly dispersing In in the alloy is insufficient, and if it exceeds 6.0%, the amount of electricity will decrease, so the Zn content was set to 0.5 to 6.0%. (2) In0.01~0.05% In has the effect of activating the Al alloy and making the anode potential much less noble, but when Zn is in the range of 0.5~6.0%, if In is less than 0.01%, the effect is weak and the anode potential is weak. The potential is not low enough. In addition, if the content exceeds 0.05%, the anode potential becomes less noble, but In
It is itself dispersed non-uniformly, which causes local corrosion and reduces the amount of electricity. Therefore, the amount of In added is
It was set at 0.01-0.05%. (3) Si0.05-0.3% When Si is included in an Al alloy containing Zn0.5-6.0% and In 0.01-0.05%, Si is added at 0.05-0.3%.
The amount of electricity increases. If Si is less than 0.05%, there is no effect, and if it exceeds 0.3%, the effect is lost again and the anode potential increases, resulting in a decrease in anticorrosion function. Therefore, the amount of Si added is 0.05 ~
It was set at 0.3%. (4) Ti0.005~0.1%, B0.001~0.02% Ti0.005~0.1% in the above Al-Zn-In-Si alloy
When 0.001 to 0.02% of B is added, the crystal structure changes from coarse columnar crystals to fine granular crystals, and as a result, the elution of the alloy becomes uniform, causing pitting corrosion,
Prevents groove corrosion and adhesion of corrosion products. As a result, the uniformity and smoothness of the melted surface is improved. The effect is not sufficient if Ti is less than 0.005% and B is less than 0.001%, but if Ti is more than 0.1% and B is less than 0.001%, the effect is insufficient.
If it exceeds 0.02%, the effective amount of electricity generated will decrease. Therefore, the amount of Ti and B added is Ti0.005 to 0.1
%, B0.001-0.02%. (5) Mg0.1-3.0% Mg has the effect of further increasing the amount of electricity in the Al-Zn-In alloy due to its synergistic effect with Si. In other words, Si was added to the Al-Zn-In alloy.
Al-Zn-In-Si alloy has an electrical capacity of 2.65A・hr/g
An Al-Zn-In-Si alloy having the above properties but further adding 0.1 to 3.0% Mg has a resistance of 2.70 A·hr/g or more. However, if the amount added is less than 0.1%, there is no effect, and if it exceeds 3.0%, the anode potential will increase. [Example] Practical tests were conducted in accordance with the method described below based on the "galvanic anodic test" of the 12th Subcommittee on Cathodic Protection of the 97th Committee of the Japan Society for the Promotion of Science. A glass beaker with a capacity of 1 is filled with 1000 ml of raw seawater having the composition shown in Table 1.
A portion of a rod-shaped sample with a diameter of 20 mm of each composition shown in the table was sealed with vinyl tape so that the exposed area was 20 cm 2 and was hung in the center of the tank as an anode, and a cathode was placed along the inner wall of the tank. A stainless steel cylinder was used. Connect the sample to the + pole of a DC power supply and the cathode plate (cylindrical) to one pole, connect a variable resistor and a coulometer in series in the circuit, and apply current to the anode current density of 1 mA/
An electrolytic test was conducted for 240 hours at a temperature of 25° C. cm 2 and a liquid temperature of 25° C., and the potential of the anode was measured once a day using a reference electrode and a voltmeter, and at the same time, the amount of electricity was measured. After the electrolysis test time had elapsed, the sample was taken out from the solution, washed with water using a brush, immersed in a 60% concentrated nitric acid solution for 3 to 5 minutes, washed with water, dried, and the surface condition of the sample was investigated. The results obtained are shown in Table 2.
【表】【table】
【表】【table】
本発明流電陽極用アルミニウム合金は、高い発
生電気量を有し、陽極電位も充分に卑であり、更
に従来の材料に比し溶解表面の均一性と平滑性が
著しく改善され、孔食や溝腐食等による自己腐食
や実使用環境中における合金の部分的脱落を防止
して長期間に亘つて安定した防食機能を有する。
The aluminum alloy for galvanic anodes of the present invention has a high amount of electricity generated, has a sufficiently base anode potential, and has significantly improved uniformity and smoothness of the melting surface compared to conventional materials, preventing pitting corrosion. It has a stable anti-corrosion function over a long period of time by preventing self-corrosion due to groove corrosion and partial shedding of the alloy in the actual usage environment.
Claims (1)
Si0.05〜0.3重量％、Ti0.005〜0.1重量％、B0.001
〜0.02重量％、Mg0.1〜3.0重量％を含み、残部が
実質的にAl及び不可避不純物からなることを特
徴とする流電陽極用アルミニウム合金。1 Zn0.5-6.0% by weight, In0.01-0.05% by weight,
Si0.05~0.3wt%, Ti0.005~0.1wt%, B0.001
An aluminum alloy for a galvanic anode, characterized in that it contains ~0.02% by weight, 0.1-3.0% by weight of Mg, and the remainder essentially consists of Al and unavoidable impurities.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30300388A JPH02149636A (en) | 1988-11-30 | 1988-11-30 | Aluminum alloy for galvanic anode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30300388A JPH02149636A (en) | 1988-11-30 | 1988-11-30 | Aluminum alloy for galvanic anode |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02149636A JPH02149636A (en) | 1990-06-08 |
| JPH036978B2 true JPH036978B2 (en) | 1991-01-31 |
Family
ID=17915767
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30300388A Granted JPH02149636A (en) | 1988-11-30 | 1988-11-30 | Aluminum alloy for galvanic anode |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02149636A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0466683A (en) * | 1990-07-04 | 1992-03-03 | Nippon Light Metal Co Ltd | Sacrificial anode made of aluminum alloy for corrosion protection for steel structure |
| CN111058044A (en) * | 2019-12-20 | 2020-04-24 | 山东南山铝业股份有限公司 | Cast aluminum alloy sacrificial anode with long service life |
-
1988
- 1988-11-30 JP JP30300388A patent/JPH02149636A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02149636A (en) | 1990-06-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |