JPH1161307A - Aluminum alloy for galvanic anode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a galvanic anode suitable for preventing the corrosion of iron reinforcing bars in reinforced concrete by using an Al alloy contg. specified amts. of Zn and Ca and the balance Al with inevitable impurities. SOLUTION: The Al alloy contains 7-50 wt.% Zn and 0.01-0.60 wt.% Ca. Both Zn and Ca inhibit self-dissolution and act to increase the quantity of electricity generated. In the case of <7 wt.% Zn and <0.01 wt.% Ca, the action is not satisfactorily exhibited. In the case of >50 wt.% Zn and >0.60 wt.% Ca, anode potential is liable to become noble. When the Al alloy is used as a galvanic anode, such a sufficiently base anode potential as <=-1,333 mV and such a sufficiently large quantity of electricity generated as >=1,255 A.hr/kg are ensured and the corrosion of iron reinforcing bars in reinforced concrete is prevented.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、流電陽極用アルミ
ニウム合金に関し、特に鉄筋コンクリート構造物中の鉄
筋の防食に最適な流電陽極用アルミニウム合金に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy for a galvanic anode, and more particularly to an aluminum alloy for a galvanic anode which is optimal for preventing corrosion of reinforcing steel in a reinforced concrete structure.

【０００２】[0002]

【従来の技術】コンクリートが強アルカリであるため
に、通常の環境の鉄筋コンクリート構造物中の鉄筋の腐
食はあまり進行しない。しかし、例えば海水上や海水中
のような環境や、あるいは凍結防止用に塩化物が散布さ
れる環境のような、塩水が浸透する環境に鉄筋コンクリ
ート構造物を設けると、鉄筋コンクリート構造物中の鉄
筋の腐食が進行するという問題がある。2. Description of the Related Art Corrosion of reinforcing steel in a reinforced concrete structure in a normal environment does not progress so much because concrete is strongly alkaline. However, if the reinforced concrete structure is installed in an environment where salt water penetrates, for example, in an environment such as seawater or seawater, or an environment in which chlorides are sprayed to prevent freezing, the reinforcement of the reinforced concrete structure may be reduced. There is a problem that corrosion progresses.

【０００３】この問題に対して、長期間低廉で安定した
防食ができる流電陽極法が注目されており、流電陽極に
亜鉛合金の使用が検討されているが、流電陽極の重要な
特性の一つである陽極電位が高（貴）すぎるという問題
がある。[0003] To solve this problem, a galvanic anode method that can provide stable corrosion protection at low cost for a long time has attracted attention, and the use of a zinc alloy for the galvanic anode has been studied. One of the problems is that the anode potential is too high (noble).

【０００４】[0004]

【発明が解決しようとする課題】本発明の目的は、上記
問題点を解消し、鉄筋コンクリート構造物中の鉄筋の防
食用に好適な組成の流電陽極、すなわち陽極電位が十分
に卑で、かつ発生電気量が十分に大きいアルミニウム合
金からなる流電陽極を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a galvanic anode having a composition suitable for preventing corrosion of reinforcing steel in a reinforced concrete structure, that is, a sufficiently low anode potential, and An object of the present invention is to provide a galvanic anode made of an aluminum alloy that generates a sufficiently large amount of electricity.

【０００５】[0005]

【課題を解決するための手段】７〜５０重量％のＺｎ
と、０．０１〜０．６０重量％のＣａとを含み、残部が
Ａｌおよび不可避不純物からなるアルミニウム合金を流
電陽極とする。Means for Solving the Problems 7 to 50% by weight of Zn
And an aluminum alloy containing 0.01 to 0.60% by weight of Ca and the balance being Al and unavoidable impurities is used as a galvanic anode.

【０００６】[0006]

【発明の実施の形態】７〜５０重量％のＺｎと、０．０
１〜０．６０重量％のＣａとを含み、残部がＡｌおよび
不可避不純物からなるアルミニウム合金を流電陽極とし
て用いる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 7 to 50% by weight of Zn and 0.0
An aluminum alloy containing 1 to 0.60% by weight of Ca and the balance being Al and unavoidable impurities is used as a galvanic anode.

【０００７】該アルミニウム合金におけるＺｎおよびＣ
ａには、いずれも自己溶解を抑制することにより発生電
気量を大きくする作用があるが、Ｚｎが７重量％未満で
あるか、またはＣａが０．０１重量％未満であると、該
作用は十分発揮されない。また、Ｚｎが５０重量％を超
えるか、またはＣａが０．６０重量％を超えると、陽極
電位が貴となりやすい。[0007] Zn and C in the aluminum alloy
a has the effect of increasing the amount of generated electricity by suppressing self-dissolution, but when Zn is less than 7% by weight or Ca is less than 0.01% by weight, the effect is reduced. Not enough. If Zn exceeds 50% by weight or Ca exceeds 0.60% by weight, the anodic potential tends to be noble.

【０００８】[0008]

【実施例】【Example】

（実施例１〜１１）実施例１〜１１として、組成を調整
したアルミニウム合金を大気溶解後、金型鋳造して、直
径２５ｍｍ、長さ２５０ｍｍの丸棒形状の鋳塊を得た。
その後、これらの鋳塊を試料として、流電陽極の性能試
験を行った。性能試験は、（社）腐食防食協会が制定し
た「流電陽極試験法」（「流電陽極試験法および同解
説」、防食技術、第３１巻、６１２〜６２０頁、１９８
２年）に準拠して実施した。(Examples 1 to 11) As Examples 1 to 11, an aluminum alloy whose composition was adjusted was melted in the air and then cast in a mold to obtain a round bar-shaped ingot having a diameter of 25 mm and a length of 250 mm.
Thereafter, a performance test of a galvanic anode was performed using these ingots as samples. The performance test was conducted using the “electrostatic anode test method” established by the Corrosion and Corrosion Prevention Association of Japan (“electrostatic anode test method and its description”, anticorrosion technology, Vol. 31, pp. 612-620, 198).
2 years).

【０００９】上記流電陽極試験法を略述すると次の通り
である。The following is a brief description of the galvanostatic anode test method.

【００１０】すなわち、試料の表面をサンドペーパーの
２４０番の粗さになるまで研磨し、側面を２０ｃｍ² 残
して、他の面はビニールテープを用いて絶縁被覆した。
次に、ＫＣｌが３２．０ｇ／ｌ、ＮａＯＨが２４．５ｇ
／ｌ、ＫＯＨが１０．０ｇ／ｌ、Ｃａ（ＯＨ）₂ が０．
１ｇ／ｌである組成の水溶液をコンクリート模擬液試験
液として、１リットルのビーカー内に満たした。陽極と
して試料をビーカー中央に配置し、陰極としてステンレ
ス円筒板をビーカー側壁に沿わせて配置し（極間距離３
０ｍｍ）、陽極と陰極との間に直流安定化電源を結線し
た。通電は、陽極電流密度が１．０ｍＡ／ｃｍ² となる
定電流条件で、２４０時間行った。発生電気量は、試料
の重量減少から算出した。また、通電終了直後に、銀−
塩化銀電極を参照電極として陽極電位を測定した。That is, the surface of the sample was polished until the roughness of the sandpaper became No. 240, and the other surface was insulated and coated with vinyl tape, leaving 20 cm ² of the side surface.
Next, KCl was 32.0 g / l and NaOH was 24.5 g.
/ L, KOH 10.0 g / l, Ca (OH) ₂ 0.1.
An aqueous solution having a composition of 1 g / l was filled in a 1-liter beaker as a concrete simulation liquid test liquid. The sample was placed at the center of the beaker as the anode, and a stainless steel cylindrical plate was placed along the side wall of the beaker as the cathode (interelectrode distance 3
0 mm), and a DC stabilized power supply was connected between the anode and the cathode. The energization was performed for 240 hours under a constant current condition at which the anode current density was 1.0 mA / cm ² . The amount of electricity generated was calculated from the weight loss of the sample. Immediately after the end of energization, silver-
The anode potential was measured using a silver chloride electrode as a reference electrode.

【００１１】試料の組成および得られた結果を表１に示
す。The composition of the sample and the results obtained are shown in Table 1.

【００１２】（比較例１〜８）また、比較例１〜８とし
て組成を調整したアルミニウム合金を実施例１〜１１と
同様にして試料の鋳塊に加工し、同様の性能試験を実施
した。(Comparative Examples 1 to 8) As Comparative Examples 1 to 8, aluminum alloys whose compositions were adjusted were processed into sample ingots in the same manner as in Examples 1 to 11, and similar performance tests were performed.

【００１３】試料の組成および得られた結果を表１に示
す。The composition of the sample and the results obtained are shown in Table 1.

【００１４】[0014]

【表１】 [Table 1]

【００１５】表１に示したように本発明のアルミニウム
合金は比較例に比して、陽極電位が−１３３３ｍＶ以下
と十分に卑であり、かつ発生電気量が１２５５Ａ・ｈｒ
／ｋｇ以上と十分に大きく、鉄筋コンクリート構造物中
の鉄筋の防食用に好適である。As shown in Table 1, the aluminum alloy of the present invention has a sufficiently low anode potential of −1333 mV and a generated electricity of 1255 A · hr, as compared with the comparative example.
/ Kg or more, which is sufficiently large and suitable for corrosion prevention of reinforcing steel in a reinforced concrete structure.

【００１６】[0016]

【発明の効果】以上のように、７〜５０重量％のＺｎ
と、０．０１〜０．６０重量％のＣａとを含み、残部が
Ａｌおよび不可避不純物からなるアルミニウム合金を流
電陽極とするので、陽極電位が十分に卑で、かつ発生電
気量が十分に大きく、鉄筋コンクリート構造物中の鉄筋
の防食用に好適となる。As described above, 7 to 50% by weight of Zn
And an aluminum alloy containing 0.01 to 0.60% by weight of Ca and the balance being Al and unavoidable impurities is used as the galvanic anode, so that the anode potential is sufficiently low and the amount of generated electricity is sufficient. It is large and is suitable for corrosion prevention of reinforcing bars in reinforced concrete structures.

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 ７〜５０重量％のＺｎと、０．０１〜
０．６０重量％のＣａとを含み、残部がＡｌおよび不可
避不純物からなる流電陽極用アルミニウム合金。1. A method according to claim 1, wherein said Zn is present in an amount of from 7 to 50% by weight.
An aluminum alloy for a galvanic anode containing 0.60% by weight of Ca, with the balance being Al and unavoidable impurities.