JPH08269753A - Al alloy member for heat exchanger excellent in corrosion resistance and al alloy made heat exchanger, their production, formaiton of corrosion resistant coating film to be applied on heat exchanger, and using method of heat exchanger - Google Patents

Al alloy member for heat exchanger excellent in corrosion resistance and al alloy made heat exchanger, their production, formaiton of corrosion resistant coating film to be applied on heat exchanger, and using method of heat exchanger

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Publication number
JPH08269753A
JPH08269753A JP7416695A JP7416695A JPH08269753A JP H08269753 A JPH08269753 A JP H08269753A JP 7416695 A JP7416695 A JP 7416695A JP 7416695 A JP7416695 A JP 7416695A JP H08269753 A JPH08269753 A JP H08269753A
Authority
JP
Japan
Prior art keywords
heat exchanger
alloy
corrosion
resistant coating
alloy member
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.)
Pending
Application number
JP7416695A
Other languages
Japanese (ja)
Inventor
Fumihiro Sato
文博 佐藤
Yoshihiko Asakawa
義彦 浅川
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kobe Steel Ltd
Original Assignee
Kobe Steel Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Kobe Steel Ltd filed Critical Kobe Steel Ltd
Priority to JP7416695A priority Critical patent/JPH08269753A/en
Publication of JPH08269753A publication Critical patent/JPH08269753A/en
Pending legal-status Critical Current

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  • Other Surface Treatments For Metallic Materials (AREA)
  • Prevention Of Electric Corrosion (AREA)

Abstract

PURPOSE: To provide a an Al alloy member for heat exchanges excellent in corrosion resistance. CONSTITUTION: The Al alloy member for heat exchanger excellent in corrosion resistance is obtained by forming a heat resistant coating film consisting essentially of an Al oxide and/or Al hydroxide and containing at least one kind of a metal more base than Al on the surface of an a Al alloy member for heat exchanger. Where, the metal element more base than Al is preferably Mg, Li or Ca.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【産業上の利用分野】本発明は、耐食性に優れた熱交換
器用Al合金部材およびその製造方法、並びに耐食性に
優れたAl合金製熱交換器およびその製造方法に関する
ものである。本発明のなかには、上記Al合金製熱交換
器に施される耐食性皮膜の形成方法および該Al合金製
熱交換器の使用方法も包含される。本発明のAl合金部
材は、熱媒体として地下水や河川等の硬水を使用する熱
交換器に好適に用いられる。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Al alloy member for a heat exchanger having excellent corrosion resistance, a method for manufacturing the same, an Al alloy heat exchanger having excellent corrosion resistance, and a method for manufacturing the same. The present invention also includes a method for forming a corrosion resistant coating applied to the Al alloy heat exchanger and a method for using the Al alloy heat exchanger. INDUSTRIAL APPLICABILITY The Al alloy member of the present invention is suitably used for a heat exchanger that uses ground water or hard water such as rivers as a heat medium.

【0002】[0002]

【従来の技術】Al合金製の熱交換器は、軽量で、且つ
熱伝導性や切削加工性等に優れるという特性を有する
他、押出材等の形材を使用することができるため、現場
での作業性が良く、従って非常に多く使用されている。
この熱交換器に用いられる熱媒体としては、安価で且つ
無害であるという理由により、工業地帯等に豊富に存在
する地下水や河川等の硬水が主に使用されている。
2. Description of the Related Art A heat exchanger made of an Al alloy is lightweight and has excellent properties such as thermal conductivity and cutting workability, and in addition, since it is possible to use a shaped material such as an extruded material, it is possible to use it on site. Has good workability and is therefore used very often.
As the heat medium used in this heat exchanger, ground water and hard water such as rivers that are abundant in industrial areas are mainly used because they are inexpensive and harmless.

【0003】しかしながら、熱媒体として有用な硬水中
には、炭酸イオン、炭酸水素イオン、硫酸イオン等の酸
化性陰イオン;Fe3+やCu2+等の高原子価金属イオン
等が多量に含まれている。これらのイオンは酸化剤とし
て作用し、例えば溶液の局部的不均一等が原因となっ
て、Al合金の自然電位が部分的に上昇し、局部電池を
形成する。そして、Alの自然電位が孔食発生電位を超
えると腐食を起こし、その結果、Al合金における典型
的な腐食の一つである孔食を招いて熱媒体の水漏れや応
力腐食割れを生じる等、熱交換器の運転に当たって大き
な弊害をもたらす様になる。
However, hard water useful as a heat medium contains a large amount of oxidizing anions such as carbonate ions, hydrogen carbonate ions and sulfate ions; and high valent metal ions such as Fe 3+ and Cu 2+. Has been. These ions act as an oxidizing agent, and due to, for example, local nonuniformity of the solution, the spontaneous potential of the Al alloy partially rises to form a local battery. Corrosion occurs when the natural potential of Al exceeds the pitting corrosion generation potential, and as a result, pitting corrosion, which is one of the typical corrosion in Al alloys, is caused, resulting in water leakage of the heat medium and stress corrosion cracking. However, it will cause a great adverse effect on the operation of the heat exchanger.

【0004】そこで、この様な腐食に基づく弊害を抑制
することを目的として、熱媒体中へ防食インヒビターを
添加する方法が実施されているが、コストが上昇する
他、これらのインヒビターには有害物質が多いので、廃
液処理が困難である等の問題が生じる。あるいは、Al
合金部材の表面に有機樹脂をコーティングして防食作用
を向上させる方法も試みられているが、コーティングに
当たって熱交換面積を拡大させる必要があり、それに伴
って設計上の複雑変更や熱伝達効率の低下等の問題を招
くと共に、コストが上昇する等の不都合を生じる。
Therefore, a method of adding an anticorrosion inhibitor to the heat medium has been carried out for the purpose of suppressing the harmful effects caused by such corrosion, but the cost is increased and a harmful substance is added to these inhibitors. Therefore, problems such as difficulty in waste liquid treatment occur. Alternatively, Al
A method of coating the surface of the alloy member with an organic resin to improve the anticorrosion effect has also been attempted, but it is necessary to enlarge the heat exchange area for coating, and accordingly, complicated design changes and reduction of heat transfer efficiency are required. And the like, and inconveniences such as an increase in cost occur.

【0005】[0005]

【発明が解決しようとする課題】本発明は上記の様な事
情に着目してなされたものであり、その目的は、耐食性
に優れた熱交換器用Al合金部材およびAl合金製熱交
換器、並びにこれらを効率よく製造することのできる方
法を提供すると共に、高耐食性を維持しつつ該熱交換器
を運転する方法等も合わせて提供することにある。
The present invention has been made in view of the above circumstances, and an object thereof is an Al alloy member for a heat exchanger excellent in corrosion resistance, an Al alloy heat exchanger, and It is an object of the present invention to provide not only a method for efficiently producing these, but also a method for operating the heat exchanger while maintaining high corrosion resistance.

【0006】[0006]

【課題を解決するための手段】上記課題を解決すること
のできた本発明の熱交換器用Al合金部材は、熱交換器
用Al合金部材の表面に、Alの酸化物および/または
Alの水酸化物を主体とし、且つAlより卑な金属元素
を少なくとも1種含有する耐食性皮膜(以下、耐食性皮
膜と略記する場合がある)が形成されたところに要旨を
有する。
The Al alloy member for a heat exchanger of the present invention, which has been able to solve the above problems, has an Al oxide and / or an Al hydroxide on the surface of the Al alloy member for a heat exchanger. The main point is that a corrosion-resistant film (hereinafter sometimes abbreviated as a corrosion-resistant film) containing at least one metal element that is mainly composed of Al and is less than Al is formed.

【0007】ここで、上記Alより卑な金属元素がM
g,LiまたはCaであるもの、および上記耐食性皮膜
の膜厚が0.2μm以上であるものは本発明の好適な実
施態である。また、上記課題を解決することのできた本
発明のAl合金製熱交換器は、熱交換器用Al合金部材
の表面に、上記耐食性皮膜が形成されたところに要旨を
有する。
Here, the metal element that is less base than Al is M
g, Li or Ca, and those in which the thickness of the corrosion-resistant coating is 0.2 μm or more are preferred embodiments of the present invention. Further, the Al alloy heat exchanger of the present invention which has been able to solve the above problems has a gist in that the above corrosion resistant coating is formed on the surface of the Al alloy member for a heat exchanger.

【0008】本発明の熱交換器用Al合金部材およびA
l合金製熱交換器を製造する方法は、Alより卑な金属
元素を少なくとも1種含有する溶液中に熱交換器用Al
合金部材を浸漬することによって、その表面に、上記耐
食性皮膜を形成するところに要旨を有する。
Al alloy member for heat exchanger of the present invention and A
The method for producing a heat exchanger made of 1-alloy is as follows.
The point is to form the above-mentioned corrosion resistant film on the surface of the alloy member by immersing the alloy member.

【0009】ここで、本発明のAl合金製熱交換器を製
造するに当たっては、上記方法の他、Al合金製熱交換
器を、熱媒体である硬水中に浸漬しながら運転すること
によって、その表面に、上記耐食性皮膜を形成する方法
も採用される。用いられる溶液として好ましいのは硬水
である。
Here, in manufacturing the Al alloy heat exchanger of the present invention, in addition to the above method, the Al alloy heat exchanger is operated while being immersed in hard water as a heat medium. A method of forming the above corrosion resistant film on the surface is also adopted. The preferred solution used is hard water.

【0010】また、上記耐食性皮膜の形成方法は、Al
合金製熱交換器を運転しながら、Alより卑な金属元素
を少なくとも1種含有させた熱媒体中に該熱交換器を浸
漬することによって、その表面に、上記耐食性皮膜を形
成するところに要旨を有する。用いられる熱媒体として
好ましいのは硬水である。
Further, the method of forming the corrosion resistant film is as follows.
While the alloy heat exchanger is being operated, the heat exchanger is immersed in a heat medium containing at least one metal element that is baser than Al to form the above corrosion-resistant coating on the surface thereof. Have. Hard water is preferred as the heat medium used.

【0011】更に、本発明のAl合金製熱交換器を使用
する方法は、Al合金製熱交換器を運転しながら、少な
くとも1種のAlより卑な金属元素を合計で0.01m
ol/L以上含有する熱媒体中に該熱交換器を浸漬する
ことによって、その表面に、上記耐食性皮膜を形成させ
つつ操業するところに要旨を有する。熱媒体として好ま
しいのは硬水である。
Further, according to the method of using the Al alloy heat exchanger of the present invention, at least one metal element which is baser than Al is 0.01 m in total while operating the Al alloy heat exchanger.
The point is to operate while forming the above-mentioned corrosion resistant film on the surface of the heat exchanger by immersing the heat exchanger in a heat medium containing ol / L or more. Hard water is preferred as the heat medium.

【0012】[0012]

【作用】上述した様に、熱交換器用熱媒体として好適に
用いられる硬水中には、炭酸水素イオン等の酸化性陰イ
オン;Fe3+やCu2+等の高原子価金属イオン等が多量
に含まれているので、それらの酸化作用により、Al合
金の自然電位が上昇して腐食(特に孔食)が生じると考
えられる。
As described above, hard water suitably used as the heat medium for the heat exchanger contains a large amount of oxidizing anions such as hydrogen carbonate ions; high valent metal ions such as Fe 3+ and Cu 2+. Therefore, it is considered that due to their oxidizing action, the spontaneous potential of the Al alloy rises and corrosion (particularly pitting corrosion) occurs.

【0013】そこで、Al合金部材の自然電位を低下さ
せる方法について本発明者等が検討したところ、Alよ
り卑な金属元素(例えばMg,Li,Ca等)を含有す
る皮膜をその表面に形成することによって、腐食に悪影
響を及ぼす上記酸化剤の作用を抑制すれば腐食を抑える
ことができることを見出して本発明を完成したのであ
る。
Then, the inventors of the present invention studied a method of lowering the spontaneous potential of the Al alloy member. As a result, a film containing a metal element (eg, Mg, Li, Ca, etc.) that is baser than Al was formed on the surface. Thus, the present invention has been completed by finding that corrosion can be suppressed by suppressing the action of the above-mentioned oxidizing agent that adversely affects corrosion.

【0014】即ち本発明は、Al合金部材の表面に、A
lの酸化物および/またはAlの水酸化物を主体とし、
且つAlより卑な金属元素を少なくとも1種含有する高
耐食性皮膜(以下、再び耐食性皮膜で代表することがあ
る)を形成する点に最大の特徴を有する。詳細には、A
lより卑な金属元素を含有する水溶性塩の水溶液をpH
調整した後、この溶液にAl合金部材を所定時間浸漬す
れば、その表面に上記耐食性皮膜が形成されるのであ
る。この様に上記耐食性皮膜は浸漬処理のみで容易に成
膜できると共に、熱交換器の運転中であっても熱媒体中
に上記金属元素を含む水溶性塩を添加すれば速やかに成
膜できることから、製造効率の面においても稼働効率の
面においても非常に優れた方法であることが分かる。更
に、一旦形成された耐食性皮膜は、酸化剤に対するバリ
ヤー層としての作用がAl23 単独の場合に比べてよ
り強く発揮する結果、炭酸イオン等の酸化剤を含有する
地下水を熱媒体として用いて熱交換を行った場合であっ
ても、優れた耐食作用を発揮することができるのであ
る。以下、この耐食性皮膜を形成する過程を順次説明し
ていきながら本発明の特徴を述べていく。
That is, according to the present invention, A
1 oxide and / or Al hydroxide as a main component,
Moreover, it has the greatest feature in forming a highly corrosion-resistant film (hereinafter, may be represented again by a corrosion-resistant film) containing at least one kind of metal element that is baser than Al. Specifically, A
l pH of an aqueous solution of a water-soluble salt containing a base metal element
After the adjustment, if the Al alloy member is dipped in this solution for a predetermined time, the above corrosion resistant film is formed on the surface thereof. As described above, the above corrosion-resistant film can be easily formed only by the dipping treatment, and even during the operation of the heat exchanger, the film can be rapidly formed by adding the water-soluble salt containing the metal element to the heating medium. It can be seen that this is a very excellent method in terms of both manufacturing efficiency and operating efficiency. Furthermore, once formed, the corrosion-resistant film exerts a stronger action as a barrier layer against an oxidizing agent than when Al 2 O 3 alone is used. As a result, groundwater containing an oxidizing agent such as carbonate ion is used as a heat medium. Even when heat exchange is performed by heat, excellent corrosion resistance can be exhibited. The features of the present invention will be described below while sequentially explaining the process of forming this corrosion-resistant coating.

【0015】まず、Alより卑な金属元素としては、M
g,Ca,Sr,Ba,Li,Na,K,Rb,Cs等
が挙げられるが、耐食性、水溶性塩の形成し易さ、低コ
スト、繁用性等を考慮すれば、Mg,CaおよびLiが
好ましく、より好ましいのはMgおよびLiである。こ
れらの金属元素は、それぞれ単独で用いてもよく、ある
いは2種以上併用してもよい。
First, as a metal element that is baser than Al, M
g, Ca, Sr, Ba, Li, Na, K, Rb, Cs, etc., but if considering corrosion resistance, easiness of forming a water-soluble salt, low cost, versatility, etc., Mg, Ca and Li is preferred, and Mg and Li are more preferred. These metal elements may be used alone or in combination of two or more.

【0016】次に、上記金属元素を水溶性塩の形態で溶
液中に含有させる訳であるが、この水溶性塩の存在形態
は、使用する金属の種類に応じて、硫酸塩、水酸塩、炭
酸塩、炭酸水素塩等の如く、溶解し易い形態を適宜選択
することが好ましい。例えば、Mgの場合はMgSO4
等、Caの場合はCa(HCO32 等、Liの場合は
LiCO3 等の様な塩の形態とすることが好ましい。
Next, the above metal element is contained in the solution in the form of a water-soluble salt. The existence form of this water-soluble salt depends on the type of metal used, sulfate or hydroxide. It is preferable to appropriately select a form that readily dissolves, such as carbonate, hydrogen carbonate, and the like. For example, in the case of Mg, MgSO 4
Etc. In the case of Ca, Ca (HCO 3 ) 2 or the like is preferable, and in the case of Li, salt forms such as LiCO 3 or the like are preferable.

【0017】次いで、上記金属元素の水溶性塩を含有す
る水溶液を好適なpHに調整した後、この溶液中に熱交
換器用Al合金部材を所定時間浸漬することにより耐食
性皮膜を形成する。
Next, after adjusting the pH of the aqueous solution containing the water-soluble salt of the metal element to a suitable pH, the Al alloy member for the heat exchanger is dipped in this solution for a predetermined time to form a corrosion resistant film.

【0018】本発明においては、上記耐食性皮膜の膜厚
を制御することにより、耐食作用を高めることができ
る。即ち、皮膜の途切れを生じさせることなく、上述し
た金属元素の添加による耐食作用を有効に発揮させるに
は、上記皮膜の膜厚を0.2μm以上とすることが好ま
しい。より好ましいのは2μm以上である。しかしなが
ら、多量に形成しても、その効果は飽和するだけであっ
て経済的に無駄であるばかりか、皮膜表面にパウダリン
グが生じる恐れがあるため、その上限を7μm以下とす
ることが好ましい。より好ましいのは4μm以下であ
る。
In the present invention, the corrosion resistance can be enhanced by controlling the film thickness of the corrosion resistant coating. That is, the film thickness of the film is preferably 0.2 μm or more in order to effectively exhibit the corrosion resistance effect due to the addition of the metal element described above without causing the film discontinuity. More preferably, it is 2 μm or more. However, even if formed in a large amount, not only is the effect saturated, which is economically wasteful, but powdering may occur on the film surface. Therefore, the upper limit is preferably 7 μm or less. More preferably, it is 4 μm or less.

【0019】この様な好適な耐食性皮膜の膜厚は、浸漬
条件をコントロールすることによって得られる。具体的
には、浸漬時間、浸漬温度、使用する金属イオンの濃度
等を適宜変化させることによって、所望の膜厚を得るの
である。
The thickness of such a suitable corrosion resistant coating can be obtained by controlling the immersion conditions. Specifically, the desired film thickness is obtained by appropriately changing the immersion time, the immersion temperature, the concentration of the metal ions used, and the like.

【0020】具体的には、例えば膜厚:3〜4μmのM
g含有皮膜を形成する場合には、水溶性塩としてMgS
4 (Mgイオン濃度:0.01〜0.05mol/
L)、pH:6〜7、浸漬温度:60〜90℃、処理時
間:15〜120分とすることが好ましい。
Specifically, for example, the film thickness: M of 3 to 4 μm
When forming a g-containing film, MgS is used as a water-soluble salt.
O 4 (Mg ion concentration: 0.01 to 0.05 mol /
L), pH: 6 to 7, immersion temperature: 60 to 90 ° C., and treatment time: 15 to 120 minutes.

【0021】この様にして形成された耐食性皮膜中、上
記金属元素がどの様な形態で存在しているかは詳細には
不明であるが、いずれにせよ上記耐食性皮膜には、Al
の酸化物および/またはAlの水酸化物を主体とし、且
つAlより卑な金属元素を少なくとも1種含有してお
り、この様な膜を有する本発明のAl合金部材および熱
交換器は、従来例(本発明による耐食性皮膜が施されて
いないもの)に比べて非常に優れた耐食性を発揮するこ
とができるのである。
It is not known in detail in what form the metal element exists in the corrosion-resistant coating thus formed, but in any case, the corrosion-resistant coating contains Al.
The Al alloy member and the heat exchanger of the present invention, which mainly contain the oxide of Al and / or the hydroxide of Al and contain at least one metal element that is baser than Al, and have such a film are It is possible to exhibit extremely excellent corrosion resistance as compared with the examples (those not provided with the corrosion resistant film according to the present invention).

【0022】そして上記耐食性皮膜は、熱交換器用Al
合金部材をAlより卑な金属元素の水溶性塩を含む水溶
液(単に溶液と略記する場合がある)中に浸漬すること
等によって容易に形成されるので、非常に簡単で効率の
良い方法と言える。
The corrosion-resistant coating is made of Al for heat exchanger.
It can be said to be a very simple and efficient method because it is easily formed by immersing the alloy member in an aqueous solution containing a water-soluble salt of a metal element less base than Al (may be simply referred to as a solution). .

【0023】なお、この耐食性皮膜を熱交換器用Al合
金部材の表面に形成する(即ち、溶液中に浸漬する)時
期としては特に限定されず、 熱交換器の組立前に、Al合金部材を溶液中に浸漬し
ても良いし、 熱交換器(耐食性皮膜処理なし)を組立ててから、溶
液中に浸漬させても良いし、あるいは、 熱交換器(耐食性皮膜処理なし)を組立てた後、熱媒
体である硬水中に浸漬しながら運転することによって耐
食性皮膜を形成させても良い。
The time when the corrosion resistant coating is formed on the surface of the Al alloy member for a heat exchanger (that is, immersed in the solution) is not particularly limited, and the Al alloy member is dissolved in the solution before the heat exchanger is assembled. It may be immersed in water, or it may be immersed in a solution after assembling a heat exchanger (without corrosion-resistant coating), or after assembling the heat exchanger (without corrosion-resistant coating). The corrosion resistant film may be formed by operating while being immersed in hard water as a medium.

【0024】この様に本発明における耐食性皮膜は、熱
交換器の組立前、組立後、運転中(運転初期のみなら
ず、全期間中も含む)の任意の段階で形成することが可
能である。ここで、各段階における成膜処理は別々に行
ってもよいし、あるいは耐食性を高めることを目的とし
て、上記の各段階で成膜処理を同時に施す(例えば、組
立前に処理した後、更に運転中にも処理する方法)こと
も勿論有効である。また成膜処理される熱交換器は、必
ずしも新品である必要はなく、長年使用して耐食性が劣
化した熱交換器を用いても良く、これにより資源の有効
利用を図ることができる。
As described above, the corrosion-resistant coating of the present invention can be formed at any stage before, after, and after operation of the heat exchanger (not only at the beginning of operation but also during the entire period). . Here, the film forming process in each step may be performed separately, or the film forming process is performed at the same time in each of the above steps for the purpose of enhancing the corrosion resistance (for example, after performing the process before assembling, further performing the operation. Of course, it is also effective to treat the inside. Further, the heat exchanger subjected to the film formation process does not necessarily have to be a new one, and a heat exchanger whose corrosion resistance has deteriorated after being used for many years may be used, which enables effective use of resources.

【0025】なお、上記金属元素を溶解して水溶性塩と
するための溶液および熱交換器の運転時に用いられる熱
媒体は、特に地下水が好ましい。地下水は地表水に比べ
て、一般にに高原子価金属イオン量は少なく炭酸イオン
等を多量に含有しているので、腐食に悪影響を及ぼす主
たる原因物質は炭酸イオンであると考えられる。そして
この炭酸イオンは、Mg等のAlより卑な金属元素と容
易に反応してMgCO 3 等の不溶性塩を形成するので、
Al合金部材に悪影響を及ぼすことがなくなる。この様
に地下水は、本発明に用いられる金属元素がトラップし
易い酸化剤を多く含有しているため、本発明による耐食
作用を一層有効に発揮させることができるのである。
The above metal element is dissolved to form a water-soluble salt.
Solution and heat used to operate the heat exchanger
Groundwater is particularly preferable as the medium. Groundwater is more than surface water
In general, the amount of high-valent metal ions is low and carbonate ions are low.
Since it contains a large amount of
The causative substance is considered to be carbonate ion. And
This carbonate ion is a metal element that is more base than Al such as Mg
Easily reacts with MgCO 3 Form insoluble salts such as
It does not adversely affect the Al alloy member. Like this
In addition, groundwater is trapped by the metal elements used in the present invention.
Corrosion resistance according to the present invention because it contains a lot of easy oxidizing agents
The effect can be exerted more effectively.

【0026】なお、本発明に用いられるAl合金部材
は、純Alを始め、種々のAl合金に適用できるが、そ
のなかでも最も汎用性の高い合金としては、Al−Mg
系合金(JIS 5000番台のAl合金)およびAl
−Mg−Si系合金(JIS6000番台のAl合金)
が挙げられる。これらの合金は、押出形材としても好適
なものである。
The Al alloy member used in the present invention can be applied to various Al alloys including pure Al. Among them, the most versatile alloy is Al-Mg.
-Based alloys (Al alloys in the JIS 5000 series) and Al
-Mg-Si system alloy (Al alloy of JIS6000 series)
Is mentioned. These alloys are also suitable as extruded profiles.

【0027】以上、本発明に施される耐食性皮膜の形成
方法を中心に説明したが、本発明の熱交換器用Al合金
部材は、その表面にこの耐食性皮膜が施されたものであ
り、また本発明のAl合金製熱交換器は、熱交換器用A
l合金部材の表面にこの耐食性皮膜が形成されたもので
ある。そして、上述の様にして形成された耐食性皮膜
は、酸化剤に対するバリヤー層としても有効に作用する
ので、熱交換等において更に酸化剤に曝されることがあ
ってもAl合金の腐食を有効に抑えることができる。そ
の詳細な理由については明らかではないが、例えば炭酸
イオンを多量に含有する地下水を熱媒体として用いた場
合を例に挙げると、以下の様なことが考えられる。即
ち、本発明の熱交換器は、熱交換中、炭酸イオン等の酸
化剤に曝されることになるが、その表面に形成された耐
食性皮膜中に存在するMgCO3 等の不溶性塩はAlに
対してアノードとして作用するため、電位を低下させる
作用があり、その結果孔食発生(電位の上昇)を抑制
し、炭酸イオンがAl合金部材の内部に侵入して腐食を
起こすのを防止することができると考えられる。
The method of forming the corrosion-resistant coating according to the present invention has been mainly described above, but the Al alloy member for a heat exchanger according to the present invention has the corrosion-resistant coating applied to the surface thereof. The heat exchanger made of Al alloy of the invention is A for heat exchanger.
The corrosion resistant coating is formed on the surface of the 1-alloy member. The corrosion-resistant film formed as described above also effectively acts as a barrier layer against the oxidizing agent, so that even if it is further exposed to the oxidizing agent during heat exchange or the like, it effectively corrodes the Al alloy. Can be suppressed. Although the detailed reason for this is not clear, the following can be considered, for example, when groundwater containing a large amount of carbonate ions is used as the heat medium. That is, the heat exchanger of the present invention is exposed to an oxidizing agent such as carbonate ion during heat exchange, but the insoluble salt such as MgCO 3 present in the corrosion-resistant film formed on the surface thereof is converted into Al. On the other hand, since it acts as an anode, it has the effect of lowering the potential, and as a result, suppresses the occurrence of pitting corrosion (elevation of the potential) and prevents carbonate ions from entering the Al alloy member and causing corrosion. It is thought that it can be done.

【0028】この様な耐食性皮膜によるバリヤー層とし
ての作用を有効に発揮させるには、この皮膜の膜厚を上
述した好適範囲(好ましくは0.2μm以上、より好ま
しくは3μm以上)に制御することが好ましい。
In order to effectively exhibit the action of such a corrosion-resistant coating as a barrier layer, the thickness of this coating should be controlled within the above-mentioned preferred range (preferably 0.2 μm or more, more preferably 3 μm or more). Is preferred.

【0029】以下実施例を挙げて本発明をさらに詳細に
説明するが、下記実施例は本発明を制限するものではな
く、前・後記の趣旨を逸脱しない範囲で変更実施するこ
とは全て本発明の技術的範囲に包含される。
The present invention will be described in more detail with reference to the following examples, but the following examples are not intended to limit the present invention, and any modification or implementation is within the scope of the present invention without departing from the gist thereof. It is included in the technical scope of.

【0030】[0030]

【実施例】50×50mmのJIS 6063Al押出
材(厚み:2.5mm)を湿式のエメリー紙(#60
0)で研磨した供試材料(No.1,1’,1''および2
〜11)を使用し、以下に示す〜の成膜処理を施す
ことにより、その表面に表1に示す膜厚からなる皮膜を
形成させた。
[Example] A 50 × 50 mm JIS 6063 Al extruded material (thickness: 2.5 mm) was applied to wet emery paper (# 60).
0) polished with the test materials (No. 1, 1 ', 1''and 2
To 11) were used to perform the film forming processes 1 to 11 below to form a film having a film thickness shown in Table 1 on the surface thereof.

【0031】[0031]

【表1】 [Table 1]

【0032】No.1、2〜6および7〜11は、表1
に示す金属イオン濃度を含有する塩溶液[Mgの場合は
MgSO4 、Liの場合はLiCO3 、Caの場合はC
a(HC032 ]中に、表1に示す処理条件で浸漬す
ることにより皮膜を形成させた。 No.1’は、上記の成膜処理を行った後、更にNo.
1で用いた金属イオン濃度を含むMg塩の地下水溶液に
90℃で20時間浸漬することにより皮膜を形成させ
た。なお、この処理に用いた地下水は、京都府南部で採
取したものであり、その組成は表2に示す通りである。
Nos. 1, 2 to 6 and 7 to 11 are shown in Table 1.
The salt solution containing the metal ion concentration shown in [[Mg 4 for Mg, LiCO 3 for Li, C for Ca]
a (HC0 3 ) 2 ] under the treatment conditions shown in Table 1 to form a film. No. 1'is No. 1 after performing the above film forming process.
A film was formed by immersing in the underground aqueous solution of the Mg salt containing the metal ion concentration used in 1 at 90 ° C. for 20 hours. The groundwater used for this treatment was collected in the southern part of Kyoto Prefecture, and its composition is as shown in Table 2.

【0033】[0033]

【表2】 [Table 2]

【0034】No.1''は、上記の方法においての
成膜処理を行わなずに処理することによって皮膜を形成
させた。 No.7は、この様な成膜処理を全く施さない従来例で
ある。
No. 1 '' was processed without performing the film forming process in the above method to form a film. No. 7 is a conventional example in which such a film forming process is not performed at all.

【0035】この様にして処理された各供試材料につい
て耐食性を評価した。耐食性の評価に当たっては、これ
らの供試材料を上記で用いた地下水中に、大気開放
下、32±1℃で20日間浸漬させた後、孔食発生の有
無を目視で観察した。なお、No.1’および1''につい
ては、成膜処理時に用いた金属元素含有地下水を用い
て、同様に耐食性を評価した。その結果を表1に併記す
る。
The corrosion resistance of each test material treated in this way was evaluated. In the evaluation of corrosion resistance, these test materials were immersed in the groundwater used above at 32 ± 1 ° C. for 20 days in the open air, and then the presence or absence of pitting corrosion was visually observed. Regarding No. 1'and 1 '', the corrosion resistance was similarly evaluated using the metal element-containing groundwater used in the film formation process. The results are also shown in Table 1.

【0036】表から明らかな様に、本発明例は、いずれ
も従来例に比べて耐食性が向上し、更に耐食性皮膜の膜
厚を0.2μm以上にすることによって、耐食性効果を
格段に向上させることができた。また、耐食性皮膜の形
成時期は、上記成膜処理条件〜のいずれを採用して
も耐食性向上効果に何等影響はないことが分かった。
As is apparent from the table, in all the examples of the present invention, the corrosion resistance is improved as compared with the conventional example, and the corrosion resistance effect is remarkably improved by setting the thickness of the corrosion resistant film to 0.2 μm or more. I was able to. Further, it was found that the formation time of the corrosion resistant coating has no effect on the corrosion resistance improving effect by adopting any one of the above film forming treatment conditions.

【0037】[0037]

【発明の効果】以上説明したことから明らかなように、
本発明の熱交換器用Al合金部材およびAl合金製熱交
換器は、その表面に、Alの酸化物および/またはAl
の水酸化物を主体とし、且つAlより卑な金属元素を少
なくとも1種含有する耐食性皮膜を有しているので、熱
交換器の運転中、耐食性を劣化させることなく効率よく
稼働させることができる。
As is apparent from the above description,
The Al alloy member for a heat exchanger and the Al alloy heat exchanger of the present invention have Al oxide and / or Al oxide on the surface thereof.
Since it has a corrosion-resistant film mainly containing hydroxide and containing at least one kind of metal element that is baser than Al, it can be efficiently operated during operation of the heat exchanger without degrading corrosion resistance. .

【0038】そして上記耐食性皮膜は、Al合金製熱交
換器の組立前、組立後、運転中のいずれの段階でも形成
することができ、且つその形成方法は、Alより卑な金
属元素を含む溶液中に熱交換器用Al合金部材を浸漬す
るだけで簡単に施すことができるので、非常に簡単で効
率の良い方法である。
The corrosion-resistant coating can be formed at any stage before, after, and after operation of the Al alloy heat exchanger, and the forming method is a solution containing a metal element less base than Al. This is a very simple and efficient method because it can be applied simply by immersing the Al alloy member for heat exchanger therein.

───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 FI 技術表示箇所 F28F 19/06 F28F 19/06 A ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Office reference number FI technical display area F28F 19/06 F28F 19/06 A

Claims (13)

【特許請求の範囲】[Claims] 【請求項1】 熱交換器用Al合金部材の表面に、Al
の酸化物および/またはAlの水酸化物を主体とし、且
つAlより卑な金属元素を少なくとも1種含有する耐食
性皮膜が形成されたものであることを特徴とする耐食性
に優れた熱交換器用Al合金部材。
1. A surface of an Al alloy member for a heat exchanger is coated with Al.
Excellent in corrosion resistance, characterized by being formed of a corrosion-resistant coating mainly containing oxide of Al and / or hydroxide of Al and containing at least one metal element that is baser than Al. Alloy material.
【請求項2】 前記Alより卑な金属元素が、Mg,L
iまたはCaである請求項1に記載のAl合金部材。
2. A metal element which is baser than Al is Mg, L
The Al alloy member according to claim 1, which is i or Ca.
【請求項3】 前記耐食性皮膜の膜厚が0.2μm以上
である請求項1または2に記載のAl合金部材。
3. The Al alloy member according to claim 1, wherein the thickness of the corrosion-resistant coating is 0.2 μm or more.
【請求項4】 熱交換器用Al合金部材の表面に、請求
項1〜3のいずれかに記載の耐食性皮膜が形成されたも
のであることを特徴とする耐食性に優れたAl合金製熱
交換器。
4. An Al alloy heat exchanger having excellent corrosion resistance, characterized in that the corrosion resistant coating according to any one of claims 1 to 3 is formed on the surface of an Al alloy member for a heat exchanger. .
【請求項5】 Alより卑な金属元素を少なくとも1種
含有する溶液中に熱交換器用Al合金部材を浸漬するこ
とによって、その表面に、請求項1〜3のいずれかに記
載の耐食性皮膜を形成することを特徴とする熱交換器用
Al合金部材の製造方法。
5. The corrosion resistant coating according to any one of claims 1 to 3 is formed on the surface of an Al alloy member for a heat exchanger by immersing it in a solution containing at least one metal element that is baser than Al. A method of manufacturing an Al alloy member for a heat exchanger, which comprises forming the Al alloy member.
【請求項6】 前記溶液が硬水である請求項5に記載の
製造方法。
6. The manufacturing method according to claim 5, wherein the solution is hard water.
【請求項7】 Alより卑な金属元素を少なくとも1種
含有する溶液中に熱交換器用Al合金部材を浸漬するこ
とによって、その表面に、請求項1〜3のいずれかに記
載の耐食性皮膜を形成することを特徴とするAl合金製
熱交換器の製造方法。
7. The corrosion resistant coating according to any one of claims 1 to 3 is formed by immersing an Al alloy member for a heat exchanger in a solution containing at least one metal element that is baser than Al. A method for manufacturing an Al alloy heat exchanger, which is characterized in that the heat exchanger is formed.
【請求項8】 前記溶液が硬水である請求項7に記載の
製造方法。
8. The manufacturing method according to claim 7, wherein the solution is hard water.
【請求項9】 Al合金製熱交換器を、熱媒体である硬
水中に浸漬しながら運転することによって、その表面
に、請求項1〜3のいずれかに記載の耐食性皮膜を形成
することを特徴とするAl合金製熱交換器の製造方法。
9. An Al alloy heat exchanger is operated while being immersed in hard water as a heat medium to form the corrosion resistant film according to any one of claims 1 to 3 on its surface. A method for manufacturing a heat exchanger made of a characteristic Al alloy.
【請求項10】 Al合金製熱交換器を運転しながら、
Alより卑な金属元素を少なくとも1種含有させた熱媒
体中に該熱交換器を浸漬することによって、その表面
に、請求項1〜3のいずれかに記載の耐食性皮膜を形成
することを特徴とするAl合金製熱交換器に施される耐
食性皮膜の形成方法。
10. While operating the Al alloy heat exchanger,
The corrosion resistant coating according to any one of claims 1 to 3 is formed on the surface of the heat exchanger by immersing the heat exchanger in a heating medium containing at least one metal element that is baser than Al. And a method for forming a corrosion resistant coating applied to an Al alloy heat exchanger.
【請求項11】 前記熱媒体が硬水である請求項10に
記載の方法。
11. The method according to claim 10, wherein the heating medium is hard water.
【請求項12】 Al合金製熱交換器を運転しながら、
少なくとも1種のAlより卑な金属元素を合計で0.0
1mol/L以上含有する熱媒体中に該熱交換器を浸漬
することによって、その表面に、請求項1〜3のいずれ
かに記載の耐食性皮膜を形成しつつ操業することを特徴
とするAl合金製熱交換器の使用方法。
12. While operating the Al alloy heat exchanger,
A total of at least one metal element that is baser than Al is 0.0
By immersing the heat exchanger in a heat medium containing 1 mol / L or more, the Al alloy is operated while forming the corrosion-resistant coating according to any one of claims 1 to 3 on its surface. How to use the heat exchanger.
【請求項13】 前記熱媒体が硬水である請求項12に
記載の方法。
13. The method according to claim 12, wherein the heating medium is hard water.
JP7416695A 1995-03-30 1995-03-30 Al alloy member for heat exchanger excellent in corrosion resistance and al alloy made heat exchanger, their production, formaiton of corrosion resistant coating film to be applied on heat exchanger, and using method of heat exchanger Pending JPH08269753A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP7416695A JPH08269753A (en) 1995-03-30 1995-03-30 Al alloy member for heat exchanger excellent in corrosion resistance and al alloy made heat exchanger, their production, formaiton of corrosion resistant coating film to be applied on heat exchanger, and using method of heat exchanger

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7416695A JPH08269753A (en) 1995-03-30 1995-03-30 Al alloy member for heat exchanger excellent in corrosion resistance and al alloy made heat exchanger, their production, formaiton of corrosion resistant coating film to be applied on heat exchanger, and using method of heat exchanger

Publications (1)

Publication Number Publication Date
JPH08269753A true JPH08269753A (en) 1996-10-15

Family

ID=13539305

Family Applications (1)

Application Number Title Priority Date Filing Date
JP7416695A Pending JPH08269753A (en) 1995-03-30 1995-03-30 Al alloy member for heat exchanger excellent in corrosion resistance and al alloy made heat exchanger, their production, formaiton of corrosion resistant coating film to be applied on heat exchanger, and using method of heat exchanger

Country Status (1)

Country Link
JP (1) JPH08269753A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1762639A1 (en) * 2005-09-13 2007-03-14 Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) Heat transfer tube for LNG vaporizer, its production method, and LNG vaporizer using such heat transfer tubes
KR100865212B1 (en) * 2005-09-13 2008-10-23 가부시키가이샤 고베 세이코쇼 Heat transfer tube for lng vaporizer, its production method, and lng vaporizer using such heat transfer tubes
CN105190218A (en) * 2013-04-19 2015-12-23 乔治洛德方法研究和开发液化空气有限公司 Method for producing a multilayer element having a protective coating

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1762639A1 (en) * 2005-09-13 2007-03-14 Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) Heat transfer tube for LNG vaporizer, its production method, and LNG vaporizer using such heat transfer tubes
KR100865212B1 (en) * 2005-09-13 2008-10-23 가부시키가이샤 고베 세이코쇼 Heat transfer tube for lng vaporizer, its production method, and lng vaporizer using such heat transfer tubes
CN105190218A (en) * 2013-04-19 2015-12-23 乔治洛德方法研究和开发液化空气有限公司 Method for producing a multilayer element having a protective coating
CN105190218B (en) * 2013-04-19 2017-12-08 乔治洛德方法研究和开发液化空气有限公司 The method for preparing the sandwich type element with protective coating

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