JPH0835052A - Production of outside face corrosion resistant cast iron tube - Google Patents
Production of outside face corrosion resistant cast iron tubeInfo
- Publication number
- JPH0835052A JPH0835052A JP17125594A JP17125594A JPH0835052A JP H0835052 A JPH0835052 A JP H0835052A JP 17125594 A JP17125594 A JP 17125594A JP 17125594 A JP17125594 A JP 17125594A JP H0835052 A JPH0835052 A JP H0835052A
- Authority
- JP
- Japan
- Prior art keywords
- cast iron
- iron pipe
- iron tube
- film
- aluminum oxide
- 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.)
- Granted
Links
Landscapes
- Cleaning By Liquid Or Steam (AREA)
- Coating By Spraying Or Casting (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は鋳鉄管の外面に、焼鈍時
の高温を利用して酸化アルミニウムの防食被膜を形成す
る方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an aluminum oxide anticorrosion coating on the outer surface of a cast iron pipe by utilizing the high temperature during annealing.
【０００２】[0002]
【従来の技術】遠心力鋳造された鋳鉄管は、基地組織を
フェライト化して靱性を付与するために、焼鈍熱処理が
施されるのが通例である。この際、特開平３−１５０３
４３号公報に開示されているように、鋳鉄管を鋳造した
後、該鋳鉄管の外周面にＡｌ又はＡｌを主成分とするＡ
ｌ合金の被膜を被着しておき、焼鈍熱処理の際にその外
周面に酸化アルミニウムの防食被膜を形成することが行
われている。2. Description of the Related Art Centrifugal cast iron pipes are usually subjected to an annealing heat treatment in order to form a matrix structure into ferrite to impart toughness. At this time, JP-A-3-1503
As disclosed in Japanese Patent Publication No. 43-43, after casting a cast iron pipe, Al or A containing Al as a main component is formed on the outer peripheral surface of the cast iron pipe.
It has been practiced to deposit an alloy film of l-alloy and form an anticorrosion film of aluminum oxide on the outer peripheral surface thereof during annealing heat treatment.
【０００３】[0003]
【発明が解決しようとする課題】叙上の方法により、鋳
鉄管の外周面に酸化アルミニウムの防食被膜が形成され
るため、酸化スケールの発生を防止することができ、ま
た防食塗装を省略することができた。しかしながら、前
記方法により形成された防食被膜はその膜厚が薄いた
め、耐食性が十分とは言えないのが実情である。The above method forms an anticorrosion coating of aluminum oxide on the outer peripheral surface of the cast iron pipe, so that it is possible to prevent the generation of oxide scale and to omit anticorrosion coating. I was able to. However, since the anticorrosion coating formed by the above method has a small thickness, it cannot be said that the corrosion resistance is sufficient.
【０００４】本発明はかかる問題に鑑みなされたもの
で、従来に比して膜厚の厚い防食被膜を形成することが
できる外面耐食鋳鉄管の製造方法を提供することを目的
とする。The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing an outer surface corrosion-resistant cast iron pipe capable of forming an anticorrosion coating having a thicker film thickness than conventional ones.
【０００５】[0005]
【課題を解決するための手段】本発明の外面耐食鋳鉄管
の製造方法は、鋳鉄管を鋳造した後、該鋳鉄管の外周面
にＡｌ又はＡｌを主成分とするＡｌ合金の被膜を被着
し、焼鈍熱処理を施して鋳鉄管を焼鈍すると共にその外
周面に酸化アルミニウムの防食被膜を形成するにおい
て、焼鈍熱処理後に鋳鉄管を高温の水蒸気中で保持し、
鋳鉄管の外周面に水蒸気との反応により酸化アルミニウ
ム被膜を生成させる。高温の水蒸気中で保持するに際し
ては、焼鈍後に鋳鉄管の外表面に付着した酸化アルミニ
ウムの粉末状のかすを除去するとよい。According to the method of manufacturing an outer surface corrosion-resistant cast iron pipe of the present invention, after casting a cast iron pipe, a coating film of Al or an Al alloy containing Al as a main component is deposited on the outer peripheral surface of the cast iron pipe. Then, in forming an aluminum oxide anticorrosion coating on the outer peripheral surface while annealing the cast iron pipe by performing the annealing heat treatment, the cast iron pipe is held in high temperature steam after the annealing heat treatment,
An aluminum oxide film is formed on the outer peripheral surface of the cast iron pipe by reaction with water vapor. When holding in high temperature steam, it is advisable to remove the powdery residue of aluminum oxide adhering to the outer surface of the cast iron pipe after annealing.
【０００６】[0006]
【作用】鋳鉄管の外表面に被着された、Ａｌ又はＡｌを
主成分とするＡｌ合金の被膜は焼鈍中に溶融し、Ａｌが
管の表面から管壁内に拡散すると共に溶融Ａｌの表面が
酸化する。焼鈍の終期には、管壁の表面部にＡｌの拡散
によるＦｅ−Ａｌ合金層が形成され、その上にＡｌ2 Ｏ
3 の不動態被膜が密着形成され、更にその上に粉末状の
Ａｌ2 Ｏ3 が付着した状態になる。前記不動態被膜は薄
く、膜厚も不均一になりやすい。次に、かかる鋳鉄管を
高温の水蒸気中で保持すると、水蒸気との反応によりＦ
ｅ−Ａｌ合金層の表面からＡｌ2 Ｏ3 又は水和Ａｌ2 Ｏ
3 が生成、焼鈍時に生成したＡｌ2 Ｏ3 被膜と相まっ
て、厚いＡｌ2 Ｏ3 の不動態被膜が形成される。水蒸気
中で保持するに際して、管表面に付着した粉末状のＡｌ
2 Ｏ3を、例えばウォータージェットで管表面を洗浄
し、除去することにより、Ａｌ2Ｏ3 の生成反応が促進
される。The coating of Al or an Al alloy containing Al as a main component, which is deposited on the outer surface of the cast iron pipe, melts during annealing, and Al diffuses from the surface of the pipe into the wall of the pipe and the surface of the molten Al. Oxidizes. At the end of the annealing, a Fe-Al alloy layer is formed by diffusion of Al on the surface of the tube wall, and Al 2 O is formed thereon.
The passivation film of No. 3 is formed in close contact, and powdered Al 2 O 3 is further adhered on it. The passivation film is thin and the film thickness tends to be non-uniform. Next, when the cast iron pipe is held in high temperature steam, F
From the surface of the e-Al alloy layer, Al 2 O 3 or hydrated Al 2 O
A thick Al 2 O 3 passivation film is formed in combination with the Al 2 O 3 film formed during the annealing and 3 formation. Powdery Al adhered to the surface of the pipe when held in steam
The reaction of forming Al 2 O 3 is promoted by cleaning the surface of the tube with 2 O 3 , for example, with a water jet and removing it.
【０００７】[0007]
【実施例】本発明を実施するには、先ず、適宜の鋳造法
で鋳造された鋳鉄管の外周面に、Ａｌ又はＡｌを主成分
とするＡｌ合金（以下、単にＡｌという。）の被膜を被
着する。鋳造法としては、例えば、遠心力鋳造を適用す
ることができる。Ａｌを主成分とするＡｌ合金として
は、Ａｌを９０wt％以上含有するものがよい。Ａｌ被膜
の被着手段としては、例えば、溶射を適用することがで
きる。Ａｌ被膜の被着量は、６０〜２００ｇ／ｍ2 程度
でよい。EXAMPLE To carry out the present invention, first, a coating film of Al or an Al alloy containing Al as a main component (hereinafter, simply referred to as Al) is formed on the outer peripheral surface of a cast iron pipe cast by an appropriate casting method. Put on. As the casting method, for example, centrifugal casting can be applied. As the Al alloy containing Al as a main component, one containing 90 wt% or more of Al is preferable. As a means for depositing the Al coating, for example, thermal spraying can be applied. The coating amount of the Al coating may be about 60 to 200 g / m 2 .
【０００８】次に、Ａｌ被膜が被着された鋳鉄管を焼鈍
炉に装入して、通常のフェライト化焼鈍条件すなわち８
００〜９００℃程度の温度で１〜２ｈｒ程度保持する。
これにより、鋳鉄管の母材の基地がフェライト化される
と共に、図１に示すように、管壁１の表面部にＡｌ拡散
層であるＦｅ−Ａｌ合金層２が形成され、その上にＡｌ
2 Ｏ3 の不動態被膜３が密着形成され、更にその上に粉
末状のＡｌ2 Ｏ3 ４が付着した状態になる。Next, the cast iron pipe coated with the Al coating is placed in an annealing furnace and subjected to normal ferritic annealing conditions, that is, 8
Hold at a temperature of about 00 to 900 ° C. for about 1 to 2 hours.
As a result, the matrix of the base material of the cast iron pipe is made ferrite, and as shown in FIG. 1, the Fe-Al alloy layer 2 which is an Al diffusion layer is formed on the surface portion of the pipe wall 1, and the Al-Al alloy layer 2 is formed thereon.
The passivation film 3 of 2 O 3 is formed in close contact, and powdery Al 2 O 3 4 is further adhered thereon.
【０００９】焼鈍後、例えばウォータージェットで管表
面を洗浄することにより粉末状のＡｌ2 Ｏ3 ４を除去す
る。かかる工程は必要に応じて行えばよいが、好ましく
は実施した方がよい。その後、高温の水蒸気中で保持す
る。これにより、図２に示すように、Ｆｅ−Ａｌ合金層
２の表面と水蒸気とが反応し、Ｆｅ−Ａｌ合金層２の表
面からＡｌ2Ｏ3 又は水和Ａｌ2 Ｏ3 が生成、成長し、
焼鈍時のＡｌ2 Ｏ3 と水蒸気処理により生成したＡｌ2
Ｏ3 とからなる厚いＡｌ2 Ｏ3 不動態被膜５が形成され
る。水蒸気の温度としては、１００℃以上であればよ
く、通常１００〜３００℃に設定される。保持時間は、
目的とする不動態被膜の膜厚によるが、５〜３０分程度
で十分である。After the annealing, the powdery Al 2 O 3 4 is removed by washing the surface of the tube with, for example, a water jet. Although such a step may be performed as necessary, it is preferably performed. Then, it hold | maintains in high temperature steam. As a result, as shown in FIG. 2, the surface of the Fe—Al alloy layer 2 reacts with water vapor, and Al 2 O 3 or hydrated Al 2 O 3 is generated and grown from the surface of the Fe—Al alloy layer 2. ,
Al 2 produced by Al 2 O 3 and steam treatment in annealing
Thick Al 2 O 3 passivating film 5 consisting of O 3 Metropolitan is formed. The temperature of the steam may be 100 ° C. or higher, and is usually set to 100 to 300 ° C. The retention time is
Depending on the desired thickness of the passivation film, about 5 to 30 minutes is sufficient.
【００１０】次に具体的実施例を掲げる。遠心力鋳造し
た後の未焼鈍管の外周面にＡｌを１３０ｇ／ｍ2 溶射し
た後、該鋳造管を焼鈍炉に装入して、９５０℃で１．５
時間保持した。その後、ウォータージェットで管表面を
洗浄し、２５０℃の水蒸気中で１５分間保持し、Ａｌ2
Ｏ 3 を生成させた。該鋳造管（実施例）と、水蒸気中で
の保持を除き、他は実施例と同条件で製造した鋳造管
（従来例）とを用いて自然電位を測定したところ、実施
例は従来例に比して約９５ｍＶ高く、耐食性に優れるこ
とが確認された。また、ＥＰＭＡにより管表面の酸素を
分析したところ、酸素カウント数は実施例が従来例に比
して５〜７倍であり、Ａｌ2 Ｏ3 の多量の存在が確認さ
れた。Next, specific examples will be given. Centrifugal casting
130g / m of Al on the outer surface of the unannealed tube after2Sprayed
After that, the casting tube is charged into an annealing furnace and heated at 950 ° C. for 1.5
Held for hours. After that, use a water jet to clean the surface of the pipe.
Clean and hold in steam at 250 ° C for 15 minutes to remove Al2
O 3Was generated. In the cast pipe (Example) and steam
Casting pipes manufactured under the same conditions as in the other examples except that
When the spontaneous potential was measured using (conventional example) and
The example is about 95 mV higher than the conventional example and has excellent corrosion resistance.
Was confirmed. Also, the oxygen on the tube surface is removed by EPMA.
As a result of analysis, the oxygen count was higher in the example than in the conventional example.
5 to 7 times, and Al2O3Confirmed the existence of a large amount of
It was
【００１１】[0011]
【発明の効果】以上説明した通り、本発明の製造方法に
よると、焼鈍熱処理後に鋳鉄管を高温の水蒸気中で保持
するので、管表面に焼鈍時に生じたＡｌ2 Ｏ3 膜のみな
らず、焼鈍により生じたＦｅ−Ａｌ合金層からＡｌ2 Ｏ
3 膜が生成し、管表面に厚いＡｌ2 Ｏ3 不動態被膜から
なる防食被膜が形成される。As described above, according to the manufacturing method of the present invention, since the cast iron pipe is held in the high temperature steam after the annealing heat treatment, not only the Al 2 O 3 film formed during annealing on the pipe surface but also the annealing is performed. From the Fe-Al alloy layer generated by Al 2 O
Three films are formed, and an anticorrosion film consisting of a thick Al 2 O 3 passivation film is formed on the tube surface.
【図１】焼鈍後の鋳鉄管の管壁の断面模式図である。FIG. 1 is a schematic sectional view of a pipe wall of a cast iron pipe after annealing.
【図２】高温水蒸気中に保持後の管壁の断面模式図であ
る。FIG. 2 is a schematic cross-sectional view of a tube wall after being held in high temperature steam.
１ 管壁 ２ Ｆｅ−Ａｌ合金層 ３ Ａｌ2 Ｏ3 不動態被膜 ４ 粉末状Ａｌ2 Ｏ3 ５ Ａｌ2 Ｏ3 不動態被膜1 Pipe Wall 2 Fe-Al Alloy Layer 3 Al 2 O 3 Passive Film 4 Powdery Al 2 O 3 5 Al 2 O 3 Passive Film
Claims (2)
にＡｌ又はＡｌを主成分とするＡｌ合金の被膜を被着
し、焼鈍熱処理を施して鋳鉄管を焼鈍すると共にその外
周面に酸化アルミニウムの防食被膜を形成する外面耐食
鋳鉄管の製造方法において、 焼鈍熱処理後に鋳鉄管を高温の水蒸気中で保持し、鋳鉄
管の外周面に水蒸気との反応により酸化アルミニウム被
膜を生成させることを特徴とする外面耐食鋳鉄管の製造
方法。1. After casting a cast iron pipe, a coating film of Al or an Al alloy containing Al as a main component is applied to the outer peripheral surface of the cast iron pipe and annealed and heat treated to anneal the cast iron pipe and its outer peripheral surface. In the manufacturing method of the outer surface corrosion-resistant cast iron pipe that forms the aluminum oxide anticorrosion coating on the outer surface of the cast iron pipe, hold the cast iron pipe in high temperature steam after annealing heat treatment, and form the aluminum oxide film on the outer peripheral surface of the cast iron pipe by the reaction with steam. A method for manufacturing an outer surface corrosion-resistant cast iron pipe characterized by:
アルミニウムの粉末状のかすを除去した後、該鋳鉄管を
高温の水蒸気中で保持する請求項１に記載した外面耐食
鋳鉄管の製造方法。2. The production of an outer corrosion-resistant cast iron pipe according to claim 1, wherein after removing the powdery residue of aluminum oxide adhering to the outer surface of the cast iron pipe after annealing, the cast iron pipe is held in high temperature steam. Method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17125594A JP2951541B2 (en) | 1994-07-22 | 1994-07-22 | Manufacturing method of external corrosion resistant cast iron pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17125594A JP2951541B2 (en) | 1994-07-22 | 1994-07-22 | Manufacturing method of external corrosion resistant cast iron pipe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0835052A true JPH0835052A (en) | 1996-02-06 |
| JP2951541B2 JP2951541B2 (en) | 1999-09-20 |
Family
ID=15919938
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17125594A Expired - Fee Related JP2951541B2 (en) | 1994-07-22 | 1994-07-22 | Manufacturing method of external corrosion resistant cast iron pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2951541B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017165031A1 (en) * | 2016-03-23 | 2017-09-28 | Applied Materials, Inc. | Alumina layer formation on aluminum surface to protect aluminum parts |
-
1994
- 1994-07-22 JP JP17125594A patent/JP2951541B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017165031A1 (en) * | 2016-03-23 | 2017-09-28 | Applied Materials, Inc. | Alumina layer formation on aluminum surface to protect aluminum parts |
| US10711350B2 (en) | 2016-03-23 | 2020-07-14 | Applied Materical, Inc. | Alumina layer formation on aluminum surface to protect aluminum parts |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2951541B2 (en) | 1999-09-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |