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Pipe provided with corrosion prevention layer on the outside surface, process for production of the same, and process for production of alloy wires used for the corrosion prevention layer

a corrosion prevention layer and pipe technology, applied in the direction of coatings, mechanical devices, transportation and packaging, etc., can solve the problems of hardly maintaining the sacrificial anode function of zinc, the corrosion of metal pipes progressing from the scratched portions, and the corrosion of metal pipes with a high ionization tendency, so as to achieve the effect of improving corrosion prevention performance, reducing the number of work, and improving corrosion prevention performan

Inactive Publication Date: 2014-08-21
KUBOTA CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a pipe with a corrosion prevention layer that includes a Zn—Sn alloy sprayed coating or a Zn—Sn—Mg alloy sprayed coating. These coatings greatly improve the corrosion prevention performance compared to a pipe using a simple zinc sprayed coating and do not use Al, which avoids health concerns. The alloy sprayed coating includes at least one of Ti, Co, Ni, and P in a predetermined content, and / or heat treated at a temperature equal to or higher than the eutectic temperature of the alloy and lower than the melting point of the alloy, which further improves the corrosion prevention performance. The use of a molten Zn—Sn—Mg alloy under solidification results in refined zinc crystals and improved mechanical properties of the alloy wire. This production method also allows for the creation of a hard-to-break wire, suitable for wiredrawing.

Problems solved by technology

When the coating of a metal pipe is scratched, however, the corrosion of the metal pipe progresses from the scratched portions.
However, zinc has a high ionization tendency, and hence zinc hardly maintains the sacrificial anode function over a long period of time.
However, in this case, in addition to the increase of the material cost, the work time is increased and the production efficiency is also degraded.
However, as for aluminum, health concern is raised from some viewpoints, and the safety of aluminum as a material applied to drink water supply pipes is not established.
For example, in a pipe joint having an inserting-receiving structure in which the inside of a socket formed at one end of a pipe receives a spigot formed at one end of another pipe, the outer surface of the spigot is brought into contact with tap water, thus causing a possibility that aluminum is eluted from the outer surface of the spigot.

Method used

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  • Pipe provided with corrosion prevention layer on the outside surface, process for production of the same, and process for production of alloy wires used for the corrosion prevention layer
  • Pipe provided with corrosion prevention layer on the outside surface, process for production of the same, and process for production of alloy wires used for the corrosion prevention layer
  • Pipe provided with corrosion prevention layer on the outside surface, process for production of the same, and process for production of alloy wires used for the corrosion prevention layer

Examples

Experimental program
Comparison scheme
Effect test

examples

[0057]Hereinafter, Examples of the present invention are described. It is to be noted that in following Examples, Comparative Examples, the evaluations of various physical properties were performed as follows.

[0058](1) Workability into Wire

[0059]An alloy ingot of 47 mm in diameter X 350 mm in length was prepared and the workability into wire was evaluated by measuring the Vickers hardness. The alloy ingot after the hardness measurement was forged so as to have a reduced diameter of 10 mm and further wiredrawn so as to have a diameter of 1.6 mm, and thus the workability was evaluated on the basis of the following standards.

[0060]G (Good): Wiredrawing can be performed to a diameter of 1.6 mm.

[0061]P (Poor): Breakage occurs during wiredrawing.

[0062](2) Corrosion Resistance

[0063]A corrosion resistance test was performed in the following manner. Specifically, a 150 mm×70 mm×2 mm sand-blast steel plate was used as a specimen. On this plate, a 20 to 30-μm thick sprayed coating was formed a...

examples 43 to 53

[0087]As shown in Table 4, in each of Examples 43 to 53, a Zn—Sn—Mg wire was used as a first wire and a Zn wire was used as a second wire, and simultaneously the first wire and the second wire were arc sprayed. The results thus obtained are shown in Table 4. In this tabular presentation, in the same manner as in above-described Examples, in each of Examples 43 to 53, when Ti, Co, Ni and P were added and the salt spray test was performed, in any of the cases in which any one of Ti, Co, Ni and P was singly added, the same evaluation results were obtained, by varying the addition amount, on the time periods until red rust occurred. Therefore, also in Table 4, for simplicity, only one typical example is shown for each of Examples 43 to 53.

TABLE 4Components(% by mass)ZnSnMgSpray conditionsHardness (Hv)Workability into wireEx. 43Balance20.02Zn—4Sn—0.04Mg wire and Zn——wireEx. 44Balance23.00Zn—4Sn—6.0Mg wire——and Zn wireEx. 45Balance100.02Zn—20Sn—0.04Mg——wire and Zn wireEx. 46Balance103.00Z...

example 54

[0104]Hereinafter, an example of the process for production of an alloy wire of the present invention is described.

[0105]By using an apparatus shown in FIG. 1, under the below-described conditions, an alloy wire 105 in which crystals were refined, the ductility thereof was improved and the diameter thereof was 10 mm was obtained. Then, the alloy wire 105 was worked into an alloy wire having a diameter of 1.6 mm with a not-shown wiredrawing machine.

[0106]Specifically, in the above-described production process, the timing of spraying cooling water was altered and quenching was performed. More specifically, as shown in Table 5, the timing of spraying cooling water (hereinafter, referred to as “water cooling timing”) was varied, and thus the specimens 1 to 4 were produced.

[0107]In other words, Zn, Sn and Mg were melted at 450° C., and these molten materials were mixed in such a way that the content of Sn was 30% by mass, the content of Mg was 0.3% by mass and the balance was composed of...

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Abstract

Disclosed is a pipe made of an iron-base material, having a corrosion prevention layer formed on the surface thereof. The corrosion prevention layer includes a Zn—Sn sprayed coating including Sn in a content of more than 1% by mass and less than 50% by mass and the balance composed of Zn. Alternatively, the corrosion prevention layer includes a Zn—Sn—Mg sprayed coating including Sn in a content of more than 1% by mass and less than 50% by mass, Mg in a content of more than 0.01% by mass and less than 5% by mass and the balance composed of Zn. Preferably, the sprayed coating of the corrosion prevention layer includes at least any one of Ti, Co, Ni and P, and the content of each of these elements is more than 0.001% by mass and less than 3% by mass.

Description

RELATED APPLICATIONS[0001]This application is a divisional of U.S. application Ser. No. 12 / 733,569, filed Mar. 9, 2010, which is a U.S. National Stage Application of International Application No. PCT / JP09 / 01193, filed Mar. 18, 2009, which claims priority from Japanese Patent Application No. 2008-074781, filed Mar. 24, 2008 and Japanese Patent Application No. 2008-136141, filed May 26, 2008; said patent applications hereby fully incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates to a pipe provided with a corrosion prevention layer on the outside surface thereof, a process for production of the pipe and a process for production of alloy wires used for the corrosion prevention layer, in particular, a pipe provided with a corrosion prevention layer on the outside surface thereof wherein the corrosion prevention layer is formed with a metal sprayed coating on the surface of the pipe made of an iron-base material, such as a cast-iron pipe, a process for pr...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22C18/00
CPCC22C18/00B22D11/0611B32B15/013C23C4/04C23C4/08C23C4/131C23C4/123B22D11/005Y10T428/12799F16L9/02
Inventor SHIMIZU, HIROAKIFUNAHASHI, GOROFUJII, HIROAKI
Owner KUBOTA CORP
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