Iron-based pipe comprising anticorrosive coating

An anti-corrosion coating and pipeline technology, applied in the field of anti-corrosion coating of iron-based pipelines, pipelines and coatings, ductile iron pipelines and pipe fittings, can solve the problems of weakening anti-corrosion performance, reducing coating adhesion, shortening anti-corrosion life, etc. Achieve the effect of reducing coating porosity, reducing surface active points, and reducing corrosion channels

Active Publication Date: 2013-10-30
XINXING DUCTILE IRON PIPES CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] At present, Zn coating is the most widely used thermal spray coating for buried earth graphite cast iron pipes and pipe fittings. Although Zn coating has good dynamic electrochemical protection performance, on the one hand, the high porosity of Zn coating weakens its On the other hand, in the normal atmospheric environment, the corrosion products of Zn coating are mainly composed of zinc oxide, basic zinc hydroxide and basic carbonate which are difficult to dissolve in water. Such corrosion products have certain self-sealing properties. ability to block the intrusion of corrosive media such as moisture, but in environments with high content of seawater or chloride ions, due to the intrusion of chloride ions, corrosion products such as carbonates that are difficult to dissolve in water on the surface of the Zn coating are quickly loosened and easily Displaced by dissolved chloride salt compounds, greatly weakening the self-healing properties of corrosion products, this reaction has a faster kinetic process
The easy solubility of corrosion products

Method used

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  • Iron-based pipe comprising anticorrosive coating
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  • Iron-based pipe comprising anticorrosive coating

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] 1. Spray ZnAlLaCe alloy layer

[0048] Spraying wire type: two ZnAlLaCe alloy wires are used, and the diameter of the alloy wire is 4.0mm.

[0049] By arc spraying, ZnAlLaCe alloy wire is used to deposit ZnAlLaCe alloy coating on the ductile iron pipe substrate. The composition content of each element of the coating is: Al: 14.9%, La+Ce: 0.1%, and the rest is Zn.

[0050] 2. Coating the sealing layer

[0051] Spray the sealing layer with epoxy resin paint, and the coating thickness is 150 microns.

[0052] (1) Adhesion test results

[0053] Table 1 Adhesion of pure zinc coating, zinc-aluminum alloy coating, zinc-aluminum rare earth alloy coating

[0054] type

[0055]

[0056] It can be seen from Table 1 that the adhesion of zinc-aluminum rare earth alloy coating is significantly higher than that of pure zinc coating and zinc-aluminum alloy coating.

[0057] (2) Porosity test results

[0058] Table 2 Porosity of pure zinc coating, zinc-aluminum...

Embodiment 2

[0085] The content of the alloy layer is: Al: 21.9%, La+Ce: 0.1%, the rest is Zn, and the rest is the same as in Example 1.

[0086] (1) Adhesion test results

[0087] Table 8 Adhesion of pure zinc coating, zinc-aluminum alloy coating, zinc-aluminum rare earth alloy coating

[0088]

[0089] It can be seen from Table 8 that the adhesion of zinc-aluminum rare earth alloy coating is higher than that of pure zinc coating and zinc-aluminum alloy coating.

[0090] (2) Porosity test results

[0091] The porosity of table 9 pure zinc coating, zinc-aluminum alloy coating, zinc-aluminum rare earth alloy coating

[0092]

[0093] It can be seen from Table 9 that the porosity of zinc-aluminum rare-earth alloy coating is significantly lower than that of pure zinc coating and zinc-aluminum alloy coating, which is more conducive to preventing external corrosive media from contacting the metal substrate, thereby improving the corrosion resistance of the coating.

[0094] (3) The ini...

Embodiment 3

[0116] 1. Spray ZnAlLa alloy layer

[0117] Spraying wire type: two ZnAlLa alloy wires are used, and the diameter of the alloy wire is 2.0mm.

[0118] By arc spraying, ZnAlLa alloy wire is used to deposit ZnAlLa alloy coating on the ductile iron pipe substrate. The composition content of each element of the coating is: Al: 4.7%, La: 0.3%, and the rest is Zn.

[0119] 2. Coating the sealing layer

[0120] The sealing layer is sprayed with epoxy resin paint, and the thickness of the coating is 60 microns.

[0121] (1) Adhesion test results

[0122] Table 15 Adhesion of pure zinc coating, zinc aluminum alloy coating, zinc aluminum rare earth alloy coating

[0123]

[0124] It can be seen from Table 15 that the adhesion of zinc-aluminum rare earth alloy coating is higher than that of pure zinc coating and zinc-aluminum alloy coating.

[0125] (2) Porosity test results

[0126] The porosity of table 16 pure zinc coating, zinc-aluminum alloy coating, zinc-aluminum rare earth...

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Abstract

The invention discloses an anticorrosive coating of a nodular cast iron pipe fitting and a nodular cast iron pipe comprising the coating. The anticorrosive coating comprises a ZnAlRE alloy layer and a hole sealing layer, the ZnAlRE alloy layer comprises, by weight, 4.7-60% of Al, 0.02%-5% of RE and the balance Zn, porosity of the coating is 1.0-2.0%, Ecorr is -1.26--1.17V, and Icorr is 1.0-1.1x10<-5>A.cm<2>. The anticorrosive coating and the nodular cast iron pipe have the advantages of environmental protection, low alloy consumption, high corrosion resistance and the like.

Description

technical field [0001] The invention relates to a pipeline and a coating, in particular to an iron-based pipeline, especially to the field of external anti-corrosion of ductile iron pipelines, in particular to an anticorrosion coating for ductile iron pipelines and pipe fittings. Background technique [0002] At present, Zn coating is the most widely used thermal spray coating for buried earth graphite cast iron pipes and pipe fittings. Although Zn coating has good dynamic electrochemical protection performance, on the one hand, the high porosity of Zn coating weakens its On the other hand, in the normal atmospheric environment, the corrosion products of Zn coating are mainly composed of zinc oxide, basic zinc hydroxide and basic carbonate which are difficult to dissolve in water. Such corrosion products have certain self-sealing properties. ability to block the intrusion of corrosive media such as moisture, but in environments with high content of seawater or chloride ions,...

Claims

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Application Information

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IPC IPC(8): F16L58/08C22C18/04
Inventor 李军王恩清信绍广张永杰李海顺綦晓平戚广宇张明张三辉赵文良
Owner XINXING DUCTILE IRON PIPES CO LTD
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