Zn-Al-Mg composite anticorrosive coating and manufacturing method thereof for cast-iron pipelines

An anti-corrosion coating, zinc-aluminum-magnesium technology, applied in pipeline anti-corrosion/rust protection, coating, pipeline protection, etc., can solve the problem of weakening the self-healing performance of corrosion products, long-term protection of cast iron pipelines, and coating anti-corrosion life Shortening and other issues, to achieve the effect of shortening the research and development cycle, reducing research and development costs, and easy implementation

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

AI Technical Summary

Problems solved by technology

[0002] Zinc coating, aluminum coating, zinc-aluminum alloy coating and zinc-aluminum pseudo-alloy coating are traditional thermal spray coatings. Although zinc coating has good dynamic electrochemical protection performance, on the one hand, the porosity of zinc coating On the other hand, in offshore environment or other high chlorine environment, zinc coating corrosion products (ie zinc oxide, basic zinc hydroxide and basic carbonate, etc.) are easy to form loose and soluble Strong chloride salt compounds greatly weaken the self-healing properties of corrosion products, and at the same time, the coating bubbles and the adhesion decreases, resulting in shortened coating anti-corrosion life
Aluminum coating has higher hardness and better erosion resistance than zinc coating, but it is easy to form Al 2 o 3 Oxide film, its electrode potential is higher than that of the base cast iron, so its electrochemical protection function is far inferior to that of zinc coating, and it is prone to pitting corrosion, so it is not suitable for highly corrosive environments
Although the Zn-Al alloy coating or Zn-Al pseudo-alloy coating reduces the porosity of the coating to a certain extent, its corrosion products have a greater self-sealing effect on the pores in the coating than pure zinc coatings and pure aluminum coatings. However, since there are only Zn and Al elements in the coating, the corrosion products of the coating are still easy to form loose and water-soluble chloride salt compounds in the marine environment, which cannot form long-term protection for cast iron pipelines.

Method used

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  • Zn-Al-Mg composite anticorrosive coating and manufacturing method thereof for cast-iron pipelines

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0051] (1) Pipe surface treatment

[0052] Surface preparation of cast iron pipes and / or fittings prior to thermal spraying to remove scale, oil, water, dust and / or any other impurities.

[0053] (2) Arc spraying alloy coating

[0054] Arc thermal spraying equipment composed of high-power spraying power supply, spraying gun, wire feeding mechanism, air compressor, and control box is selected, and two φ4.0mm 95Zn-4.8Al-0.2Mg alloy wires are used as cast iron for arc thermal spraying Silk, according to 130g / m 2 Spray on the surface of the pipeline to form a zinc-aluminum-magnesium multi-alloy coating. The coating weight composition: Zn 97%, Al 2.8%, Mg 0.2%.

[0055] (3) Coating the sealing finish coating

[0056] Coating epoxy resin on the surface of the multi-component alloy layer to seal the alloy layer, the thickness of the final sealing layer is 110 μm.

[0057] Alloy coating performance test: adhesion 10Mpa, porosity 2.0%, no red rust appears after immersion in salt wa...

Embodiment 2

[0059] (1) Pipe surface treatment

[0060] Surface preparation of cast iron pipes and / or fittings prior to thermal spraying to remove scale, oil, water, dust and / or any other impurities.

[0061] (2) Arc spraying alloy coating

[0062] Arc thermal spraying equipment composed of high-power spraying power supply, spraying gun, wire feeding mechanism, air compressor and control box is selected, and two φ3.0mm 90Zn-9.2Al-0.8Mg alloy wires are used as cast iron wires for arc thermal spraying Material, according to 150g / m 2 Spray on the surface of the pipeline to form a zinc-aluminum-magnesium multi-alloy coating. Coating weight composition: Zn 90%, Al 9.5%, Mg 0.5%.

[0063] (3) Coating the sealing finish coating

[0064] On the surface of the multi-component alloy layer, high-pressure airless spraying asphalt is used to seal the alloy layer, and the thickness of the sealing final layer is 100 μm.

[0065] Alloy coating performance test: adhesion is 10.45Mpa, porosity is 2.25%...

Embodiment 3

[0067] (1) Pipe surface treatment

[0068] Surface preparation of cast iron pipes and / or fittings prior to thermal spraying to remove scale, oil, water, dust and / or any other impurities.

[0069] (2) Arc spraying alloy coating

[0070] The arc thermal spraying equipment composed of high-power spraying power supply, spraying gun, wire feeding mechanism, air compressor and control box is selected, and two φ2.5mm 97Zn-2.0Al-1.0Mg alloy wires are used as arc thermal spraying Cast iron wire, according to 200g / m 2 Spray on the surface of the pipeline to form a zinc-aluminum-magnesium multi-alloy coating. Coating weight composition: Zn 96%, Al 2.0%, Mg 2.0%.

[0071] (3) Coating the sealing finish coating

[0072] The surface of the multi-element alloy layer is coated with acrylic resin to seal the alloy layer, and the thickness of the final sealing layer is 130 μm.

[0073] Alloy coating performance test: Adhesion 10.0Mpa, porosity 2.5%, no red rust after soaking in salt water ...

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Abstract

The invention discloses a Zn-Al-Mg composite anticorrosive coating and a manufacturing method thereof for cast-iron pipelines and relates to the technical field of corrosion prevention technology for metal materials. The Zn-Al-Mg composite anticorrosive coating comprises a Zn-Al-Mg alloy or Zn-Al-Mg pseudo alloy, and is characterized in that the Zn-Al-Mg alloy comprises, by weight, 90-97% of Zn, 2.0-9.5% of Al, 0.2-2.0% of Mg; the Zn-Al-Mg pseudo alloy comprises, by weight, 50-70% of Zn, 28-50% of Al and 1.5-5.0% of Mg; the Zn-Al-Mg alloy or Zn-Al-Mg pseudo alloy is prepared by electric arc spraying. The Zn-Al-Mg is mainly used for corrosion prevention for outer surfaces of the cast-iron pipelines and / or pipe fittings. The anticorrosive coating has advantages of high adhesion, low porosity, excellent corrosion resistance and low cost; the manufacturing method is simple, easy to operate and wide in material sources; therefore, economical benefit is good.

Description

technical field [0001] The invention relates to the technical field of anticorrosion of metal materials, in particular to a zinc-aluminum-magnesium composite anticorrosion coating for cast iron pipelines and a preparation method thereof. Background technique [0002] Zinc coating, aluminum coating, zinc-aluminum alloy coating and zinc-aluminum pseudo-alloy coating are traditional thermal spray coatings. Although zinc coating has good dynamic electrochemical protection performance, on the one hand, the porosity of zinc coating On the other hand, in offshore environment or other high chlorine environment, zinc coating corrosion products (ie zinc oxide, basic zinc hydroxide and basic carbonate, etc.) are easy to form loose and soluble Strong chloride salt compounds greatly weaken the self-healing performance of corrosion products, and at the same time, the coating is bubbling and the adhesion is reduced, resulting in a shortened coating anti-corrosion life. Aluminum coating ha...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F16L58/08C23C4/08C23C4/16C22C18/04C23C4/131
Inventor 李军宋延琦王恩清周波张永杰李海顺信绍广綦晓平张明戚广宇张三辉赵文良
Owner XINXING DUCTILE IRON PIPES CO LTD
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