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A surface pretreatment method for improving the quality of hot dip galvanized coating of malleable cast iron

A surface pretreatment, hot-dip galvanizing technology, applied in hot-dip galvanizing process, coating, metal material coating process, etc. Effects of improved coating uniformity and reduced thickness of galvanized layer

Active Publication Date: 2022-08-02
CHANGZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

On the contrary, a higher galvanizing temperature should be used. At this time, the zinc-iron reaction is intensified, the iron content in the galvanizing solution increases, and zinc slag is formed, which increases the viscosity of the galvanizing solution, and the fluidity of the alloy solution is significantly reduced. Thick zinc layer

Method used

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  • A surface pretreatment method for improving the quality of hot dip galvanized coating of malleable cast iron
  • A surface pretreatment method for improving the quality of hot dip galvanized coating of malleable cast iron
  • A surface pretreatment method for improving the quality of hot dip galvanized coating of malleable cast iron

Examples

Experimental program
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Effect test

Embodiment 1

[0028] A malleable cast iron sample with a size of 10mm × 10mm × 4mm was embedded in a sodium bicarbonate powder bed, and the surface was pretreated at 200 ° C for 60 minutes. -Dry treatment, and then immerse the malleable cast iron sample in a zinc alloy solution for 4 minutes. The composition of the hot-dip galvanized alloy solution is also Zn-0.05wt.%Al, and the temperature of the zinc alloy solution is controlled at 460°C. The thickness measurement results of malleable cast iron coating before and after 200 ℃ sodium bicarbonate pretreatment for 60 minutes are shown in Table 1. Quantitative metallographic analysis showed that the average thickness of the malleable iron coating was 86.5 μm, which was 15.2% less than the average thickness of the coating of the unpretreated samples. The difference in coating thickness between the thickest part and the thinnest part is 118.4 μm, which is 20.3% less than that between the thickest part and the thinnest part of the unpretreated sa...

Embodiment 2

[0032] A malleable cast iron sample with a size of 10mm × 10mm × 4mm was embedded in the sodium bicarbonate powder bed, and the surface was pretreated at 300 ° C for 60 minutes. -Dry a series of treatments, zinc alloy solution and then immerse malleable cast iron samples in zinc alloy solution for 4 minutes. The composition of hot-dip galvanizing solution is also Zn-0.05wt.%Al, and the temperature of zinc alloy solution is controlled at 460℃. The thickness measurement results of malleable cast iron coating before and after 300 ℃ sodium bicarbonate pretreatment for 60 minutes are shown in Table 2. Quantitative metallographic analysis showed that the average thickness of the malleable iron coating was 76.1 μm, which was 25.4% less than that of the non-pretreated samples. The thickness difference between the thickest part and the thinnest part is 71.8 μm, which is 51.7% less than that between the thickest part and the thinnest part of the unpretreated sample, and the coating unif...

Embodiment 3

[0036] A malleable cast iron sample with a size of 10mm × 10mm × 3mm was embedded in a sodium bicarbonate powder bed, and the surface was pretreated at 400 ° C for 60 minutes. -Dry a series of zinc alloy solutions, and then immerse malleable cast iron samples in zinc alloy solution for 4 minutes. The composition of hot-dip galvanizing solution is Zn-0.05wt.%Al, and the temperature of zinc alloy solution is controlled at 460℃. The thickness measurement results of malleable cast iron coating before and after 400 ℃ sodium bicarbonate pretreatment for 60 minutes are shown in Table 3. Quantitative metallographic analysis showed that the average thickness of the malleable cast iron coating was 81.3 μm, which was 20.3% less than the average thickness of the coating of the unpretreated samples. The difference in coating thickness between the thickest part and the thinnest part is 61.2 μm, which is 58.9% less than that between the thickest part and the thinnest part of the untreated sa...

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Abstract

The invention belongs to the field of metal surface engineering, and particularly relates to a surface pretreatment method for improving the quality of hot-dip galvanized coating of malleable cast iron. The present invention mainly embeds the malleable cast iron in the sodium bicarbonate powder bed, makes the malleable cast iron place in an oxidizing atmosphere for surface oxidation pretreatment, and achieves the purpose of effectively inhibiting the activity of silicon on the surface of the cast iron. Compared with unpretreated malleable cast iron, the difference of coating thickness and its average thickness in different parts of pretreated malleable cast iron is significantly reduced, the quality of coating is significantly improved, and it has broad application prospects in the galvanizing industry.

Description

technical field [0001] The invention belongs to the field of metal surface engineering, and in particular relates to a surface pretreatment method for improving the quality of hot-dip galvanized coating of malleable cast iron. Background technique [0002] In the traditional manufacturing industry, the hot-dip galvanizing method has a long history of development. As a relatively mature protection measure, it is widely used on the surface of metal parts such as high-voltage line towers exposed to the wild and street lamp poles in urban atmospheric environments. Corrosion protection. [0003] Hot-dip galvanized malleable iron is usually used in hot-dip galvanized pipe fittings, including galvanized elbows, galvanized flanges, galvanized elbows, galvanized reducers, galvanized pipe caps, etc. During the hot dip plating process, the alloy thermodynamic and kinetic reaction occurs between the pipe fittings substrate and the zinc liquid or zinc alloy liquid to form a corrosion-re...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C2/02C23C2/06
CPCC23C2/02C23C2/06
Inventor 王建华吴悔刘亚吴长军苏旭平
Owner CHANGZHOU UNIV