KR101427403B1 - Method of Zincification to Improve Corrosion Resistance, and the Plating Solution to be Used for the Method - Google Patents

Abstract

A zinc plating method for improving corrosion resistance and a plating bath to be used therefor are introduced.
The plating method for improving the corrosion resistance of the present invention is characterized in that any one selected from among ammonium sulfate, charcoal and ammonium chloride is added to zinc and a steel sheet is coated with an acidity-enhanced bath formed by further adding a titanium salt, The titanium salt is added in an amount of 0.05 mg / L or more and 1.5 mg / L or less based on the entire plating bath.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc plating method for improving corrosion resistance and a plating bath for use therein,

The present invention relates to a method for improving the corrosion resistance of zinc plating and a plating bath used therefor, and more particularly, to a method for improving the corrosion resistance of a galvanized steel sheet while maintaining the existing rate of acidic zinc plating in galvanizing Method and a plating bath used therefor, which is superior in corrosion resistance as well as in processability and weldability to conventional galvanized steel sheets, and can be widely used as a material for automobile parts, building materials and electronic parts. A zinc plating method and a plating bath used therefor.

A disadvantage of the conventional galvanized steel sheet is that the corrosion resistance is weak.

In order to overcome such disadvantages, a steel sheet is plated with zinc as a basic component and a zinc alloy containing at least one of nickel, cobalt, iron, and manganese.

Korean Patent Laid-Open No. 10-2009-0052470 (May 26, 2009) discloses a multilayer electrogalvanized steel sheet excellent in corrosion resistance and surface appearance and a method for producing the same.

It includes a zinc-nickel alloy wire plating layer and a zinc plating layer by zinc electroplating. By determining the optimal current density ratio at the time of forming the plating layer, it has excellent corrosion resistance, adhesion and surface whiteness, Resistant zinc electroplated steel sheet excellent in corrosion resistance and surface appearance, and a method for manufacturing the same.

The multi-layered electrogalvanized steel sheet excellent in corrosion resistance and surface appearance and the method for manufacturing the same is characterized by comprising 1 to 9 g / m ^{2 of} a zinc nickel plated layer containing 8 to 12 wt% of Ni formed on the surface of a steel sheet, It comprises 8g / m ² or more of the zinc coating layer formed on the current density during the formation of the zinc plating layer is characterized by 1.1 to 1.5 times the current density in forming the zinc-nickel plating line.

Korean Patent Laid-Open No. 10-2006-0076173 (2006.07.04) discloses "a plating line of high corrosion resistance, a plating bath composition, a method of manufacturing a high-corrosion-resistant plated steel wire and a wire netting product".

It is intended to provide a high strength, high porosity plated steel wire having excellent corrosion resistance and workability and further increasing the total amount of plating layer and intermediate layer.

Korean Patent Laid-Open No. 10-2004-0006896 (Apr. 24, 2002) discloses "a method of manufacturing a zinc-iron-plated steel sheet ".

The present invention relates to a method for reducing the working process in the electroplating of a zinc-iron alloy, in which the electrode voltage continuously changes in the plating bath to change the zinc-iron content ratio of the upper and lower layers of the plating layer The present invention provides a method for manufacturing a zinc-iron-based double-layer coated steel sheet, which comprises the steps of: And a 'zinc-iron-plated steel sheet manufacturing method' capable of reducing work costs and cost.

However, when alloying elements such as nickel, cobalt, iron, and manganese are added to zinc in order to reinforce the deterioration of corrosion resistance, which is a disadvantage of the galvanized steel sheet, as in the above-described prior arts, There is a problem that the plating layer is rarely accepted due to the suppression effect of zinc hydroxide formed on the surface of zinc rather than zinc, and the alloy ion concentration in the plating bath must be set fairly high for effective plating, there was.

In addition, plating using a zinc alloy has a plating rate lower than that of a conventional zinc plating, so that the efficiency of the process is lowered and the production cost is lowered.

It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present invention and is not to be construed as adhering to the prior art already known to those skilled in the art.

Korean Patent Publication No. 10-2009-0052470 (2009.05.26.) Korean Patent Publication No. 10-2006-0076173 (2006.07.04) Korean Patent Publication No. 10-2004-0006896 (Apr. 24, 2002)

It is an object of the present invention to provide a method for improving the corrosion resistance of a galvanized steel sheet and a plating solution used therefor without increasing the production cost in order to solve such conventional problems.

In order to accomplish the above object, the present invention provides a zinc plating method for improving corrosion resistance, comprising the steps of: adding any one selected from ammonium sulfate, ammonium chloride, and ammonium chloride to zinc and further adding a titanium salt, Wherein the titanium salt is added in an amount of 0.05 mg / L to 1.5 mg / L with respect to the entire plating bath.
Further, the present invention is characterized in that the steel sheet is plated with a plating bath formed by adding a titanium salt to any one selected from alkali jingite or alkaline cyanide, wherein the titanium salt is used in an amount of 0.05 mg / And an amount of 1.5 mg / L or less is added.
On the other hand, the titanium salt, potassium titanyl oxalate _{(Potassium Titanyl oxalate, K₂C₄O 9 Ti} 2H₂O), potassium hexafluorotitanate titanate (Potassium Hexafluorotitanate, K₂TiF _6), titanium tetrachloride (Titanium Tetrachloride, TiCl₄), titanium tetra-fluoride (Titanium Tetrafluoride, TiF 4), titanium trichloride (TiCl 3), and the like.
Further, it is characterized in that any one selected from ammonium sulfate, carboxy chloride and ammonium chloride is added to zinc and the titanium salt is added in an amount of 0.05 mg / L or more and 1.5 mg / L or less.
On the other hand, a titanium salt is added to any one selected from alkali jingite or alkaline cyanide, wherein the titanium salt is added in an amount of 0.05 mg / L or more and 1.5 mg / L or less based on the entire plating bath .
The titanium salt, potassium titanyl oxalate _{(Potassium Titanyl oxalate, K₂C₄O 9 Ti} 2H₂O), potassium hexafluorotitanate titanate (Potassium Hexafluorotitanate, K₂TiF _6), titanium tetrachloride (Titanium Tetrachloride, TiCl₄), titanium tetra-fluoride (Titanium Tetrafluoride, TiF₄, Titanium Trichloride and TiCl₃.

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The galvanized steel sheet produced according to the present invention is remarkably improved in not only corrosion resistance but also processability, weldability and mechanical strength as compared with the conventional galvanized steel sheet, and thus can be widely used as materials for automobile parts, building materials and electronic parts. Moreover,

The method of the present invention has the same acidic or alkaline zinc plating rate as that of the conventional zinc alloy plating method and is faster than other zinc alloy plating rates, and is economical because plating is performed while maintaining existing plating facilities as it is.

Hereinafter, a zinc plating method for improving corrosion resistance according to a preferred embodiment of the present invention and a plating bath used therein will be described with reference to the accompanying drawings.

The zinc plating method for improving the corrosion resistance of the present invention is characterized in that any one selected from ammonium sulfate, charcoal and ammonium chloride is added to zinc and further a titanium salt is further added to plate the steel sheet with the acidic ascorbic acid bath .

Such a plating method is a method in which a titanium salt is added to an existing acid plating bath to perform plating, which is faster than the conventional zinc alloy plating method and is a method capable of further improving the corrosion resistance.

Titanium salts are added to the galvanizing method for such corrosion resistance of the present invention, potassium titanyl oxalate _{(Potassium Titanyl oxalate, K₂C₄O 9 Ti} 2H₂O), potassium hexafluorotitanate titanate (Potassium Hexafluorotitanate, K₂TiF _6), titanium tetrachloride It is preferable to use any one of titanium salts selected from titanium tetrachloride, titanium tetrachloride, titanium tetrafluoride, titanium fluoride, and titanium trichloride.

Hereinafter, a method of zinc plating for improving the corrosion resistance of the present invention and a plating bath used therefor will be described with reference to examples.

In the present embodiments, the zinc-plated steel sheet is manufactured by applying the present invention, and the cold rolled sheet steel is plated with zinc-titanium alloy using a circulating plating apparatus.

Electricity was allowed to flow at a current density of 280 A / dm 2, and the plating amount was adjusted to 20 g / m 2. The basic composition of the plating solution used in this example was as follows. Plating was performed while changing the content of titanium (Ti) ions .

Example  1 to Example  8 of Plating bath  Basic composition

Zinc sulfate: 420 g / l

Ammonium sulfate: 23 g / l

Sulfuric acid: 10-13 g / l

Titanium salt: 0.05-5000 mg / l

Ph: 3-3.5

Current density: 280 A / dm 2

In Comparative Example 1, which was compared with Examples 1 to 8, 420 g / l of zinc sulfate, 23 g / l of ammonium sulfate, 10-13 g / l of sulfuric acid, 3-3.5 of Ph, The current density was 280 A / dm 2, and the cold-rolled steel sheet was plated using a circulating plating apparatus.

For the corrosion resistance test of the coated steel sheets of these Examples and Comparative Example 1, a water-soluble polyester coating agent (nonchromate) was coated to about 2 탆, dried at 120 캜 for 10 minutes and left to stand for 24 hours in accordance with JIS-Z-2371 After the elapse of 200 hours, the area of occurrence of white rust was measured to be 5% or less. The results are shown in Table 1 below.

Example Plating bath Titanium salt Titanium salt
Content (mg / l) Plating state Plated
time After treatment Corrosion resistance
(hr) One
Zinc sulfate
420 g / l
Ammonium sulfate
23 g / l
Sulfuric acid
11 g / l
PH 3.2 TiNSO4 0.05 Good 30 seconds Resin coating 240
(Good) 2 TiNSO4 0.1 Good 30 seconds Resin coating 240
(Good) 3 TiNSO4 One Good 30 seconds Resin coating 168
(Good) 4 TiNSO4 1.5 Good 30 seconds Resin coating 144
(Good) 5 K₂C₄O ₉ Ti 2H₂O 0.05 Good 30 seconds Resin coating 192
(Good) 6 K₂C₄O ₉ Ti 2H₂O 0.1 Good 30 seconds Resin coating 240
(Good) 7 K₂C₄O ₉ Ti 2H₂O One Good 30 seconds Resin coating 168
(Good) 8 K₂C₄O ₉ TI 2H₂O 1.5 Good 30 seconds Resin coating 144
(Good) Comparative Example 1 - Good 30 seconds Resin coating 48
(Fire)

As shown in Table 1, in all of Examples 1 to 8 and Comparative Example 1, the plating state was found to be good.

However, in Examples 1 to 8, it was confirmed that the time and corrosion resistance required for plating were significantly improved as compared with Comparative Example 1.

On the other hand, the present invention was applied to zinc plated samples for automobile parts, building materials or electronic parts. The test specimens used in the examples were plated with a steel bolt of M10X1.5X40 and plated to a thickness of 8 mu m, and plating was performed while changing the amount of titanium salt added to the existing acidic zinc chloride chloride plating bath. The polish was polished with benzaldehyde. The basic composition of the plating bath used in this example is as follows.

Example  9 - Example  Fifteen Plating bath  Basic composition

Zinc metal powder: 25 g / l

Caryl chloride: 200 g / l

Boric acid: 25 g / l

Benzaldehyde: 1 ml / l

Ph: 4-5.5

Plating solution temperature: 25 캜

In the case of the comparative example 2 and the comparative example 3, which were compared with those of the examples 9 to 15, the test specimens were made of steel bolts having M10X1.5X40 and plated to a thickness of 8 mu m. In the existing acidic zinc chloride- Was polished with benzaldehyde.

The results of Examples and the results of Comparative Examples 2 and 3 were tested for corrosion resistance.

For the corrosion resistance test, trivalent chromate treatment (chemical conversion coating treatment) was carried out, and the corrosion resistance test was carried out in accordance with JIS-Z-2371, and the occurrence time of white rust and the occurrence time of red rust were measured.

Example Plating bath Titanium salt Titanium salt
Content (mg / l) Glossiness After treatment Plated
time White Chung
Occur
(hr) Redness occurrence
(hr) 9 Zinc metal powder
25 g / l
Carbonated Chilli
200 g / l
Boric acid
25 g / l
Benzaldehyde
1 ml / l
PH4.5 TiNSO4 0.05 Good Chromate 40 minutes 300 1500 10 TiNSO4 0.1 Good Chromate 40 minutes 350 1500 11 TiNSO4 One Good Chromate 40 minutes 500 2000 12 TiNSO4 1.5 Good Chromate 40 minutes 500 2000 13 K₂C₄O ₉ 2H₂O 0.05 Good Chromate 40 minutes 300 1500 14 K₂C₄O ₉ 2H₂O One Good Chromate 40 minutes 500 2000 15 K₂C₄O ₉ 2H₂O 1.5 Good Chromate 40 minutes 500 2000 Comparative Example 2 Good Chromate 40 minutes 98 180 Comparative Example 3 Good 40 minutes 2 24

As shown in Table 2, in all of Examples 9 to 15 and Comparative Examples 2 and 3, it was confirmed that the plating state was good.

However, in Examples 9 to 15, it was confirmed that the time and corrosion resistance required for plating were significantly improved as compared with Comparative Example 2 and Comparative Example 3.

In the present embodiments, the present invention is applied, but zinc plating is performed on specimens used as materials for automobile parts, building materials, electronic parts, and the like, unlike the plating solutions in Examples 9 to 17.

In the present examples, the test specimens were plated with M10X1.5X40 iron bolts and plated to a thickness of 8 mu m, and plating was performed while changing the amount of titanium salt added to the existing acidic zinc ammonium chloride plating solution.

The brightener was polished with benzaldehyde. The basic composition of the plating bath used in this example is as follows.

Example  16 - Example  22 of Plating bath  Basic composition

Zinc metal powder: 25 g / l

Ammonium chloride: 200 g / l

Benzaldehyde: 1 ml / l (polish)

Ph: 4-6.5

Plating solution temperature: 25 캜

In order to confirm the effects of improving the corrosion resistance of Examples 16 to 22 to which the present invention was applied, comparative examples according to the conventional methods were performed.

In the comparative example, M10X1.5X40 steel bolts were used as the test specimens, and the plating thickness was 8 탆. Gloss plating was performed by adding polish benzaldehyde to the existing acidic zinc ammonium chloride plating solution.

The results of Examples and Comparative Examples 4 and 5 were tested for corrosion resistance.

For the corrosion resistance test, the chromate and the corrosion resistance test were carried out in the same manner as in Examples 9 to 15, and the results are shown in Table 3.

Example Plating bath Titanium salt Titanium salt
Content (mg / l) Glossiness After treatment Plating time White rust occurrence
(hr) Redness occurrence
(hr) 16 Zinc metal powder
25 g / l
Ammonium chloride
200 g / l
NA-600A
25 ml / l
NA-600B
1 ml / l
PH 5
TiNSO4 0.05 Good Chromate 40 minutes 300 1500 17 TiNSO4 0.1 Good Chromate 40 minutes 350 1500 18 TiNSO4 One Good Chromate 40 minutes 500 2000 19 TiNSO4 1.5 Good Chromate 40 minutes 500 2000 20 K₂C₄O ₉ 2H₂O 0.05 Good Chromate 40 minutes 300 1500 21 K₂C₄O ₉ 2H₂O One Good Chromate 40 minutes 500 2000 22 K₂C₄O ₉ 2H₂O 1.5 Good Chromate 40 minutes 500 2000 Comparative Example 4 Good Chromate 40 minutes 98 180 Comparative Example 5 Good 40 minutes 2 24

As shown in Table 3, in all of Examples 16 to 22 and Comparative Examples 4 and 5, it was confirmed that the plating state was good.

However, it was confirmed that the time required for plating and the corrosion resistance were significantly improved as compared with Comparative Example 4 and Comparative Example 5 in Examples 16 to 22.

In the following examples, zinc-titanium alloy plating was performed by applying the present invention.

The test specimens of the examples were plated with a steel bolt of M10X1.5X40, plated to a thickness of 8 mu m, and plated while changing the amount of titanium added to the existing alkaline plating bath. The brightener was brightly plated using nicotinic acid amide. The basic composition of the plating solution used in these examples is as follows.

Example  23 - Example  33 of Plating bath  Basic composition

Alkali zincate bath

Zinc metal powder: 8 g / l (zinc oxide: 10 g / l)

Caustic soda: 130 g / l

Nicotinic acid amide: 2 to 3 g / l

In Comparative Example 6 and Comparative Example 7, a steel bolt having a specimen M10X1.5X40 was used and plated to a thickness of 8 mu m. In a conventional alkaline plating bath, a polishing agent was prepared by using a nicotinic acid amide And then polished.

For the corrosion resistance test, the plated bolts were subjected to trivalent chromate treatment (chemical conversion coating treatment), and the corrosion resistance test was carried out in accordance with JIS-Z-2371, and the occurrence time of white rust and the occurrence time of red rust were measured. .

Example Plating bath Titanium salt Titanium salt
Content (mg / l) Plating time Glossiness After treatment White rust occurrence
(hr) Redness occurrence
(hr) 23

Zinc oxide
10 g / l

Caustic soda
130 g / l

Nicotinamide
2 to 3 g / l


K ₂ C ₄ O ₉ 2H ₂ O


0.1 40 minutes Good Chromate 350 1500 24 0.5 40 minutes Good Chromate 400 1800 25 One 40 minutes Good Chromate 500 2000 26 5 40 minutes Good Chromate 600 2000 27 2 40 minutes Good Chromate 500 2000 28 3 40 minutes Good Chromate 500 2000 29
TiNSO ₄ 0.1 40 minutes Good Chromate 300 1400 30 0.5 40 minutes Good Chromate 350 1500 31 One 40 minutes Good Chromate 450 1800 32 3 40 minutes Good Chromate 450 1800 33 5 40 minutes Good Chromate 450 1800 Comparative Example 6 40 minutes Good Chromate 72 120 Comparative Example 7 40 minutes Good 24 48

Meanwhile, the test specimens used in the examples were plated with a bolt of M10X1.5X40 to a thickness of 8 mu m, and plating was performed while changing the amount of titanium added to the existing alkaline jinkite plating bath. Gloss plating was performed using nicotinic acid amide. The basic composition of the plating solution used in these examples is as follows.

Example  34 - Example  44 of Plating bath  Basic composition

Alkaline cyan plating bath

Chrysanthemum zinc: 36 g / l (zinc oxide: 25 g / l)

Cheonghwa Soda: 28g / l

Caustic soda: 80g / l

Nicotinic acid amide: 2-3 g / l

Comparative Example 9 and Comparative Example 10 according to the conventional method were carried out in order to confirm the corrosion resistance improving effects of Examples 34 to 44 to which the present invention was applied. The specimen used in the comparative example was a bolt having a thickness of M10X1.5X40 and was plated so as to have a thickness of 8 mu m. The conventional alkaline cyan plating bath was polished using a nicotinic acid amide as a polishing agent.

The results of the above Examples and Comparative Examples 9 and 10 were tested for corrosion resistance. The corrosion resistance test was carried out in the same manner as in Examples 34 to 44, and the results are shown in Table 5.

Example Plating bath Titanium salt Titanium salt
Content (mg / l) Plating time Glossiness After treatment White rust occurrence
(hr) Redness occurrence
(hr) 34
Zinc blue
35 g / l

Soda blue
28 g / l

Caustic soda
80g / l

Nicotinamide
2-3 g / l

K ₂ C ₄ O ₉ 2H ₂ O 0.1 40 minutes Good Chromate 300 1500 35 0.5 40 minutes Good Chromate 350 1600 36 1.5 40 minutes Good Chromate 600 2000 37 3 40 minutes Good Chromate 500 2000 38 One 40 minutes Good Chromate 480 1800 39 4 40 minutes Good Chromate 500 2000 40
TiNSO ₄ 0.3 40 minutes Good Chromate 300 1500 41 0.8 40 minutes Good Chromate 350 1600 42 1.3 40 minutes Good Chromate 480 1800 43 3 40 minutes Good Chromate 500 2000 44 4 40 minutes Good Chromate 500 2000 Comparative Example 9 40 minutes Good Chromate 98 240 Comparative Example 10 40 minutes Good 24 48

While the present invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the following claims It will be apparent to those of ordinary skill in the art.

Claims (7)

Characterized in that any one selected from ammonium sulfate, carboxymethyl chloride and ammonium chloride is added to zinc and a steel sheet is plated with an acidity abrasion bath formed by further adding a titanium salt,
Wherein the titanium salt is added in an amount of 0.05 mg / l to 1.5 mg / l based on the entire plating bath.
Characterized in that the steel sheet is plated with a plating bath formed by adding a titanium salt to any one selected from the group consisting of alkaline zincate and alkaline cyanide,
Wherein the titanium salt is added in an amount of 0.05 mg / l to 1.5 mg / l based on the entire plating bath.
delete The method according to any one of claims 1 to 3,
The titanium salt, potassium titanyl oxalate _{(Potassium Titanyl oxalate, K₂C₄O 9 Ti} 2H₂O), potassium hexafluorotitanate titanate (Potassium Hexafluorotitanate, K₂TiF _6), titanium tetrachloride (Titanium Tetrachloride, TiCl₄), titanium tetra-fluoride (Titanium TiF4), titanium trichloride (TiCl3), and the like.
A zinc plating bath for improving corrosion resistance, which is formed by adding any one selected from ammonium sulfate, carboxy chloride and ammonium chloride to zinc and adding 0.05 mg / L to 1.5 mg / L of titanium salt.
An alkaline zincate or an alkaline cyanide, and further adding a titanium salt to the selected one,
Wherein the titanium salt is added in an amount of 0.05 mg / L to 1.5 mg / L with respect to the entire plating bath.
The method according to any one of claims 5 and 6,
The titanium salt, potassium titanyl oxalate _{(Potassium Titanyl oxalate, K₂C₄O 9 Ti} 2H₂O), potassium hexafluorotitanate titanate (Potassium Hexafluorotitanate, K₂TiF _6), titanium tetrachloride (Titanium Tetrachloride, TiCl₄), titanium tetra-fluoride (Titanium Wherein said at least one selected from the group consisting of titanium tetrachloride, titanium tetrachloride, titanium tetrachloride, titanium tetrachloride, titanium tetrachloride, titanium tetrachloride and titanium tetrachloride.