KR100605716B1 - Bath and electrodeposit of Sn-Zn-Ti alloy - Google Patents

Abstract

Tin-zinc-titanium alloy electroplating solutions and electroalloy plating materials are provided.

The present invention, tin chloride (SnCl ₂ H ₂ O): 10-40 g / L, hydrated zinc sulfate (ZnSO4.7H ₂ O): 10- 60 g / L, titanium chloride: 5-50 g / L, sodium sheet hydrate _{(Na 3 C 6 H 5 O} 7): 40 ~ 150g / ℓ, tartaric acid, potassium _{(K 2 C 4 H 4 O} 6 .1 / 2H 2 O): 10 ~ 80g / ℓ and ammonium sulfate (NH _{4) It} relates to a plating solution comprising ₂ SO ₄ : 30-90g / ℓ, and an electroplating steel sheet produced using the same.

Electroplating, Tin-Zinc-Titanium, Tin Chloride

Description

Tin-zinc-titanium alloy electroplating solution and electroalloy plating material {Bath and electrodeposit of Sn-Zn-Ti alloy}

The present invention relates to the production of plated steel sheet which does not contain environmentally friendly lead in place of the lead-tin alloy plated steel sheet used in automobile fuel tanks, and more particularly, provides excellent corrosion resistance and fuel resistance, and particularly good workability. The present invention relates to a plating solution for producing a tin-zinc-titanium plated steel sheet which can have excellent properties even after processing, and a plated steel sheet prepared therefrom.

The materials used in fuel tanks, which are the main parts of automobiles, need not only excellent corrosion resistance and fuel resistance but also physical properties such as workability and weldability. Conventionally, electric and molten Turner steel sheets, which are lead-tin alloy plated steel sheets, have been widely used as materials for fuel tanks.However, in recent years, there is a need for materials that have less influence on the global environment and easy to recycle resources. There is a need to develop alternative materials that do not use lead.

In particular, as global regulations on lead in dust generated from automobile scrapping have been tightened, the need for lead-free steel sheet to replace the existing molten Terne steel sheet has emerged. Technology development on resin coated steel sheet and the like is being made.

As an example of the prior art for solving this problem, there is a special chromate-treated zinc-nickel plated steel sheet proposed in Japanese Patent Laid-Open No. 9-59783. However, the chromate treatment causes a crack in the surface of the zinc-nickel alloy plating film in order to prevent the corrosion resistance after processing, resulting in a process load and deterioration of fuel resistance due to chromium elution due to moisture contained in the fuel. Has its drawbacks. In addition, it is costly by complicated processes such as resin and chromate on the plating layer, and corrosion resistance is inferior due to dropping of the resin during processing.

In addition, Japanese Patent Application Laid-Open No. 8-325692 proposes a hot-dip plating material for tin-zinc plating. However, tin-zinc hot-dip plating has difficulty in controlling the thickness of the plating layer, which causes problems in securing uniformity and poor workability. In Japanese Patent Application Laid-Open No. 8-269733, an alloy layer containing at least one of nickel, iron, zinc, and tin is 2 micrometers or less on one side, and the tin is 40-99% on the balance, and the balance is all zinc and impurities. Although a steel sheet for a fuel tank is proposed, this method has a limitation on the size control of the particles of zinc in the final plating layer, which has a defect in that the working conditions are severe when manufactured in a continuous line.

 Therefore, the present invention is to solve the above-mentioned problems of the prior art, the tin-zinc-titanium plating on the steel plate used as a base metal, which is excellent in corrosion resistance and fuel resistance tin that can be used for fuel tanks of automotive steel plates It is an object of the present invention to provide a plating solution for producing a zinc-titanium plated steel sheet and a tin-zinc-titanium plated steel sheet using the same.

The present invention for achieving the above object,

Tin chloride (SnCl ₂ .2H ₂ O): 10 to 40 g / l, hydrated zinc sulfate (ZnSO4.7H ₂ O): 10 to 60 g / l, titanium chloride: 5-50 g / l, sodium citrate hydrate (Na _{3 C 6 H 5 O 7)} : 40 ~ 150g / ℓ, tartaric acid, potassium _{(K 2 C 4 H 4 O} 6 .1 / 2H 2 O): 10 ~ 80g / ℓ and ammonium sulfate (NH _{4) 2} SO _4: It relates to a plating solution for the production of tin-zinc-titanium electroplating steel sheet, including 30-90 g / L.

The present invention also relates to a tin-zinc-titanium electroplated steel sheet in which the weight ratio of tin: zinc: titanium in the alloy plating layer produced by the plating solution is controlled from 1: 0.2 to 0.4: 0.1 to 0.2.

Hereinafter, the present invention will be described.

The present invention is carried out by using a cold-rolled steel sheet as a base metal of the plating, the plating is necessary to ensure the corrosion resistance and fuel resistance for the fuel tank. In addition, fuel must not leak due to the processability and good weldability by applying complicated shape of the lower part of the vehicle.

Considering this point, steel sheets used for automobile fuel tanks require corrosion resistance, processability, and weldability. For this purpose, tin has a weight ratio of tin: zinc: titanium at 1: 0.2 to 0.4: 0.1 to 0.2. -Zinc-titanium alloy plating layer is required to be formed.

In the present invention, such a tin-zinc-titanium alloy plated steel sheet is prepared through a plating solution based on tin chloride and zinc sulfate, titanium chloride, sodium citrate, potassium stannate and ammonium sulfate.

In the present invention, first, tin chloride (SnCl ₂ H ₂ O) content in the plating solution composition is limited to 10 ~ 40g / ℓ. If the amount of tin chloride is less than 10 g / l it is not possible to obtain the desired level of tin in the alloy plating layer, and if it exceeds 40 g / l it is because the high current density can not be maintained.

In addition, zinc sulfate (ZnSO ₄ ) content is limited to 10 ~ 60g / ℓ. If the zinc sulfate content is less than 10g / ℓ because the pinhole of the plating layer is generated, the corrosion resistance is poor, if the zinc sulfate exceeds 60g / ℓ zinc sulfate is not dissolved in the solution is difficult to obtain the concentration of the target range of the coating layer.

The present invention also limits the titanium chloride content to 5-50 g / l. If the content of titanium chloride is less than 5g / ℓ, the content of Ti is not secured as much as the target content in the coating of the coating layer, and if the content exceeds 60g / ℓ plating adhesion is poor.

In addition, in the plating solution of the present invention, the content of sodium citrate hydrate (Na ₃ C ₆ H ₅ O ₇ ) is limited to 40 ~ 150g / ℓ. If the content is less than 40g / ℓ it is difficult to high current density of the plating solution, the gloss of the plating layer is difficult to be higher than 150g / ℓ.

In addition, the content of potassium stannate (K ₂ C ₄ H ₄ O ₆ ) is limited to 10-80 g / ℓ, less than 10 g / ℓ poor adhesion to the coating, while more than 80 g / ℓ of the coating layer particles are uneven and corrosion resistance Because it falls.

The content of ammonium sulfate (NH ₄ ) ₂ SO ₄ is limited to 30 ~ 90g / ℓ because the adhesion of the coating is less than 30g / ℓ, the surface of the plating layer is changed to brown when it exceeds 90g / ℓ.

Tin-zinc-titanium electroplating steel sheet may be manufactured by electroplating using the plating solution prepared as described above, wherein the weight ratio of tin: zinc: titanium in the alloy plating layer is 1: 0.2∼0.4: It is preferable to control to 0.1-0.2 from the viewpoint of corrosion resistance and plating adhesion.

The tin-zinc-titanium electroplated steel sheet thus prepared may be subjected to post-treatment (phosphate, chromium, rubbing, etc.) to obtain a final product.

Hereinafter, the present invention will be described in detail through examples.

(Example 1)

General carbon cold rolled steel sheet was electroplated using an electroplating solution with different composition after degreasing acid, as shown in Table 1, where the temperature of the plating bath was 60 ° C, the current density was 40A / dm ² , and the plating thickness was 4㎛. It was.

Experiments were performed to evaluate the corrosion resistance, adhesion and workability of the tin-zinc-titanium alloy plated steel sheets thus plated, and the results are shown in Table 1 as well. On the other hand, the corrosion resistance in this experiment was evaluated as good when the red rust generation time is more than 350 hours when the plating thickness of 4㎛ plated steel plates in the chlorine spray test apparatus according to the JIS jet 2371, poor quality below that, adhesion It was judged as good when there was no dropout of the plating layer by bending at 180 degrees, bad when there was a dropout, and workability with a friction coefficient of 0.17 or less by a draw bead test. .

No Composition of Plating Solution (g / L) quality Tin chloride Zinc sulfate Titanium chloride Potassium Tartrate Ammonium sulfate Sodium citrate Corrosion resistance Adhesion Machinability One 5 30 15 30 50 80 Bad Good Good 2 10 30 15 30 50 80 Good Good Good 3 15 30 15 30 50 80 Good Good Good 4 30 30 15 30 50 80 Good Good Good 5 40 30 15 30 50 80 Good Good Good 6 45 30 15 30 50 80 Bad Good Bad 7 20 5 15 30 50 80 Good Good Good 8 20 10 15 30 50 80 Good Good Good 9 20 20 15 30 50 80 Good Good Good 10 20 40 15 30 50 80 Good Good Good 11 20 60 15 30 50 80 Good Good Good 12 20 65 15 30 50 80 Bad Bad Bad 13 20 30 4 30 50 80 Bad Bad Good 14 20 30 5 30 50 80 Good Good Good 15 20 30 10 30 50 80 Good Good Good 16 20 30 20 30 50 80 Good Good Good 17 20 30 40 30 50 80 Good Good Good 18 20 30 50 30 50 80 Good Good Good 19 20 30 55 30 50 80 Bad Bad Bad 20 20 30 15 5 50 80 Bad Bad Bad 21 20 30 15 10 50 80 Good Good Good 22 20 30 15 20 50 80 Good Good Good 23 20 30 15 40 50 80 Good Good Good 24 20 30 15 60 50 80 Good Good Good 25 20 30 15 80 50 80 Good Good Good 26 20 30 15 85 50 80 Bad Bad Bad 27 20 30 15 30 25 80 Bad Bad Bad 28 20 30 15 30 30 80 Good Good Good 29 20 30 15 30 50 80 Good Good Good 30 20 30 15 30 70 80 Good Good Good 31 20 30 15 30 90 80 Good Good Good 32 20 30 15 30 95 80 Bad Bad Bad 33 20 30 15 30 50 35 Bad Bad Bad 34 20 30 15 30 50 40 Good Good Good 35 20 30 15 30 50 60 Good Good Good 36 20 30 15 30 50 100 Good Good Good 37 20 30 15 30 50 130 Good Good Good 38 20 30 15 30 50 150 Good Good Good 39 20 30 15 30 50 155 Bad Bad Bad

As shown in Table 1, when the composition of the plating bath is controlled within the scope of the present invention, it can be seen that the corrosion resistance, adhesion and workability of the plated steel sheet are all excellent.

However, when one or more of the compositions of the plating bath is outside the scope of the present invention (test numbers: 1, 6, 12, 13, 19, 20, 27, 33, 39) it can be seen that the desired plating properties can not be obtained.

(Example 2)

In order to investigate the quality characteristics according to the plating layer alloy composition, the cold-rolled steel sheet was electroplated using an electroplating solution having a different composition to obtain a plating layer alloy composition ratio as shown in Table 2. At this time, the plating bath temperature was 60 ℃, current density 40A / dm ² , and the plating layer thickness was plated at 4㎛.

The plated steel sheet thus prepared was evaluated under the same conditions as in Example 1 to evaluate corrosion resistance, adhesion and workability, and are also shown in Table 2.

No Plating layer Tin: Zinc: Alloy composition ratio of titanium Corrosion resistance Adhesion Machinability 40 1: 0.15 :: 0.15 Good Bad Bad 41 1: 0.2: 0.15 Good Good Good 42 1: 0.4: 0.15 Good Good Good 43 1: 0.45: 0.15 Bad Good Good 44 1: 0.3: 0.08 Bad Good Bad 45 1: 0.3: 0.1 Good Good Good 46 1: 0.3: 0.2 Good Good Good 47 1: 0.3: 0.25 Good Bad Bad

As shown in Table 2, when the alloy composition ratio of the plating layer belongs to tin: zinc: titanium = 1: 0.2 to 0.4: 0.1 to 0.2 (41,42,45,46), it can be seen that all have excellent plating characteristics. .

As described above, the present invention can effectively produce tin-zinc-titanium plated steel sheets that can be used for automobile fuel tanks by providing an optimal plating solution composition for tin-zinc-titanium plated steel sheets.

Claims (2)

Tin chloride (SnCl ₂ .2H ₂ O): 10 to 40 g / l, hydrated zinc sulfate (ZnSO4.7H ₂ O): 10 to 60 g / l, titanium chloride: 5-50 g / l, sodium citrate hydrate (Na _{3 C 6 H 5 O 7)} : 40 ~ 150g / ℓ, tartaric acid, potassium _{(K 2 C 4 H 4 O} 6 .1 / 2H 2 O): 10 ~ 80g / ℓ and ammonium sulfate (NH _{4) 2} SO _4: Plating solution for the production of tin-zinc-titanium electroplating steel sheet comprising 30-90g / l. A tin-zinc-titanium electroplated steel sheet having a weight ratio of tin: zinc: titanium in the alloy plating layer produced using the plating solution of claim 1 being controlled from 1: 0.2 to 0.4: 0.1 to 0.2.