KR20030034390A - Zn electrodeposited steel sheet for good corrosion resistance and hardness - Google Patents

Abstract

PURPOSE: A method for manufacturing an electro-galvanized steel sheet is provided to improve corrosion resistance and hardness of plating layer during electro-galvanizing by performing plating after adding a proper amount of solution comprising Fe and W to a galvanizing bath based on chlorides. CONSTITUTION: The method for manufacturing an electro-galvanized steel sheet having good corrosion resistance and surface hardness is characterized in that plating is performed by adding a solution prepared by mixing the dissolved solutions after dissolving iron chloride and sodium tungstenate into water with a ratio of Fe to W being 1:0.05 to 1:3 to the plating bath so that the total sum of the two metals Fe and W is 0.01 milli mole to 0.1 mole when performing electro-galvanizing in an acidic chloride based electro-galvanizing bath. The electro-galvanizing solution for chloride bath is prepared by adding a solution prepared by mixing the dissolved solutions after dissolving iron chloride and sodium tungstenate into water with a ratio of Fe to W being 1:0.05 to 1:3 in an acidic chloride based electro-galvanizing bath to the plating bath so that the total sum of the two metals Fe and W is 0.01 milli mole to 0.1 mole.

Description

Method for manufacturing zinc electroplated steel sheet with good corrosion resistance and surface hardness {Zn electrodeposited steel sheet for good corrosion resistance and hardness}

The present invention relates to a method for producing a zinc electroplated steel sheet having excellent corrosion resistance and surface hardness, and more particularly, to a method for producing a plating bath and a zinc electroplated steel sheet having excellent corrosion resistance and surface hardness in a chloride-based zinc plating bath. .

In general, zinc electroplating materials in surface treatment products have many advantages in terms of ease of plating, cost and corrosion resistance, and are widely used as materials for home appliances, construction, and automobiles. In order to improve the productivity of such a steel sheet, high current density plating is mainly performed, and when used for painting, the surface appearance of the plating layer should be excellent.

In addition, it should be well processed without peeling of the plating layer where the deep processing for the final product is performed. As the zinc electroplating bath, chloride bath, sulfate bath, cyan bath and neutral salt bath are used. Among them, the chloride bath is known to be suitable for high current density plating because of its excellent electrical conductivity. Therefore, the coating amount should be increased by a certain amount because it depends on the coating amount. Therefore, as a result, plating adhesion becomes unstable and workability becomes weak. In addition, due to the low hardness of the plating layer, pressing marks become more pronounced during processing, resulting in poor striation.

In addition, U.S. Patent 4,075,066 improves the properties of plating materials by adding at least one polyoxalalkylate naphthol and Hanisa's aromatic carboxylic acid or salt for distribution of gloss, ductility and good plating current of the plating layer in ammonia free plating bath. U.S. Patent 4,146,441 is a mixture of formaldehyde in order to improve the glossiness of the plating layer and expand the plating current density in the sulfuric acid bath, and to improve the glossiness by adding an amine polymer in the chloride bath. The proposed US patent 3,855,085 improves the surface gloss by adding nonionic polyoxyethylene in a chloride bath. Selectively use calcium chloride, magnesium chloride, etc., and change the plating conditions In addition, Japanese Patent No. 61-204389 has a patent for improving the gloss by adding an additive such as amino acid, glycine, and hydroxyproline, but these are mainly limited to improving the gloss, which is the surface appearance of the galvanized layer. . In addition, patents of zinc-nickel alloy plating such as Japanese Patent Application Laid-Open No. Hei 8-225984 and Japanese Patent Laid-Open No. 6-122992 and alloy plating such as zinc-iron have been developed, but alloy plating containing a large amount of additive elements is sufficient to change the physical properties of the plating layer itself. As a result, the cost is increased.

The present invention has been made in order to solve the above problems, the present invention is to improve the corrosion resistance and hardness of the coating layer during zinc electroplating to a plating solution for zinc plating by combining a small amount of iron components and a small amount of tungsten components and An object of the present invention is to produce a steel sheet, and to achieve an effect by plating by adding an appropriate amount of a liquid composed of an iron component and a tungsten component in an appropriate ratio to a zinc plating bath based on a chloride bath.

In addition, an object of the present invention is to obtain a plating layer having excellent corrosion resistance and hardness without impairing the adhesion of the plating layer by adding a small amount of iron and tungsten components to the plating bath during the zinc electroplating in the chloride bath to precipitate on the plating surface. .

Hereinafter, the present invention will be described in more detail.

In order to solve the above problems, the present invention dissolved two components consisting of iron chloride and sodium tungsterator in zinc chloride electroplating bath in an acid chloride-based electro zinc plating bath in an iron: tungsten ratio of 1: 0.05 to 1: 3 and then dissolved in water. It proposes a method for producing a zinc electroplated steel sheet excellent in corrosion resistance and surface hardness to add a solution prepared by combining the addition of 0.01mm ~ 0.1mol of the sum of the two metal components to the plating bath.

In addition, in the present invention, a solution prepared by dissolving two components composed of iron chloride and sodium tungsterator in an acid chloride type electro zinc plating bath in an iron: tungsten ratio of 1: 0.05 to 1: 3 and then dissolving it in water is added to the plating bath. A zinc electroplating solution of chloride bath is further proposed so that the sum of the two metal components is added in an amount of 0.01 mmol to 0.1 mol.

In the present invention, two components consisting of iron chloride and sodium tungsterator are dissolved in water at room temperature-60 degrees Celsius at a ratio of iron: tungsten in a ratio of 1: 0.1 to 1: 3, and then dissolved by stirring for 300 seconds or more. Prepared in combination. When the solution prepared as described above is added with 0.01 mmol-0.1 mole of the sum of the dimetallic components added to the acidic chloride type electro zinc plating bath, electrolytic zinc plating products having excellent corrosion resistance and surface hardness as described above are obtained. I can manufacture it.

In the present invention, when the ratio of iron and tungsten is less than 1: 0.1, the content of tungsten is low, so that it is difficult to individualize the quality of the plating layer. It doesn't work. Therefore, there is no increase in corrosion resistance and hardness of the plating layer, and current efficiency decreases due to excessive tungsten.

If the added amount of the two metals (iron + tungsten) is 0.01 mmol or less, the added element is too small to achieve the desired characteristics of the plated layer. At 0.1 mol or more, the elements of the added layer are increased compared to the zinc element. The cost is increased, and a ballistic plating is generated with a black surface appearance.

The plating bath manufactured as described above may be plated under generally known zinc electroplating conditions to obtain a plated steel sheet having good quality. The electroplating by the additive element of the present invention can be applied to electrogalvanization using acid chloride regardless of the metal type and shape of the plated body, and especially excellent plating quality during continuous electrogalvanization of steel sheets requiring high current density plating. It is a very effective means to obtain easily.

Hereinafter, embodiments of the present invention will be described.

(Example)

The electroplating was performed under the plating solution concentration and plating conditions shown in Table 1 using a general low carbon steel sheet as a metal, and then the results of measurement of corrosion resistance and hardness of the coated steel sheet were compared. The concentration and plating conditions of the plating solution were Zn: 100 g / L, Cl: 260 g / L, plating amount: 40 g / m ² , temperature 60 ^° C., pH: 4.5, and current density of 100 A / dm ² .

Corrosion resistance in the evaluation of the characteristics of the plated layer was judged to be poor if red rust occurred before 72 hours by salt spray test by JIS standard jet-2371, and the hardness of the plated layer was 80 or less using Vickers hardness tester. Determined.

Plating Material No Iron: molar concentration ratio of tungsten Total amount added Corrosion resistance Hardness One 1: 0.01 0.5mmol Bad Bad 2 1: 0.04 0.5mmol Bad Bad 3 1: 0.05 0.5mmol Good Good 4 1: 0.06 0.5mmol Good Good 5 1: 0.1 0.5mmol Good Good 6 1: 0.5 0.5mmol Good Good 7 1: 0.8 0.5mmol Good Good 8 1: 1 0.5mmol Good Good 9 1: 2 0.5mmol Good Good 10 1: 3 0.5mmol Good Good 11 1: 3.1 0.5mmol Bad Bad 12 1: 0.5 0.0 moles Bad Bad 13 1: 0.5 0.001 mmol Bad Bad 14 1: 0.5 0.005 mmol Bad Bad 15 1: 0.5 0.01 mmol Good Anho 16 1: 0.5 0.05mm Good Good 17 4.0 0.5mmol Good Good 18 4.1 1.0 mmol Good Good 19 4.3 0.01 moles Good Good 20 2.0 0.05 moles Good Good 21 2.0 0.1 mole Good Good 22 2.0 0.105 mole Bad Bad 23 2.0 0.11 mol Bad Bad

As shown in the Examples of Table 1 within the limited range of the additive element of the present invention (3 ~ 10, 15 ~ 21) shows good corrosion resistance and hardness it can be confirmed that the plating quality is improved.

As described above, when the zinc electroplated steel sheet is manufactured by the plating bath according to the present invention, corrosion resistance and hardness in the plating layer are superior to those of the prior art.

Claims (2)

In an acid chloride electro zinc plating bath, two components consisting of iron chloride and sodium tungsterator are dissolved in water at an iron: tungsten ratio of 1: 0.05 to 1: 3 and then combined with zinc. A method for producing a zinc electroplated steel sheet having excellent corrosion resistance and surface hardness, characterized in that plating is performed by adding 0.01 mmol to 0.1 mol of the sum of two metal components. A solution prepared by dissolving two components composed of iron chloride and sodium tungsterator in an acid chloride-based electro zinc plating bath in an iron with a tungsten ratio of 1: 0.05 to 1: 3 and then combining the solution was prepared in the plating bath. Chloride bath zinc electroplating solution, characterized in that the addition is further added so that the sum is 0.01 mmol ~ 0.1 mol.