KR101543793B1 - Composition for Magnesium Alloy Surface Treatment and Surface Treated Magnesium Alloy using the Same - Google Patents

Abstract

The present invention relates to (A) a fluorine compound; (B) a zirconium compound; And (C) at least one compound selected from a cerium compound and a vanadium compound, and a metal material using the composition.

The composition for metal surface treatment according to the present invention is used in the surface treatment of a metal material so that the metal material produced thereon is free from the risk of rusting during transportation or storage and maintains a beautiful surface appearance even after the rust- And has a low surface electric resistance, so that it can be usefully used as an alloy for internal parts of electronic equipment.

Zirconium, fluorine, cerium, vanadium, surface electric resistance, gloss, electronic parts inside

Description

TECHNICAL FIELD [0001] The present invention relates to a composition for surface treatment of magnesium alloy, and a magnesium alloy surface-

The present invention relates to a composition for surface treatment of a magnesium alloy and a magnesium alloy surface-treated using the same.

Metal materials such as steel, aluminum, magnesium alloy or stainless steel plated with zinc in general are widely used for metal materials for home appliances as well as building materials and automotive steel sheets.

However, since these metals are easily corroded or contaminated, the metal material is provided with a function of corrosion resistance or stain resistance by performing a predetermined coating treatment on the surface of the metal material.

That is, since the corrosion resistance of the metal material is very weak, rust occurs frequently during transport or storage, and rust is easily generated due to temperature difference due to temperature difference during transport or storage through an aircraft, There is a problem in that rust easily occurs due to the same reason.

Thus, although techniques for imparting a rust preventing effect to a metal material through surface treatment of a metal material have been developed, a metal material that has been subjected to rust-preventive treatment according to a conventional method is generally used for a metal material having a beautiful surface appearance through buffing or hair- When the rust-preventive surface treatment is carried out, there is a problem that the gloss is remarkably lowered, so that there is a problem that the value as a product is lowered.

In addition, when the metal material subjected to the rust-preventive treatment as described above is applied to an alloy for an internal part of an electronic device or the like, the surface electrical resistance of the metal material must be very low. Conventionally, in order to maintain the surface electrical resistance low, There is a problem in terms of cost and efficiency because additional additional processing steps have to be additionally performed on the surface of the substrate.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a composition for metal surface treatment which is treated on the surface of a metal material to provide excellent rust resistance and gloss to the metal material, It has its purpose.

It is another object of the present invention to provide a surface treatment using the above-mentioned composition for metal surface treatment, which has excellent surface electric resistance, gloss and corrosion resistance, and thus can be applied to various industries such as building products, automobile parts, home appliances, And to provide a metal material which can be usefully used in the field.

The present invention provides, as means for solving the above problems, (A) a fluorine compound; (B) a zirconium compound; And (C) at least one compound selected from a cerium compound and a vanadium compound.

The present invention also provides, as another means for solving the above problems, a substrate comprising: a substrate; And a coating layer formed on the substrate, wherein the coating layer is formed by the composition according to the present invention.

The metal surface treatment composition of the present invention as described above is treated on the surface of a metal material to provide excellent corrosion resistance and low surface electrical resistance and also exhibits excellent gloss even after rust-proofing treatment, Such a metal material can be more effectively used as an alloy for internal parts of electronic equipment due to its excellent appearance and low surface electrical resistance.

The present invention relates to (A) a fluorine compound; (B) a zirconium compound; And (C) at least one compound selected from a cerium compound and a vanadium compound.

Hereinafter, the composition for metal surface treatment of the present invention will be described in more detail. The composition according to the present invention comprises at least one compound selected from the group consisting of (A) a fluorine compound, (B) a zirconium compound and (C) a cerium compound or a vanadium compound.

Here, the fluorine compound (A) serves to improve the corrosion resistance and gloss of the composition according to the present invention, and any compound containing a fluorine element may be used without limitation, and the kind thereof is not particularly limited, For example, hydrofluoric acid (HF), hexafluoro phosphoric acid (HPF ₆ ), fluoro phosphoric acid (H ₂ PO ₃ F), fluoro silici acid (H ₂ SiF _6), zirconate (hexafluoro zirconic acid hexafluoropropane; as H ₂ ZrF _6), fluoro, sodium hexafluoro zirconate _{(sodium hexafluoro zirconate; Na 2 ZrF} 6) , and titanate (sodium hexafluoro titanate, sodium hexafluoro; Na ₂ TiF ₆ ), and may include at least one selected from the group consisting of hydrofluoric acid.

When such a fluorine compound (A) is contained, the corrosion resistance and the film adhesion can be greatly improved, and in particular, in the case of containing hydrofluoric acid, the glossiness and corrosion resistance can be greatly improved.

On the other hand, the (B) zirconium compound is a substance which improves the corrosion resistance in the composition according to the present invention, and may be any compound containing a zirconium element without any particular limitation. For example, zirconium fluoride, zirconyl nitrate, zirconyl acetate, ammonium zirconyl carbonate, zirconium acetylacetonate, potassium zirconium fluoride, zirconium oxide zirconia, ZrO ₂ , zirconium hydrofluoric acid, zirconium ammonium fluoride, and zirconium hydroxide fluoride. Specific examples of the zirconium fluoride zirconium fluoride include zirconium fluoride . ≪ / RTI >

The zirconium fluoride has an advantage that it can function not only to improve the corrosion resistance in the composition of the present invention but also to improve the surface electrical resistance property while maintaining or improving the gloss of the surface of the plate material which is developed by the buffing and hair line treatment .

The compound (C) serves to improve the corrosion resistance in the composition according to the present invention. The cerium compound or the vanadium compound may be used singly or in combination of two kinds Or more can be mixed with each other in a complementary manner, and more specifically, it may be a vanadium compound in terms of improving the corrosion resistance.

Here, the cerium compound may be any compound including a cerium element without any particular limitation, but may include, for example, at least one of a trivalent cerium compound, a tetravalent cerium compound, or a mixture thereof.

The trivalent cerium compound is not particularly limited, and examples thereof include cerium acetate (III), cerium carbonate (III), cerium chloride (III), cerium fluoride (III), cerium nitrate (III) , Cerium sulfate (III), cerium bromide (III), cerium iodide (III), cerium oxalate (III), cerium perchlorate (III), cerium sulfide (III) and their hydrates, (IV), ammonium cerium nitrate (IV), cerium (IV) hexanitrate (IV) salt, and the like. The cerium compound of the present invention can be obtained by, for example, , Ammonium cerium (IV) sulfate, cerium (IV) sulfate and their hydrates.

On the other hand, when the cerium compound is a mixture of a trivalent cerium compound and a tetravalent cerium compound, there is no particular limitation. For example, 20 parts by weight to 100 parts by weight of a tetravalent cerium element is added to 100 parts by weight of a trivalent cerium element Or mixtures thereof.

In the composition according to the present invention, when the mixture contains less than 20 parts by weight of tetravalent cerium element with respect to 100 parts by weight of the trivalent cerium element, the corrosion resistance may be lowered, , There is a possibility that the coating film adhesion is lowered in the top coating.

The vanadium compound may be any compound containing a vanadium element. The type of the vanadium compound is not particularly limited. For example, sodium vanadate, ammonium vanadate, vanadium nitride, and vanadium oxide.

On the other hand, the composition according to the present invention may contain various combinations of the fluorine compound (A), the zirconium compound (B) and the compound (C), and the content thereof is not particularly limited.

Accordingly, the composition for metal surface treatment can be appropriately selected and included within a range that can improve physical properties such as corrosion resistance, gloss, and surface electrical resistance of a metal material to be surface-treated according to the kind of a compound to be used have.

In addition, the composition according to the present invention may be a liquid composition containing the above-mentioned compound and the remaining amount of water and is not particularly limited. For example, the content of the total solid content in the composition according to the present invention is 0.1 to 20% by weight.

Here, the composition according to the present invention may contain 0.01 to 2 parts by weight of a fluorine element relative to 100 parts by weight of the total solid content, more specifically, may contain 0.1 to 1.5 parts by weight of a fluorine element have.

Here, the content of the fluorine element includes not only the content of the fluorine element contained in the fluorine compound but also the content of the fluorine element contained in the other compound of the composition.

When the fluorine element is contained in an amount of less than 0.01 part by weight based on 100 parts by weight of the total solid content, the glossiness is remarkably lowered and the appearance of the surface of the metal material can be difficult to be realized. When the fluorine element is more than 2 parts by weight, There is a fear that the coating film adhesion and the surface electrical resistance at the time of top coating are lowered.

Also, the composition according to the present invention may contain 1 to 30 parts by weight of zirconium element relative to 100 parts by weight of the fluorine element, specifically 1 to 20 parts by weight, more specifically 1 To 10 parts by weight.

When the zirconium element is contained in an amount of less than 1 part by weight based on 100 parts by weight of the fluorine element, the corrosion resistance may be lowered. When the zirconium element is contained in an amount exceeding 30 parts by weight, There is a concern.

The composition according to the present invention may contain a cerium element or a vanadium element. When the composition contains a cerium element, the content of the cerium element is not particularly limited. For example, 100 parts by weight of a fluorine element In an amount of 5 to 30 parts by weight, specifically 5 to 15 parts by weight, and more specifically 10 to 15 parts by weight, based on the total weight of the composition.

When the composition contains a vanadium element, the content of the vanadium element is not particularly limited. For example, the vanadium element may be contained in an amount of 5 to 40 parts by weight based on 100 parts by weight of the fluorine element. More specifically, To 20 parts by weight.

If the content of the cerium element or the vanadium element is out of the above-mentioned range, the corrosion resistance or the film adhesion can be deteriorated and the surface electrical resistance may increase.

Meanwhile, the composition according to the present invention may further comprise (D) a silane compound or a titanium compound. Such a compound can be used as a coupling agent for improving the adhesion with the material and the corrosion resistance by coupling the inorganic compound contained in the composition of the present invention.

Here, the silane compound may include all of the silicon element-containing materials, and the kind thereof is not particularly limited, and examples thereof include amino silanes, epoxy silanes, acrylic silanes, mercapto silanes, vinyl silanes, and mixtures thereof And the like.

More specifically, for example, the silane compound may be 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 1,2-bis-triethoxysilylethane, 3- (? -Aminoethyl) -? - aminopropylmethyldimethoxysilane, N- (? -Aminoethyl) -? - aminopropyltrimethoxysilane,? -Glycidoxypropyltriethoxysilane, ? -glycidoxypropylmethyldimethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane.

Further, as a specific example, the silane compound may be a mixture of a silane compound having a functional group capable of reacting with a horse-organic compound and a silane compound having no functional group.

More specifically, examples of the silane compound having a functional group capable of reacting with an organic compound include an amine-based silane compound and a glycidyl-based silane compound, and a silane compound having no organic functional group capable of reacting with an organic material, , 2-bistriethoxysilylethane, and the like. However, the silane compound used in the present invention is not limited to the above exemplified materials.

On the other hand, the titanium compound is not limited as long as it is a compound containing a titanium element, and may include, for example, at least one selected from the group consisting of titanium nitrate, titanyl sulfate and titanium lactate. However, the titanium compound according to the present invention is not limited to the above exemplified materials.

Meanwhile, the composition according to the present invention may have a pH of 3.0 to 5.0.

If the pH of the composition is less than 3.0, it may be difficult to produce an effective passivation film on the upper layer due to excessive etching reaction, thereby failing to exhibit corrosion resistance and lubrication characteristics. If the pH exceeds 5.0, The etching reaction may not be sufficient and defects may be formed which can not form an effective passive film on the upper layer, which may lower the corrosion resistance.

In addition, the composition according to the present invention may be added with an additive for controlling the pH to adjust the pH within the above-mentioned range, and the kind thereof is not particularly limited. For example, an inorganic acid such as phosphoric acid, Citric acid and the like may be added.

The invention also relates to a substrate; And a coating layer formed on the substrate, wherein the coating layer is formed by the composition according to the present invention.

In the metallic material according to the present invention, the " coating layer formed by the composition " means a dry coating layer formed on the substrate by surface treatment of the substrate using the composition, The method may include all of various surface treatment methods known in the art and includes, but is not limited to, for example, immersing the substrate in a surface treatment bath containing the composition, and then drying, Can be formed.

Here, the substrate may include a substrate of all metal materials on which surface treatment can be performed, and may be, for example, a metal sheet or the like, although the kind thereof is not limited.

The metal plate refers to a metal used for automobile materials, household appliances, building materials and the like, specifically, a metal such as an iron plate. Any steel plate commonly used in the art may be used for this purpose. For example, cold rolled steel sheets; Galvanized electroplated steel sheets such as galvanized steel sheets, zinc-nickel-plated steel sheets, zinc-iron-plated steel sheets, zinc-titanium-coated steel sheets, zinc-magnesium coated steel sheets, zinc manganese-coated steel sheets and zinc- Hot - dip galvanized steel; Aluminum-plated steel sheet; Magnesium-plated steel sheet; A plating steel sheet containing a different metal or an impurity such as cobalt, molybdenum, tungsten, nickel, titanium, aluminum, manganese, iron, magnesium, tin or copper in these plating layers; A coated steel sheet in which inorganic substances such as silica and alumina are dispersed in these plating layers; Or an aluminum alloy plate to which silicon, copper, magnesium, iron, manganese, titanium, zinc or the like is added; Magnesium alloy plate; Galvanized steel plates coated with phosphate; Or a hot-rolled steel sheet may be used. If necessary, a multi-layered plating plate obtained by sequentially treating two or more kinds of the above-mentioned platings may be used.

As a concrete example, the metal sheet may be a magnesium-coated steel sheet, a magnesium alloy sheet, an aluminum alloy sheet, or stainless steel, and more specifically, a magnesium-coated steel sheet or a magnesium alloy sheet.

As described above, the metal material according to the present invention can be usefully used in various industrial fields. For example, it can be used as an alloy for internal parts of electronic devices. That is, since the metal material according to the present invention has a low surface electric resistance and an excellent gloss that can maintain a beautiful appearance even after the rust-preventive treatment, it is excellent in resistance and decorative property when used as an alloy for internal parts of electronic devices Can be usefully used.

Here, the metal material according to the present invention may have a surface electrical resistance of 0.001 m? To 2?, Specifically 0.001 m? To 1?, More specifically 0.001 m? To 0.5?.

If the surface electrical resistance is less than 0.001 m OMEGA, the chemical reaction may not sufficiently take place, and other properties such as corrosion resistance may not be improved. When the surface electrical resistance is more than 2 OMEGA, surface electrical resistance is too high, It may be difficult to apply to a product which requires a low electric resistance such as an internal part of an electronic device.

In the present invention, the term " surface electrical resistance " means a physical quantity that indicates the degree of impeding the flow of current at the surface of the metal material.

Such a method for measuring the surface electrical resistance may include all methods for measuring the surface electrical resistance commonly used in the related art. Specifically, the surface electrical resistance may be measured using a surface electric resistance meter (Loresta GP, 4-probe) .

In addition, the metal material according to the present invention may have a 60 ° gloss grade of 200 GU to 400 GU, preferably 211 GU to 400 GU, more preferably 260 GU to 400 GU.

In the present invention, the " 60 ° gloss grade " means a value measured with a general gloss meter known in the art, with the buffing direction at an angle of 60 °.

As described above, when the measured 60 ° gloss grade is less than 200 GU, since it shows a low glossiness compared to the glossiness of the plate surface immediately after the buffing and hair line, it may be difficult to use in the glossy plate and the like, , The etching reaction may be excessively activated, the effective inorganic coating may not be smoothly performed, and the effect of improving the physical properties such as corrosion resistance and coating film adhesion may not be exhibited properly.

Here, the method for surface treatment of the metallic material according to the present invention may include all known surface treatment methods for forming a coating layer on a substrate by the above-mentioned composition, and is not particularly limited. For example, , A first step of immersing the substrate in a surface treatment bath containing the composition according to the present invention; And a second step of drying the immersed base material.

In this case, the time for immersing the substrate in the surface treatment bath in the first step is not particularly limited, and can be appropriately adjusted according to the method known in the art depending on the application and the content of the composition to be applied. However, For example, it may be carried out for 10 seconds to 40 seconds, more specifically for 10 seconds to 25 seconds.

If the immersion time is less than 10 seconds, the anti-rust treatment may not be performed well, and if it exceeds 40 seconds, the gloss and the film adhesion may be deteriorated.

In addition, a method of drying the immersed substrate may be various known drying and solidifying methods that can be used to form a coating layer on the substrate in this field, and the amount of the dried coating film is not particularly limited, , It can be applied with a dry coating amount of 10 to 1000 mg / m 2, specifically, 30 to 500 mg / m 2.

If the dry film amount is less than 10 mg / m 2, the corrosion resistance and workability may be reduced. If the dry film amount is more than 1000 mg / m 2, the weldability and lubricity may decrease.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited by the following examples.

[Example 1]

10 parts by weight of 0.06 mol of zirconium fluoride, 30 parts by weight of 0.1 mol of sodium vanadate and 40 parts by weight of 2.0 mol of hydrofluoric acid was mixed with 1000 mL of water to prepare a coating solution for metal surface treatment, A magnesium alloy sheet having a thickness of 0.6 mm was immersed for 20 seconds (bonderite NT-1, Henkel) to form a passive film. Next, the magnesium alloy sheet material was washed with water and then baked by passing through an oven at a temperature of 60 to 120 DEG C to produce a post-treated magnesium alloy sheet material.

[Examples 2 to 11]

A magnesium alloy sheet material was prepared in the same manner as in Example 1, except that the coating solution having the composition shown in Table 1 was used and the immersion time was changed.

The contents of the main metal components based on the contents of the fluorine elements contained in the coating solution used in Examples 1 to 11 are shown in Table 2 below.

Example A B C1 C2 D E1 E2 E3 E4 E5 E6 E7 pH Immersion time
(second) One 1000 10 - - 30 40 - - - - - - 3.50 20 2 1000 10 - - 60 40 5 10 4 - - 32 3.34 10 3 1000 10 10 40 60 80 - - - - - - 3.49 40 4 1000 10 10 40 60 56 - - - - - 16 4.30 20 5 1000 10 - - 60 28 - 20 - 10 - 16 4.20 10 6 1000 10 - - 45 56 - - - 10 - 32 4.14 10 7 1000 10 10 55 45 56 - 10 4 - - 64 3.41 10 8 1000 10 10 55 45 56 2 10 - 10 - 32 3.97 10 9 1000 10 10 55 - 120 - - - - - - 4.46 10 10 1000 15 10 40 45 40 5 20 10 20 - 32 3.87 10 11 1000 12 - 75 - 40 - - 20 10 4 48 3.68 10

Unit: parts by weight

A: water (H ₂ O)

B: Zirconium fluoride (ZrF ₄ ) 10 g / L

C1: the cerium compound 3 _{(Ce (NO 3) 3 (} Ⅲ) · 6H 2 O) 0.05 mol

C2: 3 and 4, the cerium compound is a cerium compound. 1: 1 mixture of _{(Ce (NO 3) 3 (} Ⅲ / Ⅳ) · 6H 2 O) 0.05 mol

D: sodium vanadium (NaVO ₃₎ 0.1 mol

E1: 2.0 mol of hydrofluoric acid (HF)

E2: 0.25 mol of hexafluorophosphoric acid (HPF ₆ )

E3: 0.5 mol of fluorophosphoric acid (H ₂ PO ₃ F)

E4: 0.5 mol of hexafluorozirconic acid (H ₂ ZrF ₆ )

E5: sodium hexafluoro titanate (Na ₂ TiF ₆₎ 0.08 mol

E6: zirconate as sodium hexafluoro carbonate (Na ₂ ZrF ₆₎ 0.2 mol

E7: 0.2 mol of fluorosilicic acid (H ₂ SiF ₆ )

Example Fluorine (F) Zirconium (Zr) Cerium (Ce) Vanadium (V) Titanium (Ti) Silicon (Si) One 100 3.48 - 9.77 - - 2 100 8.57 - 11.08 - 6.49 3 100 1.77 11.34 9.92 - - 4 100 2.15 13.79 12.06 - 3.53 5 100 3.10 - 17.43 2.19 5.10 6 100 1.82 - 7.66 1.28 5.98 7 100 5.98 11.50 5.80 - 9.06 8 100 1.73 14.46 7.29 1.22 5.70 9 100 1.18 9.88 - - - 10 100 15.77 10.29 6.75 2.26 5.27 11 100 26.26 13.15 - 0.96 6.73

Unit: parts by weight

 [Experimental Example]

1. Gloss test

A buffing process was performed only at an angle of 60 ° in the buffing direction using a gloss meter, and the value (GU) of the gloss of the magnesium alloy plate, which had not been subjected to the surface treatment, and the magnesium alloy plate according to Examples 1 to 11, The results are shown in Tables 3 and 4 below.

Evaluation criterion?: 260 or more,?: 211 to 260,?: 160 to 210, 占: 159 or less

2. Surface electrical resistance test

The surface electrical resistance (Ω) of the magnesium alloy sheet according to Examples 1 to 11 was measured with a surface electric resistance meter (Loresta GP, 4-probe) only for the buffing treatment and without the surface treatment And the results are shown in Tables 3 and 4 below.

Evaluation criterion?: 0.05 or less,?: 0.06 to 1.0,?: 1.1 to 1.5, x: 1.6 or more

3. Corrosion resistance test

The corrosion resistance of the magnesium alloy sheets according to Examples 1 to 11 was evaluated in accordance with the following evaluation criteria with the time point (time) of 5% tingling occurrence as a result of the salt spray test according to JIS Z2371 standard.

Evaluation criteria ⊚: more than 18, ∘: 12 to 18, Δ: 6 to 11, ×: less than 6

4. Coating film adhesion test

A dry film was formed on the magnesium alloy sheet materials according to Examples 1 to 11 using an Alkyd sintered curing paint, and spray coating was performed to a thickness of 20 to 25 탆. Subsequently, after curing for 15 minutes at a temperature of 15 to 160 캜 for more than 24 hours, it was precipitated in a constant temperature water bath at 98 캜 for 30 minutes, then taken out to remove moisture, left at room temperature for 2 hours, (1 × 1 mm 100 scale, cross-cut test). The results were evaluated as follows (after 3M tape peel test, 100 peeled patterns (the number of scales or equivalent area) box).

As a result, the film adhesion was as shown in Table 4.

Evaluation criterion?: 0 (peeled off),?: 1 to 2,?: 3 to 5, x: 6 or more

Color difference Glossiness
(60 DEG) Surface resistance
(Ω) L * a * b * negative 73.14 -0.62 6.82 262 0.051 10 ^-3 Example 1 78.25 -0.65 2.43 319 0.034 x 10 ^-3 Example 2 77.05 -0.38 2.99 266 0.035 x 10 ^-3 Example 3 78.21 -1.07 3.87 362 0.035 x 10 ^-3 Example 4 78.06 -0.38 3.30 297 0.034 x 10 ^-3 Example 5 75.64 -0.97 5.30 266 0.034 x 10 ^-3 Example 6 78.54 -0.77 2.70 284 0.034 x 10 ^-3 Example 7 79.08 -1.14 4.14 369 0.034 x 10 ^-3 Example 8 79.10 -0.75 3.43 333 0.034 x 10 ^-3 Example 9 78.46 -0.88 1.64 322 0.034 x 10 ^-3 Example 10 75.82 1.52 2.85 332 0.035 x 10 ^-3 Example 11 77.51 -0.71 5.18 345 0.034 x 10 ^-3

Glossiness Surface resistance Corrosion resistance Coating film adhesion Example 1 ◎ ◎ ○ ◎ Example 2 ◎ ◎ ◎ ◎ Example 3 ○ ◎ ○ ◎ Example 4 ◎ ◎ ○ ◎ Example 5 ◎ ◎ ◎ ◎ Example 6 ◎ ◎ ○ ◎ Example 7 ◎ ◎ ○ ○ Example 8 ◎ ◎ ○ ◎ Example 9 ◎ ◎ ○ ○ Example 10 ◎ ◎ ○ ◎ Example 11 ◎ ◎ ○ ◎

Claims (17)

(A) a fluorine compound; (B) a zirconium compound; And (C) at least one compound selected from a cerium compound or a vanadium compound, The content ratio of each component, (A) 100 parts by weight of a fluorine element, (B) the content of the zirconium element is 1 part by weight to 30 parts by weight relative to 100 parts by weight of the fluorine element, (C) the cerium and the vanadium element are contained in an amount of 5 to 30 parts by weight, based on 100 parts by weight of the fluorine element, of the cerium element; And 5 to 40 parts by weight of a vanadium element Compositions for surface treatment of magnesium alloys. The method according to claim 1, (A) the fluorine compound includes at least one selected from the group consisting of hydrofluoric acid, hexafluorophosphoric acid, fluorophosphoric acid, fluorosilicic acid, hexafluorozirconic acid, sodium hexafluorozirconate and sodium hexafluorotitanate ≪ / RTI > The method according to claim 1, (A) the fluorine compound comprises hydrofluoric acid. The method according to claim 1, (B) the zirconium compound is selected from the group consisting of zirconium fluoride, zirconyl nitrate, zirconyl acetate, zirconyl ammonium carbonate, zirconium acetylacetonate, potassium zirconium fluoride, zirconium oxide, zirconium hydrofluoric acid, zirconium ammonium fluoride and zirconium fluoride zirconium hydroxide ≪ / RTI > The method according to claim 1, (B) the zirconium compound comprises zirconium fluoride. The method according to claim 1, Wherein the cerium compound comprises at least one of a trivalent cerium compound, a tetravalent cerium compound, or a mixture thereof. The method according to claim 1, Wherein the vanadium compound is at least one selected from the group consisting of sodium vanadate, ammonium vanadium, vanadium nitride and vanadium oxide. The method according to claim 1, And 0.01 to 2 parts by weight of a fluorine element based on 100 parts by weight of the total solid content. delete delete delete The method according to claim 1, (D) a silane compound or a titanium compound. The method according to claim 1, wherein the pH is from 3.0 to 5.0. Magnesium alloy; And a coating layer formed on the magnesium alloy, Wherein the coating layer is formed by the composition according to any one of claims 1 to 8, 12 and 13. delete 15. The method of claim 14, And a surface electric resistance of 0.001 m? To 2?. 15. The method of claim 14, Wherein the 60 ° gloss grade is from 200 GU to 400 GU.