KR20150102208A - Conversion Coating Composition of Magnesium and Magnesium Alloy and Surface Treating Method Using The Same - Google Patents

Abstract

A chromium-free conversion treatment composition forming a conversion coating on a surface of magnesium and a magnesium alloy comprises: 2-10 wt% of a phosphoric acid compound; 0.2-1 wt% of a manganese ion compound; 1-5 wt% of inorganic metal sol; 0.03-0.3 wt% of a vanadium based compound; 0.005-0.05 wt% of a selenium based compound; 0.05-0.2 wt% of a fluorine based compound; and an extra water-soluble solvent. The composition forms a uniform and a dense conversion coating on the surface of the magnesium or the magnesium alloy; and applies corrosion resistance, a base coat adhesion, and water-resistance adhesion to prevent a surface defect of a base coat.

Description

TECHNICAL FIELD The present invention relates to a surface treatment method for magnesium and magnesium alloys, and a surface treatment method for magnesium and magnesium alloys using the same,

The present invention relates to a composition for treating a magnesium and magnesium alloy, and a method for treating a surface of magnesium and magnesium alloy using the magnesium and magnesium alloy, and more particularly, to a magnesium and magnesium alloy composition comprising magnesium and a magnesium alloy And to a surface treatment method of a magnesium and magnesium alloy material using the same.

 Magnesium is the eighth most abundant metal in the world. It is the lightest metal among practical metals, and has excellent non-strength, machinability and dimensional stability. In addition, the magnesium alloy has an advantage of being applicable to electronic devices and transportation equipment aiming at lightweight because of excellent electromagnetic wave shielding property, heat radiation property and vibration absorption property. Recently, it has been applied as an electronic device such as a computer, a camera, an MP3 player, a mobile phone, a structure for an automobile such as a handle, a cylinder head, a ventilation fan, and a seat frame, and other application fields are expected to increase sharply.

As described above, since the majority of metal material members (aluminum alloy, steel, magnesium alloy, etc.) used for automobiles, motorcycles, household appliances, etc. are required to have corrosion resistance and aesthetic appearance, they are painted after being subjected to various surface treatments. The purpose of the surface treatment is to remove contaminants such as cutting oil and processing oil remaining on the surface of the workpiece to form a dense chemical film to impart corrosion resistance and paint adhesion.

The magnesium alloy member is painted after surface treatment as in the case of steel or aluminum alloy. The magnesium alloy is the most active metal among the practical metals and has a property of being easily corroded. Moreover, since the surface of the magnesium alloy is chemically uneven, the magnesium alloy is an extremely difficult material to form a dense and uniform chemical film.

In order to solve such problems, conventionally, a chemical treatment liquid containing hexavalent chromium having excellent corrosion resistance has been used to secure corrosion resistance and paint adhesion (Japanese Patent Registration No. 10-0869402). However, such hexavalent chromium And its use is regulated because it causes environmental pollution problems. Therefore, recently, a method of imparting corrosion resistance and paint adhesion by forming a dense chemical conversion film using a chromium-free processing solution containing no chromium has been applied.

As the non-chromium conversion treatment method, at least one organometallic compound selected from a metal alkoxide, metal acetylacetonate and metal carboxylate and at least one compound selected from the group consisting of an acid, an alkali and a salt thereof, or a compound having any one of a hydroxyl group, (Japanese Unexamined Patent Publication No. Hei 9-228062) ", a treatment method based on magnesium phosphate treatment, and a method of treating at least one kind of film forming auxiliary selected from zirconium, titanium Phosphate treatment (Japanese Patent Publication No. Hei 7-126858) in which a metal such as zinc is added. However, these chemical conversion treatment compositions are impractical because they require a long treatment time, and require a long time for treatment. However, there is a problem that sufficient corrosion resistance, rust resistance and film adhesion can not be imparted. It is susceptible to influence and the performance is not stable.

Inventions relating to degreasing agents and chemical etching agents have also been reported to reduce the effect of nonuniformity of the material. Acid cleaning agent for magnesium alloy (Japanese Unexamined Patent Publication No. 53-102231), "" removing smut from the surface of magnesium alloy (Japanese Unexamined Patent Publication No. 6-220663), and the like. These inventions aim to remove the release agent, the working lubricant and the alloy segregation layer by etching the surface of the magnesium alloy. However, even if these methods are applied, it is difficult to form a dense and uniform chemical treatment film on the surface of magnesium, so that it is difficult to obtain excellent corrosion resistance and coating adhesion.

SUMMARY OF THE INVENTION An object of the present invention is to overcome such problems and to provide a method for forming a uniform and dense chemical conversion coating on the surface of a magnesium or magnesium alloy material and at the same time to provide a corrosion- Which is capable of providing a chemical conversion treatment composition capable of imparting a chemical conversion.

Another object of the present invention is to overcome this problem by using a chemical conversion treatment composition to remove contaminants (oil, oil, etc.) existing on the surface of a magnesium or magnesium alloy material and an oxide layer, And a method of surface treatment of a magnesium and magnesium alloy material.

The chromium-free treating composition for forming a chemical conversion coating on a surface of a magnesium and magnesium alloy material according to the present invention comprises 2 to 10% by weight of a phosphoric acid compound, 0.2 to 1% by weight of a manganese ionic compound, To about 5% by weight of a zeolite, from 0.03 to 0.3% by weight of a vanadium compound, from 0.005 to 0.05% by weight of a selenium compound, from 0.05 to 0.2% by weight of a fluorine compound and an extra water-soluble solvent.

In one embodiment, the phosphoric acid compound is a compound which generates a discrete ion and is a phosphate such as sodium phosphate monobasic, sodium phosphate monobasic, ammonium monophosphate, ammonium dibasic, potassium monophosphate, A compound, and an orthophosphoric acid.

In one embodiment, the manganese ionic compound is selected from the group consisting of manganese (II) sulfate, manganese (II) acetate, manganese (III) acetylacetonate, manganese sulfate, and the like.

In one embodiment, the inorganic metal sol may include at least one selected from the group consisting of silica sol, alumina sol, titania sol, and zirconia sol.

In one embodiment, the vanadium compound is selected from the group consisting of vanadium pentoxide (V ₂ O ₅ ), metavanadic acid (HVO ₃ ), ammonium metavanadate, sodium metavanadate, vanadium trichloride (VOCl ₃ ) , 3 vanadium oxide V ₂ O _3), dioxide, vanadium (VO _2), oxy-sulfate, vanadium (VOSO _4), vanadium oxy-acetyl acetate _{VO (OC (= CH 2)} CH 2 COCH 3)) 2, vanadium acetylacetate V ( _{OC (= CH 2) CH 2} COCH 3)) 3, 3 vanadium chloride (VCl _3), and invar Oxnard molybdate _{H 15 -X [PV 12 -xMoxO 40} ] o _{nH 2 o (6 <x <} 12, n < 30). &Lt; / RTI &gt;

In one embodiment, the selenium-based compound is selected from the group consisting of SeO2, SeS, H2Se, PbSe, H2SeO4, At least one selected from the group consisting of sodium (Na2Se), zinc selenide (ZnSe), phenyl selenide (C6H5SeCl), benzene selenic acid (C6H6O2Se), diphenyl selenide ((C6H5) 2Se2), methyl selenic acid (CH4O2Se) . &Lt; / RTI &gt;

In one embodiment, the fluorine-based compound is selected from the group consisting of ammonium fluoride (NH4F), hydrofluoric acid (HF), potassium fluoride (KF), sodium fluoride (NaF), sodium hydrogen fluoride (NaHF2) Potassium (KHF 2), ammonium hydrogen fluoride (NH 4 HF 2).

At this time, phosphoric acid, potassium hydroxide, or the like may be further added to the chemical conversion treatment composition so that pH is 3 to 5. [

According to another aspect of the present invention, there is provided a surface treating method for a magnesium and magnesium alloy material, comprising the steps of: performing a degreasing process on magnesium and a magnesium alloy material; Etching the surface of the deslated magnesium and magnesium alloy material using an acidic aqueous solution; Performing a desmutting process for removing the smut present in the etched magnesium and magnesium alloy materials, and forming a chemical conversion coating on the surfaces of the magnesium and magnesium alloy materials using the chemical conversion composition . Wherein the chemical conversion coating comprises 2 to 10 wt% of a phosphoric acid compound, 0.2 to 1 wt% of a manganese ion compound, 1 to 5 wt% of an inorganic metal sol, 0.03 to 0.3 wt% of a vanadium compound, 0.005 to 0.05 wt% of a selenium compound, 0.05 to 0.2% by weight of a fluorine-based compound and an excess of a water-soluble solvent.

According to the embodiment of the present invention having such a composition, the chemical conversion treatment composition of magnesium and its alloy material forms a dense chemical conversion coating on the surface of magnesium or magnesium alloy material to impart high corrosion resistance, top adhesion and water resistance, And does not contain chromium. The surface treatment method according to the present embodiment provides a magnesium alloy that has good aesthetic appearance, high corrosion resistance, excellent paint adhesion, and water resistance by performing a degreasing process, an etching process, a degasification process, and a chemical conversion process from a magnesium alloy material .

Hereinafter, a chemical conversion composition for magnesium and magnesium alloys according to an embodiment of the present invention and a surface treatment method using the same will be described in detail. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are further described in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a part or a combination thereof is described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

On the other hand, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, a chromium-free treating composition and a surface treatment method using the same according to an embodiment of the present invention will be described in detail.

Chemical composition for treating magnesium and magnesium alloy

The chemical conversion treatment composition of the present invention forms a uniform and dense chemical conversion coating on the surfaces of magnesium and magnesium alloy materials, thereby imparting high corrosion resistance, topcoat adhesion, and water resistance to water, and does not cause surface defects in top coating, Which has a composition containing a phosphoric acid compound that generates phosphate ions, a manganese compound that generates manganese ions, an inorganic metal sol, a vanadium compound, a selenium compound, and a fluorine compound.

In one embodiment, the chromium-free treating composition comprises 2 to 10 wt% of a phosphoric acid compound, 0.2 to 1 wt% of a manganese ion compound, 1 to 5 wt% of an inorganic metal sol, 0.03 to 0.3 wt% of a vanadium compound, 0.005 to 0.05% by weight, a fluorine-based compound of 0.05 to 0.2% by weight, and an extra water-soluble solvent.

The phosphoric acid compound contained in the chromium-free treating composition is used for imparting corrosion resistance to the chemical conversion film formed and for improving the film adhesion.

Examples of the phosphoric acid compound include phosphate compounds such as sodium phosphate monobasic, sodium phosphate dibasic, ammonium monophosphate, ammonium dibasic, ammonium monophosphate, potassium monophosphate, and potassium dibasic phosphate, and orthophosphoric acid. have. The phosphoric acid compound may be used singly or in combination of two or more thereof.

When the content of the phosphoric acid compound to be applied to the chemical conversion composition according to the present invention is less than 2% by weight, formation of a sufficient chemical conversion film is not carried out, and corrosion resistance and paint adhesion are difficult to secure. On the other hand, when the content exceeds 10% by weight, an excessive chemical conversion film is formed on the film to improve the corrosion resistance, but it is difficult to secure the coating adhesion. Therefore, the amount of the phosphate compound is preferably 2 to 10% by weight, more preferably 3 to 9% by weight.

The manganese compound contained in the chromium-free treating composition is used to cause manganese ions to be generated in the composition, so that the manganese ions are applied to promote the formation of a chemical conversion film on the surface of the magnesium material and to improve corrosion resistance.

Examples of the manganese compound include Manganese (II) sulfate, Manganese (II) acetate, Manganese (III) acetylacetonate, Manganese (II) nitrate, Manganese (II) chloride and Manganese sulfate. The manganese compounds may be used singly or in combination of two or more thereof.

When the content of the manganese compound applied to the chemical conversion composition according to the present invention is less than 0.2% by weight, the effect of improving the corrosion resistance of the chemical conversion coating film is insufficient. On the other hand, if it exceeds 1% by weight, the corrosion resistance and paint adhesion are satisfied but the water resistance is greatly reduced. Therefore, the manganese compound is preferably used in an amount of 0.2 to 1% by weight, more preferably 0.3 to 0.9% by weight.

 The inorganic metal sol to be applied to the chemical conversion composition according to the present invention is applied to ensure corrosion resistance and to form a uniform chemical conversion coating. Examples of the inorganic metal sol include silica sol, alumina sol, titania sol, and zirconia sol. These may be used singly or in a mixture of two or more.

In one example, the GRACE Company as Silica sol Among the inorganic metal sol ^{Ludox ® HS-30, Ludox ®} HS-40, Ludox ® TM, Ludox ® SM, Ludox ® AM, Ludox ® AS, Ludox ® LS, Ludox ® CL- X, Ludox ^® SK, Ludox ^® TMA, Ludox ^® PG, Ludox ^® CL, Ludox ^® CL - P, Ludox ^® DF, Ludox ^® FM, Ludox ^® HSA, SNOWTEX ^® ST - 20L and SNOWTEX ^® ST - 40 from NISSAN CHEMICAL ^{, SNOWTEX ® ST-50, SNOWTEX} ® ST-C, SNOWTEX ® ST-N, SNOWTEX ® ST-O, SNOWTEX ® ST-OL, SNOWTEX ® ST-ZL, SNOWTEX ® ST-PS-M, SNOWTEX ® ST-PS ^{-S, SNOWTEX ® ST-PS-} SO, SNOWTEX ® ST-OUP, SNOWTEX ® ST-UP, S-CHEMTECH 's SS-SOL 30SG, SS-SOL 30E, SS-SOL 30, SS-SOL 30F, SS-SOL SS-SOL 30E, SS-SOL 30OEAC, SS-SOL 30OMAC, SS-SOL 30OPAC, SS-SOL 20EG, SS-SOL 30EK and SS-SOL 30BK). In the alumina sol (NISSAN CHEMICAL's ^{ALUMINASOL TM AS-100, ALUMINASOL TM} AS-200, GerardKluyskens Co., Inc 's Ultra-Sol 200A, Ultra-Sol 201A / 60, Ultra-Sol 201A / 280, WESBOND 's Wesol A, Wesol C12, Wesol D30), and the like. These may be used singly or in a mixture of two or more.

 If the amount of the inorganic metal sol contained in the composition according to the present invention is less than 1% by weight, the non-uniformity and corrosion resistance of the chemical conversion coating may deteriorate. On the other hand, if the content exceeds 5% by weight, There arises a problem accompanied by a decrease in the stability of the treating composition. Therefore, the inorganic metal sol is preferably used in an amount of 1 to 5% by weight, more preferably 1.5 to 4% by weight.

Further, the vanadium compound applied to the chemical conversion composition according to the present invention is applied to further improve the corrosion resistance and to impart a self-healing effect to the magnesium alloy material.

As the vanadium compound, there can be used a vanadium compound in which the oxidation number of vanadium is 5, 4 or 3. Examples of the vanadium compound include vanadium pentoxide (V ₂ O ₅ ), metavanadic acid (HVO ₃ ), metavanadine Vanadium compounds having 5 oxidation groups such as ammonium ammonium, sodium metavanadate and vanadium trichloride (VOCl ₃ ); 3 vanadium oxide (V ₂ O _3), dioxide, vanadium (VO _2), oxy-sulfate, vanadium (VOSO _4), vanadium oxy-acetyl acetate _{VO (OC (= CH 2)} CH 2 COCH 3)) 2, vanadium acetylacetate V ( _{OC (= CH 2) CH 2} COCH 3)) 3, 3 vanadium chloride (VCl _3), Invar Oxnard molybdate _{H 15 -X [PV 12 -xMoxO 40} ] o _{nH 2 o (6 <x <} 12, n < 30) or the like can be given. These may be used alone or in combination of two or more.

 If the content of the vanadium compound contained in the composition according to the present invention is less than 0.03% by weight, the corrosion resistance and self-healing effect can not be obtained. On the other hand, if the content exceeds 0.3% by weight, There is a problem that occurs. Therefore, the vanadium compound is preferably used in an amount of 0.03 to 0.3% by weight, and more preferably 0.05 to 0.2% by weight.

The selenium-based compound contained in the chromium-free treating composition is applied to impart high corrosion resistance of the chemical conversion coating.

Examples of the selenium compound include selenium oxide (SeO2), selenium selenide (SeS), hydrogen selenide (H2Se), selenium lead (PbSe), selenic acid (H2SeO4), ascelenic acid (H2SeO3), sodium selenide Zinc selenide (ZnSe), phenyl selenide (C6H5SeCl), benzene selenic acid (C6H6O2Se), diphenyl selenide ((C6H5) 2Se2), and methyl selenic acid (CH4O2Se). These may be used alone or in combination of two or more.

 If the content of the selenium compound contained in the composition according to the present invention is less than 0.005% by weight, it is difficult to obtain the effect of improving the corrosion resistance. If the content exceeds 0.05% by weight, Therefore, it is preferable that 0.005 to 0.05% by weight of the selenium compound is used.

In addition, the fluorine-based compound contained in the chromium-free treating composition is applied to increase the chemical conversion film forming speed and to form a dense chemical conversion film to improve the water resistance.

Examples of the fluorine compound include ammonium fluoride (NH4F), hydrofluoric acid (HF), potassium fluoride (KF), sodium fluoride (NaF), sodium hydrogen fluoride (NaHF2), potassium hydrogen fluoride (KHF2) Ammonium hydrogen fluoride (NH4HF2), and the like. These may be used alone or in combination of two or more.

 If the content of the fluorine-based compound contained in the composition according to the present invention is less than 0.05% by weight, there is a problem that the rate of formation of a chemical conversion film is slow and the water resistance of the water-proofing property is deteriorated. When the content is more than 0.2% by weight, A film is formed and a precipitate is generated in the solution. Therefore, it is preferable that 0.05 to 0.2% by weight of the fluorine-based compound is used.

The chromium-free treating composition having the above-mentioned composition preferably has a pH of from 3 to 5. When the normalization treating composition does not satisfy the above-mentioned pH, it is preferable to add phosphoric acid or potassium hydroxide to adjust the pH. When the composition has a pH of less than 3, the reaction proceeds very rapidly when the magnesium alloy and the above-mentioned chemical treatment composition are in contact with each other. Thus, a non-uniform chemical conversion film and a chemical conversion film having a thickness of 3 μm or more are formed, Lt; / RTI &gt; On the other hand, when the pH exceeds 5, when the magnesium alloy and the above-described chemical treatment composition are brought into contact with each other, the rate of progress of the reaction is slowed and a chemical conversion film having a thickness of 0.01 탆 or less is formed. The chemical conversion film having a thickness of 0.01 탆 or less has a good coating adhesion but a significant deterioration in corrosion resistance and water resistance.

Hereinafter, a method of surface-treating a magnesium and magnesium alloy material according to an embodiment of the present invention will be described.

The surface treatment method of the magnesium and magnesium alloy materials according to the present invention can be performed by performing the surface cleaning process and the chemical treatment process.

The surface cleaning process is a process for removing contaminants (processing oil, oil, etc.) and an oxide layer existing on the surface of the magnesium alloy before the chemical conversion treatment to help form a uniform and dense chemical conversion film. The following degreasing (alkali degreasing ) Process, a primary washing process, an etching process, a secondary washing process, a hairless process, and a tertiary washing process.

In the surface cleaning process of the present invention, the degreasing process is a step of primarily removing the oil component and the working oil component on the surface of the magnesium alloy prior to the etching process.

The degreasing solution which can be used in the degreasing step is not particularly limited as long as it can remove organic contaminants, but it is preferable to use an alkaline aqueous solution containing a surfactant. The alkali builder of the degreasing liquid may be a hydrate of an alkali metal, a phosphate, a silicate, a carbonate, or the like. As the surfactant, any of a non-ionic surfactant, a cationic surfactant, and an anionic surfactant may be used. Further, a chelating agent may be added to improve the degreasing efficiency.

The temperature and time for bringing the degreasing liquid into contact with the magnesium alloy are not particularly limited, but it is preferably within a range of 30 to 70 ° C for 2 to 10 minutes depending on the degree of contamination on the surface of magnesium. The concentration of the degreasing liquid may also be appropriately set according to the degree of contamination on the surface of the magnesium alloy, the degreasing liquid component, and the like.

The first washing step is a washing step using water to remove the washing liquid applied in the degreasing step. The first flushing may be performed by a method such as dipping, spraying, or submerging. The flushing may be performed using all kinds of water including deionized water, distilled water, pure water, and the like. However, it may be preferably carried out at a temperature range of 25 to 80 캜. This is because, when hot water is used, it becomes flush more efficiently and the composition of dehydration drying improves, so that the inflow of water into the next processing tank is minimized and the treatment liquid can be easily managed. In addition, ultrasonic vibration may be applied to enhance the cleaning effect during the washing step.

In the surface cleaning process of the present invention, the etching process is performed in order to remove the surface of the magnesium alloy which is the object to be processed, when the surface of the magnesium alloy is excessively contaminated by the processing oil or when the oxide film layer is grown. The etching treatment in the etching process is carried out by bringing an acidic aqueous solution into contact with the magnesium alloy material to be treated.

For example, the acidic aqueous solution is not particularly limited as long as it can dissolve and remove contaminants on the surface of the magnesium alloy, and it is preferable to use one or more of sulfuric acid, phosphoric acid, hydrochloric acid, hydrofluoric acid, nitric acid, . An organic acid may be mixed to improve the etching efficiency. The conditions such as the concentration of the acidic aqueous solution, the temperature, and the contact time with the surface of the magnesium alloy are not limited and are appropriately adjusted according to the degree of contamination of the magnesium alloy, the component of the acidic aqueous solution used, and the like.

The second water washing step is a cleaning step using water to remove the acidic aqueous solution to be applied in the etching step. The second washing may be performed by a method such as dipping, spraying, or submerging, and may be performed using all kinds of water including deionized water, distilled water, pure water, and the like. There is no particular limitation on the temperature range.

In the surface cleaning process of the present invention, the demersal process is performed to remove the smut when the smut remains on the surface of the magnesium alloy after the etching process. The desmutting in the desmutting step can be carried out by contacting the desmutting liquid with the magnesium alloy to be treated.

As an example, the desmut liquid is not particularly limited as long as it can remove the smut remaining on the magnesium surface after the etching process. It is also possible to mix one or two sheets of tartaric acid, ascorbic acid, gluconic acid, citric acid, Aqueous solution (PH12 or higher).

The conditions such as the concentration of the desmut liquid, the temperature, and the contact time with the surface of the magnesium alloy are not particularly limited and may be appropriately adjusted according to the degree of the smut generated after the etching process, the desmut liquid component used, and the like.

The third washing step is a washing step using water to remove the residual desmutting liquid applied in the desmutting step. The third washing may be performed by a method such as dipping, spraying, or submerging. The washing may be performed using all kinds of water including deionized water, distilled water, pure water, etc., and there is no particular limitation on the temperature range.

As another embodiment of the present invention, etching and de-smutting processes may not be performed in a surface cleaning process of magnesium and magnesium alloy materials that are free of contamination or unprocessed in processing oil.

The chemical conversion treatment according to the present invention is a process for forming a chemical conversion coating on a surface of a magnesium and magnesium alloy material having a cleaned surface using a chemical conversion composition. The chemical conversion composition of the present invention comprises 2 to 10% by weight of a phosphoric acid compound, 0.2 to 1% by weight of a manganese ion compound, 1 to 5% by weight of an inorganic metal sol, 0.03 to 0.3% by weight of a vanadium compound, %, A fluorine-based compound of 0.05 to 0.2% by weight, and an excess of an aqueous solvent. A detailed description of the chemical conversion treatment composition is given in the detailed description of the present invention and is omitted in order to avoid redundancy.

At this time, the chemical conversion coating is preferably formed to have a thickness of 0.1 to 2.5 탆. The chemical conversion coating having a thickness of 0.1 탆 or less has a good coating adhesion but a significant deterioration in corrosion resistance and water resistance. When a chemical conversion coating having a thickness of 2.5 탆 or more is formed, corrosion resistance is excellent, but paint adhesion and water resistance are deteriorated . The thickness of the chemical conversion coating can be adjusted by adjusting the temperature and time of the chemical conversion solution.

The magnesium and magnesium alloy materials formed by performing the surface treatment process described above can be used for replacing automobile parts or other steel after top coating. Since the top coat is a powder coating, moisture on the surface of the magnesium alloy material may be adversely affected by the coating, so it is desirable to carry out the drying process before the top coat.

The drying is not particularly limited and it is preferable to perform oven drying with a hot air heater or an infrared heater, and the drying temperature is preferably within a range of 80 to 160 ^° C for 5 to 30 minutes. Further, the drying conditions after the powder coating can be changed depending on the kind and the characteristics of the powder coating material,

In addition, the type of coating material used for coating is not particularly limited, and any of a water-based or solvent-based coating material may be used. The coating method of the coating material is not limited, and any conventionally known coating method such as spraying, immersion, electrodeposition coating, and the like can be applied.

Hereinafter, the present invention will be described in more detail with reference to Examples, Experimental Examples and Evaluation Examples of the present invention, but the scope of the present invention is not limited by the following Examples.

 Examples 1 to 19 and Comparative Examples 1 to 14

Cr-free treating compositions containing the ingredients set forth in Table 1 below were prepared in 1 L of distilled water.

[Table 1]

<Experimental Example 1>

Magnesium alloy material (AZ31B plate: ASTM standard product, rolled plate, 70 mm X 140 mm X 0.8 mm AZ31B processed product (hot pressed product)). Thereafter, the surface of the prepared alloy material is subjected to the surface cleaning process under the conditions shown in Table 2 below. Then, the test pieces were prepared by forming the chemical conversion coatings using the respective chemical conversion coating compositions prepared in Examples and Comparative Examples, washing with water and powder coating. Powder coating conditions are as follows.

[Table 2]

Powder coating conditions

- Curing Condition: 180 ° C x 14min

- Coating thickness: 80 ㅁ 40㎛

- Paint: INTERPON (AKZONOVEL)

Evaluation of paint tightness

The chromium-free treating composition of each of the examples and comparative examples was used to perform the surface treatment process, the chemical conversion film formation process, and the powder coating process of Experimental Example 1 to prepare samples, and then the coating adhesion of the samples was evaluated. Here, the coating adhesion was evaluated by the coating adhesion test (ASTM D3359, 1 mm X 1 mm, 100 pieces) by the Cross Cut Test (CCT) method. The evaluation criteria are shown in Table 3 below.

 [Table 3]

Water resistance evaluation

(ASTM D3359, 1 mm x 1 mm, 100 pieces) by Cross Cut Test (CCT) method after 40 days of water resistance test (40 ° C, 240 hours immersion treatment) The evaluation criteria are shown in Table 3.

Corrosion resistance evaluation

The corrosion resistance of each specimen was evaluated by applying a salt spray method according to the method specified in ASTM B117. At this time, the exposures were placed in an X-cut before the brine test. The corrosion rate after coating was evaluated by measuring the expansion width of one side from the X-cut of each specimen after completion of the salt water spraying at 800 hours. The evaluation criteria are as shown in Table 4 below.

[Table 4]

Evaluation results of Examples and Comparative Examples

Coating film adhesion, corrosion resistance, and water resistance were evaluated through the above-described methods for the specimens prepared by applying the chemical conversion compositions of Examples 1 to 22 and Comparative Examples 1 to 12. The results are shown in Table 5.

[Table 5]

(1) Evaluation of change in physical properties according to phosphate content

As shown in Table 5, when the phosphoric acid compound was added (Examples 1 to 3) as proposed in the present invention, all of the properties were found to be good or better. On the other hand, when too little phosphoric acid compound was added (Comparative Example 1), all of the properties except for corrosion resistance were unsatisfactory. When too much phosphorus compound was added (Comparative Example 2), all properties except corrosion resistance were poor . As a result, it has been confirmed that the phosphate compound has an excellent effect on corrosion resistance and is effective in improving the paint adhesion and the water resistance when it is used in an appropriate amount.

(2) Evaluation of physical property change according to manganese compound content

As shown in Table 5, when the manganese-based compound was added as suggested in the present invention, the results of Examples 4 to 6 were higher than those of all the properties. On the other hand, Comparative Example 3, in which the manganese-based compound was added in an excessively small amount, showed good results in all properties other than corrosion resistance, and Comparative Example 4 in which excessive addition of the manganese based compound showed poor results in all properties except corrosion resistance.

The addition of a small amount of the manganese-based compound improves the corrosion resistance, and when too much amount is added, the formation of an excessive chemical conversion film results in poor coating adhesion and water resistance. This is because the manganese-based compound acts as a promoter of the chemical conversion film, so that the addition of a small amount improves the corrosion resistance, but the addition of a large amount causes an excessive chemical conversion coating.

3) Evaluation of physical property change according to inorganic metal sol content

As shown in Table 5, when the inorganic metal sol (alumina sol) was added as suggested in the present invention, as shown in Examples 7 to 9, all the properties were better than those of the inorganic metal sol (alumina sol).

On the other hand, Comparative Example 5, in which too little alumina sol was added as the inorganic metal sol, showed poor results in all properties, and Comparative Example 6, which was added too much, showed poor results in all properties. The inorganic metal sol is composed of a porous inorganic material. Such a porous inorganic material tends to absorb moisture. When the content is too high, the corrosion resistance and the water resistance are poor.

4) Evaluation of change of physical properties according to content of vanadium compound

As shown in Table 5 above, when the vanadium compound (vanadium oxysulfate) was added as suggested in the present invention, all the properties were better than those of Examples 10 to 12. That is, it was confirmed that the vanadium-based compound contained in the chrome-free treating composition had an influence on the corrosion resistance. If the amount of the vanadium compound is too small, corrosion resistance becomes very poor. If the content of the vanadium compound is too high as in Comparative Example 8, the formation of an excessive vanadium coating causes a problem of poor water resistance and corrosion resistance.

5) Evaluation of change of physical properties according to content of selenium compound

As shown in Table 5, when the selenium compound (selenium sulphide) was added as suggested in the present invention, as shown in Examples 13 to 15, all of the physical properties showed better results. It has been confirmed that the selenium-based compound contained in the chromium-free treating composition affects the corrosion resistance. On the other hand, Comparative Example 9, in which too little selenium compound is added, has a problem of lowering corrosion resistance and water resistance, and Comparative Example 10, in which too much selenium compound is added, has a poor water resistance.

6) Evaluation of change of physical properties according to content of fluorinated compound

As shown in Table 5, when the fluorine compound (ammonium fluoride) was added according to the proposal of the present invention, as shown in Examples 16 to 18, all the properties were better than those of the fluorine compound (ammonium fluoride). It has been confirmed that the fluorine-based compound contained in the chromium-free treating composition improves the water-resistant adhesion by forming a more dense chemical film on the surface of the magnesium alloy. On the other hand, Comparative Example 11, in which the fluorinated compound is added in an excessively small amount, has a problem in that corrosion resistance and water resistance are lowered. In Comparative Example 12 in which too much fluoride compound is added, all properties are deteriorated.

6) Evaluation of change of physical properties according to pH change of composition

As shown in Table 5, it was confirmed that the physical properties were changed according to the PH of the chrome-free treating composition. The lower the PH, the faster the reaction with the magnesium alloy resulted in the formation of an excessive chemical conversion film, thereby improving the corrosion resistance, but the coating adhesion and the water resistance were poor. That is, as the pH is higher than 6, the reaction with the magnesium alloy proceeds slowly, so that the formation of the chemical conversion film becomes thinner, and the corrosion resistance, paint adhesion, and water resistance are decreased. From these results, it is preferable that the pH range in which the paint adhesion and the water resistance are secured at a level of good corrosion resistance is 2 to 5, more preferably 2.5 to 4.

Claims (11)

A chemical conversion composition applied to form a chemical conversion coating having corrosion resistance on the surfaces of magnesium and magnesium alloy materials,
A selenium-based compound in an amount of 0.005 to 0.05% by weight, a fluorine-based compound in an amount of 0.05 to 0.2% by weight, a phosphoric acid compound in an amount of 2 to 10% by weight, a manganese ionic compound in an amount of 0.2 to 1% % &Lt; / RTI &gt; and an excess of water-soluble solvent. The method according to claim 1, wherein the phosphoric acid compound is a compound which generates a discrete ion and is selected from the group consisting of sodium phosphate monobasic, sodium phosphate monobasic, ammonium monophosphate, ammonium dibasic, ammonium monophosphate, monobasic potassium phosphate, And at least one selected from the group consisting of phosphate compounds such as potassium phosphate and orthophosphoric acid. The method of claim 1, wherein the manganese ion compound is selected from the group consisting of manganese (II) sulfate, manganese (II) acetate, manganese (III) acetylacetonate, manganese and at least one selected from the group consisting of magnesium, magnesium, and sulfate. The composition according to claim 1, wherein the inorganic metal sol comprises at least one selected from the group consisting of silica sol, alumina sol, titania sol, and zirconia sol. The method of claim 1, wherein the vanadium compound is at least one selected from the group consisting of vanadium pentoxide (V ₂ O ₅ ), metavanadic acid (HVO ₃ ), ammonium metavanadate, sodium metavanadate, vanadium trichloride (VOCl ₃ ) , 3 vanadium oxide V ₂ O _3), dioxide, vanadium (VO _2), oxy-sulfate, vanadium (VOSO _4), vanadium oxy-acetyl acetate _{VO (OC (= CH 2)} CH 2 COCH 3)) 2, vanadium acetylacetate V ( _{OC (= CH 2) CH 2} COCH 3)) 3, 3 vanadium chloride (VCl _3), and invar Oxnard molybdate _{H 15 -X [PV 12 -xMoxO 40} ] o _{nH 2 o (6 <x <} 12, n < 30). &Lt; / RTI &gt;&lt; Desc / Clms Page number 24 &gt; The method according to claim 1, wherein the selenium compound is selected from the group consisting of SeO2, SeS, H2Se, PbSe, Selenosan (H2SeO4), Selenium (H2SeO3) At least one selected from the group consisting of sodium (Na2Se), zinc selenide (ZnSe), phenyl selenide (C6H5SeCl), benzene selenic acid (C6H6O2Se), diphenyl selenide ((C6H5) 2Se2), methyl selenic acid (CH4O2Se) The composition according to claim 1, wherein the magnesium and magnesium alloy is a magnesium alloy.
The method of claim 1, wherein the fluorine-based compound is selected from the group consisting of ammonium fluoride (NH4F), hydrofluoric acid (HF), potassium fluoride (KF), sodium fluoride (NaF), sodium hydrogen fluoride (NaHF2) Potassium (KHF 2), and ammonium hydrogen fluoride (NH 4 HF 2). Performing a cleaning process on the magnesium and magnesium alloy materials; And
Forming a chemical conversion coating on the surfaces of the magnesium and magnesium alloy materials using a chemical conversion composition,
Wherein the chemical conversion coating comprises 2 to 10 wt% of a phosphoric acid compound, 0.2 to 1 wt% of a manganese ion compound, 1 to 5 wt% of an inorganic metal sol, 0.03 to 0.3 wt% of a vanadium compound, 0.005 to 0.05 wt% of a selenium compound, 0.05 to 0.2% by weight of a compound and an excess of a water-soluble solvent, and the magnesium and magnesium alloy treating composition is used for the surface treatment of magnesium and magnesium alloy materials. 9. The method of claim 8,
Degreasing the magnesium and magnesium alloy materials;
Subjecting the degreased magnesium and magnesium ingot material to first washing treatment;
Etching the surfaces of the magnesium and magnesium alloy materials using an acidic aqueous solution;
Subjecting the etched magnesium and magnesium alloy materials to a secondary wash treatment;
Removing the smuts present in the magnesium and magnesium alloy materials by performing a de-smith process; And
And subjecting the magnesium and magnesium alloy material subjected to the desmut process to a tertiary water washing treatment. 9. The method of claim 8,
Degreasing the magnesium and magnesium alloy materials; And
And treating the degreased magnesium and magnesium alloy material with a first water washing treatment. The surface treatment method of claim 8, wherein the chemical conversion coating is formed to have a thickness of 0.1 to 2.5 탆.