WO2017138714A1 - Alkaline conversion treatment composition for magnesium and magnesium alloy, and method for performing surface treatment on magnesium and magnesium alloy material by using same - Google Patents

Abstract

An alkaline conversion treatment composition for forming a conversion coating on the surface of magnesium and a magnesium alloy material can have a composition comprising 2-10 wt% of a phosphoric acid compound, 1-5 wt% of an inorganic metal sol, 0.03-0.3 wt% of a vanadium compound, 0.5-5 wt% of a basic compound, 0.01-0.1 wt% of an acrylic resin and the balance being a water-soluble solvent. The composition forms a uniform and dense conversion coating on the surface of magnesium and a magnesium alloy material while simultaneously providing corrosion resistance, top coat adhesion, and waterproof adhesion, and does not cause surface defects on the top coat.

Description

Alkaline conversion composition for magnesium and magnesium alloy and surface treatment method of magnesium and magnesium alloy material using same

The present invention relates to an alkali chemical conversion treatment composition for magnesium and magnesium alloys and a surface treatment method of magnesium and magnesium alloy materials using the same, and more particularly, magnesium and magnesium which are applied to give high corrosion resistance to the surface of magnesium or magnesium alloys. It relates to an alkali chemical conversion treatment composition for an alloy and a surface treatment method of magnesium and magnesium alloy material using the same.

 Magnesium is the 8th most abundant metal on the planet and is the lightest among the practical metals. It is excellent in specific strength, machinability and dimensional stability. In addition, magnesium alloy is excellent in electromagnetic shielding, heat dissipation, and vibration absorption has an advantageous advantage that can be applied to electronic devices or transportation equipment aimed at light weight. Recently, electronic devices such as computers, cameras, MP3s, mobile phones, and the like are being applied as structural materials for automobiles such as steering wheels, cylinder heads, ventilation fans, seat frames, and other applications.

As described above, the majority of metal material members (aluminum alloys, steel, magnesium alloys, etc.) used in automobiles, motorcycles, home appliances, and the like are required to be coated and used after various surface treatments because corrosion resistance and aesthetics are required. The purpose of the surface treatment is to remove the contaminants such as cutting oil and processing oil remaining on the surface of the material to form a dense chemical film, thereby providing corrosion resistance and paint adhesion.

The magnesium alloy member is painted after surface treatment as in the case of steel or aluminum alloy. Magnesium alloys are the most active and easily corrosive among practical metals. Also, because the surface of the magnesium alloy is chemically uneven, it is extremely difficult to form a dense and uniform chemical film.

In order to solve this problem, conventionally, a chemical treatment solution containing hexavalent chromium having excellent corrosion resistance has been used to secure corrosion resistance and paint adhesion (Japanese Patent No. 10-0869402), but such hexavalent chromium is fatal to humans. And its use is regulated because it causes environmental pollution problems. Therefore, in recent years, a method of forming a dense chemical conversion coating using a non-chromium chemical treatment solution containing no chromium has been applied to provide corrosion resistance and paint adhesion.

The non-chromium conversion treatment method includes at least one organic metal compound selected from metal alkoxides, metal acetylacetonates, and metal carboxylates, and any one of an acid, an alkali and salts thereof, or a hydroxyl group, a carboxyl group, or an amino group. "Metal surface treatment method (Japanese Patent Application Laid-open No. Hei 9-228062)" comprising at least one coating forming agent selected from organic compounds, a treatment method based on magnesium phosphate treatment, and zirconium other than chromium and titanium "Phosphate treatment" (Japanese Patent Publication No. 7-126858) which adds metals, such as zinc and zinc, etc. are mentioned. However, these chemical conversion compositions are impractical because of their long processing process, and require a long time for treatment, but cannot provide sufficient corrosion resistance, rust resistance, and coating film adhesion. It is easy to be affected and has a problem such as unstable performance.

In order to solve this problem, the applicant has applied for a patent on the chemical conversion composition for magnesium or magnesium alloy material and received a patent registration (10-1559285). This technique has the advantage of forming a high-performance chemical conversion film, but because the chemical conversion composition has an acidic property, magnesium is eluted quickly into the chemical conversion composition when the process of forming the chemical conversion coating is repeated. Melting of magnesium causes aging of the chemical conversion composition, which makes it difficult to continuously form a chemical conversion film having excellent corrosion resistance and water resistance.

An object of the present invention was conceived to overcome such a problem, and to form a uniform and dense chemical conversion coating on the surface of a magnesium or magnesium alloy material, and at the same time, an alkali chemical treatment composition having a significantly lower aging characteristic than an existing acidic chemical treatment solution was prepared. To provide.

Another object of the present invention has been conceived to overcome this problem, magnesium and magnesium to form a uniform and dense chemical conversion film after removing the contaminants and oxide layer on the surface of the magnesium or magnesium alloy material using an alkali chemical conversion treatment composition It is to provide a surface treatment method of the alloy material.

Alkali chemical conversion treatment composition for forming a chemical film on the surface of the magnesium and magnesium alloy material of the present invention for achieving the above object is 2 to 10% by weight phosphoric acid compound, 1 to 5% by weight inorganic metal sol, 0.03 to 0.3% by weight vanadium compound %, 0.5-5% by weight of basic compound, 0.01-0.1% by weight of acrylic resin, and excess water-soluble solvent.

In the surface treatment method of magnesium and magnesium alloy material to achieve another object of the present invention, the step of performing a degreasing process on magnesium and magnesium alloy material, using an acidic aqueous solution to the degreasing magnesium and magnesium alloy material Etching the surface, performing a desmut process to remove smut present in the etched magnesium and magnesium alloy materials, and using an alkali chemical conversion composition for magnesium alloys to the surface of the magnesium and magnesium alloy materials. It can be done by performing the step of forming a chemical conversion film. In this case, the chemical conversion film is 2 to 10% by weight of phosphoric acid compound, 1 to 5% by weight of inorganic metal sol, 0.03 to 0.3% by weight of vanadium compound, 0.5 to 5% by weight of basic compound, 0.01 to 0.1% by weight of acrylic resin and extra water-soluble It is preferable to form using the alkali chemicals treatment composition for magnesium and magnesium alloy containing a solvent.

The alkali chemical treatment composition for magnesium and alloy materials of the present invention having such a composition has a low elution of magnesium ions, thereby preventing deterioration of the alkali chemical treatment composition due to the chemical conversion process. A film can be formed. As a result, high corrosion resistance, excellent paint adhesion and water resistance can be imparted to the magnesium material without causing surface defects of the top coat film formed later.

1 is a graph showing the pH change of the chemical conversion treatment compositions of Example 1 and Comparative Example 11.

2 is an enlarged photograph of the microstructure of the chemical conversion film formed using the chemical conversion treatment composition of Example 1. FIG.

Hereinafter, the alkaline chemical treatment composition for magnesium and magnesium alloy and the surface treatment method using the same according to an embodiment of the present invention will be described in detail. As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Terms such as first and second 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 the second component, and similarly, the second component may also be referred to as the first component.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, 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. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, the alkaline chemical composition and the surface treatment method using the same according to an embodiment of the present invention will be described in detail.

Alkaline Chemical Composition for Magnesium and Magnesium Alloys

Existing chemical conversion compositions have acidic properties, so when magnesium material is dipped into the solution, magnesium continues to elute from the material to promote aging of the chemical conversion composition. Magnesium is not eluted from the substrate and the reactivity with the magnesium material is well controlled to form a chemical conversion coating film having excellent properties on the surface of the magnesium material even at room temperature.

As the alkali chemical conversion treatment composition of the present embodiment having the above-described characteristics, it has a composition containing a phosphoric acid compound, an inorganic metal sol, a vanadium compound, a basic compound, an acrylic resin, and a water-soluble solvent. As an illustrative example, the alkaline chemical composition for magnesium and magnesium alloy is 2 to 10% by weight phosphoric acid compound, 1 to 5% by weight inorganic metal sol, 0.03 to 0.3% by weight vanadium compound, 0.5 to 5% by weight basic compound, acrylic It has a composition comprising 0.01 to 0.1% by weight resin and excess water-soluble solvent.

As an example, the phosphoric acid compound included in the alkali chemical treatment composition is used to impart corrosion resistance to the chemical conversion film formed and to improve coating film adhesion.

Examples of the phosphate compound include first ammonium phosphate, second sodium phosphate, second potassium phosphate, orthophosphoric acid, and the like. The phosphoric acid compound may be used alone or in combination of two or more.

When the content of the phosphoric acid compound applied to the chemical conversion treatment composition according to the present invention is less than 2% by weight, a sufficient chemical conversion film is not formed, thereby making it difficult to secure corrosion resistance and paint adhesion. On the other hand, when the content is more than 10% by weight, an excessive chemical film is formed on the film, thereby improving corrosion resistance, but it is difficult to secure paint adhesion. Therefore, the phosphoric acid compound is preferably used 2 to 10% by weight, more preferably 3 to 9% by weight.

The inorganic metal sol applied to the alkali chemical conversion treatment composition according to the present embodiment is applied to secure corrosion resistance and to form a uniform chemical conversion film. Examples of the inorganic metal sol include silica sol, alumina sol, titania sol and zirconia sol. These can be used individually or in mixture of 2 or more.

As an example, Ludox of GRACE Corporation as silica sol in the inorganic metal sol  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  SNOWTEX of HSA, NISSAN CHEMICAL  ST-20L, SNOWTEX  ST-40, 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, SS-SOL 30SG, SS-SOL 30E, SS-SOL 30, SS-SOL 30F, SS-SOL 100, SS-SOL 30A, SS-SOL 20AM, SS-SOL 30OEAC, SS- SOL 30OMAC, SS-SOL 30OPAC, SS-SOL 20EG, SS-SOL 30EK, SS-SOL 30BK) and the like can be used. The alumina zolo (ALUMINASOL ^TM AS-100, ALUMINASOL ^TM AS-200, GerardKluyskens Co., Inc. Ultra-Sol 200A, Ultra-Sol 201A / 60, Ultra-Sol 201A / 280 from NISSAN CHEMICAL, Wesol A, Wesol from WESBOND) C12, Wesol D30) and the like. These can be used individually or in mixture of 2 or more.

At this time, if the amount of the inorganic metal sol contained in the composition according to the present invention is less than 1% by weight, there is a problem that the non-uniformity and corrosion resistance of the chemical conversion film are reduced, whereas when the content is more than 5% by weight, the water-resistant adhesion resistance is reduced. Problems are accompanied by a decrease in stability of the treatment composition. Therefore, the inorganic metal sol is preferably used at 1 to 5% by weight, more preferably at 1.5 to 4% by weight.

In addition, the vanadium compound applied to the alkali treatment 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, a vanadium oxide water may be a pentavalent, tetravalent or trivalent vanadium compound. For example, vanadium pentaoxide (V ₂ O ₅ ), metavanadine acid (HVO ₃ ), metavanadine Vanadium compounds with hexavalent oxides such as ammonium acid, sodium metavanadate, vanadium oxytrichloride (VOCl ₃ ), vanadium trioxide (V ₂ O ₃ ), vanadium dioxide (VO ₂ ), vanadium oxysulphate (VOSO ₄ ), vanadium Oxyacetylacetate VO (OC (= CH ₂ ) CH ₂ COCH ₃ )) ₂ , vanadiumacetylacetate V (OC (= CH ₂ ) CH ₂ COCH ₃ )) ₃ , vanadium trichloride (VCl ₃ ), invanadic molybdate Trivalent or tetravalent vanadium compounds, such as these, are mentioned. These can be used individually or in mixture of 2 or more.

At this time, when the vanadium compound contained in the composition according to the present invention is less than 0.03% by weight, corrosion resistance and self-healing effect cannot be obtained. On the other hand, when the content exceeds 0.3% by weight, the performance improvement is not confirmed and the increase in cost There is a problem that occurs. Therefore, the vanadium compound is preferably used at 0.03 to 0.3% by weight, more preferably 0.05 to 0.2% by weight.

The basic compound serves to increase the pH of the chemical conversion composition to make a more stable alkaline chemical composition, and examples thereof include sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, ammonium hydroxide and lithium hydroxide. These can be used individually or in mixture of 2 or more.

At this time, when the content of the basic compound is less than 0.5% by weight, the pH of the alkaline chemical composition may not be increased to a desired level. When the content of the basic compound exceeds 5% by weight, the pH of the alkaline chemical composition is increased so much that when the chemical is treated on the surface of the magnesium material There is a problem that the film is not formed. Therefore, the basic compound is preferably used at 0.5 to 5% by weight.

In addition, the acrylic resin applied to the alkali chemical conversion treatment composition according to an embodiment of the present invention improves the durability of the chemical conversion film to be formed, thereby forming a denser chemical conversion film and serves to improve water resistance. Examples of the acrylic resins include acrylic polyols, acrylic acid copolymers, modified acrylic acid copolymers, and polyacrylates. These can be used individually or in mixture of 2 or more.

At this time, if the content of acrylic resin is less than 0.01% by weight, the durability of the formed chemical film is lowered, resulting in poor adhesion and water-resistant adhesion, and when the content of the acrylic resin is more than 0.1% by weight, the chemical film is thickly formed due to excess resin, thereby degrading adhesion. There is this. Therefore, it is preferable to use acrylic resin within 0.01 to 0.1 weight% of range.

In particular, it is preferable that the alkali chemicals treatment composition according to the present embodiment has a pH of 8.5 to 10.5. When the pH of the alkali chemical treatment composition is less than 8.5, the reactivity of the magnesium alloy material is increased, so that the chemical conversion film is actively formed, but magnesium ions dissolve very rapidly on the surface of the material to promote aging of the solution. On the other hand, when the pH is 10.5 or more, the reactivity of the magnesium alloy material is significantly reduced, so that the formation of the chemical conversion film on the surface of the magnesium material is difficult.

Magnesium and its alloying composition having such a composition has a low elution of magnesium ions and prevents deterioration of the alkaline conversion composition due to the chemical conversion process, thereby forming a dense chemical coating film even after several times of reuse. can do. As a result, high corrosion resistance, excellent paint adhesion and water resistance can be imparted to the magnesium material without causing surface defects of the top coat film formed later.

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

The surface treatment method of the magnesium and magnesium alloy material according to the present invention can be made by performing a surface cleaning process and a chemical conversion process.

The surface clarification process is a step of removing contaminants (processing oil, oil, etc.) and oxide layer present on the surface of magnesium alloy as a step before chemical conversion to help to form a uniform and dense chemical film. ), The first washing process, the etching process, the second washing process, the de-must process, the third washing process.

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

The degreasing solution that can be used in the degreasing step is not particularly limited as long as it can remove organic contaminants. However, it is preferable to use an alkaline aqueous solution containing a surfactant. As an alkali builder of such a degreasing liquid, hydrate, phosphate, silicate, carbonate, etc. of an alkali metal can be applied. And as surfactant, any of nonionic, cationic, and anionic system can be applied. Moreover, you may mix | blend a chelating agent in order to improve the degreasing efficiency.

The temperature and time for contacting the degreasing liquid to the magnesium alloy is not particularly limited, but it is preferably carried out within 30 to 70 ℃, 2 to 10 minutes depending on the degree of contamination of the magnesium surface. The concentration of the degreasing liquid may also be appropriately set according to the contamination degree of the magnesium alloy surface, the degreasing liquid component and the like.

The first washing step is a washing step using water to remove the washing solution applied in the degreasing step. The first washing may be carried out by a method such as immersion, spray, dripping, etc., and may be performed using all kinds of water including deionized water, distilled water, pure water, and the like, and there is no particular limitation on the temperature range. However, it may preferably be carried out in the temperature range of 25 to 80 ℃. This is because the use of hot water washes the water more efficiently and improves the dehydration and drying property, thereby minimizing the inflow of water into the next process treatment tank and managing the treatment liquid. In addition, ultrasonic vibration may be applied to increase the cleaning effect when the washing step is performed.

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

As an example, the acidic aqueous solution is not particularly limited as long as it can dissolve and remove contaminants on the magnesium alloy surface. It is preferable to use sulfuric acid, phosphoric acid, hydrochloric acid, hydrofluoric acid, nitric acid, one kind or two or more kinds thereof. In order to improve the etching efficiency, organic acids may be mixed. Conditions such as the concentration of the acidic aqueous solution, the temperature, and the contact time with the magnesium alloy surface are not limited, and are appropriately adjusted according to the contamination degree of the magnesium alloy, the components of the acidic aqueous solution to be used, and the like.

The second washing step is a washing step using water to remove the acidic aqueous solution applied in the etching step. The second washing may be performed by a method such as immersion, spray, dripping, etc., and may be performed using all kinds of water including deionized water, distilled water, pure water, and the like, and there is no particular limitation on the temperature range.

In the surface cleansing process of the present invention, the de-must process is performed to remove the smut after the etching process remains on the magnesium alloy surface. Desmuth in the desmuth process can be performed by contacting the desmuth liquid with the magnesium alloy to be processed.

As an example, the desmut solution is not particularly limited as long as it can remove the smut remaining on the magnesium surface after the etching process, and strong alkali by mixing one or two phases of tartaric acid, ascorbic acid, gluconic acid, citric acid, oxalic acid, and the like. It is preferable to mix and use in aqueous solution (PH12 or more).

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

The third water washing step is a washing step using water to remove the residual desorbed smudge liquid applied in the dewatering smudge step. The third water washing may be performed by a method such as immersion, spray, dripping, etc., and may be performed using all kinds of water including deionized water, distilled water, pure water, and the like, and there is no particular limitation on the temperature range.

In another embodiment of the present invention, the etching and desmuth processes may not be performed in the surface cleaning process of unprocessed or unprocessed magnesium and magnesium alloy material.

The chemical conversion process according to the present invention is a process of forming a chemical conversion coating on the surface of the magnesium and magnesium alloy material having a cleaned surface by using the chemical conversion treatment composition. The alkali chemical conversion treatment composition of the present invention is 2 to 10% by weight of phosphoric acid compound, 1 to 5% by weight of inorganic metal sol, 0.03 to 0.3% by weight of vanadium compound, 0.5 to 5% by weight of basic compound, 0.01 to 0.1% by weight of acrylic resin and It may have a composition comprising excess water soluble solvent. A detailed description of the alkalizing treatment composition is disclosed in the detailed description of the present invention and will be omitted to avoid duplication.

At this time, the chemical conversion film is preferably formed to have a thickness of 0.1 to 2.5㎛. The coating film of 0.1㎛ or less has good coating adhesion, but the problem of corrosion resistance and water adhesion is greatly lowered. If the chemical coating of 2.5㎛ or more is formed, the corrosion resistance is excellent, but the coating adhesion and water resistance adhesion are deteriorated. . The thickness of the chemical conversion film as described above can be adjusted by adjusting the temperature and time of the chemical conversion treatment solution.

Magnesium and magnesium alloy material formed by performing the above-described surface treatment process may be used to replace automotive parts or other steel after the top coat. Top coat is an electrodeposition coating, it is desirable to have a drying process before coating the top coating because moisture on the surface of the magnesium alloy material may be mixed into the paint.

The drying is not particularly limited, it is preferable that hot air is preferred, and drying temperature in an oven to dry by a heater or an infrared heater or the like is carried out within 80 ~ 160 ^o C, 20 to 60 minutes. In addition, the drying conditions after electrodeposition coating may vary depending on the type and characteristics of electrodeposition paint,

In addition, the kind of paint used at the time of coating is not restrict | limited, You may use any of water system and a solvent system. The coating method of the coating material is not limited, and any coating method known in the art such as spraying, dipping and powder coating can be applied.

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

 Example 1 and Comparative Examples 1 to 11

Alkaline chemical treatment compositions containing the components shown in Table 1 were prepared in 1 L of distilled water, and an acidic chemical conversion composition containing the components disclosed in Table 2 was prepared.

Experimental Example 1

A magnesium alloy material (AZ31B plate material; ASTM standard, rolled plate, 70 mm X 140 mm X 0.8 mm AZ31B (high temperature press)) was prepared, respectively. Then, the prepared alloy material was subjected to the surface cleaning process under the conditions of Table 3 below. Test specimens were prepared by the process of forming chemical films, washing with water, and electrodeposition coating using chemical conversion treatment compositions prepared in Examples and Comparative Examples, respectively.

Electrodeposition coating condition

-Curing Condition: 160 ℃ x 40min

Coating thickness: 20 ± 5㎛

-Paint: RF-6900 F-1, F-2 (Noroo Auto Coating)

Paint adhesion evaluation

Using the alkali chemical conversion treatment compositions of Examples and Comparative Examples, respectively, the surface treatment process, the chemical conversion film formation process, and electrodeposition coating were carried out to prepare samples, and the coating adhesion of the specimens was evaluated. Here, the film adhesion was evaluated by the coating film remaining test by the cross film test (ASTMD3359, 1mm X 1mm, 100) by the Cross Cut Test (CCT) method. Evaluation criteria are shown in Table 4 below.

Adhesion Resistance Evaluation

After the water resistance test (40 ℃, 240 hours, immersion treatment) was evaluated by the coating film adhesion test (ASTMD3359, 1mm X 1mm, 100) by the Cross Cut Test (CCT) method. Evaluation criteria are shown in Table 3.

Corrosion Resistance Evaluation

Each specimen was evaluated for corrosion resistance by applying the salt spray method according to the method specified in ASTM B117. At this time, the specimens were put in an X-cut before the salt water test. The salt spraying time was set to 800 hours, and corrosion resistance after coating was evaluated by measuring one expansion width from the X-cut of each specimen after the completion of the salt spraying. Evaluation criteria are shown in Table 5 below.

Evaluation results of Examples and Comparative Examples

The coating film adhesion, the corrosion resistance, and the water adhesion resistance were evaluated by the same method as above for each of the specimens prepared by applying the chemical conversion treatment compositions of Example 1 and Comparative Examples 1 to 11, and the results are shown in Table 6.

1) Evaluation of physical property change according to the content of phosphate compound

As shown in Table 6 above, when the phosphoric acid compound was added (Example 1) as suggested by the present invention, all of the physical properties showed good or better results. On the other hand, when too little phosphate compound is added (Comparative Example 1), the chemical film is formed too thin, and the corrosion resistance is very large, and when too much phosphate compound is added (Comparative Example 2), the chemical film is formed too thick, resulting in coating adhesion. And the water resistance was reduced. From the above results, it was confirmed that the phosphate compound is very effective in forming the chemical conversion film and also has an effect on corrosion resistance and other physical properties when used within the scope of the present invention.

2) Evaluation of Property Change According to Inorganic Metal Sol Content

As shown in Table 6, when the inorganic metal sol (alumina sol) is added as suggested by the present invention, as shown in Example 1, all of the physical properties showed good or better results. On the other hand, Comparative Example 3, in which too little alumina sol, an inorganic metal sol was added, showed poor results in all physical properties, and Comparative Example 4, in which too much was added, showed poor results in some physical properties. It is confirmed that the inorganic metal sol should be used within the scope of the present invention in order to obtain a uniform coating because the inorganic metal sol affects the density or uniformity of the coating film when forming the chemical conversion film.

3) Evaluation of physical property change according to vanadium compound content

As shown in Table 6, when the vanadium compound (vanadium oxysulfate) is added as suggested by the present invention, as can be seen in Example 1, all of the physical properties showed more than good results. If the amount of the vanadium-based compound is too small, the problem of corrosion resistance is very poor as in Comparative Example 5, and if the content is too high as in Comparative Example 6, water adhesion and corrosion resistance are poor due to excessive formation of vanadium film. A problem occurred.

4) Evaluation of physical property change according to basic compound (sodium hydroxide) content

As shown in Table 6, when the basic compound (sodium hydroxide) is added as suggested by the present invention, as can be seen in Example 1, all of the physical properties showed more than good results. On the other hand, in the case of adding too little sodium hydroxide in Comparative Example 7, magnesium ions are melted in the magnesium alloy material to promote aging of the solution, and due to the thickened chemical film, all the physical properties are deteriorated. In Comparative Example 8, which is a case where too much is added, it was confirmed that the pH of the chemical conversion composition is increased so that a reaction does not occur during chemical conversion and thus it is not possible to secure desired physical properties.

5) Evaluation of physical property change according to acrylic resin content

As shown in Table 6, when the acrylic resin is added according to the present invention, Example 1 showed more than good results in all physical properties. In Comparative Example 9, in which the acrylic resin contained in the alkali chemical treatment composition is added too little, the water adhesion resistance is deteriorated, which causes the acrylic resin to form a more dense and durable chemical conversion film on the surface of the magnesium alloy. This is because it serves to improve. The problem of lowering the corrosion resistance and water tightness was caused, and in Comparative Example 10, in which too much was added, the effect could not be confirmed, and both the corrosion resistance and water tightness were deteriorated.

PH change of the chemical conversion composition of Example 1 and Comparative Example 11

The magnesium alloy material (AZ31B) was treated in a chemical conversion treatment composition having the composition of Example 1 and Comparative Example 11, respectively, to measure the pH change of the solution. The measurement result is shown in FIG.

The graph of FIG. 1 shows the pH change when a magnesium alloy material is continuously processed using each chemical conversion treatment composition (Example 1, Comparative Example 11). The X axis of the graph of FIG. 1 was expressed in terms of the amount of solution (m ² / L) per treatment area by continuously treating the magnesium alloy. In the case of Comparative Example 11, the pH increases rapidly as the treatment capacity of the magnesium alloy increases, but in the case of Example 1, the pH gradually decreases. In this case, in the case of Comparative Example 11, when the pH exceeds 5 or more, as described in the existing patent, physical properties are deteriorated, and thus it cannot be used as a chemical conversion treatment composition.

Aging Evaluation of Chemical Composition Compositions of Example 1 and Comparative Example 11

The 25 cm × 9 cm AZ31B material was evaluated in two chemical conversion compositions (Example 1, Comparative Example 11) before and after the chemical conversion. Magnesium alloy material was processed 50 sheets each of the chemical conversion treatment composition having the composition of Example 1 and Comparative Example 11 and then measured the contamination of the solution by ICP (inductively coupled plasma mass spectrometry) analysis. The measurement results are shown in Table 7.

Referring to Table 7, each chemical conversion composition (Example 1, Comparative Example 11) and Comparative Example 11 of the initial state is 0.15m ² / L solution having a pH of 5 or less and Example 1 has a processing capacity of 2.0m ² The solutions at the time of treatment up to / L were analyzed respectively. The results of the measurement showed that in Comparative Example 11, the treatment capacity was 0.15 m ² / L, but the concentration of magnesium ions increased rapidly, but in Example 1, magnesium ions were not detected even in the case of 2.0 m ² / L. Could be confirmed.

In addition, the initial physical properties of the chemical conversion treatment compositions of Comparative Example 11 and Example 1 and the physical properties of the composition after the chemical conversion treatment were measured and compared, respectively. The results are shown in Table 8.

Referring to Table 8, all of the initial physical properties of the chemical conversion treatment composition of Comparative Example 1, but in the case of Comparative Example 11 shows the same results as the initial physical properties up to 0.15m ² / L, after which the physical properties are deteriorated. On the contrary, in the case of Example 1, even up to 2.0 m ² / L of treatment capacity was equivalent to the initial physical properties. This is because, in the case of Comparative Example 11, the magnesium ions continued to melt during the continuous treatment of the chemical conversion, so that the pH of the solution increased and the solution rapidly aged. In the case of Example 1, the magnesium ions did not melt during the chemical conversion treatment. It was confirmed that the aging was hardly progressed.

2 is an enlarged photograph of the microstructure of the chemical conversion film formed using the chemical conversion treatment composition of Example 1. FIG.

As shown in FIG. 2, the microstructure of the chemical conversion film formed on the surface of the magnesium alloy material (AZ31B) by the first embodiment of the present invention has a unique structure and similar to the Dendrite structure.

Claims (11)

1. In the alkali chemical conversion treatment composition which is applied to form a chemical conversion film having corrosion resistance on the surface of magnesium and magnesium alloy material,

   Magnesium containing 2 to 10% by weight of phosphoric acid compound, 1 to 5% by weight of inorganic metal sol, 0.03 to 0.3% by weight of vanadium compound, 0.5 to 5% by weight of basic compound, 0.01 to 0.1% by weight of acrylic resin and extra water-soluble solvent, and Alkaline chemical conversion treatment composition for magnesium alloy.
2. The method of claim 1, wherein the phosphate compound is a compound that generates phosphate ions, magnesium characterized in that it comprises at least one selected from the group consisting of second sodium phosphate, first ammonium phosphate, second potassium phosphate and orthophosphoric acid And an alkali chemical conversion treatment composition for magnesium alloy.
3. The alkaline chemical composition for magnesium and magnesium alloy according to claim 1, wherein the basic compound comprises at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, ammonium hydroxide and lithium hydroxide.
4. According to claim 1, wherein the inorganic metal sol is at least one selected from the group consisting of silica sol, alumina sol, titania sol and zirconia sol, the alkali chemical conversion treatment composition for magnesium and magnesium alloy.
5. The method of claim 1, wherein the vanadium compound is vanadium pentoxide (V ₂ O ₅ ), metavanadate (HVO ₃ ), ammonium metavanadate, sodium metavanadate, vanadium oxychloride (VOCl ₃ ), Vanadium trioxide V ₂ O ₃ ), vanadium dioxide (VO ₂ ), vanadium oxysulphate (VOSO ₄ ), vanadiumoxyacetylacetate VO (OC (= CH ₂ ) CH ₂ COCH ₃ )) ₂ , vanadiumacetylacetate V (OC _{(= CH 2) CH 2 COCH} 3)) 3, 3 vanadium chloride (VCl _3), and invar Oxnard molybdenum magnesium comprises at least one selected from the group consisting of acids and alkaline magnesium alloy chemical conversion treatment composition.
6. According to claim 1, The acrylic resin is an alkali chemical conversion treatment composition for magnesium and magnesium alloy, characterized in that it comprises at least one selected from the group consisting of acrylic polyol, acrylic acid copolymer, modified acrylic acid copolymer and polyacrylate.
7. The alkaline chemical conversion treatment composition for magnesium and magnesium alloys according to claim 1, which has a value of 8.5 to 10.5 pH.
8. Performing a cleaning process on the magnesium and magnesium alloy material; And

   Using an alkali chemical conversion treatment composition to form a chemical conversion film on the surface of the magnesium and magnesium alloy material,

   The chemical conversion film is composed of 2 to 10% by weight of phosphoric acid compound, 1 to 5% by weight of inorganic metal sol, 0.03 to 0.3% by weight of vanadium compound, 0.5 to 5% by weight of basic compound, 0.01 to 0.1% by weight of acrylic resin and extra water-soluble solvent. Surface treatment method of magnesium and magnesium alloy material, characterized in that formed using an alkali chemical conversion treatment composition for magnesium and magnesium alloy.
9. The method of claim 8, wherein the cleaning process

   Degreasing magnesium and magnesium alloy materials;

   First washing with degreased magnesium and magnesium alloy material;

   Etching the surface of the magnesium and magnesium alloy material using an acidic aqueous solution;

   Second flushing the etched magnesium and magnesium alloy material;

   Performing a desmert process to remove smut present in the magnesium and magnesium alloy materials; And

   A surface treatment method of magnesium and magnesium alloy material, characterized in that it comprises the step of washing the magnesium and magnesium alloy material subjected to the desmut process.
10. The method of claim 8, wherein the cleaning process

    Degreasing magnesium and magnesium alloy materials; And

    A surface treatment method of magnesium and magnesium alloy material comprising the step of first washing the degreasing magnesium and magnesium alloy material.
11. 10. The method of claim 8, wherein the chemical conversion film is formed to have a thickness of 0.1 to 2.5㎛.

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