WO2015056985A1

WO2015056985A1 - Environmentally friendly chemical conversion treatment method of magnesium cast material, and magnesium cast material prepared thereby

Info

Publication number: WO2015056985A1
Application number: PCT/KR2014/009713
Authority: WO
Inventors: 박화영; 유형조; 백승관; 서만석
Original assignee: 주식회사 대동
Priority date: 2013-10-18
Filing date: 2014-10-16
Publication date: 2015-04-23
Also published as: KR101502915B1

Abstract

The present invention provides an environmentally friendly chemical conversion treatment method of a magnesium cast material for reducing wastewater treatment costs, facilitating the expression of the original color of a paint during painting and improving corrosion resistance and environmental resistance, comprising: a pretreatment step of removing impurities or segregation from the surface of a magnesium cast material; and a step of forming a fluoride film on the surface of the magnesium cast material, which has passed through the pretreatment step, by dipping the magnesium cast material into a solution containing at least one selected from the group consisting of ammonium hydrogen difluoride (NH₄HF₂) and sodium fluoride (NaF).

Description

Environmentally Friendly Chemical Treatment of Magnesium Castings and Magnesium Castings Prepared thereby

The present invention relates to a surface treatment method, and more particularly to an environmentally friendly chemical conversion treatment method of magnesium castings and magnesium castings produced thereby.

Magnesium is a light metal with a density of 1.73-1.95 g / cm ³ , about 1/4 of iron and about 2/3 of aluminum. Magnesium has excellent absorbency against vibration and shock, and is widely used as an automotive part or an aircraft part requiring heat reduction because steel has superior thermal conductivity, and its utilization in the global material market is increasing.

However, in spite of these various advantages, the chemical activity is large and the corrosion resistance is weak, so that the corrosion progresses rapidly in the air unless surface treatment is involved. Magnesium is used in the form of wrought materials, which can be subdivided into thin plates, thick plates, platens and forgings, and cast materials, which can be produced by die casting or sand casting, especially in castings. It is understood as a challenge to overcome. Currently, the surface treatment method of magnesium is metal plating method, anodizing, chemical conversion method, etc., and chemical conversion method is mainly used for productivity and unit price.

However, since the conventional chemical treatment method used for surface treatment of magnesium castings involves the process of forming phosphate coating, phosphorus (Phosphorus) is inevitably used in the pretreatment process and the fluoride coating process. There was a problem of providing a cause of water pollution by accelerating eutrophication and red tide in the water quality during wastewater treatment. In addition, in the case of the magnesium casting material in which the phosphate coating is formed, there is a problem that the coating quality is not good as dark gray.

The present invention is to solve the various problems including the above problems, to reduce the wastewater treatment costs, to improve the quality of the coating, to provide an environmentally friendly chemical conversion treatment method of magnesium casting material, further manufactured by such a method It is an object to provide a magnesium casting material. However, these problems are exemplary, and the scope of the present invention is not limited thereby.

According to one embodiment of the invention, the pretreatment step for the surface of the magnesium casting material; And immersing the magnesium casting material subjected to the pretreatment step in a solution containing acidic ammonium fluoride (NH ₄ HF ₂ ) or sodium fluoride (NaF) to form a fluoride film on the surface of the magnesium casting material. The pretreatment step may be performed in a solution containing 1% by mass to 3% by mass of hydrofluoric acid (HF), 3% by mass to 10% by mass of organic acid, 0.1% by mass or less of fluorine-based surfactant (Surfactant), and the remainder in water. Provided is a method for chemically treating a magnesium casting, comprising etching the surface of the magnesium casting by immersing the magnesium casting.

In the chemical conversion treatment method of the magnesium casting material, the magnesium casting material may be a magnesium alloy casting material containing aluminum, the magnesium alloy casting material containing aluminum may further contain zinc or manganese. That is, the magnesium casting may include an aluminum-containing Mg-Al-based alloy casting, an Mg-Al-Zn-based alloy casting or an Mg-Al-Mn-based alloy casting.

In the chemical conversion treatment method of the magnesium casting material, the magnesium casting material is AM60 series main alloy, AS41 series main alloy, AZ91 series main alloy, AM100 series main alloy, AZ63 series main alloy, AZ81 series main alloy, AZ92 series main alloy, AM20 series It can be a cast material comprising a main alloy, an AM50 series main alloy, or an AM60 series main alloy.

In the chemical conversion treatment method of the magnesium casting material, the solution containing the acidic ammonium fluoride is 7% by mass to 15% by mass of acidic ammonium fluoride, 5% by mass to 10% by mass of hydrogen peroxide (H ₂ O ₂ ), 3 It may be a solution containing from 7% by mass of sulfuric acid (sulfuric acid, H ₂ SO ₄ ), 0.005% by mass to 1% by mass of a fluorine-based surfactant, and the rest water (H ₂ O).

In the chemical conversion treatment method of the magnesium casting material, the solution containing sodium fluoride is 5% by mass to 10% by mass of hydrofluoric acid (HF), 10% by mass to 15% by mass sodium fluoride, 3% by mass to 7% by mass fluoride It may be a solution containing potassium (Potassium fluoride (KF)), 0.005% by mass to 1% by mass of a fluorine-based surfactant and water (H ₂ O) as the remainder.

In the chemical conversion treatment method of the magnesium casting material, the pretreatment step includes degreasing the surface of the magnesium casting material, first cleaning the surface of the degreased magnesium casting material, and etching the surface of the first magnesium casting material. A second cleaning of the surface of the etched magnesium casting material, a desmuting of the surface of the second magnesium casting material, and a third cleaning of the surface of the immersed magnesium casting material can do.

According to another embodiment of the present invention, there is provided a magnesium casting material comprising a fluorinated film formed by the above-described chemical conversion treatment method of the magnesium casting material.

According to the embodiments of the present invention made as described above, it is environmentally friendly because it does not use phosphorus (P), which caused water pollution by accelerating eutrophication and red tide in the water quality during wastewater treatment. In addition, since the brightness is higher than that of the magnesium cast material on which the phosphate film is formed, and the color is close to white, it is easy to express the primary color of the coating. The fluoride coating was formed on the surface of the magnesium casting to improve the corrosion resistance and environmental resistance of the magnesium casting. Environmentally friendly chemical conversion treatment and magnesium casting material produced thereby can be implemented. Of course, the scope of the present invention is not limited by these effects.

1 is a flowchart illustrating a chemical conversion treatment of a magnesium casting material according to an embodiment of the present invention.

Figure 2 is a flow chart illustrating in more detail the pretreatment step of the magnesium casting material according to an embodiment of the present invention.

Figure 3 is a flow chart illustrating in more detail the step of forming a fluoride film on the surface of the magnesium casting material according to an embodiment of the present invention.

Figure 4 is a flow chart illustrating in more detail the step of forming a fluoride film on the surface of the magnesium casting material according to another embodiment of the present invention.

Figure 5 is a flow chart illustrating in more detail the step of forming a fluoride film on the surface of the magnesium casting material according to another embodiment of the present invention.

Figure 6 is a flow chart illustrating in more detail the step of forming a fluoride film on the surface of the magnesium casting material according to another embodiment of the present invention.

7 is a photograph comparing the surface of the magnesium casting material formed with a phosphate coating and the surface of the magnesium casting material formed by immersing in a solution containing an acidic ammonium fluoride according to an embodiment of the present invention.

8 is a photograph comparing the surface of the magnesium casting material formed with a phosphate coating and the surface of the magnesium casting material formed by immersion in a solution containing sodium fluoride according to another embodiment of the present invention.

9 is a photograph showing the surface of the magnesium casting material according to each step in the pretreatment step of FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms, and the following embodiments are intended to complete the disclosure of the present invention, the scope of the invention to those skilled in the art It is provided to inform you completely. In addition, the components may be exaggerated or reduced in size in the drawings for convenience of description.

In embodiments of the invention, the pure magnesium casting or magnesium alloy casting may be referred to as magnesium casting. However, pure magnesium may further include impurities (hereinafter, inevitable impurities) that are intentionally added but inevitably contained during the manufacturing process, even if not specifically mentioned. In addition, the magnesium alloy may refer to an alloy containing one or more additional elements in magnesium as the main element, but such magnesium alloy may further include unavoidable impurities in addition to the main element and the additive elements even when not specifically mentioned. Can be.

Referring to FIG. 1, the method for chemically treating a magnesium casting includes pretreatment of the magnesium casting (S100) and forming a fluoride film on the surface of the magnesium casting (S200). In the pretreatment step S100, foreign matter or segregation on the surface of the magnesium casting material may be removed.

In wet air, the magnesium casting material tends to naturally form a passivation film (protective film) of 1 μm or less mainly composed of an oxide component formed of Mg (OH) _{2, which} is magnesium hydroxide. However, unlike other metal materials, the protective coating naturally formed on the surface of the magnesium casting is not stable. Looking at the ratio called the PB ratio (Pilling-Bedworth ratio), if a value of less than 1 is obtained, it means that the underlying metal layer is not completely covered.The passivation film of magnesium oxide has a value of 0.81, so the lower metal layer is not completely covered. It can be seen that. As another example, it can be seen that in the case of nickel, the PB ratio of the oxide is 1.65 and is completely covered by the oxide layer formed on the nickel. Magnesium protective coatings are not dense, so that corrosion of magnesium castings may accelerate over time.

In addition, when the magnesium casting is coated in the same manner as other metals, the corrosion resistance of the magnesium casting is greatly reduced. In particular, in the case of directly forming a coating made of another material on the protective coating formed on the magnesium casting, the corrosion resistance and / or paint adhesion of the magnesium casting may not be greatly improved due to the wettability of the interface with the protective coating. Therefore, it is necessary to form another film after strengthening the interfacial bonding force with the surface of the magnesium casting. Thus, when the interfacial force is strengthened and the film is formed through other treatments, the adhesion to the magnesium casting material is improved, and thus it may have excellent surface properties. Such strengthening of the interfacial bonding force with the magnesium casting material may be achieved through a pretreatment step of the magnesium casting material described later.

In one embodiment of the invention, the magnesium casting may comprise a magnesium alloy casting. The magnesium alloy casting material may be composed of a magnesium main alloy including aluminum in order to secure strength, castability and corrosion resistance. Furthermore, the magnesium master alloy containing aluminum may further contain zinc or manganese. That is, the magnesium main alloy containing aluminum may include, for example, Mg-Al main alloy, Mg-Al-Zn main alloy, Mg-Al-Mn main alloy, and the composition and manufacturing method (die casting, Sand mold and mold casting), AM60 series, AS41 series, AZ91 series, AM100 series, AZ63 series, AZ81 series, AZ92 series, AM20 series, AM50 series casting. Alloys and AM60 series main alloys.

Since the magnesium casting material including the Mg-Al-based alloy casting material, the Mg-Al-Zn-based alloy casting material or the Mg-Al-Mn-based alloy casting material described above does not include an active element such as lithium, It is known that it is not easy to form a fluoride film on the surface of the said magnesium casting material. In the embodiments of the present invention, the pre-treatment step (S100) of the magnesium casting to remove the surface defects of the magnesium casting and to flatten the surface by immersing the magnesium casting in a solution containing a fluorine-based surfactant (Surfactant) Thus, the fluorinated film can be easily formed on the surface of the magnesium casting including the Mg-Al-based alloy casting, the Mg-Al-Zn-based alloy casting, or the Mg-Al-Mn-based alloy casting.

Figure 2 is a flow chart illustrating in more detail the pre-treatment step (S100) of the magnesium casting material according to an embodiment of the present invention.

Referring to FIG. 2, the surface of the magnesium casting may be degreased to remove oil and contaminants on the surface of the magnesium casting (S110). Degreasing treatment consists of 5% by mass to 10% by mass of sodium hydroxide (NaOH), 1% by mass to 5% by mass of sodium gluconate (C ₆ H ₁₁ NaO ₇ ), and 1% by mass to 3% by mass of sodium carbonate (Na ₂ CO). ₃ ), 0.1% by mass to 0.3% by mass of the surfactant and the rest can be achieved by immersing in a mixed solution containing water (H ₂ O), after the degreasing treatment to remove the degreasing solution remaining on the surface of the magnesium casting In order to perform the first cleaning (S120). A photograph related to the degreased magnesium casting material is shown in FIG.

The surface of the first cleaned magnesium casting may have a release agent and an impurity oxide film. In order to remove the release agent and the impurity oxide film, the surface of the magnesium casting material may be etched (S130). Etching of the magnesium casting material is a mixed solution containing 1% by mass to 3% by mass of hydrofluoric acid (HF), 3% by mass to 10% by mass of organic acid, 0.1% by mass or less of fluorine-based surfactant, and the remainder with water (H ₂ O). It can be implemented by immersion in, the organic acid may include at least one selected from the group consisting of oxalic acid (citric acid), citric acid (citric acid), malonic acid (Malonic acid). Meanwhile, the organic acid may be replaced with an inorganic acid, and the inorganic acid may include sulfuric acid, nitric acid, hydrochloric acid, and the like.

In one embodiment of the present invention, the etching removes the oxide film (combined with oxygen in the air) on the surface of the magnesium casting material to form a target film (eg, chemical film, anodizing film or plating film) for a later process. It is an important preparation step. However, according to the composition of the mixed solution for immersion in the etching step, the amount of change in the size of the magnesium casting material varies from as few tens of microns to as many as hundreds of microns, it is very important to obtain a suitable composition. When etching using the above-described composition according to an embodiment of the present invention shows a dimensional change of about 10 ~ 30㎛ when treated for 30 seconds, and also the surface of the magnesium casting material by adding the fluorine-based surfactant of 0.1% by mass or less It was confirmed that it can provide excellent wettability and penetration while protecting.

In general, there was a problem of environmental pollution due to the effect of phosphorus (P), which causes eutrophication and red tide during wastewater treatment using phosphoric acid (Phosphoric acid) even during degreasing and / or etching according to an embodiment of the present invention, Since it contains at least one selected from the group consisting of environmentally friendly hydrofluoric acid, organic acid and inorganic acid that does not contain phosphorus (P), it is possible to eco-friendly manufacture of automobiles, aircraft materials, interior and exterior cases of portable devices, sporting goods and medical devices. Can be.

After the etching process, the surface of the magnesium casting may be secondly cleaned to remove the etching solution remaining on the surface of the etched magnesium casting (S140). A photograph relating to the etched magnesium casting is shown in FIG. 9 (b).

On the surface of the second cleaned magnesium casting, there may be left an insoluble impurity metal substituted on the surface during etching. In order to remove such an insoluble impurity metal, the surface of the magnesium casting material may be desmuted (S150). The dispersing step (S150) may include 30% by mass to 40% by mass of sodium hydroxide (NaOH), 3% by mass to 5% by mass of sodium gluconate (C ₆ H ₁₁ NaO ₇ ), and 5% by mass to 10% by mass. % Sodium carbonate (Na ₂ CO ₃ ) and the rest can be implemented by immersing the magnesium casting in a solution containing water (water) it can be removed insoluble impurity metal and the like. Photographs related to the discontinued magnesium casting are shown in FIG. 9 (c).

Subsequently, after the third step of washing the surface of the magnesium casting material (S160) to remove the dismist solution remaining on the surface of the magnesium casting material (S160), in forming a film through a chemical conversion treatment, Interfacial bonding force and adhesion between the coatings formed through the treatment can be improved. Therefore, a film with strong corrosion resistance and / or paint adhesion can be formed.

After the pretreatment step S100 of the magnesium casting material is finished, a fluorinated film may be formed on the surface of the magnesium casting material (S200, see FIG. 1). The fluoride film may be formed on the surface of the magnesium casting material by immersing in a solution containing at least one selected from the group consisting of acidic ammonium fluoride (NH ₄ HF ₂ ) and sodium fluoride (NaF).

Referring to FIG. 3, the forming of the fluoride film (S200) may include immersing the magnesium casting material in a solution containing acidic ammonium fluoride (NH ₄ HF ₂ ) (S210). Immersion in a solution containing acidic ammonium fluoride (S210) is 7 to 15% by mass of acidic ammonium fluoride, 5 to 10% by mass of hydrogen peroxide (hydrogen peroxide, H ₂ O ₂ ), 3% by mass to Magnesium castings may be immersed in a solution comprising 7 mass% sulfuric acid (H ₂ SO ₄ ), 0.005 mass% to 1 mass% fluorine-based surfactant, and the remainder water (H ₂ O). The 0.005% by mass to 1% by mass of the fluorine-based surfactant is, for example, a perfluoroalkyl chain represented by F- (CF ₂ -CF ₂ ) _n (n has a range of 3 to 8). Surfactant or fluorine (fluorine) comprising a may include a surfactant that forms a strong covalent bond with carbon (carbon). The solution containing the acidic ammonium fluoride reduces the surface tension of the solution containing the acidic ammonium fluoride by containing the fluorine-based surfactant to impart excellent wetting capacity to give a fine portion of the surface of the magnesium casting material. It can play an important role in forming a conversion coating, which is a fluoride coating.

When the magnesium casting material is immersed in a solution containing acidic ammonium fluoride, it is possible to form a metal oxide on the surface of the magnesium casting material by the following formula (1) and formula (2).

Formula 1

Formula 2

The metal oxide produced by Formulas 1 and 2 may include a material such as magnesium fluoride (MgF ₂ ), and the layer containing the metal oxide may be called a fluoride coating. In addition, the fluoride film is generated on the surface of the magnesium casting material after the pretreatment step (S100) can further improve the interfacial bonding force and adhesion with the magnesium casting material.

Magnesium fluoride (MgF ₂ ) produced in the embodiments of the present invention is poorly soluble in water, and may be resistant to various organic materials such as hydrocarbons, alcohols, aromatic compounds and esters. Therefore, the fluoride coating containing magnesium fluoride with improved interfacial bonding force and adhesion can protect magnesium castings in the long term.

Referring to FIG. 7, fluoride is immersed in a solution containing ammonium fluoride in acid compared to (b), which is a magnesium casting material in which a phosphate coating is formed using a phosphate solution containing phosphorus (P) that causes eutrophication in conventional wastewater treatment. It can be seen that the brightness of (a), which is the surface of the magnesium casting material on which the film was formed, is much higher, and is white or grayish white. Therefore, due to such chemical treatment, the coating quality may be improved while improving the corrosion resistance and environmental resistance.

Referring to FIG. 4, the forming of the fluoride film (S200) may include immersing the magnesium casting material in a solution containing sodium fluoride (NaF) (S220). In the step of immersion in a solution containing sodium fluoride, 5% by mass to 10% by mass of hydrofluoric acid (HF), 10% by mass to 15% by mass sodium fluoride, 3% by mass to 7% by mass of potassium fluoride (Potassium fluoride, KF), from 0.005% by mass to 1% by mass of a fluorine-based surfactant and, as a remainder, water (H ₂ O), can be immersed in the magnesium casting material, magnesium fluoride (MgF ₂ ) and And / or a metal oxide layer comprising a material such as NaMgF ₃ . Since the fluoride film including the metal oxide is formed on the surface of the magnesium casting after the pretreatment step (S100), it is excellent in the interfacial bonding force and adhesion with the magnesium casting material, it is possible to effectively protect the magnesium casting material.

On the other hand, the 0.005% by mass to 1% by mass of the fluorine-based surfactant is, for example, perfluoroalkyl chain represented by F- (CF ₂ -CF ₂ ) _n (n has a range of 3 to 8) Surfactant containing a chain or fluorine (fluorine) may include a surfactant in which a strong covalent bond with carbon (carbon). The solution containing sodium fluoride (NaF) lowers the surface tension of the solution containing sodium fluoride (NaF) by containing the fluorine-based surfactant to impart excellent wetting capacity to give magnesium casting material. It can play an important role in forming a conversion coating, which is a fluoride coating, even to a minute portion of the surface.

8 is a surface photograph of a magnesium casting material in which a fluoride film is formed by immersion in a solution containing sodium fluoride according to another embodiment of the present invention. Referring to FIG. 8, similar to that described with reference to FIG. 7, the chemical conversion treatment having much higher brightness and excellent corrosion resistance and environmental resistance can be performed as compared with the magnesium casting material of (b) in which the phosphate film was formed.

Referring to FIG. 5, the formation of the fluoride film may include a step (S230) of immersion in a solution containing sodium fluoride after the step (S210) of sequentially immersing in a solution containing acidic ammonium fluoride. After a layer including magnesium fluoride (MgF ₂ ) is formed on the surface of the magnesium casting by the reaction of Formulas 1 and 2, a metal oxide layer including NaMgF ₃ may be further formed. Forming the fluorinated coating in such a step, it is possible to obtain the effect of double chemical conversion treatment, compared to the natural oxidized passivation layer, the quality of the coating is excellent and resistant to various organic substances, corrosion resistance, environmental resistance and coating adhesion You can give it a surname.

Referring to Figure 6, the step of forming a fluoride film (S200) after the step of immersing in a solution containing the sodium fluoride (S220), the step of immersing in a solution containing the acidic ammonium fluoride (S240) It may include sequentially. Therefore, a metal oxide layer including NaMgF ₃ may be first formed on the surface of the magnesium casting material, and then a layer including magnesium fluoride (MgF ₂ ) may be formed. The metal oxide layer is a fluoride coating of magnesium casting material, which improves corrosion resistance and paint adhesion, and has a higher coating quality than the surface of a magnesium casting material formed by immersing only in a solution containing acidic ammonium fluoride or sodium fluoride to form a fluoride coating film. It can be excellent, and the corrosion resistance and environmental resistance can be significantly increased.

Furthermore, according to another embodiment of the present invention, a fluoride film is formed by the above-described chemical conversion treatment methods of the magnesium casting material, and a magnesium casting material including such a fluoride film can be provided.

On the other hand, a coating layer containing a metal may be further formed on the fluorinated coating film formed on the surface of the magnesium casting material as necessary, and the metal forming the coating layer may include Mn, Zr, V, Al, Zn, Ca, and Ce. It may include one or more selected from the group consisting of, and may react with magnesium ions on the surface of the magnesium casting to form a coating layer.

According to the embodiments of the present invention, a magnesium casting material having excellent paint quality and corrosion resistance and a method for manufacturing the magnesium casting material in an environmentally friendly manner can be provided to reduce wastewater treatment costs.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims

Pretreatment of the surface of the magnesium casting; And

And immersing the magnesium casting material subjected to the pretreatment in a solution containing acidic ammonium fluoride (NH 4 HF 2 ) or sodium fluoride (NaF) to form a fluoride film on the surface of the magnesium casting material.

The pretreatment step may be performed in a solution containing 1% by mass to 3% by mass of hydrofluoric acid (HF), 3% by mass to 10% by mass of organic acid, 0.1% by mass or less of fluorine-based surfactant (Surfactant), and the remainder in water. Etching the surface of the magnesium casting by immersing the magnesium casting;

Process for chemical conversion of magnesium castings.
The method of claim 1,

The magnesium casting material includes an Mg-Al-based alloy casting, an Mg-Al-Zn-based alloy casting or an Mg-Al-Mn-based alloy casting containing aluminum.
The method of claim 1,

The magnesium casting material is the AM60 series, AS41 series, AZ91 series, AM100 series, AZ63 series, AZ81 series, AZ92 series, AM20 series, AM50 series, or A method for chemical conversion of a magnesium casting, which is a casting containing an AM60 series main alloy.
The method of claim 1,

The pretreatment step,

Prior to etching the surface of the magnesium casting,

  Degreasing the surface of the magnesium casting material; And

  First cleaning the surface of the degreased magnesium casting material;

More,

After etching the surface of the magnesium casting,

  Second cleaning the etched surface of the magnesium casting;

  Desmuting a surface of the second cleaned magnesium casting material; And

  Third cleaning the surface of the magnesium sintered cast material;

Further comprising,

Process for chemical conversion of magnesium castings.
The method of claim 1,

The solution containing the acidic ammonium fluoride is 7% by mass to 15% by mass of acid ammonium fluoride, 5% by mass to 10% by mass of hydrogen peroxide (hydrogen peroxide, H 2 O 2 ), 3% by mass to 7% by mass of sulfuric acid ( sulfuric acid, H 2 SO 4 ), 0.005% by mass to 1% by mass of a fluorine-based surfactant, the remainder is a solution containing water (H 2 O), the method for chemical conversion of magnesium castings.
The method of claim 1,

The solution containing sodium fluoride includes 5% by mass to 10% by mass of hydrofluoric acid (HF), 10% by mass to 15% by mass sodium fluoride, 3% by mass to 7% by mass of potassium fluoride (KF), 0.005 A method for chemically treating a magnesium casting, which is a solution containing from 1% by mass to 1% by mass of a fluorine-based surfactant and water (H 2 O) as the remainder.
The method according to claim 5 or 6,

The 0.005% by mass to 1% by mass of the fluorine-based surfactant is an interface including a perfluoroalkyl chain represented by F- (CF 2 -CF 2 ) n (n has a range of 3 to 8). A method for chemically treating a magnesium casting, wherein the activator or fluorine comprises a surfactant in which a covalent bond with carbon is formed.
Magnesium casting material containing the fluoride film formed by the chemical conversion treatment method of the magnesium casting material of any one of Claims 1-6.