TWI534299B - A method for processing the surface of magnesium alloy - Google Patents

Description

Magnesium alloy surface treatment method

The present invention relates to a surface treatment method, and more particularly to a magnesium alloy surface treatment method.

It is found that magnesium metal is light in texture, density and elastic coefficient are similar to human periosteum, and have good mechanical properties, and at the same time are biodegradable substances. Therefore, magnesium alloy prepared by mixing magnesium metal with other metals, It has the potential to replace titanium alloys and stainless steels as biomedical materials.

However, due to the poor corrosion resistance of the conventional magnesium alloy, the degradation rate is too fast in the living body, and it is easy to generate excessive magnesium ions and hydrogen ions in a short time. Although magnesium ions can be utilized by the human body, the rapid production of hydrogen ions cannot be achieved. It is metabolized by the human body in a short time, and a large amount of hydrogen ions accumulated in the body will cause the pH value in the body fluid to change, causing insufficient oxygen carrying capacity of the hemoglobin and abnormal body reaction, which may cause harm to human health.

In view of this, it is necessary to provide a magnesium alloy surface treatment method to solve the problem that the degradation rate of the conventional magnesium alloy is too fast and harmful to human health.

The present invention provides a method of surface treatment of a magnesium alloy such that one of the surface treated magnesium alloys has a lower degradation rate.

The invention provides a surface treatment method for a magnesium alloy substrate, and the surface-treated magnesium alloy prepared by the method is suitable for use as a biomedical material.

A magnesium alloy surface treatment method comprises: preparing a magnesium alloy substrate; performing a micro-arc oxidation reaction on the magnesium alloy substrate to obtain a micro-arc magnesium oxide alloy, the surface of the micro-arc magnesium oxide alloy having a surface An oxide film; the micro-arc magnesium oxide alloy is immersed in a modified solution, the modified solution containing a decane compound until the decane compound in the modified solution is attached to the surface of the micro-arc magnesium oxide alloy to obtain a The reaction product is subjected to a condensation reaction at 70 to 200 ° C until the alkyl group and the hydroxyl group are dehydrated to obtain a surface-treated magnesium alloy, and the surface-treated magnesium alloy contains a condensation reaction. The oxide film, wherein the oxide film has a plurality of pores, and the micro-arc magnesium oxide alloy is immersed in water at 70-150 ° C until the plurality of pores of the oxide film are reduced before being immersed in the modified solution.

In the magnesium alloy surface treatment method of the present invention, the micro-arc magnesium oxide alloy is immersed in the modified solution for 1 minute to 5 hours.

In the method for surface treatment of a magnesium alloy according to the present invention, the reaction product is subjected to a condensation reaction at 70 to 200 ° C for 1 minute to 5 hours.

The magnesium alloy surface treatment method of the present invention, wherein the decane compound is 3-aminopropyltrimethoxydecane, thiolpropyltrimethoxydecane or hexamethyldiazepine.

The magnesium alloy surface treatment method of the present invention, wherein the modified solution contains 3 to 20% by volume of the decane compound.

In the magnesium alloy surface treatment method of the present invention, the micro-arc magnesium oxide alloy is immersed in the modified solution for 10 to 60 minutes to obtain the reactant.

The method for surface treatment of a magnesium alloy according to the present invention, wherein the reactant is subjected to a condensation reaction at 80 to 150 ° C for 20 to 60 minutes.

In the magnesium alloy surface treatment method of the present invention, the material of the oxide film is a group consisting of magnesium oxide, magnesium hydroxide and magnesium niobate.

In the method for surface treatment of a magnesium alloy according to the present invention, the thickness of the oxide film subjected to the condensation reaction is 5 to 50 mm.

The magnesium alloy surface treatment method of the present invention, wherein the condensation reaction oxide film has a first surface and a second surface, and the condensation reaction oxide film is bonded to the magnesium alloy substrate by the first surface, and The porosity of the inner surface of the oxide film subjected to the condensation reaction is from 0 to 5 mm from the second surface, and the porosity of the oxide film inside the condensation reaction is from 2 to 3% from 5 to 10 mm of the second surface. And the porosity of the inside of the oxide film subjected to the condensation reaction is less than 1% from 10 to 50 mm of the second surface.

In the magnesium alloy surface treatment method of the present invention, the micro-arc magnesium oxide alloy is immersed in water at 70-150 ° C for 1 minute to 5 hours before being immersed in the modified solution.

The magnesium alloy surface treatment method of the present invention, wherein the micro-arc oxidation reaction has a current density of 20 to 500 mA/cm ² , a pulse frequency of 500 to 5000 Hz, a duty ratio of 10 to 60%, and a time of 5 to 30. minute.

In the magnesium alloy surface treatment method of the present invention, the magnesium alloy substrate is placed in an electrolyte to perform the micro-arc oxidation reaction, and the pH of the electrolyte is alkaline.

The method for surface treatment of a magnesium alloy according to the present invention, wherein the electrolyte is prepared by adjusting sodium hydroxide, sodium phosphate, sodium metasilicate, a salt chelating agent and a calcium-containing salt.

The magnesium alloy surface treatment method of the present invention is produced by the above-described magnesium alloy surface treatment method.

The method for treating a magnesium alloy according to the present invention, wherein the magnesium alloy substrate is subjected to micro-arc oxidation reaction, immersed in the modified solution, and applied with thermal energy to obtain the surface-treated magnesium alloy, thereby achieving the slowing of the magnesium The efficiency of the degradation rate of the alloy substrate.

The surface-treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the invention has corrosion resistance and can be decomposed in the human body at an appropriate degradation rate, and is suitable for use as a biomedical material, and achieves the effect of avoiding human health hazards. .

〔this invention〕

S1‧‧‧ first surface

S2‧‧‧ second surface

Fig. 1A is a SEM image of the surface of the surface treated magnesium alloy No. 1-0 obtained by the surface treatment method of the magnesium alloy of the present invention.

Fig. 1B is a view showing the surface SEM image of the surface-treated magnesium alloy of Group 1-1 obtained by the surface treatment method of the magnesium alloy of the present invention.

Fig. 1C is a surface SEM image of the surface treated magnesium alloy obtained in the surface treatment method of the magnesium alloy of the present invention.

Fig. 1D is a surface SEM image of the surface treated magnesium alloy of Group 2-0 obtained by the surface treatment method of the magnesium alloy of the present invention.

Fig. 1E is a SEM image of the surface of the surface treated magnesium alloy obtained in the surface treatment method of the magnesium alloy of the present invention.

Fig. 1F is a surface SEM image of the surface treated magnesium alloy of Group 2-2 obtained by the surface treatment method of the magnesium alloy of the present invention.

Fig. 2 is a SEM image of a section 1-2 of the surface-treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention.

Fig. 3A is a surface image of the surface treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention before the salt spray test.

Fig. 3B is a surface image of the surface treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention before the salt spray test.

Fig. 3C is a surface image of the first to third groups of the surface-treated magnesium obtained by the surface treatment method of the magnesium alloy of the present invention before the salt spray test.

Fig. 3D is a surface image of the surface treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention in Groups 2-0 after the salt spray test.

Fig. 3E is a surface image of the surface-treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention after the salt spray test.

Figure 3F is a surface-treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention. Surface image of Groups 2-2 after salt spray test.

Fig. 4A is a surface image of the surface treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention before the salt spray test.

Fig. 4B is a surface image of the surface-treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention before the salt spray test.

Fig. 4C is a surface image of the surface-treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention before the salt spray test.

Fig. 4D is a surface image of the surface treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention after the salt spray test.

Fig. 4E is a surface image of the surface-treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention after the salt spray test.

Fig. 4F is a surface image of the surface treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention after the salt spray test.

Fig. 5 is a cross-sectional SEM image of a surface-treated magnesium alloy obtained by the surface treatment method of the magnesium alloy of the present invention.

The above and other objects, features, and advantages of the present invention will become more apparent from the aspects of the invention. The method comprises: preparing a magnesium alloy substrate; performing a micro-arc oxidation reaction on the magnesium alloy substrate to obtain a micro-arc magnesium oxide alloy; immersing the micro-arc magnesium oxide alloy in a modified solution to obtain a reaction to be reacted; and applying a heat to cause the reactant to undergo a condensation reaction to obtain a surface-treated magnesium alloy.

In detail, the material of the magnesium alloy substrate may be an alloy of magnesium metal and other metals, and other metals may be metals such as aluminum, zinc, manganese, lanthanum, cerium or zirconium. The magnesium alloy substrate can be used for casting, die casting, extrusion, forging or welding, etc., the material of the magnesium alloy substrate can be magnesium Aluminum alloy, magnesium manganese alloy, magnesium aluminum zinc alloy or magnesium zinc zirconium alloy, etc., specifically, the magnesium alloy substrate may be made of a magnesium alloy such as AZ31, AZ91 or ZK60, wherein the composition of AZ31 is in weight percent 3~3.2% aluminum, 0.8% zinc, 0.4% manganese, the remaining component is magnesium, and the composition of ZK60 is 6.3% zinc by weight, 0.49% zirconium, and the remaining component is magnesium, but the magnesium alloy The material of the substrate is not limited to this. Further, the magnesium alloy substrate may have any shape, for example, a block shape or a sheet shape, and the shape of the magnesium alloy substrate is not limited thereto. In this embodiment, the material of the magnesium alloy substrate may be AZ31 and ZK60, and the shape thereof is a sheet shape; further, when the AZ31 contains about 3% of a trace amount of aluminum, the magnesium alloy substrate may be increased. Corrosion resistance, but there is still doubt in the medical treatment of aluminum-containing metals, so it is better to select ZK60 which is not containing aluminum as the magnesium alloy substrate.

Preferably, the magnesium alloy substrate may be pretreated before the microarc oxidation reaction, the pretreatment comprises grinding the surface of the magnesium alloy substrate by using an abrasive member, and then grinding the magnesium alloy. The substrate was sequentially washed in an aqueous solution of 10% by volume of sodium hydroxide for 180 seconds, and washed with an aqueous solution of 96% by weight in acetic acid for 30 seconds, and the magnesium was washed with aqueous sodium hydroxide solution and aqueous acetic acid solution. The alloy substrate is immersed and dried with anhydrous alcohol to remove an oxide layer which may be dense on the surface of the magnesium alloy substrate to facilitate the subsequent micro-arc oxidation reaction.

The magnesium alloy substrate is continuously subjected to the micro-arc oxidation (MAO) to obtain the micro-arc magnesium oxide alloy. During the micro-arc oxidation reaction, the magnesium alloy substrate is thermochemically A strong reaction occurs under the combined action of electrochemistry and plasma chemistry, and undergoes melting, eruption, crystallization, and high-temperature phase transformation to form an oxide film on the surface of the magnesium alloy substrate, the oxide film having a plurality of pores. The main component of the oxide film is magnesium oxide. In this embodiment, the oxide film may be made of magnesium oxide (MgO), magnesium hydroxide (Mg(OH) ₂ ), and magnesium silicate (MgSiO ₄ , Mg). A group consisting of ₂ SiO ₃ ).

In detail, when the magnesium alloy substrate is subjected to the micro-arc oxidation reaction, the magnesium alloy substrate is placed in an electrolyte, and the magnesium alloy substrate is used as a positive electrode, and the negative electrode is a stainless steel sheet. A current is passed between the positive and negative electrodes to obtain the micro-arc magnesium oxide alloy. In detail, in the micro-arc oxidation reaction of the embodiment, a pulse current can be passed between the positive and negative electrodes, and the relevant parameters of the micro-arc oxidation reaction are as follows: the current density is 20~500 mA/ Cm ² , pulse frequency is 500~5000Hz, duty cycle is 10~60%, and the time is 5~30 minutes. Micro-arc oxidation of the magnesium alloy substrate is carried out by the parameters of the micro-arc oxidation reaction described above. The reaction can be such that the oxide film of the obtained micro-arc magnesium oxide alloy has appropriate corrosion resistance.

It is worth mentioning that the pH of the electrolyte is alkaline, and the electrolyte can be configured by a compound such as sodium hydroxide, sodium phosphate, sodium metasilicate, salt chelating agent and calcium salt. The composition of the electrolyte affects the material of the oxide film, as will be understood by those of ordinary skill in the art. In the embodiment, since the electrolyte is alkaline, the pollution to the environment can be reduced, and the effect of reducing the micro-arc oxidation reaction on the environment is reduced. Further, the compound for arranging the electrolyte is easily obtained. Therefore, the difficulty of the electrolyte configuration of the micro-arc oxidation reaction can be reduced, and the material of the magnesium alloy substrate is not limited in the present invention, and the micro-arc oxidation can be performed on various magnesium alloy substrates for medical or industrial use. reaction.

Preferably, the micro-arc magnesium oxide alloy can be placed in water at 70-150 ° C for cratering before immersing in the modified solution, thereby reducing the pore size of the oxide film and the time of the cratering reaction. It can be 1 minute to 5 hours, so that the oxide film can shield the outside water and oxygen to increase the corrosion resistance of the micro-arc magnesium oxide alloy. In the present embodiment, the micro-arc magnesium oxide alloy is immersed in water at 100 ° C for 15 to 30 minutes, and the micro-arc magnesium oxide alloy subjected to the cratering reaction is further dried at 60 ° C for 2 hours. Then, the crater-reduced and dried micro-arc magnesium oxide alloy is subjected to a decaneization reaction with the modified solution, and the reactant is formed.

The micro-arc magnesium oxide alloy is continuously immersed in the modified solution for 1 minute to 5 hours, and the micro-arc magnesium oxide alloy is subjected to surface sislation treatment to adsorb the decane compound on the surface of the micro-arc magnesium oxide alloy. And the reactant to be obtained is obtained. In detail, the modified solution The liquid comprises a monodecane compound having at least one silyl group. Specifically, the decane compound may be 3-aminopropyl triethoxysilane (APTES), sulfur. Alcohol propyl trimethoxysilane (MPTMS) or bis(trimethysilylamine, HMDS), etc., which has the function of forming an intermediate medium layer to select the decane The compound is based on, but not limited to, the above compound. In the present embodiment, the decane compound in the modified solution is thiolpropyltrimethoxydecane. Preferably, the micro-arc magnesium oxide alloy is immersed in the modified solution in a vacuum environment to prevent the modified solution from reacting with substances in the air to deteriorate. In the modified solution, if the volume percentage of the decane compound in the modified solution is too high, the bonding of the decane compound to the surface of the micro-arc magnesium oxide alloy is not easy, so the modified solution preferably comprises The decane compound is in a range of 3 to 20% by volume to reduce the failure of surface modification. In this embodiment, the micro-arc magnesium oxide alloy is immersed in the modified solution for 10 to 60 minutes to obtain the reaction to be reacted. Things.

After the reaction product is obtained, the reaction product is then subjected to a condensation reaction at 70 to 200 ° C. In this reaction, the decane compound adsorbed on the surface of the micro-arc magnesium oxide alloy is condensed with the micro-arc magnesium oxide alloy. The reaction is carried out until the decyl group of the decane compound and the hydroxyl group on the surface of the micro-arc oxidation-depleted alloy remove water, and the condensation reaction may be carried out for 1 minute to 5 hours. In detail, the surface of the micro-arc magnesium oxide alloy and the decane compound contain a hydroxyl group, and in the environment of 70-200 ° C, the hydroxyl group and the decyl group are condensed and evaporated. The water produced by the condensation reaction is used to obtain the surface-treated magnesium alloy, which comprises an oxide film which has undergone a condensation reaction. In the present embodiment, the reactant is subjected to condensation reaction at 80 to 150 ° C for 20 to 60 minutes to obtain the surface-treated magnesium alloy.

The surface-treated magnesium alloy of the present invention is obtained by the above-mentioned magnesium alloy surface treatment method, and the surface-treated magnesium alloy comprises the magnesium alloy substrate and the condensation reaction oxide film, and the condensation reaction is performed. The oxide film has a first surface and a second surface, the oxygen The chemical film is bonded to the magnesium alloy substrate by the first surface, and the second surface is away from the magnesium alloy substrate from the first surface, and the thickness of the condensation reaction oxide film is about 5 to 50 μm. Further, as the distance between the inside of the oxide film subjected to the condensation reaction and the second surface increases, the porosity inside the oxide film subjected to the condensation reaction gradually decreases, and in detail, the internal distance of the oxide film subjected to the condensation reaction is the same. The porosity of the two surfaces of 0 to 5 μm is 3 to 5%, and the porosity of the oxide film which is subjected to the condensation reaction is 2 to 3% by 5 to 10 μm from the second surface, and the internal distance of the oxide film by the condensation reaction is The porosity of the second surface of 10 to 50 μm is less than 1%, and the oxide film of the condensation reaction and the protective force of the germanium alkyl group on the magnesium alloy substrate can be increased by a special pore distribution relationship.

In order to confirm that the surface-treated magnesium alloy of the present invention does have good corrosion resistance to slow down the degradation rate, the following tests were carried out:

(A) Electrochemical analysis

In this test, the micro-arc magnesium oxide alloy (in order of groups 1-1 and 2-1) after the micro-arc oxidation reaction is applied to the magnesium alloy substrates of materials AZ31 and ZK60, respectively. Group 1-1 and Group 2-1 were successively immersed in the modified solution under vacuum and reacted in an oven at 100 ° C for 30 minutes to obtain the surface-treated magnesium alloy (in order of Group 1-2) And Group 2-2), further analyzed by electrochemical analysis method, and the magnesium alloy substrate of materials AZ31 and ZK60 was used as a control group (in order of Groups 1-0 and 2-0), the results were obtained. As shown in Table 1 below.

According to the above test, the corrosion current density of the sample made of AZ31 is from the smallest to the largest, the first to the 1-2th, the 1-1th, and the 1st to the 0th, and the sample is made of the ZK60. The corrosion current density is from small to large in order of groups 2-2, 2-1 and 2-0. It can be seen that the corrosion resistance of the micro-arc magnesium oxide alloy by micro-arc oxidation reaction is obviously superior to that of the magnesium alloy substrate, and the surface-treated magnesium alloy after continuous decaneization has higher corrosion resistance than the micro-arc magnesium oxide. The high alloys show that the magnesium alloy surface treatment method of the present invention can effectively alleviate the corrosion of the magnesium alloy substrate.

(B) SEM image

The surface SEM images were taken for the above groups 1-0, 1-1, 1-2 and 2-0, 2-1, and 2-2, and the results were as shown in Figs. 1A to 1F. In the test, the SEM image of the section was taken for the first group 1-2, as shown in Fig. 2. It can be seen from the SEM image that the surface of the micro-arc magnesium oxide alloy obtained by the micro-arc oxidation reaction is not flat, and it is shown that the groups 1-1, 1-2, 2-1 and 2-2 have the condensation reaction. An oxide film, and the oxide film of the condensation reaction has a plurality of pores. Further, it can be further seen from FIG. 2 that the thickness of the oxide film subjected to the condensation reaction is about 15 to 16 μm, and the thickness is condensed. The oxide film of the reaction has the ability to block external corrosion factors.

(C) Salt spray test

Tests for Groups 1-0, 1-1, 1-2, and Groups 2-0, 2-1, and 2-2 in accordance with ASTM B-117 Salt Spray Test Specifications, and pre-test samples and tests The subsequent samples were taken separately, and the correspondence between the samples and the images is shown in Table 2 and Table 3 below.

Table 3: Correspondence between image and sample in salt spray test of sample with ZK60

Please refer to the figures 3A~3F first. After the salt spray test, the surface of Group 1-0 with AZ31 is quite rusted, compared with Groups 1-1 and 1-2. After the salt spray test, there is no obvious rust on the surface. Please refer to the 4A~4F drawings. Similar results are also shown in the sample with ZK60. The corrosion of the sample in Figure 4D is obvious, and the 4E and The sample of the 4F chart showed no rust spots, and thus it was confirmed that the magnesium alloy surface treatment method of the present invention has the effect of improving the corrosion resistance of the magnesium alloy substrate.

(D) Image of pore distribution of oxide film

Please refer to FIG. 5 , which is a SEM image taken of the cross section of the surface-treated magnesium alloy. The oxide film of the condensation reaction can be clearly observed from FIG. 5 , and the condensation reaction is observed. The first surface S1 and the second surface S2 of the oxide film have a plurality of pores inside the oxide film subjected to the condensation reaction, and the distance between the inside of the oxide film and the second surface S2 is increased as the condensation reaction increases. The porosity inside the oxide film of the condensation reaction is gradually reduced. The pore distribution inside the oxide film subjected to the condensation reaction was analyzed, and it was confirmed that the inside of the oxide film subjected to the condensation reaction was 3 to 5% by the porosity of the second surface S2 0 to 5 μm, and the inside of the oxide film subjected to the condensation reaction The porosity of the second surface S2 5 to 10 μm is 2 to 3%, and the porosity of the inside of the oxide film subjected to the condensation reaction is less than 1% from the second surface S2 by 10 to 50 μm.

In summary, the magnesium alloy surface treatment method of the present invention comprises the micro-arc oxidation reaction of the magnesium alloy substrate, and the obtained micro-arc magnesium oxide alloy is continuously immersed in the modified solution to obtain the The reactants are finally subjected to a heat reaction by subjecting the material to be reacted to a condensation reaction to form the surface-treated magnesium alloy, and the corrosion resistance of the surface-treated magnesium alloy is remarkably improved, thereby further reducing the magnesium alloy substrate. The efficiency of the degradation rate, in addition, when the When surface-treated magnesium alloy is used as a biomedical material, it can be slowly decomposed to stably release hydrogen ions and magnesium ions, so that the human body will not accumulate too much hydrogen ions and cause a large change in blood pH value, thereby achieving the effect of avoiding human health hazards. .

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

Claims (15)

A magnesium alloy surface treatment method comprises: preparing a magnesium alloy substrate; performing a micro-arc oxidation reaction on the magnesium alloy substrate to obtain a micro-arc magnesium oxide alloy, the surface of the micro-arc magnesium oxide alloy having a surface An oxide film; the micro-arc magnesium oxide alloy is immersed in a modified solution, the modified solution containing a decane compound until the decane compound in the modified solution is attached to the surface of the micro-arc magnesium oxide alloy to obtain a The reaction product is subjected to a condensation reaction at 70 to 200 ° C until the alkyl group and the hydroxyl group are dehydrated to obtain a surface-treated magnesium alloy, and the surface-treated magnesium alloy contains a condensation reaction. The oxide film, wherein the oxide film has a plurality of pores, and the micro-arc magnesium oxide alloy is immersed in water at 70-150 ° C until the plurality of pores of the oxide film are reduced before being immersed in the modified solution. The magnesium alloy surface treatment method according to claim 1, wherein the micro-arc magnesium oxide alloy is immersed in the modified solution for 1 minute to 5 hours. The method for surface treatment of a magnesium alloy according to claim 1, wherein the reaction product is subjected to a condensation reaction at 70 to 200 ° C for 1 minute to 5 hours. The method for surface treatment of a magnesium alloy according to claim 1, wherein the decane compound is 3-aminopropyltrimethoxydecane, thiolpropyltrimethoxydecane or hexamethyldioxane. The magnesium alloy surface treatment method according to claim 1, wherein the modified solution contains 3 to 20% by volume of the decane compound. The magnesium alloy surface treatment method according to claim 1, wherein the micro-arc magnesium oxide alloy is immersed in the modified solution for 10 to 60 minutes to obtain the to-be-reacted material. The method for treating a magnesium alloy surface according to claim 1, wherein the reactant The condensation reaction is carried out at 80 to 150 ° C for 20 to 60 minutes. The method for treating a surface of a magnesium alloy according to claim 1, wherein the material of the oxide film is a group consisting of magnesium oxide, magnesium hydroxide and magnesium niobate. The method for treating a magnesium alloy according to claim 1, wherein the thickness of the oxide film subjected to the condensation reaction is 5 to 50 μm. The method for surface treatment of a magnesium alloy according to claim 1, wherein the oxidation reaction film has a first surface and a second surface, and the condensation reaction oxide film is bonded to the first surface The magnesium alloy substrate, and the inside of the oxide film subjected to the condensation reaction is from 0 to 5 μm from the second surface, and the porosity of the oxide film is 5 to 10 μm from the second surface. The ratio is 2 to 3%, and the porosity of the inside of the oxide film subjected to the condensation reaction is less than 1% from 10 to 50 μm from the second surface. The magnesium alloy surface treatment method according to the first aspect of the invention, wherein the micro-arc magnesium oxide alloy is immersed in water at 70-150 ° C for 1 minute to 5 hours before being immersed in the modified solution. The method for treating a magnesium alloy according to claim 1, wherein the micro-arc oxidation reaction has a current density of 20 to 500 mA/cm ² , a pulse frequency of 500 to 5000 Hz, and a duty ratio of 10 to 60%. And the time is 5~30 minutes. The magnesium alloy surface treatment method according to claim 1, wherein the magnesium alloy substrate is placed in an electrolyte to perform the micro-arc oxidation reaction, and the pH of the electrolyte is alkaline. The method for surface treatment of a magnesium alloy according to claim 13, wherein the electrolyte is prepared by adjusting sodium hydroxide, sodium phosphate, sodium metasilicate, a salt chelating agent and a calcium-containing salt. A surface-treated magnesium alloy obtained by the surface treatment method of the magnesium alloy according to any one of claims 1 to 14.