A method for preparing TiO2-MoS2 two-dimensional thin film on magnesium alloy surface

Abstract

The present invention relates to the field of new materials technology and discloses a method for preparing a two-dimensional TiO2-MoS2 thin film on the surface of a magnesium alloy, comprising pretreatment of the magnesium alloy and preparation of a TiO2-MoS2 composite thin film material, wherein the preparation of the TiO2-MoS2 composite thin film material comprises the steps of preparing an electrophoretic solution, electrophoretic deposition, and film cleaning. The TiO2-MoS2 two-dimensional thin film prepared by the present invention by electrophoresis combines the respective characteristics and advantages of two two-dimensional materials, TiO2 and MoS2, to form a novel multifunctional composite material, forming a dense nanofilm on the surface of the magnesium alloy, preventing the medium from contacting the magnesium alloy through the film, protecting the magnesium alloy, thereby extending the service life of the magnesium alloy, and having great application potential in fields such as new material corrosion protection.

Description

Technical Field

[0001] The present invention relates to the field of new material technology, and in particular to a method for preparing a TiO2-MoS2 two-dimensional thin film on the surface of a magnesium alloy. Background Art

[0002] Magnesium metal, a Group IIA element, is considered the best green material of the 21st century. Magnesium alloys, composed of magnesium doped with varying amounts of other alloying elements, possess excellent physical and chemical properties, including good biocompatibility, large hydrogen storage capacity, and high theoretical specific capacity for batteries. Consequently, they are considered promising for applications in aerospace, transportation, computing, and other fields. However, as structural materials, magnesium alloys suffer from low strength, poor plasticity, and poor corrosion resistance, limiting their widespread application.

[0003] Due to magnesium's relatively active chemical properties, low standard electrode potential, and poor protective ability of its natural oxide film, magnesium alloys have poor corrosion resistance. When magnesium alloys come into contact with other metals, they are easily corroded first due to their very low corrosion potential. On the other hand, magnesium alloys, like aluminum alloys, can quickly form an oxide film in the air. However, unlike aluminum alloys, the oxide film formed by magnesium alloys is not as dense as that formed by aluminum alloys. Instead, the film has pores on its surface, making it easy for the medium to enter the magnesium alloy. The medium connects the inside and outside to form a galvanic cell, causing electrochemical corrosion. The oxide film has poor protective properties. If the disadvantage of magnesium alloys being easily corroded can be overcome, the application and development of magnesium alloys in various fields will be greatly improved. Summary of the Invention

[0004] In response to the poor self-oxidation protection of the existing magnesium alloy surface mentioned in the background technology, the present invention provides a method for preparing a TiO2-MoS2 two-dimensional film on the surface of a magnesium alloy. The prepared film is dense and can effectively prevent the medium from entering the interior of the magnesium alloy, thereby extending the service life of the magnesium alloy, and solving the problems raised in the above background technology.

[0005] The present invention provides the following technical solution: a method for preparing a TiO2-MoS2 two-dimensional thin film on a magnesium alloy surface, comprising the following steps:

[0006] Step 1: Magnesium alloy pretreatment

[0007] Grinding and cleaning the magnesium alloy: using sandpaper to grind the magnesium alloy to remove the oxide film on the surface of the magnesium alloy to expose the matrix under the surface; cleaning and drying the polished magnesium alloy sample to obtain a magnesium alloy matrix with a clean surface;

[0008] Step 2: Preparation of TiO2-MoS2 composite film material

[0009] (1) Preparation of electrophoresis solution: Using a pipette, a solution of TiO2 and MoS2 in a ratio of 1:0.5 to 0.8 was dispersed in 100 mL of 70% ethanol solution. The solution was then ultrasonically stirred in an ultrasonic machine to uniformly disperse the TiO2 and MoS2 in the 70% ethanol solution to prepare a stable electrophoresis solution.

[0010] (2) Electrophoretic deposition: 5 mL of the prepared solution was taken each time for electrophoretic deposition. Two treated magnesium alloy substrates were placed in the solution as the anode and cathode, and the distance between the two electrodes was kept at 15 mm to 20 mm. A voltage was applied to the magnesium alloy substrates as the two electrodes to perform electrophoresis.

[0011] (3) Film cleaning: Take out the magnesium alloy sheet with the film after electrophoretic deposition, clean the excess precipitation on the surface with deionized water, put it into the furnace for heating after natural drying, and take out the sample after the furnace cools down.

[0012] Preferably, during the pretreatment of the magnesium alloy, the magnesium alloy is polished step by step using sandpapers of 400 mesh, 800 mesh, 1200 mesh and 1500 mesh, respectively.

[0013] Preferably, during the magnesium alloy pretreatment process, the sample is ultrasonically cleaned in water and ethanol for 10 minutes.

[0014] Preferably, during the preparation of the electrophoretic fluid, the ratio of TiO2:MoS2 in the mixed solution is 1:0.7.

[0015] Preferably, during the preparation of the electrophoresis fluid, the mixed solution is ultrasonically stirred for 30 minutes.

[0016] Preferably, during the electrophoretic deposition process, the electrophoretic deposition voltage and time are 20 V and 90 s respectively.

[0017] Preferably, during the film cleaning process, the furnace temperature is 150° C. and the drying time is 60 minutes.

[0018] The present invention has the following beneficial effects:

[0019] 1. The TiO2-MoS2 two-dimensional thin film prepared by the electrophoresis method of the present invention combines the respective characteristics and advantages of TiO2 and MoS2 two-dimensional materials to form a new type of multifunctional composite material. A dense nanofilm is formed on the surface of the magnesium alloy to prevent the medium from contacting the magnesium alloy through the film, thereby protecting the magnesium alloy and extending the service life of the magnesium alloy. It has great application potential in the field of new material corrosion protection.

[0020] 2. The present invention efficiently and directly generates a nano-film composed of TiO2 and MoS2 on the surface of a magnesium alloy by electrophoretic deposition, which has a wide range of applications in various fields such as corrosion protection and biomedical coatings. The present invention adopts a simple preparation method to form a complete protective film on the surface of a magnesium alloy, thereby improving the corrosion resistance of the magnesium alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Here are the XRD patterns of magnesium alloy, single-layer TiO2, single-layer MoS2, and TiO2-MoS2 thin films;

[0022] Figure 2 These are the SEM images of TiO2-MoS2 composite films after electrophoretic deposition of TiO2 and MoS2 solutions in different ratios: a) TiO2:MoS2 is 1:0.5;

[0023] b) TiO2:MoS2 is 1:0.6;

[0024] c) TiO2:MoS2 is 1:0.7;

[0025] d) TiO2:MoS2 is 1:0.8;

[0026] Figure 3 This is the polarization curve of TiO2-MoS2 thin film after electrophoretic deposition of TiO2 and MoS2 solutions with different ratios. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Example 1: Before electrophoresis, the magnesium alloy was polished and cleaned. First, both sides were polished with coarse 400-grit sandpaper to remove the oxide film on the surface of the magnesium alloy, exposing the underlying substrate. The sample was then polished in successive grades using 800-, 1200-, and 1500-grit sandpaper. After polishing, the sample was ultrasonically cleaned in deionized water and ethanol for 10 minutes each, then removed and dried to obtain a smooth magnesium alloy substrate.

[0029] Then use a pipette to take 1 mL of the prepared TiO2 and disperse it in 100 mL of 70% ethanol solution. Then, according to the ratio of TiO2:MoS2 of 1:0.5, take 0.5 mL of 1.0 mg / mL MoS2 dispersion and drop it into the above solution. Then put it into an ultrasonic machine and stir ultrasonically for 30 minutes to make TiO2 and MoS2 evenly dispersed in the 70% ethanol solution to make a stable electrophoresis solution.

[0030] Each time, 5 mL of the prepared solution was taken for electrophoretic deposition. Two treated magnesium alloy substrates were placed in the solution as anode and cathode, and the distance between the two electrodes was kept at 15 mm to 20 mm. A fixed voltage of 20 V was applied to the two electrodes to energize them. After 90 seconds of electrophoretic deposition, a very thin TiO2-MoS2 film was deposited on the anode. The power was disconnected, and the magnesium alloy sheet with the film was taken out. The excess precipitation on the surface was washed with deionized water. After natural drying, it was placed in a furnace at 150 ° C and heated for 60 minutes. The sample was taken out after the furnace cooled down.

[0031] Example 2: Compared with Example 1, the difference is that 0.6 mL of MoS2 dispersion with a concentration of 1.0 mg / mL is dropped into 1 part of the solution, and the ratio of TiO2:MoS2 is 1:0.6.

[0032] Example 3: Compared with Example 1, the difference is that 0.7 mL of MoS2 dispersion with a concentration of 1.0 mg / mL is dropped into 1 solution, and the ratio of TiO2:MoS2 is 1:0.7.

[0033] Example 4: Compared with Example 1, the difference is that 0.8 mL of MoS2 dispersion with a concentration of 1.0 mg / mL is dropped into 1 part of the solution, and the ratio of TiO2:MoS2 is 1:0.8.

[0034] See Figure 1 As shown, there are XRD patterns of single-layer TiO2, single-layer MoS2 and TiO2-MoS2 thin films of magnesium alloy. In the figure, single-layer MoS2 has characteristic peaks at 7.6° and 21.68°, and the peak values ​​are very low, indicating that the crystallinity of MoS2 is low. The characteristic peaks of single-layer TiO2 appear at 7.1° and 15.46°. From the curve with TiO2-MoS2 thin film sample, it can be seen that in addition to the characteristic peaks of magnesium alloy, new characteristic peaks appear at 7.1°, 7.6°, 15.46° and 21.68°, which just correspond to the diffraction peaks of single-layer TiO2 and single-layer MoS2, indicating that TiO2-MoS2 thin film is successfully prepared on the surface of magnesium alloy.

[0035] Figure 2 The SEM images of TiO2-MoS2 composite films with different ratios (TiO2:MoS2) deposited by electrophoresis are shown in Figure 2. Figure 2 As can be seen in a, the TiO2-MoS2 composite film with a TiO2:MoS2 ratio of 1:0.5 covers the surface of the magnesium alloy very completely and evenly. The nanosheets are connected to form a honeycomb shape, but the distribution is not uniform, the honeycombs are of different sizes, and the composite film is not dense.

[0036] When TiO2:MoS2 is 1:0.6 ( Figure 2 b) The openings of the honeycomb-shaped composite film become smaller and cover the magnesium alloy surface more densely.

[0037] With the increase of MoS2 content, when TiO2:MoS2 is 1:0.7 ( Figure 2 c) The composite film no longer has a honeycomb shape and has become very dense, completely isolating the magnesium alloy surface from contact with air or corrosive substances, forming a good protective barrier.

[0038] Continue to increase the MoS2 content to TiO2:MoS2 1:0.8 ( Figure 2 d) The composite film has tiny honeycomb openings and small protrusions on the surface. This may be because the MoS2 content increases and the interaction force between TiO2 and MoS2 increases, causing the composite film to be not dense enough.

[0039] In summary, when the TiO2:MoS2 ratio is 1:0.7, the composite film is the most complete and dense, completely covering the entire surface of the magnesium alloy, and can serve as an effective barrier to protect the surface of the magnesium alloy.

[0040] The corrosion behavior of each sample in NaCl solution was evaluated by scanning the potential dynamic polarization curve in 3.5 wt % NaCl solution. Figure 3 Polarization curves of TiO2-MoS2 films with different ratios (TiO2:MoS2) deposited by electrophoretic deposition. The corrosion potentials of TiO2-MoS2 composite film samples obtained by electrophoretic deposition of TiO2:MoS2 at 1:0.5, 1:0.6, 1:0.7 and 1:0.8 were -1.26V, -1.18V, -1.0V and -1.07V, respectively. The corresponding corrosion current density first decreased and then increased, and was 8.26×10 -7 A.cm -2 , 6.93×10 -7 A.cm -2 , 3.69×10 -7 A.cm -2 and 5.37×10 -7 A.cm -2 Among them, the TiO2-MoS2 composite film prepared when the TiO2:MoS2 ratio was 1:0.7 had the most positive corrosion potential of -1.00 V and the smallest corrosion current density of 3.69×10 -7A.cm -2 Compared with the sample with TiO2 film, the corrosion potential of the magnesium alloy after electrophoretic deposition of TiO2-MoS2 composite film shifted positively by 0.27V, and the corrosion current density decreased by 71.4%. This shows that the sample with TiO2-MoS2 composite film obtained when the electrophoretic deposition TiO2:MoS2 ratio was 1:0.7 had the highest corrosion resistance. This is because the TiO2-MoS2 composite film prepared when the TiO2:MoS2 ratio was 1:0.7 was the most dense. It can be seen that TiO2-MoS2 composite film can improve the corrosion resistance of magnesium alloy and greatly slow down the corrosion rate of magnesium alloy. The corrosion resistance of TiO2-MoS2 composite film is the best when the electrophoretic deposition TiO2:MoS2 ratio is 1:0.7.

[0041] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0042] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a TiO2-MoS2 two-dimensional thin film on a magnesium alloy surface, characterized in that: The following steps are involved: Step 1: Magnesium alloy pretreatment Grinding and cleaning the magnesium alloy: using sandpaper to grind the magnesium alloy to remove the oxide film on the surface of the magnesium alloy to expose the matrix under the surface; cleaning and drying the polished magnesium alloy sample to obtain a magnesium alloy matrix with a clean surface; Step 2: Preparation of TiO2-MoS2 composite film material (1) Preparation of electrophoresis solution: Use a pipette to take a solution of TiO2 and MoS2 in a ratio of 1:0.5-0.8 and disperse it in 100 mL of 70% ethanol solution. Then put it into an ultrasonic machine for ultrasonic stirring to make TiO2 and MoS2 evenly dispersed in the 70% ethanol solution to obtain a stable electrophoresis solution. (2) Electrophoretic deposition: Take 5 mL of the prepared solution each time for electrophoretic deposition. Place two treated magnesium alloy substrates in the solution as anode and cathode, and keep the distance between the two electrodes at 15 mm to 20 mm. Apply voltage to the magnesium alloy substrates as the two electrodes and perform electrophoresis. (3) Film cleaning: Take out the magnesium alloy sheet with the film after electrophoretic deposition, clean the excess precipitation on the surface with deionized water, dry it naturally, put it in the furnace for heating, and take out the sample after the furnace cools down.

2. The method for preparing a two-dimensional TiO2-MoS2 thin film on a magnesium alloy surface according to claim 1, characterized in that: During the pretreatment of the magnesium alloy, the magnesium alloy was polished step by step using sandpapers of 400 mesh, 800 mesh, 1200 mesh and 1500 mesh respectively.

3. The method for preparing a two-dimensional TiO2-MoS2 thin film on a magnesium alloy surface according to claim 1, characterized in that: During the magnesium alloy pretreatment process, the sample was ultrasonically cleaned in water and ethanol for 10 minutes.

4. The method for preparing a two-dimensional TiO2-MoS2 thin film on a magnesium alloy surface according to claim 1, characterized in that: During the preparation of electrophoretic fluid, the ratio of TiO2:MoS2 is 1:0.

7.

5. The method for preparing a two-dimensional TiO2-MoS2 thin film on a magnesium alloy surface according to claim 1, characterized in that: During the preparation of the electrophoresis solution, the ultrasonic stirring time was 30 min.

6. The method for preparing a two-dimensional TiO2-MoS2 thin film on a magnesium alloy surface according to claim 1, characterized in that: During the electrophoretic deposition process, the electrophoretic deposition voltage and time were 20 V and 90 s, respectively.

7. The method for preparing a two-dimensional TiO2-MoS2 thin film on a magnesium alloy surface according to claim 1, characterized in that: During the film drying process, the furnace temperature was 150°C and the drying time was 60 min.

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