A method for surface modification of a metal and the modified metal obtained thereby and applications thereof

Abstract

The present application belongs to the technical field of metal fuel, and particularly relates to a surface modification method of metal, a modified metal obtained by the method and application of the modified metal. The modification method provided by the present application comprises hydrophilic modification and oleophilic modification. The hydrophilic modification is performed by modifying the metal with cerium hydroxide, so as to improve the dispersibility of the metal in water. The oleophilic modification is performed by modifying the surface of the metal with cerium acetate, so as to improve the dispersibility of the metal in an organic solvent. The improvement of the dispersibility promotes the combustion effect of the metal.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal fuel, and particularly relates to a surface modification method of metal, a modified metal obtained by the method and application of the modified metal. BACKGROUND

[0002] With the increasing demand for energy and the rising awareness of environmental protection, developing efficient and environmentally friendly fuels has become an important research direction. Metal fuels have been widely studied and applied in various fuel systems due to their excellent combustion performance and environmental friendly characteristics. However, some metal fuels (such as aluminum alloy) have poor dispersibility in water or organic solvents and are prone to agglomeration, which reduces the combustion efficiency and affects the performance in practical applications. Therefore, how to improve the surface properties of metal fuels to enable them to disperse uniformly in water or organic solvents is a problem to be solved. SUMMARY

[0003] The application aims to provide a surface modification method of metal, a modified metal obtained by the method and application of the modified metal. The modification method provided by the application can improve the dispersibility of metal in water or organic solvents.

[0004] To achieve the above-mentioned purpose, the application provides the following technical solutions.

[0005] The application provides a surface modification method of metal, which comprises hydrophilic modification or lipophilic modification.

[0006] The hydrophilic modification comprises the following steps: mixing a metal raw material with water to obtain a metal water dispersion; adding a soluble cerium source and an inorganic base to the metal water dispersion in sequence, and then performing a hydrophilic modification reaction to obtain a hydrophilically modified metal.

[0007] The lipophilic modification comprises the following steps: immersing the hydrophilically modified metal in an acetic acid solution to perform a lipophilic modification reaction, and obtaining a lipophilically modified metal.

[0008] Preferably, the metal raw material comprises a cerium-aluminum alloy; and the particle size of the metal raw material is 10-20 μm.

[0009] Preferably, the mass percentage of the metal raw material in the metal water dispersion is 25-40%.

[0010] The mixing of the metal raw material and water is performed under ultrasonic conditions, the power of the ultrasonic is 80-120 W, the temperature is 75-85℃, and the time is 30 min.

[0011] Preferably, the soluble cerium source comprises at least one of cerium nitrate and cerium chloride.

[0012] After the soluble cerium source is added, the pH value of the system is 4-6.

[0013] The inorganic base comprises potassium hydroxide; the inorganic base is added in the form of an inorganic base solution, the inorganic base solution is added dropwise, and the dropping rate is 1-2 mL / min;

[0014] After the inorganic base is added, the pH value of the system is 8-9.

[0015] Preferably, the hydrophilic modification reaction is carried out under ultrasonic conditions, the power of the ultrasonic is 60-180 W, the temperature is 50-90 DEG C, and the time is 30-150 min.

[0016] Preferably, the concentration of the acetic acid solution is 1 mol / L.

[0017] Preferably, the temperature of the lipophilic modification reaction is 40-65 DEG C, and the time is 30-60 min.

[0018] The application further provides the modified metal obtained by the modification method.

[0019] The hydrophilic modified metal comprises a metal substrate and cerium hydroxide on the surface of the metal substrate.

[0020] The lipophilic modified metal comprises a metal substrate and cerium acetate on the surface of the metal substrate.

[0021] Preferably, the mass percentage content of cerium hydroxide in the hydrophilic modified metal is 5-20%.

[0022] The mass percentage content of cerium acetate in the lipophilic modified metal is 2-8%.

[0023] The application further provides the application of the modified metal as a metal fuel.

[0024] The application provides a surface modification method of a metal, comprising hydrophilic modification or lipophilic modification.

[0025] The modification method provided by the application comprises hydrophilic modification or lipophilic modification, wherein the hydrophilic modification is carried out by modifying the metal with cerium hydroxide, so that the dispersibility of the metal in water is improved; the lipophilic modification is carried out by modifying the surface of the metal with cerium acetate, so that the dispersibility of the metal in an organic solvent is improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Contact angle test results of the hydrophilic modified metal obtained in Example 1;

[0027] Figure 2 Contact angle test results of the lipophilic modified metal obtained in Example 2;

[0028] Figure 3 Schematic diagram of the mechanism of the hydrophilic modification in the application;

[0029] Figure 4 Schematic diagram of the mechanism of the lipophilic modification in the application;

[0030] Figure 5 Schematic diagram of the modification method provided in the application;

[0031] Figure 6 Contact angle test results of the cerium-aluminum alloy without modification;

[0032] Figure 7 TG-DSC diagram of the modified metal obtained in Example 1 in the combustion process. DETAILED DESCRIPTION

[0033] The application provides a surface modification method of a metal, including hydrophilic modification or lipophilic modification.

[0034] The hydrophilic modification comprises the following steps: mixing a metal raw material and water to obtain a metal water dispersion liquid; sequentially adding a soluble cerium source and an inorganic base into the metal water dispersion liquid, and then performing a hydrophilic modification reaction to obtain a hydrophilic modified metal.

[0035] The lipophilic modification comprises the following steps: immersing the hydrophilic modified metal in an acetic acid solution to perform a lipophilic modification reaction, and then obtaining a lipophilic modified metal.

[0036] In the application, the hydrophilic modification comprises the following steps: mixing a metal raw material and water to obtain a metal water dispersion liquid; sequentially adding a soluble cerium source and an inorganic base into the metal water dispersion liquid, and then performing a hydrophilic modification reaction to obtain a hydrophilic modified metal.

[0037] In the application, the metal raw material preferably comprises a cerium-aluminum alloy; and the particle size of the metal raw material is preferably 10-20 μm.

[0038] In the present application, the water is preferably deionized water. In the present application, the mass percentage of the metal raw material in the metal aqueous dispersion is preferably 25-40%; the mixing of the metal raw material and water is preferably carried out under ultrasonic conditions, the power of the ultrasonic is preferably 80-120 W, further preferably 100 W, the temperature is preferably 75-85℃, further preferably 80℃, and the time is preferably 30 min.

[0039] In the present application, the soluble cerium source preferably includes at least one of cerium nitrate and cerium chloride; the soluble cerium source is preferably added in the form of a solution, and the concentration of the solution is preferably 0.1 mol / L; the addition of the soluble cerium source is preferably carried out under stirring conditions, and the stirring speed is preferably 500-800 rpm; after the addition of the soluble cerium source, the pH value of the system is preferably 4-6, further preferably 4.5.

[0040] In the present application, the inorganic base preferably includes potassium hydroxide; the inorganic base is preferably added in the form of a solution, and the concentration of the solution is preferably 0.1 mol / L; the addition mode of the solution is preferably dropwise, and the dropwise rate is preferably 1-2 mL / min; after the addition of the inorganic base, the pH value of the system is preferably 8-9, further preferably 8.5.

[0041] In the present application, the hydrophilic modification reaction is preferably carried out under ultrasonic conditions, the power of the ultrasonic is preferably 60-180 W, and can be specifically 60 W, 80 W, 100 W, 120 W, 140 W, 160 W, or 180 W; the temperature is preferably 50-90℃, and can be specifically 50℃, 60℃, 70℃, 80℃, or 90℃; the time is preferably 30-150 min, and can be specifically 30 min, 50 min, 80 min, 100 min, 120 min, or 150 min. After the hydrophilic modification reaction, the present application further preferably includes filtering the obtained system, washing the obtained precipitate with deionized water and anhydrous ethanol alternately, and drying and cooling; the number of times of the alternate washing is preferably 3, the drying mode is preferably vacuum drying, the temperature of the vacuum drying is preferably 60℃, and the time is preferably 12 h; the cooling is preferably to room temperature.

[0042] In the present application, after the addition of the soluble cerium source, the pH of the system is acidic, which can make Ce 3+ uniformly dispersed in the solution and preliminarily adsorbed on the surface of the metal particles; when the inorganic base is added dropwise, Ce 3+ is gradually hydrolyzed into Ce(OH)3, the loading of Ce(OH)3 on the surface of the metal particles is realized, and a hydrophilically modified metal is obtained. In the present application, the mechanism diagram of the hydrophilic modification is as shown in Figure 3 .

[0043] In the present application, the lipophilic modification comprises the following steps: immersing the hydrophilic modified metal in an acetic acid solution, performing a lipophilic modification reaction to obtain a lipophilic modified metal.

[0044] In the present application, before the immersion, the hydrophilic modified metal is preferably also subjected to pretreatment, which preferably comprises cleaning and drying in sequence. In the present application, the cleaning preferably comprises ultrasonic cleaning in a first organic solvent and a second organic solvent in sequence, the first organic solvent preferably comprises acetone, methyl ethyl ketone or tetrahydrofuran; and the second organic solvent preferably comprises anhydrous ethanol or isopropanol. In the present application, the power of the ultrasonic cleaning is preferably 80-300 W; and the time of the ultrasonic cleaning in the first organic solvent and the ultrasonic cleaning in the second organic solvent is independently preferably 10-30 min. In the present application, the temperature of the drying is preferably 50-110℃, and the time is preferably 30-90 min. In the present application, the purpose of the cleaning is to remove the organic matter and contaminants physically adsorbed on the surface.

[0045] In the present application, the concentration of the acetic acid solution is preferably 1 mol / L. In the present application, the temperature of the lipophilic modification reaction is preferably 40-65℃, and can be specifically 40℃, 45℃, 50℃, 55℃, 60℃ or 65℃; and the time is preferably 30-60 min, and can be specifically 30 min, 40 min, 50 min or 60 min. In the present application, the use of the acetic acid solution for modification can better control the reaction rate and avoid excessive corrosion of the alloy substrate.

[0046] In the present application, after the lipophilic modification reaction, the obtained modified material is preferably also subjected to cleaning and drying in sequence; the cleaning preferably comprises: after water washing the modified material, placing it in anhydrous ethanol for ultrasonic cleaning; the time of the ultrasonic cleaning is preferably 5-30 min, the temperature is preferably 30-65℃, and the power is preferably 80-300 W. In the present application, the temperature of the drying is preferably 45-80℃, and the time is preferably 60-120 min. In the present application, the ultrasonic cleaning can completely remove the cerium acetate salt and organic by-products that may be physically adsorbed on the surface.

[0047] In the present application, in the lipophilic modification, cerium acetate is adsorbed to the metal surface to improve the lipophilicity of the metal material. In the present application, a schematic diagram of the mechanism of the lipophilic modification is shown in Figure 4 .

[0048] The present application also provides a modified metal obtained by the modification method described in the above technical solution, which comprises a hydrophilic modified metal or a lipophilic modified metal.

[0049] The hydrophilic modified metal comprises a metal matrix and cerium hydroxide located on the surface of the metal matrix;

[0050] The oleophilic modified metal comprises a metal matrix and cerium acetate located on the surface of the metal matrix.

[0051] In this invention, the mass percentage of cerium hydroxide in the hydrophilic modified metal is preferably 5-20%. In this invention, the mass percentage of cerium acetate in the lipophilic modified metal is preferably 2-8%.

[0052] The present invention also provides the application of the modified metal described in the above technical solution as a metal fuel.

[0053] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0054] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0055] Example 1

[0056] Add 10g of deionized water and 5g of cerium-aluminum alloy (particle size 10~20μm) to a beaker, place the beaker in water at 80℃, and ultrasonically disperse for 30min under ultrasonic power of 100W to obtain a metal aqueous dispersion.

[0057] A 0.1 mol / L cerium nitrate solution was added to the obtained metal aqueous dispersion, and the mixture was mechanically stirred at 500 rpm to bring the pH of the solution to 4.5. Then, a 0.1 mol / L potassium hydroxide solution was added dropwise at a rate of 1 mL / min until the pH of the solution reached 8.5. The modification reaction was then carried out under ultrasonic power of 100 W and temperature of 80 °C for 2 h.

[0058] After filtering the reaction system, the precipitate was washed three times alternately with deionized water and anhydrous ethanol; then it was vacuum dried at 60°C for 12 hours and cooled to room temperature to obtain a hydrophilic modified cerium-aluminum alloy; the mass percentage of cerium hydroxide in the hydrophilic modified cerium-aluminum alloy was 16.3%.

[0059] The flowchart of the modification method provided in this embodiment is shown below. Figure 5 As shown.

[0060] Example 2

[0061] The 5 g of the hydrophilic modified cerium-aluminum alloy obtained in Example 1 was sequentially placed in 100 mL of acetone and 100 mL of anhydrous ethanol, and each was ultrasonically cleaned for 15 minutes at a room temperature and an ultrasonic power of 100 W; then the sample was placed in a vacuum drying oven and dried at 60°C for 50 minutes to obtain a pretreated sample;

[0062] A glass container containing 100 mL of 1 mol / L acetic acid solution was placed in a constant temperature water bath, heated and stabilized at 50°C, and the pretreated sample was completely immersed in the preheated acetic acid solution for an oleophilic modification reaction, which lasted for 30 min, during which the container was shaken 5 times to ensure uniform reaction;

[0063] Immediately after the reaction was completed, the sample was immersed in a beaker containing a large amount of deionized water, and gently shaken to terminate the reaction and wash away the residual acid; then the sample was transferred into anhydrous ethanol for immersion and ultrasonic cleaning for 5 min at a temperature of 50°C and an ultrasonic power of 100 W to completely remove the cerium acetate salt and organic byproducts that may be physically adsorbed on the surface; then it was placed in a 60°C vacuum drying oven and dried for 80 min to obtain an oleophilic modified cerium-aluminum alloy; the mass percentage content of cerium acetate in the oleophilic modified cerium-aluminum alloy was 7.1%.

[0064] The flowchart of the modification method provided in this example is shown in Figure 5 .

[0065] Performance test

[0066] Test Example 1

[0067] The contact angles of the modified cerium-aluminum alloys obtained in Examples 1 and 2 were tested; the cerium-aluminum alloy without modification was used as a comparison;

[0068] Figure 1 The contact angle test results of the hydrophilic modified cerium-aluminum alloy obtained in Example 1 showed that the contact angle test results were 20.5° and 22.2°, and the hydrophilic performance was excellent.

[0069] Figure 2 The contact angle test results of the oleophilic modified cerium-aluminum alloy obtained in Example 2 showed that the contact angle test results were 100.6° and 100.7°, and the hydrophobic performance was excellent.

[0070] Figure 6 The contact angle test results of the unmodified cerium-aluminum alloy showed that the contact angle test results were 86.7° and 86.9°, and neither the oleophilic nor the hydrophilic performance was good.

[0071] Test Example 2

[0072] The modified cerium-aluminum alloy obtained in Examples 1-2 was subjected to combustion test, and the specific test process was as follows: combustion was performed using a thermal gravimetric analyzer, the temperature was 1000 DEG C, the temperature rising rate was 10 DEG C / min, oxygen was passed through the whole process, the gas flow rate was 20 mL / min, the combustion efficiency after modification was obtained by comparing the mass before and after combustion, and the specific formula was as follows:

[0073] Combustion efficiency η = actual mass after combustion / theoretical mass after combustion * 100%;

[0074] The theoretical mass after combustion is the total mass of all substances in the raw material forming oxides;

[0075] The unmodified cerium-aluminum alloy was used as a comparison;

[0076] Figure 7 The TG-DSC graph of the modified metal obtained in Example 1 during combustion was as shown in Table 1;

[0077] Table 1: Combustion test results of the modified cerium-aluminum alloy obtained in Examples 1-2

[0078]

[0079] As can be seen from Table 1, the combustion efficiency after modification reached 95.01% and 93.54%, and the combustion efficiency was obviously improved.

[0080] Although the above examples have made a detailed description of the present application, it is only a part of the embodiments of the present application, not all the embodiments, and other embodiments can be obtained according to the present embodiments without creativity, and these embodiments all belong to the protection scope of the present application.

Claims

1. A method for surface modification of a metal, characterized by, comprising a hydrophilic modification or an oleophilic modification; the hydrophilic modification comprises the following steps: mixing a metal raw material and water to obtain a metal water dispersion; adding a soluble cerium source and an inorganic base into the metal water dispersion in sequence, and then performing a hydrophilic modification reaction to obtain a hydrophilically modified metal; the metal raw material comprises a cerium-aluminum alloy; the particle size of the metal raw material is 10-20 μm; the soluble cerium source comprises at least one of cerium nitrate and cerium chloride; after the addition of the soluble cerium source, the pH value of the system is 4-6; the inorganic base comprises potassium hydroxide; the inorganic base is added in the form of an inorganic base solution, the inorganic base solution is added dropwise, the dropwise addition rate is 1-2 mL / min; after the addition of the inorganic base, the pH value of the system is 8-9; the hydrophilic modification reaction is performed under ultrasonic conditions, the power of the ultrasonic is 60-180 W, the temperature is 50-90 ℃, and the time is 30-150 min; the oleophilic modification comprises the following steps: immersing the hydrophilically modified metal in an acetic acid solution to perform an oleophilic modification reaction to obtain an oleophilically modified metal; the concentration of the acetic acid solution is 1 mol / L; the temperature of the oleophilic modification reaction is 40-65 ℃, and the time is 30-60 min.

2. The surface modification method according to claim 1, wherein, the mass percentage of the metal raw material in the metal water dispersion is 25-40%; the mixing of the metal raw material and water is performed under ultrasonic conditions, the power of the ultrasonic is 80-120 W, the temperature is 75-85 ℃, and the time is 30 min.

3. The modified metal obtained by the modification method of claim 1 or 2, characterized in that, comprising a hydrophilically modified metal or an oleophilically modified metal; the hydrophilically modified metal comprises a metal substrate and cerium hydroxide on the surface of the metal substrate; the oleophilically modified metal comprises a metal substrate and cerium acetate on the surface of the metal substrate.

4. The modified metal according to claim 3, wherein the mass percentage of cerium hydroxide in the hydrophilically modified metal is 5-20%; the mass percentage of cerium acetate in the oleophilically modified metal is 2-8%.

5. Use of the modified metal of claim 3 or 4 as a metal fuel.

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