CN1663693A - A method for preparing superamphiphobic micro-nano film on metal surface - Google Patents

Abstract

The invention discloses a method for preparing a super-amphiphobic micro-nano film on a metal surface, relating to a metal surface treatment method, in particular to a method for constructing a super-amphiphobic micro-nano film on the surface of most common metals. Provided is a method for preparing a super-amphiphobic micro-nano film on a metal surface. The method comprises the following steps: preparing nanometer _TiO2 film on the metal surface; performing micronano treatment on the nanometer _TiO2 film. The process is simple, the operability is strong, the equipment is simple and practical, and the practicability is strong. Using hydrothermal post-treatment to micronize the surface of the nano- _TiO2 film can eliminate the cracks in the nano-film while keeping the film thickness constant, and solve the problem of cracking in the nano-film prepared by other techniques. Simply changing the temperature and time can prepare surface films with different morphology structures, which are not affected by factors such as the type, shape, and size of the substrate. The super-amphiphobic micro-nano structure TiO ₂ film can be prepared by surface fluorine silylation treatment, and the metal corrosion resistance is improved by nearly 3 orders of magnitude.

Description

A method for preparing superamphiphobic micro-nano film on metal surface

technical field

The invention relates to a metal surface treatment method, in particular to a method for constructing a super-amphiphobic micro-nano film on most common metal surfaces.

Background technique

Whether it is basic research or practical application, solid surface wettability has attracted widespread interest and attention. The super-amphiphobic or super-amphiphilic properties of material surfaces have important application significance in many high-tech fields. Since solution is an important factor leading to electrochemical corrosion damage of metal materials, surface wettability can become a key factor in controlling material corrosion. Constructing a nano-film with super-amphiphobic (hydrophobic and oleophobic) properties on the metal surface is expected to realize the dual functions of anti-corrosion and self-cleaning of the metal. For the development of super-amphiphobic nano-films, in 1997, Japan Tadanaga et al. (Tadanaga K.Katata N.Minami T., Super～water～repellent Al ₂ O ₃ coating films with high transparency, J.Am.Ceram Soc. , 1997, 80: 1040-1042) reported the preparation of boehmite (AlOOH) superhydrophobic membranes with "Flower" morphology by using sol-gel method and hydrothermal post-treatment technology; Nakajima et al. (Nakajima A.Fujishima A. Hashimoto K., Preparation of transparent superhydrophobic boehmite and silica film bysublimation of Aluminum acetylacetonate, Adv. Mater., 1999, 11(6): 1365-1368). Surface roughening of boehmite or SiO ₂ by heating and sublimating Al(C ₅ H ₇ O ₂ ) ₃ in the sintering process and subsequent fluorosilanization to prepare transparent nano-films, and applied to the windshield of automobile window glass has achieved better effect. Constructing a super-amphiphobic micro-nano TiO ₂ film on the metal surface can have a "triple effect" for the anti-corrosion technology of materials: hydrophobic effect, barrier effect and photogenerated cathodic protection effect, which has important practical application prospects. Related research has not been reported yet.

Contents of the invention

The invention aims to provide a method for preparing a super-amphiphobic micro-nano film on a metal surface.

The method for preparing a super-amphiphobic micro-nano film on a metal surface, the steps are as follows

1) Prepare nano-TiO2 film on metal surface;

2) Micro-nano treatment is carried out on the nano-TiO2 film on the metal surface.

Said preparation of nano-TiO2 film on metal surface adopts sol-gel method, at room temperature, after mixing 10-50mL absolute ethanol and 1-5mL ethyl acetoacetate (EAcAc), add 1-10ml butyl titanate Carry out the reaction, add water to adjust the size of the colloidal particles until a light yellow transparent TiO2 sol is obtained, and leave to age. The metal is ultrasonically cleaned and dried with acetone, absolute ethanol, and water three times in sequence, and the metal substrate is immersed in TiO2 sol, pulled at a speed of 0.1-10mm/s, dried naturally, and then dried under an infrared lamp. Then submerged in TiO2 sol again, pulled to form a film, and dried with infrared lamps. This preparation process was repeated 3 to 4 times, and burned at a constant temperature of 450°C for 10 to 60 minutes, and then naturally cooled to room temperature.

The amount of water adjusted by adding water is 1-10 mL. The frequency used for the three water ultrasounds is 40kHz, the power is 80W, and the time is 10-30min.

The method of micro-nano treatment on the nano-TiO2 film on the metal surface is to put the metal sample (i.e. nano-TiO2 film/metal) of the surface-modified nano-TiO2 film into 3 times of water at 40-100 ° C, and hydrothermally treat it for 1-10 hours. Finally, dry naturally, burn at 100-600°C for 10-60 minutes, cool naturally, put the nano-film/metal into 0.1-5% fluorosilane (FSA) alcohol solution, soak for 5-60 minutes Take it out and dry it at 100-200°C to prepare a super-hydrophobic nano-TiO2 film/metal (SA/TiO2/316L).

The invention can prepare the TiO2 film with super-amphiphobic micro-nano structure, which has the advantages of simple process, strong operability, simple required equipment and strong practicability. Using hydrothermal post-treatment to micronize the surface of the nano-TiO2 film can eliminate the cracks in the nano-film while keeping the film thickness constant, and solve the problem of cracking in the nano-film prepared by other techniques, especially only Surface films with different morphological structures can be prepared simply by changing the temperature and time, and are not affected by factors such as the type, shape, and size of the substrate. The super-amphiphobic micro-nano structure TiO2 film can be prepared by surface fluorosilylation treatment, which can improve the corrosion resistance of metals by nearly 3 orders of magnitude, that is, the corrosion resistance of metals is greatly improved.

Description of drawings

Figure 1 is the SEM photo of the nano-TiO2 film before micro-nano technology treatment.

Figure 2 is the AFM morphology (10 μm × 10 μm) of the TiO2 film on the surface after being treated by micro-nano technology (80°C) for 1 h.

Figure 3 is the AFM morphology (10 μm × 10 μm) of the TiO2 film on the surface after being treated by micro-nano technology (80°C) for 4 hours.

Figure 4 is the AFM morphology (10 μm × 10 μm) of the TiO2 film on the surface after being treated by micro-nanoization technology (100°C) for 4 hours.

Figure 5 is the XRD spectrum of TiO2 after micro-nano treatment. In Figure 5, the abscissa is 2θ/deg, and the ordinate is Intensity. (Give the Chinese names of the horizontal and vertical scales)

Figure 6 is a photo of the contact angle of the super-amphiphobic type formed on the surface of the TiO2 film treated by micro-nano treatment.

Figure 7 is the AC impedance spectrum of 316L stainless steel and membrane electrode in 0.5mol/L NaCl solution, a) 316L; b) TiO2/316L; c) FSA/TiO2/316L. Figure 7 (top is Bode diagram) a, b, c abscissa is log frequency (H), ordinate (right) is log impedance (Ω), ordinate (left) is phase (degree); Figure 7 (bottom is Nyqiust diagram) a, b, c, the abscissa is the real part of the impedance (MΩ), and the ordinate is the imaginary part of the impedance (MΩ))

Figure 8 Equivalent circuit of AC impedance simulation circuit, a) 316L stainless steel; (b) membrane electrode.

Detailed ways

The following embodiments will further illustrate the present invention in conjunction with the accompanying drawings.

Example 1

At normal temperature and pressure, first add 1ml EAcAc to 20ml absolute ethanol, add 4ml butyl titanate under stirring, after reacting for 1h, add 0.2ml water within 30min, stir for 5h, and wait for coating. Submerge the pretreated metal substrate (surface mechanical polishing, cleaning treatment) in the sol for 5 minutes, and pull it at a constant speed of 0.5mm/s to form a hanging film on the metal surface. After natural drying, you can see a layer of colored nano-TiO2 film on the metal surface. After drying under infrared light for 30 minutes, repeat the above process 3 times, put it in a muffle furnace at a constant temperature of 450 ° C for 30 minutes, and naturally cool to prepare nano-TiO2. membrane. The surface morphology of the nano-membrane was observed under a high-power scanning electron microscope (SEM), as shown in Figure 1. From Figure 1, it can be seen that the film is a porous film, the surface is basically flat and orderly, the diameter of the hole is about 5nm, and the particles are evenly distributed. A small amount of particles are agglomerated, the particle diameter is 18-20nm, and many particles are formed by the agglomeration of 3-4 small particles.

The drugs used in the experiment are all analytically pure, and the morphology and surface roughness of the film are tested by the NANOSCOPE IIIa scanning probe microscope (SPM) of the American DI company; the film thickness is measured by the ellipsometry tester of the University of Shanghai for Science and Technology. The particle crystal form of the nano-TiO2 thin film was tested by the Panalytical X'pert X-ray powder diffractometer of Philips company. The test parameters were: CuKα target, λ was 0.15406nm, current 20mA, voltage 40kV, and the slit system was 1°DS -1°SS-0.15mmRS, filter with graphite monochromator, scan speed 1-4°/min; use JC2000A contact angle measuring instrument (Shanghai Zhongchen Company) to test the wettability of the nano-film surface, cyclohexane instead of oil, The droplet size is 5 μL. The corrosion resistance was tested by PGSTAT30 electrochemical workstation of Autolab Company in the Netherlands.

The use of electrochemical methods to test the corrosion resistance of metals has the advantages of simplicity and reliability. The invention mainly uses an electrochemical Tafel polarization method and an electrochemical AC impedance method to test the anti-corrosion behavior of the 316L stainless steel substrate with a super-amphiphobic nano film on the surface after surface treatment. The test adopts a three-electrode system, with a membrane electrode (area 1cm×1cm) as the working electrode, Pt as the auxiliary electrode, a saturated calomel electrode (SCE) as the reference electrode, and 0.5mol/L NaCl as the electrolyte. The slots are placed in shielding boxes to reduce electromagnetic interference to the test system.

To micronize the surface of the nano-TiO2 film, first put the nano-TiO2 film into water at 80°C for three times, treat it at a constant temperature for 1-10h, and dry it at 200°C after taking it out. Figure 2 is the surface morphology of the nano-film after hydrothermal treatment for 1 h. It can be seen from Figure 2 that micron-scale holes appear on the surface of the nano-TiO2 film, the interface between the particles is clear, and the particle diameter is about 40nm. There is a phenomenon of agglomeration. The micro-nano secondary structure is obvious. If the hydrothermal treatment time is increased to 4h, the morphology of the nano-TiO2 film on the surface (as shown in Figure 3) appears a multi-layer grid-like cross-linked micro-nano secondary structure, the grid wall tends to be smooth, and the nanoparticles are blurred.

Example 2

Using this technology to micronize the surface of the nano-TiO2 film, the morphology of the nano-film can be controlled by changing the temperature and time. Similarly, the nano-TiO2 film was suspended in three times of water (pH=7), subjected to hydrothermal treatment at a constant temperature of 100° C. for 3 hours, and then dried at 200° C. after being taken out. Figure 4 shows the surface morphology of the nano-TiO2 film after hydrothermal treatment at 100°C for 3h. It can be seen that the surface morphology is a uniformly distributed pattern structure. XRD was used to characterize the crystal form of the particles in the nano-film before and after micro-nano surface treatment (Figure 5). From Figure 5, it can be seen that the film with the surface micro-nano structure is mainly TiO2 anatase (101), (004), ( 200), (211), (204), (220) and (215) and other characteristic crystal faces, indicating that the nano-film prepared by this method does not affect the TiO2 crystal form.

Example 3

FSA was assembled on the surface of the micro-nano film after hydrothermal treatment in Examples 1 and 2 for 3 hours, put into 1% FSA alcohol solution and soaked for 1 hour to take it out, and dried at 170° C. for 1 hour to prepare hydrophobic micro-nano structure TiO2 film/316L, test Its surface wettability, the results are shown in Figure 6. It can be known that the contact angles of the surface to water and cyclohexane are both 156±1°, which proves that the film with the micro-nano structure on the surface has obvious super-hydrophobic properties.

Example 4

Characterization of corrosion resistance of super-hydrophobic micro-nanostructured TiO2 film/316L stainless steel. The preparation of the hydrophobic micro-nano TiO2 film/316L electrode is as mentioned above. The electrochemical test adopts a three-electrode system, with 316L, nano-TiO2 film and hydrophobic micro-nano TiO2 film/316L electrode as the working electrode, and the Pt sheet electrode as the auxiliary electrode. , the reference electrode is a saturated calomel electrode (SCE), and the electrolyte is a 0.5mol/L NaCl (pH=4.6) solution. The AC impedance method was used to test the corrosion resistance of different electrodes in NaCl solution. The test conditions were relative to the open circuit potential, the disturbance voltage was 10mV, and the frequency range was 105-10-3Hz. Figure 7 is the AC impedance spectrum of 316L stainless steel, TiO2/316L and super amphiphobic nano-TiO2 membrane electrode in 0.5mol/L NaCl solution, where the dotted line is the experimental data, and the solid line is the fitting data. Comparing the Nyquist diagrams of the three, it can be seen that the corrosion resistance from large to small is super-hydrophobic micro-nano TiO2 film electrode, nano-TiO2 film electrode and 316L stainless steel electrode, and the former is nearly 1 to 2 orders of magnitude worse than the latter. It can be seen from the Bode diagram that when the nano-film on the surface of stainless steel is applied, two time parameters appear in its AC impedance spectrum, which is the characteristic property of the surface covering film, and its interface structure can be used as the AC impedance equivalent circuit shown in Figure 8 To describe, (a) is the equivalent circuit of 316L stainless steel, Rs is the solution resistance, Rt and Qdl are the interface reaction resistance and electric double layer capacitance; (b) is the equivalent circuit of the membrane electrode, in addition to the above parameters, more A pair of (RQ) constants describing the properties of the membrane are membrane resistance Rc and capacitance Qc, respectively. Through the fitting of the equivalent circuit, the numerical value of each element of the above-mentioned equivalent circuit can be obtained, as shown in Table 1. The results also show that the electrochemical reaction resistance of the superhydrophobic nano-film electrode is 3 orders of magnitude higher than that of the stainless steel electrode. Structured TiO2 film has better anti-corrosion performance than conventional TiO2 film electrodes.

Table 1 AC impedance equivalent circuit fitting parameters no R _s Ω.cm ² Q _d R _c Ω.cm ² Q _d R _t Ω.cm ² Y _0Ω ^{～1.cm ～2.s ～n} no Y _0Ω ^{～1.cm ～2.s ～n} no 316L 30.9 ~ ~ ~ 6.08×10 ^～6 0.9 1.32×10 ⁵ TiO ₂ /316L 45.8 4.4×10 ^～8 0.7 2152 1.90×10 ^～6 0.9 1.68×10 ⁶ FAS/TiO ₂ /316L 38.0 1.6×10 ^～9 0.6 884 1.54×10 ^～6 0.9 2.03×10 ⁸

Claims (5)

1. A method for preparing a super-amphiphobic micro-nano film on a metal surface, characterized in that the steps are 1) Prepare nano-TiO2 film on metal surface; 2) Micro-nano treatment is carried out on the nano-TiO2 film on the metal surface. 2. A method for preparing a superamphiphobic micro-nano film on a metal surface as claimed in claim 1, characterized in that said preparation of nano-TiO2 film on the metal surface adopts a sol-gel method, and at room temperature, 10-50mL After mixing absolute ethanol and 1-5mL ethyl acetoacetate, add 1-10ml butyl titanate to react, add water to adjust the size of the colloidal particles until a light yellow transparent TiO2 sol is obtained, let it stand for aging, and wash the metal with acetone, Absolute ethanol, three times of water ultrasonication, cleaning, drying, immersing the metal substrate in the TiO2 sol, pulling at a speed of 0.1-10mm/s, after natural drying, drying under the infrared lamp, and then submerging in the TiO2 sol again, Pull to form a film, dry with an infrared lamp, repeat 3 to 4 times, burn at a constant temperature of 450°C for 10 to 60 minutes, and then cool down to room temperature naturally. 3. A method for preparing a superamphiphobic micro-nano film on a metal surface as claimed in claim 2, characterized in that the amount of water adjusted by adding water is 1-10 mL. 4. A method for preparing a superamphiphobic micro-nano film on a metal surface as claimed in claim 2, characterized in that the frequency of the three water ultrasonic waves is 40kHz, the power is 80W, and the time is 10-30min. 5. A method for preparing a super-amphiphobic micro-nano film on a metal surface as claimed in claim 1, characterized in that said method of carrying out micro-nano treatment on the metal surface nano-TiO2 film is to modify the surface of the nano-TiO2 film Put the metal sample into three times of water at 40-100°C, hydrothermally treat it for 1-10 hours, dry it naturally, burn it at 100-600°C for 10-60 minutes, cool it naturally, put the nano-film/metal into 0.1- Soak in 5% fluorosilane alcohol solution, take it out after soaking for 5 to 60 minutes, and dry at 100 to 200° C. to prepare superhydrophobic nano TiO2 film/metal.

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