CN109136903B - Silane composite film doped with rare earth salt and zeolite and preparation and application methods thereof - Google Patents

Abstract

The invention discloses a silane composite film doped with rare earth salt and zeolite and a preparation and application method thereof. A silane mixture doped with rare earth salts and zeolite particles is prepared, and after ageing, it is dipped or sprayed on the surface of the metal material, and a layer of dense corrosion-resistant silane composite film is formed on the surface of the aluminum alloy after curing. The invention utilizes porous zeolite particles to support rare earth salts with corrosion inhibition and self-healing effects, and the zeolite particles enhance the cross-linking density of the silane film, effectively enhance the physical barrier effect of the silane film on corrosive media, and realize the improvement of the metal surface silane film. Corrosion resistance target. In the present invention, the density of the silane composite film doped with rare earth salt and zeolite prepared on the metal surface is greatly improved, which can effectively hinder the penetration of external erosive substances, and can improve the adhesion between the polymer coating and the metal. The bonding strength effectively enhances the corrosion resistance of metal, and can meet the service requirements of corrosion resistance of metal materials under harsh environmental conditions.

Description

A kind of silane composite film doped with rare earth salt and zeolite and its preparation and application method

technical field

The invention relates to a silane composite film doped with rare earth salt and zeolite used for anticorrosion and a preparation and application method thereof, belonging to the technical field of metal surface treatment.

Background technique

The industrial production of metal materials is extremely common as an indispensable substance in life, but the chemical or electrochemical action of environmental media produces corrosion, which not only causes significant economic losses, but also causes harmful substances to pollute the living environment and damage human health. Therefore, many researchers have done a lot of research on metal anti-corrosion measures. Generally divided into the following categories: development of corrosion-resistant metal materials, covering protective layers on metal surfaces, metal surface modification, corrosion inhibition by corrosion inhibitors and electrochemical protection. Organic coatings are also widely used as the most economical and effective anti-corrosion measures. The organic coating is uniform and dense, but usually the chemical properties and structure of the organic coating and the metal material are very different, which will lead to an unsatisfactory bonding force between the organic coating and the metal. In order to make the organic coating It has good adhesion and corrosion resistance, and generally requires interface treatment, that is, surface pretreatment of the metal. On the one hand, it can improve the corrosion resistance of the metal, and on the other hand, it can improve the bonding force between the organic coating and the metal substrate.

At present, metal surface pretreatment methods mainly include rare earth conversion coating treatment, phosphating treatment, organic thin film coating treatment and so on. Among them, the organic thin film coating treatment includes preparing a layer of organic silane film on the metal surface. Silane is a hybrid molecule with organic and inorganic functional groups. The hydrolyzable inorganic functional group will form a covalent bond with the metal substrate. The Si-O-Si network structure is formed on the metal substrate, and the organic functional group is compatible with the organic coating system, which can enhance the bonding strength of the interface. In addition, after silane hydrolysis, alcoholic hydroxyl groups are formed, and a silane film with Si-O-Si network structure is formed on the metal substrate by cross-linking, which can prevent the penetration of water and electrolyte into the metal substrate, and provide a hydrophobic physical barrier.

However, the silane film is very thin, with a thickness of about 100-500 nm, and there are some defects such as microcracks and micropores. The corrosive electrolyte easily contacts the metal surface through these defects and causes the metal to corrode. Cerium nitrate, cerium chloride and rare earth salts such as lanthanum nitrate and lanthanum chloride not only have corrosion inhibition properties, but also have self-healing properties. Cerium or lanthanum ions protect damaged areas from corrosion by forming oxides or hydroxides. The surface treatment of the metal substrate with cerium or lanthanum doped silane can effectively protect the substrate from corrosion within a certain period of time, and the corrosion resistance of the silane film is significantly improved. Si-Ce organic-inorganic hybrid films have become one of the most promising environmentally friendly alternatives to chromium conversion films.

Some researchers have prepared a Si/Zr gel coating on the surface of 6 series aluminum alloy and used cerium nitrate to improve it and achieved good results, but the problem is that the thickness of this gel layer is about 15 μm, which is too thick for interface treatment. Some researchers have also tried to prepare a thin silane film on the surface of galvanized steel and doped with cerium nitrate solution. They are also committed to combining the barrier effect of silane film and the corrosion inhibition effect of cerium nitrate. Adding to a certain extent strengthens the barrier effect of the silane film.

Rare earth salts such as rare earth cerium salts or lanthanum salts are effective corrosion inhibitors. If there is a good carrier to store them and synergize with them, the corrosion resistance of silane films can be improved to a greater extent.

Zeolite, an aluminosilicate, is an inorganic material with a three-dimensional framework structure. The framework composed of silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron connected by shared oxygen atoms has abundant microporous structure. Due to the special properties and structure of zeolite, many researchers have synthesized zeolite coatings on metal surfaces by one-step or two-step methods, and the effect is also very obvious. First, zeolite has strong chemical activity due to the presence of alcoholic hydroxyl groups on the surface. Based on this characteristic, silane can interact with its surface to react. Secondly, the porosity of zeolite provides a good carrier for corrosion inhibitors of rare earth salts such as cerium salts or lanthanum salts, and the synergistic effect of the two improves the corrosion resistance of silane films to a greater extent, and the zeolite particles are filled into the silane matrix. It can increase the crosslinking density to reduce the wettability of the overall film and hinder the entry of water molecular media. There are some hydroxyl groups on the surface of the nano-inorganic zeolite particles, which can react with silanol bonds to form external hydrophobic organic chains, thus hindering corrosive media such as water. entry.

There are no reports on silane composite films doped with rare earth salts and zeolite particles at the same time.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the primary purpose of the present invention is to provide a silane composite film doped with rare earth salt and zeolite for anticorrosion. By preparing a silane composite film doped with rare earth salts and zeolite on the surface of metal materials, both the corrosion inhibition properties of rare earth salts and the special microporous structure of zeolite particles are fully utilized to provide a good carrier for rare earth salts. They produce a synergistic effect to improve the corrosion resistance of the silane film to a greater extent. At the same time, the filling of zeolite particles into the silane matrix can increase the cross-linking density and reduce the wettability of the overall film, and form an external hydrophobic organic chain through the reaction of surface hydroxyl groups and silanol bonds, thereby hindering the entry of corrosive media such as water, effectively enhancing the The barrier function of the silane film is improved, the corrosion resistance of the metal is improved, the interface bonding strength between the organic coating and the substrate is improved, and the corrosion resistance requirements of the metal material in the harsh service environment are met.

A silane composite film doped with rare earth salt and zeolite.

Preferably, in the reaction system for preparing the silane composite film doped with rare earth salt and zeolite: the rare earth salt concentration is 1×10 ^-4 to 1×10 ^-1 mol/L, and the zeolite concentration is 0.05 to 5 g/L. In the present invention, if the concentration of rare earth salt is too low, the improvement effect of the composite film is not obvious; if the concentration is too high, phenomena such as agglomeration and accumulation will occur, thereby destroying the regularity of the composite film and increasing the probability of defects in the composite film. At the same time, too little zeolite addition in the present invention has basically no improvement effect; while too much addition will cause agglomeration and uneven particle distribution, thus seriously affecting the step-by-step process of cerium with self-healing ability.

As a further preference, the concentration of the rare earth salt is 1×10 ^-3 to 9×10 ^-3 mol/L, and the concentration of the zeolite is 0.1 to 2 g/L. Within the preferred range of the present invention, the two can produce better synergy, thereby improving the corrosion resistance of the composite film to a greater extent.

Preferably, the particle size of the zeolite is 30-900 nm, preferably 50-200 nm. In the present invention, there is no special requirement for the pore size of the zeolite particles, as long as it is larger than the radius of the rare earth metal ion.

Preferably, the thickness of the silane composite film doped with rare earth salt and zeolite is 100-2000 nm. Preferably 300-1500nm.

Since the present invention is a pretreatment process for the surface of the metal material, also called interface treatment, there are certain requirements for the thickness of the subsequent coating, and the interface treatment cannot be too thick, otherwise the thickness of the overall coating will be affected.

The second object of the present invention is to provide a method for preparing the above-mentioned silane composite film. In the invention, the surface of the metal material is first impregnated or sprayed with the aged silane mixture, and then cured to obtain the silane composite film. The process is simple and easy to operate, the conditions are mild and pollution-free, and the reproducibility is high.

In order to achieve the above object, the present invention is implemented through the following technical solutions:

(1) Preparation of silane mixed solution: add rare earth salt to the mixed solution of silane and solvent, and then add zeolite particles after aging to obtain silane mixed solution;

(2) Curing of the silane composite film: the silane mixed solution is attached to the surface of the pretreated metal material by dipping or spraying, and the silane composite film is obtained by curing.

During the preparation of the silane composite film doped with rare earth salt and zeolite, the rare earth salt is preferably added to the mixed solution of silane and solvent, and then the zeolite particles are added after aging. If the zeolite particles are added now, the micropores on the surface of the zeolite will be blocked by silane, which will greatly reduce the loading of the rare earth salt in the micropores of the zeolite, thereby affecting the synergistic effect of the zeolite and the rare earth salt.

Preferably, the rare earth salt includes: one of soluble cerium salts and lanthanum salts, such as cerium nitrate, cerium chloride, lanthanum nitrate, and lanthanum chloride.

Preferably, the silane is various mono- or di-silane coupling agents. For example, bis-[γ-(triethoxysilyl)propyl]tetrasulfide, γ-glycidylpropyl-trimethoxysilane, γ-methacryloxypropyl-trimethoxysilane.

Preferably, the volume ratio of the silane to the solvent is 1-30:99-70. More preferably, it is 3-10:97-90. More preferably, the volume ratio of the organic solvent, silane and deionized water is 98-80:1-10:1-10.

Preferably, in step (1), the solvent is an organic solvent and deionized water, such as methanol or ethanol or acetone and deionized water. Further preferred are ethanol and deionized water.

In the present invention, silane is easily soluble in ethanol but insoluble in water, and the silane composite film is combined with the substrate through alcohol hydroxyl bonds, so too few alcohol hydroxyl groups are not conducive to bonding, and too many alcohol hydroxyl groups will absorb water, so an appropriate amount of hydrolysis can be beneficial to Corrosion resistance and bond strength of silane films.

Preferably, in step (1), zeolite particles are added to the mixed solution and then ultrasonically stirred to obtain a silane mixed solution.

Preferably, in step (2), the curing conditions are as follows: the temperature is 20-200°C, preferably 80-120°C; the time is 0.5-48h, preferably 1-10h. .

Preferably, in step (1), the aging time is 1h-10d, preferably 1-5d. If the aging time is too short, the hydrolysis of the silane is insufficient; if the aging time is too long, a deposit appears at the bottom of the solution.

Preferably, the pretreated metal material is a material pretreated by boiling, grinding, ultrasonic, cleaning or micro-arc oxidation.

The preferred preparation method of the present invention comprises the steps:

(1) Sample pretreatment

The aluminum alloy plate is cut into 15×15×2mm samples, boiled in boiling water, polished with water sandpaper, ultrasonic cleaning and other surface pretreatments;

(2) Preparation of silane mixed solution

Mix ethanol, silane and deionized water uniformly in a volume ratio of 95:5:5, add 1×10 ^-3 to 9×10 ^-3 mol/L of cerium nitrate to the mixture, and age at room temperature for 1～ 5d, adding 0.1-2 g/L of nano-zeolite particles into the mixed solution, stirring for 1-100 min, and then ultrasonicating for 1-100 min to obtain a silane mixed solution;

(3) Curing of silane composite film

Put the pretreated sample into the aged silane mixture, soak it for 0.5-30 minutes, and then cure it for 1-10 hours at a temperature of 80-120 °C to obtain a silane composite film.

The third object of the present invention is to provide an application method of the silane composite film doped with rare earth salt and zeolite, specifically, curing the silane composite film doped with rare earth salt and zeolite on the surface of a metal material for anti-corrosion.

Further preferably, the metal material comprises pure aluminum, aluminum alloy, iron alloy, magnesium alloy or copper alloy.

The advantages and effects of the present invention are as follows:

1. Silane (BTESPT) is a hybrid molecule with organic and inorganic functional groups. The hydrolyzable inorganic functional group will form a covalent bond with the metal substrate, forming a Si-O-Si network structure on the metal substrate, which can prevent The water and electrolyte penetrate into the metal substrate, providing a physical barrier, while the organic functional groups are compatible with the organic coating system, thereby enhancing the bonding of the organic coating to the metal material. Rare earth salts such as cerium nitrate and cerium chloride not only have corrosion inhibition properties, but also have self-healing properties, which can protect damaged areas from corrosion by forming oxides or hydroxides. The zeolite is mainly composed of a three-dimensional silica-alumina-oxygen framework. The silica-oxygen tetrahedrons are connected in different ways. Many holes and pores are formed in the zeolite structure, which can be used as an effective carrier for rare earth metal ions to be loaded and slowly released. There are some hydroxyl groups that can react with silanol bonds to form external hydrophobic organic chains, blocking the intrusion of external water.

2. The present invention prepares a silane composite film doped with rare earth salts and zeolite on the surface of the metal substrate, which not only utilizes the corrosion inhibition properties of rare earth salts, but also makes full use of the special microporous structure of zeolite particles to provide a good environment for rare earth salts. The two have a synergistic effect to improve the corrosion resistance of the silane film to a greater extent. At the same time, the filling of zeolite particles into the silane matrix can increase the cross-linking density and reduce the wettability of the overall film, and form an external hydrophobic organic chain through the reaction of surface hydroxyl groups and silanol bonds, thereby hindering the entry of corrosive media such as water, effectively enhancing the The barrier function of the silane film is improved, the corrosion resistance of the metal matrix is improved, the interface bonding strength between the polymer coating and the matrix is improved, and the corrosion resistance requirements of the aluminum alloy in the harsh service environment are met.

3. In the present invention, the surface of the metal sample is simply pretreated to prepare a silane mixture doped with rare earth salt and zeolite. After aging, the pretreated aluminum alloy sample is prepared by dip coating method. Soak in the silane mixture for a certain period of time, or spray the aging solution on the surface of the pretreated aluminum alloy, and then solidify after drying or blowing to form a dense silane composite film on the surface of the metal material. The process is simple and easy to operate, and the conditions Mild and pollution-free, with high reproducibility.

4. The present invention is suitable for various metal anticorrosion, including interface modification of pure aluminum, aluminum alloy, iron alloy, magnesium alloy or copper alloy, etc., and has wide applicability.

Description of drawings

Figure 1 shows the polarization curves of pure silane film samples prepared at different volume fractions of silane and different curing temperatures in 3.5wt% NaCl solution;

Among them: Figure 1a shows the corrosion potential and corrosion current density of pure silane film samples prepared with different volume fractions of silane; from Figure 1a, it can be concluded that the optimal volume fraction of silane is 5% (v/v);

Figure 1b shows pure silane film samples prepared at different curing temperatures when the optimum volume fraction of silane is 5% (v/v). From Figure 1b, it can be concluded that the optimum curing temperature is 100°C.

Fig. 2 shows the polarization curves of samples doped with different concentrations of cerium nitrate alone in silane films on aluminum alloy surfaces and in 3.5wt% NaCl solution under different soaking time conditions;

Among them: Figure 2a is the polarization curve of the samples doped with different concentrations of cerium nitrate alone in the silane film on the aluminum alloy surface in 3.5wt% NaCl solution; through the change of corrosion current density, it can be concluded that the optimal doping concentration of cerium nitrate is 5×10 ^-3 moL;

Figure 2b shows the polarization curves of the samples doped with the optimal concentration of cerium nitrate in 3.5wt% NaCl solution for different soaking times.

Figure 3 shows the polarization curve of the zeolite sample added alone in the silane film on the aluminum alloy surface in the solution in 3.5wt% NaCl; it can be seen from the figure that the polarization current density of the sample has increased by one order of magnitude after one polarization test. , it can be seen that the corrosion resistance has not been improved compared with that without the addition of zeolite.

Fig. 4 shows the polarization curves of the silane composite membrane samples doped with cerium nitrate and zeolite in 3.5wt% NaCl solution for different soaking times;

Among them: Figure 4a shows the zeolite concentration of 0.25g/L, Figure 4b shows the zeolite concentration of 0.5g/L, and Figure 4c shows the zeolite concentration of 2.5g/L; comparing the polarization curves, it can be concluded that the corrosion current is when the zeolite mass concentration is 0.5g/L Lowest density and longest stable.

FIG. 5 is an AC impedance diagram of a pure silane film sample on an aluminum alloy surface in a 3.5wt% NaCl solution.

FIG. 6 is an AC impedance diagram of a sample doped with cerium nitrate alone in a silane film in a 3.5 wt% NaCl solution.

FIG. 7 is an AC impedance diagram of a sample of zeolite doped alone in a silane film in a 3.5 wt% NaCl solution.

Figure 8 is the AC impedance diagram of the silane film doped with cerium nitrate and zeolite in 3.5wt% NaCl solution; it can be seen from the figure that the low-frequency impedance value reaches 10 ⁸ Ω.cm ² when cerium nitrate and zeolite are added at the same time, and The rate of decline is the slowest, which is a great improvement over the addition of cerium nitrate alone (Fig. 6) or zeolite (Fig. 7).

Figures 5 to 8 are all characterized by characterizing impedance values and phase angles.

Figure 9 is a photo of various samples immersed in 3.5wt% NaCl solution;

From top to bottom, there are pure silane film samples on the aluminum alloy surface, samples doped with cerium nitrate in the silane film, samples doped with zeolite in the silane film, and samples doped with cerium nitrate and zeolite in the silane film;

These pictures more intuitively show the corrosion resistance of different samples in the same corrosive environment. It is obvious that the corrosion resistance of the samples added with cerium nitrate and zeolite at the same time has been greatly improved.

Figure 10 is the surface scanning electron microscope image and energy spectrum analysis of the cerium nitrate/silane treated sample (see Table 1);

Characterizing the surface morphology of the sample, it can be seen that the addition of cerium nitrate does not destroy the regularity of the silane film, and the energy spectrum analysis can show the existence of cerium oxide on the surface of the silane film.

Figure 11 is the surface scanning electron microscope image and energy spectrum analysis of the zeolite/cerium nitrate/silane treated sample of the present invention (see Table 1);

Characterizing the surface morphology of the sample, it can be seen that there are no cracks and pores between the film layer and the particles. The energy spectrum analysis shows that the zeolite particles contain cerium elements, indicating that the zeolite has the function of adsorbing cerium ions.

Fig. 12 is the electron probe surface scanning diagram of the zeolite/cerium nitrate/silane treated sample of the present invention;

From the figure, it can be analyzed that there is a single cerium oxide in the silane film, and the zeolite adsorbs cerium ions, which further proves the function of zeolite to adsorb cerium ions.

Table 1

Detailed ways

The present invention is further illustrated below in conjunction with the examples, but not limited thereto.

Example 1

(1) Sample pretreatment

The 7N01 aluminum alloy was cut into 15×15×2mm samples, boiled in boiling water, polished with water abrasive paper, and then ultrasonically cleaned in absolute ethanol and deionized water in turn;

(2) Preparation of silane mixed solution

Mix ethanol, bis-(γ-triethoxysilylpropyl)tetrasulfide silane, and deionized water in a volume ratio of 90:5:5, and mix cerium nitrate with a concentration of 1×10 ^-3 mol/L. Add to the mixed solution, age at room temperature for 3d, add zeolite nanoparticles to the mixed solution at 0.1 g/L, stir for 2 min and then ultrasonicate for 2 min to obtain a silane mixed solution;

(3) Curing of silane composite film

The pretreated aluminum alloy samples were put into the aged silane mixture, soaked for 1 min, taken out, placed in an oven and cured at 80 °C for 1 h to form a silane composite film.

Example 2

(1) Sample pretreatment

The 7020 aluminum alloy was cut into 15×15×2mm samples, boiled in boiling water, polished with water abrasive paper, and then ultrasonically cleaned in absolute ethanol and deionized water in turn;

(2) Preparation of silane mixed solution

Mix ethanol, bis-(γ-triethoxysilylpropyl)tetrasulfide silane, and deionized water in a volume ratio of 90:5:5, and mix cerium nitrate with a concentration of 5×10 ^-3 mol/L. Add to the mixed solution, age at room temperature for 1 d, add zeolite nanoparticles to the mixed solution at 0.1 g/L, stir for 2 min, and then ultrasonicate for 2 min to obtain a silane mixed solution;

(3) Curing of silane composite film

The pretreated aluminum alloy samples were put into the aged silane mixture, soaked for 1 min, taken out, placed in an oven and cured at 60 °C for 1 h to form a silane composite film.

Example 3

(1) Sample pretreatment

The 6063 aluminum alloy was cut into 15×15×2mm samples, boiled in boiling water, polished with water abrasive paper, and then ultrasonically cleaned in absolute ethanol and deionized water in turn;

(2) Preparation of silane mixed solution

Mix ethanol, bis-(γ-triethoxysilylpropyl)tetrasulfide silane, and deionized water in a volume ratio of 85:5:10, and mix cerium nitrate with a concentration of 9×10 ^-3 mol/L. Add into the mixed solution, age at room temperature for 2 d, add zeolite nanoparticles to the mixed solution at 0.5 g/L, stir for 2 min and then sonicate for 2 min to obtain a silane mixed solution;

(3) Curing of silane composite film

The pretreated aluminum alloy samples were put into the aged silane mixture, soaked for 1 min, taken out, placed in an oven and cured at 119 °C for 1 h to form a silane composite film.

Example 4

(1) Sample pretreatment

The 7005 aluminum alloy was cut into 15×15×2mm samples, boiled in boiling water, polished with water abrasive paper, and then ultrasonically cleaned in absolute ethanol and deionized water in turn;

(2) Preparation of silane mixed solution

Ethanol, γ-methacryloyloxypropyl-trimethoxysilane, and deionized water were mixed uniformly in a volume ratio of 80:10:10, and lanthanum nitrate with a concentration of 2×10 ^-2 mol/L was added to the solution. In the mixed solution, age at room temperature for 3d, add zeolite nanoparticles to the mixed solution at 0.2 g/L, stir for 2 min and then ultrasonicate for 2 min to obtain a silane mixed solution;

(3) Curing of silane composite film

The pretreated aluminum alloy samples were put into the aged silane mixture, soaked for 1 min, taken out, placed in an oven and cured at 89 °C for 1 h to form a silane composite film.

Example 5

(1) Sample pretreatment

The 2A01 aluminum alloy was cut into 15×15×2mm samples, boiled in boiling water, polished with water abrasive paper, and then ultrasonically cleaned in absolute ethanol and deionized water in turn;

(2) Preparation of silane mixed solution

Mix ethanol, vinyl tris(β-methoxyethoxy) silane and deionized water in a volume ratio of 90:5:5, and add cerium nitrate with a concentration of 7×10 ^-2 mol/L to the mixture , aged for 3d at room temperature, added zeolite nanoparticles to the mixed solution at 0.09 g/L, stirred for 2 min and then sonicated for 2 min to obtain a silane mixed solution;

(3) Curing of silane composite film

The pretreated aluminum alloy samples were put into the aged silane mixture, soaked for 1 min, taken out, placed in an oven and cured at 95 °C for 1 h to form a silane composite film.

Example 6

(1) Sample pretreatment

The 2005 aluminum alloy was cut into 15×15×2mm samples, boiled in boiling water, polished with water abrasive paper, and then ultrasonically cleaned in absolute ethanol and deionized water in turn;

(2) Preparation of silane mixed solution

Mix ethanol, N-(β-aminoethyl)-γ-aminopropyl-methyl-trimethoxysilane, and deionized water in a volume ratio of 95:5:5. The concentration is 1×10 ^-2 mol/L of cerium nitrate was added to the mixed solution, aged for 3d at room temperature, 0.3 g/L of zeolite nanoparticles was added to the mixed solution, stirred for 2 min and then sonicated for 2 min to obtain a silane mixed solution;

(3) Curing of silane composite film

The pretreated aluminum alloy samples were put into the aged silane mixture, soaked for 1 min, taken out, placed in an oven and cured at 85 °C for 1 h to form a silane composite film.

Example 7

(1) Sample pretreatment

Micro-arc oxidation pretreatment of 7N01 aluminum alloy;

(2) Preparation of silane mixed solution

Mix ethanol, bis-(γ-triethoxysilylpropyl)tetrasulfide silane, and deionized water in a volume ratio of 90:5:5, and mix cerium nitrate with a concentration of 5×10 ^-3 mol/L. Add to the mixed solution, age at room temperature for 3d, add zeolite nanoparticles to the mixed solution at 0.1 g/L, stir for 2 min and then ultrasonicate for 2 min to obtain a silane mixed solution;

(3) Curing of silane composite film

The pretreated aluminum alloy samples were put into the aged silane solution, soaked for 1 min, taken out, placed in an oven and cured at 80 °C for 1 h to form a silane composite film.

Comparative Example 1

Preparation of pure silane films:

The method of Example 2 was carried out, except that the rare earth salt and zeolite were not added.

Comparative Example 2

Preparation of Rare Earth Salt Modified Silane Thin Films

The method of Example 2 was carried out, except that no zeolite was added.

Comparative Example 3

Preparation of Zeolite-Modified Silane Films

The method of Example 2 was carried out, except that the rare earth salt was not added.

The results of Example 2 and Comparative Examples 1, 2, and 3 are shown in Figures 5, 6, 7, 8, and 9.

Claims (9)

1. A silane composite film doped with rare earth salt and zeolite; the preparation method is characterized by comprising the following steps: preparing a silane mixed solution: adding rare earth salt into a mixed solution of silane and a solvent, aging, and adding zeolite particles to obtain a silane mixed solution; (2) curing of the silane composite film: and (3) attaching the silane mixed solution to the surface of the pretreated metal material by dipping or spraying, and curing to obtain the silane composite film doped with rare earth salt and zeolite.

2. The silane composite film doped with rare earth salt and zeolite as claimed in claim 1, wherein the reaction system for preparing the silane composite film doped with rare earth salt and zeolite comprises: the rare earth salt concentration is 1 × 10^-4～1×10^-1mol/L, and the concentration of the zeolite is 0.05-5 g/L.

3. The rare earth salt and zeolite-doped silane composite film according to claim 1, wherein the particle size of the zeolite particles is 30 to 900 nm.

4. The silane composite film doped with rare earth salt and zeolite as claimed in claim 1, wherein the thickness of the silane composite film doped with rare earth salt and zeolite is 100-2000 nm.

5. The silane composite film doped with rare earth salt and zeolite according to claim 1, wherein the rare earth salt is one of soluble cerium salt and lanthanum salt; the silane is a mono-or bis-silane coupling agent.

6. The rare earth salt and zeolite-doped silane composite film according to claim 1, wherein in the step (1), the volume ratio of the silane to the solvent is 1-30: 99 to 70.

7. The silane composite film doped with rare earth salt and zeolite of claim 1, wherein in the step (1), the zeolite particles are added into the mixed solution and then ultrasonically stirred to obtain the silane mixed solution.

8. The rare earth salt and zeolite-doped silane composite film according to claim 1, wherein in the step (2), the curing conditions are as follows: the temperature is 20-200 ℃, and the time is 0.5-48 h.

9. The method for applying the silane composite film doped with the rare earth salt and the zeolite as claimed in any one of claims 1 to 8, wherein the silane composite film doped with the rare earth salt and the zeolite is cured on the surface of a metal material for corrosion prevention.

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