CN113881932A

CN113881932A - Low-temperature rapid preparation method of hydrophobic high-orientation all-silicon zeolite protective film

Info

Publication number: CN113881932A
Application number: CN202111097768.1A
Authority: CN
Inventors: 刘盼; 曹发和; 胡吉明
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2021-09-18
Filing date: 2021-09-18
Publication date: 2022-01-04
Anticipated expiration: 2041-09-18
Also published as: CN113881932B

Abstract

The invention discloses a low-temperature rapid preparation method of a hydrophobic high-orientation all-silicon zeolite protective film. The first step is to prepare the all-silicon zeolite seed crystal without the template agent through hydrothermal reaction and high-temperature calcination; coating the prepared seed crystal on a substrate material; and then placing the substrate coated with the seed crystal in a reaction kettle containing a secondary growth solution for secondary hydrothermal treatment at 100 ℃, and generating a compact film through the epitaxial growth of the seed crystal. The invention adopts a simple two-step process, and the all-silicon zeolite film prepared rapidly at lower temperature is continuous, compact and hydrophobic, and can greatly improve the corrosion resistance of the material. The method can greatly reduce the synthesis temperature of the film and reduce the contact time of the base material and the high-alkaline synthesis solution, and the thickness of about 1 mu m provides a feasible scheme for the rapid preparation of the zeolite film on the surface of the base material with stronger temperature or pH sensitivity and the corrosion protection of the surface of a precision material part with harsh requirements on the thickness of the coating.

Description

Low-temperature rapid preparation method of hydrophobic high-orientation all-silicon zeolite protective film

Technical Field

The invention relates to the field of metal protection, in particular to a method for quickly preparing a hydrophobic high-orientation all-silicon zeolite anticorrosive film at low temperature by a two-step method.

Background

Iron and iron-based alloys are widely applied to the fields of aerospace, ship heavy industry, municipal construction, home decoration and the like due to the outstanding advantages of rich reserves, low price, mature manufacturing technology and the like. However, iron and iron-based alloys have strong corrosion sensitivity due to their active chemical/electrochemical properties, and are very susceptible to corrosion damage in an aggressive environment, which seriously affects the service life and the application range of the materials.

Zeolite is an aluminosilicate compound with cubic crystals, and has the capacity of screening molecules with different sizes due to uniform microporous structure, so that the zeolite is widely applied to the fields of catalysis, pharmacy and the like. Compared with the restriction of the early macromolecular organic thin film on environmental unfriendliness, the zeolite inorganic film, especially the all-silicon zeolite inorganic film, has a series of advantages of excellent high temperature resistance, stable structure, chemical corrosion resistance, excellent mechanical properties, no toxicity, no harm and the like, and is gradually adopted in the research of the corrosion protection field. The preparation of the traditional all-silicon zeolite anticorrosive film is usually an in-situ hydrothermal method, but the application of the film on a substrate with strong temperature and pH sensitivity is greatly limited due to the prominent problems that the hydrothermal synthesis temperature is higher and can reach over 180 ℃, the alkali of a synthesis solution is strong, and the like.

Disclosure of Invention

Aiming at the defects that the application of base material corrosion protection with strong temperature and pH sensitivity is greatly limited due to higher synthesis temperature and stronger alkalinity of a synthesis solution in the process of preparing the all-silicon zeolite anticorrosive film by the traditional in-situ hydrothermal method, and the like, and simultaneously aiming at the defects of higher synthesis temperature, longer synthesis time and the like in the secondary hydrothermal process of the traditional two-step method, the invention aims to provide the low-temperature rapid preparation method of the hydrophobic high-orientation all-silicon zeolite protective film. In the method, zeolite seed crystals are uniformly coated on the surface of a substrate material in advance, and the substrate material coated with the zeolite seed crystals is placed in a secondary growth solution taking ammonium hexafluorosilicate as a silicon source for secondary hydrothermal treatment, so that the contact area of the substrate material and a high-alkalinity synthetic solution can be greatly reduced, and the preparation time of a film is shortened.

A low-temperature rapid preparation method of a hydrophobic high-orientation all-silicon zeolite protective film comprises the following steps:

1) stirring a mixed solution A of tetrapropylammonium hydroxide, tetraethyl silicate and deionized water at room temperature;

2) transferring the mixture into a high-temperature reaction kettle, taking out after hydrothermal treatment, immediately quenching in cold water, washing the generated all-silicon zeolite seed crystal with deionized water for multiple times, drying, and calcining in a muffle furnace to remove a template agent for later use;

3) the zeolite seed crystals are firstly put into an agate mortar for grinding and then evenly coated on the surface of a substrate material;

4) stirring a mixed solution B of tetrapropyl ammonium hydroxide, ammonium hexafluorosilicate, ethylenediamine and deionized water at room temperature;

5) and putting the substrate material uniformly coated with the zeolite seed crystals into a reaction kettle containing the mixed solution B, taking out the substrate material after hydrothermal treatment, immediately quenching the substrate material by cold water, washing the taken substrate material coated with the zeolite film for multiple times by deionized water, and drying the substrate material.

The full silicon type only contains silicon element and oxygen element.

The molar ratio of the tetrapropylammonium hydroxide, the tetraethyl silicate and the deionized water in the mixed solution A in the step 1) is TPAOH, TEOS and H₂O = 0.32: 1: 165; the room temperature is 20-30 ℃, and the stirring time is 4 h.

The high-temperature reaction kettle in the step 2) is a stainless steel reaction kettle nested with a polytetrafluoroethylene lining; the hydrothermal temperature is 175 ℃, the rotating speed of the high-temperature reaction kettle is 20 rpm, and the hydrothermal reaction time is 1.5 h; the cold water quenching is that the high-temperature reaction kettle is taken out and then is immediately placed in a stainless steel barrel filled with a large amount of tap water; washing for multiple times until the pH value of the supernatant is 7; the calcining temperature in the muffle furnace is 550 ℃, and the calcining time is 5 h.

The grinding time of the zeolite seed crystals in the step 3) is 15 min.

The substrate material is alloy steel, silicon chip or conductive glass.

The substrate material is alloy steel, wherein the alloy steel is Fe-based, 16.29% Cr, 8.06% Ni, 1.05% Mn, 0.47% Si, 0.047% C, 0.047% N, 0.033% P, 0.03% Cu, 0.002% S, and wt.%.

The molar ratio of tetrapropylammonium hydroxide, ammonium hexafluorosilicate, ethylenediamine and deionized water in the mixed solution B in the step 4) is TPAOH to (NH)₄)₂SiF₆∶EDA∶H₂O = 0.36: 1: 0.576: 27; the room temperature is 20-30 ℃, and the stirring time is 4 h.

The hydrothermal temperature in the step 5) is 100 ℃.

The drying temperature in the steps 2) and 5) is 60 ℃.

The invention has the beneficial effects that:

(1) the method can greatly reduce the synthesis temperature of the zeolite film and reduce the contact time of the matrix material and the high-alkaline synthesis solution, thereby providing a feasible scheme for quickly preparing the zeolite film on the surface of the metal material with stronger temperature sensitivity or pH sensitivity.

(2) The film has the thickness of only about 1 mu m, is continuous and compact, and can be applied to the corrosion protection of the surface of a precise metal part with a strict requirement on the thickness of the coating.

(3) The preparation method is simple and convenient to operate, high in regulation and control performance, high in efficiency and easy to realize.

Drawings

FIG. 1 is a scanning electron microscope photograph of the prepared all-silicon type zeolite seed crystal with the particle size of 500 nm and the alloy steel surface coated with the all-silicon type zeolite seed crystal and subjected to different secondary hydrothermal treatments;

wherein, each part is as follows: (a) preparing all-silicon zeolite seed crystals with the particle size of 500 nm; (b) alloy steel evenly coated with zeolite seed crystals; (c) carrying out secondary hydrothermal for 4 h at 100 ℃; (d) carrying out secondary hydrothermal for 6 h at 90 ℃; (e) carrying out secondary hydrothermal for 10 h at 80 ℃.

FIG. 2 is a photograph of a hydrophobic angle test of an alloy steel surface coated with a full-silicon zeolite film after two hydrothermal processes at 100 ℃ for 4 hours, 90 ℃ for 6 hours and 80 ℃ for 10 hours, respectively;

wherein, each part is as follows: (a) carrying out secondary hydrothermal for 4 h at 100 ℃; (b) carrying out secondary hydrothermal for 6 h at 90 ℃; (c) carrying out secondary hydrothermal for 10 h at 80 ℃.

FIG. 3 shows the results of atomic force microscope thickness measurement of the all-silica zeolite film after two hydrothermal treatments at 100 deg.C for 4 h, 90 deg.C for 6 h and 80 deg.C for 10 h, respectively;

FIG. 4 is Tafel curves of alloy steels coated with all-silica zeolite films in 3.5 wt.% NaCl solution after two hydrothermal processes at 100 ℃ for 4 h, 90 ℃ for 6 h and 80 ℃ for 10 h, respectively.

FIG. 5 is an optical photograph of bare alloy steel and alloy steel coated with an all-silica type zeolite film after being subjected to a secondary hydrothermal treatment at 100 ℃ for 4 hours, a secondary hydrothermal treatment at 90 ℃ for 6 hours, and a secondary hydrothermal treatment at 80 ℃ for 10 hours, respectively, in a 3.5 wt.% NaCl solution and after being soaked for 30 days;

wherein each part is as follows: (a) bare alloy; (b) carrying out secondary hydrothermal for 4 h at 100 ℃; (c) carrying out secondary hydrothermal for 6 h at 90 ℃; (d) carrying out secondary hydrothermal for 10 h at 80 ℃.

Detailed Description

The invention is further illustrated with reference to the following figures and examples, without however limiting the scope of the invention thereto.

Example 1

1) Firstly, tetrapropylammonium hydroxide, tetraethyl silicate and deionized water are mixed according to the molar ratio of TPAOH to TEOS to H₂O = 0.32: 1: 165 and stirred at room temperature for 4 h to clear and transparent.

2) And then pouring the mixed solution into a polytetrafluoroethylene lining in a stainless steel reaction kettle, preparing zeolite seed crystals at the temperature of 175 ℃ and the rotating speed of 20 rpm, wherein the hydrothermal time is 1.5 h, immediately taking out the reaction kettle after the reaction is finished, and placing the reaction kettle into a stainless steel barrel which is filled with a large amount of flowing cold water and has the capacity of 25L for quenching treatment. And repeatedly washing the prepared zeolite seed crystal by using deionized water until the pH value of the supernatant is about 7. The residual moisture is removed by drying in an oven at 60 ℃, and then the template in the pore channels is removed by calcining in a muffle furnace at 550 ℃ for 5 h and then cooled to room temperature for standby. The morphology of the all-silica type zeolite seed crystal with the particle size of 500 nm is shown as (a) in the attached figure 1.

3) The using mesh number is 400^#、600^#、800^#、1200^#The silicon carbide abrasive paper sequentially polishes the surface of the alloy steel, removes oxide skin naturally generated on the surface, then is matched with a diamond grinding agent on a polishing machine for polishing, is washed by deionized water, and is ultrasonically cleaned in acetone and ethanol for 5 min and then is dried by cold air for later use. The prepared all-silicon type zeolite seed crystal was placed in an agate mortar and ground for 15 min. A right amount of zeolite seed crystal is adhered to an index finger with an acetonitrile glove, and a layer of seed crystal layer is uniformly coated on the surface of the alloy steel in a circle drawing mode.

4) The alloy steel evenly coated with the seed crystal is placed in a polytetrafluoroethylene lining in a stainless steel reaction kettle, and the alloy steel is poured into the stainless steel reaction kettle and stirred for 4 hours at room temperature in advance according to the molar ratio of TPAOH to (NH)₄)₂SiF₆∶EDA∶H₂O = 0.36: 1: 0.576: 27.

5) Preparing the all-silicon zeolite film at the temperature of 100 ℃, wherein the secondary hydrothermal time is 4 h, immediately taking out the reaction kettle after the reaction is finished, and placing the reaction kettle in a stainless steel barrel with the capacity of 25L and filled with a large amount of flowing cold water for quenching treatment. The prepared sample was repeatedly washed with deionized water, dried in an oven at 60 ℃ to remove residual moisture, and then cooled to room temperature for use.

Example 2

The secondary hydrothermal temperature was 90 ℃ and the time was 6 hours, as in example 1.

Example 3

The secondary hydrothermal temperature was 80 ℃ and the time was 10 hours, as in example 1.

Comparison of results in examples 1, 2 and 3

1. The influence of different secondary hydrothermal temperatures on the synthesis time of the all-silicon zeolite film. The test results are shown in Table 1, and the scanning electron microscopy morphologies are shown in (c), (d), and (e) of FIG. 1. From figure 1 and table 1 it can be seen that when the secondary hydrothermal temperature is 100 c, only 4 h is required to produce a continuous dense film, and that the time required to reduce the temperature to 90 c and 80 c is further extended to 6 h and 10 h, respectively, indicating that the crystallization kinetics of the zeolite slows down with decreasing temperature.

TABLE 1 experimental results of different secondary hydrothermal temperatures on the synthesis time of all-silicon zeolite film

Secondary hydrothermal temperature/° c	Secondary hydrothermal time/h for formation of dense zeolite membrane
		100	4
90	6
		80	10

2. Influence of different secondary hydrothermal temperatures on the contact angle of the all-silicon zeolite film. The test results are shown in Table 2, and the contact angle photographs are shown in FIG. 2. As can be seen from FIG. 2 and Table 2, the average hydrophobic angle of the film was 142.5 when the secondary hydrothermal temperature was 100 ℃ and was reduced to 97.8 ℃ and 41.7 ℃ when the temperature was lowered to 90 ℃ and 80 ℃ respectively, due to the temperature dropThe slow resulting crystallization kinetics promote amorphous SiO₂Particle generation on the surface, SiO in non-mesoporous state₂The particles may cause deterioration of the hydrophobic properties of the surface of the film.

TABLE 2 experimental results of different secondary hydrothermal temperatures on contact angle of all-silicon zeolite film

Secondary hydrothermal temperature/° c	Average contact angle/°
		100	142.5
90	97.8
		80	41.7

3. The influence of different secondary hydrothermal temperatures on the thickness of the all-silicon zeolite film. The results of the atomic force microscope test for film thickness are shown in FIG. 3, and the specific values are shown in Table 3. As can be seen from FIGS. 3 and Table 3, the film thickness produced under all three conditions was about 1 μm, which is similar to that of the single zeolite seed crystal shown in FIG. 1 (a)bThe lengths in the axial direction are consistent, which shows that the films prepared under the three conditions are all single-layer zeolite films.

TABLE 3 experimental results of different secondary hydrothermal temperatures on the thickness of the all-silica type zeolite film

Secondary hydrothermal temperature/° c	Film thickness/. mu.m
		100	0.58±0.027
90	0.55±0.050
		80	0.64±0.020

4. The different secondary hydrothermal temperatures affect the corrosion resistance of the all-silica zeolite film in a 3.5 wt.% NaCl solution. The Tafel curve test was performed in a conventional three-electrode cell, in which 3.5 wt.% of prepared NaCl solution was poured, an alloy steel substrate coated with Silicalite-1 all-silica zeolite film was used as the working electrode, an Ag/AgCl (3M KCl) electrode was used as the reference electrode, and a platinum sheet was used as the counter electrode. The results of the experiment are shown in Table 4 and FIG. 4. Corrosion potential (E _corr) Generally considered as a parameter for evaluating the corrosion sensitivity of a material from a thermodynamic point of view, it can be seen from FIG. 4 and Table 4 that a decrease in temperature leads to a film being producedE _corrThe lower the secondary hydrothermal temperature, the lower the corrosion sensitivity of the film. In addition, corrosion current density: (i _corr) Further step corroborates the above view from a kinetic point of view, 100 ℃i _corrThe temperature is reduced by about one order of magnitude compared with 90 ℃ and 80 ℃, and the film prepared at the secondary hydrothermal temperature of 100 ℃ has the best corrosion resistance.

TABLE 4 results of experiments of different secondary hydrothermal temperatures on corrosion resistance test in 3.5 wt.% NaCl solution for all-silica type zeolite thin film

Secondary hydrothermal temperature/° c	i _corr(A/cm²)	E _corr(V)
			100	0.31×10^-8	-0.072
90	1.5×10^-8	-0.103
			80	6.3×10^-8	-0.176

5. The optical photographs of the obtained alloy steel coated with the all-silicon type zeolite film and the bare steel not coated with the film were immersed in a 3.5 wt.% NaCl solution for 30 days as shown in fig. 5, and it is understood from the results that no significant yellow rust or corrosion pit was observed on the surface of the zeolite film subjected to the secondary hydrothermal treatment at 100 ℃ for 4 hours under three conditions of 4 hours of the secondary hydrothermal treatment at 100 ℃, 6 hours of the secondary hydrothermal treatment at 90 ℃ and 10 hours of the secondary hydrothermal treatment at 80 ℃ (fig. 5 (b)), indicating that they had the best protective properties.

The embodiments described above can be further combined or replaced, and the embodiments are merely descriptions of preferred examples of the present invention, and do not limit the concept and scope of the present invention. For example, alloy steel may be replaced with silicon wafers or conductive glass. Various changes and modifications of the technical scheme of the invention, which are made by those skilled in the art without departing from the design idea of the invention, belong to the protection scope of the invention. The scope of the invention is given by the appended claims and any equivalents thereof.

Claims

1. A low-temperature rapid preparation method of a hydrophobic high-orientation all-silicon zeolite protective film is characterized by comprising the following steps:

2. The method according to claim 1, wherein the all-silicon type is a type containing only silicon and oxygen.

3. The method according to claim 1, wherein the molar ratio of tetrapropylammonium hydroxide, tetraethyl silicate and deionized water in the mixed solution A in the step 1) is TPAOH: TEOS: H₂O = 0.32: 1: 165; the room temperature is 20-30 ℃, and the stirring time is 4 h.

4. The preparation method of claim 1, wherein the high-temperature reaction kettle in the step 2) is a stainless steel reaction kettle nested with a polytetrafluoroethylene lining; the hydrothermal temperature is 175 ℃, the rotating speed of the high-temperature reaction kettle is 20 rpm, and the hydrothermal reaction time is 1.5 h; the cold water quenching is that the high-temperature reaction kettle is taken out and then is immediately placed in a stainless steel barrel filled with a large amount of tap water; washing for multiple times until the pH value of the supernatant is 7; the calcining temperature in the muffle furnace is 550 ℃, and the calcining time is 5 h.

5. The method as claimed in claim 1, wherein the grinding time of the zeolite seeds in the step 3) is 15 min.

6. The method according to claim 1, wherein the base material is alloy steel, silicon wafer or conductive glass.

7. The method according to claim 1, wherein the base material is an alloy steel, wherein Fe is based, 16.29% Cr, 8.06% Ni, 1.05% Mn, 0.47% Si, 0.047% C, 0.047% N, 0.033% P, 0.03% Cu, 0.002% S, wt.%.

8. The method according to claim 1, wherein the mixed solution B in the step 4) comprises tetrapropylammonium hydroxide, ammonium hexafluorosilicate, ethylenediamine and deionized water in a molar ratio of TPAOH to (NH)₄)₂SiF₆∶EDA∶H₂O = 0.36: 1: 0.576: 27; the room temperature is 20-30 ℃, and the stirring time is 4 h.

9. The method according to claim 1, wherein the hydrothermal temperature in the step 5) is 100 ℃.

10. The method of claim 1, wherein the drying temperature in the steps 2) and 5) is 60 ℃.