CN102527613A - Liquid-phase deposition-impregnation preparation method of micro/nano low-surface hydrophobic composite anti-scaling coating - Google Patents

Abstract

The invention discloses a liquid-phase deposition-impregnation preparation method of a micro/nano low-surface hydrophobic composite anti-scaling coating, which includes the following steps of (a) grinding, polishing and cleaning a stainless steel substrate to be deposited; (b) treating the stainless steel substrate with diluted acid ultrasonically, forming a coarse structural layer on the surface of the stainless steel substrate, washing and cleaning the surface with distilled water and then drying the same at the room temperature; (c) placing the stainless steel substrate with the surface having the coarse structural layer into mixed solution in a constant-temperature water bath with the temperature ranging from 20 degrees to 80 degrees to prepare a substrate chip by means of deposition; (e) sintering the dried substrate chip in a resistance furnace under protection of N2 and taking the sintered substrate chip out of the resistance furnace after reducing the temperature of the sintered substrate chip to the normal temperature; (f) impregnating the substrate chip with a TiO2 coating into fluorosilane hydrophobic solution of the mass concentration ranging from 0.1% to3%, taking out the same and then drying in an oven with the temperature ranging from 100 DEG C to 200 DEG C. The coating prepared by the method is thin, compact, uniform and free of cracking and can be combined with the substrate firmly.

Description

Liquid-phase deposition-dipping preparation method of a micro-nano low-surface hydrophobic composite antifouling coating

technical field

The invention relates to a method for preparing a nanometer film surface with low surface energy, in particular to a method for preparing a hydrophobic nanometer-thick film surface on a stainless steel surface by using a liquid phase deposition method combined with an immersion method.

Background technique

At present, there are fouling problems in the operation of heat exchange equipment. The deposition of dirt leads to increased heat exchange resistance and lower heat exchange efficiency, resulting in energy waste and equipment wear, and even threatens the safe operation of equipment. In order to reduce the deposition of dirt, mechanical cleaning or chemical cleaning agents are used to remove scale, which generally has the problems of high cost and secondary pollution. Studies have shown that reducing the surface energy of heat transfer surfaces can significantly reduce fouling formation. The researchers adopted surface treatment technology to treat the heat transfer surface to reduce the surface energy of the heat transfer surface. Such as magnetron sputtering PTFE, ion sputtering DLC, dynamic ion implantation of H, N, molecular self-assembly, etc. are used to prevent scale. However, these methods generally have problems such as high cost or complicated equipment. As a thin film preparation method developed in recent years, the liquid deposition method has many advantages, such as relatively simple preparation equipment, mild preparation temperature, and can be used for coating preparation on substrates that are not resistant to high temperatures. The size and shape of the substrate are not limited. etc. It has been widely used in the preparation of functional thin films, especially in the process of forming oxide thin films in ultra-large-scale integrated circuits, metal-oxide semiconductors and liquid crystal display devices in the microelectronics industry.

Since the hydrophobic or superhydrophobic solid surface has very low surface free energy, its boiling characteristics and fouling deposition characteristics are quite different from ordinary surfaces, so the research on low-energy surfaces for pool boiling heat transfer and antifouling is becoming more and more important. Caused widespread concern. Using fluorosilane to hydrophobize the heat transfer surface to reduce the surface energy of the heat transfer surface can achieve the dual purpose of heat transfer enhancement and anti-fouling at the same time.

The documents related to the chemical liquid phase deposition method include: Chinese patent 03100475.X prepares a saturated hydrofluorosilicic acid solution by adding silicon dioxide, etc. to the hydrofluorosilicic acid solution, and coats the semiconductor components with a protective film . Chinese patent 200710168732.1 provides a method for preparing titanium dioxide coated capillary column by liquid phase deposition method. Using ammonium fluorotitanate as raw material, a titanium dioxide film layer is deposited on the inner wall of quartz capillary by liquid phase deposition method, and is used for the separation of proteins and polypeptides , because the capillary column is not resistant to high temperature, the sintering temperature of the film is low, and the bond between the film and the capillary is not strong, so it is difficult to apply to the fields of heat transfer and dirt. Chinese patent ZL 200710060653.9 reports a method of preparing a nanometer-thick titanium dioxide film on a copper substrate by liquid phase deposition. It is not resistant to high temperature sintering, and the sintering temperature of the coating is low. Zeng Zhenou et al. (Zeng Zhenou, Xiao Zhengwei, Zhao Guopeng. Modern Coating Technology, 2007: 45-51) prepared titanium dioxide coating on 304 stainless steel by liquid phase deposition method. Chinese patent CN 101760737A reported that a dense micro-nano TiO ₂ coating was prepared on a stainless steel substrate by liquid phase deposition, but the surface energy of the coating was high and the hydrophobicity was not very good. The relevant documents on improving the hydrophobicity of the film are: Akamatsu Y et al. (Akamatsu Y et al. Thin Solid Films, 2001, 389: 138-145) studied the principle of the hydrolysis process of heptadecafluorodecyltrimethoxysilane, and prepared anti- Foggy automotive glass improves the hydrophobicity of the glass, but the prepared film is not heat-treated, so it is difficult to apply to the field of heat transfer. Chinese patent ZL 02115493.7 discloses the method for preparing hydrophobic liquid and manufacturing hydrophobic glass with tridecafluorooctyl trioxysilane, tetraethyl orthosilicate, hydrochloric acid, deionized water and hydrochloric acid, and the reported hydrophobic glass The contact angle can reach 90-100°, but this method is more suitable for surface modification of glass before installation. However, after the glass is coated with hydrophobic liquid, it needs to be heat treated at 200-350°C. This method is difficult to use after installation. and glass coating during use. Chinese patent CN1211500C uses ethyl acetoacetate, ethanol, water and tetrabutyl titanate to prepare TiO ₂ sol, prepares TiO ₂ film on the metal substrate by pulling method, and performs fluorosilylization treatment on the film surface to improve the TiO ₂ The hydrophobicity of the film reduces the corrosion current of the metal by about 3 orders of magnitude; although the film prepared by the sol-gel method has a good anti-corrosion effect, the film is thick and easy to crack, and the TiO ₂ coating The preparation method of the layer is more complicated. Chinese patent CN100429009C reports a method for forming a hydrophobic transparent film on the surface of substrates such as glass, ceramics, metal or paint, modifying the surface of the substrate with aluminum oxide, silicon oxide or titanium oxide, and using a hydroxylated fluorosilane solution Prepare a hydrophobic film with a thickness of several to tens of nanometers, and the water contact angle of the prepared film is 105-111°, but when using titanium oxide sol to treat the surface of the metal substrate, no sintering technology is used, which will make the film It is not firmly combined with the metal substrate, so it is difficult to be used in the fields of boiling heat transfer and fouling. Throughout the literature, there have been no reports on the use of low-energy fluorosilane hydrophobic composite coatings for micro-nano enhanced boiling heat transfer and anti-fouling methods.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art and provide a liquid-phase deposition-dipping preparation method of a micro-nano low-surface hydrophobic composite anti-fouling coating with dual functions of enhancing boiling evaporation heat transfer and anti-scaling.

A liquid-phase deposition-dipping preparation method of a micro-nano low-surface hydrophobic composite antifouling coating of the present invention, it comprises the following steps:

(a) Grinding, polishing and cleaning the stainless steel substrate to be deposited to obtain a clean and bright surface;

(b) Ultrasonically treat the stainless steel substrate with a dilute acid with a mass percentage of 1%-3% to form a rough structure layer on the surface of the stainless steel substrate, rinse it with distilled water, and dry it at room temperature;

(c) Deposit the stainless steel substrate with a rough structure layer on the surface in a mixed solution in a constant temperature water bath at 20-80°C to deposit the substrate. The preparation method of the mixed solution is as follows: chemically pure (NH ₄ ) ₂ TiF ₆ and analytically pure H ₃ BO ₃ were prepared into a uniform mixed solution, and the concentration of (NH ₄ ) ₂ TiF ₆ and H ₃ BO ₃ in the mixed solution were 0.05-0.5mol/L, 0.07-0.6 mol/L;

(d) the substrate deposited in the mixed solution is rinsed with distilled water to remove TiO remaining on the surface of the substrate ₂ solid particles, and then dry;

(e) putting the dried substrate into _N in a resistance furnace protected by sintering, and after the sintering is completed, drop to normal temperature and take it out, so that _TiO is obtained on the substrate Coating;

(f) Immerse the substrate with _TiO2 coating in a fluorosilane hydrophobic solution with a mass concentration of 0.1%-3%, take it out and dry it in an oven at a temperature of 100-200°C, that is, place it on a stainless steel substrate Composite hydrophobic coating is prepared; the preparation method of described fluorosilane hydrophobic solution is: (1) using isopropanol as solvent, adding perfluorodecyltriisopropoxysilane and mass concentration of 3% to the solvent successively dilute hydrochloric acid solution, the addition of the perfluorodecyltriisopropoxysilane is 0.001-0.03 times the mass of isopropanol, and the addition of the dilute hydrochloric acid is 0.0003-0.006 times the mass of isopropanol (2) Put the solution into a magnetic stirrer and stir for 10-60min, then add activated carbon, stand at room temperature for polycondensation and dehydration for 0.5-2h, filter through a filter cloth, and obtain a mass concentration of 0.1%-3%. Fluorosilane hydrophobic solution, the amount of activated carbon added is 0.006-0.06 times the mass of isopropanol.

In the actual operation process of the chemical liquid deposition preparation method of the present invention, bright coatings of different colors can be obtained according to different deposition concentrations, deposition times, programmed heating rates of resistance furnaces and sintering temperatures, and each coating has a dense and uniform appearance. The prepared coating is thinner, dense and uniform without cracking, and more firmly bonded to the substrate. In addition, this patent performs subsequent hydrophobic treatment on the titanium oxide coating, which greatly improves the hydrophobicity of the coating, reduces the surface energy, and significantly improves the enhanced heat transfer and anti-fouling performance of the coating, and the stainless steel substrate is roughened. , so that the surface energy of the prepared coating is lower. The contact angle of the film surface prepared by the method is greater than 110°, and the surface energy is between 1.2-13.0mJ·m ^-2 , which is significantly lower than that of stainless steel and titanium dioxide surfaces. The Ra value of the sintered thickness surface coating is basically the same as the Ra value after polishing by roughness meter measurement and AFM detection. The application of this heat transfer surface for pool boiling heat transfer and anti-scaling research shows that this surface can effectively prevent the fouling in boiling liquid from depositing on the surface. Since the coating thickness is much smaller than that of the 304 stainless steel sample, the prepared sample can be strengthened. The boiling heat transfer process has good effect and has the prospect of industrialization. Compared with Zeng Zhenou's literature, the coating prepared by this patent is thinner in nanoscale thickness (32.6-180.5nm). Therefore, when used in the field of heat transfer, the surface additional thermal resistance is small.

Description of drawings

Fig. 1 is the process flow diagram of a kind of micro-nano hydrophobic type liquid phase deposition-dipping composite antifouling coating preparation method of the present invention;

Fig. 2-a and Fig. 2-b are the scanning electron micrographs of the composite coating of embodiment 1 and embodiment 2 respectively;

Fig. 2-c is the scanning electron micrograph of embodiment 3 superhydrophobic fluorosilane coating;

Fig. 3 is the XPS (X-ray photoelectron spectrum) figure of fluorosilane composite coating in embodiment 1;

Fig. 4 is the AES (Auger electron spectrum) figure of fluorosilane composite coating in embodiment 2;

Fig. 5 is the XPS (X-ray photoelectron spectrum) figure of fluorosilane composite coating in embodiment 3;

Fig. 6 is the fouling thermal resistance curve obtained by putting different surfaces into the pool boiling device for fouling experiments.

Detailed ways

The present invention will be further described below in combination with specific embodiments and implementation examples.

The method of the present invention is improved and optimized on the basis of Zeng Zhenou et al.’s literature research and reference to patents ZL 200710060653.9 and CN 101760737A.

Referring to Fig. 1, a method for preparing a micro-nano hydrophobic liquid phase deposition-dipping composite antifouling coating of the present invention comprises the following steps: (a) grinding, polishing and cleaning the stainless steel substrate to be deposited to obtain a clean and bright Surface; (b) Ultrasonic treatment of the stainless steel substrate with a mass percentage of 1%-3% dilute acid to form a rough structure layer on the surface of the stainless steel substrate, rinsed with distilled water, and dried at room temperature, preferably the dilute acid is hydrochloric acid or nitric acid; ( c) Place the stainless steel substrate with a rough structure layer on the surface in a mixed solution in a constant temperature water bath at 20-80°C to deposit and prepare the substrate (below the value of the temperature range of the constant temperature water bath, the deposition time required to prepare a coating of the required thickness higher than this temperature range value, the water in the solution evaporates, easily forming large particles, and it is difficult to prepare a coating), the preparation method of the mixed solution is as follows: chemically pure (NH ₄ ) ₂ TiF ₆ , analytically pure H ₃ BO ₃ is prepared into a uniform mixed solution, and the concentration of (NH ₄ ) ₂ TiF ₆ and H ₃ BO ₃ in the mixed solution is respectively 0.05-0.5mol/L, 0.07-0.6mol/L (lower than this concentration range, the amount of reactant is small, it is difficult to prepare coating; higher than this concentration, the deposition solution is turbid, which is not conducive to the preparation of coating); (d) the substrate deposited in the mixed solution is rinsed with distilled water to remove TiO ₂ solid particles remaining on the surface of the substrate, and then dry; (e) put the dried substrate into N ₂ protected resistance furnace for sintering, after the sintering is completed, drop to normal temperature and take it out, that is, obtain TiO on the substrate ₂ coatings; (f) immersing the substrate with _TiO2 coating in a fluorosilane hydrophobic solution with a mass concentration of 0.1%-3%, the immersion time is preferably 1h-3h (less than this time range, the prepared The hydrophobicity of the coating is not good, higher than this range, the standing time is too long, the hydrophobicity of the coating is meaningless), and then the dipped substrate is put into an oven with a temperature of 100-200 ° C to dry ( Below this temperature range, the coating cannot be dried, and above this temperature range, the coating is easily damaged), that is, a composite hydrophobic coating is prepared on the substrate. The preparation method of the described fluorosilane aqueous solution is as follows: (1) using isopropanol as a solvent, sequentially adding perfluorodecyltriisopropoxysilane and dilute hydrochloric acid with a mass concentration of 3% to the solvent to prepare the solution; The addition of said perfluorodecyltriisopropoxysilane is 0.001-0.03 times of the quality of isopropanol, and the addition of said dilute hydrochloric acid is 0.0003-0.006 times of the quality of isopropanol; (less than this range , the amount of hydrolysis of the fluorosilane solution is small, above this range, the hydrolysis of fluorosilane is too fast, and the hydrophobic coating cannot be formed); (2) put the solution in a magnetic stirrer and stir for 10-60min (below this time range, the hydrolysis Incomplete, higher than this range, hydrolysis has been completed, too long is meaningless), then add activated carbon, stand at room temperature for polycondensation and dehydration for 0.5-2h (condensation time is less than this range, polycondensation is not complete, higher than the range of polycondensation time , the polycondensation has been completed, it is meaningless for too long time), and the filter cloth is filtered to obtain a mass concentration of 0.1%-3% (below this concentration range, the hydrophobicity of the prepared coating is not good, and if it is higher than this concentration, fluorine is wasted silane reactant) fluorosilane hydrophobic solution, the amount of activated carbon added is 0.006-0.06 times of the mass of isopropanol (the amount of activated carbon is lower than this range, the absorption of moisture in the solution is not complete, and if it is higher than this range, hydrolysis The reaction is too rapid to make a hydrophobic coating).

Preferably, the grinding and polishing steps in the step (a) are: (1) rough grinding the outer surface of the stainless steel substrate until the surface of the stainless steel metal is exposed; Large texture wear marks; (3) Use a 600-mesh cylindrical louver emery cloth wheel to polish the stainless steel substrate until all the coarser textures are removed; (4) Use 800-2000-mesh sandpaper sheets to finely grind the stainless steel substrate to remove Fine streaks on the polished surface; (5) Polish the surface of the stainless steel substrate with a metal polisher coated with polishing soap on a wool polishing wheel until the polished texture is no longer visible.

Preferably, the cleaning step in the step (a) is: (1) using 10% NaOH solution by mass percentage to ultrasonically soak the stainless steel substrate for cleaning for 5-10 minutes, remove stubborn grease, and then rinse it with tap water; (2) Put the stainless steel substrate into acetone with a mass ratio greater than 99.5% and absolute ethanol with a mass ratio greater than 99.7% for ultrasonic cleaning for 5-10 minutes and then take it out; (3) ultrasonically clean the stainless steel substrate with distilled water for 5-10 minutes to completely remove the surface Residual acetone and absolute ethanol; (4) dry the cleaned stainless steel substrate and place it in an airtight container for future use.

The time of the ultrasonic treatment in the step (b) is 30s-10min. (Below or above this time range, it is unfavorable to the preparation of subsequent coating hydrophobicity)

The deposition time in the step (c) is 2-30 hours. (below this range, it is difficult to prepare titanium dioxide coating, and above this range, the coating is easy to crack)

The heating rate of the sintering in the step (e) is 2-8°C/min, and the sintering temperature is 300-800°C (below this range of heating rate, the time required to reach the sintering temperature is too long, higher than this range, The coating is easy to fall off; below this sintering temperature range, the titanium oxide coating is not well bonded to the substrate and is not durable; above this range, the stainless steel substrate is easily oxidized).

The drying time in the oven in the step (f) is 2-3 hours. (Below this time range, the drying of the coating is not complete; above this range, the drying time of the hydrophobic coating is too long, which is meaningless to the coating preparation)

Example 1

(a)) Roughly grind the outer surface of the stainless steel substrate until the stainless steel metal surface is exposed; carry out medium grinding to remove the deep and large texture wear marks left by the coarse grinding process; use a 600-mesh cylindrical louver emery cloth wheel to polish the stainless steel substrate until Sand away all coarser grain; finish grind the stainless steel substrate with a 1000 grit sandpaper sheet to remove fine streaks on the surface to be polished; polish the stainless steel substrate surface with a metal polisher coated with polishing soap on a wool buffing wheel , until the polished texture is no longer visible to the naked eye; then use 10% NaOH by mass percentage to ultrasonically soak and clean for 5 minutes to remove stubborn grease, and then rinse it with tap water; then put the stainless steel substrate in turn in acetone Ultrasonic cleaning with absolute ethanol with a mass ratio greater than 99.7% was performed for 8 minutes and then taken out. Finally, the stainless steel substrate was ultrasonically cleaned with distilled water for 7 minutes to thoroughly remove the remaining acetone and absolute ethanol on the surface, dried with a hair dryer, and placed in an airtight container (b) ultrasonically treat the stainless steel substrate with 1% dilute hydrochloric acid by mass percentage for 30s to form a rough structure layer on the surface of the stainless steel substrate, rinse it with distilled water, and dry it at room temperature; (c) chemically pure (NH ₄ ) ₂ TiF ₆ and analytically pure H ₃ BO ₃ were prepared into a uniform mixed solution, and the molar concentrations of (NH ₄ ) ₂ TiF ₆ and H ₃ BO ₃ in the mixed solution were 0.05mol/L and 0.07mol/L, respectively; Put the prepared deposition solution in a constant temperature water bath with a temperature of 20°C, put the stainless steel substrate with a rough surface into the solution, and the deposition time is 5 hours; (d) After the deposition is completed, take out the substrate and rinse it with distilled water several times surface to remove the TiO ₂ solid particles on the surface of the substrate, and then dry at room temperature; (e) put the dried substrate into a muffle furnace for heating at a heating rate of 2°C/min, when the temperature rises to 500 At ℃, keep the constant temperature for 2h, turn off the heating device, and obtain a uniform and dense _TiO2 film surface after cooling; (f) weigh 160g of isopropanol solvent, add 0.16g of perfluorodecyltriisopropoxyl in the solvent Silane, then add 0.05g of 3% dilute hydrochloric acid in the solution, so that the mass concentration of perfluorodecyltriisopropoxysilane after preparation is 0.1%, add magnetron and stir for 10min to hydrolyze, add 1g of activated carbon, Polycondensate at room temperature for 0.5h, and filter through a filter cloth to obtain a hydrophobic solution. Place the sample in a hydrophobic solution, soak it at room temperature for 1 hour, take it out, dry it in the air, and put it in an oven at 100°C for 2 hours. The surface of the nano-membrane is completely hydrophobized to construct a hydrophobic nano-membrane. Table 1 is the contact angle measurement data of Example 1.

The contact angle of table 1 embodiment 1 coating and surface energy

It can be seen from Figure 2-a that nano-titanium dioxide particles with larger particle sizes are deposited on the surface of the coating, and the surface coating is relatively dense; the surface contains many round or long strip nanopores.

It can be seen from Figure 3 that the electrons on the Si2p orbital are excited, and its binding energy is 102.6 eV, corresponding to the characteristic peak of the Si-O bond, which proves the existence of the silicon-oxygen bond in the coating, and the binding energy is 529.4 eV and 532.5 The XPS peaks at eV correspond to the characteristic peaks of O-Ti bond and O-Si bond, respectively, the XPS peaks with binding energy of 458.7 eV and 464.9 eV correspond to the characteristic peaks of Ti-O bond, and the XPS peak with binding energy of 688.9 eV is at Near the characteristic peaks of -CF ₂ group and -CF ₃ group.

The Ti-O bond corresponds to the titanium oxide coating on the substrate, while the Si-O bond is the chemical bond connecting the fluorosilane to the titanium oxide coating, and the -CF ₂ and -CF ₃ groups come from the fluorosilane coating middle.

It can be seen from Figure 6 that the fouling thermal resistance of the fluorosilane hydrophobic surface is significantly smaller than that of stainless steel, and the slope of the fouling curve (fouling deposition rate) at the initial moment of the fluorosilane hydrophobic surface is smaller than that on the stainless steel surface.

Example 2

(a) Pre-treat the stainless steel substrate, use an angle grinder equipped with louver blades to roughly grind the outer surface of the cut stainless steel sample, remove surface dirt, scale and large-pore defects, and expose the stainless steel metal surface; then replace Use a nylon grinding disc for medium grinding to remove the deep and large textured grinding marks left by the rough grinding process, and select the substrate surface to be deposited on the coating; use the engraving handle of the metal polishing machine, and use a 600-mesh cylindrical louver abrasive cloth wheel Sand the base, making sure the surface is completely sanded to remove the coarser texture from the previous step. Then install a 90° angle machine or a gun-type reciprocating machine, and use 800-mesh sandpaper to finely grind the substrate to remove fine stripes on the surface to be polished; then use the die-cutting handle of the metal polishing machine combined with wool The polishing wheel is coated with commercially available green polishing soap, and the surface of the sample is polished until the polishing texture is no longer visible; then use 10% NaOH by mass percentage for ultrasonic soaking and cleaning for 8 minutes to remove stubborn grease, and then rinse with tap water; Then put the stainless steel substrate into acetone with a mass ratio greater than 99.5% and absolute ethanol with a mass ratio greater than 99.7% for ultrasonic cleaning for 10 minutes, and then take it out. Finally, ultrasonically clean the stainless steel substrate with distilled water for 5 minutes to completely remove the remaining acetone on the surface and absolute ethanol, blow dry with a hair dryer, and store in an airtight container; (b) ultrasonically treat the stainless steel substrate with 2% dilute nitric acid for 3 minutes to form a rough structure layer on the surface of the stainless steel substrate, rinse it with distilled water, Dry at room temperature; (c) Prepare chemically pure (NH ₄ ) ₂ TiF ₆ and analytically pure H ₃ BO ₃ into a uniform mixed solution, and the substances in the mixed solution (NH ₄ ) ₂ TiF ₆ and H ₃ BO ₃ The concentrations are 0.5mol/L and 0.6mol/L respectively; the prepared deposition solution is placed in a constant temperature water bath with a temperature of 50°C, and the stainless steel substrate with rough surface structure is put into the solution, and the deposition time is 15h; (d ) After the deposition is complete, the substrate is taken out, and the surface is repeatedly rinsed with distilled water to remove TiO ₂ solid particles on the surface of the substrate, and then dried; (e) the dried substrate is put into a nitrogen-protected muffle furnace for heating , the heating rate is 5°C/min. When the temperature rises to 300°C, keep the constant temperature for 2h, turn off the heating device, and obtain a uniform and dense _TiO2 film surface after cooling; (f) Weigh 160g of isopropanol solvent, add to Add 1.62g of perfluorodecyltriisopropoxysilane in the solvent, then add 0.3g of 3% dilute hydrochloric acid in the solution, so that the mass concentration of perfluorodecyltriisopropoxysilane after preparation is about Add 1% to a magnetic stirrer and stir for 25 minutes for hydrolysis, add 2g of activated carbon, polycondense at room temperature for 1 hour, and filter through a filter cloth to obtain a hydrophobic solution. Place the sample in the hydrophobic solution, soak it at room temperature for 3 hours, take it out, dry it in the air, and put it in an oven at 140°C for 2.5 hours. The surface of the nano-membrane is completely hydrophobized to construct a hydrophobic nano-membrane. Table 2 is the contact angle measurement data of Example 2.

Contact angle and surface energy of table 2 embodiment 2

It can be seen from Figure 2-b that a large number of large and dense titanium oxide particles are deposited on the surface of the coating, and the surface is dense; the surface contains many round or elongated nanopores. After the titanium dioxide coating is treated with fluorosilane, the pore size becomes smaller.

It can be seen from Figure 4 that the element profile curve is divided into three parts, the leftmost is the fluorosilane coating, the middle Ti and O element platform area is the TiO ₂ coating area, and the far right is the interface area between the coating and the stainless steel substrate. On the surface of the coating, the content of F and Si elements is very small, the highest content of F element is about 2.3%, and the highest content of Si element is 10.23%. In addition, there are also a small amount of F and Si elements inside the titanium dioxide coating, which may be a small amount of fluorine This is caused by silane penetration into the interior of the _TiO2 coating.

It can be seen from Figure 6 that the fouling thermal resistance of the fluorosilane hydrophobic surface is significantly smaller than that of stainless steel, and the slope of the fouling curve (fouling deposition rate) at the initial moment of the fluorosilane hydrophobic surface is smaller than that on the stainless steel surface.

Example 3

(a) Pretreat the stainless steel base, use an angle grinder equipped with louver blades to roughly grind the outer surface of the cut stainless steel sample, remove surface dirt, scale and large pores, and expose the 304 stainless steel metal surface; then Replace the nylon grinding disc for medium grinding, remove the deep and large textured grinding marks left by the coarse grinding process, and select the substrate surface to be deposited coating; replace the die handle of the metal polishing machine with 800-mesh cylindrical louver abrasive cloth Grind the base of the wheel, making sure that the surface is completely sanded to remove the coarser grain left over from the previous step. Then install a 90° angle machine or a gun-type reciprocating machine, and use 2000-mesh sandpaper to finely grind the substrate to remove fine stripes on the surface to be polished; then use the die-cutting handle of the metal polishing machine combined with wool The polishing wheel is coated with commercially available green polishing soap, and the surface of the sample is polished until the polishing texture is no longer visible; then use 10% NaOH with a mass percentage of 10% for ultrasonic soaking and cleaning for 10 minutes to remove stubborn grease, and then rinse with tap water; Then put the stainless steel substrate into acetone with a mass ratio greater than 99.5% and absolute ethanol with a mass ratio greater than 99.7% for 5 minutes and then take it out. Finally, use distilled water to ultrasonically clean the stainless steel substrate for 10 minutes to completely remove the remaining acetone on the surface and absolute ethanol, blow dry with a hair dryer, and store in an airtight container; (b) ultrasonically treat the stainless steel substrate with 3% dilute hydrochloric acid for 10 minutes to form a rough structure layer on the surface of the stainless steel substrate, rinse it with distilled water, Dry at room temperature; (c) Prepare chemically pure (NH ₄ ) ₂ TiF ₆ and analytically pure H ₃ BO ₃ into a uniform mixed solution, and the substances in the mixed solution (NH ₄ ) ₂ TiF ₆ and H ₃ BO ₃ The concentrations are 0.1mol/L and 0.2mol/L respectively; the prepared deposition solution is heated in a water bath with a temperature of 80°C, and the stainless steel substrate with a rough structure on the surface is put into the solution, and the deposition time is 30h; (d ) after the deposition is completed, the substrate is taken out, and the surface is washed with distilled water several times to remove the TiO ₂ solid particles on the surface of the substrate, and then dried; (e) the dried substrate is put into a muffle furnace for heating, and the heating rate is 8°C/min, when the temperature rises to 800°C, keep the constant temperature for 2 hours, turn off the heating device, and obtain a uniform and dense _TiO2 film surface after cooling; (f) Weigh 160g of isopropanol solvent, add The perfluorodecyltriisopropoxysilane of 4.98g, then add 1.0g of 3% dilute hydrochloric acid in the solution, make the mass concentration of perfluorodecyltriisopropoxysilane after preparation about 3% , add magneton and stir for 1h to hydrolyze, add 10g of activated carbon, polycondense at room temperature for 2h, and filter through a filter cloth to obtain a hydrophobic solution. Place the sample in a hydrophobic solution, soak it at room temperature for 3 hours, take it out, dry it in the air, and put it in an oven at 200°C for 3 hours. The surface of the nano-membrane is completely hydrophobized to construct a hydrophobic nano-membrane. Table 3 is the contact angle measurement data of Example 3.

The contact angle of table 3 embodiment 3 coatings and surface energy

It can be seen from Figure 2-c that a large number of large and dense titanium oxide particles are deposited on the surface of the coating, and the surface is dense; the surface contains many round or long strip nanopores. After the titanium dioxide coating is treated with fluorosilane, the pore size becomes smaller.

It can be seen from Fig. 5 that there are obvious characteristic peaks of Ti-O bond and Si-O bond as well as characteristic peaks of -CF ₂ group and -CF ₃ group in the figure. The Ti-O bond corresponds to the titanium oxide coating on the substrate, while the Si-O bond is the chemical bond connecting the fluorosilane to the titanium oxide coating, and the -CF ₂ and -CF ₃ groups come from the fluorosilane coating middle.

Compared with Example 1, the proportion of F element in Example 3 is significantly increased, indicating that the content of F element on the surface of the coating prepared in Example 3 is significantly higher than that of the surface prepared in Example 1.

It can be seen from Figure 6 that the fouling thermal resistance of the fluorosilane hydrophobic surface is significantly smaller than that of stainless steel, and the slope of the fouling curve (fouling deposition rate) at the initial moment of the fluorosilane hydrophobic surface is smaller than that on the stainless steel surface.

Claims (7)

1. liquid deposition-the impregnation preparation method of the compound antiscale coating of micro-nano low surface hydrophobicity type is characterized in that it may further comprise the steps:

(a) polish, polish and cleans at the stainless steel-based end that will be to be deposited, obtains the surface of clean light;

(b) use mass percent to make stainless steel-based basal surface form the coarse structure layer as the stainless steel-based end of diluted acid sonicated of 1%-3%, clean with distilled water flushing, room temperature is dried;

(c) the stainless steel-based end that the surface is had a coarse structure layer, place the mixed solution deposition preparation substrate of the water bath with thermostatic control that is in 20-80 ℃, and the compound method of described mixed solution is following: with chemical pure (NH ₄) ₂TiF ₆, analytically pure H ₃BO ₃Be mixed with the mixed solution of homogeneous, (NH in the mixed solution ₄) ₂TiF ₆And H ₃BO ₃Amount of substance concentration be respectively 0.05-0.5mol/L, 0.07-0.6mol/L;

(d) will be in described mixed solution post-depositional substrate remain in the TiO of substrate surface with removal with distilled water flushing ₂Solid particle dries then;

The substrate that (e) will dry is put into N ₂Carry out sintering in the resistance furnace of protection, reduce to normal temperature after sintering is accomplished and take out, promptly on substrate, obtain TiO ₂Coating;

(f) will have TiO ₂The substrate of coating impregnated in the silicon fluoride hydrophobic sol that mass concentration is 0.1%-3%, and the baking oven of putting into temperature after the taking-up and be 100-200 ℃ is dried, and promptly on the stainless steel-based end, prepares the composite hydrophobic coating; The preparation method of described silicon fluoride hydrophobic sol is: (1) is solvent with the isopropyl alcohol; In solvent, add perfluor decyl three isopropoxy silane and mass concentration successively and be 3% watery hydrochloric acid and prepare solution; The addition of described perfluor decyl three isopropoxy silane is 0.001-0.03 a times of isopropyl alcohol quality, and the addition of described watery hydrochloric acid is 0.0003-0.006 a times of isopropyl alcohol quality; (2) solution is put into the magneton agitator and stir 10-60min; And then the adding active carbon, at room temperature leaving standstill polycondensation dehydration 0.5-2h, filter cloth filters; Making mass concentration is the silicon fluoride hydrophobic sol of 0.1%-3%, and the addition of described active carbon is 0.006-0.06 a times of isopropyl alcohol quality.

2. liquid deposition-the impregnation preparation method of the compound antiscale coating of micro-nano low surface hydrophobicity type according to claim 1, it is characterized in that: the grinding and buffing step in the described step (a) is: roughly grind until exposing the stainless steel metal surface the stainless steel outer surfaces of substrates (1); (2) carry out middle mill, remove the dark large texture polishing scratch that pass stays; (3) it is all than open grain until polishing off to select for use the cylindrical blinds emery cloth of 600 purposes wheel to be polished in the stainless steel-based end; (4) select 800-2000 purpose sand paper disc for use, to finish grinding to remove the stria on the polished surface at the stainless steel-based end; (5) bore hole adopt the metal polishing machine that is coated with clear boiled soap on the wool polishing wheel that stainless steel-based basal surface is polished, till can't see the polishing texture.

3. liquid deposition-the impregnation preparation method of the compound antiscale coating of micro-nano low surface hydrophobicity type according to claim 1 and 2; It is characterized in that: the cleaning step in the described step (a) is: (1) service property (quality) percentage is 10% the stainless steel-based end cleaning of the ultrasonic immersion of NaOH solution 5-10min; Remove the intractable grease, rinse well with running water then; (2) mass ratio being put at the stainless steel-based end successively carries out taking out behind the ultrasonic cleaning 5-10min greater than 99.7% absolute ethyl alcohol greater than 99.5% acetone and mass ratio; (3) with the stainless steel-based end 5-10min of distilled water ultrasonic cleaning, thoroughly to remove surface remaining acetone and absolute ethyl alcohol; (4) it is for use to dry up and place closed container to preserve the cleaned stainless steel substrate.

4. liquid deposition-the impregnation preparation method of the compound antiscale coating of micro-nano low surface hydrophobicity type according to claim 1, it is characterized in that: the time of the sonicated in the described step (b) is 30s-10min.

5. liquid deposition-the impregnation preparation method of the compound antiscale coating of micro-nano low surface hydrophobicity type according to claim 1, it is characterized in that: the sedimentation time in the described step (c) is 2-30 hour.

6. liquid deposition-the impregnation preparation method of the compound antiscale coating of micro-nano low surface hydrophobicity type according to claim 1, it is characterized in that: the heating rate of the sintering in the described step (e) is 2-8 ℃/min, sintering temperature is 300-800 ℃.

7. liquid deposition-the impregnation preparation method of the compound antiscale coating of micro-nano low surface hydrophobicity type according to claim 1, it is characterized in that: the drying time in the baking oven in the described step (f) is 2-3 hour.

Images