CN113445107B

CN113445107B - Ni-PTFE-SiC super-hydrophobic anticorrosive coating and preparation method thereof

Info

Publication number: CN113445107B
Application number: CN202110716884.0A
Authority: CN
Inventors: 刘建国; 崔淦; 房秀婷; 邢潇; 李自力
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2021-06-28
Filing date: 2021-06-28
Publication date: 2022-05-13
Anticipated expiration: 2041-06-28
Also published as: CN113445107A

Abstract

The invention relates to the technical field of super-hydrophobic coatings, and provides a Ni-PTFE-SiC super-hydrophobic anticorrosive coating and a preparation method thereof. According to the invention, PTFE and SiC nano particles are added into a nickel-based plating solution, and a Ni-PTFE-SiC super-hydrophobic anticorrosive coating is prepared on a metal matrix by an electrodeposition method by utilizing the low surface energy and low friction coefficient of PTFE and the high hardness and high wear resistance of SiC, without secondary modification of the coating by using a low surface energy substance. The super-hydrophobic anti-corrosion coating has a micro-nano dual-scale structure and comprises a nickel metal layer, PTFE (polytetrafluoroethylene) and SiC nanoparticles embedded in the nickel metal layer, nickel crystals are adsorbed on the nanoparticles, and a large number of micro pores can be formed between the micro-nano dual-scale structure to intercept air, so that the coating achieves good hydrophobicity. Tests prove that the Ni-PTFE-SiC super-hydrophobic anticorrosive coating has a good anticorrosive effect on a matrix and has excellent mechanical stability and durability.

Description

Ni-PTFE-SiC super-hydrophobic anticorrosive coating and preparation method thereof

Technical Field

The invention relates to the technical field of super-hydrophobic coating treatment, in particular to a Ni-PTFE-SiC super-hydrophobic anticorrosive coating and a preparation method thereof.

Background

In recent years, the super-hydrophobic coating has great industrial potential in the fields of self-cleaning, oil-water separation, corrosion prevention, anti-icing, anti-fogging, drag reduction and the like, particularly in the aspect of corrosion prevention. The corrosion of metal in the world causes serious resource waste, economic loss and potential safety hazard, and the super-hydrophobic coating prepared on the surface of the metal substrate can effectively isolate the metal from a corrosive medium, thereby greatly reducing the corrosion rate.

However, the various super-hydrophobic coatings prepared at present generally have the problem of poor stability, so that the process of industrial application of the coatings is hindered. The reason for the poor stability of the superhydrophobic coating is mainly that: various preparation processes at present rely on surface modification of coatings by low surface energy substances to make the coatings super-hydrophobic, and the substances are easy to fall off in the using process; meanwhile, the surface structure and chemical properties of the super-hydrophobic surface are changed under the influence of a corrosive medium, so that the hydrophobicity is reduced. Chinese invention patent CN 112030213 a discloses a super-hydrophobic nickel tungsten/tungsten carbide composite coating, wherein a low surface energy substance must be used to perform secondary modification on the coating to make the surface reach a super-hydrophobic state, and the corrosion prevention effect of the super-hydrophobic surface is not described.

Disclosure of Invention

In view of the above, the invention provides a Ni-PTFE-SiC super-hydrophobic anticorrosive coating and a preparation method thereof. Compared with the surface modification type coating prepared by the traditional secondary modification method, the Ni-PTFE-SiC super-hydrophobic anticorrosive coating provided by the invention has better mechanical stability and durability.

In order to achieve the above object, the present invention provides the following technical solutions:

a preparation method of a Ni-PTFE-SiC super-hydrophobic anticorrosive coating comprises the following steps:

mixing polytetrafluoroethylene nanoparticles, SiC nanoparticles and nickel-based plating solution to obtain Ni-PTFE-SiC mixed solution;

and performing electrodeposition by taking the metal matrix as a cathode, a nickel plate as an anode and the Ni-PTFE-SiC mixed solution as plating solution to obtain the Ni-PTFE-SiC super-hydrophobic anticorrosive coating on the surface of the metal matrix.

Preferably, the solute of the nickel-based plating solution comprises nickel sulfate, nickel chloride, boric acid and ammonium chloride, and the solvent is water; the concentration of polytetrafluoroethylene nanoparticles in the Ni-PTFE-SiC mixed solution is 14-18 g/L, the concentration of SiC nanoparticles is 2-6 g/L, the concentration of nickel sulfate is 250-300 g/L, the concentration of nickel chloride is 40-50 g/L, the concentration of boric acid is 35-45 g/L, and the concentration of ammonium chloride is 40-50 g/L.

Preferably, the average particle size of the polytetrafluoroethylene nanoparticles is 0.7-0.9 μm, and the average particle size of the SiC nanoparticles is 0.5-0.7 μm.

Preferably, the Ni-PTFE-SiC mixed solution further includes a dispersant, and the dispersant is cetyl trimethyl ammonium bromide; the dosage of the dispersing agent is 3-5% of the total mass of the polytetrafluoroethylene nano-particles and the SiC nano-particles.

Preferably, in the electrodeposition process, the temperature of the plating solution is 50-60 ℃, the pH value is 3.5-4.5, the distance between the cathode and the anode is 5-6 cm, and the area of the anode is larger than that of the cathode.

Preferably, the electrodeposition is carried out under the condition of stirring, and the rotating speed of the stirring is 1200-1300 r/min.

Preferably, the electrodeposition comprises: sequentially carrying out first electrodeposition and second electrodeposition; the current density of the first electrodeposition is 3-7A/dm²The time is 10-20 min, and the current density of the second electrodeposition is 10-15A/dm²The time is 3-5 min.

Preferably, before the electrodeposition, the method further comprises the step of pretreating the metal substrate; the pretreatment comprises polishing, cleaning, alkali washing and acid washing which are sequentially carried out.

The invention also provides the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating prepared by the preparation method in the scheme, which has a micro-nano dual-scale structure and comprises a nickel metal layer and polytetrafluoroethylene nanoparticles and SiC nanoparticles embedded in the nickel metal layer, wherein nickel crystals in the nickel metal layer are adsorbed on the polytetrafluoroethylene nanoparticles and the SiC nanoparticles.

The invention provides a preparation method of a Ni-PTFE-SiC super-hydrophobic anticorrosive coating, which comprises the following steps: mixing Polytetrafluoroethylene (PTFE) nanoparticles, SiC nanoparticles and nickel-based plating solution to obtain Ni-PTFE-SiC mixed solution; and performing electrodeposition by taking the metal matrix as a cathode, a nickel plate as an anode and the Ni-PTFE-SiC mixed solution as plating solution to obtain the Ni-PTFE-SiC super-hydrophobic anticorrosive coating on the surface of the metal matrix. According to the invention, by utilizing the low surface energy and self-lubricity of PTFE nano particles and the high hardness and high wear resistance of SiC nano particles, the PTFE nano particles and the SiC nano particles are directly embedded into nickel-based metal through electrodeposition, nickel crystals are adsorbed on the PTFE nano particles and the SiC nano particles to form a micro-nano dual-scale structure, and the surface of the coating reaches a super-hydrophobic state without secondary modification. The preparation method provided by the invention has the advantages of simple steps, low cost, easy control of the process and no limitation of the shape of the matrix.

Further, the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating is prepared by adopting a two-step electrodeposition method, and specifically, the first electrodeposition is carried out by adopting a lower current density, the second electrodeposition is carried out by utilizing a higher current density, and the two different current densities are adopted for deposition, which means that the driving forces of the two electrodeposition processes are different in size, so that the nano particles with different sizes are fully deposited, the composite amount of the two particles in the coating is favorably improved, and the hydrophobicity of the obtained coating is further improved.

The invention also provides the Ni-PTFE-SiC super-hydrophobic anticorrosive coating prepared by the preparation method in the scheme, which comprises nickel-based metal, and polytetrafluoroethylene nanoparticles and SiC nanoparticles embedded in the nickel-based metal, wherein nickel crystals are adsorbed on the polytetrafluoroethylene nanoparticles and the SiC nanoparticles to form a micro-nano double-scale structure. A large number of micro pores are formed between the micro-nano double-scale structures, and the micro pores can intercept air to form an air cushion to prevent water from permeating, so that the coating has good hydrophobicity. The Ni-PTFE-SiC super-hydrophobic anti-corrosion coating provided by the invention has super-hydrophobic performance, so that a corrosive medium can be effectively isolated from contacting with a metal matrix, the main component of the coating is metallic nickel, the metallic nickel is a corrosion-resistant metal, and PTFE and SiC nano particles embedded in the coating also have good chemical inertness, so that the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating has excellent corrosion resistance.

In addition, the PTFE nano particles have lower surface energy, and the composite coating reaches a super-hydrophobic state without surface modification by utilizing the lower surface energy of the PTFE nano particles and the micro-nano structure of the surface of the coating, so that the defect that a surface modifier is easy to fall off is overcome; as surface modification is avoided, the chemical stability of PTFE and SiC nano particles is strong, and the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating has good durability in corrosive media. In addition, PTFE also has a lower friction coefficient, SiC has higher hardness and wear resistance, and the combination of the two can greatly improve the mechanical stability of the Ni-PTFE-SiC super-hydrophobic coating.

Drawings

FIG. 1 is a schematic perspective view of a Ni-PTFE-SiC superhydrophobic corrosion protection coating of the present invention;

FIG. 2 is a schematic plan view of a Ni-PTFE-SiC superhydrophobic corrosion protection coating of the present invention;

FIG. 3 shows the wetting process of the water droplets on the surfaces of different substances in example 1, wherein (a1) - (a5) are Ni, (b1) - (b5) are SiC, and (c1) - (c5) are PTFE;

FIG. 4 is a graph showing the dispersion of SiC nanoparticles in example 2 with different surfactants added, wherein (a) is SDS, (b) is CTAB, and (c) is FC-134;

FIG. 5 is the contact angle measurement results of the Ni-PTFE-SiC super-hydrophobic anti-corrosive coating in example 3;

FIG. 6 is an SEM photograph of Ni-PTFE-SiC super-hydrophobic anti-corrosive coating of example 3, (a) X10000, (b) X40000;

FIG. 7 is an EDS diagram of a Ni-PTFE-SiC superhydrophobic corrosion protection coating in example 3;

FIG. 8 is a plot of the polarization of the bare carbon steel substrate, the conventional Ni coating, and the Ni-PTFE-SiC superhydrophobic coating of example 4;

FIG. 9 is a schematic diagram of the sanding experiment of example 5;

FIG. 10 is a graph showing the static contact angle and the rolling angle of samples of example 5 at different abrasion distances, (a) showing a conventional surface-modified superhydrophobic coating, and (b) showing a Ni-PTFE-SiC superhydrophobic anticorrosive coating;

FIG. 11 is an optical photo of the corrosion morphology of the sample in different soaking times, wherein (a1) - (a5) are traditional surface modification type super-hydrophobic coatings, and (b1) - (b5) are Ni-PTFE-SiC super-hydrophobic anticorrosion coatings.

Detailed Description

The invention provides a preparation method of a Ni-PTFE-SiC super-hydrophobic anticorrosive coating, which comprises the following steps:

According to the invention, polytetrafluoroethylene nanoparticles, SiC nanoparticles and nickel-based plating solution are mixed to obtain Ni-PTFE-SiC mixed solution. In the invention, the average particle size of the polytetrafluoroethylene nanoparticles is preferably 0.7-0.9 μm; the average particle size of the SiC nano particles is preferably 0.5-0.7 mu m; the solute of the nickel-based plating solution preferably comprises nickel sulfate, nickel chloride, boric acid and ammonium chloride, the nickel sulfate preferably comprises nickel sulfate hexahydrate, the nickel chloride preferably comprises nickel chloride hexahydrate, and the solvent of the nickel-based plating solution preferably comprises water.

In the invention, the concentration of the polytetrafluoroethylene nanoparticles in the Ni-PTFE-SiC mixed solution is preferably 14-18 g/L, more preferably 14-16 g/L, and further preferably 14g/L, the concentration of the SiC nanoparticles is preferably 2-6 g/L, more preferably 4-6 g/L, and further preferably 6g/L, the concentration of the nickel sulfate is preferably 250-300 g/L, and more preferably 250-280 g/L, the concentration of the nickel chloride is preferably 40-50 g/L, and more preferably 40-45 g/L, the concentration of the boric acid is preferably 35-45 g/L, and more preferably 36-40 g/L, and the concentration of the ammonium chloride is preferably 40-50 g/L, and more preferably 45-50 g/L.

In the present invention, the Ni-PTFE-SiC mixed solution preferably further includes a dispersant, and the dispersant is preferably cetyltrimethylammonium bromide; the using amount of the dispersing agent is preferably 3% -5% of the total mass of the polytetrafluoroethylene and SiC nanoparticles, and more preferably 3.5-4.5%. According to the invention, the dispersing agent is added to improve the dispersibility of the nano particles, so that the nano particles are prevented from agglomerating, and hexadecyl trimethyl ammonium bromide is preferably used, so that the nano particles can be stably dispersed in an aqueous solution through a steric hindrance effect and an electrostatic repulsion effect, and the dispersing effect is better than that of other dispersing agents.

In the present invention, the mixing process of the polytetrafluoroethylene, the SiC nanoparticles, and the nickel-based plating solution preferably includes: mixing PTFE nano-particles, SiC nano-particles, a dispersing agent and water, and sequentially carrying out ultrasonic dispersion and magnetic stirring on the obtained mixed system to obtain a nano-particle dispersion liquid; dissolving nickel sulfate, nickel chloride, boric acid and ammonium chloride in water to obtain nickel-based plating solution; and mixing the nanoparticle dispersion liquid and a nickel-based plating solution to obtain the Ni-PTFE-SiC mixed liquid. In the present invention, the time for the ultrasonic dispersion is preferably 30min, and the time for the magnetic stirring is preferably 30 min.

After Ni-PTFE-SiC mixed liquid is obtained, the invention takes a metal matrix as a cathode, a nickel plate as an anode and the Ni-PTFE-SiC mixed liquid as plating liquid for electrodeposition, and the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating is obtained on the surface of the metal matrix. The invention has no special requirement on the material of the metal matrix, and the metal matrix which is well known to the technical personnel in the field can be adopted, such as a steel matrix.

In the present invention, the metal substrate is preferably pretreated before being subjected to electrodeposition; the pretreatment preferably comprises polishing, cleaning, alkali washing and acid washing which are sequentially carried out; before polishing, the metal matrix is preferably washed by deionized water, deoiled by acetone and dehydrated by absolute ethyl alcohol in sequence, and then dried for later use. In the invention, the grinding is preferably performed on the metal matrix by sequentially using 180#, 400#, 600#, 800#, 1200# sandpaper; the cleaning is preferably to firstly clean metal surface abrasive dust by using deionized water, then to sequentially use acetone and absolute ethyl alcohol to carry out ultrasonic cleaning, and the time for carrying out ultrasonic cleaning by using acetone and the time for carrying out ultrasonic cleaning by using absolute ethyl alcohol are preferably 3-5 min independently.

In the invention, the solute of the alkali washing liquid is preferably sodium hydroxide, sodium carbonate and sodium silicate, and the solvent is preferably water; the concentration of sodium hydroxide in the alkaline washing liquid is preferably 12g/L, the concentration of sodium carbonate is preferably 60g/L, and the concentration of sodium silicate is preferably 30 g/L; the temperature of the alkali washing is preferably 75 ℃, and the time is preferably 10 min.

In the invention, the acid for acid washing is preferably diluted hydrochloric acid with the mass fraction of 10%, and the time for acid washing is preferably 1 min; the invention activates the metal matrix by acid washing.

After the pretreatment is finished, the invention takes the pretreated metal matrix as a cathode, a nickel plate as an anode and the Ni-PTFE-SiC mixed solution as plating solution for electrodeposition to obtain the Ni-PTFE-SiC super-hydrophobic anticorrosive coating on the surface of the metal matrix. In the present invention, the purity of the nickel plate is preferably more than 99%; the distance between the anode and the anode is preferably 5-6 cm, the area of the anode is preferably larger than that of the cathode, and the surfaces of the anode and the cathode are opposite.

In the electrodeposition process, the temperature of the plating solution is preferably 50-60 ℃, more preferably 55 ℃, and the pH value is preferably 3.5-4.5, more preferably 4. In the embodiment of the present invention, it is preferable that the pH of the plating solution is periodically monitored during the electrodeposition, and if the pH of the plating solution is out of the above range, it is preferable that the pH of the plating solution is adjusted using sulfuric acid or ammonia water.

In the invention, the electrodeposition is preferably carried out under the condition of stirring, and the rotating speed of the stirring is preferably 1200-1300 r/min, and more preferably 1250-1300 r/min; the stirring is preferably magnetic stirring, and the magnetic stirring is used in the electrodeposition process, so that the stable dispersion of the nano particles and the timely transportation of substances are favorably maintained.

In the present invention, the electrodeposition preferably includes: sequentially carrying out first electrodeposition and second electrodeposition; the current density of the first electrodeposition is preferably 3-7A/dm²More preferably 4 to 7A/dm²More preferably 7A/dm²The time is preferably 10-20 min, more preferably 10-15 min, and further preferably 10 min; the current density of the second electrodeposition is preferably 10-15A/dm²More preferably 12 to 15A/dm²More preferably 15A/dm²The time is preferably 3 to 5min, more preferably 4 to 5min, and still more preferably 5 min. The invention preferably adopts a two-step electrodeposition method for deposition, and can improve the compounding amount of two types of nano-particles in the coating, thereby improving the hydrophobicity of the coating.

After the electrodeposition is finished, the coating is preferably subjected to ultrasonic cleaning and drying in sequence; in the invention, the solvent for ultrasonic cleaning is preferably ethanol, and the time for ultrasonic cleaning is preferably 1-3 min; the drying is preferably at room temperature; and after drying, obtaining the Ni-PTFE-SiC super-hydrophobic anticorrosive coating.

The invention also provides the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating prepared by the preparation method in the scheme, which has a micro-nano dual-scale structure and comprises a nickel metal layer, and polytetrafluoroethylene nanoparticles and SiC nanoparticles embedded in the nickel metal layer, wherein nickel crystals in the nickel metal layer are adsorbed on the polytetrafluoroethylene nanoparticles and the SiC nanoparticles; in the invention, the micro-nano dual-scale structure is a relative scale, wherein the PTFE nano particles and the SiC nano particles have larger sizes, the nickel crystals have smaller sizes, and the nickel crystals are grafted on the two nano particles with larger sizes, and the specific schematic diagram is shown in figures 1-2. According to the invention, PTFE and SiC nano particles are directly embedded into a matrix by an electrodeposition method, the obtained coating can achieve good hydrophobicity without surface modification, and the stability of the coating is better than that of the traditional super-hydrophobic coating. The Ni-PTFE-SiC super-hydrophobic anticorrosive coating provided by the invention has super-hydrophobicity, good anticorrosive effect on a metal matrix, and excellent mechanical stability and durability.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.

Example 1

Molecular dynamics are adopted to simulate wetting behaviors of water drops on the surfaces of three substances, namely Ni, PTFE and SiC, so as to analyze whether two types of nano particles embedded in nickel base are beneficial to improving the hydrophobicity of the coating, and specific results are shown in FIG. 3, wherein FIG. 3 is a wetting process of the water drops on the surfaces of different substances, wherein (a1) - (a5) are wetting processes of the water drops on the surface of Ni, (b1) - (b5) are wetting processes of the water drops on the surface of SiC, and (c1) - (c5) are wetting processes of the water drops on the surface of PTFE.

The results in fig. 3 show that: water molecules on the surface of the Ni rapidly spread downwards, and finally a layer of water film is formed on the surface of the substrate, so that the smooth nickel substrate has strong hydrophilicity; when the water drops are positioned on the surface of the SiC, the spreading speed of water molecules is relatively slow, and finally a contact angle smaller than 90 degrees is formed on the surface of the matrix, which shows that the hydrophobicity of the SiC is slightly stronger than that of the metal Ni; when the water drops are positioned on the surface of the PTFE, water molecules move downwards only under the action of gravity and basically cannot spread, the water molecules are prevented from moving on the surface of the matrix by the insertion of the hydrophobic long chains of the PTFE into the water drops, so that the final contact angle is far larger than 90 degrees, and the PTFE has extremely strong hydrophobicity. Therefore, the hydrophobicity of the three substances is from strong to weak PTFE > SiC > Ni, namely, the introduction of two nano particles of PTFE and SiC in the nickel base is beneficial to the improvement of the hydrophobicity of the coating.

Example 2

In the electrodeposition process, in order to improve the dispersibility of the nanoparticles and avoid the agglomeration of the nanoparticles, a surfactant is generally added in a sufficient concentration to improve the dispersibility, and compared with the PTFE nanoparticles, the SiC nanoparticles have a high density and have a very adverse effect on the codeposition once the agglomeration occurs. However, different surfactants are selected in different preparation processes, and in order to determine which surfactant has better dispersion effect on the electrodeposition system of the invention, molecular dynamics is adopted to simulate the dispersion effect of different types of surfactants (cetyl trimethyl ammonium bromide, sodium dodecyl sulfate, and perfluorooctyl quaternary ammonium iodide) on SiC nanoparticles, and the result is shown in FIG. 4, wherein FIG. 4 shows the dispersion situation of different surfactants on SiC nanoparticles, wherein (a) is Sodium Dodecyl Sulfate (SDS), (b) is Cetyl Trimethyl Ammonium Bromide (CTAB), and (c) is perfluorooctyl quaternary ammonium iodide (FC-134).

As can be seen from fig. 4: CTAB has the best dispersion effect in the aqueous solution, active agent molecules are tightly adsorbed around the nano particles, and the four nano particles are finally stably dispersed in the aqueous solution through the steric hindrance effect and the electrostatic repulsion effect; sodium Dodecyl Sulfate (SDS) has the second dispersing effect, and only half of the nanoparticles are dispersed; the dispersion effect of the perfluorooctyl quaternary ammonium iodide (FC-134) is the worst, only one nanoparticle and other nanoparticles are mutually dispersed, the other nanoparticles are completely agglomerated together, active agent molecules cannot be adsorbed around the nanoparticles, but a large amount of active agent molecules are agglomerated together, and the utilization rate of the active agent is low. Therefore, CTAB is selected as the dispersant in the electrodeposition process.

Example 3

Selecting 20# carbon steel as a metal substrate, wherein the size of the substrate is 50mm multiplied by 25mm multiplied by 2mm, washing with deionized water, removing oil with acetone, dehydrating with absolute ethyl alcohol, and drying with an air cooler for later use.

S1: firstly, pretreating a metal matrix, comprising the following steps:

(1) sequentially using 180#, 400#, 600#, 800# and 1200# sandpaper to polish the metal substrate, cleaning metal surface abrasive dust with deionized water, then respectively ultrasonically cleaning the substrate with acetone and absolute ethyl alcohol solution for 3-5 min, and drying the substrate with an air cooler for later use;

(2) preparing an alkaline solution, wherein the alkaline solution consists of sodium hydroxide, sodium carbonate, sodium silicate and water, the concentration of the sodium hydroxide is 12g/L, the concentration of the sodium carbonate is 60g/L, and the concentration of the sodium silicate is 30g/L, and then carrying out alkaline washing on the metal substrate for 10min at a constant temperature of 75 ℃;

(3) the metal matrix was activated with 10 wt% dilute hydrochloric acid for 1 min.

S2: preparing Ni-PTFE-SiC mixed solution, which comprises the following steps:

(1) weighing PTFE nanoparticles, SiC nanoparticles and 1g of CTAB surfactant according to the concentrations shown in Table 1, adding the weighed PTFE nanoparticles, SiC nanoparticles and CTAB surfactant into deionized water, fully stirring, then dispersing for 30min by using ultrasonic waves, and then performing magnetic stirring for 30min to form a nanoparticle dispersion liquid (marked as liquid A);

(2) weighing 250g of NiSO₄·6H₂O、40g NiCl₂·6H₂O、40g H₃BO₃、50g NH₄And adding Cl into deionized water, fully dissolving to obtain solution B, fully mixing the solution A and the solution B, and fixing the volume of the mixed solution to 1L by using the deionized water to obtain the Ni-PTFE-SiC mixed solution.

S3: the preparation method of the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating by electrodeposition comprises the following steps

(1) Taking the pretreated steel plate in S1 as a cathode, taking a pure nickel plate with the purity of 99.96% as an anode, and forming a double-electrode system, wherein the size of the anode is 60mm multiplied by 40mm multiplied by 2 mm; ensuring that the two electrodes are opposite to each other, the distance is 6cm, and keeping the pH value of the plating solution at 4;

(2) carrying out one-step electrodeposition or two-step electrodeposition according to the parameters shown in the table 1 to obtain the Ni-PTFE-SiC composite coating; the whole electrodeposition process is carried out in a thermostatic water bath at 50 ℃ with continuous assistance of magnetic stirring at 1300 r/min.

The Ni-PTFE-SiC composite coating was ultrasonically cleaned with an ethanol solution for 1min, and after drying at room temperature for two weeks, the wettability of the coating was tested, and the results are shown in table 1.

TABLE 1 contact and roll angles of coatings under different deposition processes

As can be seen from the data in Table 1, when the PTFE and SiC nanoparticles were each 10g/L, at 7A dm^-2The current density of the coating is only subjected to one-time electrodeposition for 10min, the static contact angle of the coating is only 110 degrees, and the rolling angle is 23 degrees; under the same conditions, the material is electrodeposited at 15 A.dm^-2The static contact angle of the coating is increased to 119 degrees, the rolling angle is reduced to 19 degrees, and the two-step electrodeposition is favorable for improving the hydrophobicity of the coating; when the concentration of PTFE is increased to 14g/L and the concentration of SiC is 6g/L, after two-step electrodeposition, the coating reaches a super-hydrophobic state, the static contact angle reaches 155 degrees, and the rolling angle approaches 0 degree. The above results show that the manner of electrodeposition and the concentrations of PTFE and SiC in the bath have an effect on the hydrophobicity of the coating, and that the coating obtained has the best hydrophobicity when the concentrations of PTFE and SiC in the bath are within the range of the present invention and the two-step electrodeposition method is used for deposition.

FIG. 5 is a contact angle measurement result of the Ni-PTFE-SiC superhydrophobic corrosion protection coating prepared according to the process conditions in serial number 3.

SEM images of Ni-PTFE-SiC super-hydrophobic anticorrosive coatings prepared according to the process conditions in sequence No. 3 at different magnifications are shown in FIG. 6, wherein the magnification of (a) is 10000 and the magnification of (b) is 40000. According to the graph 6, the coating is composed of nickel-based metal and PTFE and SiC nano particles embedded in the nickel base, nickel crystals are adsorbed on the particles to form a micro-nano double-scale structure, a large number of micro pores are formed between the micro-nano double-scale structure, the micro pores can intercept air to form an air cushion, water is prevented from permeating, and the coating achieves good hydrophobicity.

An EDS diagram of the Ni-PTFE-SiC superhydrophobic anticorrosive coating prepared according to the process conditions in serial No. 3 is shown in FIG. 7. As can be seen from fig. 7, the nickel element peaks the highest, indicating that metallic nickel is the major component of the coating; at the same time, F element and Si element are detected, which indicates that the two kinds of nanoparticles are successfully embedded into the coating.

In addition, the total mass percentage of F, Si elements in the lower coating obtained under the process conditions of

numbers

1 and 2 in table 1 is also tested, and the result shows that the total content of F and Si in the coating obtained by number 1 is 3.8%, and the total content of F and Si in the coating obtained by number 2 is 6.06%, which indicates that the compounding amount of two types of nanoparticles in the coating can be increased by adopting a two-step deposition method.

Example 4

And carrying out corrosion resistance test on the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating through electrochemical test.

The preparation method of the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating is the same as that in the embodiment 3, and the electrodeposition adopts the process conditions in the sequence number 3 in the table 1.

The bare carbon steel substrate and the carbon steel substrate plated with a common Ni coating are used for comparison, wherein the thickness of the Ni coating is consistent with that of the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating.

The method of corrosion resistance testing is as follows: a standard three-electrode system is adopted, a bare carbon steel substrate, a carbon steel substrate plated with a common Ni coating and a carbon steel substrate plated with a Ni-PTFE-SiC super-hydrophobic anti-corrosion coating are respectively used as working electrodes, a saturated calomel electrode and a platinum electrode are used as a reference electrode and an auxiliary electrode, and a corrosion medium is NaCl aqueous solution with the mass fraction of 3.5%, so that a polarization curve test is carried out.

The obtained polarization curve test results are shown in fig. 8, the corrosion potential and the corrosion current density of each sample are obtained by fitting the polarization curve, the corrosion prevention efficiency η of the coating is calculated according to the formula (1), and the obtained data are shown in table 2.

In the formula (1), i_corr,subAnd i_corr,coatedCorrosion current densities of bare substrate and coated substrate, respectively.

TABLE 2 polarization curve fitting data

According to the data in the table 2, it can be found that compared with the bare carbon steel substrate, the corrosion potential of the sample plated with the common nickel coating is obviously shifted forward, and the corrosion current density is slightly reduced, which indicates that the corrosion resistance of the substrate can be enhanced by the common Ni coating, but the calculated corrosion resistance efficiency is only about 43.0%; the matrix with the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating has the minimum corrosion potential, the corrosion current density is only 1/20 of a bare matrix, the corrosion efficiency is as high as 95.0% only about 1/11 of a Ni coating, and the super-hydrophobic coating plays a good role in protecting the matrix.

Example 5

It is an object of the present invention to improve the mechanical stability (abrasion resistance) of the superhydrophobic coating, and this example tests the mechanical stability of the Ni-PTFE-SiC superhydrophobic coating through a sanding experiment and compares it with the mechanical stability of the conventional surface-modified superhydrophobic coating.

The traditional surface modification type super-hydrophobic coating is prepared by soaking a carbon steel substrate plated with a common Ni coating in melted myristic acid for 2 hours and then drying.

The test procedure was as follows: the abrasion resistance of the coating was characterized by placing the coating surface down on 400# sandpaper, placing a 100g weight over the sample to apply a certain pressure to the coating, pulling the sample across the sandpaper at a constant speed of 1.6cm/s, and measuring the change in contact angle of the coating surface at different abrasion distances, the test procedure being schematically illustrated in fig. 9.

The results of the abrasion resistance test are shown in fig. 10, where (a) in fig. 10 is the results of the abrasion resistance test of the surface-modified superhydrophobic coating, and (b) is the results of the abrasion resistance test of the Ni-PTFE-SiC superhydrophobic anticorrosive coating. As can be seen from fig. 10 (a), the static contact angle of the coating in the initial state of the surface-modified super-hydrophobic coating is as high as 156 °, and the rolling angle is 0 °; when the abrasion distance is 120cm, the contact angle of the coating is reduced to 150 degrees, the rolling angle is increased to 4 degrees, and the coating still can maintain super-hydrophobicity; when the abrasion distance reaches 160cm, the static contact angle is sharply reduced to below 140 degrees, the rolling angle is also increased to above 10 degrees, and the hydrophobicity of the coating begins to sharply reduce; then, the hydrophobicity of the coating is continuously reduced along with the increase of the abrasion distance, when the abrasion distance reaches 400cm, the contact angle is reduced to be below 120 degrees, the rolling angle is increased to be nearly 20 degrees, and the hydrophobicity is greatly reduced.

According to (b) in fig. 10, it can be seen that the static contact angle of the Ni-PTFE-SiC superhydrophobic anticorrosive coating in the initial state is more than 155 °, and the rolling angle is 0 °; the static contact angle and the rolling angle of the coating hardly change after 40cm of abrasion; when the abrasion distance reaches 200cm, the static contact angle is still above 150 degrees, the rolling angle is below 5 degrees, and the coating is still in a super-hydrophobic state; after the abrasion distance exceeds 200cm, the static contact angle of the coating continues to decrease, but after the abrasion distance exceeds 280cm, the hydrophobicity of the coating decreases very slowly until the abrasion distance reaches 360cm, the static contact angle of the coating is still kept above 142 degrees, and the rolling angle is below 15 degrees; while continuing to increase the wear distance, the hydrophobicity of the coating does not change much due to the continuous exposure of the two nanoparticles embedded in the coating.

Therefore, compared with the traditional modified super-hydrophobic coating, the Ni-PTFE-SiC super-hydrophobic anticorrosion coating has better mechanical stability.

Example 6

Durability is also an important embodiment of the stability of the super-hydrophobic coating, in this embodiment, the durability of the traditional surface modification type super-hydrophobic coating and the durability of the Ni-PTFE-SiC super-hydrophobic anticorrosion coating are tested through a soaking experiment, and the preparation methods of the traditional surface modification type super-hydrophobic coating and the Ni-PTFE-SiC super-hydrophobic anticorrosion coating are the same as those in embodiment 5.

The corrosion medium used in the soaking experiment is NaCl aqueous solution with the mass fraction of 3.5%, and the change of the corrosion morphology of the coating in the whole period is observed.

FIG. 11 is an optical photo of the corrosion morphology of a conventional modified super-hydrophobic coating and a Ni-PTFE-SiC super-hydrophobic anticorrosion coating soaked in a corrosion medium for 840h, wherein (a1) - (a5) are conventional modified super-hydrophobic coatings, and (b1) - (b5) are Ni-PTFE-SiC super-hydrophobic anticorrosion coatings. As can be seen from fig. 11, after soaking for 168h, the surface topography of the two superhydrophobic coatings hardly changed; after soaking for 336h, the Ni-PTFE-SiC super-hydrophobic anticorrosive coating is slightly corroded only in a weak area at the boundary of epoxy resin and a test piece (when in deposition, the Ni-PTFE-SiC super-hydrophobic anticorrosive coating is prepared on one surface of a matrix, and the other five surfaces are packaged by epoxy resin), and a layer of modifier on the surface of the modified super-hydrophobic coating obviously falls off in a local area; when the soaking time is continuously increased, the corrosion condition of the Ni-PTFE-SiC super-hydrophobic anti-corrosion coating is basically not developed, and the falling phenomenon of a layer of modifier on the surface of the modified super-hydrophobic coating is gradually serious; after soaking for 840 hours, the modifier of the modified super-hydrophobic coating drops from the point shape and is connected into pieces, large-area dropping occurs, the dropping part develops into a weak area of corrosion, most areas of the Ni-PTFE-SiC composite super-hydrophobic coating are not obviously corroded, and better durability is shown.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a Ni-PTFE-SiC super-hydrophobic anticorrosive coating comprises the following steps:

mixing polytetrafluoroethylene nanoparticles, SiC nanoparticles and nickel-based plating solution to obtain Ni-PTFE-SiC mixed solution; the concentration of polytetrafluoroethylene nanoparticles in the Ni-PTFE-SiC mixed solution is 14-18 g/L, and the concentration of SiC nanoparticles is 2-6 g/L; the average particle size of the polytetrafluoroethylene nanoparticles is 0.7-0.9 mu m, and the average particle size of the SiC nanoparticles is 0.5-0.7 mu m;

performing electrodeposition by taking a metal matrix as a cathode, a nickel plate as an anode and the Ni-PTFE-SiC mixed solution as plating solution to obtain a Ni-PTFE-SiC super-hydrophobic anticorrosive coating on the surface of the metal matrix; the electrodeposition includes: sequentially carrying out first electrodeposition and second electrodeposition; the current density of the first electrodeposition is 7A/dm²The time is 10min, and the current density of the second electrodeposition is 10-15A/dm²The time is 3-5 min.

2. The method according to claim 1, wherein the solute of the nickel-based plating solution comprises nickel sulfate, nickel chloride, boric acid and ammonium chloride, and the solvent is water; the concentration of nickel sulfate in the Ni-PTFE-SiC mixed solution is 250-300 g/L, the concentration of nickel chloride is 40-50 g/L, the concentration of boric acid is 35-45 g/L, and the concentration of ammonium chloride is 40-50 g/L.

3. The preparation method according to claim 1 or 2, characterized in that the Ni-PTFE-SiC mixed solution further comprises a dispersant, and the dispersant is cetyltrimethylammonium bromide; the dosage of the dispersing agent is 3-5% of the total mass of the polytetrafluoroethylene nano-particles and the SiC nano-particles.

4. The preparation method according to claim 1, wherein in the electrodeposition process, the temperature of the plating solution is 50 to 60 ℃, the pH value is 3.5 to 4.5, the distance between the cathode and the anode is 5 to 6cm, and the area of the anode is larger than that of the cathode.

5. The preparation method according to claim 1, wherein the electrodeposition is carried out under stirring conditions, and the rotation speed of the stirring is 1200 to 1300 r/min.

6. The method of claim 1, further comprising, prior to the electrodepositing, pre-treating the metal substrate; the pretreatment comprises polishing, cleaning, alkali washing and acid washing which are sequentially carried out.

7. The Ni-PTFE-SiC super-hydrophobic anti-corrosion coating prepared by the preparation method of any one of claims 1 to 6 has a micro-nano dual-scale structure and comprises a nickel metal layer and polytetrafluoroethylene nanoparticles and SiC nanoparticles embedded in the nickel metal layer, wherein nickel crystals in the nickel metal layer are adsorbed on the polytetrafluoroethylene nanoparticles and the SiC nanoparticles.