CN116145206A - Intelligent metal frame-conductive polymer anti-corrosion coating, preparation method and application - Google Patents
Intelligent metal frame-conductive polymer anti-corrosion coating, preparation method and application Download PDFInfo
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Abstract
The invention discloses an intelligent metal frame-conductive polymer anti-corrosion coating, a preparation method and application thereof, wherein the preparation method comprises the following steps: preparing metal organic frameworks ZIFs by adopting a normal temperature synthesis method; preparing a mixed electrolyte for preparing a composite coating by electrodeposition; and (3) adopting a potentiostatic method to use a three-electrode system, and taking the mixed solution prepared in the step (2) as electrolyte to electrodeposit a composite coating on the surface of the working electrode to obtain the electrochemically deposited metal organic framework-conductive polymer anticorrosive coating. The coating raw materials in the invention are easy to obtain and low in toxicity, can be directly and rapidly formed into a film on the surface of a metal substrate in a large area, are not limited by factors such as the shape and the surface morphology of the substrate, effectively avoid the defects of poor adhesive force, unstable service performance and the like of the traditional conductive polymer coating, and have good application prospects in the aspects of stainless steel materials serving in acidic soil, seawater splash areas and the like and metal electrode plates of fuel cells.
Description
Technical Field
The invention relates to the technical field of metal corrosion protection, in particular to an intelligent metal frame-conductive polymer anti-corrosion coating, a preparation method and application thereof.
Background
Corrosion is a natural phenomenon in which a metal chemically or electrochemically reacts with a medium in a certain environment to cause deterioration or performance degradation of the metal. Metal corrosion can cause irreversible damage to ships, bridges, pipelines, public buildings, household equipment and the like, seriously threatens public safety and causes huge economic loss and environmental pollution. Stainless steel is used as a common metal material in industry and has very wide application in the fields of construction, ships, petrochemical industry, fuel cell polar plates and the like. However, in the presence of corrosive media such as chloride ions and sulfur-containing compounds, the corrosion process of stainless steel materials in long-term service is unavoidable, and about 20% of stainless steel is statistically corroded each year. In a practical environment, the corrosion of stainless steel cannot be completely stopped, but the corrosion rate of the stainless steel can be reduced by various means to control the corrosion process, so that the service life of the stainless steel material is prolonged, and the application cost of the stainless steel material is reduced. There are many methods of preventing corrosion of stainless steel, and the corrosion protection method of the coating is one of the most main methods of improving corrosion resistance of stainless steel.
The traditional anti-corrosion coating is mainly a resin organic coating, and the anti-corrosion mechanism is to isolate corrosive substances by forming a physical barrier on the surface of a metal substrate. However, due to the self-defects of the film-forming materials, micropores generally exist in the constructed coating structure, and long-acting corrosion protection effect cannot be exerted. In recent years, the construction of intelligent anti-corrosion coating is widely focused by people, and the bottleneck problem that the single protection mechanism of the coating cannot meet the long-acting and stable protection of stainless steel is hopefully solved. The conductive polymer (Conductive polymers, CPs) is a special polymer material, the doped CPs can be converted from an insulating state to a conductive state, and the CPs can be used as a coating material to isolate a corrosion environment, form an oxide film at a coating/metal interface, maintain the corrosion potential of the protected metal in a passivation area and further strengthen the corrosion protection effect (anode protection function) of the coating. However, CPs coatings often have defects such as micropores and cracks, and the dedoping of anions can lead to gradual reduction of CPs to an insulating state during long-term service, weakening the anodic protection effect of the coating and gradually failing the coating. Therefore, the stability of CPs coatings in long-term service greatly limits their practical application in the field of corrosion protection.
Metal organic framework compounds (Metal organic frameworks, MOFs) are organic-inorganic hybrid materials with intramolecular pores formed by self-assembly of organic ligands and metal ions or clusters through coordination bonds, and are widely used in the fields of biosensing, drug delivery and catalysis due to their highly adjustable porosity and large pore volume and abundant sites of action. Currently, MOFs materials are reported as nano microcapsule seal corrosion inhibitors for increasing the corrosion resistance of coatings.
In the prior art, the invention patent with the application publication number of CN110387548A discloses a metal organic framework encapsulated corrosion inhibitor compound, a preparation method and application thereof, wherein the corrosion inhibitor is encapsulated in MOFs nano-shells to construct a novel corrosion inhibition system which is suitable for the corrosion environment of a seawater splash zone, and the corrosion inhibitor is rapidly released and encapsulated to act on the corrosion zone by utilizing the characteristic that the MOFs material ZIF-67 is sensitive to the acidic environment. However, the compound acts by being added to an acidic corrosive environment in the form of a corrosion inhibitor, and limits the application range. The invention patent with application publication number of CN112521837A discloses a filler of MOF loaded corrosion inhibitor, self-repairing anticorrosive paint and a preparation method thereof, wherein the corrosion inhibitor is packaged in hmt-MOF and used as filler of epoxy resin to construct a protective coating, so that the self-repairing performance of the coating is endowed, but the dispersibility problem of MOFs of the packaged corrosion inhibitor as filler in a coating substrate also limits the corrosion inhibition performance.
Disclosure of Invention
Aiming at the problems in the background art, the invention provides an intelligent metal frame-conductive polymer anti-corrosion coating and a preparation method and application thereof, so as to overcome the defects and shortages of the existing intelligent anti-corrosion technology and the defects that the existing anti-corrosion coating cannot meet long-acting and stable corrosion protection. The intelligent metal organic frame-conductive polymer anti-corrosion coating provided by the invention is composed of metal organic frame materials ZIFs with corrosion inhibition function and CPs materials such as Polyaniline (PANI) and polypyrrole (PPY), and the targeted intelligent corrosion protection of metal materials such as stainless steel and the like in an acidic service environment is realized by playing the synergistic effect of CPs and MOFs.
The technical aim of the invention is realized by the following technical scheme:
a method for preparing a metal frame-conductive polymer anti-corrosion coating, comprising the following steps:
preparing metal organic frameworks ZIFs by adopting a normal-temperature synthesis method, wherein the ZIFs at least comprise ZIF-67 and/or ZIF-8;
step (2), preparing a mixed electrolyte for preparing a composite coating by electrodeposition: dispersing a conductive polymer monomer and a sodium dodecyl sulfate anionic surfactant in deionized water, then adding ZIFs prepared in the step (1), and sequentially and ultrasonically stirring uniformly to obtain a mixed solution;
and (3) adopting a potentiostatic method to use a three-electrode system, and taking the mixed solution prepared in the step (2) as electrolyte to electrodeposit a composite coating on the surface of the working electrode to obtain the electrochemical deposition metal organic framework-conductive polymer anti-corrosion coating.
Preferably, in step (1), the ZIFs material is provided with a central metal ion from a metal salt and an imidazole-based organic compound provides an organic ligand.
In any of the above embodiments, preferably, the metal salt is Zn (NO 3 ) 2 ·6H 2 O and/or Co (NO) 3 ) 2 ·6H 2 The O, imidazole organic matter is 2-methylimidazole.
In any of the above schemes, preferably, in the step (1), the preparation method of the ZIFs material comprises the following steps: zn (NO) 3 ) 2 ·6H 2 O、Co(NO 3 ) 2 ·6H 2 Dissolving at least one or two mixed metal salts in O in water or methanol to obtain component A, dissolving 2-methylimidazole organic ligand in water or methanol to obtain component B, and dissolving component A and component B sufficientlyAnd then quickly pouring the component B into the component A, stirring the components A to mix the components A and the component B, standing the mixture at room temperature for reaction, centrifugally separating the mixture to obtain a precipitate, repeatedly washing the precipitate with methanol, and drying the precipitate to obtain the metal organic framework crystal materials ZIF-67 and ZIF-8.
In any of the above schemes, it is preferable that the mixing and stirring time of the component A and the component B is 30min, the standing reaction time at room temperature is 12-48 h after mixing, the centrifugal separation time is 10-30 min after reaction, and the precipitate is dried in vacuum after washing 3-5 times by methanol, the drying temperature is 50-80 ℃ and the drying time is 12-48 h.
In the step, after the component A and the component B are mixed, standing at room temperature for reacting for any value within a range of 12-48 h, such as 12h,15h,20h,25h,30h,35h,40h and 48h; the centrifugal separation time after the reaction is any value within the range of 10-30 min, such as 10min,20min and 30min; washing with methanol for 3-5 times, and vacuum drying the precipitate at 50-80deg.C, such as 50deg.C, 60deg.C, 70deg.C, 80deg.C; the drying time is any value in the range of 12 to 48 hours, for example, 12 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 48 hours.
In any of the above schemes, it is preferred that in step (1), the molar ratio of center ion to ligand during the preparation of ZIF-67 and ZIF-8 is 1:58 and 1:70, respectively.
In any of the above schemes, preferably, in the preparation process of ZIF-67 and ZIF-8 in the step (1), the centrifugal separation speed of the product is 8000rmp, the separation time is 10-20 min, and the centrifugal cleaning time of methanol is 10-20 min each time. The centrifugal separation time of the product is any value within the range of 10-20 min, such as 10min,15min and 20min; the time of the centrifugal cleaning of the methanol is 10-20 min each time, and any value in the range can be 10min,15min and 20min.
In any of the above embodiments, preferably, in step (1), the polymer monomer (CPs monomer) includes at least one of Polyaniline (PANI) and polypyrrole (PPY).
In any of the above-mentioned schemes, it is preferable that in the step (2), the mixed solution includes pyrrole or aniline monomer with a concentration of 0.1-0.5 mol/L, sodium dodecyl sulfate with a concentration of 0.05-0.3 mol/L and ZIFs with a concentration of 0.5-2 mg/mL.
The concentration of the pyrrole or aniline monomer is any value in the range of 0.1 to 0.5mol/L, such as 0.1mol/L,0.2mol/L,0.3mol/L,0.4mol/L and 0.5mol/L; the concentration of sodium dodecyl sulfate is any value in the range of 0.05 to 0.3mol/L, such as 0.05mol/L,0.1mol/L,0.15mol/L,0.2mol/L,0.25mol/L,0.3mol/L. ZIFs concentrations are anywhere in the range of 0.5 to 2mg/mL, such as 0.5mg/mL,1mg/mL,1.5mg/mL,2mg/mL.
In any of the above schemes, preferably, in the step (2), the mixed solution is subjected to ultrasonic treatment for 10-20 min and then is subjected to continuous magnetic stirring for 10-30 min to obtain the uniform mixed electrolyte.
In the step, the ultrasonic time of the mixed solution is any value within the range of 10-20 min, such as 10min,15min and 20min; magnetic stirring is carried out for any value in the range of 10-30 min, such as 10min,15min,20min,25min and 30min.
In any of the above schemes, preferably, in the step (3), the reference electrode and the counter electrode in the three-electrode deposition system are respectively an Ag/AgCl electrode and a platinum sheet electrode, the working electrode is a stainless steel substrate needing corrosion protection, the electrochemical deposition process adopts a potentiostatic method for deposition, and the electrodeposition time is 10-30 min.
In any of the above schemes, preferably, in the method for performing electrodeposition by the potentiostatic method, for aniline and pyrrole monomers, the deposition voltage is-1.3V and 1.4V respectively, the electrodeposition time is 10-30 min, the drying temperature of the prepared coating is 30-50 ℃, and the drying time is 3-5 h. In the step, the electrodeposition time is any value within the range of 10-30 min, such as 10min,15min,20min,25min and 30min; the drying temperature of the prepared coating is any value in the range of 30-50 ℃, such as 30 ℃,35 ℃,40 ℃,45 ℃,50 ℃ and the drying time is any value in the range of 3-5 h, such as 3h,4h and 5h.
In any of the above embodiments, it is preferable that the working electrode is a stainless steel substrate requiring corrosion-resistant treatment, and the surface of the stainless steel substrate is a surface of any shape in the electrodeposition process.
In any of the above schemes, it is preferable that the non-coating deposition surface of the stainless steel is encapsulated with epoxy resin before the coating is prepared, and the deposition surface is polished, and then the non-coating deposition surface is washed by deionized water, acetone and ethanol in sequence.
In any of the above schemes, preferably, in the step (3), the metal organic framework-conductive polymer anti-corrosion coating after electrochemical deposition is washed by deionized water and dried, the drying temperature is 30-50 ℃, and the drying time is 3-5 h.
The invention also provides the metal organic frame-conductive polymer anti-corrosion coating prepared by the method.
The invention also provides a corrosion protection method for stainless steel in an acidic environment by using the metal organic frame-conductive polymer anti-corrosion coating prepared by the method.
In any of the above embodiments, the acidic environment is preferably 0.1 to 0.5mol/L sulfuric acid or hydrochloric acid solution.
The corrosion protection effect in an acidic corrosion environment was characterized by electrochemical testing. The electrochemical test is performed by a three-electrode system, wherein the sample to be tested is a working electrode, a platinum sheet electrode is a counter electrode, and an Ag/AgCl electrode is a reference electrode.
Preferably in any of the above schemes, specific electrochemical tests include potentiodynamic polarization tests, open circuit potential tests, and electrochemical impedance spectroscopy tests.
Advantageous effects
(1) As a representative class of MOFs, the zeolitic imidazolate frameworks (Zeolitic imidazolate frameworks, ZIFs) are a class of tetrahedral framework materials with imidazole esters as organic ligands. As an anti-corrosion material, ZIFs have stability and acid sensitivity characteristics which are not possessed by other MOFs, and imidazole ligands in the structure endow the ZIFs with natural corrosion inhibition functions. Therefore, the advantages of the ZIFs and the CPs can be fully exerted by in-situ composite construction of the anti-corrosion coating material, the self-repairing property of the coating is endowed by the designability of the ZIFs structure and function, the CPs are attached to the surface of the ZIFs and in the pore canal to form a laminated conductive network, the anodic protection function and the physical barrier function are fully exerted, the anti-corrosion performance of the coating is enhanced, and finally the intelligent protection of metal is realized.
(2) The preparation method of the metal organic frame-conductive polymer anti-corrosion coating provided by the invention has the advantages of simple process, safety, environmental protection and low energy consumption, is not limited by the shape of a stainless steel base material, and can be used for rapidly depositing a functional metal organic frame-conductive polymer anti-corrosion coating on the surface of the stainless steel. The method strictly controls the concentrations of CPs monomers, sodium dodecyl sulfate dopants and ZIFs and electrodeposition conditions, effectively inserts the dopants into the backbone of CPs and realizes the combination of the ZIFs and CPs.
(3) The invention constructs an intelligent composite anti-corrosion coating system and solves the problem of poor anti-corrosion stability in the existing passive anti-corrosion coating technology. The invention endows the coating with self-repairing function by using a special metal organic framework compound ZIFs, and the anode protection performance and physical barrier effect of the coating are enhanced by compounding conductive polymers. ZIFs are formed by assembling metal center ions such as Zn, co and the like and 2-methylimidazole organic ligands with corrosion inhibition function, and the ZIFs are rich in active sites, are favorable for being combined with conductive polymers and have good compatibility. The constructed composite coating can interact with a protected metal substrate to form metal-N/O coordination bonds, hydrogen bonds and the like, which is beneficial to improving the adhesive force of the coating and preventing corrosive substances from penetrating into the interface of the coating/the substrate.
(4) The main action principle of the application is as follows: ZIFs materials composed of organic ligands with corrosion inhibition properties exhibit water stability and acid dissociability and are sensitive to pH changes. In an acidic corrosive medium, a physical barrier formed by a composite coating formed by compounding CPs and ZIFs on the surface of a metal material can effectively prevent the inward penetration of corrosive substances. Under the condition that no corrosion occurs, CPs can fully exert anode protection performance, effectively reduce corrosion potential of a base metal material to enable the base metal material to be in a passivation state, and ZIFs keep a stable state, so that corrosion inhibitor active groups in the base metal material are prevented from being degraded by environment. When the corrosion substances continuously attack to cause local damage of the coating, CPs play an anodic protection role, and meanwhile, the pH change in a tiny range caused by corrosion reaction stimulates coordination bonds in ZIFs to promote dissociation of the ZIFs, and the ligand corrosion inhibitor is released to act on the damaged area of the coating, so that the corrosion inhibitor delivery of corrosion induction site targeting is realized, and the self-repairing effect of the coating is achieved.
(5) The coating has the advantages of easily available raw materials, low toxicity and easy preparation, can directly, quickly and widely form a film on the surface of a metal substrate, is not limited by factors such as the shape and the surface morphology of the substrate, effectively avoids the defects of poor adhesive force, unstable service performance and the like of the traditional conductive polymer coating, and has good application prospects in the aspects of stainless steel materials and fuel cell metal polar plates serving in acidic soil, seawater splash areas and the like. The intelligent metal organic frame-conductive polymer anti-corrosion coating material prepared by the invention realizes the organic combination of the anti-corrosion advantages of the metal organic frame and the conductive polymer, has stable and reliable anti-corrosion performance through electrochemical experiments, and is suitable for corrosion protection of stainless steel materials in acidic environments such as acidic soil, fuel cell interiors, seawater splash areas and the like. The invention has reasonable technical route, simple and environment-friendly coating preparation process, excellent product performance and wide application prospect.
Drawings
FIG. 1 is a flow chart of the preparation of the intelligent metal organic framework-conductive polymer corrosion resistant coating of the present invention;
FIG. 2 is a morphology of ZIF-67 nanoparticles synthesized in example 1 of the present invention;
FIG. 3 is a graph of the morphology of the coating of example 2 and comparative example 2 of the present invention, wherein a is a graph of the morphology of the ZIF-67-PPY corrosion-resistant coating of example 2 and b is a graph of the surface morphology of the PPY corrosion-resistant coating of comparative example 2;
FIG. 4 is a Nyquist plot of electrochemical impedance spectra as a function of time in service for example 2 and comparative example 2 in an acidic corrosive environment (0.1 mol/L HCl), wherein a is the Nyquist plot of the ZIF-67-PPY corrosion-resistant coating of example 2 and b is the Nyquist plot of the PPY corrosion-resistant coating of comparative example 2;
FIG. 5 is a plot of open circuit potential versus time for sample service for example 2 and comparative example 2 of the present invention, and the potentiodynamic polarization curves for the bare stainless steels of example 2, comparative examples 2 and 430;
FIG. 6 is a surface topography of ZIF-8 nanoparticles synthesized in example 4 of the present invention.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention, and it is apparent that the described embodiments are merely all other embodiments that a person skilled in the art may obtain without making any inventive effort, and are all within the scope of protection of the present invention. Unless otherwise specified, the relevant materials appearing in the subsequent examples were all prepared from the preceding examples.
The invention relates to a preparation method of an intelligent metal organic framework-conductive polymer anti-corrosion coating, which is shown in a figure 1, and comprises the following steps:
(1) Preparing MOFs materials of two imidazole ligands, namely ZIF-67 and ZIF-8, by adopting a normal-temperature synthesis method;
(2) Dispersing CPs monomer aniline or pyrrole, sodium dodecyl sulfate anion dopant and ZIFs in deionized water to prepare a uniform mixed solution;
(3) And electrodepositing a coating in the mixed solution by utilizing a three-electrode system to obtain the metal organic framework-conductive polymer anti-corrosion coating.
The ZIFs prepared by the normal-temperature synthesis method are ZIF-67 and ZIF-8 materials, and specifically comprise the processes of crystal growth, centrifugation, washing, vacuum drying and the like. The ZIF-67 crystal growth is more specifically carried out by the following steps: a certain amount of Co (NO) 3 ) 2 ·6H 2 O is added into 50-100 mL of water or methanol to obtain a component A, a certain amount of 2-methylimidazole is added into 50-100 mL of water or methanol to obtain a component B, after the A and the B are fully stirred and dissolved, the B is rapidly poured into the A for stirring and mixing, wherein the molar ratio of metal ions to imidazole ligand is 1:58, stirring the mixed solution at room temperature for 30min, standing for reaction for 12-48 h to enable crystals to grow, centrifuging at 8000rmp for 10-30 min, centrifuging and cleaning for 3-5 times by using methanol, and vacuum drying the washed lower precipitate at 50-80 ℃ for 12-48 h; the ZIF-8 crystal growth more specifically comprises the following steps: replacement of nitrate providing central metal ions with Zn (NO 3 ) 2 ·6H 2 O, wherein the metal ion and imidazole complexThe molar ratio of the bodies is 1:70, and the rest steps are the same as ZIF-67.
Example 1
An intelligent metal frame-conductive polymer composite conductive anticorrosive coating, in particular a ZIF-67-PANI composite coating, and the preparation method comprises the following steps:
the first step: preparing ZIF-67 by normal temperature synthesis: 2.70g of Co (NO) 3 ) 2 ·6H 2 O is added into 50mL of methanol to obtain a component A, 44.24g of 2-methylimidazole is added into 100mL of methanol to obtain a component B, after the A and the B are fully stirred and dissolved, the B is quickly poured into the A to be stirred and mixed, stirred at room temperature for 30min, and then the mixture is left to stand for reaction for 48h to enable crystals to grow. And centrifuging for 10min under 8000rmp condition, collecting precipitate, centrifuging and cleaning with methanol for 5 times each for 10min, and vacuum drying the washed lower precipitate at 70deg.C for 24 hr to obtain ZIF-67 nanoparticles. In the embodiment, the surface morphology of the ZIF-67 nano particles is shown in the figure 2, and the ZIF-67 nano particles have a rhombic dodecahedron structure and the size is 200-400 nm.
And a second step of: treatment of stainless steel substrate: encapsulation of the non-deposited face of the bulk 430 stainless steel with epoxy leaves 1X 1cm 2 The deposition area and the electrode clamp contact area are sequentially polished by using 240, 800 and 1500-mesh metallographic sand paper, then the deposition area is sequentially cleaned by using deionized water, acetone and ethanol, and finally the deposition area is dried.
And a third step of: the metal organic framework-conductive polymer coating is prepared by a one-pot electrodeposition method. Adding aniline monomer, sodium dodecyl sulfate and ZIF-67 into 100mL of deionized water, performing ultrasonic treatment for 15min, and performing magnetic stirring for 30min to prepare a uniform mixed solution, wherein the concentration of the aniline monomer is 0.25mol/L, the concentration of the sodium dodecyl sulfate is 0.3mol/L, and the concentration of the ZIF-67 is 0.5mg/mL. The treated stainless steel substrate is used as a working electrode, the platinum sheet electrode is a counter electrode, the Ag/AgCl electrode is a reference electrode, a coating is electrodeposited on the surface of the stainless steel by a potentiostatic method, the electrodeposition time is 15 minutes, the deposition voltage is-1.3V, and the obtained coating is marked as ZIF-67-PANI coating.
The coating product obtained in the embodiment has compact structure and uniform appearance, and mainly presents the appearance of the wrinkled PANI. The potentiodynamic polarization test can judge the corrosion behavior of the electrode surface, and represents the corrosion tendency and degree of the material, so that the corrosion resistance of the sample after the coating is applied is reflected. The coating samples obtained in this example had a 310mV increase in self-etching voltage in the corrosive environment simulated by 0.3mol/L sulfuric acid, relative to the 430 stainless steel substrate without the deposited coating, indicating a significant increase in corrosion resistance of 430 stainless steel.
Comparative example 1
The difference from example 1 is that:
adding aniline monomer and sodium dodecyl sulfate into 100mL of deionized water, carrying out ultrasonic treatment for 15min, and magnetically stirring for 30min to prepare a uniform mixed solution, wherein the concentration of the aniline monomer is 0.25mol/L, and the concentration of the sodium dodecyl sulfate is 0.3mol/L;
other conditions were the same as in example 1, and potentiostatic electrodeposition gave PANI coating.
The PANI coating prepared in this comparative example had a loose structure and exhibited more micropores and microcracks.
Example 2
An intelligent metal frame-conductive polymer composite conductive anticorrosive coating, in particular a ZIF-67-PPY composite coating, and the preparation method comprises the following steps:
the first step: preparing ZIF-67 by normal temperature synthesis: 2.70g of Co (NO) 3 ) 2 ·6H 2 O is added into 25mL of water to obtain a component A, 44.24g of 2-methylimidazole is added into 160mL of water to obtain a component B, after the A and the B are fully stirred and dissolved, the B is quickly poured into the A to be stirred and mixed, and the mixture is stirred at room temperature for 30min and then is left to stand for reaction for 24h to enable crystals to grow. And centrifuging for 15min under 8000rmp condition, collecting precipitate, centrifuging and cleaning with methanol for 3 times each for 10min, and vacuum drying the washed lower precipitate at 60deg.C for 24 hr to obtain ZIF-67 nanoparticle. In the embodiment, the appearance of the ZIF-67 product is similar to that of the figure 2, and the product has a rhombic dodecahedron structure with the size of 200-300 nm.
And a second step of: treatment of stainless steel substrate: encapsulation of the non-deposited side of 430 stainless steel sheet with epoxy leaves 1X 1cm 2 The deposition area and the electrode clamp contact area are sequentially polished by using 240, 800 and 1500-mesh metallographic sand paper, then the deposition area is sequentially cleaned by using deionized water, acetone and ethanol, and finally the deposition area is dried.
And a third step of: the metal organic framework-conductive polymer coating is prepared by a one-pot electrodeposition method. Adding pyrrole monomer, sodium dodecyl sulfate and ZIF-67 into 100mL of deionized water, performing ultrasonic treatment for 10min, and magnetically stirring for 20min to prepare a uniform mixed solution, wherein the concentration of the pyrrole monomer is 0.4mol/L, the concentration of the sodium dodecyl sulfate is 0.15mol/L, and the concentration of the ZIF-67 is 1mg/mL. The treated stainless steel substrate is a working electrode, the platinum sheet electrode is a counter electrode, the Ag/AgCl electrode is a reference electrode, and a coating is electrodeposited on the surface of the stainless steel by a potentiostatic method, wherein the electrodeposition time is 10min, the deposition voltage is 1.4V, and the obtained coating is marked as a ZIF-67-PPY coating.
The metal organic framework-conductive polymer coating product obtained in the embodiment has compact structure and uniform morphology, as shown in fig. 3 (a).
The electrochemical impedance spectrum can semi-quantitatively evaluate the physical barrier property of the coating system to corrosive environment and the dynamic process of interface corrosion, thereby reflecting the corrosion resistance of the coating and the dynamic process of coating damage. The Nyquist plot of the electrochemical impedance spectrum of this example in 600 hours of service in a 0.1mol/L HCl simulated corrosive environment is shown in fig. 4 (a), and it can be seen that the impedance of this example always shows an increasing trend in the first 240 hours of service, and after 240 hours of service, although the impedance is slightly reduced, it is still significantly higher than the initial stage of service. The PPY and the ZIF-67 can play a synergistic effect through the implementation of the anodic protection performance and the release of the corrosion inhibitor, so that the intelligent active protection capability of the coating is provided, and the high anti-corrosion effect can be maintained when the coating has tiny defects in long-term service.
Comparative example 2
Preparation of PPY coating
The difference from example 2 is that:
adding pyrrole monomer and sodium dodecyl sulfate into 100mL of deionized water, carrying out ultrasonic treatment for 10min, magnetically stirring for 20min, and preparing a uniform mixed solution, wherein the concentration of the pyrrole monomer is 0.4mol/L, and the concentration of the sodium dodecyl sulfate is 0.15mol/L;
other conditions were the same as in example 2, and a PPY coating was obtained by potentiostatic electrodeposition.
The morphology of the PPY coating prepared in the comparative example is shown in a figure 3 (b), the coating consists of cauliflower-shaped PPY particles, and micropores exist among the particles. The Nyquist plot of the electrochemical impedance spectrum of this example over 600 hours of service in a 0.1mol/L HCl simulated corrosion environment is shown in FIG. 4 (b), which shows that the comparative example has the greatest impedance over 48 hours of service, indicating excellent corrosion resistance of the coating in a severe corrosion environment over 0-48 hours of service. However, after the coating is in service for 48 hours, the impedance shows a linear reduction trend, and as can be seen from the enlarged illustration, the impedance is even lower than the impedance value in the initial stage of service when in service for 600 hours, which indicates that the coating fails, and the coating does not have a stable corrosion protection effect, and the corrosion protection effect is obviously inferior to that of the coating in the embodiment 2.
The change of Open Circuit Potential (OCP) of the coating in long-term service in corrosive environments can evaluate spontaneous reaction, steady-state potential formation and stability of the coating in the environment in a passivation or activation form, so that the corrosion resistance of the coating is reflected. FIG. 5 (a) is a graph showing the change of OCP value with respect to service time of example 2 and comparative example 2, and it can be seen that the coating material of example 2 according to the present invention, i.e., composed of ZIF-67, PPY, and sodium dodecyl sulfate, has a higher OCP value than that of comparative example 2 over the service time of 600 hours, and maintains a substantially stable value over the entire service time, indicating that example 2 has excellent corrosion resistance, and the coating can provide long-lasting, stable, and excellent corrosion protection to stainless steel.
FIG. 5 (b) is a plot of the electrokinetic polarization of example 2, comparative example 2, and uncoated stainless steel bare steel in an acidic corrosion environment simulated by 0.1mol/L HCl, showing that example 2 of the present invention has the highest self-corrosion potential and lowest self-corrosion current density, with a self-corrosion voltage increase of 495mV relative to the stainless steel bare steel. From the above electrochemical test results, it can be seen that the corrosion protection efficiency of example 2 is higher, which is related to the compact structure of the coating (shown in fig. 3 (a)), and benefits from the synergistic effect of CPs, dopants and MOFs, and by exerting the respective advantages, the intelligent active protection capability of the coating is given, and the corrosion resistance of the stainless steel is effectively improved.
Example 3:
an intelligent metal frame-conductive polymer composite conductive anticorrosive coating, in particular a ZIF-8-PANI composite coating, and the preparation method comprises the following steps:
the first step: preparing ZIF-8 by normal temperature synthesis: 1.17g of Zn (NO) 3 ) 2 ·6H 2 O is added into 100mL of water to obtain a component A, 22.70g of 2-methylimidazole is added into 100mL of water to obtain a component B, after the A and the B are fully stirred and dissolved, the B is quickly poured into the A to be stirred and mixed, and the mixture is stirred at room temperature for 30min and then is left to stand for reaction for 36h to enable crystals to grow. And centrifuging for 20min at 8000rmp, collecting precipitate, centrifuging and cleaning for 4 times by using methanol for 10min each time, and vacuum drying the washed lower precipitate at 50 ℃ for 48h to obtain ZIF-8 nano particles. In the embodiment, the ZIF-8 nano particles have a rhombic dodecahedron structure, and the size is 100-150nm.
And a second step of: treatment of stainless steel substrate: encapsulation of the non-deposited face of bulk 304 stainless steel with epoxy leaves 1X 1cm 2 The deposition area and the electrode clamp contact area are sequentially polished by using 240, 800 and 1500-mesh metallographic sand paper, then the deposition area is sequentially cleaned by using deionized water, acetone and ethanol, and finally the deposition area is dried.
And a third step of: the metal organic framework-conductive polymer coating is prepared by a one-pot electrodeposition method. Adding aniline monomer, sodium dodecyl sulfate and ZIF-8 into 100mL of deionized water, carrying out ultrasonic treatment for 20min, and magnetically stirring for 20min to prepare a uniform mixed solution, wherein the concentration of the aniline monomer is 0.5mol/L, the concentration of the sodium dodecyl sulfate is 0.25mol/L, and the concentration of the ZIF-8 is 2mg/mL. The treated stainless steel substrate is a working electrode, the platinum sheet electrode is a counter electrode, the Ag/AgCl electrode is a reference electrode, a coating is electrodeposited on the stainless steel surface by a potentiostatic method, the electrodeposition time is 30 minutes, the deposition voltage is-1.3V, and the obtained coating is marked as ZIF-67-PANI coating.
The morphology of the coating product obtained in this example is similar to that of the coating of example 1 shown in fig. 3 (a), and the coating product has a compact structure, uniform morphology and more complex micro morphology. The self-corrosion voltage in the corrosion environment simulated by 0.5mol/L hydrochloric acid was increased by 298mV relative to the stainless steel substrate without the deposited coating.
Comparative example 3
The difference from example 3 is that:
adding aniline monomer and sodium dodecyl sulfate into 100mL of deionized water, carrying out ultrasonic treatment for 20min, and magnetically stirring for 20min to prepare a uniform mixed solution, wherein the concentration of the aniline monomer is 0.5mol/L, and the concentration of the sodium dodecyl sulfate is 0.25mol/L;
other conditions were the same as in example 3, and potentiostatic electrodeposition gave PANI coating.
The PANI coating prepared in this comparative example exhibited more micropores and microcracks from the loose structure.
Example 4
An intelligent metal frame-conductive polymer composite conductive anticorrosive coating, in particular to a preparation method of a ZIF-8-PPY composite coating, which comprises the following steps:
the first step: preparing ZIF-8 by normal temperature synthesis: 1.17g of Zn (NO) 3 ) 2 ·6H 2 O is added into 20mL of methanol to obtain a component A, 22.70g of 2-methylimidazole is added into 100mL of methanol to obtain a component B, after the A and the B are fully stirred and dissolved, the B is quickly poured into the A to be stirred and mixed, and the mixture is stirred at room temperature for 30min and then is left to stand for reaction for 24h to enable crystals to grow. And centrifuging for 15min under 8000rmp condition, collecting precipitate, centrifuging and cleaning with methanol for 3 times each for 15min, and vacuum drying the washed lower precipitate at 60deg.C for 48 hr to obtain ZIF-8 nanoparticles. In the embodiment, the appearance of the ZIF-8 nano particles is shown in figure 6, and the product is of a rhombic dodecahedron structure with the size of 70-100 nm.
And a second step of: treatment of stainless steel substrate: encapsulation of the non-deposited side of the 304 stainless steel sheet with epoxy leaves 1X 1cm 2 The deposition area and the electrode clamp contact area of the metal-phase sand paper of 240, 800 and 1500 meshes are used in sequencePolishing the deposition area, cleaning the deposition area by using deionized water, acetone and ethanol in sequence, and finally drying.
And a third step of: the metal organic framework-conductive polymer coating is prepared by a one-pot electrodeposition method. Adding pyrrole monomer, sodium dodecyl sulfate and ZIF-8 into 100mL of deionized water, performing ultrasonic treatment for 10min, and performing magnetic stirring for 20min to prepare a uniform mixed solution, wherein the concentration of the pyrrole monomer is 0.2mol/L, the concentration of the sodium dodecyl sulfate is 0.1mol/L (SDS), and the concentration of the ZIF-8 is 1.5mg/mL. The treated stainless steel substrate is a working electrode, the platinum sheet electrode is a counter electrode, the Ag/AgCl electrode is a reference electrode, and a coating is electrodeposited on the surface of the stainless steel by a potentiostatic method, wherein the electrodeposition time is 20 minutes, the deposition voltage is 1.4V, and the obtained coating is marked as a ZIF-8-PPY coating.
The metal organic framework-conductive polymer coating product obtained in the embodiment has compact structure and uniform appearance. The self-corrosion voltage in a corrosion environment simulated by 0.5mol/L sulfuric acid was increased by 463mV relative to the uncoated 304 stainless steel substrate.
Comparative example 4
The difference from example 4 is that:
adding pyrrole monomer and sodium dodecyl sulfate into 100mL of deionized water, carrying out ultrasonic treatment for 10min, magnetically stirring for 20min, and preparing a uniform mixed solution, wherein the concentration of the pyrrole monomer is 0.2mol/L, and the concentration of the sodium dodecyl sulfate is 0.1mol/L;
other conditions were the same as in example 1, and a PPY coating was obtained by potentiostatic electrodeposition.
The appearance of the PPY coating prepared in the comparative example is similar to that of comparative example 2 shown in fig. 3 (b), the coating consists of cauliflower-shaped PPY particles, and micropores exist among the particles.
The embodiment 1-4 shows that the preparation method of the intelligent metal organic frame-conductive polymer anti-corrosion coating material is simple and convenient, the energy consumption is low, a composite coating structure with compact structure and uniform appearance can be obtained by regulating and controlling the proportion of each component, the construction of the coating is not limited by the appearance and shape of a metal substrate, and the obtained coating material not only has good physical barrier effect, but also can fully play the advantages of the conductive polymer and the metal organic frame, and provides anode protection and intelligent self-repairing function of the micro damage part of the coating for the substrate metal. Therefore, in an acidic corrosion environment, the intelligent metal organic framework-conductive polymer anti-corrosion coating can provide stable and long-acting protection for the stainless steel material. The invention has great significance in corrosion protection of stainless steel materials in acidic environments such as acidic soil, the inside of fuel cells, seawater splash areas and the like.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (10)
1. The preparation method of the intelligent metal frame-conductive polymer anti-corrosion coating is characterized by comprising the following steps of: the method comprises the following steps:
preparing metal organic frameworks ZIFs by adopting a normal-temperature synthesis method, wherein the ZIFs at least comprise ZIF-67 and/or ZIF-8;
step (2), preparing a mixed electrolyte for preparing a composite coating by electrodeposition: dispersing a conductive polymer monomer and a sodium dodecyl sulfate anionic surfactant in deionized water, then adding ZIFs prepared in the step (1), and sequentially and ultrasonically stirring uniformly to obtain a mixed solution;
and (3) adopting a potentiostatic method to use a three-electrode system, and taking the mixed solution prepared in the step (2) as electrolyte to electrodeposit a composite coating on the surface of the working electrode to obtain the electrochemical deposition metal organic framework-conductive polymer anti-corrosion coating.
2. The method for preparing the intelligent metal frame-conductive polymer anti-corrosion coating according to claim 1, wherein the method comprises the following steps: in the step (1), the ZIFs material is provided with a central metal ion by a metal salt, and an imidazole organic matter is provided with an organic ligand.
3. The method for preparing the intelligent metal frame-conductive polymer anti-corrosion coating according to claim 2, wherein the method comprises the following steps: the metal salt is Zn (NO) 3 ) 2 ·6H 2 O and/or Co (NO) 3 ) 2 ·6H 2 The O, imidazole organic matter is 2-methylimidazole.
4. The method for preparing the intelligent metal frame-conductive polymer anti-corrosion coating according to claim 1, wherein the method comprises the following steps: in the step (1), the preparation method of the ZIFs material comprises the following steps: zn (NO) 3 ) 2 ·6H 2 O、Co(NO 3 ) 2 ·6H 2 Dissolving at least one or two mixed metal salts in O in water or methanol to obtain a component A, dissolving a 2-methylimidazole organic ligand in water or methanol to obtain a component B, quickly pouring the component B into the component A after the component A and the component B are fully dissolved, stirring to mix the component A and the component B, standing at room temperature for reaction, centrifugally separating to obtain a precipitate, repeatedly washing the precipitate by methanol, and drying the precipitate to obtain the metal organic framework crystal material ZIF-67 or ZIF-8.
5. The method for preparing the intelligent metal frame-conductive polymer anti-corrosion coating according to claim 4, wherein the method comprises the following steps: the mixing and stirring time of the component A and the component B is 30min, the standing reaction time at room temperature is 12-48 h after mixing, the centrifugal separation time is 10-30 min after reaction, and the precipitate is dried in vacuum after being washed for 3-5 times by methanol, the drying temperature is 50-80 ℃ and the drying time is 12-48 h; in the preparation process of ZIF-67 and ZIF-8, the molar ratio of the center ion to the ligand is 1:58 and 1:70 respectively.
6. The method for preparing the intelligent metal frame-conductive polymer anti-corrosion coating according to claim 1, wherein the method comprises the following steps: in the step (2), the mixed solution comprises pyrrole or aniline monomers with the concentration of 0.1-0.5 mol/L, sodium dodecyl sulfate with the concentration of 0.05-0.3 mol/L and ZIFs with the concentration of 0.5-2 mg/mL.
7. The method for preparing the intelligent metal frame-conductive polymer anti-corrosion coating according to claim 1, wherein the method comprises the following steps: in the step (3), a reference electrode and a counter electrode in the three-electrode deposition system are respectively an Ag/AgCl electrode and a platinum sheet electrode, a working electrode is a stainless steel sample which needs corrosion protection, the electrochemical deposition process adopts a potentiostatic method for deposition, and the electrodeposition time is 10-30 min.
8. The method for preparing the intelligent metal frame-conductive polymer anti-corrosion coating according to claim 1, wherein the method comprises the following steps: in the step (3), the metal organic framework-conductive polymer anti-corrosion coating after electrochemical deposition is washed by deionized water and dried, wherein the drying temperature is 30-50 ℃ and the drying time is 3-5 h.
9. A metal organic framework-conductive polymer corrosion resistant coating prepared by the method of any one of claims 1 to 8.
10. A metal organic framework-conductive polymer corrosion protection coating prepared by the method of any one of claims 1 to 8 applied to corrosion protection of stainless steel in an acidic environment.
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| CN117180522A (en) * | 2023-09-13 | 2023-12-08 | 浙江大学 | ZIF-8coating modified zinc substrate implant and preparation method thereof |
| CN117264470A (en) * | 2023-10-27 | 2023-12-22 | 东北大学 | Bionic coating for preventing marine organism from fouling and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117180522A (en) * | 2023-09-13 | 2023-12-08 | 浙江大学 | ZIF-8coating modified zinc substrate implant and preparation method thereof |
| CN117264470A (en) * | 2023-10-27 | 2023-12-22 | 东北大学 | Bionic coating for preventing marine organism from fouling and preparation method thereof |
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