Anti-corrosion candle ash / MXene functionalized coating as well as preparation method and application thereof

Abstract

The invention relates to an anti-corrosion candle ash / MXene functionalized coating and a preparation method and application thereof.The coating comprises a dodecyl trimethoxy silane-MXene coating and a candle ash coating, the dodecyl trimethoxy silane-MXene coating is arranged on the surface of a substrate, and the candle ash coating is arranged on the surface of the dodecyl trimethoxy silane-MXene coating. A dodecyl trimethoxy silane-MXene coating and a candle ash coating are sequentially and electrically deposited on the surface of a pretreated substrate to prepare the candle ash coating. Compared with the prior art, the long-acting corrosion-resistant metal bipolar plate shows excellent long-acting corrosion resistance in a simulated proton exchange membrane fuel cell environment, and the service life of the metal bipolar plate can be remarkably prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy surface treatment, and in particular to an anti-corrosion candle ash / MXene functionalized coating and a preparation method and application thereof. Background Art

[0002] Proton exchange membrane fuel cell (PEMFC) is a highly efficient clean energy technology with the advantages of low pollution, high energy efficiency, and no noise. It is regarded as one of the important technologies to replace traditional fuel vehicles in the future. As one of the key components of proton exchange membrane fuel cells, bipolar plates play an important role in conducting current and transmitting gases and liquids. The corrosion of metal bipolar plates in the proton exchange membrane fuel cell environment restricts the efficiency of battery use, resulting in a shortened service life of proton exchange membrane fuel cells and increased maintenance costs. The production and manufacturing process of metal bipolar plates is complex and costly, and environmental problems such as carbon emissions may occur during the production process. Carbon emissions are generated during the production and manufacturing of bipolar plates. Every year, CO2 is generated due to the production and manufacturing of steel and aluminum alloys. 2 Emissions account for more than 8% of global carbon emissions. In addition, bipolar plate corrosion causes fuel cell safety problems. Bipolar plate materials must have excellent conductivity, corrosion resistance and mechanical strength. The corrosion problem of fuel cell bipolar plates affects the market size of green hydrogen fuel cell vehicles. In order to improve the corrosion and wear resistance of metal bipolar plates and ensure the safety, stability and efficiency of fuel cells, surface protective coating technology is required. Commonly used coatings for bipolar plate protection include metal, ceramic, and polymer coatings. There are still problems such as difficulty in uniform dispersion of nanofillers, complex preparation processes, unfriendly environment and high costs. At the same time, the thickness of the coating affects the performance of the bipolar plate. The amorphous carbon layer has both anti-corrosion and conductive properties and is an ideal choice for surface protection of metal bipolar plates. However, the commonly used magnetron sputtering preparation technology has problems such as high equipment requirements, low film formation rate, and poor coating stability. The development of new protective coatings is conducive to extending the service life of bipolar plates, reducing carbon emissions, ensuring fuel cell efficiency, reducing safety hazards, and helping the market application of hydrogen electric vehicles.

[0003] Candle ash, as a carbon material produced by incomplete burning of candles, mainly forms a coating through the aggregation of amorphous carbon particles. In recent years, it has been found to have anti-corrosion and hydrophobic characteristics, providing a new idea for metal corrosion protection. The amorphous carbon layer formed by the burning of candle ash has the advantages of fast film formation rate, low equipment requirements, and low cost, and has application value in the surface protection of bipolar plates. However, the poor bonding between the amorphous carbon layer formed by candle ash and the metal substrate makes its stable protection effect a bottleneck problem in application.

[0004] Chinese patent application number 201610040269.1 discloses a method for preparing a super hydrophobic coating using candle ash. Its advantages are low cost, simple process, and suitability for large-scale production. However, this method also has some shortcomings, such as poor durability of the coating and easy damage under extreme conditions. In addition, the coating has a relatively single function, which limits its application in specific fields.

[0005] The Chinese patent application number 202111382930.4 discloses a durable super-hydrophobic candle soot coating, comprising a metal substrate pretreated by chemical etching, a bonding layer and hydrophobic soot particles, wherein the hydrophobic soot particles are soot particles generated by incomplete combustion of candles, and the soot particles are completely and evenly distributed on the bonding layer surface of the substrate. The invention has good stability and durability, and has excellent self-cleaning properties and good corrosion resistance. However, the coating preparation process is relatively complicated and the cost is relatively high. Summary of the invention

[0006] The purpose of the present invention is to provide an anti-corrosion candle ash / MXene functionalized coating and its preparation method and application, which has good hydrophobicity and long-term anti-corrosion performance, can significantly extend the service life of metal bipolar plates, and the preparation method is simple and suitable for industrial production.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] On the one hand, the present invention provides an anti-corrosion candle ash / MXene functionalized coating, comprising a dodecyltrimethoxysilane (DTMS)-MXene coating and a candle ash coating, wherein the dodecyltrimethoxysilane-MXene coating is disposed on a surface of a substrate, and the candle ash coating is disposed on a surface of the dodecyltrimethoxysilane-MXene coating.

[0009] Preferably, the MXene comprises Ti 3 C 2 T x .

[0010] Further preferably, the Ti 3 C 2 T x Few-layer Ti 3 C 2 T x , the Ti 3 C 2 T x The number of layers is 1-7.

[0011] Preferably, the substrate comprises a metal substrate.

[0012] Further preferably, the substrate comprises an aluminum alloy.

[0013] More preferably, the aluminum alloy is 5052 aluminum alloy.

[0014] Preferably, the candle ash coating comprises spherical carbon particles.

[0015] Further preferably, the diameter of the spherical carbon particles is between 20-50 nm.

[0016] Further preferably, the candle ash coating has a porous structure, and the porous structure is formed by connecting spherical carbon particles.

[0017] Further preferably, the pore size of the candle ash coating ranges from nanometer scale to micrometer scale.

[0018] More preferably, the pore size of the candle ash coating is 20-80 nm.

[0019] Preferably, the thickness of the dodecyltrimethoxysilane-MXene coating is 10-20 μm, and the thickness of the candle ash coating is 40-60 μm.

[0020] Further preferably, the candle ash / MXene functionalized coating includes a DTMS-MXene coating formed on the surface of the aluminum alloy, and a candle ash coating covering the DTMS-MXene coating.

[0021] In a second aspect, the present invention provides a method for preparing the anti-corrosion candle ash / MXene functionalized coating, comprising the following steps:

[0022] S1: substrate surface pretreatment;

[0023] S2: preparing dodecyltrimethoxysilane-MXene coating deposition solution;

[0024] S3: using a dodecyltrimethoxysilane-MXene coating deposition liquid as an electrolyte, performing electrodeposition on the pretreated substrate surface to prepare the dodecyltrimethoxysilane-MXene coating;

[0025] S4: candle ash is deposited on a substrate having a dodecyltrimethoxysilane-MXene coating to prepare the candle ash / MXene functionalized coating.

[0026] Preferably, step S1 comprises the following steps: polishing the surface of the substrate, and performing ultrasonic cleaning in an ethanol solution and deionized water in sequence, with each ultrasonic cleaning time being 1-3 minutes.

[0027] Further preferably, in step S1, the specific step of polishing is: polishing the substrate smooth with 80 mesh, 240 mesh, 400 mesh, 1000 mesh, and 2000 mesh sandpaper in sequence.

[0028] Further preferably, in step S1, the specific steps of ultrasonic cleaning are: placing the polished substrate in an ethanol solution, ultrasonic cleaning, and then ultrasonic cleaning with deionized water to remove oil and dust on the surface of the aluminum alloy.

[0029] Further preferably, in step S1, the ultrasonic cleaning with deionized water is performed 1-2 times.

[0030] Further preferably, in step S1, the duration of each ultrasonic cleaning is 2 minutes.

[0031] Preferably, step S2 comprises the following steps: dissolving dodecyltrimethoxysilane and cerium trichloride in an ethanol solution, adding Ti 3 C 2 T x The dispersion is stirred evenly to obtain the dodecyltrimethoxysilane-MXene coating deposition liquid.

[0032] Preferably, in step S2, in the dodecyltrimethoxysilane-MXene coating deposition solution, the concentration of dodecyltrimethoxysilane is 30-40 mg / mL, the concentration of cerium trichloride is 10-20 mg / mL, and the concentration of Ti is 10-20 mg / mL. 3 C 2 T x The concentration is 0.05-0.15mg / mL.

[0033] Further preferably, in step S2, the dodecyltrimethoxysilane-MXene coating deposition solution includes 50 mL of ethanol solution, 2 mL of DTMS, 0.74516 g of cerium trichloride, 1 mL of Ti 3 C 2 T x Dispersion.

[0034] More preferably, in step S2, the purity of the DTMS is 97%, the purity of the cerium trichloride is 99.99%, and the purity of the Ti 3 C 2 T x The concentration of the dispersion was 5 mg / mL.

[0035] Further preferably, in step S2, the stirring is uniformly carried out by stirring with a magnetic stirrer and a rotor.

[0036] More preferably, in step S2, the stirring temperature is room temperature, and the stirring time is 10-20 min.

[0037] Preferably, in step S3, the substrate pretreated in step S1 is used as a cathode and the platinum electrode is used as an anode for electrodeposition, and the electrodeposition voltage is 5-40 V and the time is 5-40 min.

[0038] Further preferably, in step S3, after the electrodeposition, the coating is naturally dried at room temperature to prepare the dodecyltrimethoxysilane-MXene coating.

[0039] Preferably, in step S4, when the substrate is a small-area substrate, the following steps are included: placing the substrate having the dodecyltrimethoxysilane-MXene coating above a candle flame and moving it back and forth to deposit candle ash to prepare the candle ash / MXene functionalized coating.

[0040] Further preferably, in step S4, the candle ash deposition time is 1-10 minutes.

[0041] Preferably, in step S4, when used for large-scale industrial production, the following steps are included: collecting candle ash in advance, depositing the candle ash on a substrate by a direct deposition method such as coating, and preparing the candle ash / MXene functionalized coating.

[0042] Further preferably, the method for preparing the anti-corrosion candle ash / MXene functionalized coating comprises the following steps:

[0043] S1, aluminum alloy surface pretreatment;

[0044] S2, take the ethanol solution, add dodecyltrimethoxysilane DTMS and cerium trichloride, stir evenly, take Ti 3 C 2 T x A small layer of dispersion liquid is added to the above solution to obtain a deposition liquid;

[0045] S3, connecting the positive and negative poles of the potentiostat to the platinum electrode and the pretreated blank aluminum alloy prepared in step S1, respectively, using the solution prepared in step S2 as the electrolyte, the pretreated blank aluminum alloy prepared in step S1 as the cathode, and the platinum electrode as the anode for electrodeposition, and after the electrodeposition is completed, turning off the power supply, removing the wiring, and obtaining the DTMS-MXene coating;

[0046] S4, light a candle, and place the dried DTMS / MXene-coated aluminum alloy obtained in step S3 at the highest point of the candle flame, so that the candle ash particles are evenly distributed on the surface of the aluminum alloy sample to obtain a candle ash / MXene functionalized coating (CS-DTMS-MXene).

[0047] In a third aspect, the present invention also provides an application of the anti-corrosion candle ash / MXene functionalized coating in the field of metal bipolar plate manufacturing.

[0048] Preferably, the metal bipolar plate is used in fuel cells, ocean, petroleum, chemical industry, new energy and other fields.

[0049] In the present invention, the candle ash coating is composed of spherical carbon particles, has a porous structure and exhibits super hydrophobicity, so that it has a strong repelling effect on corrosive media, and the dodecyltrimethoxysilane (DTMS) / MXene electrodeposition layer further improves the bonding between the candle ash coating and the substrate, extending the long-term anti-corrosion performance of the coating. By sequentially depositing the DTMS / MXene electrodeposition layer and the candle ash on the metal surface, an anti-corrosion candle ash / MXene functionalized coating is formed. The candle ash / MXene functionalized coating of the present invention exhibits good long-term anti-corrosion performance in a simulated proton exchange membrane fuel cell environment, and can significantly reduce the corrosion current density, thereby extending the service life of the metal bipolar plate. The present invention is suitable for the surface protection of metal bipolar plates in proton exchange membrane fuel cells, and can also be extended to the surface corrosion protection of metal materials in other corrosive medium environments. In addition, the present invention is simple to prepare, low in cost, and can effectively utilize waste candle ash (carbon particles).

[0050] In the present invention, MXene, as a graphene-like two-dimensional transition metal carbon / nitrogen and carbonitride, can be widely used in the field of metal surface protective coatings due to its strong barrier properties, rich surface functional groups, metal-like conductivity, large specific surface area and other characteristics. Dodecyltrimethoxysilane (DTMS) has great potential in metal surface treatment technology due to its hydrolysis to form S-OH and wettability and dispersibility. The coupling agent properties of DTMS and the construction of the intermediate layer with MXene can solve the stability problem of the candle ash amorphous carbon layer.

[0051] The anti-corrosion candle ash / MXene functionalized coating of the present invention exhibits good hydrophobicity (contact angle reaches 152°) and chemical stability. In the non-immersion experiment, the corrosion current density I corr (2.871×10 -8 A / cm 2 ) than the blank aluminum alloy corr (6.017×10 -4 A / cm 2 ) is 4 orders of magnitude lower than that of the candle ash coating alone. corr (3.370×10 -8 A / cm 2 ) is low, and the candle ash / MXene functionalized coating significantly improves the corrosion resistance of the aluminum alloy surface.

[0052] In a simulated proton exchange membrane fuel cell environment, the impedance modulus value of the candle ash / MXene functionalized coating of the present invention at 0.01 Hz (1.255×10 6 Ω·cm 2 ) than candle ash coating (8.167×10 4 Ω·cm 2 ) is 2 orders of magnitude higher than that of blank aluminum alloy (8.682Ω·cm 2 ) is 5 orders of magnitude higher, indicating that the corrosion protection effect of the candle ash / MXene functionalized coating is significantly improved; after immersion for 20 days, the |Z| 0.01 The Hz value dropped to 103.1Ω·cm 2 , which is lower than the candle ash coating alone (4.231Ω·cm 2 ), blank aluminum alloy (4.627Ω·cm 2 ) are 1 order of magnitude higher. This shows that under the same corrosion environment and after the same immersion time, the candle ash coating alone has peeled off, just like the blank aluminum alloy. The candle ash / MXene functionalized coating can provide a longer-lasting protective effect.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) The present invention prepares an anti-corrosion candle ash / MXene functionalized coating by sequentially depositing a DTMS-MXene coating and a candle ash coating on the surface of a substrate. The coating has good hydrophobicity and long-lasting anti-corrosion performance, can significantly extend the service life of the metal bipolar plate, and the preparation method is simple and suitable for industrial production.

[0055] (2) The present invention utilizes the coupling agent properties of DTMS and MXene to construct a DTMS-MXene coating as an intermediate layer, which solves the problem of poor bonding and poor stability of the candle ash amorphous carbon layer, can further improve the bonding between the candle ash coating and the substrate, and extend the long-term anti-corrosion performance of the coating.

[0056] (3) The candle ash coating of the present invention is composed of spherical carbon particles, has a porous structure and exhibits super-hydrophobicity, so that it has a strong repelling effect on corrosive media and improves the anti-corrosion performance.

[0057] (4) In the present invention, the DTMS-MXene coating is relatively thin, which avoids the high interface resistance caused by the large coating thickness. At the same time, it can cover the aluminum alloy substrate, which can effectively slow down the direct contact between the corrosive liquid medium and the metal substrate surface, and can provide long-term corrosion protection performance on the metal surface.

[0058] (5) The anti-corrosion candle ash / MXene functionalized coating of the present invention has significant comprehensive advantages in terms of preparation time, cost, equipment requirements, etc., and provides a new idea for promoting the practical application of corrosion-resistant metal bipolar plate products. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a field emission scanning electron microscope (FE-SEM) surface morphology image of a blank aluminum alloy (Blank surface) after pretreatment in the present invention;

[0060] Figure 2 This is a field emission scanning electron microscope (FE-SEM) surface morphology image of the electrodeposited DTMS-MXene coating in the present invention;

[0061] Figure 3 The surface morphology of the candle ash coating (CS) prepared in the present invention at different magnifications of field emission scanning electron microscope (FE-SEM);

[0062] Figure 4 The surface morphology of the candle ash / MXene functionalized coating (CS-DTMS-MXene) prepared in the present invention at different magnifications of field emission scanning electron microscopy (FE-SEM);

[0063] Figure 5 The potentiodynamic polarization curves of the blank aluminum alloy (Blank surface), candle ash coating only (CS), and candle ash / MXene functionalized coating (CS-DTMS-MXene) after pretreatment in the present invention in the acidic environment of a simulated proton exchange membrane fuel cell;

[0064] Figure 6 The Nyquist plots of electrochemical impedance spectra of blank aluminum alloy, candle ash coating only, and candle ash / MXene functionalized coating after pretreatment in the present invention in a simulated proton exchange membrane fuel cell acidic environment;

[0065] Figure 7 Bode diagram of electrochemical impedance spectra of blank aluminum alloy, candle ash coating only, and candle ash / MXene functionalized coating after pretreatment in the present invention in a simulated proton exchange membrane fuel cell acidic environment;

[0066] Figure 8 It is a graph showing the variation of low-frequency impedance modulus with immersion time in long-term immersion experiments of blank aluminum alloy, candle ash coating only, and candle ash / MXene functionalized coating after pretreatment in the present invention;

[0067] Fig. 9Schematic diagram of the change of contact angle over time of the candle ash coating only and the candle ash / MXene functionalized coating prepared in Example 1 of the present invention in the simulated proton exchange membrane fuel cell acidic environment, wherein (a) is the candle ash coating only, and (b) is the candle ash / MXene functionalized coating;

[0068] Fig.10 It is a potentiodynamic polarization curve diagram of Examples 1-3 of the present invention in the acidic environment of a simulated proton exchange membrane fuel cell. DETAILED DESCRIPTION

[0069] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0070] The present invention provides an anti-corrosion candle ash / MXene functionalized coating, comprising a dodecyltrimethoxysilane (DTMS)-MXene coating and a candle ash coating, wherein the dodecyltrimethoxysilane-MXene coating is arranged on a substrate surface, and the candle ash coating is arranged on a dodecyltrimethoxysilane-MXene coating surface.

[0071] The preparation method is as follows:

[0072] S1: substrate surface pretreatment;

[0073] S2: preparing dodecyltrimethoxysilane-MXene coating deposition solution;

[0074] S3: using a dodecyltrimethoxysilane-MXene coating deposition liquid as an electrolyte, performing electrodeposition on the pretreated substrate surface to prepare the dodecyltrimethoxysilane-MXene coating;

[0075] S4: placing the substrate having the dodecyltrimethoxysilane-MXene coating above a candle flame to deposit candle ash to prepare the candle ash / MXene functionalized coating.

[0076] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. The various chemicals and raw materials used in the following examples are commercially available products, as follows:

[0077] The 5052 aluminum alloy plate (40×13×3 mm) used in the present invention was purchased from Shenzhen Hongwang Mould Co., Ltd., n-dodecyl trimethoxysilane (97%) and cerium trichloride (99.99%) were purchased from Titan Technology Co., Ltd., and 5 mg / mL Ti 3 C2 T x MXene was purchased from Jilin Eleven Technology Co., Ltd. (Jilin Province, China). All solvents and chemicals were analytical grade reagents without further purification.

[0078] The method for detecting performance in the following embodiments is as follows:

[0079] The present invention uses a field emission scanning electron microscope (FE-SEM, JEOL, JSM-7800F, Japan) at 5 kV to observe the surface morphology of the sample, and uses a contact angle meter (JC 2000D5, Shanghai Zhongchen Digital Technology Instrument Co., Ltd.) to measure the contact angle of water droplets on different samples at room temperature.

[0080] The electrochemical tests of various samples were carried out on an electrochemical workstation (CHI600E, Shanghai Chenhua Instrument Co., Ltd., China). 2 SO 4 The electrochemical performance of the finished product and the control group were tested in a simulated proton exchange fuel cell environment (with 2ppm HF solution) to obtain a stable open circuit potential (E OCP ). Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve tests were carried out in a three-electrode system. 2 ) as the working electrode, platinum as the counter electrode, and saturated calomel electrode as the reference electrode. For EIS testing, the frequency was set to 10 5 -10 -2 Hz, with an amplitude of 5 mV. The equivalent circuit was fitted using ZSimpWin software. The scanning range of the potentiodynamic polarization test was E OCP ±300mV (vs.SCE), scanning speed is 1mV / s. Calculate the protection efficiency (η%) according to the following formula:

[0081]

[0082] Among them I corr(Bare Al alloy) and I corr(coating) are the corrosion current densities of blank aluminum alloy and coating samples, respectively.

[0083] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0084] Example 1

[0085] This embodiment provides an anti-corrosion candle ash / MXene functionalized coating, and the specific preparation steps are as follows:

[0086] 1) Pre-treat aluminum alloy. The specific steps are as follows:

[0087] The 5052 aluminum alloy was polished with 80 mesh, 240 mesh, 400 mesh, 1000 mesh, and 2000 mesh sandpaper in sequence. The polished aluminum alloy was placed in an ethanol solution and ultrasonically cleaned twice, and then ultrasonically cleaned twice with deionized water in sequence, each cleaning lasting about 2 minutes, to remove oil and dust on the surface of the aluminum alloy.

[0088] 2) Prepare the deposition solution, the specific steps are as follows:

[0089] Take 50 mL of ethanol solution, add 2 mL of DTMS and 0.74516 g of cerium (III) chloride, and stir evenly with a magnetic stirrer and rotor. 3 C 2 T x The dispersion was added into the above solution and stirred at room temperature for 15 min to obtain the sedimentation solution.

[0090] 3) Preparation of DTMS-MXene coating, the specific steps are as follows:

[0091] The positive and negative poles of the potentiostat are respectively connected to the platinum electrode and the pretreated blank aluminum alloy prepared in step 1) and (the pretreated blank aluminum alloy is used as the cathode / negative electrode, and the platinum electrode is used as the anode / positive electrode), and placed in the deposition solution prepared in step 2), the voltage is set to 30V, the time is set to 30min, the electrodeposition is completed, and it is naturally dried at room temperature to obtain the DTMS-MXene coating.

[0092] 4) Preparation of candle ash / MXene coating (CS-DTMS-MXene), the specific steps are as follows:

[0093] Light a candle. Place the dried electrodeposited aluminum alloy at the highest point of the candle flame, press down, and move back and forth for about 4 minutes to evenly distribute the candle ash particles on the surface of the aluminum alloy sample. Obtain a candle ash / MXene functionalized coating.

[0094] Example 2

[0095] This embodiment provides an anti-corrosion candle ash / MXene functionalized coating, and the specific preparation steps are as follows:

[0096] 1) Pre-treat aluminum alloy. The specific steps are as follows:

[0097] The 5052 aluminum alloy was polished with 80 mesh, 240 mesh, 400 mesh, 1000 mesh, and 2000 mesh sandpaper in sequence. The polished aluminum alloy was placed in an ethanol solution and ultrasonically cleaned twice, and then ultrasonically cleaned twice with deionized water in sequence, each cleaning lasting about 2 minutes, to remove oil and dust on the surface of the aluminum alloy.

[0098] 2) Prepare the deposition solution, the specific steps are as follows:

[0099] Take 50 mL of ethanol solution, add 2 mL of DTMS and 0.74516 g of cerium (III) chloride, and stir evenly with a magnetic stirrer and rotor. 3 C 2 T x The dispersion was added to the above solution and stirred at room temperature for 15 min to obtain a sedimentation solution;

[0100] 3) Prepare MXene coating, the specific steps are as follows:

[0101] The positive and negative poles of the potentiostat are respectively connected to the pretreated blank aluminum alloy and the platinum electrode prepared in step 1) (wherein the pretreated blank aluminum alloy is used as the cathode / negative electrode and the platinum electrode is used as the anode / positive electrode), placed in the deposition solution prepared in step 2), the voltage is set to 5V, the time is set to 20min, the electrodeposition is completed, and it is naturally dried at room temperature to obtain a MXene coating.

[0102] 4) Preparation of candle ash / MXene coating, the specific steps are as follows:

[0103] Light a candle. Place the dried electrodeposited aluminum alloy at the highest point of the candle flame, press down, and move back and forth for about 4 minutes to evenly distribute the candle ash particles on the surface of the aluminum alloy sample. Obtain the candle ash / MXene coating.

[0104] Example 3

[0105] This embodiment provides an anti-corrosion candle ash / MXene functionalized coating, and the specific preparation steps are as follows:

[0106] 1) Pre-treat aluminum alloy. The specific steps are as follows:

[0107] The 5052 aluminum alloy was polished with 80 mesh, 240 mesh, 400 mesh, 1000 mesh, and 2000 mesh sandpaper in sequence. The polished aluminum alloy was placed in an ethanol solution and ultrasonically cleaned twice, and then ultrasonically cleaned twice with deionized water in sequence, each cleaning lasting about 2 minutes, to remove oil and dust on the surface of the aluminum alloy.

[0108] 2) Prepare the deposition solution, the specific steps are as follows:

[0109] Take 50 mL of ethanol solution, add 2 mL of DTMS and 0.74516 g of cerium (III) chloride, and stir evenly with a magnetic stirrer and rotor. 3 C 2 T x The dispersion was added to the above solution and stirred at room temperature for 15 min to obtain a sedimentation solution;

[0110] 3) Prepare MXene coating, the specific steps are as follows:

[0111] The positive and negative poles of the potentiostat are respectively connected to the pretreated blank aluminum alloy and the platinum electrode prepared in step 1) (wherein the pretreated blank aluminum alloy is used as the cathode / negative electrode and the platinum electrode is used as the anode / positive electrode), placed in the deposition solution prepared in step 2), the voltage is set to 30 V, the time is set to 30 min, the electrodeposition is completed, and it is naturally dried at room temperature to obtain a MXene coating.

[0112] 4) Preparation of candle ash / MXene coating, the specific steps are as follows:

[0113] Light a candle. Place the dried electrodeposited aluminum alloy at the highest point of the candle flame, press down, and move back and forth for about 2 minutes to evenly distribute the candle ash particles on the surface of the aluminum alloy sample. Obtain the candle ash / MXene coating.

[0114] Comparative Example 1

[0115] The blank aluminum alloy substrate after pretreatment is different from Example 1 in that only step 1 is performed.

[0116] Comparative Example 2

[0117] Candle ash coating only, unlike Example 1, only steps 1 and 4 were performed.

[0118] Field emission scanning electron microscope (FE-SEM) surface morphology of the blank aluminum alloy after pretreatment, such as Figure 1 As shown in Figure 1, the surface of the pretreated aluminum alloy has small pores and grinding marks, and the surface is not smooth. The surface morphology of the electrodeposited DTMS-MXene coating is shown in Figure 1. Figure 2 As shown in Figure 1, DTMS-MXene is relatively thin and has holes on the coating surface. The amorphous carbon coating (CS) formed by depositing only candle ash, that is, the surface morphology of the candle ash coating, is shown in Figure 1. Figure 3 As shown in Figure 1, the candle ash coating has a porous structure formed by spherical carbon particles connected together. The diameter of the spherical carbon particles is between 20-50nm, and the pore size ranges from nanometers to micrometers. Scanning electron micrographs of candle ash / MXene functionalized coatings at different magnifications are shown in Figure 1. Figure 4 As shown, compared with the candle ash-only coating, the surface of the candle ash / MXene functionalized coating is rougher, and the coating structure is mainly formed by the aggregation of carbon particles.

[0119] Comparative Example 1, Comparative Example 2, and Example 1 were subjected to electrochemical tests in a simulated proton exchange membrane fuel cell acidic environment, and the results are as follows:

[0120] Figure 5Table 1 shows the potential polarization curves of blank aluminum alloy (Comparative Example 1), candle ash coating only (Comparative Example), and candle ash / MXene functionalized coating (Example 1) in the simulated proton exchange membrane fuel cell acidic environment. Table 1 shows the potential polarization curves of blank aluminum alloy, candle ash coating only, and candle ash / MXene functionalized coating after pretreatment in the present invention ( Figure 5 ) obtained, it can be seen from Table 1 that only the E corr The highest is 0.137 V, and the E corr The E of the blank aluminum alloy is close to that of the candle ash coating alone, which is 0.034V. corr The lowest is -0.743V, which indicates that candle ash and candle ash / MXene functionalized coatings can improve the corrosion resistance of aluminum alloys under acidic conditions. The corrosion current density of candle ash / MXene functionalized coating can reach 2.871×10 -8 A / cm 2 , which is 4 orders of magnitude lower than that of the blank aluminum alloy after pretreatment and lower than that of the candle ash coating alone (3.370×10 -8 A / cm 2 ) is low, and the protection efficiency is as high as 99.9952%. The higher the corrosion current density, the higher the corrosion reaction rate and the less corrosion resistant the material. The results show that the candle ash / MXene functionalized coating has the best anti-corrosion performance.

[0121] Table 1 Electrochemical parameters obtained from potentiodynamic polarization curves

[0122] sample <![CDATA[E corr (mV)]]> <![CDATA[I corr (A / cm 2 )]]> η(%) Comparative Example 1 -743 <![CDATA[6.017×10 -4 ]]> - Comparative Example 2 137 <![CDATA[3.370×10 -8 ]]> 99.9944 Example 1 34 <![CDATA[2.871×10 -8 ]]> 99.9952

[0123] From the Nyquist plot of electrochemical impedance spectroscopy ( Figure 6 ) It can be seen that the candle ash / MXene functionalized coating has the largest capacitive reactance arc, indicating that it has the best anti-corrosion effect, followed by the candle ash coating, while the blank aluminum alloy has poor corrosion resistance, which can further prove that the candle ash / MXene functionalized coating has excellent corrosion resistance. The impedance modulus value in the low-frequency region of the Bode diagram of the electrochemical impedance spectrum is proportional to the anti-corrosion performance, such as Figure 7 As shown, the candle ash / MXene functionalized coating has the highest impedance and therefore has the best corrosion resistance.

[0124] The immersion experiment was carried out in a more corrosive simulated proton exchange membrane fuel cell acidic environment. The impedance modulus of the pretreated blank aluminum alloy, candle ash coating only, and candle ash / MXene functionalized coating at a frequency of 0.01 Hz during the immersion process was compared. The results are shown in Figure 2. Figure 8 As shown, before immersion, the |Z| 0.01HzValue (1.255×10 6 Ω·cm 2 ) than the candle ash coating alone |Z| 0.01Hz Value (8.167×10 4 Ω·cm 2 ) is higher than that of the blank aluminum alloy |Z| 0.01Hz Value (8.682Ω·cm 2 ) is nearly 5 orders of magnitude higher, which shows that the corrosion protection effect of the candle ash / MXene functionalized coating is better than that of comparative examples 1-2. During the immersion process, it can be seen that the |Z| 0.01Hz The values ​​are higher than those of candle ash coating alone and blank aluminum alloy. After immersion for 20 days, the |Z| 0.01Hz Value (103.1Ω·cm 2 ) than the candle ash coating alone |Z| 0.01Hz Value (4.231Ω·cm 2 ), blank aluminum alloy |Z| 0.01Hz Value (4.627Ω·cm 2 ) are both high. In addition, only the candle ash coating has a significantly reduced low-frequency impedance modulus to close to that of the blank aluminum alloy after immersion for 3 days, indicating that the candle ash coating has fallen off and lost its anti-corrosion effect. Therefore, the electrochemical immersion experiment proves that the deposition of DTMS-MXene coating can improve the long-term anti-corrosion performance of the candle ash coating in an acidic environment.

[0125] The wettability of the coating is directly reflected by the size of the contact angle. The contact angle changes over time in Comparative Example 2 and Example 1 in the simulated proton exchange membrane fuel cell acidic environment are shown in Figure 2. Fig. 9 As shown. The results show that only the candle ash coating maintains a contact angle of about 147°-148° in a short period of time (within 12 hours). The contact angle of the candle ash / MXene functionalized coating is stable at about 147°-148° for a longer period of time (6 days). This shows that the candle ash / MXene functionalized coating still maintains long-term hydrophobicity when immersed in an acidic solution, providing conditions for the long-term anti-corrosion performance of the coating.

[0126] like Fig.10 As shown in Figure 2, compared with Example 1, when the voltage of the electrodeposition DTMS / MXene intermediate layer is 5 V and the electrodeposition time is 20 min, the electrochemical parameters obtained from the potentiodynamic polarization curve show that the corrosion current density of the candle ash / MXene functionalized coating can reach 4.543×10 -8 A / cm 2 The corrosion current density of the candle ash coating is slightly different from that of the blank aluminum alloy, but it is quite different from that of the blank aluminum alloy, and the role of the intermediate layer is significant.

[0127] Compared with Example 1, in Example 3, when the deposition time of the candle ash coating was 2 min, the candle ash was difficult to completely and evenly cover the substrate surface, and the protection effect was poor. However, due to the electrodeposition of the DTMS-MXene coating, the electrochemical parameters obtained by the potentiodynamic polarization curve showed that the corrosion current density of the candle ash / MXene functionalized coating could reach 6.308×10 -8 A / cm 2 , the candle ash / MXene functionalized coating can still exert a significant anti-corrosion effect when the candle ash deposition effect is poor.

[0128] In summary, the present invention forms an anti-corrosion candle ash / MXene functionalized coating by sequentially depositing a DTMS-MXene coating and a candle ash amorphous coating on the surface of a substrate, which exhibits excellent long-term anti-corrosion performance in a simulated proton exchange membrane fuel cell environment and can significantly extend the service life of metal bipolar plates.

[0129] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. An anti-corrosion candle ash / MXene functionalized coating, characterized in that: It includes a dodecyltrimethoxysilane-MXene coating and a candle ash coating, wherein the dodecyltrimethoxysilane-MXene coating is arranged on the surface of a substrate, and the candle ash coating is arranged on the surface of the dodecyltrimethoxysilane-MXene coating.

2. The anti-corrosion candle ash / MXene functionalized coating according to claim 1, characterized in that: The substrate comprises an aluminum alloy; The MXene includes Ti3C2T x ; The candle ash coating comprises spherical carbon particles and has a porous structure with a pore size of 20-80 nm.

3. The anti-corrosion candle ash / MXene functionalized coating according to claim 2, characterized in that: The Ti3C2T x For few-layer Ti3C2T x , the Ti3C2T x The number of layers is 1-7; The diameter of the spherical carbon particles is between 20-50 nm.

4. The anti-corrosion candle ash / MXene functionalized coating according to claim 1, characterized in that: The thickness of the dodecyltrimethoxysilane-MXene coating is 10-20 μm, and the thickness of the candle ash coating is 40-60 μm.

5. A method for preparing an anti-corrosion candle ash / MXene functionalized coating according to any one of claims 1 to 4, characterized in that: The steps include: S1: substrate surface pretreatment; S2: preparing dodecyltrimethoxysilane-MXene coating deposition solution; S3: using a dodecyltrimethoxysilane-MXene coating deposition liquid as an electrolyte, performing electrodeposition on the pretreated substrate surface to prepare the dodecyltrimethoxysilane-MXene coating; S4: candle ash is deposited on a substrate having a dodecyltrimethoxysilane-MXene coating to prepare the candle ash / MXene functionalized coating.

6. The method for preparing the anti-corrosion candle ash / MXene functionalized coating according to claim 5, characterized in that: Step S1 includes the following steps: polishing the surface of the substrate, and performing ultrasonic cleaning in an ethanol solution and deionized water in sequence, with each ultrasonic cleaning time being 1-3 minutes.

7. The method for preparing the anti-corrosion candle ash / MXene functionalized coating according to claim 5, characterized in that: Step S2 comprises the following steps: dissolving dodecyltrimethoxysilane and cerium trichloride in an ethanol solution, adding Ti3C2T x The dispersion is stirred evenly to obtain the dodecyltrimethoxysilane-MXene coating deposition liquid.

8. The method for preparing the anti-corrosion candle ash / MXene functionalized coating according to claim 7, characterized in that: In step S2, in the dodecyltrimethoxysilane-MXene coating deposition solution, the concentration of dodecyltrimethoxysilane is 30-40 mg / mL, the concentration of cerium trichloride is 10-20 mg / mL, and the concentration of Ti3C2T x The concentration is 0.05-0.15mg / mL.

9. The method for preparing the anti-corrosion candle ash / MXene functionalized coating according to claim 5, characterized in that: In step S3, the substrate pretreated in step S1 is used as a cathode and the platinum electrode is used as an anode for electroplating. The voltage of the electroplating is 5-40V and the time is 5-40min.

10. An application of the anti-corrosion candle ash / MXene functionalized coating according to any one of claims 1 to 4 in the field of metal bipolar plate manufacturing.

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