Preparation method and application of heat-resistant and corrosion-resistant urea modified nickel-based hydroxide ultrathin coating

Abstract

The invention relates to a preparation method and application of a heat-resistant and corrosion-resistant urea modified nickel-based hydroxide ultrathin coating. According to the method, the urea molecule modified nickel-based hydroxide coating is formed on the surface of the metal material, and the coating has the nucleophilic attack effect of urea molecule carbonyl oxygen and nickel atoms in nickel-based hydroxide and the hydrogen-bond effect of urea molecule amino hydrogen and nickel-based hydroxide hydroxyl oxygen. The stable anchoring between urea and nickel-based hydroxide is formed through the nucleophilic attack effect, and meanwhile, a surface compact molecular network electrostatic field is formed through the hydrogen-bond interaction, so that the penetration of various corrosive ions can be repelled in a coulomb manner, and the coating has good thermal and chemical stability. The method disclosed by the invention is simple to operate, low in energy consumption, easy for large-scale production, suitable for substrates with complex shapes, and capable of being widely applied to industrial scenes needing corrosion-resistant and heat-resistant metal materials, such as ocean engineering, chemical equipment, high-temperature parts and the like, and provides technical support for long-life application of the metal-based materials.

Description

Technical Field

[0001] This invention relates to the field of metal corrosion and protection, and in particular to a method for preparing and applying a heat- and corrosion-resistant urea-modified nickel-based hydroxide ultrathin coating. Background Technology

[0002] Metallic materials often face challenges from heat and air corrosion, making the development of heat- and corrosion-resistant coatings crucial for their application. Typically, metallic materials spontaneously oxidize in air, forming a relatively stable natural oxide protective layer. However, this spontaneously formed protective layer is often uneven in thickness, prone to localized stress and cracking, thus failing to adequately protect the internal metal from further oxidation. Furthermore, the relatively thick oxide layer often fails to provide protection when the metal substrate is subjected to external forces due to its ceramic-like brittleness. More importantly, oxide protective layers are generally ineffective against high-temperature air corrosion. In addition, coating with organic corrosion-resistant materials or alloying are currently the main methods for corrosion resistance in metallic materials. Alloying typically introduces highly polluting heavy metal ions such as chromium and molybdenum, and is also an energy-intensive process; while organic coatings are susceptible to high temperatures and aging, making them unsuitable for practical applications. Therefore, there is an urgent need to develop environmentally friendly, heat- and corrosion-resistant, ultra-thin, dense, and highly stable oxide coating technology. Summary of the Invention

[0003] The technical problem to be solved by this invention is that the oxide protective layer spontaneously formed on the surface of metal materials is relatively thick and usually has ceramic-like brittleness. When the metal substrate is subjected to external force, the protective layer is easy to fall off and lose its protective function. Moreover, the oxide protective layer is usually difficult to resist air corrosion at high temperature. Alloying usually introduces highly polluting heavy metal ions such as chromium and molybdenum, and alloying is a high-energy-consuming process. Organic coating materials have problems such as poor high-temperature resistance and easy aging.

[0004] To solve the above-mentioned technical problems, the overall idea of ​​this invention is:

[0005] A urea-modified nickel-based hydroxide coating is formed on the surface of a metallic material. This coating exhibits nucleophilic attack between the carbonyl oxygen of the urea molecule and the nickel atom in the nickel-based hydroxide, as well as hydrogen bonding between the amino hydrogen of the urea molecule and the hydroxyl oxygen of the nickel-based hydroxide. Through nucleophilic attack, the coating establishes a stable anchor between urea and nickel-based hydroxide. Simultaneously, through hydrogen bonding, a dense molecular network electrostatic field is formed on the surface, thus coulombically repelling the penetration of various corrosive ions. This results in a coating with excellent thermal and chemical stability. The specific technical solution is as follows:

[0006] Technical Solution 1: A method for forming a heat-resistant and corrosion-resistant urea-modified nickel-based hydroxide ultrathin coating on the surface of a nickel-based metal material, comprising the following steps:

[0007] 1) The nickel-based metal material is soaked in acid or polished to remove possible surface contamination and spontaneous oxide layer, and then ultrasonically washed with ethanol and deionized water in sequence, and then dried as the working electrode to be reconstructed.

[0008] 2) Dissolve urea, sodium hydroxide or potassium hydroxide in deionized water to prepare an electrolyte. The concentrations of each component in the electrolyte are: urea: 0.01-1 mol / L, sodium hydroxide or potassium hydroxide: 0.001-5 mol / L, sodium hydroxide or 0.001-5 mol / L potassium hydroxide.

[0009] 3) The working electrode to be reconstructed obtained from the nickel-based metal material treated in step 1) is placed in the urea-containing electrolyte prepared in step 2) and used as the working electrode to be reconstructed for cyclic voltammetry electrochemical treatment.

[0010] 4) The nickel-based metal material obtained by step 3) after reconstruction is cleaned with deionized water and then air-blown and dried to form a urea-modified nickel hydroxide heat-resistant and corrosion-resistant urea-modified ultrathin coating on the nickel-based metal material.

[0011] Technical Solution 2: A method for forming a heat-resistant and corrosion-resistant urea-modified nickel-based hydroxide ultrathin coating on the surface of a non-nickel-based metal material, comprising the following steps:

[0012] 1) Soak or polish non-nickel-based metal materials in acid to remove possible surface contamination and spontaneous oxide layer, then ultrasonically wash them with ethanol and deionized water in sequence, and dry them as working electrodes to be reconstructed.

[0013] 2) Prepare an electrolyte by dissolving urea, water-soluble nickel metal salt, sodium hydroxide or potassium hydroxide in deionized water. The concentrations of each component in the electrolyte are as follows: urea: 0.01-1 mol / L, water-soluble nickel metal salt: 0.001-0.1 mol / L, sodium hydroxide or potassium hydroxide: 0.001-5 mol / L.

[0014] 3) Place the non-nickel-based metal material treated in step 1) into the solution prepared in step 2) containing urea and Ni. 2+ In an ion-ion electrolyte, it was used as the working electrode to be reconstructed and subjected to cyclic voltammetric electrochemical treatment.

[0015] 4) The non-nickel-based metal material after reconstruction in step 3) is cleaned with deionized water and then air-blown and dried to form a heat-resistant and corrosion-resistant urea-modified nickel-based hydroxide ultrathin coating on the surface of the non-nickel-based metal material.

[0016] Furthermore, the thickness of the urea-modified nickel-based hydroxide ultrathin coatings obtained by technical solutions 1 and 2 is 2-4 nanometers.

[0017] Furthermore, the main component of the coating described in technical solutions 1 and 2 is nickel-based hydroxide (Ni(OH)2), and the anchoring modified molecule is urea molecule. In the coating, the amino group of the urea molecule is bonded to the hydroxyl group on the surface of the nickel-based hydroxide through hydrogen bonds, and the carbonyl group of the urea molecule is bonded to the Ni group in the nickel-based hydroxide. 2+ Stable anchoring is achieved through nucleophilic coordination interactions.

[0018] The applicant discovered through research that during the electrochemical treatment process, when the voltage exceeds 1.3V, urea electro-oxidation is induced, thus protecting the further penetration of the electrolyte on the metal surface and facilitating the formation of a uniform nanoscale coating. Based on the above research, the cyclic voltammetry electrochemical treatment described in technical solutions 1 and 2 includes cyclic voltammetry scanning within a voltage range of 1.0 to 1.5V vs. RHE (relative to the reversible hydrogen electrode), with 5 to 20 cycles and an electrochemical scan rate of 1 to 100 mV / s.

[0019] Furthermore, the acid mentioned in step 1 of technical solutions 1 and 2 is selected from nitric acid, hydrochloric acid, sulfuric acid, and hydrofluoric acid.

[0020] Furthermore, the electrolytes prepared in step 2) of both technical solution 1 and technical solution 2 are alkaline electrolytes containing urea with a pH of 7.5-14. The electrolyte in technical solution 2 also contains Ni. 2+ .

[0021] Furthermore, in technical solution 2, the non-nickel-based metal material is made of pure Cu, Mg, Al, Fe, Co, Mn, In, Zn, and alloys thereof in any proportion.

[0022] Furthermore, in technical solution 2, the metallic nickel salt is nickel chloride, nickel nitrate, or nickel acetate.

[0023] This invention provides an electrochemical method for preparing a urea-modified nickel-based hydroxide coating on a metal substrate. The coating is nanometer-thick and highly dense. The urea-modified nickel-based hydroxide coating exhibits good electrostatic repulsion, resistance to various ionic corrosions, and high-temperature oxidation resistance, effectively blocking the penetration of corrosive ions, including CO32-. 2- SO4 2- NO3 - Cl - ,ClO - The corrosive environment has a pH value of 4 to 14; and it is low in cost and can significantly extend the service life of metal substrates in harsh chemical environments such as marine, chemical or high-temperature environments.

[0024] Beneficial Effects: This invention utilizes the nucleophilic interaction between the carbonyl oxygen in urea molecules and metallic nickel in nickel-based hydroxides to achieve tight bonding and anchoring, enhancing the thermal stability of the coating. Simultaneously, the amino hydrogen in urea molecules forms hydrogen bonds with the oxygen in nickel-based hydroxides, constituting a dense molecular modification layer. This molecular layer effectively blocks the penetration of various corrosive ions through Coulomb repulsion. Crucially, in the electrochemical preparation method of this invention, urea molecules undergo an electrochemical oxidation reaction at the anode, significantly suppressing the problem of deep peroxidation of the substrate surface caused by high voltage, thus more conducive to the formation of a uniform and dense nanoscale hydroxide protective layer.

[0025] In summary, this invention constructs a nanoscale uniform coating on a metal substrate using an electrochemical method and significantly improves the substrate's resistance to thermal and chemical corrosion by utilizing the anchoring mechanism of urea molecules (synergistic effect of nucleophilic interaction and hydrogen bonding), with broad application prospects. Compared with existing technologies, the advantages of this invention are: (1) Environmentally friendly and low-cost: It abandons the traditional alloying method that requires the addition of non-environmentally friendly metals such as chromium and molybdenum, and adopts urea molecules to modify nickel-based hydroxides. The process is simple, environmentally friendly, and low-cost, and easy to scale up. (2) Excellent performance: The ultra-thin coating is firmly bonded to the substrate. Urea molecules form a strong interaction with hydroxides through multiple mechanisms (nucleophilic anchoring and hydrogen bond network), giving the coating excellent and stable heat resistance and chemical corrosion resistance, suitable for harsh environments such as marine, chemical and high-temperature environments. (3) Mechanism innovation: It reveals a new mechanism by which organic molecules (urea) synergistically modify inorganic hydroxides through nucleophilic interaction and hydrogen bonding, providing new ideas and theoretical support for achieving high heat resistance and corrosion resistance protective coatings. Attached Figure Description

[0026] Figure 1 The current-voltage relationship (CV diagram) during the cyclic voltammetric scan electrochemical treatment in step 3) of Example 1 is shown.

[0027] Figure 2 (a) is the N1s X-ray photoelectron spectroscopy (XPS) depth profile of the nickel-based metal material with a urea molecule modified nickel hydroxide surface, i.e., a heat-resistant and corrosion-resistant urea-modified ultrathin coating (urea@Ni(OH)2 coating) prepared in Example 1, which proves that the thickness of the urea@Ni(OH)2 coating is 3nm.

[0028] Figure 2 (b) is the Ni 2p XPS depth profile of the urea@Ni(OH)2 coating prepared in Example 1.

[0029] Figure 2 (c) Transmission electron microscope (TEM) image of the urea@Ni(OH)2 coating prepared in Example 1 at the 50 nm scale.

[0030] Figure 2 (d) is a transmission electron microscope (TEM) image of the urea@Ni(OH)2 coating prepared in Example 1 at the 10 nm scale. The curve on the right is the electron energy loss spectrum of the elements contained in the coating, which proves that the main components of the urea@Ni(OH)2 coating are urea and Ni(OH)2.

[0031] Figure 2 (e) is a high-angle annular dark field image (HAADF) of the urea@Ni(OH)2 coating prepared in Example 1 and its Ni element distribution image (where the Pt element comes from the Pt deposition layer, which is introduced to stabilize the cross-section of the urea@Ni(OH)2 coating during the ion beam thinning process).

[0032] Figure 2 (f), Figure (g), Figure 2 (h) Figure 2 (i) TEM images of the Ni(OH)2 coatings prepared in Comparative Examples 1-2 after in-situ heating at 300°C for 0 seconds, 150 seconds, 300 seconds, and 400 seconds, respectively.

[0033] Figure 2 (j), Figure (k), Figure 2 (l) Figure 2 (m) are TEM images of the urea@Ni(OH)2 coating prepared in Example 1 after in-situ heating at 300°C for 0 seconds, 6 seconds, 14 seconds, and 400 seconds.

[0034] Figure 3 Thermogravimetric analysis (TGA) diagrams of the urea@Ni(OH)2 coating prepared in Example 1 and the Ni(OH)2 coating prepared in Comparative Examples 1-2 are shown.

[0035] Figure 4 (a) is a scanning electron microscope (SEM) image of the Ni foil obtained by step (1) in Comparative Example 1-1.

[0036] Figure 4 (b) is a SEM image of the Ni foil treated in step 1) of Comparative Example 1-1 after ultrasonic immersion in 1M KOH solution for 2 hours.

[0037] Figure 4 (c) is a SEM image of the Ni foil treated in step 1) of Comparative Example 1-1 after ultrasonic soaking in 1M KOH solution for 2 hours and then heating to 300℃ and holding for 8 hours.

[0038] Figure 4 (d) SEM images of Ni(OH)2 coatings prepared on Ni foil substrates in Comparative Examples 1-2.

[0039] Figure 4(e) is a SEM image of the Ni(OH)2 coating prepared on the Ni foil substrate in Comparative Examples 1-2 after ultrasonic immersion in 1M KOH solution for 2 hours.

[0040] Figure 4 (f) is a SEM image of Ni(OH)2 prepared in Comparative Examples 1-2 after ultrasonic soaking in 1M KOH solution for 2 hours and then heating to 300℃ and holding for 8 hours.

[0041] Figure 4 (g) is a SEM image of the urea@Ni(OH)2 coating prepared in Example 1.

[0042] Figure 4 (h) is a SEM image of the urea@Ni(OH)2 coating prepared in Example 1 after ultrasonic immersion in 1M KOH solution for 2 hours.

[0043] Figure 4 (i) is a SEM image of the urea@Ni(OH)2 coating prepared in Example 1 after ultrasonic immersion in 1M KOH solution for 2 hours and then heating to 300℃ and holding for 8 hours.

[0044] Figure 4 The curves in (a)-(i) are the corresponding Raman spectra.

[0045] Figure 5 (a) is a CV diagram showing the current-voltage relationship during the cyclic voltammetric electrochemical treatment in step 3) of Comparative Examples 1-2.

[0046] Figure 5 (b) is the Ni 2p X-ray photoelectron spectroscopy (XPS) spectrum of the Ni(OH)2 coating obtained in step 3) of Comparative Examples 1-2.

[0047] Figure 5 (c) is the O1s XPS spectrum of Ni(OH)2 obtained in step 3) of Comparative Example 1-2.

[0048] Figure 6 a shows the thermogravimetric analysis (TGA) diagrams of urea@NiCu(OH)2 prepared in Example 2 and NiCu(OH)2 prepared in Comparative Example 2-1.

[0049] Figure 6 b shows the thermogravimetric analysis (TGA) diagrams of the urea@NiFe(OH)2 coating prepared in Example 3 and the NiFe(OH)2 coating prepared in Comparative Example 3-1.

[0050] Figure 6c shows the thermogravimetric analysis (TGA) diagrams of the urea@NiCo(OH)2 coating prepared in Example 4 and the NiCo(OH)2 coating prepared in Comparative Example 4-1.

[0051] Figure 6 d shows the thermogravimetric analysis (TGA) diagrams of the urea@NiMn(OH)2 coating prepared in Example 5 and the NiMn(OH)2 coating prepared in Comparative Example 5-1;

[0052] Figure 6 e represents the thermogravimetric analysis (TGA) diagrams of the urea@NiIn(OH)2 coating prepared in Example 6 and the NiIn(OH)2 coating prepared in Comparative Example 6-1.

[0053] Figure 6 f is a thermogravimetric analysis (TGA) diagram of the urea@NiMg(OH)2 coating prepared in Example 7 and the NiMg(OH)2 coating prepared in Comparative Example 7-1.

[0054] Figure 6 g represents the thermogravimetric analysis (TGA) diagrams of the urea@NiZn(OH)2 coating prepared in Example 8 and the NiZn(OH)2 coating prepared in Comparative Example 8-1;

[0055] Figure 6 h represents the thermogravimetric analysis (TGA) diagrams of the urea@NiAl(OH)2 coating prepared in Example 9 and the NiAl(OH)2 coating prepared in Comparative Example 9-1.

[0056] Figure 6 i represents the urea@NiFe(OH)2@Fe prepared in Example 10. 64 Ni 36 Coating and NiFe(OH)2@Fe prepared in Comparative Example 10-1 64 Ni 36 Thermogravimetric analysis (TGA) diagram of the coating.

[0057] Figure 6 j represents the urea@NiMgAl(OH)2@Mg prepared in Example 11. 92 Al8 coating and NiMgAl(OH)2@Mg prepared in Comparative Example 11-1 92 Thermogravimetric analysis (TGA) diagram of Al8 coating.

[0058] Figure 6 k represents the urea@NiCuZn(OH)2@Cu prepared in Example 12. 65 Zn 35 Coating and NiCuZn(OH)2@Cu prepared in Comparative Example 12-1 65 Zn 35Thermogravimetric analysis (TGA) diagram of the coating. Detailed Implementation

[0059] The technical solutions in the embodiments of the present invention will be described in further detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0060] The coating preparation conditions used in this invention are as follows:

[0061] For nickel-based metal materials, an electrolyte is prepared by dissolving urea, sodium hydroxide, or potassium hydroxide in deionized water. The concentrations of each component in the electrolyte are: urea: 0.01–1 mol / L, sodium hydroxide or potassium hydroxide: 0.001–5 mol / L, sodium hydroxide or potassium hydroxide: 0.001–5 mol / L.

[0062] For non-nickel-based metal materials, an electrolyte is prepared by dissolving urea, water-soluble nickel metal salt, sodium hydroxide or potassium hydroxide in deionized water. The concentrations of each component in the electrolyte are as follows: urea: 0.01–1 mol / L, water-soluble nickel metal salt: 0.001–0.1 mol / L, sodium hydroxide or potassium hydroxide: 0.001–5 mol / L.

[0063] A three-electrode system was used for CV cyclic scanning of each embodiment and comparative example. A platinum sheet with a purity higher than 99.99% was used as the counter electrode, and a nickel foil with a purity of 99.99% was used as the working electrode. Saturated Ag / AgCl was used as the reference electrode. The testing instrument was a Shanghai Chenhua CHI 660e electrochemical workstation. All test voltage values ​​were converted to the voltage values ​​relative to the standard hydrogen electrode.

[0064] Example 1

[0065] (1) Soak the nickel foil in 0.1 mol / L dilute hydrochloric acid for 0.5 hours, then clean it by ultrasonication, wash it with ethanol and deionized water for 10 minutes each, and then blow it dry with air for later use.

[0066] (2) Weigh 1 mol / L potassium hydroxide and 0.2 mol / L urea, dissolve them in 150 mL of deionized water, and prepare an electrolyte solution;

[0067] (3) The nickel foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 20 cycles of cyclic voltammetry treatment in the voltage range of 1.0V to 1.5V to obtain a nickel foil with a urea molecule modified nickel hydroxide coating (denoted as urea@Ni(OH)2@Ni).

[0068] (4) The nickel foil with urea molecule modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0069] The nickel foil with urea-modified nickel hydroxide coating obtained in step (4) was tested for heat and corrosion resistance using methods such as surface layer XPS, Raman, TEM analysis, in-situ TEM thermal stability structure analysis, thermogravimetric analysis, and comparison of microstructure SEM images after ultrasonic immersion corrosion in 1M KOH solution for 2 hours and after heat preservation at 300℃ for 8 hours. The results are as follows:

[0070] like Figure 1 As shown, after the CV cycle scan implemented in step (3), a stable electrochemical reconstruction layer is formed on the surface of the nickel foil in potassium hydroxide + urea solution.

[0071] like Figure 2 As shown in (a), XPS analysis of the sample obtained in step (4) shows that the stable electrochemical reconstruction layer formed on the surface of the nickel foil is a 3nm Ni(OH)2 coating urea@Ni(OH)2 adsorbed by urea.

[0072] like Figure 2 (b) Figure 2 (c) Figure 2 As shown in (d), TEM electron microscopy analysis of the sample obtained in step (4) shows that the electrochemically stable urea adsorbed Ni(OH)2 layer formed on the nickel foil surface is a uniform, dense, ultrathin urea@Ni(OH)2 coating with a thickness of 3 nm.

[0073] like Figure 2 As shown in (f), the in-situ heat treatment TEM electron microscopy analysis of the sample obtained in step (4) shows that the urea@Ni(OH)2 coating formed on the nickel foil surface can maintain structural stability and has good heat resistance during heat treatment at 300℃.

[0074] like Figure 3 As shown, thermogravimetric analysis of the sample obtained in step (4) shows that the urea@Ni(OH)2 coating formed on the nickel foil surface can effectively isolate water and oxygen, suppress mass loss, and has good corrosion resistance.

[0075] like Figure 4 (g) Figure 4 (h) Figure 4 As shown in (i), SEM and Raman analysis of the sample obtained after step (4) showed that the urea@Ni(OH)2 layer formed on the nickel foil surface can effectively protect the nickel foil surface and has excellent heat resistance and corrosion resistance.

[0076] Comparative Example 1-1

[0077] (1) Soak the nickel foil in 0.1 mol / L dilute nitric acid for 1 hour, then clean it by ultrasonic cleaning, wash it with ethanol and deionized water for 10 minutes each, and dry it by air blowing (denoted as Ni);

[0078] (2) The nickel foil obtained in step (1) was ultrasonically etched in 1M KOH solution for 2 hours and kept at 300℃ for 8 hours. The corrosion resistance of the coating was then tested using the same method as in Example 1. The results are as follows: Figure 4 (a) Figure 4 (b) Figure 4 As shown in (c), SEM and Raman analysis of the sample obtained after step (2) of Comparative Example 1-1 showed that the surface of the nickel foil underwent significant structural changes after corrosion and heat treatment, indicating that the nickel foil itself does not have heat resistance and corrosion resistance.

[0079] Comparative Examples 1-2

[0080] (1) Soak the nickel foil in 2 mol / L dilute hydrochloric acid for 0.5 hours, then clean it by ultrasonication, wash it with ethanol and deionized water for 10 minutes each, and dry it by air blowing for later use.

[0081] (2) Weigh 1 mol / L potassium hydroxide, dissolve it in 100 mL of deionized water, and prepare an electrolyte solution;

[0082] (3) Electrochemically treat the nickel foil electrode from step (1) in the electrolyte obtained in step (2), and perform 10 cycles of cyclic voltammetry treatment in the voltage range of 1V to 1.5V to form a nickel hydroxide coating on the surface of the nickel foil (the coating is denoted as Ni(OH)2, and the whole sample is denoted as Ni(OH)2@Ni).

[0083] (4) The nickel foil with nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use;

[0084] The coated nickel foil obtained in step (4) was ultrasonically etched in 1M KOH solution for 2 hours and kept at 300℃ for 8 hours. The heat resistance and corrosion resistance of the coating were tested using the same method as in Example 1. The results are as follows.

[0085] like Figure 5 As shown in (a), after the CV cycle scan performed in step (3), a Ni(OH)2 coating is formed on the surface of the nickel foil and a Ni(OH)2 / NiOOH redox cycle occurs.

[0086] like Figure 5As shown in (b), XPS analysis of the samples obtained after step (4) of Comparative Examples 1-2 revealed a thick 12 nm electrochemical reconstruction layer formed on the surface of the nickel foil, which was mainly composed of Ni(OH)2.

[0087] like Figure 2 As shown in (e), the in-situ heat treatment TEM analysis of the samples obtained after step (4) of Comparative Examples 1-2 showed that the Ni(OH)2 coating gradually transformed into NiOOH during the heat treatment at 300℃ and did not have heat resistance.

[0088] like Figure 3 As shown, thermogravimetric analysis of the samples obtained after step (4) of Comparative Examples 1-2 showed that the Ni(OH)2 coating had a large mass loss, indicating that it could not isolate water and oxygen and did not have corrosion resistance.

[0089] like Figure 4 (d) Figure 4 (e) Figure 4 As shown in (f), SEM and Raman analysis of the samples obtained in step (4) of Examples 1-2 showed that the surface of the nickel foil after corrosion and heat treatment underwent significant structural changes, indicating that the Ni(OH)2 coating does not have heat resistance and corrosion resistance.

[0090] Example 2

[0091] (1) Soak the Cu foil in 0.2 mol / L dilute nitric acid for 1 minute, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0092] (2) Weigh 0.1 mol / L nickel nitrate, 2 mol / L potassium hydroxide and 0.3 mol / L urea, dissolve them in 150 mL of deionized water to prepare an electrolyte;

[0093] (3) The Cu foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 10 cycles of cyclic voltammetry treatment in the voltage range of 1.0V to 1.5V to obtain a sample with a urea-modified nickel hydroxide coating (denoted as urea@NiCu(OH)2).

[0094] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0095] The thermal stability of the urea@NiCu(OH)2 sample with urea molecule-modified nickel hydroxide coating obtained in step (4) was investigated by thermogravimetric analysis. The results are as follows:

[0096] like Figure 6As shown in (a), thermogravimetric analysis of the sample obtained in step (4) shows that the urea@NiCu(OH)2 coating formed on the copper foil surface can effectively isolate water and oxygen, suppress mass loss, and has good heat resistance and corrosion resistance.

[0097] Comparative Example 2-1

[0098] (1) Soak the Cu foil in 0.2 mol / L dilute nitric acid for 1 minute, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0099] (2) Weigh 1.5 mol / L potassium hydroxide and 0.4 mol / L urea, dissolve them in 100 mL of deionized water, and prepare an electrolyte solution;

[0100] (3) The foil electrode from step (1) is subjected to electrochemical treatment in the electrolyte obtained in step (2), and cyclic voltammetry is performed for 10 cycles in the voltage range of 1V to 1.5V to obtain a nickel hydroxide coating with urea molecule modified (denoted as NiCu(OH)2).

[0101] (4) The nickel-based hydroxide coating sample obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use;

[0102] The thermal stability of the NiCu(OH)2 obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0103] like Figure 6 As shown in (a), thermogravimetric analysis of the sample obtained in step (4) shows that the NiCu(OH)2 layer formed on the copper foil surface has a large mass loss, indicating that it cannot isolate water and oxygen and does not have corrosion resistance.

[0104] Example 3

[0105] (1) Soak the Fe foil in 0.05 mol / L dilute nitric acid for 1 minute, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0106] (2) Weigh 0.05 mol / L nickel nitrate, 1.5 mol / L potassium hydroxide and 0.25 mol urea, dissolve them in 200 mL of deionized water to prepare an electrolyte;

[0107] (3) The Fe foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 15 cycles of cyclic voltammetry in the voltage range of 1V to 1.5V to obtain a sample with a urea-modified nickel hydroxide coating (denoted as urea@NiFe(OH)2).

[0108] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0109] The thermal stability of the urea@NiFe(OH)2 sample with urea molecularly modified nickel hydroxide coating obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0110] like Figure 6 As shown in (b), thermogravimetric analysis of the sample obtained in step (4) shows that the urea@NiFe(OH)2 coating formed on the iron foil surface can effectively isolate water and oxygen, suppress mass loss, and has good heat resistance and corrosion resistance.

[0111] Comparative Example 3-1

[0112] (1) Soak the Fe foil in 0.05 mol / L dilute nitric acid for 1 minute, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0113] (2) Weigh 2.5 mol / L potassium hydroxide and 0.1 mol / L urea, dissolve them in 150 mL of deionized water, and prepare an electrolyte solution;

[0114] (3) The Fe foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 15 cycles of cyclic voltammetry in the voltage range of 1V to 1.5V to obtain a sample with a urea molecule modified nickel hydroxide coating (denoted as NiFe(OH)2).

[0115] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0116] The thermal stability of the NiFe(OH)2 sample obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0117] like Figure 6 As shown in (b), thermogravimetric analysis of the sample obtained in step (4) shows that the NiFe(OH)2 layer formed on the iron foil surface has a large mass loss, indicating that it cannot isolate water and oxygen and does not have corrosion resistance.

[0118] Example 4

[0119] (1) Soak the Co foil in 0.1 mol / L dilute nitric acid for 1 minute, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0120] (2) Weigh 0.05 mol / L nickel nitrate, 0.5 mol / L potassium hydroxide and 0.08 mol / L urea, dissolve them in 500 mL of deionized water to prepare an electrolyte;

[0121] (3) The Co foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 20 cycles of cyclic voltammetry in the voltage range of 1V to 1.5V to obtain a sample with a urea-modified nickel hydroxide coating (denoted as urea@NiCo(OH)2).

[0122] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0123] The thermal stability of the urea@NiCo(OH)2 sample obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0124] As shown in the figure Figure 6 As shown in (c), thermogravimetric analysis of the sample obtained in step (4) shows that the urea@NiCo(OH)2 coating formed on the surface of the cobalt foil can effectively isolate water and oxygen, suppress mass loss, and has good heat resistance and corrosion resistance.

[0125] Comparative Example 4-1

[0126] (1) Soak the Co foil in 0.1 mol / L dilute nitric acid for 1 minute, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0127] (2) Weigh 0.8 mol / L potassium hydroxide and 0.3 mol / L urea, dissolve them in 100 mL of deionized water, and prepare an electrolyte solution;

[0128] (3) The Co foil electrode from step (1) is subjected to electrochemical treatment in the electrolyte obtained in step (2), and cyclic voltammetry is performed for 20 cycles in the voltage range of 1V to 1.5V to obtain a nickel-based hydroxide coating sample (denoted as NiCo(OH)2).

[0129] (4) The nickel-based hydroxide coating sample obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use;

[0130] The thermal stability of NiCo(OH)2 obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0131] like Figure 6As shown in (c), thermogravimetric analysis of the sample obtained in step (4) shows that the NiCo(OH)2 layer formed on the surface of the cobalt foil has a large mass loss, indicating that it cannot isolate water and oxygen and does not have corrosion resistance.

[0132] Example 5

[0133] (1) Soak the Mn foil in 0.08 mol / L dilute nitric acid for 1 minute, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0134] (2) Weigh 0.02 mol / L nickel nitrate, 0.5 mol / L potassium hydroxide and 1 mol / L urea, dissolve them in 150 mL of deionized water to prepare an electrolyte;

[0135] (3) The Mn foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 20 cycles of cyclic voltammetry in the voltage range of 1V to 1.5V to obtain a sample with a urea-modified nickel hydroxide coating (denoted as urea@NiMn(OH)2).

[0136] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0137] The thermal stability of urea@NiMn(OH)2 obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0138] like Figure 6 As shown in (d), thermogravimetric analysis of the sample obtained in step (4) shows that the urea@NiMn(OH)2 coating formed on the surface of manganese foil can effectively isolate water and oxygen, suppress mass loss, and has good heat resistance and corrosion resistance.

[0139] Comparative Example 5-1

[0140] (1) Soak the Mn foil in 0.08 mol / L dilute nitric acid for 1 minute, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0141] (2) Weigh 3 mol / L potassium hydroxide and 1 mol / L urea, dissolve them in 100 mL of deionized water, and prepare an electrolyte solution.

[0142] (3) The Mn foil electrode from step (1) is subjected to electrochemical treatment in the electrolyte obtained in step (2), and cyclic voltammetry is performed for 20 cycles in the voltage range of 1V to 1.5V to obtain a nickel-based hydroxide coating sample (denoted as NiMn(OH)2).

[0143] (4) The nickel-based hydroxide coating sample obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use;

[0144] The thermal stability of the NiMn(OH)2 sample obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0145] like Figure 6 As shown in (d), thermogravimetric analysis of the sample obtained in step (4) shows that the NiMn(OH)2 layer formed on the surface of the manganese foil has a large mass loss, indicating that it cannot isolate water and oxygen and does not have corrosion resistance.

[0146] Example 6

[0147] (1) Soak the In foil in 0.05 mol / L dilute nitric acid for 1 minute, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0148] (2) Weigh 0.025 mol / L nickel nitrate, 1 mol / L potassium hydroxide and 0.3 mol / L urea, dissolve them in 150 mL of deionized water to prepare an electrolyte;

[0149] (3) The In foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 20 cycles of cyclic voltammetry in the voltage range of 1V to 1.5V to obtain a sample with a urea-modified nickel hydroxide coating (denoted as urea@NiIn(OH)2).

[0150] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0151] The thermal stability of the urea@NiIn(OH)2 sample obtained in step (4) was investigated by thermogravimetric analysis. The results are as follows:

[0152] As shown in the figure Figure 6 As shown in (e), thermogravimetric analysis of the sample obtained in step (4) shows that the urea@NiIn(OH)2 coating formed on the surface of the indium foil can effectively isolate water and oxygen, suppress mass loss, and has good heat resistance and corrosion resistance.

[0153] Comparative Example 6-1

[0154] (1) Soak the In foil in 0.05 mol / L dilute nitric acid for 1 minute, then clean it by ultrasonic cleaning, wash it with ethanol and deionized water for 2 minutes each, and blow it dry with air for later use.

[0155] (2) Weigh 0.3 mol / L potassium hydroxide and 0.05 mol / L urea, dissolve them in 100 mL of deionized water, and prepare an electrolyte solution;

[0156] (3) The In foil electrode from step (1) is subjected to electrochemical treatment in the electrolyte obtained in step (2), and cyclic voltammetry is performed for 20 cycles in the voltage range of 1V to 1.5V to obtain a nickel-based hydroxide coating sample (denoted as NiIn(OH)2).

[0157] (4) The nickel-based hydroxide coating sample obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use;

[0158] The thermal stability of the NiIn(OH)2 sample obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0159] like Figure 6 As shown in (e), thermogravimetric analysis of the sample obtained in step (4) shows that the NiIn(OH)2 layer formed on the surface of the indium foil has a large mass loss, indicating that it cannot isolate water and oxygen and does not have corrosion resistance.

[0160] Example 7

[0161] (1) Soak the Mg foil in 0.001 mol / L dilute nitric acid for 30 seconds, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0162] (2) Weigh 0.2 mol / L nickel nitrate, 1 mol potassium hydroxide and 0.1 mol / L urea, dissolve them in 200 mL of deionized water to prepare an electrolyte;

[0163] (3) The Mg foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 10 cycles of cyclic voltammetry in the voltage range of 1V to 1.5V to obtain a sample with a urea-modified nickel hydroxide coating (denoted as urea@NiMg(OH)2).

[0164] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0165] The thermal stability of the urea@NiMg(OH)2 sample obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0166] like Figure 6 As shown in (f), thermogravimetric analysis of the sample obtained in step (4) shows that the urea@NiMg(OH)2 coating formed on the magnesium foil surface can effectively isolate water and oxygen, suppress mass loss, and has good heat resistance and corrosion resistance.

[0167] Comparative Example 7-1

[0168] (1) Soak the Mg foil in 0.001 mol / L dilute nitric acid for 30 seconds, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0169] (2) Weigh 1 mol / L potassium hydroxide and 0.015 mol / L urea, dissolve them in 200 mL of deionized water, and prepare an electrolyte solution;

[0170] (3) The Mg foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2), and cyclic voltammetry is performed for 10 cycles in the voltage range of 1V to 1.5V to obtain a nickel hydroxide coating sample (denoted as NiMg(OH)2).

[0171] (4) The sample with nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use;

[0172] The thermal stability of the NiMg(OH)2 sample obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0173] like Figure 6 As shown in (f), thermogravimetric analysis of the sample obtained in step (4) shows that the NiMg(OH)2 layer formed on the magnesium foil surface has a large mass loss, indicating that it cannot isolate water and oxygen and does not have corrosion resistance.

[0174] Example 8

[0175] (1) Soak the Zn foil in 0.0005 mol / L dilute nitric acid for 5 seconds, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0176] (2) Weigh 0.3 mol / L nickel nitrate, 2 mol / L potassium hydroxide and 0.6 mol / L urea, dissolve them in 200 mL of deionized water to prepare an electrolyte;

[0177] (3) The Zn foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 20 cycles of cyclic voltammetry treatment in the voltage range of 1V to 1.5V to obtain a sample with a urea-modified nickel hydroxide coating (denoted as urea@NiZn(OH)2).

[0178] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0179] The thermal stability of the urea@NiZn(OH)2 sample obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0180] like Figure 6 As shown in (g), thermogravimetric analysis of the sample obtained in step (4) shows that the urea@NiZn(OH)2 coating formed on the zinc foil surface can effectively isolate water and oxygen, suppress mass loss, and has good heat resistance and corrosion resistance.

[0181] Comparative Example 8-1

[0182] (1) Soak the Zn foil in 0.0005 mol / L dilute nitric acid for 5 seconds, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0183] (2) Weigh 0.8 mol / L potassium hydroxide and 0.15 mol / L urea, dissolve them in 200 mL of deionized water, and prepare an electrolyte solution;

[0184] (3) The Zn foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 20 cycles of cyclic voltammetry in the voltage range of 1V to 1.5V to obtain a nickel hydroxide coating sample (denoted as NiZn(OH)2).

[0185] (4) The sample with nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use;

[0186] The thermal stability of the NiZn(OH)2 sample obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0187] like Figure 6 As shown in (g), thermogravimetric analysis of the sample obtained in step (4) shows that the NiZn(OH)2 layer formed on the zinc foil surface has a large mass loss, indicating that it cannot isolate water and oxygen and does not have corrosion resistance.

[0188] Example 9

[0189] (1) Soak the Al foil in 0.005 mol / L dilute nitric acid for 5 seconds, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0190] (2) Weigh 0.04 mol / L nickel nitrate, 0.9 mol / L potassium hydroxide and 0.01 mol / L urea, dissolve them in 200 mL of deionized water to prepare an electrolyte;

[0191] (3) The Al foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 20 cycles of cyclic voltammetry in the voltage range of 1V to 1.5V to obtain a sample with a urea-modified nickel hydroxide coating (denoted as urea@NiAl(OH)2).

[0192] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0193] The thermal stability of urea@NiAl(OH)2 obtained in step (4) was investigated by thermogravimetric analysis. The results are as follows:

[0194] like Figure 6 As shown in (h), thermogravimetric analysis of the sample obtained in step (4) shows that the urea@NiAl(OH)2 coating formed on the aluminum foil surface can effectively isolate water and oxygen, suppress mass loss, and has good heat resistance and corrosion resistance.

[0195] Comparative Example 9-1

[0196] (1) Soak the Al foil in 0.005 mol / L dilute nitric acid for 5 seconds, then clean it by ultrasonication, wash it with ethanol and deionized water for 2 minutes each, and dry it by air blowing for later use.

[0197] (2) Weigh 2.5 mol / L potassium hydroxide and 0.35 mol / L urea, dissolve them in 200 mL of deionized water, and prepare an electrolyte solution;

[0198] (3) The Al foil electrode from step (1) is electrochemically treated in the electrolyte obtained in step (2) and subjected to 20 cycles of cyclic voltammetry in the voltage range of 1V to 1.5V to obtain a nickel hydroxide coating sample (denoted as NiAl(OH)2).

[0199] (4) The sample with nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use;

[0200] The thermal stability of the NiAl(OH)2 sample obtained in step (4) was investigated by thermogravimetric analysis, and the results are as follows:

[0201] like Figure 6 As shown in (h), thermogravimetric analysis of the sample obtained in step (4) shows that the NiAl(OH)2 layer formed on the aluminum foil surface has a large mass loss, indicating that it cannot isolate water and oxygen and does not have corrosion resistance.

[0202] Example 10

[0203] (1) Fe 64 Ni36 The alloy foil is polished to remove the surface layer, then ultrasonically cleaned and washed with ethanol and deionized water for 2 minutes each, and then air-blown to dry for later use.

[0204] (2) Weigh 0.35 mol / L potassium hydroxide and 0.03 mol / L urea, dissolve them in 1000 mL of deionized water, and prepare an electrolyte solution;

[0205] (3) Take the Fe from step (1) 64 Ni 36 The alloy electrode was electrochemically treated in the electrolyte obtained in step (2), and cyclically voltammetrically treated for 10 cycles in the voltage range of 1V to 1.5V to obtain a sample with a urea-modified nickel hydroxide coating (denoted as urea@NiFe(OH)2@Fe). 64 Ni 36 ).

[0206] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0207] The urea@NiFe(OH)2@Fe obtained from step (4) 64 Ni 36 The thermal stability of the samples was investigated using thermogravimetric analysis, and the results are as follows:

[0208] like Figure 6 As shown in (i), thermogravimetric analysis of the sample obtained in step (4) indicates that in Fe... 64 Ni 36 urea@NiFe(OH)2@Fe formed on the alloy surface 64 Ni 36 The coating effectively isolates water and oxygen, inhibits mass loss, and has good heat and corrosion resistance.

[0209] Comparative Example 10-1

[0210] (1) Fe 64 Ni 36 The alloy foil is polished to remove the surface layer, then ultrasonically cleaned and washed with ethanol and deionized water for 2 minutes each, and then air-blown to dry for later use.

[0211] (2) Weigh 0.5 mol / L potassium hydroxide and 0.7 mol / L urea, dissolve them in 1000 mL of deionized water, and prepare an electrolyte solution;

[0212] (3) Take the Fe from step (1) 64 Ni 36The alloy electrode was electrochemically treated in the electrolyte obtained in step (2), and cyclically voltammetrically treated for 10 cycles in the voltage range of 1V to 1.5V to obtain a hydroxide coating sample (denoted as NiFe(OH)2@Fe). 64 Ni 36 ).

[0213] (4) The sample with hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use;

[0214] The NiFe(OH)2@Fe obtained from step (4) 64 Ni 36 The thermal stability of the samples was investigated using thermogravimetric analysis, and the results are as follows:

[0215] like Figure 6 As shown in (i), thermogravimetric analysis of the sample obtained in step (4) indicates that in Fe... 64 Ni 36 NiFe(OH)2@Fe formed on the surface of the alloy foil 64 The significant mass loss of the Ni3 layer indicates that it cannot isolate water and oxygen and lacks corrosion resistance.

[0216] Example 11

[0217] (1) Mg 92 The surface layer of the Al8 alloy foil was removed by grinding, and then it was ultrasonically cleaned and washed with ethanol and deionized water for 2 minutes each, and then air-blown to dry for later use.

[0218] (2) Weigh 0.025 mol / L nickel nitrate, 0.45 mol / L potassium hydroxide and 0.03 mol / L urea, dissolve them in 1000 mL of deionized water to prepare an electrolyte;

[0219] (3) Take the Mg from step (1) 92 The Al8 alloy electrode was electrochemically treated in the electrolyte obtained in step (2), and subjected to 20 cycles of cyclic voltammetry treatment in the voltage range of 1V to 1.5V to obtain a sample with a urea-modified nickel hydroxide coating (denoted as urea@NiMgAl(OH)2@Mg). 92 Al8).

[0220] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0221] The urea@NiMgAl(OH)2@Mg obtained from step (4) 92 The thermal stability of Al8 samples was investigated using thermogravimetric analysis, and the results are as follows:

[0222] like Figure 6 As shown in (j), thermogravimetric analysis of the sample obtained in step (4) indicates that in Mg 92 urea@NiMgAl(OH)2@Mg formed on the surface of Al8 alloy foil 92 Al8 coating can effectively isolate water and oxygen, inhibit mass loss, and has good heat resistance and corrosion resistance.

[0223] Comparative Example 11-1

[0224] (1) Mg 92 The surface layer of the Al8 alloy foil was removed by grinding, and then it was ultrasonically cleaned and washed with ethanol and deionized water for 2 minutes each, and then air-blown to dry for later use.

[0225] (2) Weigh 0.035 mol / L nickel nitrate, 0.75 mol / L potassium hydroxide and 0.05 mol / L urea, dissolve them in 1000 mL of deionized water to prepare an electrolyte;

[0226] (3) Take the Mg from step (1) 92 The Al8 alloy electrode was electrochemically treated in the electrolyte obtained in step (2), and cyclically voltammetrically treated for 20 cycles in the voltage range of 1V to 1.5V to obtain a hydroxide coating sample (denoted as NiMgAl(OH)2@Mg). 92 Al8).

[0227] (4) The sample with hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use;

[0228] The NiMgAl(OH)2@Mg obtained from step (4) 92 The thermal stability of Al8 samples was investigated using thermogravimetric analysis, and the results are as follows:

[0229] like Figure 6 As shown in (j), thermogravimetric analysis of the sample obtained in step (4) indicates that in Mg 92 NiMgAl(OH)2@Mg formed on the surface of Al8 alloy foil 92 The significant mass loss of the Al8 layer indicates that it cannot isolate water and oxygen and lacks corrosion resistance.

[0230] Example 12

[0231] (1) Cu 65 Zn 35 The alloy foil is polished to remove the surface layer, then ultrasonically cleaned and washed with ethanol and deionized water for 2 minutes each, and then air-blown to dry for later use.

[0232] (2) Weigh 0.025 mol / L nickel nitrate, 3 mol / L potassium hydroxide and 0.05 mol / L urea, dissolve them in 1000 mL of deionized water to prepare an electrolyte;

[0233] (3) Take the Cu from step (1) 65 Zn 35 The alloy electrode was electrochemically treated in the electrolyte obtained in step (2), and cyclically voltammetrically treated for 15 cycles in the voltage range of 1V to 1.5V to obtain a sample with a urea-modified nickel hydroxide coating (denoted as urea@NiCuZn(OH)2@Cu). 65 Zn 35 ).

[0234] (4) The sample with urea molecularly modified nickel hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use.

[0235] The urea@NiCuZn(OH)2@Cu obtained from step (4) 65 Zn 35 The thermal stability of the samples was investigated using thermogravimetric analysis, and the results are as follows:

[0236] like Figure 6 As shown in (k), thermogravimetric analysis of the sample obtained in step (4) indicates that in Cu... 65 Zn 35 urea@NiCuZn(OH)2@Cu formed on the surface of alloy foil 65 Zn 35 The coating effectively isolates water and oxygen, inhibits mass loss, and has good heat and corrosion resistance.

[0237] Comparative Example 12-1

[0238] (1) Cu 65 Zn 35 The alloy foil is polished to remove the surface layer, then ultrasonically cleaned and washed with ethanol and deionized water for 2 minutes each, and then air-blown to dry for later use.

[0239] (2) Weigh 0.025 mol / L nickel nitrate, 0.35 mol / L potassium hydroxide and 0.05 mol urea, dissolve them in 1000 mL of deionized water to prepare an electrolyte;

[0240] (3) Take the Cu from step (1) 65 Zn 35 The alloy electrode was electrochemically treated in the electrolyte obtained in step (2), and cyclically voltammetrically treated for 15 cycles in the voltage range of 1V to 1.5V to obtain a hydroxide-coated sample (denoted as NiCuZn(OH)2@Cu). 65 Zn35 ).

[0241] (4) The sample with hydroxide coating obtained in step (3) is washed with deionized water and then dried with nitrogen gas for later use;

[0242] The NiCuZn(OH)2@Cu obtained from step (4) 65 Zn 35 The thermal stability of the samples was investigated using thermogravimetric analysis, and the results are as follows:

[0243] like Figure 6 As shown in (k), thermogravimetric analysis of the sample obtained in step (4) indicates that in Cu... 65 Zn 35 NiCuZn(OH)2@Cu formed on the surface of the alloy foil 65 Zn 35 The significant loss of layer mass indicates that it cannot isolate water and oxygen and lacks corrosion resistance.

[0244] The urea-modified nickel-based hydroxide coating prepared in the above embodiments can meet the application requirements of materials in marine, chemical and high-temperature environments.

[0245] The contents not specifically described in the examples, such as ultrasonic cleaning with ethanol and deionized water, air purging and drying, and nitrogen drying, are all conventional processes.

[0246] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for forming a heat-resistant and corrosion-resistant urea-modified nickel-based hydroxide ultrathin coating on the surface of a nickel-based metal material, characterized in that, Includes the following steps: 1) Soak or polish the nickel-based metal material in acid to remove possible surface contamination and spontaneous oxide layer, then ultrasonically wash it with ethanol and deionized water in sequence and dry it for later use. 2) Dissolve urea, sodium hydroxide or potassium hydroxide in deionized water to prepare an electrolyte. The concentration of each component in the electrolyte is urea: 0.01-1 mol / L, sodium hydroxide or potassium hydroxide: 0.001-5 mol / L. 3) The nickel-based metal material treated in step 1) is placed in the urea-containing electrolyte prepared in step 2) and used as the working electrode to be reconstructed for cyclic voltammetry electrochemical treatment. 4) The nickel-based metal material after reconstruction in step 3) is cleaned with deionized water and then air-blown and dried to form a heat-resistant and corrosion-resistant urea-modified ultrathin coating on the nickel-based metal material.

2. The method as described in claim 1, characterized in that... The main component of the coating is nickel-based hydroxide (Ni(OH)2), and the anchoring modified molecule is urea molecule. In the coating, the amino group of the urea molecule is bonded to the hydroxyl group on the surface of the nickel-based hydroxide through hydrogen bonds, and the carbonyl group of the urea molecule is bonded to the Ni group in the nickel-based hydroxide. 2+ Stable anchoring is achieved through nucleophilic coordination interactions.

3. The method according to claim 1, characterized in that, The cyclic voltammetric electrochemical treatment includes cyclic voltammetric scanning in the voltage range of 1.0 to 1.5 V vs. RHE, with 5 to 20 cycles and an electrochemical scan rate of 1 to 100 mV / s.

4. A method for forming a heat-resistant and corrosion-resistant urea-modified nickel-based hydroxide ultrathin coating on the surface of a non-nickel-based metal material, characterized in that, Includes the following steps: 1) Soak or polish non-nickel-based metal materials in acid to remove possible surface contamination and spontaneous oxide layer, then ultrasonically wash them with ethanol and deionized water in sequence, and dry them as working electrodes to be reconstructed. 2) Prepare an electrolyte by dissolving urea, water-soluble nickel metal salt, sodium hydroxide or potassium hydroxide in deionized water. The concentrations of each component in the electrolyte are as follows: urea: 0.01-1 mol / L, water-soluble nickel metal salt: 0.001-0.1 mol / L, sodium hydroxide or potassium hydroxide: 0.001-5 mol / L. 3) Place the non-nickel-based metal material treated in step 1) into the solution prepared in step 2) containing urea and Ni. 2+ In the electrolyte of ions, it was used as the working electrode to be reconstructed and subjected to cyclic voltammetric electrochemical treatment; 4) The non-nickel-based metal material after reconstruction in step 3) is cleaned with deionized water and then air-blown and dried to form a heat-resistant and corrosion-resistant urea-modified ultrathin coating on the surface of the non-nickel-based metal material.

5. The method according to claim 1 or 4, characterized in that... The coating has a thickness of 2-4 nanometers.

6. The method according to claim 1 or 4, characterized in that... Step 2) The electrolyte to be prepared is an alkaline electrolyte with a pH of 7.5-14.

7. The method according to claim 4, characterized in that... The main component of the coating is nickel-based hydroxide (NiM(OH)2, where M is a non-nickel metal, and the anchoring modified molecule is urea molecule. In the coating, the amino group of the urea molecule is bonded to the hydroxyl group on the surface of the nickel-based hydroxide through hydrogen bonds, and the carbonyl group of the urea molecule is bonded to the Ni group in the nickel-based hydroxide. 2+ Stable anchoring is achieved through nucleophilic coordination interactions.

8. The method according to claim 4, characterized in that The non-nickel-based metal material is made of pure Cu, Mg, Al, Fe, Co, Mn, In, Zn, and alloys thereof in any proportion.

9. The method according to claim 5, characterized in that... The cyclic voltammetric electrochemical treatment includes cyclic voltammetric scanning in the voltage range of 1.0 to 1.5 V vs. RHE, with 5 to 20 cycles and an electrochemical scan rate of 1 to 100 mV / s.

10. The application of the method according to any one of claims 1 to 9 in the field of corrosion protection of metallic materials.

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