A wear-resistant organic polysilazane coating and a method for producing the same

Abstract

The application belongs to the technical field of coating preparation, and relates to a wear-resistant organic polysilazane coating and a preparation method thereof. Raw materials of Mo2TiAlC2 / g-C3N4 composite, MOFs / modified CeO2 composite and organic polysilazane are used to prepare mixed slurry, which is sprayed on the surface of a substrate to obtain the wear-resistant organic polysilazane coating. The Mo2TiAlC2 / g-C3N4 composite has excellent mechanical properties of Mo2TiAlC2 and high hardness of g-C3N4, and the wear resistance of the coating is improved through synergistic effect. The MOFs / modified CeO2 composite limits the modified CeO2 nanoparticles in the pores or anchors them on the surface by using the porous structure and high specific surface area of the MOFs material, and further solves the problem of nanoparticle agglomeration. Through the synergistic effect of multiple materials, the organic polysilazane coating exhibits excellent performance in wear resistance, hardness, adhesion and the like.

Description

Technical Field

[0001] This invention belongs to the field of coating preparation technology, specifically relating to a wear-resistant organopolysilazane coating and its preparation method. Background Technology

[0002] Friction and wear have a profound impact on global energy consumption, the environment, and economic development. In the context of rapid modern industrial development, materials face enormous challenges. From engine components to various transmission parts in machinery manufacturing, and precision components in electronic devices, wear not only reduces material lifespan and increases maintenance costs, but can also lead to equipment failure and safety issues in severe cases. Organopolysilazane coatings, with their unique molecular structure, exhibit superior performance. In terms of wear resistance, after curing, the coating forms a ceramic-like surface structure with high hardness, resisting various types of friction and wear. At high temperatures, it forms a more stable silicon-oxygen network structure, giving the coating excellent thermal stability. Simultaneously, organopolysilazane coatings can form a dense interface layer with the substrate through chemical bonding, effectively isolating the penetration of corrosive media such as water vapor, acids, and alkalis, greatly improving the material's corrosion resistance. It is widely used in harsh environments such as marine engineering and chemical equipment. However, some problems still need to be solved, such as poor material stability and high brittleness of the cured coating. Chinese Patent CN116970312B discloses a composite wear-resistant superhydrophobic coating and its application method. The coating consists of a top layer and a bottom layer. The bottom layer includes a mixture of fluorocarbon resin and epoxy resin. The top layer includes hydrophobically modified ceramic microspheres, hydrophobically modified nanocellulose coating the surface of the microspheres, and hydrophobically modified nanocellulose filling the interior of the microspheres. The hydrophobically modified nanocellulose fills the interior of the microspheres while also coating their surface, significantly reducing the surface energy of the coating. Furthermore, the combination of the hydrophobically modified ceramic microspheres and hydrophobically modified nanocellulose improves the roughness of the coating, and the two materials synergistically enhance the hydrophobicity and hardness of the coating. However, the above preparation process may lead to uneven coating of nanocellulose on the surface of the ceramic microspheres or insufficient filling inside, resulting in a decrease in coating performance. Summary of the Invention

[0003] To address at least one of the above problems, the present invention provides a method for preparing an abrasion-resistant organopolysilazane coating, comprising the following steps:

[0004] S100: Modified CeO2 nanoparticles are prepared using raw materials including CeO2 nanoparticles and silane coupling agents containing long chains of organosilicon.

[0005] S200, using raw materials including Mo2TiAlC2 nanosheets and g-C3N4, prepared a Mo2TiAlC2 / g-C3N4 composite.

[0006] S300, using modified CeO2 nanoparticles, metal salts and organic ligands as raw materials, prepared MOFs / modified CeO2 composites;

[0007] Using raw materials such as S400, Mo2TiAlC2 / g-C3N4 composite, MOFs / modified CeO2 composite, and organopolysilazane, a mixed slurry is prepared and sprayed onto the surface of a substrate to obtain the wear-resistant organopolysilazane coating.

[0008] Further, step S100 specifically includes: adding CeO2 nanoparticles to anhydrous ethanol, ultrasonically dispersing them, adding ethyl silicate, stirring for 10-30 min, adding a silane coupling agent containing a long organic silicon chain, stirring and mixing for 10-20 min, adding concentrated ammonia to adjust the pH to weakly alkaline, raising the temperature to 45-55℃ and reacting for 12-18 h, and obtaining modified CeO2 nanoparticles after washing, centrifugation, and drying.

[0009] Furthermore, the preparation method of the silane coupling agent containing long organic silicon chains is as follows: propyltriethoxysilane isocyanate, polydimethylsiloxane and chloroform are mixed and stirred at room temperature for 12-15 hours to obtain the silane coupling agent containing long organic silicon chains.

[0010] Furthermore, step S200 specifically includes:

[0011] S210. Mix HF, HCl and deionized water and add Mo2TiAlC2 powder. Stir at 30-35℃ for 2-4 hours. After the reaction is complete, centrifuge and wash to obtain the precipitate. Mix HF, HCl and deionized water and add LiCl. After ultrasonic dispersion, add the precipitate and stir for 10-15 hours. Centrifuge and then ultrasonically disperse for 10-20 minutes under ice bath conditions. Centrifuge to collect Mo2TiAlC2 nanosheets.

[0012] S220. Mo2TiAlC2 nanosheets were added to an aqueous solution of hydrogen peroxide and stirred at 55-65℃ for 2-4 hours. After washing and drying, they were dispersed with g-C3N4 in ethanol, ultrasonically dispersed, and stirred for 20-28 hours to obtain a mixture. After drying at 70-90℃, the temperature was raised to 280-320℃ under an inert atmosphere and kept at that temperature for 1.5-3.5 hours. After cooling, the Mo2TiAlC2 / g-C3N4 composite was obtained.

[0013] Furthermore, the preparation method of g-C3N4 is as follows: melamine is placed in a crucible, covered and placed in a muffle furnace and heated to 540-560℃, kept at that temperature for 3-5 hours, and then ground after natural cooling to obtain g-C3N4.

[0014] Further, step S300 specifically includes: dispersing modified CeO2 nanoparticles in methanol, sonicating for 20-40 min to form a suspension, adding a metal salt to the suspension, stirring for 20-30 min, adding an organic ligand, stirring for 10-20 min, transferring to a reaction vessel, raising the temperature to 100-120℃ and reacting for 18-24 h, after the reaction is completed, cooling to room temperature, and obtaining the MOFs / modified CeO2 composite by centrifugation, washing and drying.

[0015] Further, step S400 specifically includes: ultrasonically dispersing the MOFs / modified CeO2 composite and the Mo2TiAlC2 / g-C3N4 composite in a solvent, then adding an organopolysilazane and stirring for 20-40 min, followed by ultrasonication for 20-40 min to obtain a mixed slurry, spraying it onto the surface of the substrate, curing it at room temperature for 1-3 h, and then placing it in an oven for 2-4 h to obtain the wear-resistant organopolysilazane coating.

[0016] The present invention also provides a wear-resistant organopolysilazane coating, which is prepared by the method described in any of the above technical solutions for preparing a wear-resistant organopolysilazane coating.

[0017] The present invention has the following beneficial effects:

[0018] By reacting propyltriethoxysilane with polydimethylsiloxane to generate a long-chain silane coupling agent containing organosilicon, CeO2 nanoparticles were modified, improving their dispersibility in the organic matrix and enhancing interfacial adhesion. The prepared Mo2TiAlC2 / g-C3N4 composite combines the excellent mechanical properties of Mo2TiAlC2 with the high hardness of g-C3N4, synergistically improving the wear resistance of the coating. The MOFs / modified CeO2 composite utilizes the porous structure and high specific surface area of ​​MOFs to confine the modified CeO2 nanoparticles within the pores or anchor them on the surface, further addressing the issue of nanoparticle agglomeration. Simultaneously, the organic ligands of MOFs can form van der Waals forces or weak chemical bonds with the organic segments of organopolysilazane alkyl bodies, improving the interfacial adhesion between inorganic particles and the matrix and preventing filler detachment from the matrix during wear. The synergistic effect of multiple materials results in the preparation of organopolysilazane coatings exhibiting excellent performance in terms of wear resistance, hardness, and adhesion. Detailed Implementation

[0019] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0020] Organopolysilazane coatings are widely used due to their excellent high-temperature resistance, corrosion resistance, and good modeling properties. However, the wear resistance and mechanical strength of pure organopolysilazane coatings still need improvement, limiting their application in high-wear environments. Therefore, this invention provides a method for preparing a wear-resistant organopolysilazane coatings, comprising the following steps:

[0021] S100: Modified CeO2 nanoparticles are prepared using raw materials including CeO2 nanoparticles and silane coupling agents containing long chains of organosilicon.

[0022] S200, using raw materials including Mo2TiAlC2 nanosheets and g-C3N4, prepared a Mo2TiAlC2 / g-C3N4 composite.

[0023] S300, using modified CeO2 nanoparticles, metal salts and organic ligands as raw materials, prepared MOFs / modified CeO2 composites;

[0024] Using raw materials such as S400, Mo2TiAlC2 / g-C3N4 composite, MOFs / modified CeO2 composite, and organopolysilazane, a mixed slurry is prepared and sprayed onto the surface of a substrate to obtain the wear-resistant organopolysilazane coating.

[0025] Specifically, step S100 includes: adding CeO2 nanoparticles to anhydrous ethanol, ultrasonically dispersing for 30-60 min, adding ethyl silicate, stirring for 10-30 min, adding a silane coupling agent containing long-chain organosilicon, stirring and mixing for 10-20 min, adding concentrated ammonia to adjust the pH to 8-9, raising the temperature to 45-55℃ and reacting for 12-18 h, after the reaction is completed, washing with anhydrous ethanol and deionized water alternately 3-5 times, centrifuging at 6000-8000 r / min for 10-20 min, collecting the precipitate, and vacuum drying at 60-80℃ for 18-24 h to obtain modified CeO2 nanoparticles; wherein the mass ratio of CeO2 nanoparticles, ethyl silicate, and silane coupling agent containing long-chain organosilicon is 1:0.5-2:0.3-1, and the amount of CeO2 nanoparticles in anhydrous ethanol is 5-10 mg / mL.

[0026] The preparation method of the silane coupling agent containing long-chain organosilicon is as follows: propyltriethoxysilane, polydimethylsiloxane and chloroform are mixed and stirred at room temperature for 12-15 hours, and then distilled under reduced pressure at 40-50℃ to obtain the silane coupling agent containing long-chain organosilicon; wherein the mass ratio of propyltriethoxysilane, polydimethylsiloxane and chloroform is 4-8:10-15:12-20.

[0027] CeO2 nanoparticles possess high hardness and excellent chemical stability, allowing them to act as support points in coatings, reducing direct contact with the substrate surface during friction and lowering the wear rate by dispersing stress. Simultaneously, CeO2 nanoparticles exhibit redox properties; under the localized high temperatures generated by friction, they can release oxygen vacancies to repair micro-cracks on the coating surface, delaying coating failure. However, the surface of CeO2 nanoparticles is highly polar, and direct addition to organopolysilazanes can lead to uneven dispersion. Therefore, silane coupling agents are used for surface modification. However, the organic segments of traditional silane coupling agents are relatively short, and their compatibility with the long-chain structure of organopolysilazanes is limited. Therefore, propyltriethoxysilane is reacted with polydimethylsiloxane to generate a long-chain silane coupling agent containing organosilicon. Its molecular structure is similar to the main chain of organopolysilazane, which can reduce the interfacial tension between CeO2 nanoparticles and the organic matrix and reduce agglomeration. In addition, the long-chain organosilicon segments have good flexibility and can form an elastic buffer layer between CeO2 nanoparticles and the organic matrix. When the coating is subjected to friction or impact, the long-chain structure can absorb energy through chain segment movement, avoiding stress concentration that could lead to coating brittleness.

[0028] Specifically, step S200 includes:

[0029] S210. Mix HF, HCl, and deionized water in a volume ratio of 1:1-3:5-10, then add Mo2TiAlC2 powder to achieve a Mo2TiAlC2 powder concentration of 5-15 mg / mL. Stir at 30-35℃ for 2-4 hours. After the reaction is complete, centrifuge at 6000-8000 r / min for 10-15 min, wash with deionized water until neutral, and obtain the precipitate. Add HF, HCl, and deionized water in a volume ratio of 1:1-3:5-10. LiCl was used to make the concentration of LiCl 0.1-0.5 mol / L. After ultrasonic dispersion for 10-20 min, the precipitate was added. The mass ratio of precipitate to LiCl was 1:5-10. After stirring for 10-15 h, the mixture was centrifuged at 6000-8000 r / min. Then, it was ultrasonically dispersed for 10-20 min under ice bath conditions at a power of 300-500 W. Finally, it was centrifuged at 3000-5000 r / min for 5-10 min to collect Mo2TiAlC2 nanosheets.

[0030] S220. Add Mo2TiAlC2 nanosheets to a 30wt% hydrogen peroxide aqueous solution and stir at 55-65℃ for 2-4h. After washing with deionized water until neutral, dry at 60-80℃ for 4-6h. After drying, disperse it with g-C3N4 in ethanol, sonicate for 20-40min, and then stir at 30-40℃ for 20-28h to obtain a mixture. Dry the mixture at 70-90℃ and then sterilize it under an inert atmosphere at 5-100℃. The temperature was increased from 0℃ / min to 280-320℃, held for 1.5-3.5h, cooled to room temperature, and then ground to obtain the Mo2TiAlC2 / g-C3N4 composite. The amount of Mo2TiAlC2 nanosheets in hydrogen peroxide was 50-100mg / mL, the mass ratio of Mo2TiAlC2 nanosheets to g-C3N4 was 1:0.5-2, and the amount of g-C3N4 in ethanol was 15-30mg / mL.

[0031] The preparation method of g-C3N4 is as follows: melamine is placed in a crucible, covered and placed in a muffle furnace, and heated to 540-560℃ at a rate of 5-10℃ / min, kept at the temperature for 3-5h, and naturally cooled to room temperature. Then, it is ground through a 200-mesh sieve to obtain g-C3N4.

[0032] Mo2TiAlC2 material has high hardness and good ductility, and can maintain good stability at high temperatures. In this invention, Mo2TiAlC2 powder is prepared into nanosheets. Its sheet-like structure can directly resist the cutting action of abrasive particles through its high hardness, while its toughness buffers stress concentration, preventing the coating from aggravating wear due to brittle cracking. Simultaneously, the nano-thickness increases the specific surface area, providing more active sites for subsequent reactions. However, its two-dimensional structure is prone to interlayer slippage under frictional stress. Furthermore, melamine is pyrolyzed to form a graphite-like two-dimensional material, g-C3N4, which has good toughness but low hardness and cannot directly resist abrasive cutting. Therefore, Mo2TiAlC2 nanosheets are combined with g-C3N4. The layered structure of g-C3N4 forms a physical barrier network with the Mo2TiAlC2 nanosheets through hydroxyl-amino bonds. g-C3N4 can restrict the interlayer slippage of the Mo2TiAlC2 nanosheets, improving its shear resistance. The Mo2TiAlC2 nanosheets provide rigid support for g-C3N4, compensating for its insufficient hardness and further improving the stability and wear resistance of the coating.

[0033] Step S300 specifically includes: dispersing modified CeO2 nanoparticles in methanol, sonicating for 20-40 min to form a suspension, adding a metal salt, stirring for 20-30 min, adding an organic ligand, stirring for 10-20 min, transferring to a reaction vessel, raising the temperature to 100-120℃ and reacting for 18-24 h, after the reaction is completed, cooling to room temperature, centrifuging at 6000-8000 r / min for 10-15 min, washing with methanol 3-5 times, and then vacuum drying at 60-80℃ for 10-15 h to obtain MOFs / modified CeO2 composite; wherein the mass ratio of modified CeO2 nanoparticles, metal salt, organic ligand and methanol is 1:0.8-2.5:2-5:15-35; the metal salt is any one of zinc nitrate, copper nitrate, and cobalt nitrate; the organic ligand is any one of 2-methylimidazole, terephthalic acid, and trimesic acid.

[0034] MOFs possess abundant porous structures and extremely high specific surface areas, which can confine modified CeO2 nanoparticles within the pores or anchor them on the surface, further addressing the issue of nanoparticle aggregation. Furthermore, the high hardness of modified CeO2 nanoparticles can increase coating brittleness, while the organic ligands of MOFs exhibit a degree of flexibility, allowing for slight deformation. Their porous structure can also disperse localized stress during friction. When the coating is subjected to frictional impact, the pores of MOFs can absorb stress through deformation, preventing stress concentration and subsequent cracking. Simultaneously, the organic ligands of MOFs can form van der Waals forces or weak chemical bonds with the organic segments of organopolysiloxane alkylates, improving the interfacial bonding between inorganic particles and the matrix, and preventing filler detachment from the matrix during wear.

[0035] Specifically, step S400 includes: ultrasonically dispersing the MOFs / modified CeO2 composite and the Mo2TiAlC2 / g-C3N4 composite in a solvent, then adding an organopolysilazane and stirring for 20-40 minutes, followed by ultrasonication for 20-40 minutes to obtain a mixed slurry, spraying it onto the substrate surface, curing it at room temperature for 1-3 hours, and then curing it in a 60-80℃ oven for 2-4 hours to obtain the wear-resistant organopolysilazane coating; wherein the mass ratio of the MOFs / modified CeO2 composite, the Mo2TiAlC2 / g-C3N4 composite, the organopolysilazane, and the solvent is 1:0.33-1:6.67-18:8-30; wherein the substrate is an aluminum alloy substrate; the spraying pressure is 0.3-0.5 MPa, and the nozzle distance from the substrate is 15-25 cm.

[0036] The solvent is one or a mixture of several of anhydrous ethanol, xylene, and n-butanol.

[0037] In the above steps, the organopolysilazane undergoes hydrolysis under the action of moisture to generate silanol groups; the silanol groups can further undergo condensation reaction to form a network structure. At the same time, the silanol groups form chemical bonds with the substrate surface and the surfaces of MOFs / modified CeO2 composite and Mo2TiAlC2 / g-C3N4 composite. Finally, cross-linking is completed by oven curing to form a dense coating structure.

[0038] The CeO2 nanoparticles (particle size 20-50nm) and polydimethylsiloxane (viscosity 0.65cSt (25℃)) used in this invention were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Mo2TiAlC2 powder (type: 413, purity ≥99%) was purchased from Shanghai Yanbei New Material Technology Co., Ltd.; and organopolysilazane (IOTA 9150) was purchased from Anhui Aiyota Silicon Oil Co., Ltd. All reagents used in this application are commercially available.

[0039] Preparation Example 1-1

[0040] The preparation method of silane coupling agent containing long-chain organosilicon is as follows: propyltriethoxysilane, polydimethylsiloxane and chloroform are mixed and stirred at room temperature for 14 h, and then distilled under reduced pressure at 45 °C to obtain silane coupling agent containing long-chain organosilicon; wherein the mass ratio of propyltriethoxysilane, polydimethylsiloxane and chloroform is 6:12:16.

[0041] Preparation Examples 1-2

[0042] The preparation method of silane coupling agent containing long-chain organosilicon is as follows: propyltriethoxysilane, polydimethylsiloxane and chloroform are mixed and stirred at room temperature for 12 h, and then distilled under reduced pressure at 40 °C to obtain silane coupling agent containing long-chain organosilicon; wherein the mass ratio of propyltriethoxysilane, polydimethylsiloxane and chloroform is 4:10:12.

[0043] Preparation Examples 1-3

[0044] The preparation method of silane coupling agent containing long-chain organosilicon is as follows: propyltriethoxysilane, polydimethylsiloxane and chloroform are mixed and stirred at room temperature for 15 h, and then distilled under reduced pressure at 50 °C to obtain silane coupling agent containing long-chain organosilicon; wherein the mass ratio of propyltriethoxysilane, polydimethylsiloxane and chloroform is 8:15:20.

[0045] Preparation Example 2-1

[0046] HF (40wt%), HCl (37wt%), and deionized water were mixed in a volume ratio of 1:2:8, and then Mo2TiAlC2 powder was added to make the concentration of Mo2TiAlC2 powder in the solution 10 mg / mL. The mixture was stirred at 35℃ for 3 h. After the reaction was completed, the mixture was centrifuged at 7000 r / min for 12 min and washed with deionized water until neutral to obtain a precipitate. HF, HCl, and deionized water were mixed in a volume ratio of 1:2:8, and then LiCl was added to make the concentration of LiCl 0.3 mol / L. The mixture was ultrasonically dispersed for 15 min, and then the precipitate was added. The mass ratio of precipitate to LiCl was 1:8. The mixture was stirred for 12 h, centrifuged at 7000 r / min, and then ultrasonically dispersed for 15 min under ice bath conditions at a power of 400 W. Finally, the Mo2TiAlC2 nanosheets were collected by centrifugation at 4000 r / min for 8 min.

[0047] Preparation Example 2-2

[0048] HF (40wt%), HCl (37wt%), and deionized water were mixed in a volume ratio of 1:1:5, and then Mo2TiAlC2 powder was added to make the concentration of Mo2TiAlC2 powder in the solution 5 mg / mL. The mixture was stirred at 30℃ for 2 h. After the reaction was completed, the mixture was centrifuged at 6000 r / min for 10 min and washed with deionized water until neutral to obtain a precipitate. HF, HCl, and deionized water were mixed in a volume ratio of 1:1:5, and then LiCl was added to make the concentration of LiCl 0.1 mol / L. The mixture was ultrasonically dispersed for 10 min, and then the precipitate was added. The mass ratio of precipitate to LiCl was 1:5. The mixture was stirred for 10 h and then centrifuged at 6000 r / min. The mixture was then ultrasonically dispersed in an ice bath for 10 min at a power of 300 W. Finally, the Mo2TiAlC2 nanosheets were collected by centrifugation at 3000 r / min for 5 min.

[0049] Preparation Examples 2-3

[0050] HF (40wt%), HCl (37wt%), and deionized water were mixed at a volume ratio of 1:3:10, and then Mo2TiAlC2 powder was added to make the concentration of Mo2TiAlC2 powder in the solution 15 mg / mL. The mixture was stirred at 35℃ for 4 h. After the reaction was completed, the mixture was centrifuged at 8000 r / min for 15 min and washed with deionized water until neutral to obtain a precipitate. HF, HCl, and deionized water were mixed at a volume ratio of 1:3:10, and then LiCl was added to make the LiCl concentration 0.5 mol / L. The mixture was ultrasonically dispersed for 20 min, and then the precipitate was added. The mass ratio of precipitate to LiCl was 1:10. The mixture was stirred for 15 h, centrifuged at 8000 r / min, and then ultrasonically dispersed in an ice bath for 20 min at a power of 500 W. Finally, the Mo2TiAlC2 nanosheets were collected by centrifugation at 5000 r / min for 10 min.

[0051] Preparation Example 3-1

[0052] The preparation method of g-C3N4 is as follows: melamine is placed in a crucible, covered and placed in a muffle furnace, and heated to 550°C at a rate of 5°C / min. The temperature is maintained for 4 hours, and after natural cooling to room temperature, it is ground through a 200-mesh sieve to obtain g-C3N4.

[0053] Preparation Example 3-2

[0054] The preparation method of g-C3N4 is as follows: melamine is placed in a crucible, covered and placed in a muffle furnace, and heated to 540°C at a rate of 8°C / min. The temperature is maintained for 3 hours, and after natural cooling to room temperature, it is ground through a 200-mesh sieve to obtain g-C3N4.

[0055] Preparation Example 3-3

[0056] The preparation method of g-C3N4 is as follows: melamine is placed in a crucible, covered and placed in a muffle furnace, and heated to 560℃ at a rate of 10℃ / min. After holding at this temperature for 5 hours, it is naturally cooled to room temperature and then ground through a 200-mesh sieve to obtain g-C3N4.

[0057] Example 1

[0058] S1. Add 25g of CeO2 nanoparticles to 300mL of anhydrous ethanol, disperse by ultrasonication for 45min, add 25g of ethyl silicate, stir for 20min, add 20g of the silane coupling agent containing long-chain organosilicon prepared in Preparation Example 1-1, stir and mix for 15min, add concentrated ammonia to adjust the pH to 8.5, raise the temperature to 50℃ and react for 16h. After the reaction is completed, wash with anhydrous ethanol and deionized water alternately 4 times, centrifuge at 7000r / min for 15min and collect the precipitate, place it at 70℃ and vacuum dry for 20h to obtain modified CeO2 nanoparticles.

[0059] S2. Add 5g of Mo2TiAlC2 nanosheets prepared in Preparation Example 2-1 to 60mL of 30wt% hydrogen peroxide aqueous solution, stir at 60℃ for 3h, wash with deionized water until neutral, and dry at 70℃ for 5h. After drying, disperse with 5g of g-C3N4 prepared in Preparation Example 3-1 in 200mL of ethanol, sonicate for 30min, stir at 35℃ for 24h to obtain a mixture, dry at 80℃, raise to 300℃ at a rate of 5℃ / min under nitrogen atmosphere, keep at 300℃ for 2.5h, cool to room temperature, and grind to obtain Mo2TiAlC2 / g-C3N4 composite.

[0060] S3. Disperse 10g of modified CeO2 nanoparticles in 250mL of methanol, sonicate for 30min to form a suspension, add 22g of Zn(NO3)2·6H2O, stir for 25min, add 30g of 2-methylimidazole, stir for 15min, transfer to a reaction vessel, raise to 110℃ and react for 22h. After the reaction is completed, cool to room temperature, centrifuge at 7000r / min for 12min, wash with methanol 4 times and place at 70℃ for vacuum drying for 12h to obtain MOFs / modified CeO2 composite.

[0061] S4. 10g of MOFs / modified CeO2 composite and 8g of Mo2TiAlC2 / g-C3N4 composite were ultrasonically dispersed in 100mL of anhydrous ethanol. Then, 150g of polysilazane was added and stirred for 30min, followed by ultrasonication for 30min to obtain a mixed slurry. This slurry was sprayed onto the surface of an aluminum alloy substrate at a spraying pressure of 0.4MPa and a nozzle distance of 22cm from the substrate. After moisture curing at room temperature for 2h, the substrate was placed in a 70℃ oven for curing for 3h to obtain a wear-resistant organic polysilazane coating.

[0062] Example 2

[0063] This embodiment differs from Embodiment 1 in the following ways:

[0064] In step S1, 25g of CeO2 nanoparticles were added to 250mL of anhydrous ethanol and ultrasonically dispersed for 30min. Then, 12.5g of tetraethyl orthosilicate was added and stirred for 10min. Then, 7.5g of the silane coupling agent containing long-chain organosilicon prepared in Preparation Examples 1-2 was added and stirred for 10min. Concentrated ammonia was added to adjust the pH to 8, and the temperature was raised to 45℃ and reacted for 12h. After the reaction was completed, the nanoparticles were washed three times alternately with anhydrous ethanol and deionized water. After centrifugation at 6000r / min for 10min, the precipitate was collected and vacuum dried at 60℃ for 18h to obtain modified CeO2 nanoparticles.

[0065] In step S2, 5g of Mo2TiAlC2 nanosheets prepared in Preparation Example 2-2 were added to 50mL of 30wt% hydrogen peroxide aqueous solution and stirred at 55°C for 2h. After washing with deionized water until neutral, the nanosheets were dried at 60°C for 4h. After drying, the nanosheets were dispersed with 2.5g of g-C3N4 prepared in Preparation Example 3-2 in 170mL of ethanol and ultrasonically dispersed for 20min. The mixture was then stirred at 30°C for 20h to obtain a mixture. After drying at 70°C, the mixture was heated to 280°C at a rate of 10°C / min under a nitrogen atmosphere and kept at that temperature for 1.5h. After cooling to room temperature, the mixture was ground to obtain the Mo2TiAlC2 / g-C3N4 composite.

[0066] In step S3, 10g of modified CeO2 nanoparticles were dispersed in 150mL of methanol and sonicated for 20min to form a suspension. 8g of Zn(NO3)2·6H2O was added to the suspension and stirred for 20min. Then, 20g of 2-methylimidazole was added and stirred for 10min. The suspension was then transferred to a reaction vessel and heated to 100℃ for 18h. After the reaction was completed, the suspension was cooled to room temperature, centrifuged at 6000r / min for 10min, washed three times with methanol, and then vacuum dried at 60℃ for 10h to obtain the MOFs / modified CeO2 composite.

[0067] In step S4, 10g of MOFs / modified CeO2 composite and 3.5g of Mo2TiAlC2 / g-C3N4 composite are ultrasonically dispersed in 80mL of anhydrous ethanol, then 67g of polysilazane is added and stirred for 20min, followed by ultrasonication for 20min to obtain a mixed slurry. This slurry is then sprayed onto the surface of an aluminum alloy substrate to obtain a wear-resistant organic polysilazane coating.

[0068] Example 3

[0069] This embodiment differs from Embodiment 1 in the following ways:

[0070] In step S1, 25g of CeO2 nanoparticles were added to 500mL of anhydrous ethanol and ultrasonically dispersed for 30min. Then, 50g of ethyl silicate was added and stirred for 30min. Then, 25g of the silane coupling agent containing long-chain organosilicon prepared in Preparation Examples 1-2 was added and stirred for 20min. Concentrated ammonia was added to adjust the pH to 8, and the temperature was raised to 55℃ and reacted for 18h. After the reaction was completed, the nanoparticles were washed 5 times alternately with anhydrous ethanol and deionized water. After centrifugation at 8000r / min for 20min, the precipitate was collected and vacuum dried at 80℃ for 24h to obtain modified CeO2 nanoparticles.

[0071] In step S2, 5g of Mo2TiAlC2 nanosheets prepared in Preparation Example 2-3 were added to 100mL of 30wt% hydrogen peroxide aqueous solution and stirred at 65°C for 4h. After washing with deionized water until neutral, the nanosheets were dried at 80°C for 6h. After drying, the nanosheets were dispersed with 10g of g-C3N4 prepared in Preparation Example 3-3 in 300mL of ethanol and ultrasonically dispersed for 40min. The mixture was then stirred at 40°C for 28h to obtain a mixture. After drying at 90°C, the mixture was heated to 320°C at a rate of 10°C / min under a nitrogen atmosphere and kept at that temperature for 3.5h. After cooling to room temperature, the mixture was ground to obtain the Mo2TiAlC2 / g-C3N4 composite.

[0072] In step S3, 10g of modified CeO2 nanoparticles were dispersed in 300mL of methanol and sonicated for 40min to form a suspension. 25g of Zn(NO3)2·6H2O was added to the suspension and stirred for 30min. Then, 50g of 2-methylimidazole was added and stirred for 20min. The suspension was then transferred to a reaction vessel and heated to 120℃ for 24h. After the reaction was completed, the suspension was cooled to room temperature, centrifuged at 8000r / min for 15min, washed 5 times with methanol, and then vacuum dried at 80℃ for 15h to obtain the MOFs / modified CeO2 composite.

[0073] In step S4, 10g of MOFs / modified CeO2 composite and 10g of Mo2TiAlC2 / g-C3N4 composite are ultrasonically dispersed in 300mL of anhydrous ethanol, then 180g of polysilazane is added and stirred for 40min, followed by ultrasonication for 40min to obtain a mixed slurry. This slurry is then sprayed onto the surface of an aluminum alloy substrate to obtain a wear-resistant organic polysilazane coating.

[0074] Example 4

[0075] Compared with Example 1, this embodiment replaces the modified CeO2 nanoparticles with CeO2 nanoparticles.

[0076] Example 5

[0077] Compared with Example 1, this embodiment replaces Mo2TiAlC2 nanosheets with Mo2TiAlC2 powder.

[0078] Comparative Example 1

[0079] Compared with Example 1, this comparative example does not contain modified CeO2 nanoparticles, that is:

[0080] S1. Add 5g of Mo2TiAlC2 nanosheets prepared in Preparation Example 2-1 to 60mL of 30wt% hydrogen peroxide aqueous solution, stir at 60℃ for 3h, wash with deionized water until neutral, and dry at 70℃ for 5h. After drying, disperse with 5g of g-C3N4 prepared in Preparation Example 3-1 in 200mL of ethanol, sonicate for 30min, stir at 35℃ for 24h to obtain a mixture, dry at 80℃, raise to 300℃ at a rate of 5℃ / min under nitrogen atmosphere, keep at 300℃ for 2.5h, cool to room temperature, and grind to obtain Mo2TiAlC2 / g-C3N4 composite.

[0081] S2. Add 22g Zn(NO3)2·6H2O to 250mL methanol, stir for 25min, then add 30g 2-methylimidazole, stir for 30min, centrifuge at 7000r / min for 12min, wash with methanol 4 times, and then vacuum dry at 70℃ for 12h. Grind to obtain MOF powder.

[0082] S3. 10g of MOF powder and 8g of Mo2TiAlC2 / g-C3N4 composite were ultrasonically dispersed in 100mL of anhydrous ethanol. Then, 150g of polysilazane was added and stirred for 30min, followed by ultrasonication for 30min to obtain a mixed slurry. This slurry was sprayed onto the surface of an aluminum alloy substrate at a spraying pressure of 0.4MPa and a nozzle distance of 22cm from the substrate. After moisture curing at room temperature for 2h, the substrate was placed in a 70℃ oven for curing for 3h to obtain a wear-resistant organic polysilazane coating.

[0083] Comparative Example 2

[0084] Compared with Example 1, this comparative example does not contain g-C3N4, that is:

[0085] S1. Add 25g of CeO2 nanoparticles to 300mL of anhydrous ethanol, disperse by ultrasonication for 45min, add 25g of ethyl silicate, stir for 20min, add 20g of the silane coupling agent containing long-chain organosilicon prepared in Preparation Example 1-1, stir and mix for 15min, add concentrated ammonia to adjust the pH to 8.5, raise the temperature to 50℃ and react for 16h. After the reaction is completed, wash with anhydrous ethanol and deionized water alternately 4 times, centrifuge at 7000r / min for 15min and collect the precipitate, place it at 70℃ and vacuum dry for 20h to obtain modified CeO2 nanoparticles.

[0086] S2. 10g of modified CeO2 nanoparticles were dispersed in 250mL of methanol and sonicated for 30min to form a suspension. 22g of Zn(NO3)2·6H2O was added to the suspension and stirred for 25min. Then 30g of 2-methylimidazole was added and stirred for 15min. The suspension was then transferred to a reaction vessel and heated to 110℃ for 22h. After the reaction was completed, the suspension was cooled to room temperature and centrifuged at 7000r / min for 12min. The suspension was washed 4 times with methanol and then vacuum dried at 70℃ for 12h to obtain the MOFs / modified CeO2 composite.

[0087] S3. 10g of MOFs / modified CeO2 composite and 8g of Mo2TiAlC2 nanosheets prepared in Preparation Example 2-1 were ultrasonically dispersed in 100mL of anhydrous ethanol. Then, 150g of polysilazane was added and stirred for 30min, followed by ultrasonication for 30min to obtain a mixed slurry. This slurry was sprayed onto the surface of an aluminum alloy substrate at a spraying pressure of 0.4MPa and a nozzle distance of 22cm from the substrate. After moisture curing at room temperature for 2h, the substrate was placed in a 70℃ oven for curing for 3h to obtain a wear-resistant organic polysilazane coating.

[0088] Comparative Example 3

[0089] Compared with Example 1, this comparative example does not contain Mo2TiAlC2 nanosheets, that is:

[0090] S1. Add 25g of CeO2 nanoparticles to 300mL of anhydrous ethanol, disperse by ultrasonication for 45min, add 25g of ethyl silicate, stir for 20min, add 20g of the silane coupling agent containing long-chain organosilicon prepared in Preparation Example 1-1, stir and mix for 15min, add concentrated ammonia to adjust the pH to 8.5, raise the temperature to 50℃ and react for 16h. After the reaction is completed, wash with anhydrous ethanol and deionized water alternately 4 times, centrifuge at 7000r / min for 15min and collect the precipitate, place it at 70℃ and vacuum dry for 20h to obtain modified CeO2 nanoparticles.

[0091] S2. 10g of modified CeO2 nanoparticles were dispersed in 250mL of methanol and sonicated for 30min to form a suspension. 22g of Zn(NO3)2·6H2O was added to the suspension and stirred for 25min. Then 30g of 2-methylimidazole was added and stirred for 15min. The suspension was then transferred to a reaction vessel and heated to 110℃ for 22h. After the reaction was completed, the suspension was cooled to room temperature and centrifuged at 7000r / min for 12min. The suspension was washed 4 times with methanol and then vacuum dried at 70℃ for 12h to obtain the MOFs / modified CeO2 composite.

[0092] S3. 10g of MOFs / modified CeO2 composite and 8g of g-C3N4 composite prepared in Preparation Example 3-1 were ultrasonically dispersed in 100mL of anhydrous ethanol. Then, 150g of polysilazane was added and stirred for 30min, followed by ultrasonication for 30min to obtain a mixed slurry. This slurry was sprayed onto the surface of an aluminum alloy substrate at a spraying pressure of 0.4MPa and a nozzle distance of 22cm from the substrate. After moisture curing at room temperature for 2h, the substrate was placed in a 70℃ oven for curing for 3h to obtain a wear-resistant organic polysilazane coating.

[0093] Comparative Example 4

[0094] Compared with Example 1, this comparative example replaces the MOFs / modified CeO2 composite and the Mo2TiAlC2 / g-C3N4 composite with CeO2 nanoparticles, g-C3N4, and Mo2TiAlC2 powder, respectively.

[0095] S1. 25g CeO2 nanoparticles, 5g g-C3N4 prepared in Preparation Example 3-1 and 5g Mo2TiAlC2 powder were ultrasonically dispersed in 100mL anhydrous ethanol. Then 150g polysilazane was added and stirred for 30min, followed by ultrasonication for 30min to obtain a mixed slurry. This slurry was sprayed onto the surface of an aluminum alloy substrate at a spraying pressure of 0.4MPa and a nozzle distance of 22cm from the substrate. After moisture curing at room temperature for 2h, it was placed in a 70℃ oven for curing for 3h to obtain a wear-resistant organic polysilazane coating with a thickness of approximately 50μm.

[0096] Related tests

[0097] Coating hardness: Tested according to the method of GB / T 6739-2022;

[0098] Adhesion test: Tested according to the method of GB / T 9286-2021;

[0099] Thermal shock test: The test shall be conducted in accordance with the method of GB / T 30873-2014 (400℃ / 1h, five times by water quenching).

[0100] Abrasion resistance: Tested according to the method of GB / T 1768-2006.

[0101] The test results are shown in Table 1.

[0102] Table 1 Coating test results

[0103]

[0104] The test results above show that the coating prepared in this application has high hardness, good wear resistance and thermal shock resistance, and good bonding strength with the substrate.

[0105] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0106] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an wear-resistant organopolysilazane coating, characterized in that, Includes the following steps: S100: CeO2 nanoparticles are added to anhydrous ethanol, ultrasonically dispersed, and then ethyl silicate is added. After stirring for 10-30 min, a silane coupling agent containing long-chain organosilicon is added and stirred for 10-20 min. Concentrated ammonia is added to adjust the pH to weakly alkaline, and the temperature is raised to 45-55℃ for 12-18 h. After washing, centrifugation, and drying, modified CeO2 nanoparticles are obtained. The preparation method of the silane coupling agent containing long-chain organosilicon is as follows: propyltriethoxysilane isocyanate, polydimethylsiloxane, and chloroform are mixed and stirred at room temperature for 12-15 h to obtain the silane coupling agent containing long-chain organosilicon. S200: Mo2TiAlC2 nanosheets were added to an aqueous solution of hydrogen peroxide and stirred at 55-65℃ for 2-4 hours. After washing and drying, they were dispersed with g-C3N4 in ethanol, ultrasonically dispersed, and stirred for 20-28 hours to obtain a mixture. After drying at 70-90℃, the temperature was raised to 280-320℃ under an inert atmosphere and kept at that temperature for 1.5-3.5 hours. After cooling, the Mo2TiAlC2 / g-C3N4 composite was obtained. S300, using modified CeO2 nanoparticles, metal salts, and organic ligands as raw materials, prepared MOFs / modified CeO2 composites; the metal salt is any one of zinc nitrate, copper nitrate, and cobalt nitrate; the organic ligand is any one of 2-methylimidazole, terephthalic acid, and trimesic acid. Using raw materials such as S400, Mo2TiAlC2 / g-C3N4 composite, MOFs / modified CeO2 composite, and organopolysilazane, a mixed slurry is prepared and sprayed onto the surface of a substrate to obtain the wear-resistant organopolysilazane coating.

2. The method for preparing a wear-resistant organopolysilazane coating according to claim 1, characterized in that, The preparation steps of the Mo2TiAlC2 nanosheets are as follows: HF, HCl and deionized water are mixed and then added to Mo2TiAlC2 powder. The mixture is stirred at 30-35℃ for 2-4 hours. After the reaction is completed, the precipitate is obtained by centrifugation and washing. HF, HCl and deionized water are mixed and then added to LiCl. After ultrasonic dispersion, the precipitate is added and stirred for 10-15 hours. After centrifugation, the mixture is then ultrasonically dispersed for 10-20 minutes under ice bath conditions. The Mo2TiAlC2 nanosheets are collected by centrifugation.

3. The method for preparing a wear-resistant organopolysilazane coating according to claim 1, characterized in that, The preparation method of g-C3N4 is as follows: melamine is placed in a crucible, covered and placed in a muffle furnace and heated to 540-560℃, kept at that temperature for 3-5 hours, and then ground after natural cooling to obtain g-C3N4.

4. The method for preparing a wear-resistant organopolysilazane coating according to claim 1, characterized in that, Step S300 specifically includes: dispersing modified CeO2 nanoparticles in methanol, sonicating for 20-40 min to form a suspension, adding a metal salt to the suspension, stirring for 20-30 min, adding an organic ligand, stirring for 10-20 min, transferring to a reaction vessel, raising the temperature to 100-120℃ and reacting for 18-24 h, cooling to room temperature after the reaction, and obtaining the MOFs / modified CeO2 composite by centrifugation, washing and drying.

5. The method for preparing an wear-resistant organopolysilazane coating according to claim 1, characterized in that, Step S400 specifically includes: ultrasonically dispersing the MOFs / modified CeO2 composite and the Mo2TiAlC2 / g-C3N4 composite in a solvent, then adding organopolysilazane and stirring for 20-40 min, followed by ultrasonication for 20-40 min to obtain a mixed slurry, spraying it onto the surface of the substrate, and then curing it in a moisture environment at room temperature for 1-3 h before placing it in an oven for 2-4 h to obtain the wear-resistant organopolysilazane coating.

6. A wear-resistant organopolysilazane coating, characterized in that, The wear-resistant organopolysilazane coating was prepared using the method described in any one of claims 1-5.

Images