A wear-resistant ceramic coating and preparation method thereof

Abstract

The present invention belongs to the technical field of ceramic coating materials, specifically relating to a wear-resistant ceramic coating and its preparation method. This invention first prepares an alumina composite material containing modified nickel-coated graphite, which is then combined with zinc oxide, zirconium oxide, sodium molybdate, and aluminum dihydrogen phosphate to form a wear-resistant ceramic coating on the surface of a metal substrate. Through the synergistic effect of these components, the friction coefficient and wear rate of the ceramic coating are effectively reduced, while the coating hardness is simultaneously increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic coating materials, and in particular relates to a wear-resistant ceramic coating and a preparation method thereof. Background Art

[0002] In harsh working conditions, metal components and equipment can no longer meet actual production requirements, especially in industries such as mining, electricity, coal, aviation, and aerospace. Friction, wear, and corrosion often cause component and equipment failure, and even cause serious personal safety issues. Ceramic coatings applied to metal surfaces not only have the corrosion resistance, wear resistance, and high temperature resistance of ceramic materials, but also have the physical properties of metal materials. This is one of the research focuses of metal surface protection technology. Applying a layer of ceramic protective coating on the metal surface does not change the morphology, structure, and chemical composition of the metal surface, allowing the metal substrate to maintain its toughness, but also gives the base material new properties, such as wear resistance, corrosion resistance, anti-sticking, high hardness, high temperature resistance, and insulation.

[0003] A Chinese patent (publication number CN113564574B) discloses a nickel-coated graphite-reinforced wear-resistant, friction-reducing, and corrosion-resistant ceramic coating material, coating, preparation method, and application thereof. The nickel-coated graphite-reinforced wear-resistant, friction-reducing, and corrosion-resistant ceramic coating prepared by this invention utilizes a simple sol-gel method. It exhibits excellent wear resistance, friction reduction, and corrosion resistance, making it suitable for use in a variety of harsh corrosive environments and on surfaces subject to impact and wear. This broadens the coating's application areas in harsh environments and offers considerable market potential. However, further research is needed to further reduce the friction coefficient and wear rate of ceramic coatings while simultaneously increasing their hardness, ultimately achieving a ceramic coating that balances good wear resistance and hardness.

[0004] Therefore, there is an urgent need for a wear-resistant ceramic coating. By screening the components of the ceramic coating and modifying specific components, the synergistic effect of multiple components can be achieved, which can effectively reduce the friction coefficient and wear rate of the ceramic coating and improve the hardness of the coating. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a wear-resistant ceramic coating and a preparation method thereof. The present invention first prepares an alumina composite material containing modified nickel-coated graphite, and then uses it together with zinc oxide, zirconium oxide, sodium molybdate and aluminum dihydrogen phosphate to obtain a wear-resistant ceramic coating on the surface of the metal substrate. Through the synergistic effect of each component, the friction coefficient and wear rate of the ceramic coating are effectively reduced, while the hardness of the coating is improved.

[0006] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0007] A first aspect of the present invention provides a method for preparing a wear-resistant ceramic coating, comprising the following steps:

[0008] S1: 6-8 parts by weight of commercially available alumina are silanized and then dispersed in 280-300 parts of N,N-dimethylformamide, followed by addition of 20-30 parts of modified nickel-coated graphite for heating and reaction to obtain an alumina composite material;

[0009] S2: 50-60 parts of alumina composite material, 4-6 parts of zinc oxide, 2-8 parts of zirconium oxide, and 4-6 parts of sodium molybdate were mixed and ball-milled for 6-8 hours, and then 40-50 parts of aluminum dihydrogen phosphate were added and stirred for 12-16 hours to obtain a coating adhesive;

[0010] S3: coating the coating adhesive on the pretreated metal substrate, and obtaining a wear-resistant ceramic coating after curing.

[0011] As a preferred solution, the weight proportion of the alumina composite material in the present invention can be 20 parts, 22 parts, 24 parts, 26 parts, 28 parts or 30 parts.

[0012] As a preferred solution, the weight proportion of the zinc oxide in the present invention can be 4 parts, 4.5 parts, 5 parts, 5.5 parts or 6 parts.

[0013] As a preferred solution, the weight proportion of the zirconium oxide in the present invention can be 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts.

[0014] As a preferred solution, the weight proportions of the sodium molybdate in the present invention can be 4 parts, 4.5 parts, 5 parts, 5.5 parts or 6 parts.

[0015] As a preferred solution, the weight parts of the aluminum dihydrogen phosphate in the present invention can be 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts or 50 parts, etc.

[0016] As a preferred solution, the silanization treatment conditions include: fully dissolving 40 to 50 parts of γ-glycidyloxypropyltrimethoxysilane in a mixture of 400 to 450 parts of anhydrous ethanol and 50 to 100 parts of deionized water, then adding 6 to 8 parts of commercially available alumina and ultrasonically dispersing them uniformly, stirring and refluxing at 76 to 80° C. for 2 to 4 hours, washing with water, vacuum drying, and grinding.

[0017] As a preferred solution, the particle size of the commercially available alumina is 20-100 nm; further preferably, the particle size of the commercially available alumina is 20-50 nm.

[0018] As a preferred solution, the conditions of the heating reaction include: controlling the pH to 8.2-8.6, stirring at 80-90° C. for 4-6 hours, washing with water, and vacuum drying.

[0019] As a preferred solution, the preparation method of the modified nickel-coated graphite includes: mixing 60 to 70 parts by weight of hydrochloric acid and 100 to 120 parts by weight of a 30% hydrogen peroxide solution, then adding 20 to 30 parts of nickel-coated graphite for activation treatment to obtain activated nickel-coated graphite; adding 20 to 30 parts of the activated nickel-coated graphite to 80 to 100 parts by weight of an ethylenediamine solution with a concentration of 20 to 30% for surface modification to obtain modified nickel-coated graphite.

[0020] As a preferred solution, the activation treatment conditions include: stirring at room temperature for 30 to 40 minutes, filtering, washing with deionized water, and drying.

[0021] As a preferred solution, the surface modification conditions include: stirring at a speed of 90-100 r / min for 60-80 min, filtering, washing with water, and drying.

[0022] The modified nickel-coated graphite of the present invention is first activated by hydrochloric acid and hydrogen peroxide, and the nickel on the surface of the nickel-coated graphite reacts with the hydrogen peroxide under acidic conditions, and a small amount of nickel ions generated react with ethylenediamine for coordination adsorption reaction, thereby introducing amino groups into the surface of the nickel-coated graphite; hydroxyl groups exist on the surface of aluminum oxide, which can be silanized by using gamma-glycidyloxypropyltrimethoxysilane, and then the active groups of the silane coupling agent react with the ethylenediamine introduced into the modified nickel-coated graphite, thereby preparing an aluminum oxide composite material.

[0023] As a preferred solution, the zinc oxide is modified zinc oxide;

[0024] The preparation method of the modified zinc oxide comprises: adding 1.2 to 1.4 parts of zinc acetate and 10 to 14 parts of deionized water to 200 to 220 parts of diethylene glycol, performing a gelation reaction, and obtaining a zinc oxide sol; adding 0.4 to 0.8 parts of magnetic carbon nanotubes to the zinc oxide sol, performing ultrasonic treatment to form a suspension, and then performing a stirring reaction to obtain the modified zinc oxide.

[0025] As a preferred solution, the gelation reaction conditions include: stirring at 170-180° C. for 4-8 minutes, and standing at room temperature for 2-3 hours after white turbidity appears.

[0026] As a preferred solution, the stirring reaction conditions include: controlling the temperature to 176-180° C., stirring for 120-140 min, cooling to room temperature, washing with water, and vacuum drying.

[0027] As a preferred solution, the preparation method of the magnetic carbon nanotubes comprises: dissolving 40 to 50 parts of ferric chloride and 6 to 8 parts of ferrous chloride in 500 to 600 parts of deionized water, then adding 10 to 16 parts of carboxylated carbon nanotubes for ultrasonic dispersion, and then adding ammonia water and sodium citrate for hydrothermal reaction to obtain magnetic carbon nanotubes.

[0028] As a preferred solution, the specific steps of the hydrothermal reaction include: adjusting the pH to 8.2-8.8 with ammonia water with a mass concentration of 4-6%, heating to 70-80°C and stirring for 30-40 minutes, then adding 16-20 parts of sodium citrate and reacting at a constant temperature of 70-80°C for 90-100 minutes, cooling to room temperature, magnetic separation, washing with water, and drying.

[0029] The carboxylated carbon nanotubes used in the present invention have groups such as carboxyl groups and exhibit negative charges. The negative surface charge can adsorb iron ions onto the carbon nanotube surface through electrostatic action. When ammonia water is added as a precipitant, the iron ions nucleate on the carbon nanotube surface to generate ferroferric oxide particles. These particles are then composited simultaneously during the generation of magnetic particles through coprecipitation, resulting in a large and evenly distributed magnetic particle load. Simultaneously, oxygen-containing functional groups are introduced onto the surface of the magnetic carbon nanotubes through the carboxyl groups. Through physical and chemical adsorption, the zinc oxide sol formed after the hydrolysis of zinc acetate is loaded onto the carbon nanotube surface, thereby preparing modified zinc oxide.

[0030] As a preferred solution, the pretreatment conditions in step S3 include: removing the oxide layer and rust spots on the surface of the metal substrate using silicon carbide sandpaper, ultrasonic cleaning, and drying.

[0031] There are pollutants such as oil spots, rust spots, oxide scale and dust on the surface of the metal substrate. Pretreatment to remove the pollutants can ensure that the coating material and the metal substrate have good bonding strength.

[0032] As a preferred solution, the curing treatment conditions in step S3 include: first keeping warm at 50-60°C for 50-60 minutes, then heating to 100-110°C and keeping warm for 100-120 minutes, then heating to 150-160°C and keeping warm for 50-60 minutes, and finally heating to 260-280°C and keeping warm for 60-80 minutes, and cooling to room temperature.

[0033] The coating contains a large amount of adsorbed water and bound water, so the curing process of the coating cannot be too fast. It needs to be heated slowly to ensure uniform heating, so as to adopt a gradient curing method to allow the curing reaction to proceed fully.

[0034] The second aspect of the present invention provides a wear-resistant ceramic coating prepared by the method described in the first aspect.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The modified zinc oxide of the present invention loads magnetic ferroferric oxide particles through carbon nanotubes, which generates magnetic dipole-dipole attraction with nickel-coated graphite in the alumina composite material. At the same time, the carbon nanotubes of the former and the graphite of the latter are both sp² hybridized carbon structures, which can undergo π-π conjugated stacking through the π electron cloud on the surface, further strengthening the dense network formed by the two, thereby effectively reducing the friction coefficient and wear rate of the coating and improving the hardness of the coating.

[0037] (2) The alumina of the present invention has high hardness, high wear resistance and chemical stability, and is the basic skeleton of the ceramic coating. The nickel coating strengthens the bonding between the alumina and the metal substrate, reduces the concentration of interfacial stress, and the lubricating effect of the graphite reduces the surface damage caused by friction. At the same time, the ductility of the nickel buffers the impact, forming a "hard-soft" composite structure, which effectively improves the wear resistance. In addition, the nickel coating hinders dislocation movement through dispersion strengthening, enhances the plastic deformation resistance of the coating, and the interlayer shear of the graphite layer can disperse stress and inhibit crack initiation, thereby increasing the hardness of the coating.

[0038] (3) The modified zinc oxide of the present invention increases the bonding strength between the coating matrix through the bridging effect of magnetic carbon nanotubes, reduces the possibility of the coating peeling due to friction and wear, and thus reduces the wear rate of the coating. At the same time, the modified zinc oxide is squeezed out during the friction and wear process and adsorbed on the grinding surface to form a lubricating film, thereby reducing the friction coefficient of the coating. Adding modified zinc oxide to the ceramic coating can make the coating structure denser, reduce the generation of defects such as holes, and strengthen the coating through bridging and other means to form a coating with a relatively complete structure, thereby improving the overall hardness of the coating. DETAILED DESCRIPTION

[0039] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0040] The sources of some components in the Examples and Comparative Examples are as follows:

[0041] Alumina I, product number A431930, particle size 40 nm, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0042] Alumina II, product number A102005, particle size 5 μm, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0043] Commercially available zinc oxide, product number Z112848, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0044] Zirconia, product number Z431831, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0045] Sodium molybdate, CAS No. 10102-40-6, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0046] Aluminum dihydrogen phosphate, CAS No. 13530-50-2, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0047] Nickel-coated graphite, model 2701, was purchased from Beijing Antepura Materials Science and Trade Co., Ltd.;

[0048] Hydrogen peroxide solution, product number H639762, mass concentration of 30%, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0049] Ethylenediamine, CAS No. 107-15-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0050] γ-Glycidyloxypropyltrimethoxysilane, CAS No. 2530-83-8, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0051] N,N-dimethylformamide, CAS No. 68-12-2, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0052] Ferric chloride, CAS No. 10025-77-1, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0053] Ferrous chloride, CAS No. 13478-10-9, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0054] Carboxylated carbon nanotubes, model XFD06, were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0055] Ammonia water, CAS No. 1336-21-6, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0056] Sodium citrate, CAS No. 68-04-2, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0057] Zinc acetate, CAS No. 557-34-6, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0058] Diethylene glycol, CAS No. 111-46-6, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0059] Example 1

[0060] This embodiment provides a method for preparing a wear-resistant ceramic coating, comprising the following steps:

[0061] S1: Dissolve 50 parts of γ-glycidyloxypropyltrimethoxysilane in a mixture of 450 parts of anhydrous ethanol and 50 parts of deionized water, then add 8 parts of aluminum oxide I (Product No. A431930, particle size 40 nm) and disperse uniformly by ultrasonication. Stir and reflux at 80°C for 2 hours, wash with water, dry in vacuum, and grind to obtain silanized aluminum oxide. The mixture is then dispersed in 300 parts of N,N-dimethylformamide, and 30 parts of modified nickel-coated graphite are added for heating reaction. The pH is controlled at 8.6, stirred at 90°C for 4 hours, washed with water, and dried in vacuum to obtain an aluminum oxide composite material.

[0062] S2: 60 parts of alumina composite material, 6 parts of modified zinc oxide, 8 parts of zirconium oxide, and 6 parts of sodium molybdate were mixed and ball-milled for 8 hours, and then 50 parts of aluminum dihydrogen phosphate were added and stirred for 16 hours to obtain a coating adhesive;

[0063] S3: Use silicon carbide sandpaper to remove the oxide layer and rust spots on the surface of the metal substrate, ultrasonically clean and dry to obtain a pretreated metal substrate, apply the coating glue on the pretreated metal substrate, first keep it at 60°C for 50 minutes, then heat it to 110°C for 100 minutes, then heat it to 160°C for 50 minutes, and finally heat it to 280°C for 60 minutes, and cool it to room temperature to obtain a wear-resistant ceramic coating.

[0064] The modified nickel-coated graphite is prepared by uniformly mixing 70 parts of hydrochloric acid and 120 parts of a 30% hydrogen peroxide solution by weight, then adding 30 parts of nickel-coated graphite for activation treatment, stirring at room temperature for 40 minutes, filtering, washing with deionized water, and drying to obtain activated nickel-coated graphite; and adding 30 parts of the activated nickel-coated graphite to 100 parts of a 30% ethylenediamine solution for surface modification, stirring at a speed of 100 r / min for 60 minutes, filtering, washing with water, and drying to obtain the modified nickel-coated graphite.

[0065] Preparation of the modified zinc oxide: (1) Dissolve 50 parts of ferric chloride and 8 parts of ferrous chloride in 600 parts of deionized water, then add 16 parts of carboxylated carbon nanotubes and ultrasonically disperse them, adjust the pH to 8.8 with 6% ammonia water, heat to 80°C and stir for 30 minutes, then add 20 parts of sodium citrate and react at 80°C for 90 minutes, cool to room temperature, separate by magnetic attraction, wash with water, and dry to obtain magnetic carbon nanotubes. (2) Add 1.4 parts of zinc acetate and 14 parts of deionized water to 220 parts of diethylene glycol for gelation reaction (stir at 180°C for 4 minutes, let stand at room temperature for 3 hours after white turbidity appears), and obtain zinc oxide sol; add 0.8 parts of magnetic carbon nanotubes to the zinc oxide sol, ultrasonically treat to form a suspension, and then stir and react (control the temperature at 1180°C and stir for 120 minutes, cool to room temperature, wash with water, and vacuum dry) to obtain modified zinc oxide.

[0066] Example 2

[0067] This embodiment provides a method for preparing a wear-resistant ceramic coating, comprising the following steps:

[0068] S1: Dissolve 40 parts of γ-glycidyloxypropyltrimethoxysilane in a mixture of 400 parts of anhydrous ethanol and 100 parts of deionized water, then add 6 parts of aluminum oxide I (Product No. A431930, particle size 40 nm) and disperse uniformly by ultrasonication. Stir and reflux at 76°C for 4 hours, wash with water, vacuum dry, and grind to obtain silanized aluminum oxide. The mixture is then dispersed in 280 parts of N,N-dimethylformamide, and 20 parts of modified nickel-coated graphite are added for heating reaction. The pH is controlled at 8.2, stirred at 80°C for 6 hours, washed with water, and vacuum dried to obtain an aluminum oxide composite material.

[0069] S2: 50 parts of alumina composite material, 4 parts of modified zinc oxide, 2 parts of zirconium oxide, and 4 parts of sodium molybdate were mixed and ball-milled for 6 hours, and then 40 parts of aluminum dihydrogen phosphate were added and stirred for 12 hours to obtain a coating adhesive;

[0070] S3: Use silicon carbide sandpaper to remove the oxide layer and rust spots on the surface of the metal substrate, ultrasonically clean and dry to obtain a pretreated metal substrate, apply the coating glue on the pretreated metal substrate, first keep it at 50°C for 60 minutes, then heat it to 100°C for 120 minutes, then heat it to 150°C for 60 minutes, and finally heat it to 260°C for 80 minutes, and cool it to room temperature to obtain a wear-resistant ceramic coating.

[0071] The modified nickel-coated graphite is prepared by uniformly mixing 60 parts of hydrochloric acid and 100 parts of a 30% hydrogen peroxide solution by weight, then adding 20 parts of nickel-coated graphite for activation treatment, stirring at room temperature for 30 minutes, filtering, washing with deionized water, and drying to obtain activated nickel-coated graphite; and adding 20 parts of the activated nickel-coated graphite to 80 parts of a 20% ethylenediamine solution for surface modification, stirring at 90 r / min for 80 minutes, filtering, washing with water, and drying to obtain the modified nickel-coated graphite.

[0072] Preparation of the modified zinc oxide: (1) by weight, 40 parts of ferric chloride and 6 parts of ferrous chloride are dissolved in 500 parts of deionized water, and then 10 parts of carboxylated carbon nanotubes are added for ultrasonic dispersion, and the pH is adjusted to 8.2-8.8 with ammonia water having a mass concentration of 4-6%, and the temperature is raised to 70°C and stirred for 40 minutes, and then 16 parts of sodium citrate are added and the reaction is carried out at a constant temperature of 70°C for 100 minutes, and then cooled to room temperature, separated by magnetic attraction, washed with water, and dried to obtain magnetic carbon nanotubes. (2) 1.2 parts of zinc acetate and 10 parts of deionized water were added to 200 parts of diethylene glycol for gelation reaction (stirred at 170°C for 8 minutes, and allowed to stand at room temperature for 2 hours after white turbidity appeared) to obtain zinc oxide sol; 0.4 parts of magnetic carbon nanotubes were added to the zinc oxide sol, ultrasonically treated to form a suspension, and then stirred for reaction (controlled temperature at 176°C and stirred for 140 minutes, cooled to room temperature, washed with water, and vacuum dried) to obtain modified zinc oxide.

[0073] Example 3:

[0074] This embodiment provides a method for preparing a wear-resistant ceramic coating, comprising the following steps:

[0075] S1: By weight, 45 parts of γ-glycidyloxypropyltrimethoxysilane were fully dissolved in a mixture of 420 parts of anhydrous ethanol and 80 parts of deionized water. 7 parts of aluminum oxide I (Product No. A431930, particle size 40 nm) were then added and ultrasonically dispersed uniformly. The mixture was stirred and refluxed at 78°C for 3 hours, washed with water, vacuum dried, and ground to obtain silanized aluminum oxide. The mixture was then dispersed in 290 parts of N,N-dimethylformamide, and 25 parts of modified nickel-coated graphite were added for heating reaction. The pH was controlled to 8.4. The mixture was stirred at 85°C for 5 hours, washed with water, and vacuum dried to obtain an aluminum oxide composite material.

[0076] S2: 55 parts of alumina composite material, 5 parts of modified zinc oxide, 6 parts of zirconium oxide, and 5 parts of sodium molybdate were mixed and ball-milled for 7 hours, and then 45 parts of aluminum dihydrogen phosphate were added and stirred for 14 hours to obtain a coating adhesive;

[0077] S3: Use silicon carbide sandpaper to remove the oxide layer and rust spots on the surface of the metal substrate, ultrasonically clean and dry to obtain a pretreated metal substrate, apply the coating glue on the pretreated metal substrate, first keep it at 55°C for 55 minutes, then heat it to 105°C for 110 minutes, then heat it to 155°C for 55 minutes, and finally heat it to 270°C for 70 minutes, and cool it to room temperature to obtain a wear-resistant ceramic coating.

[0078] The modified nickel-coated graphite is prepared by uniformly mixing 65 parts of hydrochloric acid and 110 parts of a 30% hydrogen peroxide solution by weight, then adding 25 parts of nickel-coated graphite for activation treatment, stirring at room temperature for 35 minutes, filtering, washing with deionized water, and drying to obtain activated nickel-coated graphite; and adding 25 parts of the activated nickel-coated graphite to 90 parts of a 25% ethylenediamine solution for surface modification, stirring at a speed of 95 r / min for 70 minutes, filtering, washing with water, and drying to obtain the modified nickel-coated graphite.

[0079] Preparation of the modified zinc oxide: (1) 45 parts of ferric chloride and 7 parts of ferrous chloride were dissolved in 550 parts of deionized water, and then 14 parts of carboxylated carbon nanotubes were added for ultrasonic dispersion, and the pH was adjusted to 8.4 with 5% ammonia water, and the temperature was raised to 75°C and stirred for 35 minutes. Then 18 parts of sodium citrate were added and the mixture was kept at 75°C for 95 minutes, cooled to room temperature, separated by magnetic attraction, washed with water, and dried to obtain magnetic carbon nanotubes. (2) 1.3 parts of zinc acetate and 12 parts of deionized water were added to 210 parts of diethylene glycol for gelation reaction (stirred at 175°C for 6 minutes, and allowed to stand at room temperature for 2.5 hours after white turbidity appeared) to obtain zinc oxide sol; 0.6 parts of magnetic carbon nanotubes were added to the zinc oxide sol, ultrasonically treated to form a suspension, and then stirred (controlled at 178°C for 130 minutes, cooled to room temperature, washed with water, and vacuum dried) to obtain modified zinc oxide.

[0080] Example 4

[0081] The difference between this embodiment and embodiment 1 is that commercially available zinc oxide (product number Z112848) is used instead of modified zinc oxide.

[0082] Comparative Example 1

[0083] The difference between this comparative example and Example 1 is that 6 parts of modified zinc oxide are not added to the coating composition.

[0084] Comparative Example 2

[0085] The difference between this comparative example and Example 1 is that commercially available aluminum oxide I (product number A431930) is used instead of the aluminum oxide composite material.

[0086] Comparative Example 3

[0087] The difference between this comparative example and Example 1 is that commercially available aluminum oxide II (article number A102005) is used instead of commercially available aluminum oxide I (article number A431930) to prepare the aluminum oxide composite material.

[0088] Comparative Example 4

[0089] The difference between this comparative example and Example 1 is that commercially available aluminum oxide I (article number A431930) is used instead of the aluminum oxide composite material, and commercially available zinc oxide (article number Z112848) is used instead of the modified zinc oxide.

[0090] Comparative Example 5

[0091] The difference between this comparative example and Example 1 is that commercial silanized alumina is used instead of the alumina composite material.

[0092] Comparative Example 6

[0093] The difference between this comparative example and Example 1 is that carboxylated carbon nanotubes (model XFD06) are used instead of magnetic carbon nanotubes to prepare the modified zinc oxide.

[0094] Comparative Example 7

[0095] The difference between this comparative example and Example 1 is that nickel-coated graphite (model 2701) is used instead of modified nickel-coated graphite to prepare the alumina composite material.

[0096] The performance of the ceramic coatings provided in the above embodiments and comparative examples was tested using the following test methods:

[0097] (1) Wear resistance and friction reduction test: The ceramic coating was subjected to tribological tests using an MFT-5000 series universal friction and wear testing machine. The test conditions were as follows: a loading load of 20 N, a test time of 30 minutes, a speed of 20 mm / s, and a silicon nitride ball with a diameter of φ9 mm. The friction coefficient and wear rate of the ceramic coating were used to characterize the wear resistance.

[0098] (2) Hardness test: The coating microhardness test adopts MH-3 microhardness tester, the indenter adopts diamond regular quadrangular pyramid, the angle between the indenter faces is 136°, the test load is 980.7mN, and the holding time is 12s.

[0099] The above performance test data is shown in Table 1.

[0100]

[0101] As can be seen from the above content, the present invention first prepares an alumina composite material containing modified nickel-coated graphite, then adds modified zinc oxide containing magnetic carbon nanotubes, and simultaneously uses zirconium oxide, sodium molybdate, and aluminum dihydrogen phosphate together to obtain a wear-resistant ceramic coating on the surface of a metal substrate (Examples 1-3). The coating has excellent overall performance, including excellent wear resistance and hardness.

[0102] Compared with Example 1, when commercially available zinc oxide (Article No. Z112848) was used instead of modified zinc oxide, the wear resistance deteriorated and the hardness decreased (Example 4). Compared with Example 1, 6 parts of modified zinc oxide were not added to the coating component, the wear resistance deteriorated and the hardness decreased (Comparative Example 1). Compared with Example 1, when commercially available aluminum oxide I (Article No. A431930) was used instead of the aluminum oxide composite material, the wear resistance deteriorated and the hardness decreased (Comparative Example 2). Compared with Example 1, when commercially available aluminum oxide II (Article No. A102005) was used instead of the commercially available aluminum oxide I (Article No. A431930) to prepare the aluminum oxide composite material, the particle size of the commercially available aluminum oxide II was too large, the modification effect was not good, the wear resistance deteriorated and the hardness decreased (Comparative Example 3). Compared with Example 1, when commercially available aluminum oxide I (Article No. A431930) was used instead of the aluminum oxide composite material, commercially available zinc oxide (Article No. Z112 848) instead of modified zinc oxide, the wear resistance deteriorates and the hardness decreases (Comparative Example 4); compared with Example 1, silanized alumina is used to replace the alumina composite material. Since the alumina is only surface treated and the modified nickel-coated graphite is not introduced, the lubricating effect of the nickel-coated graphite is lacking, the wear resistance deteriorates and the hardness decreases (Comparative Example 5); compared with Example 1, carboxylated carbon nanotubes (model XFD06) are used to replace magnetic carbon nanotubes for the preparation of modified zinc oxide. Due to the lack of magnetic adsorption of magnetic carbon nanotubes, the synergistic effect deteriorates, the wear resistance deteriorates and the hardness decreases (Comparative Example 6); compared with Example 1, nickel-coated graphite (model 2701) is used to replace modified nickel-coated graphite for the preparation of alumina composite material. Since the surface of nickel-coated graphite lacks active groups, it is difficult to combine with silanized alumina, resulting in poor modification effect, poor wear resistance and reduced hardness (Comparative Example 7).

[0103] In summary, the present invention first prepares an alumina composite material containing modified nickel-coated graphite, and then uses it together with modified zinc oxide, zirconium oxide, sodium molybdate and aluminum dihydrogen phosphate to obtain a wear-resistant ceramic coating on the surface of the metal substrate. Through the synergistic effect of each component, the friction coefficient and wear rate of the ceramic coating are effectively reduced, while the hardness of the coating is improved.

Claims

1. A method for preparing a wear-resistant ceramic coating, characterized in that: The following steps are involved: S1: 6-8 parts by weight of commercially available alumina are silanized and then dispersed in 280-300 parts of N,N-dimethylformamide, followed by addition of 20-30 parts of modified nickel-coated graphite for heating and reaction to obtain an alumina composite material; S2: 50-60 parts of alumina composite material, 4-6 parts of modified zinc oxide, 2-8 parts of zirconium oxide, and 4-6 parts of sodium molybdate were mixed and ball-milled for 6-8 hours, and then 40-50 parts of aluminum dihydrogen phosphate were added and stirred for 12-16 hours to obtain a coating adhesive; S3: applying the coating adhesive on the pretreated metal substrate, and curing the coating to obtain a wear-resistant ceramic coating; The preparation method of the modified nickel-coated graphite comprises: uniformly mixing 60-70 parts of hydrochloric acid and 100-120 parts of a hydrogen peroxide solution with a mass concentration of 30%, and then adding 20-30 parts of nickel-coated graphite for activation treatment to obtain activated nickel-coated graphite; adding 20-30 parts of the activated nickel-coated graphite to 80-100 parts of an ethylenediamine solution with a mass concentration of 20-30% for surface modification to obtain modified nickel-coated graphite; The preparation method of the modified zinc oxide comprises: adding 1.2 to 1.4 parts of zinc acetate and 10 to 14 parts of deionized water to 200 to 220 parts of diethylene glycol for gelation reaction to obtain a zinc oxide sol; adding 0.4 to 0.8 parts of magnetic carbon nanotubes to the zinc oxide sol, ultrasonically treating the sol to form a suspension, and then stirring the suspension to obtain the modified zinc oxide; The silanization treatment conditions include: fully dissolving 40-50 parts of γ-glycidyloxypropyltrimethoxysilane in a mixture of 400-450 parts of anhydrous ethanol and 50-100 parts of deionized water, then adding 6-8 parts of commercially available aluminum oxide and ultrasonically dispersing the mixture uniformly, stirring and refluxing at 76-80° C. for 2-4 hours, washing with water, vacuum drying, and grinding.

2. The method for preparing a wear-resistant ceramic coating according to claim 1, characterized in that: The particle size of the commercially available alumina is 20-100 nm.

3. The method for preparing a wear-resistant ceramic coating according to claim 1, characterized in that: The gelation reaction conditions include: stirring at 170-180° C. for 4-8 minutes, and standing at room temperature for 2-3 hours after white turbidity appears.

4. The method for preparing a wear-resistant ceramic coating according to claim 1, characterized in that: The preparation method of the magnetic carbon nanotubes comprises: dissolving 40 to 50 parts by weight of ferric chloride and 6 to 8 parts of ferrous chloride in 500 to 600 parts of deionized water, then adding 10 to 16 parts of carboxylated carbon nanotubes for ultrasonic dispersion, and then adding ammonia water and sodium citrate for hydrothermal reaction to obtain the magnetic carbon nanotubes.

5. The method for preparing a wear-resistant ceramic coating according to claim 4, characterized in that: The specific steps of the hydrothermal reaction include: adjusting the pH to 8.2-8.8 with ammonia water with a mass concentration of 4-6%, heating to 70-80°C and stirring for 30-40 minutes, adding 16-20 parts of sodium citrate and reacting at a constant temperature of 70-80°C for 90-100 minutes, cooling to room temperature, magnetic separation, water washing, and drying.

6. The method for preparing a wear-resistant ceramic coating according to claim 1, characterized in that: The pretreatment conditions in step S3 include: removing the oxide layer and rust spots on the surface of the metal substrate using silicon carbide sandpaper, ultrasonic cleaning, and drying.

7. A wear-resistant ceramic coating, characterized in that ， Prepared according to the method according to any one of claims 1 to 6.

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