Corrosion and wear resistant epoxy coating and method of making same

Abstract

This invention discloses a corrosion-resistant and wear-resistant epoxy coating, which is made from the following raw materials in parts by weight: 1-5 parts carbon nanotubes, 5-10 parts chopped carbon fibers, 10-20 parts silicon carbide powder, 80-150 parts dimethylformamide solvent, 100-200 parts epoxy resin, 100-200 parts curing agent, and 1-2 parts leveling agent. This invention also discloses a method for preparing the corrosion-resistant and wear-resistant epoxy coating, involving surface modification of carbon nanotubes, silicon carbide, and chopped carbon fibers; preparation of a composite modified epoxy coating of carbon nanotubes / chopped carbon fibers / silicon carbide; and preparation of the corrosion-resistant and wear-resistant epoxy coating using the composite modified epoxy coating. The epoxy coating prepared by this invention can give the coating properties such as corrosion resistance, wear resistance, and crack resistance, greatly improving the service life of the coating in complex environments, and has important theoretical significance and engineering application value.

Description

Technical Field

[0001] This invention belongs to the field of surface engineering technology, specifically relating to corrosion-resistant and wear-resistant epoxy coatings, and also to a method for preparing corrosion-resistant and wear-resistant epoxy coatings. Background Technology

[0002] Applying organic coatings to the surface of equipment is currently the main protective measure for marine equipment, and epoxy resin coatings are an excellent choice for marine equipment protection due to their excellent adhesion, water resistance, and low cost. Epoxy resin coatings use epoxy resin as the main film-forming substance, combined with reinforcing phases, auxiliary fillers, and additives. Because there are many types of epoxy resins and reinforcing materials, anti-corrosion coatings suitable for various corrosive environments can be made, and epoxy resin anti-corrosion coatings are currently the most widely used anti-corrosion coatings in the world. However, epoxy resins also have some drawbacks, such as poor strength and wear resistance, susceptibility to aging and cracking, lack of toughness, and their inherent corrosion resistance cannot meet the requirements of marine equipment.

[0003] Existing epoxy coating modification and preparation technologies mainly improve the corrosion resistance of epoxy resin by adding inorganic nanofillers such as glass flakes, carbon nanotubes, and graphene, or by adding molybdenum disulfide to reduce the coefficient of friction or by adding hard reinforcing phases such as alumina and tungsten carbide to improve the wear resistance. However, most of these technologies only target specific corrosion or wear resistance improvements and do not fundamentally address the comprehensive requirements for corrosion resistance, wear resistance, and high toughness of epoxy resin coatings in complex and harsh marine environments such as high salt, high humidity, strong ultraviolet radiation, seawater erosion, and friction.

[0004] Carbon nanotubes possess nanoscale characteristics and excellent chemical stability; therefore, doping them into coatings typically improves the coating's corrosion resistance and bonding strength. Silicon carbide exhibits extremely high hardness and stability, and as a filler, it can enhance the hardness and wear resistance of epoxy resin coatings. Short-cut carbon fibers possess high strength and stiffness; when added to the resin matrix as a reinforcement, the resin can transfer stress to the carbon fibers when external stress is applied to the resin coating, significantly improving the resin's mechanical properties. Summary of the Invention

[0005] The purpose of this invention is to provide a corrosion-resistant and wear-resistant epoxy coating, which solves the problems of low hardness, poor corrosion resistance and wear resistance of traditional epoxy coatings.

[0006] Another object of the present invention is to provide a method for preparing a corrosion-resistant and wear-resistant epoxy coating.

[0007] The first technical solution adopted in this invention is a corrosion-resistant and wear-resistant epoxy coating, which is made from the following raw materials in parts by weight: 1-5 parts carbon nanotubes, 5-10 parts chopped carbon fibers, 10-20 parts silicon carbide powder, 80-150 parts dimethylformamide solvent, 100-200 parts epoxy resin, 100-200 parts curing agent, and 1-2 parts leveling agent; the epoxy resin is E44; the curing agent is polyamide 650; and the leveling agent is BYK306.

[0008] Another technical solution adopted in this invention is: the preparation method of the above-mentioned corrosion-resistant and wear-resistant epoxy coating, the specific steps of which are as follows:

[0009] Step 1, Surface modification of carbon nanotubes

[0010] Step 1.1: Prepare a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, add carbon nanotubes, and react with ultrasonic vibration. After filtration, wash the carbon nanotubes with deionized water, and finally obtain carboxylated carbon nanotubes after filtration and drying.

[0011] Step 1.2: Dissolve carboxylated carbon nanotubes in a tris(hydroxymethyl)aminomethane buffer solution, and sonicate until homogeneous to obtain an aqueous suspension of carbon nanotubes. Then, add dopamine hydrochloride, mechanically stir to ensure complete reaction, and filter to obtain polydopamine-coated carbon nanotubes. Wash the polydopamine-coated carbon nanotubes several times with deionized water, and finally dry them thoroughly in a vacuum drying oven.

[0012] Step 1.3: Polydopamine-coated carbon nanotubes are added to hydrochloric acid and aniline, and the mixture is mechanically stirred to form a homogeneous suspension. Then, ammonium persulfate solution is added to complete the oxidative polymerization reaction. The precipitate is washed several times with deionized water and vacuum dried to obtain polyaniline-coated carbon nanotubes.

[0013] Step 2, Surface modification of silicon carbide and chopped carbon fibers

[0014] Step 2.1: Prepare an ethanol-water solution, then add a silane coupling agent and sonicate.

[0015] Step 2.2: Disperse silicon carbide and chopped carbon fibers in xylene solution respectively, and homogenize them by ultrasonic oscillation to obtain silicon carbide and chopped carbon fiber solutions respectively.

[0016] Step 2.3: After reacting the solution obtained in step 2.2 with the solution obtained in step 2.1, the resulting silicon carbide and chopped carbon fibers are washed with alcohol and then vacuum dried.

[0017] Step 3, Preparation of carbon nanotube / chopped carbon fiber / silicon carbide composite modified epoxy coating

[0018] Surface-modified carbon nanotubes, chopped carbon fibers, and silicon carbide were added to dimethylformamide solvent and ultrasonically vibrated. Then, epoxy resin was added and mechanically stirred to uniformly disperse the carbon nanotubes, chopped carbon fibers, and silicon carbide into the epoxy resin coating.

[0019] Step 4, Preparation of corrosion-resistant and wear-resistant epoxy coating

[0020] Add curing agent and leveling agent to the epoxy resin coating prepared in step 3, and mix thoroughly by mechanical stirring. Then, evacuate the mixture in a vacuum drying oven to eliminate air bubbles generated during stirring. Finally, apply the mixture to a metal substrate and cure to obtain a corrosion-resistant and wear-resistant epoxy coating.

[0021] The invention is further characterized in that,

[0022] Furthermore, in step 1, the carbon nanotube has an outer diameter of (8–30) nm, an inner diameter of (3–10) nm, and a length of (3–30) μm.

[0023] Further, in step 1.1, the ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid solution is 3:1, the concentration of concentrated sulfuric acid is (95-98)%, and the concentration of concentrated nitric acid is (65-68)%.

[0024] Furthermore, in step 1.1, the ultrasonic oscillation time is (0.5~1)h.

[0025] Further, in step 1.1, the carbon nanotubes are filtered using a vacuum filter and dried at (50-80)℃ to obtain carboxylated carbon nanotubes.

[0026] Furthermore, in step 1.2, the molar amount of the tris(hydroxymethyl)aminomethane buffer solution is 10 mM, and the pH value is 8.5.

[0027] Furthermore, in step 1.2, the ultrasonic oscillation time is (0.5~1)h.

[0028] Furthermore, in step 1.2, the mechanical stirring speed is 300 r / min, and the stirring time is (10-24) hours.

[0029] Furthermore, in step 1.2, the drying temperature in the vacuum drying oven is (50~80)℃, and the drying time is (6~12)h.

[0030] Furthermore, in step 1.3, the concentration of hydrochloric acid is 0.5 mol / L.

[0031] Furthermore, in step 1.3, the oxidative polymerization reaction is carried out in an ice bath for 4 to 10 hours to complete.

[0032] Furthermore, in step 1.3, the drying temperature in the vacuum drying oven is (50~80)℃, and the drying time is (6~12)h.

[0033] Furthermore, in step 2.1, the volume ratio of ethanol to deionized water is 4:1 (V(C2H5OH):V(H2O)=4:1).

[0034] Furthermore, in step 2.1, the silane coupling agent is KH560.

[0035] Furthermore, in step 2.1, the ultrasonic oscillation time is (0.5~1)h.

[0036] Furthermore, in step 2.2, the silicon carbide particle size is (5-75) μm.

[0037] Furthermore, in step 2.2, the chopped carbon fiber has a diameter of 7 μm and a length of (0.1–0.5) mm.

[0038] Furthermore, in step 2.2, the ultrasonic oscillation time is (0.5~1)h.

[0039] Furthermore, in step 2.3, the reaction temperature is (50~80)℃ and the reaction time is (0.5~1)h.

[0040] Furthermore, in step 2.3, the drying temperature in the vacuum drying oven is (50~80)℃, and the drying time is (6~12)h.

[0041] Furthermore, in step 3, the ultrasonic oscillation time is (0.5–1) h.

[0042] Furthermore, in step 3, the epoxy resin is E44.

[0043] Furthermore, in step 3, the mechanical stirring speed is 200 r / min, and the mechanical stirring time is (0.5~1) h.

[0044] Furthermore, in step 4, the curing agent is polyamide 650.

[0045] Furthermore, in step 4, the leveling agent is BYK306.

[0046] Furthermore, in step 4, the curing process involves drying at room temperature for 12–24 hours, followed by drying in a vacuum oven at 80°C for 4–8 hours.

[0047] The surface modification mechanism of carbon nanotubes in this invention:

[0048] The spontaneous oxidative polymerization process of dopamine: In aqueous solution, the catechol group of dopamine is easily oxidized to generate dopaquinone compound with catechol structure. A disproportionation reaction occurs between dopamine and dopaquinone to generate semiquinone free radicals. The semiquinone free radicals couple to form cross-linked bonds, and at the same time, a tightly attached cross-linked composite layer is formed on the surface of carbon nanotubes.

[0049] Polymerization process of polyaniline: Polydopamine-coated carbon nanotubes are added to hydrochloric acid and aniline, and the mixture is mechanically stirred to form a homogeneous suspension. Then, ammonium persulfate solution is added. The decomposition of ammonium persulfate produces unstable free radicals SO4-, which rapidly complete the oxidative polymerization reaction, forming a polyaniline layer on the polydopamine-coated carbon nanotubes. The modified polyaniline can better coat the surface of the carbon nanotubes; the polyaniline layer has good thermal stability, thereby improving the corrosion resistance of epoxy resin coatings.

[0050] The beneficial effects of this invention are:

[0051] 1. This invention uses carbon nanotubes to modify epoxy coatings. The polyaniline-coated carbon nanotubes can greatly improve the corrosion resistance of epoxy resin coatings.

[0052] 2. Silicon carbide has high hardness. When added to epoxy resin as a filler, it can increase the hardness and strength of the epoxy resin coating and improve the wear resistance of the coating.

[0053] 3. Short-cut carbon fibers can increase the toughness of epoxy resin coatings. Randomly interlaced short-cut carbon fibers can improve the crack resistance of epoxy coatings and prevent the shedding of silicon carbide particles.

[0054] 4. The formation of a multi-scale mixed reinforcing phase by nanoscale carbon nanotubes, micron-scale silicon carbide, and submillimeter-scale short-cut carbon fibers is beneficial for stress dispersion, reducing stress concentration, and improving the overall mechanical properties of the coating.

[0055] In summary, the epoxy coating prepared by this invention can combine corrosion resistance, wear resistance, and crack resistance, greatly improving the service life of the coating in complex environments, and has important theoretical significance and engineering application value. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the corrosion-resistant and wear-resistant epoxy coating structure of the present invention;

[0057] In the figure, 1. Corrosion-resistant and wear-resistant epoxy coating, 2. Metal substrate, 3. Carbon nanotubes, 4. Silicon carbide, 5. Short-cut carbon fibers. Detailed Implementation

[0058] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0059] The corrosion-resistant and wear-resistant epoxy coating of this invention comprises 1-5 parts carbon nanotubes, 5-10 parts chopped carbon fibers, 10-20 parts silicon carbide powder, 80-150 parts dimethylformamide solvent, 100-200 parts epoxy resin, 100-200 parts curing agent, and 1-2 parts leveling agent. The structure of the corrosion-resistant and wear-resistant epoxy coating prepared by this invention is as follows: Figure 1 As shown, a corrosion-resistant and wear-resistant epoxy coating 1 is coated on a metal substrate 2; carbon nanotubes 3, silicon carbide 4, and short-cut carbon fibers 5 are used as reinforcing phases in the coating, and then coated onto the metal substrate to form a corrosion-resistant and wear-resistant epoxy coating 1, which improves the corrosion resistance and wear resistance of the coating, and its stiffness is also greatly improved.

[0060] Example 1

[0061] The specific steps for preparing the corrosion-resistant and wear-resistant epoxy coating of this invention are as follows:

[0062] Step 1, Surface modification of carbon nanotubes

[0063] Step 1.1: Prepare a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, add carbon nanotubes with an outer diameter of (20-30) nm, an inner diameter of (5-10) nm, and a length of (10-20) μm, and sonicate for 1 h. After filtration, wash three times with deionized water, and finally obtain carboxylated carbon nanotubes after filtration and drying at 80 °C.

[0064] The ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid solution is 3:1, with a concentration of concentrated sulfuric acid of (95-98)% and a concentration of concentrated nitric acid of (65-68)%.

[0065] Step 1.2: Dissolve the carboxylated carbon nanotubes obtained in Step 1.1 in a tris(hydroxymethyl)aminomethane buffer solution and sonicate for 1 hour to obtain an aqueous suspension of carbon nanotubes. Then add dopamine hydrochloride and stir mechanically for 12 hours. After filtration, obtain polydopamine-coated carbon nanotubes. Wash the polydopamine-coated carbon nanotubes three times with deionized water and dry them at 80°C.

[0066] The molar volume of the tris(hydroxymethyl)aminomethane buffer solution is 10 mM, and the pH value is 8.5.

[0067] Step 1.3: Polydopamine-coated carbon nanotubes were added to 0.5 mol / L hydrochloric acid and aniline, and the mixture was mechanically stirred to form a homogeneous suspension. Then, ammonium persulfate solution was added, and the reaction was carried out under ice bath conditions for 6 hours. The precipitate was washed three times with deionized water and dried at 80°C to obtain polyaniline-coated carbon nanotubes.

[0068] Step 2, Surface modification of silicon carbide and chopped carbon fibers

[0069] Step 2.1: Prepare an ethanol-water solution, then add silane coupling agent KH560, and sonicate for 1 hour.

[0070] The volume ratio of ethanol to deionized water is 4:1 (V(C2H5OH):V(H2O)=4:1).

[0071] Step 2.2: Silicon carbide with a particle size of (5-15) μm and short-cut carbon fibers with a diameter of 7 μm and a length of 0.5 mm are dispersed in xylene solution and homogenized by ultrasonic oscillation for 1 h to obtain silicon carbide and short-cut carbon fiber solutions respectively.

[0072] Step 2.3: The solution obtained in step 2.2 is added to the solution obtained in step 2.1 and reacted at 60°C for 1 hour. The resulting silicon carbide and short-cut carbon fibers are filtered, washed with alcohol, and then vacuum dried at 60°C for 8 hours.

[0073] Step 3, Preparation of carbon nanotube / chopped carbon fiber / silicon carbide composite modified epoxy coating

[0074] Two parts of surface-modified carbon nanotubes, five parts of chopped carbon fibers, and ten parts of silicon carbide were added to 100 parts of dimethylformamide solvent and ultrasonically vibrated for 1 hour. Then, 100 parts of epoxy resin E44 were added and mechanically stirred for 1 hour at a speed of 200 r / min to uniformly disperse the carbon nanotubes, chopped carbon fibers, and silicon carbide into the epoxy resin coating.

[0075] Step 4, Preparation of corrosion-resistant and wear-resistant epoxy coating

[0076] Add 100 parts of polyamide 650 curing agent and 1 part of BYK306 leveling agent to the epoxy resin coating prepared in step 3, and mix thoroughly by mechanical stirring. Then, evacuate the mixture in a vacuum drying oven to eliminate air bubbles generated during stirring. Finally, brush the mixture onto a steel substrate and allow it to dry at room temperature for 24 hours to achieve surface dryness. Then, cure it by drying in a vacuum oven at 80°C for 8 hours to obtain a corrosion-resistant and wear-resistant epoxy coating.

[0077] Example 2

[0078] Step 1, Surface modification of carbon nanotubes

[0079] Step 1.1: Prepare a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, add carbon nanotubes with an outer diameter of (20-30) nm, an inner diameter of (5-10) nm, and a length of (10-20) μm, and sonicate for 1 h. After filtration, wash three times with deionized water, and finally obtain carboxylated carbon nanotubes after filtration and drying at 80 °C.

[0080] The ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid solution is 3:1, with a concentration of concentrated sulfuric acid of (95-98)% and a concentration of concentrated nitric acid of (65-68)%.

[0081] Step 1.2: Dissolve the carboxylated carbon nanotubes obtained in Step 1.1 in a tris(hydroxymethyl)aminomethane buffer solution and sonicate for 1 hour to obtain an aqueous suspension of carbon nanotubes. Then add dopamine hydrochloride and stir mechanically for 12 hours. After filtration, obtain polydopamine-coated carbon nanotubes. Wash the polydopamine-coated carbon nanotubes three times with deionized water and dry them at 80°C.

[0082] The molar volume of the tris(hydroxymethyl)aminomethane buffer solution is 10 mM, and the pH value is 8.5.

[0083] Step 1.3: Polydopamine-coated carbon nanotubes were added to 0.5 mol / L hydrochloric acid and aniline, and the mixture was mechanically stirred to form a homogeneous suspension. Then, ammonium persulfate solution was added, and the reaction was carried out under ice bath conditions for 6 hours. The precipitate was washed three times with deionized water and dried at 80°C to obtain polyaniline-coated carbon nanotubes.

[0084] Step 2, Surface modification of silicon carbide and chopped carbon fibers

[0085] Step 2.1: Prepare an ethanol-water solution, then add silane coupling agent KH560, and sonicate for 1 hour.

[0086] The volume ratio of ethanol to deionized water is 4:1 (V(C2H5OH):V(H2O)=4:1).

[0087] Step 2.2: Silicon carbide with a particle size of (5-15) μm and short-cut carbon fibers with a diameter of 7 μm and a length of 0.5 mm are dispersed in xylene solution and homogenized by ultrasonic oscillation for 1 h to obtain silicon carbide and short-cut carbon fiber solutions respectively.

[0088] Step 2.3: The solution obtained in step 2.2 is added to the solution obtained in step 2.1 and reacted at 60°C for 1 hour. The resulting silicon carbide and short-cut carbon fibers are filtered, washed with alcohol, and then vacuum dried at 60°C for 8 hours.

[0089] Step 3, Preparation of carbon nanotube / chopped carbon fiber / silicon carbide composite modified epoxy coating

[0090] Two parts of surface-modified carbon nanotubes, ten parts of chopped carbon fibers, and twenty parts of silicon carbide were added to 100 parts of dimethylformamide solvent and ultrasonically vibrated for 1 hour. Then, 100 parts of epoxy resin E44 were added and mechanically stirred for 1 hour at a speed of 200 r / min to uniformly disperse the carbon nanotubes, chopped carbon fibers, and silicon carbide into the epoxy resin coating.

[0091] Step 4, Preparation of corrosion-resistant and wear-resistant epoxy coating

[0092] Add 100 parts of polyamide 650 curing agent and 1 part of BYK306 leveling agent to the epoxy resin coating prepared in step 3, and mix thoroughly by mechanical stirring. Then, evacuate the mixture in a vacuum drying oven to eliminate air bubbles generated during stirring. Finally, brush the mixture onto a steel substrate and allow it to dry at room temperature for 24 hours to achieve surface dryness. Then, cure it by drying in a vacuum oven at 80°C for 8 hours to obtain a corrosion-resistant and wear-resistant epoxy coating.

[0093] Example 3

[0094] Step 1, Surface modification of carbon nanotubes

[0095] Step 1.1: Prepare a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, add carbon nanotubes with an outer diameter of (20-30) nm, an inner diameter of (5-10) nm, and a length of (10-20) μm, and sonicate for 1 h. After filtration, wash three times with deionized water, and finally obtain carboxylated carbon nanotubes after filtration and drying at 80 °C.

[0096] The ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid solution is 3:1, with a concentration of concentrated sulfuric acid of (95-98)% and a concentration of concentrated nitric acid of (65-68)%.

[0097] Step 1.2: Dissolve the carboxylated carbon nanotubes obtained in Step 1.1 in a tris(hydroxymethyl)aminomethane buffer solution and sonicate for 1 hour to obtain an aqueous suspension of carbon nanotubes. Then add dopamine hydrochloride and stir mechanically for 12 hours. After filtration, obtain polydopamine-coated carbon nanotubes. Wash the polydopamine-coated carbon nanotubes three times with deionized water and dry them at 80°C.

[0098] The molar volume of the tris(hydroxymethyl)aminomethane buffer solution is 10 mM, and the pH value is 8.5.

[0099] Step 1.3: Polydopamine-coated carbon nanotubes were added to 0.5 mol / L hydrochloric acid and aniline, and the mixture was mechanically stirred to form a homogeneous suspension. Then, ammonium persulfate solution was added, and the reaction was carried out under ice bath conditions for 6 hours. The precipitate was washed three times with deionized water and dried at 80°C to obtain polyaniline-coated carbon nanotubes.

[0100] Step 2, Surface modification of silicon carbide and chopped carbon fibers

[0101] Step 2.1: Prepare an ethanol-water solution, then add silane coupling agent KH560, and sonicate for 1 hour.

[0102] The volume ratio of ethanol to deionized water is 4:1 (V(C2H5OH):V(H2O)=4:1).

[0103] Step 2.2: Silicon carbide with a particle size of (5-15) μm and short-cut carbon fibers with a diameter of 7 μm and a length of 0.5 mm are dispersed in xylene solution and homogenized by ultrasonic oscillation for 1 h to obtain silicon carbide and short-cut carbon fiber solutions respectively.

[0104] Step 2.3: The solution obtained in step 2.2 is added to the solution obtained in step 2.1 and reacted at 60°C for 1 hour. The resulting silicon carbide and short-cut carbon fibers are filtered, washed with alcohol, and then vacuum dried at 60°C for 8 hours.

[0105] Step 3, Preparation of carbon nanotube / chopped carbon fiber / silicon carbide composite modified epoxy coating

[0106] Four parts of surface-modified carbon nanotubes, eight parts of chopped carbon fibers, and twelve parts of silicon carbide were added to 100 parts of dimethylformamide solvent and ultrasonically vibrated for 1 hour. Then, 150 parts of epoxy resin E44 were added and mechanically stirred for 1 hour at a speed of 200 r / min to uniformly disperse the carbon nanotubes, chopped carbon fibers, and silicon carbide into the epoxy resin coating.

[0107] Step 4, Preparation of corrosion-resistant and wear-resistant epoxy coating

[0108] Add 150 parts of polyamide 650 curing agent and 1.5 parts of BYK306 leveling agent to the epoxy resin coating prepared in step 3, and mix thoroughly by mechanical stirring. Then, evacuate the mixture in a vacuum drying oven to eliminate air bubbles generated during stirring. Finally, apply the mixture to a steel substrate and allow it to dry at room temperature for 24 hours to achieve surface dryness. Then, cure it by drying in a vacuum oven at 80°C for 8 hours to obtain a corrosion-resistant and wear-resistant epoxy coating.

[0109] Example 4

[0110] Step 1, Surface modification of carbon nanotubes

[0111] Step 1.1: Prepare a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, add carbon nanotubes with an outer diameter of (20-30) nm, an inner diameter of (5-10) nm, and a length of (10-20) μm, and sonicate for 1 h. After filtration, wash three times with deionized water, and finally obtain carboxylated carbon nanotubes after filtration and drying at 80 °C.

[0112] The ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid solution is 3:1, with a concentration of concentrated sulfuric acid of (95-98)% and a concentration of concentrated nitric acid of (65-68)%.

[0113] Step 1.2: Dissolve the carboxylated carbon nanotubes obtained in Step 1.1 in a tris(hydroxymethyl)aminomethane buffer solution and sonicate for 1 hour to obtain an aqueous suspension of carbon nanotubes. Then add dopamine hydrochloride and stir mechanically for 12 hours. After filtration, obtain polydopamine-coated carbon nanotubes. Wash the polydopamine-coated carbon nanotubes three times with deionized water and dry them at 80°C.

[0114] The molar volume of the tris(hydroxymethyl)aminomethane buffer solution is 10 mM, and the pH value is 8.5.

[0115] Step 1.3: Polydopamine-coated carbon nanotubes were added to 0.5 mol / L hydrochloric acid and aniline, and the mixture was mechanically stirred to form a homogeneous suspension. Then, ammonium persulfate solution was added, and the reaction was carried out under ice bath conditions for 6 hours. The precipitate was washed three times with deionized water and dried at 80°C to obtain polyaniline-coated carbon nanotubes.

[0116] Step 2, Surface modification of silicon carbide and chopped carbon fibers

[0117] Step 2.1: Prepare an ethanol-water solution, then add silane coupling agent KH560, and sonicate for 1 hour.

[0118] The volume ratio of ethanol to deionized water is 4:1 (V(C2H5OH):V(H2O)=4:1).

[0119] Step 2.2: Silicon carbide with a particle size of (5-15) μm and short-cut carbon fibers with a diameter of 7 μm and a length of 0.5 mm are dispersed in xylene solution and homogenized by ultrasonic oscillation for 1 h to obtain silicon carbide and short-cut carbon fiber solutions respectively.

[0120] Step 2.3: The solution obtained in step 2.2 is added to the solution obtained in step 2.1 and reacted at 60°C for 1 hour. The resulting silicon carbide and short-cut carbon fibers are filtered, washed with alcohol, and then vacuum dried at 60°C for 8 hours.

[0121] Step 3, Preparation of carbon nanotube / chopped carbon fiber / silicon carbide composite modified epoxy coating

[0122] Five parts of surface-modified carbon nanotubes, ten parts of chopped carbon fibers, and twenty parts of silicon carbide were added to 150 parts of dimethylformamide solvent and ultrasonically vibrated for 1 hour. Then, 200 parts of epoxy resin E44 were added and mechanically stirred for 1 hour at a speed of 200 r / min to uniformly disperse the carbon nanotubes, chopped carbon fibers, and silicon carbide into the epoxy resin coating.

[0123] Step 4, Preparation of corrosion-resistant and wear-resistant epoxy coating

[0124] Add 200 parts of polyamide 650 curing agent and 2 parts of BYK306 leveling agent to the epoxy resin coating prepared in step 3, and mix thoroughly by mechanical stirring. Then, evacuate the mixture in a vacuum drying oven to eliminate air bubbles generated during stirring. Finally, apply the mixture to a steel substrate and allow it to dry at room temperature for 24 hours to achieve surface dryness. Then, cure it in a vacuum oven at 80°C for 8 hours to obtain a corrosion-resistant and wear-resistant epoxy coating.

[0125] Example 5

[0126] Step 1, Surface modification of carbon nanotubes

[0127] Step 1.1: Prepare a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, add carbon nanotubes with an outer diameter of (20-30) nm, an inner diameter of (5-10) nm, and a length of (10-20) μm, and sonicate for 1 h. After filtration, wash three times with deionized water, and finally obtain carboxylated carbon nanotubes after filtration and drying at 80 °C.

[0128] The ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid solution is 3:1, with a concentration of concentrated sulfuric acid of (95-98)% and a concentration of concentrated nitric acid of (65-68)%.

[0129] Step 1.2: Dissolve the carboxylated carbon nanotubes obtained in Step 1.1 in a tris(hydroxymethyl)aminomethane buffer solution and sonicate for 1 hour to obtain an aqueous suspension of carbon nanotubes. Then add dopamine hydrochloride and stir mechanically for 12 hours. After filtration, obtain polydopamine-coated carbon nanotubes. Wash the polydopamine-coated carbon nanotubes three times with deionized water and dry them at 80°C.

[0130] The molar volume of the tris(hydroxymethyl)aminomethane buffer solution is 10 mM, and the pH value is 8.5.

[0131] Step 1.3: Polydopamine-coated carbon nanotubes were added to 0.5 mol / L hydrochloric acid and aniline, and the mixture was mechanically stirred to form a homogeneous suspension. Then, ammonium persulfate solution was added, and the reaction was carried out under ice bath conditions for 6 hours. The precipitate was washed three times with deionized water and dried at 80°C to obtain polyaniline-coated carbon nanotubes.

[0132] Step 2, Surface modification of silicon carbide and chopped carbon fibers

[0133] Step 2.1: Prepare an ethanol-water solution, then add silane coupling agent KH560, and sonicate for 1 hour.

[0134] The volume ratio of ethanol to deionized water is 4:1 (V(C2H5OH):V(H2O)=4:1).

[0135] Step 2.2: Silicon carbide with a particle size of (5-15) μm and short-cut carbon fibers with a diameter of 7 μm and a length of 0.5 mm are dispersed in xylene solution and homogenized by ultrasonic oscillation for 1 h to obtain silicon carbide and short-cut carbon fiber solutions respectively.

[0136] Step 2.3: The solution obtained in step 2.2 is added to the solution obtained in step 2.1 and reacted at 60°C for 1 hour. The resulting silicon carbide and short-cut carbon fibers are filtered, washed with alcohol, and then vacuum dried at 60°C for 8 hours.

[0137] Step 3, Preparation of carbon nanotube / chopped carbon fiber / silicon carbide composite modified epoxy coating

[0138] Two parts of surface-modified carbon nanotubes, ten parts of chopped carbon fibers, and ten parts of silicon carbide were added to 100 parts of dimethylformamide solvent and ultrasonically vibrated for 1 hour. Then, 150 parts of epoxy resin E44 were added and mechanically stirred for 1 hour at a speed of 200 r / min to uniformly disperse the carbon nanotubes, chopped carbon fibers, and silicon carbide into the epoxy resin coating.

[0139] Step 4, Preparation of corrosion-resistant and wear-resistant epoxy coating

[0140] Add 150 parts of polyamide 650 curing agent and 1.5 parts of BYK306 leveling agent to the epoxy resin coating prepared in step 3, and mix thoroughly by mechanical stirring. Then, evacuate the mixture in a vacuum drying oven to eliminate air bubbles generated during stirring. Finally, apply the mixture to a steel substrate and allow it to dry at room temperature for 24 hours to achieve surface dryness. Then, cure it by drying in a vacuum oven at 80°C for 8 hours to obtain a corrosion-resistant and wear-resistant epoxy coating.

[0141] The comparison results of the wear resistance of the coatings prepared in the embodiments of the present invention are as follows:

[0142]

[0143] The corrosion resistance comparison results are as follows:

[0144]

[0145] The performance verification results above show that the epoxy resin coating prepared by the method of the present invention has significantly better wear resistance and corrosion resistance than traditional epoxy resin coatings.

Claims

1. A corrosion-resistant and wear-resistant epoxy coating, characterized in that, It is made from the following raw materials in parts by weight: 1-5 parts carbon nanotubes, 5-10 parts chopped carbon fibers, 10-20 parts silicon carbide powder, 80-150 parts dimethylformamide solvent, 100-200 parts epoxy resin, 100-200 parts curing agent, and 1-2 parts leveling agent. The surface modification method for the carbon nanotubes is as follows: Step 1.1: Prepare a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, add carbon nanotubes, sonicate for 0.5-1 h, filter, wash the carbon nanotubes with deionized water, and finally filter and dry at 50-80℃ to obtain carboxylated carbon nanotubes; the ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid solution is 3:1, the mass concentration of concentrated sulfuric acid is 95-98%, and the mass concentration of concentrated nitric acid is 65-68%; Step 1.2: Dissolve carboxylated carbon nanotubes in tris(hydroxymethyl)aminomethane buffer solution, sonicate for 0.5-1 h until homogeneous to obtain an aqueous suspension of carbon nanotubes, then add dopamine hydrochloride, mechanically stir to fully react, filter to obtain polydopamine-coated carbon nanotubes; wash the polydopamine-coated carbon nanotubes several times with deionized water, and finally dry them thoroughly in a vacuum drying oven; Step 1.3: Add polydopamine-coated carbon nanotubes to hydrochloric acid and aniline at a concentration of 0.5 mol / L, and mechanically stir to form a uniform suspension; then, add ammonium persulfate solution, and continue the oxidative polymerization reaction under ice bath for 4-10 hours; wash the precipitate several times with deionized water and vacuum dry to obtain polyaniline-coated carbon nanotubes; The method for surface modification of silicon carbide and chopped carbon fibers is as follows: Step 2.1: Prepare an ethanol-water solution with a volume ratio of ethanol to deionized water of 4:1; then add a silane coupling agent and ultrasonically vibrate. Step 2.2: Silicon carbide with a particle size of 5~75μm and short-cut carbon fibers with a diameter of 7μm and a length of 0.1~0.5mm are dispersed in xylene solution and homogenized by ultrasonic oscillation to obtain silicon carbide and short-cut carbon fiber solutions respectively. Step 2.3: After reacting the solution obtained in step 2.2 with the solution obtained in step 2.1, the resulting silicon carbide and chopped carbon fibers are washed with alcohol and then vacuum dried.

2. The corrosion-resistant and wear-resistant epoxy coating according to claim 1, characterized in that, The epoxy resin is E44; the curing agent is polyamide 650; and the leveling agent is BYK306.

3. A method for preparing a corrosion-resistant and wear-resistant epoxy coating, characterized in that, The specific steps are as follows: Step 1: Surface modification of carbon nanotubes; Step 2: Surface modification of silicon carbide and chopped carbon fibers; Step 3: Prepare a composite modified epoxy coating of carbon nanotubes / chopped carbon fibers / silicon carbide; Step 4: Prepare a corrosion-resistant and wear-resistant epoxy coating using the composite modified epoxy coating.

4. The method for preparing the corrosion-resistant and wear-resistant epoxy coating according to claim 3, characterized in that, Step 1 is as follows: Step 1.1: Prepare a mixed acid solution of concentrated sulfuric acid and concentrated nitric acid, add carbon nanotubes, sonicate for 0.5-1 h, filter, wash the carbon nanotubes with deionized water, and finally filter and dry at 50-80℃ to obtain carboxylated carbon nanotubes; the ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid solution is 3:1, the mass concentration of concentrated sulfuric acid is 95-98%, and the mass concentration of concentrated nitric acid is 65-68%; Step 1.2: Dissolve carboxylated carbon nanotubes in tris(hydroxymethyl)aminomethane buffer solution, sonicate for 0.5-1 h until homogeneous to obtain an aqueous suspension of carbon nanotubes, then add dopamine hydrochloride, mechanically stir to fully react, filter to obtain polydopamine-coated carbon nanotubes; wash the polydopamine-coated carbon nanotubes several times with deionized water, and finally dry them thoroughly in a vacuum drying oven; Step 1.3: Add polydopamine-coated carbon nanotubes to hydrochloric acid and aniline at a concentration of 0.5 mol / L and mechanically stir to form a uniform suspension; then, add ammonium persulfate solution and continue the oxidative polymerization reaction under ice bath for 4-10 hours; wash the precipitate several times with deionized water and vacuum dry to obtain polyaniline-coated carbon nanotubes.

5. The method for preparing the corrosion-resistant and wear-resistant epoxy coating according to claim 3, characterized in that, Step 2 is as follows: Step 2.1: Prepare an ethanol-water solution with a volume ratio of ethanol to deionized water of 4:1; then add a silane coupling agent and ultrasonically vibrate. Step 2.2: Silicon carbide with a particle size of 5~75μm and short-cut carbon fibers with a diameter of 7μm and a length of 0.1~0.5mm are dispersed in xylene solution and homogenized by ultrasonic oscillation to obtain silicon carbide and short-cut carbon fiber solutions respectively. Step 2.3: After reacting the solution obtained in step 2.2 with the solution obtained in step 2.1, the resulting silicon carbide and chopped carbon fibers are washed with alcohol and then vacuum dried.

6. The method for preparing the corrosion-resistant and wear-resistant epoxy coating according to claim 3, characterized in that, Step 3 is as follows: Add the surface-modified carbon nanotubes, chopped carbon fibers, and silicon carbide to dimethylformamide solvent and sonicate for 0.5 to 1 hour. Then add epoxy resin and stir mechanically to uniformly disperse the carbon nanotubes, chopped carbon fibers, and silicon carbide into the epoxy resin coating.

7. The method for preparing the corrosion-resistant and wear-resistant epoxy coating according to claim 4, characterized in that, Step 4 is as follows: Add curing agent and leveling agent to the epoxy resin coating prepared in step 3, mix evenly by mechanical stirring, and evacuate in a vacuum drying oven to eliminate air bubbles generated by stirring; finally, brush it onto the metal substrate, and obtain a corrosion-resistant and wear-resistant epoxy coating after curing.

8. The method for preparing the corrosion-resistant and wear-resistant epoxy coating according to claim 4, characterized in that, The carbon nanotubes mentioned in step 1 have an outer diameter of 8~30nm, an inner diameter of 3~10nm, and a length of 3~30μm.

9. The method for preparing the corrosion-resistant and wear-resistant epoxy coating according to claim 4, characterized in that, In step 1.2, the molar amount of the tris(hydroxymethyl)aminomethane buffer solution is 10 mM, and the pH value is 8.

5.

10. The method for preparing the corrosion-resistant and wear-resistant epoxy coating according to claim 4, characterized in that, In step 2.1, the silane coupling agent is KH560; in step 3, the epoxy resin is E44; in step 4, the curing agent is polyamide 650 and the leveling agent is BYK306; the curing process in step 4 is to dry at room temperature for 12~24h, and then dry in a vacuum oven at 80℃ for 4~8h.

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