Anticorrosion, wear-resistant and high-temperature-resistant coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of protective coatings, and discloses an anti-corrosion, wear-resistant and high-temperature-resistant coating as well as a preparation method and application thereof. The coating comprises a primer, a middle transition layer and a finish; the raw materials of the primer comprise a primer material and a primer curing agent component; the primer material comprises modified epoxy phenolic resin, a primer functional filler, a first mixed solvent, a high-temperature-resistant coupling agent and an anti-settling agent; the raw materials of the middle transition layer comprise a middle transition layer material and a middle curing agent component; the materials of the middle transition layer comprise polyimide modified epoxy resin, a wear-resistant filler, a reactive diluent, a carbon nanotube, a first dispersant and a compatilizer; the raw materials of the finishing paint comprise a finishing paint material and a finishing paint curing agent component; the finishing paint material comprises organic silicon modified fluorocarbon resin, finishing paint functional filler, a second mixed solvent, a second dispersing agent and a flatting agent. According to the invention, a resin-based composite coating system is synergistically designed through multi-phase materials, so that optimal balance of corrosion resistance, wear resistance, toughness and high temperature resistance of the coating is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of protective coatings, and more specifically, relates to an anti-corrosion, wear-resistant and high-temperature resistant coating and a preparation method and application thereof. Background Art

[0002] In oil, natural gas and geological exploration operations, drill pipes, as the core components of the drill string system, are exposed to high temperature, high pressure, highly corrosive media (such as hydrogen sulfide-containing formation water, salt spray, acidic soil) and highly abrasive environments (such as rock cuttings impact and downhole gravel friction) for a long time, and are subjected to the combined effects of severe friction, alternating stress, corrosive media and high temperature.

[0003] Existing drill pipe protection technologies mainly use metal coatings (such as chrome plating, nickel-based alloy coatings), organic anti-corrosion coatings (such as epoxy resin, polyurethane coatings) or ceramic coatings (such as alumina, tungsten carbide thermal spraying). Among them:

[0004] Although metal coatings have good wear resistance, they have the following significant defects: the electroplating process is highly polluting and prone to hydrogen embrittlement risks; the difference in thermal expansion coefficients between the coating and the substrate makes it easy to peel off under high-temperature conditions; it is sensitive to local pitting corrosion and will cause accelerated corrosion once damaged.

[0005] Organic anti-corrosion coatings are easy to apply and have excellent chemical resistance, but their hardness is generally lower than HB grade (usually <3H), and their wear rate in highly abrasive media such as quartz sand is as high as 10 -4 mm 3 / N·m level, which cannot meet the protection requirements of key wear parts such as drill pipe couplings and thickened transition zones, and has poor high temperature resistance and is prone to decomposition and failure under long-term high temperature.

[0006] Although the ceramic coating has high hardness (reaching HV1000 or above), it has poor toughness and high brittleness. It is prone to microcracks under frequent loading and unloading of the drill pipe and bending stress. Its porous structure (porosity > 5%) provides a channel for the penetration of corrosive media, leading to hidden corrosion of the substrate.

[0007] What is more serious is that the current drill pipe protection technology is difficult to solve the problem of accelerated corrosion during dynamic wear: when the coating surface is thinned due to wear, the corrosive medium will quickly invade the coating / substrate interface along the wear path, induce corrosion pits and accelerate coating peeling. This phenomenon is particularly serious in Cl-containing soils. - 、SO4 2- In addition, high temperature will accelerate the corrosion reaction rate, further exacerbating the failure of the coating.

[0008] Industry statistics indicate that approximately 65% ​​of drill pipe failures are due to the interaction of corrosion and wear, and existing single-function coatings are unable to effectively suppress this synergistic damage mechanism. In high-temperature environments, such as geothermal wells, the impact of high temperatures on coating performance must also be considered. Therefore, there is an urgent need to develop a composite coating for drill pipe that combines long-term corrosion protection, excellent wear resistance, high-temperature resistance, and ease of field repair to meet the demands of long-term service in complex operating conditions. Summary of the Invention

[0009] The present invention addresses the bottlenecks of existing technologies by providing a corrosion-resistant, wear-resistant, and high-temperature-resistant coating, as well as its preparation method and application. By collaboratively designing a resin-based composite coating system using multiphase materials, the present invention achieves an optimal balance of the coating's corrosion resistance, wear resistance, toughness, and high-temperature resistance. The result is a composite coating that combines long-lasting corrosion protection with excellent wear resistance and high-temperature resistance.

[0010] In order to achieve the above object, the first aspect of the present invention provides an anti-corrosion, wear-resistant and high-temperature resistant coating, the coating comprising a primer, an intermediate transition layer and a topcoat arranged in sequence from bottom to top;

[0011] The raw materials of the primer include: a primer material and a primer curing agent component; the primer material includes: a modified epoxy phenolic resin, a primer functional filler, a first mixed solvent, a high-temperature resistant coupling agent, and an anti-settling agent; the primer functional filler includes: flaky zinc powder, ferrophosphorus powder, and optional zinc oxide whiskers; the primer curing agent component includes: a cardanol-modified polyamide curing agent;

[0012] The raw materials of the intermediate transition layer include: intermediate transition layer material and intermediate curing agent component; the intermediate transition layer material includes: polyimide modified epoxy resin, wear-resistant filler, active diluent, carbon nanotubes, a first dispersant and a compatibilizer; the wear-resistant filler includes: fused alumina, silicon carbide and optionally silicon nitride; the intermediate curing agent component includes: polyamide curing agent;

[0013] The raw materials of the topcoat include: topcoat material and topcoat curing agent component; the topcoat material includes: organosilicon-modified fluorocarbon resin, topcoat functional filler, a second mixed solvent, a second dispersant and a leveling agent; the topcoat functional filler includes: glass flake powder, hydrophobically modified nano-silica and optional nano-cerium oxide; the topcoat curing agent component includes: isocyanate curing agent.

[0014] In the present invention, in order to improve the overall high-temperature resistance of the coating, the present invention screens and optimizes the materials of each layer, and uses high-temperature resistant inorganic materials and modified organic materials as much as possible.

[0015] In the present invention, the primer (ie, adhesion enhancing layer) provides strong metal adhesion (>18 MPa) and cathodic protection while enhancing high temperature resistance.

[0016] According to the present invention, preferably, based on the total weight of the primer material, the primer material includes: 40-50wt% of modified epoxy phenolic resin, 25-32wt% of flaky zinc powder, 8-10wt% of ferrophosphorus powder, 10-15wt% of a first mixed solvent, 1-3wt% of a high temperature resistant coupling agent, 1-2wt% of an anti-settling agent and 0-3wt% of zinc oxide whiskers.

[0017] In the present invention, the modified epoxy phenolic resin is preferably selected from DEN TM 431, epoxy value is 0.56-0.58, phenolic content is 15-25%.

[0018] In the present invention, as a preferred embodiment, the high temperature resistant coupling agent is a silane coupling agent. The present invention uses the high temperature resistant coupling agent to enhance the bonding strength between the primer functional filler and the substrate (such as oil well drill pipe), especially the bonding strength at high temperature.

[0019] In the present invention, a small amount of anti-settling agent is added to prevent the flake zinc powder and ferrophosphorus powder from settling, thereby improving storage stability and film-forming uniformity.

[0020] According to the present invention, preferably, the weight amount of the cardanol-modified polyamide curing agent is calculated and determined based on the epoxy value of the modified epoxy phenolic resin and the amine value of the cardanol-modified polyamide curing agent itself; preferably, the primer curing agent component further includes: a first mixed solvent; the weight amount of the first mixed solvent in the primer curing agent component is determined according to the viscosity requirement of the primer.

[0021] In the present invention, the intermediate transition layer (ie, the wear-resistant and thermal shock-resistant strengthening layer) can construct a high-hardness wear-resistant skeleton (preferably with a hardness of Hv450-550) to enhance the wear resistance and thermal shock resistance of the coating.

[0022] According to the present invention, preferably, based on the total weight of the intermediate transition layer material, the intermediate transition layer material includes: 45-55wt% of polyimide-modified epoxy resin, 20-27wt% of molten alumina, 6-10wt% of silicon carbide, 12-17wt% of active diluent, 0.5-1.5wt% of carbon nanotubes, 0.5-1wt% of compatibilizer, 0.5-1wt% of first dispersant and 0-3wt% of silicon nitride.

[0023] In the present invention, the polyimide-modified epoxy resin is obtained by blending polyimide and epoxy resin, wherein the ratio of polyimide to epoxy resin is 3:7, the relative molecular weight of the polyimide is 1500, the epoxy value of the epoxy resin is 0.18-0.22, the polyimide is preferably PMR-15, and the epoxy resin is preferably E-20.

[0024] In the present invention, the compatibilizer is used to avoid possible phase separation between polyimide and epoxy resin, thereby improving the resin compatibility; and the first dispersant can enhance the dispersion efficiency of the wear-resistant filler.

[0025] According to the present invention, preferably, the weight amount of the polyamide curing agent is calculated and determined based on the epoxy value of the epoxy resin of the polyimide-modified epoxy resin and the amine value of the polyamide curing agent itself; preferably, the intermediate curing agent component also includes: a reactive diluent; the weight amount of the reactive diluent in the intermediate curing agent component is determined based on the viscosity requirement of the intermediate transition layer.

[0026] In the present invention, the topcoat (ie, the anti-corrosion sealing layer) provides excellent anti-corrosion sealing performance, blocks the penetration of corrosive media, and has excellent high-temperature oxidation resistance.

[0027] According to the present invention, preferably, based on the total weight of the topcoat material, the topcoat material includes: 45-55wt% of organosilicon-modified fluorocarbon resin (fluorocarbon resin: organosilicon = 7:3), 27-38wt% of glass flake powder, 2-3wt% of hydrophobically modified nano-silica, 10-15wt% of a second mixed solvent, 0.5-1wt% of a second dispersant, 0.5-1wt% of a leveling agent and 0-2wt% of nano-cerium oxide; preferably, based on the total weight of the topcoat material, the topcoat material also includes: 0.5-1wt% of a defoaming agent.

[0028] In the present invention, since the preparation of the organosilicon-modified fluorocarbon resin needs to be carried out under the protection of an inert gas, it is usually prepared once and used multiple times, and this process will not be described in detail below.

[0029] In the present invention, the second dispersant can improve the dispersion efficiency of the functional filler in the topcoat.

[0030] In the present invention, adding a small amount of leveling agent can improve the leveling performance of the topcoat.

[0031] In the present invention, a fluorocarbon resin and organosilicon are added to a third container, and half the total amount of the second mixed solvent required for the topcoat material is added. Under inert gas protection, the reaction is carried out at 110-120°C and 800-1000 rpm for 2-3 hours to prepare an organosilicon-modified fluorocarbon resin. In the present invention, the ratio of fluorocarbon resin to organosilicon is 7:3. The fluorocarbon resin is preferably GK570, and the organosilicon is preferably DC-3074.

[0032] According to the present invention, preferably, the weight amount of the isocyanate curing agent is calculated and determined based on the hydroxyl equivalent of the fluorocarbon resin in the silicone-modified fluorocarbon resin and the NCO content of the isocyanate curing agent itself; preferably, the topcoat curing agent component also includes: a second mixed solvent; the weight amount of the second mixed solvent in the topcoat curing agent component is determined based on the viscosity requirement of the topcoat.

[0033] According to the present invention, preferably, the first mixed solvent comprises toluene, xylene and n-butanol, and the weight ratio of toluene, xylene and n-butanol is (3.5-4.5):(2.5-3.5):(2.5-3.5). More preferably, the weight ratio of toluene, xylene and n-butanol is 4:3:3.

[0034] According to the present invention, preferably, the particle size of the flaky zinc powder is 10-15 μm.

[0035] According to the present invention, preferably, the particle size of the ferrophosphorus powder is 5-8 μm.

[0036] According to the present invention, preferably, the reactive diluent comprises ethylene glycol butyl ether and propylene glycol methyl ether acetate, and the weight ratio of the ethylene glycol butyl ether to the propylene glycol methyl ether acetate is (5.5-6.5):(3.5-4.5).

[0037] According to the present invention, preferably, the particle size of the fused alumina is 80-120 mesh.

[0038] According to the present invention, preferably, the particle size of the silicon carbide is 200-400 mesh.

[0039] According to the present invention, preferably, the particle size of the silicon nitride is 200-400 mesh.

[0040] According to the present invention, preferably, the second mixed solvent comprises xylene, propylene glycol methyl ether acetate and cyclohexanone, and the weight ratio of xylene, propylene glycol methyl ether acetate and cyclohexanone is (5.0-6.0):(3.0-4.0):(1.0-2.0).

[0041] According to the present invention, preferably, the particle size of the glass flake powder is 20-30 μm.

[0042] According to the present invention, preferably, the particle size of the hydrophobically modified nano-silica is 30-50 nm.

[0043] According to the present invention, preferably, the particle size of the nano-cerium oxide is 30-50 nm.

[0044] According to the present invention, preferably, the dry film thickness of the primer is 40-50 μm.

[0045] According to the present invention, preferably, the dry film thickness of the intermediate transition layer is 130-160 μm.

[0046] According to the present invention, preferably, the dry film thickness of the topcoat is 60-80 μm.

[0047] A second aspect of the present invention provides a method for preparing the aforementioned anti-corrosion, wear-resistant, and high-temperature resistant coating, the method comprising the following steps:

[0048] S1: adding the modified epoxy phenolic resin and the first mixed solvent into a first container and mixing and dispersing them, then adding the anti-settling agent and the high temperature resistant coupling agent into the first container and mixing and dispersing them, and then adding the primer functional filler into the first container and mixing and dispersing them to obtain the primer material; mixing and dispersing the primer material with a cardanol modified polyamide curing agent to obtain a primer mixture system, filtering, coating, drying and curing to obtain a primer;

[0049] S2: adding the polyimide-modified epoxy resin and the reactive diluent to a second container and mixing and dispersing them, then adding the compatibilizer and the first dispersant to the second container and mixing and dispersing them, then adding the carbon nanotubes to the second container and mixing and dispersing them, then gradually adding the wear-resistant filler to the second container and mixing and dispersing them, and grinding to obtain an intermediate transition layer material; mixing and dispersing the intermediate transition layer material with the polyamide curing agent to obtain an intermediate transition layer mixed system, filtering, coating, and step-drying and curing to obtain an intermediate transition layer;

[0050] S3: Add the organosilicon-modified fluorocarbon resin and the second mixed solvent into a third container and mix and disperse them, then add the second dispersant and leveling agent into the third container and mix and disperse them, then add the hydrophobically modified nano-silica and optional nano-cerium oxide into the third container and mix and disperse them, then add the glass flake powder into the third container and mix and disperse them, grind to obtain the topcoat material; mix and disperse the topcoat material with an isocyanate curing agent to obtain a topcoat mixed system, filter, coat, dry and solidify to obtain a topcoat.

[0051] According to the present invention, preferably, the coating method is at least one of cold spraying, air spraying and brushing.

[0052] According to the present invention, preferably, in step S1:

[0053] The modified epoxy phenolic resin and the first mixed solvent are added to a first container and mixed and dispersed at 800-1000 rpm for 10-15 minutes, then the anti-settling agent and the high temperature resistant coupling agent are added to the first container and mixed and dispersed at 1000-1200 rpm for 10-15 minutes, and then the primer functional filler is added to the first container and mixed and dispersed at 2000-2200 rpm for 1.5-2 hours to obtain the primer material; the primer material is mixed and dispersed with a cardanol-modified polyamide curing agent at 1300-1500 rpm for 20-40 minutes to obtain a primer mixture system, which is filtered, coated, dried and solidified to obtain a primer;

[0054] The drying and curing includes a first stage and a second stage which are carried out continuously. The temperature of the first stage is 70-80°C and the time is 50-70 minutes. After the first stage is cured, the temperature is raised to the second stage at a rate of ≤5°C / min. The temperature of the second stage is 150-180°C and the time is 60-90 minutes.

[0055] According to the present invention, preferably, the primer material, the cardanol-modified polyamide curing agent and the first mixed solvent are mixed and dispersed together at 1300-1500 rpm for 20-40 minutes to obtain a primer mixture system that meets the viscosity requirements, and the mixture is filtered, coated, dried and cured to obtain a primer.

[0056] According to the present invention, preferably, in step S2:

[0057] The polyimide-modified epoxy resin and the reactive diluent are added to a second container and mixed and dispersed at 800-1000 rpm for 10-15 minutes, then the compatibilizer and the first dispersant are added to the second container and mixed and dispersed at 1000-1200 rpm for 10-15 minutes, then the carbon nanotubes are added to the second container and mixed and dispersed at 1800-2000 rpm for 10-15 minutes, then the wear-resistant filler is added to the second container in a gradient manner and mixed and dispersed at 1400-1500 rpm for 1.5-2 hours, and ground to obtain an intermediate transition layer material; the intermediate transition layer material is mixed and dispersed with the polyamide curing agent at 1000-1200 rpm for 20-40 minutes to obtain an intermediate transition layer mixed system, which is filtered, coated, dried and solidified to obtain an intermediate transition layer;

[0058] Gradual addition of the wear-resistant filler is to add the wear-resistant filler into the second container in batches, with the weight of each batch of wear-resistant filler being ≤ 5wt% of the total weight of the wear-resistant filler, and the batch interval being 4-6 minutes;

[0059] Grinding so that the fineness of the intermediate transition layer material is ≤50 μm;

[0060] The drying and curing process includes a first stage and a second stage which are carried out continuously. The temperature of the first stage is 80-85°C and the time is 40-60 minutes. After the first stage is cured, the temperature is raised to the second stage at a rate of ≤5°C / min. The temperature of the second stage is 120-125°C and the time is 60-90 minutes.

[0061] According to the present invention, preferably, the intermediate transition layer material, polyamide curing agent and reactive diluent are mixed and dispersed together at 1000-1200 rpm for 40-60 minutes to obtain an intermediate transition layer mixed system that meets the viscosity requirements, and then filtered, coated, dried and solidified to obtain the intermediate transition layer.

[0062] According to the present invention, preferably, in step S3:

[0063] Add the fluorocarbon resin and organosilicon to a third container, add half of the second mixed solvent required for the topcoat material, and react at 110-120° C. and 800-1000 rpm for 2-3 hours under inert gas protection to prepare the organosilicon-modified fluorocarbon resin; add the remaining second mixed solvent required for the topcoat material to the third container and mix and disperse at 800-1000 rpm for 10-15 minutes; then add the second dispersant and leveling agent to the third container and mix and disperse at 1000-1200 rpm for 10-15 minutes. in, then adding the hydrophobically modified nano-silica and optional nano-cerium oxide to the third container and mixing and dispersing them at 1800-2000rpm for 10-15min, then adding the glass flake powder to the third container and mixing and dispersing them at 1400-1500rpm for 1.5-2h, grinding to obtain the topcoat material; mixing and dispersing the topcoat material with an isocyanate curing agent at 1000-1200rpm for 40-60min to obtain a topcoat mixed system, filtering, coating, drying and curing to obtain a topcoat;

[0064] Grinding the topcoat material to a fineness of ≤40 μm;

[0065] The drying and curing includes a first stage and a second stage which are carried out continuously. The temperature of the first stage is 22-30°C and the time is 100-120 minutes. After the first stage is cured, the temperature is raised to the second stage at a rate of ≤5°C / min. The temperature of the second stage is 130-150°C and the time is 40-60 minutes.

[0066] According to the present invention, preferably, the topcoat material, isocyanate curing agent and second mixed solvent are mixed and dispersed together at 1000-1200 rpm for 40-60 minutes to obtain a topcoat mixed system that meets the viscosity requirements, and then filtered, coated, dried and solidified to obtain a topcoat.

[0067] The third aspect of the present invention provides the application of the anti-corrosion, wear-resistant and high-temperature resistant coating in the protection of oil well drill pipes; preferably, the protection includes using the anti-corrosion, wear-resistant and high-temperature resistant coating to coat the oil well drill pipes, and using the anti-corrosion, wear-resistant and high-temperature resistant coating to perform on-site repair of oil well drill pipes that have been worn during operation.

[0068] In the present invention, the coating step includes:

[0069] (1) Paint preparation

[0070] Primer: Epoxy phenolic resin + first mixed solvent pre-dispersion (800-1000rpm, 10-15min) → Add anti-settling agent and silane coupling agent and disperse (1000-1200rpm, 10-15min) → Slowly add primer functional filler and continue to disperse (2000-2200rpm, 1.5-2h) → Seal and set aside. Add cardanol modified polyamide curing agent in proportion before use (1300-1500rpm, 0.5h). The first mixed solvent can be added appropriately to adjust to the suitable viscosity for spraying. It can be used after filtering.

[0071] Intermediate transition layer: polyimide modified epoxy resin + active diluent dispersion (800-1000rpm, 10-15min) → add compatibilizer and first dispersant (1000-1200rpm, 10-15min) → add carbon nanotube dispersion (1800-2000rpm, 10-15min) → add wear-resistant filler in a gradient and continue to disperse (each time ≤5wt%, 1400-1500rpm, 1.5-2h (total time for mixing and dispersing all wear-resistant fillers)) → grind to a fineness of ≤50μm and seal for use. Add polyamide curing agent in proportion before use (1000-1200rpm, 0.5h). Active diluent can be added appropriately to adjust to a suitable viscosity for spraying. It can be used after filtering.

[0072] Topcoat: fluorocarbon resin + silicone + second mixed solvent dispersion (inert gas protection, 110-120 ° C, 800-1000 rpm, 2-3h) → add the remaining second mixed solvent dispersion (800-1000 rpm, 10-15min) → add the second dispersant, leveling agent (1000-1200 rpm, 10-15min) → add hydrophobically modified nano-silica and optional nano-cerium oxide dispersion (1800-2000 rpm, 10-15min) → add glass flake powder (1400-1500 rpm, 1.5-2h) → grind to a fineness of ≤40μm and seal for use. Add isocyanate curing agent in proportion before use (1000-1200 rpm, 0.5h). The second mixed solvent can be added appropriately to adjust to a suitable viscosity for spraying. It can be used after filtering.

[0073] (2) Coating application, parameters are shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] In the present invention, oil well drill pipe coating can be applied by brushing, but spraying is preferred, resulting in a more uniform and dense coating. Brushing can be used in situations where spraying is unsuitable, such as on-site repairs. The drill pipe is a core component of the drill string system used in oil, gas, and geological exploration operations, and is exposed to high-temperature environments found in deep and ultra-deep wells and complex geological conditions.

[0078] In the present invention, the temperature of the oil well is ≤200°C, preferably 150°C-200°C.

[0079] In the present invention, the steps of on-site repair include:

[0080] (1) Treatment of wear (damage) area:

[0081] Polish the worn oil well drill pipe to St3 grade → clean with the second mixed solvent → locally heat and dehumidify (80-100℃);

[0082] If the primer in the worn area is intact, the primer does not need to be repaired;

[0083] (2) Coating adaptability adjustment:

[0084] According to the on-site working conditions, the amount of active diluent is increased in the intermediate transition layer mixing system, and the viscosity of the paint is adjusted to 70-80s per 4 cups. Reducing the viscosity is conducive to on-site brushing.

[0085] Increase the amount of the second mixed solvent in the topcoat mixing system and adjust the coating viscosity of the paint to 70-80s per 4 cups. Lowering the viscosity will facilitate on-site brushing.

[0086] In addition, if the topcoat is applied by brush, 0.5-1wt% defoamer should be added to the topcoat mixing system.

[0087] (3) Curing:

[0088] Primer: infrared heating 70-80℃ / 50-70min, 150-180℃ / 60-90min;

[0089] Intermediate transition layer: 80-85℃ / 40-60min, 120-125℃ / 60-90min;

[0090] Topcoat: 22-30℃ / 100-120min, hot air circulation 130-150℃ / 40-60min;

[0091] The curing time can be adjusted dynamically according to the thickness of the repair.

[0092] In the present invention, the oil well drill pipe that has been worn in operation can be an oil well drill pipe that has been coated with the coating of the present invention but has been worn in operation, and an oil well drill pipe that has been coated with a protective coating known in the art but has been worn in operation (the wear area needs to be treated according to the above steps).

[0093] The beneficial effects of the technical solution of the present invention are as follows:

[0094] 1. The present invention achieves an optimized balance of the coating's corrosion resistance, wear resistance, toughness and high-temperature resistance by collaboratively designing a resin-based composite coating system and preparation process using multi-phase materials. The coating has been developed to provide a composite coating for drill pipe that has long-term corrosion resistance (salt spray resistance ≥ 1000h), excellent mechanical properties (adhesion ≥ 15MPa, tensile strength ≥ 230MPa at 150°C), excellent wear resistance (weight loss due to wear ≤ 0.05g / 1000r, hardness ≥ Hv400), high-temperature resistance (long-term (not less than 1 year) working temperature ≥ 150°C, short-term (at least 30d) resistance to 200°C), and is easy to repair on site.

[0095] 2. The coating of the present invention supports convenient coating processes such as spraying (cold spraying, air spraying) and brushing, and is suitable for drill pipe coating and on-site repair needs.

[0096] 3. The coating of the present invention has a greatly enhanced resistance to combined wear and corrosion (i.e., resistance to synergistic damage by corrosion and wear) compared to traditional technologies, significantly improving the service life of drill pipes. It is particularly suitable for the protection of oil well drill pipes in high-temperature environments, and is suitable for corrosion protection and surface strengthening treatment of high-strength drill pipes in deep wells, ultra-deep wells and complex geological conditions, thereby reducing drilling operation and maintenance costs.

[0097] 4. The design innovations of the coating of the present invention include:

[0098] (1) Functional structure design: A three-layer composite functional structure of "primer-intermediate transition layer-topcoat" is adopted to achieve the functional progression of "strong adhesion + cathodic protection (primer) - high wear resistance (intermediate transition layer) - super hydrophobic barrier (topcoat)", suppress stress concentration between layers, and improve overall high temperature resistance;

[0099] (2) Filler compounding strategy: Flake zinc powder + glass flake powder constructs a labyrinthine barrier path, aluminum oxide / silicon carbide dual phase enhances wear resistance, silicon nitride further improves wear resistance and high temperature resistance, and nano-cerium oxide can improve high temperature oxidation resistance;

[0100] (3) Synergistic modification of resins: Modification of fluorocarbon groups with silicone groups can significantly improve the corrosion resistance and high-temperature oxidation resistance of the coating; modification of epoxy phenolic resin and polyimide-modified epoxy resin can improve the temperature resistance of the coating;

[0101] (4) Enhanced thermal conductivity: Adding carbon nanotubes can improve the thermal conductivity and mechanical properties of the coating, reduce local heat accumulation, and reduce thermal stress.

[0102] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0104] Figure 1 A schematic structural diagram of an anti-corrosion, wear-resistant and high-temperature resistant coating provided in Example 1 of the present invention is shown.

[0105] Figure 2 The slow rate tensile curve of an anti-corrosion, wear-resistant and high-temperature resistant coating provided in Example 1 of the present invention at 150° C. is shown.

[0106] Figure 3 The morphology of a test piece of an anti-corrosion, wear-resistant and high-temperature resistant coating provided in Example 1 of the present invention after an abrasion test at 150°C, 1000g and 1000r is shown. DETAILED DESCRIPTION

[0107] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Instead, these embodiments are provided to make the present invention more thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0108] In the following embodiments:

[0109] In primer: modified epoxy phenolic resin uses DEN TM 431; ZH-325 is used for flaky zinc powder; HY-FeP is used for ferrophosphorus powder; HW-ZNW-01 is used for zinc oxide whisker; KH-550 is used as silane coupling agent; BYK-410 is used as anti-settling agent; NX-2015 is used as cardanol-modified polyamide curing agent; all components in the first mixed solvent (toluene, xylene and n-butanol) are products of Sinopharm Group.

[0110] In the intermediate transition layer: PMR-15+E-20 is used as polyimide-modified epoxy resin; WA-100 is used as fused alumina; GC-320 is used as silicon carbide; SN-E10 is used as silicon nitride; NC7000 is used as carbon nanotube; FX-1 is used as compatibilizer; BYK-110 is used as the first dispersant; polyamide curing agent is 650; all components in the active diluent (ethylene glycol butyl ether and propylene glycol methyl ether acetate) are products of Sinopharm Group.

[0111] In the topcoat: GF-25 is used as glass flake powder; AEROSIL R972 is used as hydrophobically modified nano-silica; CX-CeO2 is used as nano-cerium oxide; BYK-W9010 is used as the second dispersant; BYK-307 is used as the leveling agent; Desmodur N75 is used as the isocyanate curing agent; and all components in the second mixed solvent (xylene, propylene glycol methyl ether acetate, and cyclohexanone) are products of Sinopharm Group.

[0112] Example 1

[0113] This embodiment provides a corrosion-resistant, wear-resistant and high-temperature resistant coating, such as Figure 1 As shown, the coating comprises a primer, an intermediate transition layer and a topcoat arranged in sequence from bottom to top;

[0114] The raw materials of the primer include: a primer material and a primer curing agent component; based on the total weight of the primer material, the primer material includes: 45wt% of modified epoxy phenolic resin, 28.5wt% of flaky zinc powder, 9wt% of ferrophosphorus powder, 12.5wt% of a first mixed solvent, 2wt% of a silane coupling agent, 1.5wt% of an anti-settling agent, and 1.5wt% of zinc oxide whiskers;

[0115] The primer curing agent component includes: a cardanol-modified polyamide curing agent and a first mixed solvent; the weight amount of the cardanol-modified polyamide curing agent is calculated and determined based on the epoxy value of the modified epoxy novolac resin and the amine value of the cardanol-modified polyamide curing agent itself, and is 35wt% of the weight of the primer material; the weight amount of the first mixed solvent in the primer curing agent component is determined based on the viscosity requirement of the primer, and is 10wt% of the weight of the primer material;

[0116] The first mixed solvent includes toluene, xylene and n-butanol, and the weight ratio of toluene, xylene and n-butanol is 4:3:3;

[0117] The raw materials of the intermediate transition layer include: an intermediate transition layer material and an intermediate curing agent component; based on the total weight of the intermediate transition layer material, the intermediate transition layer material includes: 50wt% of polyimide-modified epoxy resin, 23.5wt% of fused alumina, 8wt% of silicon carbide, 14.5wt% of reactive diluent, 1.25wt% of carbon nanotubes, 0.5% of compatibilizer, 0.75wt% of first dispersant and 1.5wt% of silicon nitride;

[0118] The intermediate curing agent component includes: a polyamide curing agent and a reactive diluent; the weight amount of the polyamide curing agent is calculated based on the epoxy value of the polyimide-modified epoxy resin and the amine value of the polyamide curing agent itself, and is 20wt% of the weight of the intermediate transition layer material; the weight amount of the reactive diluent in the intermediate curing agent component is determined based on the viscosity requirement of the intermediate transition layer, and is 3wt% of the weight of the intermediate transition layer material;

[0119] The active diluent includes ethylene glycol butyl ether and propylene glycol methyl ether acetate, and the weight ratio of the ethylene glycol butyl ether to the propylene glycol methyl ether acetate is 6:4;

[0120] The raw materials of the topcoat include: a topcoat material and a topcoat curing agent component; the topcoat material includes: 50wt% of organosilicon-modified fluorocarbon resin, 32.5wt% of glass flake powder, 2.5wt% of hydrophobically modified nano-silica, 12.5wt% of a second mixed solvent, 0.75wt% of a second dispersant, 0.75wt% of a leveling agent and 1wt% of nano-cerium oxide;

[0121] The topcoat curing agent component includes: an isocyanate curing agent and a second mixed solvent; the weight amount of the isocyanate curing agent is calculated based on the hydroxyl equivalent of the fluorocarbon resin in the organosilicon-modified fluorocarbon resin and the NCO content of the isocyanate curing agent itself, and is 15wt% of the weight of the topcoat material; the weight amount of the second mixed solvent in the topcoat curing agent component is determined based on the viscosity requirement of the topcoat, and is 4wt% of the weight of the topcoat material;

[0122] The second mixed solvent includes xylene, propylene glycol methyl ether acetate and cyclohexanone, and the weight ratio of the xylene, propylene glycol methyl ether acetate and cyclohexanone is 6:3:1.

[0123] The preparation method of the above-mentioned anti-corrosion, wear-resistant and high-temperature resistant coating comprises the following steps:

[0124] Coating preparation:

[0125] S1: adding the modified epoxy phenolic resin and the first mixed solvent to a first container and mixing and dispersing them at 900 rpm for 15 min, then adding the anti-settling agent and the silane coupling agent to the first container and mixing and dispersing them at 1100 rpm for 15 min, then adding flaky zinc powder, ferrophosphorus powder and zinc oxide whiskers to the first container and mixing and dispersing them at 2100 rpm for 2 h to obtain the primer material, which is sealed for later use; before spraying, mixing and dispersing the primer material, the cardanol-modified polyamide curing agent and the first mixed solvent together at 1500 rpm for 0.5 h to obtain a primer mixture system that meets the viscosity requirements, and filtering for later use;

[0126] S2: Add the polyimide-modified epoxy resin and the reactive diluent to a second container and mix and disperse them at 900 rpm for 15 minutes, then add the compatibilizer and the first dispersant to the second container and mix and disperse them at 1100 rpm for 15 minutes, then add the carbon nanotubes to the second container and mix and disperse them at 1900 rpm for 15 minutes, then add molten alumina, silicon carbide and silicon nitride to the second container in a gradient manner (gradient means that the wear-resistant filler is added to the second container in batches, and the weight of each batch of wear-resistant filler added is ≤5wt% of the total weight of the wear-resistant filler) and mix and disperse them at 1500 rpm for 2 hours, grind to a fineness of ≤50 μm to obtain an intermediate transition layer material, and seal it for use; before spraying, mix and disperse the intermediate transition layer material, polyamide curing agent and reactive diluent together at 1200 rpm for 0.5 hours to obtain an intermediate transition layer mixed system that meets the viscosity requirements, and filter it for use;

[0127] S3: Add fluorocarbon resin and silicone to a third container, add half of the second mixed solvent required in the topcoat material, and react at 110-120°C and 800-1000rpm for 2-3h under inert gas protection to prepare the silicone-modified fluorocarbon resin; add the remaining second mixed solvent required for the topcoat material to a third container and mix and disperse at 900rpm for 15min, then add the second dispersant and leveling agent to the third container and mix and disperse at 1100rpm for 15min, then add the hydrophobically modified nano-silica and nano-cerium oxide to the third container and mix and disperse at 1900rpm for 15min, then add the glass flake powder to the third container and mix and disperse at 1500rpm for 2h, grind to a fineness of ≤40μm to obtain the topcoat material, and seal for use; mix and disperse the topcoat material, isocyanate curing agent and second mixed solvent together at 1100rpm for 0.5h to obtain a topcoat mixing system that meets the viscosity requirements, and filter for use.

[0128] Coating:

[0129] Use oil well drill pipe as the substrate, sandblast the substrate to Sa2.5 level, Ra=40-50μm, clean it with acetone, and blow dry it for later use;

[0130] Air spraying is used, where:

[0131] After the primer is sprayed on the substrate, it is first cured at 75℃ for 60 minutes, and then at 175℃ for 75 minutes. The dry film thickness is 43-45μm.

[0132] After spraying the intermediate transition layer, first cure it at 80℃ for 50min, then cure it at 120℃ for 75min, with a dry film thickness of 142-148μm;

[0133] After spraying the topcoat, first cure it at 25℃ for 120min and then at 140℃ for 50min. The dry film thickness is 70-73μm.

[0134] Example 2

[0135] In this embodiment, the anti-corrosion, wear-resistant and high-temperature resistant coating material is used to perform on-site repair on an oil well drill pipe that has been coated with the coating of Example 1 but has been worn during operation.

[0136] The primer of the worn area of ​​the oil well drill pipe in this embodiment is intact. After the area is partially polished to St3 level, the surface is cleaned with acetone solvent and dried at 80-100°C.

[0137] Primer: The remaining thickness of the tested primer is 42-45 μm, so the primer does not need to be repaired.

[0138] Intermediate transition layer: Add 9 wt% of the active diluent by weight of the intermediate transition layer material to the intermediate transition layer mixture obtained in step S2 of Example 1, adjust the coating viscosity of the paint to 72s per 4 cup, and cure at 80-85°C for 50 minutes after brushing, and then cure at 125°C for 80 minutes, to a repair thickness of 143-145 μm;

[0139] Topcoat: Add 0.5wt% defoamer and 20wt% of the second mixed solvent by weight of the topcoat material to the topcoat mixing system obtained in step S3 of Example 1, adjust the coating viscosity of the paint to 70s, and after brushing, cure it at 26°C for 100min and then at 140°C for 50min, and the repair thickness is 69-72μm.

[0140] After on-site repair, the coating surface was flat and smooth without obvious defects, indicating that the coating system of the present invention is reasonably designed and has good process adaptability.

[0141] Test Case

[0142] This test example conducts hardness test, adhesion test, neutral salt spray resistance test, abrasion test, high temperature tensile test and thermal shock test on the anti-corrosion, wear-resistant and high temperature resistant coating of Example 1 to verify the corrosion resistance, wear resistance and high temperature resistance of the coating.

[0143] Test method:

[0144] Hardness: Due to the thick coating, pencil hardness test cannot be used, and microhardness tester is used instead;

[0145] Adhesion: Refer to GB / T 5210-2006;

[0146] Neutral salt spray resistance: refer to GB / T1771-2007;

[0147] Wear test: refer to GBT 1768-2006, the temperature is set to 150℃;

[0148] Thermal shock test: Refer to ASTM C633 Appendix 3, the temperature is set to 200℃;

[0149] High temperature tensile test: refer to GB / T 1040.2-2006, the temperature is set to 150℃.

[0150] The test results are shown in Table 2.

[0151] Table 2

[0152]

[0153] The results of the high temperature tensile test are shown in Figure 2 , Figure 2 is the slow rate tensile curve of the anti-corrosion, wear-resistant and high temperature resistant coating of Example 1 at 150°C, Figure 2 It can be seen that at 150℃, the coating tensile strength R m The tensile strength is 234.78 MPa, and the elongation at break is 7.66%, which shows that the corrosion-resistant, wear-resistant and high-temperature resistant coating of the present invention has excellent mechanical properties at high temperatures.

[0154] As shown in Table 2, the loss of the anti-corrosion, wear-resistant and high-temperature resistant coating of Example 1 after the abrasion test at 150°C, 1000g and 1000r is 6.3mg. Figure 3 This is the test piece morphology of the anti-corrosion, wear-resistant and high-temperature resistant coating of Example 1 after the abrasion test at 150°C, 1000g, and 1000r. It can be seen that the coating of the present invention shows outstanding wear resistance.

[0155] By optimizing the coating material and structure, as well as improving the preparation process, this paper has successfully developed a wear-resistant and corrosion-resistant coating for drill pipe suitable for high-temperature environments. This coating not only exhibits excellent wear and corrosion resistance, but also good high-temperature resistance. The repair process is simple and inexpensive, effectively extending the service life of the drill pipe and reducing drilling operation and maintenance costs.

[0156] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A corrosion-resistant, wear-resistant and high-temperature resistant coating, characterized in that: The coating comprises a primer, an intermediate transition layer and a topcoat arranged in sequence from bottom to top; The raw materials of the primer include: a primer material and a primer curing agent component; the primer material includes: a modified epoxy phenolic resin, a primer functional filler, a first mixed solvent, a high-temperature resistant coupling agent, and an anti-settling agent; the primer functional filler includes: flaky zinc powder, ferrophosphorus powder, and optional zinc oxide whiskers; the primer curing agent component includes: a cardanol-modified polyamide curing agent; The raw materials of the intermediate transition layer include: intermediate transition layer material and intermediate curing agent component; the intermediate transition layer material includes: polyimide modified epoxy resin, wear-resistant filler, active diluent, carbon nanotubes, a first dispersant and a compatibilizer; the wear-resistant filler includes: fused alumina, silicon carbide and optionally silicon nitride; the intermediate curing agent component includes: polyamide curing agent; The raw materials of the topcoat include: topcoat material and topcoat curing agent component; the topcoat material includes: organosilicon-modified fluorocarbon resin, topcoat functional filler, a second mixed solvent, a second dispersant and a leveling agent; the topcoat functional filler includes: glass flake powder, hydrophobically modified nano-silica and optional nano-cerium oxide; the topcoat curing agent component includes: isocyanate curing agent.

2. The anti-corrosion, wear-resistant and high-temperature resistant coating according to claim 1, wherein: The primer material comprises, based on the total weight of the primer material, 40-50 wt% of a modified epoxy phenolic resin, 25-32 wt% of flaky zinc powder, 8-10 wt% of ferrophosphorus powder, 10-15 wt% of a first mixed solvent, 1-3 wt% of a high-temperature resistant coupling agent, 1-2 wt% of an anti-settling agent, and 0-3 wt% of zinc oxide whiskers; The weight amount of the cardanol modified polyamide curing agent is calculated and determined based on the epoxy value of the modified epoxy phenolic resin and the amine value of the cardanol modified polyamide curing agent itself; preferably, the primer curing agent component further includes: a first mixed solvent; the weight amount of the first mixed solvent in the primer curing agent component is determined based on the viscosity requirement of the primer; Based on the total weight of the intermediate transition layer material, the intermediate transition layer material includes: 45-55wt% of polyimide-modified epoxy resin, 20-27wt% of fused alumina, 6-10wt% of silicon carbide, 12-17wt% of reactive diluent, 0.5-1.5wt% of carbon nanotubes, 0.5-1wt% of compatibilizer, 0.5-1wt% of first dispersant, and 0-3wt% of silicon nitride; The weight amount of the polyamide curing agent is calculated and determined based on the epoxy value of the polyimide-modified epoxy resin and the amine value of the polyamide curing agent itself; preferably, the intermediate curing agent component further includes: a reactive diluent; the weight amount of the reactive diluent in the intermediate curing agent component is determined based on the viscosity requirement of the intermediate transition layer; Calculated based on the total weight of the topcoat material, the topcoat material includes: 45-55wt% of organosilicon-modified fluorocarbon resin, 27-38wt% of glass flake powder, 2-3wt% of hydrophobically modified nano-silica, 10-15wt% of a second mixed solvent, 0.5-1wt% of a second dispersant, 0.5-1wt% of a leveling agent and 0-2wt% of nano-cerium oxide; preferably, calculated based on the total weight of the topcoat material, the topcoat material also includes: 0.5-1wt% of a defoaming agent. The weight amount of the isocyanate curing agent is calculated and determined based on the hydroxyl equivalent of the fluorocarbon resin in the silicone-modified fluorocarbon resin and the NCO content of the isocyanate curing agent itself; preferably, the topcoat curing agent component also includes: a second mixed solvent; the weight amount of the second mixed solvent in the topcoat curing agent component is determined based on the viscosity requirement of the topcoat.

3. The anti-corrosion, wear-resistant and high-temperature resistant coating according to claim 1 or 2, wherein: The first mixed solvent comprises toluene, xylene and n-butanol, and the weight ratio of the toluene, xylene and n-butanol is (3.5-4.5): (2.5-3.5): (2.5-3.5); The particle size of the flaky zinc powder is 10-15 μm; The particle size of the ferrophosphorus powder is 5-8 μm; The active diluent includes ethylene glycol butyl ether and propylene glycol methyl ether acetate, and the weight ratio of the ethylene glycol butyl ether to the propylene glycol methyl ether acetate is (5.5-6.5):(3.5-4.5); The particle size of the fused alumina is 80-120 mesh; The particle size of the silicon carbide is 200-400 mesh; The particle size of the silicon nitride is 200-400 mesh; The second mixed solvent comprises xylene, propylene glycol methyl ether acetate and cyclohexanone, and the weight ratio of the xylene, propylene glycol methyl ether acetate and cyclohexanone is (5.0-6.0):(3.0-4.0):(1.0-2.0); The particle size of the glass flake powder is 20-30 μm; The particle size of the hydrophobically modified nano-silica is 30-50 nm; The particle size of the nano-cerium oxide is 30-50 nm.

4. The anti-corrosion, wear-resistant and high-temperature resistant coating according to claim 1, wherein: The dry film thickness of the primer is 40-50 μm; The dry film thickness of the intermediate transition layer is 130-160 μm; The dry film thickness of the topcoat is 60-80 μm.

5. The method for preparing the anti-corrosion, wear-resistant and high-temperature resistant coating according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: S1: adding the modified epoxy phenolic resin and the first mixed solvent into a first container and mixing and dispersing them, then adding the anti-settling agent and the high temperature resistant coupling agent into the first container and mixing and dispersing them, and then adding the primer functional filler into the first container and mixing and dispersing them to obtain the primer material; mixing and dispersing the primer material with a cardanol modified polyamide curing agent to obtain a primer mixture system, filtering, coating, drying and curing to obtain a primer; S2: adding the polyimide-modified epoxy resin and the reactive diluent to a second container and mixing and dispersing them, then adding the compatibilizer and the first dispersant to the second container and mixing and dispersing them, then adding the carbon nanotubes to the second container and mixing and dispersing them, then gradually adding the wear-resistant filler to the second container and mixing and dispersing them, and grinding to obtain an intermediate transition layer material; mixing and dispersing the intermediate transition layer material with the polyamide curing agent to obtain an intermediate transition layer mixed system, filtering, coating, and step-drying and curing to obtain an intermediate transition layer; S3: Add the organosilicon-modified fluorocarbon resin and the second mixed solvent into a third container and mix and disperse them, then add the second dispersant and leveling agent into the third container and mix and disperse them, then add the hydrophobically modified nano-silica and optional nano-cerium oxide into the third container and mix and disperse them, then add the glass flake powder into the third container and mix and disperse them, grind to obtain the topcoat material; mix and disperse the topcoat material with an isocyanate curing agent to obtain a topcoat mixed system, filter, coat, dry and solidify to obtain a topcoat.

6. The method for preparing the anti-corrosion, wear-resistant and high-temperature resistant coating according to claim 5, wherein: The coating method is at least one of cold spraying, air spraying and brushing.

7. The method for preparing the anti-corrosion, wear-resistant and high-temperature resistant coating according to claim 5, wherein: In step S1: The modified epoxy phenolic resin and the first mixed solvent are added to a first container and mixed and dispersed at 800-1000 rpm for 10-15 minutes, then the anti-settling agent and the high temperature resistant coupling agent are added to the first container and mixed and dispersed at 1000-1200 rpm for 10-15 minutes, and then the primer functional filler is added to the first container and mixed and dispersed at 2000-2200 rpm for 1.5-2 hours to obtain the primer material; the primer material is mixed and dispersed with a cardanol-modified polyamide polyamide curing agent at 1300-1500 rpm for 20-40 minutes to obtain a primer mixed system, which is filtered, coated, dried and solidified to obtain a primer; Drying and curing includes the first and second stages which are carried out continuously. The temperature of the first stage is 70-80℃ and the time is 50-70min. After the first stage curing, the temperature is raised to the second stage at a rate of ≤5℃ / min. The temperature of the second stage is 150-180℃ and the time is 60-90min. Preferably, the primer material, the cardanol-modified polyamide curing agent and the first mixed solvent are mixed and dispersed together at 1300-1500 rpm for 20-40 minutes to obtain a primer mixture system that meets the viscosity requirements, and the mixture is filtered, coated, dried and cured to obtain a primer.

8. The method for preparing the anti-corrosion, wear-resistant and high-temperature resistant coating according to claim 5, wherein: In step S2: The polyimide-modified epoxy resin and the reactive diluent are added to a second container and mixed and dispersed at 800-1000 rpm for 10-15 minutes, then the compatibilizer and the first dispersant are added to the second container and mixed and dispersed at 1000-1200 rpm for 10-15 minutes, then the carbon nanotubes are added to the second container and mixed and dispersed at 1800-2000 rpm for 10-15 minutes, then the wear-resistant filler is added to the second container in a gradient manner and mixed and dispersed at 1400-1500 rpm for 1.5-2 hours, and ground to obtain an intermediate transition layer material; the intermediate transition layer material is mixed and dispersed with the polyamide curing agent at 1000-1200 rpm for 20-40 minutes to obtain an intermediate transition layer mixed system, which is filtered, coated, dried and solidified to obtain an intermediate transition layer; Gradual addition of the wear-resistant filler is to add the wear-resistant filler into the second container in batches, with the weight of each batch of wear-resistant filler being ≤ 5wt% of the total weight of the wear-resistant filler, and the batch interval being 4-6 minutes; Grinding so that the fineness of the intermediate transition layer material is ≤50 μm; Drying and curing includes the first and second stages which are carried out continuously. The temperature of the first stage is 80-85°C and the time is 40-60 minutes. After the first stage is cured, the temperature is raised to the second stage at a rate of ≤5°C / min. The temperature of the second stage is 120-125°C and the time is 60-90 minutes. Preferably, the intermediate transition layer material, polyamide curing agent and reactive diluent are mixed and dispersed together at 1000-1200 rpm for 40-60 min to obtain an intermediate transition layer mixed system that meets the viscosity requirements, and the intermediate transition layer is obtained by filtering, coating, drying and curing.

9. The method for preparing the anti-corrosion, wear-resistant and high-temperature resistant coating according to claim 5, wherein: In step S3: Add the fluorocarbon resin and organosilicon to a third container, add half of the second mixed solvent required for the topcoat material, and react at 110-120° C. and 800-1000 rpm for 2-3 hours under inert gas protection to prepare the organosilicon-modified fluorocarbon resin; add the remaining second mixed solvent required for the topcoat material to the third container and mix and disperse at 800-1000 rpm for 10-15 minutes; then add the second dispersant and leveling agent to the third container and mix and disperse at 1000-1200 rpm for 10-15 minutes. in, then adding the hydrophobically modified nano-silica and optional nano-cerium oxide to the third container and mixing and dispersing them at 1800-2000rpm for 10-15min, then adding the glass flake powder to the third container and mixing and dispersing them at 1400-1500rpm for 1.5-2h, grinding to obtain the topcoat material; mixing and dispersing the topcoat material with an isocyanate curing agent at 1000-1200rpm for 40-60min to obtain a topcoat mixed system, filtering, coating, drying and curing to obtain a topcoat; Grinding the topcoat material to a fineness of ≤40 μm; Drying and curing includes the first and second stages which are carried out continuously. The temperature of the first stage is 22-30°C and the time is 100-120 minutes. After the first stage curing, the temperature is raised to the second stage at a rate of ≤5°C / min. The temperature of the second stage is 130-150°C and the time is 40-60 minutes. Preferably, the topcoat material, isocyanate curing agent and second mixed solvent are mixed and dispersed together at 1000-1200 rpm for 40-60 min to obtain a topcoat mixed system that meets the viscosity requirements, and the topcoat is obtained by filtering, coating, drying and curing.

10. Use of the anti-corrosion, wear-resistant and high-temperature resistant coating according to any one of claims 1 to 4 in protecting oil well drill pipes; Preferably, the protection includes coating the oil well drill pipe with the anti-corrosion, wear-resistant and high temperature resistant coating, and performing on-site repair of the oil well drill pipe that has been worn out by work with the anti-corrosion, wear-resistant and high temperature resistant coating.

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