Wear-resistant coating for drill rod, preparation method of wear-resistant coating, drill rod with surface wear-resistant coating and preparation method of drill rod

Abstract

The invention relates to the field of composite materials, in particular to wear-resistant paint for a drill rod, a preparation method of the wear-resistant paint, the drill rod with a surface wear-resistant coating and a preparation method of the drill rod. The preparation method of the wear-resistant coating for the drill rod comprises the following steps: S1, performing high-temperature oxidation treatment on composite powder of silicon carbide and diamond to obtain pretreated composite powder; s2, mixing the pretreated composite powder obtained in the step S1 with a silane coupling agent solution, heating and stirring, and then drying to obtain surface modified composite powder; s3, mixing epoxy resin with a toughening agent and a defoaming agent, heating, then adding the surface modified composite powder obtained in the step S2, uniformly mixing, and defoaming to obtain mixed slurry; s4, mixing the mixed slurry obtained in the step S3 with a curing agent, and defoaming to obtain the wear-resistant coating. The wear-resistant paint provided by the invention can form a coating with high wear resistance and high toughness on the surface of the drill rod.

Description

Technical Field

[0001] The present invention relates to the field of composite materials, in particular to a wear-resistant coating for a drill rod and a preparation method thereof, a drill rod with a surface wear-resistant coating and a preparation method thereof. Background Art

[0002] Drill pipe is an important drilling equipment. In the well, the drill pipe has to withstand complex loads such as internal and external pressure, friction and wear, bending, torque, vibration, etc., and is also subject to corrosion from drilling fluid, oil and gas, and seawater. In general, the use of lightweight and high-strength drill pipe is the right idea to further improve drilling capabilities based on existing drilling equipment and process conditions. Compared with traditional metal materials, continuous fiber reinforced resin-based composite materials (hereinafter referred to as composite materials) have the advantages of low density, high strength, corrosion resistance, fatigue resistance, strong material performance design, and simple molding. Although composite materials are regarded as the optimal solution for material lightweighting in many equipment fields, there is no precedent for the engineering application of composite drill pipe in my country, but there are related patent layouts in the industry. Combined with the structural characteristics and service conditions of drill pipe, we believe that the research and development of composite drill pipe needs to focus on the following key technologies: (1) Mechanical property design of composite pipe body; (2) Interface strengthening between composite pipe body and steel joint; (3) Wear-resistant design of composite pipe body.

[0003] In recent years, the oil and geological drilling industries have increasingly focused on continuous fiber-reinforced resin-based composites. Due to their lightweight and high-strength properties, composite drill pipe is expected to become a lightweight solution for drill pipe equipment. Current research and development of composite drill pipe focuses on improving the overall load-bearing capacity of the structure. However, for composite drill pipe to enter practical application, its surface wear resistance needs to be improved.

[0004] Patent CN200820056720.X provides a connection structure between a composite pipe body and a steel head, and does not involve the design of a wear-resistant coating on the surface of the drill pipe. Patent CN115847852A provides a comprehensive application method of carbon fiber composite materials in geological drilling equipment. The tensile and torsional bearing capacity of the composite drill pipe are given in the embodiment, and does not involve the design of a wear-resistant coating on the surface of the drill pipe. Patent CN113790030A provides a mixed fiber composite drill pipe structure design scheme, including an internal rigid layer, an intermediate strength layer, an intermediate torsional layer and a surface wear-resistant layer, wherein the surface wear-resistant layer is a composite of a two-dimensional planar woven laminated structure of carbon fiber and a resin matrix. Patent CN117654855A provides a method for manufacturing a composite oil pipe body, and its surface wear-resistant layer adopts a composite material formula of carbon fiber / graphite and polyetheretherketone. It can be seen from the above patents that the wear-resistant layer material on the surface of the composite drill pipe is mostly composed of a thermosetting resin or other thermoplastic polymer matrix. The wear resistance is achieved by adding wear-resistant or drag-reducing fibers or fillers to the matrix. The preparation of the wear-resistant coating is achieved through a process of composite winding with the fibers.

[0005] The matrix of the composite pipe body is mostly made of epoxy resin, so the matrix of the wear-resistant coating on its surface is made of epoxy resin, which can form a good bonding match with the pipe body. Adding wear-resistant inorganic fillers to epoxy resin is one of the ways to improve the wear resistance of the coating. However, inorganic fillers with low particle size are prone to agglomeration in epoxy resin, resulting in poor dispersibility, which is not conducive to improving the wear resistance. In addition, inorganic fillers such as silicon carbide and diamond are difficult to form a high-performance interface with the epoxy resin matrix, which causes premature shedding of the filler during friction and wear. CN116496606A provides a method for preparing a highly wear-resistant epoxy resin-silicon carbide composite material. The surface modification of silicon carbide is achieved by hydrofluoric acid immersion and coupling agent grafting. However, the particle size of silicon carbide in this patent is in the range of 0.5-2mm. The excessively large silicon carbide particle size makes the material unsuitable for the preparation of wear-resistant coating on the surface of composite drill pipe; moreover, the silicon carbide surface is activated by hydrofluoric acid immersion. Hydrofluoric acid is highly corrosive, not only causing non-uniform etching on the silicon carbide surface, but also significantly reducing the mechanical strength of the material. This is especially true for micron- and nanometer-sized particles, where excessively high concentrations of hydrofluoric acid can damage the particle structure. Fluorides generated by the reaction of hydrofluoric acid with silicon carbide easily remain on the silicon carbide surface and may decompose to produce hydrogen fluoride during the subsequent high-temperature curing process of the coating. This not only easily corrodes the mold, but may also generate microbubbles within the coating, degrading coating performance. Finally, the highly toxic nature of hydrofluoric acid necessitates specialized protective facilities and complex wastewater treatment processes during the production process, significantly increasing equipment investment and operating costs, which is inconsistent with the development trend of green chemistry. Summary of the Invention

[0006] In view of this, the present invention provides a wear-resistant coating for a drill pipe and a preparation method thereof, a drill pipe with a surface wear-resistant coating and a preparation method thereof. The wear-resistant coating provided by the present invention can form a highly wear-resistant and high-toughness coating on the surface of the drill pipe.

[0007] The present invention provides a method for preparing a wear-resistant coating for a drill pipe, comprising the following steps:

[0008] S1. performing high-temperature oxidation treatment on a composite powder of silicon carbide and diamond to obtain a pretreated composite powder;

[0009] S2, mixing the pretreated composite powder obtained in step S1 with a silane coupling agent solution, heating and stirring, and then drying to obtain a surface-modified composite powder;

[0010] S3, mixing the epoxy resin with the toughening agent and the defoaming agent, heating, then adding the surface-modified composite powder obtained in step S2, mixing evenly, and degassing to obtain a mixed slurry;

[0011] S4. Mix the mixed slurry obtained in step S3 with a curing agent, and perform degassing treatment to obtain a wear-resistant coating.

[0012] Preferably, in step S1:

[0013] The temperature of the high temperature oxidation treatment is 600-800°C, and the holding time is 120-240 minutes;

[0014] The average particle size of the silicon carbide powder is 5 to 20 μm;

[0015] The average particle size of the diamond powder is 5 to 30 μm;

[0016] The mass ratio of diamond to silicon carbide is (0.1-0.5):1.

[0017] Preferably, in step S2, the silane coupling agent solution is prepared by the following method: mixing the silane coupling agent with water for hydrolysis, and then adding anhydrous ethanol to obtain the silane coupling agent solution;

[0018] The mass ratio of the silane coupling agent to water is 1:(3-4);

[0019] The mass ratio of the silane coupling agent to anhydrous ethanol is 1:(15-30);

[0020] The pH value of the silane coupling agent solution is 4-5.

[0021] Preferably, in step S2, the heating temperature is 60-80°C, the stirring speed is 1300-1800 rpm, the heating and stirring time is 360-480 min; and the standing time is 30-60 min.

[0022] Preferably, in step S3:

[0023] The epoxy resin is at least one of N,N-diglycidyl-p-glycidyloxyaniline and bisphenol A epoxy resin;

[0024] The mass ratio of the toughening agent to the epoxy resin is (0.1-0.3):1;

[0025] The mass ratio of the defoamer to the epoxy resin is (0.005-0.01):1;

[0026] The mass ratio of the surface-modified composite powder obtained in step S2 to the epoxy resin is preferably (0.1-0.3):1.

[0027] Preferably, in step S4, the curing agent is isophorone diamine curing agent;

[0028] The mass ratio of the curing agent to the epoxy resin in step S3 is (0.2-0.45):1.

[0029] The present invention also provides a wear-resistant coating for a drill rod prepared by the preparation method described in the above technical solution.

[0030] The present invention also provides a method for preparing a drill rod with a surface wear-resistant coating, comprising the following steps: applying a wear-resistant coating to the surface of the drill rod, curing, and forming a wear-resistant coating; wherein the wear-resistant coating is the wear-resistant coating for the drill rod described in the above technical solution.

[0031] Preferably, the curing is step curing, specifically pre-curing and high temperature curing are performed in sequence;

[0032] The pre-curing temperature is 50-70° C., and the time is 120-180 min; the high-temperature curing temperature is 100-150° C., and the time is 180-240 min.

[0033] The present invention also provides a drill rod with a surface wear-resistant coating, which is prepared by the preparation method described in the above technical solution.

[0034] The wear-resistant coating provided by the present invention first performs a high-temperature oxidation treatment on the composite powder of silicon carbide and diamond, then performs a surface modification treatment using a silane coupling agent solution, and then uniformly mixes the epoxy resin with a toughening agent, a defoaming agent and the composite powder subjected to the surface modification treatment, performs a degassing treatment, and obtains a mixed slurry; and then introduces a curing agent to form a wear-resistant coating. The present invention does not directly mix the epoxy resin with the solid powder and the additives. Instead, through the above-mentioned step-by-step treatment and mixing, it can improve the surface activity of the inorganic filler in the coating material, solve the problems of uneven dispersion and poor interfacial bonding with the substrate, improve the wear resistance and toughness of the coating material, and further form a wear-resistant coating with uniform thickness and stable performance on the surface of the drill pipe, thereby improving the wear resistance of the composite drill pipe and helping to extend the service life of the composite drill pipe. In addition, the present invention does not use hydrofluoric acid for immersion modification, thereby avoiding the problems of etching the silicon carbide surface and reducing the material strength, decomposing and generating hydrogen fluoride during high-temperature curing and corroding the mold, and causing microbubbles inside the coating and degrading the coating performance, and also avoiding the cost of protective facilities and waste liquid treatment caused by the toxicity of hydrofluoric acid. The preparation process of the present invention is simple, the cost and energy consumption are low, and it is in line with the development trend of green chemistry.

[0035] The experimental results show that the friction coefficient of the wear-resistant coating of the drill rod of the present invention is below 0.52, and the wear rate is below 0.033mm. 3 / min or less, showing excellent wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0037] Figure 1 It is a front view of the assembly of the mold and the drill rod in the present invention;

[0038] Figure 2 for Figure 1 AA direction cross-sectional view;

[0039] Figure 3 for Figure 1 BB direction cross-sectional view;

[0040] Figure 4 This is the surface wear morphology of the wear-resistant coating of the product obtained in Example 1;

[0041] Figure 5 This is the surface wear morphology of the wear-resistant coating of the product obtained in Example 2;

[0042] Figure 6 This is the surface wear morphology of the wear-resistant coating of the product obtained in Example 3;

[0043] Figure 7 This is the surface wear morphology of the wear-resistant coating of the product obtained in Example 4;

[0044] Figure 8 This is the surface wear morphology of the 7075 aluminum alloy drill rod in Comparative Example 1;

[0045] Figure 9 This is the surface wear morphology of the drill pipe body material in Comparative Example 2;

[0046] Figure 10 This is the surface wear morphology of the wear-resistant coating of the product obtained in Comparative Example 3;

[0047] Figure 11 This is the surface wear morphology of the wear-resistant coating of the product obtained in Comparative Example 4. DETAILED DESCRIPTION

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0049] In this article, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0050] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0051] As used herein, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Furthermore, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0052] In this document, when referring to a range, if the unit is followed only by the right endpoint, it means that the units of the left and right endpoints are the same. For example, 5-20 μm means that the units of the left endpoint "5" and the right endpoint "20" are both μm.

[0053] In a first aspect, the present invention provides a method for preparing a wear-resistant coating for a drill pipe, comprising the following steps:

[0054] S1. performing high-temperature oxidation treatment on a composite powder of silicon carbide and diamond to obtain a pretreated composite powder;

[0055] S2, mixing the pretreated composite powder obtained in step S1 with a silane coupling agent solution, heating and stirring, and then drying to obtain a surface-modified composite powder;

[0056] S3, mixing the epoxy resin with the toughening agent and the defoaming agent, heating, then adding the surface-modified composite powder obtained in step S2, mixing evenly, and degassing to obtain a mixed slurry;

[0057] S4. Mix the mixed slurry obtained in step S3 with a curing agent, and perform degassing treatment to obtain a wear-resistant coating.

[0058] About step S1 :

[0059] S1. Performing high-temperature oxidation treatment on the composite powder of silicon carbide and diamond to obtain pretreated composite powder.

[0060] In the present invention, the average particle size of the silicon carbide powder is preferably 5 to 20 μm, specifically 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, and 20 μm. The average particle size of the diamond powder is preferably 5 to 30 μm, specifically 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, and 30 μm. The mass ratio of diamond to silicon carbide is preferably (0.1-0.5):1, specifically 0.1:1, 0.2:1, 0.3:1, 0.4:1, or 0.5:1. There is no particular limitation on the preparation method of the composite powder of silicon carbide and diamond, and the silicon carbide powder and diamond powder can be uniformly mixed.

[0061] In the present invention, the high-temperature oxidation treatment can be carried out in a muffle furnace. The high-temperature oxidation treatment is carried out in an air atmosphere. The heating rate of the high-temperature oxidation treatment is preferably 3 to 10°C / min, specifically 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, and 10°C / min. The temperature of the high-temperature oxidation treatment is preferably 600 to 800°C, specifically 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, and 800°C, more preferably 800°C. The holding time of the high-temperature oxidation treatment is preferably 120 to 240 minutes, specifically 120 minutes, 150 minutes, 180 minutes, 210 minutes, or 240 minutes.

[0062] In the present invention, after the high-temperature oxidation, cooling and grinding are preferably performed. The cooling preferably involves furnace cooling to room temperature. After the high-temperature treatment, the powder will agglomerate. Grinding eliminates visible agglomerates. After the above treatment, a pretreated composite powder is obtained.

[0063] About step S2 :

[0064] S2. Mixing the pretreated composite powder obtained in step S1 with the silane coupling agent solution, heating and stirring, and then drying to obtain a surface-modified composite powder.

[0065] In the present invention, the silane coupling agent solution is preferably prepared by the following method: mixing a silane coupling agent with water for hydrolysis, and then adding an organic solvent to obtain a silane coupling agent solution. The silane coupling agent is preferably at least one of KH550, KH560, and KH570. The water is preferably distilled water. The organic solvent is preferably at least one of anhydrous ethanol and propanol. The mass ratio of the silane coupling agent to water is preferably 1:(3-4), specifically 1:3 or 1:4. The mass ratio of the silane coupling agent to the organic solvent is preferably 1:(15-30), specifically 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:28, 1:29, or 1:30. After adding the organic solvent, the pH value is preferably adjusted to 4 to 5, specifically 4 or 5. The pH regulator used to adjust the pH value is preferably acid solution, more preferably dilute hydrochloric acid.

[0066] In the present invention, when the pretreated composite powder obtained in step S1 is mixed with the silane coupling agent solution, the mass ratio of the pretreated composite powder obtained in step S1 to the silane coupling agent solution is preferably 1:(0.2-0.3), specifically 1:0.2 or 1:0.3. After the above mixing, heating and stirring are performed. The heating and stirring can be achieved by a constant temperature water bath. The heating temperature is preferably 60-80°C, specifically 60°C, 65°C, 70°C, 75°C, or 80°C. The stirring speed is preferably 1300-1800 rpm, specifically 1300 rpm, 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, or 1800 rpm. The heating and stirring time is preferably 360-480 min, specifically 360 min, 390 min, 420 min, 450 min, or 480 min.

[0067] In the present invention, after the above-mentioned heating and stirring, it is preferably allowed to stand for 30 to 60 minutes, specifically 30 minutes, 40 minutes, 50 minutes, or 60 minutes.

[0068] In the present invention, after the above treatment, drying is performed. The drying is preferably vacuum drying. The vacuum degree of the vacuum drying is preferably 90-100 kPa, specifically 90 kPa, 95 kPa, or 100 kPa. The drying temperature is preferably 40-50°C, specifically 40°C, 45°C, or 50°C. The drying time is preferably 600-720 min, specifically 600 min, 630 min, 660 min, 690 min, or 720 min.

[0069] In the present invention, after the drying, the powder is preferably cooled and ground. The cooling is preferably performed to room temperature. The grinding is performed until the powder has no visible lumps. After the above treatment, a surface-modified composite powder is obtained.

[0070] About step S3 :

[0071] S3. Mix the epoxy resin with the toughening agent and the defoaming agent, heat them, then add the surface-modified composite powder obtained in step S2, mix them evenly, and degas to obtain a mixed slurry.

[0072] In the present invention, the epoxy resin is preferably at least one of N,N-diglycidyl-p-glycidyloxyaniline and bisphenol A epoxy resin. When the epoxy resin is a composite of N,N-diglycidyl-p-glycidyloxyaniline and bisphenol A epoxy resin, the mass ratio of N,N-diglycidyl-p-glycidyloxyaniline to bisphenol A epoxy resin is preferably (0.1-0.5):1, specifically 0.1:1, 0.2:1, 0.3:1, 0.4:1, or 0.5:1.

[0073] In the present invention, the toughening agent is preferably a reactive epoxy toughening agent CYH-227. In the present invention, the mass ratio of the toughening agent to the epoxy resin is preferably (0.1-0.3):1, specifically 0.1:1, 0.2:1, or 0.3:1.

[0074] In the present invention, the defoaming agent is preferably HX-2080. In the present invention, the mass ratio of the defoaming agent to the epoxy resin is preferably (0.005-0.01):1, specifically 0.005:1, 0.006:1, 0.007:1, 0.008:1, 0.009:1, or 0.01:1.

[0075] In the present invention, the epoxy resin is first mixed with a toughening agent and a defoaming agent and heated. The heating temperature is preferably 50 to 60°C, specifically 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, and 60°C. Stirring is performed during the heating process and after heating to the target temperature. The stirring speed is preferably 800 to 1000 rpm, specifically 800 rpm, 850 rpm, 900 rpm, 950 rpm, and 1000 rpm. The stirring time is preferably 15 to 20 minutes, specifically 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, and 20 minutes. After heating and stirring, the mixture is allowed to stand. The standing time is preferably 5 to 10 minutes, specifically 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, and 10 minutes.

[0076] In the present invention, after the above treatment, the surface-modified composite powder obtained in step S2 is added. In the present invention, the mass ratio of the surface-modified composite powder obtained in step S2 to the epoxy resin is preferably (0.1-0.3):1, specifically 0.1:1, 0.2:1, 0.3:1. In the present invention, after adding the surface-modified composite powder obtained in step S2, stirring is performed. The stirring speed is preferably 800-1000 rpm, specifically 800 rpm, 850 rpm, 900 rpm, 950 rpm, 1000 rpm. The stirring time is preferably 15-20 min, specifically 15 min, 16 min, 17 min, 18 min, 19 min, 20 min. After stirring, the materials are mixed and then allowed to stand. The standing time is preferably 5-10 min, specifically 5 min, 6 min, 7 min, 8 min, 9 min, 10 min. After standing, degassing treatment is performed. The degassing treatment is preferably carried out under vacuum conditions, specifically, in a vacuum drying oven. The vacuum degree of the degassing treatment is preferably 90-100kPa, specifically 90kPa, 91kPa, 92kPa, 93kPa, 94kPa, 95kPa, 96kPa, 97kPa, 98kPa, 99kPa, 100kPa. The temperature of the degassing treatment is preferably 60-70°C, specifically 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C. The duration of the degassing treatment is preferably 15-20min, specifically 15min, 16min, 17min, 18min, 19min, 20min. After the above treatment, a mixed slurry is obtained.

[0077] About step S4 :

[0078] S4. Mix the mixed slurry obtained in step S3 with a curing agent, and perform degassing treatment to obtain a wear-resistant coating.

[0079] In the present invention, the curing agent is preferably an isophorone diamine curing agent. The mass ratio of the curing agent to the epoxy resin in step S3 is preferably (0.2 to 0.45): 1, specifically 0.20: 1, 0.25: 1, 0.30: 1, 0.35: 1, 0.40: 1, 0.45: 1. The mixing method is preferably stirring and mixing. After uniform mixing, degassing is performed. The degassing is preferably performed under vacuum conditions, specifically, in a vacuum drying oven. The vacuum degree of the degassing is preferably 90 to 100 kPa, specifically 90 kPa, 91 kPa, 92 kPa, 93 kPa, 94 kPa, 95 kPa, 96 kPa, 97 kPa, 98 kPa, 99 kPa, 100 kPa. The degassing treatment temperature is room temperature, specifically 18-25°C, specifically 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C, or 25°C. The degassing treatment duration is preferably 15-20 minutes, specifically 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, or 20 minutes. After the above treatment, a wear-resistant coating, i.e., a wear-resistant coating castable, is obtained.

[0080] In a second aspect, the present invention provides a wear-resistant coating for a drill pipe produced by the preparation method described in the above technical solution.

[0081] In a third aspect, the present invention provides a method for preparing a drill rod with a surface wear-resistant coating, comprising the following steps: applying a wear-resistant coating to the surface of the drill rod, curing, and forming a wear-resistant coating; wherein the wear-resistant coating is the wear-resistant coating for the drill rod described in the above technical solution.

[0082] In the present invention, the drill pipe can be any conventional drill pipe in the art, typically a composite material drill pipe; preferably, an epoxy resin-based composite material drill pipe. Specifically, the drill pipe comprises a threaded steel joint, an internally threaded steel joint, and a composite material pipe body. The composite material pipe body is an epoxy resin-based composite material, prepared by combining fibers with resin through a winding molding process. The specific process is not particularly limited and can be a conventional preparation process in the art. The fibers are preferably carbon fibers and / or glass fibers.

[0083] In the present invention, the wear-resistant coating is preferably applied to the surface of the drill rod by pouring. The specific process is preferably as follows: the drill rod is placed in a mold, and the wear-resistant coating is poured into the mold.

[0084] The drill pipe is pre-surface treated; this surface treatment includes sanding the surface of the drill pipe with sandpaper, followed by cleaning and drying. The sandpaper is preferably silicon carbide sandpaper, preferably 120-300 grit, specifically 120 grit, 150 grit, 200 grit, 250 grit, or 300 grit, with 200 grit being more preferred. The cleaning agent used is preferably at least one of anhydrous ethanol and distilled water, with anhydrous ethanol being more preferred. After cleaning and drying, the drill pipe is ready.

[0085] After the drill rod is prepared, it is placed in a mold. The mold includes an external threaded plug, an internal threaded plug, a half-sleeve A, a half-sleeve B and screws. The external threaded plug is connected to the internal threaded steel joint of the drill rod through a threaded connection, the internal threaded plug is connected to the external threaded steel joint of the drill rod through a threaded connection, and the half-sleeve A and half-sleeve B are connected to the plug through screws. A release agent is evenly applied to the inner surface of the half-sleeve, and a casting space for the wear-resistant coating is formed between the half-sleeve and the outer surface of the drill rod. A rectangular opening is set in the middle of the half-sleeve A as a pouring port for the wear-resistant coating. Figure 1-3 As shown, Figure 1 This is a front view of the assembly of the mold and the drill rod in the present invention. Figure 2 for Figure 1 AA direction cross-sectional view, Figure 3 for Figure 1 BB direction cross-sectional view; among them, 1-1 is the composite material pipe body, 1-2 is the external thread steel joint, 1-3 is the internal thread steel joint, 2-1 is the external thread plug, 2-2 is the internal thread plug, 2-3 is the half casing A, 2-4 is the half casing B, 2-5 is the pouring gate, and 2-6 is the pouring space.

[0086] The preparation process of the above-mentioned drill rod with a surface wear-resistant coating is combined with the preparation process of the wear-resistant coating. Specifically, after the drill rod is loaded into the mold, the above-mentioned step S4 is performed, i.e., the process of adding a curing agent and degassing treatment to form the wear-resistant coating is performed. Then, the wear-resistant coating is poured into the mold and then cured.

[0087] In the present invention, the curing is preferably step curing, specifically pre-curing and high-temperature curing are performed in sequence; wherein the pre-curing temperature is preferably 50-70°C, specifically 50°C, 55°C, 60°C, 65°C, and 70°C. The pre-curing time is preferably 120-180 minutes, specifically 120 minutes, 150 minutes, and 180 minutes. The high-temperature curing temperature is preferably 100-150°C, specifically 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, and 150°C. The high-temperature curing time is preferably 180-240 minutes, specifically 180 minutes, 210 minutes, and 240 minutes. The operation of the above-mentioned curing process is specifically to place the mold after casting in a high-temperature furnace, first heat it to the pre-curing temperature for pre-curing, and then heat it to the high-temperature curing temperature for high-temperature curing. After the curing is completed, it is cooled, preferably cooled with the furnace. Then, the mold is disassembled and the surface of the drill rod is turned to obtain a surface wear-resistant coating that meets the thickness requirements. In the present invention, the thickness of the wear-resistant coating on the drill rod surface is preferably 0.5 to 2.0 mm, specifically 0.5 mm, 1.0 mm, 1.5 mm, or 2.0 mm.

[0088] In a fourth aspect, the present invention provides a drill rod with a surface wear-resistant coating, which is prepared by the preparation method described in the above technical solution.

[0089] The wear-resistant coating provided by the present invention first performs a high-temperature oxidation treatment on a composite powder of silicon carbide and diamond, then performs a surface modification treatment using a silane coupling agent solution, and then uniformly mixes an epoxy resin with a toughening agent, a defoaming agent, and the composite powder subjected to the surface modification treatment, degassing treatment, and obtaining a mixed slurry; and then introduces a curing agent to form a wear-resistant coating. The present invention does not directly mix the epoxy resin with the solid powder and additives. Instead, through the above-mentioned step-by-step treatment and mixing, the surface activity of the inorganic filler in the coating material can be improved, the problem of uneven dispersion and poor interface bonding with the matrix can be solved, the wear resistance and toughness of the coating material can be improved, and a wear-resistant coating with uniform thickness and stable performance can be formed on the surface of the drill pipe, thereby improving the wear resistance of the composite drill pipe and helping to extend the service life of the composite drill pipe. In addition, the present invention does not use hydrofluoric acid immersion modification, thereby avoiding the problem of etching the silicon carbide surface and reducing the material strength, decomposing and producing hydrogen fluoride during high-temperature curing and corroding the mold, and causing microbubbles inside the coating to reduce the coating performance, as well as avoiding the problem of the cost of protective facilities and waste liquid treatment caused by the toxicity of hydrofluoric acid.

[0090] The experimental results show that the friction coefficient of the wear-resistant coating of the drill rod of the present invention is below 0.52, and the wear rate is below 0.033mm. 3 / min or less, showing excellent wear resistance.

[0091] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0092] Example 1

[0093] 1. Preparation of wear-resistant coating:

[0094] S1. Placing a composite powder of silicon carbide and diamond into a muffle furnace and performing a high-temperature oxidation treatment in an air atmosphere; the high-temperature oxidation treatment process is as follows: heating from room temperature to 800°C at a rate of 5°C / min and holding at the oxidation temperature for 120 min; then cooling in the furnace and grinding until the powder has no visible agglomerates to obtain a pretreated composite powder;

[0095] The average particle size of the silicon carbide powder is 10 μm, the average particle size of the diamond powder is 15 μm, and the mass ratio of diamond to silicon carbide is 0.1:1.

[0096] S2. Add the pretreated composite powder obtained in step S1 to the silane coupling agent solution, stir continuously at 1500 rpm in a constant temperature water bath at 70° C. for 360 min, and then let it stand for 40 min; then vacuum dry (vacuum degree 90 kPa, drying temperature 50° C., drying time 600 min), then cool in the furnace, and grind until the powder has no visible lumps to obtain a surface-modified composite powder;

[0097] The silane coupling agent solution is prepared by the following method: mixing the silane coupling agent KH550 and distilled water in a mass ratio of 1:3 for hydrolysis, then adding anhydrous ethanol (the mass ratio of the silane coupling agent to the anhydrous ethanol is 1:20) and mixing evenly, and then adding dilute hydrochloric acid to adjust the pH value to 4 to obtain a silane coupling agent solution.

[0098] S3, add toughener CYH-227 (the mass ratio of toughener to epoxy resin is 0.2: 1) and defoamer HX-2080 (the mass ratio of defoamer to epoxy resin is 0.005: 1) to bisphenol A epoxy resin, heat to 50 ° C and stir at 800 rpm for 15 min, and then let it stand for 5 min; then, add the surface-modified composite powder obtained in step S3 (the mass ratio of surface-modified composite powder to epoxy resin is 0.2: 1), stir at 800 rpm for 15 min; then, let it stand in a vacuum drying oven for degassing treatment, the vacuum degree is 90 kPa, the temperature is 60 ° C, and the degassing time lasts for 20 min to obtain a mixed slurry.

[0099] S4, in described mixed slurry, add isophorone diamine curing agent (mass ratio of curing agent and epoxy resin is 0.22: 1), under 400rpm rotating speed, stir 5min, afterwards, be placed in vacuum drying oven and carry out deaeration process, vacuum degree is 90kPa, and temperature is room temperature, and deaeration time continues 20min, obtains wear-resistant coating.

[0100] 2. Preparation of drill pipe with surface wear-resistant coating:

[0101] Install the drill rod into the mold (assemble as shown Figure 1-3 As shown), a wear-resistant coating is poured into the mold, and then placed in a high-temperature furnace for two-stage curing treatment, wherein the first stage pre-curing is maintained at 60°C for 120 minutes, and the second stage high-temperature curing is maintained at 100°C for 180 minutes; then cooled with the furnace, the mold is disassembled, and the surface of the drill rod is turned to obtain a drill rod with a 2 mm thick wear-resistant coating.

[0102] Before assembly, the drill rod is pre-surface treated: the surface of the composite material drill rod is polished with 200-mesh silicon carbide sandpaper, and then the surface of the drill rod is cleaned and dried with anhydrous ethanol.

[0103] The preparation process of the above-mentioned drill rod with a surface wear-resistant coating is combined with the preparation process of the wear-resistant coating. Specifically, after the drill rod is loaded into the mold, the above-mentioned step S4 is performed, i.e., the process of adding a curing agent and degassing treatment to form the wear-resistant coating is performed. Then, the wear-resistant coating is poured into the mold and subsequent processes are performed.

[0104] Example 2

[0105] 1. Preparation of wear-resistant coating:

[0106] S1. Placing a composite powder of silicon carbide and diamond in a muffle furnace and performing a high-temperature oxidation treatment in an air atmosphere; the high-temperature oxidation treatment process is as follows: heating from room temperature to 800°C at a rate of 3°C / min and holding at the oxidation temperature for 120 min; then cooling in the furnace and grinding until the powder has no visible agglomerates to obtain a pretreated composite powder;

[0107] The average particle size of the silicon carbide powder is 10 μm, the average particle size of the diamond powder is 15 μm, and the mass ratio of diamond to silicon carbide is 0.3:1.

[0108] S2. Add the pretreated composite powder obtained in step S1 to the silane coupling agent solution, stir continuously at 1500 rpm in a constant temperature water bath at 70° C. for 360 min, and then let it stand for 40 min; then vacuum dry (vacuum degree 90 kPa, drying temperature 50° C., drying time 600 min), then cool in the furnace, and grind until the powder has no visible lumps to obtain a surface-modified composite powder;

[0109] The silane coupling agent solution is prepared by the following method: mixing the silane coupling agent KH550 and distilled water in a mass ratio of 1:3 for hydrolysis, then adding anhydrous ethanol (the mass ratio of the silane coupling agent to the anhydrous ethanol is 1:20) and mixing evenly, and then adding dilute hydrochloric acid to adjust the pH value to 4 to obtain a silane coupling agent solution.

[0110] S3. Add toughener CYH-227 (the mass ratio of toughener to epoxy resin is 0.2: 1) and defoamer HX-2080 (the mass ratio of defoamer to epoxy resin is 0.005: 1) to N,N-diglycidyl-p-glycidyloxyaniline, heat to 50°C and stir at 900 rpm for 15 min, and then let stand for 5 min; then, add the surface-modified composite powder obtained in step S3 (the mass ratio of surface-modified composite powder to epoxy resin is 0.2: 1), stir at 800 rpm for 15 min; then, place in a vacuum drying oven for degassing treatment, the vacuum degree is 90 kPa, the temperature is 60°C, and the degassing time lasts for 20 min to obtain a mixed slurry.

[0111] S4, in described mixed slurry, add isophorone diamine curing agent (mass ratio of curing agent and epoxy resin is 0.43: 1), under 400rpm rotating speed, stir 5min, afterwards, be placed in vacuum drying oven and carry out deaeration process, vacuum degree is 90kPa, and temperature is room temperature, and deaeration time continues 20min, obtains wear-resistant coating.

[0112] 2. Preparation of drill pipe with surface wear-resistant coating:

[0113] Install the drill rod into the mold (assemble as shown Figure 1-3 As shown), a wear-resistant coating is poured into the mold, and then placed in a high-temperature furnace for two-stage curing treatment, wherein the first stage pre-curing is maintained at 60°C for 120 minutes, and the second stage high-temperature curing is maintained at 100°C for 180 minutes; then cooled with the furnace, the mold is disassembled, and the surface of the drill rod is turned to obtain a drill rod with a 2 mm thick wear-resistant coating.

[0114] Before assembly, the drill rod is pre-surface treated: the surface of the composite material drill rod is polished with 200-mesh silicon carbide sandpaper, and then the surface of the drill rod is cleaned and dried with anhydrous ethanol.

[0115] The preparation process of the above-mentioned drill rod with a surface wear-resistant coating is combined with the preparation process of the wear-resistant coating. Specifically, after the drill rod is loaded into the mold, the above-mentioned step S4 is performed, i.e., the process of adding a curing agent and degassing treatment to form the wear-resistant coating is performed. Then, the wear-resistant coating is poured into the mold and subsequent processes are performed.

[0116] Example 3

[0117] 1. Preparation of wear-resistant coating:

[0118] S1. Placing a composite powder of silicon carbide and diamond in a muffle furnace and performing a high-temperature oxidation treatment in an air atmosphere; the high-temperature oxidation treatment process is as follows: heating from room temperature to 700°C at a heating rate of 3°C / min and holding at the oxidation temperature for 180 min; then cooling in the furnace and grinding until the powder has no visible agglomerates to obtain a pretreated composite powder;

[0119] The average particle size of the silicon carbide powder is 10 μm, the average particle size of the diamond powder is 15 μm, and the mass ratio of diamond to silicon carbide is 0.5:1.

[0120] S2. Add the pretreated composite powder obtained in step S1 to the silane coupling agent solution, and continuously stir at a speed of 1500 rpm in a constant temperature water bath at 80° C. for 360 min, and then let it stand for 30 min; then vacuum dry (vacuum degree 90 kPa, drying temperature 50° C., drying time 600 min), and then cool with the furnace and grind until the powder has no visible lumps to obtain a surface-modified composite powder;

[0121] The silane coupling agent solution is prepared by the following method: mixing the silane coupling agent KH550 and distilled water in a mass ratio of 1:3 for hydrolysis, then adding anhydrous ethanol (the mass ratio of the silane coupling agent to the anhydrous ethanol is 1:20) and mixing evenly, and then adding dilute hydrochloric acid to adjust the pH value to 4 to obtain a silane coupling agent solution.

[0122] S3, add toughener CYH-227 (the mass ratio of toughener to epoxy resin is 0.2: 1) and defoamer HX-2080 (the mass ratio of defoamer to epoxy resin is 0.005: 1) to bisphenol A epoxy resin, heat to 60 ° C and stir at 800 rpm for 15 min, and then let it stand for 5 min; then, add the surface-modified composite powder obtained in step S3 (the mass ratio of surface-modified composite powder to epoxy resin is 0.2: 1), stir at 800 rpm for 15 min; then, let it stand in a vacuum drying oven for degassing treatment, the vacuum degree is 90 kPa, the temperature is 60 ° C, and the degassing time lasts for 20 min to obtain a mixed slurry.

[0123] S4, in described mixed slurry, add isophorone diamine curing agent (mass ratio of curing agent and epoxy resin is 0.22: 1), under 400rpm rotating speed, stir 5min, afterwards, be placed in vacuum drying oven and carry out deaeration process, vacuum degree is 90kPa, and temperature is room temperature, and deaeration time continues 20min, obtains wear-resistant coating.

[0124] 2. Preparation of drill pipe with surface wear-resistant coating:

[0125] Install the drill rod into the mold (assemble as shown Figure 1-3 As shown), a wear-resistant coating is poured into the mold, and then placed in a high-temperature furnace for two-stage curing treatment, wherein the first stage pre-curing is maintained at 60°C for 120 minutes, and the second stage high-temperature curing is maintained at 100°C for 180 minutes; then cooled with the furnace, the mold is disassembled, and the surface of the drill rod is turned to obtain a drill rod with a 2 mm thick wear-resistant coating.

[0126] Before assembly, the drill rod is pre-surface treated: the surface of the composite material drill rod is polished with 200-mesh silicon carbide sandpaper, and then the surface of the drill rod is cleaned and dried with anhydrous ethanol.

[0127] The preparation process of the above-mentioned drill rod with a surface wear-resistant coating is combined with the preparation process of the wear-resistant coating. Specifically, after the drill rod is loaded into the mold, the above-mentioned step S4 is performed, i.e., the process of adding a curing agent and degassing treatment to form the wear-resistant coating is performed. Then, the wear-resistant coating is poured into the mold and subsequent processes are performed.

[0128] Example 4

[0129] The method was implemented in accordance with Example 1, except that the bisphenol A epoxy resin in step S3 was replaced by a composite resin of N,N-diglycidyl-p-glycidyloxyaniline and bisphenol A epoxy resin (the mass ratio of the two resins was 0.3:1).

[0130] Comparative Example 1

[0131] 7075 aluminum alloy drill pipe was used as comparison material.

[0132] Comparative Example 2

[0133] The method was implemented in accordance with Example 1, except that no wear-resistant coating was prepared, and the drill pipe body material without wear-resistant coating was directly used as the comparison material.

[0134] Comparative Example 3

[0135] The method is implemented in accordance with Example 1, except that the pretreatment of step S1 is not performed, and the surface modification treatment of step S2 and subsequent steps S3 to S4 are directly performed on the composite powder of silicon carbide and diamond.

[0136] Comparative Example 4

[0137] The method is implemented in accordance with Example 1, except that after the pretreatment of step S1 is completed, the surface modification treatment of step S2 is not performed, and steps S3 to S4 are directly performed.

[0138] Effect test :

[0139] Friction and wear test: The products of each embodiment and comparative example were tested in a water environment with a load of 100N and a sliding speed of 0.1m / s for 1 hour. Among them, the comparative example 3 was stopped after 5 minutes due to excessive wear speed. The test results are shown in Table 1 and Figure 4-11 ,in, Figure 4 This is the surface wear morphology of the wear-resistant coating of the product obtained in Example 1. Figure 5 This is the surface wear morphology of the wear-resistant coating of the product obtained in Example 2. Figure 6 This is the surface wear morphology of the wear-resistant coating of the product obtained in Example 3. Figure 7 This is the surface wear morphology of the wear-resistant coating of the product obtained in Example 4. Figure 8 This is the surface wear morphology of the 7075 aluminum alloy drill rod in Comparative Example 1. Figure 9 This is the surface wear morphology of the drill rod body material in comparative example 2. Figure 10 This is the surface wear morphology of the wear-resistant coating of the product obtained in Comparative Example 3. Figure 11 This is the surface wear morphology of the wear-resistant coating of the product obtained in Comparative Example 4.

[0140] Toughness: Impact toughness testing was conducted on the products according to GB / T1843-2008. Comparative Examples 1 and 2 are not listed for impact toughness because they use metal materials, a test standard not applicable to metal impact toughness measurements. Comparative Example 3 is a substrate material for wear-resistant coatings, and its impact toughness is not comparable, so the impact toughness is also not listed for Comparative Example 3. See Table 1 for test results.

[0141] Table 1: Test results

[0142] Friction coefficient <![CDATA[Wear rate (mm 3 / min)]]> <![CDATA[Toughness (KJ / m 2 )]]> Example 1 0.3428 0.0008 14.06 Example 2 0.3006 0.0023 10.22 Example 3 0.5142 0.0322 13.68 Example 4 0.4236 0.0156 8.23 Comparative Example 1 0.6327 0.0870 / Comparative Example 2 0.6883 0.1513 / Comparative Example 3 0.5567 0.0532 9.87 Comparative Example 4 0.5833 0.0613 8.78

[0143] It can be seen from the test results in the table above that the friction coefficient of the drill rod with wear-resistant coating obtained in Examples 1-4 of the present invention is below 0.52, and the wear rate is below 0.033mm. 3 / min or less, impact toughness is 8.2KJ / m 2The above shows excellent wear resistance. Compared with Comparative Example 1, the wear resistance of the present invention is higher, proving that the wear resistance of the drill pipe with a wear-resistant coating of the present invention is even better than that of the alloy material. Compared with Comparative Example 2, the wear resistance of the present invention is significantly improved, proving that coating the surface of the composite drill pipe substrate with the wear-resistant coating of the present invention can significantly improve the wear resistance of the composite drill pipe surface. Compared with Comparative Examples 3-4, the wear resistance of the present invention is improved, proving that the specific treatment of the silicon carbide and diamond composite powder by the present invention can effectively improve the wear resistance of the coating.

[0144] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal description of the claims, or if they include equivalent structural elements that are not substantially different from the literal description of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing a wear-resistant coating for a drill pipe, characterized in that: The following steps are involved: S1. performing high-temperature oxidation treatment on a composite powder of silicon carbide and diamond to obtain a pretreated composite powder; S2, mixing the pretreated composite powder obtained in step S1 with a silane coupling agent solution, heating and stirring, and then drying to obtain a surface-modified composite powder; S3, mixing the epoxy resin with the toughening agent and the defoaming agent, heating, then adding the surface-modified composite powder obtained in step S2, mixing evenly, and degassing to obtain a mixed slurry; S4. Mix the mixed slurry obtained in step S3 with a curing agent, and perform degassing treatment to obtain a wear-resistant coating.

2. The preparation method according to claim 1, characterized in that In step S1: The temperature of the high temperature oxidation treatment is 600-800°C, and the holding time is 120-240 minutes; The average particle size of the silicon carbide powder is 5 to 20 μm; The average particle size of the diamond powder is 5 to 30 μm; The mass ratio of diamond to silicon carbide is (0.1-0.5):

1.

3. The preparation method according to claim 1, characterized in that In step S2, the silane coupling agent solution is prepared by the following method: mixing the silane coupling agent with water for hydrolysis, and then adding anhydrous ethanol to obtain the silane coupling agent solution; The mass ratio of the silane coupling agent to water is 1:(3-4); The mass ratio of the silane coupling agent to anhydrous ethanol is 1:(15-30); The pH value of the silane coupling agent solution is 4-5.

4. The preparation method according to claim 1, characterized in that In step S2, the heating temperature is 60-80°C, the stirring speed is 1300-1800 rpm, the heating and stirring time is 360-480 min; and the standing time is 30-60 min.

5. The preparation method according to claim 1, characterized in that In step S3: The epoxy resin is at least one of N,N-diglycidyl-p-glycidyloxyaniline and bisphenol A epoxy resin; The mass ratio of the toughening agent to the epoxy resin is (0.1-0.3):1; The mass ratio of the defoamer to the epoxy resin is (0.005-0.01):1; The mass ratio of the surface-modified composite powder obtained in step S2 to the epoxy resin is preferably (0.1-0.3):

1.

6. The preparation method according to claim 1, characterized in that In step S4, the curing agent is isophorone diamine curing agent; The mass ratio of the curing agent to the epoxy resin in step S3 is (0.2-0.45):

1.

7. A wear-resistant coating for a drill pipe produced by the method according to any one of claims 1 to 6.

8. A method for preparing a drill pipe with a surface wear-resistant coating, comprising the following steps: Apply a wear-resistant coating to the surface of the drill pipe and solidify it to form a wear-resistant coating; wherein the wear-resistant coating is the wear-resistant coating for the drill pipe according to claim 8.

9. The preparation method according to claim 8, characterized in that The curing is step curing, specifically pre-curing and high temperature curing are performed in sequence; The pre-curing temperature is 50-70° C., and the time is 120-180 min; the high-temperature curing temperature is 100-150° C., and the time is 180-240 min.

10. A drill pipe with a surface wear-resistant coating, produced by the preparation method according to any one of claims 8 to 9.

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