High-performance steel pipe and method for manufacturing the same

Abstract

The application discloses a kind of high-performance steel pipes and preparation method thereof, belong to steel pipe surface treatment technical field, the high-performance steel pipe includes steel pipe and its surface protective layer;The protective layer includes diamond-like bottom layer, carboxyl functional layer and epoxy resin layer from inside to outside.The preparation method includes the following steps: diamond-like bottom layer is deposited on the surface of steel pipe using magnetron sputtering method;Carboxyl functional layer is introduced on the surface of diamond-like bottom layer by plasma polymerization, then epoxy resin is coated, and epoxy resin layer is formed after curing.The high-performance steel pipe prepared by the above method, the interfacial bonding strength of coating and matrix is obviously improved compared with traditional coating process, the coating is not easy to peel or crack in bending, stretching and cold thermal cycle test, effectively guarantee the long-term service reliability of pipe material under harsh working conditions.

Description

Technical Field

[0001] This invention belongs to the field of steel pipe surface treatment technology, specifically relating to a high-performance steel pipe and its preparation method. Background Technology

[0002] Stainless steel exhibits excellent plasticity during processing due to its good flexibility. It maintains its shape under conditions such as extrusion, tension, and thermal shock, and is not prone to failure such as fracture, hardening, or brittleness. Based on these characteristics, stainless steel pipes are widely used in construction, machinery, chemical, and nuclear power industries. However, after basic forming, various stainless steel products typically require surface treatment to improve their corrosion resistance, wear resistance, and fatigue resistance.

[0003] Among numerous surface treatment technologies, coating technology is widely used due to its relatively mature processes and controllable costs. However, the interfacial bonding strength between the coating and the substrate remains a core factor determining the coating's service performance. In existing technologies, stainless steel pipe surface coatings often suffer from poor bonding. Specifically, microcracks easily initiate at the coating-substrate interface, gradually expanding into coating peeling or cracking under alternating loads or thermal cycling, thus significantly shortening the pipe's service life. This problem is particularly prominent in applications with extremely high reliability requirements, such as nuclear power and chemical equipment, severely hindering the further promotion of coated steel pipes in these fields.

[0004] To improve the aforementioned problem of poor interfacial bonding, existing technologies typically employ methods such as surface pretreatment, introducing transition layers, or optimizing coating formulations. Surface pretreatment increases the surface roughness of the substrate through mechanical or chemical means to enhance the mechanical interlocking between the coating and the substrate; the introduction of transition layers aims to mitigate the differences in physical properties between the substrate and the coating; and coating formulation optimization improves the cohesive strength of the coating itself by adjusting the ratio of binder to functional filler. These methods, to a certain extent, improve the bonding strength between the coating and the substrate and delay the occurrence of early coating failure.

[0005] However, existing improvement methods still have many shortcomings. First, simple surface pretreatment often fails to achieve a balance between increased roughness and sufficient coating wetting; excessive roughness can actually lead to more interface defects. Second, the problem of matching the coefficients of thermal expansion between the transition layer, the substrate, and the coating has not been fundamentally solved, and residual stress at the interface may still induce coating failure under thermal shock conditions. Third, while pursuing high bonding strength, existing coating technologies often fail to address the need for surface functionalization modification. This results in coatings that, while possessing excellent mechanical anchoring properties, lack active sites that can form chemical bonds with external media, thus limiting further improvements in interfacial bonding strength. Furthermore, existing methods still lack sufficient process adaptability and stability in complex service environments, making it difficult to simultaneously meet the comprehensive requirements of high bonding strength, high surface activity, and long-term service reliability. Summary of the Invention

[0006] The purpose of this invention is to provide a high-performance steel pipe and its preparation method, so as to solve the problem of poor interfacial bonding strength between the coating and the substrate in steel pipes.

[0007] The objective of this invention can be achieved through the following technical solutions: The first aspect of the present invention provides a high-performance steel pipe, comprising a steel pipe and a protective layer on its surface; the protective layer comprises, from the inside out, a diamond-like carbon base layer, a carboxyl functional layer and an epoxy resin layer.

[0008] In some possible implementations, the roughness of the diamond-like substrate is 4-50 nm; preferably, the roughness of the diamond-like substrate is 10-50 nm.

[0009] A second aspect of the present invention provides a method for preparing a high-performance steel pipe, comprising the following steps: A diamond-like carbon (DLC) substrate is deposited on the surface of a steel pipe using magnetron sputtering. A carboxyl functional layer is then introduced onto the DLC substrate surface via plasma polymerization, followed by an epoxy resin coating to form an epoxy resin layer. The synergistic effect of the mechanical anchoring of the DLC substrate, the chemical bonding of the carboxyl functional layer, and the functional protection of the epoxy resin surface layer constitutes the core mechanism for achieving high-performance steel pipes. The presence or absence of the carboxyl functional layer has the most significant impact on thermal shock resistance. The polar groups introduced through plasma polymerization, combined with silane-assisted bonding, effectively compensate for the differences in thermophysical properties between the metal substrate and the organic coating, providing a fundamental guarantee for the long-term reliable service of the coating under extreme temperature cycling.

[0010] In some possible implementations, the epoxy resin layer is formed by curing an epoxy resin coating; the epoxy resin coating is prepared by the following steps: By weight, 0.05-0.06 parts filler and 2-3 parts solvent are mixed and dispersed at 45-50℃, followed by 5-6 parts epoxy resin and 0.3-0.4 parts curing agent, then 0.4-0.6 parts diluent and 0.4-0.6 parts plasticizer. The mixture is then ultrasonically stirred at 65-70℃ for 40-60 minutes to obtain an epoxy resin coating. The Ti4O7 / polyaniline composite filler doped in the epoxy resin surface layer forms a hybrid network structure with excellent barrier and conductivity properties through the coordination of phosphonic acid groups with titanium oxides and the in-situ oxidative polymerization of aniline. This filler not only reduces the coefficient of thermal expansion of the epoxy resin matrix and decreases the accumulation of internal stress during temperature cycling, but also inhibits the penetration path of corrosive media through the passivation effect of polyaniline.

[0011] In some possible implementations, the thickness of the epoxy resin layer is 65-75 μm; The curing conditions are 100-110℃ and 40-50 min.

[0012] In some possible implementations, the filler is prepared by the following steps: According to the proportion, 0.4-0.5 mol of 2-phosphonobutane-1,2,4-tricarboxylic acid and 400-500 mL of water were mixed, and the pH was adjusted to 2.5-3. 1.2-1.5 g of Ti4O7 nanoparticles were added and ultrasonically dispersed. Then, 50-60 mmol of aniline was added under ice-water bath conditions. After the addition was completed, the reaction was stirred for 50-60 min. Then, 35-40 mmol of potassium persulfate was added in three batches with an interval of 5-6 h between them. After the addition was completed, the reaction was continued for 10-12 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed with alcohol and water, and dried under vacuum at 60 °C to obtain the filler. Ti4O7 (magnesite phase titanium dioxide) exhibits high corrosion resistance and stability, resisting strong acids, strong alkalis, and chloride ion attack. It does not swell or degrade in neutral salt spray and acts as an inert barrier for long-term stability. In this scheme, 2-phosphonobutane-1,2,4-tricarboxylic acid is used as a multifunctional interfacial bridger. Its phosphonic acid groups are firmly anchored to the Ti4O7 surface through Lewis acid-base coordination and P–O–Ti heterocondensation bonds, while the three carboxyl groups face the organic phase. During the chemical oxidative polymerization stage, the carboxyl groups act as protonic acid dopants, embedding between polyaniline (PANI) chains and inducing the directional growth of PANI on the Ti4O7 surface, forming a dense core-shell coating structure that effectively prevents the aggregation of Ti4O7 nanoparticles. During the epoxy resin curing stage, the remaining carboxyl groups undergo ring-opening esterification with epoxy groups under the promotion of imidazole, achieving covalent bonding between the filler and the resin matrix, significantly improving interfacial compatibility. The introduction of PANI endows the coating with excellent passivation protection capabilities. Its reversible redox activity can form a dense passivation film on the metal substrate surface, blocking Cl. -The coating provides penetration channels for corrosive ions; simultaneously, the conductive network of Ti4O7 promotes uniform charge distribution within the coating, inhibiting localized galvanic corrosion and pitting corrosion initiation. The resulting PANI-PBTCA-Ti4O7 / EP composite coating possesses a triple protection mechanism combining physical barriers, chemical bonding interfaces, and electrochemical activity, exhibiting excellent resistance to neutral salt spray, long-lasting corrosion protection, and good coating adhesion.

[0013] In some possible implementations, the working gas for magnetron sputtering is a mixture of argon and methane, with a total flow rate maintained at 20-30 sccm; During the deposition of diamond-like carbon substrate, the surface roughness of the film is controlled by adjusting the methane flow rate. The methane flow rate is set to 3 to 5 sccm, and the roughness is 4-10 nm. Methane flow rate 5 to 10 sccm, roughness 10-50 nm; The deposition time is 30-120 minutes, and the substrate temperature is maintained between room temperature and 150°C.

[0014] The diamond-like intermediate layer is deposited by magnetron sputtering. Its surface roughness can be varied from several nanometers to tens of nanometers by precisely controlling the flow rate of carbon-containing gas. This rough structure not only increases the physical contact area between the coating and the substrate, forming an effective mechanical interlocking effect, but also provides sufficient anchoring sites for the attachment of the upper carboxyl functional layer, so that the interfacial bonding changes from a single physical adsorption to a synergistic effect of physical interlocking and chemical bonding.

[0015] In some possible implementations, the working gas for plasma polymerization comprises a mixture of argon, acetylene, acrylic acid vapor, and auxiliary gases; the working pressure is 1000-2500 Pa, the discharge voltage is set to 3.0-4.0 kV, and the discharge mode is pulsed. Specific parameters include: pulse frequency 50-500 Hz, duty cycle 5%-30% (i.e., on-time t_on is 50-300 μs, off-time t_off is 0.5-5 ms). The temperature is maintained between 40-50℃.

[0016] In some possible implementations, the total flow rate of the mixed gas is set to 5-30 sccm; the total flow rate of acetylene is set to 1-5 sccm; the flow ratio of acetylene to acrylic acid vapor is 0.1-0.5:2; argon is used as the carrier gas and dilution gas; the auxiliary gas is tetramethylsilane (volatile), with a flow rate set to 0.1-0.5 sccm. Controllable polymerization of the monomer is achieved in the plasma tail region using acrylic acid as the functional monomer, acetylene as the crosslinking regulator, and tetramethylsilane as the auxiliary gas. This layer is rich in polar functional groups such as carboxyl groups, which can form covalent bonds or hydrogen bonds with the active carbon sites of the diamond-like carbon substrate and the epoxy groups of the epoxy resin surface layer, respectively, constructing a chemical bridging network that spans the three-phase interface. The introduction of tetramethylsilane further forms a Si-OC flexible bonding structure, endowing the functional layer with the ability to adapt bond angles during thermal expansion and contraction, effectively alleviating the interfacial shear stress caused by the difference in thermal expansion coefficients between the metal substrate and the organic coating.

[0017] In some possible implementations, the steel pipe is cleaned before depositing the diamond-like carbon (DLC) underlayer: the steel pipe is ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water, dried with nitrogen, and then subjected to plasma cleaning. The argon flow rate is set to 5-15 sccm, the working pressure is controlled at 150-250 Pa, the discharge voltage is 3.5-4.5 kV, and the treatment time is 5-15 min, in order to remove the oxide layer and contaminants on the steel pipe surface. Surface activation treatment uses plasma cleaning technology, which removes organic contaminants and passivation films from the steel pipe surface by bombardment with high-energy particles in an argon atmosphere. At the same time, it causes the surface atoms to reconstruct and form active sites, providing a clean and highly reactive interface basis for the subsequent coating deposition, fundamentally improving the initial contact state between the coating and the substrate.

[0018] The beneficial effects of this invention are: This invention provides a high-performance steel pipe and its preparation method. The method involves constructing a transition layer with a specific interface structure on the surface of a stainless steel substrate, and employing an in-situ plasma-assisted polymerization process to form an interfacial bonding region between the steel pipe and the functional coating (epoxy resin layer) that is synergistically enhanced by chemical bonding and physical anchoring.

[0019] The method disclosed in this invention first performs surface activation treatment on the steel pipe to remove the surface passivation film and introduce polar functional groups. Then, by controlling the mixing ratio of carbon-containing gas and functional monomers in the plasma discharge atmosphere, a diamond-like carbon (DLC) intermediate layer with controllable roughness and a carboxyl-rich functional layer are sequentially deposited on the substrate surface. This allows for a gradient transition between the coating system and the steel pipe substrate, from inorganic metal to DLC and then to organic polymer, thereby significantly suppressing interfacial stress concentration. The high-performance steel pipe prepared by this method exhibits significantly improved interfacial bonding strength between the coating and the substrate compared to traditional coating processes. The coating is less prone to peeling or cracking during bending, tensile, and thermal cycling tests, effectively ensuring the long-term reliability of the pipe under harsh operating conditions. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] The following is a detailed description of a high-performance steel pipe and its preparation method according to an embodiment of this application.

[0022] The following is a detailed description with reference to specific examples.

[0023] Example 1 This embodiment provides a high-performance steel pipe, which includes a steel pipe and a protective layer on its surface; the protective layer includes, from the inside out, a diamond-like carbon (DLC) underlayer, a carboxyl functional layer, and an epoxy resin layer; the preparation method of the high-performance steel pipe includes the following steps: Cleaning the steel pipe: The steel pipe is ultrasonically cleaned in sequence with acetone, anhydrous ethanol and deionized water. After being dried with nitrogen, plasma cleaning is performed. The argon flow rate is set to 10 sccm, the working pressure is controlled at 200 Pa, the discharge voltage is 4kV, and the processing time is 10 min.

[0024] A diamond-like carbon (DLC) substrate was deposited on the surface of a steel pipe using magnetron sputtering. The working gas for magnetron sputtering was a mixture of argon and methane, with a total flow rate maintained in the range of 20-30 sccm. The methane flow rate was set to 10 sccm, the roughness was 30-50 nm, the deposition time was 120 min, and the substrate temperature was maintained between room temperature and 150 °C.

[0025] A carboxyl functional layer was introduced onto the surface of a diamond-like carbon (DLC) substrate via plasma polymerization. The working gas for plasma polymerization consisted of a mixture of argon, acetylene, acrylic acid vapor, and an auxiliary gas. The working pressure was 2000 Pa, the discharge voltage was set to 3.0 kV, the discharge mode was pulsed, the discharge time was 50 μs, the shutdown time was 500 μs, and the frequency was 500 kHz. The temperature was maintained between 40-50 °C. The total flow rate of the mixed gas was set to 30 sccm; the total flow rate of acetylene was set to 1 sccm; the flow ratio of acetylene to acrylic acid vapor was 0.1:2; argon was used as both the carrier gas and the dilution gas; and the auxiliary gas was tetramethylsilane, with a flow rate set to 0.1 sccm.

[0026] To form an epoxy resin layer, an epoxy resin layer was formed by coating the carboxyl functional layer with epoxy resin. According to the specified ratio, 0.4 mol of 2-phosphonobutane-1,2,4-tricarboxylic acid and 400 mL of water were mixed, and the pH was adjusted to 2.5 with 1 mol / L ammonia. 1.2 g of Ti4O7 nanoparticles were added, and after ultrasonic dispersion, 50 mmol of aniline was added under ice-water bath conditions. After the addition was complete, the mixture was stirred for 50 min. Then, a total of 35 mmol of potassium persulfate was added in three batches, with an interval of 5 h between each batch. After the addition was complete, the mixture was reacted for another 10 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed with alcohol and water, and dried under vacuum at 60 °C to obtain the filler.

[0027] By weight, 0.05 parts of filler and 2 parts of solvent (n-butanol and N-methylpyrrolidone, volume ratio 2:1) are mixed and dispersed at 50°C. Then, 5.5 parts of epoxy resin (epoxy resin E51) and 0.35 parts of curing agent (2-ethyl-4-methylimidazolium) are added. Next, 0.5 parts of diluent (ethyl acetate) and 0.5 parts of plasticizer (dibutyl phthalate) are added. The mixture is ultrasonically stirred at 70°C for 60 min to obtain an epoxy resin coating.

[0028] An epoxy resin coating is applied to the surface of the carboxyl functional layer. The thickness of the epoxy resin layer is 65-75 μm. The curing conditions are 100°C and 50 min.

[0029] Example 2 This embodiment provides a high-performance steel pipe. The difference between this embodiment and Embodiment 1 is that the preparation conditions of the diamond-like carbon substrate are different: the methane flow rate is set to 5 sccm and the surface roughness of the film is 10-30 nm.

[0030] The remaining raw materials and preparation process are the same as in Example 1.

[0031] Example 3 This embodiment provides a high-performance steel pipe. The difference between this embodiment and Embodiment 1 is that the preparation conditions of the diamond-like carbon substrate are different: the methane flow rate is set to 4 sccm and the surface roughness of the film is 4-10 nm.

[0032] The remaining raw materials and preparation process are the same as in Example 1.

[0033] Example 4 This embodiment provides a high-performance steel pipe. Compared with Embodiment 1, the preparation conditions of the carboxyl functional layer are different: the total flow rate of the mixed gas is set to 30 sccm; the total flow rate of acetylene is set to 3 sccm; the flow ratio of acetylene to acrylic acid vapor is 0.3:2; argon is used as the carrier gas and dilution gas; the auxiliary gas is tetramethylsilane, and the flow rate is set to 0.3 sccm.

[0034] The remaining raw materials and preparation process are the same as in Example 1.

[0035] Example 5 This embodiment provides a high-performance steel pipe. Compared with Embodiment 1, the preparation conditions of the carboxyl functional layer are different: the total flow rate of the mixed gas is set to 30 sccm; the total flow rate of acetylene is set to 5 sccm; the flow ratio of acetylene to acrylic acid vapor is 0.5:2; argon is used as the carrier gas and dilution gas; the auxiliary gas is tetramethylsilane, and the flow rate is set to 0.5 sccm.

[0036] Example 6 This embodiment provides a high-performance steel pipe. Compared with Embodiment 1, the preparation conditions of the carboxyl functional layer are different: the total flow rate of the mixed gas is set to 30 sccm; the total flow rate of acetylene is set to 5 sccm; the flow ratio of acetylene to acrylic acid vapor is 0.5:2; argon is used as the carrier gas and dilution gas; the auxiliary gas is tetramethylsilane, and the flow rate is set to 0.3 sccm.

[0037] The remaining raw materials and preparation process are the same as in Example 1.

[0038] Example 7 This embodiment provides a high-performance steel pipe. The difference between this embodiment and Embodiment 1 is that the epoxy resin coating ratio is different: by weight, 0.05 parts of filler and 2 parts of solvent (n-butanol and N-methylpyrrolidone, volume ratio 2:1) are mixed and dispersed at 50°C, then 5 parts of epoxy resin (epoxy resin E51) and 0.3 parts of curing agent (2-ethyl-4-methylimidazolium) are added, followed by 0.5 parts of diluent (ethyl acetate) and 0.5 parts of plasticizer (dibutyl phthalate). The mixture is ultrasonically stirred at 70°C for 60 minutes to obtain the epoxy resin coating.

[0039] The remaining raw materials and preparation process are the same as in Example 1.

[0040] Example 8 This embodiment provides a high-performance steel pipe. The difference between this embodiment and Embodiment 1 is that the epoxy resin coating formulation is different: by weight, 0.06 parts of filler and 3 parts of solvent (n-butanol and N-methylpyrrolidone, volume ratio 2:1) are mixed and dispersed at 50°C, then 6 parts of epoxy resin (epoxy resin E51) and 0.4 parts of curing agent (2-ethyl-4-methylimidazolium) are added, followed by 0.5 parts of diluent (ethyl acetate) and 0.5 parts of plasticizer (dibutyl phthalate). The mixture is ultrasonically stirred at 70°C for 60 minutes to obtain the epoxy resin coating.

[0041] The remaining raw materials and preparation process are the same as in Example 1.

[0042] Example 9 This embodiment provides a high-performance steel pipe. The difference between this embodiment and Embodiment 1 lies in the different fillers in the epoxy resin coating: According to the specified ratio, 0.5 mol of 2-phosphonobutane-1,2,4-tricarboxylic acid and 500 mL of water were mixed, and the pH was adjusted to 2.5 with 1 mol / L ammonia. 1.5 g of Ti4O7 nanoparticles were added and ultrasonically dispersed. Then, 60 mmol of aniline was added under ice-water bath conditions. After the addition was complete, the reaction was stirred for 60 min. Then, a total of 40 mmol of potassium persulfate was added in three batches with an interval of 6 h between them. After the addition was complete, the reaction was continued for 112 h. After the reaction was completed, the mixture was filtered under reduced pressure, washed with alcohol and water, and dried under vacuum at 60 °C to obtain the filler.

[0043] The remaining raw materials and preparation process are the same as in Example 1.

[0044] Comparative Example 1 The difference between this comparative example and Example 1 is that there is no carboxyl functional layer; that is, the epoxy resin coating is directly applied to the diamond-like carbon substrate. The other raw materials and preparation process are the same as in Example 1.

[0045] Comparative Example 2 The difference between this comparative example and Example 1 is that the preparation conditions of the carboxyl functional layer are different: no auxiliary gas is added, while the other raw materials and preparation process are the same as in Example 1.

[0046] Comparative Example 3 The difference between this comparative example and Example 1 is that no filler was added, while the other raw materials and preparation process remained the same as in Example 1.

[0047] Comparative Example 4 The difference between this comparative example and Example 1 is that the epoxy resin coating was applied directly after cleaning the steel pipe, while the other raw materials and preparation process remained the same as in Example 1.

[0048] Test case Performance tests were conducted on Examples 1-9 and Comparative Examples 1-4, and the adhesion of the epoxy resin layer was tested according to GB / T 5210—2006.

[0049] According to GB / T 10125-2021, the epoxy resin layer's resistance to neutral salt spray should be tested. If blistering, rusting, or coating peeling occurs, it is considered to have failed.

[0050] Thermal shock conditions: -65℃ The coating adhesion was tested after thermal shock at +150℃ for 1000 cycles, with each temperature point exposed for 30 minutes and the transition time not exceeding 1 minute.

[0051] The results are shown in Table 1: Table 1

[0052] As shown in Table 1, the initial adhesion of all embodiments was within the range of 25.3–27.9 MPa, and the neutral salt spray resistance was greater than 1000 h, demonstrating good and stable coating adhesion and corrosion resistance. After undergoing alternating thermal shocks at -65℃ and +150℃, the adhesion of the embodiments remained between 18.2 and 22.9 MPa, with retention rates generally exceeding 70%. Among them, the adhesion of embodiments 4, 5, 6, and 9 after thermal shocks was all higher than 22 MPa, showing excellent resistance to thermal cycling peeling. In contrast, Comparative Example 1, lacking a carboxyl functional layer, experienced a sharp drop in adhesion to 8.5 MPa after thermal shock; Comparative Example 2, without the addition of an auxiliary gas (tetramethylsilane), while exhibiting acceptable initial adhesion and salt spray resistance, only achieved an adhesion of 16.4 MPa after thermal shock, significantly lower than the other examples; Comparative Example 3, without filler, saw its salt spray resistance drop to 761 hours, with an adhesion of only 7.5 MPa after thermal shock; Comparative Example 4, without any transition layer, had the lowest initial adhesion (21.5 MPa), a salt spray resistance of 864 hours, and an adhesion of only 4.8 MPa after thermal shock. These data indicate that the "diamond-like carbon substrate" constructed in this invention... Carboxyl functional layer The epoxy resin layer composite structure, especially the synergistic effect of acetylene, acrylic acid and tetramethylsilane in the functional layer, as well as the modification of epoxy resin by fillers, can significantly improve the interfacial bonding stability of the coating under severe thermal shock conditions and effectively inhibit coating peeling and cracking failure.

[0053] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0054] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high performance steel pipe characterized by, It includes a steel pipe and a protective layer on its surface; the protective layer, from the inside out, includes a diamond-like carbon base layer, a carboxyl functional layer, and an epoxy resin layer.

2. A high performance steel pipe according to claim 1, characterized in that The roughness of the diamond-like substrate is 4-50 nm.

3. A method for preparing a high-performance steel pipe, used to prepare the high-performance steel pipe according to any one of claims 1-2, characterized in that, Includes the following steps: A diamond-like carbon (DLC) substrate is deposited on the surface of a steel pipe using magnetron sputtering. A carboxyl functional layer is then introduced onto the surface of the DLC substrate via plasma polymerization, followed by coating with epoxy resin to form an epoxy resin layer.

4. The method for preparing a high-performance steel pipe according to claim 3, characterized in that, The epoxy resin layer is formed by curing an epoxy resin coating. The epoxy resin coating is prepared by the following steps: by weight, 0.05-0.06 parts of filler and 2-3 parts of solvent are mixed and dispersed at 45-50℃, then 5-6 parts of epoxy resin and 0.3-0.4 parts of curing agent are added, followed by 0.4-0.6 parts of diluent and 0.4-0.6 parts of plasticizer. The mixture is then ultrasonically stirred at 65-70℃ for 40-60 minutes to obtain the epoxy resin coating.

5. The method for preparing a high-performance steel pipe according to claim 3, characterized in that, The thickness of the epoxy resin layer is 65-75 μm; The curing conditions are 100-110℃ and 40-50 min.

6. The method for preparing a high-performance steel pipe according to claim 4, characterized in that, The filler is prepared by the following steps: 2-phosphonobutane-1,2,4-tricarboxylic acid was mixed with water, the pH was adjusted to 2.5-3, Ti4O7 nanoparticles were added, and after ultrasonic dispersion, aniline was added under ice-water bath conditions. After the addition was complete, the reaction was stirred and potassium persulfate was added and stirred to obtain the filler.

7. The method for preparing a high-performance steel pipe according to claim 3, characterized in that, The working gas for magnetron sputtering is a mixture of argon and methane, with a total flow rate maintained at 20-30 sccm. The surface roughness of the film is controlled by adjusting the methane flow rate during the deposition of the diamond-like carbon substrate. The deposition time is 30-120 min, and the substrate temperature is maintained between room temperature and 150°C.

8. The method for preparing a high-performance steel pipe according to claim 3, characterized in that, The working gas for plasma polymerization consists of a mixture of argon, acetylene, acrylic acid vapor, and auxiliary gas; the working pressure is 1000-2500 Pa, the discharge voltage is set to 3.0-4.0 kV, and the discharge mode is pulsed.

9. The method for preparing a high-performance steel pipe according to claim 8, characterized in that, The total flow rate of the mixture is set to 5-30 sccm; The total acetylene flow rate is set to 1-5 sccm; the flow rate ratio of acetylene to acrylic acid vapor is 0.1-0.5:

2. Argon was used as both a carrier gas and a dilution gas. The auxiliary gas is tetramethylsilane, and the flow rate is set to 0.1-0.5 sccm.

10. The method for preparing a high-performance steel pipe according to claim 3, characterized in that, Cleaning the steel pipe before depositing diamond-like carbon (DLC) substrate: The steel pipe is ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water. After being dried with nitrogen, plasma cleaning is performed. The argon flow rate is set to 5-15 sccm, the working pressure is controlled at 150-250 Pa, the discharge voltage is 3.5-4.5 kV, and the processing time is 5-15 min.

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