Cr2O3-based hydrogen-resistant coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of hydrogen transmission pipeline steel coatings, and particularly discloses a Cr2O3-based hydrogen-resistant coating and a preparation method and application thereof.The Cr2O3-based hydrogen-resistant coating is prepared by taking Cr2O3 as a matrix and doping La2O3 or Y elements; when La2O3 is doped, the doping mass fraction of La2O3 is 2%; when the Y element is doped, the mass fraction of the doped Y element is 2%. According to the Cr2O3-based hydrogen-resistant coating and the preparation method and application thereof, X80 pipeline steel is selected as a base material, advanced plasma spraying equipment is utilized, two composite coatings of Cr2O3-2% La2O3 and Cr2O3-2% Y are prepared, grain boundary hydrogen capture-diffusion of the Cr2O3-based coating is synergistically regulated and controlled through doping of La2O3 and Y, then the hydrogen resistance of the coating can be improved, and the hydrogen resistance of the coating is improved. The problem of hydrogen embrittlement of the hydrogen conveying pipeline steel is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen pipeline steel coatings, and in particular relates to a Cr2O3-based hydrogen-resistant coating and a preparation method and application thereof. Background Art

[0002] Hydrogen holds a vital position in the energy, chemical, and other sectors due to its zero-pollution, high-energy, abundant resources, and wide range of applications. Hydrogen transportation plays a vital role throughout the entire industry chain. Transporting gaseous hydrogen through existing natural gas pipelines provides a cost-effective and efficient option for long-distance hydrogen transportation. However, the storage and transportation stages of the hydrogen energy industry chain face significant technical bottlenecks: hydrogen penetration into metal materials can lead to hydrogen embrittlement failure, significantly shortening equipment life and posing safety risks.

[0003] Currently, the key technological approach to addressing this problem is to prepare hydrogen permeation barrier coatings on the surface of metal substrates. Certain oxides, such as Al2O3, Cr2O3, Y2O3, and Er2O3, are suitable candidates for hydrogen permeation barriers due to their low hydrogen isotope permeability, high strength, and thermal stability. Among them, Cr2O3 coatings are widely used as transition layer materials due to their good thermal expansion coefficient matching with the steel substrate. However, single oxide coatings still suffer from insufficient hydrogen barrier efficiency and poor interface stability under high-temperature and high-pressure conditions, which restricts the large-scale application of hydrogen energy storage and transportation technologies. Therefore, composite coating technology has become a research hotspot. For example, a Cr2O3 / Al2O3 composite film was prepared on the surface of 316L stainless steel using metal organic chemical vapor deposition (MOCVD) technology. The composite film consists of a 174nm Al2O3 outer layer and a 156nm Cr2O3 inner layer. In the temperature range of 823-973K, the permeability reduction factor (PRF) of the composite film reached 230-544, while the PRF values of single Al2O3 and Cr2O3 films of the same thickness were only 95-247 and 24-117 respectively. A Cr2O3 / Y2O3 composite coating was prepared on the surface of 316L stainless steel using MOCVD technology. The composite coating consists of a 420nm Y2O3 outer layer and a 50nm Cr2O3 inner layer. In the temperature range of 823-973K, the PRF of the composite coating reached 167-477, while the PRF of the single Y2O3 coating was only 96-292. It can be seen that the composite coating significantly improves the hydrogen barrier efficiency through its layered structure design.

[0004] From a micromechanistic perspective, the diffusion behavior of hydrogen in oxide coatings is synergistically regulated by defects such as grain boundaries, vacancies, and dopant elements. Grain boundaries, as specialized regions within the crystal structure, offer additional diffusion pathways for hydrogen atoms due to their complex atomic arrangement and higher energy state. Furthermore, the stress field at grain boundaries may also influence the hydrogen diffusion rate. Vacancy defects lower the hydrogen migration barrier, making it easier for hydrogen atoms to move within the lattice, thereby accelerating the diffusion process. Dopant elements, on the other hand, inhibit hydrogen diffusion through a charge compensation effect. Upon entering the oxide lattice, they alter the local charge distribution, forming a binding force on hydrogen atoms and hindering further diffusion. However, existing research has primarily focused on single oxide systems, and a deep understanding of the grain boundary regulation and hydrogen capture mechanisms in Cr2O3-based composite coatings remains lacking. In particular, the segregation behavior of elements at grain boundaries, their interaction with oxygen vacancies, and their regulatory mechanisms for hydrogen diffusion pathways remain largely unexplained, hindering the development of high-performance hydrogen permeation barrier coatings.

[0005] Therefore, based on the existing research on the diffusion behavior of hydrogen in a single oxide system and the current lack of in-depth understanding of the grain boundary regulation effect and hydrogen capture mechanism in the field of Cr2O3-based composite coatings, this field needs to develop a Cr2O3-based hydrogen-resistant coating and its preparation method and application to effectively solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a Cr2O3-based hydrogen-resistant coating, a preparation method and application thereof. The method selects X80 pipeline steel as the base material and uses advanced plasma spraying equipment to prepare two composite coatings: Cr2O3-2% La2O3 and Cr2O3-2% Y. By doping with La2O3 and Y, the grain boundary hydrogen capture and diffusion of the Cr2O3-based coating are synergistically regulated, thereby improving the hydrogen barrier performance of the coating and solving the hydrogen embrittlement problem of hydrogen pipeline steel.

[0007] To achieve the above objectives, the present invention provides a Cr2O3-based hydrogen-resistant coating, comprising Cr2O3 as a matrix and doped with La2O3 or Y element; when doped with La2O3, the mass fraction of La2O3 doping is 2%; when doped with Y element, the mass fraction of Y element doping is 2%.

[0008] The present invention also provides a method for preparing a Cr2O3-based hydrogen-resistant coating, comprising the following steps:

[0009] Step S1: In order to increase the bonding strength between the coating and the substrate, the substrate surface needs to be pretreated before coating;

[0010] Step S2: preparing a Cr2O3-based hydrogen-resistant coating.

[0011] Preferably, step S1 is specifically as follows:

[0012] Step S11: select X80 pipeline steel as the base, and cut the X80 pipeline steel into the required size using a wire-cut electric discharge machine;

[0013] Step S12: Grind the surface of the X80 pipeline steel in stages using #400-#2000 grit sandpaper to completely remove the oxide layer on the surface, laying a good foundation for subsequent processing;

[0014] Step S13: completely immerse the polished X80 pipeline steel in anhydrous ethanol and perform ultrasonic cleaning for 10 minutes to remove any residual surface oil;

[0015] Step S14: After cleaning, the X80 pipeline steel is placed in an oven to be thoroughly dried for subsequent use.

[0016] Preferably, step S2 is specifically as follows:

[0017] Step S21: using composite powder particles of Cr2O3-2%La2O3 or Cr2O3-2%Y as raw materials, and spraying using plasma spraying equipment;

[0018] In step S22, the composite powder particles are heated to a molten or highly molten state, and then accelerated and violently impacted onto the pretreated substrate surface under the drag of the plasma high-speed flame flow, and finally deposited to form a uniform and dense coating, namely, a Cr2O3-based hydrogen-resistant coating.

[0019] Preferably, in step S21, the particle size of the composite powder particles is 15 to 45 μm.

[0020] Preferably, the spraying parameters in step S21 are set as follows: current intensity of 500 A, scanning speed of 20 mm / s, powder feeding rate of 14.6 g / min; at the same time, the N2 carrier gas flow rate is 4 L / min.

[0021] The present invention also provides an application of a Cr2O3-based anti-hydrogen coating in the surface protection of hydrogen pipeline steel.

[0022] The present invention adopts the above-mentioned Cr2O3-based hydrogen-resistant coating and its preparation method and application, and has the following beneficial effects:

[0023] (1) The La2O3-doped Cr2O3 composite coating of the present invention maintains the physical mixing characteristics of the α-Cr2O3 corundum structure and the trigonal La2O3, while the Y-doped system forms a Cr2O3 / Y / Y2O3 three-phase coexistence structure through partial oxidation of the element.

[0024] (2) La2O3 doping in the present invention increases the average hardness of the coating to 810HV (peak 1036HV), which is 34% higher than that of the pure Cr2O3 coating, while Y doping increases the average microhardness of the coating to 779HV (peak 885HV), an increase of 29.2%, demonstrating that both doping systems can effectively enhance the mechanical properties of the coating.

[0025] (3) The hydrogen permeation time (2096s) of the Cr2O3-2%Y coating of the present invention was extended by 27.0%, and the steady-state current density (0.098μA / cm 2 ) is reduced by 65.0%, and has better hydrogen barrier performance, which is attributed to the synergistic mechanism of Y / Y2O3 dual-phase synergistic optimization of coating density and hydrogen diffusion path blocking efficiency.

[0026] (4) The hydrogen permeation time of the Cr2O3-2% La2O3 coating of the present invention is 1651s, and the steady-state current density is 0.28μA / cm 2 The coating structure was optimized by doping with La2O3, significantly extending the hydrogen permeation path.

[0027] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The XRD pattern of a Cr2O3-2% La2O3 coating prepared in Example 1 of a Cr2O3-based hydrogen-resistant coating and its preparation method and application is shown in FIG.

[0029] Figure 2 Surface morphology images of a Cr2O3-2% La2O3 coating prepared in Example 1 of the present invention, a Cr2O3-based hydrogen-resistant coating and its preparation method and application; wherein (a) is a low magnification and (b) is a high magnification;

[0030] Figure 3 The present invention provides a Cr2O3-based hydrogen-resistant coating and its preparation method and application example 1 and example 2 to prepare the microhardness distribution characteristics of the Cr2O3-2% La2O3 coating and the Cr2O3-2% Y coating;

[0031] Figure 4 The present invention provides a Cr2O3-based anti-hydrogen coating and its preparation method and application example 1 for preparing an electrochemical hydrogen permeation curve of a Cr2O3-2% La2O3 coating;

[0032] Figure 5 The XRD pattern of a Cr2O3-2% Y coating prepared in Example 2 of a Cr2O3-based hydrogen-resistant coating and its preparation method and application according to the present invention;

[0033] Figure 6 Surface morphology images of a Cr2O3-2% Y coating prepared in Example 2 of a Cr2O3-based hydrogen-resistant coating and its preparation method and application according to the present invention at different magnifications; (a) is a low magnification and (b) is a high magnification;

[0034] Figure 7 This is an electrochemical hydrogen permeation curve of a Cr2O3-2%Y coating prepared in Example 2 of a Cr2O3-based hydrogen-resistant coating and its preparation method and application. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0036] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0037] Example 1

[0038] A method for preparing a Cr2O3-2% La2O3 coating comprises the following steps:

[0039] Step S1: pre-treating the substrate.

[0040] Step S11: Select X80 pipeline steel as the base and cut the X80 pipeline steel into pieces with a size of 30×20×5mm using an electric spark wire cutting machine. 3 samples.

[0041] Step S12: Use #400-#2000 grit sandpaper to polish the surface of the X80 pipeline steel in stages.

[0042] Step S13: completely immerse the polished X80 pipeline steel in anhydrous ethanol and perform ultrasonic cleaning for 10 minutes.

[0043] Step S14: After cleaning, the X80 pipeline steel is placed in an oven to be thoroughly dried for subsequent use.

[0044] Step S2: preparing a Cr2O3-2%La2O3 coating.

[0045] Step S21: Using Cr2O3-2% La2O3 composite powder particles as raw material, the composite powder particles have a particle size of 15-45 μm, and using plasma spraying equipment (Metco 9MB) for spraying.

[0046] The spraying parameters were set as follows: current intensity of 500A, scanning speed of 20mm / s, powder feeding rate of 14.6g / min, and N2 carrier gas flow rate of 4L / min.

[0047] Step S22: The composite powder particles are heated to a molten or highly molten state, and then accelerated and violently impacted onto the pretreated substrate surface under the drag of the plasma high-speed flame flow, and finally deposited to form a uniform and dense coating, namely, the Cr2O3-2%La2O3 coating.

[0048] The performance of the Cr2O3-2%La2O3 coating prepared in this example was tested:

[0049] (1) Microstructure and composition analysis;

[0050] Experimental process:

[0051] Field emission scanning electron microscopy (FE-SEM, Nova 400Nano) was used for observation. Furthermore, X-ray diffraction (XRD, D / MAX2500PC) was used to fully characterize the sample structure, using a Cu-target Kα X-ray source. The test conditions were set at a scan speed of 1° / min, a diffraction angle scanning range of 5° to 90°, and an operating voltage of 40 kV.

[0052] (1) Phase analysis;

[0053] like Figure 1 As shown, the sharp diffraction peaks of Cr2O3 (PDF#04-005-9887) coexist with the characteristic peaks of La2O3 (PDF#00-005-0602) (2θ = 30.5°, 44.7°, 55.2°, 73.5°, and 79.5°), corresponding to the (101), (110), (112), (210), and (114) crystal planes of the trigonal system (space group P-3m1), respectively. No characteristic peaks of the ternary Cr-La-O compound were detected, indicating that the two phases are physically mixed as independent crystalline phases and that the doping of La2O3 does not change the main corundum structure of Cr2O3 (α phase, space group R3-c).

[0054] (2) morphological analysis;

[0055] like Figure 2 As shown in (a), at low magnification, the coating surface shows typical lamellar structural characteristics, consisting of a large number of flattened areas of molten droplets. Figure 2 As shown in (b), as the magnification increases, three typical structural features can be observed: (1) the completely melted area presents a smooth glassy morphology; (2) the partially melted particles retain the angular characteristics of the original powder; (3) the network of microcracks extends along the lamellar boundaries, accompanied by the formation of pores, the formation of which is related to the release of thermal stress during the rapid solidification of the molten droplet.

[0056] (3) Microhardness

[0057] Experimental Procedure: The coatings were microhardness tested using a Vickers hardness tester (HVS-1000Z). During the test, the applied load was precisely controlled to 300g, and the loading time was set to 10s. Before the test began, the test samples underwent meticulous pretreatment: first, grinding to remove surface imperfections, and then polishing to ensure a smooth and flawless surface. Hardness measurements were systematically taken at multiple locations along the coating thickness, with each sample measured three times to ensure statistical reliability.

[0058] Experimental results: Figure 3 As shown in the Vickers hardness test, the trace addition of 2 wt.% La2O3 increases the coating's maximum hardness to 1036 HV and its average hardness to 810 HV, a 34% improvement over the undoped system (pure Cr2O3 coating: 603 HV). This value not only demonstrates its excellent mechanical properties, but also further verifies the superiority of La2O3 as a hard coating material.

[0059] (4) Hydrogen barrier performance;

[0060] Experimental process: After the sample is degreased and cleaned, the hydrogen-escape side of the sample is nickel-plated in a nickel plating solution with a current density of 5 mA / cm 2 , time is 5.5min. Nickel plating solution composition: 250g / L nickel sulfate + 45g / L nickel chloride + 40g / L boron + 0.2g / L sodium dodecyl sulfate, pH = 3. Hydrogen charging side electrolyte and hydrogen escape side electrolyte: 0.1mol / L NaOH solution. The hydrogen permeation test was carried out using a Devanathan-Stachurski double electrolytic cell. The sample was sandwiched between the two electrolytic cells. The anode cell was the detection cell and the cathode cell was the hydrogen charging cell. A Gamry electrochemical workstation was used to apply polarization to the sample and collect the hydrogen permeation current density. A constant current source was used to charge the sample with hydrogen. The hydrogen charging current density was 1mA / cm 2 , the potential of hydrogen evolution side is 300mV. Before hydrogen charging, constant potential anodic polarization is performed on the hydrogen evolution side. When the current density drops to 0.5μA / cm 2 When the current density of hydrogen permeation reaches a stable state, the test is stopped.

[0061] Experimental results: Figure 4 As shown, the hydrogen permeation current was monitored at t = 1651s, and the steady-state current density was 0.28 μA / cm 2 , compared with steel substrate (t=75s,4.4μA / cm 2 ) and pure Cr2O3 coating (t=1023s,0.81μA / cm 2 ) were reduced by 15.71 times and 2.89 times, respectively, indicating that the doping of La2O3 optimized the coating structure and significantly prolonged the hydrogen permeation path.

[0062] Therefore, the Cr2O3-2%La2O3 composite coating effectively restricts the penetration of hydrogen into X80 pipeline steel and reduces the hydrogen concentration in the matrix.

[0063] Example 2

[0064] A method for preparing a Cr2O3-2%Y coating comprises the following steps:

[0065] Step S1: pre-treating the substrate.

[0066] Step S11: Select X80 pipeline steel as the base and cut the X80 pipeline steel into pieces with a size of 30×20×5mm using an electric spark wire cutting machine. 3 samples.

[0067] Step S12: Use #400-#2000 grit sandpaper to polish the surface of the X80 pipeline steel in stages.

[0068] Step S13: completely immerse the polished X80 pipeline steel in anhydrous ethanol and perform ultrasonic cleaning for 10 minutes.

[0069] Step S14: After cleaning, the X80 pipeline steel is placed in an oven to be thoroughly dried for subsequent use.

[0070] Step S2: preparing a Cr2O3-2%Y coating.

[0071] Step S21: Using Cr2O3-2%Y composite powder particles as raw material, the composite powder particles have a particle size of 15-45 μm, and using plasma spraying equipment (Metco 9MB) for spraying.

[0072] The spraying parameters were set as follows: current intensity of 500A, scanning speed of 20mm / s, powder feeding rate of 14.6g / min, and N2 carrier gas flow rate of 4L / min.

[0073] Step S22: The composite powder particles are heated to a molten or highly molten state, and then accelerated and violently impacted onto the pretreated substrate surface under the drag of the plasma high-speed flame flow, and finally deposited to form a uniform and dense coating, namely the Cr2O3-2%Y coating.

[0074] The Cr2O3-2%Y coating prepared in this example was subjected to performance tests:

[0075] First, the sample was precisely cut into 10×10×5mm pieces using a wire cutting machine. 3The coating surface was then carefully polished using silicon carbide sandpaper with grit ranging from #400 to #2000 until the surface was smooth and flat. The coating was then finally polished using diamond paste (polishing agent grit size 1.5 microns). After polishing, the sample was thoroughly cleaned with alcohol to ensure no residual impurities and quickly dried with cold air.

[0076] (1) Microstructure and composition analysis;

[0077] Experimental process:

[0078] Field emission scanning electron microscopy (FE-SEM, Nova 400Nano) was used for observation. Furthermore, X-ray diffraction (XRD, D / MAX2500PC) was used to fully characterize the sample structure, using a Cu-target Kα X-ray source. The test conditions were set at a scan speed of 1° / min, a diffraction angle scanning range of 5° to 90°, and an operating voltage of 40 kV.

[0079] (1) Phase analysis;

[0080] like Figure 5 As shown, in addition to the dominant Cr2O3 phase (PDF#01-073-4336), characteristic peaks of metallic Y (PDF#01-089-2933) appear at 2θ = 50°, 58.4°, and 65°. Simultaneously, diffraction signals of Y2O3 (PDF#99-000-3963) are detected at 29.1°, 33.7°, 35.9°, 39.8°, and 48.5°. This phenomenon suggests that the Y element undergoes partial oxidation during the preparation process, forming a new Y2O3 phase, confirming the presence of significant phase transformation in the coating system.

[0081] (2) morphological analysis;

[0082] like Figure 6 As shown in (a), at low magnification, the coating surface shows typical lamellar structural characteristics, consisting of a large number of flattened areas of molten droplets. Figure 6 As shown in (b), as the magnification increases, three typical structural features can be observed: (1) the completely melted area presents a smooth glassy morphology; (2) the partially melted particles retain the angular characteristics of the original powder; (3) the network of microcracks extends along the lamellar boundaries, accompanied by the formation of pores, the formation of which is related to the release of thermal stress during the rapid solidification of the molten droplet.

[0083] (3) Microhardness;

[0084] Experimental Procedure: The coatings were microhardness tested using a Vickers hardness tester (HVS-1000Z). During the test, the applied load was precisely controlled to 300g, and the loading time was set to 10s. Before the test began, the test samples underwent meticulous pretreatment: first, grinding to remove surface imperfections, and then polishing to ensure a smooth and flawless surface. Hardness measurements were systematically taken at multiple locations along the coating thickness, with each sample measured three times to ensure statistical reliability.

[0085] Experimental results: Figure 3 As shown in the figure, yttrium doping increases the peak hardness to 885 HV and the average microhardness to 779 HV. This is a 29.2% improvement compared to the pure Cr2O3 coating (603 HV), fully demonstrating the effectiveness of yttrium doping in strengthening chromium oxide-based coatings. The addition of trace amounts of rare earth oxides can significantly increase the coating hardness.

[0086] (4) Hydrogen barrier performance;

[0087] Experimental process: After the sample is degreased and cleaned, the hydrogen-escape side of the sample is nickel-plated in a nickel plating solution with a current density of 5 mA / cm 2 , time is 5.5min. Nickel plating solution composition: 250g / L nickel sulfate + 45g / L nickel chloride + 40g / L boron + 0.2g / L sodium dodecyl sulfate, pH = 3. Hydrogen charging side electrolyte and hydrogen escape side electrolyte: 0.1mol / L NaOH solution. The hydrogen permeation test was carried out using a Devanathan-Stachurski double electrolytic cell. The sample was sandwiched between the two electrolytic cells. The anode cell was the detection cell and the cathode cell was the hydrogen charging cell. A Gamry electrochemical workstation was used to apply polarization to the sample and collect the hydrogen permeation current density. A constant current source was used to charge the sample with hydrogen. The hydrogen charging current density was 1mA / cm 2 , the potential of hydrogen evolution side is 300mV. Before hydrogen charging, constant potential anodic polarization is performed on the hydrogen evolution side. When the current density drops to 0.5μA / cm 2 When the current density of hydrogen permeation reaches a stable state, the test is stopped.

[0088] Experimental results: Figure 7 As shown in the figure, the hydrogen permeation starting time is extended to 2096s, which is 104.9% higher than that of pure Cr2O3 coating and 27.95 times that of steel substrate (t = 75s); the steady-state current density is further reduced to 0.098μA / cm 2 , only pure Cr2O3 coating (0.81μA / cm 2 ) of 12.1% and steel matrix (4.4μA / cm 2 ), with a decrease of 87.9% and 97.8% respectively.

[0089] This phenomenon is attributed to the dual optimization of coating density by Y doping: on the one hand, the Y element forms Y2O3 phase through oxidation, which effectively fills the grain boundary defects; on the other hand, its solid solution strengthening effect improves the blocking efficiency of the hydrogen diffusion path.

[0090] Therefore, the Cr2O3-2%Y composite coating effectively limits the penetration of hydrogen into X80 pipeline steel and reduces the hydrogen concentration in the matrix.

[0091] Therefore, the present invention adopts the above-mentioned Cr2O3-based hydrogen-resistant coating and its preparation method and application. This method selects X80 pipeline steel as the base material and uses advanced plasma spraying equipment to prepare two composite coatings, Cr2O3-2% La2O3 and Cr2O3-2% Y. By doping with La2O3 and Y, the grain boundary hydrogen capture-diffusion of the Cr2O3-based coating is synergistically regulated, thereby improving the hydrogen barrier performance of the coating and solving the hydrogen embrittlement problem of hydrogen pipeline steel.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A Cr2O3-based hydrogen-resistant coating, characterized in that: The method comprises taking Cr2O3 as a matrix and doping La2O3 or Y element; when La2O3 is doped, the mass fraction of La2O3 doping is 2%; when Y element is doped, the mass fraction of Y element doping is 2%.

2. A method for preparing a Cr2O3-based hydrogen-resistant coating according to claim 1, characterized in that: The following steps are involved: Step S1, pre-treating the substrate; Step S2: preparing a Cr2O3-based hydrogen-resistant coating.

3. The method for preparing a Cr2O3-based hydrogen-resistant coating according to claim 2, characterized in that: Step S1 is specifically as follows: Step S11: select X80 pipeline steel as the base, and cut the X80 pipeline steel into a specified size using a wire-cut electric discharge machine; Step S12: Grind the surface of the X80 pipeline steel in stages using #400-#2000 grit sandpaper; Step S13: completely immerse the polished X80 pipeline steel in anhydrous ethanol and perform ultrasonic cleaning for 10 minutes; Step S14: After cleaning, the X80 pipeline steel is placed in an oven to be thoroughly dried for subsequent use.

4. The method for preparing a Cr2O3-based hydrogen-resistant coating according to claim 2, characterized in that: Step S2 is specifically as follows: Step S21: using composite powder particles of Cr2O3-2%La2O3 or Cr2O3-2%Y as raw materials, and spraying using plasma spraying equipment; In step S22, the composite powder particles are heated to a molten or highly molten state, and then accelerated and violently impacted onto the pretreated substrate surface under the drag of the plasma high-speed flame flow, and finally deposited to form a uniform and dense coating, namely, a Cr2O3-based hydrogen-resistant coating.

5. The method for preparing a Cr2O3-based hydrogen-resistant coating according to claim 4, characterized in that: In step S21 , the particle size of the composite powder particles is 15 to 45 μm.

6. The method for preparing a Cr2O3-based hydrogen-resistant coating according to claim 4, characterized in that: In step S21, the spraying parameters are set as follows: current intensity is 500 A, scanning speed is 20 mm / s, powder feeding rate is 14.6 g / min; at the same time, the N2 carrier gas flow rate is 4 L / min.

7. Use of the Cr2O3-based anti-hydrogen coating as claimed in claim 1 in protecting the surface of hydrogen pipeline steel.

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