Application of composite coating formed by titanium oxide and chromium oxide in hydrogen resistance

Abstract

The invention provides an application of a composite coating formed by titanium oxide and chromium oxide in hydrogen resistance, which comprises the following steps: substrate preparation: cutting a metal sample into a metal substrate, pretreating the surface of the metal substrate, polishing, cleaning and drying; cr2O3-10% TiO2 composite powder is adopted, the composite powder is heated to be in a molten or molten state, and under traction of plasma high-speed flame flow, the composite powder impacts the surface of the base body in an accelerated mode and deposits to form the ceramic coating. According to the application of the composite coating formed by the titanium oxide and the chromium oxide in hydrogen resistance, the hydrogen permeation current is reduced, so that the hydrogen resistance of the coating is enhanced.

Description

Technical Field

[0001] The present invention relates to the field of surface treatment, and in particular to the application of a composite coating formed by titanium oxide and chromium oxide in hydrogen resistance. Background Art

[0002] Hydrogen energy has the advantages of being renewable, having a high calorific value for combustion, and having no pollution in combustion products, and plays an increasingly important role in modern society. In long-distance hydrogen transportation, pipeline transportation is recognized as the most economical method. However, due to the characteristics of small hydrogen molecule volume and fast diffusion, hydrogen is very easy to enter the alloy interior, causing changes in the organizational structure, resulting in a decrease in mechanical properties (tensile strength, fatigue strength, etc.), and even fracture, posing a threat to hydrogen transmission and the safe use of structural materials.

[0003] Currently, people set a hydrogen barrier layer on the inner wall of steel pipes to prevent or delay the diffusion of hydrogen inside the steel pipes to ensure the comprehensive performance of the steel. Some oxide ceramic coatings such as Al 2 O 3 coating, Er 2 O 3 coating, ZrO 2 coating, Y 2 O 3 coating and their composite coatings are currently the most promising hydrogen permeation resistance coatings. The high hydrogen permeation coefficient may be because the molecules contain strong ionic bonds, making the metal and oxygen atoms closely connected, thereby affecting the dissolution and diffusion of hydrogen. Cr 2 O 3 As a new type of hydrogen permeation resistance material, it has good thermal stability and a thermal expansion coefficient similar to that of stainless steel, and can be used to reduce the thermal mismatch between stainless steel and the coating. For example, He et al. prepared an Al 2 O 3 / Cr 2 O 3 composite film on 316L stainless steel by metal-organic chemical vapor deposition, solving the thermal matching problem between stainless steel and the coating. Zhang et al. deposited Al 2 O 3 on the surface of Cr 2 O 3 to prepare an Al 2 O 3 / Cr 2 O 3 bipolar oxide barrier layer. Experiments have proved that the hydrogen permeation resistance performance of this bipolar oxide is better than that of the original oxide and Cr 2 O 3 film. In addition, Cr 2 O 3Due to its strong internal ionic bonds, it has a good inhibitory effect on the infiltration of hydrogen isotopes. Chen et al. used first-principles calculations to study the diffusion of hydrogen in the Cr 2 O 3 system. The study found that in the Cr 2 O 3 crystal, the most stable positions of hydrogen atoms are on both sides of the center of the unoccupied O octahedral interstitial sites, and the potential barrier for hydrogen atom diffusion is on the O atomic plane of adjacent octahedral interstitials. The diffusion activation energy is 0.73 eV, and the diffusion coefficient of hydrogen atoms in Cr 2 O 3 is 5.03×10 -10 cm 2 / s at 500 °C, which is much smaller than the diffusion coefficient of 9.94×10 -4 cm 2 / s in Q235 stainless steel. Li et al. used radio frequency magnetron sputtering method to prepare a Cr 2 O 3 hydrogen isotope permeation barrier on 316L stainless steel. The results showed that the D-PRF values of 0.5 μm Cr 2 O 3 -HIPB at 700 °C and 400 °C are 48 and 152 respectively. The above research results all show that Cr 2 O 3 contains strong ionic bonds and can effectively prevent the diffusion of hydrogen, and it is a material with great application potential.

[0004] At present, there are various methods for preparing hydrogen-blocking coatings, such as hot dip aluminizing, physical vapor deposition, plasma spraying, chemical vapor deposition, electrochemcial deposition, and sol-gel method, etc. The ceramic coatings produced by plasma spraying process are both economical and convenient and can meet the usage requirements. Preparing Cr 2 O 3 ceramic coatings by plasma spraying can significantly improve the corrosion resistance and wear resistance of workpieces. Aiming at the problems of large brittleness and many structural defects of Cr 2 O 3 -based ceramic coatings, such as easy cracking and peeling during use, by adding other phases, not only retains the excellent properties of the matrix, but also can reduce defects such as pores and cracks in the coating, and broaden its application fields.

[0005] TiO 2 is a common thermal spraying material and is often used to improve the properties of coatings. Gao et al. prepared Al 2 O 3 -ZrO 2 composite coatings by plasma spraying and modified them by adding TiO 2 . The study found that Al2 O 3 -ZrO 2 -TiO 2 The microstructure of the coating is denser than that of the Al 2 O 3 -ZrO 2 coating, with fewer microcracks and more amorphous structures. In addition, some scholars have also found that titanium compounds have excellent hydrogen barrier properties. Zhu et al. used 316L stainless steel as the substrate and obtained FeAl / Al 2 O 3 / TiO 2 composite anti-tritium coatings by pack cementation and sol-gel methods. The study found that the FeAl / Al 2 O 3 / TiO 2 composite coating has better room-temperature hydrogen resistance than the FeAl / Al 2 O 3 coating. However, at present, there are many studies on the application of Cr 2 O 3 and TiO 2 in the fields of corrosion protection, thermal barrier coatings, hydrophobic coatings, catalytic reactions, and tribology. However, there are few reports on composite coatings with a hydrogen permeation barrier constructed with Cr 2 O 3 as the main body doped with TiO 2 .

[0006] Therefore, in this paper, using an X80 pipeline steel substrate and a plasma spraying device, Cr 2 O 3 coatings and Cr 2 O 3 -10%TiO 2 composite hydrogen barrier coatings were prepared, and their hydrogen barrier properties and mechanical properties were studied. First-principles calculations were used to reveal the synergistic mechanism of TiO 2 on the hydrogen barrier properties of Cr 2 O 3 -based coatings at the atomic scale, providing experimental evidence and theoretical support for the permeation behavior of hydrogen in Cr 2 O 3 and its composite hydrogen barrier coatings and the hydrogen damage mechanism. Summary of the Invention

[0007] The purpose of the present invention is to provide an application of a composite coating formed by titanium oxide and chromium oxide in hydrogen barrier. The doping of TiO 2 can significantly improve the surface finish of the coating and reduce pores. The doping of TiO 2The addition increases the time for hydrogen to penetrate the coating, reduces the hydrogen permeation current, and thus enhances the hydrogen-blocking performance of the coating. Using first-principles calculations, the synergistic mechanism of the hydrogen-blocking performance of the Cr 2 - 2 O 3 -based coating is revealed at the atomic scale, providing experimental evidence and theoretical support for the penetration behavior of hydrogen and the mechanism of hydrogen damage in Cr 2 O 3 and its composite hydrogen-blocking coatings.

[0008] To achieve the above object, the present invention provides an application of a composite coating formed by titanium oxide and chromium oxide in hydrogen blocking, including the following steps:

[0009] Substrate preparation: Cut the sample into a metal substrate, and perform pretreatment on the surface of the metal substrate, including grinding, cleaning, and drying;

[0010] Ceramic layer preparation: Use Cr 2 O 3 and TiO 2 composite powder. The composite powder is heated to a molten or fused state and, under the drag of a high-speed plasma jet, is accelerated to impact the surface of the substrate and deposit to form a ceramic coating.

[0011] Preferably, the working parameters during plasma spraying are as follows:

[0012] Current 450 - 500 A, scanning speed 18 - 20 mm / s, powder feeding rate 13 - 14.6 g / min, carrier gas flow rate 3.5 - 4 L / min.

[0013] Preferably, the particle size of the composite powder is 15 - 45 μm.

[0014] Preferably, the metal substrate includes pipeline steel and stainless steel.

[0015] Preferably, in the composite powder, the mass ratio of Cr 2 O 3 : TiO 2 is 1:0.08 - 0.1.

[0016] Preferably, the thickness of the ceramic coating is 100 - 300 μm.

[0017] Therefore, the present invention adopts the above application of a composite coating formed by titanium oxide and chromium oxide in hydrogen blocking, and the technical effects are as follows:

[0018] (1) Research has confirmed that the TiO 2 -doped coating has a smoother surface finish and fewer pores, but reduces the hardness of the composite coating by 12.6%. TiO 2The doping increases the time for hydrogen to penetrate the coating, reduces the hydrogen permeation current, and enhances the hydrogen-blocking performance of the coating.

[0019] (2) Hydrogen atoms are prone to adsorption on the α-Fe(001) surface, and the adsorbed hydrogen atoms further diffuse inward, causing hydrogen damage to the substrate; on the contrary, for Cr 2 O 3 (0001) surface, the adsorption energy of hydrogen atoms is positive, indicating that H atoms are not easily adsorbed on the Cr 2 O 3 (0001) surface, which shows that the dense chromium oxide layer can prevent the adsorption of H on the surface, thereby reducing the amount of H atoms penetrating into the substrate.

[0020] (3) On the α-Fe(001) and Cr 2 O 3 (0001) surface, the formation of O vacancies is more favorable than the formation of cation vacancies. The movement of H into the interior of defect-free Cr 2 O 3 requires more energy. This means that the ideal oxide film without vacancies can prevent the diffusion of H atoms. Vacancies promote the penetration of H atoms, ultimately leading to hydrogen damage to the substrate.

[0021] (4) At the α-Fe(001) / Cr 2 O 3 (0001) interface, the unoccupied O octahedral interstitial sites and oxygen vacancies have good hydrogen-trapping ability. When hydrogen atoms pass through the surface, they will preferentially occupy these positions as hydrogen traps. At the same time, these positions will also become channels for hydrogen atoms to pass through quickly. After adding TiO 2 , the composite coating forms a Cr 2 O 3 / TiO 2 interface. The embedding energy of H atoms in the O interstitial sites is positive, and the diffusion of H atoms at the Cr 2 O 3 / TiO 2 interface requires heat absorption, which is energetically unfavorable for H diffusion. This indicates that the formation of the Cr 2 O 3 / TiO 2 interface effectively blocks the diffusion of H. Description of the Drawings

[0022] Figure 1 is a schematic diagram of the hydrogen permeation device;

[0023] Figure 2 is an XRD pattern; Figure 2 (a) is the Cr 2 O 3 coating; Figure 2(b) is Cr 2 O 3 -10% TiO 2 XRD pattern of the composite coating;

[0024] Figure 3 SEM image of the surface morphology of the coating; Figure 3 (a) is Cr 2 O 3 SEM image of the surface morphology of the coating; Figure 3 (b) is Cr 2 O 3 SEM image of the surface morphology of the coating; Figure 3 (c) is Cr 2 O 3 -10% TiO 2 SEM image of the surface morphology of the composite coating; Figure 3 (d) is Cr 2 O 3 -10% TiO 2 SEM image of the surface morphology of the composite coating;

[0025] Figure 4 SEM image of the cross-section of the coating; Figure 4 (a) is Cr 2 O 3 SEM image of the cross-section of the coating; Figure 4 (a) is Cr 2 O 3 SEM image of the cross-section of the coating; Figure 4 (c) is Cr 2 O 3 -10% TiO 2 SEM image of the cross-section of the composite coating; Figure 4 (d) is Cr 2 O 3 -10% TiO 2 SEM image of the cross-section of the composite coating;

[0026] Figure 5 is Cr 2 O 3 coating and Cr 2 O 3 -10% TiO 2 Vickers hardness of the composite coating;

[0027] Figure 6 Electrochemical hydrogen permeation curve of the coating; Figure 6 (a) is Cr 2 O 3 Electrochemical hydrogen permeation curve of the coating; Figure 6 (b) is Cr 2O 3 -10% TiO 2 Electrochemical hydrogen permeation curves of the composite coating. Specific embodiments

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention belongs.

[0030] Example 1

[0031] Application of a composite coating formed by titanium oxide and chromium oxide in hydrogen resistance, including the following steps:

[0032] Substrate preparation: Cut X80 pipeline steel into a metal substrate with a size of 30×20×5 mm 3 , and perform pretreatment on the surface of the metal substrate, including grinding, cleaning, and drying; use sandpaper with a mesh size of #400 to #2000 to gradually grind its surface to remove the oxide layer on the substrate surface. Immerse the ground substrate in absolute ethanol and ultrasonicate for 10 min to remove surface oil stains, and dry it in an oven for standby.

[0033] Ceramic layer preparation: Use Cr 2 O 3 -10% TiO 2 composite powder (particle size 15 - 45 μm). Use a plasma spraying device (Metco9MB) for spraying, with a current of 500 A, a scanning speed of 20 mm / s, a powder feeding rate of 14.6 g / min, and a carrier gas flow rate of 4 L / min. The powder is heated to a molten or semi-molten state and, under the drag of the high-speed plasma jet, accelerates and impacts onto the substrate surface and deposits to form a coating.

[0034] Example 2

[0035] Application of a composite coating formed by titanium oxide and chromium oxide in hydrogen resistance, including the following steps:

[0036] Substrate preparation: Cut X80 pipeline steel into the required substrate size, which is 30×20×5 mm 3 , and perform pretreatment on the surface of the metal substrate, including grinding, cleaning, and drying; use sandpaper with a mesh size of #400 to #2000 to gradually grind its surface to remove the oxide layer on the substrate surface. Immerse the ground substrate in absolute ethanol and ultrasonicate for 10 min to remove surface oil stains, and dry it in an oven for standby.

[0037] Ceramic layer preparation: Use Cr 2 O 3Powder, (particle size 15 - 45 μm). Spraying was carried out using a plasma spraying equipment (Metco9MB), with a current of 500 A, a scanning speed of 20 mm / s, a powder feeding rate of 14.6 g / min, and a carrier gas flow rate of 4 L / min. The powder was heated to a molten or fused state and, under the drag of the high-speed plasma jet, accelerated to impact the substrate surface and deposit to form a coating.

[0038] Example 3

[0039] Application of a composite coating formed by titanium oxide and chromium oxide in hydrogen resistance, including the following steps:

[0040] Substrate preparation: Cut the X80 pipeline steel into the required substrate size, with the size of 30×20×5 mm 3 , and perform pre-treatment on the surface of the metal substrate, including grinding, cleaning, and drying; use sandpaper with #400 to #2000 meshes to gradually grind its surface to remove the oxide layer on the substrate surface. Immerse the ground substrate in absolute ethanol and ultrasonicate for 10 min to remove surface oil stains, and dry it in an oven for standby.

[0041] Ceramic layer preparation: Use Cr 2 O 3 -8% TiO 2 Composite powder, (particle size 15 - 45 μm). Spraying was carried out using a plasma spraying equipment (Metco9MB), with a current of 500 A, a scanning speed of 20 mm / s, a powder feeding rate of 14.6 g / min, and a carrier gas flow rate of 4 L / min. The powder was heated to a molten or fused state and, under the drag of the high-speed plasma jet, accelerated to impact the substrate surface and deposit to form a coating.

[0042] II. Performance experimental analysis

[0043] 2.1 Microstructure and composition analysis

[0044] Before the experiment, use a wire cutting machine to precisely cut the sample into a size of 10×10×5 mm 3 for microstructure analysis and performance evaluation. Subsequently, perform a grinding process on the coating surface, successively use sandpaper with #400 to #2000 meshes for grinding, and finally perform diamond spray polishing (particle size 2.5 microns). After polishing, thoroughly clean the sample with alcohol to ensure that its surface has no impurities, and then dry it with hot air. Observe the surface and cross-section microstructures of the coating through a field emission scanning electron microscope (FE-SEM).

[0045] Use X-ray diffraction (XRD, D / MAX2500PC) to comprehensively characterize the structure of the sample, using Cu target K αX-ray source. The test conditions were a scanning speed of 1° / min, a diffraction angle range of 5° to 90°, and an operating voltage of 40 kV.

[0046] 2.2 Coating hardness

[0047] The microhardness of the coating was measured using a Vickers hardness tester (HVS-1000Z). The test loads and loading times were 300 g and 10 s, respectively. First, the specimen to be tested was polished. During the test, measurements were taken successively in multiple positions of the coating along the thickness direction, and the average value of the test results was taken.

[0048] 2.3 Hydrogen barrier performance

[0049] After degreasing and cleaning the specimen, nickel plating was carried out on the hydrogen-evolving side of the specimen in a nickel plating solution. The current density was 5 mA / cm 2 , and the time was 5.5 min. The composition of the nickel plating solution: 250 g / L nickel sulfate + 45 g / L nickel chloride + 40 g / L boron + 0.2 g / L sodium dodecyl sulfate, pH = 3. The electrolyte on the hydrogen charging side and the hydrogen-evolving side: 0.1 mol / L NaOH solution. A Devanathan-Stachurski double electrolytic cell was used for the hydrogen permeation test. The specimen was clamped between the two electrolytic cells. The anode cell was the detection cell, and the cathode cell was the hydrogen charging cell, as Figure 1 shown. A Gamry electrochemical workstation was used to apply polarization to the specimen and collect the hydrogen permeation current density, and a constant current source was used to charge hydrogen to the specimen. The hydrogen charging current density was 1 mA / cm 2 , and the potential on the hydrogen-evolving side was 300 mV. Before hydrogen charging, a constant potential anodic polarization was carried out on the hydrogen-evolving side. When the current density dropped to below 0.5 μA / cm 2 and stabilized, the hydrogen charging solution was poured in to start the test. Once the hydrogen permeation current density reached a stable state, the test was stopped.

[0050] III. Results and discussion

[0051] 3.1 Phase and morphology analysis

[0052] Figure 2 (a) and (b) respectively show the XRD patterns of the Cr 2 O 3 coating and the Cr 2 O 3 -10% TiO 2 composite coating, as well as the PDF (Powder Diffraction File, PDF) standard cards for comparison. The results show that due to Cr 2 O 3The properties of the material, whose crystal has a high melting point and stability. The diffraction peaks of the coating correspond to those of the PDF standard card, and no new diffraction peaks appear, indicating that the phase composition in the coating is consistent with the expectation. From Figure 2 (b), it can be seen that Cr 2 O 3 -10% TiO 2 The main phases of the composite coating are Cr 2 O 3 and TiO 2 . No diffraction peaks of other phases are found, and no large-range shifts occur in each diffraction peak, which further indicates that no obvious phase transformation and lattice expansion or contraction occur during the preparation of the material. Therefore, it can be inferred that Cr 2 O 3 and TiO 2 in the coating exist in the form of physical mixture rather than generating new compounds through chemical reaction, indicating the stable structure of the coating.

[0053] Figure 3 Shown are the surface morphologies of the Cr 2 O 3 coating Figure 3 (a) and (b), and the Cr 2 O 3 -10% TiO 2 composite coating Figure 3 (c) and (d) at different magnifications. It can be seen that the surfaces of both coatings are uneven, presenting a complex lamellar stacking structure. There are cracks and pores on the coating surface, and it is composed of completely molten regions and partially melted particles, which are the significant characteristics of the plasma spraying technology. The boundary lines of the particles are clearly visible, and micropores are distributed along these boundary lines. This is caused by the high heat and kinetic energy of the particles during the preparation process. When the molten particles bombard the substrate, rapid cooling occurs before the molten particles are completely melted, resulting in volume contraction of the particles, and then micropores and obvious edges appear. From Figure 3 (c) and (d), it can be observed that the addition of TiO 2 does not significantly change the overall surface morphology of the coating, which is still mainly in the lamellar structure. However, the addition of TiO 2 effectively improves the bonding force between the lamellar structures, making the completely molten region more extensive and the surface smoother compared to the single Cr 2 O 3 coating.

[0054] Figure 4 Shows the Cr 2 O 3 coating at different magnifications ( Figure 4 (a) and (b)) and Cr2 O 3 -10% TiO 2 Cross-sectional SEM images of the composite coatings ( Figure 4 (c) and (d)). The main purpose of analyzing these images is to accurately measure the thickness of the coatings and detect possible structural defects. Observe Cr 2 O 3 coating ( Figure 4 (b)), it can be found that there are many large pores inside. However, when adding 10 wt% of TiO 2 , the microstructure of the composite coating shows a more uniform distribution. Specifically, the number of large pores significantly decreases, and the coating exhibits the smallest average thickness (as shown in Figure 4 (c) and (d)). This reduction in thickness is attributed to the unique properties of TiO 2 powder during the coating preparation process. Compared with Cr 2 O 3 (melting point is 2435 °C), TiO 2 has finer particle size and lower melting point (1840 °C). These properties promote a more uniform deposition process, making the coating structure denser and more compact, thereby reducing the overall thickness of the coating.

[0055] 3.2 Microhardness

[0056] Figure 5 shows the distribution of cross-sectional microhardness of two groups of specimens. The results show that the cross-sectional microhardness of the coating gradually decreases, showing a stepped distribution, and only stabilizes when reaching the substrate hardness (243 HV). The hardness of the clad layer is the largest on the cross-section, followed by the heat-affected zone, and the hardness of the substrate not affected by heat is the smallest. The average hardness value of the Cr 2 O 3 coating is 603 HV, and the average hardness value of the Cr 2 O 3 -10% TiO 2 composite coating is 527 HV. The hardness of the composite coating formed after adding TiO 2 decreases. Bolelli et al. conducted a systematic study on Cr 2 O 3 and its composite coatings and found that compared with pure Cr 2 O 3 , the Cr 2 O 3 –25% TiO 2 coating has lower hardness but greater toughness, showing better wear resistance.

[0057] 3.3 Hydrogen permeation curve

[0058] Figure 6Depicts Cr 2 O 3 coating ([[]] Figure 6 (a)) and Cr 2 O 3 -10% TiO 2 composite coating ([[]] Figure 6 (b)) in the graph of current density varying with time. Given that the samples adopt a composite material structure combining metal and coating, calculating the diffusion coefficient of the coating becomes extremely complex and challenging, and there is currently no generally applicable method. Therefore, this article only focuses on the comparison of hydrogen permeation rates under steady state, specifically measured by the magnitude of the steady-state permeation current. It can be observed from the graph that after evolution over different time periods, the current values of each sample can reach a stable state, and there are significant differences among the maximum values of these steady-state currents. It should be noted that the time points when hydrogen permeation current is first detected for each specimen are not consistent. Specifically, the Cr 2 O 3 coating detected hydrogen permeation current within a relatively short time (t = 1023 s), and its steady-state current density reached 0.81 μA / cm2. In contrast, the Cr 2 O 3 -10% TiO 2 composite coating detected hydrogen permeation current after a longer time (t = 2405 s), and its steady-state current density was 0.44 μA / cm2. This result indicates that the doping of TiO 2 not only prolongs the time for hydrogen atoms to penetrate the specimen but also reduces the steady-state current density.

[0059] Thus, it can be seen that the addition of TiO 2 affects the coating performance mainly in two aspects: First, it reduces the porosity of the coating, making the coating structure more dense, thus slowing down the diffusion rate of hydrogen atoms; Second, the introduction of TiO 2 increases new interfaces (i.e., the Cr 2 O 3 / TiO 2 interface), and these interfaces have the ability to capture hydrogen atoms, forming so-called "hydrogen traps". These hydrogen traps enhance the binding effect of the coating on hydrogen atoms and further inhibit the hydrogen diffusion process.

[0060] Two hydrogen-blocking coatings Cr 2 O 3 and Cr 2 O 3 -10% TiO 2 were prepared using a plasma spraying device. A comprehensive study was conducted on the Cr 2 O 3 coating and Cr 2 O 3-10% TiO 2 Synergistic effects of the microstructure, mechanical properties, and hydrogen barrier mechanism of the coating.

[0061] Therefore, the application of the composite coating formed by the above titanium oxide and chromium oxide in hydrogen barrier reduces the hydrogen permeation current, thereby enhancing the hydrogen barrier performance of the coating.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. Application of a composite coating formed of titanium oxide and chromium oxide in hydrogen barrier, characterized in that: The following steps are involved: Matrix preparation: Cut the sample into metal matrix, and pre-treat the surface of the metal matrix by grinding, cleaning and drying; Preparation of ceramic layer: Cr2O3 and TiO2 composite powder is used. The composite powder is heated to a molten or melted state. Under the traction of the plasma high-speed flame flow, it is accelerated to collide with the substrate surface and deposited to form a ceramic coating.

2. The use of a composite coating formed of titanium oxide and chromium oxide in hydrogen barrier according to claim 1, characterized in that: The working parameters of plasma spraying are: Current 450-500A, scanning speed 18-20mm / s, powder feeding rate 13-14.6g / min, carrier gas flow rate 3.5-4L / min.

3. The use of a composite coating formed of titanium oxide and chromium oxide in hydrogen barrier according to claim 1, characterized in that: The particle size of the composite powder is 15 to 45 μm.

4. The use of a composite coating formed of titanium oxide and chromium oxide in hydrogen barrier according to claim 1, characterized in that: Metal substrates include pipeline steel and stainless steel.

5. The use of a composite coating formed of titanium oxide and chromium oxide in hydrogen barrier according to claim 1, characterized in that: In the composite powder, the mass ratio of Cr2O3:TiO2 is 1:0.08-0.

1.

6. The use of a composite coating formed of titanium oxide and chromium oxide in hydrogen barrier according to claim 1, characterized in that: The thickness of the ceramic coating is 100-300 μm.

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