A stainless steel surface Al2O3 / Ti self-absorbing composite hydrogen barrier coating and a preparation method thereof

Abstract

The application discloses a stainless steel surface Al2O3 / Ti self-absorption composite hydrogen barrier coating and a preparation method thereof, wherein the stainless steel surface Al2O3 / Ti self-absorption composite hydrogen barrier coating comprises a TiC alloy outer coating, a Ti / Al alloy intermediate coating and an Al2O3 inner coating; the TiC alloy outer coating is composed of nano-level conical TiC grains, the Ti / Al alloy intermediate coating is composed of a Ti / Al solid melt, and the Al2O3 inner coating is composed of an oxidized ceramic. The composite hydrogen barrier coating can improve the PRF size of the existing Al2O3 hydrogen barrier coating, and the sol-gel method combined with the preparation method of the magnetron sputtering and the chemical vapor deposition can solve the problems of the existing Al2O3 hydrogen barrier coating, such as difficult preparation and poor service performance.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen barrier coating technology for hydrogen-related systems, specifically relating to an Al2O3 / Ti self-absorbing composite hydrogen barrier coating on a stainless steel surface and its preparation method. Background Technology

[0002] Currently, hydrogen is widely used in strategic emerging industries such as new materials, new energy, fuel cells, automobiles, energy storage, shipbuilding, nuclear energy, aerospace, and petrochemicals. New materials for hydrogen-environment environments will be a key focus of research and development. Stainless steel is currently the main structural material for hydrogen-environment systems; however, stainless steel has a relatively high hydrogen permeation or leakage rate. Developing highly efficient hydrogen-barrier coatings to reduce hydrogen isotope permeation is of great significance for the production, storage, transportation, and safe utilization of hydrogen. Achieving breakthroughs in key hydrogen-related new material technologies and improving the safety and reliability of hydrogen isotope systems and equipment is expected to reduce the costs of hydrogen storage, transportation, and hydrogen energy applications. Furthermore, fusion energy is considered one of the clean energy sources capable of large-scale development and utilization, and is an ideal energy source with the potential to solve future energy crises. Tritium is one of the main fuels in fusion reactors, and stainless steel is an important structural material in the nuclear industry, often used to manufacture deuterium and tritium storage containers, transport pipelines, tritium operating systems, equipment, and pipelines. Tritium is an isotope of hydrogen, but it can rapidly permeate most metallic materials, causing hydrogen embrittlement / helium embrittlement problems in structural materials. Furthermore, tritium permeation can lead to the loss of tritium fuel, potentially making the fusion reaction unsustainable. Therefore, tritium permeation control and tritium inhibition are among the key technologies for the engineering and commercialization of fusion reactors.

[0003] Currently, one of the most effective methods to prevent hydrogen permeation is to prepare hydrogen-barrier coatings on the surface of structural materials. Common hydrogen-barrier coatings are mainly divided into three categories: oxide coatings, non-oxide coatings, and composite coatings. Among them, Al2O3, with its excellent comprehensive properties such as high melting point, chemical stability, low hydrogen solubility, and low permeability, is considered a typical candidate material for hydrogen-barrier coatings. However, some laboratories have observed a hydrogen permeation resistance factor (PRF) of 10. 3 -10 4 The coatings exhibit significantly reduced performance in high-temperature environments or reactor irradiation environments, with some even dropping to 3, indicating that hydrogen permeation cannot be reduced simply by blocking hydrogen.

[0004] Commonly used methods for preparing Al2O3 hydrogen barrier coatings include physical / chemical vapor deposition, plasma spraying, plasma electrolytic oxidation, embedding aluminizing, hot-dip aluminizing, slurry methods, sol-gel methods, micro-arc oxidation, and organometallic decomposition. However, Al2O3 coatings not only face significant challenges in preparation but are also prone to peeling and damage under harsh in-reasonable conditions such as high temperatures and irradiation, compromising their integrity and effectiveness, thus drastically reducing their hydrogen barrier efficiency. Therefore, there is an urgent need in this field to develop a hydrogen barrier coating that exhibits high uniformity and density, good service performance, excellent hydrogen barrier properties, and a simple and cost-effective preparation process. Summary of the Invention

[0005] To address the shortcomings of the existing technologies, this invention provides an Al2O3 / Ti self-absorbing composite hydrogen barrier coating for stainless steel surfaces and its preparation method. The composite hydrogen barrier coating of this invention can improve the PRF (Potentially Reducing Fiber) of existing Al2O3 hydrogen barrier coatings. Furthermore, the sol-gel method combined with magnetron sputtering and chemical vapor deposition proposed in this invention can solve the problems of difficult preparation and poor service performance of existing Al2O3 hydrogen barrier coatings.

[0006] This invention relates to an Al2O3 / Ti self-absorbing composite hydrogen-barrier coating for stainless steel surfaces, comprising a TiC alloy outer coating, a Ti / Al alloy intermediate coating, and an Al2O3 inner coating. The TiC alloy outer coating is composed of nanoscale conical TiC grains, the Ti / Al alloy intermediate coating is composed of a Ti / Al solid solution, and the Al2O3 inner coating is composed of oxide ceramics.

[0007] Furthermore, the cone-shaped TiC grains have a particle size of 50nm-200nm, the outer coating of the TiC alloy has a thickness of 1μm-2μm, the intermediate coating of the Ti / Al alloy has a thickness of 500nm-1μm, the grain size in the intermediate coating of the Ti / Al alloy has a size of 100nm-150nm, the inner coating of the Al2O3 has a thickness of 800nm-2μm, and the composite hydrogen barrier coating has a thickness of 2μm-5μm.

[0008] Furthermore, in the Ti / Al alloy intermediate coating, the atomic ratio of Ti to Al is 1-3:1.

[0009] The method for preparing the Al2O3 / Ti self-absorbing composite hydrogen barrier coating on the stainless steel surface of the present invention includes the following steps:

[0010] Step 1: Use stainless steel as a substrate and perform surface pretreatment on it;

[0011] Step 2: An Al2O3 coating is prepared on the stainless steel substrate after the pretreatment in Step 1 by the sol-gel method, and an Al2O3 inner coating is formed after heat treatment;

[0012] Step 3: Prepare a Ti / Al alloy intermediate coating by sputtering a titanium source onto the Al2O3 inner coating obtained in Step 2 using magnetron sputtering.

[0013] Step 4: In an inert atmosphere, carbon source is deposited on the surface of the Ti / Al alloy intermediate coating by chemical vapor deposition to obtain the nano-TiC alloy outer coating, thus obtaining the composite hydrogen barrier coating.

[0014] In step 1, the stainless steel substrate is first polished with 600-2000 grit sandpaper to achieve a surface roughness of 0.04-0.15. Then, it is ultrasonically cleaned with acetone and alcohol.

[0015] In step 2, Al2O3 sol-gel solution is prepared by reacting Al(NO3)3 with ammonia. The stainless steel substrate coated with Al2O3 sol-gel solution is then heat-treated in an inert atmosphere to form an Al2O3 inner coating on the substrate surface.

[0016] Furthermore, the concentration of Al(NO3)3 solution is 0.5mol / L-1mol / L, and the concentration of ammonia water is 0.5mol / L-1mol / L.

[0017] Furthermore, the heat treatment temperature is 600℃-800℃; the thickness of the Al2O3 inner coating is 800nm-2μm.

[0018] In step 3, during magnetron sputtering, the vacuum pressure is less than 1.0 × 10⁻⁶. -4 Pa, sputtering power of 150W-300W, sputtering deposition time of 25min-75min, inert argon gas is introduced during sputtering, argon gas pressure of 1Pa-2Pa, argon gas flow rate of 40sccm-100sccm.

[0019] In step 3, the titanium source is either a titanium target or titanium powder.

[0020] In step 4, the substrate is preheated to 800℃-1000℃ at a heating rate of 5℃ / min-10℃ / min, and the chemical vapor deposition time is 100min-500min.

[0021] Furthermore, the carbon source is one of methane, ethane, propane, acetylene, propylene, butene, isobutene, benzene, and toluene, and the carbon source flow rate is controlled at 500 sccm-800 sccm.

[0022] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0023] This invention composites a hydrogen-absorbing material, Ti, onto an Al2O3 coating. Through a self-absorption mechanism, it forms metal hydrides that adsorb hydrogen, thus blocking hydrogen permeation. Subsequently, heating the TiH2 metal hydrides desorbs the hydrogen, releasing it. This organic combination of hydrogen blocking and absorption significantly reduces hydrogen permeation, increasing the PRF value to 10. 3 -10 4 .

[0024] The hydrogen-barrier composite coating of the present invention is prepared on a metal substrate by magnetron sputtering to form a Ti / Al alloy coating, which forms solid solution alloys TiAl and Ti3Al with Al, which is beneficial to improving the adhesion of the coating.

[0025] The nano-TiC coating prepared by chemical vapor deposition in this invention can effectively control the coating structure and grain size, enhance the film-substrate adhesion, coating density and reduce defects, and improve the hydrogen barrier performance of the composite coating.

[0026] This invention discloses a method for preparing an Al2O3 / Ti self-absorbing composite tritium-blocking coating on a stainless steel substrate. The method is simple to operate and has low preparation cost. The prepared Al2O3 / Ti composite coating is more uniform and dense, which can effectively improve the hydrogen barrier performance and service performance of the coating. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the Al2O3 / Ti self-absorbing composite hydrogen barrier coating on the surface of stainless steel components in a hydrogen-related system.

[0028] Figure 2 This is a SEM image of the Al2O3 coating surface. Detailed Implementation

[0029] Example 1:

[0030] In this embodiment, the Al2O3 / Ti self-absorbing composite hydrogen barrier coating on the stainless steel surface is applied to SS316L steel, and the preparation steps are as follows:

[0031] 1. Polish the surface of the SS316L steel substrate with dimensions of 50mm×50mm×3.5mm to a surface roughness of 0.04-0.15. Then, ultrasonically clean the substrate with alcohol and finally dry it in a 100℃ oven for 2.5 hours.

[0032] 2. First, an Al2O3 sol-gel solution was prepared by reacting Al(NO3)3 with ammonia water. The concentration of the Al(NO3)3 solution was 0.8 mol / L, and the concentration of the ammonia water was 0.8 mol / L. An Al2O3 coating was then prepared on a stainless steel substrate using the sol-gel method. The substrate coated with the Al2O3 sol-gel solution was then heat-treated at 700℃ for 1.5 hours to form an inner Al2O3 coating with a thickness of 1.2 μm.

[0033] 3. Then, on the Al2O3 coating, a titanium source is sputtered by magnetron sputtering. The titanium source is either a titanium target or titanium powder to prepare a Ti / Al alloy intermediate coating. The thickness of the intermediate coating is 800 nm, the ratio of Ti to Al is 1:1, and the grain size of the AlTi intermediate coating is 150 nm. It has a good grain gap filling function and increases the adhesion between the inner and outer coatings.

[0034] 4. Finally, under inert gas, carbon source is deposited on the surface of Ti / Al alloy intermediate coating by chemical vapor deposition to obtain nano-TiC outer coating with a thickness of 1.5 μm, forming hydrogen-barrier composite coating with a thickness of 4 μm.

[0035] 5. Conduct hydrogen permeation testing. First, use a leak detector to check for leaks in the high-temperature gas phase deuterium permeation device; then, evacuate to ensure the low-pressure chamber has a vacuum level of 10. -5 The stainless steel sample with the composite hydrogen barrier coating was degassed for 6 hours. The sample was then heated to 300℃ using electric heating and kept at a constant temperature before being filled with high-purity deuterium gas. Finally, the deuterium permeability at different times was detected by quadrupole mass spectrometry (QMS), and the PRF value and high-temperature performance of the composite hydrogen barrier coating at different temperatures were obtained. The maximum PRF value was approximately 8 × 10⁻⁶. 3 The composite coating is dense and uniform, and there is no peeling at a high temperature of 1000℃.

[0036] Example 2:

[0037] In this embodiment, the Al2O3 / Ti self-absorbing composite hydrogen barrier coating on the stainless steel surface is applied to CLF-1 steel, and the preparation steps are as follows:

[0038] 1. The size is The CLF-1 steel substrate is ground and polished to a surface roughness of 0.04-0.15. Then, the substrate is ultrasonically cleaned with alcohol and finally dried in a 100℃ oven for 3 hours.

[0039] 2. First, an Al2O3 sol-gel solution was prepared by reacting Al(NO3)3 with ammonia water. The concentration of the Al(NO3)3 solution was 1 mol / L, and the concentration of the ammonia water was 1 mol / L. An Al2O3 coating was then prepared on a stainless steel substrate using the sol-gel method. The substrate coated with the Al2O3 sol-gel solution was then heat-treated at 800℃ for 2 hours to form an inner Al2O3 coating with a thickness of 2 μm.

[0040] 3. Then, on the Al2O3 coating, a titanium source is sputtered by magnetron sputtering. The titanium source is either a titanium target or titanium powder to prepare a Ti / Al alloy intermediate coating. The thickness of the intermediate coating is 1 μm, the ratio of Ti to Al is 3:1, and the grain size of the AlTi3 intermediate coating is 100 nm. It has a good grain gap filling function and increases the adhesion between the inner and outer coatings.

[0041] 4. Finally, under inert gas, carbon source is deposited on the surface of Ti / Al alloy intermediate coating by chemical vapor deposition to obtain nano-TiC outer coating with a thickness of 2μm, forming hydrogen barrier composite coating with a thickness of 5μm.

[0042] 5. Conduct hydrogen permeation testing. First, use a leak detector to check for leaks in the high-temperature gas phase deuterium permeation device; then, evacuate to ensure the low-pressure chamber has a vacuum level of 10. -6 The stainless steel sample with the composite hydrogen barrier coating was degassed for 6 hours. The sample was then heated to 300℃ using electric heating and kept at a constant temperature before being filled with high-purity deuterium gas. Finally, the deuterium permeability at different times was detected by quadrupole mass spectrometry (QMS), and the PRF value and high-temperature performance of the composite hydrogen barrier coating at different temperatures were obtained. The maximum PRF value was approximately 5 × 10⁻⁶. 3 The composite coating is dense and uniform, and there is no peeling at a high temperature of 1000℃.

[0043] Example 3:

[0044] In this embodiment, the Al2O3 / Ti self-absorbing composite hydrogen barrier coating on the stainless steel surface is applied to ODS steel, and the preparation steps are as follows:

[0045] 1. The size is The ODS steel substrate is ground and polished to a surface roughness of 0.04-0.15. Then, the substrate is ultrasonically cleaned with alcohol and finally dried in an oven at 100℃ for 2 hours.

[0046] 2. First, an Al2O3 sol-gel solution was prepared by reacting Al(NO3)3 with ammonia water. The concentration of both the Al(NO3)3 solution and the ammonia water was 0.5 mol / L. An Al2O3 coating was then prepared on a stainless steel substrate using the sol-gel method. The substrate coated with the Al2O3 sol-gel solution was then heat-treated at 600℃ for 1 hour to form an inner Al2O3 coating with a thickness of 800 nm.

[0047] 3. Then, on the Al2O3 coating, a titanium source is sputtered by magnetron sputtering. The titanium source is either a titanium target or titanium powder to prepare a Ti / Al alloy intermediate coating. The thickness of the intermediate coating is 500 nm, the ratio of Ti to Al is 1:1, and the grain size of the AlTi intermediate coating is 150 nm. It has a good grain gap filling function and increases the adhesion between the inner and outer coatings.

[0048] 4. Finally, under inert gas, carbon source is deposited on the surface of Ti / Al alloy intermediate coating by chemical vapor deposition to obtain nano-TiC outer coating with a thickness of 1μm, forming a hydrogen-barrier composite coating with a thickness of 3μm.

[0049] 5. Conduct hydrogen permeation testing. First, use a leak detector to check for leaks in the high-temperature gas phase deuterium permeation device; then, evacuate to ensure the low-pressure chamber vacuum level is 5 × 10⁻⁶. -5 The stainless steel sample with the composite hydrogen barrier coating was degassed for 6 hours. The sample was then heated to 300℃ using electric heating and kept at a constant temperature before being filled with high-purity deuterium gas. Finally, the deuterium permeability at different times was detected by quadrupole mass spectrometry (QMS), and the PRF value and high-temperature performance of the composite hydrogen barrier coating at different temperatures were obtained. The maximum PRF value was approximately 1×10⁻⁶. 4 The composite coating is dense and uniform, and there is no peeling at a high temperature of 1000℃.

[0050] Comparison of Examples 1-3:

[0051] The grain morphology, grain size, and hydrogen barrier properties of the coatings prepared in Examples 1-3 were compared. The substrates used in Examples 1-3 were different, resulting in varying hydrogen barrier capabilities; ODS steel exhibited the weakest hydrogen permeation capacity. In Example 2, the Ti:Al ratio was 3:1, resulting in the smallest grain size and the weakest hydrogen barrier capability. Therefore, the PRF value prepared in Example 2 was the smallest, thus increasing the thickness of the Al2O3 inner coating in these examples.

[0052] Example 4:

[0053] The method is the same as in Example 1, except that in step 3, the thickness of the outer coating is 1 μm.

[0054] The results show that the TiC outer coating exhibits a nanoscale conical TiC grain structure with a size of 100 nm, demonstrating good hydrogen self-absorption properties; the AlTi intermediate coating has a grain size of 150 nm, providing good intergranular filling and increasing the adhesion between the inner and outer coatings; the maximum PRF value is approximately 6 × 10⁻⁶. 3 The composite coating is dense and uniform, and there is no peeling or flaking even at a high temperature of 1000℃.

[0055] Example 5:

[0056] The method is the same as in Example 1, except that in step 3, the thickness of the outer coating is 1.2 μm.

[0057] The results show that the TiC outer coating exhibits a nanoscale conical TiC grain structure with a size of 100 nm, demonstrating good hydrogen self-absorption properties; the AlTi intermediate coating has a grain size of 150 nm, providing good intergranular filling and increasing the adhesion between the inner and outer coatings; the maximum PRF value is approximately 7 × 10⁻⁶. 3 The composite coating is dense and uniform, and there is no peeling or flaking even at a high temperature of 1000℃.

[0058] Example 6:

[0059] The method is the same as in Example 1, except that in step 3, the thickness of the outer coating is 2 μm.

[0060] The results show that the TiC outer coating exhibits a nanoscale conical TiC grain structure with a size of 100 nm, demonstrating good hydrogen self-absorption properties; the AlTi intermediate coating has a grain size of 150 nm, providing good intergranular filling and increasing the adhesion between the inner and outer coatings; the maximum PRF value is approximately 1 × 10⁻⁶. 4 The composite coating is dense and uniform, and there is no peeling or flaking even at a high temperature of 1000℃.

[0061] Comparison of Examples 4-6:

[0062] The grain morphology, grain size and hydrogen barrier performance of the coatings prepared in Examples 4-6 were compared. The TiC outer coating in Example 6 was the thickest and had the strongest hydrogen adsorption capacity. Therefore, the PRF value of the coating prepared in Example 6 was the largest.

Claims

1. A self-absorbing composite hydrogen-barrier coating of Al2O3 / Ti on a stainless steel surface, characterized in that: The Al2O3 / Ti self-absorbing composite hydrogen barrier coating on the stainless steel surface includes a TiC alloy outer coating, a Ti / Al alloy intermediate coating, and an Al2O3 inner coating; the TiC alloy outer coating is composed of nanoscale conical TiC grains, the Ti / Al alloy intermediate coating is composed of Ti / Al solid solution, and the Al2O3 inner coating is composed of oxide ceramic. The conical TiC grains have a diameter of 50 nm-200 nm; the outer TiC alloy coating has a thickness of 1 μm-2 μm; the Ti / Al alloy intermediate coating has a thickness of 500 nm-1 μm, and the grain size in the Ti / Al alloy intermediate coating is 100 nm-150 nm; the inner Al2O3 coating has a thickness of 800 nm-2 μm; and the composite hydrogen barrier coating has a thickness of 2 μm-5 μm. In the Ti / Al alloy intermediate coating, the atomic ratio of Ti to Al is 1-3:

1.

2. The method for preparing the Al2O3 / Ti self-absorbing composite hydrogen barrier coating on the stainless steel surface as described in claim 1, characterized in that... Includes the following steps: Step 1: Use stainless steel as a substrate and perform surface pretreatment on it; Step 2: An Al2O3 coating is prepared on the stainless steel substrate after the pretreatment in Step 1 by the sol-gel method, and an Al2O3 inner coating is formed after heat treatment; Step 3: Prepare a Ti / Al alloy intermediate coating by sputtering a titanium source onto the Al2O3 inner coating obtained in Step 2 using magnetron sputtering. Step 4: In an inert atmosphere, carbon source is deposited on the surface of the Ti / Al alloy intermediate coating by chemical vapor deposition to obtain the nano-TiC alloy outer coating, thus obtaining the composite hydrogen barrier coating. In step 2, Al2O3 sol-gel solution is prepared by reacting Al(NO3)3 with ammonia water. The stainless steel substrate coated with Al2O3 sol-gel solution is then heat-treated in an inert atmosphere to form an Al2O3 inner coating on the substrate surface. In step 3, during magnetron sputtering, the vacuum pressure is less than 1.0 × 10⁻⁶. -4 Pa, sputtering power of 150 W-300 W, sputtering deposition time of 25 min-75 min, inert argon gas is introduced during sputtering, argon gas pressure of 1 Pa-2 Pa, argon gas flow rate of 40 sccm-100 sccm; In step 4, the substrate is preheated to 800℃-1000℃ at a heating rate of 5℃ / min-10℃ / min, and the chemical vapor deposition time is 100 min-500 min.

3. The preparation method according to claim 2, characterized in that: The concentration of Al(NO3)3 solution is 0.5 mol / L-1 mol / L, and the concentration of ammonia water is 0.5 mol / L-1 mol / L.

4. The preparation method according to claim 2, characterized in that: The heat treatment temperature is 600 ℃-800 ℃; the thickness of the Al2O3 inner coating is 800 nm-2 μm.

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