Manufacturing process of liquid hydrogen storage tank with carbon-based anti-seepage coating on inner wall

Abstract

The invention discloses a manufacturing process of a liquid hydrogen storage tank with a carbon-based anti-seepage coating on the inner wall. The manufacturing process comprises the following steps that a liquid hydrogen storage tank base body and the carbon-based anti-seepage coating are prepared; wherein the carbon-based anti-seepage coating comprises carbon nanotubes and polymer resin, and the mass fraction of the carbon nanotubes in the carbon-based anti-seepage coating is 30%-50%. And the surface of the inner wall of the liquid hydrogen storage tank base body is coated with the carbon-based anti-seepage coating, the carbon-based anti-seepage coating is cured, and the liquid hydrogen storage tank with the carbon-based anti-seepage coating on the inner wall is obtained. Wherein the thickness of the carbon-based anti-seepage coating is 30 + / -5 [mu] m. The liquid hydrogen storage tank carbon-based anti-seepage coating prepared through the method is high in adhesive force, excellent in anti-seepage performance and high in pressure resistance, and the carbon-based anti-seepage coating is uniform and free of bubbles, cracks and other defects in the preparation process.

Description

Technical Field

[0001] This invention relates to the field of seepage prevention and protection of hydrogen storage cylinders for aviation, and particularly to a manufacturing process for a liquid hydrogen storage tank with a carbon-based seepage prevention coating on the inner wall. Background Technology

[0002] With the rapid development of aerospace technology, hydrogen, as a high-energy-density energy carrier, is increasingly used in spacecraft propulsion systems. To achieve safe and efficient hydrogen storage and transportation, the safety and airtightness of liquid hydrogen storage tanks have become crucial technical requirements. The inner wall coating of liquid hydrogen storage tanks is an important component ensuring their airtightness, pressure resistance, and corrosion resistance. To meet the high safety, reliability, and long-term stability requirements of liquid hydrogen storage tanks in aerospace applications, coating technology is constantly being innovated. Traditional coating materials and processes often face problems such as weak coating adhesion, insufficient pressure resistance, and poor gas permeability, making it difficult to meet the stringent requirements of the aerospace field for liquid hydrogen storage tanks.

[0003] Existing coating technologies for the inner walls of liquid hydrogen storage tanks mainly employ traditional coating materials and processes, such as metal coatings or ordinary polymer coatings. While these provide some protection, most existing coatings suffer from poor adhesion and pressure resistance. Especially in a hydrogen environment, the coatings are prone to peeling, detachment, or cracking, leading to hydrogen leakage or permeation. This severely impacts the safety and airtightness of the liquid hydrogen storage tank. The poor permeability and airtightness of existing coating materials make them unable to effectively prevent hydrogen leakage and permeation. This poses potential safety hazards to liquid hydrogen storage tanks during long-term use. Traditional cleaning and surface treatment processes often fail to completely remove contaminants from the inner walls, resulting in uneven coating adhesion and unstable quality, which in turn affects the overall performance of the liquid hydrogen storage tank. Summary of the Invention

[0004] This invention provides a manufacturing process for a liquid hydrogen storage tank with a carbon-based anti-seepage coating on the inner wall, which can significantly improve the impermeability and airtightness of the carbon-based anti-seepage coating, reducing the hydrogen leakage rate and permeation to extremely low levels.

[0005] The present invention adopts the following technical solutions: This invention provides a manufacturing process for a liquid hydrogen storage tank with a carbon-based anti-seepage coating on its inner wall, comprising the following steps: preparing a liquid hydrogen storage tank substrate and a carbon-based anti-seepage coating. The carbon-based anti-seepage coating comprises carbon nanotubes and a polymer resin, with the carbon nanotubes comprising 30%–50% by mass. The carbon-based anti-seepage coating is then applied to the inner wall surface of the liquid hydrogen storage tank substrate, and the coating is cured to obtain a liquid hydrogen storage tank with a carbon-based anti-seepage coating on its inner wall. The thickness of the carbon-based anti-seepage coating is 30±5 μm.

[0006] Furthermore, during the curing process of the carbon-based waterproof coating, the curing temperature is 150℃ and the curing time is 2 hours.

[0007] Furthermore, during the application of the carbon-based anti-seepage coating, the carbon-based anti-seepage coating is sprayed using a carrier gas containing a gaseous surfactant.

[0008] Furthermore, the carrier gas pressure is maintained at 1-2 bar.

[0009] Furthermore, before applying a carbon-based anti-seepage coating to the inner wall surface of the liquid hydrogen storage tank substrate, the inner wall surface of the liquid hydrogen storage tank substrate is first cleaned, and then the inner wall surface of the liquid hydrogen storage tank substrate is roughened.

[0010] Furthermore, the inner wall surface of the liquid hydrogen storage tank substrate is roughened by plasma spraying.

[0011] Furthermore, the inner wall surface of the liquid hydrogen storage tank substrate is first cleaned by ultrasonic cleaning, and then the inner wall surface of the liquid hydrogen storage tank substrate is cleaned by acidic solution.

[0012] Furthermore, after obtaining a liquid hydrogen storage tank with a carbon-based anti-seepage coating on the inner wall, the thickness of the carbon-based anti-seepage coating, the adhesion of the carbon-based anti-seepage coating, and the airtightness of the liquid hydrogen storage tank are tested.

[0013] Furthermore, during the airtightness test of the liquid hydrogen storage tank, the pressure should be maintained at no less than 100 MPa.

[0014] Furthermore, the thickness of the carbon-based anti-seepage coating on the liquid hydrogen storage tank was measured using ultrasonic testing.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention cleans the inner wall surface of the liquid hydrogen storage tank substrate using ultrasonic cleaning and acidic solution cleaning, thoroughly removing contaminants from the inner wall surface of the liquid hydrogen storage tank substrate, providing a clean adhesion interface for the carbon-based anti-seepage coating, and further ensuring the uniformity and integrity of the carbon-based anti-seepage coating.

[0016] This invention uses plasma spraying to microscopically roughen the inner wall surface of the liquid hydrogen storage tank substrate, significantly enhancing the mechanical anchoring ability between the carbon-based anti-seepage coating and the liquid hydrogen storage tank substrate. This results in excellent coating adhesion and pressure resistance for the liquid hydrogen storage tank, effectively preventing the peeling and detachment of the carbon-based anti-seepage coating under environmental conditions.

[0017] This invention promotes the full cross-linking of polymer molecular chains in the carbon-based anti-seepage coating by making the mass fraction of carbon nanotubes in the carbon-based anti-seepage coating 30%–50% and curing the carbon-based anti-seepage coating at 150°C for 2 hours, forming a dense three-dimensional network structure. This significantly improves the impermeability and airtightness of the carbon-based anti-seepage coating, reducing the hydrogen leakage rate and permeation to extremely low levels.

[0018] This invention ensures that the thickness of the carbon-based anti-seepage coating on liquid hydrogen storage tanks is consistent and defect-free, thereby exhibiting excellent anti-seepage performance and structural stability under hydrogen storage conditions, meeting the high requirements for safety and reliability in aerospace applications. Attached Figure Description

[0019] Figure 1 The results are from performance tests conducted at room temperature on the liquid hydrogen storage tanks prepared in Example 1 and Comparative Examples 1-3. Detailed Implementation

[0020] The technical methods in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] This invention provides a manufacturing process for a liquid hydrogen storage tank with a carbon-based impermeable coating on its inner wall. The aforementioned liquid hydrogen storage tank is used in the aerospace field. The manufacturing process includes the following steps: (1) Prepare the liquid hydrogen storage tank substrate and carbon-based anti-seepage coating. The carbon-based anti-seepage coating contains carbon nanotubes and polymer resin. The mass fraction of carbon nanotubes in the carbon-based anti-seepage coating is 30%–50%, such as 30%, 40%, or 50%. The polymer resin is selected from epoxy resin, phenolic resin, polyurethane resin, and vinyl ester resin.

[0022] In the above steps, the base material of the liquid hydrogen storage tank is high-strength 316L stainless steel. This 316L stainless steel has high resistance to hydrogen embrittlement and, after surface cleaning, grinding, and preliminary processing, possesses good surface adhesion and pressure resistance, meeting the strength requirements of the liquid hydrogen storage tank.

[0023] (2) Clean the inner wall surface of the liquid hydrogen storage tank base, and then roughen the inner wall surface of the liquid hydrogen storage tank base.

[0024] In the above steps, the inner wall surface of the liquid hydrogen storage tank substrate is first cleaned using ultrasonic cleaning, and then cleaned again using an acidic solution to ensure that the inner wall surface of the liquid hydrogen storage tank substrate is free of grease, dust, and oxides. During the ultrasonic cleaning process, the high-frequency vibration waves generated by ultrasound in the cleaning solution are used to remove grease and particulate contaminants adhering to the inner wall surface of the liquid hydrogen storage tank substrate through cavitation. During the ultrasonic cleaning process, the working frequency of the ultrasound and the concentration ratio of the cleaning solution are precisely controlled according to the specific composition of the liquid hydrogen storage tank substrate and the requirements of the carbon-based anti-seepage coating, ensuring that all contaminants are thoroughly removed without causing corrosive damage to the liquid hydrogen storage tank substrate, creating perfect interface conditions for the subsequent application of the carbon-based anti-seepage coating. During the acidic solution cleaning process, a specific concentration of acidic solution is used for chemical cleaning to effectively remove the oxide layer on the inner wall surface of the liquid hydrogen storage tank substrate. The working frequency of the ultrasound can be 800W-6000W, such as 800W, 2000W, 4000W, and 6000W. The acidic solution can be a mixture of nitric acid, hydrofluoric acid, and water, wherein the volume fraction of nitric acid in the mixture is 5%-10%, such as 5%, 8%, and 10%, and the volume fraction of hydrofluoric acid in the mixture is 1%-3%, such as 1%, 2%, and 3%.

[0025] Plasma spraying roughens the inner wall surface of the liquid hydrogen storage tank substrate, microscopically roughening it to improve the adhesion of the carbon-based anti-seepage coating. This plasma spraying process uses high-temperature plasma to propel specific material particles (such as 316L stainless steel particles) at high speed onto the inner wall surface of the liquid hydrogen storage tank substrate, forming a uniformly distributed micron-level uneven structure. This treatment significantly increases the contact area between the carbon-based anti-seepage coating and the liquid hydrogen storage tank substrate, providing a strong mechanical anchoring foundation for the subsequent carbon-based anti-seepage coating, thus fundamentally ensuring the long-term stability of the carbon-based anti-seepage coating.

[0026] (3) Coat the inner wall surface of the liquid hydrogen storage tank substrate with a carbon-based anti-seepage coating.

[0027] In the above steps, during the application of the carbon-based geotextile coating, the coating is sprayed using a carrier gas containing a gaseous active agent. The spraying equipment is an automated spray gun system. The carrier gas can be compressed air, and its pressure is maintained at 1-2 bar. The gaseous active agent can be fatty alcohol polyoxyethylene ether. The volume fraction of the gaseous active agent in the carrier gas is 0.1%–1.0%, such as 0.1%, 0.5%, or 1.0%. During spraying, the automated spray gun system uniformly covers every part of the inner wall surface of the liquid hydrogen storage tank substrate at a preset trajectory and speed, performing a precise spraying operation to ensure the consistency of the carbon-based geotextile coating thickness. Simultaneously, carbon nanotubes form a three-dimensional network structure within the carbon-based geotextile coating, while the gaseous active agent promotes the uniform dispersion and interfacial bonding of the components, ensuring that the carbon-based geotextile coating possesses ideal geotextile resistance and mechanical strength.

[0028] (4) Curing the carbon-based anti-seepage coating to obtain a liquid hydrogen storage tank with a carbon-based anti-seepage coating on the inner wall. The thickness of the carbon-based anti-seepage coating is 30±5μm.

[0029] In the above steps, the curing temperature for the carbon-based geomembrane coating is 150℃, and the curing time is 2 hours to ensure the stability and strength of the coating. This curing is carried out in a dedicated heating furnace. During the curing process, the polymer molecular chains in the carbon-based geomembrane coating undergo a full cross-linking reaction under thermal energy, forming a stable three-dimensional network structure. This molecular-level structural change significantly enhances the sealing performance and impermeability of the carbon-based geomembrane coating, while also improving the chemical bond strength between the coating and the liquid hydrogen storage tank substrate. Precise calculations determined that a curing temperature of 150℃ and a curing time of 2 hours ensure complete cross-linking while avoiding material degradation caused by excessive heat, ultimately forming a dense and stable geomembrane barrier.

[0030] (5) Conduct carbon-based anti-seepage coating thickness test, carbon-based anti-seepage coating adhesion test and air tightness test on liquid hydrogen storage tank.

[0031] In the above steps, ultrasonic testing is used to measure the thickness of the carbon-based anti-seepage coating on the liquid hydrogen storage tank, performing non-destructive testing on the interior of the coating to accurately identify potential defects such as bubbles and cracks. A cross-cut adhesion test is used to assess the adhesion strength between the carbon-based anti-seepage coating and the liquid hydrogen storage tank substrate. During the airtightness test, the pressure is maintained at no less than 100 MPa, and hydrogen leakage is monitored. All airtightness tests are conducted at room temperature. Only liquid hydrogen storage tanks that pass all tests are considered qualified products, ensuring their safe and reliable operation in aerospace hydrogen storage environments.

[0032] The carbon-based anti-seepage coating for liquid hydrogen storage tanks prepared by the method of the present invention has strong adhesion, excellent anti-seepage performance, and high pressure resistance. Moreover, the carbon-based anti-seepage coating is uniform and free from defects such as bubbles and cracks during the preparation process.

[0033] The following detailed description is provided with reference to specific embodiments: Example 1 (1) Prepare the liquid hydrogen storage tank substrate and carbon-based anti-seepage coating. The liquid hydrogen storage tank substrate is made of 316L stainless steel. The carbon-based anti-seepage coating contains carbon nanotubes and polymer resin. The mass fraction of carbon nanotubes in the carbon-based anti-seepage coating is 30%, and the polymer resin is epoxy resin.

[0034] (2) The inner wall surface of the liquid hydrogen storage tank substrate is cleaned by ultrasonic cleaning. The ultrasonic frequency is 800W. Then, the inner wall surface of the liquid hydrogen storage tank substrate is cleaned by an acidic solution. The acidic solution is a mixture of nitric acid, hydrofluoric acid, and water, with the volume fraction of nitric acid in the mixture being 5% and the volume fraction of hydrofluoric acid being 1%. Afterward, the inner wall surface of the liquid hydrogen storage tank substrate is roughened by plasma spraying with 316L stainless steel particles.

[0035] (3) A carbon-based anti-seepage coating is sprayed onto the inner wall surface of the liquid hydrogen storage tank substrate using a carrier gas containing a gaseous active agent. The carrier gas is compressed air. The pressure of the carrier gas is maintained at 1-2 bar. The gaseous active agent is fatty alcohol polyoxyethylene ether. The volume fraction of the gaseous active agent in the carrier gas is 0.1%.

[0036] (4) Curing the carbon-based impermeable coating to obtain a liquid hydrogen storage tank with a carbon-based impermeable coating on the inner wall. The curing temperature is 150℃ and the curing time is 2 hours. The thickness of the carbon-based impermeable coating is 30±5μm.

[0037] (5) The thickness of the carbon-based anti-seepage coating of the liquid hydrogen storage tank is tested by ultrasonic testing, the adhesion of the carbon-based anti-seepage coating of the liquid hydrogen storage tank is tested, and the air tightness of the liquid hydrogen storage tank is tested under the condition of maintaining a pressure of not less than 100 MPa.

[0038] Example 2 (1) Prepare the liquid hydrogen storage tank substrate and carbon-based anti-seepage coating. The liquid hydrogen storage tank substrate is made of 316L stainless steel. The carbon-based anti-seepage coating contains carbon nanotubes and polymer resin. The mass fraction of carbon nanotubes in the carbon-based anti-seepage coating is 40%, and the polymer resin is epoxy resin.

[0039] (2) The inner wall surface of the liquid hydrogen storage tank substrate is cleaned by ultrasonic cleaning. The ultrasonic frequency is 2000W. Then, the inner wall surface of the liquid hydrogen storage tank substrate is cleaned by an acidic solution. The acidic solution is a mixture of nitric acid, hydrofluoric acid, and water, with the volume fraction of nitric acid in the mixture being 8% and the volume fraction of hydrofluoric acid being 2%. Afterward, the inner wall surface of the liquid hydrogen storage tank substrate is roughened by plasma spraying with 316L stainless steel particles.

[0040] (3) A carbon-based anti-seepage coating is sprayed onto the inner wall surface of the liquid hydrogen storage tank substrate using a carrier gas containing a gaseous active agent. The carrier gas is compressed air. The pressure of the carrier gas is maintained at 1-2 bar. The gaseous active agent is fatty alcohol polyoxyethylene ether. The volume fraction of the gaseous active agent in the carrier gas is 0.5%.

[0041] (4) Curing the carbon-based impermeable coating to obtain a liquid hydrogen storage tank with a carbon-based impermeable coating on the inner wall. The curing temperature is 150℃ and the curing time is 2 hours. The thickness of the carbon-based impermeable coating is 30±5μm.

[0042] (5) The thickness of the carbon-based anti-seepage coating of the liquid hydrogen storage tank is tested by ultrasonic testing, the adhesion of the carbon-based anti-seepage coating of the liquid hydrogen storage tank is tested, and the air tightness of the liquid hydrogen storage tank is tested under the condition of maintaining a pressure of not less than 100 MPa.

[0043] Example 3 (1) Prepare the liquid hydrogen storage tank substrate and carbon-based anti-seepage coating. The liquid hydrogen storage tank substrate is made of 316L stainless steel. The carbon-based anti-seepage coating contains carbon nanotubes and polymer resin. The mass fraction of carbon nanotubes in the carbon-based anti-seepage coating is 50%, and the polymer resin is epoxy resin. (2) The inner wall surface of the liquid hydrogen storage tank substrate is cleaned by ultrasonic cleaning. The ultrasonic frequency is 6000W. Then, the inner wall surface of the liquid hydrogen storage tank substrate is cleaned by an acidic solution. The acidic solution is a mixture of nitric acid, hydrofluoric acid, and water, with the volume fraction of nitric acid in the mixture being 10% and the volume fraction of hydrofluoric acid being 3%. Afterward, the inner wall surface of the liquid hydrogen storage tank substrate is roughened by plasma spraying with 316L stainless steel particles.

[0044] (3) A carbon-based anti-seepage coating is sprayed onto the inner wall surface of the liquid hydrogen storage tank substrate using a carrier gas containing a gaseous active agent. The carrier gas is compressed air. The pressure of the carrier gas is maintained at 1-2 bar. The gaseous active agent is fatty alcohol polyoxyethylene ether. The volume fraction of the gaseous active agent in the carrier gas is 1.0%.

[0045] (4) Curing the carbon-based impermeable coating to obtain a liquid hydrogen storage tank with a carbon-based impermeable coating on the inner wall. The curing temperature is 150℃ and the curing time is 2 hours. The thickness of the carbon-based impermeable coating is 30±5μm.

[0046] (5) The thickness of the carbon-based anti-seepage coating of the liquid hydrogen storage tank is tested by ultrasonic testing, the adhesion of the carbon-based anti-seepage coating of the liquid hydrogen storage tank is tested, and the air tightness of the liquid hydrogen storage tank is tested under the condition of maintaining a pressure of not less than 100 MPa.

[0047] Comparative Example 1 The only difference from Example 1 is that in step (2), the inner wall surface of the liquid hydrogen storage tank substrate is roughened by conventional grinding instead of plasma spraying.

[0048] Comparative Example 2 The only difference from Example 1 is that in step (1), the mass fraction of carbon nanotubes in the carbon-based anti-seepage coating is 10%, and the carrier gas does not contain gaseous activators.

[0049] Comparative Example 3 The only difference from Example 1 is that the curing temperature in step (4) is 80°C and the curing time is 1 hour.

[0050] Test case The liquid hydrogen storage tanks prepared in Example 1 and Comparative Examples 1-3 were subjected to the following performance tests at room temperature: Coating adhesion test: The cross-cut test was used to evaluate coating peeling. Air tightness test: Maintain a pressure of 100MPa for 30 minutes and detect the hydrogen leakage rate; Pressure resistance test: Gradually increase the pressure to 150MPa and observe whether the coating cracks or peels off; Permeability test: Hydrogen permeation was detected using a mass spectrometer.

[0051] Test results are as follows Figure 1 As shown: Depend on Figure 1 The test results show that: Example 1 performed best in terms of coating adhesion, airtightness, pressure resistance, and impermeability; compared with Example 1, the adhesion of Comparative Example 1 decreased significantly because the adhesion to the inner wall surface of the liquid hydrogen storage tank substrate was insufficient, making the carbon-based anti-permeability coating easy to peel off; compared with Example 1, the impermeability of Comparative Example 2 deteriorated significantly because the carbon nanotube content in the carbon-based anti-permeability coating was insufficient, resulting in a loose structure that easily produced bubbles and cracks; compared with Example 1, the impermeability of Comparative Example 3 deteriorated because the molecular chain cross-linking of the carbon-based anti-permeability coating was insufficient, making it prone to hydrogen permeation.

[0052] In summary, this invention cleans the inner wall surface of the liquid hydrogen storage tank substrate using ultrasonic cleaning and acidic solution cleaning, thoroughly removing contaminants from the inner wall surface of the liquid hydrogen storage tank substrate, providing a clean adhesion interface for the carbon-based anti-seepage coating, and further ensuring the uniformity and integrity of the carbon-based anti-seepage coating.

[0053] This invention uses plasma spraying to microscopically roughen the inner wall surface of the liquid hydrogen storage tank substrate, significantly enhancing the mechanical anchoring ability between the carbon-based anti-seepage coating and the liquid hydrogen storage tank substrate. This results in excellent coating adhesion and pressure resistance for the liquid hydrogen storage tank, effectively preventing the peeling and detachment of the carbon-based anti-seepage coating under environmental conditions.

[0054] This invention promotes the full cross-linking of polymer molecular chains in the carbon-based anti-seepage coating by making the mass fraction of carbon nanotubes in the carbon-based anti-seepage coating 30%–50% and curing the carbon-based anti-seepage coating at 150°C for 2 hours, forming a dense three-dimensional network structure. This significantly improves the impermeability and airtightness of the carbon-based anti-seepage coating, reducing the hydrogen leakage rate and permeation to extremely low levels.

[0055] This invention ensures that the thickness of the carbon-based anti-seepage coating on liquid hydrogen storage tanks is consistent and defect-free, thereby exhibiting excellent anti-seepage performance and structural stability under hydrogen storage conditions, meeting the high requirements for safety and reliability in aerospace applications.

[0056] 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 the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A manufacturing process for a liquid hydrogen storage tank with a carbon-based anti-seepage coating on its inner wall, characterized in that, Includes the following steps: Prepare a liquid hydrogen storage tank substrate and a carbon-based impermeable coating; wherein the carbon-based impermeable coating comprises carbon nanotubes and polymer resin, and the mass fraction of the carbon nanotubes in the carbon-based impermeable coating is 30%–50%; The carbon-based anti-seepage coating is coated onto the inner wall surface of the liquid hydrogen storage tank substrate, and the carbon-based anti-seepage coating is cured to obtain a liquid hydrogen storage tank with a carbon-based anti-seepage coating on the inner wall; wherein, the thickness of the carbon-based anti-seepage coating is 30±5μm.

2. The manufacturing process as described in claim 1, characterized in that, During the curing process of the carbon-based anti-seepage coating, the curing temperature is 150℃ and the curing time is 2 hours.

3. The manufacturing process as described in claim 1, characterized in that, During the application of the carbon-based anti-seepage coating, the carbon-based anti-seepage coating is sprayed using a carrier gas containing a gaseous surfactant.

4. The manufacturing process as described in claim 3, characterized in that, The pressure of the carrier gas is maintained at 1-2 bar.

5. The manufacturing process as described in claim 1, characterized in that, Before applying the carbon-based anti-seepage coating to the inner wall surface of the liquid hydrogen storage tank substrate, the inner wall surface of the liquid hydrogen storage tank substrate is first cleaned, and then the inner wall surface of the liquid hydrogen storage tank substrate is roughened.

6. The manufacturing process as described in claim 5, characterized in that, The inner wall surface of the liquid hydrogen storage tank substrate is roughened by plasma spraying.

7. The manufacturing process as described in claim 5, characterized in that, First, the inner wall surface of the liquid hydrogen storage tank substrate is cleaned by ultrasonic cleaning, and then the inner wall surface of the liquid hydrogen storage tank substrate is cleaned by acidic solution cleaning.

8. The manufacturing process as described in claim 1, characterized in that, After obtaining a liquid hydrogen storage tank with a carbon-based anti-seepage coating on the inner wall, the thickness of the carbon-based anti-seepage coating, the adhesion of the carbon-based anti-seepage coating, and the airtightness of the liquid hydrogen storage tank are tested.

9. The manufacturing process as described in claim 8, characterized in that, During the airtightness test of the liquid hydrogen storage tank, the pressure is maintained at no less than 100 MPa.

10. The manufacturing process as described in claim 8, characterized in that, The thickness of the carbon-based anti-seepage coating on the liquid hydrogen storage tank was measured using ultrasonic testing.

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