Hydrogen-resistant coating paint and hydrogen conveying pipeline

Abstract

The invention belongs to the technical field of metal corrosion prevention, and particularly relates to improved hydrogen-resistant coating paint and a hydrogen conveying pipeline. The hydrogen-resistant coating is prepared from the following components in parts by mass: 450 to 550 parts of sintered epoxy powder; 8 to 12 parts of few-layer graphene; 12 to 18 parts of a silane coupling agent; 8 to 12 parts of alcohol; 0.5 to 1.5 parts of weak acid; the few-layer graphene is a graphene layered accumulation body formed by five or less layers. According to the preparation method of the coating, a raw material mixture is subjected to high-speed crushing treatment, and the finally obtained coating is in a powder form and can be directly coated on the surface of a finished pipeline in a thermal spraying manner. According to the invention, the component type selection and proportion of the coating are improved, so that the graphene can keep good dispersity in the sintered epoxy powder, the coating product can be suitable for a thermal spraying coating mode, and finally a compact hydrogen-resistant coating is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of metal corrosion protection, and particularly relates to an improved hydrogen barrier coating and a hydrogen transmission pipeline. Background Art

[0002] Pipeline transportation is the primary means of energy transportation. Compared to traditional oil and gas pipelines, the primary cause of failure in hydrogen pipelines is hydrogen embrittlement caused by hydrogen atoms entering the pipeline matrix. To prevent hydrogen atoms from entering the pipeline matrix, various hydrogen pipeline coating materials and preparation methods have been proposed in the prior art. For example, patent CN119286361A proposes a hydrogen barrier coating for stainless steel surfaces and its preparation method. The coating's chemical composition by weight is as follows: 42.2% epoxy resin, 29.5% curing agent, 23.2% diluent, 23.8% MoSe, 0.45% silane-modified graphene, and 0.85% Ti3AlC2. The coating is prepared by preparing a coating mixture according to a certain ratio, applying the mixed solution to the surface of 316L stainless steel, then air-drying it for 12 to 18 hours, drying it in a vacuum drying oven at 50 to 65°C for 24 to 30 hours, and then curing it naturally at room temperature, thereby producing a composite organic hydrogen barrier coating. The drawback of this solution is that the coating requires vacuum drying, significantly limiting the shape and volume of the workpiece. Large-scale equipment cannot use this method to produce hydrogen-blocking coatings. For example, patent CN 119463553 A proposes a hydrogen-permeation-resistant composite coating for hydrogen pipelines and its preparation method. The coating proposed in this patent comprises one or more of silicon carbide powder, silicon carbide fiber, and modified silicon carbide powder, along with an organic resin. The coating is prepared by brushing the coating mixture onto the hydrogen pipeline substrate (steel plate), curing it at room temperature for 24 hours, and then vacuum drying it at 50°C for 4 hours to obtain a stable coating. The coating proposed in this solution also requires vacuum drying, so the treatment target is the hydrogen pipeline substrate, not the finished pipeline. Damage to the coating during pipeline construction is still possible, necessitating post-construction repairs. Summary of the Invention

[0003] In view of this, the present invention hopes to propose a hydrogen barrier coating and preparation method that can be applied to large and medium-sized hydrogen pipelines, so as to solve the problem of harsh coating preparation conditions in the prior art.

[0004] The present invention is achieved through the following technical solutions:

[0005] A hydrogen barrier coating comprises the following preparation steps: high-speed pulverizing a mixture of 450-550 parts by mass of fused epoxy powder, 8-12 parts by mass of few-layer graphene, 12-18 parts by mass of silane coupling agent, 8-12 parts by mass of alcohol, and 0.5-1.5 parts by mass of weak acid; wherein the few-layer graphene is a graphene layered stack formed of 5 or less layers.

[0006] Preferably, the few-layer graphene has 3 to 5 layers.

[0007] Preferably, the silane coupling agent is KH-560.

[0008] Preferably, the weight ratio of the silane coupling agent to the few-layer graphene is 1.2-1.8:1.

[0009] Preferably, the weight ratio of the silane coupling agent to the alcohol is 1.2-1.8:1.

[0010] Preferably, the weight ratio of the fused epoxy powder to the few-layer graphene is 45-55:1.

[0011] Preferably, the dispersant is BYK9076, which can be used for solvent-free wetting of resin systems.

[0012] During hydrogen embrittlement, hydrogen, in the form of hydrogen atoms, penetrates into the metal matrix. A hydrogen atom has a diameter of 0.2 nm, so only materials with gaps smaller than a hydrogen atom can block its passage. Graphene, with an interatomic distance of 0.064 nm, effectively blocks hydrogen atoms. Therefore, incorporating graphene can improve the hydrogen barrier properties of coatings. Conventional graphene-containing coatings typically use a diluent system, due to the inherent properties of graphene. Graphene itself is only compatible with certain highly toxic solvents, such as DMF, and has very poor affinity for most low-toxic solvents, necessitating modification with a silane coupling agent. The dosage of silane coupling agent should be 10-40% of the graphene mass; excessive amounts can lead to self-agglomeration, introducing defects and impurities into the material. Silane coupling agents require hydrolysis to provide reactive groups. Conventional silane coupling agents are typically prepared as 0.5%-2% alcohol solutions, which introduce a large amount of liquid phase into the graphene powder system. If a modified graphene solution is dried before use, it can easily cause graphene aggregation and lose its properties as a sheet of graphene. Therefore, graphene is typically added to a coating system as a dilute modified graphene solution. The resulting coating system is also in liquid form, equivalent to a coating system in which the diluent is the dispersed phase and the graphene and other coating components are the dispersed phase. The liquid coating is applied to the surface to be treated by brushing. After the coating cures, it is vacuum-dried to remove the liquid phase.

[0013] When diluted coatings are applied to hydrogen barrier coatings on pipelines, the space utilization efficiency of vacuum drying large pipelines is very low. Therefore, the hydrogen barrier coating is not applied directly to the finished pipelines. Instead, the coating is applied by first coating the substrate, then welding and assembling the substrate, and finally repairing the coating. This process is relatively inefficient. The present invention aims to provide a hydrogen barrier coating that can be directly applied to finished pipelines.

[0014] This invention uses fusion-bonded epoxy powder as the coating base. According to the national standard GB / T 39636-2020, fusion-bonded epoxy powder (FBE) is a powder formed by melt-extrusion and pulverization of bisphenol A epoxy resin, novolac epoxy resin, curing agent, filler, and additives. Fusion-bonded epoxy powder can be applied by thermal spraying, which does not require drying.

[0015] To accommodate this characteristic, the other components of the coating must also be in powder form. However, without a diluent, mixing graphene powder with fused epoxy powder presents challenges in terms of both compatibility and dispersibility. Therefore, the present invention improves the selection and proportioning of coating components.

[0016] From a theoretical perspective, the hydrogen barrier effect of single-layer graphene is the best, and the average interlayer spacing of multilayer graphene is 0.33nm. The more layers of graphene, the higher the risk of hydrogen atoms passing through between the layers of graphene. However, in a mixed system, single-layer graphene has a larger specific surface area and a higher surface energy. It is easy to agglomerate and form graphite particles compared to few-layer graphene, but loses the hydrogen barrier effect. In the present invention, the preferred number of layers of few-layer graphene is 3 to 5 layers, which first enables graphene itself to maintain a more stable dispersed state in the system, and secondly, it is possible to reduce the cost of graphene, and improve the usage ratio and abundance ratio of coating graphene under the same material cost range.

[0017] In this coating system, the preferred silane coupling agent is KH-560. KH-560, also known as γ-glycidoxypropyltrimethoxysilane (γ-GPS), improves the bonding between few-layer graphene and the resin matrix. When used to treat mineral fillers, KH-560 can modify fillers using high shear forces in a solvent-free environment. Experimental results indicate that KH-560 can also treat few-layer graphene in trace amounts of solvent. Therefore, in this coating system, the weight ratio of silane coupling agent to alcohol solvent can be increased to 1.2-1.8:1, significantly reducing the overall wettability of the coating and maintaining a powdery state.

[0018] In a dilute system, silane diffuses evenly onto the graphene surface, whereas the migration of the silane coupling agent is hindered in this system. Therefore, this coating also increases the ratio of silane coupling agent to the few-layer graphene to compensate. Excess silane coupling agent, when grafted onto the graphene surface, covers the π electron channels, forming an insulating layer. This prevents aggregation of the few-layer graphene by both altering electrical properties and creating steric hindrance. Using KH-560 allows for increased silane coupling agent usage while reducing the need for alcohol solvent.

[0019] By adjusting the coating's component selection and ratio, the present invention improves the compatibility between the few-layer graphene and the fused epoxy powder. This optimization further increases the mass fraction of graphene that can be supported and immobilized by the fused epoxy powder. The weight ratio of fused epoxy powder to the few-layer graphene in the present invention can reach 45-55:1, significantly exceeding the graphene-supporting capacity of epoxy resins in prior art dilute coatings, further enhancing the coating's hydrogen barrier properties.

[0020] The present invention also proposes a hydrogen barrier coating, comprising the following components: 450 to 550 parts by mass of fused epoxy powder; 8 to 12 parts of few-layer graphene; 12 to 18 parts of silane coupling agent; 8 to 12 parts of alcohol; and 0.5 to 1.5 parts of weak acid; the few-layer graphene is a graphene layered stack formed of less than 5 layers.

[0021] Preferably, the few-layer graphene has 3 to 5 layers.

[0022] From the overall coating ratio, the mass ratio of the liquid phase to the solid phase is less than 2%. During hot-melt application, the liquid phase evaporates, forming a relatively thick system with graphene as the dispersant and the fused epoxy powder melt as the dispersed phase. In a dilute system, graphene sheets easily come into contact and aggregate due to the migration of solvent molecules. The low liquid-to-solid ratio increases the viscosity of the system, limiting the graphene's freedom of movement and making it more difficult to agglomerate, thus helping the graphene maintain a well-dispersed state during the curing process. The vacuum drying temperature is between 50 and 60°C, while the thermal spray process temperature is typically above 180°C, which promotes the condensation of the silanol groups of the silane coupling agent on the surface and removes the byproduct methanol, forming a dense coating surface.

[0023] The present invention also provides a hydrogen transmission pipeline comprising the aforementioned hydrogen barrier coating.

[0024] Preferably, the thickness of the hydrogen barrier coating is 150-200 μm.

[0025] The present invention first proposes a hydrogen barrier coating that can be applied to the surface of a hydrogen pipeline by thermal spraying, which simplifies the coating preparation process for hydrogen pipelines. The coating uses fused epoxy powder and graphene powder as the main active ingredients, and on this basis further optimizes the selection and proportion of auxiliary materials such as silane coupling agents and alcohol solvents, so that the coating can maintain good dispersion during the thermal spraying process and form a dense coating surface, thereby improving the hydrogen barrier effect. The preparation method of the coating is also very simple and can be obtained by only one-step shear mixing; in this method, the few-layer graphene does not need to be modified and dispersed through repeated dilution and drying, which is beneficial to maintaining the dispersed state of the few-layer graphene and improving the density of the hydrogen barrier coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Comparison of hydrogen permeation curves of the hydrogen pipeline of Example 2 and the hydrogen pipeline of the comparative example. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only a portion of the embodiments of the present invention, rather than all of the embodiments. Therefore, all other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0028] Example 1

[0029] This embodiment provides a method for preparing a hydrogen barrier coating and a corresponding powder type hydrogen barrier coating.

[0030] 1. Weigh 800g of XFQ027 graphene nanosheets (GNPs), 5L of isopropyl alcohol (IPA), 0.5% BYK088 defoamer, and 40g of sodium dodecyl sulfate (SDS) into a plastic bucket. Shear and mix using a high-speed shearing machine at 8000rpm for 3 hours. Then, homogenize 40 times using a homogenizer at 1500bar. After processing, measure the graphene particle size using a laser particle size analyzer. The measured particle sizes (D90 = 3.9 μm) and (D50 = 2.4 μm) meet the requirements.

[0031] 2. Use a vacuum powder dryer to dry the solution homogenized in the first step into powder.

[0032] 3. Take 500g of fused epoxy powder, 10g of the graphene powder prepared above, 2.25g of dispersant BYK9076, 15g of γ-GPS801 (epoxy bifunctional silane KH-560), 10g of ethanol and about 1mL of acetic acid, and mix them in a high-speed grinder for 10 minutes to obtain hydrogen barrier coating powder.

[0033] The mixed raw materials of this embodiment are all in powder form except for a small amount of ethanol and acetic acid, and the solvent-free wetting dispersant BYK9076 is selected as a processing aid to improve the processing performance. The final coating product is in powder form. This embodiment uses KH-560 as a silane coupling agent to improve the bonding between the few-layer graphene and the resin matrix. The weight ratio of the fused epoxy powder to the few-layer graphene in the coating product can reach 50:1, and the graphene loading ratio is high, which is conducive to improving the hydrogen resistance. In this embodiment, the weight ratio of the silane coupling agent to the few-layer graphene is 1.5:1; during the thermal spraying process, the silanol groups of the silane coupling agent condense on the surface and remove the byproduct methanol to form a dense coating surface.

[0034] Example 2

[0035] This example depicts a hydrogen pipeline. The pipeline's base material is X52 steel, a specialized wide and thick steel plate used for oil and natural gas pipelines. The hydrogen coating powder obtained in Example 1 was applied to the pipeline's surface using a conventional thermal spray process to a thickness of 150 μm. The coating was then left at room temperature for 24 hours to fully cure, resulting in a stable coating.

[0036] Comparative Example

[0037] This embodiment is a hydrogen transmission pipeline, the pipeline base material is X52 steel, and does not include a hydrogen barrier coating.

[0038] The hydrogen permeation test was performed on the hydrogen pipelines obtained in Example 2 and the comparative example at 4 MPa. The test results are shown in Table 1 and Figure 1 shown.

[0039] Table 1 Calculation results of hydrogen permeation parameters Sample Coating condition Hydrogen filling pressure Hysteresis time (s) Steady-state current density (A / cm²) <![CDATA[Overall hydrogen diffusion coefficient D (cm 2 / s)]]> Coating hydrogen diffusion coefficient (cm² / s) Surface hydrogen concentration Example 2 have 4MPa 2145 4.0046E-7 1.9599E-7 6.2378E-8 5.9296E-6 Comparative Example none 4MPa 66670 6.9463E-7 2.9545E-6 / 4.7516E-7 .

[0040] Under the condition of hydrogen filling pressure of 4MPa, the hydrogen diffusion coefficient of X52 hydrogen pipeline with coating is 6.2378×10 -8 The hydrogen diffusion coefficient of the uncoated X52 hydrogen pipeline is 2.5945×10 -6 The hydrogen diffusion coefficient decreased by 470% compared to the control; the hysteresis time was extended by 30 times; and the overall hydrogen diffusion coefficient and surface hydrogen concentration both decreased by an order of magnitude. The performance comparison between Example 2 and the comparative example shows that the hydrogen barrier coating prepared in Example 1 has a dense structure and good hydrogen barrier effect.

Claims

1. A hydrogen barrier coating, characterized in that: The preparation method thereof comprises the following preparation steps: A mixture of 450 to 550 parts by mass of fused epoxy powder, 8 to 12 parts of few-layer graphene, 12 to 18 parts of a silane coupling agent, 8 to 12 parts of an alcohol, and 0.5 to 1.5 parts of a weak acid is subjected to high-speed pulverization; the few-layer graphene is a graphene layered stack formed with less than 5 layers.

2. The hydrogen barrier coating according to claim 1, characterized in that: The few-layer graphene has 3 to 5 layers.

3. The hydrogen barrier coating according to claim 1, characterized in that: The silane coupling agent is KH-560.

4. The hydrogen barrier coating according to claim 1, characterized in that: The weight ratio of the silane coupling agent to the few-layer graphene is 1.2-1.8:

1.

5. The hydrogen barrier coating according to claim 1, characterized in that: The weight ratio of the silane coupling agent to the alcohol is 1.2-1.8:

1.

6. The hydrogen barrier coating according to claim 1, characterized in that: The weight ratio of the fused epoxy powder to the few-layer graphene is 45-55:

1.

7. The hydrogen barrier coating according to claim 1, characterized in that: The dispersant is BYK9076.

8. A hydrogen barrier coating, characterized in that: The invention comprises the following components: 450-550 parts by mass of fused epoxy powder; 8-12 parts by mass of few-layer graphene; 12-18 parts by mass of silane coupling agent; 8-12 parts by mass of alcohol; and 0.5-1.5 parts by mass of weak acid. The few-layer graphene is a graphene layered stack formed with 5 or less layers.

9. A hydrogen transmission pipeline, characterized in that: A hydrogen barrier coating made of the hydrogen barrier coating material according to claim 8.

10. The hydrogen transmission pipeline according to claim 9, characterized in that: The thickness of the hydrogen barrier coating is 150-200 μm.

Images