A composite oxide hydrogen barrier coating and its preparation method

Abstract

The present invention discloses a hydrogen-barrier composite oxide coating and a preparation method thereof, comprising the following steps: S1. Alumina, yttrium oxide and lithium borate are ball-milled and mixed evenly to obtain a precursor powder; S2. The precursor powder is mixed into a solvent, and a mixed slurry is obtained by means of grinding, stirring, ball-milling or ultrasonic treatment, etc.; S3. A metal substrate is immersed in the mixed slurry and then taken out, and after vacuum drying and low-temperature sintering, a hydrogen-barrier coating attached to the surface of the metal substrate is obtained. By making use of the excellent hydrogen-barrier effect of existing oxide coatings such as alumina and yttrium oxide, and by mixing a small amount of lithium borate, and taking advantage of the low melting point characteristic of lithium borate, which is partially liquefied at a lower sintering temperature, the aggregation of alumina and yttrium oxide microcrystalline particles is effectively promoted and densification sintering is achieved, the bonding effect between the coating and the substrate is improved, and finally a dense coating is constructed on the surface of the iron-based structural member at a lower sintering temperature. This method has the characteristics of low cost, simple operation and excellent hydrogen-barrier effect.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen barrier coatings, and specifically to a composite oxide hydrogen barrier coating and a preparation method thereof. Background Art

[0002] At present, the diffusion problem existing in the storage, transportation and use of hydrogen energy still needs to be solved urgently. Hydrogen and its isotopes have extremely small radii and are very easy to penetrate into the surrounding iron-based metal structural components, becoming interstitial atoms, which reduces the mechanical strength of the metal and even has an adverse impact on the functionality of the structural components. Therefore, coating the surface of equipment in contact with hydrogen and its isotopes with a hydrogen barrier coating to inhibit or greatly slow down the diffusion of hydrogen into iron-based metal components has become a research hotspot. Since hydrogen diffuses in metals in the form of hydrogen atoms in metal interstices, while in ceramics it mainly diffuses in the form of hydrogen molecules, oxide ceramics, including alumina and yttrium oxide, have received extensive attention due to their excellent hydrogen barrier performance and high-temperature structural stability and have become one of the preferred materials for hydrogen barrier coatings. However, how to construct a dense oxide ceramic hydrogen barrier coating on the surface of iron-based metal structural components has not been solved yet. Since the densification sintering temperature of oxide ceramics is too high, while the sintering temperature of the iron-based substrate is not higher than 800°C, the mismatch in sintering temperature brings difficulties to the processing and preparation of coating materials. Therefore, it is very crucial to achieve the densification sintering of oxide ceramics on the surface of iron-based metal components at a lower temperature. Summary of the Invention

[0003] In view of this, the present invention provides a composite oxide hydrogen barrier coating and a preparation method thereof to solve the problems raised in the above background art.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] On the one hand, the present invention discloses a preparation method of a composite oxide hydrogen barrier coating, including the following steps:

[0006] S1. Mix alumina, yttrium oxide and lithium borate evenly by ball milling to obtain a precursor powder;

[0007] S2. Mix the precursor powder into a solvent and obtain a mixed slurry by methods such as grinding, stirring, ball milling or ultrasonic treatment;

[0008] S3. Immerse a metal substrate into the mixed slurry and then take it out, and obtain a hydrogen barrier coating attached to the surface of the metal substrate after vacuum drying and low-temperature sintering.

[0009] As a further solution of the present invention: the mass ratio of alumina, yttrium oxide and lithium borate is (20 - 70):(20 - 50):(10 - 30).

[0010] As a further solution of the present invention: the solvent is at least one of deionized water, ethanol, acetone, isopropanol, propanol, ethylene glycol, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, polyvinyl butyral, polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, and styrene-butadiene rubber.

[0011] As a further solution of the present invention: in step S3, the low-temperature sintering is carried out in one or more of air, nitrogen, argon, or oxygen atmosphere conditions at 600 - 750 °C for 30 - 300 minutes.

[0012] As a further solution of the present invention: the thickness of the hydrogen barrier coating is 0.1 - 20 μm.

[0013] As a further solution of the present invention: the material of the metal matrix is iron.

[0014] On the other hand, the present invention discloses a composite oxide hydrogen barrier coating prepared by the preparation method described in any one of the above.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] The present invention makes full use of the excellent hydrogen barrier effect of oxide coatings such as alumina and yttrium oxide in the prior art. By mixing a small amount of lithium borate, and utilizing the low melting point characteristic of lithium borate, it is partially liquefied at a lower sintering temperature, effectively promoting the aggregation of alumina and yttrium oxide microcrystalline particles and achieving densification sintering, improving the bonding effect between the coating and the substrate, and finally achieving the construction of a dense coating on the surface of the iron-based structural part at a lower sintering temperature. This method has the characteristics of low cost, simple operation, and excellent hydrogen barrier effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the morphology of the composite oxide hydrogen barrier coating prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0020] The raw materials used in the following examples and comparative examples are all commercially available conventional and commonly used products. The reduction of hydrogen permeation was measured using a gas-phase hydrogen permeation device. The higher the value, the lower the permeability.

[0021] It can be understood that the above raw material reagents are only examples of some specific embodiments of the present invention to make the technical solution of the present invention clearer, and do not represent that the present invention can only use the above reagents. Specifically, it is subject to the scope in the claims. In addition, the "parts" mentioned in the examples and comparative examples refer to parts by weight unless otherwise specified.

[0022] Any range described in the present invention includes the end values and any numerical values between the end values, as well as any sub-ranges constituted by any numerical values between the end values or the end values.

[0023] Example 1

[0024] Step S1: Weigh 70 parts of alumina, 20 parts of yttrium oxide, and 10 parts of lithium borate. Use acetone as a dispersant for ball milling. The ball milling rate is 300 rpm and the ball milling time is 2 h to obtain a precursor powder. Subsequently, the precursor powder is placed in an oven at 100 °C for drying to obtain a dried powder.

[0025] Step S2: Add the dried powder into a mixed solvent of ethanol and glycerol (the volume ratio of ethanol to glycerol is 1:1), and stir and mix well to obtain a mixed slurry with a solid content of 50%. Immerse the iron-based sample completely in the mixed slurry for 10 min, take it out and hang it in a vacuum drying oven, and continuously maintain a low pressure at room temperature until it dries.

[0026] Step S3: Hang the sample dried in Step S3 in a high-temperature furnace and sinter it at 700 °C for 1 h in an air atmosphere to obtain a hydrogen-blocking coating attached to the surface of the sample; the coating is relatively dense, there are no obvious pores in the cross-section, and the coating thickness is 1 μm. At room temperature, the hydrogen permeation reduction factor of the coating is 1800.

[0027] Example 2

[0028] Step S1: Weigh 60 parts of alumina, 25 parts of yttrium oxide, and 15 parts of lithium borate. Use ethanol as a dispersant for ball milling. The ball milling rate is 200 rpm and the ball milling time is 10 h to obtain a precursor powder. Subsequently, the precursor powder is placed in an oven at 100 °C for drying to obtain a dried powder.

[0029] Step S2: Add the dried powder into a mixed solvent of acetone and ethylene glycol (where the volume ratio of acetone to ethylene glycol is 1:1), and fully stir and mix by ball milling to obtain a mixed slurry. The ball milling rate is 100 rpm, the ball milling time is 5 h, and the solid content in the slurry is 40%. Immerse the iron-based sample completely in the slurry, take it out and hang it in a vacuum drying oven. When there are no more dripping liquid drops, immerse it completely in the slurry again, and take it out and hang it in a vacuum drying oven. After repeating the immersion 5 times, hang the sample in the vacuum drying oven at room temperature, and continuously maintain a low pressure until it is dried.

[0030] Step S3: Place the sample dried in Step S2 in a muffle furnace, and sinter it at 750 °C for 0.5 h under an argon atmosphere to obtain a hydrogen-blocking coating attached to the surface of the sample; the coating thickness is 3 μm. At room temperature, the hydrogen permeation reduction factor of the coating is 2200.

[0031] Example 3

[0032] Step S1: Weigh 20 parts of alumina, 50 parts of yttrium oxide, and 30 parts of lithium borate, and use deionized water as a dispersant for ball milling. The ball milling rate is 400 rpm, and the ball milling time is 2 h to obtain a precursor powder. Subsequently, place the precursor powder in an oven at 120 °C for drying to obtain a dried powder.

[0033] Step S2: Add the dried powder into a mixed solvent of acetone, deionized water, and sodium carboxymethylcellulose, and fully grind and stir for 1 hour to obtain a mixed slurry, where the solid content is 45%. Immerse the iron-based sample completely in the slurry, take it out and hang it in a vacuum drying oven. When there are no more dripping liquid drops, immerse it completely in the mixed slurry again, and take it out and hang it in a vacuum drying oven. After repeating the immersion 10 times, hang the sample in the vacuum drying oven at room temperature, and continuously maintain a low pressure until it is dried.

[0034] Step S3: Place the sample dried in Step S2 in a high-temperature furnace, and sinter it at 700 °C for 2 h under an oxygen atmosphere to obtain a hydrogen-blocking coating attached to the surface of the sample; the coating thickness is 5 μm. At room temperature, the hydrogen permeation reduction factor of the coating is 2700.

[0035] Comparative Example 1

[0036] Step S1: Weigh 70 parts of alumina and 30 parts of yttrium oxide, and use acetone as a dispersant for ball milling. The ball milling rate is 300 rpm, and the ball milling time is 2 h to obtain a precursor powder. Subsequently, place the precursor powder in an oven at 100 °C for drying to obtain a dried powder.

[0037] Step S2: Add the dried powder into a mixed solvent of ethanol and glycerol, and stir well to obtain a mixed slurry with a solid content of 50%. Immerse the iron-based structural part completely in the slurry for 10 minutes, take it out and hang it in a vacuum drying oven, and continuously maintain a low pressure at room temperature until it dries.

[0038] Step S3: Place the dried sample in Step S3 in a high-temperature furnace, and sinter it at 700 °C for 2 hours in an air atmosphere to obtain a hydrogen-blocking coating attached to the surface of the sample. However, the whole coating is in a pulverized state and has a weak bond with the substrate. The coating thickness is 1 μm. At room temperature, the hydrogen permeation reduction factor of the coating is 350.

[0039] Although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0040] Therefore, the above description is only the preferred embodiment of the present application, and is not used to limit the scope of implementation of the present application; that is, all equivalent transformations made according to the scope of the claims of the present application are within the protection scope of the claims of the present application.

Claims

1. A method for preparing a hydrogen-blocking coating of a composite oxide, characterized in that, It includes the following steps: S1. Ball-mill and mix alumina, yttrium oxide, and lithium borate evenly to obtain a precursor powder; S2. Mix the precursor powder into a solvent to obtain a mixed slurry; S3. Immerse the metal substrate into the mixed slurry and then take it out, and after vacuum drying and low-temperature sintering, a hydrogen-blocking coating attached to the surface of the metal substrate is obtained; In step S3, the low-temperature sintering is carried out at 600 - 750 °C for 30 - 300 minutes under one or more of the atmosphere conditions of air, nitrogen, argon, or oxygen; The mass ratio of the alumina, yttrium oxide, and lithium borate is (20 - 70):(20 - 50):(10 - 30).

2. The preparation method according to claim 1, wherein The solvent is at least one of deionized water, ethanol, acetone, isopropanol, propanol, ethylene glycol, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, polyvinyl butyral, polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, and styrene-butadiene rubber.

3. The preparation method according to claim 1, wherein The thickness of the hydrogen-blocking coating is 0.1 - 20 μm.

4. The preparation method according to claim 1, wherein The material of the metal substrate is iron.

5. A composite oxide hydrogen-blocking coating prepared by the preparation method according to any one of claims 1 - 4.

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