In-situ grown large size nanoplatelet reinforced and toughened hydrogen permeation barrier coating and method of making the same

Abstract

The present application relates to a kind of in situ autogenous large size nanosheet reinforced toughening hydrogen permeation resistant coating and its preparation method, can be applicable to fusion reactor blanket module structural material and hydrogen storage device and the hydrogen permeation resistance of various hydrogen-related fields of isotope of it.This composite coating uses phosphate and alumina powder as precursor, in situ aluminum phosphate nanosheet is generated in the coating.The composite coating combines the hydrogen / deuterium / tritium permeation resistance of phosphate and alumina, and through the reinforcement and toughening effect of in situ autogenous nanosheet, not only improve the hydrogen / deuterium / tritium performance of coating, but also increase the fracture toughness of coating by nearly 5 times, increase its service life.The preparation process of slurry dipping and pulling can be applied to the coating of the surface of complex structure material, greatly improve the practical value of this composite coating.The whole process is simple, healthy and environmentally friendly, suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coating materials, and particularly relates to a large-size in-situ self-grown nanosheet reinforced and toughened hydrogen permeation resistant coating and a preparation method thereof. BACKGROUND

[0002] Hydrogen and its isotopes deuterium, tritium, etc. can easily permeate into metal structural materials, resulting in a decrease in the strength and plasticity of the structural materials, performance deterioration, and thus a shortened service life of the structural materials and a threat to the use safety. At present, there are serious hydrogen isotope permeation problems in devices related to hydrogen, such as the blanket module structural materials of fusion reactors, heat collecting tubes for solar thermal power generation, pump barrels of oil pumps, oil pipelines, etc., and therefore it is urgent to coat a layer of coating material capable of blocking hydrogen permeation on the surface of the structural materials, i.e. a hydrogen permeation resistant coating. Among numerous coating materials, ceramics have the advantages of low hydrogen permeation rate and hydrogen solubility, high mechanical hardness, excellent thermal stability, and corrosion resistance, and therefore are widely considered as the best hydrogen permeation resistant candidate material.

[0003] The mechanical properties of the hydrogen permeation resistant coating have an important influence on its service life, but the mechanical properties of the hydrogen permeation resistant coating have not been studied yet. Hardness and fracture toughness are key indicators for evaluating the mechanical properties of the coating. Lower hardness will result in poor protection effect of the coating and the coating is easily deformed by external force. Low fracture toughness will also affect the service performance of the coating and easily cause the coating to fall off due to cracks. At present, there is no report on the toughening of ceramic hydrogen permeation resistant coatings.

[0004] Commonly used hydrogen resistant ceramic materials include Al2O3, Cr2O3, etc. For example, patent No. CN105667009 discloses a Y2O3 / Al2O3 / Cr2O3 composite gradient hydrogen permeation resistant coating and a preparation method thereof. The method uses metal-organic chemical vapor deposition technology to prepare a Y2O3 / Al2O3 / Cr2O3 multilayer composite gradient hydrogen permeation resistant coating on the surface of steel. Among them, the Cr2O3 coating serves as an intermediate layer to relieve thermal stress, and an Al2O3 coating with better hydrogen resistance is deposited thereon. However, this method needs multiple steps for coating deposition, and the process is complex, the cost is high, and the mechanical properties of the prepared coating are poor.

[0005] In summary, there is still a lack of a hydrogen resistant material with high hydrogen resistance and good toughness in the current ceramic hydrogen resistant coating, and it also meets the requirements of simple preparation process and coating preparation on the surface of complex parts. SUMMARY

[0006] The application provides an in-situ self-grown large-size nanosheet reinforced and toughened hydrogen permeation resistant coating and a preparation method thereof.

[0007] To achieve the above-mentioned purpose, the application adopts the following technical scheme.

[0008] The application provides an in-situ self-grown large-size nanosheet reinforced and toughened hydrogen permeation resistant coating, which is prepared by using phosphate and aluminum oxide as precursors, and aluminum phosphate nanosheets are generated in-situ in the coating during heat treatment.

[0009] Further, the coating is a single-layer composite coating, the aluminum phosphate nanosheets are generated in-situ in the coating, the thickness of the single-layer composite coating is less than or equal to 70 microns, and the thickness of the aluminum phosphate nanosheets is less than 1 micron.

[0010] Further, the mass ratio of the phosphate and the oxide is 100:1 to 1:1.

[0011] The application further provides a preparation method of the in-situ self-grown large-size nanosheet reinforced and toughened hydrogen permeation resistant coating.

[0012] (1) Preparing a phosphate precursor: phosphoric acid, aluminum hydroxide, deionized water and metal oxide are used as raw materials, and the mixture is fully stirred and dissolved to form a clear and transparent mixed solution, wherein the mass fraction of the phosphoric acid is 20% to 80%, the mass fraction of the aluminum hydroxide is 3% to 9%, the mass fraction of the metal oxide is 5% to 15%, and the mass fraction of the deionized water is 5% to 70%.

[0013] (2) Preparing a mixed slurry of phosphate and aluminum oxide powder: the phosphate precursor prepared in step (1) is mixed with aluminum oxide powder, and the mixture is fully stirred to form a uniform and stable slurry, wherein the mass ratio of the phosphate and the aluminum oxide powder is 100:1 to 1:1.

[0014] (3) The mixed slurry prepared in step (2) is uniformly coated on a stainless steel substrate by using a dip-coating method to obtain a substrate coating.

[0015] (4) The substrate coating obtained in step (3) is placed in a muffle furnace at a temperature of 100 DEG C to 800 DEG C for heat preservation for 30 to 120 minutes, the crystallization water in the coating is slowly removed, and finally the substrate coating is subjected to heat treatment in a muffle furnace at a temperature of 300 DEG C to 800 DEG C in an air atmosphere for 1 to 5 hours, the reaction temperature is controlled to adjust the morphology of the nanosheets, and the in-situ self-grown large-size nanosheet reinforced and toughened hydrogen permeation resistant coating is formed.

[0016] Further, the metal oxide includes zinc oxide or magnesium oxide.

[0017] Further, the step (3) uniformly coats the mixed slurry prepared in the step (2) on the stainless steel substrate by a dip-coating method, specifically including: immersing the stainless steel substrate into the mixed slurry, controlling the ascending speed of the substrate to be 1-300 um / s, and then drying and shaping the substrate in an oven after the substrate completely floats out of the liquid surface, wherein the drying temperature is 50-80℃, and the drying time is 1-3h.

[0018] The present application has the following beneficial effects:

[0019] 1. Compared with the prior art, the present application greatly improves the hydrogen / deuterium / tritium permeation resistance of the hydrogen permeation resistant ceramic coating by using the large-size nanosheets generated in situ during the coating preparation process. The generation of the nanosheets prolongs the permeation path of the hydrogen / deuterium / tritium molecules and increases the shielding effect of the coating, thereby protecting the steel substrate from erosion.

[0020] 2. The nanosheet reinforced and toughened hydrogen permeation resistant coating prepared by the present application also has good toughness because the nanosheets generated in situ in the coating hinder the propagation of cracks.

[0021] 3. The nanosheet reinforced and toughened hydrogen permeation resistant coating prepared by the present application can adjust the composition ratio of the phosphates and oxides therein, adjust the morphology of the nanosheets, control the hardness and elastic modulus of the coating, further improve the mechanical properties of the coating, meet the use needs of different scenes, and improve the service life of the coating.

[0022] 4. The preparation process of the present application is simple, the dip-coating process can meet the coating requirements of the surface coating of complex shape and structure components, and has strong repeatability, which is suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the high-temperature gas phase deuterium resistance experiment deuterium ion permeation current graph of the pure aluminum zinc phosphate coating;

[0024] Figure 2 is the high-temperature gas phase deuterium resistance experiment deuterium ion permeation current graph of the aluminum zinc phosphate and alpha-Al2O3 with a mass ratio of 10:1;

[0025] Figure 3 is the high-temperature gas phase deuterium resistance experiment deuterium ion permeation current graph of the aluminum zinc phosphate and alpha-Al2O3 with a mass ratio of 10:3;

[0026] Figure 4 is the SEM graph of the cracks generated in the aluminum phosphate / alpha-Al2O3 composite coating without nanosheets after high-temperature test;

[0027] Figure 5SEM image of the dense and intact aluminum zinc phosphate / α-Al2O3 composite coating produced by nanosheets after high temperature test;

[0028] Figure 6 SEM image of aluminum phosphate nanosheets generated in situ in the aluminum zinc phosphate coating. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0030] Example 1

[0031] A pure aluminum zinc phosphate reinforced and toughened hydrogen / deuterium / tritium permeation resistant coating with in-situ self-grown large-size nanosheets is prepared by the following method:

[0032] 1. The 321 stainless steel is polished flat with 1200 grit sandpaper, and then cleaned with deionized water and acetone after ultrasonic treatment with ethanol for 15 min.

[0033] 2. 15 g of phosphoric acid, 3.18 g of Al(OH)3 and 15 ml of deionized water are weighed and placed in a magnetic stirrer at 80°C

[0034] Heat and stir for about 12 h until it is fully dissolved and becomes clear and transparent. Then add 15 g of phosphoric acid and 4.80 g of zinc oxide, and place in a magnetic stirrer at 80°C Heat and stir for about 2 h until it is fully dissolved and becomes clear and transparent. The aluminum zinc phosphate precursor solution is prepared.

[0035] 3. The dip-coating process is completed with a pulling machine. The pulling speed is uniform throughout the process, and the pulling speed is set to 3 um / s. After pulling, the precursor coating and the substrate are placed in an oven at 80°C for 1 h. Finally, heat treatment is performed at 400°C for 90 min and at 500°C for 1 h with a heating rate of 5°C / min.

[0036] Example 2

[0037] An aluminum zinc phosphate / α-Al2O3 composite hydrogen / deuterium / tritium permeation resistant coating with a mass ratio of aluminum zinc phosphate to α-Al2O3 of 10:1 is prepared by the following method:

[0038] 1. The 321 stainless steel is polished flat with 1200 grit sandpaper, and then cleaned with deionized water and acetone after ultrasonic treatment with ethanol for 15 min.

[0039] 2. Weigh 15 g of phosphoric acid, add 3.18 g of Al(OH)3 and 15 ml of deionized water, and place in a magnetic stirrer at 80°C

[0040] Stir for 12 h or so until it is fully dissolved and clear and transparent, then add 15 g of phosphoric acid and 4.80 g of zinc oxide, and place in a magnetic stirrer at 80°C and stir for 2 h or so until it is fully dissolved and clear and transparent, to prepare an aluminum zinc phosphate precursor solution.

[0041] 3. Mix the aluminum zinc phosphate precursor solution prepared in the previous step with 30 nm nano-a-Al2O3 powder in a mass ratio of 10:1, and place in a magnetic stirrer, and stir at room temperature for 12 h until a uniform and stable slurry is obtained.

[0042] 4. Dip-coating process is completed with a pulling machine, the pulling speed is uniform throughout the process, the pulling speed is set to 7 um / s, after pulling, the precursor coating is placed together with the substrate in an oven at 80°C for 1 h, and finally heat treated at 400°C

[0043] for 90 min, and heat treated at 500°C for 1 h, with a heating rate of 5°C / min.

[0044] Example 3

[0045] An in-situ self-grown large-size nano-sheet (Al-Zn)PO4 toughened hydrogen permeation resistant coating with a mass ratio of aluminum zinc phosphate to a-Al2O3 of 10:3 is prepared by the following method:

[0046] 1. Grind the 321 stainless steel flat with 1200 mesh sandpaper, and clean with deionized water and acetone after ultrasonic cleaning with ethanol for 15 min.

[0047] 2. Weigh 15 g of phosphoric acid, add 3.18 g of Al(OH)3 and 15 ml of deionized water, and place in a magnetic stirrer at 80°C

[0048] Stir for 12 h or so until it is fully dissolved and clear and transparent, then add 15 g of phosphoric acid and 4.80 g of zinc oxide, and place in a magnetic stirrer at 80°C and stir for 2 h or so until it is fully dissolved and clear and transparent, to prepare an aluminum zinc phosphate precursor solution.

[0049] 3. Mix the aluminum zinc phosphate precursor solution prepared in the previous step with 30 nm nano-a-Al2O3 powder in a mass ratio

[0050] of 10:3, and place in a magnetic stirrer, and stir at room temperature for 12 h until a uniform and stable slurry is obtained.

[0051] 4. The dipping and pulling process is completed by a pulling machine, the pulling speed is uniform throughout the process, the pulling speed is set to 10 um / s, after pulling, the precursor coating is dried together with the substrate at 80 DEG C for 1 h, and finally, heat treatment is performed, the temperature is kept at 400 DEG C for 90 min, and the temperature is kept at 500 DEG C for 1 h, and the heating rate is 5 DEG C / min.

[0052] From comparative example 1 and examples 2 and 3, it can be seen that the high-temperature gas-phase deuterium ion penetration current of the aluminum zinc phosphate / alpha-Al2O3 composite coating reaches a steady state at 500 DEG C, which is an order of magnitude lower than that of pure aluminum zinc phosphate, and the deuterium penetration reduction factors of the 321L stainless steel are 220, 3440 and 2749 respectively, which indicates that the deuterium penetration resistance of the aluminum zinc phosphate / alpha-Al2O3 composite coating is at least 15 times higher than that of the single system of the aluminum zinc phosphate coating.

[0053] From comparative examples 2 and 3, it is found that the content of alpha-Al2O3 with different mass ratios has little effect on the performance of the coating, it is speculated that the morphology of the nanosheet in the coating does not change much, when the mass ratio is 10:1, the deuterium penetration resistance is best.

[0054] According to the above Figure 4 and Figure 5 It can be seen from the comparison that the generation of nanosheets greatly increases the fracture toughness of the coating, and no cracks are generated after high-temperature testing, which indicates that the nanosheets improve the mechanical properties of the coating, and further indicates that the application range of the coating is enhanced and the service life of the coating is prolonged.

[0055] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical scope disclosed by the present application can be easily thought by any person skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An in-situ self-grown large size nanoplatelet reinforced and toughened hydrogen permeation barrier coating, characterized in that, The coating takes phosphate and alumina as precursors, and aluminum phosphate nanosheets are generated in situ in the coating during heat treatment; the preparation method of the in-situ self-grown large-size nanosheet reinforced and toughened hydrogen permeation resistant coating comprises the following steps: (1) preparing a phosphate precursor: taking phosphoric acid, aluminum hydroxide, deionized water and metal oxide as raw materials, fully stirring and dissolving to form a clear and transparent mixed solution, wherein the mass fraction of phosphoric acid is 20%-80%; the mass fractions of aluminum hydroxide and metal oxide are 3%-9% and 5%-15% respectively; the mass fraction of deionized water is 5%-70%; (2) preparing a mixed slurry of phosphate and alumina powder: mixing the phosphate precursor prepared in step (1) with alumina powder, fully stirring to form a uniform and stable slurry, wherein the mass ratio of the two phases of phosphate and alumina powder is 10:1-1:1; (3) uniformly coating the mixed slurry prepared in step (2) on a stainless steel substrate by dip-coating method to obtain a substrate coating; (4) placing the substrate coating obtained in step (3) in a muffle furnace at 100-800 ℃ for 30-120 min to slowly remove the crystal water in the coating, and finally performing heat treatment at 300-800 ℃ in an atmospheric atmosphere for 1-5 h to control the reaction temperature and adjust the morphology of the nanosheets, thereby forming the in-situ self-grown large-size nanosheet reinforced and toughened hydrogen permeation resistant coating.

2. The in-situ autogenously grown large size nanoplatelet reinforced and toughened hydrogen permeation barrier coating as claimed in claim 1 wherein, The coating is a single-layer composite coating, aluminum phosphate nanosheets are generated in situ in the coating, the thickness of the single-layer composite coating is ≤70 um, and the thickness of the aluminum phosphate nanosheets is <1 um.

3. The in-situ autogenously grown large size nanoplatelet reinforced and toughened hydrogen permeation barrier coating of claim 1, wherein, The metal oxide includes zinc oxide or magnesium oxide.

4. The in-situ autogenously grown large size nanoplatelet reinforced and toughened hydrogen permeation barrier coating as claimed in claim 1 wherein, Step (3) uniformly coats the mixed slurry prepared in step (2) on a stainless steel substrate by dip-coating method, which specifically comprises: immersing the stainless steel substrate in the mixed slurry, controlling the rising speed of the substrate to be 1-300 um / s, and then placing the substrate in an oven for drying and setting after the substrate completely floats out of the liquid surface, the drying temperature is 50-80 ℃, and the drying time is 1-3 h.

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