An Al2O3 - Y2O3 - Cr2O3 - Li3BO3 hydrogen - resistant coating and its preparation method

Abstract

The present invention relates to an Al2O3-Y2O3-Cr2O3-Li3BO3 hydrogen barrier coating and a preparation method thereof. The preparation method includes the following steps: Step 1: Ball-mill and mix Al2O3, Y2O3, Cr2O3, and Li3BO3 evenly according to the mass ratio to obtain a precursor powder; Step 2: Mix the precursor powder obtained in Step 1 with a solvent to prepare a slurry, immerse an iron-based substrate in the slurry, and then take it out and dry; Step 3: After subjecting the iron-based substrate treated with the slurry in Step 2 to low-temperature heat treatment, a hydrogen barrier coating is formed on its surface. In the coating, the mass ratio of Al2O3 is 40%-70%, the mass ratio of Y2O3 is 20%-50%, the mass ratio of Cr2O3 is 20%-50%, and the mass ratio of Li3BO3 is 5%-30%. The present invention utilizes the low melting point fluxing property of Li3BO3 to effectively reduce the densification sintering temperature of the Al2O3-Y2O3-Cr2O3 hydrogen barrier material, and a dense hydrogen barrier coating can be prepared at a lower temperature. This method has the advantages of low cost, simple operation, and excellent hydrogen barrier effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen barrier coatings, and particularly relates to an Al2O3 - Y2O3 - Cr2O3 - Li3BO3 hydrogen barrier coating and a preparation method thereof. Background Art

[0002] Hydrogen and its isotopes, due to their small radii, can easily penetrate into surrounding structural components, causing a decline in their mechanical strength and other properties, seriously affecting safety. To solve this problem, it is crucial to construct a hydrogen barrier coating on the surface of equipment under conditions involving the use of hydrogen and its isotopes.

[0003] However, among the developed hydrogen barrier materials, the oxide ceramic coating with the best hydrogen barrier ability has a mismatch in thermal expansion coefficient with the iron - based substrate. The thermal stress generated by drastic temperature changes can easily lead to coating cracking or separation from the substrate; moreover, the densification sintering temperature of the oxide - type hydrogen barrier material is too high, which will have an adverse impact on the base material during the coating preparation process. Therefore, it is very crucial to find a hydrogen barrier coating process with low - temperature preparation, strong bonding force, and excellent hydrogen barrier effect. Summary of the Invention

[0004] The purpose of the present invention is to provide an Al2O3 - Y2O3 - Cr2O3 - Li3BO3 hydrogen barrier coating and a preparation method thereof to solve the above - mentioned problems.

[0005] The present invention realizes the above - mentioned purpose through the following technical solutions:

[0006] The present invention provides an Al2O3 - Y2O3 - Cr2O3 - Li3BO3 hydrogen barrier coating, characterized in that the hydrogen barrier coating is a coating with a composition of Al2O3 - Y2O3 - Cr2O3 - Li3BO3 formed on an iron - based substrate.

[0007] As a further optimized scheme of the present invention, the hydrogen barrier coating is prepared by a low - temperature heat treatment method.

[0008] The present invention also provides a preparation method of the Al2O3 - Y2O3 - Cr2O3 - Li3BO3 hydrogen barrier coating as described in any one of the above, including the following steps,

[0009] Step 1: Ball - mill and mix Al2O3, Y2O3, Cr2O3, and Li3BO3 evenly according to a mass ratio to obtain a precursor powder.

[0010] Step 2: Mix the precursor powder obtained in Step 1 with a solution to prepare a slurry, immerse the iron - based substrate in the slurry, and then take it out and dry.

[0011] Step 3: After low - temperature heat treatment of the iron - based substrate treated with the slurry in Step 2, a hydrogen barrier coating is formed on its surface.

[0012] As a further optimization scheme of the present invention, in the first step, in terms of mass ratio, the proportion of Al2O3 is 40%-70%, the proportion of Y2O3 is 20%-50%, the proportion of Cr2O3 is 20%-50%, and the proportion of Li3BO3 is 5-30%.

[0013] As a further optimization scheme of the present invention, in the second step, the solution includes one or more of deionized water, ethanol, acetone, ethylene glycol, polyethylene glycol, butanol, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, N-methyl-2-pyrrolidone, polyvinyl butyral, polyvinylidene fluoride, polytetrafluoroethylene, triethanolamine, dibutyl phthalate, sodium carboxymethyl cellulose, styrene-butadiene rubber.

[0014] As a further optimization scheme of the present invention, in the third step, the low-temperature heat treatment is sintering at 600-800°C for 30-300 min in an air or oxygen atmosphere, and the thickness of the hydrogen barrier coating is 0.1-20 μm.

[0015] The beneficial effects of the present invention are as follows:

[0016] The present invention makes full use of the excellent hydrogen barrier effect of the existing Al2O3, Cr2O3, and Y2O3-based coatings, and further improves the densification sintering temperature of the hydrogen barrier coating and its bonding effect with the iron-based substrate by mixing Li3BO3, with the characteristics of low cost, simple operation, and excellent hydrogen barrier effect. Description of the Drawings

[0017] Figure 1 It is a morphology diagram of the Al2O3(40%)-Y2O3(30%)-Cr2O3(20%)-Li3BO3 hydrogen barrier coating prepared in Example 1 of the present invention. The coating thickness is about 1 μm, the structure is dense and there are no obvious pores between the coating and the substrate. Detailed Embodiments

[0018] The present invention will be further described in detail below with reference to the drawings. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present invention and cannot be understood as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention according to the above application content.

[0019] Example 1

[0020] This example provides a preparation method of an Al2O3-Y2O3-Cr2O3-Li3BO3 hydrogen barrier coating, including the following steps:

[0021] Step 1: Weigh Al2O3, Y2O3, Cr2O3, and Li3BO3 according to the mass ratio. Use ethanol as a dispersant for ball milling. The ball milling rate is 300 rpm, and the ball milling time is 2 h. Then, place the mixed powder in an oven at 100 °C for drying to obtain the precursor powder.

[0022] Among them, for the dosages of Al2O3, Y2O3, Cr2O3, and Li3BO3, by mass ratio, the proportion of Al2O3 is 40%, the proportion of Y2O3 is 30%, the proportion of Cr2O3 is 20%, and the proportion of Li3BO3 is 10%.

[0023] Step 2: Add the precursor powder obtained in Step 1 to a mixed solution with a volume ratio of ethanol to deionized water of 6:4, so that the solid content is 20%. Then add 10 wt% triethanolamine and 5 wt% polyethylene glycol, and stir and mix well to obtain a mixed slurry. Immerse the FeCrAl type steel specimen completely in this 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.

[0024] Step 3: Place the FeCrAl type steel specimen obtained in Step 2 in a muffle furnace and sinter it at 700 °C for 5 h, that is, a hydrogen barrier coating is formed on the surface of the iron-based matrix (as Figure 1 shown). The thickness of the hydrogen barrier layer is about 1 μm, the structure is dense and there are no obvious pores between the matrix. The hydrogen permeation reduction factor of the coating is tested by a gas phase hydrogen permeation device and the result is about 1750.

[0025] Example 2

[0026] This example provides a method for preparing an Al2O3 - Y2O3 - Cr2O3 - Li3BO3 hydrogen barrier coating, including the following steps:

[0027] Step 1: Weigh Al2O3, Y2O3, Cr2O3, and Li3BO3 according to the mass ratio. Use acetone as a dispersant for ball milling. The ball milling rate is 200 rpm, and the ball milling time is 10 h. Then, place the mixed powder in an oven at 110 °C for drying to obtain the precursor powder.

[0028] Among them, for the dosages of Al2O3, Y2O3, Cr2O3, and Li3BO3, by mass ratio, the proportion of Al2O3 is 50%, the proportion of Y2O3 is 20%, the proportion of Cr2O3 is 20%, and the proportion of Li3BO3 is 10%.

[0029] Step 2: Add the precursor powder obtained in Step 1 into a mixed solution of acetone and deionized water with a volume ratio of 5:5 to make its solid content 40%, then add 5wt% triethanolamine and 5wt% polyethylene glycol, and mix thoroughly by ball milling to obtain a slurry. Immerse the FeYAl type steel specimen 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 4 times, hang the sample in the vacuum drying oven at room temperature and keep the low pressure continuously until it is air-dried.

[0030] Step 3: Place the FeYAl type steel specimen obtained in Step 2 in a muffle furnace and sinter it at 800 °C for 2 h, that is, a hydrogen barrier coating is formed on the surface of the iron-based matrix. The thickness of the hydrogen barrier layer is about 4 μm, the structure is dense and there are no obvious pores between the coating and the matrix. The hydrogen permeation reduction factor of the coating is tested by a gas-phase hydrogen permeation device, and the result is about 2730.

[0031] Example 3

[0032] This example provides a method for preparing an Al2O3 - Y2O3 - Cr2O3 - Li3BO3 hydrogen barrier coating, including the following steps:

[0033] Step 1: Weigh Al2O3, Y2O3, Cr2O3, and Li3BO3 according to the mass ratio, use deionized water as a dispersant for ball milling, the ball milling rate is 300 rpm, and the ball milling time is 2 h. Then place the mixed powder in an oven at 120 °C for drying to obtain the precursor powder;

[0034] Among them, for Al2O3, Y2O3, Cr2O3, and Li3BO3 calculated by mass ratio, the proportion of Al2O3 is 40%, the proportion of Y2O3 is 20%, the proportion of Cr2O3 is 20%, and the proportion of Li3BO3 is 20%.

[0035] Step 2: Add the precursor powder obtained in Step 1 into a mixed solution of acetone and ethylene glycol with a volume ratio of 9:1 to make its solid content 30%, then add 5wt% polyethylene glycol and 5wt% polyvinyl butyral, and stir and mix thoroughly to obtain a mixed slurry. 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 keep the low pressure continuously at room temperature until it is air-dried.

[0036] Step 3: Place the FeCrAl type steel specimen obtained in Step 2 in a muffle furnace and sinter it at 750 °C for 4 h, that is, a hydrogen barrier coating is formed on the surface of the iron-based matrix. The thickness of the hydrogen barrier layer is about 2 μm, the structure is dense and there are no obvious pores between the coating and the matrix. The hydrogen permeation reduction factor of the coating is tested by a gas-phase hydrogen permeation device, and the result is about 2450.

[0037] Comparative Example 1

[0038] This comparative example provides a method for preparing an Al2O3-Y2O3-Cr2O3 hydrogen barrier coating, comprising the following steps:

[0039] Step 1: Weigh Al2O3, Y2O3, and Cr2O3 according to the mass ratio, use ethanol as a dispersant for ball milling, the ball milling rate is 300 rpm, the ball milling time is 2 h, and then the mixed powder is placed in an oven at 100 ° C to dry to obtain a precursor powder;

[0040] Among them, the usage of Al2O3, Y2O3 and Cr2O3, calculated by mass ratio, is 45% for Al2O3, 33% for Y2O3 and 22% for Cr2O3.

[0041] Step 2: Add the precursor powder obtained in step 1 to a mixed solution of ethanol and deionized water in a volume ratio of 6:4 to make the solid content 20%, then add 10wt% triethanolamine and 5wt% polyethylene glycol, and stir and mix thoroughly to obtain a mixed slurry. The FeCrAl steel specimen is completely immersed in the mixed slurry for 10 minutes, taken out and hung in a vacuum drying oven, and low pressure is continuously maintained at room temperature until it is dried.

[0042] Step 3: Place the FeCrAl steel specimen obtained in step 2 in a muffle furnace and sinter it at 700°C for 5 hours to form a hydrogen barrier coating on the surface of the iron-based substrate. Since the sintering temperature is too low and there is no flux assistance, only a powdered and loose coating is formed on the surface of the sample.

[0043] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. An Al2O3 - Y2O3 - Cr2O3 - Li3BO3 hydrogen - resistant coating, characterized in that, The hydrogen-blocking coating is a coating with a composition of Al2O3 - Y2O3 - Cr2O3 - Li3BO3 formed on an iron-based substrate; The hydrogen-blocking coating is prepared by a low-temperature heat treatment method, and the preparation method includes the following steps: Step 1: Ball-mill and mix Al2O3, Y2O3, Cr2O3, and Li3BO3 evenly according to the mass ratio to obtain a precursor powder. The dosages of Al2O3, Y2O3, Cr2O3, and Li3BO3, calculated by mass ratio, are as follows: the proportion of Al2O3 is 40% - 50%, the proportion of Y2O3 is 20% - 30%, the proportion of Cr2O3 is 20%, and the proportion of Li3BO3 is 5% - 20%; Step 2: Mix the precursor powder obtained in Step 1 with a solution to prepare a slurry, immerse the iron-based substrate in the slurry, and then take it out and dry it; Step 3: After low-temperature heat treatment of the iron-based substrate treated with the slurry in Step 2, a hydrogen-blocking coating is formed on its surface; In Step 3, the low-temperature heat treatment is sintering at 600 - 800 °C for 30 - 300 min in an air or oxygen atmosphere, and the thickness of the hydrogen-blocking coating is 0.1 - 20 μm.

2. The Al2O3 - Y2O3 - Cr2O3 - Li3BO3 hydrogen - resistant coating according to claim 1, wherein, In Step 2, the solution contains one or more of deionized water, ethanol, acetone, ethylene glycol, polyethylene glycol, butanol, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, N-methyl-2-pyrrolidone, triethanolamine, and dibutyl phthalate.

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