Preparation method and application of surface spraying coating of nuclear power spent fuel transportation container

Abstract

The invention discloses a preparation method and application of a surface spraying coating of a nuclear power spent fuel transportation container, and belongs to the technical field of metal material and component surface modification and processing and frictional wear protection. According to the method, the powder core nickel-based wire is prepared, the NiCrB base coat is sprayed through the electric arc, and the Ni-based boron-containing composite coating surface layer is sprayed through the electric arc, so that the bonding strength between the Ni-based composite coating and the A350LF3 steel and the compactness of the coating are greatly improved. The obtained Ni-based boron-containing composite coating meets the binding force and density requirements of an A350LF3 steel surface coating for the nuclear power spent fuel transportation container, the purpose of shielding gamma radiation and neutron radiation is achieved, the reliability of the nuclear power spent fuel transportation container can be remarkably improved, and the service life of the nuclear power spent fuel transportation container can be remarkably prolonged; and the harsh service requirements of high temperature and high radiation of the spent fuel transportation container for nuclear power are met.

Description

Technical Field

[0001] The invention relates to a coating preparation method and application of a spent fuel transport container for nuclear power, belonging to the technical field of surface modification and processing of metal materials and components, and friction and wear protection. Background Art

[0002] As nuclear power is put into operation, the fissile nuclides uranium in the fuel are gradually consumed and are insufficient to maintain the fission reaction. The fuel removed from the reactor is called spent fuel, or irradiated fuel. The 3% to 4% of uranium waste (spent fuel) that has been used is separated from the fission products by chemical methods, which is called spent fuel re-dissolution and reprocessing technology, which is also the most critical link in the latter part of the nuclear fuel cycle. The research and development design of spent fuel transport containers is more difficult than that of new fuel and uranium hexafluoride transport containers. In addition to ensuring subcritical safety, due to its radioactivity and decay heat, it is also necessary to ensure safety under normal transportation conditions and accident conditions during transportation. In order to achieve the purpose of safe transportation, neutron absorbing materials are required in the container to ensure subcritical safety; sufficient shielding thickness and appropriate shielding materials are required to shield gamma radiation and neutron radiation; a good heat dissipation structure is required to timely conduct decay heat to prevent the temperature of the component cladding from being too high; at the same time, it must be able to effectively block the introduction of external heat so that the container can ensure safety under high temperature conditions of 800℃ for half an hour.

[0003] In recent years, the nuclear power industry in our country has developed rapidly, and the localization of spent fuel transport containers required by nuclear power plants has become a trend. A350 LF3 is a new type of container steel used for storing and transporting highly radioactive spent fuel. Due to the particularity of the use environment of A350 LF3, the performance requirements in terms of high strength, high temperature corrosion resistance, radiation resistance, and low thermal expansion coefficient are more stringent. Therefore, it is necessary to develop materials for spent fuel transport containers that meet stringent requirements. Among them, Ni-based boron-containing composite materials combine the advantages of aluminum metal such as toughness, ductility, and formability with the advantages of boron carbide ceramics such as hardness, ablation resistance, and low density. It has low density, high thermal conductivity, good mechanical properties, and high neutron absorption capacity. However, the price of this material is relatively high and cannot be widely promoted and applied. The combination of A350 LF3 steel matrix + Ni-based boron-containing composite coating provides a more economical solution for spent fuel transport container materials. However, in order to meet the structural strength requirements of large containers while achieving the purpose of radioactive shielding, there are high requirements for the surface process of setting composite material coatings on the A350 LF3 steel matrix. The arc spraying process has the advantages of high production efficiency, high energy utilization, low spraying cost, good safety and high coating bonding strength. It is suitable for the surface modification of large spent fuel transport containers for nuclear power. However, there are no related reports on the method of using arc spraying to spray dense Ni-based boron-containing composite coatings on A350 LF3 steel substrates at home and abroad. Summary of the invention

[0004] The purpose of the present invention is to provide a coating preparation method and application of a spent fuel transport container for nuclear power in order to solve the above problems. The obtained Ni-based boron-containing composite coating meets the bonding strength and density requirements of the surface coating of A350 LF3 steel for spent fuel transport containers for nuclear power, and achieves the purpose of shielding gamma radiation and neutron radiation, which can significantly improve the reliability and service life of spent fuel transport containers for nuclear power, and meet the high temperature and high radiation stringent service requirements of spent fuel transport containers for nuclear power.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application of the present invention comprises the following steps:

[0007] S1: Add B4C ceramic powder to the activation solution and perform ultrasonic treatment at room temperature for 60 to 90 minutes; separate the activation solution after static sedimentation, and then wash the powder with deionized water for plating. Prepare Ni-Mo coated B4C powder by room temperature ultrasonic assisted chemical plating method, adjust the pH value of the chemical plating solution to 9 to 11 with NaOH, and the powder loading amount is 8 to 12 g / L. Perform ultrasonic assisted chemical plating at room temperature for 80 to 120 minutes. After the chemical plating is completed, wash the powder with deionized water and dry it to obtain Ni-Mo coated B4C powder.

[0008] S2: Take 30-50 parts by weight of Ni-Mo coated B4C powder, 20-30 parts by weight of FeB powder and 20-50 parts by weight of FeCr67C6.0 powder, stir them at high speed with a V-type powder mixer, and fill them into a U-shaped Ni-Cu (Monel 400) alloy strip with a purity of 99% and a certain shape, with a filling rate of 30-50%, and then roll and draw them into Φ2.0-3.0mm powder core nickel-based wire.

[0009] S3: The NiCrB powder core wire is directly sprayed onto the surface of A350 LF3 steel for nuclear power spent fuel container by arc spraying through a spray gun. The spraying process parameters are: voltage 28-35V; current 180-220A; spraying distance 150-200mm; compressed air pressure 0.4-0.6MPa, and a NiCrB base layer with a thickness of 50-100μm is prepared.

[0010] S4: The powder-core nickel-based wire in S1 was sprayed onto the surface of A350 LF3 steel for nuclear power spent fuel container by an arc spraying method through a spray gun to form a NiCrB base layer. The spraying process parameters were: voltage 30-35V; current 200-250A; spraying distance 150-200mm; compressed air pressure 0.4-0.6MPa, and a nickel-based boron-containing composite coating with a thickness of 1000-2000μm was prepared.

[0011] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application are characterized in that the components and concentrations of the chemical plating solution in S1 are: NiSO4·6H2O 15-20g / L, Na2MoO4·2H2O 10-15g / L, Na3C6H5O7·2H2O 20-30g / L, CN2H4S 0.02-0.10g / L and N2H4·H2O (80%) 80-100mL / L.

[0012] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application are characterized in that the particle size range of the Ni-Mo coated B4C powder, FeB powder and FeCr67C6.0 powder in S2 is 20 to 60 μm, the high-speed stirring rate of the V-type powder mixer is 3000 to 5000 rpm, and the stirring time is 60 to 120 min.

[0013] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application are characterized in that the composition of the NiCrB powder core wire in S3 is: Cr 18-20wt.%, B 5.0-7.0wt.%, O≤0.1wt.%, Ni balance. The outer skin is made of nickel strip, and the diameter of the final powder core wire is 2.0-3.0mm.

[0014] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application are characterized in that the porosity of the nickel-based composite coating sprayed in S3 and S4 does not exceed 3%, and the bonding strength with A350 LF3 steel is not less than 35MPa.

[0015] The above-mentioned method for preparing a surface spray coating for a spent fuel transport container for nuclear power and its application are characterized in that the thermal neutron absorption performance of the nickel-based boron-containing composite coating prepared by arc spraying in S3 and S4 together with the steel plate as a whole is not less than 90%.

[0016] The present invention is beneficial in that:

[0017] 1. The Ni-based boron-containing composite coating obtained by the coating preparation method of the nuclear power spent fuel transport container of the present invention is prepared by preparing a powder-core nickel-based wire, an arc-sprayed NiCrB primer layer and an arc-sprayed Ni-based boron-containing composite coating surface layer, thereby greatly improving the bonding strength between the Ni-based composite coating and the A350 LF3 steel and the density of the coating. The arc spraying method is adopted, and the inventors spray the NiCrB primer layer and set the arc spraying parameters through creative labor, so that the surface roughness is further increased, and the bonding strength between the Ni-based coating and the A350 LF3 steel is ensured; at the same time, the Ni-based coating has good high temperature resistance and corrosion resistance, and the introduction of a large amount of B element can improve the shielding effect of gamma radiation and neutron radiation. Therefore, the combination of A350LF3 steel + arc-sprayed boron-containing Ni-based composite coating can achieve the purpose of radioactive shielding while meeting the structural strength requirements of the container, which is conducive to the comprehensive improvement of the service life of the nuclear power spent fuel transport container.

[0018] 2. In the Ni-based boron-containing composite coating of the present invention, since the Ni-Mo coated B4C powder, the loss of B element during the spraying process is relatively low, and the AES test shows that the B element content on the coating surface is ≥40at.%; therefore, the arc-sprayed Ni-based boron-containing composite coating obtained by the present invention has a strong thermal neutron absorption capacity, the neutron absorption cross section of which far exceeds that of ordinary boron-containing steel, and the thermal neutron absorption performance is not less than 90%;

[0019] 3. The high-speed stirring of the V-type powder mixer ensures that the particles of each component in the powder core wire can be evenly dispersed; the powder core wire obtained by rolling and drawing and the arc spraying method ensure the uniform distribution of each component in the surface coating of A350 LF3 steel;

[0020] 4. The nickel-based powder core wire is made of U-shaped Ni-Cu (Monel 400) alloy strip. The Cu element contained in it helps to improve the conductivity of the wire, obtain better melting and atomization effects, and help to reduce the porosity of the sprayed coating.

[0021] 5. The present invention forms a Ni-based boron-containing composite coating on the surface of a spent fuel transport container for nuclear power by using an arc spraying method, thereby achieving corrosion resistance, high temperature resistance and improved radioactive shielding performance, while also greatly reducing spraying energy consumption and cost, and improving spraying efficiency and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a SEM morphology photo of the Ni-based boron-containing composite coating on the surface of the spent fuel transport container for nuclear power prepared in Example 1. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with Examples 1-3 and Comparative Example 1.

[0024] Embodiment 1:

[0025] Follow the steps below to prepare and apply the spray coating on the surface of spent fuel transport container for nuclear power:

[0026] S1: Add B4C ceramic powder to the activation solution and treat it with ultrasound at room temperature for 90 minutes; separate the activation solution after static sedimentation, and then wash the powder with deionized water for plating. Ni-Mo coated B4C powder was prepared by room temperature ultrasonic assisted chemical plating method. The pH value of the chemical plating solution was adjusted to 10 with NaOH, the powder loading was 10g / L, and ultrasonic assisted chemical plating was performed at room temperature for 120 minutes. After the chemical plating was completed, the powder was washed with deionized water and dried to obtain Ni-Mo coated B4C powder.

[0027] S2: Take 50 parts by weight of Ni-Mo coated B4C powder, 20 parts of FeB powder and 30 parts by weight of FeCr67C6.0 powder, stir them at high speed with a V-type powder mixer, and fill them into a U-shaped Ni-Cu (Monel 400) alloy strip with a purity of 99% and a certain shape. The filling rate is 45%, and then rolled and drawn to make a Φ2.0mm powder-core nickel-based wire.

[0028] S3: The NiCrB powder core wire was directly sprayed onto the surface of A350 LF3 steel for nuclear power spent fuel container by arc spraying method through a spray gun. The spraying process parameters were: voltage 30V; current 200A; spraying distance 150mm; compressed air pressure 0.5MPa, and a NiCrB primer layer with a thickness of 100μm was prepared.

[0029] S4: The powder-core nickel-based wire in S1 was sprayed onto the surface of A350 LF3 steel for nuclear power spent fuel container by an arc spraying method through a spray gun to form a NiCrB base layer. The spraying process parameters were: voltage 35V; current 220A; spraying distance 150mm; compressed air pressure 0.5MPa, and a nickel-based boron-containing composite coating with a thickness of 2000μm was prepared.

[0030] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application are characterized in that the components and concentrations of the chemical plating solution in S1 are respectively: NiSO4·6H2O 20g / L, Na2MoO4·2H2O 15g / L, Na3C6H5O7·2H2O 30g / L, CN2H4S 0.05g / L and N2H4·H2O (80%) 100mL / L.

[0031] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application are characterized in that the particle size range of the Ni-Mo coated B4C powder, FeB powder and FeCr67C6.0 powder in S2 is 40 μm, the high-speed stirring rate of the V-type powder mixer is 4000 rpm, and the stirring time is 120 min.

[0032] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application is characterized in that the composition of the NiCrB powder core wire in S3 is: Cr 20wt.%, B 5.0wt.%, O≤0.1wt.%, Ni balance. The outer skin is made of nickel strip, and the diameter of the final powder core wire is 2.0mm.

[0033] The steel grade used for nuclear power spent fuel containers is A350 LF3 steel.

[0034] The porosity of the nickel-based boron-containing composite coating sprayed in S3 and S4 was 2.8% according to the GB / T 13298-2015 standard, and the bonding strength with A350 LF3 steel after testing according to the GB / T 8642-2002 standard was 36 MPa.

[0035] The thermal neutron absorption performance of the nickel-based boron-containing composite coating prepared by arc spraying in S3 and S4 together with the steel plate as a whole is about 95%. 13 ~2.5×10 14 cm -2 After neutron irradiation with a certain amount of radiation, the material did not suffer obvious radiation damage; in the neutral salt spray test according to GB6458 standard, no corrosion was found on the coating surface after more than 2000 hours.

[0036] Embodiment 2:

[0037] Follow the steps below to prepare and apply the spray coating on the surface of spent fuel transport container for nuclear power:

[0038] S1: Add B4C ceramic powder to the activation solution and treat it with ultrasound at room temperature for 90 minutes; separate the activation solution after static sedimentation, and then wash the powder with deionized water for plating. Ni-Mo coated B4C powder was prepared by room temperature ultrasonic assisted chemical plating method. The pH value of the chemical plating solution was adjusted to 10 with NaOH, the powder loading was 10g / L, and ultrasonic assisted chemical plating was performed at room temperature for 120 minutes. After the chemical plating was completed, the powder was washed with deionized water and dried to obtain Ni-Mo coated B4C powder.

[0039] S2: Take 40 parts by weight of Ni-Mo coated B4C powder, 30 parts of FeB powder and 30 parts of FeCr67C6.0 powder, stir them at high speed with a V-type powder mixer, and fill them into a U-shaped Ni-Cu (Monel 400) alloy strip with a purity of 99% and a certain shape. The filling rate is 40%, and then rolled and drawn to make a Φ2.0mm powder-core nickel-based wire.

[0040] S3: The NiCrB powder core wire was directly sprayed onto the surface of A350 LF3 steel for nuclear power spent fuel container by arc spraying method through a spray gun. The spraying process parameters were: voltage 30V; current 200A; spraying distance 150mm; compressed air pressure 0.5MPa, and a NiCrB primer layer with a thickness of 100μm was prepared.

[0041] S4: The powder-core nickel-based wire in S1 was sprayed onto the surface of A350 LF3 steel for nuclear power spent fuel container by an arc spraying method through a spray gun to form a NiCrB base layer. The spraying process parameters were: voltage 35V; current 220A; spraying distance 150mm; compressed air pressure 0.5MPa, and a nickel-based boron-containing composite coating with a thickness of 2000μm was prepared.

[0042] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application are characterized in that the components and concentrations of the chemical plating solution in S1 are respectively: NiSO4·6H2O 20g / L, Na2MoO4·2H2O 15g / L, Na3C6H5O7·2H2O 30g / L, CN2H4S 0.05g / L and N2H4·H2O (80%) 100mL / L.

[0043] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application are characterized in that the particle size range of the Ni-Mo coated B4C powder, FeB powder and FeCr67C6.0 powder in S2 is 40 μm, the high-speed stirring rate of the V-type powder mixer is 4000 rpm, and the stirring time is 120 min.

[0044] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application is characterized in that the composition of the NiCrB powder core wire in S3 is: Cr 20wt.%, B 5.0wt.%, O≤0.1wt.%, Ni balance. The outer skin is made of nickel strip, and the diameter of the final powder core wire is 2.0mm.

[0045] The steel grade used for nuclear power spent fuel containers is A350 LF3 steel.

[0046] The porosity of the nickel-based boron-containing composite coating sprayed in S3 and S4 was 2.3% according to the GB / T 13298-2015 standard, and the bonding strength with A350 LF3 steel after testing according to the GB / T 8642-2002 standard was 41 MPa.

[0047] The thermal neutron absorption performance of the nickel-based boron-containing composite coating prepared by arc spraying in S3 and S4 together with the steel plate as a whole is about 93%. 13 ~2.5×10 14 cm -2 After neutron irradiation with a certain amount of radiation, the material did not suffer obvious radiation damage; in the neutral salt spray test according to GB6458 standard, no corrosion was found on the coating surface after more than 2000 hours.

[0048] Embodiment 3:

[0049] Follow the steps below to prepare and apply the spray coating on the surface of spent fuel transport container for nuclear power:

[0050] S1: Add B4C ceramic powder to the activation solution and treat it with ultrasound at room temperature for 90 minutes; separate the activation solution after static sedimentation, and then wash the powder with deionized water for plating. Ni-Mo coated B4C powder was prepared by room temperature ultrasonic assisted chemical plating method. The pH value of the chemical plating solution was adjusted to 10 with NaOH, the powder loading was 10g / L, and ultrasonic assisted chemical plating was performed at room temperature for 120 minutes. After the chemical plating was completed, the powder was washed with deionized water and dried to obtain Ni-Mo coated B4C powder.

[0051] S2: Take 30 parts by weight of Ni-Mo coated B4C powder, 30 parts of FeB powder and 40 parts by weight of FeCr67C6.0 powder, stir them at high speed with a V-type powder mixer, and fill them into a U-shaped Ni-Cu (Monel 400) alloy strip with a purity of 99% and a certain shape. The filling rate is 40%, and then rolled and drawn to make a Φ2.0mm powder-core nickel-based wire.

[0052] S3: The NiCrB powder core wire was directly sprayed onto the surface of A350 LF3 steel for nuclear power spent fuel container by arc spraying method through a spray gun. The spraying process parameters were: voltage 30V; current 200A; spraying distance 150mm; compressed air pressure 0.5MPa, and a NiCrB primer layer with a thickness of 100μm was prepared.

[0053] S4: The powder-core nickel-based wire in S1 was sprayed onto the surface of A350 LF3 steel for nuclear power spent fuel container by an arc spraying method through a spray gun to form a NiCrB base layer. The spraying process parameters were: voltage 35V; current 220A; spraying distance 150mm; compressed air pressure 0.5MPa, and a nickel-based boron-containing composite coating with a thickness of 2000μm was prepared.

[0054] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application are characterized in that the components and concentrations of the chemical plating solution in S1 are respectively: NiSO4·6H2O 20g / L, Na2MoO4·2H2O 15g / L, Na3C6H5O7·2H2O 30g / L, CN2H4S 0.05g / L and N2H4·H2O (80%) 100mL / L.

[0055] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application are characterized in that the particle size range of the Ni-Mo coated B4C powder, FeB powder and FeCr67C6.0 powder in S2 is 40 μm, the high-speed stirring rate of the V-type powder mixer is 4000 rpm, and the stirring time is 120 min.

[0056] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application is characterized in that the composition of the NiCrB powder core wire in S3 is: Cr 20wt.%, B 5.0wt.%, O≤0.1wt.%, Ni balance. The outer skin is made of nickel strip, and the diameter of the final powder core wire is 2.0mm.

[0057] The steel grade used for nuclear power spent fuel containers is A350 LF3 steel.

[0058] The porosity of the nickel-based boron-containing composite coating sprayed in S3 and S4 was 1.9% according to the GB / T 13298-2015 standard, and the bonding strength with A350 LF3 steel after testing according to the GB / T 8642-2002 standard was 43 MPa.

[0059] The thermal neutron absorption performance of the nickel-based boron-containing composite coating prepared by arc spraying in S3 and S4 together with the steel plate as a whole is about 91%. 13 ~2.5×10 14 cm -2 After neutron irradiation with a certain amount of radiation, the material did not suffer obvious radiation damage; in the neutral salt spray test according to GB6458 standard, no corrosion was found on the coating surface after more than 2000 hours.

[0060] Comparative Example 1

[0061] Follow the steps below to prepare and apply the spray coating on the surface of spent fuel transport container for nuclear power:

[0062] S1: Add B4C ceramic powder to the activation solution and treat it with ultrasound at room temperature for 90 minutes; wash the powder with deionized water and dry it to obtain uncoated B4C powder.

[0063] S2: Take 50 parts by weight of uncoated B4C powder, 20 parts of FeB powder and 30 parts by weight of FeCr67C6.0 powder, stir them at high speed with a V-type powder mixer, and fill them into a U-shaped pure Ni strip with a purity of 99% with a certain shape. The filling rate is 45%, and then rolled and drawn to make a Φ2.0mm powder-core nickel-based wire.

[0064] S3: The powder-core nickel-based wire in S1 was directly sprayed onto the surface of A350 LF3 steel for nuclear power spent fuel containers by an arc spraying method through a spray gun. The spraying process parameters were: voltage 35V; current 220A; spraying distance 150mm; compressed air pressure 0.5MPa, and a nickel-based boron-containing composite coating with a thickness of 2000μm was prepared.

[0065] The above-mentioned method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application are characterized in that the particle size range of the B4C powder, FeB powder and FeCr67C6.0 powder in S2 is 40 μm, the high-speed stirring rate of the V-type powder mixer is 4000 rpm, and the stirring time is 120 min.

[0066] The steel grade used for nuclear power spent fuel containers is A350 LF3 steel.

[0067] The porosity of the nickel-based boron-containing composite coating sprayed in S3 was 5.7% according to GB / T 13298-2015 standard, and the bonding strength with A350 LF3 steel after testing according to GB / T 8642-2002 standard was 18 MPa, which was lower than that of Examples 1 to 3.

[0068] The thermal neutron absorption performance of the nickel-based boron-containing composite coating prepared by arc spraying in S3 and S4 together with the steel plate as a whole is about 77%, which is lower than that of Examples 1 to 3. 13 ~2.5×10 14 cm -2 After neutron irradiation with a certain amount of radiation, the material did not suffer obvious radiation damage; in the neutral salt spray test according to GB6458 standard, no corrosion was found on the coating surface after more than 2000 hours.

[0069] It can be seen from Examples 1-3 and Comparative Example 1 that the Ni-based boron-containing composite coating obtained by the coating preparation method of the spent fuel transport container for nuclear power of the present invention has a low loss of B element during the spraying process due to the Ni-Mo coated B4C powder in the Ni-based boron-containing composite coating of the present invention, and the AES test shows that the B element content on the surface of the coating is ≥40at.%; therefore, the arc-sprayed Ni-based boron-containing composite coating obtained by the present invention has a strong thermal neutron absorption capacity, wherein the neutron absorption cross section far exceeds that of ordinary boron-containing steel, and the thermal neutron absorption performance is not less than 90%; the high-speed stirring of the V-type powder mixer ensures that the particles of each component in the powder core wire can be evenly dispersed; the powder core wire obtained by rolling and drawing and the arc spraying method ensure the uniform distribution of each component in the A350 LF3 steel surface coating; the nickel-based powder core wire is made of a U-shaped Ni-Cu (Monel 400) alloy strip, and the Cu element contained therein helps to improve the conductivity of the wire, obtain better melting and atomization effects, and help to reduce the porosity of the coating obtained by spraying. Arc spraying NiCrB base layer and arc spraying Ni-based boron-containing composite coating surface layer greatly improved the bonding strength between the Ni-based composite coating and A350 LF3 steel and the density of the coating. Due to the use of arc spraying, the energy consumption and cost of spraying are greatly reduced, and the efficiency and safety of spraying are improved. And through the creative work of the inventor, NiCrB is sprayed as a base layer and the arc spraying parameters are set, so that the surface roughness is further increased, and the bonding strength between the Ni-based coating and the A350 LF3 steel is ensured; at the same time, the Ni-based coating has good high temperature resistance and corrosion resistance, and the introduction of a large amount of B element can improve the shielding effect of gamma radiation and neutron radiation. The arc-sprayed Ni-based boron-containing composite coating obtained by the present invention has a strong thermal neutron absorption capacity, and its neutron absorption cross-section far exceeds that of ordinary boron-containing steel, and the thermal neutron absorption performance is not less than 90%; therefore, the combination of A350 LF3 steel + arc-sprayed Ni-based boron-containing composite coating can achieve the purpose of radioactive shielding while meeting the structural strength requirements of the container, which is helpful to comprehensively improve the service life of spent fuel transport containers for nuclear power.

[0070] The above embodiments are only used to illustrate the present invention, rather than to limit the present invention. Those skilled in the relevant technical field may make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also belong to the scope of the present invention and should be defined by the claims.

Claims

1. A method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application, characterized in that: The preparation method and application include the following steps: S1: Add B4C ceramic powder to the activation solution and perform ultrasonic treatment at room temperature for 60 to 90 minutes; separate the activation solution after static sedimentation, and then wash the powder with deionized water for plating. Prepare Ni-Mo coated B4C powder by room temperature ultrasonic assisted chemical plating method, adjust the pH value of the chemical plating solution to 9 to 11 with NaOH, and the powder loading amount is 8 to 12 g / L. Perform ultrasonic assisted chemical plating at room temperature for 80 to 120 minutes. After the chemical plating is completed, wash the powder with deionized water and dry it to obtain Ni-Mo coated B4C powder. S2: Take 30-50 parts by weight of Ni-Mo coated B4C powder, 20-30 parts by weight of FeB powder and 20-50 parts by weight of FeCr67C6.0 powder, stir them at high speed with a V-type powder mixer, and fill them into a U-shaped Ni-Cu (Monel 400) alloy strip with a purity of 99% and a certain shape, with a filling rate of 30-50%, and then roll and draw them into Φ2.0-3.0mm powder core nickel-based wire. S3: The NiCrB powder core wire is directly sprayed onto the surface of A350LF3 steel for nuclear power spent fuel container by a spray gun using the arc spraying method. The spraying process parameters are: voltage 28-35V; current 180-220A; spraying distance 150-200mm; compressed air pressure 0.4-0.6MPa, and a NiCrB base layer with a thickness of 50-100μm is prepared. S4: The powder-core nickel-based wire in S1 was sprayed onto the surface of A350LF3 steel for nuclear power spent fuel container by a spray gun using arc spraying method to form NiCrB base layer. The spraying process parameters were: voltage 30-35V; current 200-250A; spraying distance 150-200mm; compressed air pressure 0.4-0.6MPa, and a nickel-based boron-containing composite coating with a thickness of 1000-2000μm was prepared.

2. The method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application as claimed in claim 1, characterized in that: The components and concentrations of the chemical plating solution in S1 are: NiSO4·6H2O 15-20 g / L, Na2MoO4·2H2O 10-15 g / L, Na3C6H5O7·2H2O 20-30 g / L, CN2H4S 0.02-0.10 g / L and N2H4·H2O (80%) 80-100 mL / L.

3. The method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application as claimed in claim 1, characterized in that: The particle size range of the Ni-Mo coated B4C powder, FeB powder and FeCr67C6.0 powder in the S2 is 20-60 μm, the high-speed stirring rate of the V-type powder mixer is 3000-5000 rpm, and the stirring time is 60-120 min.

4. The method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application as claimed in claim 1, characterized in that: The composition of the NiCrB powder core wire in S3 is: Cr 18-20wt.%, B 5.0-7.0wt.%, O≤0.1wt.%, Ni balance. The outer skin is made of nickel strip, and the diameter of the final powder core wire is 2.0-3.0mm.

5. The method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application as claimed in claim 1, characterized in that: The porosity of the nickel-based composite coating sprayed in S3 and S4 does not exceed 3%, and the bonding strength with A350 LF3 steel is not less than 35 MPa.

6. The method for preparing a surface spray coating of a spent fuel transport container for nuclear power and its application as claimed in claim 1, characterized in that: The thermal neutron absorption performance of the nickel-based boron-containing composite coating prepared by arc spraying in S3 and S4 together with the steel plate as a whole is not less than 90%.

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