An additive manufacturing method of depositing a material

Abstract

The present application relates to the technical field of nuclear reactor fuel and moderator, and provides an additive manufacturing method of deposition material, comprising the following steps: feeding the deposition material into a powder feeder; wherein the deposition material is metal powder and / or metal fuel powder; placing a substrate into a working box and fixing the substrate on a workbench, and maintaining the whole process in a protective atmosphere; adjusting the powder feeding rate of the powder feeder, starting the laser and starting the synchronous powder feeding, starting to deposit a first deposition layer with a thickness of 20-100 microns on the substrate; after forming the first deposition layer, completing hydrogenation of the first layer deposition layer, then starting the laser and starting the synchronous powder feeding by using the powder feeder, and depositing a fusion layer with a thickness of 20-100 microns on the first layer deposition layer; the additive manufacturing is carried out in a hydrogen atmosphere, the additive hydrogenation integrated process can be realized, large / complex hydride moderators and hydride fuels can be freely produced, and the hydrogen content of each layer of the moderator / fuel can be freely adjusted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear reactor fuel and moderator, in particular to a method for additive manufacturing of deposition materials. BACKGROUND

[0002] The design of new reactors requires higher volume power density, so the operating temperature needs to be increased to achieve higher heat transfer efficiency. At high temperatures, the coolant cannot continue to use water or heavy water with moderation ability, and high-temperature and high-heat-transfer-capacity coolants such as supercritical carbon dioxide, alkali metals sodium and potassium, lead bismuth, etc. are used. At this time, since the coolant cannot be used as a moderator, the reactor is designed as a fast neutron reactor in physics. The small fast neutron fission cross section leads to a large amount of uranium loading and a high requirement for the enrichment of uranium 235. In order to reduce the uranium loading of the reactor core, reduce the requirement for the enrichment of uranium 235, and improve the economy of new reactors, a moderator can be arranged in the reactor to slow down the fast neutrons, and the reactor can be designed as a thermal neutron or medium-energy neutron reactor. However, at high temperatures, traditional water or heavy water cannot be used as a moderator, and solid materials such as graphite, beryllium and beryllium oxide have a certain moderation ability and can be used as a moderator, but their moderation ability is weak and insufficient at high temperatures.

[0003] Hydride fuel is an ideal moderator and fuel form in the design of new reactors due to its good neutron moderation ability. However, it is difficult to prepare large blocks / complex shapes of hydride and hydride fuel by traditional hydrogenation and powder sintering, which limits the design of the reactor core and the use of space and weight of new reactors. SUMMARY

[0004] The present application aims to provide a method for additive manufacturing of deposition materials, which can realize an integrated process of additive hydrogenation by additive manufacturing in a hydrogen atmosphere, freely produce large / complex hydride moderators and hydride fuels, and freely adjust the hydrogen content of each layer of the moderator / fuel.

[0005] The embodiments of the present application are implemented by the following technical solutions:

[0006] A method for additive manufacturing of deposition materials, comprising the following steps:

[0007] S1. feeding the deposition material into the powder feeder cylinder; wherein the deposition material is metal powder and / or metal fuel powder, and if the deposition material is metal moderator powder and metal fuel powder, they are fed into different powder feeder cylinders of the powder feeder respectively;

[0008] S2. placing the substrate into the working box and fixing the substrate on the workbench, and maintaining the whole process in a protective atmosphere;

[0009] S3. Adjusting the powder feeding rate of the powder feeder, turning on the laser and starting the synchronous powder feeding, starting to deposit a first deposition layer with a thickness of 20-100 microns on the substrate;

[0010] S4. After forming the first deposition layer, after the first layer deposition layer is completed hydrogenation, turning on the laser and starting the synchronous powder feeding with the powder feeder, depositing a fusion layer with a thickness of 20-100 microns on the first layer deposition layer.

[0011] Further, the above steps are repeated several times until the required deposition material is formed.

[0012] Further, in S1, the diameters of the metal moderator powder and the metal fuel powder are both 50-500 microns.

[0013] Further, in S1, the metal moderator powder is one or more of zirconium powder, yttrium powder, zirconium-niobium alloy powder, yttrium-niobium alloy powder, zirconium hydride powder, and yttrium hydride powder.

[0014] Further, in S1, when the metal moderator powder is zirconium hydride powder or yttrium hydride powder, the hydrogen atom ratio is 33%-80%.

[0015] Further, in S1, the metal fuel powder is one or more of U powder, U-Zr alloy powder, and U-Y alloy powder.

[0016] Further, in S2, the protective atmosphere is hydrogen with a purity of 99% or more or high-purity argon-hydrogen mixed gas (hydrogen content ≥5%).

[0017] Further, in S3, the laser power of the laser is 150W-350W, the laser scanning speed is 800mm / s-1000mm / s, and the laser scanning pitch is 0.10-0.15mm; and the powder feeding amount of the powder feeder is 1.5-2g / min.

[0018] Further, in S4, the parameters of the laser and the powder feeder are consistent with those in S3.

[0019] The technical scheme of the embodiment of the application has at least the following advantages and beneficial effects:

[0020] The additive manufacturing method of the deposition material provided by the application can realize an additive hydrogenation integrated process by additive manufacturing in a hydrogen atmosphere, can freely produce large / complex hydride moderators and hydride fuels, can freely adjust the hydrogen content of each layer of moderator / fuel by controlling the manufacturing process, has strong operability, and is conducive to the core design, space, and weight utilization of new reactors. DETAILED DESCRIPTION

[0021] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. If specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturers are adopted. If the manufacturers of the reagents or instruments are not specified, the conventional products that can be purchased in the market are adopted.

[0022] The additive manufacturing method for depositing materials provided by the embodiments of the present application will be described in detail below.

[0023] An additive manufacturing method for depositing materials, comprising the following steps:

[0024] S1. feeding the depositing material into the powder feeding cylinder of the powder feeder; wherein the depositing material is metal moderator powder and / or metal fuel powder, and if the depositing material is metal moderator powder and metal fuel powder, they are respectively fed into different powder feeding cylinders of the powder feeder;

[0025] S2. placing the substrate into the working box and fixing the substrate on the workbench so that the position of the substrate does not change during the processing, and maintaining the substrate in a protective atmosphere with a purity of 99.99%-99.999% throughout the process; the gas concentration in the working box reaches 99.9-99.9999%, and the tail gas is discharged through the exhaust pipeline or ignited; by flushing with hydrogen or high-purity argon-hydrogen mixed gas, on the one hand, the protective gas effect is provided, and on the other hand, the hydrogen permeation effect is provided;

[0026] S3. adjusting the powder feeding rate of the powder feeder, starting the laser and starting the synchronous powder feeding, and starting to deposit a first deposition layer with a thickness of 20-100 μm on the substrate; during the deposition process, the metal powder will melt and then solidify to form a deposited structure, but in the hydrogen / argon-hydrogen atmosphere, the metal (Zr, Y, etc.) powder will start to permeate hydrogen to form hydride;

[0027] S4. after the first deposition layer is formed, waiting for 3 min, and after the first layer deposition layer completes the hydrogen permeation process, starting the laser and starting the synchronous powder feeding by the powder feeder to deposit a fusion layer with a thickness of 20-100 μm on the first layer deposition layer. When the hydrogen permeation time is reduced, the hydrogen content in the deposition layer will decrease, and when the hydrogen permeation time is prolonged, the hydrogen content in the deposition layer will increase, but as the time is prolonged, the hydrogen content increases to H:Zr>1.6, and the rate of hydrogen content increase decreases, therefore, under the hydrogen permeation process of 3 min, not only the excellent hydrogen permeation effect can be maintained, but also the deposition layer can be more stable, and the bonding force with the substrate can be greatly improved.

[0028] S5. repeating the above steps several times until the required depositing material is formed.

[0029] The additive manufacturing technology is used to prepare the hydride moderator and the hydride fuel, the additive hydrogenation and integration process can be realized by additive manufacturing in a hydrogen atmosphere, large / complex hydride moderators and hydride fuels can be freely produced, and the hydrogen content of each layer of the moderator / fuel can be freely adjusted by controlling the manufacturing process. Therefore, the additive manufacturing technology for preparing the hydride moderator and the hydride fuel has strong operability, and gives the hydride moderator and the hydride fuel more design ideas and expansion space. Therefore, the additive manufacturing method of the hydride moderator and the hydride fuel is provided, and the preparation of the hydride moderator and the hydride fuel can be realized.

[0030] Further, in S1, the diameters of the metal moderator powder and the metal fuel powder are 50-500 microns.

[0031] Further, in S1, the metal moderator powder is one or more of zirconium powder, yttrium powder, zirconium-niobium alloy powder, yttrium-niobium alloy powder, zirconium hydride powder ZrH2, yttrium hydride powder YH2, and YH3.

[0032] Further, in S1, when the metal moderator powder is zirconium hydride powder or yttrium hydride powder, the hydrogen atom ratio is 33%-80%.

[0033] Further, in S1, the metal fuel powder is hydride fuel containing fissile nuclides, such as uranium 235, plutonium 239, uranium 233, thorium 232, etc., and the enrichment of the fissile nuclides is 0.1%-99%; for example, it can be one or more of U powder, U-Zr alloy powder, and U-Y alloy powder.

[0034] In addition, it should be noted that the hydrogen atom ratio in the metal moderator and the metal fuel powder is 33%-80%.

[0035] Further, in S2, the protective atmosphere is hydrogen with a purity of more than 99% or high-purity argon-hydrogen mixed gas (hydrogen content ≥5%).

[0036] Further, in S3, the laser power of the laser is 150W-350W, the laser scanning speed is 800mm / s-1000mm / s, and the laser scanning interval is 0.10-0.15mm; the powder feeding amount of the powder feeder is 1.5-2g / min; in S4, the parameters of the laser and the powder feeder are consistent with those in S3.

[0037] Example 1

[0038] The embodiment provides an additive manufacturing method of a zirconium hydride moderator, comprising the following steps:

[0039] 1) Put the ZrH2 powder with a diameter of 50-500 microns into the powder feeding cylinder of the powder feeder;

[0040] 2) Place the zirconium alloy substrate in a work box filled with a protective atmosphere and fix the substrate on a workbench so that the position of the substrate does not change during the processing;

[0041] 3) High-purity hydrogen with a purity of 99.999% was injected into the protective atmosphere working box to make the gas concentration in the working box reach 99.9999%. The tail gas was discharged into the gas outlet and ignited. The substrate was heated by a thermocouple to a temperature of 500°C.

[0042] 4) Adjust the powder feeding rate of the powder feeder, turn on the laser and start synchronous powder feeding, and start depositing the first deposition layer with a thickness of 50 μm on the substrate. The parameters are laser power 250 W, laser scanning speed 900 mm / s, laser scanning spacing 0.10 mm, and powder feeding rate 2 g / min. At this time, the deposited layer is a Zr structure;

[0043] 5) After forming the first deposition layer, wait for 3 minutes until the hydrogen permeation process of the deposition layer is completed, then turn on the laser flow and start synchronous powder feeding to deposit a 50μm thick deposition layer on the previous layer;

[0044] 6) Repeat the above steps until the desired hydride is formed.

[0045] In this embodiment, the deviation of the hydrogen-zirconium atomic ratio of the additively manufactured zirconium hydride sample along the deposition direction is 1.6±0.15.

[0046] Below, we will use a layer height of 50μm as an example to estimate the time required to complete hydrogen permeation of each layer when additively manufacturing ZrH2.

[0047] According to experimental experience, when hydrogenating a 1mm zirconium alloy sheet, it often takes 20 hours to keep the hydrogen absorption of the zirconium alloy constant. According to the second law of diffusion, the time required for the same degree of diffusion is proportional to the square of the distance. Therefore, it only takes 3 minutes to hydrogenate a layer height of 50μm. Therefore, from the above derivation process, the extremely thin thickness of additive manufacturing actually speeds up the hydrogen permeation process. The laser additive manufacturing process is generally 1-5mm / s, and the spot diameter is also 3-4mm. Considering the overlap rate of 70%, the manufacturing speed of the laser additive manufacturing process is about 2-15mm 2 / s. From this rate, it can be seen that the laser scanning can cover 3.6cm in 3 minutes. 2 The cross section of the component must be larger than 3.6cm 2 , the hydrogen permeation process can be completed synchronously during the additive process without the need for additional waiting process.

[0048] Example 2

[0049] An additive manufacturing method of hydride moderator and hydride fuel, comprising the following steps

[0050] 1) Put ZrH2 powder with a diameter of 50-500 microns into a powder feeding cylinder;

[0051] 2) Put the substrate into an atmosphere protection workbox and fix the substrate on the atmosphere protection workbench so that the position of the substrate does not change during the processing;

[0052] 3) Inject high-purity hydrogen with a purity of 99.999% into the atmosphere protection workbox, so that the gas concentration in the atmosphere protection workbox reaches 99.9999%, exhaust the tail gas into the gas outlet, ignite it, and use a thermocouple to heat the substrate to a temperature of 550°C;

[0053] 4) Adjust the powder feeding rate of the powder feeder, turn on the laser and start synchronous powder feeding, start depositing a first deposition layer with a thickness of 40 microns on the substrate, the laser power is 200 W, the laser scanning speed is 8,50 mm / s, the laser scanning interval is 0.15 mm, and the powder feeding amount is 1.5 g / min, at this time the deposition layer is Zr organization;

[0054] 5) After forming the first deposition layer, wait for 2 min, and after the layer deposition layer completes the hydrogenation process, turn on the laser flow and start synchronous powder feeding to deposit a fusion layer with a thickness of 50 microns on the previous layer;

[0055] 6) Repeat the above steps until the required hydride is formed.

[0056] In this embodiment, the manufactured zirconium hydride has a hydrogen zirconium atomic ratio deviation of 1.45±0.15 along the deposition direction.

[0057] Example 3

[0058] An additive manufacturing method of hydride moderator and hydride fuel, comprising the following steps

[0059] 1) Put YHx powder with a diameter of 50-500 microns into a powder feeding cylinder, 2.5>x>2.3;

[0060] 2) Put the substrate into an atmosphere protection workbox and fix the substrate on the atmosphere protection workbench so that the position of the substrate does not change during the processing;

[0061] 3) Inject high-purity hydrogen with a purity of 99.999% into the atmosphere protection workbox, so that the gas concentration in the atmosphere protection workbox reaches 99.9999%, exhaust the tail gas into the gas outlet, ignite it, and use a thermocouple to heat the substrate to a temperature of 600°C;

[0062] 4) Adjust the powder feeding rate of the powder feeder, turn on the laser and start the synchronous powder feeding, start depositing the first deposited layer with a thickness of 50 μm on the substrate, the parameters of the laser power 300 W, the laser scanning speed 1000 mm / s, the laser scanning pitch 0.15 mm, the powder feeding amount 1.8 g / min, at this time the deposited layer is Y structure;

[0063] 5) After forming the first deposited layer, wait for 3 min, and then turn on the laser flow and start the synchronous powder feeding to deposit the fused layer with a thickness of 50 μm on the previous layer;

[0064] 6) Repeat the above steps until the required hydride is formed.

[0065] In this embodiment, the deviation of the atomic ratio of yttrium hydride to zirconium in the additive manufactured yttrium hydride sample along the deposition direction is 1.7±0.15.

[0066] The above only is the preferred embodiment of the present application, and is not used to limit the present application, for the person skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method of additive manufacturing of a deposited material, characterized in that, The method comprises the following steps: S1. feeding the deposition material into the powder feeding cylinder of the powder feeder; wherein the deposition material is metal moderator powder and / or metal fuel powder; the metal moderator powder is one or more of zirconium powder, yttrium powder, zirconium-niobium alloy powder, yttrium-niobium alloy powder, zirconium hydride powder, and yttrium hydride powder; the metal fuel powder is one or more of uranium powder, uranium-zirconium alloy powder, and uranium-yttrium alloy powder; S2. placing the substrate into the working box and fixing the substrate on the workbench, and maintaining the whole process in a protective atmosphere; the protective atmosphere is hydrogen gas with a purity of 99% or more or high-purity argon-hydrogen mixed gas; S3. adjusting the powder feeding rate of the powder feeder, turning on the laser and starting synchronous powder feeding, and starting to deposit a first deposition layer with a thickness of 20-100 μm on the substrate; S4. after forming the first deposition layer, starting synchronous powder feeding by turning on the laser and using the powder feeder to deposit a fusion layer with a thickness of 20-100 μm on the first deposition layer after the first deposition layer is completed hydrogenation; the hydrogen atom ratio in the first deposition layer and the fusion layer is 33%-80%; S5: repeat the above steps several times until the required metal moderator powder and / or metal fuel powder is formed.

2. The additive manufacturing method of depositing a material according to claim 1, wherein, In S1, the diameter of the metal moderator powder and the metal fuel powder is 50-500 microns.

3. The additive manufacturing method of the deposition material according to claim 1, in S3, the laser power of the laser is 150 W-350 W, the laser scanning speed is 800 mm / s-1000 mm / s, and the laser scanning pitch is 0.10-0.15 mm; the powder feeding amount of the powder feeder is 1.5-2 g / min.

4. The additive manufacturing method of the deposition material according to claim 1, in S4, the working parameters of the laser and the powder feeder are consistent with those in S3.