Additive manufacturing method of deposition material

Abstract

The invention relates to the technical field of nuclear reactor fuel and moderator, and provides an additive manufacturing method of a deposition material, which comprises the following steps: feeding the deposition material into a powder feeder; wherein the deposition material is metal powder and / or metal fuel powder; putting the substrate into a working box, fixing the substrate on a working table, and maintaining the substrate in a protective atmosphere in the whole process; the powder feeding rate of a powder feeder is adjusted, a laser is started, synchronous powder feeding is started, and a first deposition layer with the thickness ranging from 20 micrometers to 100 micrometers is deposited on the base material; after the first deposition layer is formed and hydrogen permeation of the first deposition layer is completed, a laser is started, synchronous powder feeding is started through a powder feeder, and a fused deposition layer with the thickness of 20-100 microns is deposited on the first deposition layer; additive manufacturing is carried out under the hydrogen atmosphere, the additive hydrogen permeation integrated process can be achieved, the large / complex hydride moderator and hydride fuel can be freely produced, and the hydrogen content of each layer of moderator / fuel can be freely adjusted.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear reactor fuel and moderator, and in particular to an additive manufacturing method for deposition materials. Background Art

[0002] The design of the new reactor requires a higher volume power density, so it is required to increase the operating temperature to achieve a higher heat transfer efficiency. At high temperatures, the coolant can no longer use water or heavy water with moderation ability, but uses coolants with higher applicable temperatures and stronger heat transfer capabilities, such as supercritical carbon dioxide, alkali metal sodium, potassium, lead bismuth, etc. At this time, since the coolant cannot be used as a moderator, the reactor is physically designed as a fast neutron reactor. The fast neutron fission cross section is small, resulting in a large uranium load and a high enrichment requirement for uranium 235. In order to reduce the core uranium load, reduce the uranium 235 enrichment requirement, and improve the economy of the new reactor, a moderator can be arranged in the reactor to moderate the fast neutrons, and the reactor can be designed as a thermal neutron or medium energy neutron reactor. However, traditional water or heavy water cannot be used as a moderator at high temperatures. Solid materials such as graphite, beryllium and beryllium oxide have certain moderation capabilities and can be used as moderators, but their moderation capabilities are weak and insufficient at high temperatures.

[0003] Hydride fuel is an ideal moderator and fuel form in new reactor designs due to its good neutron moderation ability. However, the traditional hydrogenation and powder sintering methods are difficult to prepare large blocks / complex shapes of hydrides and hydride fuels, which limits the core design and space and weight utilization of new reactors. Summary of the invention

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

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

[0006] An additive manufacturing method for depositing material, comprising the following steps:

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

[0008] S2. Place the substrate into the work box and fix the substrate on the workbench, and maintain it in a protective atmosphere throughout the process;

[0009] S3. Adjust the powder feeding rate of the powder feeder, turn on the laser and start synchronous powder feeding, and start depositing a first deposition layer with a thickness of 20-100 μm on the substrate;

[0010] S4. After forming the first deposition layer, the first deposition layer is hydrogenated, and then the laser is turned on and the powder feeder is used to start synchronous powder feeding to deposit a molten layer with a thickness of 20-100 μm on the first deposition layer.

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

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

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

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

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

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

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

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

[0019] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

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

[0021] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0022] The following is a detailed description of an additive manufacturing method for a deposition material provided by an embodiment of the present invention.

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

[0024] S1. Feeding the deposition material into the powder feeding tube of the powder feeder; wherein the deposition material is metal moderator powder and / or metal fuel powder. If the deposition material is metal moderator powder and metal fuel powder, they are respectively fed into different powder feeding tubes of the powder feeder;

[0025] S2. Place the substrate into the work box and fix the substrate on the workbench so that the position of the substrate does not change during the processing and is maintained in a protective atmosphere with a purity of 99.99%-99.999% throughout the process; make the gas concentration in the work box reach 99.9-99.9999%, and the tail gas is discharged or ignited through the exhaust pipe; by flushing in hydrogen or high-purity argon-hydrogen mixed gas, on the one hand, it provides a protective gas effect, and on the other hand, it plays a hydrogen permeation role;

[0026] S3. 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 20-100 μm on the substrate; during the deposition process, the metal powder will melt and then re-solidify to form a deposited structure, but in the hydrogen / argon hydrogen atmosphere, the metal (Zr, Y, etc.) powder will begin to permeate hydrogen to form hydrides;

[0027] S4. After forming the first deposition layer, wait for 3 minutes, and after the first deposition layer completes the hydrogenation process, turn on the laser and use the powder feeder to start synchronous powder feeding to deposit a 20-100μm thick molten layer on the first deposition layer. When the hydrogenation time is reduced, the hydrogen content in the deposition layer will decrease, and when the hydrogenation time is extended, the hydrogen content in the deposition layer will increase. However, as time goes by, after the hydrogen content increases to H:Zr>1.6, the rate of increase of the hydrogen content decreases. Therefore, maintaining a 3-minute hydrogenation process can not only maintain an excellent hydrogenation effect, but also make the deposition layer more stable and greatly improve the bonding strength with the substrate.

[0028] S5. Repeat the above steps several times until the required deposition material is formed.

[0029] The present invention prepares hydride moderators and hydride fuels through additive manufacturing technology, and by performing additive manufacturing in a hydrogen atmosphere, an integrated process of additive hydrogenation can be realized, and large / complex hydride moderators and hydride fuels can be freely produced, and the hydrogen content of each layer of moderator / fuel can be freely adjusted by controlling the manufacturing process. Therefore, the preparation of hydride moderators and hydride fuels through additive manufacturing technology has strong operability, giving hydride moderators and hydride fuels greater ideas and expansion space for design. Therefore, the present invention proposes an additive manufacturing method for hydride moderators and hydride fuels, which can realize the preparation of hydride moderators and hydride fuels.

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

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

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

[0033] Furthermore, in S1, the metal fuel powder is a 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% to 99%; for example, it can be one or more of U powder, U-Zr alloy powder, and UY alloy powder.

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

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

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

[0037] Example 1

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

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

[0040] 2) placing the zirconium alloy substrate into a working box filled with a protective atmosphere and fixing the substrate on a working table so that the position of the substrate does not change during the processing;

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

[0042] 4) The powder feeding rate of the powder feeder was adjusted, the laser was turned on and the powder feeding was started synchronously, and the first deposition layer with a thickness of 50 μm was deposited on the substrate. The parameters were as follows: the laser power was 250 W, the laser scanning speed was 900 mm / s, the laser scanning spacing was 0.10 mm, and the powder feeding amount was 2 g / min. At this time, the deposition layer was a Zr structure.

[0043] 5) After forming the first deposition layer, wait for 3 minutes until the deposition layer completes the hydrogen permeation process, then turn on the laser flow, start synchronous powder feeding, and deposit a 50 μm 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 take a layer height of 50μm as an example to estimate the time required to complete the 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 hydrogenation 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 greater than 3.6 cm 2 , the hydrogen permeation process can be completed synchronously during the additive process without the need for an additional waiting process.

[0048] Example 2

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

[0050] 1) Place ZrH2 powder with a diameter of 50-500 microns into the powder feeding tube;

[0051] 2) Place the substrate into the atmosphere protection work box and fix the substrate on the atmosphere protection work table so that the position of the substrate does not change during the processing;

[0052] 3) High-purity hydrogen with a purity of 99.999% is flushed into the protective atmosphere working box to make the gas concentration in the atmosphere protective working box reach 99.9999%, the tail gas is discharged into the gas outlet, and it is ignited, and the substrate is heated by a thermocouple to make its temperature reach 550°C;

[0053] 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 40 μm on the substrate. The parameters are as follows: laser power 200 W, laser scanning speed 8,50 mm / s, laser scanning spacing, 0.15 mm, and powder feeding amount 1.5 g / min. At this time, the deposition layer is a Zr structure;

[0054] 5) After forming the first deposition layer, wait for 2 minutes until the deposition layer completes the hydrogen permeation process, then turn on the laser flow, start synchronous powder feeding, and deposit a 50 μm thick deposition layer on the previous layer;

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

[0056] In this embodiment, the deviation of the hydrogen-zirconium atomic ratio of the additively manufactured zirconium hydride sample along the deposition direction is 1.45±0.15.

[0057] Example 3

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

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

[0060] 2) Place the substrate into the atmosphere protection work box and fix the substrate on the atmosphere protection work table so that the position of the substrate does not change during the processing;

[0061] 3) High-purity hydrogen with a purity of 99.999% is flushed into the protective atmosphere working box to make the gas concentration in the atmosphere protective working box reach 99.9999%, the tail gas is discharged into the gas outlet, and it is ignited, and the substrate is heated by a thermocouple to make its temperature reach 600°C;

[0062] 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 as follows: the laser power is 300 W, the laser scanning speed is 1000 mm / s, the laser scanning spacing is 0.15 mm, and the powder feeding amount is 1.8 g / min. At this time, the deposition layer is a Y structure;

[0063] 5) After forming the first deposition layer, wait for 3 minutes until the deposition layer completes the hydrogen permeation process, then turn on the laser flow, start synchronous powder feeding, and deposit a 50 μm thick deposition layer on the previous layer;

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

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

[0066] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for additive manufacturing of deposited materials, characterized in that: The following steps are involved: S1. Feeding the deposition material into the powder feeding tube of the powder feeder; wherein the deposition material is metal moderator powder and / or metal fuel powder; S2. Place the substrate into the work box and fix the substrate on the workbench, and maintain it in a protective atmosphere throughout the process; S3. Adjust the powder feeding rate of the powder feeder, turn on the laser and start synchronous powder feeding, and start depositing a first deposition layer with a thickness of 20-100 μm on the substrate; S4. After forming the first deposition layer, the first deposition layer is hydrogenated, and then the laser is turned on and the powder feeder is used to start synchronous powder feeding to deposit a molten layer with a thickness of 20-100 μm on the first deposition layer.

2. The additive manufacturing method of the deposition material according to claim 1, characterized in that: In S1, the diameters of the metal moderator powder and the metal fuel powder are both 50-500 microns.

3. According to the additive manufacturing method of deposition material according to claim 2, in S1, the metal moderator powder is one or more of zirconium powder, yttrium powder, zirconium-niobium alloy powder, yttrium-niobium alloy powder, zirconium powder hydride powder, and yttrium powder hydride powder.

4. The additive manufacturing method of deposition materials according to claim 2, wherein in S1, the metal fuel powder is one or more of U powder, U-Zr alloy powder, and UY alloy powder. 5 . The additive manufacturing method of the deposition material according to claim 1 , wherein the hydrogen atomic ratio in the first deposition layer and the deposition layer is 33%-80%.

6. The additive manufacturing method of deposition material according to claim 1, wherein in S2, the protective atmosphere is hydrogen gas with a purity of more than 99% or a high-purity argon-hydrogen mixed gas.

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

8. According to the additive manufacturing method of deposition materials according to claim 1, in S4, the operating parameters of the laser and the powder feeder are consistent with those in S3.

9. The additive manufacturing method of deposition material according to claim 1 further comprises step S5: repeating the above steps several times until the required metal moderator powder and / or metal fuel powder is formed.