A composite deuterium storage coating for neutron emission tubes and its preparation method

Abstract

The present invention provides a composite deuterium storage coating material for neutron emission tubes and a preparation method thereof. By using a chemical vapor deposition method, a metal transition layer is deposited on the surface of a substrate to further enhance the bonding strength between the coating and the substrate. A metal deuteride thin film is deposited and prepared on the surface of the metal transition layer. By controlling the percentage of deuterium gas introduced during sputtering, the deuterium storage amount in the deposited coating is regulated. On the premise of meeting higher deuterium storage density and good thermal stability, the hydrogen embrittlement resistance and deuterium storage performance of the coating are improved. Finally, a protective layer is deposited on the surface of the deuterium storage thin film to enhance the oxidation resistance and anti-carbonization performance of the deuterium storage composite thin film.

Description

Technical Field

[0001] The present invention relates to the technical field of neutron generation, and particularly relates to a composite deuterium storage coating material for a neutron emission tube and a preparation method thereof. Background Art

[0002] A neutron emission tube is a small accelerator neutron source, which seals an ion source, a target and a gas pressure regulating system in a ceramic tube to form an electro-vacuum device with a simple and compact structure and convenient use. As a key component of a neutron emission tube and a neutron generator, the deuterium target is required to have a high deuterium storage capacity. Since the neutron tube is bombarded by a large beam of deuterium ions during operation, the surface temperature of the target film rises, and the target film is also required to have high thermal stability. In addition, the bonding strength, hydrogen embrittlement resistance and oxidation resistance of the target film are all key factors affecting the quality of the deuterium target.

[0003] Most neutron sources of domestic and foreign neutron emission tubes and neutron generators use metals such as molybdenum, tungsten, and copper as substrates, and elements such as titanium, zirconium, and scandium are plated on the surface as deuterium absorption thin film materials. Research shows that titanium, as one of the metal materials with the highest hydrogen absorption density at present, has the characteristics of low price, simple titanium film preparation process, and deuterium absorption stability. It is generally used as the deuterium absorption film material for the deuterium target of neutron tubes and neutron generators. It can absorb high-concentration deuterium and hydrogen isotope tritium, and at the same time can form a thin film on the metal substrate. An appropriate titanium layer thickness can ensure that its surface temperature is low enough to keep the total amount of activity in the target unchanged. However, pure titanium film as a deuterium absorption thin film also has some defects: 1. The titanium film is extremely easy to be contaminated by elements such as O and C, and a carbide or oxide film layer is formed on the surface, thus affecting the deuterium absorption and desorption performance of the thin film; 2. After pure titanium film absorbs hydrogen, a unique hydrogen embrittlement phenomenon will occur, which deteriorates the mechanical properties of the material, resulting in powdering or falling off of the whole target film, causing high-voltage breakdown of the neutron tube; 3. The pure titanium film cannot reach a high deuterium-titanium ratio, and the neutron yield is low. For example, Huang WC et al. disclosed a method for preparing a Mg / Nb hydrogen storage composite thin film by magnetron co-sputtering. Its subsequent hydrogen absorption process needs to be completed at a higher temperature and hydrogen partial pressure. Although it can store hydrogen, it does not solve the problems of hydrogen embrittlement powdering and low hydrogen absorption rate. In the invention of CN106544628A, a method for preparing a deuterium-containing metal thin film is proposed. High-purity deuterium gas is introduced during the sputtering deposition process to directly form a deuterium-containing metal thin film, which can effectively avoid problems such as hydrogen embrittlement and powder falling of pure metal thin films during deuterium absorption, but it fails to solve the problem that the surface of the deuterium storage thin film is easily oxidized, which affects the neutron yield. Summary of the Invention

[0004] The object of the present invention is to provide a composite deuterium storage coating material for neutron emission tubes and a preparation method thereof. By using the reactive magnetron sputtering method, a metal transition layer is deposited on the surface of the substrate to further enhance the bonding strength between the coating and the substrate. A metal deuteride film is deposited on the surface of the metal transition layer, and the deuterium storage amount in the deposited coating is regulated by controlling the percentage of deuterium gas introduced during the sputtering process. On the premise of meeting a relatively high deuterium storage density and good thermal stability, the hydrogen embrittlement resistance and deuterium storage performance of the coating are improved. Finally, a protective layer is deposited on the surface of the deuterium storage film to enhance the antioxidant and anti-carbonization properties of the deuterium storage composite film.

[0005] To solve the above technical problems, the present invention provides a composite deuterium storage coating material for neutron emission tubes, which comprises a metal transition layer, MD x a deuterium storage layer and a protective layer.

[0006] The present invention also provides a neutron emission tube, which comprises a substrate, a metal transition layer, MD x a deuterium storage layer and a protective layer sequentially attached to the substrate.

[0007] Among them, the substrate is made of a metal with a high thermal conductivity coefficient.

[0008] Among them, M in the MDx is one or more alloys of Mg, Ti, Ni, La, Co, Zr, Hf, Al.

[0009] Among them, the MD x The x value in the deuterium storage layer refers to the atomic ratio of deuterium to titanium, which is 0.5 to 2.5.

[0010] Among them, the total thickness of the metal transition layer, MD x the deuterium storage layer and the protective layer does not exceed 30 μm.

[0011] Among them, the thickness of the metal transition layer does not exceed 5.0 μm.

[0012] Among them, the MD x The thickness of the deuterium storage layer does not exceed 20 μm.

[0013] Among them, the surface protective layer is palladium or a palladium alloy, and the thickness is 0.1 to 5.0 μm.

[0014] The present invention also provides a preparation method for the above-mentioned composite deuterium storage coating material for neutron emission tubes, which comprises:

[0015] In the first step, the surface of the substrate is polished to a roughness Ra < 0.8 μm, and after ultrasonic cleaning and drying, a substrate material sample with a smooth and flat surface is obtained;

[0016] In the second step, a metal transition layer is deposited on the surface of the substrate by physical vapor deposition.

[0017] In the third step, an MDx deuterium storage coating is deposited on the metal transition layer by physical vapor deposition;

[0018] In the fourth step, a protective layer is deposited on the MDx deuterium storage coating by physical vapor deposition.

[0019] The physical vapor deposition method is physical vapor deposition.

[0020] The physical vapor deposition method can be selected from electron beam evaporation coating, magnetron sputtering coating, arc plasma coating, ion coating, molecular beam epitaxy coating, etc.

[0021] Advantages of the present invention

[0022] (1) The composite deuterium storage coating for neutron emission tubes of the present invention is composed of a metal transition inner layer, an MDx deuterium storage coating, and a protective outer layer. The inner layer is a metal transition layer. Since the film grains formed by sputtering are relatively dense and have a good bonding force with the substrate, it can make the relatively loose TiDx layer have a good connection with the substrate. In addition, the metal layer can also absorb the deuterium gas that has not fully reacted during the deposition process; the MDx deuterium storage coating has the advantages of controllable composition, low equilibrium pressure, and high deuterium storage capacity; in addition, the outer protective layer can effectively avoid the problem of reduced neutron yield caused by the oxidation and carbonization of the deuterium storage layer. (2) The preparation method of the MDx coating for deuterium storage of neutron emission tubes provided by the present invention is a physical vapor deposition process. The preparation method of the present invention is simple and reliable, can store deuterium in the form of a metal compound, and the prepared thin film has a small thickness, light weight and good bonding force with the substrate.

[0023] The composite coating composed of the metal transition inner layer, MDx deuterium storage coating, and protective outer layer of the present invention is prepared on the surface of the metal structural material. The deuterium storage amount in the deposited coating is regulated by the percentage of deuterium gas introduced during physical vapor deposition. On the premise of meeting higher deuterium storage density and good thermal stability, the bonding strength between the coating and the substrate is further enhanced, and the hydrogen embrittlement resistance and oxidation resistance of the coating are improved. The composite coating is arranged in sequence by a structural material substrate, a metal transition layer, an MDx deuterium storage layer, and a protective layer. The composite coating is prepared by physical vapor deposition, and the total thickness of the coating does not exceed 30 μm. The coating preparation process is simple, the cost is low, and it stores deuterium in the form of a metal compound, having the advantages of good air stability, low equilibrium pressure, and high deuterium storage capacity. Under the high-temperature test at 600 °C, its deuterium storage amount can reach 7.9 wt%. Brief description of the drawings

[0024] Figure 1 It is a structural layout diagram of the TiDx composite deuterium storage coating for neutron emission tubes of the present invention;

[0025] Figure 2 It is a cross-sectional SEM diagram of the TiDx composite deuterium storage coating for neutron emission tubes of the present invention;

[0026] Figure 3 This is the XRD pattern of the TiDx composite deuterium storage coating for the neutron emission tube of the present invention. Detailed implementation manners

[0027] The present invention provides a composite deuterium storage coating material for a neutron emission tube, which includes a metal transition layer, an MD x deuterium storage layer and a protective layer.

[0028] The present invention also provides a neutron emission tube, which includes a substrate, a metal transition layer, an MD x deuterium storage layer and a protective layer successively attached to the substrate.

[0029] The substrate is made of a metal with a high thermal conductivity coefficient, preferably one or more composites of oxygen-free copper, red copper, tungsten, and stainless steel.

[0030] The metal transition layer is an alloy of one or more of Mg, Ti, Ni, La, Co, Zr, Hf, and Al.

[0031] In MDx, M is an alloy of one or more of Mg, Ti, Ni, La, Co, Zr, Hf, and Al, preferably Ti.

[0032] The MD x The x value in the deuterium storage layer refers to the atomic ratio of deuterium to titanium, preferably 0.5 - 2.5.

[0033] The total thickness of the metal transition layer, the MD x deuterium storage layer and the protective layer does not exceed 30 μm, more preferably 0.3 - 30 μm.

[0034] The thickness of the metal transition layer does not exceed 5.0 μm, more preferably 0.1 - 5.0 μm.

[0035] The MD x The thickness of the deuterium storage layer does not exceed 20 μm, more preferably 0.1 - 20 μm.

[0036] The surface protective layer is further, the surface protective layer is palladium or a palladium alloy, and the thickness is 0.1 - 5.0 μm.

[0037] The present invention also provides a preparation method of the above-mentioned composite deuterium storage coating material for a neutron emission tube, which includes:

[0038] In the first step, the surface of the substrate is polished to a roughness Ra < 0.8 μm, and after ultrasonic cleaning and drying, a substrate material sample with a smooth and flat surface is obtained;

[0039] In the second step, a metal transition layer is deposited and prepared on the surface of the substrate by a vapor deposition method;

[0040] In the third step, an MDx deuterium storage coating is deposited on the metal transition layer by a vapor deposition method;

[0041] In the fourth step, a protective layer is deposited on the MDx deuterium storage coating by a vapor deposition method.

[0042] The vapor deposition method is a physical vapor deposition method.

[0043] The physical vapor deposition method can be selected from electron beam evaporation coating, magnetron sputtering coating, arc plasma coating, ion coating, molecular beam epitaxy coating, etc.

[0044] The following uses examples and drawings to detail the implementation manner of the present invention, so as to fully understand how the present invention uses technical means to solve technical problems and achieve the implementation process of technical effects and implement accordingly.

[0045] Example 1

[0046] A preparation method of a composite deuterium storage coating for a neutron emission tube, comprising the following steps:

[0047] (1) Select oxygen-free copper as the substrate material, polish one side of the substrate material to a roughness of 0.1 - 2.0 μm, and perform sputtering using a pure titanium (Ti) target with a diameter of 100 mm;

[0048] (2) Use a mechanical pump and a molecular pump to evacuate the magnetron sputtering chamber in sequence until the vacuum degree reaches 2.0×10 -4 Pa;

[0049] (3) Introduce the working gas Ar gas, control the intake flow rate to be 20 sccm, adjust the sputtering gas pressure to 0.8 Pa, the sputtering power to 200 W, and the target-substrate distance to 80 mm. After 20 minutes of sputtering deposition, a pure Ti transition layer with a thickness of 0.2 μm is obtained;

[0050] (4) Use a pure titanium (Ti) target with a diameter of 100 mm to deposit and prepare a TiD x deuterium storage coating on the pure Ti transition layer by reactive radio frequency sputtering;

[0051] (5) Introduce a mixed gas of the working gas Ar gas and the reactive gas D2, where Ar:D2 = 20:1 sccm. Adjust the coating deposition pressure to 0.8 Pa, the sputtering power to 200 W, and the target-substrate distance to 80 mm. After 2 hours of reactive radio frequency magnetron sputtering deposition, a 1.0 μm thick TiD x deuterium storage coating is prepared.

[0052] (6) Use a pure palladium (Pd) target with a diameter of 100 mm to deposit and prepare a Pd protective coating on the TiD x deuterium storage coating by radio frequency sputtering;

[0053] (7) Introduce the working gas Ar, control the inlet gas flow rate to be 20 sccm, adjust the sputtering gas pressure to 0.8 Pa, the sputtering power to 150 W, and the target-substrate distance to 80 mm. After 30 minutes of sputtering deposition, a pure Pd protective layer with a thickness of 0.2 μm is obtained, and finally a Ti / TiD x / Pd deuterium storage composite coating with a structure layout diagram as shown in Figure 1 is obtained.

[0054] Test the titanium-deuterium ratio and deuterium storage capacity of the composite coating prepared in Example 1. The test results show that the bonding strength between the coating and the substrate is 23 N, and the bonding strength is good. And for the TiD x deuterium storage coating, the titanium-deuterium ratio is Ti:D = 1:1, and the total deuterium storage capacity is about 4.3 wt%.

[0055] Example 2

[0056] A preparation method of a composite deuterium storage coating for neutron emission tubes, comprising the following steps:

[0057] (1) Select oxygen-free copper as the substrate material, polish one side of the substrate material to a roughness of 0.1 - 2.0 μm, and use a pure titanium (Ti) target with a diameter of 100 mm for sputtering;

[0058] (2) Use a mechanical pump and a molecular pump to evacuate the magnetron sputtering chamber in sequence until the vacuum degree reaches 2.0×10 -4 Pa;

[0059] (3) Introduce the working gas Ar, control the inlet gas flow rate to be 20 sccm, adjust the sputtering gas pressure to 0.8 Pa, the sputtering power to 200 W, and the target-substrate distance to 80 mm. After 20 minutes of sputtering deposition, a pure Ti transition layer with a thickness of 0.2 μm is obtained;

[0060] (4) Use a pure titanium (Ti) target with a diameter of 100 mm to deposit and prepare a TiD x deuterium storage coating on the pure Ti transition layer by reactive radio frequency sputtering method;

[0061] (5) Introduce a mixed gas of the working gas Ar and the reactive gas D2, where Ar:D2 = 20:5 sccm, adjust the coating deposition pressure to 0.8 Pa, the sputtering power to 200 W, and the target-substrate distance to 80 mm. After 2 hours of reactive radio frequency magnetron sputtering deposition, a 1.1 μm thick TiD x deuterium storage coating is prepared.

[0062] (6) Use a pure palladium (Pd) target with a diameter of 100 mm to deposit and prepare a Pd protective coating on the TiD x deuterium storage coating by radio frequency sputtering method;

[0063] (7) Introduce working gas Ar, control the inlet gas flow rate to be 20 sccm, adjust the sputtering gas pressure to 0.8 Pa, the sputtering power to 150 W, and the target-substrate distance to 80 mm. After 20 minutes of sputtering deposition, a pure Pd protective layer with a thickness of 0.2 μm is obtained, and finally a Ti / TiD x / Pd deuterium storage composite coating with a thickness of 1.5 μm is obtained, and its structural layout diagram is shown in Figure 1.

[0064] For the composite coating prepared in Example 2, the titanium-deuterium ratio and deuterium storage capacity are tested. The test results show that the bonding strength between the coating and the substrate is 22 N, the bonding strength is good, and the titanium-deuterium ratio of the TiD x deuterium storage coating is Ti:D = 1:1.5, and the total deuterium storage capacity is about 5.7 wt%.

[0065] Example 3

[0066] A preparation method of a composite deuterium storage coating for a neutron emission tube, comprising the following steps:

[0067] (1) Select oxygen-free copper as the substrate material, polish one side of the substrate material to a roughness of 0.1 - 2.0 μm, and use a pure magnesium (Mg) target with a diameter of 100 mm for sputtering;

[0068] (2) Use a mechanical pump and a molecular pump to evacuate the magnetron sputtering chamber in sequence until the vacuum degree reaches 2.0×10 -4 Pa;

[0069] (3) Introduce working gas Ar, control the inlet gas flow rate to be 20 sccm, adjust the sputtering gas pressure to 0.8 Pa, the sputtering power to 200 W, and the target-substrate distance to 80 mm. After 1 hour of sputtering deposition, a pure Ti transition layer with a thickness of 0.8 μm is obtained;

[0070] (4) Use a pure magnesium (Mg) target with a diameter of 100 mm to deposit and prepare a MgD x deuterium storage coating on the pure Mg transition layer by reactive radio frequency sputtering method;

[0071] (5) Introduce a mixed gas of working gas Ar and reactive gas D2, where Ar:D2 = 20:8 sccm, adjust the coating deposition pressure to 0.8 Pa, the sputtering power to 200 W, and the target-substrate distance to 80 mm. After 6 hours of reactive radio frequency magnetron sputtering deposition, a 4.2-μm-thick MgD x deuterium storage coating is prepared.

[0072] (6) Use a palladium-copper alloy target with a diameter of 100 mm to deposit and prepare a PdCu alloy protective coating on the MgD x deuterium storage coating by radio frequency sputtering method;

[0073] (7) Introduce the working gas Ar, control the inlet gas flow rate to be 20 sccm, adjust the sputtering gas pressure to 0.8 Pa, the sputtering power to 150 W, and the target-substrate distance to 80 mm. After 20 minutes of sputtering deposition, a PdCu alloy protective layer with a thickness of 0.3 μm is obtained, and finally a Mg / MgD x / PdCu deuterium storage composite coating with a thickness of 5.3 μm is obtained, and its structural layout diagram is shown in Figure 1.

[0074] Test the magnesium-deuterium ratio and deuterium storage capacity of the composite coating prepared in Example 3. The test results show that the bonding force between the coating and the substrate is 26 N, the bonding force is good, and MgD x The metal-deuterium ratio of the deuterium storage coating is Mg:D = 1:2.0, and the total deuterium storage capacity is about 7.9 wt%.

[0075] Example 4

[0076] A preparation method of a composite deuterium storage coating for a neutron emission tube, comprising the following steps:

[0077] (1) Select oxygen-free copper as the substrate material, polish one side of the substrate material to a roughness of 0.1 - 2.0 μm, and ultrasonically clean it with acetone, ethanol, and deionized water in sequence, and then set it aside;

[0078] (2) Use a mechanical pump and a molecular pump to evacuate the evaporation coating chamber in sequence until the vacuum degree reaches 2.0×10 -4 Pa;

[0079] (3) Use pure Ti particles with a particle size of 3 - 5 mm as the evaporation source to deposit and prepare a pure Ti transition layer on the substrate.

[0080] (4) Place the substrate in the center of the sample stage, and adjust the distance d between the center of the substrate and the tungsten boat to be 12 - 18 cm. Turn on the electron beam power supply, slowly adjust the electron beam current to 70 mA, open the baffle for evaporation deposition coating, and obtain a pure Ti transition layer with a thickness of 0.15 μm after 20 minutes of evaporation deposition;

[0081] (5) Use pure Ti particles with a particle size of 3 - 5 mm as the evaporation source to deposit and prepare a TiD x deuterium storage coating on the pure Ti transition layer by reactive evaporation coating method;

[0082] (6) Introduce the reaction gas D2, control the flow rate of deuterium gas to be 10 sccm. Turn on the electron beam power supply, slowly adjust the electron beam current to 70 mA, open the baffle for evaporation deposition coating, and obtain a TiD x deuterium storage coating with a thickness of 0.5 μm after 60 minutes of reactive evaporation deposition;

[0083] (7) Use pure Pd particles with a particle size of 3 - 5 mm as the evaporation source on TiDx Deposit a Pd protective coating on the deuterium storage coating by evaporation coating method;

[0084] (8) Turn on the electron beam power supply, slowly adjust the electron beam current to 80 mA, open the baffle for evaporation deposition coating, and obtain a 0.2-μm-thick pure Pd transition layer after 20 min of evaporation deposition. Finally, obtain a Ti / TiD x / Pd deuterium storage composite coating, and its structural layout diagram is shown in Figure 1.

[0085] Test the titanium-deuterium ratio and deuterium storage capacity of the composite coating prepared in Example 4. The test results show that the bonding strength between the coating and the substrate is 16 N, the bonding strength is good, and the TiD x The titanium-deuterium ratio of the composite deuterium storage coating is Ti:D = 1:1.7, and the total deuterium storage capacity is about 5.5 wt%.

[0086] Implementing this intellectual property right in all the above ways does not set restrictions on other forms of implementing this new product and / or new method. Those skilled in the art will use this important information to modify the above content to achieve similar implementation situations. However, all modifications or adaptations based on the new product of the present invention are within the reserved rights.

[0087] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A composite deuterium storage coating material for neutron emission tubes, characterized in that: It includes a metal transition layer, MD x a deuterium storage layer and a protective layer; the total thickness of the metal transition layer, MD x the deuterium storage layer and the protective layer does not exceed 30 μm; the thickness of the metal transition layer does not exceed 5.0 μm; The MD x wherein M in x is one or more alloys of Mg, Ti, Ni, La, Co, Zr, Hf, Al; the MD x The value of x in the deuterium storage layer represents the atomic ratio of deuterium to titanium, which is 0.5 - 2.

5.

2. The composite deuterium storage coating material for neutron emission tubes according to claim 1, wherein: The MD mentioned above x The thickness of the deuterium storage layer does not exceed 20 μm.

3. The composite deuterium storage coating material for neutron emission tubes according to claim 1, characterized in that: The protective layer is palladium or a palladium alloy, and the thickness is 0.1 - 5.0 μm.

4. A preparation method of a composite deuterium storage coating material for a neutron emission tube according to any one of claims 1 to 3, characterized in that, It includes: First step: Polish the surface of the substrate to a roughness Ra < 0.8 μm, ultrasonically clean and dry it to obtain a substrate material sample with a smooth and flat surface. Second step: Deposit and prepare a metal transition layer on the surface of the substrate by a vapor deposition method. Third step: Deposit and prepare an MDx deuterium storage coating on the metal transition layer by a vapor deposition method. Step 4, on the MD x Deposit and prepare a protective layer on the deuterium storage coating by chemical vapor deposition method.

5. A neutron emission tube, characterized in that, It includes: Substrate, a metal transition layer of the composite deuterium storage coating material for neutron emission tubes as described in claim 1 successively attached to the substrate, MD x Deuterium storage layer and protective layer.

6. The neutron emission tube according to claim 5, wherein: The substrate is made of a metal with a high thermal conductivity.

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