A method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method and the composite materials.

Abstract

The application belongs to the technical field of neutron shielding materials, and relates to a method for preparing GdB2C2 / Al composite material based on in-situ reaction of molten salt method and the composite material, the method comprising the following steps: S1, mixing B4C powder and graphite powder to obtain mixed powder, mixing the mixed powder and carbonate molten salt to obtain premix, heating the premix to complete melting at a heating temperature of 900-1200 DEG C to obtain a first reaction melt; S2, adding aluminum gadolinium alloy to the first reaction melt to perform first reaction at a constant temperature of 900-1200 DEG C to obtain a second reaction melt, and then adding pure aluminum to the second reaction melt to perform second reaction to obtain a third reaction melt; S3, removing the slag on the surface of the third reaction melt, and casting into a mold to form the GdB2C2 / Al composite material. The composite material has high neutron absorption efficiency and good mechanical properties, and is suitable for the fields of nuclear fuel storage and nuclear radiation protection.

Description

Technical Field

[0001] This invention belongs to the field of neutron shielding materials technology, and relates to a method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method, and the composite materials themselves. Background Technology

[0002] With the widespread application of nuclear energy, the demand for high-efficiency neutron shielding materials for spent fuel storage and transportation containers and storage racks is constantly increasing. An ideal neutron shielding material not only needs a high neutron absorption cross-section but also excellent mechanical properties and low density to meet the safety and reliability requirements of nuclear equipment under long-term service conditions. Existing aluminum-based neutron shielding materials are mainly represented by B4C / Al composite materials, which are relatively mature in industrial applications. However, the composite material only possesses good neutron shielding capability when the B4C content reaches 30% or more, which often leads to a significant reduction in its plasticity and toughness, thus limiting its engineering applications. Furthermore, traditional B4C / Al composite materials are mostly prepared through powder metallurgy, a method that is energy-intensive, has limited output, and a long production cycle, hindering large-scale applications.

[0003] In contrast, using an in-situ reactive melting-casting process to prepare aluminum-based neutron shielding composites can significantly improve production efficiency, reduce energy consumption and preparation cycle, and achieve a tight bond between the reinforcing phase and the matrix, further improving the overall performance of the material. However, the solubility of B4C and graphite (C) in molten aluminum is extremely low, making it difficult to fully react with Gd in Al-Gd alloys, thus limiting the in-situ formation of the highly efficient neutron-absorbing phase GdB2C2. To solve this problem, if a molten salt method can be introduced to improve the reactivity of B4C and C, promoting the dissolution and diffusion of B and C, and then allowing them to react in-situ with Gd, it is hoped that a one-step rapid synthesis of the GdB2C2 ceramic phase can be achieved in an aluminum matrix. This not only provides a feasible new approach for the preparation of highly efficient neutron shielding composites but also provides important support for the safety assurance of nuclear energy equipment. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method. This method solves the problems of low solubility and insufficient reaction of B4C and C in molten aluminum, and generates a uniformly distributed GdB2C2 ceramic phase in situ within the aluminum matrix.

[0005] One objective of this invention is achieved through the following technical solution:

[0006] A method for preparing GdB2C2 / Al composite materials based on molten salt in-situ reaction, the method comprising the following steps:

[0007] S1. Mix B4C powder with graphite powder to obtain a mixed powder, mix the mixed powder with carbonate molten salt to obtain a premix, and heat the premix at a heating temperature of 900~1200℃ until it is completely melted to obtain the first reaction melt.

[0008] S2. At a constant temperature of 900~1200℃, aluminum-gadolinium alloy is added to the first reaction melt to carry out the first reaction and obtain the second reaction melt. Then, pure aluminum is added to the second reaction melt to carry out the second reaction and obtain the third reaction melt.

[0009] S3. Remove the slag from the surface of the third reaction melt and cast it into a mold to obtain the GdB2C2 / Al composite material.

[0010] Preferably, in step S1, the carbonate molten salt includes at least two of sodium carbonate, potassium carbonate, and calcium carbonate.

[0011] More preferably, the carbonate molten salt is sodium carbonate and potassium carbonate in a mass ratio of 1:(0.1~10).

[0012] More preferably, the carbonate molten salt is sodium carbonate and potassium carbonate in a mass ratio of 1:1.

[0013] Preferably, in step S1, the mass ratio of B4C powder to graphite powder is 1:(0.5~3).

[0014] Further optimization yields a B4C powder to graphite powder mass ratio of 1:(1~2).

[0015] Preferably, in step S1, the mass ratio of the mixed powder to the carbonate molten salt is 1:(2~5).

[0016] Further optimization yields a mass ratio of 1:3 for the mixed powder and the carbonate molten salt.

[0017] Preferably, in step S1, the heating temperature of the premix is ​​900~1000℃.

[0018] Preferably, in step S1, during the heating process, the mixture is stirred for 1 to 5 minutes at a speed of 60 to 120 r / min every 10 to 20 minutes.

[0019] Preferably, in step S2, the mass ratio of the first reaction melt to the aluminum-gadox alloy Al-Gd is 1:(1~10).

[0020] Further optimization is that the mass ratio of the first reaction melt to the aluminum-gadolinium alloy is 1:(1~5).

[0021] Preferably, in step S2, the mass ratio of the second reaction melt to pure aluminum is 1:(0.1~1).

[0022] Further optimization is that the mass ratio of the second reaction melt to pure aluminum is 1:(0.6~1).

[0023] Preferably, in step S2, the amount of aluminum-gadolinium alloy Al-Gd added to the third reaction melt is 20~45wt%, and the amount of pure aluminum added to the third reaction melt is 35~60wt%.

[0024] Further optimization is that the amount of aluminum-gadolinium alloy Al-Gd added in the third reaction melt is 20~40wt%, and the amount of pure aluminum added in the third reaction melt is 42~49wt%.

[0025] Preferably, in step S2, the molar ratio of Gd, B, and C elements in the third reaction melt is 1:2:2.

[0026] Preferably, in step S2, both the first and second reaction processes are mechanically stirred.

[0027] Further optimization involves stirring with a graphite stirring rod at a speed of 60-120 r / min for 1-5 minutes every 1-30 minutes during the first and second reaction processes.

[0028] Preferably, in step S2, the first reaction is followed by heat preservation for 10-60 minutes; the second reaction is followed by heat preservation for 30-300 minutes.

[0029] In a further preferred embodiment, the total heat preservation time in step S2 is 1 to 4 hours.

[0030] Preferably, in step S2, the pure aluminum is pure aluminum ingot, and the content of impurity elements in the pure aluminum ingot is 0.01~0.4wt% by mass percentage, with the remainder being Al; the impurity elements include one or more of Si, Fe, and Cu.

[0031] In a further preferred embodiment, in step S2, the pure aluminum is pure aluminum ingot, and the content of impurity elements in the pure aluminum ingot is 0.1~0.2wt% by mass percentage, with the remainder being Al; the impurity elements include one or more of Si, Fe, and Cu.

[0032] Preferably, in step S2, the content of Gd in the aluminum-gadolinium alloy is 1~60wt% by mass percentage, with the remainder being Al.

[0033] Further optimization shows that, by mass percentage, the content of Gd in the aluminum-gadolinium alloy is 30-50 wt%, with the remainder being Al.

[0034] Preferably, the constant temperature in step S2 is 1000~1200℃.

[0035] Preferably, the constant temperature in step S2 is greater than or equal to the heating temperature in step S1.

[0036] More preferably, the constant temperature in step S2 is greater than the heating temperature in step S1.

[0037] Preferably, in step S3, the casting mold is made of steel or graphite.

[0038] Preferably, the method further includes post-processing, which includes: extrusion forming and / or rolling deformation;

[0039] The extrusion ratio used in the extrusion molding process is greater than 10:1;

[0040] The deformation during rolling is greater than 30%.

[0041] Further preferably, the GdB2C2 / Al composite material undergoes post-processing, which includes: sequential extrusion molding and rolling deformation.

[0042] More preferably, the GdB2C2 / Al composite material is extruded into an extruded sheet at an extrusion ratio of (16~25):1; the extruded sheet is then rolled and deformed by a deformation amount of 40~60%.

[0043] Preferably, the GdB2C2 / Al composite material is an aluminum-based composite material containing GdB2C2 particles, with the volume percentage of GdB2C2 being 0.1~15 vol.

[0044] The second objective of this invention is achieved through the following technical solution:

[0045] A GdB2C2 / Al composite material prepared by the above method, wherein the volume percentage of GdB2C2 is 0.1~15 vol.

[0046] Preferably, the mass percentage of GdB2C2 in the GdB2C2 / Al composite material is 1~10wt%.

[0047] Further preferably, the mass percentage of GdB2C2 in the GdB2C2 / Al composite material is 5 wt%.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] 1. This invention introduces a molten salt system to obtain a B4C-C molten salt system, which significantly improves the reactivity of B4C and C and effectively overcomes their low solubility in molten aluminum.

[0050] 2. In this invention, aluminum and Al-Gd alloy are gradually added to the B4C-C molten salt system, and the GdB2C2 ceramic phase is generated in situ and uniformly distributed in the aluminum matrix. The structure is stable, with high neutron absorption efficiency and good mechanical properties, and it is suitable for nuclear fuel storage and nuclear radiation protection.

[0051] 3. The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method of the present invention is simple and controllable, suitable for large-scale industrial production, and reduces production costs. Attached Figure Description

[0052] Figure 1 This is a microstructure diagram of the GdB2C2 / Al composite material in Example 1 of the present invention.

[0053] Figure 2 This is an energy dispersive spectroscopy (EDS) analysis result of region A of the GdB2C2 / Al composite material in Example 1 of the present invention. Detailed Implementation

[0054] The technical solution of the present invention will be further described and illustrated below through specific embodiments. It should be understood that the specific embodiments described herein are only for the purpose of helping to understand the present invention and are not intended to limit the present invention.

[0055] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used in the art, and the methods used in the embodiments are all conventional methods in the art.

[0056] In this article, the raw materials include:

[0057] Pure aluminum: Hebei Luohong Technology Co., Ltd., pure aluminum ingots with a purity of 99.8%, and the total weight ratio of other impurity elements such as Si, Fe, and Cu does not exceed 0.2%;

[0058] Al-Gd alloys: Hebei Luohong Technology Co., Ltd., Al-30Gd, Al-50Gd;

[0059] B4C powder: Zhongbo Technology (Weihai) Co., Ltd., ultrafine B4C powder, average particle size 1 μm.

[0060] Graphite powder: Qinhuangdao Yinuo High-tech Materials Development Co., Ltd., 99% pure graphite powder, average particle size 1 μm;

[0061] Refining agent: Shenzhen Ruibao Industrial Co., Ltd., RJ-1 type refining agent.

[0062] The tests in this article include:

[0063] Yield strength, tensile strength, and elongation were tested according to ASTM E8 / E8M-15a standard;

[0064] The neutron shielding efficiency was tested under the conditions of neutron energy of 0.025 eV and material thickness of 30 mm.

[0065] The volume fraction (vol%) of the GdB2C2 phase in the GdB2C2 / Al composite material was obtained by binarized image analysis.

[0066] Example 1

[0067] The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method in this embodiment includes the following steps:

[0068] S1. Weigh 19.8g Na2CO3 and 19.8g K2CO3 as carbonate molten salt; weigh 7.1g B4C and 6.1g graphite powder and mix them to obtain a mixed powder; mix the mixed powder with the carbonate molten salt (mass ratio of 1:3) to obtain a premix; grind and stir the premix thoroughly and place it in an alumina crucible lined with dense boron nitride; place the crucible in a high-temperature furnace and heat it to a heating temperature of 900℃ until it is completely melted to obtain the first reaction melt (B4C-C molten salt system).

[0069] S2. Maintaining a constant temperature of 1000℃, add 133.0g of aluminum-gadolinium alloy Al-30Gd to the first reaction melt to carry out the first reaction and hold for 20min, allowing Gd to react with B and C elements to generate the GdB2C2 precursor, thus obtaining the second reaction melt; add 155.3g of pure aluminum to the second reaction melt to carry out the second reaction and hold for 60min; stir with a graphite rod at 80r / min for 2min every 20min to obtain the third reaction melt;

[0070] S3. Remove the slag from the surface of the third reaction melt using a slag scraper, and cast it into a graphite mold to obtain the GdB2C2 / Al composite material.

[0071] In this embodiment, the theoretical volume fraction of the GdB2C2 reinforcing phase in the GdB2C2 / Al composite material is 8.0 vol.%, and the actual volume fraction is 7.8 vol.%.

[0072] Figure 1 The image shows the microstructure of the GdB2C2 / Al composite material prepared in this embodiment. Figure 2 The energy dispersive spectroscopy (EDS) analysis results for region A of this microstructure indicate that the GdB2C2 phase was successfully formed in this region.

[0073] The properties of the GdB2C2 / Al composite material in this embodiment are shown in Table 1.

[0074] Example 2

[0075] The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method in this embodiment includes the following steps:

[0076] S1. Weigh 19.8g Na2CO3 and 19.8g K2CO3 as carbonate molten salt; weigh 7.1g B4C and 6.1g graphite powder and mix them to obtain a mixed powder; mix the mixed powder with the carbonate molten salt (mass ratio of 1:3) to obtain a premix; grind and stir the premix thoroughly and place it in an alumina crucible lined with dense boron nitride; place the crucible in a high-temperature furnace and heat it to a heating temperature of 1000℃ until it is completely melted to obtain the first reaction melt (B4C-C molten salt system).

[0077] S2. Maintaining a constant temperature of 1000℃, add 133.0g of aluminum-gadolinium alloy Al-30Gd to the first reaction melt to carry out the first reaction and hold for 20min, allowing Gd to react with B and C elements to generate the GdB2C2 precursor, thus obtaining the second reaction melt; add 155.3g of pure aluminum to the second reaction melt to carry out the second reaction and hold for 60min; stir with a graphite rod at 80r / min for 2min every 20min to obtain the third reaction melt;

[0078] S3. Remove the slag from the surface of the third reaction melt using a slag scraper, and cast it into a graphite mold to obtain the GdB2C2 / Al composite material.

[0079] In this embodiment, the theoretical volume fraction of the GdB2C2 reinforcing phase in the GdB2C2 / Al composite material is 8.0 vol.%, and the actual volume fraction is 7.9 vol.%.

[0080] The properties of the GdB2C2 / Al composite material in this embodiment are shown in Table 1.

[0081] Example 3

[0082] The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method in this embodiment includes the following steps:

[0083] S1. Weigh 19.8g Na2CO3 and 19.8g K2CO3 as carbonate molten salt; weigh 7.0g B4C and 4.57g graphite powder and mix them to obtain a mixed powder; mix the mixed powder with the carbonate molten salt (mass ratio of 1:3) to obtain a premix; grind and stir the premix thoroughly and place it in an alumina crucible lined with dense boron nitride; place the crucible in a high-temperature furnace and heat it to a heating temperature of 900℃ until it is completely melted to obtain the first reaction melt (B4C-C molten salt system).

[0084] S2. Maintaining a constant temperature of 900℃, add 133.0g of aluminum-gadolinium alloy Al-50Gd to the first reaction melt to carry out the first reaction and hold for 20min, allowing Gd to react with B and C elements to generate the GdB2C2 precursor, thus obtaining the second reaction melt; add 208.51g of pure aluminum to the second reaction melt to carry out the second reaction and hold for 60min; stir with a graphite rod at 80r / min for 2min every 20min to obtain the third reaction melt;

[0085] S3. Remove the slag from the surface of the third reaction melt using a slag scraper, and cast it into a graphite mold to obtain the GdB2C2 / Al composite material.

[0086] In this embodiment, the theoretical volume fraction of the GdB2C2 reinforcing phase in the GdB2C2 / Al composite material is 8.0 vol.%, and the actual volume fraction is 7.7 vol.%.

[0087] The properties of the GdB2C2 / Al composite material in this embodiment are shown in Table 1.

[0088] Example 4

[0089] The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method in this embodiment includes the following steps:

[0090] The GdB2C2 / Al composite material of Example 1 was post-processed: it was extruded into sheet using a vertical hydraulic press in Rugao, Nantong, with an extrusion ratio of 25:1; and then hot-rolled into sheet using a double-roll mill in Guancheng, Wuxi, with a final deformation of 40%.

[0091] The properties of the GdB2C2 / Al composite material (plate) in this embodiment are shown in Table 1.

[0092] Comparative Example 1

[0093] The comparative example uses a melting and casting method to prepare GdB2C2 / Al composite materials, which includes the following steps:

[0094] The raw materials were prepared according to the proportions in Example 1; B4C powder and graphite powder were mixed and then wrapped in aluminum foil and pressed into preforms by a hydraulic press; pure aluminum was smelted at 900°C, and after complete melting, Al-30Gd alloy was added to react. The preforms were then placed 50 mm below the liquid surface through a bell jar to react. After holding at 900°C for 2 hours, a refining agent was added, stirred, and the slag was removed. Finally, the mixture was cast into a mold to obtain the GdB2C2 / Al composite material.

[0095] The properties of the GdB2C2 / Al composite material in this comparative example are shown in Table 1.

[0096] Comparative Example 2

[0097] The method for preparing GdB2C2 / Al composite materials using powder metallurgy in this comparative example includes the following steps:

[0098] S1. Weigh 44.67 g of Gd2O3 powder, 6.83 g of B4C powder, and 4.42 g of graphite powder, add anhydrous ethanol, and wet ball mill at 300 rpm for 12 h in a ball mill jar. After ball milling, remove the slurry and dry it in an 80℃ vacuum drying oven until no solvent residue remains. Place the dried powder into a graphite crucible and react at 1800℃ for 4 h under an argon atmosphere to obtain GdB2C2 bulk product. After grinding and sieving, obtain GdB2C2 powder.

[0099] S2. The above GdB2C2 powder and 241.38 g of pure aluminum powder were placed in a ball mill jar and ball milled at 200 rpm for 4 hours. Then the mixed powder was sieved and loaded into a graphite mold. It was then hot-pressed and sintered in a hot-pressing sintering furnace at 50 MPa and 580℃ to obtain the GdB2C2 / Al composite material.

[0100] The properties of the GdB2C2 / Al composite material in this comparative example are shown in Table 1.

[0101] Comparative Example 3

[0102] The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt in this comparative example includes the following steps:

[0103] S1. Proceed according to step S1 of Example 1;

[0104] S2. Proceed according to step S2 of Example 1, except that pure aluminum is added first, followed by Al-30Gd;

[0105] S3. Proceed according to step S3 of Example 1 to obtain the GdB2C2 / Al composite material.

[0106] The properties of the GdB2C2 / Al composite material in this comparative example are shown in Table 1.

[0107] Comparative Example 4

[0108] The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt in this comparative example includes the following steps:

[0109] S1. Proceed according to step S1 of Example 1, except that the heating temperature is 1500℃;

[0110] S2. Proceed according to step S2 of Example 1, except that the constant temperature is 1500℃.

[0111] S3. Proceed according to step S3 of Example 1 to obtain the GdB2C2 / Al composite material.

[0112] The properties of the GdB2C2 / Al composite material in this comparative example are shown in Table 1.

[0113] Comparative Example 5

[0114] The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt in this comparative example includes the following steps:

[0115] S1. Proceed according to step S1 of Example 1, except that the heating temperature is 800°C;

[0116] S2. Follow step S2 of Example 1, except that the constant temperature is 800°C.

[0117] S3. Proceed according to step S3 of Example 1 to obtain the GdB2C2 / Al composite material.

[0118] The properties of the GdB2C2 / Al composite material in this comparative example are shown in Table 1.

[0119] Comparative Example 6

[0120] The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt in this comparative example includes the following steps:

[0121] S1. Proceed according to step S1 of Example 1;

[0122] S2. Perform step S2 of Example 1, except that the constant temperature is 1300℃.

[0123] S3. Proceed according to step S3 of Example 1 to obtain the GdB2C2 / Al composite material.

[0124] The properties of the GdB2C2 / Al composite material in this comparative example are shown in Table 1.

[0125] Comparative Example 7

[0126] The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt in this comparative example includes the following steps:

[0127] S1. Proceed according to step S1 of Example 1, except that the heating temperature is 1300°C;

[0128] S2. Proceed according to step S2 of Example 1;

[0129] S3. Proceed according to step S3 of Example 1 to obtain the GdB2C2 / Al composite material.

[0130] The properties of the GdB2C2 / Al composite material in this comparative example are shown in Table 1.

[0131] Comparative Example 8

[0132] The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt in this comparative example includes the following steps:

[0133] S1. Proceed according to step S1 of Example 1, except that the molten salt is 19.8 g NaCl and 19.8 g KCl;

[0134] S2. Proceed according to step S2 of Example 1;

[0135] S3. Proceed according to step S3 of Example 1 to obtain the GdB2C2 / Al composite material.

[0136] The properties of the GdB2C2 / Al composite material in this comparative example are shown in Table 1.

[0137]

[0138] As shown in the table above, the method of preparing GdB2C2 / Al composite material based on molten salt in-situ reaction of the present invention can obtain GdB2C2 / Al composite material with both excellent mechanical properties and neutron shielding properties.

[0139] Example 1 of this invention uses molten salt-assisted in-situ reaction to prepare GdB2C2 / Al composite materials. The entire process takes about 3 hours and consumes about 18 kWh of electricity, demonstrating high efficiency and low energy consumption. In contrast, the powder metallurgy process used in Comparative Example 2 takes more than 18 hours and consumes over 65 kWh of electricity; moreover, due to poor interfacial bonding, the mechanical properties of the prepared composite material are significantly reduced. In Example 4, the molten salt in-situ reaction combined with extrusion and rolling post-treatment allows for sufficient dynamic recrystallization and dislocation strengthening of the composite material during subsequent deformation, while further improving the dispersion of the reinforcing phase. Therefore, its mechanical properties are significantly improved compared to Examples 1-3, and the neutron shielding performance is also enhanced. Comparative Example 1 uses a conventional melting and casting method without introducing a molten salt system, resulting in insufficient reactivity between B4C and graphite. The actual GdB2C2 content generated is significantly lower than the nominal value, ultimately resulting in poor mechanical and shielding properties. In Comparative Example 3, the addition of pure aluminum followed by the Al-Gd master alloy hindered the contact and reaction between gadolinium and boron and carbon, resulting in insufficient GdB2C2 formation and a significant performance degradation. In Comparative Example 4, both the heating and holding temperatures were far above the optimal range, causing the loss of boron and carbon in the molten salt and gadolinium in the aluminum melt, leading to a decrease in GdB2C2 content and subsequent performance deterioration. In Comparative Example 5, the excessively low heating and holding temperatures resulted in insufficient reactivity of boron, carbon, and gadolinium, also leading to low GdB2C2 formation and performance degradation. Comparative Examples 6 and 7, due to excessively high holding and heating temperatures respectively, caused the loss of gadolinium or boron and carbon, both resulting in insufficient reinforcing phase content and performance degradation. Comparative Example 8 uses a chloride salt system. Since a single chloride salt is difficult to provide effective chemical activation, its wetting and dispersion effects on B4C are limited. It is also prone to side reactions with aluminum and introduces pores and impurities, ultimately resulting in a low GdB2C2 content and significantly weakened mechanical properties and neutron shielding performance.

[0140] In summary, this invention introduces a carbonate molten salt system to obtain a B4C-C molten salt system, which significantly improves the reactivity of B4C and C and effectively overcomes their low solubility in molten aluminum. Subsequently, aluminum and Al-Gd alloy are gradually added, and the GdB2C2 ceramic phase is generated in situ and uniformly distributed in the aluminum matrix. The structure is stable, with high neutron absorption efficiency and good mechanical properties, making it suitable for nuclear fuel storage and nuclear radiation protection.

[0141] All aspects, embodiments, and features of this invention should be considered illustrative in all respects and not limiting of the invention; the scope of the invention is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0142] In the preparation method of this invention, the order of the steps is not limited to the listed order. For those skilled in the art, variations in the order of the steps without creative effort are also within the scope of protection of this invention. Furthermore, two or more steps or actions can be performed simultaneously.

[0143] Finally, it should be noted that the specific embodiments described herein are merely illustrative examples of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them; it is neither necessary nor possible to exemplify all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the invention still fall within the scope of protection of the invention, and interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method, characterized in that, The method includes the following steps: S1. Mix B4C powder with graphite powder to obtain a mixed powder, mix the mixed powder with carbonate molten salt to obtain a premix, and heat the premix at a heating temperature of 900~1200℃ until it is completely melted to obtain the first reaction melt. S2. At a constant temperature of 900~1200℃, aluminum-gadolinium alloy is added to the first reaction melt to carry out the first reaction and obtain the second reaction melt. Then, pure aluminum is added to the second reaction melt to carry out the second reaction and obtain the third reaction melt. S3. Remove the slag from the surface of the third reaction melt and cast it into a mold to obtain the GdB2C2 / Al composite material; Wherein, the constant temperature in step S2 is greater than or equal to the heating temperature in step S1; In step S1, the mass ratio of B4C powder to graphite powder is 1:(0.5~3). In step S1, the mass ratio of the mixed powder to the carbonate molten salt is 1:(2~5). In step S2, the mass ratio of the first reaction melt to the aluminum-gadolinium alloy Al-Gd is 1:(1~10). In step S2, the mass ratio of the second reaction melt to pure aluminum is 1:(0.1~1). In step S2, the first reaction process is mechanically stirred, and the temperature is maintained for 10-60 minutes after the first reaction; the second reaction process is mechanically stirred, and the temperature is maintained for 30-300 minutes after the second reaction.

2. The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method according to claim 1, characterized in that, In step S1, the carbonate molten salt includes at least two of sodium carbonate, potassium carbonate, and calcium carbonate.

3. The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method according to claim 1, characterized in that, In step S1, the heating temperature of the premix is ​​900~1000℃.

4. The method for preparing GdB2C2 / Al composite materials based on in-situ reaction using molten salt method according to claim 1, characterized in that, The method further includes post-processing, which includes: extrusion forming and / or rolling deformation; The extrusion ratio used in the extrusion molding process is greater than 10:1; The deformation during rolling is greater than 30%.

5. A GdB2C2 / Al composite material, characterized in that, It is prepared by the method for preparing GdB2C2 / Al composite material based on in-situ reaction of molten salt method as described in any one of claims 1 to 4.

6. The GdB2C2 / Al composite material according to claim 5, characterized in that, The volume percentage of GdB2C2 in the GdB2C2 / Al composite material is 0.1~15 vol.

Images