Anti-ionizing radiation powder with core-shell heterogeneous gradient structure as well as preparation method and application of anti-ionizing radiation powder

Abstract

The invention provides anti-ionizing radiation powder with a core-shell heterogeneous gradient structure and a preparation method and application of the anti-ionizing radiation powder, and belongs to the field of radiation protection.The preparation method of the anti-ionizing radiation powder with the core-shell heterogeneous gradient structure comprises the following steps that high-atomic-number metal salt is added into deionized water, aging, washing, drying and primary calcination are conducted in sequence, and the anti-ionizing radiation powder with the core-shell heterogeneous gradient structure is obtained; a core layer is obtained; the core layer and low-atomic-number metal salt are added into deionized water, aging, washing, drying and primary calcination are sequentially conducted, and preliminary wrapping powder with the high-atomic-number metal core layer wrapped by low-atomic-number metal is obtained; and adding the preliminarily wrapped powder and rare earth salt into deionized water, and sequentially performing aging, washing, drying, primary calcining, secondary calcining, airflow crushing and air rotation purging to obtain the anti-ionizing radiation powder with the core-shell heterogeneous gradient structure. Through cooperation of the core-shell heterostructure, the high-atomic-number oxide, the low-atomic-number oxide and the multi-element rare earth element, the shielding performance of the material is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of radiation protection technology, and in particular to a core-shell heterogeneous gradient structure ionizing radiation protection powder and a preparation method and application thereof. Background Art

[0002] With the rapid development of nuclear technology, the demand for radiation protection materials is growing. While traditional radiation protection materials (such as lead plates and concrete) offer some shielding effectiveness against gamma rays and X-rays, lead-based materials have an extremely high density (11.34 g / cm³), making protective equipment bulky and prone to fatigue with long-term use. Lead-based materials are also highly toxic, and long-term exposure can damage the human nervous system and cause various diseases. Furthermore, bulk materials lack flexibility, making their rigid structures difficult to conform to complex surfaces, leading to gaps and seams, creating blind spots in protection. This is particularly problematic in applications such as medical interventional protection and aerospace cabins. Consequently, traditional radiation protection materials struggle to meet the demands for lightweight, flexible, and complex applications. Summary of the Invention

[0003] In view of the technical problems existing in the background technology, the present application provides a core-shell heterogeneous gradient structure anti-ionizing radiation powder and its preparation method and application, aiming to solve the technical problem that traditional radiation protection materials are difficult to meet the application requirements of lightweight and complex scenarios.

[0004] In a first aspect, the present invention provides a method for preparing a core-shell heterogeneous gradient structured ionizing radiation-proof powder, comprising the following steps: S1. Adding a high atomic number metal salt to deionized water, followed by aging, washing, drying, and primary calcination to obtain a high atomic number metal core layer; S2, adding the high atomic number metal core layer and the low atomic number metal salt into deionized water, and then sequentially aging, washing, drying, and once calcining to obtain a preliminary coated powder of the low atomic number metal coating the high atomic number metal core layer; S3. Add the preliminary coated powder and rare earth salt into deionized water, and then carry out aging, washing, drying, primary calcination, secondary calcination, air flow crushing, and air rotary blowing in sequence to obtain a core-shell heterogeneous gradient structure anti-ionizing radiation powder.

[0005] In the technical solution of the embodiment of the present application, a sol-gel method combined with a calcination process is used to prepare different metal layers, and through multiple, layer-by-layer coating, a multilayer core-shell structure is formed with a high atomic number metal oxide as the core layer, a gradient shell layer wrapped with a low atomic number metal oxide, and a medium atomic number rare earth metal oxide as the surface layer. The high atomic number metal oxide of the core layer and the medium atomic number rare earth metal oxide of the surface layer can provide complementarity for the electron density of the low atomic number metal oxide in the middle layer, forming a gradient electron density structure, and utilizing the synergistic effect of high and low atomic number oxides and multi-rare earth elements, thereby realizing multi-mechanism collaborative shielding of wide energy spectrum radiation, significantly improving the shielding performance of the material.

[0006] Furthermore, in some embodiments, the mass percentages of the high atomic number metal salt, the low atomic number metal salt, and the rare earth salt are 2%-10%: 8%-20%: 70%-90%.

[0007] In this embodiment, by reasonably controlling the mass percentages of different metal salts, the contents of rare earth metal oxides, low atomic number oxides and high atomic number metal oxides in the core-shell heterogeneous gradient structure anti-ionizing radiation powder show a gradient change, thereby achieving a better shielding effect.

[0008] Furthermore, in some embodiments, the rare earth salt includes a mixture of lanthanum nitrate, cerium nitrate, and gadolinium nitrate; and / or the mass percentages of lanthanum nitrate, cerium nitrate, and gadolinium nitrate are 50%-70%: 20%-30%: 10%-20%.

[0009] In this embodiment, by setting the rare earth salt to a mixture of multiple rare earth metals and rationally controlling the mass percentages of different rare earth salts, the surface layer of the obtained core-shell heterogeneous gradient structure anti-ionizing radiation powder contains different proportions of lanthanum nitrate, cerium nitrate, and gadolinium nitrate, thereby achieving efficient shielding.

[0010] Furthermore, in some embodiments, the rare earth salt further includes one or more of samarium nitrate, europium nitrate, praseodymium nitrate, neodymium nitrate, dysprosium nitrate, erbium nitrate, thulium nitrate, and ytterbium nitrate.

[0011] In this embodiment, the shielding performance is further improved by doping with trace amounts of samarium nitrate, europium nitrate, praseodymium nitrate, neodymium nitrate, dysprosium nitrate, erbium nitrate, thulium nitrate, ytterbium nitrate, etc.

[0012] Furthermore, in some embodiments, the high atomic number metal salt includes one or more of sodium metatungstate, tantalum oxalate, and bismuth nitrate; and / or the low atomic number metal salt includes one or more of ferric nitrate, zinc nitrate, and stannous nitrate.

[0013] In this embodiment, by properly setting the types of high atomic number metal salts and low atomic number metal salts, the high atomic number metal oxides, low atomic number metal oxides and rare earth oxides can be better coordinated with each other, thereby improving the shielding effect.

[0014] Furthermore, in some embodiments, the calcination temperature of the first calcination is 200-350° C., and the calcination time is 3-9 hours; and / or the calcination temperature of the second calcination is 560-680° C., and the calcination time is 6-8 hours.

[0015] In this example, by properly setting the primary calcination temperature, moisture is further removed from the three-dimensional network structure of the hydroxide precipitate, while simultaneously decomposing the hydroxide precipitate into metal oxides, thereby improving shielding properties. By properly setting the secondary calcination temperature, the surface rare earth metal oxide layer is coated more densely, thereby improving the stability of the resulting powder material.

[0016] Furthermore, in some embodiments, in step S3, the power of the air flow crushing is 10~30KW, and the crushing time is 0.2~0.5h; and / or, the temperature of the air rotary purge is 920~1200℃, the purge rate is 2~5m / s, and the purge time is 5~10min.

[0017] In this example, by properly controlling the airflow power and pulverization time, the generated powder is uniformly pulverized, agglomeration is avoided, and the particle size distribution is precisely controlled, resulting in uniform multi-component rare earth nanoparticles. By properly controlling the temperature, purging rate, and purging time of the air rotation purge, the resulting multi-component rare earth nanoparticles are further surface treated to produce a low-density core-shell heterogeneous gradient structured ionizing radiation-resistant powder.

[0018] Furthermore, in some embodiments, aging specifically comprises: adjusting the pH value of the solution to 7-8 using ammonia water with a mass concentration of 10%-25%, and aging for 12-18 hours to obtain a mixed precipitate of high atomic number metals; and / or, washing specifically comprises: washing the precipitate 3-5 times using deionized water; and / or, drying specifically comprises: drying at 110-150° C. for 2-3 hours.

[0019] In this embodiment, the pH of the solution is adjusted by ammonia water to promote the formation of a colloidal precipitate; metal salt impurities that may be doped in the precipitate are removed by washing to obtain a high-purity precipitate; and moisture in the precipitate and the moisture in the three-dimensional network structure of the colloidal structure are preliminarily removed by drying, providing favorable conditions for the subsequent primary calcination.

[0020] In the second aspect, an embodiment of the present application provides a core-shell heterogeneous gradient structure anti-ionizing radiation powder prepared by the preparation method of the core-shell heterogeneous gradient structure anti-ionizing radiation powder provided in the first aspect of the present application, the core-shell heterogeneous gradient structure anti-ionizing radiation powder including a high atomic number metal protective layer, a low atomic number metal protective layer and a rare earth metal protective layer arranged in sequence from the inside to the outside; the density of the core-shell heterogeneous gradient structure anti-ionizing radiation powder is 4.5-5.5g / cm³.

[0021] In the technical solution of the embodiment of the present application, the core-shell heterogeneous gradient structure anti-ionizing radiation powder prepared by the specific preparation method of the present application makes the performance of the powder stable and excellent.

[0022] In a third aspect, an embodiment of the present application provides an application of a core-shell heterogeneous gradient structure anti-ionizing radiation powder, wherein the core-shell heterogeneous gradient structure anti-ionizing radiation powder is mixed with natural rubber in an open mill to prepare an anti-radiation sheet; the mass ratio of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the anti-radiation sheet is 60%~80%; and / or, the shielding energy range of the anti-radiation sheet is 20-660KeV.

[0023] In the technical solution of the embodiment of the present application, by reasonably controlling the mass ratio of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the radiation-proof sheet, the obtained radiation-proof sheet has the characteristics of high shielding and high mechanical strength.

[0024] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0026] Figure 1 This is a cross-sectional view of the core-shell heterogeneous gradient structured anti-ionizing radiation powder in the radiation protection sheet according to an embodiment of the present application; Figure 2 These are the SEM images (left) and TEM images (right) of the core-shell heterogeneous gradient structured anti-ionizing radiation powder in the radiation protection sheet prepared in Example 1 of the present application.

[0027] Explanation of the accompanying figures: 1 - rare earth metal protective layer; 2 - low atomic number metal protective layer; 3 - high atomic number metal protective layer. DETAILED DESCRIPTION

[0028] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0030] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0031] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0032] With the rapid development of nuclear technology, people's demand for radiation protection materials is increasing. Traditional lead radiation protection materials have many blind spots, bulky protective equipment and high toxicity, making it difficult for traditional radiation protection materials to meet the application requirements of lightweight and complex scenarios.

[0033] In order to solve the technical problem that traditional radiation protection materials are difficult to meet the application requirements of lightweight and complex scenarios, the present application provides a core-shell heterogeneous gradient structure anti-ionizing radiation powder and its preparation method and application, wherein different metal layers are prepared by adopting a sol-gel method combined with a calcination process, and through multiple, layer-by-layer coating, a multilayer core-shell structure is formed with a high atomic number metal oxide as the core layer, a gradient shell layer wrapped with a low atomic number metal oxide, and a medium atomic number rare earth metal oxide as the surface layer. The high atomic number metal oxide in the core layer and the medium atomic number rare earth metal oxide in the surface layer can provide complementarity for the electron density of the low atomic number metal oxide in the middle layer, forming a gradient structure electron density distribution, and utilizing the synergistic effect of high and low atomic number oxides and multi-rare earth elements to achieve multi-mechanism collaborative shielding of wide energy spectrum radiation, significantly improving the shielding performance of the material.

[0034] In a first aspect, the present invention provides a method for preparing a core-shell heterogeneous gradient structured ionizing radiation-proof powder, comprising the following steps: S1. Add a high atomic number metal salt to deionized water, and then age, wash, dry, and calcine once to obtain a high atomic number metal core layer. Specifically, add the high atomic number metal salt to deionized water, stir with a stirrer at a speed of 400-600 r / min for 2-6 hours to obtain a high atomic number metal mixed solution, and then age, wash, dry, and calcine once to obtain a high atomic number metal core layer with a density of 9.5-19.3 g / cm 3 The high atomic number metal core layer. The conductivity of deionized water is 0.055μS / cm.

[0035] S2. Add the high atomic number metal core layer and the low atomic number metal salt into deionized water, and then age, wash, dry, and calcine once in sequence to obtain a preliminary coated powder of the low atomic number metal encapsulating the high atomic number metal core layer. Specifically, the high atomic number metal core layer obtained in step S1 and the low atomic number metal salt are mixed and added into deionized water, and stirred with a stirrer at a speed of 400-600 r / min for 2-6 hours to obtain a multi-metal mixed solution, and the obtained multi-metal mixed solution is aged, washed, dried, and calcined once to obtain a powder having a density of 8.7-10.8 g / cm 3 The initial coating powder.

[0036] S3, adding the preliminary coated powder and rare earth salt to deionized water, and then aging, washing, drying, primary calcination, secondary calcination, air flow crushing, and air rotary purging in sequence to obtain a core-shell heterogeneous gradient structure ionizing radiation protection powder. Specifically, the preliminary coated powder obtained in step S2 is mixed with the rare earth salt and added to deionized water, and stirred with a stirrer at a speed of 400-600 r / min for 2-6 hours to obtain a multi-component rare earth mixed solution, and the obtained multi-component rare earth mixed solution is aged, washed, dried, and calcined once to obtain a density of 7.6-8.5 g / cm 3 The secondary coated powder is calcined and air flow crushed to obtain a density of 6.5~7.4g / cm 3 The multi-element rare earth nanoparticles are then blown by air to obtain a density of 4.5~5.5g / cm 3 Core-shell heterogeneous gradient structure ionizing radiation-proof powder.

[0037] In the technical solution of the embodiment of the present application, a high atomic number metal core layer (the metal exists in the form of oxide) is first prepared by a sol-gel method combined with a calcination process, and then the high atomic number metal core layer and a low atomic number metal salt are blended so that the low atomic number metal salt adheres to the surface of the high atomic number metal core layer, and again the sol-gel method is combined with a calcination process so that the low atomic number metal is wrapped on the surface of the high atomic number metal core layer to form a preliminary wrapped powder with a core-shell structure (the metal exists in the form of oxide); then the preliminary wrapped powder and a rare earth salt are blended so that the rare earth salt adheres to the surface of the preliminary wrapped powder, and again the sol-gel method is combined with a calcination process so that the rare earth metal is wrapped on the surface of the preliminary wrapped powder (the metal exists in the form of oxide) to form the final core-shell heterogeneous gradient structure ionizing radiation protection powder. The present invention uses multiple, layer-by-layer coatings to form a multilayer core-shell structure with a high-atomic-number metal oxide as the core, a gradient shell layer of low-atomic-number metal oxides, and a surface layer of medium-atomic-number rare-earth metal oxides. The high-atomic-number metal oxide in the core and the medium-atomic-number rare-earth metal oxide in the surface complement the electron density of the low-atomic-number metal oxide in the intermediate layer, forming a gradient electron density distribution. This achieves multi-mechanism synergistic shielding (photoelectric effect, Compton scattering) for wide-energy radiation (X-rays / gamma rays). This achieves multi-mechanism shielding in the 20-660 keV energy range for the first time, increasing shielding efficiency by 20% compared to traditional lead-based materials and eliminating the numerous blind spots associated with traditional lead-based protective materials (which shield in the energy range <100 keV). Simultaneously, the rare-earth metal oxide in the surface layer shields a significant amount of radiation, while the high-atomic-number metal oxide and low-atomic-number metal oxide in the interior provide secondary radiation suppression, further enhancing the excellent shielding performance of the core-shell heterogeneous gradient structured anti-ionizing radiation powder. Specifically, this application significantly enhances the shielding performance of the material through the innovative design of a core-shell heterostructure and the synergistic effects of high- and low-atomic-number oxides and multiple rare earth elements. This approach provides a new high-performance, low-environmental-burden protective material solution for fields such as nuclear medicine and aerospace, while also being feasible for large-scale production.

[0038] Furthermore, in this embodiment, the density of the obtained core-shell heterogeneous gradient structure ionizing radiation protection powder is 4.5-5.5 g / cm 3 , light texture, compared with traditional lead-based materials (lead density 11.34g / cm³), the powder density of this application is reduced by more than 50%.

[0039] Furthermore, in this embodiment, the sol-gel combined with the controllable calcination process can precisely control the chemical composition of the core-shell interface and the thickness of different layers to obtain a core-shell heterogeneous gradient structured ionizing radiation-proof powder with a specific structure.

[0040] Furthermore, in some embodiments, the mass percentages of the high atomic number metal salt, the low atomic number metal salt, and the rare earth salt are 2%-10%, 8%-20%, and 70%-90%. Specifically, before preparing the core-shell heterogeneous gradient structure ionizing radiation-proof powder, the required mass of the high atomic number metal salt, the low atomic number metal salt, and the rare earth salt are weighed and set aside according to the mass percentages of the high atomic number metal salt, the low atomic number metal salt, and the rare earth salt of 2%-10%, 8%-20%, and 70%-90%, based on 100% by mass.

[0041] In the technical solution of the embodiment of the present application, by reasonably controlling the mass percentages of high atomic number metal salts, low atomic number metal salts and rare earth salts, the contents of different layers in the core-shell heterogeneous gradient structure anti-ionizing radiation powder show a gradient change trend, with the content of rare earth metal oxides being the highest, the content of low atomic number oxides being the second, and the content of high atomic number metal oxides being the least. On the one hand, a better shielding effect can be achieved through the mutual cooperation of different proportions. On the other hand, the amounts of the core layer, the middle layer and the surface layer are increased successively, so that the powder obtained by one calcination during the material preparation process is surrounded by the layer to be wrapped in the solution, thereby achieving a better wrapping effect.

[0042] Furthermore, in some embodiments, the rare earth salt includes a mixture of lanthanum nitrate, cerium nitrate, and gadolinium nitrate; and / or the mass percentages of lanthanum nitrate, cerium nitrate, and gadolinium nitrate are 50%-70%: 20%-30%: 10%-20%.

[0043] In the technical solution of the embodiment of the present application, by setting the rare earth salt to a mixture of multiple rare earth metals such as lanthanum nitrate, cerium nitrate, and gadolinium nitrate, and rationally controlling the mass percentages of different rare earth salts, the surface layer of the obtained core-shell heterogeneous gradient structure anti-ionizing radiation powder contains different proportions of lanthanum nitrate, cerium nitrate, and gadolinium nitrate, and efficient shielding is achieved through the mutual synergy of different rare earth metal oxides.

[0044] Furthermore, in some embodiments, the rare earth salt further comprises one or more of samarium nitrate, europium nitrate, praseodymium nitrate, neodymium nitrate, dysprosium nitrate, erbium nitrate, thulium nitrate, and ytterbium nitrate. Specifically, samarium nitrate, europium nitrate, praseodymium nitrate, neodymium nitrate, dysprosium nitrate, erbium nitrate, thulium nitrate, and ytterbium nitrate are doped in trace amounts.

[0045] In the technical solution of the embodiment of the present application, the shielding performance is further improved by trace doping with samarium nitrate, europium nitrate, praseodymium nitrate, neodymium nitrate, dysprosium nitrate, erbium nitrate, thulium nitrate, ytterbium nitrate, etc.

[0046] Furthermore, in some embodiments, the high atomic number metal salt includes one or more of sodium metatungstate, tantalum oxalate, and bismuth nitrate; and / or the low atomic number metal salt includes one or more of ferric nitrate, zinc nitrate, and stannous nitrate.

[0047] In the technical solution of the embodiments of this application, by rationally selecting the types of high-atomic-number metal salts and low-atomic-number metal salts, it is possible to achieve better synergy between high-atomic-number metal oxides, low-atomic-number metal oxides, and rare earth oxides, thereby enhancing shielding effectiveness. Furthermore, the materials used in this core-shell heterogeneous gradient structured anti-ionizing radiation powder are lead-free, pollution-free, and harmless to the human body, achieving the desired synergistic combination of key functional indicators such as nuclear radiation protection performance, lightweight, soft and comfortable, and non-toxic.

[0048] Furthermore, in some embodiments, the primary calcination temperature is 200-350°C, and the calcination time is 3-9 hours; the secondary calcination temperature is 560-680°C, and the calcination time is 6-8 hours. Specifically, both the primary calcination and the secondary calcination are performed under nitrogen protection.

[0049] In the technical solution of the embodiment of the present application, by reasonably setting the temperature of the first calcination, the moisture in the three-dimensional network structure of the hydroxide precipitate is further removed, and the hydroxide precipitate is decomposed into metal oxides, thereby improving the shielding performance; the calcination temperature of the first calcination is controlled at 200~350℃ to prevent the temperature from being too low to achieve sufficient decomposition of the hydroxide precipitate, and to avoid excessively high temperature from destroying the crystal structure of the generated metal oxide. By reasonably setting the temperature of the second calcination, the rare earth metal oxide layer on the surface is coated more densely, thereby improving the stability of the obtained powder material. By carrying out both the first calcination and the second calcination under nitrogen protection, the generation of impurities is avoided, thereby improving the purity and performance of the obtained powder material.

[0050] Furthermore, in some embodiments, in step S3, the air flow pulverization power is 10-30 kW, the pulverization time is 0.2-0.5 h, the air rotary purge temperature is 920-1200° C., the purge speed is 2-5 m / s, and the purge time is 5-10 min.

[0051] In the technical solution of the embodiment of the present application, by reasonably setting the power and pulverization time of the air flow pulverization, the air flow pulverization reaches a certain intensity, thereby uniformly pulverizing the generated secondary coated powder, avoiding agglomeration between the secondary coated powders, achieving ultrafine pulverization of the secondary coated powders, and accurately controlling their particle size distribution, obtaining multi-component rare earth nanoparticles with uniform particle size, and providing favorable conditions for subsequent air rotary purging. By reasonably controlling the temperature, purging rate, and purging time of the air rotary purging, the obtained multi-component rare earth nanoparticles are further surface treated to remove impurities that may be attached to their surfaces, while making the surfaces of the multi-component rare earth nanoparticles smooth and rounded, obtaining a low-density core-shell heterogeneous gradient structure anti-ionizing radiation powder.

[0052] Furthermore, in some embodiments, aging specifically comprises: adjusting the pH value of the solution to 7-8 using ammonia water with a mass concentration of 10%-25%, aging for 12-18 hours, and obtaining a high atomic number metal mixed precipitate; washing specifically comprises: washing the precipitate 3-5 times using deionized water; and drying specifically comprises: drying at 110-150° C. for 2-3 hours.

[0053] In the technical solution of the embodiment of the present application, the pH value of the metal salt solution is adjusted to 7-8 by ammonia, so that the metal salt solution is hydrolyzed to generate hydroxide colloidal particles, and a hydroxide precipitate is obtained after aging. The presence of ammonia adjusts the pH of the solution to promote the formation of the precipitate, and on the other hand, affects the stability and particle size distribution of the colloidal particles. By washing, the metal salt impurities that may be doped in the precipitate are removed to obtain a high-purity precipitate, which provides favorable conditions for the subsequent preparation of a high-purity gradient structure. Drying preliminarily removes the moisture in the precipitate and the moisture in the colloidal three-dimensional network structure, providing favorable conditions for the subsequent primary calcination.

[0054] Second, please refer to Figure 1 , an embodiment of the present application provides a core-shell heterogeneous gradient structure anti-ionizing radiation powder prepared by the preparation method of the core-shell heterogeneous gradient structure anti-ionizing radiation powder provided by the first aspect of the present application, the core-shell heterogeneous gradient structure anti-ionizing radiation powder includes a high atomic number metal protective layer 3, a low atomic number metal protective layer 2 and a rare earth metal protective layer 1 arranged in sequence from the inside to the outside; the density of the core-shell heterogeneous gradient structure anti-ionizing radiation powder is 4.5-5.5g / cm³.

[0055] In the technical solution of the embodiment of the present application, the core-shell heterogeneous gradient structure anti-ionizing radiation powder prepared by the specific preparation method of the present application has a surface layer of a rare earth metal oxide that is wear-resistant and corrosion-resistant, and a core layer of a stable high-atomic-number metal oxide, resulting in stable and excellent performance of the powder. The resulting core-shell heterogeneous gradient structure anti-ionizing radiation powder has a low density; the detection level of heavy metals such as lead, mercury, cadmium, and chromium is zero, and it is highly safe; and wide-band shielding is achieved through energy spectrum matching design, reducing the leakage blind area of ​​a single radiation type, that is, the protection energy band is wide and the protection blind area is small.

[0056] On the third aspect, the embodiment of the present application provides an application of a core-shell heterogeneous gradient structure anti-ionizing radiation powder, in which the core-shell heterogeneous gradient structure anti-ionizing radiation powder is mixed with natural rubber in an open mill to prepare an anti-radiation sheet; the mass ratio of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the anti-radiation sheet is 60% to 80%, and the shielding energy range of the anti-radiation sheet is 20-660KeV. Specifically, the core-shell heterogeneous gradient structure anti-ionizing radiation powder is sprayed with a silane coupling agent, dried, and then mixed with natural rubber in an open mill to prepare an anti-radiation sheet. Natural rubber is vulcanized at 120-150°C. The tensile strength of the obtained anti-radiation sheet is 7.38MPa, the X-ray protection performance is improved by 20%, and the softness is increased by 3 times compared with lead-based materials.

[0057] In the technical solution of the embodiment of the present application, the core-shell heterogeneous gradient structure anti-ionizing radiation powder is first sprayed with a silane coupling agent, and the active groups on the surface of the powder react with the silane coupling agent, so that the silane coupling agent is evenly bonded to the surface of the powder; then it is mixed with natural rubber in an open mill, and the silane coupling agent reacts with the natural rubber and bonds with each other, realizing chemical bonding at the heterogeneous interface, improving the bonding strength between the core-shell heterogeneous gradient structure anti-ionizing radiation powder and the natural rubber, and obtaining a film with a stable structure and uniform powder distribution.

[0058] Furthermore, in this embodiment, vulcanization of natural rubber can change the molecular structure through chemical cross-linking, thereby significantly improving the physical and mechanical properties of natural rubber.

[0059] Furthermore, in this embodiment, by reasonably controlling the mass ratio of the core-shell heterogeneous gradient structured anti-ionizing radiation powder in the anti-radiation sheet, the amount of natural rubber used is minimized to avoid the brittleness of the material.

[0060] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0061] Example 1 A method for preparing a core-shell heterogeneous gradient structure ionizing radiation protection powder comprises the following steps: Taking the mass as 100%, the required mass of high atomic number metal salt, low atomic number metal salt and rare earth salt is weighed according to the mass percentage of high atomic number metal salt, low atomic number metal salt and rare earth salt of 5%:15%:80%, that is, the mass percentage of high atomic number metal salt, low atomic number metal salt and rare earth salt is 5%:15%:80%.

[0062] S1. Add 5% sodium metatungstate to deionized water, stir with a stirrer at 500r / min for 5h to obtain a sodium metatungstate mixed solution; then adjust the pH value of the sodium metatungstate mixed solution to 7-8 with 20% ammonia water, and age it for 18h to obtain a precipitate; then wash the precipitate 4 times with deionized water, and dry it at 130℃ for 2.5h; then calcined at 300℃ for 6h under nitrogen protection to obtain a high atomic number metal core layer.

[0063] S2. The high atomic number metal core layer obtained in step S1 is mixed with 15% ferric nitrate and added to deionized water. The mixture is stirred at a speed of 500 r / min with a stirrer for 5 hours to obtain a multi-metal mixed solution. The pH value of the multi-metal mixed solution is then adjusted to 7-8 with ammonia water having a mass concentration of 20%, and aged for 18 hours to obtain a precipitate. The precipitate is then washed 4 times with deionized water and dried at 130° C. for 2.5 hours. The mixture is then calcined at 300° C. for 6 hours under nitrogen protection to obtain a preliminary coated powder.

[0064] S3, the primary coated powder obtained in step S2 is mixed with 80% of rare earth salt and added into deionized water, and stirred with a stirrer at a speed of 500r / min for 5h to obtain a multi-metal mixed solution, and then the pH value of the mixed solution is adjusted to 7-8 with ammonia water having a mass concentration of 20%, and aged for 18h to obtain a precipitate; then the precipitate is washed 4 times with deionized water, dried at 130°C for 2.5h; then calcined at 300°C for 6h under nitrogen protection to obtain a secondary coated powder; the secondary coated powder is calcined at 600°C for 6h under nitrogen protection, and air flow crushed for 0.4h; then purged with air at 1000°C for 8min to obtain a density of 4.79g / cm 3 Core-shell heterogeneous gradient structure ionizing radiation-proof powder.

[0065] The rare earth salt comprises a mixture of lanthanum nitrate, cerium nitrate, and gadolinium nitrate; the mass percentages of lanthanum nitrate, cerium nitrate, and gadolinium nitrate are 60%:25%:15%. The air flow milling power is 20 kW, and the air rotary sweeping speed is 3.5 m / s.

[0066] S4. Spraying the core-shell heterogeneous gradient structure anti-ionizing radiation powder with a silane coupling agent mixture, drying, and mixing with natural rubber in an open mill to prepare a radiation-proof sheet. The mass ratio of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the radiation-proof sheet is 70%. Specifically, the silane coupling agent mixture is a mixture of KH550, ethanol, and deionized water in a mass ratio of 5%:50%:45%, accounting for 3% of the mass of the core-shell heterogeneous gradient structure anti-ionizing radiation powder. It is sprayed evenly in small amounts multiple times and then dried.

[0067] like Figure 2As shown in the figure, there are SEM and TEM images of the core-shell heterogeneous gradient structure anti-ionizing radiation powder prepared in Example 1. It can be seen from the SEM image that the surface of the obtained core-shell heterogeneous gradient structure anti-ionizing radiation powder has wrapped particles. At the same time, it can be seen from the TEM image that the obtained anti-ionizing radiation powder has a neat core-shell structure.

[0068] Examples 2-3 and Comparative Examples 1-6 A method for preparing a core-shell heterogeneous gradient structure ionizing radiation-proof powder is different from that of Example 1 in that the mass percentages of the high atomic number metal salt, the low atomic number metal salt, and the rare earth salt are different. The rest is substantially the same as that of Example 1 and will not be repeated here.

[0069] The density of the core-shell heterogeneous gradient structure anti-ionizing radiation powders prepared in Examples 1 to 3 and Comparative Examples 1 to 6 and the radiation protection performance (to X-rays and gamma rays) of the radiation protection films were tested. The results are shown in Table 1.

[0070] Density test is carried out using a density tester.

[0071] Radiation protection tests were conducted and the shielding efficiency (attenuation efficiency) was calculated according to the method disclosed in GBZT 147-2002 "Determination of attenuation properties of X-ray shielding materials." The incident energies of X-rays and gamma rays were 110 KeV and 660 KeV, respectively.

[0072] Table 1 Performance test of Examples 1 to 3 and Comparative Examples 1 to 6 As shown in Table 1, when the mass percentages of the high atomic number metal salt, the low atomic number metal salt, and the rare earth salt vary within an appropriate range (Examples 1-3), the density of the obtained core-shell heterogeneous gradient structured ionizing radiation-proof powder is lower than 5.50 g / cm³. At the same time, the radiation protection efficiency of the radiation-proof sheet against X-rays is higher than 71%, and the radiation protection efficiency against gamma rays is higher than 57%, indicating good overall performance.

[0073] When the high-atomic-number metal salt content is excessive (Comparative Example 1), while the radiation protection performance of the flakes increases, the resulting core-shell heterogeneous gradient structured ionizing radiation-blocking powder has a high density, which is not conducive to lightweighting. When the high-atomic-number metal salt content is too low (Comparative Example 2), the radiation protection performance of the flakes is weakened. Varying the proportion of high-atomic-number metal salts significantly affects the density of the resulting core-shell heterogeneous gradient structured ionizing radiation-blocking powder. In practical applications, the construction of a core-shell heterogeneous gradient structure can effectively reduce the material's density while maintaining substantial radiation protection performance.

[0074] When the amount of low-atomic-number metal salt used is too high (Comparative Example 4), the radiation protection performance of the sheet is affected to a certain extent. When the amount of low-atomic-number metal salt used is too low (Comparative Example 3), the amount of high-atomic-number metal salt used is relatively high, and the density of the ionizing radiation protection powder is relatively high.

[0075] When the amount of rare earth salt used is too small (Comparative Example 5), the density of the anti-ionizing radiation powder is too high; when the amount of rare earth salt used is too large (Comparative Example 6), the radiation protection of the thin sheet prepared from the core-shell heterogeneous gradient structure anti-ionizing radiation powder is reduced.

[0076] Examples 4-5 and Comparative Examples 7-8 A method for preparing a core-shell heterogeneous gradient structure anti-ionizing radiation powder is different from that in Example 1 in that, in step S4, the mass ratio of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the radiation protection sheet is different. The rest is substantially the same as Example 1 and will not be repeated here.

[0077] A universal material testing machine (tensile testing machine) was used to test the tensile strength of the radiation protection film.

[0078] Table 2 Performance test of Examples 4-5 and Comparative Examples 7-8 Table 2 shows that when the weight percentage of the core-shell heterogeneous gradient structured ionizing radiation protection powder in the radiation-proof sheet ranges from 60% to 80%, the overall performance of the core-shell heterogeneous gradient structured ionizing radiation protection powder and the radiation-proof sheet is good. As the weight percentage of the ionizing radiation protection powder increases, the X-ray and gamma-ray protection performance of the radiation-proof sheet gradually increases, but the tensile strength gradually decreases. When the weight percentage of the core-shell heterogeneous gradient structured ionizing radiation protection powder in the radiation-proof sheet exceeds 80%, the tensile strength of the radiation-proof sheet is significantly poor. This may be because the excessive weight percentage of the core-shell heterogeneous gradient structured ionizing radiation protection powder disrupts the crosslinking between the natural rubber molecular chains, thereby affecting its tensile strength and ultimately rendering it unusable. When the weight percentage of the core-shell heterogeneous gradient structured ionizing radiation protection powder in the radiation-proof sheet is less than 60%, the radiation protection performance of the radiation-proof sheet is poor and cannot meet daily protection needs.

[0079] Example 6 A method for preparing a core-shell heterogeneous gradient structured ionizing radiation-proof powder is different from that in Example 1 in that, in step S3, the rare earth salt includes samarium nitrate in addition to lanthanum nitrate, cerium nitrate, and gadolinium nitrate, and their mass percentages are 60%:25%:10%:5%. The rest is substantially the same as in Example 1 and will not be repeated here.

[0080] Table 3 Performance test of Example 1 and Example 6 As can be seen from Table 3, the density of the core-shell heterogeneous gradient structure anti-ionizing radiation powder obtained in Example 6 is 4.73 g / cm³, and the shielding efficiency against X-rays and γ-rays is 71.982% and 57.627%, respectively. This shows that the addition of samarium nitrate not only reduces the density, but also improves the protection performance of X-rays and γ-rays. At the same time, the tensile strength of the sheet is increased. It can be seen that multi-element composite can optimize the density of the core-shell heterogeneous gradient structure anti-ionizing radiation powder and the comprehensive performance of the sheet.

[0081] Examples 7-8 and Comparative Examples 9-11 A method for preparing a core-shell heterogeneous gradient structured ionizing radiation-proof powder is provided. The method differs from Example 1 in that, in step S3, the mass percentages of lanthanum nitrate, cerium nitrate, and gadolinium nitrate in the rare earth salt are different. The other aspects are substantially the same as those of Example 1 and are not described herein.

[0082] Table 4 Performance test of Examples 7-8 and Comparative Examples 9-11 It can be seen from Table 4 that when the mass percentages of lanthanum nitrate, cerium nitrate, and gadolinium nitrate vary within an appropriate range, the overall performance of the obtained core-shell heterogeneous gradient structured anti-ionizing radiation powder and anti-radiation sheet is better, and when the content of cerium nitrate and gadolinium nitrate is higher, the protective performance of the obtained anti-radiation sheet is better.

[0083] The data from Comparative Examples 9-11 show that when the rare earth metal salts are not a mixture of lanthanum nitrate, cerium nitrate, and gadolinium nitrate, but only one or two of these, the resulting radiation shielding sheet exhibits significantly poorer radiation protection performance. This suggests that the lanthanum nitrate, cerium nitrate, and gadolinium nitrate synergize to achieve a better radiation shielding effect. Furthermore, when the content of cerium nitrate and gadolinium nitrate is high, the resulting radiation shielding sheet exhibits better protection.

[0084] Comparative Example 12 A method for preparing a core-shell heterogeneous gradient structured ionizing radiation-proof powder is different from that in Example 1 in that no secondary calcination is performed in step S3. The rest is substantially the same as in Example 1 and will not be described in detail here.

[0085] Comparative Example 13 A method for preparing an ionizing radiation-proof powder is disclosed. Compared with Example 1, the method differs in that a high atomic number metal salt, a low atomic number metal salt, and a rare earth salt are directly blended to form a mixed solution, and then aged, washed, dried, calcined once, calcined twice, air flow crushed, and air rotary purged to obtain the ionizing radiation-proof powder. The other steps are substantially the same as those in Example 1 and are not further described here.

[0086] Comparative Example 14 A method for preparing a core-shell heterogeneous gradient structure ionizing radiation-proof powder is disclosed. Compared to Example 1, the method differs in that the rare earth metal oxide in the obtained core-shell heterogeneous gradient structure ionizing radiation-proof powder forms a core layer and a high-atomic-number metal oxide forms a surface layer. The mass percentages of the rare earth salt, the low-atomic-number metal salt, and the high-atomic-number metal salt are 5%:15%:80%. Other aspects are substantially the same as in Example 1 and are not further described here.

[0087] Comparative Example 15 A method for preparing a core-shell heterogeneous gradient structure ionizing radiation protection powder comprises the following steps: Taking the mass as 100%, the required mass of high atomic number metal salt, low atomic number metal salt and rare earth salt is weighed according to the mass percentage of high atomic number metal salt, low atomic number metal salt and rare earth salt of 5%:15%:80%, that is, the mass percentage of high atomic number metal salt, low atomic number metal salt and rare earth salt is 5%:15%:80%.

[0088] S1. Add 5% sodium metatungstate to deionized water, stir with a stirrer at 500r / min for 5h to obtain a sodium metatungstate mixed solution; then adjust the pH value of the sodium metatungstate mixed solution to 7-8 with 20% ammonia water, and age it for 18h to obtain a precipitate; S2, adding 15% ferric nitrate solution to the precipitate in step S1, stirring with a stirrer at a speed of 500r / min for 5h to obtain a multi-metal mixed solution, then adjusting the pH value of the sodium metatungstate mixed solution to 7-8 with 20% ammonia water, and aging for 18h to obtain a precipitate; S3. Add 80% of the rare earth salt solution to the precipitate of step S2, stir with a stirrer at a speed of 500 r / min for 5 hours to obtain a multi-metal mixed solution, then use 20% ammonia water to adjust the pH value of the sodium metatungstate mixed solution to 7-8, and age it for 18 hours to obtain a precipitate; then use deionized water to wash the precipitate 4 times, and dry it at 130°C for 2.5 hours; then calcine it at 300°C for 6 hours under nitrogen protection to obtain a secondary coated powder; the secondary coated powder is calcined at 600°C for 6 hours under nitrogen protection, and is air-flow-pulverized for 0.4 hours to obtain multi-metal rare earth nanoparticles; then it is purged with air at 1000°C for 8 minutes to obtain a core-shell heterogeneous gradient structure anti-ionizing radiation powder.

[0089] The rare earth salt comprises a mixture of lanthanum nitrate, cerium nitrate, and gadolinium nitrate; the mass percentages of lanthanum nitrate, cerium nitrate, and gadolinium nitrate are 60%:25%:15%. The air flow milling power is 20 kW, and the air rotary sweeping speed is 3.5 m / s.

[0090] S4. Spraying the core-shell heterogeneous gradient structured ionizing radiation protection powder with a silane coupling agent, drying the powder, and mixing it with natural rubber in an open mill to prepare a radiation protection sheet. The weight ratio of the core-shell heterogeneous gradient structured ionizing radiation protection powder in the radiation protection sheet is 70%.

[0091] Table 5 Performance test of comparative examples 12 to 15 It can be seen from the data of Comparative Example 12 in Table 5 that when the secondary calcination is not performed in step S3, the density of the obtained core-shell heterogeneous gradient structure anti-ionizing radiation powder increases, and the radiation protection performance of the radiation protection powder decreases. This may be because during the secondary calcination, further bonding occurs between the rare earth oxides in the surface rare earth metal oxide layer, changing the binding structure between the molecules, making the powder more stable, and the mutual synergistic effect between various substances is optimized, thereby making the powder lighter and the radiation protection performance of the radiation protection film more stable.

[0092] It can be seen from the data of Comparative Example 13 that when high atomic number metal salts, low atomic number metal salts and rare earth salts are directly blended, the anti-ionizing radiation powder obtained at this time cannot achieve a core-shell heterogeneous gradient structure, thereby reducing the radiation protection performance of the obtained radiation-proof sheet, indicating the importance of the core-shell heterogeneous gradient structure of the present invention.

[0093] It can be seen from the data of Comparative Example 14 that when rare earth metal oxide is used as the core layer and high atomic number metal oxide is used as the surface layer, the radiation protection performance of the radiation protection sheet prepared from the obtained core-shell heterogeneous gradient structure anti-ionizing radiation powder is significantly reduced, which shows that the arrangement relationship of the core-shell structure will also affect the radiation performance.

[0094] It can be seen from the data of Comparative Example 15 that when the core layer and the intermediate layer are prepared only by the sol-gel method, and when the sol-gel method and calcination are combined after the outermost layer of rare earth salt is coated, the density of the obtained core-shell heterogeneous gradient structure anti-ionizing radiation powder and the performance of the radiation-proof thin sheet are affected. This may be because the layered structure of the core-shell heterogeneous gradient structure anti-ionizing radiation powder obtained at this time is not obvious, that is, the layer structure is not neat, which affects the electron cloud density arrangement of the powder and the mutual synergy between different layers, thereby affecting its performance.

[0095] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing a core-shell heterogeneous gradient structure ionizing radiation protection powder, characterized in that: The steps include: S1. Adding a high atomic number metal salt to deionized water, followed by aging, washing, drying, and primary calcination to obtain a high atomic number metal core layer; S2, adding the high atomic number metal core layer and the low atomic number metal salt into deionized water, and then sequentially aging, washing, drying, and calcining to obtain a preliminary coated powder of the low atomic number metal coating the high atomic number metal core layer; S3. Adding the preliminary coated powder and rare earth salt into deionized water, followed by aging, washing, drying, primary calcination, secondary calcination, air flow pulverization, and air rotary purging to obtain a core-shell heterogeneous gradient structured ionizing radiation-proof powder.

2. The method for preparing the core-shell heterogeneous gradient structure ionizing radiation protection powder according to claim 1, characterized in that: The mass percentages of the high atomic number metal salt, the low atomic number metal salt and the rare earth salt are 2%-10%: 8%-20%: 70%-90%.

3. The method for preparing the core-shell heterogeneous gradient structure ionizing radiation protection powder according to claim 1, characterized in that: The rare earth salt comprises a mixture of lanthanum nitrate, cerium nitrate and gadolinium nitrate; and / or, The mass percentages of the lanthanum nitrate, cerium nitrate, and gadolinium nitrate are 50%-70%: 20%-30%: 10%-20%.

4. The method for preparing the core-shell heterogeneous gradient structure ionizing radiation protection powder according to claim 3, characterized in that: The rare earth salt further comprises one or more of samarium nitrate, europium nitrate, praseodymium nitrate, neodymium nitrate, dysprosium nitrate, erbium nitrate, thulium nitrate, and ytterbium nitrate.

5. The method for preparing the core-shell heterogeneous gradient structure ionizing radiation protection powder according to claim 1, characterized in that: The high atomic number metal salt includes one or more of sodium metatungstate, tantalum oxalate, and bismuth nitrate; and / or, The low atomic number metal salt includes one or more of ferric nitrate, zinc nitrate, and stannous nitrate.

6. The method for preparing the core-shell heterogeneous gradient structure ionizing radiation protection powder according to claim 1, characterized in that: The primary calcination temperature is 200-350° C. and the calcination time is 3-9 hours; and / or, The secondary calcination has a calcination temperature of 560-680° C. and a calcination time of 6-8 hours.

7. The method for preparing the core-shell heterogeneous gradient structure ionizing radiation protection powder according to claim 1, characterized in that: In step S3, the power of the air flow pulverization is 10-30 kW, and the pulverization time is 0.2-0.5 h; and / or, The temperature of the air rotary purge is 920-1200° C., the purge speed is 2-5 m / s, and the purge time is 5-10 min.

8. The method for preparing the core-shell heterogeneous gradient structure ionizing radiation protection powder according to claim 1, characterized in that: The aging specifically comprises: adjusting the pH value of the solution to 7-8 using ammonia water with a mass concentration of 10%-25%, and aging for 12-18 hours; and / or, The washing specifically comprises: washing the precipitate 3 to 5 times with deionized water; and / or, The drying is specifically: drying at 110-150° C. for 2-3 hours.

9. A core-shell heterogeneous gradient structure ionizing radiation protection powder prepared by the method for preparing a core-shell heterogeneous gradient structure ionizing radiation protection powder according to any one of claims 1 to 8, characterized in that: The core-shell heterogeneous gradient structure ionizing radiation protection powder includes a high atomic number metal protective layer, a low atomic number metal protective layer and a rare earth metal protective layer arranged in sequence from the inside to the outside; the density of the core-shell heterogeneous gradient structure ionizing radiation protection powder is 4.5-5.5g / cm³.

10. An application of a core-shell heterogeneous gradient structured ionizing radiation protection powder, characterized in that: The core-shell heterogeneous gradient structure ionizing radiation protection powder is mixed with natural rubber in an open mill to prepare a radiation protection sheet; the mass ratio of the core-shell heterogeneous gradient structure ionizing radiation protection powder in the radiation protection sheet is 60% to 80%; and / or, The shielding energy range of the radiation protection sheet is 20-660 KeV.

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