Core-shell hetero-gradient structure anti-ionizing radiation powder, preparation method and application thereof

Abstract

The application provides a core-shell heterogeneous gradient structure anti-ionizing radiation powder and a preparation method and application thereof, and belongs to the field of radiation protection. The preparation method of the core-shell heterogeneous gradient structure anti-ionizing radiation powder comprises the following steps: adding a high-atomic-number metal salt into deionized water, sequentially performing aging, washing, drying and primary calcination to obtain a core layer; adding the core layer and a low-atomic-number metal salt into deionized water, sequentially performing aging, washing, drying and primary calcination to obtain a preliminary wrapped powder in which a low-atomic-number metal wraps a high-atomic-number metal core layer; adding the preliminary wrapped powder and a rare earth salt into deionized water, sequentially performing aging, washing, drying, primary calcination, secondary calcination, airflow pulverization and air rotation blowing to obtain the core-shell heterogeneous gradient structure anti-ionizing radiation powder. Through the synergy of the core-shell heterogeneous structure, high-atomic-number and low-atomic-number oxides and multiple rare earth elements, the shielding performance of the material is significantly improved.

Description

TECHNICAL FIELD

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

[0002] With the rapid development of nuclear technology, the demand for radiation protection materials is increasing. Traditional radiation protection materials (such as lead plates, concrete) have certain shielding effect on gamma rays and X-rays, but lead-based materials have extremely high density (the density of lead is 11.34 g / cm³), which leads to heavy protective equipment, and long-term use can cause fatigue; lead-based materials are highly toxic, and long-term contact can damage the nervous system of the human body and cause various diseases; in addition, the block material has poor flexibility, and its rigid structure is difficult to fit complex surfaces, which can easily produce joints, gaps and other blind areas of protection, especially in medical intervention protection, aerospace cabin and other scenes. It can be seen that traditional radiation protection materials are difficult to meet the application requirements of lightweight, flexibility and complex scenes. SUMMARY

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

[0004] In a first aspect, the present application provides a preparation method of a core-shell heterogeneous gradient structure anti-ionizing radiation powder, comprising the following steps:

[0005] S1, adding a high-atomic-number metal salt into deionized water, and then sequentially performing aging, washing, drying and primary calcination to obtain a high-atomic-number metal core layer;

[0006] S2, adding the high-atomic-number metal core layer and a low-atomic-number metal salt into deionized water, and then sequentially performing aging, washing, drying and primary calcination to obtain a preliminary coated powder of the low-atomic-number metal wrapping the high-atomic-number metal core layer;

[0007] S3, adding the preliminary coated powder and a rare earth salt into deionized water, and then sequentially performing aging, washing, drying, primary calcination, secondary calcination, airflow pulverization and air rotation blowing to obtain a core-shell heterogeneous gradient structure anti-ionizing radiation powder.

[0008] In the technical scheme of the embodiment of the present application, different metal layers are prepared by adopting a sol-gel method combined with a calcination process, and a multi-layer core-shell structure is formed by multiple and layer-by-layer coating, in which a high-atomic-number metal oxide is used as a core layer, a low-atomic-number metal oxide is used as a gradient shell layer, and a rare earth metal oxide with a medium atomic number is used as a surface layer. The high-atomic-number metal oxide of the core layer and the rare earth metal oxide with a medium atomic number of the surface layer can provide complementation for the electron density of the low-atomic-number metal oxide of the intermediate layer, form a gradient electron density structure, and utilize the synergistic effect of the high- and low-atomic-number oxides and the multiple rare earth elements, thereby realizing multi-mechanism synergistic shielding of wide-energy-spectrum radiation and significantly improving the shielding performance of the material.

[0009] Further, 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% to 10%, 8% to 20%, and 70% to 90%, respectively.

[0010] In this embodiment, by reasonably controlling the mass percentages of different metal salts, the contents of the non-rare earth metal oxide, the low-atomic-number oxide, and the high-atomic-number metal oxide in the core-shell heterogeneous gradient structure anti-ionizing radiation powder are made to change in a gradient manner, thereby achieving better shielding effect.

[0011] Further, in some embodiments, the rare earth salt includes a mixture of lanthanum nitrate, cerium nitrate, and gadolinium nitrate; and / or, the mass percentages of the lanthanum nitrate, the cerium nitrate, and the gadolinium nitrate are 50% to 70%, 20% to 30%, and 10% to 20%, respectively.

[0012] In this embodiment, by setting the rare earth salt as a mixture of multiple rare earth metals and reasonably 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 high-efficiency shielding.

[0013] Further, 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.

[0014] In this embodiment, by slightly doping samarium nitrate, europium nitrate, praseodymium nitrate, neodymium nitrate, dysprosium nitrate, erbium nitrate, thulium nitrate, and ytterbium nitrate, the shielding performance is further improved.

[0015] Further, 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 iron nitrate, zinc nitrate, and stannous nitrate.

[0016] In this embodiment, by reasonably setting the types of high-atomic-number metal salt and low-atomic-number metal salt, the mutual synergy of high-atomic-number metal oxide, low-atomic-number metal oxide and rare earth oxide can be better realized, and the shielding effect is further improved.

[0017] Further, in some embodiments, the calcination temperature of the first calcination is 200-350℃, and the calcination time is 3-9h; and / or, the calcination temperature of the second calcination is 560-680℃, and the calcination time is 6-8h.

[0018] In this embodiment, 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 at the same time the hydroxide precipitate is decomposed into metal oxide, thereby improving the shielding performance. By reasonably setting the temperature of the second calcination, the rare earth metal oxide layer on the surface layer is coated more densely, thereby improving the stability of the obtained powder material.

[0019] Further, in some embodiments, in step S3, the power of the jet milling is 10-30KW, and the milling time is 0.2-0.5h; and / or, the temperature of the air rotary blowing is 920-1200℃, the blowing rate is 2-5m / s, and the blowing time is 5-10min.

[0020] In this embodiment, by reasonably setting the power and the milling time of the jet milling, the generated powder is uniformly milled to avoid agglomeration, and the particle size distribution is precisely controlled to obtain multi-element rare earth nanoparticles with uniform particle size. By reasonably controlling the temperature, the blowing rate and the blowing time of the air rotary blowing, the obtained multi-element rare earth nanoparticles are further surface treated to obtain a low-density core-shell heterogeneous gradient structure anti-ionizing radiation powder.

[0021] Further, in some embodiments, the aging is specifically: adjusting the pH value of the solution to 7-8 by using ammonia water with a mass concentration of 10%-25%, and aging for 12-18h to obtain a high-atomic-number metal mixed precipitate; and / or, the washing is specifically: washing the precipitate with deionized water for 3-5 times; and / or, the drying is specifically: drying at 110-150℃ for 2-3h.

[0022] In this embodiment, by adjusting the pH of the solution with ammonia water, the formation of the colloidal precipitate is promoted; by washing, the metal salt impurities possibly doped in the precipitate are removed to obtain a high-purity precipitate; by drying, the moisture in the precipitate and the moisture in the three-dimensional network structure of the colloidal precipitate are preliminarily removed to provide favorable conditions for the subsequent first calcination.

[0023] In a second aspect, the embodiments of the present application provide a preparation method of the core-shell heterogeneous gradient structure anti-ionizing radiation powder provided by the first aspect of the present application, and the core-shell heterogeneous gradient structure anti-ionizing radiation powder is prepared by the preparation method.

[0024] In the technical solution of the embodiments 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 stable and excellent performance.

[0025] In a third aspect, the embodiments of the present application provide an application of the core-shell heterogeneous gradient structure anti-ionizing radiation powder, 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 / or the shielding energy range of the anti-radiation sheet is 20-660KeV.

[0026] In the technical solution of the embodiments of the present application, the mass ratio of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the anti-radiation sheet is reasonably controlled, so that the obtained anti-radiation sheet has the characteristics of high shielding and high mechanical strength.

[0027] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following will specifically describe the embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the present application, the drawings used in the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating any creative labor on the basis of these drawings.

[0029] Figure 1 A sectional view of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the anti-radiation sheet in the embodiments of the present application;

[0030] Figure 2 A SEM image (left) and a TEM image (right) of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the anti-radiation sheet prepared in the embodiments of the present application.

[0031] Reference numerals: 1 - rare earth metal protective layer; 2 - low atomic number metal protective layer; 3 - high atomic number metal protective layer. DETAILED DESCRIPTION

[0032] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill 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 the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0034] In this paper, "embodiment" means that the specific features, structures or properties described in conjunction with the embodiment can be included in at least one embodiment of the present application. The phrase appears in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment to other embodiments. The skilled person in the art explicitly and implicitly understands that the embodiments described herein can be combined with other embodiments.

[0035] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents a "or" relationship between the front and rear associated objects.

[0036] With the rapid development of nuclear technology, the demand for radiation protection materials is increasing. The traditional lead radiation protection materials have many blind spots, heavy protection equipment and high toxicity, which makes it difficult for traditional radiation protection materials to meet the application requirements of lightweight and complex scenes.

[0037] In order to solve the technical problem that the traditional radiation protection materials are difficult to meet the application requirements of lightweight and complex scenes, the application provides a core-shell heterogeneous gradient structure anti-ionizing radiation powder and a preparation method and application thereof. The different metal layers are prepared by adopting a sol-gel method combined with a calcination process, and a multi-layer core-shell structure is formed by multiple and layer-by-layer coating, in which a high-atomic-number metal oxide is used as a core layer, a low-atomic-number metal oxide is used as a gradient shell layer, and a rare earth metal oxide with a medium atomic number is used as a surface layer. The high-atomic-number metal oxide of the core layer and the rare earth metal oxide with a medium atomic number of the surface layer can complement the electron density of the low-atomic-number metal oxide of the intermediate layer, form a gradient structure electron density distribution, and utilize the synergistic effect of high- and low-atomic-number oxides and multiple rare earth elements, so as to realize multi-mechanism synergistic shielding of a wide energy spectrum radiation, and significantly improve the shielding performance of the material.

[0038] In a first aspect, the application embodiment provides a preparation method of a core-shell heterogeneous gradient structure anti-ionizing radiation powder, including the following steps:

[0039] S1, adding a high-atomic-number metal salt into deionized water, and then sequentially performing aging, washing, drying and first calcination to obtain a high-atomic-number metal core layer. Specifically, the high-atomic-number metal salt is added into deionized water, and then stirred at a speed of 400-600 r / min by a stirrer for 2-6 h to obtain a high-atomic-number metal mixed solution. Then, the high-atomic-number metal mixed solution is subjected to aging, washing, drying and first calcination to obtain the high-atomic-number metal core layer with a density of 9.5-19.3 g / cm 3 . The conductivity of the deionized water is 0.055 μS / cm.

[0040] S2, adding the high-atomic-number metal core layer and a low-atomic-number metal salt into deionized water, and then sequentially performing aging, washing, drying and first calcination to obtain a preliminary coated powder in which a low-atomic-number metal coats a 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 then stirred at a speed of 400-600 r / min by a stirrer for 2-6 h to obtain a multi-metal mixed solution. Then, the multi-metal mixed solution is subjected to aging, washing, drying and first calcination to obtain the preliminary coated powder with a density of 8.7-10.8 g / cm 3 .

[0041] S3, the primary coated powder and rare earth salt are added into deionized water, and then aging, washing, drying, primary calcination, secondary calcination, air flow pulverization and air rotation blowing are sequentially performed to obtain the core-shell heterogeneous gradient structure anti-ionizing radiation powder. Specifically, the primary coated powder obtained in step S2 is mixed with rare earth salt and added into deionized water, and then stirred by a stirrer at a rotating speed of 400-600 r / min for 2-6 h to obtain a multi-element rare earth mixture, the obtained multi-element rare earth mixture is subjected to aging, washing, drying and primary calcination to obtain secondary coated powder with a density of 7.6-8.5 g / cm 3 ; the secondary coated powder is subjected to secondary calcination and air flow pulverization to obtain multi-element rare earth nanoparticles with a density of 6.5-7.4 g / cm 3 ; and then air rotation blowing is performed to obtain the core-shell heterogeneous gradient structure anti-ionizing radiation powder with a density of 4.5-5.5 g / cm 3 .

[0042] In the technical scheme of the embodiment of the present application, firstly, a high-atomic-number metal core layer (metal in the form of oxide) is prepared by adopting a sol-gel method combined with a calcination process, 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, according to the sol-gel method combined with the calcination process, the low-atomic-number metal is wrapped on the surface of the high-atomic-number metal core layer, to form a preliminary wrapped powder (metal in the form of oxide) of core-shell structure; 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, according to the sol-gel method combined with the calcination process, the rare earth metal is wrapped on the surface of the preliminary wrapped powder (metal in the form of oxide), to form a final ionizing radiation shielding powder of core-shell heterogeneous gradient structure. Through multiple and layer-by-layer wrapping, the present application forms a multi-layer core-shell structure with the high-atomic-number metal oxide as the core layer, the low-atomic-number metal oxide as the gradient shell layer, and the 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 complementation for the electron density of the low-atomic-number metal oxide of the intermediate layer, form a gradient structure of electron density distribution, and thus realize multi-mechanism synergistic shielding (photoelectric effect, Compton scattering) of wide energy spectrum radiation (X / γ rays). The present application first realizes multi-mechanism shielding of the energy segment of 20-660KeV, and the shielding efficiency is improved by 20% compared with traditional lead-based materials. The problem of multiple blind spots of traditional lead shielding materials (the shielding energy segment of traditional lead shielding materials is <100KeV) is eliminated. At the same time, the rare earth metal oxide of the surface layer shields a large amount of radiation, and the high-atomic-number metal oxide and the low-atomic-number metal oxide in the interior secondarily inhibit the radiation, further improving the shielding performance of the ionizing radiation shielding powder of core-shell heterogeneous gradient structure. That is, the present application significantly improves the shielding performance of the material by innovatively designing the core-shell heterogeneous structure and utilizing the synergistic effect of high- and low-atomic-number oxides and multi-element rare earth elements. The method provides a new type of high-performance, low-environmental-load shielding material solution for the fields of nuclear medicine, aerospace, etc., and has the feasibility of large-scale production.

[0043] Further, in this embodiment, the density of the obtained ionizing radiation shielding powder of core-shell heterogeneous gradient structure is 4.5-5.5 g / cm 3 , and the texture is light. Compared with traditional lead-based materials (the density of lead is 11.34 g / cm³), the density of the powder of the present application is reduced by more than 50%.

[0044] Further, in this embodiment, a sol-gel combined with a controllable calcination process is adopted, which can accurately control the chemical composition of the core-shell interface and the thickness of different layers, to obtain the ionizing radiation shielding powder of core-shell heterogeneous gradient structure with a specific structure.

[0045] Further, in some embodiments, the mass percentage of the high-atomic-number metal salt, the low-atomic-number metal salt, and the rare earth salt is 2%-10%:8%-20%:70%-90%. Specifically, before preparing the core-shell heterogeneous gradient structure anti-ionizing radiation powder, the high-atomic-number metal salt, the low-atomic-number metal salt, and the rare earth salt are weighed according to the mass percentage of 2%-10%:8%-20%:70%-90% in 100% of the mass.

[0046] In the technical scheme of the embodiments of the present application, by reasonably controlling the mass percentage of the high-atomic-number metal salt, the low-atomic-number metal salt, and the rare earth salt, the content of different layers of the core-shell heterogeneous gradient structure anti-ionizing radiation powder shows a gradient change trend, the content of the rare earth metal oxide is the highest, the content of the low-atomic-number oxide is the second, and the content of the high-atomic-number metal oxide is the least. On the one hand, a better shielding effect can be achieved by the mutual coordination of different proportions, and on the other hand, the amount of the core layer, the intermediate layer, and the surface layer is sequentially increased, so that the powder obtained by one-time calcination in the material preparation process is surrounded by the to-be-wrapped layer in the solution, and a better wrapping effect is achieved.

[0047] Further, in some embodiments, the rare earth salt includes a mixture of lanthanum nitrate, cerium nitrate, and gadolinium nitrate; and / or the mass percentage of the lanthanum nitrate, the cerium nitrate, and the gadolinium nitrate is 50%-70%:20%-30%:10%-20%.

[0048] In the technical scheme of the embodiments of the present application, by setting the rare earth salt as a mixture of multiple rare earth metals such as lanthanum nitrate, cerium nitrate, and gadolinium nitrate, and reasonably controlling the mass percentage 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 high-efficiency shielding is achieved through the mutual coordination of different rare earth metal oxides.

[0049] Further, 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. Specifically, the samarium nitrate, the europium nitrate, the praseodymium nitrate, the neodymium nitrate, the dysprosium nitrate, the erbium nitrate, the thulium nitrate, and the ytterbium nitrate are trace doping.

[0050] In the technical scheme of the embodiments of the present application, by trace doping of samarium nitrate, europium nitrate, praseodymium nitrate, neodymium nitrate, dysprosium nitrate, erbium nitrate, thulium nitrate, and ytterbium nitrate, the shielding performance is further improved.

[0051] Further, 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 iron nitrate, zinc nitrate, and stannous nitrate.

[0052] In the technical scheme of the embodiment of the present application, by reasonably setting the types of the high-atomic-number metal salt and the low-atomic-number metal salt, the mutual synergy of the high-atomic-number metal oxide, the low-atomic-number metal oxide and the rare earth oxide can be better achieved, and the shielding effect is improved. In addition, the material used for the core-shell heterogeneous gradient structure anti-ionizing radiation powder does not contain lead, is pollution-free and harmless to the human body, and the requirements of the synergistic combination of the key functional indicators such as the nuclear radiation protection performance, light weight, softness, comfort and non-toxicity are achieved.

[0053] Further, in some embodiments, the calcination temperature of the first calcination is 200-350℃, and the calcination time is 3-9h; the calcination temperature of the second calcination is 560-680℃, and the calcination time is 6-8h. Specifically, the first calcination and the second calcination are both carried out under nitrogen protection.

[0054] In the technical scheme of the embodiment of the present application, by reasonably setting the temperature of the first calcination, the water in the three-dimensional network structure of the hydroxide precipitate is further removed, and at the same time, the hydroxide precipitate is decomposed into metal oxide, and the shielding performance is improved; the calcination temperature of the first calcination is controlled to be 200-350℃, so as to prevent that the temperature is too low to achieve the full decomposition of the hydroxide precipitate, and at the same time, avoid that the temperature is too high to damage the crystal structure of the generated metal oxide. By reasonably setting the temperature of the second calcination, the rare earth metal oxide layer of the surface layer is coated more densely, and the stability of the obtained powder material is improved. By carrying out the first calcination and the second calcination under nitrogen protection, the generation of impurities is avoided, and the purity and performance of the obtained powder material are improved.

[0055] Further, in some embodiments, in step S3, the power of the jet milling is 10-30KW, and the milling time is 0.2-0.5h; the temperature of the air rotary blowing is 920-1200℃, and the blowing rate is 2-5m / s. The blowing time is 5-10min.

[0056] In the technical scheme of the embodiment of the present application, by reasonably setting the power and the milling time of the jet milling, the jet milling reaches a certain intensity, so as to uniformly mill the generated secondly wrapped powder, avoid the agglomeration between the secondly wrapped powders, realize the superfine milling of the secondly wrapped powders, accurately control the particle size distribution, obtain the multi-element rare earth nanoparticles with uniform particle size, and provide favorable conditions for the subsequent air rotary blowing. By reasonably controlling the temperature, the blowing rate and the blowing time of the air rotary blowing, the obtained multi-element rare earth nanoparticles are further subjected to surface treatment, the impurities possibly attached to the surface of the multi-element rare earth nanoparticles are removed, and at the same time, the surface of the multi-element rare earth nanoparticles is smooth and round, and the core-shell heterogeneous gradient structure anti-ionizing radiation powder with low density is obtained.

[0057] Further, in some embodiments, the aging is specifically: adjusting the pH value of the solution to 7-8 by using ammonia water with a mass concentration of 10%-25%, and aging for 12-18 hours to obtain the mixed precipitate of high-atomic-number metals; the washing is specifically: washing the precipitate for 3-5 times by using deionized water; and the drying is specifically: drying at 110-150 DEG C for 2-3 hours.

[0058] In the technical scheme of the embodiments of the present application, the pH value of the metal salt solution is adjusted to 7-8 by using ammonia water, so that the metal salt solution is hydrolyzed to generate hydroxide colloidal particles, and the hydroxide precipitate is obtained after aging. The presence of ammonia water 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 possibly doped in the precipitate are removed, and the precipitate with high purity is obtained, which provides favorable conditions for the subsequent preparation of the high-purity gradient structure. The drying preliminarily removes the water in the precipitate and the water in the colloidal three-dimensional network structure, which provides favorable conditions for the subsequent first calcination.

[0059] In the second aspect, referring to Figure 1 The present application provides a preparation method of the core-shell heterogeneous gradient structure anti-ionizing radiation powder provided in the first aspect of the present application, and the core-shell heterogeneous gradient structure anti-ionizing radiation powder is prepared by the preparation method. The core-shell heterogeneous gradient structure anti-ionizing radiation powder comprises 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 inside to outside. The density of the core-shell heterogeneous gradient structure anti-ionizing radiation powder is 4.5-5.5 g / cm3.

[0060] In the technical scheme of the embodiments of the present application, the core-shell heterogeneous gradient structure anti-ionizing radiation powder is prepared by the specific preparation method of the present application. The surface layer is a wear-resistant and corrosion-resistant rare earth metal oxide, and the core layer is a stable high-atomic-number metal oxide, so that the performance of the powder is stable and excellent. The density of the obtained core-shell heterogeneous gradient structure anti-ionizing radiation powder is small; the detection amount of heavy metals such as lead, mercury, cadmium and chromium is 0, and the safety is high; the wide frequency band shielding is realized by the energy spectrum matching design, and the leakage blind area of a single radiation type is reduced, that is, the protection energy band is wide, and the protection blind area is small.

[0061] In a third aspect, the application provides an application of the core-shell heterogeneous gradient structure anti-ionizing radiation powder. 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 segment of the anti-radiation sheet is 20-660KeV. Specifically, the core-shell heterogeneous gradient structure anti-ionizing radiation powder is treated by spraying a silane coupling agent and mixed with natural rubber in an open mill after drying to prepare an anti-radiation sheet. The 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 improved by 3 times compared with a lead-based material.

[0062] In the technical solution of the application, the core-shell heterogeneous gradient structure anti-ionizing radiation powder is first treated by spraying a silane coupling agent, the active groups on the surface of the powder react with the silane coupling agent to make the silane coupling agent uniformly bonded to the surface of the powder. Then, the powder is mixed with natural rubber in an open mill, the silane coupling agent reacts with the natural rubber and is bonded to each other to realize chemical bonding of the heterogeneous interface, improve the bonding strength of the core-shell heterogeneous gradient structure anti-ionizing radiation powder and the natural rubber, and obtain a thin film with stable structure and uniform powder distribution.

[0063] Further, in this embodiment, the natural rubber is treated by vulcanization to change the molecular structure through chemical crosslinking, thereby significantly improving the physical and mechanical properties of the natural rubber.

[0064] Further, in this embodiment, by reasonably controlling the mass ratio of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the anti-radiation sheet, the amount of natural rubber is minimized to avoid the brittleness problem of the material.

[0065] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are used to explain the application, and cannot be understood as limiting the application. If the specific technology or condition is not specified in the examples, the technology or condition described in the literature in the art or according to the product manual is used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained by market purchase.

[0066] Example 1

[0067] A preparation method of a core-shell heterogeneous gradient structure anti-ionizing radiation powder, comprising the following steps:

[0068] The high-atomic-number metal salt, the low-atomic-number metal salt and the rare earth salt are weighed according to the mass percentage of 5%:15%:80% of the high-atomic-number metal salt, the low-atomic-number metal salt and the rare earth salt, that is, the mass percentage of the high-atomic-number metal salt, the low-atomic-number metal salt and the rare earth salt is 5%:15%:80%.

[0069] S1, 5% of sodium tungstate is added to deionized water, and stirred with a stirrer at a speed of 500 r / min for 5 h to obtain a sodium tungstate mixture; then the pH value of the sodium tungstate mixture is adjusted to 7-8 by using 20% ammonia water, and the precipitate is obtained after aging for 18 h; then the precipitate is washed 4 times with deionized water and dried at 130℃ for 2.5 h; then the high-atomic-number metal core layer is obtained by calcining at 300℃ for 6 h under nitrogen protection.

[0070] S2, the high-atomic-number metal core layer obtained in step S1 is mixed with 15% of iron nitrate and added to deionized water, and stirred with a stirrer at a speed of 500 r / min for 5 h to obtain a multi-metal mixture, then the pH value of the multi-metal mixture is adjusted to 7-8 by using 20% ammonia water, and the precipitate is obtained after aging for 18 h; then the precipitate is washed 4 times with deionized water and dried at 130℃ for 2.5 h; then the preliminary wrapped powder is obtained by calcining at 300℃ for 6 h under nitrogen protection.

[0071] S3, the preliminary wrapped powder obtained in step S2 is mixed with 80% of the rare earth salt and added to deionized water, and stirred with a stirrer at a speed of 500 r / min for 5 h to obtain a multi-metal mixture, then the pH value of the mixture is adjusted to 7-8 by using 20% ammonia water, and the precipitate is obtained after aging for 18 h; then the precipitate is washed 4 times with deionized water and dried at 130℃ for 2.5 h; then the secondary wrapped powder is obtained by calcining at 300℃ for 6 h under nitrogen protection; the secondary wrapped powder is calcined at 600℃ for 6 h under nitrogen protection, and then air-rotating blowing is performed for 0.4 h; then air-rotating blowing is performed at 1000℃ for 8 min to obtain the core-shell heterogeneous gradient structure anti-ionizing radiation powder with a density of 4.79 g / cm 3 .

[0072] The rare earth salt includes a mixture of lanthanum nitrate, cerium nitrate and gadolinium nitrate, and the mass percentage of the lanthanum nitrate, the cerium nitrate and the gadolinium nitrate is 60%:25%:15%. The power of the air flow crushing is 20 KW, and the speed of the air-rotating blowing is 3.5 m / s.

[0073] 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.

[0074] like Figure 2 As 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.

[0075] Examples 2-3 and Comparative Examples 1-6

[0076] 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.

[0077] 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.

[0078] Density test is carried out using a density tester.

[0079] 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.

[0080] Table 1 Performance test of Examples 1 to 3 and Comparative Examples 1 to 6

[0081]

[0082] 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.

[0083] When the high-atomic-number metal salt is too much (Comparative Example 1), although the radiation resistance of the sheet tends to increase, the density of the obtained core-shell heterogeneous gradient structure anti-ionizing radiation powder is large, which is not conducive to the demand for light weight. When the high-atomic-number metal salt is too little (Comparative Example 2), the radiation resistance of the sheet is weakened. The change of the proportion of the high-atomic-number metal salt has a greater impact on the density of the obtained core-shell heterogeneous gradient structure anti-ionizing radiation powder. In practical applications, the density of the material can be effectively reduced while the radiation resistance is basically maintained by constructing the core-shell heterogeneous gradient structure.

[0084] When the amount of low-atomic-number metal salt is too much (Comparative Example 4), the radiation resistance of the sheet will be affected to some extent. When the amount of low-atomic-number metal salt is too little (Comparative Example 3), the amount of high-atomic-number metal salt is relatively large at this time, and the density of the anti-ionizing radiation powder is large.

[0085] When the amount of rare earth salt is too little (Comparative Example 5), the density of the anti-ionizing radiation powder is large; when the amount of rare earth salt is too much (Comparative Example 6), the radiation resistance of the sheet prepared from the core-shell heterogeneous gradient structure anti-ionizing radiation powder is reduced.

[0086] Examples 4-5 and Comparative Examples 7-8

[0087] A preparation method of a core-shell heterogeneous gradient structure anti-ionizing radiation powder, which differs from Example 1 in that in step S4, the mass ratio of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the radiation-resistant sheet is different, and other aspects are substantially the same as those of Example 1, which will not be repeated here.

[0088] A universal material testing machine (tension machine) is used to detect the tensile strength of the anti-radiation film.

[0089] Table 2 Performance test of Examples 4-5 and Comparative Examples 7-8

[0090]

[0091] As can be seen from Table 2, when the mass percentage of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the anti-radiation sheet is 60% to 80%, the overall performance of the core-shell heterogeneous gradient structure anti-ionizing radiation powder and the anti-radiation sheet is better. With the increase of the content of the anti-ionizing radiation powder, the X-ray and gamma-ray protection performance of the anti-radiation sheet gradually increases, but the tensile strength gradually decreases. When the mass percentage of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the anti-radiation sheet is higher than 80%, the tensile strength of the anti-radiation sheet is obviously poor. This may be because when the mass percentage of the core-shell heterogeneous gradient structure anti-ionizing radiation powder is too high, the cross-linking action between the molecular chains of the natural rubber is destroyed, thereby affecting the tensile strength, and finally resulting in that the anti-radiation sheet cannot be used. When the mass percentage of the core-shell heterogeneous gradient structure anti-ionizing radiation powder in the anti-radiation sheet is lower than 60%, the anti-radiation performance of the anti-radiation sheet is poor, and cannot well meet the daily protection requirements.

[0092] Example 6

[0093] A preparation method of a core-shell heterogeneous gradient structure anti-ionizing radiation powder, which is different from example 1 in that in step S3, in addition to lanthanum nitrate, cerium nitrate and gadolinium nitrate, samarium nitrate is also included, and the mass percentage of them is 60%:25%:10%:5%, and other aspects are substantially the same as those of example 1, which will not be repeated here.

[0094] Table 3 performance test of example 1 and example 6

[0095]

[0096] 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 of X-ray and gamma-ray is 71.982% and 57.627% respectively, which indicates that the addition of samarium nitrate not only reduces the density, but also improves the protection performance of X-ray and gamma-ray, and the tensile strength of the sheet is also increased. Therefore, it can be seen that multi-element compounding can optimize the density of the core-shell heterogeneous gradient structure anti-ionizing radiation powder and the comprehensive performance of the sheet.

[0097] Examples 7-8 and comparative examples 9-11

[0098] A preparation method of a core-shell heterogeneous gradient structure anti-ionizing radiation powder, which is different from example 1 in that in step S3, the mass percentage of lanthanum nitrate, cerium nitrate and gadolinium nitrate in the rare earth salt is different, and other aspects are substantially the same as those of example 1, which will not be repeated here.

[0099] Table 4 performance test of examples 7-8 and comparative examples 9-11

[0100]

[0101] From Table 4, it can be seen that when the mass percentage of lanthanum nitrate, cerium nitrate and gadolinium nitrate is changed within the appropriate range, the overall performance of the obtained core-shell heterogeneous gradient structure anti-ionizing radiation powder and anti-radiation sheet is good, and when the content of cerium nitrate and gadolinium nitrate is higher, the obtained anti-radiation sheet has better protection performance.

[0102] From the data of Comparative Examples 9-11, it can be seen that when the rare earth metal salt is not a mixture of lanthanum nitrate, cerium nitrate and gadolinium nitrate, but only one or two of them, the anti-radiation performance of the obtained anti-radiation sheet is obviously poorer, indicating that lanthanum nitrate, cerium nitrate and gadolinium nitrate synergize with each other to achieve better anti-radiation effect. At the same time, when the content of cerium nitrate and gadolinium nitrate is higher, the obtained anti-radiation sheet has better protection performance.

[0103] Comparative Example 12

[0104] A preparation method of a core-shell heterogeneous gradient structure anti-ionizing radiation powder, which is different from Example 1 in that in step S3, no secondary calcination is performed, and other aspects are substantially the same as those of Example 1, which will not be repeated here.

[0105] Comparative Example 13

[0106] A preparation method of an anti-ionizing radiation powder, which is different from Example 1 in that the high-atomic-number metal salt, the low-atomic-number metal salt and the rare earth salt are directly blended to form a mixed solution, and then the mixed solution is aged, washed, dried, once calcined, twice calcined, airflow pulverized and air-rotary purged to obtain the anti-ionizing radiation powder, and other aspects are substantially the same as those of Example 1, which will not be repeated here.

[0107] Comparative Example 14

[0108] A preparation method of a core-shell heterogeneous gradient structure anti-ionizing radiation powder, which is different from Example 1 in that the rare earth metal oxide is the core layer and the high-atomic-number metal oxide is the surface layer in the obtained core-shell heterogeneous gradient structure anti-ionizing radiation powder, and the mass percentage of the rare earth salt, the low-atomic-number metal salt and the high-atomic-number metal salt is 5%:15%:80%. Other aspects are substantially the same as those of Example 1, which will not be repeated here.

[0109] Comparative Example 15

[0110] A preparation method of a core-shell heterogeneous gradient structure anti-ionizing radiation powder, comprising the following steps:

[0111] The high atomic number metal salt, the low atomic number metal salt and the rare earth salt are weighed according to the mass percentage of 5%:15%:80% of the high atomic number metal salt, the low atomic number metal salt and the rare earth salt, that is, the mass percentage of the high atomic number metal salt, the low atomic number metal salt and the rare earth salt is 5%:15%:80%.

[0112] S1, 5% of sodium tungstate is added to deionized water, and stirred with a stirrer at a speed of 500 r / min for 5 h to obtain a sodium tungstate mixture; then the pH value of the sodium tungstate mixture is adjusted to 7-8 by using 20% ammonia water, and the precipitate is obtained after aging for 18 h;

[0113] S2, 15% of the iron nitrate solution is added to the precipitate of step S1, and stirred with a stirrer at a speed of 500 r / min for 5 h to obtain a multi-metal mixture, then the pH value of the sodium tungstate mixture is adjusted to 7-8 by using 20% ammonia water, and the precipitate is obtained after aging for 18 h;

[0114] S3, 80% of the rare earth salt solution is added to the precipitate of step S2, and stirred with a stirrer at a speed of 500 r / min for 5 h to obtain a multi-metal mixture, then the pH value of the sodium tungstate mixture is adjusted to 7-8 by using 20% ammonia water, and the precipitate is obtained after aging for 18 h; then the precipitate is washed 4 times with deionized water, and dried at 130℃ for 2.5 h; then calcined at 300℃ for 6 h under nitrogen protection, to obtain a secondary coated powder; the secondary coated powder is calcined at 600℃ for 6 h under nitrogen protection, and then air flow crushed for 0.4 h, to obtain multi-rare earth nano particles; then air-rotating blowing at 1000℃ for 8 min, to obtain a core-shell heterogeneous gradient structure anti-ionizing radiation powder.

[0115] The rare earth salt includes a mixture of lanthanum nitrate, cerium nitrate and gadolinium nitrate, and the mass percentage of the lanthanum nitrate, the cerium nitrate and the gadolinium nitrate is 60%:25%:15%. The power of the air flow crushing is 20 KW, and the speed of the air-rotating blowing is 3.5 m / s.

[0116] S4, the core-shell heterogeneous gradient structure anti-ionizing radiation powder is treated by spraying with a silane coupling agent, and then dried and 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 70%.

[0117] Table 5, performance test of comparative examples 12-15

[0118]

[0119] As can be seen from the data of the comparative example 12 in Table 5, when no secondary calcination is performed in step S3, the density of the obtained ionizing radiation-proof powder with core-shell heterogeneous gradient structure increases, and meanwhile the anti-radiation performance of the ionizing radiation-proof powder decreases, which is probably because, during the secondary calcination, the rare earth oxides in the rare earth metal oxide layer of the surface layer are further bonded, the combination structure between molecules is changed, the powder is more stable, the mutual synergistic effect between various substances is optimal, and thus the powder is lighter, and meanwhile the anti-radiation performance of the anti-radiation film is more stable.

[0120] As can be seen from the data of the comparative example 13, when the high-atomic-number metal salt, the low-atomic-number metal salt and the rare earth salt are directly blended, the ionizing radiation-proof powder obtained at this time cannot realize the core-shell heterogeneous gradient structure, and thus the anti-radiation performance of the obtained anti-radiation sheet decreases, which illustrates the importance of the core-shell heterogeneous gradient structure of the present application.

[0121] As can be seen from the data of the comparative example 14, when the rare earth metal oxide is used as the core layer and the high-atomic-number metal oxide is used as the surface layer, the anti-radiation performance of the anti-radiation sheet prepared from the obtained ionizing radiation-proof powder with core-shell heterogeneous gradient structure decreases obviously, which illustrates that the arrangement relationship of the core-shell structure also affects the anti-radiation performance.

[0122] As can be seen from the data of the comparative example 15, when only the sol-gel method is used to prepare the core layer and the intermediate layer, and then the sol-gel method and calcination are combined after the outermost rare earth salt is coated, the density of the obtained ionizing radiation-proof powder with core-shell heterogeneous gradient structure and the performance of the anti-radiation sheet are both affected, which is probably because the layered structure of the obtained ionizing radiation-proof powder with core-shell heterogeneous gradient structure is not obvious, i.e., the layer structure is not neat, and thus the electron cloud density arrangement of the powder and the mutual synergistic effect between different layers are affected, and further the performance is affected.

[0123] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are only examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solutions of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, and other modes constructed by combining part of the configuration 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 calcining in sequence 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, and then sequentially performing aging, washing, drying, primary calcination, secondary calcination, air flow pulverization, and air rotary purging to obtain a core-shell heterogeneous gradient structure ionizing radiation protection powder; The high atomic number metal salt includes one or more of sodium metatungstate, tantalum oxalate, and bismuth nitrate; the low atomic number metal salt includes one or more of ferric nitrate, zinc nitrate, and stannous nitrate; The mass percentages of the high atomic number metal salt, the low atomic number metal salt and the rare earth salt are 2% to 10%: 8% to 20%: 70% to 90%; The rare earth salt includes a mixture of lanthanum nitrate, cerium nitrate, and gadolinium nitrate; The aging specifically includes: 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.

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 lanthanum nitrate, cerium nitrate, and gadolinium nitrate are 50%-70%: 20%-30%: 10%-20%.

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 further comprises one or more of samarium nitrate, europium nitrate, praseodymium nitrate, neodymium nitrate, dysprosium nitrate, erbium nitrate, thulium nitrate, and ytterbium nitrate.

4. 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.

5. 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.

6. The method for preparing the core-shell heterogeneous gradient structure ionizing radiation protection powder according to claim 1, characterized in that: The washing is specifically: 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.

7. 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 6, 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.

8. An application of the core-shell heterogeneous gradient structure ionizing radiation protection powder according to claim 7, 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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