10B-enriched ZrB2 ceramic as well as preparation method and application thereof

Abstract

The invention relates to the technical field of nuclear energy materials, and discloses a 10B-enriched ZrB2 ceramic and a preparation method and application thereof.The preparation method comprises the following steps that ZrO2, H3BO3 and graphite powder are mixed, and a uniformly-dispersed mixed raw material is obtained; sintering the mixed raw material, and grinding and sieving a product obtained after sintering to obtain zirconium boride powder; performing compression molding on the zirconium boride powder obtained in the step S2, and then performing hot pressed sintering; after sintering is completed, cooling is conducted, and the 10B-enriched ZrB2 ceramic is obtained. The density of the ZrB2 ceramic is effectively improved and the mechanical property of the ZrB2 ceramic is enhanced by adopting a hot pressing sintering technology; meanwhile, the failure risk caused by pores or microcracks can be reduced due to the high density; the preparation method disclosed by the invention has the advantages of convenience in operation, low equipment requirement, short preparation period, low preparation cost, easiness in product control and the like, and is suitable for being popularized and used in the industry.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear energy materials, especially in the fields of nuclear engineering, radiation protection, high-temperature superconductivity, etc., and relates to a 10 B-enriched ZrB2 ceramic and its preparation method and application. Background Art

[0002] Since the 21st century, the energy issue has always been the focus of attention. As a new type of clean energy that is pollution-free and sustainable, nuclear energy has received extensive attention. The fuel pellets used in the most advanced third-generation nuclear power units (AP1000 nuclear power unit reactors) at present are mainly integral fuel burnable absorbers, usually a 10 B-enriched ZrB2 thin film is sputtered on the surface of UO2 fuel pellets.

[0003] The reason for choosing 10 B-enriched ZrB2 thin film is that 10 B has a relatively high neutron absorption cross-section, while ZrB2, as a super-high temperature material, has the advantages of high melting point, high thermal conductivity, good electrical conductivity, and heat shock resistance, and can still maintain high strength and stability under high-temperature corrosion conditions. It has been widely used in high-temperature thermal protection, electronic components, military composite materials, nuclear industry and other fields. Research shows that 10 B-enriched ZrB2 has good neutron absorption characteristics and anti-irradiation performance. Prepared by carbothermal reduction hot pressing sintering, 10 B-enriched ZrB2 ceramic materials have broad application prospects in the nuclear energy field. By 10 enriching B into ZrB2 ceramics, the absorption and shielding capabilities of the materials in a neutron radiation environment can be significantly improved, thereby enhancing their application value in nuclear technology.

[0004] The methods for preparing ZrB2 powder include chemical vapor deposition method, sol-gel method, liquid phase method, direct synthesis method, carbothermal reduction method, etc. For 10 B-enriched ZrB2 powder, 10 the raw material price of B is very expensive. In order to facilitate industrial production, it is most appropriate to choose the low-cost carbothermal reduction method. However, due to the low conversion rate of the carbothermal reduction method and the existence of multiple side reactions in the reaction system, it may lead to a relatively high content of product impurities (ZrC, B4C and other phases); at the same time, the reaction temperature is high (>1600 °C) and the time is long, and the synthesized powder particles are coarse, resulting in low sintering activity and it is difficult to obtain a highly dense ceramic block. And the integral fuel burnable absorber ZrB2 coating used in the AP1000 nuclear power unit reactor has relatively high requirements for its chemical purity. Therefore, the sintering densification of the target material (ZrB2 ceramic) plays a crucial role in the preparation of the ZrB2 coating.

[0005] Therefore, there is an urgent need for a 10 ZrB2 ceramic enriched with B and its preparation method and application to solve the above technical problems. Summary of the Invention

[0006] In view of the deficiencies of the above-mentioned prior art, the present invention aims to provide a 10 ZrB2 ceramic enriched with B and its preparation method and application, to solve the problems of difficult high-efficiency enrichment of B and structural uniformity in the existing synthesis technology, and to improve the neutron absorption performance and structural stability of ZrB2 ceramic in a high-radiation environment. 10 To achieve the above object, the present invention is implemented according to the following technical scheme:

[0007] A

[0008] preparation method of 10 ZrB2 ceramic enriched with B, comprising the following steps:

[0009] S1, mixing raw material powders

[0010] Mix ZrO2 (zirconia), H3BO3 (boric acid) and graphite powder to obtain a uniformly dispersed mixed raw material; the molar ratio of ZrO2, H3BO3, and graphite powder is (1 to 1.2):(2.8 to 3.0):(5.2 to 5.4);

[0011] The H3BO3 is 10 H3BO3 enriched with B;

[0012] S2, synthesizing ZrB2 (zirconium boride) powder

[0013] Sinter the mixed raw material, and grind and screen the product obtained after sintering to obtain zirconium boride powder;

[0014] S3, hot pressing and sintering to synthesize 10 ZrB2 ceramic material enriched with B

[0015] Press the zirconium boride powder obtained in step S2 into a mold and then perform hot pressing sintering; after sintering is completed, cool to obtain 10 ZrB2 ceramic enriched with B.

[0016] Further preferably, the H3BO3 used is boric acid-10B, and its relative abundance is 92.0%.

[0017] Preferably, in step S1, the particle size of the graphite powder is 1 to 3 μm, the particle size of the H3BO3 is 1 to 3 μm, and the particle size of the ZrO2 is 100 nm.

[0018] Further preferably, the dispersant is ultrapure water.

[0019] Preferably, in the step S1, the mixing process is as follows: ZrO2, H3BO3, graphite powder, and a dispersant are mixed and then ball-milled; after mixing, a slurry is obtained, and the slurry is dried, ground, and sieved to obtain a uniformly dispersed mixed raw material.

[0020] Preferably, in the step S1, the dispersant is ultrapure water or ethanol;

[0021] The mass ratio of the sum of the masses of ZrO2, H3BO3, and graphite powder : ball-milling beads : dispersant is 1 : 1.8 : 1.5; the ball-milling speed is 90 r / min, and the ball-milling time is 12 - 18 h.

[0022] Specifically, in the step S1, the ball-milling time is 12 h; the ball-milling speed is 90 r / min; drying is carried out using a rotary evaporator, the rotary evaporation water bath temperature of the rotary evaporator is 65°C, and the speed is 60 r / min; the aperture of the sieve used for sieving is 200 mesh.

[0023] Preferably, in the step S2, the sintering process is as follows: under argon protection, the temperature is raised to 600 - 625°C, sintered at a constant temperature for 25 - 30 min, and then the temperature is raised to 1700 - 1900°C, and sintered at a constant temperature for at least 30 min.

[0024] More preferably, in the step S2, the sintering process is as follows: under argon protection, the temperature is raised to 600 - 625°C, sintered at a constant temperature for 25 - 30 min, and then the temperature is raised to 1900°C, and sintered at a constant temperature for at least 30 min.

[0025] Preferably, in the step S2, when the temperature is lower than 1000°C, the heating rate is 8 - 10°C / min; when the temperature is between 1000 - 1600°C, the heating rate is 5 - 8°C / min, and when the temperature is higher than 1600°C, the heating rate is 3 - 5°C / min; after sintering at 1700 - 1900°C is completed, the temperature is lowered to 1000°C at a rate of 8 - 10°C / min, and then cooled in the furnace to below 200°C.

[0026] Specifically, the sintering process of the step S2 is as follows:

[0027] ① The heating rate is 10°C / min, the temperature is raised to 600°C, and sintered at a constant temperature for 30 min;

[0028] ② The heating rate is 10°C / min, and the temperature is raised to 1000°C;

[0029] ③ The heating rate is 8°C / min, and the temperature is raised to 1600°C;

[0030] ④ The heating rate is 5°C / min, the temperature is raised to 1700 - 1900°C, and sintered at a constant temperature for 30 min;

[0031] ⑤Cooling rate: 10 °C / min, cool down to 1000 °C;

[0032] ⑥When the temperature is below 1000 °C, set the cooling procedure as furnace cooling.

[0033] Preferably, in step S3, the sintering process is as follows: Under the protection of an argon atmosphere, keep the temperature at 1980 °C and the pressure at 60 MPa for at least 30 minutes while maintaining pressure.

[0034] Preferably, in step S3, when the temperature is below 1000 °C, the heating rate is 8 - 10 °C / min and the pressure is 60 MPa; when the temperature is between 1000 - 1600 °C, the heating rate is 5 - 8 °C / min and the pressure is 60 MPa; when the temperature is above 1600 °C, the heating rate is 3 - 5 °C / min and the pressure is 60 MPa; after sintering is completed, cool down to 1000 °C at a rate of 8 - 10 °C / min with a pressure of 60 MPa, and then cool in the furnace to below 200 °C.

[0035] Specifically, the sintering process of step S3 is as follows:

[0036] ①Heating rate: 10 °C / min, heat up to 1000 °C, pressure 60 MPa;

[0037] ②Heating rate: 8 °C / min, heat up to 1600 °C, pressure 60 MPa;

[0038] ③Heating rate: 5 °C / min, heat up to 1980 °C, pressure 60 MPa, keep warm for 30 minutes;

[0039] ④Cooling rate: 10 °C / min, cool down to 1000 °C, pressure 60 MPa;

[0040] ⑤Release pressure when the temperature is below 1000 °C, set the cooling procedure as furnace cooling.

[0041] The ZrB2 (zirconium boride) powder prepared in step S2 of the present invention has a uniform particle size distribution, 10 The relative abundance of B isotope is high, reaching 91.7%.

[0042] Specifically, it includes the following steps:

[0043] S1, Mix raw material powders

[0044] Put ZrO2, H3BO3, graphite powder, dispersant, and ball milling balls into a ball milling tank, ball mill for at least 12 hours to obtain a slurry; dry the ball milled slurry in a rotary evaporator, then grind and sieve to obtain a uniformly dispersed mixed raw material powder;

[0045] S2, Synthesize ZrB2 (zirconium boride) powder

[0046] The mixed raw materials are dry-pressed into a disc shape, placed in a graphite crucible, and pre-sintered in a hot press furnace; the pre-sintering process is as follows: under argon protection, the temperature is raised to 600-625°C, and the temperature is kept for 25-30 minutes; after the pre-sintering is completed, the temperature is raised to 1700-1900°C, and the temperature is kept for at least 30 minutes to complete the reaction; the reaction product is ground in a mortar, and sieved to obtain ZrB2 powder;

[0047] S3, hot pressing sintering 10 B-enriched ZrB2 ceramic materials

[0048] The ZrB2 powder obtained in step S2 is pressed into a disc with a diameter of 30 mm in a tablet press, placed in a graphite crucible, loaded into a hot press furnace, and kept at a temperature of 1980°C and a pressure of 60 MPa for at least 30 minutes under the protection of an argon atmosphere; after sintering, it is cooled to below 200°C and sampled to obtain 10 B-enriched ZrB2 ceramics.

[0049] The present invention also includes the 10 B-enriched ZrB2 ceramics.

[0050] The present invention also includes 10 Application of B-enriched ZrB2 ceramics in radiation protection of nuclear engineering.

[0051] Working principle:

[0052] The present invention selects zirconium oxide, boric acid-10B and graphite as raw materials; disperses the raw material powder into a uniform mixed powder by a dispersant; pre-sinters in an argon atmosphere to obtain a fine, uniform, 10 The zirconium boride powder with high B abundance is finally obtained by hot pressing and sintering. 10 B-enriched ZrB2 ceramics. The obtained ceramic material 10 B has high enrichment, which solves the problem that is difficult to achieve in the synthesis process in the existing technology 10 The problem of efficient enrichment of B and poor uniformity of ceramic performance is expected to improve the stability and neutron absorption performance of ZrB2 ceramics in high radiation environments. The present invention has the advantages of easy operation and simple process.

[0053] Compared with the traditional preparation method, the present invention uses ultrapure water as a dispersant, which can effectively avoid raw material loss and improve the powder purity and particle uniformity. By controlling the sintering temperature and process parameters, the purity, particle uniformity and density of ZrB2 ceramics are significantly improved to meet the high-performance requirements of the integrated burnable poison (ZrB2 coating) in the AP1000 nuclear power unit. In addition, this method has the advantages of low equipment requirements, short cycle and controllable cost, can realize large-scale industrial production, and has important application prospects.

[0054] Beneficial effects:

[0055] 1. The present invention uses the raw material H3BO3 containing 10 B, and the obtained 10 B-enriched ZrB2 ceramics can effectively absorb thermal neutrons and have a low neutron scattering cross-section. Therefore, they are used as neutron absorption materials in nuclear reactors, which can reduce the reactor neutron flux and regulate the reactor dynamics characteristics;

[0056] 2. The 10 B-enriched ZrB2 ceramics prepared by the present invention can reduce the damage of nuclear radiation to materials by absorbing neutrons in a neutron radiation environment, and can effectively resist the structural damage caused by irradiation, thereby enhancing their service life in nuclear reactors and irradiation environments;

[0057] 3. The 10 B-enriched ZrB2 ceramics prepared by the present invention have good thermal conductivity, can work stably under high-temperature conditions, enhance the thermomechanical properties of the materials, increase their service life in extreme environments, and can improve the stability of the reactor system;

[0058] 4. The hot pressing sintering technology adopted by the present invention effectively improves the density of ZrB2 ceramics and enhances their mechanical properties; at the same time, the higher density can reduce the failure risk caused by pores or microcracks;

[0059] 5. The preparation method of the 10 B-enriched ZrB2 ceramics involved in the present invention has the advantages of convenient operation, low equipment requirements, short preparation cycle, low preparation cost, easy control of products, etc., and is suitable for popularization and use in the industry. Description of the drawings

[0060] Figure 1 XRD (X-ray diffraction spectrum) pattern of the mixed raw materials prepared in step (1) of Example 1;

[0061] Figure 2 XRD pattern of the ZrB2 powder prepared in step (2) of Example 1;

[0062] Figure 3XRD pattern of the mixed raw materials prepared in step (1) of Example 2;

[0063] Figure 4 XRD pattern of the ZrB2 powder prepared in step (2) of Example 2;

[0064] Figure 5 XRD pattern of the ZrB2 powder prepared in step (2) of Example 3;

[0065] Figure 6 XRD pattern of the ZrB2 powder prepared in step (2) of Example 4;

[0066] Figure 7 SEM (scanning electron microscope) image of the mixed raw materials prepared in step (1) of Example 2;

[0067] Figure 8 SEM image of the ZrB2 powder prepared in step (2) of Example 2;

[0068] Figure 9 Particle size distribution diagram of the ZrB2 powder prepared in step (2) of Example 2;

[0069] Figure 10 For the ZrB2 powder prepared in step (2) of Example 2 10 B isotope mass spectrometry detection results;

[0070] Figure 11 For the product prepared in step (3) of Example 2 10 SEM image of the B-enriched ZrB2 ceramic material. Detailed implementation mode

[0071] The present invention will be further described in detail below with specific examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not used to limit the present invention.

[0072] For all raw materials of the present invention, there is no special limitation on their purity. The present invention preferably uses industrial pure or conventional purity used in the art.

[0073] For the devices used in the present invention, those without special limitations are all commonly used devices in the art.

[0074] In the following examples, the H3BO3 powder used is boric acid-10B with a relative abundance of 92.0%.

[0075] Example 1

[0076] (1) Mixed raw material powder

[0077] 8.19 g of ZrO2 powder, 11.41 g of H3BO3 powder, and 4.28 g of graphite powder were added to a 100 ml reagent bottle. After mixing according to the mass ratio of raw materials∶ball milling beads∶ethanol of 1∶1.8∶1.5, drum ball milling was carried out for 12 h at a rotation speed of 90 r / min; Subsequently, a rotary evaporator was used to dry the mixed slurry at a rotation speed of 60 r / min and a water bath temperature of 65 °C; Immediately afterwards, the dried mixed powder was ground and passed through a 200-mesh sieve to obtain a uniformly dispersed mixed raw material;

[0078] (2) Synthesis of ZrB2 powder

[0079] The dried raw material powder was loaded into a dry pressing mold and dry pressed into a green body wafer in a tablet press; Subsequently, it was loaded into a graphite crucible and placed in a hot press furnace. It was heated from room temperature to 600 °C at a rate of 10 °C / min and pre-burned for 30 min in an argon atmosphere to convert H3BO3 into B2O3. Subsequently, it was heated to 1000 °C at a rate of 10 °C / min, then to 1600 °C at a rate of 8 °C / min, immediately followed by heating to 1900 °C at a rate of 5 °C / min and holding for 30 min; Finally, it was cooled to 1000 °C at a rate of 10 °C / min and then cooled with the furnace. The furnace was opened to take samples, which were ground in an agate mortar and passed through a 200-mesh sieve to obtain ZrB2 powder;

[0080] (3) Hot pressing sintering to prepare zirconium boride ceramics

[0081] The ZrB2 powder synthesized in step (2) was pressed into a wafer with a diameter of 30 mm in a tablet press and then placed in a graphite crucible, loaded into a hot press furnace, and heated from room temperature to 1000 °C at a rate of 10 °C / min in an argon atmosphere, then to 1600 °C at a rate of 8 °C / min, and subsequently to 1980 °C at a rate of 5 °C / min and held under a pressure of 60 MPa for 30 min. Immediately afterwards, it was cooled to 1000 °C at a rate of 10 °C / min and then depressurized and cooled with the furnace to obtain 10 B-enriched ZrB2 ceramics.

[0082] Example 2

[0083] (1) Mixed raw material powder

[0084] 8.19 g of ZrO2 powder, 11.41 g of H3BO3 powder, and 4.28 g of graphite powder were added to a 100 ml reagent bottle. After mixing according to the mass ratio of raw materials∶ball milling beads∶ultrapure water of 1∶1.8∶1.5, drum ball milling was carried out for 12 h at a rotation speed of 90 r / min; Subsequently, a rotary evaporator was used to dry the mixed slurry at a rotation speed of 60 r / min and a water bath temperature of 65 °C; Immediately afterwards, the dried mixed powder was ground and passed through a 200-mesh sieve to obtain a uniformly dispersed mixed raw material;

[0085] (2) Synthesis of ZrB2 powder

[0086] The dried raw material powder is loaded into a dry pressing mold, and placed in a tablet press to dry press into a green blank disc; then it is loaded into a graphite crucible and placed in a hot pressing furnace, and the temperature is increased from room temperature to 600°C at 10°C / min, and pre-burned in an argon atmosphere for 30 minutes to convert H3BO3 into B2O3, and then the temperature is increased to 1000°C at 10°C / min, and then the temperature is increased to 1600°C at 8°C / min, and then the temperature is increased to 1900°C at 5°C / min, and the temperature is kept for 30 minutes; finally, the temperature is reduced to 1000°C at 10°C / min, and then cooled with the furnace, the furnace is opened for sampling, and the ZrB2 powder is obtained by grinding in an agate mortar and passing through a 200-mesh sieve;

[0087] (3) Preparation of zirconium boride ceramics by hot pressing sintering

[0088] The ZrB2 powder synthesized in step (2) was pressed into a disc with a diameter of 30 mm in a tablet press, and then placed in a graphite crucible, loaded into a hot press furnace, and heated from room temperature to 1000°C at 10°C / min in an argon atmosphere, and then heated to 1600°C at 8°C / min, and then heated to 1980°C at 5°C / min and maintained at 60MPa for 30min, and then cooled to 1000°C at 10°C / min, and then released, cooled in the furnace, to obtain 10 B-enriched ZrB2 ceramics.

[0089] Example 3

[0090] (1) Mixed raw material powder

[0091] 8.19g ZrO2 powder, 11.41g H3BO3 powder and 4.28g graphite powder were added into a 100ml reagent bottle, and mixed according to the mass ratio of raw material: ball milling beads: ultrapure water of 1:1.8:1.5, and then roller milled for 12h at a speed of 90r / min; then the mixed slurry was dried by a rotary evaporator at a speed of 60r / min and a water bath temperature of 65°C; then the dried mixed powder was ground and passed through a 200-mesh sieve to obtain a uniformly dispersed mixed raw material;

[0092] (2) Synthesis of ZrB2 powder

[0093] The dried raw material powder is loaded into a dry pressing mold, and placed in a tablet press to dry press into a green blank disc; then it is loaded into a graphite crucible and placed in a hot pressing furnace, and the temperature is increased from room temperature to 600°C at 10°C / min, and pre-burned in an argon atmosphere for 30 minutes to convert H3BO3 into B2O3, and then the temperature is increased to 1000°C at 10°C / min, and then the temperature is increased to 1600°C at 8°C / min, and then the temperature is increased to 1800°C at 5°C / min, and the temperature is kept for 30 minutes; finally, the temperature is reduced to 1000°C at 10°C / min, and then cooled with the furnace, the furnace is opened for sampling, and the ZrB2 powder is obtained by grinding in an agate mortar and passing through a 200-mesh sieve;

[0094] (3) Preparation of zirconium boride ceramics by hot pressing sintering

[0095] The ZrB2 powder synthesized in step (2) was pressed into a wafer with a diameter of 30 mm in a tablet press and then placed in a graphite crucible, which was loaded into a hot press furnace. It was heated from room temperature to 1000 °C at a rate of 10 °C / min in an argon atmosphere, then heated to 1600 °C at a rate of 8 °C / min, and subsequently heated to 1980 °C at a rate of 5 °C / min and held at 60 MPa for 30 min. Immediately afterwards, it was cooled to 1000 °C at a rate of 10 °C / min and then depressurized, and cooled with the furnace to obtain 10 ZrB2 ceramics enriched in B.

[0096] Example 4

[0097] (1) Mixing raw material powders

[0098] 8.19 g of ZrO2 powder, 11.41 g of H3BO3 powder, and 4.28 g of graphite powder were added to a 100 ml reagent bottle. After mixing according to the mass ratio of raw material∶ball milling beads∶ultrapure water of 1∶1.8∶1.5, drum ball milling was carried out for 12 h at a rotation speed of 90 r / min; Subsequently, a rotary evaporator was used to dry the mixed slurry at a rotation speed of 60 r / min and a water bath temperature of 65 °C; Immediately afterwards, the dried mixed powder was ground and passed through a 200-mesh sieve to obtain a uniformly dispersed mixed raw material;

[0099] (2) Synthesis of ZrB2 powder

[0100] The dried raw material powder was loaded into a dry pressing mold and dry pressed into a green wafer in a tablet press; Subsequently, it was placed in a graphite crucible and then loaded into a hot press furnace. It was heated from room temperature to 600 °C at a rate of 10 °C / min and pre-sintered for 30 min in an argon atmosphere to convert H3BO3 into B2O3. Subsequently, it was heated to 1000 °C at a rate of 10 °C / min, then heated to 1600 °C at a rate of 8 °C / min, and immediately heated to 1700 °C at a rate of 5 °C / min and held for 30 min; Finally, it was cooled to 1000 °C at a rate of 10 °C / min and then cooled with the furnace. The furnace was opened to take samples, which were placed in an agate mortar, ground, and passed through a 200-mesh sieve to obtain ZrB2 powder;

[0101] (3) Preparation of zirconium boride ceramics by hot pressing sintering

[0102] The ZrB2 powder synthesized in step (2) was pressed into a wafer with a diameter of 30 mm in a tablet press and then placed in a graphite crucible, which was loaded into a hot press furnace. It was heated from room temperature to 1000 °C at a rate of 10 °C / min in an argon atmosphere, then heated to 1600 °C at a rate of 8 °C / min, and subsequently heated to 1980 °C at a rate of 5 °C / min and held at 60 MPa for 30 min. Immediately afterwards, it was cooled to 1000 °C at a rate of 10 °C / min and then depressurized, and cooled with the furnace to obtain10 B-enriched ZrB2 ceramics

[0103] Perform phase and morphology analysis on the raw materials, zirconium boride powder, and ceramics prepared in the above sub-examples:

[0104] As Figure 1 shown, it is the XRD (X-ray diffraction spectrum) pattern of the mixed raw materials prepared in step (1) of Example 1;

[0105] As Figure 2 shown, it is the XRD pattern of the ZrB2 powder prepared in step (2) of Example 1;

[0106] As Figure 3 shown, it is the XRD pattern of the mixed raw materials prepared in step (1) of Example 2;

[0107] As Figure 4 shown, it is the XRD pattern of the ZrB2 powder prepared in step (2) of Example 2;

[0108] As Figure 5 shown, it is the XRD pattern of the ZrB2 powder prepared in step (2) of Example 3;

[0109] As Figure 6 shown, it is the XRD pattern of the ZrB2 powder prepared in step (2) of Example 4;

[0110] As Figure 7 shown, it is the SEM (scanning electron microscope) image of the mixed raw materials prepared in step (1) of Example 2;

[0111] As Figure 8 shown, it is the SEM image of the ZrB2 powder prepared in step (2) of Example 2;

[0112] As Figure 9 shown, it is the particle size distribution diagram of the ZrB2 powder prepared in step (2) of Example 2;

[0113] As Figure 10 shown, it is the 10 B isotope mass spectrometry detection result of the ZrB2 powder prepared in step (2) of Example 2;

[0114] As Figure 11 shown, it is the 10 SEM image of the B-enriched ZrB2 ceramic material prepared in step (3) of Example 2.

[0115] Compare the XRD pattern of the mixed raw materials in Comparative Example 1 ( Figure 1 ) and the XRD pattern of the mixed raw materials in Example 2 ( Figure 3) It can be found that when ethanol is used as the dispersant, there is obvious loss of boron in the raw materials. The reason is that ethanol will react with boric acid under certain conditions, and then rotary evaporation causes boron loss. Therefore, from Figure 2 it can be found that the prepared ZrB2 powder is impure, and the main phase becomes ZrC (boron source loss, C excess); comparing the XRD pattern of the ZrB2 powder prepared in Example 1 ( Figure 2 ) and the XRD pattern of the ZrB2 powder prepared in Example 2 ( Figure 4 ), when ultrapure water is used as the dispersant, Figure 4 the XRD pattern in shows that there is no obvious loss of raw materials, good crystallinity, and high product purity.

[0116] Comparing the XRD patterns of the ZrB2 powders prepared in Example 2, Example 3, and Example 4 ( Figure 4 , Figure 5 , Figure 6 ), when the sintering temperature in step (2) of the example is reduced to 1800 °C and 1700 °C, as Figure 5 , Figure 6 shown, impurity phases such as graphite and ZrC appear in the zirconium boride powder, and the product purity is affected.

[0117] From Figure 7 the SEM image in, it is observed that the lamellar graphite, granular zirconia, boric acid, etc. in the mixed raw materials are evenly mixed and have good dispersibility. In addition, Figure 8 the SEM pattern of shows that the zirconium boride powder prepared using ultrapure water as the dispersant has good crystallinity and uniform particle size. Figure 9 The particle size distribution statistical chart of shows that the ZrB2 particles have uniform size and small particle size (average particle diameter is 6.07 μm), and single-phase ZrB2 powder is synthesized. Figure 10 The isotope mass spectrometry detection of shows that the prepared ZrB2 powder material 10 has a high relative abundance of B, reaching 91.7%, and successfully prepares 10 B-enriched ZrB2 powder material. Figure 11 is the SEM spectrum of the ZrB2 ceramic material prepared by hot pressing sintering in Example 2. The average relative density measured by the Archimedes drainage method reaches 95.19%, and a ZrB2 ceramic material with a relatively high density is successfully prepared 10 with B enrichment.

[0118] The technical solution of the present invention is not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solution of the present invention falls within the protection scope of the present invention.

Claims

1. A 10 method for preparing B-enriched ZrB2 ceramics, characterized in that: It includes the following steps: S1, mixing raw material powders Mix ZrO2, H3BO3 and graphite powder to obtain a uniformly dispersed mixed raw material; the molar ratio of ZrO2, H3BO3, and graphite powder is (1 - 1.2)∶(2.8 - 3.0)∶(5.2 - 5.4); The H3BO3 is enriched 10 H3BO3 containing B; S2, synthesizing ZrB2 powder Sinter the mixed raw material, and grind and screen the product obtained after sintering to obtain zirconium boride powder; S3, hot-press sintering synthesis 10 B-enriched ZrB2 ceramic material Press the zirconium boride powder obtained in step S2 into a mold and then perform hot - press sintering; After sintering is completed and cooling is carried out, 10 B-enriched ZrB2 ceramics are obtained.

2. A method for preparing a B-enriched ZrB2 ceramic according to claim 1, characterized in that: 10 In step S1, the particle size of the graphite powder is 1 - 3 μm, the particle size of H3BO3 is 1 - 3 μm, and the particle size of ZrO2 is 100 nm.

3. A method for preparing a 10 B-enriched ZrB2 ceramic, characterized in that: In step S1, the mixing process is as follows: Mix ZrO2, H3BO3, graphite powder, and a dispersant and then perform ball - milling. Ball - milling beads are used during the ball - milling process; after mixing, a slurry is obtained. The slurry is dried, ground, and screened to obtain a uniformly dispersed mixed raw material.

4. A method for preparing a 10 B-enriched ZrB2 ceramic, characterized in that: In step S1, the dispersant is ultrapure water or ethanol; The mass ratio of the sum of the masses of ZrO2, H3BO3, and graphite powder∶ball - milling beads∶dispersant is 1∶1.8∶1.5; the ball - milling speed is 90 r / min, and the ball - milling time is 12 - 18 h.

5. A method for preparing a B-enriched ZrB2 ceramic according to claim 1, characterized in that: 10 In step S2, the sintering process is: Under argon protection, heat up to 600 - 625 °C, hold for sintering for 25 - 30 min, then heat up to 1700 - 1900 °C, and hold for sintering for at least 30 min. ​ 6. The method for preparing a B-enriched ZrB2 ceramic according to claim 5, characterized in that: 10 In step S2, when the temperature is lower than 1000 °C, the heating rate is 8 - 10 °C / min; when the temperature is between 1000 - 1600 °C, the heating rate is 5 - 8 °C / min, when the temperature is higher than 1600 °C, the heating rate is 3 - 5 °C / min; after sintering at 1700 - 1900 °C, cool down to 1000 °C at a rate of 8 - 10 °C / min, and then cool down with the furnace to below 200 °C.

7. The method for preparing a 10 B-enriched ZrB2 ceramic according to claim 1, characterized in that: In step S3, the sintering process is as follows: Under argon atmosphere protection, keep the temperature at 1980 °C and the pressure at 60 MPa and hold for at least 30 min.

8. A 10 method for preparing B-enriched ZrB2 ceramics, characterized in that: In step S3, when the temperature is lower than 1000 °C, the heating rate is 8 - 10 °C / min and the pressure is 60 MPa; when the temperature is between 1000 - 1600 °C, the heating rate is 5 - 8 °C / min and the pressure is 60 MPa; when the temperature is higher than 1600 °C, the heating rate is 3 - 5 °C / min and the pressure is 60 MPa; After sintering, cool down to 1000 °C at a rate of 8 - 10 °C / min, with the pressure at 60 MPa, and then cool down with the furnace to below 200 °C.

9. Prepared by the preparation method according to any one of claims 1-8 10 B-enriched ZrB2 ceramic.

10. The application of the B-enriched ZrB2 ceramic as claimed in claim 9 in nuclear engineering radiation protection. 10 in nuclear engineering radiation protection.

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