Heat treatment method of aluminum-based boron carbide composite material

Abstract

The embodiment of the invention provides a heat treatment method of an aluminum-based boron carbide composite material, and the heat treatment method comprises the following steps: carrying out electric pulse auxiliary thermal field treatment on the aluminum-based boron carbide composite material, and carrying out electric pulse auxiliary thermal field treatment on the aluminum-based boron carbide composite material, and the temperature of the thermal field is 500-580 DEG C. A heat treatment technology for a microstructure of an aluminum-based boron carbide composite material mostly adopts pure thermal field treatment at present, and has the problems of low treatment efficiency and long treatment time. In the embodiment of the invention, the problems are effectively improved by utilizing the unique thermal effect and non-thermal effect of the electric pulse, and the microstructure and high-temperature mechanical properties of the composite material are regulated and controlled by introducing the electric pulse treatment on the basis of the thermal field, so that the high-temperature strength and high-temperature plasticity of the composite material can be improved within a short time.

Description

Technical Field

[0001] The present application relates to the technical field of neutron absorption materials, and in particular to a heat treatment method for aluminum-based boron carbide composite materials. Background Art

[0002] Neutron-absorbing materials, as an important material for nuclear power, play a vital role in the storage and transportation of spent nuclear fuel. Spent fuel storage is primarily categorized into two methods: dry storage and wet storage. Wet storage involves placing spent fuel in racks made of neutron-absorbing material and immersing the fuel in boron-containing water. Heat released by the fuel is promptly removed through a pool water cooling system. Dry storage, on the other hand, involves placing spent fuel, once cooled to a safe temperature, into storage containers and circulating air or inert gas for cooling. Because the storage process does not require a complex water-cooling circulation system and produces no secondary pollutants, dry storage significantly reduces management costs and offers far greater resistance to man-made and natural disasters than wet storage. However, this method places higher demands on high-temperature mechanical properties.

[0003] Aluminum-based boron carbide has broad prospects as a neutron-absorbing material in the field of dry storage of spent fuel. The synergistic improvement of its high-temperature strength and plasticity is crucial to the safety of spent fuel storage and transportation. The traditional preparation method of aluminum-based boron carbide is powder metallurgy, which utilizes the self-generated amorphous aluminum oxide nanofilm on the surface of aluminum powder and combines particle size regulation to achieve controllable introduction of nanophase, thereby improving the high-temperature strength of aluminum-based boron carbide. Then, through heat treatment, the continuous oxide film on the surface of the aluminum powder is broken, the morphology is transformed, and the crystal state is transformed to promote the improvement of its high-temperature plasticity. However, traditional heat treatment methods have the problems of low efficiency and high energy consumption. To this end, it is necessary to provide a more efficient and environmentally friendly heat treatment method for aluminum-based boron carbide composite materials that takes into account both high-temperature strength and high-temperature plasticity. Summary of the Invention

[0004] The main purpose of the embodiments of the present application is to provide a heat treatment method for aluminum-based boron carbide composite materials that is more efficient and environmentally friendly while taking into account both high-temperature strength and high-temperature plasticity.

[0005] To achieve the above objectives, the first aspect of the present application provides a heat treatment method for an aluminum-based boron carbide composite material, the heat treatment method comprising the following steps:

[0006] The aluminum-based boron carbide composite material is subjected to electric pulse assisted thermal field treatment, which includes placing the aluminum-based boron carbide composite material in a thermal field and applying a pulse current. The temperature of the thermal field is 500°C to 580°C.

[0007] In some embodiments of the present application, the temperature of the thermal field may be, for example, 500°C, 505°C, 510°C, 515°C, 520°C, 525°C, 530°C, 535°C, 540°C, 545°C, 550°C, 555°C, 560°C, 565°C, 570°C, 575°C, or 580°C.

[0008] In some embodiments of the present application, the frequency of the pulse current is 1 Hz to 300 Hz, for example, it can be 1 Hz, 2 Hz, 3 Hz, 4 Hz, 5 Hz, 6 Hz, 8 Hz, 10 Hz, 15 Hz, 20 Hz, 30 Hz, 40 Hz, 50 Hz, 60 Hz, 70 Hz, 80 Hz, 90 Hz, 100 Hz, 110 Hz, 120 Hz, 130 Hz, 140 Hz, 150 Hz, 160 Hz, 170 Hz, 180 Hz, 190 Hz, 200 Hz, 210 Hz, 220 Hz, 230 Hz, 240 Hz, 250 Hz, 260 Hz, 270 Hz, 280 Hz, 290 Hz, or 300 Hz.

[0009] In some embodiments of the present application, the voltage of the pulse current is 1V to 200V, for example, it can be 1V, 2V, 3V, 4V, 5V, 6V, 8V, 10V, 15V, 20V, 30V, 40V, 50V, 60V, 70V, 80V, 90V, 100V, 110V, 120V, 130V, 140V, 150V, 160V, 170V, 180V, 190V, or 200V.

[0010] In some embodiments of the present application, the treatment time of electric pulse assisted thermal field treatment is 5 min to 180 min, for example, it can be 5 min, 6 min, 8 min, 10 min, 15 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, or 180 min.

[0011] In some embodiments of the present application, the aluminum-based boron carbide composite material is an extruded aluminum-based boron carbide composite material.

[0012] In some embodiments of the present application, the aluminum-based boron carbide composite material is prepared by powder metallurgy using aluminum powder and boron carbide powder as raw materials.

[0013] In some embodiments of the present application, the median particle size of the aluminum powder is below 3 μm, such as 1 μm to 3 μm, and specifically can be 3 μm, 2.9 μm, 2.8 μm, 2.7 μm, 2.6 μm, 2.5 μm, 2.4 μm, 2.3 μm, 2.2 μm, 2.1 μm, 2 μm, 1.9 μm, 1.8 μm, 1.7 μm, 1.6 μm, 1.5 μm, 1.4 μm, 1.3 μm, 1.2 μm, 1.1 μm, 1 μm.

[0014] In some embodiments of the present application, the median particle size of the boron carbide powder is 4 μm to 20 μm, for example, it can be 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm.

[0015] In some embodiments of the present application, the powder metallurgy method includes the steps of mixing and cold isostatic pressing.

[0016] In some embodiments of the present application, the mixing includes dry mixing the aluminum powder and the boron carbide powder, for example, mixing the aluminum powder and the boron carbide powder by at least one of mechanical force and air flow.

[0017] In some embodiments of the present application, the pressure of cold isostatic pressing is 200 MPa to 400 MPa, for example, it can be 200 MPa, 220 MPa, 240 MPa, 250 MPa, 260 MPa, 280 MPa, 300 MPa, 320 MPa, 340 MPa, 350 MPa, 360 MPa, 380 MPa, or 400 MPa.

[0018] In some embodiments of the present application, the pressing time of cold isostatic pressing is 30s to 10min, for example, it can be 30s, 45s, 1min, 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min, or 10min.

[0019] In some embodiments of the present application, the mass percentage of boron carbide powder in the raw material is 5% to 20%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%.

[0020] In some embodiments of the present application, the mass percentage of aluminum powder in the corresponding raw material is 80% to 95%, for example, it can be 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, or 95%.

[0021] In some embodiments of the present application, the powder metallurgy method further includes sintering and hot deformation steps after cold isostatic pressing.

[0022] In some embodiments of the present application, the sintering temperature is 400-500°C, for example, it can be 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, or 500°C.

[0023] In some embodiments of the present application, the sintering time is 30 min to 24 h, for example, it can be 30 min, 45 min, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, or 12 h.

[0024] In some embodiments of the present application, impurities are removed before sintering.

[0025] In some embodiments of the present application, impurity removal includes treatment at 150-300°C for 10-60 min, and the specific temperature can be 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, and the treatment time can be 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min.

[0026] In some embodiments of the present application, the thermal deformation process includes thermal extrusion.

[0027] In some embodiments of the present application, the extrusion temperature of hot extrusion is 400-600°C, for example, it can be 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, and 600°C.

[0028] In some embodiments of the present application, the extrusion ratio of hot extrusion is 3 to 20:1, for example, it can be 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or 20:1.

[0029] In a second aspect of the present application, an aluminum-based boron carbide composite material is proposed. The aluminum-based boron carbide composite material is obtained by the aforementioned heat treatment method.

[0030] In a third aspect of the present application, a spent fuel storage device is provided. The spent fuel storage device includes the aforementioned aluminum-based boron carbide composite material.

[0031] In some embodiments of the present application, the spent fuel storage device is a spent fuel dry storage device.

[0032] The beneficial effects of the present invention are:

[0033] Currently, pure thermal field treatment is the most common heat treatment method for the microstructure of aluminum-based boron carbide composites, which suffers from low treatment efficiency and long treatment times. However, this application utilizes the unique thermal and non-thermal effects of electric pulses to effectively improve these issues. By introducing electric pulses into the heat treatment process based on pure thermal field treatment to regulate the microstructure and high-temperature mechanical properties of the composite material, the high-temperature strength and high-temperature plasticity of the composite material can be improved in a short period of time. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. The terms "first", "second", etc. are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. "At least one" refers to one or more, and "a plurality" refers to two or more.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing the embodiments of this application only and are not intended to limit this application.

[0036] The embodiments described in the embodiments of this application are intended to more clearly illustrate the technical solutions of the embodiments of this application and do not constitute a limitation on the technical solutions provided by the embodiments of this application. Those skilled in the art will appreciate that with the evolution of technology and the emergence of new application scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0037] The present invention will be further described in detail below through specific examples. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0038] Example 1

[0039] This embodiment provides an aluminum-based boron carbide, and the preparation process is as follows:

[0040] (1) Ultrafine aluminum powder with a median particle size of 1.5 μm (Beijing Huisheng New Material Technology Co., Ltd.) and boron carbide powder with a median particle size of 7.0 μm (Mudanjiang Jingangzuan Boron Carbide Co., Ltd.) were taken in a mass ratio of 9:1, and 10 wt% B4C / Al mixed powder was obtained after dry mixing.

[0041] (2) Place the B4C / Al mixed powder into the cold pressing sleeve and use a mechanical pump to evacuate the filled and compacted cold pressing sleeve to 10 -2 Pa, and then cold isostatically pressed at 400 MPa for 1 min to obtain a cold isostatically pressed green body with a density of about 96%.

[0042] (3) Place the green body into the sintering furnace and evacuate until the vacuum drops below 1 Pa. -3 Pa, start heating, and keep it warm for 30 minutes when the temperature reaches 200℃ to remove free water on the surface of aluminum powder and impurity gas in the gap between materials; then reduce the vacuum degree to 10 -3 After Pa, the temperature was raised to 420℃ for vacuum sintering for 12h, and finally extruded by hot extrusion process (extrusion temperature 465℃, extrusion ratio 5:1) to obtain extruded aluminum-based boron carbide composite material.

[0043] (4) Place the extruded aluminum-based boron carbide composite material into a heat treatment furnace. At the same time, fix one end of the extruded aluminum-based boron carbide composite material to the electrode of the pulse power supply. Use a multimeter to check to ensure that the green body is in good contact with the electrode. Then turn on the power of the heat treatment furnace, increase the temperature, and connect the pulse power supply at the same time. Adjust the pulse current parameters until the set experimental temperature is reached and stabilized. Perform electric pulse assisted thermal field treatment to obtain the aluminum-based boron carbide composite material. The electric pulse parameters are: voltage 80V, frequency 120Hz, thermal field temperature 500℃, and treatment time 2h. After the set time is reached, turn off the power of the heat treatment furnace and the pulse power supply. After the sample cools down, remove it for subsequent testing.

[0044] Example 2

[0045] This embodiment provides an aluminum-based boron carbide. The preparation process is different from that of Example 1, except that the thermal field temperature during the heat treatment in step (4) is 540° C. and the treatment time is 1 hour.

[0046] Example 3

[0047] This embodiment provides an aluminum-based boron carbide. The preparation process is different from that of Example 1, except that the thermal field temperature during the heat treatment in step (4) is 540° C. and the treatment time is 2 h.

[0048] Example 4

[0049] This embodiment provides an aluminum-based boron carbide. The preparation process is different from that of Example 1, except that the thermal field temperature during the heat treatment in step (4) is 580° C. and the treatment time is 0.5 h.

[0050] Comparative Example 1

[0051] This comparative example provides an aluminum-based boron carbide. The preparation process is different from that of Example 1, except that step (4) is not included.

[0052] Comparative Example 2

[0053] This comparative example provides an aluminum-based boron carbide. The preparation process is different from that of Example 1, except that step (4) is replaced by: continuing to raise the temperature to 500°C, keeping the temperature for 24 hours and performing vacuum sintering to obtain an aluminum-based boron carbide composite material.

[0054] Comparative Example 3

[0055] This comparative example provides an aluminum-based boron carbide. The preparation process is compared with that of Example 1, except that the thermal field temperature during the heat treatment in step (4) is 450° C. and the treatment time is 2 h.

[0056] Comparative Example 4

[0057] This comparative example provides an aluminum-based boron carbide. The preparation process is compared with that of Example 1, except that the thermal field temperature during the heat treatment in step (4) is 600° C. and the treatment time is 0.5 h.

[0058] The aluminum-based boron carbides prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were subjected to tensile tests, as follows:

[0059] Experimental equipment: MTS-Landmark 370.25 room high temperature universal tensile machine;

[0060] High-temperature stretching parameters: stretching after keeping at 350℃ for 30min, stretching rate 1.2mm / s.

[0061] The test results are shown in Table 1:

[0062] Table 1. Tensile test results

[0063]

[0064]

[0065] Comparative Example 2 uses a traditional heat treatment method. Compared with the initial sample in Comparative Example 1 that has not been heat treated, its high-temperature plasticity (elongation at break) increases by more than 40%, but at the same time, the high-temperature strength (tensile strength) decreases to 88% of the initial sample. Compared with the traditional heat treatment method in Comparative Example 2, Examples 1 to 4 that use electric pulse assisted thermal field treatment have slightly higher high-temperature strength, and in some cases can be restored to a level close to that of the initial sample; at the same time, the high-temperature plasticity has been further improved, with an amplitude of more than 25%. On the other hand, the processing time required for this method is shorter and the energy consumption is lower. In addition, the thermal field temperature in Comparative Example 3 is relatively low. Although it has undergone electric pulse assisted thermal field treatment, the performance of the treated aluminum-based boron carbide is relatively close to that of the initial sample in Comparative Example 1, and there is no significant improvement. Due to the excessively high thermal field temperature in Comparative Example 4, although the high-temperature plasticity has been greatly improved, its high-temperature tensile strength has decreased significantly.

[0066] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A heat treatment method for aluminum-based boron carbide composite materials, characterized in that: The following steps are involved: The aluminum-based boron carbide composite material is subjected to electric pulse assisted thermal field treatment, wherein the electric pulse assisted thermal field treatment comprises placing the aluminum-based boron carbide composite material in a thermal field and applying a pulse current, wherein the temperature of the thermal field is 500° C. to 580° C.

2. The heat treatment method according to claim 1, characterized in that The frequency of the pulse current is 1 Hz to 300 Hz, and / or the voltage of the pulse current is 1 V to 200 V.

3. The heat treatment method according to claim 1, characterized in that The treatment time of the electric pulse assisted thermal field treatment is 5 minutes to 180 minutes.

4. The heat treatment method according to claim 1, characterized in that The aluminum-based boron carbide composite material is prepared by a powder metallurgy method using aluminum powder and boron carbide powder as raw materials.

5. The heat treatment method according to claim 4, characterized in that The powder metallurgy method includes the steps of mixing materials and cold isostatic pressing.

6. The heat treatment method according to claim 5, characterized in that The mixing comprises dry mixing of aluminum powder and boron carbide powder.

7. The heat treatment method according to claim 5, characterized in that The cold isostatic pressing comprises pressing at a pressure of 200 MPa to 400 MPa for 2 to 10 minutes.

8. The heat treatment method according to claim 4, characterized in that The mass percentage of boron carbide powder in the raw material is 5-20%.

9. Aluminum-based boron carbide composite material, characterized in that: The aluminum-based boron carbide composite material is obtained by the heat treatment method according to any one of claims 1 to 8.

10. Spent fuel storage device, characterized in that: Including the aluminum-based boron carbide composite material according to claim 9.

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