Aluminum nitride coated short tungsten fiber toughened tungsten matrix composite and method of making

Abstract

The present application provides a kind of plated aluminum nitride short tungsten fiber tough tungsten-based composite material and its preparation method.The matrix of the composite material is tungsten matrix, and the toughening body is short tungsten fiber with aluminum nitride coating on the surface, wherein the addition amount of plated aluminum nitride short tungsten fiber is 10% to 50% (vol.%).Aluminum nitride coating is prepared on the surface of short tungsten fiber by surface plating technology, the plated aluminum nitride short tungsten fiber is mixed with raw powder in a certain proportion by ball milling, and then sintering is carried out by spark plasma sintering technology, the sintering temperature is 1500 to 2000 ℃, the sintering pressure is 50 to 80 MPa, and the holding and pressure holding time is 1 to 5 min.The plated aluminum nitride short tungsten fiber tough tungsten-based composite material involved in the present application can simultaneously improve the mechanical properties and thermal conductivity of tungsten material, and has the required strength and toughness and rapid heat conduction capacity as a plasma facing material.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy for preparing high-performance tungsten-based composite materials, specifically to a tungsten-based composite material toughened with aluminum nitride-coated short tungsten fibers and its preparation method. Background Technology

[0002] Tungsten metal and its alloys possess a series of advantages, including high melting point, low coefficient of thermal expansion, low sputtering corrosion rate, and low deuterium-tritium retention rate, making them candidate materials for future plasma-oriented materials in nuclear fusion reactors. However, the brittleness of tungsten materials severely limits their application in this field. Plasma-oriented materials will be subjected to significant thermal loads during service, and internal temperature gradients induce thermal stress. Under such significant thermal stress, brittle tungsten materials may crack.

[0003] Alloying, grain strengthening, and fine-grain strengthening are traditional methods for addressing the brittleness of tungsten materials. However, under high heat flux and neutron irradiation, these internal toughening mechanisms gradually fail. Therefore, tungsten materials prepared using internal toughening processes are unsuitable for long-term plasma-oriented service. To address this issue, researchers both domestically and internationally have employed fiber toughening processes to prepare tungsten fibers (W... f Toughened tungsten-based (W) composite material (W) f / W composite materials). This type of composite material is based on an external toughening mechanism. By introducing tungsten fiber tougheners into the tungsten matrix, energy dissipation mechanisms such as crack deflection, crack bridging, fiber debonding, and fiber pull-out are achieved, thereby improving the strength and toughness of the composite material. Commonly used tungsten fiber tougheners include long tungsten fibers, tungsten fiber webs, three-dimensional tungsten wire braids, and short tungsten fibers. Rui Shu et al. prepared long fiber W composite materials using long tungsten fibers as tougheners. f / W composite material, the mechanical property test results show that the composite material has high flexural strength and obvious "pseudoplastic" characteristics [R.Shu,Y.Mao,JWCoenen,A.Terra,C.Liu,S. J.Riesch,C.Linsmeier,C.Broeckmann,Interface and mechanical properties of the single-layer longfiber reinforced W f / W composites fabricated via field-assisted sintering technology, Mater. Sci. Eng. A. 857 (2022) 144098]. Wang Shan, Xie Mengyu, et al. prepared fiber mesh W using tungsten fiber mesh as toughening material. f / W composite material, compared with pure W material, the toughness of the composite material is improved by 60% to 80% [A layered fiber toughening tungsten-based composite material and its preparation method, Publication No.: CN 112442643 A]. Yan Binyou, Song Jiupeng et al. prepared fiber braided W using three-dimensional tungsten wire braid as toughening agent. f / W composite material, the mechanical property test results show that the composite material has excellent room temperature three-dimensional strength and room temperature three-dimensional toughness [a method for preparing tungsten wire reinforced tungsten matrix composite material, publication number: CN 115404419 A]. However, long fiber W prepared with long tungsten fibers or tungsten fiber webs as toughening agents f / W composite material or fiber mesh W f The W / T composite material suffers from anisotropic mechanical properties. The directions perpendicular to the long tungsten fibers or tungsten fiber webs represent the weakest points in the mechanical properties of the two composites, respectively. Furthermore, the preparation process is complex, requiring the artificial layering of long tungsten fibers / tungsten fiber webs with tungsten powder before sintering, which cannot guarantee product quality stability. The W / T composite material prepared using a three-dimensional tungsten wire braid as a toughening agent... f While the / W composite material achieves improved strength and toughness in three dimensions, it requires the pre-fabrication of a three-dimensional tungsten wire braid, making the process relatively complex. Short fiber W, prepared using short tungsten fibers as a toughening agent... f / W composite materials have advantages such as simple preparation process, isotropic mechanical properties, and high product quality stability, making them the most popular W composite materials currently available. f The main directions of research and development of / W composite materials.

[0004] W f Another key issue in W / W composite materials is the design of the fiber / matrix interface structure. The interface structure and properties within the composite material are crucial factors influencing its strength and toughness. Generally, fiber / matrix interface structures with weaker bonding strength facilitate energy dissipation mechanisms such as crack deflection, crack bridging, fiber debonding, and fiber pull-out, which are beneficial for improving the strength and toughness of the composite material. Therefore, in W / W composite materials... f In the preparation of W / W composite materials, it is often necessary to design the fiber / matrix interface as a weak bonding interface. Specifically, this usually requires pre-coating the W / W matrix with a surface coating technique. f A ceramic coating is prepared on the surface, and then W is prepared using it as a toughening agent. f / W composite materials. Current research mainly focuses on short W fibers coated with oxides or nitrides. f Preparation of short fiber W for toughening f / W composite materials. Luo Guangnan, Zhao Sixiang, and others used physical vapor deposition, chemical vapor deposition, or sol-gel methods to deposit W on short fiber composites. f Surface coatings of ZrO2, La2O3, Y2O3, etc. are prepared, and short fiber W is prepared using these coatings as toughening agents.f / W composite materials can significantly improve the brittleness problem of tungsten materials [A tungsten-based plasma-oriented material and its preparation method, Publication No.: CN 102560292 A]. JWCoenen et al. used magnetron sputtering technology to apply W to short fibers f A Y2O3 coating was prepared on the surface, followed by short fiber W... f The sintering of / W composite materials revealed a clear pseudo-ductile characteristic in the load-displacement curves of the material's mechanical properties tests, characterized by "cracks without breaks." The fracture surfaces of the samples exhibited obvious fiber debonding and pull-out phenomena [JWCoenen, Y.Mao, S.Sistla, J.Riesch, T.Hoeschen, C.Broeckmann, R.Neu, C.Linsmeier, Improved pseudo-ductile behavior of powder metallurgical tungsten short fiber-reinforced tungsten (W)]. f / W), Nucl. Mater. Energy. 15 (2018) 214–219]. Y. Mao et al. also studied short fiber W. f A Y2O3 coating is prepared on the surface, followed by short fiber W. f The sintering and mechanical property testing results of the / W composite material showed that the room temperature fracture toughness of the composite material reached 38.86 MPa·m. 1 / 2 The room temperature fracture energy density reaches 2.7 KJ / m³. 2 The room temperature fracture toughness of pure W material prepared under the same process parameters is only 5.48 MPa·m. 1 / 2 The room temperature fracture energy density is only 0.11 kJ / m³. 2 [Y.Mao,JWCoenen,J.Riesch,S.Sistla,J. J.Reiser,A.Terra,C.Chen,Y.Wu,L.Raumann,T. H. Gietl, R. Neu, C. Linsmeier, C. Broeckmann, Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites, Nucl. Fusion. 59(2019) 86034]. However, the oxide coating has a high vapor pressure, which raises concerns about its stability. Under the influence of sintering temperature and pressure, the short fiber W... fThe integrity of the surface oxide coating (such as Y2O3) is easily damaged, affecting the mechanical properties of the composite material [Y.Mao, JWCoenen, J.Riesch, S.Sistla, J. B. Jasper, A. Terra, T. H. Gietl, M. Bram, J. Gonzalez-Julian, C. Linsmeier, C. Broeckmann, Development and characterization of powder metallurgically produced discontinuous tungsten fiber reinforced tungsten composites, Phys. Scr. 2017(2017)14005]. Meanwhile, the low thermal conductivity of oxide coatings such as ZrO2, La2O3, and Y2O3, and the presence of a low thermal conductivity layer at the fiber / matrix interface within the composite material, will lead to a decrease in the material's thermal conductivity. Jiang Zhizhong, Chen Hao, et al. used boric acid and urea as raw materials to develop short fiber W... f A BN coating was prepared on the surface to coat BN short fibers W f Short fiber W prepared as toughening agent f / W composite materials exhibit high strength and toughness, with a room temperature tensile strength reaching 371 MPa and an elongation of 1.4%, while pure W materials prepared under the same process parameters have a room temperature tensile strength of only about 240 MPa and an elongation of only about 0.3%. [A high-strength and tough W composite material] f / W composite material and its preparation method, publication number: CN 114717491 B]. Nitride coating can exist stably inside the composite material, but BN material has low thermal conductivity, so BN short fiber W is coated with it. f Preparation of short fiber W for toughening f / W composite materials also suffer from the problem of reduced thermal conductivity.

[0005] As a plasma-oriented material, tungsten needs to possess both high strength and toughness to prevent cracking and failure under significant thermal stress, and excellent thermal conductivity to ensure rapid heat conduction and prevent melting or recrystallization embrittlement on the plasma-facing side due to excessively high temperatures. Therefore, it is necessary to develop a short-fiber W-type tungsten material with a novel fiber / matrix interface structure that balances both strength and rapid thermal conductivity. f / W composite materials are of great significance. Summary of the Invention

[0006] This invention aims to develop a short fiber W that can simultaneously improve the strength, toughness, and thermal conductivity of tungsten metal materials. fToughened W-based composite material. Aluminum nitride (AlN) is used as the short fiber W. f The fiber / matrix interface layer of the composite material aims to achieve a balance between the composite's strength and toughness and its rapid thermal conductivity. Therefore, this invention provides an aluminum nitride-coated short tungsten fiber-reinforced tungsten-based composite material and its preparation method.

[0007] The tungsten-based composite material toughened with aluminum nitride-coated short tungsten fibers proposed in this invention has a tungsten (W) matrix and a toughening agent consisting of short tungsten fibers (W) with an aluminum nitride (AlN) coating on their surface. f ), including aluminum nitride-coated short tungsten fibers (W f The amount of AlN added is 10% to 50% by volume, and the amount of activating sintering elements added to the matrix is ​​0% to 1.0% by mass.

[0008] Furthermore, the activating sintering elements in the matrix include iron powder, nickel powder, cobalt powder, aluminum powder, and palladium powder, with an addition amount of 0.1% to 1.0% by mass.

[0009] The preparation method of the above-mentioned aluminum nitride-coated short tungsten fiber-reinforced tungsten-based composite material includes the following steps:

[0010] Step (1) Coating AlN short fibers W f Preparation

[0011] a. Apply anhydrous ethanol or acetone to the original short fibers W f Ultrasonic cleaning is performed, followed by vacuum drying;

[0012] b. Surface coating techniques, including but not limited to magnetron sputtering and chemical vapor deposition, are used on the original short fiber W. f An AlN coating was prepared on the surface to obtain AlN-coated short fibers W. f .

[0013] Step (2) AlN short fiber W f Preparation of toughened W-based composite materials

[0014] a. Prepare AlN-plated short fibers W according to a certain proportion f W powder and activated sintering element powder, including AlN short fiber W f The addition amount is 10% to 50% by volume, and the addition amount of activating sintering element is 0% to 1.0% by mass. The above raw materials are mixed evenly by ball milling to obtain mixed powder.

[0015] b. The mixed powder is densified and sintered using spark plasma sintering (SPSS) at a temperature of 1500–2000℃ and a pressure of 50–80 MPa, with a holding time of 1–5 min, to obtain AlN-coated short fibers W. fToughened W-based composite materials.

[0016] Furthermore, in step (1)ab, the original short fiber W f It is a potassium-doped tungsten fiber with a diameter of 50–250 μm, a length of 1–4 mm, and a potassium content of 50–80 ppm.

[0017] Furthermore, in step (1)b, magnetron sputtering technology is used to deposit the raw short fiber W f When preparing an AlN coating on the surface, a certain amount of raw short fibers W f Sputtering is performed on a rotating substrate disk within the equipment chamber. The target material is pure aluminum, and the substrate is short fiber W. f The temperature is 300–450℃, the distance between the target and the substrate is 40–60 mm, the sputtering power is 150–450 W, the sputtering atmosphere is a high-purity Ar / N2 mixed atmosphere, the Ar:N2 flow ratio is 1:4–4:1, the sputtering pressure is 0.5–2 Pa, and the sputtering time is 2–20 h.

[0018] Furthermore, in step (1)b, chemical vapor deposition is used on the original short fiber W f When preparing an AlN coating on the surface, a certain amount of raw short fibers W f The substrate is placed on a rotating disk in the equipment chamber for deposition. The precursors are gaseous AlCl3 and NH3. The deposition temperature is 600-800℃, the flow ratio of gaseous AlCl3 to NH3 is 1:4-1:1, and the deposition time is 0.5-5h.

[0019] Furthermore, in step (2)a, the particle size of W powder is 500 nm to 10 μm, and the particle size of activated sintering element powder is 1 to 5 μm.

[0020] Furthermore, in step (2)a, when the raw materials are ball-milled and mixed, the grinding jar and grinding balls used are both made of cemented carbide. The W powder and AlN-coated short fiber W are then mixed. f Place the powdered W powder and activated sintering element powder in a ball mill jar according to the following ratio: ball to powder ratio 1:4 to 2:1, mill for 0.5 to 1 hour, and rotate at 50 to 150 r / min. If adding activated sintering element powder is required, first place the W powder and activated sintering element powder in a ball mill jar according to the following ratio: ball to powder ratio 2:1 to 8:1, mill for 2 to 10 hours, and rotate at 150 to 300 r / min. Then add the AlN-coated short fiber W powder. f Place the materials in a ball mill jar at a ratio of 1:4 to 2:1, mill for 0.5 to 1 hour, and rotate at a speed of 50 to 150 r / min.

[0021] Furthermore, in step (2)a, when the raw materials are mixed, high-purity Ar is introduced into the ball mill jar as a protective atmosphere. In step (2)b, high-purity Ar is used as a protective atmosphere throughout the spark plasma sintering process.

[0022] Further, in step (2)b, the discharge plasma sintering process is to raise the temperature to the target temperature at a heating rate of 50-100℃ / min, and the sintering pressure is simultaneously loaded to the target pressure during the heating process. The heat preservation process and the pressure preservation process are carried out simultaneously, and then the furnace is cooled down while the pressure is unloaded.

[0023] Furthermore, if the equipment used for sintering cannot meet the temperature requirements, and the sintering temperature is below 1800℃, activation sintering elements can be added to the tungsten matrix, including but not limited to iron powder (Fe), nickel powder (Ni), cobalt powder (Co), aluminum powder (Al), palladium powder (Pd), etc. The amount of activation sintering element powder added is 0.1% to 1.0% by mass. The activation sintering process is used to reduce the temperature required for densification of tungsten-based composite materials.

[0024] The aluminum nitride-coated short tungsten fiber-reinforced tungsten-based composite material of this invention is applicable to the field of high-performance tungsten-based structural materials, and is particularly suitable for the field of nuclear fusion plasma-oriented materials that require a balance between strength, toughness and thermal conductivity.

[0025] It should be noted that some activating sintering elements, such as Ni, Co, and Pd, are subject to radiation transmutation. Under neutron irradiation, these elements can produce radioactive elements with long half-lives, and therefore their use is prohibited in the field of nuclear fusion-oriented plasma materials. Accordingly, Fe can be selected as an activating sintering element in this field. If there are no restrictions on the elements used in the application of the material, other activating sintering elements can be selected.

[0026] The advantages of this invention are:

[0027] 1. This invention is the first to use aluminum nitride-coated short tungsten fibers (W f @AlN) was used to prepare short fiber W for the toughening material. f Toughened W-based composite materials. The presence of the AlN layer results in a weak bond at the fiber / matrix interface. When cracks propagate to the vicinity of the fibers, the weak bond facilitates energy dissipation mechanisms such as crack deflection, crack bridging, fiber debonding, and fiber pull-out, increasing the crack propagation path and thus improving the strength and toughness of the composite material.

[0028] 2. AlN has a high thermal conductivity (higher than pure W), and the AlN layer located at the fiber / matrix interface can be used as a base for short fiber W. fThe toughened W-based composite material provides a rapid pathway for thermal conduction, and its high thermal conductivity compensates for the additional interfacial thermal resistance introduced by the AlN layer. Therefore, the composite material exhibits higher thermal conductivity than the corresponding tungsten matrix material, while simultaneously improving the strength, toughness, and thermal conductivity of the tungsten metal. Attached Figure Description

[0029] Figure 1 AlN-coated short fibers W prepared in Example 1 f SEM images of surface microstructure and EDS composition analysis, (a) is a low-magnification SEM image; (b) is a high-magnification SEM image.

[0030] Figure 2 AlN-coated short fibers W prepared in Example 2 f SEM images of surface microstructure and EDS composition analysis, (a) is a low-magnification SEM image; (b) is a high-magnification SEM image.

[0031] Figure 3 The AlN-coated short fibers W prepared in Examples 1-4 f Schematic diagram of toughened W-based composite material structure. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited thereto. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment describes a tungsten-based composite material toughened with aluminum nitride-coated short tungsten fibers and its preparation method.

[0035] The composite material involved has a composition of 30% W. f @AlN / W, i.e., AlN-coated short fiber W f The volume fraction is 30%; the original short fibers involved are W f It has a diameter of 100μm, a length of 2.5mm, a potassium content of 70ppm, and a W powder particle size of 1μm.

[0036] The preparation method in this embodiment specifically includes the following steps:

[0037] Step (1) Coating AlN short fibers W f Preparation

[0038] Using anhydrous ethanol to treat the original short fibers W f Ultrasonic cleaning and vacuum drying were performed. Magnetron sputtering technology was then used to coat the raw short fibers with W... f To prepare an AlN coating on the surface, 10g of raw short fiber Wf Sputtering is performed on a rotating substrate disk within the equipment chamber. The target material is pure aluminum, and the substrate is short fiber W. f The sputtering temperature was 400℃, the distance between the target and the substrate was 50mm, the sputtering power was 400W, the sputtering atmosphere was a high-purity Ar / N2 mixed atmosphere, the Ar:N2 flow ratio was 2:1, the sputtering pressure was 1Pa, and the sputtering time was 15h, resulting in AlN short fiber W. f Surface microstructure and elemental composition analysis, such as Figure 1 As shown.

[0039] Step (2) AlN short fiber W f Preparation of toughened W-based composite materials

[0040] W powder and AlN-coated short fibers W f The materials used in the ball milling process were cemented carbide jars and grinding balls. High-purity Ar was used as a protective atmosphere in the jars. The ball-to-powder ratio was 1:3, the milling time was 0.5 hours, and the rotation speed was 70 r / min, resulting in a mixed powder. The mixed powder was then sintered using spark plasma sintering at 1900℃ and 50 MPa. The holding and pressure holding times were 4 minutes. The temperature was increased to the target temperature at a rate of 100℃ / min, and the sintering pressure was simultaneously increased to the target pressure during the heating process. The holding and pressure holding processes were carried out simultaneously, followed by furnace cooling and pressure release. High-purity Ar was used as the protective atmosphere throughout the sintering process, yielding AlN-coated short fiber W. f Toughened W-based composite material. A structural schematic diagram of the composite material is shown below. Figure 3 As shown, the density is 98.2%.

[0041] Example 2

[0042] This embodiment describes a tungsten-based composite material toughened with aluminum nitride-coated short tungsten fibers and its preparation method.

[0043] The composite material involved has a composition of 20% W. f @AlN / W, i.e., AlN-coated short fiber W f The volume fraction is 20%; the original short fibers involved are W f It has a diameter of 150μm, a length of 2mm, a potassium content of 60ppm, and a W powder particle size of 1μm.

[0044] The preparation method in this embodiment specifically includes the following steps:

[0045] Step (1) Coating AlN short fibers W f Preparation

[0046] Using anhydrous ethanol to treat the original short fibers W fUltrasonic cleaning and vacuum drying were performed. Chemical vapor deposition was then used to coat the virgin short fiber W... f An AlN coating was prepared on the surface using 7g of raw short fibers W. f The substrate was placed on a rotating disk within the equipment chamber for deposition. The precursors were gaseous AlCl3 and NH3. The deposition temperature was 750℃, the flow ratio of gaseous AlCl3 to NH3 was 1:2, and the deposition time was 3 hours, yielding AlN-coated short fibers W. f Surface microstructure and elemental composition analysis, such as Figure 2 As shown.

[0047] Step (2) AlN short fiber W f Preparation of toughened W-based composite materials

[0048] W powder and AlN-coated short fibers W f The materials used in the ball milling process were cemented carbide jars and grinding balls. High-purity Ar was used as a protective atmosphere in the jars. The ball-to-powder ratio was 1:2, the milling time was 0.5 hours, and the rotation speed was 80 r / min, resulting in a mixed powder. The mixed powder was then sintered using spark plasma sintering at 1900℃ and 50 MPa. The holding and pressure holding times were 4 minutes. The temperature was increased to the target temperature at a rate of 100℃ / min, and the sintering pressure was simultaneously increased to the target pressure during the heating process. The holding and pressure holding processes were carried out simultaneously, followed by furnace cooling and pressure release. High-purity Ar was used as the protective atmosphere throughout the sintering process, yielding AlN-coated short fiber W. f Toughened W-based composite material. A structural schematic diagram of the composite material is shown below. Figure 3 As shown, the density is 98.6%.

[0049] Example 3

[0050] This embodiment describes a tungsten-based composite material toughened with aluminum nitride-coated short tungsten fibers and its preparation method.

[0051] The composite material involved has a composition of 10% W. f @AlN / W-0.75%Fe, i.e., AlN short fiber coated with W f The volume fraction of W is 10%, and the mass fraction of Fe, the activation sintering element in the W matrix, is 0.75%. The original short fibers involved are W... f It has a diameter of 150μm, a length of 2.5mm, a potassium content of 75ppm, a W powder particle size of 5μm, and an Fe powder particle size of 2μm.

[0052] The preparation method in this embodiment specifically includes the following steps:

[0053] Step (1) Coating AlN short fibers W f Preparation

[0054] Using acetone on the original short fiber W f Ultrasonic cleaning and vacuum drying were performed. Magnetron sputtering technology was then used to coat the raw short fibers with W... f An AlN coating was prepared on the surface by using 4g of raw short fibers W f Sputtering is performed on a rotating substrate disk within the equipment chamber. The target material is pure aluminum, and the substrate is short fiber W. f The sputtering temperature was 350℃, the target-substrate distance was 60mm, the sputtering power was 350W, the sputtering atmosphere was a high-purity Ar / N2 mixed atmosphere with an Ar:N2 flow ratio of 3:1, the sputtering pressure was 1.5Pa, and the sputtering time was 10h, resulting in AlN short fiber W. f .

[0055] Step (2) AlN short fiber W f Preparation of toughened W-based composite materials

[0056] W powder, Fe powder and AlN-plated short fibers W f The powders were ball-milled in a specific ratio, using a cemented carbide jar and grinding balls. High-purity Ar was used as a protective atmosphere in the jar. First, W powder and Fe powder were mixed in a 4:1 ball-to-powder ratio, ball-milled for 5 hours at a speed of 200 r / min, and then mixed with AlN-coated short fiber W powder. f The powder was mixed in a 1:2 ratio with a ball-to-powder ratio, ball-milled for 0.5 hours at a speed of 60 r / min to obtain a mixed powder. The mixed powder was sintered using spark plasma sintering at 1600℃ and 60 MPa, with a holding time of 1 min. The temperature was increased to the target temperature at a rate of 80℃ / min, and the sintering pressure was simultaneously increased to the target pressure during the heating process. The holding and pressure holding processes were carried out simultaneously, followed by furnace cooling while simultaneously unloading the pressure. High-purity Ar was used as the protective atmosphere throughout the sintering process to obtain AlN-coated short fiber W. f Toughened W-based composite material. A structural schematic diagram of the composite material is shown below. Figure 3 As shown, the density is 99.5%.

[0057] Example 4

[0058] This embodiment describes a tungsten-based composite material toughened with aluminum nitride-coated short tungsten fibers and its preparation method.

[0059] The composite material involved has a composition of 30% W. f @AlN / W-0.75%Fe, i.e., AlN short fiber coated with W f The volume fraction of W is 30%, and the mass fraction of Fe, the activation sintering element in the W matrix, is 0.75%. The original short fibers involved are W... fIt has a diameter of 200μm, a length of 1.5mm, a potassium content of 65ppm, a W powder particle size of 5μm, and an Fe powder particle size of 2μm.

[0060] The preparation method in this embodiment specifically includes the following steps:

[0061] Step (1) Coating AlN short fibers W f Preparation

[0062] Using acetone on the original short fiber W f Ultrasonic cleaning and vacuum drying were performed. Chemical vapor deposition was then used to coat the virgin short fiber W... f To prepare an AlN coating on the surface, 10g of raw short fiber W f The substrate disk, placed within the equipment chamber and equipped with a rotating function, was used for deposition. The precursors were gaseous AlCl3 and NH3. The deposition temperature was 650℃, the flow ratio of gaseous AlCl3 to NH3 was 1:3, and the deposition time was 2 hours, yielding AlN-coated short fibers W. f .

[0063] Step (2) AlN short fiber W f Preparation of toughened W-based composite materials

[0064] W powder, Fe powder and AlN-plated short fibers W f The powders were ball-milled in a specific ratio, using a cemented carbide jar and grinding balls. High-purity Ar was used as a protective atmosphere in the jar. First, W powder and Fe powder were mixed in a 4:1 ball-to-powder ratio, ball-milled for 5 hours at a speed of 200 r / min, and then mixed with AlN-coated short fiber W powder. f The powder was mixed in a 1:4 ball-to-powder ratio, ball-milled for 0.5 hours at a speed of 50 r / min to obtain a mixed powder. The mixed powder was sintered using spark plasma sintering at 1600℃ and 60 MPa, with a holding time of 1 min. The temperature was increased to the target temperature at a rate of 80℃ / min, and the sintering pressure was simultaneously increased to the target pressure during the heating process. The holding and pressure holding processes were carried out simultaneously, followed by furnace cooling while simultaneously unloading the pressure. High-purity Ar was used as the protective atmosphere throughout the sintering process to obtain AlN-coated short fiber W. f Toughened W-based composite material. A structural schematic diagram of the composite material is shown below. Figure 3 As shown, the density is 99.1%.

[0065] Comparative Example a

[0066] The implementation procedures are the same as in Examples 1 and 2. The only difference between Comparative Example a and Examples 1 and 2 is that the material used in Comparative Example a does not contain AlN-plated short fibers W. fIt is made solely of pure W material. The density of the obtained pure W material is 99.3%.

[0067] Comparative Example b

[0068] The implementation procedures are the same as in Examples 3 and 4. The only difference between Comparative Example b and Examples 3 and 4 is that the material used in Comparative Example b does not contain AlN-plated short fibers W. f This refers to a W-0.75%Fe material with added Fe as an activation sintering element. The density of the resulting W-0.75%Fe material is 99.8%.

[0069] Table 1 shows the room temperature flexural strength, fracture toughness, and thermal conductivity of the materials prepared in Examples 1-4 and Comparative Example ab.

[0070] Table 1

[0071]

[0072]

Claims

1. A tungsten-based composite material toughened with aluminum nitride-coated short tungsten fibers, characterized in that, The matrix is ​​a tungsten (W) matrix, and the toughening agent is short tungsten fibers (W) with an aluminum nitride (AlN) coating on the surface. f Among them, aluminum nitride-coated short tungsten fibers W f The amount of AlN added is 10%~50% by volume, and the amount of activating sintering elements added to the matrix is ​​0~1.0% by mass. The preparation method of the aluminum nitride-coated short tungsten fiber-toughened tungsten-based composite material includes the following steps: 1) Using surface coating technology, the original short fibers W f An AlN coating was prepared on the surface to obtain AlN-coated short fibers W. f Original short fiber W f It is a potassium-doped tungsten fiber with a diameter of 50~250 μm, a length of 1~4 mm, and a potassium content of 50~80 ppm; 2) Prepare AlN-coated short fibers W according to a certain proportion f W powder and activated sintering element powder, including AlN short fiber W f The addition amount is 10%~50% by volume, and the addition amount of activating sintering element is 0~1.0% by mass. The above raw materials are mixed evenly using a ball milling process to obtain a mixed powder, which is then densified and sintered to obtain AlN-coated short fiber W. f Toughened W-based composite materials.

2. The tungsten-based composite material toughened with aluminum nitride short tungsten fibers according to claim 1, characterized in that, The activating sintering elements in the matrix include iron powder, nickel powder, cobalt powder, aluminum powder, and palladium powder, with an addition amount of 0.1% to 1.0% by mass.

3. The method for preparing the aluminum nitride-coated short tungsten fiber-reinforced tungsten-based composite material according to claim 1, characterized in that, Includes the following steps: Step (1) Coating AlN short fibers W f Preparation a. Apply anhydrous ethanol or acetone to the original short fibers W f Ultrasonic cleaning is performed, followed by vacuum drying; b. Surface coating technology using magnetron sputtering and chemical vapor deposition is applied to the original short fiber W f An AlN coating was prepared on the surface to obtain AlN-coated short fibers W. f ; The magnetron sputtering technology is used to sputter a certain amount of raw short fibers W f Sputtering is performed on a rotating substrate disk within the equipment chamber. The target material is pure aluminum, and the substrate is short fiber W. f The temperature is 300~450 ℃, the distance between the target and the substrate is 40~60 mm, the sputtering power is 150~450 W, the sputtering atmosphere is a high-purity Ar / N2 mixed atmosphere, the Ar:N2 flow ratio is 1:4~4:1, the sputtering pressure is 0.5~2 Pa, and the sputtering time is 2~20 h. The chemical vapor deposition technique employed involves depositing a certain amount of raw short fibers W f Deposition was performed on a rotating substrate disk within the equipment chamber. The precursors were gaseous AlCl3 and NH3. The deposition temperature was 600–800 °C, the flow ratio of gaseous AlCl3 to NH3 was 1:4–1:1, and the deposition time was 0.5–5 h. (2) AlN-coated short fiber W f Preparation of toughened W-based composite materials a. Prepare AlN-plated short fibers W according to a certain proportion f W powder and activated sintering element powder, including AlN short fiber W f The addition amount is 10%~50% by volume, and the addition amount of activating sintering element is 0~1.0% by mass. The above raw materials are mixed evenly by ball milling to obtain mixed powder. b. The mixed powder is densified and sintered using spark plasma sintering (SPSS) at a temperature of 1500–2000℃ and a pressure of 50–80 MPa for 1–5 min, to obtain AlN-coated short fibers W. f Toughened W-based composite materials.

4. The method for preparing the aluminum nitride-plated short tungsten fiber-reinforced tungsten-based composite material according to claim 3, characterized in that, In step (2)a, the particle size of W powder is 500 nm to 10 μm, and the particle size of the activated sintering element powder is 1 to 5 μm.

5. The method for preparing the aluminum nitride-plated short tungsten fiber-toughened tungsten-based composite material according to claim 3, characterized in that, In step (2)a, when the raw materials are ball-milled and mixed, the grinding jar and grinding balls used are both made of cemented carbide. The W powder and AlN-coated short fiber W are then mixed. f Place the powdered W powder and activated sintering element powder in a ball mill jar according to the following ratio: ball to powder ratio 1:4~2:1, mill for 0.5~1 h, and rotate at 50~150 r / min. If adding activated sintering element powder is required, first place the W powder and activated sintering element powder in a ball mill jar according to the following ratio: ball to powder ratio 2:1~8:1, mill for 2~10 h, and rotate at 150~300 r / min. Then add the AlN-coated short fiber W powder. f Place the materials in a ball mill jar according to the following ratio: ball to material ratio 1:4 to 2:1, mill for 0.5 to 1 hour, and rotate at 50 to 150 r / min.

6. The method for preparing the aluminum nitride-plated short tungsten fiber-reinforced tungsten-based composite material according to claim 3, characterized in that, In step (2)a, high-purity Ar is introduced into the ball mill jar as a protective atmosphere during raw material mixing. In step (2)b, high-purity Ar is used as a protective atmosphere throughout the spark plasma sintering process.

7. The method for preparing the aluminum nitride-plated short tungsten fiber-reinforced tungsten-based composite material according to claim 3, characterized in that, In step (2)b, the discharge plasma sintering process is heated to the target temperature at a heating rate of 50~100 ℃ / min. The sintering pressure is simultaneously applied to the target pressure during the heating process. The heat preservation process and the pressure preservation process are carried out simultaneously. Then, the furnace is cooled and the pressure is unloaded at the same time.

8. The method for preparing the aluminum nitride-plated short tungsten fiber-toughened tungsten-based composite material according to claim 3, characterized in that, When the sintering temperature is below 1800℃, activate sintering element powder, including iron powder, nickel powder, cobalt powder, aluminum powder, and palladium powder, is added to the W matrix. The amount of activated sintering element powder added is 0.1~1.0% by mass.

9. The aluminum nitride-plated short tungsten fiber-toughened tungsten matrix composite material according to any one of claims 1-2 is used for high-performance tungsten-based structural materials, and is particularly suitable for plasma-oriented materials in nuclear fusion reactors.

Images