A multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material and a preparation method thereof

Abstract

This invention discloses a multi-scale tungsten fiber synergistic reinforcement and toughening tungsten-based composite material and its preparation method. The composite material raw materials include tungsten fibers and tungsten powder; the mass fractions of tungsten fibers and tungsten powder are 5-20% and 80-95%, respectively; the tungsten fibers include tungsten fibers of various lengths, with the mass fraction of different lengths exhibiting a normal distribution; the tungsten powder includes tungsten powder with a particle size of 0.5 μm, tungsten powder with a particle size of 2 μm, and tungsten powder with a particle size of 10 μm in a mass ratio of 1:2:4. The tungsten fiber-toughened tungsten composite material of this invention, with a normally distributed fiber length, can better withstand pressure and prevent the propagation of bridging cracks compared to ordinary short tungsten fiber-toughened tungsten composite materials, fully utilizing the toughening effect of tungsten fibers and playing a strengthening role, resulting in better strength and toughness of the composite material; compared to ordinary long tungsten fiber-toughened tungsten composite materials, no braiding treatment of the tungsten fibers is required, making the preparation process simpler and more convenient, and reducing production costs.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, specifically to a multi-scale tungsten fiber synergistic reinforcement and toughening tungsten-based composite material and its preparation method. Background Technology

[0002] Tungsten is an ideal plasma-oriented material due to its high melting point (3410℃), high thermal conductivity (173 W / (m·K)), excellent thermal shock resistance, and low sputtering yield. However, tungsten's intrinsic brittleness and high ductile-brittle transition temperature significantly limit its applications.

[0003] Currently, there are two main principles for improving the toughness of tungsten: internal toughening and external toughening. Internal toughening improves the plasticity of tungsten mainly by adding alloying elements, second-phase particles, or refining the tungsten grains. However, because tungsten is very sensitive to impurity elements and is prone to recrystallization under high-heat service conditions, these methods do not have a significant toughening effect. External toughening mainly involves preparing tungsten-based composite materials, which can be divided into fiber toughening and layered toughening depending on the toughening phase. Chinese patent application CN102560292A discloses a tungsten-based plasma-oriented material and its preparation method. It uses a mixing method that does not damage the tungsten fibers to mix tungsten powder and tungsten fibers evenly, and then uses hot isostatic pressing to sinter the bulk fiber-toughened tungsten-based material. However, the tungsten fibers in this material are short-cut fibers with a length of 1-5 mm, resulting in poor toughening effect. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to improve the brittleness of tungsten materials and increase their toughness.

[0005] The present invention solves the above-mentioned technical problems through the following technical means:

[0006] A multi-scale tungsten fiber synergistic reinforcement and toughening tungsten-based composite material, the raw materials of which include tungsten fibers and tungsten powder; the mass fraction of the tungsten fibers is 5-20%; the mass fraction of the tungsten powder is 80-95%; the tungsten fibers include tungsten fibers of various lengths, and the mass fraction of tungsten fibers of different lengths follows a normal distribution; the tungsten powder includes tungsten powder with a particle size of 0.5 μm, tungsten powder with a particle size of 2 μm and tungsten powder with a particle size of 10 μm, and the mass ratio of tungsten powder with a particle size of 0.5 μm, tungsten powder with a particle size of 2 μm and tungsten powder with a particle size of 10 μm is 1:2:4.

[0007] The mass fraction of tungsten fibers of different lengths exhibits a normal distribution. Specifically, the middle-length fibers, which are between the shortest and longest fibers, have the highest mass fraction. The mass fraction of fibers of different lengths, distributed sequentially from the shortest to the middle-length fibers, increases with increasing length, while the mass fraction of fibers of different lengths, distributed sequentially from the middle-length to the longest fibers, decreases with increasing length.

[0008] Preferably, the tungsten fiber is a drawn scheelite wire with a diameter of 50–200 μm.

[0009] Preferably, during the preparation of the composite material, tungsten fibers and tungsten powder are mechanically mixed using a three-dimensional powder mixer.

[0010] Preferably, when the composite material is cylindrical, the length distribution of the tungsten fibers is between the height and diameter of the cylinder; when the composite material is polyhedron, the length distribution of the tungsten fibers is between the shortest and longest side lengths of the polyhedron.

[0011] Preferably, the composite material is a cylindrical composite material with a diameter of 30 mm and a height of 3 mm; the tungsten fiber has a diameter of 150 μm, the tungsten fiber mass percentage is 5%, and the tungsten powder mass percentage is 95%; the tungsten fiber length distribution is 6–26 mm, wherein the 6 mm long tungsten fiber mass percentage is 5%, the 11 mm long tungsten fiber mass percentage is 20%, the 16 mm long tungsten fiber mass percentage is 50%, the 21 mm long tungsten fiber mass percentage is 20%, and the 26 mm long tungsten fiber mass percentage is 5%.

[0012] Preferably, the composite material is a cylindrical composite material with a diameter of 50 mm and a height of 3 mm, the tungsten fiber has a diameter of 100 μm, the tungsten fiber accounts for 10% of the mass, and the tungsten powder accounts for 90% of the mass; the tungsten fiber length distribution is 7-43 mm, wherein the tungsten fiber with a length of 7 mm accounts for 8% of the mass, the tungsten fiber with a length of 16 mm accounts for 25% of the mass, the tungsten fiber with a length of 25 mm accounts for 34% of the mass, the tungsten fiber with a length of 34 mm accounts for 25% of the mass, and the tungsten fiber with a length of 43 mm accounts for 8% of the mass.

[0013] This invention also proposes a method for preparing the aforementioned multi-scale tungsten fiber synergistic reinforcement and toughening tungsten-based composite material, comprising the following steps:

[0014] S1: Powder mixing: Put tungsten fibers and tungsten powder into a three-dimensional powder mixer and mix them;

[0015] S2: Molding: The mixed powder is placed into the mold to form the body to be sintered;

[0016] S3: Sintering: Sintering the body to be sintered under vacuum.

[0017] Preferably, in S1, the mixing time is 8 to 12 hours.

[0018] Preferably, in S2, the mixed powder and the mold cavity are separated by tungsten foil, and a layer of tungsten foil is placed at each of the upper and lower ends of the powder to isolate carbon contamination.

[0019] Preferably, in S3, the sintering pressure is 30-80 MPa, the holding temperature is 1450-1900 °C, and the holding time is 5 min.

[0020] The advantages of this invention are:

[0021] The tungsten fiber-reinforced tungsten composite material of the present invention, with a normal fiber length distribution, can effectively withstand pressure and prevent the propagation of bridging cracks with a smaller mass fraction of tungsten fibers compared to ordinary short tungsten fiber-reinforced tungsten composite materials. It fully utilizes the toughening effect of tungsten fibers and plays a reinforcing role, resulting in better strength and toughness of the composite material. Compared to ordinary long tungsten fiber-reinforced tungsten composite materials, it does not require weaving of tungsten fibers, making the preparation process simpler and more convenient, and reducing production costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the multi-scale tungsten fiber synergistic reinforcement and toughening tungsten-based composite material in Embodiment 1 of the present invention;

[0023] Figure 2 This is a macroscopic metallographic image of the multi-scale tungsten fiber synergistic reinforcement and toughening tungsten matrix composite material of Example 1 of the present invention;

[0024] Figure 3 This is a three-point bending stress-deflection diagram of the multi-scale tungsten fiber synergistic reinforcement and toughening tungsten matrix composite material of Example 1 of the present invention;

[0025] Figure 4 This is a three-point bending stress-deflection diagram of the multi-scale tungsten fiber synergistic reinforcement and toughening tungsten matrix composite material of Example 2 of the present invention;

[0026] Figure 5 This is a three-point bending stress-deflection diagram of the multi-scale tungsten fiber synergistic reinforcement and toughening tungsten matrix composite material of Example 3 of the present invention;

[0027] Figure 6 This is a length distribution diagram of the tungsten fibers used in Example 1 of the present invention;

[0028] Figure 7 This is a three-point bending stress-deflection diagram of the composite material of Comparative Example 1 of the present invention;

[0029] Figure 8 This is a scanned image of the composite material of Comparative Example 2 of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0032] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0033] In the following examples and comparative examples, the tungsten fiber is a drawn scheelite wire.

[0034] Example 1

[0035] This embodiment provides a multi-scale tungsten fiber synergistic reinforcement and toughening tungsten-based composite material (W). f / W composite material), which is a cylindrical W with a diameter of 30mm and a height of 3mm. f / W composite material, its schematic diagram is as follows Figure 1 As shown, its raw materials include tungsten powder and tungsten fibers; the tungsten fibers have a diameter of 150 μm and a tungsten fiber mass percentage of 5% (of which, 6 mm long tungsten fibers account for 5% of the total tungsten fiber mass, 11 mm long tungsten fibers account for 20% of the total tungsten fiber mass, 16 mm long tungsten fibers account for 50% of the total tungsten fiber mass, 21 mm long tungsten fibers account for 20% of the total tungsten fiber mass, and 26 mm long tungsten fibers account for 5% of the total tungsten fiber mass, such as...). Figure 6 As shown in the figure, the tungsten powder accounts for 95% of the total mass, and the particle sizes are 0.5μm, 2μm, and 10μm, with a mass ratio of 1:2:4. The specific preparation method is as follows:

[0036] Powder mixing: Tungsten fibers of different lengths and tungsten powder of different particle sizes are placed in a three-dimensional powder mixer and mixed for 12 hours;

[0037] Molding: The mixed powder is placed into a graphite mold to form the body to be sintered;

[0038] Sintering: The body to be sintered is sintered under vacuum at a temperature of 1500℃, uniformly pressurized to 40MPa, held at that temperature for 5 minutes, and then furnace cooled. After sintering, the mold is removed, and the prepared sample is demolded to obtain the composite material.

[0039] Example 2

[0040] This embodiment provides a multi-scale tungsten fiber synergistic reinforcement and toughening tungsten-based composite material (W). f / W composite material), which is a cylindrical W with a diameter of 50mm and a height of 3mm. f The / W composite material comprises tungsten powder and tungsten fibers as raw materials. The tungsten fibers have a diameter of 100 μm and a tungsten fiber mass percentage of 10% (of which, 7 mm long tungsten fibers account for 8% of the total tungsten fiber mass, 16 mm long tungsten fibers account for 25% of the total tungsten fiber mass, 25 mm long tungsten fibers account for 34% of the total tungsten fiber mass, 34 mm long tungsten fibers account for 25% of the total tungsten fiber mass, and 43 mm long tungsten fibers account for 8% of the total tungsten fiber mass). The tungsten powder mass percentage is 90%, and the tungsten powder particle sizes are 0.5 μm, 2 μm, and 10 μm, with a mass ratio of 1:2:4. The specific preparation method is as follows:

[0041] Powder mixing: Tungsten fibers of different lengths and tungsten powder of different particle sizes are mixed in a three-dimensional powder mixer for 10 hours;

[0042] Molding: The mixed powder is placed into a graphite mold to form the body to be sintered;

[0043] Sintering: The body to be sintered is sintered under vacuum at a temperature of 1500℃, uniformly pressurized to 40MPa, held at that temperature for 5 minutes, and then furnace cooled. After sintering, the mold is removed, and the prepared sample is demolded to obtain the composite material.

[0044] Example 3

[0045] This embodiment provides a multi-scale tungsten fiber synergistic reinforcement and toughening tungsten-based composite material (W). f / W composite material), which is a cylindrical W with a diameter of 50mm and a height of 3mm. f The / W composite material comprises tungsten powder and tungsten fibers as raw materials. The tungsten fibers have a diameter of 200 μm and a tungsten fiber mass percentage of 20% (of which, 7 mm long tungsten fibers account for 8% of the total tungsten fiber mass, 16 mm long tungsten fibers account for 25% of the total tungsten fiber mass, 25 mm long tungsten fibers account for 34% of the total tungsten fiber mass, 34 mm long tungsten fibers account for 25% of the total tungsten fiber mass, and 43 mm long tungsten fibers account for 8% of the total tungsten fiber mass). The tungsten powder has particle sizes of 0.5 μm, 2 μm, and 10 μm, with a mass ratio of 1:2:4. The specific preparation method is as follows:

[0046] Powder mixing: Tungsten fibers of different lengths and tungsten powder of different particle sizes are mixed in a three-dimensional powder mixer for 8 hours;

[0047] Molding: The mixed powder is placed into a graphite mold to form the body to be sintered;

[0048] Sintering: The body to be sintered is sintered under vacuum at a temperature of 1500℃, uniformly pressurized to 40MPa, held at that temperature for 5 minutes, and then furnace cooled. After sintering, the mold is removed, and the prepared sample is demolded to obtain the composite material.

[0049] Comparative Example 1

[0050] This comparative example provides a short tungsten fiber-reinforced tungsten-based composite material of the same length, which is a cylindrical W-shaped material with a diameter of 20 mm and a height of 5 mm. f / W composite material, the raw materials of which include tungsten powder and tungsten fiber; the tungsten fiber is 2.4 mm in length and 150 μm in diameter, the mass fraction of tungsten fiber is 20%, the mass fraction of tungsten powder is 80%, the particle size of tungsten powder is 0.5 μm, 2 μm and 10 μm, and the mass ratio is 1:2:4;

[0051] The specific preparation method is as follows:

[0052] Powder mixing: Tungsten fibers and tungsten powder are mixed in a three-dimensional powder mixer;

[0053] Molding: The mixed powder is placed into a graphite mold to form the body to be sintered;

[0054] Sintering: The body to be sintered is sintered under vacuum at a temperature of 1500℃, uniformly pressurized to 40MPa, held at that temperature for 5 minutes, and then furnace cooled. After sintering, the mold is removed, and the prepared sample is demolded.

[0055] Comparative Example 2

[0056] This comparative example provides a multi-scale tungsten fiber synergistic reinforcement and toughening tungsten-based composite material (W). f / W composite material), which is a cylindrical W with a diameter of 30mm and a height of 3mm. f The / W composite material comprises tungsten powder and tungsten fibers as raw materials. The tungsten fibers have a diameter of 150 μm and comprise 30% of the total mass (of which, 6 mm long tungsten fibers account for 5% of the total mass, 11 mm long tungsten fibers account for 20%, 16 mm long tungsten fibers account for 50%, 21 mm long tungsten fibers account for 20%, and 26 mm long tungsten fibers account for 5%). The tungsten powder comprises 70% of the total mass, with particle sizes of 0.5 μm, 2 μm, and 10 μm, in a mass ratio of 1:2:4. The specific preparation method is as follows:

[0057] Powder mixing: Tungsten fibers of different lengths and tungsten powder of different particle sizes are mixed in a three-dimensional powder mixer for 12 hours;

[0058] Molding: The mixed powder is placed into a graphite mold to form the body to be sintered;

[0059] Sintering: The body to be sintered is sintered under vacuum at a temperature of 1500℃, uniformly pressurized to 40MPa, held at that temperature for 5 minutes, and then furnace cooled. After sintering, the mold is removed, and the prepared sample is demolded to obtain the composite material.

[0060] Figure 2 This is a macroscopic metallographic image of the multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material of Example 1 of the present invention; [The image is] derived from... Figure 2 It can be seen that the fibers are evenly distributed.

[0061] Figure 3 This is a three-point bending stress-deflection diagram of the multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material of Example 1 of the present invention; (The diagram is derived from...) Figure 3 It can be seen that during the increase of the load, there were two instances of decrease followed by increase. When the load reached its maximum value, it did not decrease directly, but decreased slowly and in a step-like manner.

[0062] Figure 4 This is a three-point bending stress-deflection diagram of the multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material of Example 2 of the present invention; from Figure 4 It can be seen that during the process of increasing load, there were multiple instances of decreases followed by increases. When the load reached its maximum value, it did not decrease directly, but rather decreased slowly, resulting in a stepped decrease.

[0063] Figure 5 This is a three-point bending stress-deflection diagram of the multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material of Example 3 of the present invention; from Figure 5 It can be seen that the load decreased twice during the increase. When the load reached its maximum value, it did not decrease directly, but decreased slowly.

[0064] Figure 7 This is a three-point bending stress-deflection diagram of the composite material of Comparative Example 1 of the present invention; by Figure 7 As can be seen, once the load increases directly to its maximum value, it immediately drops to its minimum value, which is a typical case of brittle fracture.

[0065] Figure 8 This is a scanned image of the composite material of Comparative Example 2 of the present invention; by Figure 8 It can be seen that the fibers are severely entangled and there are large pores inside the sample.

[0066] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material, characterized in that: The raw materials include tungsten fibers and tungsten powder; the mass fraction of the tungsten fibers is 5-20%; the mass fraction of the tungsten powder is 80-95%; the tungsten fibers include tungsten fibers of various lengths, and the mass fraction of tungsten fibers of different lengths follows a normal distribution; the tungsten powder includes tungsten powder with a particle size of 0.5μm, tungsten powder with a particle size of 2μm, and tungsten powder with a particle size of 10μm, and the mass ratio of tungsten powder with a particle size of 0.5μm, tungsten powder with a particle size of 2μm, and tungsten powder with a particle size of 10μm is 1:2:4; The tungsten fiber length distribution is 6~26mm, with 6mm long tungsten fibers accounting for 5% of the mass, 11mm long tungsten fibers accounting for 20% of the mass, 16mm long tungsten fibers accounting for 50% of the mass, 21mm long tungsten fibers accounting for 20% of the mass, and 26mm long tungsten fibers accounting for 5% of the mass; or, the tungsten fiber length distribution is 7~43mm, with 7mm long tungsten fibers accounting for 8% of the mass, 16mm long tungsten fibers accounting for 25% of the mass, 25mm long tungsten fibers accounting for 34% of the mass, 34mm long tungsten fibers accounting for 25% of the mass, and 43mm long tungsten fibers accounting for 8% of the mass.

2. The multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material according to claim 1, characterized in that: The tungsten fiber is a drawn scheelite wire with a diameter of 50~200μm.

3. The multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material according to claim 1, characterized in that: In the preparation of composite materials, tungsten fibers and tungsten powder are mechanically mixed using a three-dimensional powder mixer.

4. The multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material according to claim 1, characterized in that: When the composite material is cylindrical, the length distribution of the tungsten fiber lies between the height and diameter of the cylinder; when the composite material is polyhedral, the length distribution of the tungsten fiber lies between the shortest and longest side lengths of the polyhedron.

5. The multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material according to any one of claims 1-4, characterized in that: The composite material is a cylindrical composite material with a diameter of 30 mm and a height of 3 mm; the tungsten fiber accounts for 5% of the mass and the tungsten powder accounts for 95% of the mass; the diameter of the tungsten fiber is 150 μm.

6. The multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material according to any one of claims 1-4, characterized in that: The composite material is a cylindrical composite material with a diameter of 50 mm and a height of 3 mm. The tungsten fiber has a diameter of 100 μm, the tungsten fiber accounts for 10% of the mass, and the tungsten powder accounts for 90% of the mass.

7. A method for preparing a multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Powder mixing: Put tungsten fibers and tungsten powder into a three-dimensional powder mixer and mix them; S2: Molding: The mixed powder is placed into the mold to form the body to be sintered; S3: Sintering: Sintering the body to be sintered under vacuum.

8. The method for preparing the multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material according to claim 7, characterized in that, In S1, the mixing time is 8~12h.

9. The method for preparing the multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material according to claim 7, characterized in that, In S2, the mixed powder and the mold cavity are separated by tungsten foil, and a layer of tungsten foil is placed at both the top and bottom of the powder to isolate carbon contamination.

10. The method for preparing the multi-scale tungsten fiber synergistically reinforced and toughened tungsten-based composite material according to any one of claims 7-9, characterized in that, In S3, the sintering pressure is 30~80MPa, the holding temperature is 1450~1900℃, and the holding time is 5min.

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