A method for reinforcing tungsten-based composite materials

Abstract

This invention discloses a method for reinforcing tungsten-based composite materials. It involves using W, Cu, and Zr powders of different particle sizes in a composite mix, while simultaneously doping with a certain proportion of yttrium oxide. The mixture is then homogenized and mechanically alloyed through high-speed ball milling. Finally, the composite powder is cold-pressed and sintered using multi-field coupling to obtain a high-performance W-Cu-Zr composite material. This invention fully utilizes the characteristic that Zr can simultaneously form solid solutions and intermetallic compounds with W and Cu, improving the interfacial bonding between W and Cu, forming a tighter bonding interface and a new base phase. Combined with the synergistic reinforcing effect of yttrium oxide, this results in a composite material with improved densification and superior performance. The process is simple, highly targeted, and efficient at densifying composite materials. The final composite material achieves the designed performance, exhibiting higher mechanical strength and superior overall properties.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation technology, and specifically relates to a method for reinforcing tungsten-based composite materials. Background Technology

[0002] W-Cu binary pseudoalloys combine the advantages of both W and Cu, exhibiting outstanding characteristics such as high strength, high hardness, high electrical conductivity, high thermal conductivity, and low thermal expansion. They are widely used in electrode and contact materials, electronic packaging materials, and high-temperature structural materials. my country possesses abundant tungsten resources, providing a guarantee for the vigorous development of W-based composite materials. However, W and Cu are neither miscible nor reactive, and have poor wettability. The melting points of W and Cu are approximately 3400℃ and 1083℃, respectively, a significant difference. Even in the molten state, W and Cu are difficult to mix, posing a significant challenge to the preparation of W-Cu composite materials.

[0003] Currently, the main methods for preparing W-Cu composite materials include traditional melting, liquid-phase sintering, melt infiltration, microwave sintering, spark plasma sintering, and high-current electric field sintering. However, these methods still have some shortcomings. Traditional melting methods involve high temperatures, long processing times, complex steps, high energy consumption, and high costs. High-temperature liquid-phase sintering and melt infiltration methods suffer from high sintering temperatures, long holding times, uneven Cu phase distribution, grain growth, and complex preparation processes. Microwave sintering, due to its selective heating characteristics, allows the powder composition and size to affect the overall heating uniformity, thus impacting material properties. Spark plasma sintering and high-current electric field sintering, due to their rapid completion and the difficulty in densifying the material itself, struggle to obtain fully dense W-Cu composite materials. The W-Cu composite materials prepared by these methods suffer from low density and microstructural defects such as porosity and inhomogeneity, which also limit their applications. In addition, the activation energy of the sintering system can be reduced by adding transition metal activators (such as Fe, Ni, Co, etc.) to the composite powder, thereby reducing the sintering temperature and energy consumption during the preparation process. However, the addition of these activators has an adverse effect on the conductivity of the material.

[0004] In summary, existing methods for preparing W-Cu composite materials have drawbacks such as high sintering temperatures and long sintering times. Moreover, these cumbersome preparation processes increase production steps, production difficulty, and production costs. They may also result in problems such as low composite material density and severe grain growth, which to some extent limit the application of W-Cu composite materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for reinforcing tungsten-based composite materials, so as to solve the technical problems of severe grain growth and low density of composite materials.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for reinforcing tungsten-based composite materials, comprising the following steps: mixing tungsten, copper, zirconium, and yttrium oxide in a uniform ratio and mechanically alloying by high-speed ball milling, then pressing to obtain a green blank, subjecting the green blank to cold isostatic pressing, heating, and finally cooling to room temperature to obtain a W-Cu-Zr composite material, wherein the mass ratio of tungsten, copper, and zirconium is 70-90:5-15:5-15, and the amount of yttrium oxide added is 0.1-1% of the total mass of tungsten, copper, and zirconium.

[0007] The beneficial effects of the above-mentioned technical solution of this invention are as follows: The appropriate amount of added Y2O3 not only plays a role in dispersion strengthening and grain refinement of the tungsten skeleton, but also makes the Cu phase mesh more dispersed and continuous. On the other hand, Y2O3 has good thermodynamic stability and good wettability between Y2O3 and Cu. It is conducive to the formation of a network structure in which Cu continuously coats W, which can make the three phases of W, Cu and Zr uniformly distributed and the grains refined, which is beneficial to improving the comprehensive performance of W-Cu-Zr materials. However, if too much Y2O3 is added (greater than 1 wt%), the contact probability between Y2O3 particles increases, which can easily lead to agglomeration, block the pores of the W skeleton, hinder the penetration and effective feeding of liquid Cu, cause pore defects, and reduce the hardness of the alloy.

[0008] Based on the above technical solution, the present invention can be further improved as follows:

[0009] Furthermore, the tungsten, copper, and zirconium are composed of 80-90 wt% of larger particle size powder and 10-20 wt% of extremely fine powder, wherein the larger particle size powder is W powder with a particle size of 2-15 μm and Cu and Zr powder with a particle size of 3-10 μm, and the particle size of W powder is 1.5 times that of Cu and Zr powder; the extremely fine powder is W, Cu, and Zr powder with a particle size of 0.1-1 μm.

[0010] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: The present invention uses extremely fine powder of the same material to be mixed into powder of larger particle size, and selects tungsten, copper and zirconium powders of different particle sizes for composite stacking, and fills the gaps formed by particle bridging with small particles, making full use of the size effect of powder particle size, and the advantages of fine particles being able to effectively fill the gaps between large particles, so that W-Cu-Zr composite material can quickly achieve high densification at a lower temperature, significantly improving the density, strength and hardness of composite material.

[0011] Furthermore, the high-speed ball mill rotation speed is 400-600 r / min, and the ball milling time is 10-60 h.

[0012] Furthermore, the pressure for cold isostatic pressing is 400-500 MPa, and the holding time is 2-10 min.

[0013] Furthermore, the heating process involves heating the green billet to 200°C and holding it for 5-10 minutes under the combined action of thermo-electric-mechanical fields. Then, the temperature is increased to 950-1100°C, while the pressure is gradually increased to 50-60 MPa and held for 10-30 minutes.

[0014] Furthermore, the gradient pressurization process is as follows: pressurization is increased from 5MPa to 50-60MPa at a pressurization rate of 2-5MPa / min.

[0015] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: the multi-field coupling effect of heat, electricity and force can effectively promote the diffusion, solid solution and alloying between alloying elements. Compared with the traditional powder metallurgy method, the material can form a brand-new alloy phase under the multi-physical field coupling effect, which can effectively improve the density and strength of the material. At the same time, in order to prevent defects such as cracks caused by excessive loading pressure at the beginning of the green blank, as the sintering progresses, the strength of the material gradually increases after the sintering neck is formed and grown, and its pressure resistance also gradually increases. Therefore, the gradient pressurization method can further sinter and densify the composite material under greater pressure. Compared with the normal pressure method, the material achieves densification under higher pressure, which can effectively improve the density and key properties of the composite material.

[0016] The beneficial effects of this invention are as follows:

[0017] 1. The proportion of raw material components in the high-performance W-Cu-Zr composite material of this invention changes the phase of the metal matrix in the W-Cu-Zr composite material, forming new alloy base phases such as Zr-W and Zr-Cu. At the same time, the synergistic effect of yttrium oxide in strengthening the composite material is utilized, so that the W-Cu-Zr composite material has been comprehensively optimized in terms of density, strength and hardness.

[0018] 2. The method of this invention, combined with a newly optimized formula composition and mixing ratio, adopts a thermo-electric-mechanical multi-field coupling process for sintering and molding. It fully leverages the enhancing effect of the new basic components and W-Cu-Zr composite material formed under the multi-physical field coupling to enhance the material properties. The sintering process is controlled to obtain a high-performance W-Cu-Zr composite material with a uniform and dense structure, effectively giving full play to the comprehensive performance advantages of the new material.

[0019] 3. The method of the present invention has the advantages of high efficiency, speed, energy saving and environmental protection, and is an innovative technology for preparing high density and high performance W-Cu-Zr composite materials. Attached Figure Description

[0020] Figure 1 Fracture morphology of the W-Cu-Zr composite material prepared in Example 2. Detailed Implementation

[0021] The specific embodiments of the present invention are described below to facilitate understanding by those skilled in the art. Unless otherwise specified, specific conditions are applied according to conventional conditions or the manufacturer's recommendations. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various modifications are obvious as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims. All inventions utilizing the concept of this invention are protected.

[0022] Example 1:

[0023] A reinforced tungsten-based composite material, wherein the raw materials used include tungsten, copper and zirconium in a mass ratio of 80:10:10, and the amount of yttrium oxide added is 0.2% of the total mass of tungsten, copper and zirconium.

[0024] The preparation method of the composite material includes the following steps: Yttrium oxide is mixed with 80 wt% of W powder with a particle size of 7.5 μm and Cu and Zr powder with a particle size of 5 μm, and 20 wt% of W, Cu and Zr powder with a particle size of 0.5 μm according to the specified ratio. Then, the mixture is added to a high-energy planetary ball mill and ball-milled at a speed of 400 r / min for 30 h. The mixture is then pressed into a cylindrical green compact with a diameter of 14 mm and a height of 12 mm (relative density of 70%). The green compact is then cold isostatically pressed at a pressure of 400 MPa for 5 min, at which point the relative density of the green compact reaches 80%. The green compact is then heated to 200 °C and held for 5 min. The temperature is then increased to 950 °C, and the pressure is increased from 5 MPa to 60 MPa at a pressurization rate of 5 MPa / min and held for 20 min. Finally, the mixture is cooled to room temperature in the furnace to obtain the W-Cu-Zr composite material.

[0025] Example 2:

[0026] A reinforced tungsten-based composite material, wherein the raw materials used include tungsten, copper and zirconium in a mass ratio of 70:15:15, and the amount of yttrium oxide added is 0.4% of the total mass of tungsten, copper and zirconium.

[0027] The preparation method of the composite material includes the following steps: Yttrium oxide is mixed evenly with 80 wt% of W powder with a particle size of 15 μm and Cu and Zr powder with a particle size of 10 μm, and 20 wt% of W, Cu and Zr powder with a particle size of 1 μm. Then, the mixture is added to a high-energy planetary ball mill and ball-milled at a speed of 400 r / min for 40 h. The mixture is then pressed into a cylindrical green compact with a diameter of 14 mm and a height of 12 mm (relative density of 70%). The green compact is then cold isostatically pressed at a pressure of 400 MPa for 10 min, at which point the relative density of the green compact reaches 80%. The green compact is then heated to 200 °C and held for 5 min, and then heated to 1000 °C. At the same time, the pressure is increased from 5 MPa to 60 MPa at a pressurization rate of 5 MPa / min and held for 15 min. Finally, the mixture is cooled to room temperature in the furnace to obtain the W-Cu-Zr composite material.

[0028] Example 3:

[0029] A reinforced tungsten-based composite material, wherein the raw materials used include tungsten, copper and zirconium in a mass ratio of 85:10:5, and the amount of yttrium oxide added is 0.5% of the total mass of tungsten, copper and zirconium.

[0030] The preparation method of the composite material includes the following steps: Yttrium oxide is mixed with 80 wt% of W powder with a particle size of 15 μm and Cu and Zr powder with a particle size of 10 μm, and 20 wt% of W, Cu and Zr powder with a particle size of 0.1 μm according to the specified ratio. Then, the mixture is added to a high-energy planetary ball mill and ball-milled at a speed of 400 r / min for 20 h. The mixture is then pressed into a cylindrical green compact with a diameter of 14 mm and a height of 12 mm (relative density of 70%). The green compact is then cold isostatically pressed at a pressure of 400 MPa for 10 min, at which point the relative density of the green compact reaches 80%. The green compact is then heated to 200 °C and held for 5 min. The temperature is then increased to 920 °C, and the pressure is increased from 5 MPa to 60 MPa at a pressurization rate of 5 MPa / min and held for 20 min. Finally, the mixture is cooled to room temperature in the furnace to obtain the W-Cu-Zr composite material.

[0031] Example 4:

[0032] A reinforced tungsten-based composite material, wherein the raw materials used include tungsten, copper and zirconium in a mass ratio of 90:5:5, and the amount of yttrium oxide added is 0.6% of the total mass of tungsten, copper and zirconium.

[0033] The preparation method of the composite material includes the following steps: Yttrium oxide is mixed evenly with 90 wt% W powder with a particle size of 15 μm and Cu and Zr powder with a particle size of 10 μm, and 10 wt% W, Cu and Zr powder with a particle size of 1 μm according to the specified ratio. Then, the mixture is added to a high-energy planetary ball mill and ball-milled at a speed of 400 r / min for 10 h. The mixture is then pressed into a cylindrical green compact with a diameter of 14 mm and a height of 12 mm (relative density of 70%). The green compact is cold isostatically pressed at a pressure of 400 MPa for 10 min, at which point the relative density of the green compact reaches 80%. The green compact is then heated to 200 °C and held for 5 min. The temperature is then increased to 980 °C, and the pressure is increased from 5 MPa to 60 MPa at a pressurization rate of 5 MPa / min and held for 10 min. Finally, the mixture is cooled to room temperature in the furnace to obtain the W-Cu-Zr composite material.

[0034] Example 5:

[0035] A reinforced tungsten-based composite material, wherein the raw materials used include tungsten, copper and zirconium in a mass ratio of 80:5:15, and the amount of yttrium oxide added is 0.8% of the total mass of tungsten, copper and zirconium.

[0036] The preparation method of the composite material includes the following steps: Yttrium oxide is mixed with 80 wt% of W powder with a particle size of 9 μm and Cu and Zr powder with a particle size of 6 μm, and 20 wt% of W, Cu and Zr powder with a particle size of 0.5 μm according to the specified ratio. Then, the mixture is added to a high-energy planetary ball mill and ball-milled at a speed of 400 r / min for 20 h. The mixture is then pressed into a cylindrical green compact with a diameter of 14 mm and a height of 12 mm (relative density of 70%). The green compact is then cold isostatically pressed at a pressure of 400 MPa for 10 min, at which point the relative density of the green compact reaches 80%. The green compact is then heated to 200 °C and held for 5 min, and then heated to 1050 °C. At the same time, the pressure is increased from 5 MPa to 60 MPa at a pressurization rate of 5 MPa / min and held for 30 min. Finally, the mixture is cooled to room temperature in the furnace to obtain the W-Cu-Zr composite material.

[0037] Example 6:

[0038] A reinforced tungsten-based composite material, wherein the raw materials used include tungsten, copper and zirconium in a mass ratio of 75:10:15, and the amount of yttrium oxide added is 1% of the total mass of tungsten, copper and zirconium.

[0039] The preparation method of the composite material includes the following steps: Yttrium oxide is mixed evenly with 80 wt% W powder with a particle size of 7.5 μm and Cu and Zr powder with a particle size of 5 μm, and 20 wt% W, Cu and Zr powder with a particle size of 1 μm according to the specified ratio. Then, the mixture is added to a high-energy planetary ball mill and ball-milled at a speed of 400 r / min for 40 h. The mixture is then pressed into a cylindrical green compact with a diameter of 14 mm and a height of 12 mm (relative density of 70%). The green compact is cold isostatically pressed at a pressure of 400 MPa for 10 min, at which point the relative density of the green compact reaches 80%. The green compact is then heated to 200 °C and held for 5 min. The temperature is then increased to 1000 °C, and the pressure is increased from 5 MPa to 60 MPa at a pressurization rate of 5 MPa / min and held for 30 min. Finally, the mixture is cooled to room temperature in the furnace to obtain the W-Cu-Zr composite material.

[0040] Comparative Example 1:

[0041] A W-Cu composite material, the raw materials of which include tungsten and copper in a mass ratio of 80:20.

[0042] The preparation method of the composite material includes the following steps: 80 wt% of W powder with a particle size of 15 μm and Cu powder with a particle size of 10 μm, and 20 wt% of W powder with a particle size of 1 μm are mixed evenly according to the specified ratio. Then, the mixture is added to a high-energy planetary ball mill and ball-milled at a speed of 400 r / min for 40 h. The mixture is then pressed into a cylindrical green compact with a diameter of 14 mm and a height of 12 mm (relative density of 70%). The green compact is then cold isostatically pressed at a pressure of 400 MPa for 10 min, at which point the relative density of the green compact reaches 80%. The green compact is then heated to 230 °C and held for 5 min. The temperature is then increased to 1000 °C, and the pressure is increased from 5 MPa to 60 MPa at a pressurization rate of 5 MPa / min and held for 15 min. Finally, the mixture is cooled to room temperature in the furnace to obtain the W-Cu composite material.

[0043] Comparative Example 2:

[0044] A W-Cu-Zr composite material, the raw materials of which include tungsten, copper and zirconium in a mass ratio of 70:15:15.

[0045] The preparation method of the composite material includes the following steps: 80 wt% of W powder with a particle size of 15 μm and Cu and Zr powder with a particle size of 10 μm, and 20 wt% of W, Cu and Zr powder with a particle size of 1 μm are mixed evenly according to the formula. Then, the mixture is added to a high-energy planetary ball mill and ball-milled at a speed of 400 r / min for 40 h. Then, it is pressed into a cylindrical green compact with a diameter of 14 mm and a height of 12 mm (relative density of 70%). The green compact is cold isostatically pressed at a pressure of 400 MPa for 10 min, at which point the relative density of the green compact reaches 80%. Then, the green compact is heated to 200℃ and held for 5 min. Then, the temperature is increased to 1000℃, and the pressure is increased from 5 MPa to 60 MPa at a pressurization rate of 5 MPa / min and held for 15 min. Finally, it is cooled to room temperature in the furnace to obtain the W-Cu-Zr composite material.

[0046] Experimental example:

[0047] The actual density and relative density of the composite materials prepared in Examples 1-6 and Comparative Examples 1 and 2 were measured using the Archimedes method; the Vickers hardness of the composite materials was measured using a Vickers hardness tester; and the resistivity of the composite materials was measured using a digital portable eddy current resistivity meter. The test results are shown in Table 1.

[0048] Table 1 Composite material performance data

[0049]

[0050] Results analysis: Fracture morphology diagram of the W-Cu-Zr composite material prepared in Example 2 ( Figure 1 As can be seen, the W-Cu-Zr composite material prepared by multi-physics coupling has a uniform and dense structure, fine grains, and good interparticle bonding. The table shows that, compared to the W-Cu composite material (Comparative Example 1), the introduction of Zr significantly improves the density, hardness, and electrical conductivity of the W-Cu-Zr composite material (Comparative Example 2), and with the synergistic reinforcing effect of an appropriate amount of yttrium oxide, the density and hardness of the W-Cu-Zr composite material are further comprehensively optimized (Example 2).

Claims

1. A method for reinforcing tungsten-based composite materials, characterized in that, Includes the following steps: Tungsten, copper, zirconium, and yttrium oxide are mixed uniformly according to a certain ratio and mechanically alloyed by high-speed ball milling. The mixture is then pressed to obtain a green compact, which is subjected to cold isostatic pressing, heated, and finally cooled to room temperature to obtain a W-Cu-Zr composite material. The mass ratio of tungsten, copper, and zirconium is 70-90:5-15:5-15. The amount of yttrium oxide added is 0.1-1% of the total mass of tungsten, copper, and zirconium. The tungsten, copper, and zirconium are composed of 80-90 wt% of larger particle size powder and 10-20 wt% of extremely fine powder. The larger particle size powder consists of W powder with a particle size of 3-15 μm and Cu and Zr powder with a particle size of 2-10 μm, with the W powder particle size being 1.5 times that of the Cu and Zr powder. The extremely fine powder consists of W, Cu, and Zr powder with a particle size of 0.1-1 μm.

2. The method for reinforcing tungsten-based composite materials according to claim 1, characterized in that: The high-speed ball mill has a rotation speed of 400-600 r / min and a milling time of 10-60 h.

3. The method for reinforcing tungsten-based composite materials according to claim 1, characterized in that: The pressure of the cold isostatic pressing is 400-500 MPa, and the holding time is 2-10 min.

4. The method for reinforcing tungsten-based composite materials according to claim 1, characterized in that: The heating process involves heating the green billet to 200°C and holding it for 2-10 minutes under the combined action of thermo-electric-mechanical fields. Then, the temperature is increased to 950-1100°C, and the pressure is gradually increased to 50-60 MPa before holding it for 10-30 minutes.

5. The method for reinforcing tungsten-based composite materials according to claim 4, characterized in that: The gradient pressurization process is as follows: pressurize from 5MPa to 50-60MPa at a pressurization rate of 2-5MPa / min.

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