High-performance tungsten-copper composite material prepared through electric field assisted hot pressing sintering and preparation method and application of high-performance tungsten-copper composite material

Abstract

The invention discloses a high-performance tungsten-copper composite material prepared through electric field assisted hot pressing sintering and a preparation method and application of the high-performance tungsten-copper composite material. The method comprises the steps that (1) tungsten powder, copper powder and nickel powder are prepared; (2) pretreating tungsten powder, copper powder and nickel powder; and (3) preparation of the high-performance tungsten-copper composite material: performing direct-current electric field assisted hot pressing sintering on the tungsten-copper composite material powder to obtain the high-performance tungsten-copper composite material. According to the method, economical and practical direct current is added in the process of preparing the tungsten-copper composite material through vacuum hot pressing sintering, the tungsten-copper composite material is sintered and formed under the assistance of the electric field, the sintering temperature can be reduced, sample densification can be accelerated, the sintering time is short, and the production efficiency is greatly improved. The method is few in process, simple and efficient, the prepared tungsten-copper composite material is high in performance and suitable for various working conditions, especially working conditions with harsh high-temperature frictional wear and current-carrying frictional wear, and the cost is saved.

Description

Technical Field

[0001] The present invention belongs to the technical field of tungsten-copper composite materials, and particularly relates to a high-performance tungsten-copper composite material prepared by electric field assisted hot pressing and sintering, a preparation method thereof, and applications thereof. Background Art

[0002] Tungsten copper composite material is a two-phase monomer uniformly mixed composite material composed of tungsten with a high melting point and low thermal expansion coefficient and copper with high electrical conductivity and high thermal conductivity. It neither dissolves in each other nor forms an intermetallic compound. It is also called a "pseudo-alloy". Tungsten copper composite material (its composition range is generally WCu7~WCu50) combines the advantages of both tungsten and copper. It has good electrical and thermal conductivity, adjustable thermal expansion coefficient, good arc erosion resistance, high strength, high hardness, high density, high temperature resistance and other special properties. It is widely used in the defense industry, aerospace, electronic information and mechanical processing fields, such as rocket engine nozzles, EDM electrodes, electrical alloys for high-voltage switches and electronic packaging materials.

[0003] Common methods for preparing tungsten-copper composite materials include high-temperature liquid-phase sintering, activated liquid-phase sintering, melt infiltration, metal injection molding, and laser 3D printing. Most of these methods involve numerous steps, complex processes, and high costs. From an application perspective, simple mechanical alloying followed by sintering offers the highest efficiency and lowest cost for directly producing dense, high-performance tungsten-copper composite materials. However, traditional pressureless sintering and conventional vacuum hot-pressing methods for preparing tungsten-copper composite materials have slow heating rates, higher sintering temperatures, and longer processing times. The resulting tungsten-copper composite materials are not dense and have relatively low performance. Furthermore, while spark plasma sintering (SPS) technology can quickly produce dense tungsten-copper composite materials, it does so at a higher technical cost. Therefore, there is an urgent need for new, low-cost sintering methods to quickly, simply, and effectively prepare high-performance tungsten-copper composite materials. Summary of the Invention

[0004] The object of the present invention is to provide a high-performance tungsten-copper composite material prepared by electric field assisted hot pressing and sintering and a preparation method thereof.

[0005] The present invention also aims to provide the use of the high-performance tungsten-copper composite material prepared by the above method in the preparation of high-temperature friction and wear or current-carrying friction and wear products.

[0006] The first object of the present invention can be achieved by the following technical solution: A method for preparing a high-performance tungsten-copper composite material by electric field assisted hot pressing sintering, comprising the following steps:

[0007] (1) Preparation of tungsten powder, copper powder and nickel powder: Take tungsten powder, copper powder and nickel powder according to the following mass percentage: W 70-90%, Cu 10-30%, Ni 0-8%;

[0008] (2) Pretreatment of tungsten powder, copper powder and nickel powder: mixing by ball milling to obtain a uniformly mixed tungsten-copper composite material powder;

[0009] (3) Preparation of high-performance tungsten-copper composite materials: The tungsten-copper composite material powder is sintered by hot pressing assisted by a DC electric field to obtain a high-performance tungsten-copper composite material.

[0010] Therefore, the method of the present invention adds a certain amount of direct current during the vacuum hot pressing sintering process of tungsten-copper (nickel) alloy powder, and quickly prepares a high-performance tungsten-copper composite material with high density, good performance and suitable for harsh working conditions of high-temperature friction and wear and current-carrying friction and wear with the assistance of an electric field; this method for preparing tungsten-copper composite materials greatly improves preparation efficiency and effectively reduces costs.

[0011] In the above method for preparing high-performance tungsten-copper composite materials by electric field assisted hot pressing and sintering:

[0012] Preferably, in step (1), W is taken in the following mass percentages: 75-82%, Cu is 15-22%, and Ni is 3-6%.

[0013] More preferably, in step (1), W is taken in the following mass percentages: 75-80%, Cu is 15-20%, and Ni is 4-6%.

[0014] Furthermore, when the content of nickel powder is not zero, the pretreatment of tungsten powder, copper powder and nickel powder in step (2) of the present invention includes:

[0015] (2.1) Mechanical alloying of copper powder and nickel powder: Copper powder and nickel powder are mechanically alloyed using a ball mill under protective gas to obtain copper-nickel alloy powder;

[0016] (2.2) Mixing the mechanically alloyed copper-nickel alloy powder and tungsten powder: The copper-nickel alloy powder and tungsten powder are mechanically alloyed using a ball mill under a protective gas to obtain a tungsten-copper composite material powder.

[0017] That is, as a more preferred technical solution of the present invention, when the nickel content is not zero, the method for preparing a high-performance tungsten-copper composite material by electric field-assisted hot pressing sintering provided by the present invention comprises the following steps:

[0018] (1) Preparation of tungsten powder, copper powder and nickel powder

[0019] Take tungsten powder, copper powder and nickel powder according to the following mass percentage: W 75-82%, Cu 15-22%, Ni 3-6%;

[0020] (2) Pretreatment of tungsten powder, copper powder and nickel powder

[0021] (2.1) Mechanical alloying of copper powder and nickel powder: Copper powder and nickel powder are mechanically alloyed using a ball mill under protective gas to obtain copper-nickel alloy powder;

[0022] (2.2) Mixing the mechanically alloyed copper-nickel alloy powder and tungsten powder: The copper-nickel alloy powder and tungsten powder are mechanically alloyed using a ball mill under a protective gas to obtain tungsten-copper alloy powder;

[0023] (3) Preparation of high-performance tungsten-copper composite materials: Tungsten-copper alloy powder is sintered by hot pressing assisted by a DC electric field to obtain a high-performance tungsten-copper composite material.

[0024] Preferably, in step (2.1), mechanical alloying treatment of the copper powder and the nickel powder using a ball mill under the action of a protective gas includes: using zirconia balls, the mass ratio of the zirconia balls to the copper powder and the nickel powder is 8 to 12:1, placing the copper powder and the nickel powder in the ball mill, passing argon gas for protection, adjusting the speed to 300 to 400 r / min, setting the ball mill to alternate forward and reverse rotations, with an interval of 10 to 20 minutes between forward and reverse rotations, each ball milling for 20 to 40 minutes, and a total ball milling time of 15 to 30 hours. After the mechanical alloying is completed, the powder is cooled to room temperature and then taken out for sieving.

[0025] More preferably, in step (2.1), the copper powder and nickel powder are subjected to mechanical alloying treatment using a ball mill under the action of a protective gas, comprising: mixing the copper powder and the nickel powder in a mass ratio of 3 to 4:1, using zirconia balls, and placing the copper powder and the nickel powder in a ball mill according to a mass ratio of the ball materials (copper powder and nickel powder) of 8 to 12:1, introducing argon gas with a purity of 99.99 wt% or more into the ball mill for protection, adjusting the speed to 300 to 400 r / min, setting the ball mill to alternate forward and reverse rotations, with an interval of 15 minutes between forward and reverse rotations, each ball milling for 30 minutes, and a total ball milling time of 15 to 30 hours. After the mechanical alloying is completed, the powder is cooled to room temperature and then removed and sieved.

[0026] The present invention utilizes high-energy ball milling to mechanically alloy tungsten powder and nickel powder in advance. During the high-energy ball milling process, copper powder and nickel powder are repeatedly cold-welded, fractured, and diffused to form a uniform solid solution. Nickel can improve the wettability between tungsten and copper. At high temperatures, nickel diffuses to the surface, reducing the contact angle between copper and tungsten, optimizing the wetting behavior of tungsten and copper, promoting the expansion of copper on the surface of tungsten particles, and enhancing the bonding strength of tungsten and copper. Therefore, the role of nickel is to improve the wettability of the tungsten and copper surfaces. In addition to nickel, other metals can also be used to improve the wettability of the tungsten and copper surfaces, but nickel is preferred.

[0027] Preferably, in step (2.2), the copper-nickel alloy powder and the tungsten powder are subjected to mechanical alloying treatment using a ball mill under the action of a protective gas, which includes: using zirconia balls, the mass ratio of the zirconia balls to the copper-nickel alloy powder and the tungsten powder is 1 to 2:1, the copper-nickel alloy powder and the tungsten powder are placed in a ball mill, argon gas is introduced for protection, the speed is adjusted to 150 to 250 r / min, the ball mill is set to alternate forward and reverse rotation, the interval between forward and reverse rotation is 150 to 20 minutes, each ball milling is 20 to 40 minutes, and the total ball milling time is 2 to 4 hours. After the mechanical alloying is completed, the powder is cooled to room temperature and then taken out for sieving.

[0028] More preferably, in step (2.2), the copper-nickel alloy powder and the tungsten powder are subjected to mechanical alloying treatment using a ball mill under the action of a protective gas, including: mixing the copper-nickel alloy powder and the tungsten powder in a mass ratio of 3 to 4:1, placing the copper-nickel alloy powder and the tungsten powder in a ball mill, introducing argon gas with a purity of 99.99wt% or more for protection, using zirconia grinding balls, adjusting the mass ratio of the ball materials (copper-nickel alloy powder and tungsten powder) to 1.5:1, adjusting the speed to 200r / min, setting the ball mill to alternate forward and reverse rotations, with an interval of 15min between forward and reverse rotations, each ball milling for 30min, and a total ball milling time of 4h.

[0029] Preferably, in step (1), tungsten powder, copper powder and nickel powder are taken according to the following mass percentages: W 75-80%, Cu 15-20%, Ni 4-6%.

[0030] Preferably, the particle size of the tungsten powder in step (1) is 5-15 μm, the particle size of the copper powder is 10-35 μm, the particle size of the nickel powder is 15-45 μm, and the purity of the tungsten powder, copper powder and nickel powder is above 99.9%.

[0031] More preferably, the particle size of the tungsten powder in step (1) is 5 to 10 μm.

[0032] More preferably, the particle size of the tungsten powder in step (1) is 5 to 8 μm.

[0033] More preferably, the particle size of the copper powder in step (1) is 10 to 30 μm.

[0034] More preferably, the particle size of the copper powder in step (1) is 12 to 25 μm.

[0035] More preferably, the particle size of the nickel powder in step (1) is 20-45 μm.

[0036] More preferably, the particle size of the nickel powder in step (1) is 20 to 25 μm.

[0037] Preferably, the DC current of the DC electric field in step (3) is 1000 to 4500A.

[0038] More preferably, the DC current of the DC electric field in step (3) is 2000-4500A.

[0039] More preferably, the DC current of the DC electric field in step (3) is 3000-4000A.

[0040] Preferably, a graphite mold is used during hot pressing and sintering in step (3), and the vacuum degree during hot pressing and sintering is 10 -1 ~10 - 3 Pa, pressure is 30-50 MPa, heating rate is 80-200℃ / min, sintering temperature is 950-1050℃, and holding time is 5-20min.

[0041] More preferably, a graphite mold is used during hot pressing and sintering in step (3), and the vacuum degree during hot pressing and sintering is 10 -1 ~10 - 3 Pa, pressure is 30-50 MPa, heating rate is 100-200℃ / min, sintering temperature is 950-980℃, and holding time is 5-10min.

[0042] When direct current passes through the conductive tungsten-copper powder and the graphite mold, Joule heat is generated due to resistance, causing the tungsten-copper to heat up rapidly. At the same time, under high current density, tungsten ions and copper ions migrate along the electric field direction, thereby enhancing the material transmission capacity and reducing the diffusion activation energy. The tungsten-copper composite material has a fast heating rate, low sintering temperature, short preparation time and high efficiency. The surface hardness of the prepared tungsten-copper composite material reaches about 400HV and the tensile strength is not less than 433MPa. It is suitable for harsh working conditions of high-temperature friction and wear and current-carrying friction and wear.

[0043] The method incorporates economical direct current into the vacuum hot-pressing sintering process to prepare high-performance tungsten-copper composite materials. The sintering process is assisted by an electric field. This method can reduce the sintering temperature and accelerate sample densification. The sintering time is also short, significantly improving production efficiency. The method of the present invention has a limited number of steps, is simple and efficient, and the resulting tungsten-copper composite material has high performance and is suitable for a variety of operating conditions, particularly those subject to high-temperature friction and wear and current-carrying friction and wear, saving costs.

[0044] The present invention also provides a high-performance tungsten-copper composite material, which is prepared by the above method.

[0045] The second object of the present invention can be achieved by the following technical solution: application of the high-performance tungsten-copper composite material in the preparation of high-temperature friction and wear or current-carrying friction and wear products.

[0046] The high-performance tungsten-copper composite material prepared by the method of the present invention is suitable for various working conditions, especially high-temperature friction and wear and current-carrying friction and wear working conditions, and can be used as a high-temperature friction and wear or current-carrying friction and wear product.

[0047] The present invention has the following advantages:

[0048] (1) The method for preparing high-performance tungsten-copper composite materials by electric field-assisted hot pressing sintering provided by the present invention adds economical direct current during the sintering process. Sintering with the assistance of the electric field can reduce the sintering temperature and accelerate the densification of the sample. Unlike expensive spark plasma sintering (SPS), direct current electric field-assisted sintering not only has the characteristics of high material density and fast sintering rate, but also can quickly achieve sample densification in just 10-20 minutes, with a heating rate of up to 1000°C / min. In addition, the rapid hot pressing sintering temperature is relatively low, the sintering time is short, and the grain growth rate of the sample is slowed down, which is conducive to the preparation of fine-grained materials.

[0049] (2) In the present invention, nickel powder and copper powder are pre-mechanically alloyed, and a nickel coating is prepared on the surface of the copper powder to improve the wettability between tungsten and copper, making the composite material sintered more densely;

[0050] (3) The high-performance tungsten-copper composite material prepared in the present invention is suitable for various working conditions, especially high-temperature friction and wear and current-carrying friction and wear working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The present invention will be further described below in conjunction with embodiments with reference to the accompanying drawings.

[0052] Figure 1 The DC electric field assisted hot pressing sintering device used in Examples 1-4 and Comparative Examples 1-2 is shown. In Comparative Examples 2-3, the DC electrode can be turned off.

[0053] Figure 2 shows the stress and strain diagrams of the tungsten-copper composite materials prepared in Example 1 and Example 4;

[0054] Figure 3 The XRD patterns of the tungsten-copper composite materials prepared in Examples 1-3 are shown;

[0055] Figure 4 The SEM surface morphology of the tungsten-copper composite materials prepared in Example 1 and Comparative Examples 1-2 is shown;

[0056] Figure 5 The figure shows the change of friction coefficient of the tungsten-copper composite material prepared in Example 1 and commercially available pure tungsten in a high-temperature friction and wear test at 800°C;

[0057] Figure 6The figure shows the three-dimensional morphology of the wear scar after high-temperature friction and wear between the tungsten-copper composite material prepared in Example 1 and commercially available pure tungsten at 800°C;

[0058] Figure 7 The figure shows the volume loss of the tungsten-copper composite material prepared in Example 1 and commercially available pure tungsten after high-temperature friction and wear at 800°C;

[0059] Figure 8 The figure shows the volume loss of the tungsten-copper composite material prepared in Example 1 and commercially available pure copper after current-carrying friction and wear tests;

[0060] Figure 9 The SEM surface morphology of the tungsten-copper composite material prepared in Example 1 and commercially available pure copper after current-carrying friction and wear tests is shown. DETAILED DESCRIPTION

[0061] The following is a further description of specific embodiments of the present invention. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0062] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0063] Unless otherwise specified, the experimental methods used in the following implementation methods are all conventional experimental methods.

[0064] Unless otherwise specified, the terms used in the following implementation methods and examples generally have the meanings commonly understood by those skilled in the art.

[0065] Part 1 A method for preparing high-performance tungsten-copper composite materials by electric field assisted hot pressing and sintering

[0066] Example 1

[0067] The method for preparing a high-performance tungsten-copper composite material by electric field-assisted hot pressing sintering provided in this embodiment includes the following steps:

[0068] (1) Preparation of tungsten copper powder:

[0069] The commercially available powders of each component were weighed according to the mass fractions of W 75%, Cu 20%, and Ni 5%. The raw materials were sieved to obtain the target particle size range: tungsten powder 8-12 μm, copper powder 10-15 μm, and nickel powder 20-30 μm, with a purity of more than 99.99%.

[0070] (2) Pretreatment of tungsten copper powder:

[0071] (2.1) Mechanical alloying of copper-nickel powder: The mass ratio of Cu powder to Ni powder is 4:1. Zirconia grinding balls are used, and the ball-to-material ratio is 10:1. Argon gas with a purity of more than 99.99% is passed into the ball mill for protection. The rotation speed is 350 r / min. The ball mill is set to alternate forward and reverse rotations with an interval of 15 minutes between forward and reverse rotations. Each ball milling lasts 30 minutes, and the total ball milling time is 30 hours. After the mechanical alloying is completed, the powder is cooled to room temperature and then taken out for sieving.

[0072] (2.2) Mixing of mechanically alloyed copper-nickel powder and tungsten powder: Weigh tungsten powder and mechanically alloyed copper powder in a mass ratio of 3:1, put the tungsten-copper powder into a ball mill, and introduce argon gas with a purity of more than 99.99% for protection. Use zirconia grinding balls with a ball-to-material ratio of 2:1 and a rotation speed of 250 r / min. Set the ball mill to rotate alternately in forward and reverse directions with an interval of 15 minutes between forward and reverse rotations. Each ball milling lasts 30 minutes, and the total ball milling time is 2 hours.

[0073] (3) Preparation of tungsten-copper composite materials:

[0074] The tungsten copper alloy powder prepared above was sintered by DC electric field assisted hot pressing (test device as shown in Figure 1 As shown, the same below, it is obtained by equipping the pressure head of a commercial hot pressing sintering furnace with a DC electrode, and the DC electrode is provided with an independent control knob) to prepare a tungsten copper composite material, and the sintering vacuum degree reaches 10 -3 Pa, pressure 30MPa, heating rate 100℃ / min, and adjusting the DC current size to 3000~4500A can maintain a fixed heating rate during the sintering process, the sintering temperature is 980℃, and the holding time is 5min.

[0075] Example 2

[0076] The method for preparing a high-performance tungsten-copper composite material by electric field-assisted hot pressing sintering provided in this embodiment includes the following steps:

[0077] (1) Preparation of tungsten copper powder:

[0078] The commercially available powders of each component are weighed according to the mass fractions of W 80%, Cu 16%, and Ni 4%. The particle sizes of the raw materials are: tungsten powder 8-15 μm, copper powder 10-20 μm, and nickel powder 15-25 μm, and the purity is above 99.99%.

[0079] (2) Pretreatment of tungsten copper powder:

[0080] (2.1) Mechanical alloying of copper-nickel powder: The mass ratio of Cu powder to Ni powder is 4:1. Zirconia grinding balls are used, and the ball-to-material ratio is 8:1. Argon gas with a purity of more than 99.99% is passed into the ball mill for protection. The rotation speed is 300 r / min. The ball mill is set to alternate forward and reverse rotations with an interval of 15 minutes between forward and reverse rotations. Each ball milling lasts 30 minutes, and the total ball milling time is 25 hours. After the mechanical alloying is completed, the powder is cooled to room temperature and then taken out for sieving.

[0081] (2.2) Mixing of mechanically alloyed copper-nickel powder and tungsten powder: Weigh tungsten powder and mechanically alloyed copper powder in a mass ratio of 4:1, put the tungsten-copper powder into a ball mill, and introduce argon gas with a purity of more than 99.99% for protection. Use zirconia grinding balls with a ball-to-material ratio of 1:1 and a rotation speed of 200 r / min. Set the ball mill to alternate forward and reverse rotations with an interval of 15 minutes between forward and reverse rotations. Each ball milling lasts 30 minutes, and the total ball milling time is 4 hours.

[0082] (3) Preparation of tungsten-copper composite materials:

[0083] The tungsten-copper alloy powder prepared above was sintered by hot pressing assisted by DC electric field to prepare tungsten-copper composite material. -2 Pa, pressure 35MPa, heating rate 100℃ / min, DC current 2000~4500A, sintering temperature 950℃, holding time 15min.

[0084] Example 3

[0085] The method for preparing a high-performance tungsten-copper composite material by electric field-assisted hot pressing sintering provided in this embodiment includes the following steps:

[0086] (1) Preparation of tungsten copper powder:

[0087] The commercially available powders of each component were weighed according to the mass fractions of W 76%, Cu 18%, and Ni 6%. The particle sizes of the raw materials were: tungsten powder 8-12 μm, copper powder 10-15 μm, and nickel powder 20-30 μm, and the purity was above 99.99%.

[0088] (2) Pretreatment of tungsten copper powder:

[0089] (2.1) Mechanical alloying of copper-nickel powder: The mass ratio of Cu powder to Ni powder is 3:1. Zirconia grinding balls are used, and the ball-to-material ratio is 9:1. Argon gas with a purity of more than 99.99% is passed into the ball mill for protection. The rotation speed is 400 r / min. The ball mill is set to alternate forward and reverse rotations with an interval of 15 minutes between forward and reverse rotations. Each ball milling lasts 30 minutes, and the total ball milling time is 20 hours. After the mechanical alloying is completed, the powder is cooled to room temperature and then taken out for sieving.

[0090] (2.2) Mixing of mechanically alloyed copper-nickel powder and tungsten powder: Weigh tungsten powder and mechanically alloyed copper powder at a mass ratio of 3.17:1, put the tungsten-copper powder into a ball mill, and introduce argon gas with a purity of more than 99.99% for protection. Use zirconia grinding balls with a ball-to-material ratio of 1.5:1 and a rotation speed of 200 r / min. Set the ball mill to alternate forward and reverse rotations with an interval of 15 minutes between forward and reverse rotations. Each ball milling lasts 30 minutes, and the total ball milling time is 4 hours.

[0091] (3) Preparation of tungsten-copper composite materials:

[0092] The tungsten-copper alloy powder prepared above was sintered by hot pressing assisted by DC electric field to prepare tungsten-copper composite material. -2 Pa, pressure 50MPa, heating rate 80℃ / min, DC current 1000~4500A, sintering temperature 1050℃, holding time 10min.

[0093] Example 4

[0094] Compared with Example 1, the difference is that: nickel powder is not added in step (1), copper powder and nickel powder are not mechanically alloyed in the tungsten-copper powder in step (2), and copper powder and tungsten powder are directly ball-milled and mixed, wherein the ratio of tungsten powder to copper powder is 75% W and 25% Cu.

[0095] Comparative Example 1

[0096] Compared with Example 1, the difference is that in step (3), no direct current is applied to the tungsten copper powder during the sintering process, the heating rate is 5°C / min, the sintering temperature is 980°C, and the holding time is 2h.

[0097] Comparative Example 2

[0098] Compared with Example 1, the difference is that in step (3), no direct current is applied to the tungsten copper powder during the sintering process, the heating rate is 5°C / min, the sintering temperature is 1200°C, and the holding time is 2h.

[0099] Part 2 Microstructure and performance testing of high-performance tungsten-copper composites prepared by electric field assisted rapid sintering

[0100] 1) Physical and mechanical properties tests were performed on the tungsten-copper composite materials in Examples 1-3:

[0101] The density of the tungsten-copper composite materials in Examples 1-3 was measured according to the ASTM B311-22 standard test method for determining the density of sintered metal materials. The hardness of the tungsten-copper composite materials in Examples 1-3 was tested according to the method in GB / T 4340.1-2009 Vickers hardness test for metal materials. Seven data points were collected in the test, and the average value was taken after removing the maximum value. The conductivity of the tungsten-copper composite materials in Examples 1-3 was tested according to the method in ASTM B193 standard for testing the resistance of conductive materials. The density, hardness and conductivity measurement results are shown in Table 1.

[0102] Table 1 Physical and mechanical properties of tungsten-copper composite materials prepared in Examples 1-3

[0103] Sample name Example 1 Example 2 Example 3 Density / % 98.2 98.6 98.4 Vickers hardness / HV 394.1 416.4 383.4 Conductivity IACS 36.3 34.2 36.1

[0104] It can be seen from Table 1 that the density, surface hardness and electrical conductivity of the tungsten-copper composite materials prepared in Examples 1-3 are all at a high level. The surface hardness is not only related to the density, but also positively correlated with the ratio of tungsten to copper. The proportion of tungsten in Example 2 is slightly higher, so its hardness is slightly higher than that of Example 1 and Example 3.

[0105] 2) Physical and mechanical properties tests were performed on the tungsten-copper composite material in Example 1 and the tungsten-copper composite material in Example 4:

[0106] The density of the tungsten-copper composite materials in Example 1 and Example 4 was measured according to the ASTM B311-22 standard test method for determining the density of sintered metal materials. The hardness of the tungsten-copper composite materials in Example 1 and Example 4 was tested according to the method in GB / T4340.1-2009 Vickers hardness test for metal materials. Seven data points were collected in the test, and the average value was obtained after removing the maximum value. The electrical conductivity of the tungsten-copper composite materials in Example 1 and Example 4 was tested according to the method in ASTM B193 standard for testing the resistance of conductive materials. The density, hardness and electrical conductivity measurement results are shown in Table 2.

[0107] Table 2 Physical and mechanical properties of tungsten-copper composite materials prepared in Example 1 and Example 4

[0108] Sample name Example 1 Example 4 Density / % 98.2 96.8 Vickers hardness / HV 394.1 357.3 Conductivity IACS 36.3 31.2

[0109] It can be seen from Table 2 that the tungsten-copper composite material without copper-nickel mechanical alloying has poor surface wettability of tungsten and copper, and its density, hardness and conductivity after sintering are not as good as those after pretreatment (high-energy ball milling mechanical alloying of copper powder and nickel powder).

[0110] 3) The physical and mechanical properties of the tungsten-copper composite material in Example 1 and the tungsten-copper composite material in Comparative Examples 1-2 were tested.

[0111] The density of the tungsten-copper composite materials in Example 1 and Comparative Examples 1-2 was measured according to the ASTM B311-22 standard test method for determining the density of sintered metal materials. The hardness of the tungsten-copper composite materials in Example 1 and Comparative Examples 1-2 was tested according to the method in GB / T4340.1-2009 for Vickers hardness test of metal materials. Seven data points were collected in the test, and the average value was obtained after removing the maximum value. The conductivity of the tungsten-copper composite materials in Example 1 and Comparative Examples 1-2 was tested according to the method in ASTM B193 standard for testing the resistance of conductive materials. The density, hardness and conductivity measurement results are shown in Table 3.

[0112] Table 3 Physical and mechanical properties of tungsten-copper composite materials prepared in Example 1 and Comparative Examples 1-2

[0113] Sample name Example 1 Comparative Example 1 Comparative Example 2 Density / % 98.2 90.3 93.9 Vickers hardness / HV 394.1 219.7 295.6 Conductivity IACS 36.3 10.8 25.1

[0114] As can be seen from Table 3, the hardness, density, hardness, and electrical conductivity of the tungsten-copper composite materials prepared in Comparative Examples 1 and 2 are all much lower than those of the tungsten-copper composite material prepared in Example 1. This indicates that at the same relatively low sintering temperature (980°C), sintering without a DC electric field assisted sintering not only results in a longer heating rate and holding time, but also results in a less dense sintered material. The sintering temperature in Example 1 is 980°C, while the sintering temperature in Comparative Example 2 is 1200°C. This indicates that the sintering temperature of the tungsten-copper composite material is significantly reduced after adding a DC electric field assisted sintering, and the prepared composite material is more dense, takes less time, and is more efficient.

[0115] 4) The tensile properties of the tungsten-copper composite materials prepared in Example 1 and Example 4 were tested

[0116] According to GB / T 228.1 Metallic Materials Tensile Test Part 1: Room Temperature Test Method, the tungsten-copper composite materials in Example 1 and Example 4 were subjected to tensile tests to measure their tensile strength. The stress-strain curves are shown in FIG. Figure 2 shown.

[0117] from Figure 2 The tensile strengths of the tungsten-copper composite materials prepared in Examples 1 and 4 are shown to be approximately 468 MPa and 433 MPa, respectively. The tensile strength of Example 1 is higher than that of Example 4. This indicates that the composite material prepared by mechanically alloying the copper powder and nickel powder before mixing with the tungsten powder has a higher bonding strength. This is because the tungsten powder and nickel powder are mechanically alloyed in advance using high-energy ball milling, and a nickel coating is pre-formed on the surface of the tungsten powder, which improves the wettability between tungsten and copper. At high temperatures, nickel diffuses into the copper matrix to form a gradient interface, which optimizes the wetting behavior of tungsten and copper, promotes the expansion of copper on the surface of the tungsten particles, and enhances the bonding strength of tungsten and copper.

[0118] 5) XRD test of the tungsten-copper composite materials prepared in Examples 1-3

[0119] According to the test method in GB / T5618-2014 X-ray diffraction analysis method and technical conditions, the tungsten-copper composite materials prepared in Examples 1-3 and pure tungsten and pure copper were subjected to XRD phase tests. The results are as follows: Figure 3 shown.

[0120] from Figure 3 It can be seen that the tungsten and copper in the tungsten-copper composite materials prepared in Examples 1-3 exist as single phases, without solid solution in each other or forming an intermetallic compound. Instead, they are simply a composite material consisting of a uniform mixture of two phases. Since XRD generally only measures the sample surface, the nickel content is low and diffuses into the copper, so the characteristic peaks of copper are not detected here.

[0121] at the same time Figure 2 Mainly to illustrate the problem of tungsten and copper maintaining their respective single phases

[0122] 6) The surface morphologies of the tungsten-copper composite material in Example 1 and the tungsten-copper composite material in Comparative Examples 1-2 were observed.

[0123] According to the test method in GB / T 20307-2006, the surface morphology of the tungsten-copper composite materials in Example 1 and Comparative Examples 1-2 was observed by scanning electron microscope. Figure 4 shown.

[0124] from Figure 4 It can be seen that the tungsten-copper composite material prepared in Example 1 has a denser structure and smaller grain size, while the tungsten-copper composite material prepared in Comparative Example 1 is not dense at 980°C due to the lack of electric field assisted sintering, and is in a loose granular state with low density. This shows that ordinary hot pressing sintering at 980°C cannot sinter into a sintered shape. The tungsten-copper composite material prepared in Comparative Example 2 has obvious defects and coarse grains, indicating that ordinary hot pressing sintering also has many defects after increasing the sintering temperature. If the density of Comparative Example 2 is to be further improved, the sintering temperature and holding time need to be increased, which makes the grains of the structure coarser and also greatly affects the production efficiency.

[0125] 7) The tungsten-copper composite material in Example 1 was subjected to a high-temperature reciprocating friction and wear test with commercially available pure tungsten.

[0126] According to the ASTM G133 linear reciprocating friction and wear test method, the tungsten-copper composite material in Example 1 was subjected to high-temperature reciprocating friction and wear together with a commercially available pure tungsten sample. The temperature was 800°C, the load was 30N, the reciprocating friction frequency was 10Hz, the test time was 30min, and the grinding balls were silicon carbide ceramic balls. After the test, the change in the friction coefficient was recorded and the wear scar 3D map was taken by laser confocal microscopy and the volume wear was measured. Figure 5-7 shown.

[0127] from Figure 5 It can be seen that the high-performance tungsten-copper composite material prepared in Example 1 has a lower friction coefficient at a high temperature of 800°C than pure tungsten. This is because copper plays a "lubricating" role in the tungsten matrix during high-temperature friction and wear, thereby reducing the friction coefficient. Figure 6 、 Figure 7 It can be seen that the high-performance tungsten-copper composite material prepared in Example 1 has smaller wear scars and a lower volume wear rate than pure tungsten, indicating that the prepared tungsten-copper composite material is more adaptable to harsh working conditions such as high-temperature friction.

[0128] 8) The tungsten-copper composite material in Example 1 was subjected to a current-carrying friction and wear test with commercially available pure copper.

[0129] According to the standard test method of ASTM G99 pin-on-disk wear test, the tungsten-copper composite material in Example 1 and a commercially available pure copper sample were subjected to a current-carrying friction and wear test with a load of 80N, a current of 300A, and a turntable linear speed of 350km / h. After the test, the volume wear loss rate was recorded as follows: Figure 8 As shown; According to the test method in GB / T 20307-2006, the tungsten-copper composite material of Example 1 and commercially available pure copper were subjected to a current-carrying friction and wear test and the surface morphology was observed by scanning electron microscopy. The surface morphology is shown in FIG. Figure 9 shown.

[0130] from Figure 8 It can be seen that the tungsten-copper composite material prepared in Example 1 has a low volume wear rate in current-carrying friction and wear, and is relatively wear-resistant in the harsh working environment of high-speed operation with a large load current. This is because the softer copper is evenly distributed in the continuous hard matrix tungsten, and it has both the lubrication of copper and the wear resistance of tungsten.

[0131] from Figure 9 It can be seen that after the current-carrying friction and wear test, the tungsten-copper composite material prepared in Example 1 has "furrows" and "peeling pits", indicating that the current-carrying friction and wear is mainly abrasive wear, while the surface morphology of the pure copper sample not only has "furrows" but also local melting on the surface, indicating that the copper sample has suffered from more serious abrasive wear and arc erosion under the harsh working conditions of high-speed current-carrying friction and wear. The tungsten-copper composite material prepared in Example 1 generates high temperature due to friction heat under high-speed current-carrying friction and wear, or generates arcs under offline action, causing instantaneous high temperature. This pseudo-alloy combination of tungsten-copper composite material can be applied to instantaneous high temperature. This is because the low-melting-point copper melts in the continuous tungsten matrix (high melting point) under instantaneous high temperature and quickly cools down to take away the heat, which plays a cooling role. At the same time, the hard tungsten matrix on the surface is almost unaffected and can maintain normal working conditions.

[0132] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and the changes still fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-performance tungsten-copper composite material by electric field assisted hot pressing sintering, characterized in that: The following steps are involved: (1) Preparation of tungsten powder, copper powder and nickel powder: Take tungsten powder, copper powder and nickel powder according to the following mass percentage: W 70-90%, Cu 10-30%, Ni 0-8%; (2) Pretreatment of tungsten powder, copper powder and nickel powder: mixing by ball milling to obtain a uniformly mixed tungsten-copper composite material powder; (3) Preparation of high-performance tungsten-copper composite materials: The tungsten-copper composite material powder is sintered by hot pressing assisted by a DC electric field to obtain a high-performance tungsten-copper composite material.

2. The method for preparing a high-performance tungsten-copper composite material by electric field assisted hot pressing sintering according to claim 1, characterized in that: In step (1), W 75-82%, Cu 15-22%, and Ni 3-6% are taken according to the following mass percentages.

3. The method for preparing a high-performance tungsten-copper composite material by electric field assisted hot pressing sintering according to claim 2, characterized in that: The pretreatment of tungsten powder, copper powder and nickel powder in step (2) includes: (2.1) Mechanical alloying of copper powder and nickel powder: Copper powder and nickel powder are mechanically alloyed using a ball mill under protective gas to obtain copper-nickel alloy powder; (2.2) Mixing the mechanically alloyed copper-nickel alloy powder and tungsten powder: The copper-nickel alloy powder and tungsten powder are mechanically alloyed using a ball mill under a protective gas to obtain a tungsten-copper composite material powder.

4. The method for preparing a high-performance tungsten-copper composite material by electric field assisted hot pressing sintering according to claim 3, characterized in that: In step (2.1), the copper powder and the nickel powder are subjected to mechanical alloying treatment using a ball mill under the action of a protective gas, including: using zirconia balls, the mass ratio of the zirconia balls to the copper powder and the nickel powder is 8 to 12:1, the copper powder and the nickel powder are placed in the ball mill, argon gas is introduced for protection, the speed is adjusted to 300 to 400 r / min, the ball mill is set to alternate forward and reverse rotation, the interval between forward and reverse rotation is 10 to 20 minutes, each ball milling is 20 to 40 minutes, and the total ball milling time is 15 to 30 hours. After the mechanical alloying is completed, the powder is cooled to room temperature and then taken out for sieving.

5. The method for preparing a high-performance tungsten-copper composite material by electric field assisted hot pressing sintering according to claim 3, characterized in that: In step (2.2), the copper-nickel alloy powder and the tungsten powder are subjected to mechanical alloying treatment using a ball mill under the action of a protective gas, including: using zirconia balls, the mass ratio of the zirconia balls to the copper-nickel alloy powder and the tungsten powder is 1 to 2:1, the copper-nickel alloy powder and the tungsten powder are placed in the ball mill, argon gas is introduced for protection, the speed is adjusted to 150 to 250 r / min, the ball mill is set to alternate forward and reverse rotations, the interval between forward and reverse rotations is 150 to 20 minutes, each ball milling is 20 to 40 minutes, and the total ball milling time is 2 to 4 hours. After the mechanical alloying is completed, the powder is cooled to room temperature and then taken out for sieving.

6. The method for preparing a high-performance tungsten-copper composite material by electric field assisted hot pressing sintering according to any one of claims 1 to 5, characterized in that: The particle size of the tungsten powder in step (1) is 5 to 15 μm, the particle size of the copper powder is 10 to 35 μm, and the particle size of the nickel powder is 15 to 45 μm. The purity of the tungsten powder, copper powder and nickel powder is all above 99.9%.

7. The method for preparing a high-performance tungsten-copper composite material by electric field assisted hot pressing sintering according to any one of claims 1 to 5, characterized in that: The DC current of the DC electric field in step (3) is 1000 to 4500A.

8. The method for preparing a high-performance tungsten-copper composite material by electric field assisted hot pressing sintering according to any one of claims 1 to 5, characterized in that: In step (3), a graphite mold is used during hot pressing and sintering, and the vacuum degree during hot pressing and sintering is 10 -1 ~10 - 3 Pa, pressure is 30-50 MPa, heating rate is 80-200℃ / min, sintering temperature is 950-1050℃, and holding time is 5-20min.

9. A high performance tungsten copper composite material, characterized in that: The method according to any one of claims 1 to 8 is used to prepare the product.

10. Use of the high-performance tungsten-copper composite material according to claim 9 in the preparation of high-temperature friction and wear or current-carrying friction and wear products.

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