Copper-tungsten alloy and preparation process thereof

Abstract

The invention belongs to the technical field of tungsten-copper alloy materials, and particularly relates to a copper-tungsten alloy and a preparation process thereof.The preparation process includes the steps that after tungsten powder is dried and ball-milled, plasma activating treatment is conducted on the surface of the tungsten powder under the ultrasonic vibration effect; under the action of ultrasonic vibration, a magnetron sputtering method is adopted for sputtering a copper plating layer on the surface of the activated tungsten powder, and copper-coated tungsten composite powder is obtained; the copper-coated tungsten composite powder and copper powder are evenly mixed, vacuum hot pressing sintering is conducted, and an initial-state copper-tungsten alloy block is prepared; and the initial-state copper-tungsten alloy block is subjected to semi-liquid sintering, and the copper-tungsten alloy is prepared. The surface of the tungsten powder is coated with a layer of high-purity copper with a certain thickness on the basis of the magnetron sputtering method, impurity elements in the tungsten-copper alloy can be remarkably reduced while effective modification of a copper-tungsten interface is achieved, the structure uniformity of the tungsten-copper alloy is improved, and finally the tungsten-copper alloy with the uniform structure and high compactness is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of tungsten-copper alloy materials and relates to a copper-tungsten alloy and a preparation process thereof. Background Art

[0002] Tungsten copper alloy has high density, high strength, high ablation resistance and welding resistance, as well as good thermal conductivity, electrical conductivity and high temperature performance. Therefore, it is widely used in various electrical contact materials for core components of high-voltage circuit breakers, electrode materials for EDM, and materials for transferring large heat flux devices. As a typical pseudo alloy, tungsten copper alloy, coupled with the high melting point of tungsten, determines that tungsten copper can only be produced through special preparation technologies such as powder metallurgy technology. Its preparation process generally involves two key links: powder preparation and powder molding.

[0003] Powder preparation is the key technical basis for obtaining tungsten-copper alloy. Since the melting points of tungsten and copper are very different, it is not feasible to prepare tungsten-copper alloy powder by traditional technical means such as atomization of alloy powder. At present, the composite powder used to prepare tungsten-copper alloy can be a mixed powder of tungsten and copper. This type of powder is generally obtained by mechanical stirring such as a mixer or ball mill. The uniformity of the obtained mixed powder is poor and the ball milling mixing process often introduces some unnecessary impurities, which is extremely unfavorable to the thermal conductivity and other properties of tungsten-copper alloy; some coated powders can also be used to prepare tungsten-copper alloy. The organizational uniformity of this type of powder is usually significantly better than that of tungsten and copper mixed powders obtained by mechanical mixing, and the interface bonding effect of tungsten and copper in the obtained composite powder is better, which is extremely beneficial for the preparation of high-performance tungsten-copper alloy.

[0004] At present, given that coated composite powders have good microscopic uniformity and good surface bonding effects. At present, people have conducted a lot of research on the preparation of coated composite powders, and a variety of methods have emerged. The most widely used coating methods are: chemical vapor deposition, precipitation method, sol-gel method, chemical plating method, etc. These methods all belong to the field of chemical methods. Usually, chemical methods will introduce more carbon, oxygen atoms, and metal impurities such as iron into the precipitated metal micro-nano particles. These impurity elements weaken the purity of the tungsten-copper alloy prepared by chemically coating the powder and affect the uniformity of the structure. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a copper-tungsten alloy and a preparation process thereof. The present invention copper-plates tungsten powder by magnetron sputtering under vacuum conditions to obtain a high-activity copper-coated tungsten composite powder with uniform structure and high purity, and further adopts vacuum hot pressing sintering to obtain a copper-tungsten bulk alloy. The obtained alloy has few impurity elements, uniform structure and high density; at the same time, since the copper layer coated by magnetron sputtering exhibits a metastable state, the sintering time during the hot pressing sintering process is short and the energy consumption is low. The present invention solves the problem of uneven structure and high impurity content of copper-tungsten alloy prepared by traditional methods, and also effectively reduces the sintering energy consumption.

[0006] The present invention is achieved through the following technical solutions.

[0007] The present invention provides a preparation process of a copper-tungsten alloy, comprising the following steps:

[0008] After the tungsten powder is dried and ball-milled, the surface of the tungsten powder is plasma activated under the action of ultrasonic vibration. This not only removes the residual impurities on the surface of the tungsten powder, but also increases the surface energy of the tungsten powder, which can better combine with the coated metal and make the combination stronger.

[0009] Under the action of ultrasonic vibration, a copper coating is sputtered on the surface of the activated tungsten powder particles by magnetron sputtering until the copper coating thickness is 0.2-20μm to obtain a copper-coated tungsten composite powder. After the tungsten powder particles are activated, the increase in surface energy allows the tungsten powder to form a strong chemical bond with copper; the tungsten powder is in a continuous vibration state during the coating process, and the coating rate is controlled at the same time, so as to achieve uniform coating on each surface of the particles, which lays an important foundation for the uniformity of the structure of the tungsten-copper bulk alloy; since the target materials used in magnetron sputtering are all high-purity (99.99%), and the sputtering process is completed completely under high vacuum conditions, the purity of the obtained copper-coated tungsten composite powder is high, avoiding the presence of impurities inside the particles.

[0010] The copper-coated tungsten composite powder and the pure copper powder are uniformly mixed and vacuum hot-pressed and sintered to prepare an initial copper-tungsten alloy block.

[0011] The initial copper-tungsten alloy block is subjected to semi-liquid sintering. During the semi-liquid sintering process, part of the pure copper melts, and the molten liquid copper fills the micro-nano pores existing in the initial copper-tungsten alloy block to obtain a copper-tungsten alloy. There must be some tiny gaps between the copper-coated tungsten powder particles during the hot pressing process. The existence of these gaps leads to the existence of some holes in the hot-pressed sintered block, which is an inevitable phenomenon of traditional sintering technologies including vacuum hot pressing sintering, plasma rapid sintering, and high-pressure sintering. On the basis of hot pressing sintering, the present invention uses semi-liquid sintering (i.e., pure copper partially melts under sintering temperature conditions) to effectively fill the micro-nano pores existing in the hot-pressed sintered blank with molten liquid copper, which is beneficial to improving the bonding effect and density of the sintered structure.

[0012] In a preferred embodiment of the present invention, a continuous magnetron sputtering coating device is used for plasma activation treatment, and the platform is kept vibrating during the treatment process. The specific parameters are: the protective atmosphere is Ar, the working gas pressure is 0.5Pa~1.0Pa, the treatment time is 5min~30min, the temperature is room temperature, the power is 200W~600W, and the bias voltage is 80V~200V.

[0013] In a preferred embodiment of the present invention, a continuous magnetron sputtering coating device is used for magnetron sputtering, and the platform vibration is maintained during the deposition process. The parameters are: the working atmosphere is Ar, the working gas pressure is 0.2Pa~0.6Pa, the magnetron sputtering power is 800W~1200W, the sputtering time is 50min~120min, and the vacuum chamber heating temperature is 40℃~80℃.

[0014] In a preferred embodiment of the present invention, the mass ratio of the copper-clad tungsten composite powder to the pure copper powder is 0.26-0.75:1.

[0015] In a preferred embodiment of the present invention, during vacuum hot pressing sintering, the vacuum degree is 1 × 10 -3 Pa, the sintering pressure is 20MPa~60MPa, the temperature is 850℃~950℃, the holding time is 20min~60min, and the cooling method is furnace cooling.

[0016] In a preferred embodiment of the present invention, during semi-liquid sintering, the vacuum degree is 1 × 10 -3 Pa, 20MPa~60MPa, temperature is 1085℃~1200℃, holding time is 20min~60min, and cooling method is furnace cooling.

[0017] In a preferred embodiment of the present invention, after semi-liquid sintering, the ratio of the mass of copper-tungsten powder to the mass of pure copper in the copper-tungsten alloy is 0.16-0.55:1.

[0018] In a preferred embodiment of the present invention, the particle size of the tungsten powder is 1 μm to 8 μm, and the tungsten powder is ball-milled for 0.5 h after being dried. The purity of the copper target and copper powder used in magnetron sputtering is ≥ 99.99%.

[0019] The present invention also provides a copper-tungsten alloy prepared by the above preparation process.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention copper-plated tungsten powder by magnetron sputtering under vacuum conditions to obtain a high-activity copper-coated tungsten composite powder with uniform structure and high purity, and then performed vacuum hot pressing sintering and semi-liquid sintering to obtain a copper-tungsten alloy. The prepared copper-tungsten alloy has high purity and uniform structure. The specific mechanism is:

[0022] The present invention performs plasma activation treatment on tungsten powder particles before coating, which can not only remove residual impurities on the surface of tungsten powder, but also increase the surface energy of tungsten powder, so that it can better combine with the plated metal and make the combination stronger; in an ultrasonic vibration environment, magnetron sputtering is used for copper plating. Unlike the metal layer obtained by electroplating method which is only mechanically attached to the surface of tungsten powder, after the tungsten powder particles are activated, the increase in surface energy enables the tungsten powder to form a strong chemical bond with copper; the tungsten powder is in a continuous vibration state during the coating process, and the coating rate is controlled at the same time, so as to achieve uniform coating on each surface of the particle, which lays an important foundation for the uniformity of the structure of the tungsten-copper bulk alloy; because the target materials used in magnetron sputtering are all high-purity (99.99%), and the sputtering process is completely completed under high vacuum conditions, the purity of the obtained copper-coated tungsten composite powder is high, and the presence of impurity components inside the particles is avoided.

[0023] There must be some tiny gaps between the copper-coated tungsten powder particles during the hot pressing process. The existence of these gaps leads to the existence of some holes in the hot-pressed sintered block, which is an inevitable phenomenon in traditional sintering technologies including vacuum hot pressing sintering, plasma rapid sintering, and high-pressure sintering. On the basis of hot pressing sintering, the present invention uses semi-liquid sintering (i.e., pure copper partially melts under sintering temperature conditions) to effectively fill the micro-nano holes in the hot-pressed sintered blank with molten liquid copper, which is beneficial to improving the bonding effect and density of the sintered structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 In the figure, (a) is a cross-sectional image of the copper-clad tungsten composite powder obtained in step 1 of Example 1, and (b) and (c) are EDS energy spectrum element distribution diagrams of the copper-clad tungsten composite powder, wherein (b) is tungsten element and (c) is copper element.

[0025] Figure 2 This is the SEM image of the initial copper-tungsten alloy block obtained in step 2 of Example 1.

[0026] Figure 3 This is the SEM image of the copper-tungsten alloy obtained in step 3 of Example 1.

[0027] Figure 4 This is the SEM image of the copper-tungsten alloy obtained in Comparative Example 1.

[0028] Figure 5 This is the metallographic image of the copper-tungsten alloy obtained in Comparative Example 1.

[0029] Figure 6 This is the metallographic image of the copper-tungsten alloy obtained in step 3 of Example 1.

[0030] Figure 7 This is a diagram of the copper-tungsten alloy grain size obtained in step 3 of Example 1.

[0031] Figure 8 This is the grain size diagram of the copper-tungsten alloy obtained in Comparative Example 1. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is further described below in conjunction with specific embodiments and drawings, but the embodiments are not intended to limit the present invention. The experimental methods and detection methods described in the following embodiments are conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0033] Example 1

[0034] A preparation process of copper-tungsten alloy comprises the following steps:

[0035] Step 1: Preparation of copper-coated tungsten composite powder

[0036] 1) Disperse tungsten powder into the cavity of the oven equipment. The particle size of the tungsten powder is 1 μm to 8 μm. Before copper plating by magnetron sputtering, dry the tungsten powder at 100°C for 0.5 h and then ball mill for 0.5 h to fully disperse the agglomerated tungsten powder.

[0037] 2) Using continuous magnetron sputtering coating equipment, the tungsten powder particles obtained in step 1) are evenly spread on the heating platform and then the platform is placed on the conveyor belt. The platform is kept vibrating during the deposition process, and the parameters are adjusted to perform plasma activation treatment on the tungsten powder particles; the specific parameters are: temperature is room temperature, working atmosphere is Ar, working gas pressure is 0.8 Pa, cleaning time is 10 min, power is 400 W, and bias voltage is 100 V.

[0038] 3) Using the same equipment, adjusting the magnetron sputtering parameters, sputtering a copper layer on the surface of the activated tungsten powder; the specific magnetron sputtering parameters are: working atmosphere is Ar, working pressure is 0.6Pa, magnetron sputtering power is 1000W, sputtering time is 50min, vacuum chamber heating temperature is 50℃, and copper-coated tungsten composite powder is obtained. The thickness of the copper coating is distributed in the range of 0.2μm to 1.1μm. The post-treatment process of magnetron sputtering is: vacuum drying-vacuum encapsulation.

[0039] Step 2: Vacuum hot pressing sintering

[0040] Pour the copper-coated tungsten composite powder and high-purity copper powder into a Φ30 graphite mold, with the ratio of the two powders being about 0.75:1. Then put it into a vacuum hot-pressing sintering furnace, evacuate and pressurize it. When the vacuum degree is lower than 10Pa, start sintering. The sintering pressure is 50MPa, the temperature is 850℃, the insulation time is 20min, and the vacuum degree is 1 × 10 -3 Pa, and the cooling method is furnace cooling to obtain the initial copper-tungsten alloy block.

[0041] Step 3: Semi-liquid sintering

[0042] 5) Place the initial copper-tungsten alloy block into a Φ50 graphite mold, and start sintering when the vacuum degree is lower than 10Pa. The sintering pressure is 50MPa, the temperature is 1085℃, the insulation time is 20min, and the vacuum degree is 1 × 10 -3 The cooling method is furnace cooling to obtain copper-tungsten alloy.

[0043] Example 2

[0044] A preparation process of copper-tungsten alloy comprises the following steps:

[0045] Step 1: Preparation of copper-coated tungsten composite powder

[0046] 1) Disperse tungsten powder into the cavity of the oven equipment. The particle size of the tungsten powder is 1 μm to 8 μm. Before copper plating by magnetron sputtering, dry the tungsten powder at 100°C for 0.5 h and then ball mill for 0.5 h to fully disperse the agglomerated tungsten powder.

[0047] 2) Using continuous magnetron sputtering coating equipment, the tungsten powder particles obtained in step 1) are evenly spread on the heating platform and then the platform is placed on the conveyor belt. The platform is kept vibrating during the deposition process, and the parameters are adjusted to perform plasma activation treatment on the tungsten powder particles; the specific parameters are: temperature is room temperature, working atmosphere is Ar, working gas pressure is 0.8 Pa, cleaning time is 10 min, power is 400 W, and bias voltage is 100 V.

[0048] 3) Using the same equipment, adjusting the magnetron sputtering parameters, sputtering a copper layer on the surface of the activated tungsten powder; the specific magnetron sputtering parameters are: working atmosphere is Ar, working pressure is 0.6Pa, magnetron sputtering power is 1000W, sputtering time is 80min, vacuum chamber heating temperature is 50℃, and copper-coated tungsten composite powder is obtained. The thickness of the copper coating is distributed in the range of 7μm to 8μm. The post-treatment process of magnetron sputtering is: vacuum drying-vacuum encapsulation.

[0049] Step 2: Vacuum hot pressing sintering

[0050] Pour the copper-coated tungsten composite powder and high-purity copper powder into a Φ30 graphite mold, with the ratio of the two powders being about 0.7:1. Then put it into a vacuum hot-pressing sintering furnace, evacuate and pressurize it. When the vacuum degree is lower than 10Pa, start sintering. The sintering pressure is 60MPa, the temperature is 950℃, the insulation time is 30min, and the vacuum degree is 1 × 10 -3 Pa, and the cooling method is furnace cooling to obtain the initial copper-tungsten alloy block.

[0051] Step 3: Semi-liquid sintering

[0052] 5) Place the initial copper-tungsten alloy block into a Φ50 graphite mold, and start sintering when the vacuum degree is lower than 10Pa. The sintering pressure is 50MPa, the temperature is 1085℃, the insulation time is 20min, and the vacuum degree is 1 × 10 -3 The cooling method is furnace cooling to obtain copper-tungsten alloy.

[0053] Example 3

[0054] A preparation process of copper-tungsten alloy comprises the following steps:

[0055] Step 1: Preparation of copper-coated tungsten composite powder

[0056] 1) Disperse tungsten powder into the cavity of the oven equipment. The particle size of the tungsten powder is 1 μm to 8 μm. Before copper plating by magnetron sputtering, dry the tungsten powder at 100°C for 0.5 h and then ball mill for 0.5 h to fully disperse the agglomerated tungsten powder.

[0057] 2) Using continuous magnetron sputtering coating equipment, the tungsten powder particles obtained in step 1) are evenly spread on the heating platform and then the platform is placed on the conveyor belt. The platform is kept vibrating during the deposition process, and the parameters are adjusted to perform plasma activation treatment on the tungsten powder particles; the specific parameters are: temperature is room temperature, working atmosphere is Ar, working gas pressure is 0.8 Pa, cleaning time is 10 min, power is 400 W, and bias voltage is 100 V.

[0058] 3) Using the same equipment, adjusting the magnetron sputtering parameters, sputtering a copper layer on the surface of the activated tungsten powder; the specific magnetron sputtering parameters are: working atmosphere is Ar, working pressure is 0.6Pa, magnetron sputtering power is 1000W, sputtering time is 110min, vacuum chamber heating temperature is 50℃, and copper-coated tungsten composite powder is obtained. The thickness of the copper coating is distributed in 18μm~19μm. The post-treatment process of magnetron sputtering is: vacuum drying-vacuum encapsulation.

[0059] Step 2: Vacuum hot pressing sintering

[0060] Pour the copper-coated tungsten composite powder and high-purity copper powder into a Φ30 graphite mold, with the ratio of the two powders being about 0.7:1. Then put it into a vacuum hot-pressing sintering furnace, evacuate and pressurize it. When the vacuum degree is lower than 10Pa, start sintering. The sintering pressure is 20MPa, the temperature is 900℃, the insulation time is 60min, and the vacuum degree is 1 × 10 -3 Pa, and the cooling method is furnace cooling to obtain the initial copper-tungsten alloy block.

[0061] Step 3: Semi-liquid sintering

[0062] 5) Place the initial copper-tungsten alloy block into a Φ50 graphite mold, and start sintering when the vacuum degree is lower than 10Pa. The sintering pressure is 20MPa, the temperature is 1200℃, the insulation time is 20min, and the vacuum degree is 1 × 10 -3 The cooling method is furnace cooling to obtain copper-tungsten alloy.

[0063] Example 4

[0064] A preparation process of copper-tungsten alloy comprises the following steps:

[0065] Step 1: Preparation of copper-coated tungsten composite powder

[0066] 1) Disperse tungsten powder into the cavity of the oven equipment. The particle size of the tungsten powder is 1 μm to 8 μm. Before copper plating by magnetron sputtering, dry the tungsten powder at 100°C for 0.5 h and then ball mill for 0.5 h to fully disperse the agglomerated tungsten powder.

[0067] 2) Using continuous magnetron sputtering coating equipment, the tungsten powder particles obtained in step 1) are evenly spread on the heating platform and then the platform is placed on the conveyor belt. The platform is kept vibrating during the deposition process, and the parameters are adjusted to perform plasma activation treatment on the tungsten powder particles; the specific parameters are: temperature is room temperature, working atmosphere is Ar, working gas pressure is 0.5 Pa, cleaning time is 30 min, power is 600 W, and bias voltage is 80 V.

[0068] 3) Using the same equipment, adjusting the magnetron sputtering parameters, sputtering a copper layer on the surface of the activated tungsten powder; the specific magnetron sputtering parameters are: working atmosphere is Ar, working pressure is 0.2Pa, magnetron sputtering power is 800W, sputtering time is 110min, vacuum chamber heating temperature is 50℃, and copper-coated tungsten composite powder is obtained. The thickness of the copper coating is distributed in 19μm~20μm. The post-treatment process of magnetron sputtering is: vacuum drying-vacuum encapsulation.

[0069] Step 2: Vacuum hot pressing sintering

[0070] Pour the copper-coated tungsten composite powder and high-purity copper powder into a Φ30 graphite mold, with the ratio of the two powders being about 0.7:1. Then put it into a vacuum hot-pressing sintering furnace, evacuate and pressurize it. When the vacuum degree is lower than 10Pa, start sintering. The sintering pressure is 50MPa, the temperature is 850℃, the insulation time is 20min, and the vacuum degree is 1 × 10 -3 Pa, and the cooling method is furnace cooling to obtain the initial copper-tungsten alloy block.

[0071] Step 3: Semi-liquid sintering

[0072] 5) Place the initial copper-tungsten alloy block into a Φ50 graphite mold, and start sintering when the vacuum degree is lower than 10Pa. The sintering pressure is 50MPa, the temperature is 1100℃, the insulation time is 20min, and the vacuum degree is 1 × 10 -3 The cooling method is furnace cooling to obtain copper-tungsten alloy.

[0073] Example 5

[0074] A preparation process of copper-tungsten alloy comprises the following steps:

[0075] Step 1: Preparation of copper-coated tungsten composite powder

[0076] 1) Disperse tungsten powder into the cavity of the oven equipment. The particle size of the tungsten powder is 1 μm to 8 μm. Before copper plating by magnetron sputtering, dry the tungsten powder at 100°C for 0.5 h and then ball mill for 0.5 h to fully disperse the agglomerated tungsten powder.

[0077] 2) Using continuous magnetron sputtering coating equipment, the tungsten powder particles obtained in step 1) are evenly spread on the heating platform and then the platform is placed on the conveyor belt. The platform is kept vibrating during the deposition process, and the parameters are adjusted to perform plasma activation treatment on the tungsten powder particles; the specific parameters are: temperature is room temperature, working atmosphere is Ar, working gas pressure is 1Pa, cleaning time is 5min, power is 200W, and bias voltage is 200V.

[0078] 3) Using the same equipment, adjusting the magnetron sputtering parameters, sputtering a copper layer on the surface of the activated tungsten powder; the specific magnetron sputtering parameters are: working atmosphere is Ar, working pressure is 0.2Pa, magnetron sputtering power is 1200W, sputtering time is 120min, vacuum chamber heating temperature is 50℃, and copper-coated tungsten composite powder is obtained. The thickness of the copper coating is distributed in 19μm~20μm. The post-treatment process of magnetron sputtering is: vacuum drying-vacuum encapsulation.

[0079] Step 2: Vacuum hot pressing sintering

[0080] Pour the copper-coated tungsten composite powder and high-purity copper powder into a Φ30 graphite mold, with the ratio of the two powders being about 0.7:1. Then put it into a vacuum hot-pressing sintering furnace, evacuate and pressurize it. When the vacuum degree is lower than 10Pa, start sintering. The sintering pressure is 50MPa, the temperature is 850℃, the insulation time is 20min, and the vacuum degree is 1 × 10 -3 Pa, and the cooling method is furnace cooling to obtain the initial copper-tungsten alloy block.

[0081] Step 3: Semi-liquid sintering

[0082] 5) Place the initial copper-tungsten alloy block into a Φ50 graphite mold, and start sintering when the vacuum degree is lower than 10Pa. The sintering pressure is 50MPa, the temperature is 1085℃, the insulation time is 20min, and the vacuum degree is 1 × 10 -3 The cooling method is furnace cooling to obtain copper-tungsten alloy.

[0083] Comparative Example 1

[0084] Compared with Example 1, one-step sintering is adopted, which specifically includes the following steps:

[0085] Step 1: Preparation of copper-coated tungsten composite powder

[0086] 1) Disperse tungsten powder into the cavity of the oven equipment. The particle size of the tungsten powder is 1 μm to 8 μm. Before copper plating by magnetron sputtering, dry the tungsten powder at 100°C for 0.5 h and then ball mill for 0.5 h to fully disperse the agglomerated tungsten powder.

[0087] 2) Using continuous magnetron sputtering coating equipment, the tungsten powder particles obtained in step 1) are evenly spread on the heating platform and then the platform is placed on the conveyor belt. The platform is kept vibrating during the deposition process, and the parameters are adjusted to perform plasma activation treatment on the tungsten powder particles; the specific parameters are: temperature is room temperature, working atmosphere is Ar, working gas pressure is 0.8 Pa, cleaning time is 10 min, power is 400 W, and bias voltage is 100 V.

[0088] 3) Using the same equipment, adjusting the magnetron sputtering parameters, sputtering a copper layer on the surface of the activated tungsten powder; the specific magnetron sputtering parameters are: working atmosphere is Ar, working pressure is 0.6Pa, magnetron sputtering power is 1000W, sputtering time is 50min, vacuum chamber heating temperature is 50℃, and copper-coated tungsten composite powder is obtained. The thickness of the copper coating is distributed in the range of 0.2μm to 1.1μm. The post-treatment process of magnetron sputtering is: vacuum drying-vacuum encapsulation.

[0089] Step 2: Vacuum hot pressing sintering

[0090] Pour the copper-coated tungsten composite powder and high-purity copper powder into a Φ30 graphite mold, with the ratio of the two powders being about 0.75:1. Then put it into a vacuum hot-pressing sintering furnace, evacuate and pressurize it. When the vacuum degree is lower than 10Pa, start sintering. The sintering pressure is 50MPa, the temperature is 1085℃, the insulation time is 20min, and the vacuum degree is 1 × 10 -3 Pa, and the cooling method is furnace cooling to obtain the initial copper-tungsten alloy block.

[0091] Figure 1 In the figure, (a) is a cross-sectional image of the copper-coated tungsten composite powder obtained in step 1 of Example 1, and (b) and (c) are EDS energy spectrum element distribution diagrams of the copper-coated tungsten composite powder, where (b) is tungsten element and (c) is copper element. It can be seen that the copper coating is evenly plated on the surface of the tungsten powder, and only the composite powder with large particle size after grinding has part of the tungsten exposed.

[0092] Figure 2 This is a SEM image of the initial copper-tungsten alloy block obtained in step 2 of Example 1. It can be seen that the density is low, only some small particles of powder form sintering necks with large particles of powder, and the large particles are not completely fused.

[0093] Figure 3 This is the SEM image of the copper-tungsten alloy obtained in step 3 of Example 1. Figure 4 This is a SEM image of the copper-tungsten alloy obtained in Comparative Example 1. In Comparative Example 1, the alloy is rough and uneven, while the alloy structure in Example 1 is uniform.

[0094] Figure 5 This is the metallographic image of the copper-tungsten alloy obtained in Comparative Example 1. Figure 6 This is the metallographic image of the copper-tungsten alloy obtained in step 3 of Example 1. Compared with Comparative Example 1, Figure 6 The alloy is more dense. It is explained that the present invention first performs vacuum hot pressing sintering and then performs semi-liquid sintering, which is beneficial to improving the density of the alloy.

[0095] Figure 7 This is a diagram of the copper-tungsten alloy grain size obtained in step 3 of Example 1. Figure 8 The copper-tungsten alloy grain size diagram obtained in Comparative Example 1. It can be seen that compared with Comparative Example 1, the copper-tungsten alloy grain size distribution in Example 1 is more uniform, and the grains are smaller, while the copper-tungsten alloy grain size in Comparative Example 1 is more dispersed, and the grain size is larger. It shows that the alloy prepared by the one-step sintering method is not conducive to the refinement of the alloy grains. The remaining embodiments are similar to Example 1 and will not be repeated.

[0096] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, they are also intended to be included.

Claims

1. A process for preparing a copper-tungsten alloy, characterized in that: The following steps are involved: After the tungsten powder is dried and ball-milled, the surface of the tungsten powder is subjected to plasma activation treatment under the action of ultrasonic vibration; Under the action of ultrasonic vibration, a copper coating is sputtered on the surface of the activated tungsten powder by a magnetron sputtering method to obtain a copper-coated tungsten composite powder; The copper-coated tungsten composite powder and the copper powder are uniformly mixed, and vacuum hot-pressed and sintered to prepare an initial copper-tungsten alloy block; The initial copper-tungsten alloy block is semi-liquid sintered. During the semi-liquid sintering process, part of the copper melts, and the molten liquid copper fills the micro-nano pores in the initial copper-tungsten alloy block to obtain the copper-tungsten alloy.

2. The preparation process of the copper-tungsten alloy according to claim 1, characterized in that: The thickness of the magnetron sputtering copper plating layer is 0.2 μm to 20 μm.

3. The preparation process of the copper-tungsten alloy according to claim 1, characterized in that: Continuous magnetron sputtering coating equipment is used for plasma activation treatment. The platform is kept vibrating during the treatment process. The specific parameters are: working atmosphere is Ar, working pressure is 0.5Pa~1.0Pa, treatment time is 5min~30min, temperature is room temperature, power is 200W~600W, and bias voltage is 80V~200V.

4. The preparation process of the copper-tungsten alloy according to claim 1, characterized in that: Continuous magnetron sputtering coating equipment is used for magnetron sputtering. The platform is kept vibrating during the deposition process. The parameters are: working atmosphere is Ar, working gas pressure is 0.2Pa~0.6Pa, magnetron sputtering power is 800W~1200W, sputtering time is 50min~120min, and vacuum chamber heating temperature is 40℃~80℃.

5. The preparation process of the copper-tungsten alloy according to claim 1, characterized in that: The mass ratio of the copper-coated tungsten composite powder to the copper powder is 0.26-0.75:

1.

6. The process for preparing the copper-tungsten alloy according to claim 1, characterized in that: During vacuum hot pressing sintering, under vacuum conditions, the sintering pressure is 20MPa-60MPa, the temperature is 850℃-950℃, and the holding time is 20min-60min.

7. The process for preparing the copper-tungsten alloy according to claim 1, characterized in that: During semi-liquid sintering, under vacuum conditions, the sintering pressure is 20MPa~60MPa, the temperature is 1085℃~1200℃, and the insulation time is 20min~60min.

8. The process for preparing the copper-tungsten alloy according to claim 1, characterized in that: The particle size of the raw material tungsten powder is 1 μm to 8 μm, the purity of the copper target used for magnetron sputtering is ≥ 99.99%, and the purity of the copper powder is ≥ 99.99%.

9. Copper-tungsten alloy prepared according to the preparation process according to any one of claims 1 to 8.

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