Preparation process of high-density tungsten-copper alloy

Abstract

The present invention relates to a preparation process of a high-density tungsten-copper alloy. The preparation process comprises: mixing oxide powder of copper having a certain proportion with oxide powder of tungsten in a dual-power mixer, performing crushing and activation treatment on the mixed powder in a high-speed crusher, and then reducing in a hydrogen atmosphere to obtain the nano tungsten-copper composite powder; and carrying out sheathing, degassing, and hot isostatic pressing treatment on the nano tungsten-copper composite powder, carrying out thermoplastic processing, and then carrying out annealing treatment to obtain the high-density tungsten-copper alloy. The process of the present invention is simple and controllable, has high operability, and is easy to industrialize; the phenomena of component segregation caused by preparation of the tungsten-copper alloy by an infiltration method, and uneven crystal grain size caused by particle aggregation and growth are avoided; and the proportion of the two-phase components can be accurately regulated, so that the tungsten-copper alloy with a tungsten content of 5%-95% can be prepared. The density (relative density) of the prepared tungsten-copper alloy reaches 99.6% or above; the oxygen content is lower than 40 ppm; the alloy has a uniform structure; the crystal grains are fine; and the present invention has wide application prospects and popularization value.

Description

A preparation process of high-density tungsten-copper alloy Technical Field

[0001] The invention belongs to the technical field of alloy material preparation, and in particular relates to a preparation process of a high-density tungsten-copper alloy. Background Art

[0002] Tungsten-copper alloy combines the advantages of tungsten and copper, possessing the low thermal expansion properties of tungsten and the high electrical and thermal conductivity of copper. Its thermal expansion coefficient and thermal and electrical conductivity can be adjusted by adjusting the ratio of tungsten and copper elements. Tungsten-copper alloy has advantages such as high strength, high temperature resistance, arc ablation resistance, and excellent electrical and thermal conductivity. It is widely used in aerospace, aviation, electronics, electricity, metallurgy, machinery, sports equipment and other industries.

[0003] Currently, the industrial preparation of tungsten-copper alloys with copper contents below 50% mainly uses the melt infiltration method to pre-sinter the tungsten skeleton, and then uses melt infiltration of copper liquid. The liquid copper fills the gaps between the particles to achieve material densification, and the alloy density is only 94-95%. At the same time, after the alloy cools to room temperature, the copper will shrink significantly; the overflow of copper on the surface of the sintered body causes the alloy components to segregate, and the tungsten particles to aggregate and grow severely, resulting in coarse and uneven grains; the ratio of the two-phase components cannot be precisely controlled, resulting in poor repeatability of sample performance. Tungsten-copper alloys with copper contents above 50% cannot form a continuous tungsten skeleton due to the low tungsten content, and such alloys cannot be prepared by the melt infiltration method. Currently, there is a lack of a universal preparation process for tungsten-copper alloys with different copper contents. Summary of the Invention

[0004] In response to the above problems, the present invention provides a preparation process for a high-density tungsten-copper alloy, which adopts a three-dimensional mixing-high-speed crushing-hydrogen reduction simplified process technology to prepare tungsten-copper powder, and adopts a hot isostatic pressing-thermoplastic processing-heat treatment process without removing the forming agent. The thermoplastic processing with a sheath avoids alloy oxidation and reduces the oxygen content. With reasonable process parameters, a fine-grained, high-density, and uniformly organized tungsten-copper alloy is prepared, avoiding the component segregation caused by the infiltration method for preparing tungsten-copper alloys and the phenomenon of coarse and uneven grains caused by particle aggregation and growth. The ratio of the two-phase components can be precisely controlled, and the preparation of tungsten-copper alloys in the full composition range (tungsten-copper alloys with different copper contents) can be achieved, and the process has a wide range of applicability.

[0005] The present invention is specifically implemented by the following technical solutions. According to the present invention, a preparation process of a high-density tungsten-copper alloy is proposed, which includes the following steps:

[0006] 1) Copper oxide powder and tungsten oxide powder of a certain ratio are mixed in a dual-power mixer to obtain a mixed powder;

[0007] 2) crushing and activating the mixed powder obtained in step 1) in a high-speed crusher;

[0008] 3) reducing the powder obtained in step 2) under hydrogen atmosphere to obtain nano-tungsten-copper composite powder; the reduction comprises a two-stage hydrogen reduction, wherein the first stage is a hydrogen reduction temperature of 400-550°C, a time of 1-3 h, and a hydrogen flow rate of 10 m 3 / h~20 m 3 / h, powder laying height ≤ 2 / 3; the second stage hydrogen reduction temperature is 750-800 ℃, the time is 2-6 h, and the hydrogen flow rate is 15 m 3 / h~25 m 3 / h, powder spreading height ≤ 2 / 3;

[0009] 4) The tungsten-copper composite powder obtained in step 3) is subjected to encapsulation, degassing, and hot isostatic pressing, and then subjected to thermoplastic processing with the encapsulation, followed by annealing, and a high-density tungsten-copper alloy is obtained after the encapsulation is removed.

[0010] Preferably, in step 1), the speed of the dual-power mixer is set to 500-800 r / min, and the mixing process time is 4-10 hours.

[0011] Preferably, the copper oxide in step 1) is selected from one or more of CuO and Cu2O, and the tungsten oxide is selected from yellow tungsten (WO3), blue tungsten (WO 2.9 ), purple tungsten (WO 2.72 ), one or more of tungsten (WO2).

[0012] Furthermore, in step 2), the time for the crushing and activation treatment is 0.5 to 4 minutes, and the speed of the high-speed crusher is set to 36,000 r / min.

[0013] Furthermore, the sheath in step 4) is a carbon steel sheath, and the specific degassing operation includes: evacuating the sheath with a vacuum pump at room temperature to reduce the vacuum degree to 1×10 -4 Pa~1×10 -2 After Pa, seal welding is performed.

[0014] Preferably, the hot isostatic pressing treatment is performed at a temperature of 900-1070° C., a pressure of 95-160 MPa, and a time of 2-8 h.

[0015] Preferably, the thermoplastic processing is one or a combination of rolling, extrusion or drawing; the total number of passes of the thermoplastic processing is 3 to 10 times, the deformation amount of each pass is 25 to 35%, and the total deformation amount is ≥80%.

[0016] Preferably, the annealing treatment is carried out at 650-900°C in a hydrogen or argon atmosphere or in a vacuum, the annealing holding time is 0.5-2.0 h, and the vacuum degree is less than 10 -2 MPa.

[0017] The density (relative density) of the high-density tungsten-copper alloy prepared according to the above method reaches more than 99.6%, and the impurity oxygen content is less than 40 ppm.

[0018] The above process has a wide range of applications and can also be used to prepare molybdenum-copper alloys. The difference lies in replacing the tungsten oxide in step 1) with molybdenum oxide, which can be selected from one or both of Mo₂O₃ and MoO₂. Furthermore, the present invention allows for the addition of a second phase to the prepared high-density tungsten-copper or molybdenum-copper alloy, thereby producing a doped tungsten-copper or molybdenum-copper alloy. This second phase can be one or more rare earth oxides such as lanthanum oxide, yttrium oxide, and cerium oxide; one or more oxides such as aluminum oxide, zirconium oxide, and titanium oxide; or one or more carbides such as TiC, NbC, and VC.

[0019] Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above technical solution, the present invention can achieve considerable technological advancement and practicality, and has a wide range of utilization value. It has at least the following advantages:

[0020] (1) The present invention adopts a simplified process of three-dimensional mixing-high-speed crushing-hydrogen reduction to prepare tungsten copper powder. The three-dimensional mixing ensures the uniform mixing of the tungsten source and the copper source, the high-speed crushing improves the activity and dispersibility of the powder, and the particle size and morphology of the tungsten copper powder are regulated by the reduction process. The hot isostatic pressing-thermoplastic processing-heat treatment process is adopted, and there is no need to remove the forming agent. The thermoplastic processing with a jacket avoids the oxidation of the alloy and reduces the oxygen content. With reasonable process parameters, a fine-grained, high-density, and uniformly organized tungsten copper alloy can be prepared. Its density (relative density) can reach more than 99.6%, the oxygen content is less than 40ppm, the alloy structure is uniform, and the grains are fine (less than 1μm). The performance is higher than that of publicly reported alloys with the same composition, and it has a very broad application prospect and promotion value.

[0021] (2) The process of the present invention is simple and controllable, highly operable, and easy to industrialize. It avoids the composition segregation caused by the infiltration method for preparing tungsten-copper alloys, and the phenomenon of coarse and uneven grains caused by particle aggregation and growth. The ratio of the two-phase components can be precisely controlled, and the preparation of tungsten-copper alloys with a full composition range (tungsten-copper alloys with different copper contents) can be achieved. The process has a wide range of applicability. The present invention can also be applied to the preparation of second-phase doped tungsten-copper alloys, molybdenum-copper alloys, etc. Type the technical problem description paragraph here. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG1 is a BSEM image of the high-density tungsten-copper alloy prepared in Example 2.

[0023] FIG2 is a BSEM image of the high-density tungsten-copper alloy prepared in Example 4.

[0024] FIG3 is a BSEM image of the high-density tungsten-copper alloy prepared in Example 5. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] Example 1

[0027] 1) CuO powder and WO2 powder were weighed according to the mass ratio of metal Cu to W of 1:9, and the materials were three-dimensionally mixed in a dual-power mixer for 6 h. The speed of the dual-power mixer was set to 600 r / min.

[0028] 2) The mixed powder obtained in step 1) was crushed and activated in a high-speed crusher for 4 minutes at a speed of 36,000 r / min;

[0029] 3) The powder obtained in step 2) is reduced in a hydrogen atmosphere to obtain nano-tungsten-copper composite powder; the reduction includes a two-stage hydrogen reduction, wherein the first stage is a hydrogen reduction temperature of 500 °C, a time of 2.5 h, and a hydrogen flow rate of 10 m 3 / h, powder laying height ≤ 2 / 3; the second stage hydrogen reduction temperature is 800 ℃, the time is 5 h, and the hydrogen flow rate is 10 m 3 / h, powder spreading height ≤2 / 3.

[0030] 4) The tungsten-copper composite powder obtained in step 3) was subjected to sheathing, degassing, and hot isostatic pressing, and then subjected to thermoplastic processing with the sheath, and then kept at 900°C in a hydrogen atmosphere for 2.0 h. After removing the sheath, a high-density tungsten-copper alloy was obtained, and its density (relative density) was 99.6% (density was 16.87 g / cm 3 ), impurity oxygen content is less than 40 ppm.

[0031] The package described in this step is a carbon steel package. The specific degassing operation includes: using a vacuum pump to evacuate the package at room temperature and reduce the vacuum degree to 1×10 -2After the evacuation, the can was placed in a hot isostatic pressing (HIP) machine for 2.5 hours at a temperature of 1050°C and a pressure of 160 MPa. The hot plastic processing involved rolling at 1050°C, with four passes, a deformation of 21% per pass, and a total deformation of 84%.

[0032] Example 2

[0033] 1) Cu2O powder and WO2 powder were weighed according to the mass ratio of metal Cu to W of 1:3, and the materials were mixed in a dual-power mixer for 4 h. The speed of the dual-power mixer was set to 600 r / min.

[0034] 2) The mixed powder obtained in step 1) was crushed and activated in a high-speed crusher for 3 minutes at a speed of 36,000 r / min;

[0035] 3) The powder obtained in step 2) is reduced in a hydrogen atmosphere to obtain nano-tungsten-copper composite powder; the reduction includes a two-stage hydrogen reduction, wherein the first stage is a hydrogen reduction temperature of 450 °C, a time of 3 h, and a hydrogen flow rate of 20 m 3 / h, powder laying height ≤ 2 / 3; the second stage hydrogen reduction temperature is 780 ℃, the time is 4 h, and the hydrogen flow rate is 20 m 3 / h, powder spreading height ≤2 / 3.

[0036] 4) The tungsten-copper composite powder obtained in step 3) was subjected to sheathing, degassing, and hot isostatic pressing, and then subjected to thermoplastic processing with the sheath. Then, the powder was kept at 900°C in a hydrogen atmosphere for 1.5 h. After removing the sheath, a high-density tungsten-copper alloy was obtained, and its density (relative density) was 99.7% (density was 14.68 g / cm 3 ), impurity oxygen content is less than 40 ppm.

[0037] The package described in this step is a carbon steel package. The specific degassing operation includes: using a vacuum pump to evacuate the package at room temperature and reduce the vacuum degree to 0.5×10 -3 After the evacuation, the can was placed in a hot isostatic pressing (HIP) machine for 4 hours at a temperature of 1050°C and a pressure of 130 MPa. Thermoplastic processing was performed using hot extrusion, with a die temperature of 450°C. The can was heated to 1050°C for 30 minutes at an extrusion rate of 10 mm / s and an extrusion ratio of 8. The heat treatment temperature was 900°C.

[0038] Figure 1 is a BSEM image of the high-density tungsten-copper alloy prepared in this example, with a copper content of 25% by mass and a tungsten content of 75% by mass. The dark area in Figure 1 represents the copper phase, and the gray area represents the tungsten phase. As shown in Figure 1, the prepared high-density tungsten-copper alloy has a uniform and dense structure, fine grains, and a tungsten particle size of less than 1 μm. The W and Cu phases are evenly distributed, greatly improving the performance of the alloy.

[0039] Example 3

[0040] 1) CuO powder and WO 2.9 The powders were weighed according to a mass ratio of metal Cu and W of 2:3, and the materials were three-dimensionally mixed in a dual-power mixer for 5 h. The speed of the dual-power mixer was set to 800 r / min.

[0041] 2) The mixed powder obtained in step 1) was crushed and activated in a high-speed crusher for 3 minutes at a speed of 36,000 r / min;

[0042] 3) The powder obtained in step 2) was reduced in a hydrogen atmosphere to obtain nano-tungsten-copper composite powder; the reduction included two-stage hydrogen reduction, wherein the first stage was reduced at a temperature of 450 °C for 4 h and a hydrogen flow rate of 15 m 3 / h, powder laying height ≤ 2 / 3; the second stage hydrogen reduction temperature is 800 ℃, time is 3 h, hydrogen flow rate is 15 m 3 / h, powder spreading height ≤2 / 3.

[0043] 4) The tungsten-copper composite powder obtained in step 3) was subjected to sheathing, degassing, and hot isostatic pressing, and then subjected to thermoplastic processing with the sheath, and then kept at 700°C in an argon atmosphere for 1 hour. After removing the sheath, a high-density tungsten-copper alloy was obtained, and its density (relative density) was 99.8% (density was 12.99 g / cm 3 ), impurity oxygen content is less than 40 ppm.

[0044] The cannula described in this step is a carbon steel cannula. The degassing process involves evacuating the cannula at room temperature using a vacuum pump, reducing the vacuum to 0.001 Pa, and then performing a sealing weld. The evacuated cannula is then placed in a hot isostatic pressing (HIP) machine for 3 hours at a temperature of 980°C and a pressure of 140 MPa. The thermoplastic processing involves hot extrusion, with a die temperature of 450°C, a heating temperature of 1000°C for 30 minutes, an extrusion rate of 8 mm / s, and an extrusion ratio of 7. The heat treatment temperature is 700°C.

[0045] Example 4

[0046] 1) CuO powder and WO 2.9The powders were weighed according to a mass ratio of 7:3 between metal Cu and W, and three-dimensionally mixed in a dual-power mixer for 4 h. The speed of the dual-power mixer was set at 700 r / min.

[0047] 2) The mixed powder obtained in step 1) was crushed and activated in a high-speed crusher for 3 minutes at a speed of 36,000 r / min;

[0048] 3) The powder obtained in step 2) is reduced in a hydrogen atmosphere to obtain nano-tungsten-copper composite powder; the reduction includes a two-stage hydrogen reduction, wherein the first stage is a hydrogen reduction temperature of 500 °C, a time of 3 h, and a hydrogen flow rate of 10 m 3 / h, powder laying height ≤ 2 / 3; the second stage hydrogen reduction temperature is 800 ℃, the time is 4 h, and the hydrogen flow rate is 10 m 3 / h, powder spreading height ≤2 / 3.

[0049] 4) The tungsten-copper composite powder obtained in step 3) was subjected to sheathing, degassing, and hot isostatic pressing, and then subjected to thermoplastic processing with the sheath. Then, the powder was kept at 600°C in a hydrogen atmosphere for 1.2 h. After removing the sheath, a high-density tungsten-copper alloy was obtained, and its density (relative density) was 99.8% (density was 10.55 g / cm 3 ), impurity oxygen content is less than 40 ppm.

[0050] The cannula described in this step is a carbon steel cannula. The degassing process involves evacuating the cannula at room temperature using a vacuum pump, reducing the vacuum to 0.006 Pa before sealing. The evacuated cannula is then placed in a hot isostatic pressing (HIP) machine for 3 hours at a temperature of 980°C and a pressure of 120 MPa. The thermoplastic processing involves hot extrusion, with a die temperature of 400°C, a cannula sample heated to 1000°C for 30 minutes, an extrusion rate of 8 mm / s, and an extrusion ratio of 7. The heat treatment temperature is 600°C.

[0051] Figure 2 is a BSEM image of the high-density tungsten-copper alloy prepared in this embodiment, with a copper mass content of 70% and a tungsten mass content of 30%. The dark area in Figure 2 is the copper phase, and the light area is the tungsten phase. The tungsten-copper alloy has a uniform and dense structure, and the tungsten particles are evenly distributed in the copper matrix. The tungsten particle size is less than 1 μm, and no voids are observed.

[0052] Example 5

[0053] 1) CuO powder and WO3 powder were weighed according to the mass ratio of metal Cu to W of 4:1, and the materials were mixed in a dual-power mixer for 5 h. The speed of the dual-power mixer was set to 500 r / min.

[0054] 2) The mixed powder obtained in step 1) was crushed and activated in a high-speed crusher for 2 minutes at a speed of 36,000 r / min;

[0055] 3) The powder obtained in step 2) is reduced in a hydrogen atmosphere to obtain nano-tungsten-copper composite powder; the reduction includes a two-stage hydrogen reduction, wherein the first stage is a hydrogen reduction temperature of 400 °C, a time of 3 h, and a hydrogen flow rate of 15 m 3 / h, powder laying height ≤ 2 / 3; the second stage hydrogen reduction temperature is 750 ℃, time is 3 h, hydrogen flow rate is 15 m 3 / h, powder spreading height ≤2 / 3.

[0056] 4) The tungsten-copper composite powder obtained in step 3) was subjected to sheathing, degassing, and hot isostatic pressing, and then subjected to thermoplastic processing with the sheath, and then kept at 600°C in an argon atmosphere for 1 hour. After removing the sheath, a high-density tungsten-copper alloy was obtained, and its density (relative density) was 99.9% (density was 9.94 g / cm 3 ), impurity oxygen content is less than 40 ppm.

[0057] The package described in this step is a carbon steel package. The specific degassing operation includes: using a vacuum pump to evacuate the package at room temperature and reduce the vacuum degree to 1×10 -3 After the evacuation, the can was placed in a hot isostatic pressing (HIP) machine for 4 hours at a temperature of 950°C and a pressure of 100 MPa. The hot plastic working process was rolling at 900°C, with three passes, a deformation of 28% per pass, and a total deformation of 84%.

[0058] Figure 3 is a BSEM image of the high-density tungsten-copper alloy prepared in this example, with a copper content of 80% by mass and a tungsten content of 20% by mass. The dark areas in Figure 3 represent the copper phase, while the light areas represent the tungsten phase. Tungsten particles are evenly distributed in the copper matrix, with a particle size of less than 1 μm and no voids observed.

[0059] The density (relative density), electrical conductivity and hardness of the high-density tungsten-copper alloys prepared in Examples 1 to 5 were tested. The results are shown in Table 1. As can be seen from Table 1, the high-density tungsten-copper alloys prepared in the present invention have an increased density, an increased electrical conductivity and a decreased hardness as the copper content increases. However, the measured values ​​are all higher than the national standard values, indicating that the high-density tungsten-copper alloys prepared in the present invention have excellent properties.

[0060] Table 1. Properties of tungsten-copper alloys prepared in Examples 1-5

[0061] Example Copper content Wt.% Density (%) Density (g / cm 3) Conductivity (IACS%) Hardness (HV) 11099.616.8739.832222599.714.6854.326534099.812.9963.422647099.810.5581.019458099.99.9489.5143

[0062] The above description is merely an embodiment of the present invention and does not constitute any limitation thereto. The present invention may also have other embodiments based on the above structures and functions, which are not listed here. Therefore, any simple modifications, equivalent variations, and modifications made to the above embodiments by any person skilled in the art, without departing from the scope of the present invention, based on the technical essence of the present invention, are still within the scope of the present invention. Enter the description of the best mode of implementation of the present invention here.

Claims

1. A preparation process of a high-density tungsten-copper alloy, characterized in that The following steps are involved: 1) Copper oxide powder and tungsten oxide powder of a certain ratio are mixed in a dual-power mixer to obtain a mixed powder; 2) crushing and activating the mixed powder obtained in step 1) in a high-speed crusher; 3) The powder obtained by the pulverization in step 2) is reduced in a hydrogen atmosphere to obtain a tungsten-copper composite powder; the reduction comprises a two-stage hydrogen reduction, wherein the first stage is a hydrogen reduction temperature of 400-550°C, a time of 1-3 h, and a hydrogen flow rate of 10 m 3 / h~20 m 3 / h, powder laying height ≤ 2 / 3; the second stage hydrogen reduction temperature is 750-800 ℃, the time is 2-6h, and the hydrogen flow rate is 15 m 3 / h~25 m 3 / h, powder spreading height ≤ 2 / 3; 4) The tungsten-copper composite powder obtained in step 3) is subjected to sheathing, degassing, and hot isostatic pressing, and then subjected to thermoplastic processing and annealing to obtain a high-density tungsten-copper alloy.

2. The process for preparing a high-density tungsten-copper alloy according to claim 1, wherein In step 1), the speed of the dual-power mixer is set to 500-800 r / min, and the mixing processing time is 4-10 hours.

3. The preparation process of the high-density tungsten-copper alloy according to claim 1, characterized in that The copper oxide in step 1) is selected from one or more of CuO and Cu2O, and the tungsten oxide is selected from yellow tungsten (WO3), blue tungsten (WO 2.9 ), purple tungsten (WO 2.72 ), one or more of tungsten (WO2).

4. The process for preparing a high-density tungsten-copper alloy according to claim 1, wherein The time of the crushing and activation treatment in step 2) is 0.5 to 4 minutes, and the speed of the high-speed crusher is set to 36,000 r / min.

5. The process for preparing the high-density tungsten-copper alloy according to claim 1, wherein The package mentioned in step 4) is a carbon steel package. The specific degassing operation includes: using a vacuum pump to evacuate the package at room temperature and reduce the vacuum degree to 1×10 -4 Pa~1×10 -2 After Pa, seal welding is performed.

6. The process for preparing the high-density tungsten-copper alloy according to claim 1 or 5, characterized in that The hot isostatic pressing treatment is performed at a temperature of 900-1070° C., a pressure of 95-160 MPa, and a time of 2.5-7 h.

7. The process for preparing a high-density tungsten-copper alloy according to claim 1 or 5, characterized in that The thermoplastic processing is one or a combination of rolling, extrusion or drawing; the total number of thermoplastic processing passes is 3 to 10 times, the deformation amount of each pass is 25 to 35%, and the total deformation amount is ≥80%.

8. The process for preparing a high-density tungsten-copper alloy according to claim 1 or 5, characterized in that The annealing treatment is carried out at 650-900°C in a hydrogen or argon atmosphere or in a vacuum, the annealing holding time is 0.5-2.0 h, and the vacuum degree is less than 10 -2 MPa.

9. The process for preparing a high-density tungsten-copper alloy according to claim 1, wherein The density of the prepared high-density tungsten-copper alloy reaches above 99.6%, and the impurity oxygen content is less than 40 ppm.

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