Device and method for preparing tungsten-copper particle gradient composite material through vibration induction

Abstract

The invention discloses a device and a method for preparing a tungsten-copper particle gradient composite material through vibration induction, and belongs to the crossing field of powder metallurgy and material forming machining. Aiming at the problems of powder agglomeration, non-uniform component distribution, difficulty in accurate control of a gradient structure and poor interface continuity in the preparation of a traditional tungsten-copper gradient composite material, a powder mixing-vibration mold filling-hot pressing sintering integrated process is adopted; tungsten copper powder distribution is optimized through a vibration external field capable of being precisely regulated and controlled. High-frequency small-amplitude vibration breaks particle aggregation so as to improve the filling uniformity, and low-frequency large-amplitude vibration guides tungsten copper two phases to form a preset gradient. The preparation device is used for completing powder homogenization and gradient regulation and control, and the tungsten-copper gradient composite material is prepared in cooperation with follow-up spark plasma sintering. According to the method, the vibration external field is only applied in the tungsten-copper particle mold filling stage, the process complexity does not need to be increased, the microstructure uniformity of the tungsten-copper composite material can be remarkably improved, and the gradient structure transition continuity is enhanced. The prepared composite material has the characteristics of high temperature resistance and low expansion of tungsten and high heat conductivity and high electric conductivity of copper, and can be widely applied to the high-end manufacturing fields of electronic power, aerospace, nuclear industry and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the cross field of powder metallurgy and material forming processing, and particularly relates to a device and method for preparing a vibration-induced tungsten-copper particle gradient composite material. BACKGROUND

[0002] Under the trend of vigorous development of modern high-end manufacturing industry, the demand for high-performance materials is growing exponentially. Tungsten-copper gradient composite material has unique comprehensive performance. Its performance gradient adapts to the properties of tungsten, such as high temperature resistance, low expansion, and the properties of copper, such as high thermal conductivity and high electrical conductivity. It can relieve interfacial thermal stress and avoid the peeling and cracking risks of traditional composite materials, and has stronger stability. It can also customize the gradient distribution as needed to meet the differentiated functional needs of different parts. It has good chemical stability and can maintain stable performance in extreme environments such as high temperature and high pressure. It has a wide range of applications in the construction of nuclear fusion devices in the nuclear industry, the manufacturing of high-power device heat dissipation / packaging components in the electronic power field, and the manufacturing of high-temperature stressed components in the aerospace field, and plays an irreplaceable role in many key fields.

[0003] However, the preparation of tungsten-copper composite material faces many difficult problems. Tungsten and copper have a huge difference in physical and chemical properties. They are almost insoluble, the density difference is about 3.5 times, and the melting point difference is more than 1000℃. This huge difference makes it difficult to prepare tungsten-copper gradient composite material with uniform interpenetrating network structure. The traditional methods for preparing tungsten-copper gradient composite material are mainly: powder metallurgy gradient sintering method; infiltration method; and laminated sintering method. Although the traditional methods can obtain tungsten-copper gradient composite structure under certain conditions, the material still has problems such as uneven distribution of powder agglomeration, difficulty in precise control of gradient structure, and poor density and interface continuity after sintering.

[0004] Therefore, it is very important to develop an innovative preparation technology to accurately control the distribution of tungsten and copper in tungsten-copper gradient composite material, improve the uniformity of microstructure and the comprehensive performance of the material, and not increase the complexity of the process, in order to promote the development of related industries and meet the needs of high-end manufacturing. SUMMARY

[0005] (I) Technical problems to be solved

[0006] The scheme mainly solves the problems of powder agglomeration, uneven distribution of components, difficulty in precise control of gradient structure, and poor interface continuity in the preparation of tungsten-copper gradient composite material.

[0007] To this end, the method of applying a vibrating external field is adopted to reduce particle friction, break agglomeration and optimize the arrangement of tungsten-copper powder in the filling stage, so that the tungsten-copper powder is more evenly distributed; adjusting the vibration parameters guides the gradient distribution of tungsten-copper two phases, and finally realizes the preparation of tungsten-copper gradient composite material. This technology reduces the copper enrichment rate, makes the microstructure of the material more uniform, better controls the gradient structure, better combines the interface, improves the comprehensive performance of the material, does not increase the process complexity, and meets the demand of high-performance tungsten-copper gradient composite material in many fields.

[0008] (II) Technical solution

[0009] The core of the application is to realize the gradient distribution of tungsten-copper powder and the efficient preparation of composite material through the integrated process of "mixing powder-vibration filling-thermal pressure sintering". The core innovation lies in introducing a precisely controllable vibrating external field, breaking the bottleneck of easy agglomeration of powder and uneven distribution of composition in the traditional mixing powder-sintering process, destroying the interlocking structure and agglomeration tendency between powder particles in the vibration process by selecting high frequency and small amplitude, avoiding the agglomeration of copper-rich particles to improve the filling uniformity, guiding the formation of a preset gradient of tungsten-copper two phases by selecting low frequency and large amplitude, and finally obtaining tungsten-copper gradient composite material with controllable performance gradient and good interface bonding.

[0010] In the application, the device for preparing tungsten-copper gradient composite material in the filling stage comprises a vibrating table, a fixed clamp, a vibration generating system, a graphite mold, the fixed straight frame is used to fix the graphite mold on the vibrating platform, the vibration generating system is located below the vibrating platform, and the vibration frequency and vibration amplitude can be adjusted in real time; the tungsten-copper powder is evenly distributed and filled into the graphite mold, the composition distribution of the tungsten-copper powder in the mold is changed by adjusting the frequency vibration all-in-one machine; the adjustable parameters include vibration amplitude, vibration frequency and vibration duration. The high-temperature resistance and thermal conductivity of the graphite mold can match the subsequent spark plasma sintering process, and deformation of the mold under high temperature and high pressure is avoided.

[0011] The application provides a preparation method of tungsten-copper gradient composite material, which adopts the preparation device and comprises the following steps.

[0012] S1, powder screening: the tungsten-copper powder of multiple sizes is screened through a vibrating screen to obtain the desired particle size.

[0013] S2, powder mixing: the required tungsten-copper powder is proportioned according to the mass ratio of 1:1, and then the proportioned powder is stirred for 8 hours to uniformly mix the tungsten-copper.

[0014] S3, mechanical vibration: the uniformly mixed tungsten-copper powder is placed in a graphite mold with a diameter of R mm, the graphite mold is fixed on the mechanical vibration platform, the required vibration amplitude, vibration frequency and vibration time are adjusted through the vibration generating device, and the tungsten-copper powder is subjected to vibration treatment.

[0015] The high frequency and small amplitude are selected, the mutual locking structure and the agglomeration tendency between the powder particles are destroyed in the vibration process, the agglomeration of the copper-rich particles can be effectively avoided, and the uniform stacking of the stacking structure can be realized.

[0016] The low frequency and large amplitude are selected, the vibration can effectively guide the gradient stacking of the tungsten-copper powder, the tungsten-copper gradient composite structure is formed, the gradient of the stacking structure can be realized, and the purpose of preparing the tungsten-copper gradient composite material is achieved.

[0017] S4, hot pressing sintering: finally, the graphite mold filled with the tungsten-copper powder after vibration is placed into a hot pressing sintering furnace for hot pressing sintering, a sintering process parameter is set for sintering, and finally, the furnace is cooled to room temperature.

[0018] Preferably, the preparation device has a maximum experimental load of 40 kg, an adjustable vibration frequency of 0-600 Hz (different density vibration cycles can be set as required), a no-load amplitude of 0-5 mm, a fixed vertical vibration direction, a rated vibration power of 1.5 kw, and an adaptive use environment temperature of 0-40 DEG C.

[0019] Preferably, high-purity graphite (purity > 99.8 %) is selected for processing, the mold has an inner diameter of 15 mm, a height of 40 mm, and an inner wall roughness of Ra≤0.8 um to avoid powder adhesion; the mold is provided with a gas permeable hole (hole diameter 1 mm, hole spacing 5 mm) to facilitate gas discharge during sintering.

[0020] Preferably, the sintering process parameter in step S4 is that, under a pressure of 50 MPa, heating is performed at a temperature increasing rate of 100 DEG C / min, when the temperature reaches 800 DEG C, the temperature is kept for 5 min, then heating is continued at a temperature increasing rate of 25 DEG C / min to a set sintering temperature of 1000 DEG C, the pressure is kept for 5 min after reaching the sintering temperature, and finally, the furnace is cooled to room temperature.

[0021] (Three) beneficial effects

[0022] The beneficial effects of the present application are:

[0023] The present application effectively solves the problems of powder agglomeration, uneven composition distribution, difficult precise control of gradient structure and insufficient interface bonding in the preparation of traditional tungsten-copper gradient composite materials. The powder arrangement is optimized by the controllable vibration external field, the copper network connectivity is improved, the copper enrichment rate is reduced, and the material microstructure is more uniform. Without increasing the process complexity, the interface bonding strength and the comprehensive performance of the material are significantly enhanced, and the excellent properties of tungsten and copper are taken into account. The preparation device is adapted to the subsequent sintering process, the operation is convenient, the prepared composite material can meet the needs of high-end fields such as electronic power, aerospace, nuclear industry, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A front view of a device for preparing the present application;

[0025] Figure 2 A schematic view of a cutting surface of a W-20Cu sintered sample;

[0026] Figure 3 A comparison of sintering density of tungsten-copper composite material with and without high-frequency small-amplitude vibration applied;

[0027] Figure 4 A comparison of microhardness of tungsten-copper composite material sintered sample with and without high-frequency small-amplitude vibration applied;

[0028] Figure 5 A microhardness and tungsten-copper content diagram of tungsten-copper composite material sintered sample with low-frequency large-amplitude vibration applied;

[0029] Figure 6 A vibration parameter reference diagram of an external vibration field;

[0030]

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 : 1: graphite mold; 2: fixed clamp; 3: filled tungsten-copper powder; 4: vibration table surface; 5: vibration generation system;

[0032] Figure 2 : (a): upper part of sintered sample cutting; (b): middle part of sintered sample cutting; (c): lower part of sintered sample cutting.

[0033] Figure 6 : comprehensive influence of vibration frequency and vibration amplitude on gradient degree. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application, and all other embodiments obtained by those skilled in the art without creative labor on the basis of the embodiments in the present application belong to the scope of protection of the present application.

[0035] Example 1

[0036] This example is carried out around tungsten-copper gradient composite material, tungsten-copper powder is subjected to vibration filling treatment, then discharge plasma sintering is adopted and specific parameters are set, finally performance test and microstructure observation are carried out, so as to study the influence of different factors on the performance and structure of the composite material. The specific content is as follows:

[0037] Mixing powder:

[0038] The tungsten powder with purity > 99.9% and electrolytic copper powder are selected as raw materials, the tungsten-copper powder of multiple sizes is screened by a vibrating screen to obtain the desired particle size, and the tungsten powder and copper powder are accurately weighed in a mass ratio of 4:1 (corresponding to the final composition of the composite material W-20Cu), and the weighing error is controlled within ±0.1%. The mixed powder after weighing is subjected to powder mixing treatment, and the powder mixing time lasts for 8 hours, providing a uniform initial material state for subsequent vibration gradient regulation.

[0039] Vibration filling:

[0040] The uniform tungsten-copper powder after powder mixing treatment is slowly loaded into a graphite mold, and the mold side wall is tapped during the powder loading process to avoid initial voids in the powder (two graphite molds are loaded with powder, one without vibration treatment for subsequent performance comparison); after the powder loading is completed, one mold is placed in the center of the clamp of the vibration table, and the clamp is fastened by bolts to ensure that the mold is tightly attached to the table.

[0041] Start the vibration equipment and adjust the parameters according to the following steps:

[0042] Adjust the parameters according to the preset gradient requirements: set the frequency to 170 Hz, the amplitude to 0.75 mm, and the vibration duration to 20 min. During the vibration process, the control system monitors the parameter stability in real time to ensure that there is no significant fluctuation.

[0043] Hot pressing sintering: finally, the tungsten-copper powder-filled graphite mold after vibration is placed in a hot pressing sintering furnace for hot pressing sintering. The sintering process parameters are set as follows: under a pressure of 50 MPa, heat at a rate of 100 ℃ / min, when the temperature reaches 800 ℃, keep for 5 min, then continue to heat at a rate of 25 ℃ / min to the set sintering temperature of 1000 ℃, keep the pressure for 5 min after reaching the sintering temperature, and finally cool to room temperature with the furnace.

[0044] Microstructure analysis of W-20Cu composite material prepared under the above vibration conditions:

[0045] The cutting method of the two samples prepared by adding different vibration methods during the filling process is consistent, as shown in Figure 2 .

[0046] The W-20Cu composite material with 170 Hz, 0.75 mm (high frequency and small amplitude) vibration has uniform microstructure distribution on the three cutting surfaces (a), (b), and (c), and the Cu matrix is uniformly distributed around the W particles, forming a continuous and dense Cu network around the W particles. There is no copper-rich region and a large amount of W agglomeration, and a dense microstructure can be formed. As shown in Figure 3As shown, the sintering density of W-20Cu composite without mechanical vibration during the filling process is 93.38%, and the sintering density of W-20Cu composite with 170Hz, 0.75mm (high frequency and small amplitude) vibration during the filling process is 98.58%, which is 5.2% higher than that without mechanical vibration. As shown in the following table, the microhardness of each layer is relatively uniform by testing the microhardness of each layer; the average hardness of layer a is 196.77HV, which is 24.13HV higher than that without vibration, the average hardness of layer b is 226.56HV, which is 43.31HV higher than that without vibration, and the average hardness of layer c is 211.54HV, which is 34.96HV higher than that without vibration. Adding 170Hz, 0.75mm (high frequency and small amplitude) vibration during the filling process helps to improve the microhardness of W-20Cu composite and does not destroy the uniformity of microhardness distribution. Therefore, adding uniform vibration during the filling process plays a good role in the uniformity of the structure, the microhardness of the composite material, and the distribution of the copper network, while improving the sintering density of W-20Cu. Figure 4 As shown, the microhardness of each layer is relatively uniform by testing the microhardness of each layer; the average hardness of layer a is 196.77HV, which is 24.13HV higher than that without vibration, the average hardness of layer b is 226.56HV, which is 43.31HV higher than that without vibration, and the average hardness of layer c is 211.54HV, which is 34.96HV higher than that without vibration. Adding 170Hz, 0.75mm (high frequency and small amplitude) vibration during the filling process helps to improve the microhardness of W-20Cu composite and does not destroy the uniformity of microhardness distribution. Therefore, adding uniform vibration during the filling process plays a good role in the uniformity of the structure, the microhardness of the composite material, and the distribution of the copper network, while improving the sintering density of W-20Cu.

[0047] Example 2

[0048] This example focuses on tungsten-copper gradient composite material. The tungsten-copper powder is subjected to vibration filling treatment, then subjected to spark plasma sintering with specific parameters, and finally subjected to performance testing and microstructure observation to study the influence of different factors on the performance and structure of the composite material. The specific content is as follows:

[0049] Mixing powder:

[0050] Pure tungsten powder with purity > 99.9% and electrolytic copper powder are selected as raw materials. The tungsten-copper powder of multiple sizes is sieved to the desired particle size by a vibrating screen. The tungsten powder and copper powder are accurately weighed in a ratio of 4:1 (corresponding to the final composite material composition of W-20Cu), with a weighing error controlled within ±0.1%. The mixed powder after weighing is subjected to mixing treatment for 8 hours, providing a uniform initial material state for subsequent vibration gradient control.

[0051] Vibration filling:

[0052] The uniform tungsten-copper powder after mixing treatment is slowly loaded into a graphite mold. During the powder loading process, the mold side wall is lightly tapped to avoid initial voids in the powder (two graphite molds are loaded with powder, one without vibration treatment for subsequent performance comparison). After the powder loading is completed, one mold is placed in the center of the clamp on the vibration table, and the mold is tightly attached to the table by tightening the clamping plate with bolts.

[0053] Start the vibration equipment and follow the steps below to adjust the parameters:

[0054] Adjust the parameters according to the preset gradient requirements: set the frequency to 12Hz, the amplitude to 2mm, and vibrate continuously for 20 minutes. During the vibration, the stability of the parameters is monitored in real time by the control system to ensure that there are no obvious fluctuations.

[0055] Hot pressing sintering: Finally, the vibrated graphite mold containing tungsten copper powder is placed in a hot pressing sintering furnace for hot pressing sintering. Spark plasma sintering technology is adopted, and the sintering process parameters are set as follows: under a pressure of 50 MPa, the temperature is increased at a rate of 100℃ / min. When the temperature reaches 800℃, it is held for 5 minutes. Then, the temperature is increased at a rate of 25℃ / min until the set sintering temperature of 1000℃ is reached. After reaching the sintering temperature, the pressure is maintained for 5 minutes. Finally, the furnace is cooled to room temperature.

[0056] Microstructure analysis of W-20Cu composite materials prepared under the above different vibration conditions:

[0057] The experiment used the same cutting method for two samples prepared with different vibration modes added during the filling process, such as... Figure 2 Cut as shown.

[0058] In the W-20Cu composite material with 12Hz, 2mm (low-frequency, large-amplitude) vibration, the copper matrix on the (a) cut surface is uniformly distributed among the tungsten particles, as shown in the image. Figure 5 As shown, the tungsten content in the microstructure of (a) is slightly higher than that in (b) and (c), while the copper content is lower at 11.2%. In (b), the tungsten and copper distribution is more uniform, with the tungsten and copper content falling between (a) and (c) at 21.1%. In (c), the copper content is higher than the tungsten content, with a copper content of 30.5%. Microhardness testing of each layer revealed a relatively uniform distribution. The average hardness of layer a was 255.45 HV, layer b was 205.13 HV, and layer c was 163.51 HV. The microhardness increased with increasing copper content in different cut surfaces. Therefore, comparing the microstructures of the three cut surfaces shows that gradient vibration can induce a gradient distribution in the microstructure of the W-20Cu composite material, with the bottom layer containing more copper than the upper layers.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the patent. Any simple modifications or equivalent transformations made by those skilled in the art based on the content of the present invention, or any direct or indirect applications in other related technical fields, are all included within the scope of patent protection of the present invention.

Claims

1. An apparatus and method for preparing vibration-induced tungsten-copper particle gradient composite material, characterized in that, The system includes a vibration table, a fixing fixture, a vibration generating system, and a graphite mold. The fixing fixture is used to fix the graphite mold on the vibration table. The vibration generating system is located below the vibration table and can adjust the vibration frequency and amplitude in real time. The preparation device applies a vibrational external field to induce a gradient transformation of tungsten and copper particles, achieving gradient filling. The powder after vibration filling is then hot-pressed and sintered to prepare a tungsten-copper gradient composite material.

2. The preparation apparatus according to claim 1, characterized in that... The test load of this vibration device is 40kg, the adjustable frequency range is 0-600Hz, the no-load amplitude range is 0-5mm, the vibration direction is vertical, the vibration power is 1.5kw, and the operating environment is 0-40℃.

3. The preparation apparatus as described in claim 1, characterized in that... The graphite mold is made of high-purity graphite (purity > 99.8%). The mold's inner diameter (R), height (H), and inner wall roughness (Ra ≤ 0.8 μm) are specified to prevent powder adhesion. A vent hole in the center of the mold facilitates gas escape during sintering. The graphite mold's high-temperature resistance and thermal conductivity are compatible with subsequent spark plasma sintering processes, preventing mold deformation under high temperature and pressure.

4. A method for preparing a tungsten-copper gradient composite material, characterized in that, The preparation apparatus according to any one of claims 1-3 comprises the following steps: S1. Powder sieving: Tungsten copper powder of various sizes is sieved through a vibrating screen to separate the desired particle size. S2. Powder mixing: Mix the required tungsten copper powder according to the preset ratio, and then mix the powder for 8 hours to ensure that the tungsten copper powder is evenly mixed. S3. Mechanical Vibration: The uniformly mixed tungsten copper powder is then placed into a graphite mold with a diameter of R mm. The graphite mold is fixed on a mechanical vibration platform, and the required vibration amplitude, vibration frequency, and vibration time are adjusted by a vibration generator to perform vibration treatment on the tungsten copper powder. S4. Hot pressing sintering: Finally, the vibrated graphite mold containing tungsten copper powder is placed into the hot pressing sintering furnace for hot pressing sintering. The spark plasma sintering technology is adopted, and the sintering process parameters are set for sintering. Finally, the furnace is cooled to room temperature.

5. The method for preparing tungsten-copper gradient composite materials by vibration filling as described in claim 4, characterized in that, When vibration is performed at high frequency and small amplitude (frequency 175-250Hz, amplitude 0.60-0.90mm), the interlocking structure and agglomeration tendency between powder particles can be disrupted, thus avoiding the agglomeration of copper-rich particles and improving filling uniformity.

6. The method for preparing tungsten-copper gradient composite materials by vibration filling as described in claim 4, characterized in that, When vibration is performed at low frequency and large amplitude (frequency 10-30Hz, amplitude 1.85-2.15mm), it can guide the tungsten and copper phases to form a gradient distribution, thereby achieving the gradient of tungsten and copper powder.

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