High-entropy quinary monoboride reinforced copper-based contact material and preparation method thereof

Abstract

The application relates to the technical field of electrical contact materials, in particular to a Cu-(MoWVCrNi)B high-entropy monoboride reinforced copper-based contact material and a preparation method thereof, which comprises the following steps: 1) mixing vanadium, chromium, molybdenum, tungsten, nickel and boron powder raw materials according to the stoichiometric ratio, and obtaining monoboride powder after ball milling; 2) mixing the monoboride powder and copper powder, and grinding copper-based contact powder by a planetary ball mill; and 3) preparing a copper-based contact material by spark plasma sintering the copper-based contact powder. The prepared copper-based contact material can realize bidirectional synergistic regulation and control of the electrical conductivity and the mechanical strength of the material by regulating and controlling the proportion of the material reinforcing phase, can be designed according to different actual use conditions, has a wide adaptation range, and is more diversified in actual application scenarios.

Description

Technical Field

[0001] This invention belongs to the field of electrical contact material technology, specifically relating to a Cu-(MoWVCrNi)B high-entropy monoboride reinforced copper-based contact material and its preparation method. Background Technology

[0002] Copper-based contacts are composite materials for electrical contact, made from copper (Cu) as the matrix and reinforced with one or more phases such as tungsten, chromium, graphite, and oxides, through processes such as powder metallurgy and melt infiltration. They are core components in electrical equipment such as switches, relays, and circuit breakers, responsible for the conduction and interruption of current. With the emergence of high-end equipment such as new energy charging piles, photovoltaic inverters, rail transit, and vacuum circuit breakers, the requirements for the current carrying capacity, thermal stability, fatigue life, and environmental adaptability of contacts have increased significantly.

[0003] The application scenarios for electrical equipment are becoming increasingly diversified, leading to differentiated market demands for the performance of copper-based contacts. Some power transmission, high-power distribution, and precision low-voltage devices have stringent requirements for contact conductivity, necessitating the use of high-conductivity copper-based contacts to ensure low energy consumption, high current carrying capacity, and low contact resistance. In harsh operating environments such as high-frequency switching, strong arc impact, and high-intensity friction and wear, the focus is more on contact wear resistance, mechanical hardness, and structural stability. For these conditions, copper-based contacts with relatively lower conductivity and superior overall mechanical and corrosion resistance are suitable. Existing conventional copper-based contact structures and formulations cannot simultaneously meet both types of differentiated application needs, limiting their applicability and failing to flexibly adapt to the actual requirements of different operating conditions.

[0004] Furthermore, traditional pure copper and ordinary copper-based contacts are prone to performance problems such as wear and deformation, material detachment, low mechanical strength, and incompatibility with application scenarios. Long-term service can lead to potential hazards such as switch jamming, poor contact, and insulation failure, shortening the lifespan of electrical equipment. Problems with existing traditional copper-based contacts include: 1) Performance contradiction: Existing conventional copper-based contact materials such as CuCr and CuW cannot simultaneously achieve both electrical and thermal conductivity and wear resistance. They are difficult to meet the comprehensive requirements of electrical contact conductivity and mechanical strength at the same time. Repeated opening and closing of contacts can easily lead to surface wear and material peeling, shortening the actual service life. 2) Manufacturing process issues: Conventional copper-based contact material manufacturing processes are prone to causing coarse copper matrix grains, agglomeration of reinforcing phase particles, and poor interfacial bonding strength. This makes it impossible to achieve uniform dispersion of the reinforcing phase in the copper matrix, resulting in technical shortcomings such as poor microstructure uniformity and high manufacturing costs in the contacts. 3) Insufficient adaptability to operating conditions: Traditional materials cannot be adapted to the contact requirements of high-voltage vacuum circuit breakers and contactors of different voltage levels through composition adjustment, thus limiting application scenarios.

[0005] As a core component for the conduction and interruption of current in switching electrical appliances, copper-based contacts are currently unable to meet the harsh service conditions and diverse application scenarios, and there is an urgent need to improve the performance of copper-based materials. Summary of the Invention

[0006] The purpose of this invention is to provide a Cu-(MoWVCrNi)B high-entropy monoboride reinforced copper-based contact material and its preparation method. Copper-based contact powder is prepared by ultra-low temperature short-time ball milling. By controlling the content and dispersion distribution of high-entropy monoborides, the conductivity and mechanical properties of the material are synergistically optimized, while ensuring uniform structure and good interfacial bonding. It can be adapted to different voltage levels and meet the practical application requirements of electrical contacts such as medium and high voltage vacuum circuit breakers and contactors.

[0007] To achieve the above objectives, the present invention is implemented according to the following technical solution: A high-entropy pentagonal single-boron reinforced copper-based contact material and its preparation method, comprising the following steps: 1) Preparation of high-entropy pentagonal single-boron compound (HEB) by high-energy ball milling: Vanadium (V), chromium (Cr), molybdenum (Mo), tungsten (W), nickel (Ni) metal powder and boron powder raw material are accurately weighed according to the stoichiometric ratio of (MoWVCrNi)B to obtain mixed raw material powder; the mixed raw material powder is ground by high-energy ball milling to prepare single-phase, impurity-free high-entropy HEB powder; 2) Preparation of Cu-HEB powder using a planetary ball mill: Weigh copper powder and mix it with the HEB powder prepared in step 1) to obtain Cu / HEB mixed powder, wherein the mass percentage of HEB is 15~45% and the remainder is copper powder; Grind the Cu / HEB mixed powder using a planetary ball mill at a ball milling temperature of -60℃ for 2-5 h. After ball milling, Cu-HEB powder with HEB uniformly dispersed in the Cu matrix is ​​obtained. 3) Preparation of bulk contact material by spark plasma sintering (SPS): The Cu-HEB powder prepared in step 2) is loaded into a graphite mold to ensure that the powder is packed evenly and densely; the mold is placed in a sintering furnace, the sintering program is started, and after sintering, the mold is cooled to room temperature with the furnace. After demolding, Cu-(MoWVCrNi)B high-entropy monoboride reinforced copper-based contact material is obtained.

[0008] Preferably, in step 1), the ball milling ratio is 10:1, the ball mill speed is 300~500 rpm, and the ball milling time is 20-40 h.

[0009] Preferably, in step 1), argon gas is introduced during the high-energy ball milling process to avoid oxidation of the metal powder and boron powder.

[0010] Preferably, in step 2), the ball milling ratio of the planetary ball mill is 5:1 and the ball mill speed is 150-300 rpm.

[0011] Preferably, in step 2), argon gas is introduced during the preparation of Cu-HEB using the planetary ball mill to avoid oxidation of the powder.

[0012] Preferably, in step 3), the sintering process parameters are: heating rate 50-100 ℃ / min, sintering temperature 850-1000 ℃, sintering pressure 30-80 MPa, and holding time 5-15 min.

[0013] Preferably, in step 3), a vacuum or argon gas is used as a protective atmosphere.

[0014] Beneficial effects This invention relates to a copper-based multiphase contact material reinforced with high-entropy monoborides. The material has a dense, bulk structure, consisting of a continuous copper matrix and dispersed high-entropy monoborides as reinforcing phases. Its specific structural features offer the following advantages: 1) Matrix phase: Pure copper is used as a continuous matrix to form the material's electrical and thermal conductivity network, ensuring that the material as a whole has good electrical and thermal conductivity and maintaining the structural continuity of the matrix.

[0015] 2) Reinforcing phase: (MoWVCrNi)B high-entropy monoboride (HEB) has a single-phase solid solution crystal structure with no impurity phases generated. The reinforcing phase exists in the form of particles with a size controlled between 1 and 10 μm. It is uniformly dispersed in the copper matrix without obvious segregation or agglomeration.

[0016] 3) Interface structure: The high-entropy monoboride particles and the copper matrix have a tight interface and high bonding strength, with no interface cracks, pores and other defects, which ensures the effective transfer of stress and energy between the two phases and improves the overall mechanical properties and service stability of the material.

[0017] 4) Overall phase structure: The material consists only of copper phase and high-entropy monoboride phase, without other impurity phases or intermediate reaction phases. The phase is pure and the microstructure is uniform.

[0018] 5) Preparation process: The ball milling process with an ultra-low temperature of -60℃ and a short time of 2-5 hours is adopted. This process can effectively inhibit the oxidation of copper powder, avoid damage to the crystal structure of the reinforcing phase, and quickly complete the mixing and refining of powder. It can also prevent the agglomeration of particles during cold welding, shorten the process cycle, and retain the original phase and physicochemical properties of the raw materials to the greatest extent, providing high-quality powder raw materials for the subsequent sintering preparation of high-performance copper-based composite contacts. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Figure 1 XRD patterns of copper-based contacts prepared in Examples 1-3 and Comparative Example 1.

[0021] Figure 2 SEM images of the copper-based contacts prepared in Examples 1-3 and Comparative Example 1.

[0022] Figure 3 EDS elemental distribution diagram of the copper-based contact prepared in Example 1.

[0023] Figure 4 Vickers hardness diagrams of copper-based contacts prepared in Examples 1-3 and Comparative Example 1.

[0024] Figure 5 Comparison of the conductivity of copper-based contacts prepared in Examples 1-3 and Comparative Example 1. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments. The illustrative embodiments and descriptions herein are used to explain the invention but are not intended to limit the invention. There are no particular limitations on the purity of any raw materials used in the present invention; conventional purity levels used in the art are acceptable. There are also no particular limitations on their source; they can be purchased commercially or prepared using conventional methods known to those skilled in the art. While there are no particular limitations on their purity, the present invention preferably uses conventional purity levels used in the art.

[0026] All processes in this invention are referred to by abbreviations that are common abbreviations in the field. Each abbreviation is clear and specific in its relevant application area, and those skilled in the art can understand its conventional process steps based on the abbreviation.

[0027] Example 1 A method for preparing a high-entropy pentagonal single-boron reinforced copper-based contact material includes the following steps: 1) Preparation of high-entropy pentagonal single-boron compound (HEB) by high-energy ball milling: Vanadium (V), chromium (Cr), molybdenum (Mo), tungsten (W), nickel (Ni) metal powder and boron powder raw material were accurately weighed according to the stoichiometric ratio of (MoWVCrNi)B; the above powders were ground by high-energy ball milling with a ball-to-material ratio of 10:1, a ball mill speed of 400 rpm, and a ball milling time of 30 h. Argon gas was used as a protective atmosphere throughout the ball milling process to prepare single-phase, impurity-free high-entropy single-boron compound powder; 2) Preparation of Cu-HEB powder using a planetary ball mill: Weigh copper powder and mix it with the HEB powder prepared in step 1) to obtain Cu / HEB mixed powder, wherein the mass percentage of HEB is 15% and the remainder is copper powder; Grind the Cu / HEB mixed powder using a planetary ball mill. Argon gas is introduced for protection during the ball milling process. The ball milling process parameters are: ball milling temperature -60℃, ball-to-material ratio 5:1, ball mill speed 250 rpm, and ball milling time 3 h. After ball milling, Cu-HEB powder with HEB uniformly dispersed in the Cu matrix is ​​obtained. 3) Preparation of bulk contact material by spark plasma sintering (SPS): The Cu-HEB powder prepared in 2) is loaded into a graphite mold, ensuring that the powder is packed evenly and densely; the mold is placed in an SPS sintering furnace, and the sintering program is started by evacuating or introducing argon gas as a protective gas. The sintering process parameters are: heating rate 50℃ / min, sintering temperature 1000℃, sintering pressure 55MPa, and holding time 10 min; after sintering, the furnace is cooled to room temperature, and after demolding, Cu-(MoWVCrNi)B high-entropy monoboride reinforced copper-based contact material is obtained.

[0028] 4) X-ray diffraction was used to detect the crystal form of the prepared bulk copper-based contact material; the conductivity of the copper-based contact material was detected; the Vickers hardness of the copper-based contact material was detected; SEM images of the copper-based contact material were taken and EDS elemental analysis was performed.

[0029] Example 2 The difference from Example 1 is that the mass percentage of HEB powder in step 2) is 30%, while the rest of the steps are the same as in Example 1.

[0030] Example 3 The difference from Example 1 is that the mass percentage of HEB powder in step 2) is 45%, while the rest of the steps are the same as in Example 1.

[0031] Comparative Example 1 The difference from Example 1 is that the mass percentage of HEB powder in step 2) is 0%, while the rest of the steps are the same as in Example 1.

[0032] Results Analysis (a) Characterizing the crystal phase of the prepared copper-based contact material. For example... Figure 1 The figure shows the XRD patterns of copper-based contact materials with different HEB contents. As can be seen from the figure, the preparation method adopted in this invention can prepare pentagonal homogeneous single-phase boride (MoWVCrNi)B, and the pentagonal homogeneous single-phase structure of HEB is not destroyed when it is dissolved in copper powder.

[0033] (ii) The microstructure, elemental composition, and distribution of the prepared copper-based contact material were characterized. For example... Figure 2 The figure shows SEM images of copper-based contact materials with different HEB contents. As can be seen from the figure, the copper-based contact material prepared by the present invention has good microstructure uniformity, no obvious agglomeration or segregation of HEB reinforcing phase, tight bonding between particles and copper matrix interface, low porosity and good density; the overall microstructure of the material is regular, without obvious cracks and defects, which can effectively ensure the mechanical load-bearing capacity and wear resistance service life of the material. Figure 3 The results, obtained using EDS elemental analysis, further demonstrate that the ratio of copper matrix elements to the characteristic elements contained in HEB is highly consistent with the design composition. The elements are well dispersed and distributed, with no elemental segregation, missing elements, or other impurity enrichment. From the perspective of elemental composition, it is confirmed that the raw materials are fully mixed and the reaction is stable, ensuring that the material's conductivity and strengthening properties meet the standards.

[0034] (iii) The mechanical hardness of the prepared copper-based contact material was characterized. For example... Figure 4 As shown, the Vickers hardness of copper-based contacts with different HEB contents is represented. The horizontal axis, indentation load, refers to the magnitude of the indentation load applied to the sample surface by the diamond indenter during the test. The figure shows that when Vickers hardness tests are conducted on copper-based contact materials with different indentation loads, the results indicate that the Vickers hardness of the sample material with added reinforcing phase tends to stabilize with increasing indentation load, indicating that the overall internal and external mechanical properties of the material are small and the overall structure is highly uniform. Furthermore, as the proportion of HEB reinforcing phase increases, the Vickers hardness of the sample increases synchronously. The sample with the highest reinforcing phase content maintains the highest hardness level throughout the entire indentation load range. These results confirm that the introduction of the reinforcing phase can significantly improve the mechanical hardness of the copper-based contact material while maintaining structural uniformity. Moreover, the high proportion of reinforcing phase can continuously exert a strengthening effect under different test load conditions, resulting in a prominent overall hardening effect of the material.

[0035] (iv) The electrical conductivity of the prepared copper-based contact material was characterized. For example... Figure 5 As shown in the figure, the conductivity of copper-based contacts with different HEB contents is as follows: The conductivity decreases significantly with increasing reinforcing phase ratio. However, this property can be used to flexibly control the conductivity of copper-based contact materials by precisely adjusting the reinforcing phase addition ratio. Based on this, suitable components can be designed to meet the electrical performance requirements of different operating conditions and actual scenarios, matching high and low conductivity indicators as needed. This allows for meeting the high conductivity requirements of high-current switching scenarios as well as adapting to special service environments with low current and requiring moderate adjustment of conductivity parameters, thus broadening the practical application range of the material.

[0036] The embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The technical solutions of the present invention are not limited to the specific embodiments described above; all technical modifications made according to the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-entropy pentagonal single-boron reinforced copper-based contact material, characterized in that, Includes the following steps: 1) Preparation of pentagonal boron compounds: Mix and grind six elemental powders of vanadium, chromium, molybdenum, tungsten, nickel and boron in a molar ratio of 1:1:1:1:1:1 to obtain boron compound powder; 2) Preparation of copper-monoboride powder: Mix copper powder with monoboride powder from step 1) to obtain mixed powder, thus preparing copper-monoboride powder; 3) Copper-monoboride powder was sintered using a spark plasma sintering process to obtain copper-based contact materials.

2. The method for preparing a high-entropy pentagonal single-boron reinforced copper-based contact material according to claim 1, characterized in that, In step 2), ball milling is used for mixing. The ball milling temperature is -60℃ and the ball milling time is 2-5 h. Argon gas is introduced as a protective gas during the ball milling process.

3. The method for preparing a high-entropy pentagonal single-boron reinforced copper-based contact material according to claim 1, characterized in that, In step 2), a planetary ball mill is used for ball milling, with a ball milling ratio of 5:1 and a rotation speed of 150-300 rpm.

4. The method for preparing a high-entropy pentagonal single-boron reinforced copper-based contact material according to claim 1, characterized in that, In step 2), the mass percentage of the monoboride powder is 15-45%, with the remainder being copper powder.

5. The method for preparing a high-entropy pentagonal single-boron reinforced copper-based contact material according to claim 1, characterized in that, In step 1), the grinding method is high-energy ball milling. The process parameters of the high-energy ball milling are: ball milling ratio of 10:1, ball mill speed of 300-500 rpm, and ball milling time of 20-40 h. Argon gas is introduced into the high-energy ball mill as a protective gas during the grinding process.

6. The method for preparing a high-entropy pentagonal single-boron reinforced copper-based contact material according to claim 1, characterized in that, In step 3), the discharge plasma sintering process is as follows: the copper-monoboride powder prepared in step 2) is loaded into a graphite mold to ensure that the powder is filled evenly and densely. The mold is placed in a discharge plasma sintering furnace, the sintering program is started, and after sintering, the furnace is cooled to room temperature. After demolding, Cu-(MoWVCrNi)B high-entropy monoboride reinforced copper-based contact material is obtained.

7. The method for preparing a high-entropy pentagonal single-boron reinforced copper-based contact material according to claim 6, characterized in that, The process parameters for the discharge plasma sintering process are as follows: heating rate of 50-100 ℃ / min, sintering temperature of 850-1000 ℃, sintering pressure of 30-80 MPa, and holding time of 5-15 min. The sintering process uses vacuum or argon gas as a protective atmosphere.

8. A high-entropy pentagonal single-boron reinforced copper-based contact material prepared by any of the preparation methods described in claims 1 to 7.

Images