Long-life high-performance silver-based layered brush material and preparation method thereof

Abstract

The application discloses a long-life high-performance layered silver-based brush material and a preparation method thereof, and belongs to the technical field of silver-based composite material preparation. The preparation method of the layered silver-based brush material comprises the following steps: firstly, a surface modified multi-walled carbon nanotube paper is obtained by depositing a metal layer on the surface of the multi-walled carbon nanotube paper through vacuum evaporation plating; then, the surface modified multi-walled carbon nanotube paper and silver alloy powder are alternately charged in a graphite mold according to layers, and discharge plasma sintering is carried out to obtain the layered silver-based brush material. Through the surface metal layer modification of the multi-walled carbon nanotube paper and the adjustment of the stacking mode of the surface modified multi-walled carbon nanotube paper and the silver alloy powder, the interface bonding between the multi-walled carbon nanotube paper and the silver matrix is improved, and the mechanical and conductive properties of the high-carbon reinforced phase (weight ratio greater than or equal to 30 wt.%) silver-based brush material are improved. Meanwhile, the preparation process of the application is simplified, has no environmental pollution, and is easy to realize batch production.

Description

Technical Field

[0001] This invention belongs to the field of silver-based composite material preparation technology, specifically relating to a long-life, high-performance layered silver-based brush material and its preparation method. Background Technology

[0002] Silver-graphite composites are high-performance conductive materials made from silver and graphite through powder metallurgy. They combine the excellent electrical and thermal conductivity of silver with the wear resistance and lubricity of graphite, and are widely used in aerospace, new energy vehicles, electric transportation, industrial motors, and power equipment. However, performance optimization of silver-graphite composites faces challenges such as component segregation and low interfacial strength. In recent years, the application of novel preparation processes (such as wet mixing-decomposition technology) and additives (such as carbon nanotubes and molybdenum disulfide) has significantly improved their conductivity and wear resistance. However, for silver-graphite composites with high carbon content (>30 wt.%), the large density difference between graphite and silver matrix powders makes it difficult for traditional powder metallurgy processes to guarantee the uniformity of graphite dispersion and the interfacial bonding strength. Therefore, the development of high-carbon silver-carbon composites is an urgent problem to be solved in many key projects in my country.

[0003] Currently, carbon-based reinforced silver-based composite materials are typically prepared using powder metallurgy. For example, patent application CN201210519873.4 discloses a carbon fiber / copper composite material and its preparation method. This method uses a porous carbon preform obtained by pressing short carbon fibers as a preform, and infiltrates copper alloy into the pores of the preform. This allows the copper alloy to fully fill the pores within the carbon preform, ultimately forming a network-like continuously distributed copper alloy matrix. However, this type of preparation process is lengthy, costly, and prone to voids, making it difficult to guarantee the stability of the material's properties. Patent application CN202411627074.8 discloses a silver-graphite brush material and its preparation method, which addresses the problems of severe segregation and low interfacial strength in silver-graphite brushes by adding thermosetting resin. Meanwhile, patent application CN202311518985.2 discloses a brush material for smart home appliances and its preparation method, which also prepares the brush material by mixing and sintering a matrix graphite powder with a composite binder. However, achieving uniform graphite powder mixing through additives has several drawbacks. First, it prolongs the preparation process, and the volatilization and decomposition of the additives further compromise the uniformity of graphite dispersion. Second, additives cannot improve the interfacial bonding strength between graphite and the silver matrix.

[0004] Therefore, it is necessary to provide a novel method for preparing layered silver-based brush materials, which optimizes the spatial configuration distribution of the carbon-based reinforcing phase in the silver matrix and improves the interfacial bonding strength; at the same time, it can reduce the preparation process and improve the applicability of the preparation method. Summary of the Invention

[0005] To address or partially address the problems existing in related technologies, this invention provides a long-life, high-performance layered silver-based brush material and its preparation method.

[0006] This invention provides a method for preparing a long-life, high-performance layered silver-based brush material, comprising the following steps: (1) A surface-modified multi-walled carbon nanotube paper was obtained by depositing a metal layer on the surface of the paper by vacuum evaporation. (2) Surface-modified multi-walled carbon nanotube paper and silver alloy powder are placed in a graphite mold and loaded alternately in layers. Then, spark plasma sintering is performed to obtain layered silver-based brush material.

[0007] Preferably, the evaporation source material used in the vacuum evaporation deposition is one of high-purity copper particles, high-purity nickel particles, high-purity tin particles, and high-purity silver particles; the weight of the metal layer deposited on the surface of the multi-walled carbon nanotube paper is 5-15 wt. of the weight of the multi-walled carbon nanotube paper.

[0008] Preferably, the high-purity copper particles, high-purity nickel particles, high-purity tin particles, and high-purity silver particles have a purity of 99.99% and a particle size of 100-200μm; the multi-walled carbon nanotube paper has a thickness of 50-100μm.

[0009] Preferably, the vacuum degree of the vacuum evaporation deposition is ≤ 10. -3 Pa, resistance evaporation temperature is 500-1700℃, and plating time is 20-60min.

[0010] Preferably, the silver alloy powder is one of AgCu alloy, AgNi alloy, and AgCuNi alloy, wherein the Cu content in the AgCu alloy powder is 2.0 wt.%; the Ni content in the AgNi alloy powder is 2.0 wt.%; the Cu content in the AgCuNi alloy powder is 20 wt.% and the Ni content is 2 wt.%; and the particle size of the silver alloy powder is 20-50 μm.

[0011] Preferably, the vacuum degree of the discharge plasma sintering is <10. -1 Pa, sintering temperature is 600~800℃, holding time is 10~30min, heating rate is 100℃ / min, sintering pressure is 50MPa.

[0012] Preferably, in step (2), the total number of alternating layers is 7-15.

[0013] Preferably, in step (2), the mass of the surface-modified multi-walled carbon nanotube paper accounts for more than 30% of the mass of the layered silver-based brush material.

[0014] This invention also claims protection for the long-life, high-performance layered silver-based brush material prepared by the method described above.

[0015] The technical solution provided by this invention has the following beneficial effects: 1. This invention utilizes vacuum evaporation deposition technology to deposit a metal layer on the surface of multi-walled carbon nanotube paper to prepare surface-modified multi-walled carbon nanotube paper, thereby improving the interfacial bonding strength between the carbon-based reinforcing phase and the silver alloy matrix, which is beneficial to improving the service performance of layered silver-based brush materials.

[0016] 2. This invention uses multi-walled carbon nanotube paper as a carbon-based reinforcing phase. Compared with traditional graphite or carbon fiber, multi-walled carbon nanotube paper itself has excellent electrical conductivity and mechanical properties. Compared with the dispersed distribution of reinforcing phase in traditional powder metallurgy processes, the layered structure design can further increase the content of carbon-based reinforcing phase, thereby realizing the preparation of high-carbon-content silver-based brush materials.

[0017] 3. The preparation method of this invention is relatively simple, environmentally friendly and has relatively low energy consumption, making it suitable for industrial application. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the preparation process of long-life, high-performance layered silver-based brush materials. Detailed Implementation

[0019] Example 1 A method for preparing a long-life, high-performance layered silver-based brush material includes the following steps: (1) Place high-purity copper powder with a purity of 99.99% and a particle size of 100 μm into the resistance heating evaporation cavity, and evacuate the evaporation cavity to a vacuum degree ≤10. -3 Pa; then, the resistance heating evaporation chamber was heated to 1200℃; the multi-walled carbon nanotube paper with a thickness of 50 μm and a diameter of 10 cm was vacuum evaporated to deposit copper for 20 min, and the weight ratio of the copper layer deposited on the surface of the multi-walled carbon nanotube paper was 5 wt.%.

[0020] (2) The copper-plated multi-walled carbon nanotube paper and 20 μm AgCu2 powder obtained in step (1) were placed in a graphite mold and alternately loaded (AgCu2 powder was filled first, followed by copper-plated multi-walled carbon nanotube paper); then, spark plasma sintering was performed to prepare a layered silver-based brush material, wherein the copper-plated multi-walled carbon nanotube paper accounted for 30 wt.% of the weight of the layered silver-based brush material (for example, 10g sample requires 3 layers of copper-plated multi-walled carbon nanotube paper and 4 layers of silver alloy powder). During the spark plasma sintering process, the sintering temperature was 600℃, the holding time was 10min, the sintering pressure was 50MPa, and the vacuum degree was <10 -1 Pa, heating rate 100℃ / min.

[0021] The prepared layered silver-based brush material has a tensile strength of 89 MPa and a conductivity of 65% IACS.

[0022] Example 2 A method for preparing a long-life, high-performance layered silver-based brush material includes the following steps: (1) Place high-purity nickel powder with a purity of 99.99% and a particle size of 150 μm into a resistance heating evaporation cavity, and evacuate the evaporation cavity to a vacuum degree ≤ 10. -3 Pa; then, the resistance heating evaporation chamber was heated to 1500℃; the multi-walled carbon nanotube paper with a thickness of 70 μm and a diameter of 10 cm was vacuum evaporated to deposit nickel for 20 min, and the weight ratio of the metallic nickel layer deposited on the surface of the multi-walled carbon nanotube paper was 7 wt.%.

[0023] (2) The nickel-plated multi-walled carbon nanotube paper and 50 μm AgCu2 powder obtained in step (1) were placed in a graphite mold and alternately loaded (AgCu2 powder was filled first, followed by nickel-plated multi-walled carbon nanotube paper); then, spark plasma sintering was performed to prepare a layered silver-based brush material, wherein the nickel-plated multi-walled carbon nanotube paper accounted for 40 wt.% of the weight of the layered silver-based brush material (for example, 10g sample requires 4 layers of nickel-plated multi-walled carbon nanotube paper and 5 layers of silver alloy powder). During the spark plasma sintering process, the sintering temperature was 700℃, the holding time was 30min, the sintering pressure was 50MPa, and the vacuum degree was <10 -1 Pa, heating rate 100℃ / min.

[0024] The prepared layered silver-based brush material has a tensile strength of 71 MPa and a conductivity of 59% IACS.

[0025] Example 3 A method for preparing a long-life, high-performance layered silver-based brush material includes the following steps: (1) Place high-purity tin powder with a purity of 99.99% and a particle size of 200 μm into the resistance heating evaporation cavity, and evacuate the evaporation cavity to a vacuum degree ≤ 10. -3 Pa; then, the resistance heating evaporation chamber was heated to 500°C; further, the multi-walled carbon nanotube paper with a thickness of 100 μm and a diameter of 10 cm was vacuum evaporated and tin was deposited for 60 min, and the weight ratio of the tin layer deposited on the surface of the multi-walled carbon nanotube paper was 15 wt.%.

[0026] (2) The tin-plated multi-walled carbon nanotube paper and 30 μm AgNi2 powder obtained in step (1) were placed in a graphite mold and alternately loaded (AgNi2 powder was filled first, followed by tin-plated multi-walled carbon nanotube paper); then, spark plasma sintering was performed to prepare a layered silver-based brush material, wherein the tin-plated multi-walled carbon nanotube paper accounted for 40 wt.% of the total weight (for example, 10g of sample requires 4 layers of tin-plated multi-walled carbon nanotube paper and 5 layers of silver alloy powder). During the spark plasma sintering process, the sintering temperature was 800℃, the holding time was 30min, the sintering pressure was 50MPa, and the vacuum degree was <10 -1 Pa, heating rate 100℃ / min.

[0027] The prepared layered silver-based brush material has a tensile strength of 69 MPa and a conductivity of 51% IACS.

[0028] Example 4 A method for preparing a long-life, high-performance layered silver-based brush material includes the following steps: (1) Place high-purity silver powder with a purity of 99.99% and a particle size of 100 μm into a resistance heating evaporation cavity, and evacuate the evaporation cavity to a vacuum degree ≤ 10. -3 Pa; subsequently, the resistance-heated evaporation chamber was heated to 1200℃; further, a multi-walled carbon nanotube paper with a thickness of 50 μm and a diameter of 10 cm was vacuum evaporated to deposit silver for 30 min. The weight ratio of the silver layer deposited on the surface of the multi-walled carbon nanotube paper was 10 wt.%.

[0029] (2) The silver-plated multi-walled carbon nanotube paper and 20 μm AgCu20Ni2 powder obtained in step (1) were placed in a graphite mold and alternately loaded (AgCu20Ni2 powder was filled first, followed by silver-plated multi-walled carbon nanotube paper); then, spark plasma sintering was performed to prepare a layered silver-based brush material, wherein the silver-plated multi-walled carbon nanotube paper accounted for 50 wt.% of the weight of the layered silver-based brush material (for example, 10g sample requires 5 layers of silver-plated multi-walled carbon nanotube paper and 6 layers of silver alloy powder). During the spark plasma sintering process, the sintering temperature was 800℃, the holding time was 30min, the sintering pressure was 50MPa, and the vacuum degree was <10 -1 Pa, heating rate 100℃ / min.

[0030] The prepared layered silver-based brush material has a tensile strength of 65 MPa and a conductivity of 41% IACS.

[0031] Comparative Example 1 A method for preparing a silver-based brush material includes the following steps: (1) Place high-purity copper powder with a purity of 99.99% and a particle size of 100 μm into the resistance heating evaporation cavity, and evacuate the evaporation cavity to a vacuum degree ≤10. -3 Pa; then, the resistance heating evaporation chamber was heated to 1200℃; the multi-walled carbon nanotubes were vacuum evaporated to deposit copper for 20 min, and the weight ratio of the copper layer deposited on the surface of the multi-walled carbon nanotubes was 5 wt.%.

[0032] (2) After uniformly mixing the copper-coated multi-walled carbon nanotubes obtained in step (1) with AgCu2 powder of 20 μm particle size, the mixture was placed in a graphite mold; subsequently, spark plasma sintering was performed to prepare a silver-based brush material, wherein the copper-coated multi-walled carbon nanotubes accounted for 30 wt.% of the weight of the silver-based brush material. During the spark plasma sintering process, the sintering temperature was 600℃, the holding time was 10 min, the sintering pressure was 50 MPa, and the vacuum degree was <10 -1 Pa, heating rate 100℃ / min.

[0033] The prepared layered silver-based brush material has a tensile strength of 65 MPa and a conductivity of 55% IACS.

[0034] Comparative Example 2 A method for preparing a layered silver-based electric brush material includes the following steps: (1) Alternating loading of 50 μm thick, 10 cm diameter multi-walled carbon nanotube paper and 20 μm particle size AgCu2 powder (AgCu2 powder first, then multi-walled carbon nanotube paper) was carried out in a graphite mold; subsequently, spark plasma sintering was performed to prepare layered silver-based brush material, wherein the multi-walled carbon nanotube paper accounted for 30 wt.% of the weight of the layered silver-based brush material (for example, 10 g sample requires 3 layers of multi-walled carbon nanotube paper and 4 layers of silver alloy powder). During spark plasma sintering, the sintering temperature was 600℃, the holding time was 10 min, the sintering pressure was 50 MPa, and the vacuum degree was <10 -1 Pa, heating rate 100℃ / min.

[0035] The prepared layered silver-based brush material has a tensile strength of 61 MPa and a conductivity of 54% IACS.

[0036] The various 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 terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a long-life, high-performance layered silver-based brush material, characterized in that: The steps include the following: (1) A surface-modified multi-walled carbon nanotube paper was obtained by depositing a metal layer on the surface of the paper by vacuum evaporation. (2) Surface-modified multi-walled carbon nanotube paper and silver alloy powder are placed in a graphite mold and loaded alternately in layers. The total number of alternating layers is 7-15. Then, spark plasma sintering is performed to obtain layered silver-based brush material. The silver alloy powder is one of AgCu alloy, AgNi alloy, and AgCuNi alloy, wherein the Cu content in the AgCu alloy powder is 2.0 wt.%; the Ni content in the AgNi alloy powder is 2.0 wt.%; the Cu content in the AgCuNi alloy powder is 20 wt.% and the Ni content is 2 wt.%; and the particle size of the silver alloy powder is 20-50 μm. The mass of surface-modified multi-walled carbon nanotube paper accounts for more than 30% of the mass of layered silver-based brush material.

2. The method for preparing the long-life, high-performance layered silver-based brush material according to claim 1, characterized in that: The evaporation source material used in the vacuum evaporation deposition is one of high-purity copper particles, high-purity nickel particles, high-purity tin particles, and high-purity silver particles; the weight of the metal layer deposited on the surface of the multi-walled carbon nanotube paper is 5-15 wt. of the weight of the multi-walled carbon nanotube paper.

3. The method for preparing the long-life, high-performance layered silver-based brush material according to claim 2, characterized in that: The high-purity copper particles, high-purity nickel particles, high-purity tin particles, and high-purity silver particles have a purity of 99.99% and a particle size of 100-200μm; the multi-walled carbon nanotube paper has a thickness of 50-100μm.

4. The method for preparing the long-life, high-performance layered silver-based brush material according to claim 1, characterized in that: The vacuum degree of the vacuum evaporation deposition is ≤10. -3 Pa, resistance evaporation temperature is 500-1700℃, and plating time is 20-60min.

5. The method for preparing the long-life, high-performance layered silver-based brush material according to claim 1, characterized in that: The vacuum degree of the discharge plasma sintering is <10. -1 Pa, sintering temperature is 600~800℃, holding time is 10~30min, heating rate is 100℃ / min, sintering pressure is 50MPa.

6. The long-life, high-performance layered silver-based brush material prepared by the preparation method of any one of claims 1-5.

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