A motor carbon brush composite material and preparation method thereof

Abstract

The invention discloses a motor carbon brush composite material and a preparation method thereof. The invention first performs surface oxidation treatment on hexagonal boron nitride, introduces oxygen-containing defects on the surface of the boron nitride, and then pre-treats the hexagonal boron nitride and reacts with nano silicon dioxide during high-temperature sintering to obtain a boron nitride / silicon dioxide ceramic material. Compared with a single boron nitride material, the boron nitride / silicon dioxide ceramic material has higher hardness and strength, increases the mechanical strength and wear resistance of the carbon brush material, and thus improves the service life of the carbon brush material. Nano zero-valent copper and zero-valent iron are loaded on the surface and interlayer of the boron nitride / silicon dioxide / molybdenum disulfide composite material. Nano zero-valent copper is a good conductive material, and nano zero-valent iron also has a certain conductivity. The combination of the two can improve the comprehensive conductive performance of the carbon brush material, especially in high-frequency motor applications, the improvement effect is more significant.

Description

Technical Field

[0001] The invention relates to the technical field of carbon brush material preparation, and in particular to a motor carbon brush composite material and a preparation method thereof. Background Art

[0002] Carbon brushes are important components of motors. Their function is to conduct current between the fixed parts of the motor and the rotating parts of the commutator or collector ring. Their performance directly affects the normal operation of the motor. Compared with ordinary mechanical friction and wear, carbon brush materials have multiple mechanical friction and wear mechanisms during motor operation, accompanied by arc erosion and electrical wear. The wear conditions of automobile starter motors are complex, requiring carbon brush materials to have large current carrying capacity, excellent commutation performance and sliding contact performance. Conventional carbon brushes will experience increased wear and severe arc erosion under high-density current conditions, which cannot meet the use requirements.

[0003] At present, most carbon brushes are generally made of graphite, metal materials, resin adhesives and other additives, and are made by sintering. Although graphite has good wear resistance, it is easy to wear in actual use, which is difficult to overcome. If the wear resistance of the carbon brush is not improved, it will seriously affect the performance and service life of the entire equipment. At present, the comprehensive performance of carbon brush materials is improved mainly through three methods: matrix alloying, surface treatment of graphite and adding appropriate additives. For example, Chinese patent document 201710153401.4 discloses a lanthanum oxide doped copper-based graphite motor carbon brush and its preparation method. The carbon brush material uses natural flake graphite, porous carbon powder, copper powder and bronze powder as the base material, and adds lanthanum oxide for modification to improve the sintering performance. However, the hardness and bending strength of the carbon brush material prepared by it are still insufficient. In addition, although the deformation degree of the copper matrix during wear can be improved by adding SiC particles, SiC, as a ceramic phase particle, will have an adverse effect on the electrical conductivity of the composite material. In order to obtain a low-cost and long-life carbon brush material for motors with good electrical conductivity and wear resistance, it is necessary to comprehensively consider the reasonable matching between material manufacturing cost, processability, thermal conductivity, electrical conductivity, mechanical properties and friction and wear properties, and reasonably design the material composition. Summary of the invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide a motor carbon brush composite material and a preparation method thereof, wherein the prepared motor carbon brush composite material has excellent wear resistance and good electrical conductivity.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A motor carbon brush composite material comprises the following raw materials in parts by weight: 40-60 parts of flake graphite powder, 10-20 parts of expanded graphite, 15-25 parts of copper powder, 5-10 parts of asphalt powder, 4-8 parts of boron nitride composite material, 1-3 parts of carboxymethyl cellulose and 2-4 parts of sulfur powder.

[0007] Preferably, in some embodiments of the present invention, the flake graphite powder can be selected from 40 parts, 42 parts, 45 parts, 48 ​​parts, 50 parts, 52 parts, 54 parts, 55 parts, 56 parts, 58 parts, and 60 parts, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0008] In the present invention, flake graphite has excellent lubricating properties and can form a thin film between the carbon brush and the commutator to reduce friction and wear, thereby reducing heat generation and extending the service life of the carbon brush. At the same time, flake graphite powder can improve the conductivity of the carbon brush, ensure smooth conduction of current, and improve the overall motor efficiency.

[0009] Preferably, in some embodiments of the present invention, the expanded graphite can be selected to be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, and 20 parts, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0010] In the present invention, the layered structure of expanded graphite can form an effective lubricating film between the carbon brush and the commutator, significantly reducing the friction coefficient and wear, thereby increasing the service life of the carbon brush; at the same time, the high thermal conductivity of the expanded graphite helps to improve the heat dissipation capacity of the carbon brush, reduce the temperature, and prevent material deterioration or performance degradation due to temperature increase.

[0011] Preferably, in some embodiments of the present invention, the copper powder can be selected to be 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, and 25 parts, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0012] In the present invention, copper powder has excellent electrical conductivity and can significantly improve the electrical conductivity of the carbon brush; copper has good thermal conductivity, and the addition of copper powder helps to enhance the heat dissipation performance of the carbon brush, reduce the operating temperature, and prevent performance degradation due to overheating.

[0013] Preferably, in some embodiments of the present invention, the asphalt powder can be selected to be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] Preferably, in some embodiments of the present invention, the boron nitride composite material can be selected to be 4 parts, 5 parts, 6 parts, 7 parts, or 8 parts, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0015] More preferably, the preparation method of the boron nitride composite material is as follows:

[0016] S1, adding hexagonal boron nitride to a mixed solution of H2O2 and H2SO4, stirring and impregnating, filtering, washing and drying after impregnation to obtain pretreated hexagonal boron nitride;

[0017] S2, mixing the pretreated hexagonal boron nitride and nano-silicon dioxide uniformly, and then wet ball milling, drying the ball-milled slurry, crushing and screening, granulating, and then sintering at high temperature under a nitrogen atmosphere, and then cooling to room temperature, crushing and screening, to obtain a boron nitride / silicon dioxide ceramic material;

[0018] S3, dispersing the boron nitride / silicon dioxide ceramic material in deionized water, then adding ammonium molybdate, thiourea and surfactant hexadecyltrimethylammonium bromide thereto, stirring evenly, transferring to a reactor for hydrothermal reaction, and after the reaction is completed, performing solid-liquid separation, washing and drying to obtain a boron nitride / silicon dioxide / molybdenum disulfide composite material;

[0019] S4. Disperse the boron nitride / silicon dioxide / molybdenum disulfide composite material in deionized water, introduce nitrogen to expel the air, add ferrous sulfate and copper sulfate, stir evenly, heat in a water bath to 70-85°C, then add reducing agent sodium borohydride, stir to react, and after the reaction is completed, wash, filter, dry, grind and sieve to obtain the boron nitride composite material.

[0020] Preferably, in step S1, the stirring and dipping temperature is 25-40° C., and the stirring and dipping time is 1-5 h.

[0021] Preferably, in step S2, the mass ratio of pretreated hexagonal boron nitride to nano-silicon dioxide is 10-15:4-8.

[0022] Preferably, in step S2, the high temperature sintering temperature is 1500-1600° C., and the high temperature sintering time is 1-4 hours.

[0023] Preferably, in step S3, the mass ratio of boron nitride / silicon dioxide ceramic material, ammonium molybdate, thiourea and hexadecyltrimethylammonium bromide is 10-15:3-6:5-8:0.8-1.2.

[0024] Preferably, in step S3, the temperature of the hydrothermal reaction is 180-210° C., and the time of the hydrothermal reaction is 12-24 h.

[0025] Preferably, in step S4, the mass ratio of the boron nitride / silicon dioxide / molybdenum disulfide composite material, ferrous sulfate, copper sulfate and sodium borohydride is 10-15:6-10:8-12:15-25.

[0026] Preferably, in step S4, the stirring reaction temperature is 70-85° C., and the stirring reaction time is 2-5 h.

[0027] Preferably, in some embodiments of the present invention, the carboxymethyl cellulose may be selected to be 1 part, 1.5 parts, 2 parts, 2.5 parts, or 3 parts, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] In the present invention, carboxymethyl cellulose is mainly used as a binder to enhance the structural integrity of the carbon brush material and improve the bonding force between the components.

[0029] Preferably, in some embodiments of the present invention, the sulfur powder can be selected to be 2 parts, 2.5 parts, 3 parts, 3.5 parts, or 4 parts, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] The present invention also provides a method for preparing the above-mentioned motor carbon brush composite material, comprising the following steps: putting each raw material into a mixer according to weight and mixing them evenly, stirring at 60-80°C for 1-2h, and then crushing, the obtained powder is sieved through a 200-mesh sieve to obtain micropowder, pressing the obtained micropowder in a mold, and obtaining a blank after demolding, and then sintering at 800-850°C for 30-60min, and pressing and molding at a pressure of 160-180MPa to obtain the motor carbon brush composite material.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention first performs surface oxidation treatment on hexagonal boron nitride to introduce oxygen-containing defects on the surface of the boron nitride, and then pre-treats the hexagonal boron nitride and reacts with nano-silicon dioxide during high-temperature sintering to obtain a boron nitride / silicon dioxide ceramic material. Compared with a single boron nitride material, the boron nitride / silicon dioxide ceramic material has higher hardness and strength, increases the mechanical strength and wear resistance of the carbon brush material, and thus improves the service life of the carbon brush material.

[0033] (2) The present invention generates molybdenum disulfide in situ on the surface of the boron nitride / silicon dioxide ceramic material to obtain a boron nitride / silicon dioxide / molybdenum disulfide composite material. The unique "sandwich" structure of molybdenum disulfide makes it easy to peel off the layers, and it has good lubrication properties. When it is loaded on the surface of the boron nitride / silicon dioxide ceramic material, the lubrication properties of molybdenum disulfide and the hard grinding properties of the ceramic material are combined, further improving the wear resistance of the carbon brush material.

[0034] (3) The present invention loads nano zero-valent copper and zero-valent iron on the surface and interlayer of the boron nitride / silicon dioxide / molybdenum disulfide composite material. Nano zero-valent copper is a good conductive material, and nano zero-valent iron also has a certain conductivity. The combination of the two can improve the comprehensive conductivity of the carbon brush material, especially in high-frequency motor applications. The improvement effect is more significant; at the same time, the characteristics of nano zero-valent copper and zero-valent iron can complement each other. Nano zero-valent copper can reduce friction and improve lubricity, while zero-valent iron can increase hardness and wear resistance. Nano zero-valent copper and zero-valent iron can form a moderately thick, uniform and stable friction film on the friction surface during the electric friction process, which effectively ensures the stability of the carbon brush during operation and greatly reduces the wear rate of the carbon brush material. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0036] It should be noted that, unless otherwise specified, the chemical reagents involved in the present invention were purchased through commercial channels.

[0037] The specification of the flake graphite powder used in the present invention is 325 mesh;

[0038] The specification of expanded graphite is 200 mesh;

[0039] The specification of asphalt powder is 200-250 mesh;

[0040] The specification of copper powder is 325 mesh and the purity is 99.5%;

[0041] The specification of hexagonal boron nitride is 2000 mesh;

[0042] The specification of nano-silicon dioxide is 40-60nm;

[0043] Carboxymethyl cellulose was purchased from Shandong Zhengyang New Material Technology Co., Ltd.;

[0044] The specification of sulfur powder is 400 mesh;

[0045] The mass fraction of H2O2 is 30%, and the mass fraction of H2SO4 is 68%.

[0046] Example 1

[0047] A method for preparing a motor carbon brush composite material comprises the following steps:

[0048] 40 parts of flake graphite powder, 15 parts of expanded graphite, 25 parts of copper powder, 8 parts of asphalt powder, 5 parts of boron nitride composite material, 1 part of carboxymethyl cellulose and 2 parts of sulfur powder were put into a mixer and mixed evenly, stirred at 60°C for 2h, and then crushed, the obtained powder was sieved through a 200-mesh sieve to obtain micropowder, the obtained micropowder was pressed in a mold, and a blank was obtained after demolding, and then sintered at 800°C for 45min, and pressed under a pressure of 160MPa to obtain a motor carbon brush composite material;

[0049] Wherein, the preparation method of the boron nitride composite material is as follows:

[0050] S1. Add 10 g of hexagonal boron nitride to a mixed solution of 25 mL of H2O2 and 75 mL of H2SO4, and stir and immerse for 3 h at 25 °C. After the immersion is completed, filter, wash, and dry to obtain pretreated hexagonal boron nitride;

[0051] S2, 10g pretreated hexagonal boron nitride and 4g nano silicon dioxide were mixed evenly, and then wet ball milling was performed, the ball-milled slurry was dried, crushed through a 400-mesh sieve, granulated, and then high-temperature sintered in a nitrogen atmosphere at a temperature of 1500°C for 2h, and then cooled to room temperature, crushed through a 400-mesh sieve, to obtain a boron nitride / silicon dioxide ceramic material;

[0052] S3, 10g of boron nitride / silicon dioxide ceramic material is dispersed in 150mL of deionized water, and then 3g of ammonium molybdate, 5g of thiourea and 0.8g of surfactant hexadecyltrimethylammonium bromide are added thereto, stirred evenly, and transferred to a reactor for hydrothermal reaction, the temperature of the hydrothermal reaction is 210°C, and the time of the hydrothermal reaction is 18h. After the reaction is completed, solid-liquid separation, washing and drying are performed to obtain a boron nitride / silicon dioxide / molybdenum disulfide composite material;

[0053] S4. Disperse 10 g of boron nitride / silicon dioxide / molybdenum disulfide composite material in 150 mL of deionized water, introduce nitrogen to expel the air, add 6 g of ferrous sulfate and 8 g of copper sulfate, stir evenly, heat to 80°C in a water bath, then add 15 g of reducing agent sodium borohydride, continue stirring and reacting at 80°C for 3 hours. After the reaction is completed, wash, filter, dry, and grind through a 400-mesh sieve to obtain a boron nitride composite material.

[0054] Example 2

[0055] A method for preparing a motor carbon brush composite material comprises the following steps:

[0056] 50 parts of flake graphite powder, 10 parts of expanded graphite, 15 parts of copper powder, 10 parts of asphalt powder, 6 parts of boron nitride composite material, 2 parts of carboxymethyl cellulose and 3 parts of sulfur powder were put into a mixer and mixed evenly, stirred at 80°C for 1 hour, and then crushed, the obtained powder was sieved through a 200-mesh sieve to obtain micropowder, the obtained micropowder was pressed in a mold, and a blank was obtained after demolding, and then sintered at 800°C for 45 minutes, and pressed under a pressure of 180MPa to obtain a motor carbon brush composite material;

[0057] Wherein, the preparation method of the boron nitride composite material is as follows:

[0058] S1. Add 10 g of hexagonal boron nitride to a mixed solution of 25 mL of H2O2 and 75 mL of H2SO4, and stir and immerse for 5 h at 25 °C. After the immersion is completed, filter, wash, and dry to obtain pretreated hexagonal boron nitride;

[0059] S2, 12g pretreated hexagonal boron nitride and 6g nano silicon dioxide were mixed evenly, and then wet ball milling was performed, the ball-milled slurry was dried, crushed through a 400-mesh sieve, granulated, and then high-temperature sintered in a nitrogen atmosphere at a temperature of 1500°C for 2h, and then cooled to room temperature, crushed through a 400-mesh sieve, to obtain a boron nitride / silicon dioxide ceramic material;

[0060] S3, 12g of boron nitride / silicon dioxide ceramic material is dispersed in 150mL of deionized water, and then 4g of ammonium molybdate, 6g of thiourea and 1g of surfactant hexadecyltrimethylammonium bromide are added thereto, stirred evenly, and transferred to a reactor for hydrothermal reaction at a temperature of 210°C for 24h. After the reaction is completed, solid-liquid separation, washing and drying are performed to obtain a boron nitride / silicon dioxide / molybdenum disulfide composite material;

[0061] S4. Disperse 12g of boron nitride / silicon dioxide / molybdenum disulfide composite material in 150mL of deionized water, introduce nitrogen to expel the air, add 8g of ferrous sulfate and 10g of copper sulfate, stir evenly, heat to 80°C in a water bath, add 20g of reducing agent sodium borohydride, continue stirring and reacting at 80°C for 3h, after the reaction is completed, wash, filter, dry, and grind through a 400-mesh sieve to obtain a boron nitride composite material.

[0062] Example 3

[0063] A method for preparing a motor carbon brush composite material comprises the following steps:

[0064] 45 parts of flake graphite powder, 15 parts of expanded graphite, 20 parts of copper powder, 6 parts of asphalt powder, 4 parts of boron nitride composite material, 2 parts of carboxymethyl cellulose and 2 parts of sulfur powder were put into a mixer and mixed evenly, stirred at 60°C for 2h, and then crushed, the obtained powder was sieved through a 200-mesh sieve to obtain micropowder, the obtained micropowder was pressed in a mold, and a blank was obtained after demolding, and then sintered at 820°C for 40min, and pressed under a pressure of 170MPa to obtain a motor carbon brush composite material;

[0065] Wherein, the preparation method of the boron nitride composite material is as follows:

[0066] S1. Add 10 g of hexagonal boron nitride to a mixed solution of 25 mL of H2O2 and 75 mL of H2SO4, and stir and immerse at 40°C for 3 h. After the immersion is completed, filter, wash, and dry to obtain pretreated hexagonal boron nitride.

[0067] S2, 15g pretreated hexagonal boron nitride and 8g nano silicon dioxide were mixed evenly, and then wet ball milling was performed, the ball-milled slurry was dried, crushed through a 400-mesh sieve, granulated, and then high-temperature sintered in a nitrogen atmosphere at a temperature of 1600°C for 2h, and then cooled to room temperature, crushed through a 400-mesh sieve, to obtain a boron nitride / silicon dioxide ceramic material;

[0068] S3, 15g of boron nitride / silicon dioxide ceramic material is dispersed in 150mL of deionized water, and then 6g of ammonium molybdate, 8g of thiourea and 1.2g of surfactant hexadecyltrimethylammonium bromide are added thereto, stirred evenly, and transferred to a reactor for hydrothermal reaction at a temperature of 180°C for 24h. After the reaction is completed, solid-liquid separation, washing and drying are performed to obtain a boron nitride / silicon dioxide / molybdenum disulfide composite material;

[0069] S4. Disperse 15g of boron nitride / silicon dioxide / molybdenum disulfide composite material in 150mL of deionized water, introduce nitrogen to expel the air, add 10g of ferrous sulfate and 12g of copper sulfate, stir evenly, heat to 80°C in a water bath, add 25g of reducing agent sodium borohydride, continue stirring and reacting at 80°C for 3h, after the reaction is completed, wash, filter, dry, and grind through a 400-mesh sieve to obtain a boron nitride composite material.

[0070] Example 4

[0071] A method for preparing a motor carbon brush composite material comprises the following steps:

[0072] 60 parts of flake graphite powder, 20 parts of expanded graphite, 18 parts of copper powder, 6 parts of asphalt powder, 8 parts of boron nitride composite material, 3 parts of carboxymethyl cellulose and 4 parts of sulfur powder were put into a mixer and mixed evenly, stirred at 60°C for 2h, and then crushed, the obtained powder was sieved through a 200-mesh sieve to obtain micropowder, the obtained micropowder was pressed in a mold, and a blank was obtained after demolding, and then sintered at 850°C for 30min, and pressed under a pressure of 180MPa to obtain a motor carbon brush composite material;

[0073] Wherein, the preparation method of the boron nitride composite material is as follows:

[0074] S1. Add 10 g of hexagonal boron nitride to a mixed solution of 25 mL of H2O2 and 75 mL of H2SO4, and stir and immerse at 40°C for 5 h. After immersion, filter, wash, and dry to obtain pretreated hexagonal boron nitride.

[0075] S2, 12g pretreated hexagonal boron nitride and 8g nano silicon dioxide were mixed evenly, and then wet ball milling was performed, the ball-milled slurry was dried, crushed through a 400-mesh sieve, granulated, and then high-temperature sintered in a nitrogen atmosphere at a temperature of 1600°C for 2h, and then cooled to room temperature, crushed through a 400-mesh sieve, to obtain a boron nitride / silicon dioxide ceramic material;

[0076] S3, 12g of boron nitride / silicon dioxide ceramic material is dispersed in 150mL of deionized water, and then 6g of ammonium molybdate, 6g of thiourea and 1g of surfactant hexadecyltrimethylammonium bromide are added thereto, stirred evenly, and transferred to a reactor for hydrothermal reaction, the temperature of the hydrothermal reaction is 200°C, and the time of the hydrothermal reaction is 18h. After the reaction is completed, solid-liquid separation, washing and drying are performed to obtain a boron nitride / silicon dioxide / molybdenum disulfide composite material;

[0077] S4. Disperse 12 g of boron nitride / silicon dioxide / molybdenum disulfide composite material in 150 mL of deionized water, introduce nitrogen to expel air, add 8 g of ferrous sulfate and 10 g of copper sulfate, stir evenly, heat to 85°C in a water bath, add 24 g of reducing agent sodium borohydride, continue stirring and reacting at 85°C for 3 hours, and after the reaction is completed, wash, filter, dry, and grind through a 400-mesh sieve to obtain a boron nitride composite material.

[0078] Comparative Example 1

[0079] A method for preparing a motor carbon brush composite material comprises the following steps:

[0080] 40 parts of flake graphite powder, 15 parts of expanded graphite, 25 parts of copper powder, 8 parts of asphalt powder, 5 parts of boron nitride composite material, 1 part of carboxymethyl cellulose and 2 parts of sulfur powder were put into a mixer and mixed evenly, stirred at 60°C for 2h, and then crushed, the obtained powder was sieved through a 200-mesh sieve to obtain micropowder, the obtained micropowder was pressed in a mold, and a blank was obtained after demolding, and then sintered at 800°C for 45min, and pressed under a pressure of 160MPa to obtain a motor carbon brush composite material;

[0081] Wherein, the preparation method of the boron nitride composite material is as follows:

[0082] S1. Add 10 g of hexagonal boron nitride to a mixed solution of 25 mL of H2O2 and 75 mL of H2SO4, and stir and immerse for 3 h at 25 °C. After the immersion is completed, filter, wash, and dry to obtain pretreated hexagonal boron nitride;

[0083] S2, 10g of pretreated hexagonal boron nitride and 4g of nano-silicon dioxide were mixed evenly, and then wet-milled, the milled slurry was dried and crushed through a 400-mesh sieve to obtain a boron nitride / silicon dioxide composite material;

[0084] S3, 10g of boron nitride / silicon dioxide composite material was dispersed in 150mL of deionized water, and then 3g of ammonium molybdate, 5g of thiourea and 0.8g of surfactant hexadecyltrimethylammonium bromide were added thereto, stirred evenly, and transferred to a reactor for hydrothermal reaction at a temperature of 210°C for 18h. After the reaction was completed, solid-liquid separation, washing and drying were performed to obtain a boron nitride / silicon dioxide / molybdenum disulfide composite material;

[0085] S4. Disperse 10 g of boron nitride / silicon dioxide / molybdenum disulfide composite material in 150 mL of deionized water, introduce nitrogen to expel the air, add 6 g of ferrous sulfate and 8 g of copper sulfate, stir evenly, heat to 80°C in a water bath, then add 15 g of reducing agent sodium borohydride, continue stirring and reacting at 80°C for 3 hours. After the reaction is completed, wash, filter, dry, and grind through a 400-mesh sieve to obtain a boron nitride composite material.

[0086] Compared with Example 1, in Comparative Example 1, the pretreated hexagonal boron nitride and nano-silicon dioxide were not subjected to high-temperature sintering after wet ball milling.

[0087] Comparative Example 2

[0088] A method for preparing a motor carbon brush composite material comprises the following steps:

[0089] 40 parts of flake graphite powder, 15 parts of expanded graphite, 25 parts of copper powder, 8 parts of asphalt powder, 5 parts of boron nitride composite material, 1 part of carboxymethyl cellulose and 2 parts of sulfur powder were put into a mixer and mixed evenly, stirred at 60°C for 2h, and then crushed, the obtained powder was sieved through a 200-mesh sieve to obtain micropowder, the obtained micropowder was pressed in a mold, and a blank was obtained after demolding, and then sintered at 800°C for 45min, and pressed under a pressure of 160MPa to obtain a motor carbon brush composite material;

[0090] Wherein, the preparation method of the boron nitride composite material is as follows:

[0091] S1. Add 10 g of hexagonal boron nitride to a mixed solution of 25 mL of H2O2 and 75 mL of H2SO4, and stir and immerse for 3 h at 25 °C. After the immersion is completed, filter, wash, and dry to obtain pretreated hexagonal boron nitride;

[0092] S2, 10g pretreated hexagonal boron nitride and 4g nano silicon dioxide were mixed evenly, and then wet ball milling was performed, the ball-milled slurry was dried, crushed through a 400-mesh sieve, granulated, and then high-temperature sintered in a nitrogen atmosphere at a temperature of 1500°C for 2h, and then cooled to room temperature, crushed through a 400-mesh sieve, to obtain a boron nitride / silicon dioxide ceramic material;

[0093] S3. Disperse 10g of boron nitride / silicon dioxide ceramic material in 150mL of deionized water, then add 3g of ammonium molybdate, 5g of thiourea and 0.8g of surfactant hexadecyltrimethylammonium bromide, stir evenly, and transfer to a reactor for hydrothermal reaction. The temperature of the hydrothermal reaction is 210°C and the time of the hydrothermal reaction is 18h. After the reaction is completed, perform solid-liquid separation, washing and drying to obtain a boron nitride composite material.

[0094] Compared with Example 1, in Comparative Example 2, nanometer zero-valent copper and zero-valent iron are not loaded on the boron nitride / silicon dioxide / molybdenum disulfide composite material.

[0095] Comparative Example 3

[0096] A method for preparing a motor carbon brush composite material comprises the following steps:

[0097] 40 parts of flake graphite powder, 15 parts of expanded graphite, 25 parts of copper powder, 8 parts of asphalt powder, 5 parts of boron nitride composite material, 1 part of carboxymethyl cellulose and 2 parts of sulfur powder were put into a mixer and mixed evenly, stirred at 60°C for 2h, and then crushed, the obtained powder was sieved through a 200-mesh sieve to obtain micropowder, the obtained micropowder was pressed in a mold, and a blank was obtained after demolding, and then sintered at 800°C for 45min, and pressed under a pressure of 160MPa to obtain a motor carbon brush composite material;

[0098] Wherein, the preparation method of the boron nitride composite material is as follows:

[0099] S1. Add 10 g of hexagonal boron nitride to a mixed solution of 25 mL of H2O2 and 75 mL of H2SO4, and stir and immerse for 3 h at 25 °C. After the immersion is completed, filter, wash, and dry to obtain pretreated hexagonal boron nitride;

[0100] S2, 10g pretreated hexagonal boron nitride and 4g nano silicon dioxide were mixed evenly, and then wet ball milling was performed, the ball-milled slurry was dried, crushed through a 400-mesh sieve, granulated, and then high-temperature sintered in a nitrogen atmosphere at a temperature of 1500°C for 2h, and then cooled to room temperature, crushed through a 400-mesh sieve, to obtain a boron nitride / silicon dioxide ceramic material;

[0101] S3, 10g of boron nitride / silicon dioxide ceramic material is dispersed in 150mL of deionized water, and then 3g of ammonium molybdate, 5g of thiourea and 0.8g of surfactant hexadecyltrimethylammonium bromide are added thereto, stirred evenly, and transferred to a reactor for hydrothermal reaction, the temperature of the hydrothermal reaction is 210°C, and the time of the hydrothermal reaction is 18h. After the reaction is completed, solid-liquid separation, washing and drying are performed to obtain a boron nitride / silicon dioxide / molybdenum disulfide composite material;

[0102] S4. Disperse 10 g of boron nitride / silicon dioxide / molybdenum disulfide composite material in 150 mL of deionized water, introduce nitrogen to expel the air, add 8 g of copper sulfate, stir evenly, heat to 80°C in a water bath, then add 15 g of reducing agent sodium borohydride, continue stirring and reacting at 80°C for 3 hours. After the reaction is completed, wash, filter, dry, and grind through a 400-mesh sieve to obtain a boron nitride composite material.

[0103] Compared with Example 1, Comparative Example 3 does not load nano zero-valent iron.

[0104] The samples prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to performance tests, as follows:

[0105] Resistivity test: Tested in accordance with JB / T 8133.2-2013 standard;

[0106] Rockwell hardness test: Tested in accordance with JB / T 8133.3-2013 standard;

[0107] Electric friction experiment: The motor rotor and carbon brush are rubbed against each other, and the current density of the carbon brush is 67A / cm 2 , contact pressure 0.23MPa, rotor rotation speed 1000r / min, after continuous grinding for 100 hours, the length and size wear of the carbon brush are measured;

[0108] The power drop of carbon brush after 100,000 times: According to the working voltage: 12V; operation mode: work 1.5s, rest 28.5s; test conditions: air cooling test method, the carbon brush finished product is tested to detect the power drop of carbon brush after 100,000 times.

[0109] The test results are shown in the following table:

[0110]

[0111] Finally, it should be noted that the above embodiments do not limit the present invention in any form. For those skilled in the art, some modifications and improvements can be made to the present invention. Therefore, any modification or improvement made without departing from the spirit of the present invention belongs to the scope of protection claimed in the present invention.

Claims

1. A motor carbon brush composite material, characterized in that: The raw materials include the following components in parts by weight: 40-60 parts of flake graphite powder, 10-20 parts of expanded graphite, 15-25 parts of copper powder, 5-10 parts of asphalt powder, 4-8 parts of boron nitride composite material, 1-3 parts of carboxymethyl cellulose, and 2-4 parts of sulfur powder; Wherein, the preparation method of the boron nitride composite material is as follows: S1, adding hexagonal boron nitride to a mixed solution of H2O2 and H2SO4, stirring and impregnating, filtering, washing and drying after impregnation to obtain pretreated hexagonal boron nitride; S2, mixing the pretreated hexagonal boron nitride and nano-silicon dioxide uniformly, and then wet ball milling, drying the ball-milled slurry, crushing and screening, granulating, and then sintering at high temperature under a nitrogen atmosphere, and then cooling to room temperature, crushing and screening, to obtain a boron nitride / silicon dioxide ceramic material; S3, dispersing the boron nitride / silicon dioxide ceramic material in deionized water, then adding ammonium molybdate, thiourea and surfactant hexadecyltrimethylammonium bromide thereto, stirring evenly, transferring to a reactor for hydrothermal reaction, and after the reaction is completed, performing solid-liquid separation, washing and drying to obtain a boron nitride / silicon dioxide / molybdenum disulfide composite material; S4. Disperse the boron nitride / silicon dioxide / molybdenum disulfide composite material in deionized water, introduce nitrogen to expel the air, add ferrous sulfate and copper sulfate, stir evenly, heat in a water bath to 70-85°C, then add reducing agent sodium borohydride, stir to react, and after the reaction is completed, wash, filter, dry, grind and sieve to obtain the boron nitride composite material.

2. The motor carbon brush composite material according to claim 1, characterized in that: In step S1, the stirring and dipping temperature is 25-40°C, and the stirring and dipping time is 1-5h.

3. The motor carbon brush composite material according to claim 1, characterized in that: In step S2, the mass ratio of pretreated hexagonal boron nitride to nano-silicon dioxide is 10-15:4-8.

4. The motor carbon brush composite material according to claim 1, characterized in that: In step S2, the high temperature sintering temperature is 1500-1600°C, and the high temperature sintering time is 1-4h.

5. The motor carbon brush composite material according to claim 1, characterized in that: In step S3, the mass ratio of the boron nitride / silicon dioxide ceramic material, ammonium molybdate, thiourea and hexadecyltrimethylammonium bromide is 10-15:3-6:5-8:0.8-1.

2.

6. The motor carbon brush composite material according to claim 1, characterized in that: In step S3, the temperature of the hydrothermal reaction is 180-210° C., and the time of the hydrothermal reaction is 12-24 hours.

7. The motor carbon brush composite material according to claim 1, characterized in that: In step S4, the mass ratio of the boron nitride / silicon dioxide / molybdenum disulfide composite material, ferrous sulfate, copper sulfate and sodium borohydride is 10-15:6-10:8-12:15-25.

8. The motor carbon brush composite material according to claim 1, characterized in that: In step S4, the stirring reaction temperature is 70-85° C., and the stirring reaction time is 2-5 h.

9. The method for preparing the motor carbon brush composite material according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: putting each raw material into a mixer according to weight and mixing them evenly, stirring at 60-80°C for 1-2h, and then crushing the raw material, passing the obtained powder through a 200-mesh sieve to obtain micro powder, pressing the obtained micro powder in a mold, and obtaining a blank after demolding, and then sintering at 800-850°C for 30-60min, and pressing and molding at a pressure of 160-180MPa to obtain a motor carbon brush composite material.

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