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 motor carbon brush composite material comprises the following raw materials in parts by weight: 50-65 parts of modified copper-based metal powder, 40-55 parts of modified crystalline flake graphite powder, 10-17 parts of copper powder, 7-13 parts of silver tungsten powder, 5-10 parts of asphalt powder and 2-3 parts of sulfur powder. The motor carbon brush composite material is a metal-based composite material, has good heat resistance, thermal conductivity and electrical conductivity, improves the wear resistance of the motor carbon brush composite material, still has good wear resistance under a high-current condition, and prolongs the service life of the motor carbon brush composite material.

Description

Technical Field

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

[0002] A carbon brush is a device for transmitting energy or signals between the fixed part and the rotating part of a motor, and is an important component of the motor. It is widely applicable to various AC and DC generators, synchronous motors, etc. The quality and performance of the carbon brush affect the normal operation of the motor. During the operation of the motor, the carbon brush undergoes various mechanical friction and wear, accompanied by arc erosion and electrical wear. Conventional carbon brushes will show phenomena such as increased wear and severe arc erosion under high-density current conditions, greatly weakening the wear resistance of the carbon brush and shortening its service life. Therefore, there is an urgent need to develop a brush material with good wear resistance under high-current conditions. Summary of the Invention

[0003] At least aiming at one of the above problems existing in the prior art, the present invention provides a motor carbon brush composite material and a preparation method thereof. The motor carbon brush composite material is a metal matrix composite material, which has good heat resistance, thermal conductivity and electrical conductivity, improves the wear resistance of the motor carbon brush composite material, and still has good wear resistance under high-current conditions, extending its service life.

[0004] To achieve the above object, the present invention adopts the following technical solution: A motor carbon brush composite material, comprising the following raw materials in parts by weight: 50 - 65 parts of modified copper-based metal powder, 40 - 55 parts of modified flake graphite powder, 10 - 17 parts of copper powder, 7 - 13 parts of silver tungsten powder, 5 - 10 parts of asphalt powder, and 2 - 3 parts of sulfur powder.

[0005] Preferably, the modified copper-based metal powder is obtained by mixing a mixture of copper powder, nickel powder and tin powder, melting and atomizing to form an alloy powder, then grinding the alloy powder with silicon carbide, and then mixing with graphite powder and reacting with an unsaturated gaseous carbon source material.

[0006] Preferably, in the modified copper-based metal powder, the weight of nickel powder is 3 - 4% of the weight of copper powder, the weight of tin powder is 1 - 2% of the weight of copper powder, the weight of graphite powder is 4 - 5% of the weight of copper powder, and the weight of silicon carbide is 2 - 3% of the weight of copper powder.

[0007] Preferably, the unsaturated gaseous carbon source material is one of ethylene, acetylene or propylene.

[0008] Preferably, the specific preparation method of the modified copper-based metal powder is as follows:

[0009] A1) Mix copper powder, nickel powder and tin powder, then heat and melt to form an alloy liquid, remove impurities, and then atomize to form an alloy powder to obtain copper-based metal powder;

[0010] A2) Mix the copper-based metal powder with silicon carbide and grind for 20 - 30 min, then add graphite powder and mix. After that, heat under an inert gas, and then introduce an unsaturated gaseous carbon source material and react for 30 - 40 min to obtain the modified copper-based metal powder.

[0011] Preferably, in step A1), the melting temperature is 1250 - 1300 °C.

[0012] Preferably, in step A1), the atomization air pressure is 1 - 1.2 MPa.

[0013] Preferably, in step A2), the heating temperature under an inert gas is 1150 - 1200 °C.

[0014] Preferably, the modified flake graphite powder is obtained by oxidizing and roasting flake graphite with hydrogen peroxide.

[0015] Preferably, the specific preparation method of the modified flake graphite powder is as follows:

[0016] B1) Immerse the flake graphite powder in a mixed solution of hydrogen peroxide aqueous solution and concentrated sulfuric acid, and perform ultrasonic treatment. Then filter, wash, and dry to obtain oxidized flake graphite powder;

[0017] B2) Roast the oxidized flake graphite powder to obtain the modified flake graphite powder.

[0018] Preferably, in step B1), the volume ratio of 30% hydrogen peroxide aqueous solution to 98% concentrated sulfuric acid in the hydrogen peroxide and concentrated sulfuric acid mixed solution is 1:1.

[0019] Preferably, in step B1), the ultrasonic treatment conditions are: ultrasonic temperature is 30 - 35 °C, ultrasonic power is 300 - 400 W, and ultrasonic time is 40 - 50 min.

[0020] Preferably, in step B2), the roasting temperature is 800 - 850 °C, and the roasting time is 10 - 15 min.

[0021] Preferably, in the silver tungsten powder, the tungsten content is 25 - 35%, and the rest is silver.

[0022] The present invention also provides a preparation method of a motor carbon brush composite material, comprising the following steps:

[0023] (1) First, mix the modified flake graphite powder, copper powder, and silver tungsten powder, grind, and then add the modified copper-based metal powder, asphalt powder, and sulfur powder and stir and mix evenly to obtain a mixed powder;

[0024] (2) Place the mixed powder in a mold and press it into shape to obtain a blank;

[0025] (3) Sinter the blank under nitrogen protection and then cool it with a nitrogen-hydrogen mixed gas to obtain the motor carbon brush composite material.

[0026] Preferably, it further includes step (4) of processing the motor carbon brush composite material into motor carbon brush bars.

[0027] Preferably, in step (1), the grinding time is 30 - 50 min; the stirring rate is 350 - 450 rpm, and the stirring time is 20 - 30 min.

[0028] Preferably, in step (2), the pressing pressure is 120 - 130 Mpa, and the pressing time is 2 - 3 s.

[0029] Preferably, in step (3), the sintering temperature is 750 - 800 °C, and the sintering time is 4 - 6 h.

[0030] Advantages of the present invention:

[0031] 1. The motor carbon brush composite material of the present invention uses modified copper-based metal powder, modified flake graphite powder, copper powder, silver tungsten powder, asphalt powder and sulfur powder as raw materials to form a metal matrix composite material with a compound system. First, mix and grind the modified flake graphite powder, copper powder and silver tungsten powder, then add the modified copper-based metal powder, asphalt powder and sulfur powder and mix them, then press and sinter. Through the mutual cooperation of each raw material, it has good heat resistance and thermal conductivity, improves the wear resistance and hardness of the motor carbon brush composite material, avoids the problem of increased wear caused by temperature rise, also improves the electrical conductivity of the motor carbon brush composite material, and can withstand higher currents at the same time, avoiding the problem of serious current ablation caused by high currents, thereby extending the service life of the motor carbon brush.

[0032] 2. The motor carbon brush composite material of the present invention forms an alloy powder by melting and atomizing the mixture of copper powder, nickel powder and tin powder, which improves the strength and hardness of the modified copper-based metal powder. Then, the alloy powder is first ground with silicon carbide, then mixed with graphite powder and reacted with an unsaturated gaseous carbon source material to obtain the modified copper-based metal powder, which makes the modified copper-based metal powder have better wettability, adhesiveness, heat resistance, etc. At the same time, it also improves the current conduction efficiency of the modified copper-based metal powder, helps to improve the wear resistance and high current resistance characteristics of the modified copper-based metal powder, as well as its bonding performance with asphalt powder, thereby improving the mechanical properties of the carbon brush material.

[0033] 3. The motor carbon brush composite material of the present invention introduces oxygen-containing functional groups into the flake graphite powder through concentrated sulfuric acid and hydrogen peroxide under ultrasonic treatment, and then calcines it to obtain the modified flake graphite powder, which makes the modified flake graphite powder have a larger specific surface area, high diffusivity and heat resistance, helps to reduce the friction coefficient of the motor carbon brush composite material, improves the wear resistance of the material, and also improves its bonding performance with asphalt powder, thereby improving the mechanical properties of the carbon brush material.

[0034] 4. The motor carbon brush composite material of the present invention, the modified flake graphite powder contains oxygen functional groups, which has good compatibility. When grinding with copper powder and silver tungsten, it is beneficial for the copper powder and silver tungsten to be evenly dispersed in the modified flake graphite powder and form a good interfacial bond with the modified flake graphite powder, which is beneficial to reducing the resistivity of the motor carbon brush composite material and improving the current resistance characteristics of the modified flake graphite powder. Detailed implementation mode

[0035] The following is a clear and complete description of the technical solutions in the implementation of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer.

[0036] Preparation example 1

[0037] The preparation of the modified copper-based metal powder of the present invention is specifically carried out according to the following steps:

[0038] A1) Mix copper powder, nickel powder and tin powder. The weight of nickel powder is 3% of the weight of copper powder, and the weight of tin powder is 1% of the weight of copper powder. Then heat to 1250 °C for melting to form an alloy liquid, remove impurities, and then atomize at a pressure of 1 MPa to form alloy powder, obtaining copper-based metal powder;

[0039] A2) Mix the copper-based metal powder with silicon carbide and grind for 20 min. The silicon carbide is 2% of the weight of copper powder, then add graphite powder and mix. The graphite powder is 4% of the weight of copper powder. Then heat to 1150 °C under inert gas, and then introduce ethylene and react for 40 min to obtain the modified copper-based metal powder.

[0040] Preparation example 2

[0041] The preparation of the modified copper-based metal powder of the present invention is specifically carried out according to the following steps:

[0042] A1) Mix copper powder, nickel powder and tin powder. The weight of nickel powder is 3.5% of the weight of copper powder, and the weight of tin powder is 1.2% of the weight of copper powder. Then heat to 1275 °C for melting to form an alloy liquid, remove impurities, and then atomize at a pressure of 1.1 MPa to form alloy powder, obtaining copper-based metal powder;

[0043] A2) Mix the copper-based metal powder with silicon carbide and grind for 25 min. The silicon carbide is 2.5% of the weight of copper powder, then add graphite powder and mix. The graphite powder is 4.5% of the weight of copper powder. Then heat to 1175 °C under inert gas, and then introduce acetylene and react for 35 min to obtain the modified copper-based metal powder.

[0044] Preparation Example 3

[0045] The preparation of the modified copper-based metal powder of the present invention is carried out as follows:

[0046] A1) Mix copper powder, nickel powder and tin powder. The weight of nickel powder is 4% of the weight of copper powder, and the weight of tin powder is 2% of the weight of copper powder. Then heat to 1300 °C for melting to form an alloy liquid, remove impurities, and then atomize at a pressure of 1.2 MPa to form alloy powder, obtaining copper-based metal powder;

[0047] A2) Mix the copper-based metal powder with silicon carbide and grind for 30 min. The weight of silicon carbide is 3% of the weight of copper powder, then add graphite powder and mix. The weight of graphite powder is 4% of the weight of copper powder. Then heat to 1200 °C under inert gas, and then introduce propylene and react for 30 min to obtain the modified copper-based metal powder.

[0048] Preparation Example 4

[0049] The preparation of the modified flake graphite powder of the present invention is carried out as follows:

[0050] B1) Immerse the flake graphite powder in a mixed solution with a volume ratio of 1:1 of 30% hydrogen peroxide aqueous solution and 98% concentrated sulfuric acid, and carry out ultrasonic treatment at a temperature of 35 °C and a power of 350 W for 45 min. Then filter, wash and dry to obtain oxidized flake graphite powder;

[0051] B2) Roast the oxidized flake graphite powder at a temperature of 820 °C for 12 min to obtain the modified flake graphite powder.

[0052] Example 1

[0053] A motor carbon brush composite material comprises the following raw materials in parts by weight: 50 parts of modified copper-based metal powder, 40 parts of modified flake graphite powder, 10 parts of copper powder, 7 parts of silver-tungsten powder, 5 parts of asphalt powder and 2 parts of sulfur powder; in the silver-tungsten powder, the tungsten content is 25%, and the rest is silver;

[0054] The preparation method of the motor carbon brush composite material is carried out as follows:

[0055] (1) First, mix 40 parts of the modified flake graphite powder, 10 parts of copper powder and 7 parts of silver-tungsten powder in Preparation Example 4, grind for 30 min, then add 50 parts of the modified copper-based metal powder, 5 parts of asphalt powder and 2 parts of sulfur powder in Preparation Example 1 and mix, and stir at a speed of 350 rpm for 20 min to obtain a mixed powder;

[0056] (2) Place the mixed powder in a mold and press at a pressure of 120 Mpa for 3 s to form a blank;

[0057] (3) Sinter the blank under nitrogen protection at a temperature of 750 °C for 6 h, and then cool it with a nitrogen-hydrogen mixed gas to obtain the motor carbon brush composite material;

[0058] (4) Process the motor carbon brush composite material into motor carbon brush bars.

[0059] Example 2

[0060] A motor carbon brush composite material, comprising the following raw materials in parts by weight: 58 parts of modified copper-based metal powder, 47 parts of modified flake graphite powder, 14 parts of copper powder, 10 parts of silver-tungsten powder, 7.5 parts of asphalt powder, and 2.5 parts of sulfur powder; in the silver-tungsten powder, the tungsten content is 30%, and the rest is silver;

[0061] The preparation method of the motor carbon brush composite material is as follows:

[0062] (1) First, mix 47 parts of the modified flake graphite powder, 14 parts of copper powder, and 10 parts of silver-tungsten powder in Preparation Example 4, grind for 40 min, then add 58 parts of the modified copper-based metal powder, 7.5 parts of asphalt powder, and 2.5 parts of sulfur powder in Preparation Example 1 and mix them, and stir at a speed of 400 rpm for 25 min to obtain a mixed powder;

[0063] (2) Place the mixed powder in a mold and press it at a pressure of 125 Mpa for 2.5 s to form a blank;

[0064] (3) Sinter the blank under nitrogen protection at a temperature of 775 °C for 5 h, and then cool it with a nitrogen-hydrogen mixed gas to obtain the motor carbon brush composite material;

[0065] (4) Process the motor carbon brush composite material into motor carbon brush bars.

[0066] Example 3

[0067] A motor carbon brush composite material, comprising the following raw materials in parts by weight: 65 parts of modified copper-based metal powder, 55 parts of modified flake graphite powder, 17 parts of copper powder, 13 parts of silver-tungsten powder, 10 parts of asphalt powder, and 3 parts of sulfur powder; in the silver-tungsten powder, the tungsten content is 35%, and the rest is silver;

[0068] The preparation method of the motor carbon brush composite material is as follows:

[0069] (1) First, mix 55 parts of the modified flake graphite powder, 17 parts of copper powder, and 13 parts of silver-tungsten powder in Preparation Example 4, grind for 50 min, then add 65 parts of the modified copper-based metal powder, 10 parts of asphalt powder, and 3 parts of sulfur powder in Preparation Example 1 and mix them, and stir at a speed of 450 rpm for 30 min to obtain a mixed powder;

[0070] (2) Place the mixed powder in a mold and press it at a pressure of 130 Mpa for 2 s to form a blank;

[0071] (3) Sinter the blank under nitrogen protection at a temperature of 800 °C for 4 h, and then cool it with a nitrogen-hydrogen mixed gas to obtain the motor carbon brush composite material;

[0072] (4) Process the motor carbon brush composite material into motor carbon brush bars.

[0073] Example 4

[0074] A motor carbon brush composite material, comprising the following raw materials in parts by weight: 55 parts of modified copper-based metal powder, 50 parts of modified flake graphite powder, 12 parts of copper powder, 10 parts of silver-tungsten powder, 5 parts of asphalt powder, and 2 parts of sulfur powder; in the silver-tungsten powder, the tungsten content is 30%, and the rest is silver;

[0075] The preparation method of the motor carbon brush composite material is specifically as follows:

[0076] (1) First, mix 55 parts of the modified flake graphite powder, 17 parts of copper powder, and 13 parts of silver-tungsten powder in Preparation Example 4, grind for 50 min, and then add 65 parts of the modified copper-based metal powder, 10 parts of asphalt powder, and 3 parts of sulfur powder in Preparation Example 2, and stir at a rotation speed of 400 rpm for 30 min to obtain a mixed powder;

[0077] (2) Place the mixed powder in a mold and press it at a pressure of 125 Mpa for 2 s to form a blank;

[0078] (3) Sinter the blank under nitrogen protection at a temperature of 780 °C for 4 h, and then cool it with a nitrogen-hydrogen mixed gas to obtain the motor carbon brush composite material;

[0079] (4) Process the motor carbon brush composite material into motor carbon brush bars.

[0080] Example 5

[0081] A motor carbon brush composite material, comprising the following raw materials in parts by weight: 60 parts of modified copper-based metal powder, 45 parts of modified flake graphite powder, 11 parts of copper powder, 7.5 parts of silver-tungsten powder, 6 parts of asphalt powder, and 2.5 parts of sulfur powder; in the silver-tungsten powder, the tungsten content is 30%, and the rest is silver;

[0082] The preparation method of the motor carbon brush composite material is specifically as follows:

[0083] (1) First, mix 55 parts of the modified flake graphite powder, 17 parts of copper powder, and 13 parts of silver-tungsten powder in Preparation Example 4, grind for 30 min, and then add 65 parts of the modified copper-based metal powder, 10 parts of asphalt powder, and 3 parts of sulfur powder in Preparation Example 2, and stir at a rotation speed of 400 rpm for 20 min to obtain a mixed powder;

[0084] (2) Place the mixed powder in a mold and press it at a pressure of 120 Mpa for 2 s to form a blank;

[0085] (3) Sinter the blank under nitrogen protection at a temperature of 750 °C for 5 h, and then cool it with a nitrogen-hydrogen mixed gas to obtain the motor carbon brush composite material;

[0086] (4) Process the motor carbon brush composite material into motor carbon brush bars.

[0087] Comparative Example 1

[0088] A motor carbon brush composite material and its preparation method, which is different from Example 2 in that: it does not contain modified copper-based metal powder, the weight of copper powder is adjusted to 72 parts, and 14 parts of copper powder are ground together with silver tungsten powder and modified flake graphite powder; the rest are exactly the same.

[0089] Comparative Example 2

[0090] A motor carbon brush composite material and its preparation method, which is different from Example 2 in that: the modified flake graphite powder is adjusted to flake graphite powder, and the flake graphite powder is ground together with copper powder and silver tungsten powder; the rest are exactly the same.

[0091] Comparative Example 3

[0092] A motor carbon brush composite material and its preparation method, which is different from Example 2 in that: it does not contain silver tungsten powder, and the weight portion of copper powder is adjusted to 24 parts of copper powder, and the rest are exactly the same.

[0093] Comparative Example 4

[0094] A motor carbon brush composite material and its preparation method, which is different from Example 2 in that: in the silver tungsten powder, the tungsten content is 40%, and the rest is silver; the rest are exactly the same.

[0095] Comparative Example 5

[0096] A motor carbon brush composite material and its preparation method, which is different from Example 2 in that: in the silver tungsten powder, the tungsten content is 20%, and the rest is silver; the rest are exactly the same.

[0097] Comparative Example 6

[0098] A motor carbon brush composite material and its preparation method, which is different from Example 2 in that: in step A2) of the preparation of the modified copper-based metal powder, the copper-based metal powder, silicon carbide, and graphite powder are mixed, the silicon carbide is 2% of the weight of the copper powder, the graphite powder is 4% of the weight of the copper powder, and then heated to 1150 °C under an inert gas, and then ethylene is introduced and reacted for 40 min to obtain the modified copper-based metal powder; the rest are exactly the same.

[0099] Comparative Example 7

[0100] A motor carbon brush composite material and its preparation method, which is different from Example 2 in that: in step (1), 58 parts of modified copper-based metal powder, 47 parts of modified flake graphite, 14 parts of copper powder, 10 parts of silver-tungsten powder, 7.5 parts of asphalt powder and 2.5 parts of sulfur powder are mixed and stirred at a speed of 400 rpm for 25 min to obtain a mixed powder; the rest is exactly the same.

[0101] Test experiment: The motor carbon brush strips processed from the motor carbon brush composite materials prepared in Examples 1 to 5 and Comparative Examples 1 to 7 are tested for resistivity, Rockwell hardness, wear, and high-current resistance. The results are shown in Tables 1 and 2.

[0102] 1. Resistivity test: Test according to the JB / T8133.2-2013 standard;

[0103] 2. Rockwell hardness test: Test according to the JB / T8133.3-2013 standard;

[0104] 3. Flexural strength test: Test according to the JB / T8133.7-2013 standard;

[0105] 4. Wear test: The motor rotor and the carbon brush are abraded against each other. The current density of the carbon brush is 67 A / cm 2 , the contact pressure is 0.23 MPa, the rotor rotation speed is 1000 r / min, and the length dimension wear amount of the carbon brush is measured after continuous abrasion for 100 h;

[0106] 5. Carbon brush power decline after 100,000 times: According to the working voltage: 12 V, operating mode: working for 1.5 s, resting for 28.5 s; test conditions: air-cooled test method, the carbon brush finished product is tested for the carbon brush power decline after 100,000 times of working tests;

[0107] 6. High-current resistance: The environmental temperature is 120 °C. The carbon brush is assembled on the fan assembly to simulate the real vehicle environment. A DC voltage of 13.5 V is provided, and the wear time of the carbon brush until it is worn out is tested when the fan is running at high speed.

[0108] Table 1 Resistivity, Rockwell hardness, wear performance

[0109]

[0110] Table 2 High-current resistance

[0111] Average wear time (h) Average current value (A) Example 1 1287 28.3 Example 2 1318 29.4 Example 3 1298 28.5 Example 4 1323 29.2 Example 5 1302 29.1 Comparative Example 1 1073 26.3 Comparative Example 2 1032 26.5 Comparative Example 3 1089 26.0 Comparative Example 4 1044 26.4 Comparative Example 5 1105 26.6 Comparative Example 6 1042 25.2 Comparative Example 7 1038 25.9

[0112] As can be seen from Table 1 and Table 2 above, compared with Comparative Examples 1-5, Example 2 uses a compound system of modified copper-based metal powder, modified flake graphite powder, copper powder, silver tungsten powder, asphalt powder and sulfur powder, and the tungsten content in the silver tungsten powder is 25-35%. Through the mutual cooperation between the raw materials, the motor carbon brush composite material has good heat resistance, thermal conductivity and electrical conductivity, improves the wear resistance, hardness and mechanical properties of the motor carbon brush composite material, and reduces its resistivity, not only avoiding the problem of increased wear caused by temperature rise, but also enabling the motor carbon brush composite material to withstand higher currents and avoiding the serious problem of current ablation caused by high currents; compared with Comparative Examples 6 and 7, in the preparation of the modified copper-based metal powder in Example 2, alloy powder and silicon carbide are ground, which can form a conductive channel between the silicon carbide particles at the interface of the alloy powder. In the preparation of the motor carbon brush composite material, the modified flake graphite powder is ground with copper powder and silver tungsten, forming a good interface bond with the modified flake graphite powder and enhancing the conductive channel between the interfaces of the modified flake graphite powder. This not only reduces the resistivity of the motor carbon brush composite material, but also improves the high-current resistance performance of the motor carbon brush composite material.

[0113] In summary, the motor carbon brush composite material of the present invention is a metal matrix composite material, which forms a compound system with modified copper-based metal powder, modified flake graphite powder, copper powder, silver tungsten powder, asphalt powder and sulfur powder as raw materials. First, the modified flake graphite powder, copper powder and silver tungsten powder are mixed and ground, then the modified copper-based metal powder, asphalt powder and sulfur powder are added and mixed, and then pressed and sintered. Through the mutual cooperation between the raw materials, the wear resistance and hardness of the motor carbon brush composite material are improved, and at the same time, it has good heat resistance and thermal conductivity, avoiding the problem of increased wear caused by temperature rise, and also improving the electrical conductivity of the motor carbon brush composite material, enabling it to withstand higher currents and avoiding the serious problem of current ablation caused by high currents.

[0114] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit and basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

[0115] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A motor carbon brush composite material, characterized in that, it comprises the following raw materials in parts by weight: 50 - 65 parts of modified copper-based metal powder, 40 - 55 parts of modified flake graphite powder, 10 - 17 parts of copper powder, 7 - 13 parts of silver tungsten powder, 5 - 10 parts of asphalt powder, and 2 - 3 parts of sulfur powder.

2. The motor carbon brush composite material according to claim 1, characterized in that, the modified copper-based metal powder is obtained by mixing a mixture of copper powder, nickel powder and tin powder, melting and atomizing to form an alloy powder, then grinding the alloy powder with silicon carbide, and then mixing with graphite powder and reacting with an unsaturated gaseous carbon source material.

3. The motor carbon brush composite material according to claim 2, characterized in that, in the modified copper-based metal powder, the weight of nickel powder is 3 - 4% of the weight of copper powder, the weight of tin powder is 1 - 2% of the weight of copper powder, the weight of graphite powder is 4 - 5% of the weight of copper powder, and the weight of silicon carbide is 2 - 3% of the weight of copper powder.

4. The motor carbon brush composite material according to claim 2, characterized in that, the unsaturated gaseous carbon source material is one of ethylene, acetylene or propylene.

5. The motor carbon brush composite material according to any one of claims 1 - 4, characterized in that, the specific preparation method of the modified copper-based metal powder is as follows: A1) Mix copper powder, nickel powder and tin powder, then heat and melt to form an alloy liquid, remove impurities, and then atomize to form an alloy powder to obtain copper-based metal powder; A2) Mix the copper-based metal powder with silicon carbide and grind for 20 - 30 min, then add graphite powder and mix, then heat under an inert gas, and then introduce an unsaturated gaseous carbon source material and react for 30 - 40 min to obtain the modified copper-based metal powder.

6. The motor carbon brush composite material according to claim 1, characterized in that, the modified flake graphite powder is obtained by oxidizing and roasting flake graphite.

7. The motor carbon brush composite material according to claim 1 or 6, characterized in that, the specific preparation method of the modified flake graphite powder is as follows: B1) Immerse the flake graphite powder in a mixed solution of hydrogen peroxide aqueous solution and concentrated sulfuric acid, and perform ultrasonic treatment, then filter, wash and dry to obtain oxidized flake graphite powder; B2) Roast the oxidized flake graphite powder to obtain the modified flake graphite powder.

8. The motor carbon brush composite material according to claim 1, characterized in that, in the silver tungsten powder, the tungsten content is 25 - 35%, and the rest is silver.

9. A preparation method of the motor carbon brush composite material according to claim 1, characterized in that, it comprises the following steps: (1) First mix the modified flake graphite powder, copper powder and silver tungsten powder, grind, and then add the modified copper-based metal powder, asphalt powder and sulfur powder and stir and mix evenly to obtain a mixed powder; (2) Place the mixed powder in a mold and press it into shape to obtain a blank; (3) Sinter the blank under nitrogen protection, and then cool it with a nitrogen-hydrogen mixed gas to obtain the motor carbon brush composite material.

10. The preparation method of the motor carbon brush composite material according to claim 9, characterized in that, In step (1), the grinding time is 30 to 50 min; in step (2), the pressing pressure is 120 to 130 Mpa and the pressing time is 2 to 3 s; in step (3), the sintering temperature is 750 to 800 °C and the sintering time is 4 to 6 h.

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