Copper-free ceramic brake pad beneficial to electrostatic spraying and preparation method of copper-free ceramic brake pad

Abstract

The invention relates to the technical field of automobile brake pads, in particular to a copper-free ceramic brake pad beneficial to electrostatic spraying and a preparation method of the copper-free ceramic brake pad. The friction material of the copper-free ceramic brake pad comprises the following components in parts by weight: 4-10 parts of phenolic resin, 1-3 parts of a resin modifier, 10-20 parts of potassium titanate, 3-8 parts of friction powder, 2-11 parts of barium sulfate, 6-12 parts of a superconducting material, 1-5 parts of calcium fluoride, 3-8 parts of tire powder, 5-10 parts of calcium carbonate, 3-7 parts of iron oxide black, 1-3 parts of aluminum oxide, 2-7 parts of zirconium silicate and 5-15 parts of a reinforcing material. And 10-25 parts of a lubricating material. The superconductive material is added into the copper-free ceramic formula, the electrostatic spraying effect of the copper-free ceramic formula can be effectively improved, meanwhile, the superconductive material and the iron oxide black have the synergistic effect, the effect of stabilizing the friction coefficient can be achieved, and better appearance performance and performance improvement are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile brake pads, and in particular to a copper-free ceramic brake pad that is conducive to electrostatic spraying and a preparation method thereof. Background Art

[0002] With the continuous development of the automotive industry, people's requirements for the performance and quality of auto parts are also increasing. As a key component of the automobile braking system, the performance of brake pads is directly related to driving safety and driving experience.

[0003] Copper-free ceramic brake pads are increasingly popular with consumers due to their comfort, environmental friendliness, and long lifespan. These brake pads excel in reducing noise and dust pollution, while also improving braking performance and stability, becoming a trend in the brake pad industry.

[0004] In recent years, electrostatic spraying technology has been widely used in the brake pad industry to further enhance the aesthetics of brake pads. The principle of electrostatic spraying is as follows: the spray gun acts as the negative electrode of the electric field, and the workpiece acts as the positive electrode of the electric field and is well grounded. Under the influence of the electric field, the negatively charged paint powder is attracted to the workpiece, which serves as the positive electrode. When the paint powder reaches the workpiece surface, it transfers its own negative charge to the workpiece. Since the workpiece is grounded, the negative charge is quickly dissipated without accumulating on the workpiece, thereby preventing subsequent charged paint particles from reaching the workpiece surface. This technology enables the paint to adhere evenly to the brake pad surface, forming an attractive and durable coating. This not only improves the product's appearance but also enhances the brake pad's protective performance to a certain extent.

[0005] However, copper-free ceramic brake pads have encountered challenges when applying electrostatic spraying technology. Since copper-free ceramic formulas contain no metal components, their conductivity is poor. This makes it difficult for the coating powder to effectively adhere to the brake pad surface during the electrostatic spraying process, resulting in poor spraying results, uneven coating, and poor adhesion. This seriously affects the aesthetics and protective performance of the copper-free ceramic brake pads. This reduced aesthetics and protective performance directly leads to decreased customer satisfaction and safety, which to some extent limits the market promotion and application of copper-free ceramic brake pads.

[0006] Therefore, how to solve the problem of poor electrostatic spraying effect of copper-free ceramic brake pads has become a technical problem that needs to be urgently solved in the current brake pad industry. Summary of the Invention

[0007] In order to solve the above technical problems existing in the prior art, the present invention provides a copper-free ceramic brake pad that is conducive to electrostatic spraying and a preparation method thereof.

[0008] The technical scheme of the present application for solving the above technical problems is as follows: The first aspect of the present application is to provide a copper-free ceramic brake pad for electrostatic spraying, wherein the friction material of the copper-free ceramic brake pad comprises the following components in parts by weight: phenolic resin 4-10 parts, resin modifier 1-3 parts, potassium titanate 10-20 parts, friction powder 3-8 parts, barium sulfate 2-11 parts, superconductive material 6-12 parts, calcium fluoride 1-5 parts, tire powder 3-8 parts, calcium carbonate 5-10 parts, iron oxide black 3-7 parts, aluminum oxide 1-3 parts, zirconium silicate 2-7 parts, reinforcing material 5-15 parts, and lubricating material 10-25 parts.

[0009] On the basis of the above technical scheme, the present application can also be improved as follows: Further, the reinforcing material is a combination of two or more of aramid fiber, cellulose fiber, collagen fiber and mineral fiber; the lubricating material is a combination of two or more of petroleum coke, antimony sulfide and mica powder; and the resin modifier is nitrile rubber.

[0010] Further, the superconductive material is a mixture of graphite, graphene, boron nitride, liquid resin and glue powder, and the content of each component is 30-60% of graphite, 10-25% of graphene, 5-15% of boron nitride, 5-10% of liquid resin and 2-8% of glue powder.

[0011] The beneficial effects of the above further technical scheme are that the conductivity and thermal conductivity of the superconductive material are improved, and among them, boron nitride has a two-dimensional layered structure similar to graphene, and is an insulator itself, but when combined with graphene, it can serve as a "substrate" for graphene, reducing electron scattering and improving the conductivity of graphene.

[0012] Further, the tire powder is processed by crushing waste tires, the particle size of the tire powder is 40-80 mesh, and the tire powder comprises natural vulcanized rubber and styrene-butadiene vulcanized rubber.

[0013] Further, the tire powder is processed by crushing the tread rubber of the waste tire after removing the cord (cord layer), and the black rubber powder has a fineness of 40-80 mesh.

[0014] The beneficial effects of the above further technical scheme are that the hardness of the brake pad is reduced, which is conducive to reducing the braking noise.

[0015] Another aspect of the present application is to provide a preparation method of the above copper-free ceramic brake pad for electrostatic spraying, comprising the following steps: S1, preparing a superconductive material: adding each raw material into a liquid spraying mixer according to the weight parts to obtain the superconductive material by blending; S2, mixing: each component is added to the horizontal mixer according to the weight fraction, and the mixture is obtained by blending; S3, hot pressing: the mixture is hot pressed in a hot pressing mold to obtain a blank; S4, heat treatment: the blank is heat treated, and then cooled to room temperature; S5, machining: the blank after heat treatment is processed by flat grinding, chamfering and grooving; S6, spraying: the surface of the machined blank is uniformly sprayed with electrostatic spraying powder to obtain the copper-free ceramic brake pad.

[0016] Further, in S1, the stirring blade of the liquid injection mixer rotates at 1000-3000 r / min, and the plow blade rotates at 80-120 r / min. The blending time is controlled to be 3-8 minutes.

[0017] Further, in S2, the stirring blade of the horizontal mixer rotates at 3000-6000 r / min, and the plow blade rotates at 80-120 r / min. The blending time is controlled to be 8-12 minutes.

[0018] The stirring blade is a cross structure composed of a flying knife, which mainly breaks some long fiber materials. The plow blade is a plow type structure, which mainly turns over the material to make it uniformly mixed.

[0019] Further, in S3, the temperature of the hot pressing mold is controlled to be 145-165℃, the pressing pressure is 350kg / cm 2 , the pressing time is 5-10s, the air release time is 5-8s, the final pressure holding time is 180-300s, and the cycle number of pressing and air release is 5-10 times.

[0020] The hot pressing process using a hot pressing mold mainly includes the following steps: replacing the mold, inputting temperature, time, pressure and other parameters, heating, weighing, feeding, placing the steel back, pressing, air release, pressure holding, and completing, wherein the pressing and air release are repeated multiple times.

[0021] Further, in S4, the heat treatment includes the following steps: starting from room temperature, heating at a constant speed for 60-90 minutes, heating to 150-180℃, holding for 60-90 minutes, then heating at a constant speed for 60-90 minutes to 200-230℃, holding for 180-240 minutes, and finally naturally cooling to room temperature.

[0022] Further, in S6, the surface of the machined blank is uniformly sprayed with electrostatic spraying powder by using a spray gun, the spraying thickness is 40-100 mu m, the atomizing gas flow of the spray gun is 0.1 m³ / h, and the input gas pressure is 0.4-0.7 MPa; the sprayed product enters a tunnel furnace, the spraying powder is solidified, the temperature of the tunnel furnace is 180-220 DEG C, and the chain speed of the tunnel furnace is 40-60 Hz.

[0023] Further, between steps S2 and S3, the following steps are further included: steel back pre-treatment: the steel back is placed into a cleaning tank, 10-40 DEG C, cleaned for 5-10 minutes, dried at 90-110 DEG C for 2-5 minutes, and oil stains on the surface are removed; the cleaned steel back is placed into a shot blasting machine, 20-40 mesh steel shots are used for shot blasting for 8-12 minutes, and rust on the surface is removed; the shot blasted steel back is placed into a net tray and sent into a glue spraying equipment, glue spraying is performed, and the glue spraying thickness is 5-20 mu m.

[0024] The brake pad needs to be pressed together with the steel back and the friction material, the steel back is sprayed with glue, and the steel back and the friction material are bonded together to form the brake pad. During braking, the steel back is in contact with the caliper piston, and the friction material is in contact with the brake disc.

[0025] Compared with the prior art, the present application has the following technical effects: The application provides a copper-free ceramic brake pad facilitating electrostatic spraying, which is prepared by adding a premixed superconductive material into a friction material, so that the electrostatic spraying effect of the copper-free ceramic formula is effectively improved, and the premixed superconductive material and iron oxide black can cooperate to stabilize the friction coefficient; the boron nitride in the application belongs to a hexagonal crystal system, has a flaky structure, is also called white graphite, has a white loose appearance, soft texture and smooth feeling, is a high-temperature solid lubricant, has good thermal conductivity and chemical corrosion resistance, and can reduce the wear of the brake pad and the brake disc; the boron nitride has a two-dimensional layered structure similar to graphene, is an insulator, but can serve as a "substrate" of graphene when being combined with the graphene, can reduce electron scattering, and improve the conductive performance of the graphene; the resin modifier can reduce mold damage, reduce the water absorption of the mixture, improve the LOI (loss on ignition), reduce the gas release rate, and increase or maintain the impact and tensile strength of the product; calcium fluoride is a good solid lubricant and has a layered structure, can easily slip under the action of shear force, is a good high-temperature lubricating material, can effectively lubricate in the range of 250-700 DEG C, can still maintain good lubricating performance even if the temperature exceeds 1000 DEG C, has lubricating performance due to the brittle-to-plastic transition at high temperatures, in addition, the chemical action of fluorine in calcium fluoride with the wear surface in the friction process is also an important reason for the lubricating performance of calcium fluoride; the calcium fluoride has high stability at room temperature, but can chemically react to generate a continuous thin transfer film containing calcium elements under the environment of local high stress and high temperature in the friction process, and the generation of the thin transfer film improves the friction and wear performance of the friction pad; when the thin transfer film is generated, the wear rate of the brake pad can be obviously reduced; the addition of the tire powder into the friction material can effectively reduce the hardness of the brake pad and is beneficial to reducing the brake noise; and the friction material provided by the application can realize better appearance and performance improvement through reasonable collocation of the components. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A spraying effect photo of the copper-free ceramic brake pad prepared in Example 1 of the application is shown; Figure 2 A spraying effect photo of the copper-free ceramic brake pad prepared in Example 2 of the application is shown; Figure 3 A spraying effect photo of the copper-free ceramic brake pad prepared in Example 3 of the application is shown; Figure 4 A spraying effect photo of the copper-free ceramic brake pad prepared in Comparative Example 1 of the application is shown. DETAILED DESCRIPTION

[0027] The advantages and effects of the present application can be easily understood by those skilled in the art from the content disclosed in the specification. Although the description of the present application will be introduced in combination with the preferred embodiments, it does not mean that the features of the present application are limited to the embodiments. On the contrary, the purpose of introducing the present application in combination with the embodiments is to cover other options or modifications that can be extended based on the claims of the present application. In order to provide a deep understanding of the present application, many specific details will be included in the following description. The present application can also be implemented without using these details. In addition, in order to avoid confusion or ambiguity of the present application, some specific details will be omitted in the description. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0028] Embodiment 1 A copper-free ceramic brake pad for electrostatic spraying, the friction material is composed of the following components by weight: phenolic resin 10 parts, resin modifier 3 parts, potassium titanate 20 parts, friction powder 3 parts, barium sulfate 11 parts, super-conductive material 6 parts, calcium fluoride 5 parts, tire powder 3 parts, calcium carbonate 6.5 parts, black iron oxide 7 parts, aluminum oxide 3 parts, zirconium silicate 2 parts, aramid fiber 2.5 parts, mineral fiber 5 parts, petroleum coke 5 parts, mica powder 5 parts; the super-conductive material includes the following components by mass fraction: graphite 42%, graphene 25%, boron nitride 15%, liquid resin 10%, and glue powder 8%.

[0029] A preparation method of a copper-free ceramic brake pad for electrostatic spraying, comprising the following steps: 1) Preparation of super-conductive material: add the above raw materials of super-conductive material into a spray liquid mixer according to the proportion, set the stirring blade speed to 1000 r / min and the plow blade speed to 100 r / min, and blend for 5 minutes to obtain the super-conductive material; 2) Mixing: add each component into a horizontal mixer according to the weight fraction, set the stirring blade speed to 3000 r / min and the plow blade speed to 100 r / min, and blend for 10 minutes to obtain the mixed material; 3) Steel back pretreatment: place the steel back into a cleaning tank at 40℃, clean for 8 minutes, and dry at 110℃ for 5 minutes to remove the oil stains on the surface; place the cleaned steel back into a shot blasting machine, use 40-mesh steel shots for shot blasting for 8 minutes to remove the rust on the surface; place the shot blasted steel back into a net disc and send it into a glue spraying equipment for glue spraying, and the glue spraying thickness is 20μm; 4) Hot pressing: place the mixed material into a hot pressing mold and then place the glue sprayed steel back for hot pressing, the mold temperature is 150℃, the pressing pressure is 350kg / cm 2 , the pressing time is 10s, the releasing time is 5s, the final pressure maintaining time is 300s, and the cycle number of pressing and releasing is 8 times to obtain a blank body; 5) heat treatment: after hot pressing, the blank is placed in an oven, and the temperature is increased at a constant rate for 90 minutes from room temperature to 180℃, kept for 60 minutes, and then increased at a constant rate for 60 minutes to 210℃, kept for 180 minutes, and naturally cooled to room temperature.

[0030] 6) flat grinding, chamfering, and slotting treatment are performed on the semi-finished product prepared in step 4); 7) the semi-finished product prepared in step 5) is uniformly sprayed with electrostatic spraying powder using a spray gun, the spraying thickness is 80μm, the atomizing gas flow of the spray gun is 0.1m 3 / h, the input gas pressure is 0.5MPa; the sprayed product enters a tunnel furnace for curing of the spraying powder, the temperature of the tunnel furnace is 210℃, the chain speed of the tunnel furnace is 50Hz, and a copper-free ceramic brake pad is obtained.

[0031] Example 2 A copper-free ceramic brake pad beneficial for electrostatic spraying, the friction material is composed of the following components by weight parts: phenolic resin 4 parts, resin modifier 2 parts, potassium titanate 15 parts, friction powder 3 parts, barium sulfate 6 parts, superconductive material 12 parts, calcium fluoride 1 part, tire powder 8 parts, calcium carbonate 7 parts, iron oxide black 3 parts, aluminum oxide 1 part, zirconium silicate 7 parts, cellulose fiber 5 parts, mineral fiber 5 parts, antimony sulfide 7 parts, mica powder 5 parts; the superconductive material includes the following components by mass fraction: graphite 60%, graphene 15%, boron nitride 11%, liquid resin 8%, and glue powder 6%.

[0032] A method for preparing a copper-free ceramic brake pad beneficial for electrostatic spraying, comprising the following steps: 1) preparing a superconductive material: adding each raw material according to the weight fraction into a spray-type mixer, setting the stirring blade speed to 1000r / min and the plow blade speed to 100r / min, and blending for 5 minutes to obtain the superconductive material; 2) mixing: adding each component according to the weight fraction into a horizontal mixer, setting the stirring blade speed to 3000r / min and the plow blade speed to 100r / min, and blending for 10 minutes to obtain the mixture; 3) steel back pretreatment: placing the steel back into a cleaning tank at 40℃ for 8 minutes and drying at 110℃ for 5 minutes to remove surface oil stains; placing the cleaned steel back into a shot blasting machine and using 40-mesh steel shots for 8 minutes to remove surface rust; placing the shot blasted steel back into a net tray and feeding it into a glue spraying equipment for glue spraying with a thickness of 20μm; 4) hot pressing: placing the mixture into a hot pressing mold and then placing the glue sprayed steel back for hot pressing, the mold temperature is 150℃, and the pressing pressure is 350kg / cm 2The pressure time is 10s, the deflation time is 5s, the final pressure maintaining time is 300s, and the cycle number of pressure and deflation is 8, to obtain the blank; 5) heat treatment: the blank after hot pressing is put into an oven, and the temperature is increased at a constant speed for 90 minutes from room temperature to 180℃, and then kept for 60 minutes, and then increased at a constant speed for 60 minutes to 210℃, and then kept for 180 minutes, and then naturally cooled to room temperature; 6) the semi-finished product prepared in step 4) is processed by flat grinding, chamfering and grooving; 7) the semi-finished product prepared in step 5) is uniformly sprayed with electrostatic spraying powder by a spray gun, the spraying thickness is 80μm, the atomizing gas flow of the spray gun is 0.1m 3 / h, the input gas pressure is 0.5MPa; the product after spraying enters a tunnel furnace to solidify the spraying powder, the temperature of the tunnel furnace is 210℃, and the chain speed of the tunnel furnace is 50Hz.

[0033] Example 3 A copper-free ceramic brake pad for electrostatic spraying, the friction material is composed of the following components by weight: phenolic resin 8 parts, resin modifier 1 part, potassium titanate 10 parts, friction powder 8 parts, barium sulfate 7 parts, superconductive material 9 parts, calcium fluoride 3 parts, tire powder 5 parts, calcium carbonate 7 parts, black iron oxide 5 parts, friction powder 4 parts, aluminum oxide 2 parts, zirconium silicate 4 parts, aramid fiber 3 parts, mineral fiber 8 parts, antimony sulfide 4 parts, petroleum coke 7, mica powder 5; the superconductive material includes the following components by mass fraction: graphite 55%, graphene 22%, boron nitride 12%, liquid resin 7%, and glue powder 4%.

[0034] A preparation method of a copper-free ceramic brake pad for electrostatic spraying, comprising the following steps: 1) preparing superconductive material: adding each raw material according to the weight fraction into a spray liquid mixer, setting the stirring blade speed to 1000r / min and the plow blade speed to 100r / min, and blending for 5 minutes to obtain the superconductive material; 2) mixing: adding each component according to the weight fraction into a horizontal mixer, setting the stirring blade speed to 3000r / min and the plow blade speed to 100r / min, and blending for 10 minutes to obtain the mixture; 3) steel back pretreatment: placing the steel back into a cleaning tank at 40℃ for 8 minutes and drying at 110℃ for 5 minutes to remove the oil stains on the surface; placing the cleaned steel back into a shot blasting machine and using 40-mesh steel shots for 8 minutes to remove the rust on the surface; placing the shot blasted steel back into a net tray and feeding into a glue spraying equipment for glue spraying, and the glue spraying thickness is 20μm; 4) Hot pressing: the mixture is put into a hot pressing mold and then a steel back after glue spraying is put on to perform hot pressing, the mold temperature is 150°C, the pressing pressure is 350 kg / cm2, the pressing time is 10 s, the releasing time is 5 s, the final pressure maintaining time is 300 s, and the cycle number of pressing and releasing is 8 times, to obtain a blank; 5) Heat treatment: the blank after hot pressing is put into an oven, and the temperature is increased at a constant speed for 90 minutes from room temperature to 180°C, and then kept for 60 minutes, and then increased at a constant speed for 60 minutes to 210°C, and then kept for 180 minutes, and then naturally cooled to room temperature; 6) The semi-finished product obtained in step 4) is processed by flat grinding, chamfering and slotting; 7) The semi-finished product obtained in step 5) is uniformly sprayed with electrostatic spraying powder by using a spray gun, the spraying thickness is 80 μm, the atomizing gas flow of the spray gun is 0.1 m 3 / h, the input gas pressure is 0.5 Mpa; the product after spraying enters a tunnel furnace to solidify the spraying powder, the tunnel furnace temperature is 210°C, and the tunnel furnace chain speed is 50 Hz.

[0035] The preparation method of the copper-free ceramic brake pad of the comparative example is the same as that of example 1.

[0036] Comparative example 1 A copper-free ceramic brake pad, the friction material is composed of the following components in parts by weight: phenolic resin 8 parts, magnesium oxide 6 parts, potassium titanate 18 parts, friction powder 4 parts, barium sulfate 12 parts, vermiculite 7 parts, wollastonite 10 parts, calcium fluoride 5 parts, calcium carbonate 5 parts, aluminum oxide 3 parts, zirconium silicate 2 parts, aramid fiber 2 parts, mineral fiber 5 parts, petroleum coke 5 parts, and mica powder 5 parts.

[0037] The preparation method of the copper-free ceramic brake pad of the comparative example is the same as that of example 1, and the difference from example 1 is that in step 4) hot pressing process, the pressing pressure is 400 Kg / cm 3 , and the mold temperature is 155°C.

[0038] Test method explanation: (1) Coefficient of friction: SAE J2522 performance procedure; (2) Wear data: SAE J2707 wear procedure.

[0039] (3) Noise data: SAE J2521 noise procedure; The test data of each example and comparative example is shown in Table 1.

[0040] Table 1 Test data of each example and comparative example

[0041] The brake pad needs to be pressed with the steel back and the friction material together, and the steel back is bonded with the friction material after being sprayed with glue to make the brake pad. The steel back contacts the piston of the caliper during braking, and the friction material contacts the brake disc. Two brake pads and one disc are provided for one wheel of the automobile, and the inner pad refers to the inner brake pad which is usually in contact with the inner piston of the caliper, and the outer pad refers to the outer brake pad which is usually in contact with the outer piston of the caliper.

[0042] It can be seen from the test data in Table 1 that the copper-free ceramic brake pad for electrostatic spraying has not only good appearance, but also better product performance. It has good performance in braking force (friction coefficient), comfort (noise occurrence rate), service life (wear data), etc. A small amount of pre-mixed super-conductive material is added to the copper-free ceramic formula of the application, which can effectively improve the electrostatic spraying effect of the copper-free ceramic formula, and the pre-mixed super-conductive material and iron oxide black can synergistically stabilize the friction coefficient. Through the reasonable collocation of the two materials, better appearance and performance improvement can be achieved.

[0043] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A copper-free ceramic brake pad that is conducive to electrostatic spraying, characterized in that: The friction material of the copper-free ceramic brake pad includes the following components by weight: 4-10 parts of phenolic resin, 1-3 parts of resin modifier, 10-20 parts of potassium titanate, 3-8 parts of friction powder, 2-11 parts of barium sulfate, 6-12 parts of superconducting material, 1-5 parts of calcium fluoride, 3-8 parts of tire powder, 5-10 parts of calcium carbonate, 3-7 parts of iron oxide black, 1-3 parts of aluminum oxide, 2-7 parts of zirconium silicate, 5-15 parts of reinforcing material, and 10-25 parts of lubricating material.

2. The copper-free ceramic brake pad that is conducive to electrostatic spraying according to claim 1 is characterized in that: The reinforcing material is a combination of two or more of aramid fiber, cellulose fiber, collagen fiber and mineral fiber; the lubricating material is a combination of two or more of petroleum coke, antimony sulfide and mica powder; and the resin modifier is nitrile rubber.

3. The copper-free ceramic brake pad that is conducive to electrostatic spraying according to claim 1 is characterized in that: The superconducting material is a mixture of graphite, graphene, boron nitride, liquid resin and rubber powder as raw materials. The content of each component is as follows by mass: 30-60% graphite, 10-25% graphene, 5-15% boron nitride, 5-10% liquid resin and 2-8% rubber powder.

4. The copper-free ceramic brake pad that is conducive to electrostatic spraying according to claim 1 is characterized in that: The tire powder is obtained by crushing waste tires, the particle size of the tire powder is 40 to 80 meshes, and the tire powder includes natural vulcanized rubber and styrene-butadiene vulcanized rubber.

5. A method for preparing a copper-free ceramic brake pad that is conducive to electrostatic spraying according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Preparing a superconducting material: adding the raw materials according to their weight parts into a liquid jet mixer and blending to obtain a superconducting material; S2. Mixing: adding each component according to parts by weight into a horizontal mixer and blending to obtain a mixture; S3, hot pressing: hot pressing the mixed material in a hot pressing mold to obtain a green body; S4, heat treatment: heat treating the green body and then cooling it to room temperature; S5, machining: grinding, chamfering and slotting the heat-treated blank; S6. Spraying: evenly spraying electrostatic spray powder on the surface of the machined blank to obtain the copper-free ceramic brake pad.

6. The method for preparing a copper-free ceramic brake pad that is conducive to electrostatic spraying according to claim 5, characterized in that: In S1, the stirring blade speed of the spray mixer is 1000-3000 r / min, the plow blade speed is 80-120 r / min, and the blending time is controlled to be 3-8 minutes.

7. The method for preparing a copper-free ceramic brake pad that is conducive to electrostatic spraying according to claim 5, characterized in that: In S2, the stirring blade speed of the horizontal mixer is controlled to be 3000 r / min-6000 r / min, the plow blade speed is controlled to be 80-120 r / min, and the blending time is controlled to be 8-12 minutes.

8. The method for preparing a copper-free ceramic brake pad that is conducive to electrostatic spraying according to claim 5, characterized in that: In S3, the temperature of the hot pressing mold is controlled to be 145-165℃, the pressing pressure is 350kg / cm², the pressing time is 5-10s, the degassing time is 5-8s, the final holding time is 180-300s, and the number of pressurization and degassing cycles is 5-10 times.

9. The method for preparing a copper-free ceramic brake pad that is conducive to electrostatic spraying according to claim 5, characterized in that: In S4, the heat treatment includes the following steps: starting from room temperature, heating at a constant rate for 60-90 minutes to 150-180°C, keeping the temperature at that temperature for 60-90 minutes, heating at a constant rate for another 60-90 minutes to 200-230°C, keeping the temperature at that temperature for 180-240 minutes, and finally cooling naturally to room temperature.

10. The method for preparing a copper-free ceramic brake pad that is conducive to electrostatic spraying according to claim 5, characterized in that: In S6, a spray gun is used to evenly spray electrostatic spray powder on the surface of the machined blank, with a spraying thickness of 40-100 μm. The atomizing gas flow rate of the spray gun is 0.1 m 3 / h, the input air pressure is 0.4-0.7MPa; the sprayed product enters the tunnel furnace to solidify the spray powder, the tunnel furnace temperature is 180-220℃, and the tunnel furnace chain speed is 40-60Hz.

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