A wind power electromagnetic brake friction material and a preparation method thereof

Abstract

The application relates to the technical field of friction materials, and discloses a wind power electromagnetic brake friction material and a preparation method thereof, which aims at the problem that the existing friction materials are cracked due to abrasion caused by heating during use, thereby affecting the strength and other performances of the friction materials. According to the wind power electromagnetic brake friction material, 20-30 parts of reinforcing materials, 30-45 parts of friction-increasing fillers, 10-20 parts of friction-reducing fillers, 5-15 parts of epoxy resin microcapsules, 2-5.5 parts of Ni-Ti alloy short fibers, 3.5-5 parts of epoxy-based polymers and 20-25 parts of adhesives are used. The epoxy resin microcapsules comprise core materials and wall materials, the core materials comprise epoxy resin and a curing agent, the wall materials comprise urea-formaldehyde resin, the particle size of the epoxy resin microcapsules is 10-30 mu m, and the thickness of the wall materials is 5-15 mu m. The epoxy resin microcapsules, the Ni-Ti alloy short fibers and the epoxy-based polymers are introduced, and the raw material components of the friction material are regulated, so that the friction material can be self-repaired after being abraded under heating, and the strength and other performances of the friction material can be kept stable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of friction materials, in particular to a wind power electromagnetic brake friction material and a preparation method thereof. BACKGROUND

[0002] Wind power generation refers to converting the kinetic energy of wind into mechanical energy, and then converting the mechanical energy into electric power energy. It is an important form of wind energy utilization. In recent years, with the development of the wind power market, the demand for the performance, safety and reliability of wind power equipment is increasing, and the requirements are becoming higher and higher. Among them, the electromagnetic brake, as one of the key safety components of the wind turbine generator system, directly affects the safe operation of the whole system, and the friction material, as the core component of the electromagnetic brake, is particularly critical in terms of friction performance, wear resistance and thermal stability.

[0003] The existing friction materials have problems such as insufficient strength and / or instability, low and unstable friction coefficient, and poor environmental adaptability. For example, the patent with the publication number CN119244671A provides a phase change heat storage composite brake pad friction material, a friction body and a preparation method thereof, which comprises Cu powder, Cr powder, V powder, CuAlMn particles, graphene powder and graphite powder in a mass ratio of 40-60:10-25:0.1-1.5:10-30:0.5-1.5:4-6. The brake pad friction material made of the above components has low friction coefficient, good wear resistance and good heat decay resistance. Cu is used as the matrix, and Cr and V are used as the reinforcing matrix components, which play an important role in the overall strength and wear resistance of the brake pad material. CuAlMn particles are used to effectively alleviate the instability of the friction coefficient and brake failure of the brake pad friction material caused by high temperature. Graphene and graphite are used as lubricating materials to effectively reduce and stabilize the friction coefficient and improve the thermal stability. However, the existing friction materials such as the above can only improve the high-temperature stability of the friction material to a certain extent by using high-temperature resistant components, but it is difficult to fundamentally solve or repair the damage caused by high temperature to the material.

[0004] Based on the above situation, there is an urgent need for a friction material that can maintain and repair the material form and performance more stably in the high-temperature environment caused by friction, to meet the performance requirements of wind power electromagnetic brakes. SUMMARY

[0005] The purpose of the present application is to solve the problem that the existing friction materials crack due to heating and other reasons during use, which affects the strength and other performance of the friction materials.

[0006] The application is achieved by the following technical solutions:

[0007] The application provides a wind power electromagnetic brake friction material, which comprises 20-30 parts of reinforcing materials, 30-45 parts of friction-reducing fillers, 10-20 parts of antifriction fillers, 5-15 parts of epoxy resin microcapsules, 2-5.5 parts of Ni-Ti alloy short fibers, 3.5-5 parts of epoxy-based polymers and 20-25 parts of adhesives in terms of mass fraction; the epoxy resin microcapsules comprise core materials and wall materials, the core materials comprise epoxy resin and curing agents, the wall materials comprise urea-formaldehyde resin, and the particle size of the epoxy resin microcapsules is 10-30 microns and the thickness of the wall materials is 5-15 microns.

[0008] Preferably, the preparation method of the epoxy resin microcapsules comprises the following steps:

[0009] A1, the epoxy resin and the curing agent are mixed in a mass ratio of 3:0.5-1.5, added into deionized water containing 1.5-3.5 wt% emulsifier, stirred, emulsified, and a repair emulsion is obtained;

[0010] A2, the urea and the formaldehyde are mixed in a mass ratio of 1:1-2, added into deionized water, a sodium hydroxide solution is added dropwise, heated and reacted, and a urea-formaldehyde resin prepolymer is obtained; the urea-formaldehyde resin prepolymer is added into the repair emulsion, hydrochloric acid is added dropwise, heated and reacted, and the primary microcapsules are obtained;

[0011] A3, the sodium hydroxide solution is added dropwise to the primary microcapsule material system until it is neutral, and then the system is left to stand, filtered, washed and dried, and the epoxy resin microcapsules are obtained.

[0012] Preferably, in step A2, the sodium hydroxide solution is added dropwise to adjust the pH value to 8.0-9.0, heated to 60-80℃, and reacted for 20-45 min; the hydrochloric acid is added dropwise to adjust the pH value to 2.0-3.0, heated to 50-60℃, and stirred and reacted for 2-4 h.

[0013] Preferably, in the Ni-Ti alloy short fibers, the mass percentage content of Ni is 54.5-57.0%, and the balance is Ti and inevitable impurities.

[0014] Preferably, the diameter of the Ni-Ti alloy short fibers is 0.1-0.3 mm, the length is 1-3 mm, and the surface is subjected to sandblasting treatment.

[0015] Preferably, the preparation method of the epoxy-based polymers comprises the following steps:

[0016] The epoxy resin, the cross-linking agent and the catalyst are mixed uniformly according to a mass ratio of 100:70-90:0.5-2, heated to 60-80 DEG C, pre-cured for 1-3h, heated to 100-130 DEG C again, secondly cured for 3-5h, cooled, and crushed to obtain the epoxy-based polymer.

[0017] Preferably, the particle size of the epoxy-based polymer is 800-1200 mu m.

[0018] The application further provides a preparation method of the wind power electromagnetic brake friction material.

[0019] S1 mixing: the raw materials are weighed and mixed uniformly, dried to obtain a premix;

[0020] S2 pressing: the premix is placed in a mold, and cold pressing and hot pressing are sequentially performed to obtain a pressed blank;

[0021] S3 heat treatment: the pressed blank is heat treated in the following multiple heating modes:

[0022] From room temperature, heating at 5-8 DEG C / min to 120-140 DEG C, and holding for 1-2h;

[0023] Then heating at 3-5 DEG C / min to 160-200 DEG C, and holding for 0.5-2h;

[0024] Then heating at 2-3 DEG C / min to 210-230 DEG C, and holding for 8-12h;

[0025] After furnace cooling, the wind power electromagnetic brake friction material is obtained by taking out and grinding.

[0026] Preferably, in step S2, the cold pressing treatment condition is that the cold pressing pressure is 50-60 MPa.

[0027] The hot pressing treatment condition is that the heating temperature is 170-180 DEG C, and the pressing pressure is 30-40 MPa.

[0028] Preferably, before the hot pressing treatment, exhaust treatment is performed: exhaust for 3-5s every 5-8s of pressing, and then perform 3-5 times of exhaust, and then perform 60-80s / mm pressure holding.

[0029] The technical scheme of the application has the following beneficial effects:

[0030] (1) The application introduces the epoxy resin microcapsules with core-shell structure into the friction material, and the epoxy resin and the curing agent are used as core materials, and the urea-formaldehyde resin is used as wall material.

[0031] The epoxy resin has good bonding performance and high strength after curing, can effectively fill the cracks on the surface of the friction material, and by selecting a low viscosity type of epoxy resin, the good flowability of the epoxy resin can further promote the rapid diffusion of the microcapsule to the damage site after the microcapsule is broken; and by using a curing agent such as dicyandiamide, when the friction material is subjected to heat stimulation of 120 DEG C or above, the curing agent can form a strong repair layer through a curing reaction with the epoxy resin, that is, the curing agent can not only play an effective repair role, but also can maintain good use performance of the friction material before heat stimulation.

[0032] The urea-formaldehyde resin has good film-forming property, sealing property and chemical corrosion resistance, can effectively wrap the core material, and avoid the premature curing and repair of the core material before the core material plays a repair role, thereby affecting the normal use of the friction material; and the mechanical property of the urea-formaldehyde resin can always break to release the repair core material when the friction material is subjected to wear and generates cracks.

[0033] (2) The Ni-Ti alloy short fiber and the epoxy-based polymer can jointly play a role in improving the mechanical property, the content of nickel and titanium in the Ni-Ti alloy short fiber is controlled to adjust the shape memory effect and super-elasticity of the alloy fiber in the working temperature range of 60-150 DEG C of the friction material, when the surface of the friction material appears wear or cracks, the Ni-Ti alloy short fiber generates phase transition under the action of heat generated by friction, and returns to the preset shape, and the stress generated thereby can promote the cracks to develop in the direction of closing; in addition, the epoxy-based polymer has high strength and good shape memory property, the content of monomers and curing agents and the like is adjusted to adjust the glass transition temperature of the epoxy-based polymer to coincide with the working temperature of the friction material of about 80-120 DEG C, when the temperature of the friction heat rises to above the glass transition temperature, the epoxy-based polymer softens and flows, and can be filled into the crack gap, and when the temperature decreases, the epoxy-based polymer is cured again, thereby achieving the role of repairing the cracks generated by heat of the friction material. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be clearly and completely described below. Wherein, the specific conditions in the embodiments are not specified, and are carried out according to conventional conditions or the conditions recommended by the manufacturer; the instruments, devices or reagents, raw materials and the like not specified by the manufacturer are all conventional products that can be obtained by market purchase.

[0035] The present application provides a kind of wind power electromagnetic brake friction material, by mass fraction, including 20~30 parts of reinforcing material, 30~45 parts of friction-enhancing filler, 10~20 parts of friction-reducing filler, 5-15 parts of epoxy resin microcapsule, 2-5.5 parts of Ni-Ti alloy short fiber, 3.5-5 parts of epoxy-based polymer and 20~25 parts of adhesive.

[0036] In the present application, the reinforcing material includes one or more of aramid pulp, acrylic pulp, modified lignin fiber, calcium sulfate whisker, four acicular zinc oxide whisker, etc.

[0037] The preparation process of the modified lignin fiber includes the following steps:

[0038] (1) Put the lignin fiber into 5-10wt% sodium hydroxide solution, heat to 40-60℃, soak for 30-40min, then wash with deionized water for several times, and dry at 60-80℃ for 1-2h;

[0039] (2) Then according to the mass ratio of 1:5-10, put the dried lignin fiber into 10-20wt% methyl imidazole chloride salt solution, heat to 80-100℃, stir for 1-2h; then add 1-3 times the mass of lignin fiber of acetic acid, maintain the above temperature, and stir for 2-5h; then add a large amount of distilled water, stand for precipitation, solid-liquid separation, take the lignin fiber, wash with deionized water for several times, and dry at 60-80℃ for 1-2h to obtain the modified lignin fiber.

[0040] The methyl imidazole chloride salt includes one or more of 1,3-dimethyl imidazole chloride salt, 1-ethyl-3-methyl imidazole chloride salt, 1-methyl-3-hydroxyethyl imidazole chloride salt, etc.

[0041] In the present application, the friction-increasing filler includes one or more of precipitated barium sulfate, acicular wollastonite, ice crystal, feldspar powder, friction powder, aluminum oxide, etc.

[0042] In the present application, the friction-reducing filler includes one or more of flake graphite, poly-p-hydroxybenzoate, hydrotalcite powder, etc.

[0043] In the present application, the adhesive includes one or more of phenolic resin, benzoxazine, nitrile rubber powder, etc.

[0044] In the present application, the epoxy resin microcapsule includes core material and wall material, the main components of the core material are epoxy resin and curing agent, the main component of the wall material is urea-formaldehyde resin, and the particle size of the epoxy resin microcapsule is 10-30μm, and the wall material thickness is 5-15μm, and the preparation method is as follows:

[0045] (1) Preparation of core material:

[0046] According to the mass ratio of 3:0.5-1.5, mix the epoxy resin and curing agent, then add to the deionized water containing 1.5-3.5wt% emulsifier, stir at 800-1200r / min, emulsify for 30-60min, form water-in-oil type repair emulsion, and the droplet size in the repair emulsion is 5-20μm.

[0047] (2) Coating treatment:

[0048] The urea and formaldehyde are mixed in a mass ratio of 1:1-2, then added into deionized water, stirred and dissolved, and sodium hydroxide solution is added dropwise until the pH value is adjusted to 8.0-9.0, heated to 60-80℃, and reacted for 20-45 min to obtain a urea-formaldehyde resin prepolymer.

[0049] The urea-formaldehyde resin prepolymer is added to the repair emulsion, hydrochloric acid is added dropwise until the pH value is adjusted to 2.0-3.0, heated to 50-60℃, and stirred and reacted for 2-4 h, and the urea-formaldehyde resin prepolymer is polymerized on the surface of the droplets of the repair emulsion to form a wall material to obtain a primary microcapsule.

[0050] (3) Post-treatment:

[0051] The sodium hydroxide solution is continuously added dropwise to the primary microcapsule material system until the pH value is adjusted to neutral, and the product is allowed to stand and precipitate, filtered, washed with deionized water several times, and dried at 50-70℃ for 20-28 h to obtain an epoxy resin microcapsule with self-repairing function.

[0052] In the present application, the mass percentage content of Ni in the Ni-Ti alloy short fiber is 54.5-57.0%, the balance is Ti and unavoidable impurities, and the content of each of carbon, hydrogen, nitrogen and other impurities is controlled to not more than 0.05wt%, the diameter of the short fiber is controlled to 0.1-0.3mm, the length is controlled to 1-3mm, and sandblasting treatment is carried out by using 0.5-1.5mm sand particles and 0.4-0.6MPa pressure, so that a certain roughness is formed on the surface of the Ni-Ti alloy short fiber, thereby enabling the Ni-Ti alloy short fiber to form a strong mechanical engagement effect with the base material of the friction material.

[0053] In the present application, the epoxy-based polymer is prepared by the following method: the epoxy resin, crosslinking agent and catalyst are uniformly mixed in a mass ratio of 100:70-90:0.5-2, heated to 60-80℃, pre-cured for 1-3h, then heated to 100-130℃, and secondarily cured for 3-5h, and after cooling, the product is crushed to a particle size of 800-1200μm granular material to obtain the epoxy-based polymer.

[0054] The preparation method of the wind power electromagnetic brake friction material of the present application comprises the following steps:

[0055] (1) Mixing

[0056] The raw materials are weighed according to the amount, mixed by high-energy ball milling and ultrasonic assistance, and placed in an oven at 60-80℃ for 1-2h to obtain a premix;

[0057] (2) Pressing

[0058] The premix is added into a cold pressing mold, the cold pressing pressure is adjusted to 50-60 MPa, and a blank is pressed to obtain a cold blank; the cold blank is then placed into a hot pressing mold, heated to 170-180℃, and pressed at a pressure of 30-40 MPa, first exhaust, exhaust for 3-5 s every 5-8 s of pressing, after 3-5 times of exhaust, pressure holding for 60-80 s / mm, to obtain a pressed blank;

[0059] (3) Heat treatment

[0060] The pressed blank is heated from room temperature to 120-140℃ at a rate of 5-8℃ / min, and held for 1-2 h; then heated to 160-200℃ at a rate of 3-5℃ / min, and held for 0.5-2 h; then heated to 210-230℃ at a rate of 2-3℃ / min, and held for 8-12 h; and then cooled to 50℃ or below in the furnace, and taken out.

[0061] (4) Post-treatment

[0062] The blank after heat treatment is ground by double-end-face abrasive belt to remove the surface oxide skin, burrs and flash, etc., to obtain a friction material that can be used in a wind power electromagnetic brake.

[0063] Example 1

[0064] Step 1: Preparation of weighed raw materials

[0065] Reinforcing material: take 1.5 mm aramid pulp, 1.5 mm acrylic pulp, 2 mm modified lignin fiber, 180 μm calcium sulfate whisker, and 350 mesh four-needle zinc oxide whisker in a mass ratio of 2:3:5:8:4, mix uniformly to obtain the reinforcing material.

[0066] Friction-increasing material: take 325 mesh precipitated barium sulfate, 24:1 needle-shaped wollastonite, 325 mesh ice crystal, 325 mesh feldspar powder, 70 mesh friction powder, and 325 mesh aluminum oxide in a mass ratio of 10:8:6:6:4:1, mix uniformly to obtain the friction-increasing material.

[0067] Friction-reducing material: take 100 mesh flake graphite, 325 mesh poly-p-hydroxybenzoic acid ester, and 6000 mesh hydrotalcite powder in a mass ratio of 5:3:6, mix uniformly to obtain the friction-reducing material.

[0068] Epoxy resin microcapsule: mixed epoxy resin and dicyandiamide with mass ratio of 3:1.2, added into deionized water containing 2wt% sodium dodecyl sulfate, emulsified by stirring at 1000r / min for 45min to obtain repair emulsion. Mixed urea and formaldehyde with mass ratio of 1:1.5, added into deionized water, stirred and dissolved, then added 20% sodium hydroxide solution dropwise, adjusted pH value to about 8.5, heated to 70℃, reacted for 35min to form urea-formaldehyde resin prepolymer. Added urea-formaldehyde resin prepolymer into repair emulsion, added hydrochloric acid dropwise, adjusted pH value to about 2.5, heated to 55℃, stirred and reacted for 3h to form urea-formaldehyde resin prepolymer coated repair liquid droplet primary microcapsule; then added 20% sodium hydroxide solution dropwise to adjust pH value to neutral, placed and precipitated, suction filtered, washed the filtered solid with deionized water for several times, dried at 60℃ for 24h to obtain epoxy resin microcapsule.

[0069] Ni-Ti alloy short fiber: took Ni-Ti alloy fiber containing 55.6wt% Ni and the balance of Ti and inevitable impurities, screened out short fibers with diameter of 0.2±0.05mm and length of 2±0.5mm, used 1mm sand particles to perform sandblasting treatment at 0.5MPa to obtain Ni-Ti alloy fiber.

[0070] Epoxy-based polymer: took bisphenol A type epoxy resin, methyl hexahydrophthalic anhydride and boron trifluoride ether with mass ratio of 100:80:1, mixed uniformly, heated to 70℃, pre-cured for 2h, then heated to 120℃, secondary cured for 4h, after cooling, crushed to 1000±50μm particle size granules to obtain epoxy-based polymer.

[0071] Adhesive: took 200 mesh phenolic resin, 200 mesh benzoxazine and 50 mesh butyronitrile rubber powder with mass ratio of 5:12:5 respectively, mixed uniformly to obtain adhesive.

[0072] According to mass ratio of 2.5:3.8:1.5:1:0.3:0.45:2.2, respectively weighed reinforcing material, friction-enhancing filler, friction-reducing filler, epoxy resin microcapsule, Ni-Ti alloy short fiber, epoxy-based polymer and adhesive, ready for use.

[0073] Step two: preparation of friction material

[0074] The raw materials of each component are sequentially mixed by high-energy ball milling and ultrasonic assistance, and then dried in a 70℃ oven for 1.5h to obtain a premix; the premix is placed in a cold pressing mold, and the cold pressing pressure is adjusted to 55MPa to press into a blank; then the blank is placed in a hot pressing mold, heated to about 175℃, and then pressed for 3 times with 5-8s of pressing and 3-5s of exhaust every time, and then hot pressed at 35MPa for 70s / mm, to obtain a pressed blank; the pressed blank is placed in a heating furnace, heated to 130℃ at a rate of 6.5℃ / min, and kept for 1.5h; then heated to 180℃ at a rate of 3.5℃ / min, and kept for 1.5h; then heated to 220℃ at a rate of 2.5℃ / min, and kept for 10h; then cooled to 50℃ or below in the furnace, taken out, and ground to obtain a wind power electromagnetic brake friction material.

[0075] Example 2

[0076] The difference between this example and Example 1 is that the mass ratio of the reinforcing material, the friction-increasing filler, the friction-reducing filler, the epoxy resin microcapsule, the Ni-Ti alloy short fiber, the epoxy-based polymer, and the binder in the raw materials of each component is 2.5:3.8:1.5:0.6:0.3:0.45:2.2.

[0077] Example 3

[0078] The difference between this example and Example 1 is that the mass ratio of the reinforcing material, the friction-increasing filler, the friction-reducing filler, the epoxy resin microcapsule, the Ni-Ti alloy short fiber, the epoxy-based polymer, and the binder in the raw materials of each component is 2.5:3.8:1.5:1:0.2:0.35:2.2.

[0079] Example 4

[0080] The difference between this example and Example 1 is that the mass ratio of the reinforcing material, the friction-increasing filler, the friction-reducing filler, the epoxy resin microcapsule, the Ni-Ti alloy short fiber, the epoxy-based polymer, and the binder in the raw materials of each component is 2.5:3.8:1.5:0.6:0.2:0.35:2.2.

[0081] Comparative Example 1

[0082] The difference between this example and Example 1 is that the mass ratio of the reinforcing material, the friction-increasing filler, the friction-reducing filler, the epoxy resin microcapsule, the Ni-Ti alloy short fiber, the epoxy-based polymer, and the binder in the raw materials of each component is 2.5:3.8:1.5:0.2:0.05:0.08:2.2.

[0083] Comparative Example 2

[0084] The difference between this example and Example 1 is that the raw materials of each component do not contain epoxy resin microcapsules.

[0085] Comparative Example 3

[0086] The difference between this example and Example 1 is that the component raw materials do not contain Ni-Ti alloy short fibers and epoxy-based polymers.

[0087] Comparative Example 4

[0088] The difference between this example and Example 1 is that the component raw materials do not contain epoxy resin microcapsules, Ni-Ti alloy short fibers and epoxy-based polymers.

[0089] Test Example

[0090] Samples: Examples 1-4, Comparative Examples 1-4

[0091] According to GB / T 5764-2023 "Automobile Clutch Facing", the friction coefficient and wear rate of the above different samples during heating and cooling were determined, and the results are summarized in Table 1 below:

[0092] Table 1 Test results of friction coefficient and wear rate of different samples

[0093]

[0094] According to GB / T 1041-2008 "Determination of Compression Properties of Plastics", the strength properties and changes of the above different samples were determined, and the results are summarized in Table 2 below:

[0095] Table 2 Test results of strength properties of different samples

[0096]

[0097] The above different samples were respectively assembled into electromagnetic brakes, and the electromagnetic brakes selected the model CDC-FD-P58-14(180V)45C30, the rated torque was 50 N·m, and the working gap was 0.3(+0.1 / -0.05)mm. Then the electromagnetic brakes were tested for emergency braking, and the test parameters were emergency braking energy 493J, rotation speed 810prm, and emergency braking times 1000. The test results are shown in Table 3 below:

[0098] Table 3 Emergency braking test results of electromagnetic brakes assembled with different samples

[0099]

[0100] It can be seen from the above tests and determination results that, compared with the comparative examples 1-4, the friction material prepared by the method proposed in the application in the example 1-4 has a more stable friction coefficient when facing temperature changes, a lower wear rate, and a significantly smaller degree of decrease in mechanical properties of the friction material after repeated wear, that is, the normal performance and working normality that can be maintained are more stable and more durable. Therefore, it can be shown from the above tests that the friction material of the application can solve the problem of existing friction materials that are cracked due to heat and other reasons during use, thereby affecting the strength and other properties of the friction material, that is, the friction material has more stable use performance.

[0101] The preferred embodiments of the application are described above, but the application is not limited to the above. Any modifications, equivalent replacements, improvements and the like made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A friction material for a wind turbine electromagnetic brake, characterized in that, By weight, it includes 20-30 parts reinforcing material, 30-45 parts friction-increasing filler, 10-20 parts friction-reducing filler, 5-15 parts epoxy resin microcapsules, 2-5.5 parts Ni-Ti alloy short fibers, 3.5-5 parts epoxy polymer and 20-25 parts adhesive; The epoxy resin microcapsules include a core material and a wall material. The core material includes epoxy resin and a curing agent, and the wall material includes urea-formaldehyde resin. The particle size of the epoxy resin microcapsules is 10-30 μm, and the wall material thickness is 5-15 μm. The Ni-Ti alloy short fibers contain 54.5-57.0% Ni by mass, with the balance being Ti and unavoidable impurities. The preparation method of the epoxy polymer includes the following steps: epoxy resin, crosslinking agent and catalyst are mixed evenly in a mass ratio of 100:70-90:0.5-2, heated to 60-80℃, pre-cured for 1-3 hours, then heated to 100-130℃, and cured for 3-5 hours. After cooling, the mixture is pulverized to obtain the epoxy polymer. The reinforcing material includes one or more of aramid pulp, acrylic pulp, modified lignin fiber, calcium sulfate whiskers, and tetraneedle-shaped zinc oxide whiskers. The friction-enhancing filler includes one or more of the following: precipitated barium sulfate, acicular wollastonite, cryolite, feldspar powder, friction powder, and alumina. The friction-reducing filler includes one or more of flake graphite, poly(p-hydroxybenzoate), and hydrotalcite powder.

2. The friction material for the wind power electromagnetic brake according to claim 1, characterized in that, The preparation method of the epoxy resin microcapsules includes the following steps: A1 Mix epoxy resin and curing agent at a mass ratio of 3:0.5-1.5, add to deionized water containing 1.5-3.5wt% emulsifier, stir, and emulsify to obtain repair emulsion; A2. Urea and formaldehyde are mixed at a mass ratio of 1:1-2, added to deionized water, sodium hydroxide solution is added dropwise, and the mixture is heated to react and obtain urea-formaldehyde resin prepolymer; the urea-formaldehyde resin prepolymer is added to the repair emulsion, hydrochloric acid is added dropwise, and the mixture is heated to react and obtain the initial microcapsules. A3 Add sodium hydroxide solution dropwise to the initial microcapsule material system until neutral, allow to stand and precipitate, filter, wash and dry to obtain the epoxy resin microcapsules.

3. The friction material for the wind power electromagnetic brake according to claim 2, characterized in that, In step A2, sodium hydroxide solution is added dropwise to adjust the pH to 8.0-9.0, and the mixture is heated to 60-80℃ and reacted for 20-45 minutes; hydrochloric acid is added dropwise to adjust the pH to 2.0-3.0, and the mixture is heated to 50-60℃ and stirred for 2-4 hours.

4. The friction material for the wind power electromagnetic brake according to claim 1, characterized in that, The Ni-Ti alloy short fibers have a diameter of 0.1-0.3 mm, a length of 1-3 mm, and a surface treated with sandblasting.

5. The friction material for the wind power electromagnetic brake according to claim 1, characterized in that, The epoxy polymer has a particle size of 800-1200 μm.

6. A method for preparing a friction material for a wind power electromagnetic brake as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1 Mixing: Take the raw materials of each component according to the specified amount, mix them evenly, and dry them to obtain the premix; S2 Compression Molding: The premixed material is placed in a mold and then subjected to cold pressing and hot pressing in sequence to obtain a pressed blank; S3 Heat Treatment: The pressed blank is heat-treated by heating it multiple times as follows: Starting from room temperature, heat to 120-140℃ at a rate of 5-8℃ / min, and hold for 1-2 hours; Then heat to 160-200℃ at a rate of 3-5℃ / min and hold for 0.5-2 hours; Then heat to 210-230℃ at 2-3℃ / min and hold for 8-12 hours; After cooling in the furnace, it is taken out and ground to obtain the friction material of the wind power electromagnetic brake.

7. The method for preparing the friction material for a wind power electromagnetic brake according to claim 6, characterized in that, In step S2, the cold pressing conditions are: cold pressing pressure is 50-60 MPa; The hot pressing conditions are: heating temperature of 170-180℃ and pressing pressure of 30-40MPa.

8. The method for preparing the friction material for a wind turbine electromagnetic brake according to claim 7, characterized in that, Before hot pressing, exhaust is performed: after pressing for 5-8 seconds, exhaust for 3-5 seconds, and after 3-5 exhaust cycles, hold the pressure for 60-80 seconds / mm.

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