CN115896531A - Copper-based powder metallurgy friction material and preparation method and application thereof - Google Patents
Copper-based powder metallurgy friction material and preparation method and application thereof Download PDFInfo
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- 239000002783 friction material Substances 0.000 title claims abstract description 74
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 71
- 238000004663 powder metallurgy Methods 0.000 title claims abstract description 42
- 239000010949 copper Substances 0.000 title claims abstract description 37
- 229910052802 copper Inorganic materials 0.000 title claims abstract description 37
- 238000002360 preparation method Methods 0.000 title abstract description 13
- 239000000463 material Substances 0.000 claims abstract description 92
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 60
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 54
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 52
- 239000010439 graphite Substances 0.000 claims abstract description 52
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 44
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 41
- 239000002994 raw material Substances 0.000 claims abstract description 29
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000004576 sand Substances 0.000 claims abstract description 20
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 20
- 239000003350 kerosene Substances 0.000 claims abstract description 19
- 238000010030 laminating Methods 0.000 claims abstract description 4
- 239000000203 mixture Substances 0.000 claims description 71
- 238000000034 method Methods 0.000 claims description 50
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- 241000357293 Leptobrama muelleri Species 0.000 claims description 14
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
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- 239000002131 composite material Substances 0.000 description 3
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical group [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 3
- 238000011161 development Methods 0.000 description 3
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- CREMABGTGYGIQB-UHFFFAOYSA-N carbon carbon Chemical compound C.C CREMABGTGYGIQB-UHFFFAOYSA-N 0.000 description 2
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- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 description 2
- 229910052982 molybdenum disulfide Inorganic materials 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/72—Wind turbines with rotation axis in wind direction
Abstract
The invention discloses a copper-based powder metallurgy friction material and a preparation method and application thereof, wherein the powder metallurgy friction material is formed by laminating a friction layer material and a bonding layer material; the friction layer material is composed of main raw materials and auxiliary materials, wherein the main raw materials comprise the following components in percentage by mass: 65-72% of copper powder, 6-9% of iron powder, 2-8% of granular graphite, 3-7% of flake graphite, 2-5% of molybdenum powder, 3-6% of silica sand and 2-6% of tin powder. The auxiliary material is kerosene; the bonding layer material comprises the following components in percentage by mass: 70-80% of copper powder, 10-20% of iron powder and 5-15% of tin powder. The invention adopts a double-layer material formula, and utilizes the binding material layer to improve the binding force between the friction material and the support steel backing on the premise of not influencing the friction and wear performance of the friction material, thereby solving the problem of the peeling of the friction block of the wind power brake pad.
Description
Technical Field
The invention belongs to the technical field of preparation of powder metallurgy friction materials, and particularly relates to a copper-based powder metallurgy friction material and a preparation method and application thereof.
Background
Clean energy is vigorously developed to solve the problems of increasing energy demand and decreasing resources all over the world. At present, petroleum and natural gas resources which are mainly adopted belong to non-renewable resources, the price of the related resources is increasingly high, and the energy safety becomes a problem which needs to be solved in the development of various countries. Therefore, the development of clean, environment-friendly and renewable new energy sources becomes the key point of the development of all countries. The wind generating set is used as power generation equipment with wide application, and the use safety is particularly important. The wind power brake is used as a key component of the wind turbine generator, friction heating is performed in the braking process, a large amount of heat can be generated, and the heat fading phenomenon of a friction material is caused due to the temperature rise. Therefore, the performance of the friction material is related to the safety and the power generation aging ratio of the wind generating set. With the gradual installation and use of a wind turbine with higher power, the friction material for braking is required to have more excellent performance, and has the characteristics of high coefficient, low abrasion and the like under a high-energy condition. Meanwhile, the thermal stress generated by the temperature rise of the friction material after the high kinetic energy is converted into the heat energy is met. And the stable operation of the wind power generator set is ensured.
Common friction materials such as resin-based friction materials and carbon-carbon composite friction materials are applied to wind power main shaft braking, have certain limitations and are difficult to meet requirements. The resin-based friction material has poor thermal conductivity, when the temperature exceeds 400 ℃ during braking, the wear rate is quickly increased, the friction coefficient is reduced along with the components, and the resin-based friction material is only suitable for low-power wind turbines. The carbon-carbon composite friction material has the advantages of good mechanical property, good high-temperature resistance braking performance, light weight and the like. However, under the working conditions of rain, snow and humidity, the friction coefficient is rapidly reduced, and the cost is high, so that the wind turbine generator is not suitable for use. The copper-based friction material prepared by the powder metallurgy method is suitable for the braking working condition at a higher temperature, and has the characteristics of stable friction coefficient, high strength, good heat conductivity and small abrasion. The wind power generation equipment is required to operate stably for a long time outdoors, complex environments need to be tested, and the high-performance copper-based powder metallurgy friction material has excellent performance, can effectively improve the operation time of a wind turbine generator, reduces the maintenance cost, and is an ideal choice for a wind power brake. The copper-based powder metallurgy friction material for the wind power brake at present also has some problems, and the most important is that the performance at high temperature (above 600 ℃) is unstable, the heat fading phenomenon often appears in the braking process, the friction coefficient is unstable, the abrasion loss is increased, the heat stress difference causes the friction block to peel off, and the like, and the use requirement of a wind power unit is not met.
Disclosure of Invention
In view of the shortcomings of the prior art, a first object of the present invention is to provide a copper-based powder metallurgy friction material.
The second purpose of the invention is to provide a preparation method of the copper-based powder metallurgy friction material.
The third purpose of the invention is to provide application of the copper-based powder metallurgy friction material, and the powder metallurgy friction material is used for a wind turbine braking device.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to a copper-based powder metallurgy friction material, which is formed by laminating a friction layer material and a bonding layer material; the friction layer material is prepared from main raw materials and auxiliary materials, wherein the main raw materials comprise the following components in percentage by mass: 65-72% of copper powder, 6-9% of iron powder, 2-8% of granular graphite, 3-7% of flake graphite, 2-5% of molybdenum powder, 3-6% of silica sand and 2-6% of tin powder; the auxiliary material is kerosene; the bonding layer material comprises the following raw materials in percentage by mass: 70-80% of copper powder, 10-20% of iron powder and 5-15% of tin powder.
The powder metallurgy friction material provided by the invention is formed by laminating a friction layer material and a bonding layer material, wherein the bonding layer material is bonded with a supporting steel back; the high-melting-point iron and silica sand are used as friction components, and the high hardness and good thermal stability of the friction materials are utilized to ensure that the friction materials in the formula still maintain stable mechanical strength and excellent friction and wear performance under the harsh condition of braking, and meanwhile, the high-melting-point molybdenum powder can effectively improve the oxidation resistance of the materials and prevent copper oxidation of a metal matrix under the condition of high energy and high temperature; meanwhile, two kinds of graphite with different configurations are used as the lubricant, incompatibility with other lubricating components is reduced, particle graphite and strip-shaped flake graphite which are made of the same material can be organically combined, a three-dimensional reinforcing effect is achieved, the interface binding force of a nonmetal and metal material is improved, and the use strength of the material is guaranteed. The invention adopts a double-layer material formula, improves the binding force between the friction material and the supporting steel back by utilizing the binding material layer on the premise of not influencing the frictional wear performance of the friction material ratio, and effectively solves the peeling phenomenon of the friction block of the wind power brake pad.
In a preferred scheme, the friction layer material comprises the following main raw materials in percentage by mass: 66-70% of copper powder, 7-8% of iron powder, 5-7% of granular graphite, 4-5% of flake graphite, 2-5% of molybdenum powder, 4-5% of silica sand and 5-6% of tin powder.
Preferably, the average particle size of the granular graphite is 50 meshes, and the average particle size of the flake graphite is 80 meshes.
In the invention, a three-dimensional structure can be formed by adopting artificial granular graphite and natural crystalline flake graphite according to a specific proportion, the crystalline flake graphite forms grids, and the granular graphite is distributed in the grids and mutually reinforced, so that the particle diameters of the granular graphite and the crystalline flake graphite are controlled within the range, and the finally formed three-dimensional reinforcing effect is optimal.
If only natural crystalline flake graphite is adopted, the natural crystalline flake graphite is parallel to a friction surface in a strip mode in a matrix, an arch bridge effect is easily formed, and holes and cracks formed on a material interface are easily caused. If only artificial graphite particles are adopted, the artificial graphite particles are embedded in the matrix in a polygonal mode in the braking process, so that the artificial graphite particles are easy to fall off, and the abrasion is accelerated.
Preferably, the copper powder is electrolytic copper powder, and the particle size of the copper powder is 45-75 μm.
Preferably, the iron powder is reduced iron powder, and the particle size of the iron powder is 56 to 106 μm.
Preferably, the particle size of the tin powder is 45 to 75 μm.
In a preferred embodiment, the particle size of the molybdenum powder is 2 to 5 μm.
Preferably, the particle size of the silica sand is 150 to 300 μm.
The inventor finds that by adopting the raw materials with the particle sizes, the performance of the final material is optimal, the particle size is reasonable, the proper powder particle size and shape formed after mixing are facilitated, the particle size distribution of the metal components and the nonmetal components is reasonable, the homogenization process of the components and the base metal in the sintering process is ensured, the binding force between the final components of the product and the base is improved, and the strength and the frictional wear performance of the powder metallurgy product are improved.
In the preferable scheme, the kerosene is aviation kerosene, and the addition amount of the kerosene is 1.0-2.0% of the total mass of the main raw materials.
The invention relates to a preparation method of a copper-based powder metallurgy friction material, which comprises the steps of preparing raw materials in a bonding layer material according to a designed proportion, mixing to obtain a bonding layer mixture, sieving the bonding layer mixture into a mold cavity through a screen, then preparing main raw materials and auxiliary materials in the friction layer material according to the designed proportion, mixing to obtain a friction layer mixture, pouring the friction layer mixture into the mold cavity to cover the upper part of the bonding layer mixture, placing the mold under a press for press forming to obtain a double-layer pressed blank containing the bonding layer and the friction layer, bonding the bonding layer in the double-layer pressed blank with a support steel back, and sintering to obtain the powder metallurgy friction material.
According to the preparation method of the copper-based powder metallurgy friction material, the bonding layer mixture is firstly screened into the mold through the screen and placed at the bottom of the mold, and the inventor finds that the bonding layer mixture can be uniformly distributed in the cavity of the mold, and one side of the bonding layer mixture does not exist, and the other side of the bonding layer mixture does not exist. The bonding layer material can relieve thermal stress caused by large difference of thermal expansion coefficients between the friction material and the support steel back, so that the friction material falls off from the support steel back. And then pouring the friction layer mixture into a die cavity to strickle the material surface, uniformly filling the powder material, then, pressing and molding the powder in the die cavity under the action of a press to obtain a double-layer pressed compact containing the bonding layer and the friction layer, attaching the double-layer pressed compact to a support steel back, and sintering to obtain the powder metallurgy friction material.
In a preferred scheme, the obtaining process of the bonding layer mixture comprises the following steps: firstly weighing tin powder, passing through a 100-mesh screen, mixing with copper powder to obtain a mixture A, adding iron powder into the mixture A, manually premixing, and mixing in a mixer at a rotating speed of 50-120 r/min for 0.5-1 h.
The inventor finds that the tin powder is sieved firstly, then is manually mixed with the copper powder, and finally is mixed with the iron powder, so that the problem that the low-melting-point tin powder is separated out during sintering due to agglomeration of the tin powder, the proportion in the mixture is influenced, and the performance of the composite material cannot meet the requirement can be effectively avoided.
In a preferred scheme, the friction layer mixture is obtained by the following steps: the friction layer mixture obtaining process comprises the following steps: weighing tin powder, passing through a 100-mesh screen, mixing with copper powder, sieving with a 40-mesh screen to obtain a mixture C, adding iron powder, molybdenum powder and silica sand into the mixture C, mixing to obtain a mixed powder D, mixing granular graphite, flake graphite and kerosene to obtain a mixed powder E, manually premixing the mixed powder D and the mixed powder E, and mixing in a mixer at a rotating speed of 50-120 r/min for 3-6 h.
The inventor finds that the mixing process of the raw materials has great influence on the performance of the final material, and in the process of obtaining the friction layer mixture, on one hand, the tin powder is sieved firstly, then is manually and uniformly mixed with the copper powder, and then is mixed with the iron powder, the molybdenum powder and the silica sand, so that the tin powder in the obtained friction layer mixture can be effectively prevented from agglomerating, the low-melting-point tin powder is prevented from being separated out in advance in the sintering process, and the product proportion is changed; on the other hand, the invention fully wets and uniformly mixes the graphite by the granular graphite, the crystalline flake graphite and the kerosene, thereby avoiding the quality loss and uneven distribution of the graphite caused by floating in the mixing process due to low density of the graphite. And finally, before mechanical mixing, the materials can be mixed more uniformly by manual premixing, and the particle sizes of the components are proper and the components are uniformly distributed by controlling the rotating speed and time of the mixer. The inventors have found that even in the final mechanical compounding process, if the time is too short, the rotation speed is too low, the compound is not mixed sufficiently, the particle size gap is too large, and the subsequent densification is insufficient. The time is too long, the rotating speed is too high, so that the mixture is broken, the granularity is too small, agglomeration occurs, the component distribution is uneven, and the final mechanical alloying of the product is influenced.
In the preferred scheme, the compression molding pressure is 200-400 Mpa, and the pressure maintaining time is less than or equal to 3s. The inventor finds that the mixed powder can be pressed and formed only by keeping the pressure for 1-3 s, and if the pressing time is too long, the internal stress of the material is too large, and the pressed blank is layered and edge-removed after being demoulded. The pressure of the compression molding also needs to be effectively controlled, if the compression pressure is too small, the green compact density is insufficient, the number of gaps is large, and the final product performance cannot meet the requirement; the pressed compact is easy to crack or seriously damage due to overlarge pressing pressure.
In the invention, the steel back is processed by adopting a high-quality carbon structural steel cold-rolled steel plate, electroplating protection is adopted, and the surface coating of the steel back after sintering is uniform in color and luster, and free of material stripping and serious bubbles.
Preferably, the sintering is carried out in a protective atmosphere, the pressure per unit area is 0.4-1.1 MPa, the sintering temperature is 900-950 ℃, and the sintering time is 2-4 h.
The copper-based friction material adopts sectional type pressure sintering, so that the density of the copper-based friction material can be improved, the components of each component in the formula are ensured to fully react in the sintering process of single axial pressure, and other components added in the formula can be uniformly distributed in the copper base material, so that the consistency and stability in the material preparation and forming process are guaranteed. Finally, the copper-based powder metallurgy friction material with good bonding strength and excellent performance is obtained.
Further preferably, the sintering process is as follows: firstly heating from room temperature to 450-500 ℃ within 40-60min, controlling the pressure of unit area to be 0.1-0.3 MPa, then heating from 450-500 ℃ to 750-800 ℃ within 60-90 min, controlling the pressure of unit area to be 0.5-0.8 MPa, then heating from 750-800 ℃ to 900-950 ℃ within 70-90 min, controlling the pressure of unit area to be 0.8-1.1 MPa, then keeping the temperature at 900-950 ℃ for 2-4 h, controlling the pressure of unit area to be 0.8-1.1 MPa, finally discharging the furnace after cooling to 100 ℃ by water cooling, and controlling the pressure of unit area to be 0.5-0.8 MPa in the process of cooling by water cooling. The sintering process uses hydrogen as a protective gas.
In the preferred sintering process, the temperature is quickly raised to 450-500 ℃, impurities such as kerosene and the like are volatilized, and the base material is softened at high temperature, which is the standard for the subsequent sintering process; then reducing the heating rate, slowly heating to 750-800 ℃ to ensure that tin can be fully dissolved in the copper matrix, and the atoms move in an accelerated way to homogenize the components of the product; then the temperature is slowly increased to 900-950 ℃, so that the copper-tin alloy forms solid solution, the matrix is strengthened, and the pressure is increased, thereby being beneficial to the molecular motion and the mechanical alloying process. After the temperature rise is finished, the temperature is kept at 900-950 ℃ to ensure that all raw material components are fully activated and molecules are fully reacted, and the densification sintering process is finished. And after the heat preservation is finished, rapidly cooling by water cooling to obtain the required crystalline phase. By adopting the sintering mode, the full reaction among the components with different phase transition temperatures can be ensured, and the consistency of the material performance is improved. Inadequate sintering of the material can be caused by improper sintering process procedures, and the strength, hardness, density, frictional wear and other properties of the material are affected.
In the actual operation process, the water cooling process comprises the steps of hanging the heating body of the bell jar furnace, replacing the cooling cover, applying pressure of 0.5-0.8 MPa per unit area, and then spraying water to the sintering inner cover for cooling.
The invention also provides application of the copper-based powder metallurgy friction material, and the copper-based powder metallurgy friction material is used for a wind turbine generator braking device.
In the actual operation process, equipment such as a lathe, a grinding machine and the like is used for carrying out subsequent treatment on the sintered product, so that the appearance, the size and the surface treatment of the product meet the requirements.
Advantageous effects
In the prior art, in the braking process, the friction block falls off from the support steel backing due to thermal stress caused by large difference of thermal expansion coefficients of the temperature rise rate block, the friction layer material and the support steel backing. Therefore, the powder friction material with the double-layer structure of the friction layer material and the binding layer material is adopted, and the binding layer material is combined with the support steel back, so that the thermal expansion difference between the friction layer material and the support steel back can be relieved under the action of high-temperature impact force and shearing force, the binding force between the friction layer material and the support steel back is effectively improved, and the friction block is prevented from falling off.
The friction layer material of the invention uses tin powder and copper powder to form copper-tin alloy, thus improving the strength of the matrix; the high-melting-point iron and silica sand are used as friction components, and the high hardness and good thermal stability of the high-melting-point iron and silica sand are utilized to ensure that the friction material of the formula still keeps stable mechanical strength and excellent friction and wear properties under the harsh condition of braking, and the high-melting-point molybdenum powder can effectively improve the oxidation resistance of the material and prevent copper oxidation of a metal matrix under the high-energy and high-temperature conditions; meanwhile, two kinds of graphite with different configurations are used as the lubricating agent, incompatibility with other lubricating components is reduced, and granular graphite and strip-shaped crystalline flake graphite with different shapes can be organically combined, so that a three-dimensional reinforcing effect is achieved, the interface binding force of nonmetal and metal materials is improved, and the use strength of the materials is guaranteed. The invention adopts a double-layer material formula, and on the premise of not influencing the friction and wear properties of the friction material, the increased binding material layer can improve the binding force between the friction material and the supporting steel back, thereby effectively solving the problem of the falling of the friction block.
Compared with the copper-based powder metallurgy friction material in the prior art, the friction layer material adopts fewer raw material types, the inventor finds that excessive raw materials are easy to cause stress on the interface between the material components, and easily cause thermal stress release, cracks and recession in the high-temperature use process of the product. In the invention, by using tin powder with proper content, copper-tin alloy is formed in the sintering process, and the high-temperature performance is effectively improved. Meanwhile, the iron powder is used as a matrix for reinforcement, and has obvious reinforcement effect on copper base. The friction agent adopts silica sand, has high hardness and high melting point, is embedded in the matrix in an amorphous state, is not easy to oxidize and decompose, and ensures the friction stability in a high-energy state. The lubricating component adopts molybdenum powder and graphite with various forms. Molybdenum powder is directly used without molybdenum disulfide, so that adverse effects of S elements decomposed by molybdenum disulfide on a matrix are effectively avoided, and meanwhile, the molybdenum powder can form solid solution strengthening with iron powder besides the lubricating effect, and the matrix performance is enhanced; and graphite in various forms is adopted and used as a high-melting-point substance, so that sufficient lubrication and stable coefficient in the friction process are ensured.
In the preparation process, the components are fully and uniformly mixed, reasonably crushed and uniformly distributed through the material mixing process. The sectional type pressure sintering process is adopted, so that the components are fully reacted, and the combination between the metal and nonmetal components is good. The product has the advantages of uniform distribution of all components, high mechanical alloying degree and excellent performance.
Compared with the existing powder metallurgy friction material, the powder metallurgy friction material formula has the advantages that the material formula design is redesigned, the material manufacturing process is simplified, and the material manufacturing cost is reduced. The prepared wind power brake shoe product has stable performance and excellent friction performance.
Drawings
FIG. 1 is a schematic representation of a copper-based friction material provided by the present invention.
Detailed Description
In examples 1 to 3:
the average particle size of the granular graphite is 50 meshes, and the average particle size of the flake graphite is 80 meshes.
The copper powder is electrolytic copper powder, and the particle size of the copper powder is 45-75 mu m.
The iron powder is reduced iron powder, and the particle size of the iron powder is 56-106 mu m.
The particle size of the tin powder is 45-75 mu m.
The granularity of the molybdenum powder is 2-5 mu m.
The grain diameter of the silica sand is 150-300 mu m.
Example 1
The friction layer material comprises the following main raw materials in percentage by mass: 70% of copper powder, 7% of iron powder, 6% of granular graphite and 5% of flake graphite. 2% of molybdenum powder, 5% of silica sand and 5% of tin powder.
The auxiliary materials are as follows: aviation kerosene, the addition of which is 1.5% of the total mass of the main raw materials.
The bonding layer material comprises the following raw materials in percentage by mass: 80% of copper powder, 10% of iron powder and 10% of tin powder.
The preparation process comprises the following steps:
mixing materials:
firstly, weighing tin powder according to the formula of a bonding layer material, passing the tin powder through a 100-mesh screen, mixing the tin powder with copper powder to obtain a mixture A, adding iron powder into the mixture A, manually premixing the mixture, placing the mixture in a mixer, and mixing the mixture for 1 hour at a rotating speed of 80 revolutions per minute to obtain a bonding layer mixture; and then massaging the formula of the friction layer material, weighing tin powder, passing through a 100-mesh screen, mixing with copper powder, passing through a 40-mesh screen to obtain a mixture C, adding iron powder, molybdenum powder and silica sand into the mixture C, mixing to obtain a mixed powder D, uniformly mixing granular graphite, flake graphite and kerosene to obtain a mixed powder E, manually premixing the mixed powder D and the mixed powder E to obtain a mixture F, pouring the mixture F into a mixer, and mixing at the rotating speed of 80 r/min for 5 hours to obtain a friction layer mixture.
Profiling:
the method comprises the steps of screening a bonding layer mixture into a mold cavity through a screen, pouring a friction layer mixture into the mold cavity, pressing at 300Mpa for 2s, and performing compression molding to obtain a double-layer green compact containing a bonding material layer and a friction material layer.
And (3) sintering:
and (3) after the pressed compact binding material layer is attached to the support steel back, carrying out sectional type pressure sintering, and taking hydrogen as a protective gas in the whole process.
(1) Stage (2): the temperature is between room temperature and 450 ℃, the pressure per unit area is 0.1MPa, and the temperature rise time is 60min;
(2) stage (2): 450-780 ℃, the pressure per unit area is 0.6MPa, and the heating time is 80min;
(3) stage (2): 780-920 ℃, the pressure per unit area is 1.0MPa, and the heat preservation time is 70min;
(4) stage (2): 920 ℃, the pressure per unit area is 1.0MPa, and the heat preservation time is 150min;
(5) stage (2): and (3) cooling to below 100 ℃ by adopting a water cooling mode with the unit area pressure of 1.0MPa to obtain the powder metallurgy friction material.
The friction material obtained in example 1 was subjected to an MM-3000 frictional wear tester at a test speed of 6500rpm and a test inertia of 0.25kg · m 2 The test braking pressure is 0.8MPa, the braking times are 10 times, the average value of the last 5 times is taken, and the results are shown in the following table 1.
Example 2
The friction layer material comprises the following main raw materials in percentage by mass: 68% of copper powder, 7% of iron powder, 6% of granular graphite and 5% of flake graphite. 4% of molybdenum powder, 5% of silica sand and 5% of tin powder.
The auxiliary materials are as follows: aviation kerosene, the addition of which is 1.5% of the total mass of the main raw materials.
The bonding layer material comprises the following raw materials in percentage by mass: 80% of copper powder, 10% of iron powder and 10% of tin powder.
The preparation process comprises the following steps:
mixing materials:
firstly, weighing tin powder according to the formula of a bonding layer material, passing the tin powder through a 100-mesh screen, mixing the tin powder with copper powder to obtain a mixture A, adding iron powder into the mixture A, manually premixing the mixture, placing the mixture in a mixer, and mixing the mixture for 1 hour at a rotating speed of 80 revolutions per minute to obtain a bonding layer mixture; and then massaging the formula of the friction layer material, weighing tin powder, passing through a 100-mesh screen, mixing with copper powder, passing through a 40-mesh screen to obtain a mixture C, adding iron powder, molybdenum powder and silica sand into the mixture C, mixing to obtain a mixed powder D, uniformly mixing granular graphite, flake graphite and kerosene to obtain a mixed powder E, manually premixing the mixed powder D and the mixed powder E to obtain a mixture F, pouring the mixture F into a mixer, and mixing at the rotating speed of 80 r/min for 5 hours to obtain a friction layer mixture.
Profiling:
and (3) screening the bonding layer mixture into a mold cavity through a screen, pouring the friction layer mixture into the mold cavity, pressing at 300Mpa for 2s, and performing compression molding to obtain a double-layer green compact containing the bonding material layer and the friction material layer.
And (3) sintering:
and (3) after the pressed compact bonding material layer is attached to the support steel backing, carrying out sectional type pressure sintering, and adopting hydrogen as a protective gas in the whole process.
(1) Stage (2): the temperature is between room temperature and 450 ℃, the pressure per unit area is 0.1MPa, and the temperature rise time is 60min;
(2) stage (2): 450-780 ℃, the pressure per unit area is 0.6MPa, and the heating time is 80min;
(3) stage (2): 780-920 ℃, 1.0MPa of unit area pressure and 70min of heat preservation time;
(4) stage (2): 920 ℃, the pressure per unit area is 1.0MPa, and the heat preservation time is 150min;
(5) stage (2): and (3) cooling to below 100 ℃ by adopting a water cooling mode with the unit area pressure of 1.0MPa to obtain the powder metallurgy friction material.
The friction material obtained in example 1 was subjected to an MM-3000 frictional wear tester at a test speed of 6500rpm and a test inertia of 0.25kg · m 2 The test braking pressure is 0.8MPa, the braking times are 10 times, the average value of the last 5 times is taken, and the results are shown in the following table 1.
Example 3
The friction layer material comprises the following main raw materials in percentage by mass: 66% of copper, 8% of iron powder, 6% of granular graphite, 5% of flake graphite, 5% of molybdenum powder, 4% of silica sand and 6% of tin powder.
The auxiliary materials are as follows: aviation kerosene, the addition of which is 1.5% of the total mass of the main raw materials.
The bonding layer material comprises the following raw materials in percentage by mass: 80% of copper powder, 10% of iron powder and 10% of tin powder.
The preparation process comprises the following steps:
mixing materials:
weighing tin powder according to the formula of a bonding layer material, passing the tin powder through a 100-mesh screen, mixing the tin powder with copper powder to obtain a mixture A, adding iron powder into the mixture A, manually premixing the mixture, placing the mixture in a mixer, and mixing the mixture for 1 hour at a rotating speed of 80 revolutions per minute to obtain a bonding layer mixture; and then massaging the formula of the friction layer material, weighing tin powder, passing through a 100-mesh screen, mixing with copper powder, passing through a 40-mesh screen to obtain a mixture C, adding iron powder, molybdenum powder and silica sand into the mixture C, mixing to obtain a mixed powder D, uniformly mixing granular graphite, flake graphite and kerosene to obtain a mixed powder E, manually premixing the mixed powder D and the mixed powder E to obtain a mixture F, pouring the mixture F into a mixer, and mixing at the rotating speed of 80 r/min for 5 hours to obtain a friction layer mixture.
Profiling:
and (3) screening the bonding layer mixture into a mold cavity through a screen, pouring the friction layer mixture into the mold cavity, pressing at 300Mpa for 2s, and performing compression molding to obtain a double-layer green compact containing the bonding material layer and the friction material layer.
And (3) sintering:
and (3) after the pressed compact bonding material layer is attached to the support steel backing, carrying out sectional type pressure sintering, and adopting hydrogen as a protective gas in the whole process.
(1) Stage (2): the temperature is between room temperature and 450 ℃, the pressure per unit area is 0.1MPa, and the temperature rise time is 60min;
(2) stage (2): 450-780 ℃, the pressure per unit area is 0.6MPa, and the heating time is 80min;
(3) stage (2): 780-920 ℃, the pressure per unit area is 1.0MPa, and the heat preservation time is 70min;
(4) stage (2): 920 ℃, the pressure per unit area is 1.0MPa, and the heat preservation time is 150min;
(5) stage (2): and cooling to below 100 ℃ by adopting a water cooling mode with the unit area pressure of 1.0MPa to obtain the powder metallurgy friction material.
The friction material obtained in example 1 was subjected to an MM-3000 frictional wear tester at a test speed of 6500rpm and a test inertia of 0.25kg · m 2 The test braking pressure is 0.8MPa, the braking times are 10 times, the average value of the last 5 times is taken, and the results are shown in the following table 1.
Comparative example 1
Other conditions were the same as in example 1, replacing 5% of the flake graphite with the particulate graphite.
The friction material obtained in comparative example 1 was put on an MM-3000 frictional wear tester with a test speed of 6500rpm and an inertia of 0.25kg · m 2 The braking pressure is 0.8MPa, the braking times are 10 times, and the average value is obtained, and the results are shown in the following table 1.
Comparative example 2
Other conditions were the same as in example 1, except that iron powder having a particle size of 106 to 150 μm was used instead of iron powder having a particle size of 56 to 106 μm. The friction material obtained in comparative example 2 was put on an MM-3000 frictional wear tester with a test speed of 6500rpm and an inertia of 0.25kg · m 2 The braking pressure was 0.8MPa, the number of times of braking was 10, and the results are shown in Table 1 below.
TABLE 1
| Number of | Coefficient of dynamic friction | Coefficient of stability | Material abrasion mm/surface/times |
| Example 1 | 0.307 | 77％ | 0.0023 |
| Example 2 | 0.294 | 71％ | 0.0033 |
| Example 3 | 0.301 | 69％ | 0.0030 |
| Comparative example 1 | 0.202 | 59％ | 0.0060 |
| Comparative example 2 | 0.277 | 56％ | 0.0053 |
| The use requirement | ≥0.25 | / | ≦0.0040 |
Claims (10)
1. A copper-based powder metallurgy friction material is characterized in that: the powder metallurgy friction material is formed by laminating a friction layer material and a bonding layer material; the friction layer material is prepared from main raw materials and auxiliary materials, wherein the main raw materials comprise the following components in percentage by mass: 65-72% of copper powder, 6-9% of iron powder, 2-8% of granular graphite, 3-7% of flake graphite, 2-5% of molybdenum powder, 3-6% of silica sand and 2-6% of tin powder. The auxiliary material is kerosene; the bonding layer material comprises the following raw materials in percentage by mass: 70-80% of copper powder, 10-20% of iron powder and 5-15% of tin powder.
2. Copper-based powder metallurgy friction material according to claim 1 or 2, wherein: the average particle size of the granular graphite is 50 meshes, and the average particle size of the flake graphite is 80 meshes.
3. Copper-based powder metallurgy friction material according to claim 1 or 2, wherein:
the copper powder is electrolytic copper powder, and the particle size of the copper powder is 45-75 mu m;
the iron powder is reduced iron powder, and the particle size of the iron powder is 56-106 mu m;
the particle size of the tin powder is 45-75 mu m;
the granularity of the molybdenum powder is 2-5 mu m;
the grain diameter of the silica sand is 150-300 mu m.
4. A copper based powder metallurgy friction material according to claim 1 or 2, wherein:
the kerosene is aviation kerosene, and the addition amount of the kerosene is 1.0-2.0% of the total mass of the main raw materials.
5. The method for preparing a copper-based powder metallurgy friction material according to any one of claims 1 to 4, wherein: preparing raw materials in the bonding layer material according to a designed proportion, mixing to obtain a bonding layer mixture, sieving the bonding layer mixture into a mold cavity through a screen, then preparing main raw materials and auxiliary materials in the friction layer material according to the designed proportion, mixing to obtain a friction layer mixture, pouring the friction layer mixture into the mold cavity to cover the upper part of the bonding layer mixture, placing the mold under a press for compression molding to obtain a double-layer pressed compact containing the bonding layer and the friction layer, and sintering after the bonding layer in the double-layer pressed compact is attached to a support steel back to obtain the powder metallurgy friction material.
6. The method for preparing the copper-based powder metallurgy friction material according to claim 5, wherein the method comprises the following steps: the obtaining process of the bonding layer mixture comprises the following steps: firstly weighing tin powder, passing through a 100-mesh screen, mixing with copper powder to obtain a mixture A, adding iron powder into the mixture A, manually premixing, and mixing in a mixer at a rotating speed of 50-120 r/min for 0.5-1 h.
7. The method for preparing the copper-based powder metallurgy friction material according to claim 5, wherein the method comprises the following steps: the friction layer mixture obtaining process comprises the following steps: weighing tin powder, passing through a 100-mesh screen, mixing with copper powder, sieving with a 40-mesh sieve to obtain a mixture C, adding iron powder, molybdenum powder and silica sand into the mixture C, mixing to obtain a mixed powder D, mixing granular graphite, flake graphite and kerosene to obtain a mixed powder E, manually premixing the mixed powder D and the mixed powder E, and mixing in a mixer at a rotating speed of 50-120 r/min for 3-6 h.
8. The method for preparing the copper-based powder metallurgy friction material according to claim 5, wherein the method comprises the following steps: the pressure of the compression molding is 200-400 Mpa, and the pressure maintaining time is less than or equal to 3s;
the sintering is carried out in a protective atmosphere, the pressure per unit area is 0.4-1.1 MPa, the sintering temperature is 900-950 ℃, and the sintering time is 2-4 h.
9. The method for preparing the copper-based powder metallurgy friction material according to claim 8, wherein the method comprises the following steps: the sintering process comprises the following steps: firstly heating from room temperature to 450-500 ℃ within 40-60min, controlling the pressure of unit area to be 0.1-0.3 MPa, then heating from 450-500 ℃ to 750-800 ℃ within 60-90 min, controlling the pressure of unit area to be 0.5-0.8 MPa, then heating from 750-800 ℃ to 900-950 ℃ within 70-90 min, controlling the pressure of unit area to be 0.8-1.1 MPa, then keeping the temperature at 900-950 ℃ for 2-4 h, controlling the pressure of unit area to be 0.8-1.1 MPa, finally discharging the furnace after cooling to below 100 ℃ by water cooling, and controlling the pressure of unit area to be 0.5-0.8 MPa in the process of cooling by water.
10. Use of a copper based powder metallurgy friction material according to any one of claims 1 to 4, wherein: the copper-based powder metallurgy friction material is used for a wind turbine braking device.
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