CN114210966A - Copper-based powder metallurgy friction material with high stable friction coefficient and preparation method thereof - Google Patents
Copper-based powder metallurgy friction material with high stable friction coefficient and preparation method thereof Download PDFInfo
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- CN114210966A CN114210966A CN202111510085.4A CN202111510085A CN114210966A CN 114210966 A CN114210966 A CN 114210966A CN 202111510085 A CN202111510085 A CN 202111510085A CN 114210966 A CN114210966 A CN 114210966A
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 99
- 239000002783 friction material Substances 0.000 title claims abstract description 74
- 239000010949 copper Substances 0.000 title claims abstract description 71
- 229910052802 copper Inorganic materials 0.000 title claims abstract description 68
- 238000004663 powder metallurgy Methods 0.000 title claims abstract description 54
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- 238000000034 method Methods 0.000 claims abstract description 20
- 239000000463 material Substances 0.000 claims abstract description 18
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 40
- 239000000843 powder Substances 0.000 claims description 39
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 claims description 32
- 238000005245 sintering Methods 0.000 claims description 25
- 238000006722 reduction reaction Methods 0.000 claims description 24
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 22
- 238000010438 heat treatment Methods 0.000 claims description 19
- 229910000604 Ferrochrome Inorganic materials 0.000 claims description 16
- 239000000203 mixture Substances 0.000 claims description 15
- 229910002804 graphite Inorganic materials 0.000 claims description 14
- 239000010439 graphite Substances 0.000 claims description 14
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 12
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 12
- 239000003921 oil Substances 0.000 claims description 12
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 12
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 12
- 229910000831 Steel Inorganic materials 0.000 claims description 10
- 239000010959 steel Substances 0.000 claims description 10
- 238000002156 mixing Methods 0.000 claims description 8
- 238000000498 ball milling Methods 0.000 claims description 7
- 238000007873 sieving Methods 0.000 claims description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 6
- 229910045601 alloy Inorganic materials 0.000 claims description 6
- 239000000956 alloy Substances 0.000 claims description 6
- 239000004615 ingredient Substances 0.000 claims description 6
- 239000010705 motor oil Substances 0.000 claims description 6
- 238000000465 moulding Methods 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 238000005303 weighing Methods 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- 238000004321 preservation Methods 0.000 claims description 5
- 238000003825 pressing Methods 0.000 claims description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 4
- 238000013461 design Methods 0.000 claims description 4
- 239000001257 hydrogen Substances 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 229910000599 Cr alloy Inorganic materials 0.000 claims description 3
- 229910021529 ammonia Inorganic materials 0.000 claims description 3
- 239000000788 chromium alloy Substances 0.000 claims description 3
- DYRBFMPPJATHRF-UHFFFAOYSA-N chromium silicon Chemical compound [Si].[Cr] DYRBFMPPJATHRF-UHFFFAOYSA-N 0.000 claims description 3
- 238000000354 decomposition reaction Methods 0.000 claims description 3
- 239000007789 gas Substances 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- 239000011733 molybdenum Substances 0.000 claims description 3
- 238000005299 abrasion Methods 0.000 abstract description 6
- 230000000694 effects Effects 0.000 abstract description 3
- 239000011159 matrix material Substances 0.000 abstract description 2
- 229910000881 Cu alloy Inorganic materials 0.000 abstract 1
- 230000001050 lubricating effect Effects 0.000 abstract 1
- 239000007787 solid Substances 0.000 abstract 1
- 238000012360 testing method Methods 0.000 description 13
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000011056 performance test Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011651 chromium Substances 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 229920002748 Basalt fiber Polymers 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920002689 polyvinyl acetate Polymers 0.000 description 1
- 239000011118 polyvinyl acetate Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229920003169 water-soluble polymer Polymers 0.000 description 1
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
- B22F3/14—Both compacting and sintering simultaneously
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
- B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
- B22F7/08—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools with one or more parts not made from powder
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D69/00—Friction linings; Attachment thereof; Selection of coacting friction substances or surfaces
- F16D69/02—Composition of linings ; Methods of manufacturing
- F16D69/027—Compositions based on metals or inorganic oxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
- B22F2009/043—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by ball milling
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Inorganic Chemistry (AREA)
- Composite Materials (AREA)
- Materials Engineering (AREA)
- Powder Metallurgy (AREA)
Abstract
A copper-based powder metallurgy friction material with high stable friction coefficient and a preparation method thereof optimize the components and the preparation process of the material, exert the system matching effect of a copper alloy matrix, a lubricating component and a solid component, and have the advantages of high strength, low expansion rate, small deformation and good wear resistance, so that the fluctuation range of the friction coefficient of the friction material is not more than +/-5 percent, and the average friction coefficient is not less than 0.31 and not more than mucpLess than or equal to 0.34, the fluctuation range of the friction coefficient is less than or equal to plus or minus 5 percent of the average friction coefficient, and the linear abrasion loss of the friction material is less than or equal to 0.0038 mm/surface/time. The friction material obtained by the invention has good mechanical strength, is suitable for the working condition that the positive pressure is 2.032KN and the speed is 75m/s, has the advantages of high strength, low expansion rate, small deformation, good wear resistance and the like, does not have the phenomena of friction layer falling, block falling, clamping stagnation, bonding and the like in use, and has stable braking curve and stable and reliable braking process.
Description
Technical Field
The invention relates to the field of powder metallurgy copper-based brake materials, in particular to a copper-based powder metallurgy friction material with a high stable friction coefficient and a preparation method thereof.
Background
Friction materials based on copper in powder metallurgy friction materials are widely used in the fields of machining, transportation, aviation and navigation, etc. due to their excellent product characteristics. However, the existing copper-based friction material still has the problems of low hardness, high wear rate and the like, and particularly has the phenomenon that the fluctuation range of the friction coefficient exceeds +/-10% in the high-speed braking process, so that the braking distance is unstable, and a higher danger coefficient is generated. Therefore, the preparation of the copper-based powder metallurgy friction material with moderate friction coefficient and stable braking has great significance.
The invention with the publication number of CN108907177A provides a copper-based powder metallurgy friction material for braking of high-speed trains, only the preparation process and the material components are described, the friction test result of the material is verified to be single, only the friction coefficient and the average abrasion loss are shown, and the friction stability is not described.
In the invention creation with publication No. CN106641049, a method for manufacturing a brake pad using basalt fiber is disclosed, which can reduce the content of metal components of the brake pad and reduce the noise and abrasion of the brake pad, but does not explain the fluctuation range of the friction coefficient.
In the invention with the publication number of CN106011520A, a dry copper-based powder metallurgy friction material for a clutch is provided, and the stable coefficient of the friction coefficient of the material is 0.59 through friction test verification, but the fluctuation range of the friction coefficient is not indicated.
The invention with the publication number of CN104480342A discloses a corrosion-resistant copper-based brake material with a high friction coefficient and a preparation method thereof, wherein the maximum bearing load of the material is 6.6MPa, the dynamic friction coefficient is 0.32-0.37, but the friction stability is not described.
The invention with the publication numbers of CN109988937A and CN109513939A only provides a preparation process of the copper-based powder metallurgy material, and tests and verifications are not carried out on the prepared copper-based material, so that whether the prepared copper-based material meets the technical requirements of products or not cannot be described.
Disclosure of Invention
In order to solve the friction stability of the copper-based powder metallurgy friction material, the invention provides the copper-based powder metallurgy friction material with a high stable friction coefficient and a preparation method thereof.
The copper-based powder metallurgy friction material with the high stable friction coefficient consists of 48-52% of electrolytic copper powder, 18-24% of reduced iron powder, 12-16% of graphite, 3-6% of ferrochromium alloy, 2-4% of aluminum oxide, 2-4% of molybdenum powder, 2-5% of precipitated barium sulfate and 3-6% of polyvinyl alcohol powder; the percentage is mass percentage.
The Cu content in the electrolytic copper powder is more than or equal to 99.8%. The content of Fe in the reduced iron powder is more than or equal to 98.5 percent. The content of C in the graphite is more than or equal to 99.99 percent; the graphite was in the form of + 80-mesh flake. Cr in the ferrochrome is more than or equal to 60 percent. MoS in the molybdenum powder2Not less than 99 percent. Al in the aluminum oxide2O3Not less than 99 percent. BaSO in the precipitated barium sulfate4More than or equal to 98 percent. (C) of the polyvinyl alcohol powder2H4O)n≥90.5％。
The specific process for preparing the copper-based powder metallurgy friction material with the high stable friction coefficient provided by the invention comprises the following steps:
respectively placing copper powder and iron powder in a reducing furnace for reduction reaction;
when the copper powder is subjected to reduction reaction, the reduction temperature is 380-450 ℃, and the heating rate is 150 ℃/h; when the iron powder is subjected to reduction reaction, the reduction temperature is 620-700 ℃, and the heating rate is 200 ℃/h; the heat preservation time of the reduction reaction of the copper powder and the iron powder is 2-3 h.
and respectively putting the qualified copper powder and the iron powder after reduction into a ball mill for ball milling for 0.5-1 h. Steel ball and copper powder are 10:1, and iron powder is 10: 1. The proportion is weight ratio.
In the ball-milled steel balls, the diameter of a big ball is 96mm, the diameter of a small ball is 40mm, the ratio of the big ball to the small ball is 3:1, and the weight ratio is the weight ratio.
And step 3, drying:
placing graphite powder, molybdenum powder, silicon-chromium alloy and barium sulfate powder into an oven in a classified mode, heating the oven to 120-150 ℃, and preserving heat for 3.0-6.0 hours to remove water in the various powders.
The temperature rise time of the oven is 30 min.
And 4, sieving:
sieving the dried ferrochrome powder, graphite powder, barium sulfate and aluminum oxide powder respectively, and taking-200 meshes of ferrochrome powder, +80 meshes of graphite powder, -400 meshes of barium sulfate powder and-100 meshes of aluminum oxide powder for later use.
weighing electrolytic copper powder, reduced iron powder, graphite, ferrochrome, aluminum oxide, molybdenum powder, precipitated barium sulfate and polyvinyl alcohol powder in sequence according to the mass percentage, and mixing the weighed materials and mixed oil in a double-cone mixer at the fighting speed of 40-50 r/min for 20-24 h; and obtaining a mixture.
The ratio of the sum of all the ingredients to the mixed oil is 1: 10; the proportion is weight ratio. Wherein the weight unit of the ingredients is kg, and the weight unit of the mixed oil is ml. The mixed oil is a mixture of gasoline and engine oil; the gasoline comprises the following components: 1:1 of engine oil; the proportion is weight ratio
Step 6, pressing:
weighing the obtained mixture according to the design requirements of the product, pouring the mixture into a mold, strickling and performing cold press molding to obtain a plurality of materials with the density of 5.8-6.5 g/cm3The compact of the copper-based powder metallurgy friction material.
In the cold press molding, the pressure born by the pressed compact of the iron-based powder metallurgy friction material in unit area is 500-600 MPa, and the pressure maintaining time is 10 s.
And 7, sintering:
and respectively assembling the obtained pressed compact of each copper-based powder metallurgy friction material and the steel backing into an assembly. And (4) putting the stacked assembly parts into a pressure sintering furnace for sintering to obtain the copper-based powder metallurgy friction material.
During sintering, heating the pressurized sintering furnace to 120 ℃ at the speed of 5 ℃/min under the condition of introducing hydrogen or ammonia decomposition gas, and preserving heat for 1.5-2 h; after the heat preservation is finished, heating to 700 ℃ at the speed of 2 ℃/min, and preserving the heat for 1.5-2 h; continuously heating to the sintering temperature of 860-890 ℃ at the speed of 5 ℃/min, pressurizing to the sintering pressure of 0.5-0.7/MPa, and maintaining the pressure and the temperature for 3-5 h. After sintering, water is cooled to below 60 ℃ for pressure relief, and the product is discharged.
The hardness of the obtained copper-based powder metallurgy friction material is 35-42 HRF, the average friction coefficient is 0.31-0.34, the fluctuation range of the friction coefficient is 3.03-4.61, and the wear rate is 0.0024-0.0038 mm/surface.
The invention develops the copper-based powder metallurgy friction material with the fluctuation range of the friction coefficient not more than +/-5 percent, certain strength and high stable friction coefficient by adjusting the formula of the copper-based powder metallurgy friction material. The average friction coefficient of the friction material is more than or equal to 0.31 mucpLess than or equal to 0.34, the fluctuation range of the friction coefficient is less than or equal to plus or minus 5 percent of the average friction coefficient, and the linear abrasion loss of the friction material is less than or equal to 0.0038 mm/surface/time.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention scientifically designs various components of the material by utilizing a powder metallurgy preparation technology, and gives the proportioning of various raw materials of the copper-based powder metallurgy friction material and process schemes and parameters in the whole production process of raw material reduction, ball milling, drying, sieving, proportioning, mixing, pressing, sintering and the like in detail.
2. The invention provides a copper-based powder metallurgy friction material with high stable friction coefficient and a preparation method thereof, wherein the copper-based powder metallurgy friction material has good mechanical strength and is suitable for working conditions with positive pressure of 2.032KN and speed of 75 m/s.
3. The powder metallurgy copper-based friction material manufactured according to the invention has the advantages of high strength, low expansion rate, small deformation, good wear resistance and the like. When the friction pair consisting of the brake part with the friction layer thickness less than 5mm and the 30CrMnSi (HRC34-42) steel material prepared from the powder metallurgy copper-based friction material is used under the condition of 75m/s, the friction coefficients can reach 0.31 to mucpLess than or equal to 0.34, the fluctuation range of the friction coefficient is not more than +/-5 percent of the average friction coefficient, and the linear abrasion loss is less than or equal to 0.0038 mm/surface/time. As shown in FIG. 3, it can be seen from the figure that under a certain pressure and rotation speed, when the prepared copper-based friction material and the friction pairing material form good friction contact, the friction coefficient trend of the copper-based friction material is relatively stable, the fluctuation range is not more than +/-5% of the average friction coefficient, and the technical requirements of products are met.
4. The friction material manufactured according to the invention has no phenomena of friction layer falling, block falling, clamping stagnation, bonding and the like in the friction process, and has stable curve and stable and reliable braking.
5. The invention has the beneficial effect that the polyvinyl alcohol is a water-soluble polymer which is not polymerized by monomers but obtained by hydrolyzing polyvinyl acetate. The polymer has stable chemical property, does not influence the structure of the copper-based friction material, and has the characteristic of easy volatilization under the high temperature condition, so that pores in the structure are uniformly distributed.
6. The invention has the advantages that the polyvinyl alcohol in the pressed compact is effectively removed and a certain amount of air holes are formed in a mode of continuously heating and then preserving heat, and the air holes can effectively accelerate the diffusion and the fluidity of copper under the high-temperature condition, so that the copper is more uniformly distributed in the friction material, and the stability in the braking process is improved. As shown in FIG. 2, the copper-based matrix is tightly connected with other components, and certain pores exist, so that the thermal stability of the copper-based friction material in the friction process is improved.
Drawings
FIG. 1 shows a sample of a copper-based friction material obtained according to the present invention.
FIG. 2 is an SEM image of the copper-based friction material obtained by the present invention.
FIG. 3 shows the inertia of a sample made of the copper-based powder metallurgy friction material obtained by the invention at 0.05 Kg.m2A friction and wear performance test curve measured under the forward pressure of 2.032KN, the radius of 0.032m and the rotating speed of 8061 rpm; in the figure, curve 1 is the friction coefficient curve measured with the braking time, curve 2 is the rotation speed curve measured with the braking time, and curve 3 is the forward pressure curve given during braking.
FIG. 4 shows the surface of a copper-based friction material sample after a friction test.
Fig. 5 is a flow chart of the present invention.
Detailed Description
The invention relates to a copper-based powder metallurgy friction material with a high stable friction coefficient, which consists of 48-52% of electrolytic copper powder, 18-24% of reduced iron powder, 12-16% of graphite, 3-6% of ferrochrome alloy, 2-4% of aluminum oxide, 2-4% of molybdenum powder, 2-5% of precipitated barium sulfate and 3-6% of polyvinyl alcohol powder, wherein the percentages are mass percentages.
The invention specifically describes the technical scheme through 4 embodiments. The compositions of the examples are shown in Table 1:
the components of each embodiment example provided by the invention are shown in the table 1, wherein the content of each component is mass percent (%).
TABLE 1
The content of Cu in the electrolytic copper powder is more than or equal to 99.8%, and the execution standard is GB/T5246-2007.
The content of Fe in the reduced iron powder is more than or equal to 98.5 percent, and the execution standard is GB/T4136-94.
The content of C in the graphite is more than or equal to 99.99 percent, and the execution standard is GB/T3518-95. The graphite was in the form of + 80-mesh flake.
Cr in the ferrochrome alloy is more than or equal to 60 percent, and the execution standard is GB/T5683-
MoS in the molybdenum powder2And the execution standard is GB/T23271-2009.
Al in the aluminum oxide2O3And the execution standard is GB/T11200.2-2008.
BaSO in the precipitated barium sulfate4More than or equal to 98 percent, and the execution standard is GB/T2899-2008.
(C) of the polyvinyl alcohol powder2H4O) n is more than or equal to 90.5 percent, and the standard GB/T19001-2016 is implemented.
The invention also provides a method for preparing the copper-based powder metallurgy friction material.
The specific process for preparing the copper-based powder metallurgy friction material comprises the following steps:
And obtaining the reduced copper powder and the reduced iron powder. The qualified copper powder is rose-red sponge-shaped, and the iron powder is silver-gray sponge-shaped.
The reduction temperature process parameters of the examples provided by the invention are shown in table 2:
TABLE 2
The steel ball comprises a big ball and a small ball. The diameter of the big ball is 96mm, the diameter of the small ball is 40mm, and the ratio of the big ball to the small ball is 3:1, wherein the weight ratio is the weight ratio.
And step 3, drying: placing graphite powder, molybdenum powder, silicon-chromium alloy and barium sulfate powder into an oven in a classified mode, heating the oven to 120-150 ℃, and preserving heat for 3.0-6.0 hours to remove water in the various powders.
The temperature rise time of the oven is 30 min.
The drying process parameters of the embodiments provided by the invention are shown in table 3:
TABLE 3
And 4, sieving: sieving the dried ferrochrome powder, graphite powder, barium sulfate and aluminum oxide powder respectively, and taking-200 meshes of ferrochrome powder, +80 meshes of graphite powder, -400 meshes of barium sulfate powder and-100 meshes of aluminum oxide powder for later use.
The rotating speed of the double-cone mixer is 40-50 r/min.
The ratio of the sum of all the ingredients to the mixed oil is 1: 10; the proportion is weight ratio. Wherein the weight unit of the ingredients is kg, and the weight unit of the mixed oil is ml.
The mixed oil is a mixture of gasoline and engine oil; the gasoline comprises the following components: 1:1 of engine oil; the proportion is weight ratio.
TABLE 4
| Examples | 1 | 2 | 3 | 4 |
| |
20 | 22 | 23 | 24 |
| Rotating speed r/min of mixer | 40 | 43 | 46 | 50 |
Step 6, pressing: weighing the obtained mixture according to the design requirements of the product, pouring the mixture into a mold, leveling the mixture by using a leveling device, and carrying out cold press molding on the mixture on a 5000KN hydraulic press to obtain the product with the density of 5.8-6.5 g/cm3The compact of the copper-based powder metallurgy friction material. In the cold press molding, the pressure born by the unit area of the pressed compact of the iron-based powder metallurgy friction material is 500-600 MPa, and the pressure maintaining time is 10 s. And obtaining a plurality of compacts of the copper-based powder metallurgy friction material.
The pressing process parameters for each example proposed by the present invention are shown in table 5:
TABLE 5
| Examples | 1 | 2 | 3 | 4 |
| Pressure MPa | 500 | 530 | 550 | 600 |
| Dwell time s | 10 | 10 | 10 | 10 |
| Density g/cm3 | 5.8 | 6.0 | 6.2 | 6.5 |
And 7, sintering: and respectively assembling the obtained pressed compact of each copper-based powder metallurgy friction material and the steel backing into an assembly. The components are stacked to form a column according to the prior art and are separated from each other by graphite spacers.
And (4) loading the stacked assembly into a pressure sintering furnace for sintering.
And (3) heating the pressure sintering furnace to 120 ℃ at a speed of 5 ℃/min under the condition of introducing hydrogen or ammonia decomposition gas, preserving heat for 1.5-2 h, heating to 700 ℃ at a speed of 2 ℃/min, preserving heat for 1.5-2 h, heating to the sintering temperature of 860-890 ℃ at a speed of 5 ℃/min, pressurizing to the sintering pressure of 0.5-0.7/MPa, and preserving pressure and heat for 3-5 h. And after sintering, cooling the copper-based powder metallurgy friction material with water to below 60 ℃, releasing the pressure, and discharging the copper-based powder metallurgy friction material out of the furnace to obtain the copper-based powder metallurgy friction material.
The sintering process parameters for each example proposed by the present invention are shown in table 6:
TABLE 6
In order to verify the effect of the invention, the invention simulates specific working conditions and tests are carried out to verify the effect of the invention.
The testing machine is an MM-3000 type friction and wear performance testing stand; the specification of a sample of the friction material product is 21cm ═ S2R is 0.032m, where S is the surface area of the sample and r is the radius of the pattern; the dual material is 30CrMnSi, and the hardness is HRF 26-32.
The test conditions are as follows: friction material product J is 0.05 kg.m2F2.03 KN, N8061 rpm; wherein J is inertia, F is forward pressure, and N is the testing machine rotational speed. The test environment was a dry environment.
The test results are as follows: by performing a frictional wear performance test on an MM-3000 type frictional wear performance test bed, the inertia of a sample made of the copper-based friction material obtained by the invention is 0.05 kg.m2Under the friction test conditions of forward pressure of 2.032KN and rotation speed of 8061rpm, the average friction coefficient of the copper-based friction material is between 0.31 and 0.34, the fluctuation range of the friction coefficient is not more than +/-5 percent, and the absorbed kinetic energy Ws per unit area is not less than 1260.65J/cm2The average braking distance s is less than or equal to 116.32m, the friction braking time s is less than or equal to 2.89s, and the linear abrasion loss of the friction material is less than or equal to 0.0038 mm/surface.times, thereby meeting the technical requirements of products and being applicable to batch industrial production.
FIG. 4 is a surface of a copper-based friction material sample after a friction test. The surface of the copper-based friction material is complete, the phenomena of surface layer stripping, block dropping, clamping stagnation, bonding and the like do not occur, and the product performance is stable.
The main physical and mechanical properties of the copper-based powder metallurgy friction material produced according to the formula in each example are shown in the following table 7:
TABLE 7
| Examples | Hardness HRF | Average coefficient of friction | Fluctuation range of friction coefficient% | The wear rate is mm/ |
| 1 | 35 | 0.31～0.33 | 3.12 | 0.0038 |
| 2 | 37 | 0.32～0.34 | 3.03 | 0.0035 |
| 3 | 42 | 0.31～0.34 | 4.61 | 0.0024 |
| 4 | 40 | 0.31～0.34 | 4.61 | 0.0028 |
Claims (10)
1. The copper-based powder metallurgy friction material with the high stable friction coefficient is characterized by consisting of 48-52% of electrolytic copper powder, 18-24% of reduced iron powder, 12-16% of graphite, 3-6% of ferrochrome alloy, 2-4% of aluminum oxide, 2-4% of molybdenum powder, 2-5% of precipitated barium sulfate and 3-6% of polyvinyl alcohol powder; the percentage is mass percentage.
2. Copper-based powder metallurgy friction material with high stable friction coefficient according to claim 1, wherein the content of Cu in the electrolytic copper powder is more than or equal to 99.8%; the content of Fe in the reduced iron powder is more than or equal to 98.5 percent; the content of C in the graphite is more than or equal to 99.99 percent; the graphite is in a + 80-mesh scaly shape; cr in the ferrochrome is more than or equal to 60 percent; MoS in the molybdenum powder2More than or equal to 99 percent; al in the aluminum oxide2O3More than or equal to 99 percent; BaSO in the precipitated barium sulfate4More than or equal to 98 percent; (C) of the polyvinyl alcohol powder2H4O)n≥90.5％。
3. The preparation method of the copper-based powder metallurgy friction material with the high stable friction coefficient is characterized by comprising the following specific steps:
step 1, reduction of copper powder and iron powder:
respectively placing copper powder and iron powder in a reducing furnace for reduction reaction;
step 2, ball milling:
respectively putting the qualified copper powder and the iron powder after reduction into a ball mill for ball milling for 0.5-1 h; steel ball, copper powder, iron powder, 10: 1; the proportion is weight ratio;
and step 3, drying:
placing graphite powder, molybdenum powder, silicon-chromium alloy and barium sulfate powder into an oven in a classified manner, heating the oven to 120-150 ℃, and preserving heat for 3.0-6.0 h to remove water in the powder;
the temperature rise time of the oven is 30 min;
and 4, sieving:
sieving the dried ferrochrome powder, graphite powder, barium sulfate and aluminum oxide powder respectively, and taking-200-mesh ferrochrome powder, + 80-mesh graphite powder, -400-mesh barium sulfate powder and-100-mesh aluminum oxide powder for later use;
step 5, batching and mixing:
weighing electrolytic copper powder, reduced iron powder, graphite, ferrochrome, aluminum oxide, molybdenum powder, precipitated barium sulfate and polyvinyl alcohol powder in sequence according to the mass percentage, and mixing the weighed materials and mixed oil in a double-cone mixer at the fighting speed of 40-50 r/min for 20-24 h; obtaining a mixture;
step 6, pressing:
weighing the obtained mixture according to the design requirements of the product, pouring the mixture into a mold, strickling and performing cold press molding to obtain a plurality of materials with the density of 5.8-6.5 g/cm3The compact of the copper-based powder metallurgy friction material;
and 7, sintering:
respectively assembling the obtained pressed compact of each copper-based powder metallurgy friction material and the steel backing into an assembly part; and (4) putting the stacked assembly parts into a pressure sintering furnace for sintering to obtain the copper-based powder metallurgy friction material.
4. The method for preparing the copper-based powder metallurgy friction material with the high stable friction coefficient according to the claim 3, is characterized in that the specific process is as follows: when the copper powder is subjected to reduction reaction, the reduction temperature is 380-450 ℃, and the heating rate is 150 ℃/h; when the iron powder is subjected to reduction reaction, the reduction temperature is 620-700 ℃, and the heating rate is 200 ℃/h; the heat preservation time of the reduction reaction of the copper powder and the iron powder is 2-3 h.
5. The method for preparing the copper-based powder metallurgy friction material with the high stable friction coefficient according to claim 3, wherein the ball-milled steel balls are 96mm in diameter of a large ball, 40mm in diameter of a small ball, and 3:1 in ratio of the large ball to the small ball, wherein the weight ratio is.
6. The method for preparing the copper-based powder metallurgy friction material with the high stable friction coefficient according to the claim 3, wherein, the ratio of the total amount of the ingredients to the mixed oil is 1: 10; the proportion is weight ratio; wherein the weight unit of the ingredients is kg, and the weight unit of the mixed oil is ml.
7. The method for preparing the copper-based powder metallurgy friction material with the high stable friction coefficient according to claim 6, wherein the mixed oil is a mixture of gasoline and engine oil; the gasoline comprises the following components: 1:1 of engine oil; the proportion is weight ratio.
8. The method for preparing the copper-based powder metallurgy friction material with the high stable friction coefficient according to claim 3, wherein in the cold press molding, the pressure born by the pressed compact of the iron-based powder metallurgy friction material per unit area is 500-600 MPa, and the dwell time is 10 s.
9. The method for preparing the copper-based powder metallurgy friction material with the high stable friction coefficient according to the claim 3, wherein in the sintering process, the temperature of a pressurizing sintering furnace is raised to 120 ℃ at the speed of 5 ℃/min under the condition of introducing hydrogen or ammonia decomposition gas, and the temperature is kept for 1.5-2 h; after the heat preservation is finished, heating to 700 ℃ at the speed of 2 ℃/min, and preserving the heat for 1.5-2 h; continuously heating to the sintering temperature of 860-890 ℃ at the speed of 5 ℃/min, pressurizing to the sintering pressure of 0.5-0.7/MPa, and maintaining the pressure and the temperature for 3-5 h; after sintering, water is cooled to below 60 ℃ for pressure relief, and the product is discharged.
10. The method for preparing the copper-based powder metallurgy friction material with the high stable friction coefficient according to claim 3, wherein the hardness of the copper-based powder metallurgy friction material is 35-42 HRF, the average friction coefficient is 0.31-0.34, the fluctuation range of the friction coefficient is 3.03-4.61, and the wear rate is 0.0024-0.0038 mm/surface.
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