CN115233019B - Preparation method, product and application of copper-based brake pad material - Google Patents
Preparation method, product and application of copper-based brake pad material Download PDFInfo
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- CN115233019B CN115233019B CN202210916414.3A CN202210916414A CN115233019B CN 115233019 B CN115233019 B CN 115233019B CN 202210916414 A CN202210916414 A CN 202210916414A CN 115233019 B CN115233019 B CN 115233019B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/0425—Copper-based alloys
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- 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
- B22F3/02—Compacting only
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- 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
- B22F3/10—Sintering only
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- 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
- B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C9/00—Alloys based on copper
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Abstract
The invention discloses a preparation method, a product and application of a copper-based brake pad material, and relates to the technical field of powder metallurgy materials. The method comprises the following steps: step 1, preparing copper and iron into copper-iron alloy powder, and preparing copper and tin into copper-tin alloy powder; step 2, mixing the copper-iron alloy powder and the copper-tin alloy powder serving as main components with a lubricating component, a friction component and an auxiliary component to obtain a mixture; step 3, pressing the mixture into a green body; and 4, carrying out air pressure sintering on the green body to obtain the sintered copper-based brake pad. The method solves the technical problems of poor stability of the friction coefficient, low friction coefficient value (less than 0.5) and poor wear resistance of the conventional copper-based brake pad material, and has the advantages of no pollution, simple process flow and low cost.
Description
Technical Field
The invention relates to the technical field of powder metallurgy materials, in particular to a preparation method, a product and application of a copper-based brake pad material.
Background
With the increasing improvement of living standard and the rapid development of urbanization of people, various vehicles emerge endlessly, the power, the load and the speed of the machine are further improved, and people have higher requirements on safety, environmental protection and comfort while going out conveniently. The brake block is used as a material for absorbing power, is a safe guarantee, and is widely applied to various transportation equipment such as automobiles, motorcycles, bicycles, trains, airplanes and the like.
The copper-based brake pad takes copper as a base body, and is added with base body strengthening components (Fe, ni, mo, ti, sn, zn, P and the like) and friction components (SiO) 2 、A1 2 O 3 SiC, asbestos, metal, zrO 2 Metalloid oxides, carbides, nitrides) and lubricating elements (graphite, moS) 2 、CaF 2 、WS 2 、B 4 C. BN, pb, bi, etc.). Copper as a matrix has good thermal conductivity, and can quickly conduct and dissipate a large amount of heat generated in the friction process. However, because the strength of the copper matrix is low, the strength of the copper-based friction material can be reduced violently by the huge heat generated in the braking process, so that the friction and wear performance of the friction material is reduced, and the service life is shortened. In order to increase the strength of the copper matrix, mechanical or chemical methods (e.g. internal oxidation, codeposition, internal autodeposition) are often used in the prior artMethods and mechanical alloying) to introduce second phase particles into the pure copper to increase the strength of the copper matrix. However, this results in poor contact between the primary particles and a reduction in plasticity of the copper matrix after sintering, thereby reducing the mechanical properties (i.e., hardness and wear resistance) of the brake pad. The solid solution strengthening by using alloy elements is also a simple and effective copper strengthening method, at present, the simplest and most common copper strengthening method is to directly add a second phase into a copper matrix for strengthening, although the method can improve the friction and wear performance of the material under limited temperature and sintering time, the friction coefficient and the wear rate of the material cannot reach ideal states due to low homogenization degree of the alloy.
Therefore, the preparation method of the copper-based brake pad material capable of obtaining the high friction coefficient and the low wear rate is provided, and has important significance for the technical field of the copper-based brake pad.
Disclosure of Invention
The invention aims to provide a preparation method, a product and application of a copper-based brake pad material, which are used for solving the problems in the prior art and enabling the copper-based brake pad material to have high friction coefficient and low wear rate.
In order to achieve the purpose, the invention provides the following scheme:
one of the technical schemes of the invention is a preparation method of a copper-based brake pad material, which comprises the following steps:
and 4, carrying out air pressure sintering on the green body to obtain the copper-based brake pad material.
The copper, iron and tin in the step 1 can be powder or blocks, and both the metal powder and the metal blocks can be smelted and are commercially available and can be obtained through purchasing.
Further, in the step 1, the particle size of the copper-iron alloy powder is 10-50 micrometers; the copper content in the copper-iron alloy powder is 70wt.%, and the iron content is 30wt.%. The copper-iron alloy powder is near-spherical alloy powder.
Further, in the step 1, the particle size of the copper-tin alloy powder is 10-50 microns; the copper content in the copper-tin alloy powder is 90wt.%, and the tin content is 10wt.%. The copper-tin alloy powder is near-spherical alloy powder.
Further, in the step 2, the main components comprise 30-40 parts of copper-iron alloy powder and 15-25 parts of copper-tin alloy powder by mass;
the lubricating component comprises 6-8 parts of graphite powder and 1-3 parts of molybdenum disulfide by mass; the grain diameter of the lubricating component is 80-150 micrometers;
the friction component comprises 3-5 parts of mullite, 1-3 parts of zircon powder, 1-3 parts of titanium carbide and 1-3 parts of silicon nitride in parts by mass; the particle size of the friction component is 100-150 microns;
the auxiliary components comprise 5-10 parts of copper powder by mass; the particle size of the auxiliary component is not more than 10 microns.
Further, in step 3, the pressing specifically comprises: and maintaining the pressure for 2 to 3 seconds under the pressing pressure of 6 to 8 tons per square centimeter.
Further, in step 4, the gas pressure sintering specifically comprises: vacuumizing to 0.1-0.3 Pa, and introducing 0.8-1.2 m 3 Hydrogen per hour and the discharged waste gas are ignited, then the temperature is increased to 860 to 880 ℃ at the speed of 200 to 300 ℃/hour, the temperature is kept for 1 to 1.5 hours, the ignited waste gas is extinguished, inert gas is filled until the pressure reaches 1.3 to 1.5 atmospheric pressures, and then the temperature is kept for 0.5 to 1 hour.
The sintering temperature is too high, on one hand, the sintering temperature exceeds or is close to the melting point of copper, so that the product is deformed, on the other hand, the sintering mechanism and the densification mechanism are completely different, and meanwhile, the cost is increased, and the requirements of energy sources and equipment are wasted. And the sintering temperature is too low, a sintering neck and metallurgical bonding cannot be formed, and the material performance is greatly reduced. The sintering body can not be densified, a bonding phase is extruded or the sintering body is adhered to a tray due to overhigh or overlow pressure, and the proper pressure is found out through a plurality of experiments and is 1.3-1.5 atmospheric pressures.
Further, the inert gas is nitrogen or argon.
Further, step 4 includes a grinding process after sintering.
According to the second technical scheme, the copper-based brake pad material prepared by the preparation method is used.
In the third technical scheme of the invention, the copper-based brake pad material is applied to traffic equipment.
The technical conception of the invention is as follows:
the invention uses copper iron and copper tin alloy powder as main components, which is neither the mixing or mechanical alloying of copper iron tin powder nor the surface coating and plating of composite powder, thus greatly reducing the time required by the mutual diffusion migration of the components during the subsequent sintering and rapidly achieving the effects of alloy homogenization and densification. The addition of a small amount of fine copper powder (auxiliary component) contributes to the improvement of the bonding strength of the sintered body. Moreover, the friction component is added with high-hardness, high-wear-resistance and corrosion-resistance silicon nitride and titanium carbide, so that the wear-resistance of the brake pad material can be better improved.
The brake pad material is obtained by cold pressing and then high-temperature hot-pressing sintering. And (3) performing compression molding by adopting the pressure of 600-800 MPa (keeping the pressure for 2-3 seconds under the compression pressure of 6-8 tons/square centimeter), and obtaining the pressed compact with high density. The pressed compact is placed in a heating furnace and is subjected to air pressure sintering (equivalent to hot isostatic pressing sintering) in an inert protective atmosphere, the purposes of purifying materials and homogenizing sintering can be achieved by sequentially vacuumizing, filling hydrogen and filling inert gas, because the hydrogen has strong reducing capability on one hand, can reduce most metal oxides (iron and copper) and remove impurities and partial oxygen in the mixture, and on the other hand, the hydrogen is light and can be used as carrier gas to take away some media (changed into gas at high temperature) added to the mixture, so that the purpose of washing the furnace is achieved, the inert atmosphere is filled, the safety is achieved, and meanwhile, the effect of isostatic pressing is achieved by utilizing the incompressibility and the easy flowability of the gas, so that the purposes of purifying materials and homogenizing sintering are achieved.
The invention discloses the following technical effects:
the invention takes copper-iron alloy powder and copper-tin alloy powder as a matrix (main component), and prepares the copper-based brake pad material by the powder metallurgy technology, thereby obtaining high friction coefficient and low wear rate.
The method solves the technical problems of poor stability of the friction coefficient, low friction coefficient value (less than 0.5) and poor wear resistance of the conventional copper-based brake pad material, and has the advantages of no pollution, simple process flow and low cost.
The copper-based brake pad material prepared by the invention has the advantages of high friction coefficient, stable friction coefficient, good wear resistance and small heat fading (as can be seen from the data in figure 1, the friction coefficient is reduced slightly along with the temperature rise, the middle part is also increased to a certain extent, the abrasion loss is not changed greatly, and the heat fading is small).
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a graph of friction coefficient and wear rate data for a copper-based brake pad prepared in example 1;
FIG. 2 is a diagram of an atomizing apparatus for preparing Cu-Fe and Cu-Sn alloy powder according to an embodiment of the present invention;
FIG. 3 is a metallographic structure drawing of a copper-based brake pad prepared in examples 1 to 3; wherein (a) represents example 1, (b) represents example 2, and (c) represents example 3;
FIG. 4 is a metallographic structure diagram of the copper-based brake pads prepared in comparative examples 3 and 4; wherein (a) represents comparative example 3 and (b) represents comparative example 4.
Detailed Description
Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.
The "parts" in the present invention are all parts by mass unless otherwise specified.
The raw materials used in the examples of the present invention are all commercially available products and are available from commercial sources unless otherwise specified.
The aviation gasoline used in the embodiment of the invention has a No. 120 grade, and has the characteristics of low impurity content, especially low lead content.
The diagram of the atomization device for preparing the copper-iron and copper-tin alloy powder in the embodiment of the invention is shown in fig. 2.
The invention provides a preparation method of a copper-based brake pad material, which comprises the following steps:
By utilizing the limited solubility between copper and iron, and between copper and tin, mixing iron powder (the grain diameter is 1 mm-1 cm, and the iron block can achieve the same technical effect as the iron powder) and copper powder (the grain diameter is 1 mm-1 cm, and the copper block can achieve the same technical effect as the copper powder) according to the mass ratio of 3: 7. copper powder (the particle size is 1 mm-1 cm, and the copper block can achieve the same technical effect as the copper powder) and tin powder (the particle size is 1 mm-1 cm, and the tin block can achieve the same technical effect as the tin powder) according to the mass ratio of 9:1, respectively putting the powder into a smelting furnace with protective atmosphere (nitrogen or argon), induction heating and melting the powder (forming molten liquid state and preserving heat for 10 to 15 minutes), and then utilizing a traditional atomizing device to obtain the nearly spherical alloy powder of Cu70Fe30 and Cu90Sn10 (the figures represent the mass percentage) with the particle size distribution of 10 to 50 micrometers through inert gas (nitrogen or argon) protection and atomization.
The mass ratio of iron to copper is higher than 3:7, the iron content is too high, the sintering temperature is required to be high, and the key is that the brake feels harder and the comfort level is poor; and less than 3:7, the copper content is higher, the disc sticking phenomenon is easy to happen to the grinding disc, and particularly, the continuous braking effect is greatly reduced or the brake fails at high temperature. The mass ratio of copper to tin is higher than 9:1 is, as in the previous case, less than 9:1 will increase the low melting point tin, resulting in some tin overflow and the presence of tiny tin particles on the surface. The most important is that the alloy powder can promote the rapid densification and the great improvement of the performance of the brake pad material and can reduce the cost of the copper-based brake pad (the content of high-price copper is reduced, and the content of low-price iron is increased). Therefore, in the present invention, it is preferable to set the composition of the CuFe alloy powder to Cu70Fe30 and the composition of the CuSn alloy powder to Cu90Sn10.
Weighing raw materials, main components: 30-40 parts of Cu70Fe30 alloy powder obtained in the step 1 and 15-25 parts of Cu90Sn10 alloy powder; a lubricating component: 6-8 parts of flake graphite powder and 1-3 parts of molybdenum disulfide powder; the grain size of the lubricating component is 80-150 microns; friction component: mullite (Al) 2 O 3 +SiO 2 Mixed powder) 3-5 parts, zircon powder 1-3 parts, titanium carbide 1-3 parts and silicon nitride 1-3 parts; the grain size of the friction component is 100-150 microns; auxiliary components: 5-10 parts of pure copper powder with the particle size not more than 10 microns. All the components are added into a mixer according to the proportion, mixed for 4 to 6 hours at the rotating speed of 100 to 200 revolutions per minute, and aviation gasoline with the total mass of 1 to 2 percent of all the components is added during mixing to obtain a mixture.
The aviation gasoline with the proportion of 1-2% is added, so that the powder with different specific gravities and different thicknesses can be easily and uniformly mixed, the dust raising phenomenon can be avoided, and meanwhile, impurities do not remain in subsequent sintering and are easy to remove.
Calculating the surface area and the volume of each friction material according to a brake pad drawing provided by a user, and calculating the theoretical density (4.5-5.3 g/cm) of the brake pad material 3 ) Calculating the mass of each brake pad material, namely the loading amount, by 90-95 percent of the total weight of the brake pad material;
adjusting the relative position of a female die and a lower punch of the steel pressing die according to the charge amount to enable the volume of a cavity of the die to be filled with the calculated raw materials;
putting the mixture prepared in the step 2 into a steel pressing die, adopting dies with different shapes for brake pads with different requirements, naturally filling the mixture into a die cavity formed by the adjusted stamping and female dies, and scraping redundant raw materials on the surface by using a wood board; and then applying unit pressing pressure of 6-8 tons/square centimeter to the mixture in a steel pressing die through an upper die punch, maintaining the pressure for 2-3 seconds, then unloading the pressure and taking out the mixture to obtain a pressed green body.
Sequentially placing the green bodies pressed in the step 3 in a bell jar type sintering furnace (not only canVacuumizing and filling protective atmosphere in a high-temperature sintering furnace), closing the furnace door, vacuumizing to 0.1-0.3 Pa, and introducing 0.8-1.2 m 3 Hydrogen per hour is ignited to discharge gas, then the temperature is raised to 860 to 880 ℃ at the speed of 200 to 300 ℃/hour, the temperature is kept for 1 to 1.5 hours, argon or nitrogen is filled into a hearth after the ignited waste gas is extinguished until the pressure reaches 1.3 to 1.5 atmospheric pressures, then the temperature is kept for 0.5 to 1 hour, then the furnace is cooled, the pressure is kept until the temperature is reduced to below 200 ℃, then an air valve is closed, a furnace door is opened, and the sintered brake pad material is taken out.
And (4) paving the brake pad materials sintered in the step (4) on a plane grinder in sequence, clamping and then grinding to ensure that the surfaces are uniform (obtaining uniformly-arranged fine plow-shaped grinding marks), meeting the requirement of drawing size and obtaining the copper-based brake pad.
The density of the copper-based brake pad prepared by the method is 4.0-4.8 g/cm 3 (ii) a The average hardness is HV 90-HV 127; the friction coefficient is 0.55-0.72; the wear rate is 2-3.5 multiplied by 10 at 200 DEG C -8 cm 3 /Nm。
The invention also provides the copper-based brake pad material prepared by the method.
The invention also provides application of the copper-based brake pad material in traffic equipment.
Example 1A cylindrical brake pad having a diameter of about 30 mm and a height of 10 mm was prepared
Mixing iron powder and copper powder according to the mass ratio of 3: 7. the mass ratio of the copper powder to the tin powder is 9:1, respectively placing the powder in a smelting furnace with protective atmosphere nitrogen to perform induction heating melting (forming molten liquid state and preserving heat for 10 minutes), and then utilizing a traditional atomizing device to perform atomizing under the protection of inert gas (nitrogen) to obtain nearly spherical alloy powder of Cu70Fe30 and Cu90Sn10 (the figures represent the mass percentage) with the grain diameter distribution of 10-50 micrometers.
Weighing raw materials, main components: step 1 obtaining30 parts of Cu70Fe30 alloy powder and 25 parts of Cu90Sn10 alloy powder; a lubricating component: 6 parts of flake graphite powder and 1 part of molybdenum disulfide powder; the grain size of the lubricating component is 80 microns; friction component: mullite (Al) 2 O 3 +SiO 2 Mixed powder) 3 parts, zircon powder 1 part, titanium carbide 1 part and silicon nitride 3 parts; the particle size of the friction component is 100 microns; auxiliary components: 5 parts of pure copper powder with the particle size of 10 microns. All the components are added into a mixer according to the proportion, mixed for 4 hours at the rotating speed of 100 r/min, and aviation gasoline accounting for 1 percent of the total mass of all the components is added during mixing to obtain a mixture.
According to the drawing size of the brake pad, the surface area (7.07 cm) of the brake pad is calculated 2 ) And volume (7 cm) 3 ) According to the theoretical density of the brake pad material (4.5 g/cm) 3 ) Calculating the mass (30.2 g) of each brake pad material, namely the loading amount;
adjusting the relative position of a female die and a lower punch of the steel pressing die according to the charge amount to enable the volume of a cavity of the die to be filled with the calculated raw materials;
putting the mixture prepared in the step 2 into a steel pressing die, naturally filling the mixture into a die cavity formed by the adjusted stamping and female die, and scraping the redundant raw materials on the surface by using a wood board; then, 42 tons of pressing pressure (unit pressing pressure of 6 tons/square centimeter) is applied to the mixture in a steel pressing die through an upper punch, and the mixture is discharged after pressure maintaining for 2 seconds, so that a pressed green body is obtained.
Placing the green bodies pressed in the step 3 in a bell jar type sintering furnace in sequence, closing a furnace door, vacuumizing to 0.1Pa, and introducing 0.8m 3 Hydrogen per hour is used for igniting the discharged gas, then the temperature is raised to 860 ℃ at the speed of 200 ℃/hour, the temperature is kept for 1.5 hours, argon is filled into a hearth after the ignited waste gas is extinguished until the pressure reaches 1.3 atmospheric pressure, the temperature is kept for 1 hour, then the furnace is cooled, the pressure is kept until the temperature is reduced to below 200 ℃, then an air valve is closed, a furnace door is opened, and the sintered brake pad material is taken out.
And (4) paving the brake pad materials sintered in the step (4) on a plane grinder in sequence, clamping and then grinding to ensure that the surfaces are uniform (obtaining uniformly-arranged fine plow-shaped grinding marks), meeting the requirement of drawing size and obtaining the copper-based brake pad.
The density of the copper-based brake pad prepared in the embodiment is 4.2g/cm 3 (ii) a The average hardness is HV98; the room-temperature friction coefficient is 0.57; the wear rate is 3.2X 10 at 200 DEG C -8 cm 3 Nm, impact toughness 15.5J/cm 2 。
Example 2 preparation of cuboid brake pad with length of 40 mm, width of 20 mm and height of 10 mm step 1 preparation of near-spherical copper-iron and copper-tin alloy powder by gas atomization method
Mixing iron powder and copper powder according to the mass ratio of 3: 7. the mass ratio of the copper powder to the tin powder is 9:1, respectively putting the powder into a smelting furnace with protective atmosphere nitrogen for induction heating and melting (forming molten liquid state and preserving heat for 10 minutes), and then utilizing a traditional atomizing device to obtain nearly spherical alloy powder of Cu70Fe30 and Cu90Sn10 (figures represent mass percent) with the particle size distribution of 10-50 micrometers through inert gas (nitrogen or argon) protection and atomization.
Weighing raw materials, main components: 40 parts of Cu70Fe30 alloy powder obtained in the step 1 and 15 parts of Cu90Sn10 alloy powder; a lubricating component: 6 parts of flake graphite powder and 3 parts of molybdenum disulfide powder; the grain diameter of the lubricating component is 100 micrometers; friction component: mullite (Al) 2 O 3 +SiO 2 Mixed powder) 5 parts, zircon powder 3 parts, titanium carbide 3 parts and silicon nitride 1 part; the particle size of the friction component is 120 microns; auxiliary components: 10 parts of pure copper powder with the particle size of 6 microns. All the components are added into a mixer according to the proportion, mixed for 6 hours at the rotating speed of 200 r/min, and aviation gasoline accounting for 2 percent of the total mass of all the components is added during mixing to obtain a mixture.
Calculating the surface area (8 cm) of each friction material according to the brake pad drawing provided by a user 2 ) And volume (8 cm) 3 ) According to whichTheoretical density of brake pad material (5.3 g/cm) 3 ) Calculating the mass (38.2 g) of each brake pad material, namely the loading amount of the brake pad material;
adjusting the relative position of a female die of the steel pressing die and a lower punch according to the charge amount, so that the calculated raw material can be loaded into the volume of a cavity of the die;
putting the mixture prepared in the step 2 into a steel pressing die, adopting dies with different shapes for brake pads with different requirements, naturally filling the mixture into a die cavity formed by the adjusted stamping and female dies, and scraping redundant raw materials on the surface by using a wood board; then, 64 tons of pressing pressure (unit pressing pressure of 6 tons/square centimeter) is applied to the mixture in a steel pressing die through an upper punch, and pressure is maintained for 3 seconds, then pressure is released and taken out, so that a pressed green body is obtained.
Placing the green bodies pressed in the step 3 in a bell jar type sintering furnace in sequence, closing a furnace door, vacuumizing to 0.3Pa, and introducing 1.2m 3 Hydrogen per hour is used for igniting the discharged gas, then the temperature is raised to 880 ℃ at the speed of 300 ℃/hour, the temperature is kept for 1 hour, argon or nitrogen is filled into a hearth after the ignited waste gas is extinguished until the pressure reaches 1.5 atmospheric pressure, the temperature is kept for 0.5 hour, then the furnace is cooled, the pressure is kept until the temperature is reduced to below 200 ℃, then an air valve is closed, a furnace door is opened, and the sintered brake pad material is taken out.
And (4) paving the brake pad materials sintered in the step (4) on a plane grinder in sequence, clamping and then grinding to ensure that the surfaces are uniform (obtaining uniformly-arranged fine plow-shaped grinding marks), meeting the requirement of drawing size and obtaining the copper-based brake pad.
The density of the copper-based brake pad prepared in the example is 5.0g/cm 3 (ii) a The average hardness is HV110; the room-temperature friction coefficient is 0.62; the wear rate is 2.2X 10 at 200 DEG C -8 cm 3 Nm, impact toughness 20.1J/cm 2 。
Example 3 a brake segment having an outer arc radius of 100 mm, an inner arc radius of 70 mm, a center angle of 60 degrees, and a thickness of 10 mm was prepared
Mixing iron powder and copper powder according to the mass ratio of 3: 7. the mass ratio of the copper powder to the tin powder is 9:1, respectively placing the powder in a smelting furnace with protective atmosphere argon to perform induction heating melting (forming a molten liquid state and keeping the temperature for 15 minutes), and then utilizing a traditional atomizing device to perform atomizing under the protection of inert gas (nitrogen or argon) to obtain nearly spherical alloy powder of Cu70Fe30 and Cu90Sn10 (the figures represent the mass percent) with the particle size distribution of 10-50 micrometers.
Weighing raw materials, main components: 35 parts of Cu70Fe30 alloy powder and 20 parts of Cu90Sn10 alloy powder obtained in the step 1; a lubricating component: 7 parts of flake graphite powder and 2 parts of molybdenum disulfide powder; the grain size of the lubricating component is 150 microns; friction component: mullite (Al) 2 O 3 +SiO 2 Mixed powder) 4 parts, zircon powder 2 parts, titanium carbide 2 parts and silicon nitride 2 parts; the particle size of the friction component is 150 microns; auxiliary components: 8 parts of pure copper powder with the particle size of 3 microns. All the components are added into a mixer according to the proportion, mixed for 5 hours under the condition that the rotating speed is 150 revolutions per minute, and aviation gasoline accounting for 1.5 percent of the total mass of all the components is added during mixing to obtain a mixture.
The surface area of each friction material (8.5 cm) was calculated from the brake pad drawing paper provided by the user 2 ) And volume (8.5 cm) 3 ) According to the theoretical density of the brake pad material (5.0 g/cm) 3 ) Calculating the mass (39.5 g) of each brake pad material, namely the loading amount, according to the 93 percent of the brake pad material;
adjusting the relative position of a female die and a lower punch of the steel pressing die according to the charge amount to enable the volume of a cavity of the die to be filled with the calculated raw materials;
the mixture prepared in the step 2 is arranged in a steel pressing die, the brake pads with different requirements adopt dies with different shapes, the mixture is naturally filled in a die cavity formed by the adjusted punch and the female die, and then a wood board is used for scraping redundant raw materials on the surface; and then 50 tons of pressing pressure (unit pressing pressure of 6 tons/square centimeter) is applied to the mixture in a steel pressing die through an upper punch, and the mixture is unloaded and taken out after pressure maintaining for 3 seconds to obtain a pressed green body.
Placing the green bodies pressed in the step 3 in a bell jar type sintering furnace in sequence, closing a furnace door, vacuumizing to 0.2Pa, and introducing 1.0m 3 Hydrogen per hour is used for igniting exhausted gas, then the temperature is increased to 870 ℃ at the speed of 250 ℃/hour, the temperature is kept for 1.2 hours, argon or nitrogen is filled into a hearth after the ignited waste gas is extinguished until the pressure reaches 1.4 atmospheric pressure, the temperature is kept for 0.7 hour, then the hearth is cooled along with the furnace, the pressure is kept until the temperature is reduced to be below 200 ℃, then an air valve is closed, a furnace door is opened, and the sintered brake pad material is taken out.
And (4) paving the brake pad materials sintered in the step (4) on a plane grinder in sequence, clamping and then grinding to ensure that the surfaces are uniform (obtaining uniformly-arranged fine plow-shaped grinding marks), meeting the requirement of drawing size and obtaining the copper-based brake pad.
The density of the copper-based brake pad prepared in the example is 4.7g/cm 3 (ii) a The average hardness is HV103; the room temperature friction coefficient is 0.60; the wear rate is 2.8X 10 at 200 DEG C -8 cm 3 Nm, impact toughness 16.3J/cm 2 。
FIG. 3 is a metallographic structure diagram of the copper-based brake pad prepared in examples 1 to 3; wherein (a) represents example 1, (b) represents example 2, and (c) represents example 3. As can be seen from FIG. 3, the phases are uniformly distributed (dark black is the lubricating component, gray is the main component and the auxiliary component, the friction component is mixed in the lubricating component), and the texture is compact.
Comparative example 1
The only difference from example 1 is that the preparation of Cu90Sn10 in step 1 is omitted, and the Cu90Sn10 in step 2 is replaced by a copper to tin mass ratio of 9:1 (50-100 microns) and tin (50-100 microns).
The density of the copper-based brake pad prepared by the comparative example is 4.3g/cm 3 (ii) a The average hardness is HV77; the room temperature friction coefficient is 0.44; the wear rate is 1.2X 10 at 200 DEG C -7 cm 3 Nm, impact toughness of 10.7J/cm 2 。
Comparative example 2
Only different from example 1 in that the preparation of Cu70Fe30 in step 1 was omitted, and the Cu70Fe30 in step 2 was replaced with 3:7 iron powder (50-100 microns) and copper powder (50-100 microns).
The density of the copper-based brake pad prepared by the comparative example is 4.0g/cm 3 (ii) a The average hardness is HV69; the room temperature friction coefficient is 0.47; the wear rate is 2.2X 10 at 200 DEG C -7 cm 3 Nm, impact toughness of 15.5J/cm 2 。
Comparative example 3
The only difference from example 1 is that the preparation of Cu70Fe30 and Cu90Sn10 in step 1 is omitted, and the Cu70Fe30 in step 2 is replaced by a ratio of iron to copper by mass of 3:7 (50-100 microns) and copper (50-100 microns), replacing Cu90Sn10 with copper and tin in a mass ratio of 9:1 copper powder (50-100 microns) and tin powder (50-100 microns).
The density of the copper-based brake pad prepared by the comparative example is 4.0g/cm 3 (ii) a The average hardness is HV80; the friction coefficient at room temperature is 0.50; the wear rate is 2.0X 10 at 200 DEG C -7 cm 3 Nm, impact toughness of 12.3J/cm 2 . The metallographic structure of the copper-based brake pad prepared in this comparative example is shown in fig. 4 (a).
Comparative example 4
The only difference from comparative example 3 is that the mass ratio of iron powder to copper powder was 0.5.
The metallographic structure of the copper-based brake pad prepared in this comparative example is shown in fig. 4 (b).
Comparing fig. 4 with fig. 3, it can be seen that each phase in fig. 3 is uniformly distributed and has a dense tissue. In FIG. 4, the agglomeration or the pores of the local region exist, the tissue compactness is poor, and the difference between the two is obvious.
The above-described embodiments are only intended to illustrate the preferred embodiments of the present invention, and not to limit the scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims (8)
1. The preparation method of the copper-based brake pad material is characterized by comprising the following steps of:
step 1, preparing copper and iron into copper-iron alloy powder, and preparing copper and tin into copper-tin alloy powder;
step 2, mixing the copper-iron alloy powder and the copper-tin alloy powder serving as main components with a lubricating component, a friction component and an auxiliary component to obtain a mixture;
step 3, pressing the mixture into a green body;
step 4, carrying out air pressure sintering on the green body to obtain the copper-based brake pad material;
the copper content in the copper-iron alloy powder is 70wt.%, and the iron content is 30wt.%;
the copper content in the copper-tin alloy powder is 90%, and the tin content is 10%;
the copper-iron alloy powder and the copper-tin alloy powder are prepared by a gas atomization method;
in step 3, the pressing specifically comprises: keeping the pressure for 2 to 3 seconds under the pressing pressure of 6 to 8 tons per square centimeter;
in step 4, the air pressure sintering specifically comprises the following steps: vacuumizing to 0.1-0.3 Pa, and introducing 0.8-1.2 m 3 Hydrogen per hour and the discharged waste gas is ignited, then the temperature is raised to 860 to 880 ℃ at the speed of 200 to 300 ℃/hour, the temperature is kept for 1 to 1.5 hours, the ignited waste gas is filled with inert gas after being extinguished until the pressure reaches 1.3 to 1.5 atmospheric pressures, and then the temperature is kept for 0.5 to 1 hour;
in the step 2, the main components comprise 30-40 parts of copper-iron alloy powder and 15-25 parts of copper-tin alloy powder by mass; the lubricating component comprises 6-8 parts of graphite powder and 1-3 parts of molybdenum disulfide; the grain size of the lubricating component is 80-150 microns; the friction component comprises 3-5 parts of mullite, 1-3 parts of zircon powder, 1-3 parts of titanium carbide and 1-3 parts of silicon nitride; the particle size of the friction component is 100-150 microns; the auxiliary component comprises 5-10 parts of copper powder.
2. The preparation method of the copper-based brake pad material according to claim 1, wherein in the step 1, the particle size of the copper-iron alloy powder is 10-50 microns.
3. The method for preparing the copper-based brake pad material according to claim 1, wherein in the step 1, the particle size of the copper-tin alloy powder is 10-50 micrometers.
4. The method for preparing the copper-based brake pad material according to claim 1, wherein in the step 2, the particle size of the lubricating component is 80-150 micrometers; the grain diameter of the friction component is 100-150 micrometers; the particle size of the auxiliary component is not more than 10 microns.
5. The method for preparing the copper-based brake pad material according to claim 1, wherein the inert gas is nitrogen or argon.
6. The method for preparing a copper-based brake pad material according to claim 1, wherein the step of grinding is further included after the completion of the gas pressure sintering in the step 4.
7. Copper-based brake pad material prepared by the preparation method according to any one of claims 1 to 6.
8. Use of a copper base brake pad material according to claim 7 in transportation equipment.
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| JPH08253826A (en) * | 1994-10-19 | 1996-10-01 | Sumitomo Electric Ind Ltd | Sintered friction material, composite copper alloy powder used therefor and their production |
| JP4979993B2 (en) * | 2006-06-16 | 2012-07-18 | 三菱電機株式会社 | Contact material and manufacturing method thereof |
| CN106544542B (en) * | 2016-11-10 | 2018-10-02 | 合肥工业大学 | A kind of unleaded Cu-based sliding bearing material and preparation method thereof |
| CN107267800B (en) * | 2017-07-05 | 2019-03-26 | 北京科技大学 | A kind of preparation method of the equally distributed copper base friction material of Fe phase |
| CN109692951B (en) * | 2018-12-20 | 2022-03-01 | 东睦新材料集团股份有限公司 | Method for manufacturing powder metallurgy self-lubricating bearing |
| JP2021011609A (en) * | 2019-07-05 | 2021-02-04 | 昭和電工マテリアルズ株式会社 | Sintered body for friction dampers and method for producing the same |
| CN111360243B (en) * | 2020-04-24 | 2022-04-01 | 长沙迈特锐新材料有限公司 | High-performance self-lubricating copper-based pantograph slide plate material and preparation method thereof |
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