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CN111014692B - Friction material and preparation method and application thereof - Google Patents

Friction material and preparation method and application thereof Download PDF

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Publication number
CN111014692B
CN111014692B CN201911242360.1A CN201911242360A CN111014692B CN 111014692 B CN111014692 B CN 111014692B CN 201911242360 A CN201911242360 A CN 201911242360A CN 111014692 B CN111014692 B CN 111014692B
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China
Prior art keywords
friction material
heat preservation
under
carrying
pressed compact
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CN201911242360.1A
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CN111014692A (en
Inventor
吴佩芳
释加才让
赵尚节
曹静武
程景琳
马成龙
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Beijing Tianrendaohe New Material Co ltd
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Beijing Tianrendaohe New Material Co ltd
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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
    • B22F1/0003—
    • 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
    • B22F3/1003—Use of special medium during sintering, e.g. sintering aid
    • B22F3/1007—Atmosphere
    • 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
    • B22F3/1017—Multiple heating or additional steps
    • B22F3/1028—Controlled cooling
    • 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
    • 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
    • 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
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • 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
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
    • 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
    • F16D2200/00—Materials; Production methods therefor
    • F16D2200/0004—Materials; Production methods therefor metallic
    • F16D2200/0026—Non-ferro
    • 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
    • F16D2200/00—Materials; Production methods therefor
    • F16D2200/0082—Production methods therefor

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Powder Metallurgy (AREA)

Abstract

The invention relates to the technical field of brake materials, in particular to a friction material and a preparation method and application thereof. The preparation method of the friction material provided by the invention comprises the steps of sequentially carrying out proportioning, mixing, pressing and sintering on the raw materials of the friction material, wherein the sintering step comprises the following steps: 1) under the atmosphere of hydrogen and/or nitrogen, carrying out primary heat preservation on the friction material pressed compact at the temperature of 950 plus 1050 ℃ and under the pressure of 2-4MPa for 15-30 min; 2) reducing the temperature of the friction material pressed compact to 750-850 ℃ under 2-4MPa, and carrying out secondary heat preservation for 15-30 min; 3) reducing the temperature of the friction material pressed compact to 550-650 ℃ under 2-4MPa, and carrying out heat preservation for 15-30min for three times; 4) and after the third heat preservation, removing the pressure, and cooling to room temperature to obtain the friction material. The preparation method of the friction material provided by the invention can effectively avoid the problem that the friction coefficient consistency of the friction material is poor due to the expansion of the friction material after pressure unloading under the high-temperature condition.

Description

Friction material and preparation method and application thereof
Technical Field
The invention relates to the technical field of brake materials, in particular to a friction material and a preparation method and application thereof.
Background
The friction material is a key material for forming friction brakes and clutches of aviation, vehicles, machinery and the like. With the development of science and technology, the power, speed and load of the machine are increasingly improved, and the working condition is increasingly severe, so that higher requirements are provided for the comprehensive performance of the friction material, namely that the friction material is required to have stable friction coefficient besides good wear resistance, high strength, good thermal conductivity, corrosion resistance and low noise, so that the vehicle is kept stable at high speed and high pressure.
The existing friction materials are generally of the asbestos type, the semi-metallic type, and the ceramic type. The asbestos type friction material is a friction material which takes asbestos as a base material and phenolic resin as a binder, and because the asbestos type brake block has carcinogenicity, the asbestos type brake block can not only harm human health, but also generate a 'brake atrophy' phenomenon after repeated braking, even brake failure and serious harm to traffic safety, and is eliminated by the market at present; the ceramic type has high manufacturing cost and unstable performance, and is less applied to civil articles. The semimetal type friction material is divided into an iron-based friction material and a copper-based friction material, and the iron-based friction material is high-temperature resistant, can bear larger load, has high mechanical strength and is low in price; however, the wear-resistant coating tends to adhere to the mating surface, and is poor in wear resistance. Compared with an iron-based friction material, the copper-based friction material has good bonding resistance, wear resistance and thermal conductivity, but has small friction coefficient and poor stability of the friction coefficient.
The semimetal-based friction material is mostly prepared by adopting a powder metallurgy technology, and is prepared by taking metal powder as a matrix, adding a proper amount of a friction reducing agent and a proper amount of a friction increasing agent, uniformly mixing, and then performing compression molding or pressure sintering. The existing preparation process of the copper-based powder metallurgy friction material comprises the steps of material preparation → material mixing → pressing → sintering, wherein the sintering process is a key process influencing the material performance. The existing sintering process of the copper-based powder metallurgy friction material mostly adopts sintering under the conditions of high temperature and high pressure, pressure is removed after sintering is finished, and the friction material is directly cooled to room temperature, but the operation easily causes that the friction material expands under the high temperature condition because of pressure unloading so as to influence the stability and consistency of the material.
Disclosure of Invention
The invention aims to solve the problem of poor material stability and consistency caused by pressure unloading in the process of cooling the existing copper-based powder metallurgy friction material after high-temperature and high-pressure sintering is finished, and further provides a friction material and a preparation method and application thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of a friction material comprises the steps of sequentially carrying out proportioning, mixing, pressing and sintering on raw materials of the friction material, wherein the sintering step comprises the following steps:
1) under the atmosphere of hydrogen and/or nitrogen, carrying out primary heat preservation on the friction material pressed compact at the temperature of 950 plus 1050 ℃ and under the pressure of 2-4MPa for 15-30 min;
2) after the primary heat preservation is finished, reducing the temperature of the friction material pressed compact to 850 ℃ at 2-4MPa, and carrying out secondary heat preservation for 15-30min at 2-4MPa and 850 ℃ at 750-;
3) after the secondary heat preservation is finished, reducing the temperature of the friction material pressed compact to 550-650 ℃ under 2-4MPa, and carrying out heat preservation for 15-30min for three times under 2-4MPa and 550-650 ℃;
4) and after the third heat preservation, removing the pressure, and cooling the friction material pressed compact to the room temperature to obtain the friction material.
Preferably, the volume ratio of the hydrogen to the nitrogen is 5:95 to 10: 90.
Preferably, the pressure of the primary heat preservation, the secondary heat preservation and the third heat preservation is equal.
Preferably, the sintering step comprises the steps of:
1) in the atmosphere of hydrogen and nitrogen, carrying out primary heat preservation on a friction material pressed compact at 1000 ℃ and 3MPa for 30min, wherein the volume ratio of hydrogen to nitrogen is 5: 95;
2) after the primary heat preservation is finished, reducing the temperature of the friction material pressed compact to 800 ℃ under 3MPa, and carrying out secondary heat preservation for 30min under 3MPa and 800 ℃;
3) after the secondary heat preservation is finished, reducing the temperature of the friction material pressed compact to 600 ℃ under 3MPa, and carrying out heat preservation for 30min for three times under 3MPa and 600 ℃;
4) and after the third heat preservation, removing the pressure, and cooling the friction material pressed compact to the room temperature to obtain the friction material.
Preferably, the preparation method of the friction material pressed blank comprises the following steps of mixing and blending friction material raw materials to obtain a friction material mixture, and pressing the friction material mixture to obtain the friction material pressed blank, wherein the pressing pressure is 6-15MPa, and the pressing time is 3-5 s.
Preferably, the equipment that the batching step adopted includes the weighing device, the equipment that the compounding step adopted includes the powder compounding device, the powder compounding device includes:
a mixing bin;
the spiral main reamer is arranged in the mixing bin and is driven to rotate along the circumferential direction of the mixing bin;
the auxiliary reamer is arranged on the side part of the spiral main reamer, and the cutter head of the auxiliary reamer is arranged towards the spiral main reamer;
further comprising: with the weighing device that blending bunker is linked together, weighing device includes:
a main storage bin;
the weighing bin is used for weighing materials, the weighing bin is communicated with the main bin through a connecting channel, and a spiral rotating rod is arranged in the connecting channel;
the spiral rotating rod is provided with threads for accommodating materials, a sleeve sleeved and connected with the spiral rotating rod is arranged on the outer side of the spiral rotating rod, and the sleeve and the spiral rotating rod enclose the connecting channel; the spiral rotating rod is driven to rotate, the materials contained in the threads are transferred to a sleeve discharge port from a sleeve feed port of the connecting channel, the sleeve feed port is communicated with the main material bin, and the sleeve discharge port is communicated with the weighing bin.
The invention provides a friction material, which comprises the following raw materials in parts by weight,
55-60 parts of copper powder, 22-28 parts of iron powder, 6-8 parts of ferrochrome powder, 4-6 parts of graphite, 2-4 parts of silicon dioxide, 0.5-1.5 parts of molybdenum disulfide, 1-2 parts of cast iron powder and 1-2 parts of zirconium corundum.
Preferably, the zirconia content in the zirconia corundum is 8-12% by mass.
Preferably, the friction material is prepared by the preparation method of the friction material.
The invention also provides a brake pad which comprises the friction material.
The invention has the beneficial effects that:
1) according to the preparation method of the friction material, the specific steps of primary heat preservation, secondary heat preservation and tertiary heat preservation are adopted, and the segmented pressurizing process is adopted in the sintering and cooling process, so that the problem that the consistency of the friction coefficient of the friction material is poor due to expansion of the friction material after pressure unloading under the high-temperature condition is effectively solved, the stability of the friction coefficient of the friction material is ensured, and the performance of the material is stabilized. Meanwhile, the sintering step is carried out in the atmosphere of hydrogen and/or nitrogen, which is beneficial to improving the density, hardness, shearing strength and compressive strength of the friction material and improving the friction coefficient stability of the friction material under the condition of a certain speed grade.
2) Further, the volume ratio of the hydrogen to the nitrogen is 5:95-10: 90. According to the invention, the sintering step is controlled to be carried out in the atmosphere with the volume ratio of the hydrogen to the nitrogen being 5:95-10:90, so that the density, the hardness, the shear strength and the compressive strength of the friction material can be further improved, and the friction coefficient stability of the friction material under a certain speed grade condition can be further improved.
3) The preparation method of the friction material provided by the invention further has the advantages that the pressure of the primary heat preservation, the secondary heat preservation and the third heat preservation is equal, and the defect of poor performance of the friction material caused by pressure change in the sintering and cooling process is further overcome by controlling the pressure of the primary heat preservation, the secondary heat preservation and the third heat preservation to be equal.
4) According to the preparation method of the friction material, a specific powder mixing device is adopted in the mixing step, the auxiliary reamer is arranged on the side portion of the spiral main reamer, and when the spiral main reamer rotates along the circumferential direction of the spiral main reamer, centrifugal force is generated, so that materials in the mixing bin are driven to move towards the direction far away from the spiral main reamer. At this time, the material moves toward the assist reamer, and is stirred by the assist reamer. Above-mentioned auxiliary reamer can assist the spiral main reamer effectively and process the material, has avoided its material of current powder blendor to concentrate near the bulkhead in stirring the storehouse effectively, leads to the material stirring inhomogeneous, and the problem of additive segregation is held to the group appears in the material easily.
The batching step adopts a specific weighing device, the weighing device replaces the existing volume cavity through a weighing bin to weigh materials such as powder metallurgy and the like, the situation that the height of a die cavity is required to be controlled through traditional powder metallurgy pressing is effectively avoided, a volume cavity is obtained, powder is filled into the volume cavity, and the powder filling quality is determined. And the problems that the volume of the volume cavity cannot be accurately adjusted, the loose packing density of the powder is different and the powder is not uniformly distributed when the powder is filled in the volume cavity in the method are further solved.
According to the invention, through the specific weighing device and the powder mixing device, the problem that the stability of the friction material is influenced due to uneven powder distribution and different powder apparent densities in the steps of material proportioning and mixing of the friction material raw materials is effectively solved.
5) The friction material provided by the invention further comprises, by weight, 55-60 parts of copper powder, 22-28 parts of iron powder, 6-8 parts of ferrochrome powder, 4-6 parts of graphite, 2-4 parts of silicon dioxide, 0.5-1.5 parts of molybdenum disulfide, 1-2 parts of cast iron powder and 1-2 parts of zirconium corundum; the friction material is prepared by the preparation method of the friction material. The friction material is prepared by the preparation method, so that the obtained friction material has higher density, hardness, shear strength and compressive strength, and the friction coefficient of the friction material is more stable under the condition of a certain speed grade. Meanwhile, the friction coefficient of the friction material can be effectively improved by adding the specific amount of the cast iron powder into the friction material, but the addition of the cast iron powder can improve the abrasion loss of the friction material, is not beneficial to the stability of the friction material and influences the service life of the friction material.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic view of an internal structure of a powder mixing apparatus according to the present invention;
FIG. 2 is a schematic view of the inner structure of the powder mixing device according to the present invention;
fig. 3 is a schematic structural diagram of the weighing apparatus provided by the present invention.
Description of reference numerals:
1-a mixing bin; 2-a helical main reamer; 3-auxiliary reamer; 4-a cutter head; 5-a feed inlet; 6-a nozzle; 7-heating means; 8-a discharge mechanism; 9-a weighing device; 10-a main storage bin; 11-a weighing bin; 12-spirometric rods; 13-a sleeve; 14-sleeve feed port; 15-sleeve discharge hole.
Detailed Description
The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
The invention provides a preparation method of a friction material, which comprises the steps of sequentially carrying out proportioning, mixing, pressing and sintering on raw materials of the friction material, wherein the sintering step comprises the following steps:
1) under the atmosphere of hydrogen and/or nitrogen, carrying out primary heat preservation on the friction material pressed compact at the temperature of 950 plus 1050 ℃ and under the pressure of 2-4MPa for 15-30 min;
2) after the primary heat preservation is finished, reducing the temperature of the friction material pressed compact to 850 ℃ at 2-4MPa, and carrying out secondary heat preservation for 15-30min at 2-4MPa and 850 ℃ at 750-;
3) after the secondary heat preservation is finished, reducing the temperature of the friction material pressed compact to 550-650 ℃ under 2-4MPa, and carrying out heat preservation for 15-30min for three times under 2-4MPa and 550-650 ℃;
4) and after the third heat preservation, removing the pressure, and cooling the friction material pressed compact to the room temperature to obtain the friction material.
Hydrogen is a very strong reducing atmosphere and nitrogen is a safe and cheap inert gas, but pure nitrogen is rarely used as a sintering atmosphere in the production of powder metallurgy brake pads because pure nitrogen does not have reducing properties at the sintering temperature. According to the invention, the volume ratio of the hydrogen to the nitrogen is controlled to be 5:95-10:90, on one hand, the activity of the atmosphere is controlled by the high-content nitrogen, and on the other hand, the residual oxygen in the sintering furnace and the sintered product can be reduced by the presence of the hydrogen, so that the stability of the product is ensured. Meanwhile, the whole sintering step of the present invention is performed under an atmosphere of hydrogen and/or nitrogen, and preferably, the whole sintering step is performed under an atmosphere of hydrogen and nitrogen. The inventor surprisingly finds that in the sintering step, by controlling the volume ratio of the hydrogen to the nitrogen to be 5:95-10:90, the stability of the friction coefficient of the friction material can be effectively ensured, the stability of the instantaneous friction coefficient of the friction material is better, and the density, the hardness, the shear strength and the compressive strength of the friction material can be further improved.
Preferably, the pressure of the primary heat preservation, the secondary heat preservation and the third heat preservation is equal. The invention is beneficial to further eliminating the defect of poor performance of the friction material caused by the change of the pressure in the sintering and cooling process by controlling the pressure of the primary heat preservation, the secondary heat preservation and the third heat preservation to be equal.
Preferably, the sintering step comprises the steps of:
1) in the atmosphere of hydrogen and nitrogen, carrying out primary heat preservation on a friction material pressed compact at 1000 ℃ and 3MPa for 30min, wherein the volume ratio of hydrogen to nitrogen is 5: 95;
2) after the primary heat preservation is finished, reducing the temperature of the friction material pressed compact to 800 ℃ under 3MPa, and carrying out secondary heat preservation for 30min under 3MPa and 800 ℃;
3) after the secondary heat preservation is finished, reducing the temperature of the friction material pressed compact to 600 ℃ under 3MPa, and carrying out heat preservation for 30min for three times under 3MPa and 600 ℃;
4) and after the third heat preservation, removing the pressure, and cooling the friction material pressed compact to the room temperature to obtain the friction material.
Preferably, the preparation method of the friction material compact comprises the following steps: the method comprises the steps of mixing materials of the friction material to obtain a friction material mixture, and pressing the friction material mixture to obtain a friction material pressed blank, wherein the pressing pressure is 6-15MPa, and the pressing time is 3-5 s. Wherein the step of proportioning comprises weighing the raw materials of the friction material according to the proportion; the mixing step comprises the step of mixing the weighed raw materials of the friction material.
Preferably, after the sintering step, the method further comprises the step of post-treating the friction material compact. The post-processing step includes a step of machining the sintered friction material compact.
Preferably, the apparatus used in the step of dosing comprises a weighing device, the apparatus used in the step of mixing comprises a powder mixing device, and the powder mixing device, as shown in fig. 1 and 2, comprises:
the mixing bin 1 is provided with a feeding hole 5 for materials to enter;
the spiral main reamer 2 is a variable-speed main reamer, is arranged in the mixing bin 1 and is driven to rotate along the circumferential direction of the mixing bin; the screw pitch value of the part, close to the feed port 5, of the spiral main reamer 2 is larger than that of the part, far away from the feed port 5, of the spiral main reamer 2, and the screw pitch value of the spiral main reamer 2 gradually increases towards the direction close to the feed port 5;
the auxiliary reamer 3 is a variable-speed auxiliary reamer and is arranged on the side part of the spiral main reamer 2, and a cutter head 4 of the auxiliary reamer 3 faces the spiral main reamer 2; the auxiliary reamer 3 is driven by a high-speed rotor, the rotating speed of the spiral main reamer 2 is greater than that of the spiral main reamer 2, the number of the auxiliary reamer 3 is 4, and the auxiliary reamer 3 is symmetrically arranged on two sides of the spiral main reamer 2 in pairs. The auxiliary reamer 3 is arranged in the axial direction of the spiral main reamer 2 and is close to the feed inlet 5 of the mixing bin 1; according to the invention, the auxiliary reamer 3 is arranged on the side part of the spiral main reamer 2, so that centrifugal force is generated in the process that the spiral main reamer 2 rotates along the circumferential direction of the spiral main reamer, and the material in the mixing bin 1 is driven to move towards the direction far away from the spiral main reamer 2. At this time, the material moves toward the assist reamer 3, and is stirred by the assist reamer 3. Above-mentioned auxiliary reamer 3 can assist spiral main reamer 2 effectively and process the material, has avoided its material of current powder blendor to concentrate near the bulkhead in stirring the storehouse effectively, leads to the material stirring inhomogeneous, and the problem of additive segregation is held to the group appears in the material easily. In addition, the material can be effectively prevented from remaining on the wall of the stirring bin, and when the material is discharged, the material cannot be effectively discharged, so that the problems of raw material waste and insufficient utilization are caused;
and the nozzle 6 is arranged in the mixing bin 1 and faces the inner wall of the mixing bin 1 to spray air so as to discharge the residual materials in the mixing bin 1. The nozzle 6 is arranged at the top of the mixing bin 1 and forms a 45-degree included angle with a vertical plane where the spiral main reamer 2 is located. And the angle of the nozzle 6 is adjustable. The nozzle 6 capable of rotating at an angle can spray gas towards the inner wall of the mixing bin 1, so that residual mixture in the mixing bin 1 is led out, raw materials are fully utilized, and waste is avoided;
the heating parts 7 are thermocouples arranged on the wall of the mixing bin 1, and the number of the thermocouples close to the feeding port 5 is more than that of the thermocouples far away from the feeding port 5 of the mixing bin 1. Because the material quantity near the feed inlet 5 position is more, through increasing the thermocouple quantity in feed inlet 5 position, can avoid near the feed inlet 5 mixture heating insufficient, the poor problem of powder blendor's compounding effect. The heating temperature of the heating part to the friction material mixture is 100-200 ℃, and preferably 120 ℃.
Arrange material mechanism 8, arrange material mechanism 8 with blending bunker 1 is linked together, it includes to arrange material mechanism 8: a spiral push rod for propelling movement material. The spiral push rod has controllable rotating speed and can rotate forwards and reversely, so that the mixture can be effectively and uniformly discharged, and the waste of raw materials is avoided;
weighing device 9, as shown in fig. 3, weighing device 9 with blending bunker 1 is linked together, weighing device 9 includes:
a main bin 10;
the weighing bin 11 is used for weighing materials, the weighing bin 11 is communicated with the main bin 10 through a connecting channel, and a spiral rotating rod 12 is arranged in the connecting channel; the spiral rotating rod 12 is provided with threads for accommodating materials, a sleeve 13 sleeved and connected with the spiral rotating rod 12 is arranged on the outer side of the spiral rotating rod 12, and the sleeve 13 and the spiral rotating rod 12 enclose a connecting channel; the spiral rotating rod 12 is driven to rotate, the materials contained in the threads are transferred to a sleeve discharge hole 15 from a sleeve feed hole 14 of the connecting channel, the sleeve feed hole 14 is communicated with the main bin 10, and the sleeve discharge hole 15 is communicated with the weighing bin 11.
Firstly, the weighing bin is used for replacing the existing volume cavity to weigh materials such as powder metallurgy and the like, so that the condition that the height of a die cavity is controlled by controlling the height of the die cavity in the traditional powder metallurgy pressing process is effectively avoided, a volume cavity is obtained, and powder is filled into the volume cavity, so that the powder filling quality is determined. Further, the problems that the volume of the volume cavity cannot be accurately adjusted, the loose packing density of the powder is different, and the powder is not uniform when the powder is filled in the volume cavity in the method are solved, and the problem that the amount of the powder filled in the volume cavity cannot be accurately controlled is solved. The problems that the quality of powder cannot be accurately controlled, the quality fluctuation is large in the powder pressing process, and the rejection rate of parts is high are solved. According to the method, the volume of the volume cavity does not need to be calculated, the height of the cavity is repeatedly and accurately adjusted, and the working efficiency is improved. Secondly, the weighing bin 11 and the main bin 10 are connected through a connecting channel, and a spiral rotating rod 12 is arranged in the connecting channel; the spiral rotating rod 12 is provided with threads for containing the materials, the spiral rotating rod 12 is driven to rotate, the materials contained in the threads are transferred to the sleeve discharge hole 15 from the sleeve feed port 14, the sleeve feed port 14 is communicated with the main bin 10, and the sleeve discharge hole 15 is communicated with the weighing bin 11, so that the quantity of the materials such as powder metallurgy and the like led into the weighing bin 11 is effectively controlled, the effect of accurately controlling the weight of the materials entering the weighing bin 11 is achieved, the problem that the quantity of the materials entering the weighing bin 11 is difficult to control is solved, and the weighing precision and the weighing efficiency are improved. And, through above-mentioned sleeve 13 of putting on spiral bull stick 12 of cover, can make sleeve 13 and spiral bull stick 12 enclose into interface channel for each section of interface channel all holds the powder metallurgy material of equivalent, can put into weigh bin 11 with quantitative powder metallurgy material accurately when spiral bull stick 12 rotates, avoids putting into the problem that how much is difficult to accurate control of the material in weigh bin 11.
In this embodiment, the auxiliary reamer 3 is disposed at a position below the side of the helical main reamer 2, and the cutter head 4 is disposed obliquely upward toward the helical main reamer 2. And the vertical plane where the auxiliary reamer 3 and the spiral main reamer 2 are positioned mutually form an included angle of 45 degrees. Through setting up auxiliary reamer 3 in 2 lateral parts belows on the main reamer of spiral, and let auxiliary reamer 3's tool bit 4 upwards incline towards the main reamer of spiral, can stir the material that receives the action of gravity whereabouts effectively, and then improve auxiliary reamer 3's stirring efficiency.
In the present embodiment, the number of the spiral rotating rods 12 is multiple, and the plurality of the spiral rotating rods 12 have at least two different pitch values.
Of course, the number of the auxiliary reamers 3 in the present application is not limited specifically, and in other embodiments, there may be more than 4 auxiliary reamers 3, and a plurality of auxiliary reamers 3 are disposed on both sides of the spiral main reamer 2.
Of course, the application of the present invention does not specifically limit the inclined angle of the auxiliary reamer 3, and in other embodiments, the auxiliary reamer 3 and the vertical plane where the spiral main reamer 2 is located form an angle of 30 degrees or an angle of 60 degrees with each other.
Of course, the medium sprayed from the nozzle 6 is not limited in any way, and in other embodiments, the nozzle 6 may also spray other media that do not react with the mixture chemically.
Of course, the number and pitch of the spiral rotating rods 12 are not limited in the present application, and in other embodiments, the spiral rotating rods 12 are in three groups, each group has three or more spiral rotating rods 12, and the pitches increase sequentially.
Of course, the present application does not specifically limit the positions of the sleeve inlet 14 and the sleeve outlet 15 disposed on the sleeve 13, and in other embodiments, the sleeve inlet 14 and the sleeve outlet 15 may also be disposed at two ends of the sleeve 13 respectively.
According to the invention, through the specific weighing device and the powder mixing device, the problem that the stability of the friction material is influenced due to uneven powder distribution and different powder apparent densities in the steps of material proportioning and mixing of the friction material raw materials is effectively solved.
The invention provides a friction material, which comprises the following raw materials in parts by weight,
55-60 parts of copper powder, 22-28 parts of iron powder, 6-8 parts of ferrochrome powder, 4-6 parts of graphite, 2-4 parts of silicon dioxide, 0.5-1.5 parts of molybdenum disulfide, 1-2 parts of cast iron powder and 1-2 parts of zirconium corundum.
Preferably, the zirconia content in the zirconia corundum is 8-12% by mass.
Preferably, the friction material is prepared by the preparation method of the friction material.
The friction material prepared by the preparation method has higher density, hardness, shear strength and compressive strength, and the friction coefficient of the friction material is more stable under a certain speed grade condition. Meanwhile, the friction coefficient of the friction material can be effectively improved by adding the specific amount of the cast iron powder into the friction material, but the addition of the cast iron powder can improve the abrasion loss of the friction material, is not beneficial to the stability of the friction material and influences the service life of the friction material.
Preferably, the zirconia content in the zirconia corundum is 8-12% by mass. The invention can further reduce the adverse effect caused by the addition of the cast iron powder by mutually matching the zirconium corundum with the cast iron powder with the mass content of 8-12 percent, effectively reduce the abrasion loss of the friction material and ensure that the friction coefficient stability of the friction material is better.
The invention also provides a brake pad which comprises the friction material.
The technical solution of the present invention is explained by the following embodiments:
the blending steps in the following examples 1 to 8 are all conventional in the field, the mixing steps are all conventional in the field, and the mixing equipment adopted in the mixing steps is a mixing tank of mixing equipment conventional in the field.
Example 1:
the embodiment provides a friction material, which comprises the following raw materials: 55kg of copper powder, 28kg of iron powder, 6kg of ferrochrome powder, 6kg of graphite, 2kg of silicon dioxide, 1.5kg of molybdenum disulfide, 1kg of cast iron powder and 2kg of zirconia corundum, wherein the mass content of zirconium dioxide in the zirconia corundum is 8%.
The preparation method of the friction material comprises the following steps:
(1) preparing materials: weighing the raw materials according to the proportion;
(2) mixing materials: mixing the weighed raw materials to obtain a friction material mixture;
(3) pressing: pressing the friction material mixture into a pressed blank to obtain a friction material pressed blank, wherein the pressing pressure is 6MPa, and the pressing time is 5 s;
(4) and (3) sintering: the sintering step comprises the following steps:
1) under the atmosphere of hydrogen and nitrogen, carrying out primary heat preservation on the friction material pressed compact at 950 ℃ and 4MPa for 15 min; the volume ratio of the hydrogen to the nitrogen is 5: 95;
2) after the primary heat preservation is finished, reducing the temperature of the friction material pressed compact to 850 ℃ under 2MPa, and carrying out secondary heat preservation for 20min under 2MPa and 850 ℃;
3) after the secondary heat preservation is finished, reducing the temperature of the friction material pressed compact to 550 ℃ under 2MPa, and carrying out heat preservation for 15min for three times under 2MPa and 550 ℃;
4) and after the third heat preservation, removing the pressure, and cooling the friction material pressed compact to the room temperature to obtain the friction material.
Example 2:
the embodiment provides a friction material, which comprises the following raw materials: 60kg of copper powder, 22kg of iron powder, 8kg of ferrochrome powder, 4kg of graphite, 4kg of silicon dioxide, 0.5kg of molybdenum disulfide, 2kg of cast iron powder and 1kg of zirconia corundum, wherein the mass content of zirconium dioxide in the zirconia corundum is 12%.
The preparation method of the friction material comprises the following steps:
(1) preparing materials: weighing the raw materials according to the proportion;
(2) mixing materials: mixing the weighed raw materials to obtain a friction material mixture;
(3) pressing: pressing the friction material mixture into a pressed blank to obtain a friction material pressed blank, wherein the pressing pressure is 15MPa, and the pressing time is 3 s;
(4) and (3) sintering: the sintering step comprises the following steps:
1) under the atmosphere of hydrogen and nitrogen, carrying out primary heat preservation on the friction material pressed compact at 1050 ℃ and 2MPa for 30 min; the volume ratio of the hydrogen to the nitrogen is 10: 90;
2) after the primary heat preservation is finished, reducing the temperature of the friction material pressed compact to 750 ℃ under 4MPa, and carrying out secondary heat preservation for 15min under 4MPa and 750 ℃;
3) after the secondary heat preservation is finished, reducing the temperature of the friction material pressed compact to 650 ℃ under 4MPa, and carrying out heat preservation for 30min for three times under 4MPa and 650 ℃;
4) and after the third heat preservation, removing the pressure, and cooling the friction material pressed compact to the room temperature to obtain the friction material.
Example 3:
the embodiment provides a friction material, which comprises the following raw materials: 55kg of copper powder, 26kg of iron powder, 7kg of ferrochrome powder, 5kg of graphite, 3kg of silicon dioxide, 1kg of molybdenum disulfide, 1.5kg of cast iron powder and 1.5kg of zirconia corundum, wherein the mass content of zirconium dioxide in the zirconia corundum is 10%.
The preparation method of the friction material comprises the following steps:
(1) preparing materials: weighing the raw materials according to the proportion;
(2) mixing materials: mixing the weighed raw materials to obtain a friction material mixture;
(3) pressing: pressing the friction material mixture into a pressed blank to obtain a friction material pressed blank, wherein the pressing pressure is 8MPa, and the pressing time is 3.5 s;
(4) and (3) sintering: the sintering step comprises the following steps:
1) under the atmosphere of hydrogen and nitrogen, carrying out primary heat preservation on the friction material pressed compact at 1000 ℃ and 3MPa for 30 min; the volume ratio of the hydrogen to the nitrogen is 5: 95;
2) after the primary heat preservation is finished, reducing the temperature of the friction material pressed compact to 800 ℃ under 3MPa, and carrying out secondary heat preservation for 30min under 3MPa and 800 ℃;
3) after the secondary heat preservation is finished, reducing the temperature of the friction material pressed compact to 600 ℃ under 3MPa, and carrying out heat preservation for 30min for three times under 3MPa and 600 ℃;
4) and after the third heat preservation, removing the pressure, and cooling the friction material pressed compact to the room temperature to obtain the friction material.
Example 4:
the embodiment provides a friction material, which comprises the following raw materials: 56.70kg of copper powder, 26.8kg of iron powder, 7.22kg of ferrochrome powder, 5.15kg of graphite, 3.10kg of silicon dioxide, 1.03kg of molybdenum disulfide, 1.2kg of cast iron powder and 1.8kg of zirconia corundum, wherein the mass content of zirconium dioxide in the zirconia corundum is 11%.
The preparation method of the friction material comprises the following steps:
(1) preparing materials: weighing the raw materials according to the proportion;
(2) mixing materials: mixing the weighed raw materials to obtain a friction material mixture;
(3) pressing: pressing the friction material mixture into a pressed blank to obtain a friction material pressed blank, wherein the pressing pressure is 8MPa, and the pressing time is 3.5 s;
(4) and (3) sintering: the sintering step comprises the following steps:
1) under the atmosphere of hydrogen and nitrogen, carrying out primary heat preservation on the friction material pressed compact at 1000 ℃ and 3MPa for 30 min; the volume ratio of the hydrogen to the nitrogen is 5: 95;
2) after the primary heat preservation is finished, reducing the temperature of the friction material pressed compact to 800 ℃ under 3MPa, and carrying out secondary heat preservation for 30min under 3MPa and 800 ℃;
3) after the secondary heat preservation is finished, reducing the temperature of the friction material pressed compact to 600 ℃ under 3MPa, and carrying out heat preservation for 30min for three times under 3MPa and 600 ℃;
4) and after the third heat preservation, removing the pressure, and cooling the friction material pressed compact to the room temperature to obtain the friction material.
Example 5:
this example provides a friction material, which differs from example 3 only in that the sintering step is performed only under an atmosphere of hydrogen.
Example 6:
this example provides a friction material, which differs from example 3 only in that the sintering step is performed only under an atmosphere of nitrogen.
Example 7:
this example provides a friction material that differs from example 3 only in that the volume ratio of hydrogen to nitrogen in the sintering step is 90: 10.
Example 8:
this example provides a friction material that differs from example 3 only in that the volume ratio of hydrogen to nitrogen in the sintering step is 95: 5.
Example 9:
this example provides a friction material, which is different from example 3 only in that the equipment used in the material-mixing step is the weighing device of the present invention, and the equipment used in the material-mixing step is the powder mixing device of the present invention.
Comparative example 1
This comparative example provides a friction material which, in comparison with example 3, differs only in that no corundum-zirconia is added to the starting material.
Comparative example 2
This comparative example provides a friction material which, in comparison with example 3, differs only in that the zirconia content in the zirconia corundum in the raw material is 40% by mass.
Performance testing
1. The physical and mechanical properties of the friction materials obtained in examples 1 to 9 and comparative examples 1 to 2 were measured, respectively, and the results are shown in Table 1.
TABLE 1 physical and mechanical Properties of the Friction materials
Figure BDA0002306618190000131
2. The friction materials obtained in examples 1 to 9 and comparative examples 1 to 2 were measured for the instantaneous coefficient of friction at a brake pressure of 32kN at 120km/h using an MM3000 Friction wear tester, and the results are shown in Table 2.
TABLE 1 instantaneous Friction coefficient behavior of the respective Friction materials
Figure BDA0002306618190000132
Figure BDA0002306618190000141
3. The friction materials obtained by the examples 1 to 9 and the comparative examples 1 to 2 were measured for wear loss by using an MM3000 friction wear tester, wherein the friction materials were weighed before the test, and then the friction materials were simulated under a pressure of 23kN for 10 times of 120km/h, 10 times of 160km/h, 10 times of 200km/h, and 10 times of 260km/h, and the weight of the friction materials was weighed after the test; the weight reduction calculation method is that the weight of the friction material before the test is subtracted by the weight of the friction material after the test; the test results are shown in table 3.
TABLE 3 abrasion loss of each friction material
Figure BDA0002306618190000142
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims (9)

1. The preparation method of the friction material comprises the steps of sequentially carrying out proportioning, mixing, pressing and sintering on raw materials of the friction material, and is characterized in that the sintering step comprises the following steps:
1) under the atmosphere of hydrogen and/or nitrogen, carrying out primary heat preservation on the friction material pressed compact at the temperature of 950 plus 1050 ℃ and under the pressure of 2-4MPa for 15-30 min;
2) after the primary heat preservation is finished, reducing the temperature of the friction material pressed compact to 850 ℃ at 2-4MPa, and carrying out secondary heat preservation for 15-30min at 2-4MPa and 850 ℃ at 750-;
3) after the secondary heat preservation is finished, reducing the temperature of the friction material pressed compact to 550-650 ℃ under 2-4MPa, and carrying out heat preservation for 15-30min for three times under 2-4MPa and 550-650 ℃;
4) and after the third heat preservation, removing the pressure, and cooling the friction material pressed compact to the room temperature to obtain the friction material.
2. The method of producing a friction material according to claim 1, wherein the volume ratio of hydrogen gas to nitrogen gas is 5:95 to 10: 90.
3. The method of claim 1, wherein the pressure of the first, second and third holding is the same.
4. A method of making a friction material as described in claim 3 wherein said sintering step comprises the steps of:
1) in the atmosphere of hydrogen and nitrogen, carrying out primary heat preservation on a friction material pressed compact at 1000 ℃ and 3MPa for 30min, wherein the volume ratio of hydrogen to nitrogen is 5: 95;
2) after the primary heat preservation is finished, reducing the temperature of the friction material pressed compact to 800 ℃ under 3MPa, and carrying out secondary heat preservation for 30min under 3MPa and 800 ℃;
3) after the secondary heat preservation is finished, reducing the temperature of the friction material pressed compact to 600 ℃ under 3MPa, and carrying out heat preservation for 30min for three times under 3MPa and 600 ℃;
4) and after the third heat preservation, removing the pressure, and cooling the friction material pressed compact to the room temperature to obtain the friction material.
5. The preparation method of the friction material according to any one of claims 1 to 4, wherein the preparation method of the friction material green compact comprises the following steps of mixing and blending raw materials of the friction material to obtain a friction material mixture, and pressing the friction material mixture to obtain the friction material green compact, wherein the pressing pressure is 6-15MPa, and the pressing time is 3-5 s.
6. A method of making a friction material as recited in claim 5 wherein said step of compounding employs equipment that includes a weighing device, said step of compounding employs equipment that includes a powder compounding device, said powder compounding device comprising:
a mixing bin (1);
the spiral main reamer (2) is arranged in the mixing bin (1) and is driven to rotate along the circumferential direction of the mixing bin;
the auxiliary reamer (3) is arranged on the side part of the spiral main reamer (2), and a cutter head (4) of the auxiliary reamer (3) is arranged towards the spiral main reamer (2);
further comprising: with weighing device (9) that blending bunker (1) is linked together, weighing device (9) include:
a main silo (10);
the weighing bin (11) is used for weighing materials, the weighing bin (11) is communicated with the main bin (10) through a connecting channel, and a spiral rotating rod (12) is arranged in the connecting channel;
the spiral rotating rod (12) is provided with threads for accommodating materials, a sleeve (13) sleeved and connected with the spiral rotating rod (12) is arranged on the outer side of the spiral rotating rod (12), and the sleeve (13) and the spiral rotating rod (12) enclose a connecting channel; the spiral rotating rod (12) is driven to rotate, the materials contained in the threads are transferred to a sleeve discharge hole (15) from a sleeve feed hole (14) of the connecting channel, the sleeve feed hole (14) is communicated with the main bin (10), and the sleeve discharge hole (15) is communicated with the weighing bin (11).
7. A friction material is characterized in that raw materials of the friction material comprise, by weight,
55-60 parts of copper powder, 22-28 parts of iron powder, 6-8 parts of ferrochrome powder, 4-6 parts of graphite, 2-4 parts of silicon dioxide, 0.5-1.5 parts of molybdenum disulfide, 1-2 parts of cast iron powder and 1-2 parts of zirconium corundum;
the friction material is prepared by the preparation method of the friction material according to any one of claims 1 to 6.
8. The friction material of claim 7, wherein the zirconia content in the zirconia corundum is 8-12% by mass.
9. Brake pad, characterized in that it comprises a friction material according to claim 7 or 8.
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