CN116377279A - Copper-based powder metallurgy brake pad containing multiple ceramic components and preparation method thereof - Google Patents
Copper-based powder metallurgy brake pad containing multiple ceramic components and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a copper-based powder metallurgy brake pad containing various ceramic components and a preparation method thereof. The ceramic contains a plurality of ceramicsThe copper-based powder metallurgy brake pad comprises the following raw materials in percentage by mass: 50-60% of electrolytic copper powder; 10-18% of reduced iron powder; 2-4% of electrolytic nickel powder; 2-4% of atomized tin powder; 2-5% of tungsten powder; 8-14% of natural flake graphite powder; 2-4% of hexagonal boron nitride powder; 2-6% of boron carbide powder; 2 to 6 percent of titanium carbide powder. The preparation method comprises the steps of mixing materials, pressing to obtain a green body, treating a steel back, and then carrying out hot-pressing sintering to obtain the product. The product obtained by the invention has the braking pressure of 0.6MPa and the braking inertia of 0.35 kg.m 2 The abrasion loss is 0.04-0.15 cm 3 and/MJ, the friction stability coefficient is 0.72-0.86. The invention has reasonable component design, simple and controllable preparation process, and the obtained product has excellent performance and is convenient for industrialized application.
Description
Technical Field
The invention belongs to the technical field of preparation of copper-based powder metallurgy brake discs, and particularly relates to a copper-based powder metallurgy brake disc containing various ceramic components and a preparation method thereof.
Background
Friction consumes a lot of energy in production and life, wear causes failure of about 80% of machine parts, lubrication failure and excessive wear cause overall failure or major accidents of more than 50% of equipment. If calculated according to 5% of GDP, the loss of China caused by friction and abrasion in 2019 reaches 4.95 trillion yuan. Therefore, the potential of realizing energy conservation by applying the advanced friction technology in the production and manufacturing processes in China is huge. The high-speed railways in China become the country with the largest building mode, the longest operation mileage, the largest high-speed train quantity and the highest operation speed in the world, the number of motor train units in the country in 2020 has increased to 3918 groups, and the number of motor trains reaches 31340. The brake system is a key system for ensuring the safety and emergency of the transportation means, and the basic brake formed by the friction pair materials plays a decisive role in the brake system, so that the high speed of the transportation means can not be realized without the safe and reliable friction pair materials of the brake system.
Most of brake systems for high-speed rail are disc-shaped brake devices, and friction pairs are composed of brake discs and brake pads, and the friction forces generated by the brake discs and the brake pads are utilized to realize deceleration or parking. The brake pad belongs to consumable materials, the brake pad is required to be replaced for about 4 times a year for one train of motor train units, the required number of each motor train unit is about 24, the high-speed rail replacement requirement of China in 2020 is about 300 ten thousand pieces according to the required number, and the corresponding market space is estimated to be billion. However, the domestic brands only occupy 20% of the domestic brake pad market at present, only a few companies such as best in the days, beijing Pu Ran, boshen tool and the like are developing and innovating, the localization process is not high, and the few countries such as Germany, japan, french and the like are the main supply countries of the high-speed rail brake pads, wherein the Germany Kenuel company monopolizes the near half of the high-speed rail brake pad market worldwide. Therefore, the production technology of the high-speed railway brake pad at the current stage of China is not mature enough and has a certain gap with the advanced level of foreign countries, so that the development of the high-temperature-resistant low-abrasion high-performance brake pad is urgently needed in China, the domestic market is preempted, monopoly is broken, and the smooth change of the light weight and high-speed development of the next-generation high-speed train in China is ensured.
Chinese patent document CN114542632a discloses a high-speed rail brake pad using composite wear-resistant material and method for preparing the same, wherein the composite wear-resistant material comprises metal powder and inorganic nonmetallic powder. The wear resistance and the strength of the high-speed rail brake pad are improved in the mode.
Chinese patent document CN102102720B discloses a ceramic/metal bicontinuous phase composite brake pad, which relates to silicon carbide foam ceramic, and the produced brake pad can cooperate with a brake disc, has a suitable and stable friction coefficient, and has low manufacturing cost and long service life.
Chinese patent document CN113550993B discloses a reinforced high-speed train brake pad material and a preparation method thereof, wherein the reinforced component adopted by the reinforced high-speed train brake pad material is MoAl-Si-B powder, so that the brake pad with higher friction coefficient, low abrasion loss and small damage to a brake disc is prepared.
From the above, it is known that ceramic powder plays a very good role in stabilizing friction performance at high temperature due to its own excellent characteristics such as high strength, stable chemical properties, excellent corrosion resistance and high temperature resistance. However, to date, there has been a fresh use of double ceramic powder B 4 C-TiC is matched with hexagonal boron nitride powder and a metal matrix to improve friction stability and heat resistance of the brake pad.
Disclosure of Invention
The invention is based on improving the heat resistance of the copper-based powder metallurgy brake pad, utilizes the characteristic parameters of various reinforcing phases to cooperatively reinforce, fully plays the advantages and coupling effects of each component, and obtains the copper-based composite material with excellent comprehensive performance. The invention is for the first timeAttempts were made to use double ceramic powder B 4 C-TiC cooperates with hexagonal boron nitride powder and a metal matrix to improve friction stability and heat resistance of the brake pad.
The invention relates to a copper-based powder metallurgy brake pad containing a plurality of ceramic components, which comprises the following raw materials in percentage by mass:
50-60% of electrolytic copper powder, preferably 52-58%;
10 to 18 percent of reduced iron powder, preferably 14 to 16 percent;
2-4%, preferably 2-3% of electrolytic nickel powder;
2 to 4 percent of atomized tin powder, preferably 2 to 2.5 percent;
2 to 5 percent of tungsten powder, preferably 2 to 4 percent, and more preferably 2 percent;
8-14%, preferably 10-14%, more preferably 10% of natural flaky graphite powder;
2-4%, preferably 2% of hexagonal boron nitride powder;
2-6%, preferably 2-4% of boron carbide powder;
2 to 6 percent of titanium carbide powder, preferably 5 to 6 percent.
As a further preferred embodiment; when the components are in a limited range, the friction stability of the product can be further improved when the content of the boron carbide powder is 3 percent and the content of the titanium carbide is 5 percent.
As a further preferred embodiment: 58% of electrolytic copper powder, 16% of reduced iron powder, 2% of electrolytic nickel, 2% of atomized tin powder, 2% of tungsten powder, 10% of natural flaky graphite powder, 2% of hexagonal boron nitride powder, 3% of boron carbide powder and 5% of titanium carbide powder.
Compared with the existing copper-based powder metallurgy friction material reinforced by single ceramic powder, the invention utilizes the characteristic parameters of boron carbide, titanium carbide and hexagonal boron nitride to cooperatively reinforce, and fully exerts the advantages and coupling effect of three components. In the braking process, boron carbide powder can generate a boron oxide ceramic film on the friction surface, so that the stability of friction performance at high temperature is improved. The titanium carbide powder can be adhered to the copper matrix, so that the loss of the matrix is reduced, and the wear resistance is improved. The synergistic effect of the two ceramic powders ensures that the copper-based powder metallurgy brake pad not only has good high temperature resistance, but also keeps less abrasion. When a proper amount of boron carbide powder and titanium carbide powder are matched with hexagonal boron nitride powder and a metal matrix, a direct mixing mode can be adopted to prepare the copper-based powder metallurgy friction material with excellent performance. Of course, if the prepared ceramic powder (such as hexagonal boron nitride powder, boron carbide powder and titanium carbide powder) is subjected to high-energy ball milling, the performance of the product is further improved.
The electrolytic copper powder is used as a matrix component and is used as a main body for bearing load and heat conduction, and is a main channel for friction heat dissipation, and the particle size is 60-80 microns.
The reduced iron powder is used as a matrix strengthening component, has small solubility and good wettability, and is used as a second phase in copper powder, so that the friction and wear properties of the material are better, and the particle size is 60-80 microns.
The electrolytic nickel powder is a matrix strengthening component, is infinitely dissolved with a copper matrix, can improve the melting point and high-temperature strength of the matrix, and has a particle size of 60-80 microns.
The atomized tin powder is used as a matrix strengthening component, and transient liquid phase is generated in the sintering process to promote the densification of sintering, and the particle size is not higher than 60-80 microns.
The tungsten powder is a matrix reinforcing component, can increase the specific heat capacity of the matrix, and ensures excellent thermal conductivity, and the particle size is 60-80 microns.
The natural flake graphite powder is used as a matrix lubricating component and is used for eliminating clamping stagnation, reducing noise, adjusting friction factors and reducing abrasion of a brake disc, and the particle size is 150-200 microns.
The hexagonal boron nitride powder is used as a matrix lubricating component, so that the high-temperature friction stability is improved, and the particle size is 60-80 microns.
The boron carbide powder is used as a friction component of a matrix, can be used as a microprotrusion body at high temperature to prevent the matrix from losing, and has the particle size of 60-80 microns.
The titanium carbide powder is used as a matrix friction component, the friction factor is adjusted, and adhesion accumulation and oxide on the surface of the brake disc are eliminated to improve the high-temperature friction stability, and the particle size is 60-80 microns.
The invention relates to a preparation method of a copper-based powder metallurgy brake pad containing various ceramic components, which comprises the following steps:
the first step:
weighing electrolytic copper powder, reduced iron powder, electrolytic nickel powder, atomized tin powder, tungsten powder, natural scaly graphite powder, hexagonal boron nitride powder, boron carbide powder and titanium carbide powder according to design components, adding the prepared powder into a V-shaped mixer, supplementing aviation kerosene accounting for 2.5-3.5% of the total mass of the powder, controlling the rotating speed to be 90-100r/min, and mixing for 10-12 hours at normal temperature to obtain uniformly mixed powder;
second step
Pouring the uniformly mixed powder into a grinding tool, and performing compression molding, wherein the compression pressure is controlled to be 450-550 MPa during compression molding, and the pressure maintaining time is controlled to be 15-25 s;
third step, shot blasting of the steel back
Carrying out surface pretreatment on the required steel back, polishing and smoothing, cleaning and drying;
fourth step, sintering and forming
Placing the obtained green body on a steel back, sintering by using a pressurized sintering furnace, and adopting a technology of combining stepped heating and sectional pressurizing; the specific process comprises the following steps: heating to 600 ℃ under the condition that the sintering pressure is 1-1.5 MPa; then the sintering pressure is increased to 2-2.5MPa and the sintering temperature is increased to 910-940 ℃; then the sintering pressure is raised to 3-5 MPa and the temperature is kept at the sintering temperature for 2-3 hours, H 2 And N 2 As a whole protective atmosphere; to obtain the copper-based powder metallurgy brake pad containing various ceramic components.
In industrial application, firstly, the prepared hexagonal boron nitride powder, boron carbide powder and titanium carbide powder are placed in a high-energy ball mill, 50ml of ethanol is added, and the ball-to-material ratio is 50-100:1, preferably 50:1. the control rotation speed is 350-450r/min, preferably 400-450:1. the ball milling time is 10 to 50 hours, preferably 40 to 55 hours. The composite ceramic powder after high-energy ball milling is not only uniformly mixed, but also small in particle size and high in activity, and is beneficial to densification of green body sintering.
Carrying out surface pretreatment on the required steel back, polishing and smoothing, cleaning and drying; the surface roughness was measured to be 0.8-1.6.
During sintering and forming, the protective gas is H 2 And N 2 According to the volume ratio of 1-2: 1-2.
The copper-based powder metallurgy brake pad containing various ceramic components is designed and prepared by the invention; its density is 4.2-5.2g/cm 3 The aperture ratio is 2-10%.
The copper-based powder metallurgy brake pad containing various ceramic components is designed and prepared by the invention; the braking pressure is 0.6MPa, and the braking inertia is 0.35 kg.m 2 Under the condition of adopting an MM-3000 shrinkage ratio tester to pair with a carbon ceramic plate, repeating braking for 10 times under the drying working condition, setting the braking speed to be 24m/s, and making the carbon ceramic plate (density 2.32 g/cm) by the university of south China powder metallurgy institute 3 Hardness of 121.2 HRL) is 0.05-0.15 cm 3 Preferably 0.05 to 0.08cm 3 The friction stability factor is 0.74-0.86, preferably 0.82-0.86.
The copper-based powder metallurgy brake pad containing various ceramic components is designed and prepared by the invention; the braking pressure is 0.6MPa, and the braking inertia is 0.35 kg.m 2 Under the condition of adopting an MM-3000 scaling tester, the abrasion loss is 0.04-0.13 cm when being matched with a 30CrMnSi steel brake disc (Dayu Special steel Co., ltd.) 3 Preferably 0.04 to 0.08cm 3 The friction stability factor is between 0.72 and 0.85, preferably between 0.81 and 0.85.
Of course, the copper-based powder metallurgy brake pad containing various ceramic components, which is related and prepared by the invention, can be matched with the existing carbon ceramic disc or metal brake disc for use.
Advantageous effects
In the aspect of material design, electrolytic copper powder is adopted as a matrix component and is used as a main body for bearing load and heat conduction, so that the electrolytic copper powder is a main channel for friction heat dissipation. Reduced iron powder is introduced as a second phase to strengthen the friction and wear properties of the material. Electrolytic nickel powder is introduced to infinitely dissolve with a copper matrix to improve the melting point and high-temperature strength of the matrix. Atomized tin powder and tungsten powder are introduced to promote densification of the sintering and to increase the specific heat capacity of the matrix. Proper amounts of natural flake graphite powder and hexagonal boron nitride powder are introduced to adjust the friction factor and improve the high-temperature friction stability. Proper amounts of boron carbide powder and titanium carbide powder are introduced to cooperatively strengthen the high temperature resistance and the friction stability of the copper-based powder metallurgy brake pad. Wherein, boron carbide promotes the stability of friction performance at high temperature through generating boron oxide ceramic film on the friction surface. The titanium carbide powder can be adhered to the copper matrix, so that the loss of the matrix is reduced, and the wear resistance is improved. The increase of the ceramic powder content in the copper-based powder metallurgy brake pad is beneficial to the improvement of high-temperature friction stability, and the optimization of the introduction ratio of the boron carbide powder and the titanium carbide powder also increases the brake pad friction stability.
When the copper-based powder metallurgy brake pad provided by the invention acts with the carbon ceramic brake disc, the abrasion is low, the high-temperature friction stability is good, the brake pad and the brake disc are not defective, and the matching performance is good. The brake pad with high content and proper proportion of ceramic powder introduced (3% boron carbide-5% titanium carbide-2% hexagonal boron nitride) has good high-temperature friction stability and mechanical strength, and keeps less abrasion. Meanwhile, asbestos, lead and compounds thereof are not used for the brake pad.
Drawings
Fig. 1 is a friction braking curve of the examples and comparative examples of the present invention.
Fig. 2 shows the coefficient of friction stability under 10 repeated high-energy braking for the example of the present invention and the comparative example.
Fig. 3 shows the wear rate after 10 repetitions of high-energy braking and the corresponding loss rate of carbon Tao Panmo for the examples and comparative examples according to the invention.
FIG. 4 is a graph of the friction surface after a braking experiment for example 4 of the present invention.
As can be seen from fig. 1 and 2: the stability of the braking curve and the friction stability coefficient of the embodiment are superior to those of the comparative example, and the synergistic strengthening effect of the composite ceramic powder is beneficial to improving the friction performance. Example 1 is advantageous over examples 2 and 3 in that the optimization of the proportion of the composite ceramic powder is beneficial to the improvement of the friction performance. Example 4 is advantageous over example 1 in that the composite ceramic powder after high energy ball milling is beneficial to improving the friction performance. Example 4 is advantageous over example 6 in that optimization of high energy ball milling conditions is beneficial for improved friction performance. Example 4 is superior to example 7, and the prepared copper-based powder metallurgy brake pad and the carbon ceramic disc have better adaptability.
As can be seen from fig. 3: the abrasion rate after high-energy braking is smaller than that of the comparative example, the damage of the carbon ceramic disc is lower, the friction performance is better, and the synergistic strengthening effect of the composite ceramic powder is beneficial to improving the friction performance.
As can be seen from fig. 4: example 4 the friction surface had a smooth film, no obvious defects and little wear.
Detailed Description
The invention discloses a copper-based powder metallurgy brake pad prepared by double ceramic powder, which comprises the following steps:
example 1:
firstly, raw material weighing
58% of electrolytic copper powder, 16% of reduced iron powder, 2% of electrolytic nickel, 2% of atomized tin powder, 2% of tungsten powder, 10% of natural scaly graphite powder, 2% of hexagonal boron nitride powder, 3% of boron carbide powder and 5% of titanium carbide powder are sequentially weighed according to the mass percentage from small to large, each raw material is added, the mixture is stirred for 3 minutes by a crucible, and finally aviation kerosene accounting for 3% of the total mass of the powder is added into the manually premixed raw materials.
Step two, mixing the raw materials
The manually premixed raw materials are put into a V-shaped mixer which is dried after being cleaned by ethanol, the rotating speed is 100r/min, and the raw materials are mixed for 10 hours at normal temperature and then are put into a vacuum sealing bag for preservation.
Third step, pressing the green compact
The stored powder was poured into a grinding tool, and a hollow circle of 74mm (outer diameter) ×53mm (inner diameter) and a square of 25mm were each pressed at normal temperature under 550MPa for 25s.
Fourth step, shot blasting of the steel back
And (3) carrying out surface pretreatment on the required steel back, polishing and smoothing, cleaning and drying, wherein the surface roughness is 1.1.
Fifth step, sintering and forming
The obtained green body is placed on a steel back, and is sintered by a bell jar type pressurized sintering furnace, and a technology of combining stepped heating and sectional pressurizing is adopted. Tool withThe body process comprises the following steps: heating to 600 ℃ under the condition that the sintering pressure is 1.5 MPa; heating to 920 ℃ under the condition of sintering pressure of 2 MPa; under the condition of 4MPa of sintering pressure, preserving heat for 2 hours at the sintering temperature, H 2 And N 2 And taking the mixed gas formed by the volume ratio of 1:2 as the whole-course protective atmosphere.
Sixth step, surface treatment
Naturally cooling the sintered blank to room temperature, polishing the surface of the blank to be smooth, and then cleaning and drying the blank for later use.
Seventh step, high-energy braking test
Adopting an MM-3000 shrinkage tester, wherein the hollow circle with the size of 74MM (outer diameter) multiplied by 53MM (inner diameter) is used as a dual part by self-made carbon ceramic disc of the university of middle and south powder metallurgy institute, 3200J/cm 2 A brake energy density of 10 brake averages; the test results are shown in fig. 1 and 2. During high-energy braking, the average friction stability coefficient of the copper-based powder metallurgy brake pad is 0.82, and the abrasion loss of the copper-based powder metallurgy brake pad and the abrasion loss of the carbon ceramic are respectively equal to 0.08cm 3 MJ and 0.01cm 3 /MJ。
Average coefficient of friction stability = average coefficient of friction/maximum coefficient of friction in the braking curve.
Example 2:
firstly, raw material weighing
According to the mass percentage, sequentially weighing 54% of electrolytic copper powder, 14% of reduced iron powder, 4% of electrolytic nickel, 4% of atomized tin powder, 2% of tungsten powder, 12% of natural scaly graphite powder, 2% of hexagonal boron nitride powder, 2% of boron carbide powder and 6% of titanium carbide powder from small to large, stirring for 3 minutes by using a crucible, and finally adding aviation kerosene accounting for 3% of the total mass of the powder into the manually premixed raw materials.
Step two, mixing the raw materials
The manually premixed raw materials are put into a V-shaped mixer which is dried after being cleaned by ethanol, the rotating speed is 100r/min, and the raw materials are mixed for 9 hours at normal temperature and then are put into a vacuum sealing bag for preservation.
Third step, pressing the green compact
The stored powder was poured into a grinding tool, and a hollow circle of 74mm (outer diameter) ×53mm (inner diameter) and a square of 25mm were each pressed at normal temperature under 550MPa for 20s.
Fourth step, shot blasting of the steel back
And (3) carrying out surface pretreatment on the required steel back, polishing and smoothing, cleaning and drying, wherein the surface roughness is 1.0.
Fifth step, sintering and forming
The obtained green body is placed on a steel back, and is sintered by a bell jar type pressurized sintering furnace, and a technology of combining stepped heating and sectional pressurizing is adopted. The specific process comprises the following steps: heating to 600 ℃ under the condition that the sintering pressure is 1 MPa; heating to a sintering temperature of 930 ℃ under the condition that the sintering pressure is 2.5 MPa; under the condition of 4.5MPa of sintering pressure, preserving heat for 3 hours at the sintering temperature, H 2 And N 2 And taking the mixed gas formed by the volume ratio of 1:2 as the whole-course protective atmosphere.
And sixthly, naturally cooling the blank subjected to surface treatment and sintering to room temperature, polishing the surface of the blank to be smooth, and cleaning and drying the blank for later use.
Seventh step, high-energy braking test
Adopting an MM-3000 shrinkage tester, wherein the hollow circle with the size of 74MM (outer diameter) multiplied by 53MM (inner diameter) is used as a dual part by self-made carbon ceramic disc of the university of middle and south powder metallurgy institute, 3200J/cm 2 A brake energy density of 10 brake averages; the test results are shown in fig. 1 and 2. During high-energy braking, the average friction stability coefficient of the copper-based powder metallurgy brake pad is 0.75, and the abrasion amounts of the copper-based powder metallurgy brake pad and the carbon ceramic are respectively equal to 0.12cm 3 MJ and 0.02cm 3 /MJ。
Example 3:
firstly, raw material weighing
52% of electrolytic copper powder, 16% of reduced iron powder, 3% of electrolytic nickel, 3% of atomized tin powder, 4% of tungsten powder, 14% of natural scaly graphite powder, 2% of hexagonal boron nitride powder, 4% of boron carbide powder and 2% of titanium carbide powder are sequentially weighed according to the mass percentage from small to large, each raw material is added, the crucible is used for stirring for 3 minutes, and finally 3% of aviation kerosene which is the total amount of the powder is added into the manually premixed raw materials.
Step two, mixing the raw materials
The manually premixed raw materials are put into a V-shaped mixer which is dried after being cleaned by ethanol, the rotating speed is 100r/min, and the raw materials are mixed for 9 hours at normal temperature and then are put into a vacuum sealing bag for preservation.
Third step, pressing the green compact
The stored powder was poured into a grinding tool, and a hollow circle of 74mm (outer diameter) ×53mm (inner diameter) and a square of 25mm were each pressed at normal temperature under 550MPa for 20s.
Fourth step, shot blasting of the steel back
And (3) carrying out surface pretreatment on the required steel back, polishing and smoothing, cleaning and drying, wherein the surface roughness is 0.8.
Fifth step, sintering and forming
The obtained green body is placed on a steel back, and is sintered by a bell jar type pressurized sintering furnace, and a technology of combining stepped heating and sectional pressurizing is adopted. The specific process comprises the following steps: heating to 600 ℃ under the condition that the sintering pressure is 1 MPa; heating to a sintering temperature of 930 ℃ under the condition that the sintering pressure is 2.5 MPa; under the condition of 4.5MPa of sintering pressure, preserving heat for 3 hours at the sintering temperature, H 2 And N 2 The mixed gas with the volume ratio of 1:1 is used as the whole-course protective atmosphere.
And sixthly, naturally cooling the blank subjected to surface treatment and sintering to room temperature, polishing the surface of the blank to be smooth, and cleaning and drying the blank for later use.
Seventh step, high-energy braking test
Adopting an MM-3000 shrinkage tester, wherein the hollow circle with the size of 74MM (outer diameter) multiplied by 53MM (inner diameter) is used as a dual part by self-made carbon ceramic disc of the university of middle and south powder metallurgy institute, 3200J/cm 2 A brake energy density of 10 brake averages; the test results are shown in fig. 1 and 2. During high-energy braking, the average friction stability coefficient of the copper-based powder metallurgy brake pad is 0.74, and the abrasion amounts of the copper-based powder metallurgy brake pad and the carbon ceramic are respectively equal to 0.11cm 3 MJ and 0.018cm 3 /MJ。
Example 4
Other conditions were the same as in example 1, except thatFirstly, putting the prepared hexagonal boron nitride powder, boron carbide powder and titanium carbide powder into a high-energy ball mill, wherein the ball-to-material ratio is 50:1, the rotating speed is 450r/min, and ball milling is carried out for 40 hours. After ball milling, drying to obtain activated and uniformly mixed ceramic powder; then mixing the activated and uniformly mixed ceramic powder with 58% of electrolytic copper powder, 16% of reduced iron powder, 2% of electrolytic nickel, 2% of atomized tin powder, 2% of tungsten powder and 10% of natural flaky graphite powder according to the method of the embodiment 1. The obtained product has the properties of average friction stability coefficient of 0.86, and the abrasion loss of copper-based powder metallurgy brake pad and carbon ceramic is respectively equal to 0.05cm 3 MJ and 0.005cm 3 /MJ。
Example 5
Other conditions were consistent with example 4, except that the proportion of the composite ceramic powder was changed. Adding 4% of hexagonal boron nitride powder, 2% of boron carbide powder and 4% of titanium carbide powder. The obtained product has the performance that the average friction stability coefficient is 0.77, and the abrasion loss of the copper-based powder metallurgy brake pad and the carbon ceramic is respectively 0.08cm 3 MJ and 0.01cm 3 /MJ。
Example 6
Other conditions were identical to example 4, except that the ball milling conditions were changed such that the ball-to-material ratio was 100:1, the rotating speed is 350r/min, and ball milling is carried out for 20 hours. The obtained product has the performance that the average friction stability coefficient is 0.83, and the abrasion loss of the copper-based powder metallurgy brake pad and the carbon ceramic is respectively equal to 0.06cm 3 MJ and 0.012cm 3 /MJ。
Example 7, other conditions were identical to example 4, except for the change in mating discs. Adopting an MM-3000 shrinkage tester, wherein a hollow circle with the size of 74MM (outer diameter) multiplied by 53MM (inner diameter) is adopted, and a 30CrMnSi steel brake disc is used as a pair piece, 3200J/cm 2 Is a brake energy density of 10 brake averages. The average friction stability coefficient of the copper-based powder metallurgy brake pad is 0.85, and the abrasion loss of the copper-based powder metallurgy brake pad and the abrasion loss of the carbon ceramic are respectively equal to 0.04cm 3 MJ and 0.003cm 3 /MJ。
Example 8 otherwise corresponds to example 1, except for the change in mating discs. The size of the sample is 74MM (outer diameter). Times.53 MM (inner diameter) by using an MM-3000 scaling testerHollow round, 30CrMnSi steel brake disc is a dual piece, 3200J/cm 2 Is a brake energy density of 10 brake averages. The average friction stability coefficient of the copper-based powder metallurgy brake pad is 0.81, and the abrasion loss of the copper-based powder metallurgy brake pad and the abrasion loss of the carbon ceramic are respectively equal to 0.08cm 3 MJ and 0.005cm 3 /MJ。
Comparative example 1:
firstly, raw material weighing
58% of electrolytic copper powder, 11% of reduced iron powder, 2% of electrolytic nickel, 3% of atomized tin powder, 2% of tungsten powder, 10% of natural scaly graphite powder, 4% of hexagonal boron nitride powder, 5% of boron carbide powder and 5% of titanium carbide powder are sequentially weighed according to the mass percentage from small to large, each raw material is added, the raw material is stirred for 3 minutes by a crucible, and finally 3% of aviation kerosene which is the total amount of the powder is added into the raw materials which are manually premixed.
Step two, mixing the raw materials
The manually premixed raw materials are put into a V-shaped mixer which is dried after being cleaned by ethanol, the rotating speed is 100r/min, and the raw materials are mixed for 9 hours at normal temperature and then are put into a vacuum sealing bag for preservation.
Third step, pressing the green compact
The stored powder was poured into a grinding tool, and a hollow circle of 74mm (outer diameter) ×53mm (inner diameter) and a square of 25mm were each pressed at normal temperature under 550MPa for 20s.
Fourth step, shot blasting of the steel back
And (3) carrying out surface pretreatment on the required steel back, polishing and smoothing, cleaning and drying, wherein the surface roughness is 1.0.
Fifth step, sintering and forming
The obtained green body is placed on a steel back, and is sintered by a bell jar type pressurized sintering furnace, and a technology of combining stepped heating and sectional pressurizing is adopted. The specific process comprises the following steps: heating to 600 ℃ under the condition that the sintering pressure is 1 MPa; heating to a sintering temperature of 930 ℃ under the condition that the sintering pressure is 2.5 MPa; under the condition of 4.5MPa of sintering pressure, preserving heat for 3 hours at the sintering temperature, H 2 And N 2 And taking the mixed gas formed by the volume ratio of 1:2 as the whole-course protective atmosphere.
And sixthly, naturally cooling the blank subjected to surface treatment and sintering to room temperature, polishing the surface of the blank to be smooth, and cleaning and drying the blank for later use.
Seventh step, high-energy braking test
Adopting an MM-3000 shrinkage tester, wherein the hollow circle with the size of 74MM (outer diameter) multiplied by 53MM (inner diameter) is used as a dual part by self-made carbon ceramic disc of the university of middle and south powder metallurgy institute, 3200J/cm 2 A brake energy density of 10 brake averages; the test results are shown in fig. 1 and 2. During high-energy braking, the average friction stability coefficient of the copper-based powder metallurgy brake pad is 0.61, and the abrasion amounts of the copper-based powder metallurgy brake pad and the carbon ceramic are respectively equal to 0.14cm 3 MJ and 0.04cm 3 /MJ。
Comparative example 2
Other conditions were the same as in example 1 except that the proportion of the composite ceramic powder was changed. Adding 4% of hexagonal boron nitride powder, 8% of boron carbide powder and 0% of titanium carbide powder. The obtained product has the performance of average friction stability coefficient of 0.55, and the abrasion loss of the copper-based powder metallurgy brake pad and the carbon ceramic is respectively equal to 0.18cm 3 MJ and 0.10cm 3 /MJ。
Comparative example 3
Other conditions were the same as in example 1 except that the proportion of the composite ceramic powder was changed. Adding 4% of hexagonal boron nitride powder, 0% of boron carbide powder and 8% of titanium carbide powder. The obtained product has the performance of average friction stability coefficient of 0.56, and the abrasion loss of the copper-based powder metallurgy brake pad and the carbon ceramic is respectively equal to 0.17cm 3 MJ and 0.09cm 3 /MJ。
Comparative example 4
Other conditions were the same as in example 1 except that the proportion of the composite ceramic powder was changed. Adding 0% of hexagonal boron nitride powder, 4% of boron carbide powder and 6% of titanium carbide powder. The obtained product has the performance of average friction stability coefficient of 0.58, and the abrasion loss of the copper-based powder metallurgy brake pad and the carbon ceramic is respectively equal to 0.16cm 3 MJ and 0.08cm 3 /MJ。
Comparative example 5
Other conditions were the same as in example 1 except that the ratio of the raw materials was changed. 50% of electrolytic copper powder and20% of raw iron powder, 3% of electrolytic nickel, 3% of atomized tin powder, 4% of tungsten powder, 14% of natural flaky graphite powder, 2% of hexagonal boron nitride powder, 2% of boron carbide powder and 2% of titanium carbide powder. The obtained product has the performance of average friction stability coefficient of 0.51, and the abrasion loss of the copper-based powder metallurgy brake pad and the carbon ceramic is respectively equal to 0.20cm 3 MJ and 0.12cm 3 /MJ。
Comparative example 6
Other conditions were identical to example 3, except for the change in the proportions of the raw materials. 58% of electrolytic copper powder, 18% of reduced iron powder, 4% of electrolytic nickel, 3% of atomized tin powder, 4% of tungsten powder, 6% of natural flaky graphite powder, 2% of hexagonal boron nitride powder, 1% of boron carbide powder and 4% of titanium carbide powder. The obtained product has the performance of average friction stability coefficient of 0.57, and the abrasion loss of the copper-based powder metallurgy brake pad and the carbon ceramic is respectively equal to 0.15cm 3 MJ and 0.06cm 3 /MJ。
Comparative example 7
Other conditions were identical to comparative example 2, except for the change of the mating disc. Adopting an MM-3000 shrinkage tester, wherein a hollow circle with the size of 74MM (outer diameter) multiplied by 53MM (inner diameter) is adopted, and a 30CrMnSi steel brake disc is used as a pair piece, 3200J/cm 2 Is a brake energy density of 10 brake averages. The average friction stability coefficient of the copper-based powder metallurgy brake pad is 0.54, and the abrasion loss of the copper-based powder metallurgy brake pad and the abrasion loss of the carbon ceramic are respectively equal to 0.16cm 3 MJ and 0.08cm 3 /MJ。
Comparative example 8
Other conditions were identical to comparative example 4, except for the change of the mating disc. Adopting an MM-3000 shrinkage tester, wherein a hollow circle with the size of 74MM (outer diameter) multiplied by 53MM (inner diameter) is adopted, and a 30CrMnSi steel brake disc is used as a pair piece, 3200J/cm 2 Is a brake energy density of 10 brake averages. The average friction stability coefficient of the copper-based powder metallurgy brake pad is 0.57, and the abrasion loss of the copper-based powder metallurgy brake pad and the abrasion loss of the carbon ceramic are respectively equal to 0.13cm 3 MJ and 0.05cm 3 /MJ。
Claims (10)
1. A copper-based powder metallurgy brake pad containing a plurality of ceramic components, which is characterized in that; the raw materials comprise the following components in percentage by mass:
50-60% of electrolytic copper powder;
10-18% of reduced iron powder;
2-4% of electrolytic nickel powder;
2-4% of atomized tin powder;
2-5% of tungsten powder;
8-14% of natural flake graphite powder;
2-4% of hexagonal boron nitride powder;
2-6% of boron carbide powder;
2 to 6 percent of titanium carbide powder.
2. A copper-based powder metallurgy brake pad comprising a plurality of ceramic components according to claim 1 wherein; the raw materials comprise the following components in percentage by mass:
52-58% of electrolytic copper powder;
14-16% of reduced iron powder;
2-3% of electrolytic nickel powder;
2 to 2.5 percent of atomized tin powder;
2-4% of tungsten powder;
10-14% of natural flake graphite powder;
2% of hexagonal boron nitride powder;
2-4% of boron carbide powder;
5 to 6 percent of titanium carbide powder.
3. A copper-based powder metallurgy brake pad comprising a plurality of ceramic components according to claim 2, wherein: the raw materials used comprise 3wt% of boron carbide powder and 5wt% of titanium carbide.
4. A copper-based powder metallurgy brake pad comprising a plurality of ceramic components according to claim 2, wherein; the raw materials comprise the following components in percentage by mass:
58% of electrolytic copper powder, 16% of reduced iron powder, 2% of electrolytic nickel, 2% of atomized tin powder, 2% of tungsten powder, 10% of natural flaky graphite powder, 2% of hexagonal boron nitride powder, 3% of boron carbide powder and 5% of titanium carbide powder.
5. A copper-based powder metallurgy brake pad comprising a plurality of ceramic components according to claim 2, wherein:
the particle size of the electrolytic copper powder is 60-80 microns;
the particle size of the reduced iron powder is 60-80 microns;
the particle size of the electrolytic nickel powder is 60-80 microns;
the particle size of the atomized tin powder is not higher than 80 microns;
the particle size of the tungsten powder is 60-80 microns.
The particle size of the natural flaky graphite powder is 150-200 microns;
the particle size of the hexagonal boron nitride powder is 60-80 microns;
the particle size of the boron carbide powder is 60-80 microns;
the particle size of the titanium carbide powder is 60-80 microns.
6. A method for producing a copper-based powder metallurgy brake pad containing a plurality of ceramic components according to any one of claims 1 to 5, characterized by; comprising the following steps:
the first step:
weighing electrolytic copper powder, reduced iron powder, electrolytic nickel powder, atomized tin powder, tungsten powder, natural scaly graphite powder, hexagonal boron nitride powder, boron carbide powder and titanium carbide powder according to design components, adding the prepared powder into a V-shaped mixer, supplementing aviation kerosene accounting for 2.5-3.5% of the total mass of the powder, controlling the rotating speed to be 90-100r/min, and mixing for 10-12 hours at normal temperature to obtain uniformly mixed powder;
second step
Pouring the uniformly mixed powder into a grinding tool, and performing compression molding, wherein the compression pressure is controlled to be 450-550 MPa during compression molding, and the pressure maintaining time is controlled to be 15-25 s;
third step, shot blasting of the steel back
Carrying out surface pretreatment on the required steel back, polishing and smoothing, cleaning and drying;
fourth step, sintering and forming
The green body obtained is placed on a steel backing, using pressureSintering in a sintering furnace by adopting a technology of combining stepped heating and sectional pressurizing; the specific process comprises the following steps: heating to 600 ℃ under the condition that the sintering pressure is 1-1.5 MPa; then the sintering pressure is increased to 2-2.5MPa and the sintering temperature is increased to 910-940 ℃; then the sintering pressure is raised to 3-5 MPa and the temperature is kept at the sintering temperature for 2-3 hours, H 2 And N 2 As a whole protective atmosphere; to obtain the copper-based powder metallurgy brake pad containing various ceramic components.
7. The method for producing a copper-based powder metallurgy brake pad containing a plurality of ceramic components according to claim 6, wherein:
firstly, putting the prepared hexagonal boron nitride powder, boron carbide powder and titanium carbide powder into a high-energy ball mill, adding 50ml of ethanol, and adopting a ball-to-material ratio of 50-100:1, preferably 50:1, a step of; the control rotation speed is 350-450r/min, preferably 400-450:1, a step of; the ball milling time is 10 to 50 hours, preferably 40 to 55 hours.
8. The method for producing a copper-based powder metallurgy brake pad containing a plurality of ceramic components according to claim 6, wherein:
carrying out surface pretreatment on the required steel back, polishing and smoothing, cleaning and drying; measuring to obtain the surface roughness of 0.8-1.6;
during sintering and forming, the protective gas is H 2 And N 2 According to the volume ratio of 1-2: 1-2.
9. The method for producing a copper-based powder metallurgy brake pad containing a plurality of ceramic components according to claim 6, wherein: the prepared copper-based powder metallurgy brake pad containing various ceramic components; its density is 4.2-5.2g/cm 3 The aperture ratio is 2-10%.
10. The method for producing a copper-based powder metallurgy brake pad containing a plurality of ceramic components according to claim 6, wherein: the braking pressure is 0.6MPa, and the braking inertia is 0.35 kg.m 2 Under the condition of adopting MM-3000 reduction testThe machine is matched with a carbon ceramic disc, repeated braking is carried out under the condition of 10 times of drying, the braking speed is set to be 24m/s, and the abrasion loss is 0.05-0.15 cm 3 MJ, coefficient of friction stability of 0.74-0.86;
the braking pressure is 0.6MPa, and the braking inertia is 0.35 kg.m 2 Under the condition of adopting an MM-3000 scaling tester to pair with a 30CrMnSi steel brake disc, repeating the braking under 10 times of drying working conditions, setting the braking speed to be 24m/s, and the abrasion loss to be 0.04-0.13 cm 3 and/MJ, the friction stability coefficient is 0.72-0.85.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117904482A (en) * | 2024-03-20 | 2024-04-19 | 中南大学 | Ceramic-containing copper-based powder metallurgy friction material and preparation method and application thereof |
| CN118389896A (en) * | 2024-06-17 | 2024-07-26 | 中南大学 | Ternary modified complex-phase ceramic powder reinforced copper-based powder metallurgy friction material |
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2023
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117904482A (en) * | 2024-03-20 | 2024-04-19 | 中南大学 | Ceramic-containing copper-based powder metallurgy friction material and preparation method and application thereof |
| CN117904482B (en) * | 2024-03-20 | 2024-06-04 | 中南大学 | Ceramic-containing copper-based powder metallurgy friction material and preparation method and application thereof |
| CN118389896A (en) * | 2024-06-17 | 2024-07-26 | 中南大学 | Ternary modified complex-phase ceramic powder reinforced copper-based powder metallurgy friction material |
| CN118389896B (en) * | 2024-06-17 | 2024-08-23 | 中南大学 | Ternary modified complex-phase ceramic powder reinforced copper-based powder metallurgy friction material |
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