High-wear-resistance aluminum-based friction material for heavy truck and preparation method of high-wear-resistance aluminum-based friction material

Abstract

The invention discloses a high-wear-resistance aluminum-based friction material for a heavy truck and a preparation method of the high-wear-resistance aluminum-based friction material, and belongs to the field of metal-based friction materials. The friction material is basically composed of metal elements of Al, Cr and Ce, the atomic percent of Al is 70%-90%, the atomic percent of Cr is 0%-20%, and the atomic percent of Ce is 0%-20%. The preparation method comprises the following steps: melting all the components into a whole through a vacuum melting technology, uniformly annealing in a vacuum annealing furnace at 800 DEG C for 360 hours, and quenching in water to obtain the required aluminum-based friction material. Compared with the prior art, the prepared aluminum-based friction material has the following advantages that (1) a three-phase structure of Al4Cr, Al20Cr2Ce and Al8Cr4Ce can be stably obtained by adding a proper amount of Al, Cr and Ce elements; (2) Al4Cr is used as a hard phase, so that the hardness of the material can be obviously improved, Al20Cr2Ce and Al8Cr4Ce enable the material to have higher hardness and tensile strength and also have good high-temperature stability, and through the three-phase synergistic effect, the material has higher hardness, proper and stable average friction coefficient and lower volume wear rate at the same time; and (3) raw materials are easy to obtain, preparation is convenient, and the aluminum-based friction material has good application value in the field of aluminum-based friction materials for heavy trucks.

Description

Technical Field

[0001] The invention relates to the technical field of metal-based friction materials, in particular to a highly wear-resistant aluminum-based friction material for heavy trucks and a preparation method thereof. Background Art

[0002] Brake discs are core components of the braking systems of aerospace, high-speed rail, mining machinery, and automobiles. They are usually used in harsh working conditions such as heavy loads and high temperatures, and have high requirements for friction and wear performance. Aluminum alloys are widely used due to their advantages such as low density, high specific strength, high modulus, and easy processing, but their friction and wear performance is relatively poor, the average friction coefficient fluctuates greatly, and the wear resistance is poor, which greatly limits their application in the brake disc field.

[0003] Element Cr has the advantages of improving the hardness, strength, oxidation resistance and wear resistance of aluminum alloy, while element Ce has the functions of improving aluminum alloy structure, refining grains, improving heat resistance, corrosion resistance and extending service life. Relevant research shows that when about 25% Cr (mass fraction) is added to the Fe-Al-Cr alloy system, the material achieves a good microhardness of 460.3HV 0.1 and toughness, its elastic modulus and plastic deformation work are 284.2 GPa and 5.68×10 -8 J, which increases the average friction coefficient of the material, but its wear rate reaches 10 -12 m 3 ·N -1 ·m -1 At the same time, studies have shown that after adding 0.50% and 1.00% Ce (mass fraction) to the Mg-Al-Mn alloy system, the volume wear rate of the material can reach 10 -13 m 3 ·N -1 ·m -1 The Chinese patent "Aluminum-based friction material for automobile brake pads" with publication number CN11811215A uses hot pressing sintering, solid solution aging and other methods to prepare aluminum-based friction materials with no cold brittleness and thermal decay in the working range of -40 to 350 ° C, and the density is ≤3.0g·cm -3 , but it does not list the specific average friction coefficient and volume wear rate for reference. Therefore, it is urgent to prepare aluminum-based friction materials with higher average friction coefficient, good friction stability and lower volume wear rate to meet the needs of brake discs. Summary of the invention

[0004] The purpose of the present invention is to improve the mechanical and friction and wear properties of aluminum-based friction materials by adding Cr and Ce and performing annealing and quenching treatments, and to provide a highly wear-resistant aluminum-based friction material for heavy trucks and a preparation method thereof.

[0005] In order to achieve the above object, the present invention provides the following scheme:

[0006] The present invention provides a high wear-resistant aluminum-based friction material for heavy trucks and a preparation method thereof, wherein the preparation comprises the following steps:

[0007] (1) Weigh the metal elements in order according to the atomic percentages of 70% to 90% Al, 0% to 20% Cr, and 0% to 20% Ce;

[0008] (2) placing the metal element in a water-cooled copper mold crucible in a non-consumable vacuum arc melting furnace, placing high-purity titanium particles in the crucible for oxygen absorption, closing the vacuum arc furnace door, and tightening the knob;

[0009] (3) evacuate the vacuum arc furnace, then introduce argon gas into the furnace, and repeat this step 5 times;

[0010] (4) Adjust the smelting current, melt the high-purity titanium particles first before smelting, and then melt each metal element and turn it over continuously, repeat this step 5 times, and finally cool it with the furnace;

[0011] (5) The cooled sample is placed in a vacuum annealing furnace for annealing, and then quenched to obtain the desired metal-based friction material.

[0012] Furthermore, the metal element in step (1) is in the form of blocks, flakes or granules with a purity of 99.9%, and the average particle size of the metal element is ≤2 mm.

[0013] Furthermore, the vacuum degree of the vacuum arc furnace in step (3) should reach 5×10 -3 Pa, after the introduction of argon, the pressure in the furnace should reach 0.8-0.9 standard atmospheric pressure.

[0014] Furthermore, in step (4), the smelting current is in the range of 40 to 100 A, the smelting time of high-purity titanium particles is 1 to 2 minutes, and the smelting time of the metal element is 30 to 45 seconds.

[0015] Furthermore, in step (5), the annealing environment is a vacuum state, the annealing temperature is 800° C., the annealing time is 360 h, and the quenching medium is water.

[0016] The invention provides a high wear-resistant aluminum-based friction material for heavy trucks and a preparation method thereof.

[0017] The present invention also provides the use of the metal-based friction material in a brake disc for a heavy truck, and the average friction coefficient of the friction material should be controlled within a range of 0.30 to 0.80.

[0018] The present invention discloses the following technical effects:

[0019] The present invention improves the mechanical and friction and wear properties of aluminum-based friction materials by adding Cr and Ce and performing annealing and quenching treatment. When the atomic percentages of the three metal elements Al, Cr and Ce are 81.0%, 14.5% and 4.5% respectively and after vacuum melting, vacuum annealing at 800°C for 360h and quenching, Al4Cr, Al 20 Aluminum-based friction material composed of Cr2Ce and Al8Cr4Ce. Among them, Al4Cr as a hard phase can significantly improve the hardness of the material. 20 Cr2Ce and Al8Cr4Ce make the material have high hardness and tensile strength while also having good high-temperature stability. The synergistic effect of the three phases makes it have good application value in the field of brake discs for heavy trucks. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 is the XRD pattern of Example 2 of the present invention;

[0022] Figure 2 This is a tissue morphology diagram of Example 2 of the present invention;

[0023] Figure 3 This is a microscopic morphology diagram of Example 2 of the present invention after wear;

[0024] Figure 4 This is a super-depth three-dimensional topography image of the wear scar of Example 2 of the present invention;

[0025] Figure 5 The friction coefficient curves of Examples 1 and 2 of the present invention are shown;

[0026] Figure 6 Graph showing the average friction coefficient and volume wear rate of Examples 1 and 2 of the present invention. DETAILED DESCRIPTION

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0028] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the stated range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0029] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation and testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0030] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention without departing from the scope or spirit of the present invention.The present invention description and examples are intended to be exemplary only.

[0031] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended words, meaning including but not limited to.

[0032] Example 1

[0033] (1) Weigh 0.644 g of high-purity metal elements Al, 0.253 g of Cr, and 0.103 g of Ce (atomic percentages are 81.0%, 16.5%, and 2.5%, respectively). First, place Al and Ce at the bottom of the crucible to reduce the volatilization of low-melting-point Al, then place Cr on the top to ensure its complete melting, and finally place high-purity titanium particles in the crucible for oxygen absorption. Close the vacuum arc furnace door and tighten the knob.

[0034] (2) Evacuate the vacuum arc furnace to 5×10 -3 Pa, then introduce argon into the furnace to make the pressure inside the furnace reach 0.8-0.9 standard atmospheres, and repeat this step 5 times;

[0035] (3) Adjust the smelting current to 40-100A. Before smelting, smelt the high-purity titanium particles first, then smelt each metal element and turn it over continuously. Repeat this step 5 times, and finally cool it with the furnace.

[0036] (4) The cooled sample is placed in a vacuum annealing furnace at 800° C. for annealing for 360 hours, and then placed in water for quenching. After completion, the desired aluminum-based friction material is obtained. The material prepared in this embodiment is recorded as sample L1.

[0037] Take sample L1 and use HRA-150 Rockwell hardness tester to test the hardness of the material. The hardness test points of each sample are 5 points evenly distributed on the entire sample surface, and the average value is taken as the hardness of the sample.

[0038] Take sample L1 and test its friction and wear performance on CFT-I friction and wear testing machine. The sample is a Φ8mm×4mm cylinder, and the counterpart is an AISI-45 steel ball with a diameter of 6mm. The Rockwell hardness is 25HRC. Before the test, the sample and the counterpart are polished with sandpaper and cleaned with alcohol to improve the reliability of the data obtained during the test. The test is carried out at room temperature and dry friction conditions. The test load is 5N, the number of reciprocating times is 200t / min, the reciprocating length is 5mm, and the reciprocating time is 30min.

[0039] Example 2

[0040] High-purity metal single substances Al 0.612g, Cr 0.211g, and Ce 0.177g (atomic percentages are 81.0%, 14.5%, and 4.5%, respectively) were weighed respectively. The preparation process and characterization methods were the same as those in Example 1. The material prepared in this example was recorded as sample No. L2.

[0041] Example 3

[0042] High-purity metal single substances Al 0.583 g, Cr 0.174 g, and Ce 0.243 g (atomic percentages are 81.0%, 12.5%, and 6.5%, respectively) were weighed respectively. The preparation process and characterization methods were the same as those in Example 1. The material prepared in this example was recorded as sample No. L3.

[0043] Example 4

[0044] High-purity metal single substances Al 0.557 g, Cr 0.139 g, and Ce 0.304 g (atomic percentages are 81.0%, 10.5%, and 8.5%, respectively) were weighed respectively. The preparation process and characterization methods were the same as those in Example 1. The material prepared in this example was recorded as sample No. L4.

[0045] Example 5

[0046] High-purity metal single substances Al 0.533 g, Cr 0.108 g, and Ce 0.359 g (atomic percentages are 81.0%, 8.5%, and 10.5%, respectively) were weighed respectively. The preparation process and characterization methods were the same as those in Example 1. The material prepared in this example was recorded as sample No. L5.

[0047] Microstructure and performance characterization results

[0048] The XRD spectrum of the aluminum-based friction material prepared in Example 2 is shown in Figure 1 The microstructure of the aluminum-based friction material prepared in Example 2 is shown in Figure 2 The microscopic morphology of the aluminum-based friction material prepared in Example 2 after wear is shown in Figure 3 The ultra-depth three-dimensional morphology of the wear scar of the aluminum-based friction material prepared in Example 2 is shown in Figure 4 The friction coefficient curves of the aluminum-based friction materials prepared in Examples 1 and 2 are shown in Figure 5 The average friction coefficient and volume wear rate curves of the aluminum-based friction materials prepared in Examples 1 and 2 are shown in Figure 6 . Table 1 shows the test results of physical, mechanical and friction and wear properties of aluminum-based friction material samples LI to L5 obtained in Examples 1 to 5. It can be seen from the test results that the aluminum-based friction material prepared by vacuum annealing the Al-Cr-Ce ternary alloy at 800°C for 360 hours and quenching in water has the characteristics of low density, high hardness and average friction coefficient, and low volume wear rate, which meets the processing and use requirements. At the same time, it was found that when the atomic percentages of the three metal elements Al, Cr and Ce were 81.0%, 14.5% and 4.5% respectively, Al4Cr, Al2O3 and Al4O3 could be stably obtained. 20 The aluminum-based friction material composed of Cr2Ce and Al8Cr4Ce three phases has the best mechanical and friction and wear properties at this time.

[0049] Table 1 Physical, mechanical and friction and wear properties of friction materials

[0050]

[0051] As can be seen from the above examples, the present invention can stably obtain Al4Cr, Al4Cr and Ce by adding three metal elements and controlling their atomic percentages to 81.0%, 14.5% and 4.5% respectively, and then vacuum melting, vacuum annealing at 800℃ for 360h and quenching in water. 20 Aluminum-based friction materials with a three-phase structure of Cr2Ce and Al8Cr4Ce. Under this condition, the material has the advantages of low density, high hardness and average friction coefficient, good friction stability and low volume wear rate, and has good application value in the field of brake discs for heavy trucks.

[0052] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A highly wear-resistant aluminum-based friction material for heavy trucks and a preparation method thereof, characterized in that: The preparation comprises the following steps: (1) Weigh the metal elements in order according to the atomic percentage of 70% to 90% Al, 0% to 20% Cr, and 0% to 20% Ce; (2) Place the metal elements in a water-cooled copper mold crucible in a non-consumable vacuum arc melting furnace, place high-purity titanium particles in the crucible for oxygen absorption, close the vacuum arc furnace door, and tighten the knob (3) evacuate the vacuum arc furnace, and then introduce argon gas into the furnace, and repeat this step 5 times; (4) Adjust the melting current, melt the high-purity titanium particles before melting, and then melt each metal element and continuously turn it over, repeat this step 5 times, and finally cool it with the furnace; (5) Place the cooled sample in an annealing furnace for annealing treatment, and then quench it to obtain the desired aluminum-based friction material.

2. A highly wear-resistant aluminum-based friction material for heavy trucks and a preparation method thereof according to claim 1, characterized in that: The metal element in step (1) is in the form of blocks, flakes or granules with a purity of 99.9%, and the average particle size of the metal element is ≤2 mm.

3. The high wear-resistant aluminum-based friction material for heavy trucks and the preparation method thereof according to claim 1, characterized in that: The vacuum degree of the vacuum arc furnace in step (3) should reach 5×10 -3 Pa, after the introduction of argon, the pressure in the furnace should reach 0.8-0.9 standard atmospheric pressure.

4. The high wear-resistant aluminum-based friction material for heavy trucks and the preparation method thereof according to claim 1, characterized in that: The smelting current in step (4) is in the range of 40 to 100 A, the smelting time of high-purity titanium particles is 1 to 2 minutes, and the smelting time of metal elements is 30 to 45 seconds.

5. The highly wear-resistant aluminum-based friction material for heavy trucks and the preparation method thereof according to claim 1, characterized in that: The annealing environment in step (5) is a vacuum state, the annealing temperature is 800° C., the annealing time is 360 h, and the quenching medium is water.

6. A highly wear-resistant aluminum-based friction material for heavy trucks as claimed in any one of claims 1 to 5 and an aluminum-based friction material obtained by the preparation method thereof.

7. The aluminum-based friction material prepared according to claims 1 to 7 is used in the field of heavy truck brake discs.

Images