Aluminum alloy and preparation method therefor, and motor rotor

Abstract

The present application provides an aluminum alloy and a preparation method therefor, and a motor rotor. The aluminum alloy comprises the following components in percentage by mass: 0.38-0.60% of Si, not more than 0.15% of Fe, not more than 0.05% of Cu, not more than 0.05% of Zn, 0.005-0.01% of Ti, not more than 0.03% of Ga, 0.01-0.1% of Sm, 0.005-0.05% of Er, 0.5-0.8% of Mg, and the balance being Al and other elements, the total amount of the other elements is less than 0.1%, and the content of each of the other elements is less than 0.01%. The high-temperature yield strength of the aluminum alloy provided by the present application can be improved while keeping good conductivity by means of rational proportioning of all the element components, and when the aluminum alloy is used for preparing a motor rotor of an electric vehicle, the obtained motor rotor can run for a long time under the conditions of high rotating speed and high acceleration and is not prone to deformation or failure.

Description

An aluminum alloy and its preparation method, and an electric motor rotor

[0001] This application claims priority to Chinese Patent Application No. 202411510386.0, filed on October 28, 2024, entitled "An Aluminum Alloy and Its Preparation Method, Motor Rotor", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of aluminum alloy materials technology, and in particular to an aluminum alloy and its preparation method, and an electric motor rotor. Background Technology

[0003] Aluminum's electrical and thermal conductivity are second only to silver, copper, and gold among metals. Compared to silver, copper, and gold, aluminum is not only abundant in resources and inexpensive, but also has the highest thermal and electrical conductivity per unit weight, making its lightweight advantage very obvious.

[0004] Ordinary motors typically operate at speeds below 3000 rpm, and their rotors are made of pure aluminum (Al99.70). However, the drive motors for electric vehicles have already exceeded 10,000 rpm and are moving towards 30,000 rpm or even higher speeds, which is 10 to 40 times faster than ordinary motors. Although pure aluminum has strong electrical conductivity, it has low strength and can no longer meet the mechanical performance requirements of high-speed motors. At the same time, the higher the rotor speed, the longer the rotor operates at high temperatures. Therefore, high-speed motors also have higher requirements for the high-temperature performance of materials.

[0005] Application content

[0006] This application provides an aluminum alloy whose high-temperature yield strength can be improved by reasonably proportioning its components while maintaining good electrical conductivity.

[0007] This application also provides a method for preparing the above-mentioned aluminum alloy, which is capable of preparing the above-mentioned aluminum alloy and has a simple process.

[0008] This application also provides a motor rotor, which, because it is made of the aforementioned aluminum alloy, is able to operate under high speed and high acceleration conditions without easily deforming or failing.

[0009] In a first aspect, this application provides an aluminum alloy, comprising, by mass percentage: 0.38-0.60% Si, not more than 0.15% Fe, not more than 0.05% Cu, not more than 0.05% Zn, 0.005-0.01% Ti, not more than 0.03% Ga, 0.01-0.1% Sm, 0.005-0.05% Er, 0.5-0.8% Mg, and the balance Al and other elements, wherein the total amount of the other elements is less than 0.1%, and the individual content of the other elements is less than 0.01%.

[0010] Furthermore, its composition includes: 0.42-0.46% Si, 0.68-0.75% Fe, 0.004-0.006% Cu, 0.015-0.020% Zn, 0.005-0.007% Ti, 0.012-0.015% Ga, 0.04-0.1% Sm, and 0.02-0.05% Er.

[0011] Furthermore, it contains 0.42-0.45% Si, 0.69-0.72% Fe, 0.004-0.006% Cu, 0.017-0.018% Zn, 0.005-0.007% Ti, 0.013-0.014% Ga, 0.04-0.1% Sm, and 0.02-0.05% Er.

[0012] Furthermore, the other elements include V and / or Cr, the total amount of V and Cr accounting for m of the mass of the aluminum alloy, where m ≤ 0.008%.

[0013] Furthermore, 0.0035≤m≤0.0037.

[0014] Secondly, this application provides a method for preparing an aluminum alloy, comprising the following steps:

[0015] 1) Mix raw materials other than Ti, Sm, and Er, and heat to 760-780℃ to obtain the first aluminum liquid;

[0016] 2) Add aluminum-boron alloy to the first aluminum liquid and let the aluminum liquid stand at temperature M℃ for 30-60 minutes to separate the solid and liquid phases and obtain the second aluminum liquid; wherein, the liquidus temperature of the first aluminum liquid is N℃, N℃+10℃≤M℃≤N℃+20℃;

[0017] 3) At 710-750℃, aluminum-titanium master alloy, aluminum-erbium master alloy, and aluminum-samarium master alloy are added to the second aluminum liquid, and after mixing treatment, a third aluminum liquid is obtained;

[0018] 4) The third aluminum liquid is refined and deslag removed, and then refined and degassed before being cast to obtain the aluminum alloy.

[0019] Furthermore, the refining and slag removal specifically includes the following processes:

[0020] At 710-750℃, a solid flux is sprayed into the third aluminum liquid, and after standing or stirring, the solids on the surface of the third aluminum liquid are removed.

[0021] Furthermore, the refining and degassing process includes the steps of introducing argon gas into the third molten aluminum at 700-740°C and allowing it to stand.

[0022] Furthermore, the casting process specifically includes the following steps:

[0023] After the third aluminum liquid is poured into the casting tank, argon gas is used to remove hydrogen. The hydrogen-removed third aluminum liquid is then filtered to remove impurities larger than 20 micrometers.

[0024] Thirdly, this application provides an electrode rotor made of an aluminum alloy prepared by the method of the first aspect or the method of the second aspect.

[0025] The aluminum alloy provided in this application, by reasonably proportioning the components of each element, can improve its high-temperature yield strength while maintaining good electrical conductivity. The electric motor rotor made of it can operate for a long time under high speed and high acceleration conditions without easily deforming or failing. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0027] Figure 1 is a process flow diagram of preparing aluminum alloy according to a specific embodiment of this application. Detailed Implementation

[0028] To enable those skilled in the art to better understand the solutions of this application, a further detailed description of this application is provided below. The specific embodiments listed below are merely descriptions of the principles and features of this application; the examples are only for explaining this application and are not intended to limit its scope. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0029] In a first aspect, this application provides an aluminum alloy, comprising, by mass percentage: 0.38-0.60% Si, not more than 0.15% Fe, not more than 0.05% Cu, not more than 0.05% Zn, 0.005-0.01% Ti, not more than 0.03% Ga, 0.01-0.1% Sm, 0.005-0.05% Er, 0.5-0.8% Mg, and the balance Al and other elements, wherein the total amount of the other elements is less than 0.1%, and the individual content of the other elements is less than 0.01%.

[0030] According to the aluminum alloy provided in this application, by controlling the proportion of each element in the aluminum alloy, the aluminum alloy has a high yield strength and electrical conductivity, and its yield strength remains at a high level even when the temperature rises to 180℃. Specifically, at room temperature, the yield strength of the aluminum alloy provided in this application is not less than 95 MPa, and at 180℃, its yield strength is not less than 90 MPa.

[0031] It should be noted that the other elements mentioned above refer to elements other than Si, Fe, Cu, Ti, Zn, Ga, Sm, Er, Mg, and Al.

[0032] In detail, the aluminum alloy of this application employs a combination of Ti and Er to refine the grains. This grain refinement strengthens and stabilizes the yield strength of the aluminum alloy. The reason for this is that, according to the Hall-Petch formula σ=σ0+k / d (1 / 2) Yield strength is inversely proportional to the square root of the grain diameter; that is, the finer the grain, the higher the yield strength. However, using Ti as a grain refining element will severely reduce the electrical conductivity of aluminum alloys. To ensure the electrical conductivity of aluminum alloys, only a small amount can be added, resulting in a weak grain refining effect. The resulting aluminum alloys not only have low yield strength but also poor yield strength stability. Therefore, this application utilizes elements such as Ti, Er, and Sm to form a metallic compound, which can not only ensure the electrical conductivity of aluminum alloys but also effectively prevent the yield strength decrease caused by grain deformation at high temperatures. On the other hand, since the aluminum alloy of this application includes the rare earth element Sm, it can reduce dissolved hydrogen in the aluminum alloy, thereby reducing the probability and size of pinhole formation in the casting, which is beneficial to improving the density of the casting, thereby improving the electrical conductivity and yield strength of the aluminum alloy.

[0033] To further ensure the high-temperature yield strength of the aluminum alloy, in one specific embodiment, its composition includes: 0.42-0.46% Si, 0.68-0.75% Fe, 0.004-0.006% Cu, 0.015-0.020% Zn, 0.005-0.007% Ti, 0.012-0.015% Ga, 0.04-0.1% Sm, and 0.02-0.05% Er.

[0034] In another specific embodiment, the composition includes 0.42-0.45% Si, 0.69-0.72% Fe, 0.004-0.006% Cu, 0.017-0.018% Zn, 0.005-0.007% Ti, 0.013-0.014% Ga, 0.04-0.1% Sm, and 0.02-0.05% Er.

[0035] In one specific embodiment, the other elements include V and / or Cr, and the total amount of V and Cr accounts for m of the mass ratio of the aluminum alloy, where m ≤ 0.008%. Since V and / or Cr exist in solid solution form, they increase the degree of lattice distortion in the aluminum alloy, hindering electron movement and thus reducing the conductivity of the aluminum alloy. Therefore, the total amount of V and Cr should not be too high, especially within the range of the above embodiments, to ensure that the conductivity of the aluminum alloy is not affected by V and Cr.

[0036] In one specific implementation, 0.0035 ≤ m ≤ 0.0037.

[0037] Secondly, this application provides a method for preparing the above-mentioned aluminum alloy, which, in conjunction with Figure 1, includes the following steps:

[0038] 1) Mix raw materials other than Ti, Sm, and Er, and heat to 760-780℃ to obtain the first aluminum liquid;

[0039] 2) Add aluminum-boron alloy to the first aluminum liquid and let the aluminum liquid stand at temperature M℃ for 30-60 minutes to separate the solid and liquid phases and obtain the second aluminum liquid; wherein, the liquidus temperature of the first aluminum liquid is N℃, N℃+10℃≤M℃≤N℃+20℃;

[0040] 3) At 710-750℃, aluminum-titanium master alloy, aluminum-erbium master alloy, and aluminum-samarium master alloy are added to the second aluminum liquid, and after mixing treatment, a third aluminum liquid is obtained;

[0041] 4) The third aluminum liquid is refined and deslag removed, and then refined and degassed before being cast to obtain the aluminum alloy.

[0042] The above-mentioned preparation method can obtain the aluminum alloy described in the first aspect by batch feeding and coordinating the processing temperature, slag removal, and hydrogen removal at each step. In detail, the above-mentioned preparation method first melts part of the raw materials at a certain temperature, and then uses the aluminum-boron alloy to react with impurity elements such as V in the aluminum liquid to form precipitates and remove them, thereby reducing the content of impurity elements. Secondly, the remaining raw materials are added at a certain temperature and subjected to slag removal and hydrogen removal treatment, so that the inclusions and hydrogen content in the third aluminum liquid are reduced to an extremely low level, thereby reducing the adverse effects of inclusions on the mechanical and electrical properties of the aluminum alloy.

[0043] It is understandable that the amount of aluminum-boron alloy added can be calculated based on the molecular weights of TiB2, VB2, CrB2, and ZrB2. If too much is added, the remaining B content should be less than 0.01% to avoid affecting the electrical conductivity of the aluminum alloy.

[0044] In one specific embodiment, the refining and slag removal specifically includes the following process:

[0045] At 710-750℃, a solid flux is sprayed into the third aluminum liquid, and after standing or stirring, the solids on the surface of the third aluminum liquid are removed.

[0046] In this process, a solid flux is sprayed into the third molten aluminum. As the solid flux liquefies and floats to the surface of the molten aluminum, it adsorbs metal oxides (alumina, silicon dioxide, magnesium oxide, etc.) from the molten aluminum, making them easier to remove later. For example, the solid flux can be a commonly used solid flux such as sodium chloride or potassium chloride. In some embodiments, the solid solvent is composed of sodium chloride, potassium chloride, sodium fluoroaluminate (Na3AlF6), and other salts. The total mass of sodium chloride and potassium chloride accounts for 50%-95% of the total weight of the solid solvent.

[0047] In one specific embodiment, the refining and degassing includes the steps of introducing argon gas into the third molten aluminum at 700-740°C and allowing it to stand.

[0048] Argon gas is introduced into the third aluminum liquid to form bubbles. Hydrogen in the aluminum liquid will enter the argon bubbles through permeation. During the settling process, hydrogen will float to the surface of the aluminum liquid and then enter the air.

[0049] In one specific embodiment, the casting process includes the following steps:

[0050] After the third aluminum liquid is poured into the casting tank, argon gas is used to remove hydrogen. The hydrogen-removed third aluminum liquid is then filtered to remove impurities larger than 20 micrometers.

[0051] The aforementioned argon dehydrogenation can be performed using rotary degassing, permeable brick degassing, or a combination of both.

[0052] In the above embodiments, filtration can be achieved by passing the third molten aluminum through two-stage ceramic filter plates of 30 and 40 mesh, respectively. The use of multi-stage ceramic filter plates can further filter out large-sized solid impurities such as alumina and magnesium oxide from the molten aluminum, thereby further improving the electrical conductivity of the aluminum alloy.

[0053] Thirdly, this application provides an electric motor rotor made of an aluminum alloy prepared by the method of the first aspect or the method of the second aspect.

[0054] It is understood that the motor rotor of this application can be used in various devices that need to convert electrical energy into mechanical energy or mechanical energy into electrical energy, including but not limited to: electric vehicles, hybrid vehicles, cranes, excavators, concrete mixers, subways, MRI scanners, CT scanners, surgical robots, etc.

[0055] In some embodiments, the aluminum alloy ingots are remelted, refined, and degassed: the aluminum ingots are added to the furnace side of the casting machine, completely melted into a liquid state, and then slag is removed and degassed; the rotor is then cast into a motor rotor using a centrifugal casting process. The centrifugal process includes the following steps:

[0056] Mold preparation: Select a suitable mold and fix it in the centrifugal casting machine.

[0057] Injecting molten metal: Start the equipment and fill the mold under centrifugal force.

[0058] Cooling and solidification: The liquid metal cools and solidifies inside the mold, forming a preliminary casting.

[0059] Post-processing: Cleaning, inspection, and necessary post-machining of the castings.

[0060] To further understand this application, the technical solutions of this application will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0061] Unless otherwise specified, all reagents involved in the embodiments of this application are commercially available products and can be purchased through commercial channels.

[0062] The specifications or sources of some of the raw materials involved in the following experiments are shown in Table 1.

[0063] Table 1:

[0064] Example 1

[0065] This example provides an aluminum alloy comprising: 0.422% Si, 0.071% Fe, 0.005% Cu, 0.018% Zn, 0.005% Ti, 0.014% Ga, 0.04% Sm, 0.02% Er, 0.061% Mg, V+Cr = 0.0037, and the balance Al.

[0066] Its preparation method includes the following steps:

[0067] 1) Mix electrolytic aluminum, magnesium ingots, and industrial silicon, preheat and melt them into a liquid state, and then raise the temperature to 760-780℃ to obtain the first aluminum liquid;

[0068] 2) Add aluminum-boron master alloy to the first aluminum liquid to generate heavy metal compounds such as TiB2 and VB2 from impurity elements Ti and V, and make the temperature of the aluminum liquid 10-20℃ higher than the liquidus temperature of the first aluminum liquid. Let it stand for 30-60 minutes to separate the solid and liquid and obtain the second aluminum liquid.

[0069] 3) At 750°C, aluminum-titanium master alloy, aluminum-erbium master alloy, and aluminum-samarium master alloy are added to the second aluminum liquid, and after mixing treatment, a third aluminum liquid is obtained;

[0070] 4) At 750℃, a solid flux is added to the third aluminum melt, the amount of which is 1-2% of the weight of the aluminum melt. After the solid flux liquefies, it floats to the surface of the melt and adsorbs metal oxides (alumina, silicon dioxide, magnesium oxide, etc.) in the aluminum melt, and is finally removed. Then, argon gas (argon flow rate of 15-25L / min) is introduced into the aluminum melt to form bubbles. Hydrogen in the aluminum melt will form argon bubbles under the action of permeation, float to the surface of the melt and enter the air.

[0071] 5) At 740℃, after the third aluminum liquid is poured into the casting channel, a second argon gas (argon flow rate of 15-25L / min) is used for hydrogen removal by rotary degassing. Then, the third aluminum liquid will pass through two-stage ceramic plate filters of 30 and 40 mesh respectively to completely filter out impurities larger than 20 micrometers in the aluminum liquid. Aluminum ingot casting and forming: the aluminum melt enters the aluminum ingot mold and solidifies into aluminum ingot.

[0072] Example 2-3

[0073] It is basically the same as Example 1, except that the composition of the aluminum alloy is different, as shown in Table 2.

[0074] Comparative Examples 1-3

[0075] It is basically the same as Example 1, except that the constituent elements or their contents of the aluminum alloy are different, as shown in Table 2.

[0076] Application examples

[0077] The aluminum alloys from the above embodiments and comparative examples are added to the furnace side of the casting machine and completely melted into a liquid state. Then, slag removal and degassing are performed. The rotor of the motor is cast using a centrifugal casting process. The centrifugal process includes the following steps: mold preparation: select a mold and fix it in the centrifugal casting machine; injection of molten metal: start the equipment and fill the mold under centrifugal force; cooling and solidification: the molten metal cools and solidifies in the mold to form a preliminary casting; post-processing: clean, inspect and process the casting.

[0078] Test case

[0079] The following performance tests were performed on the aluminum alloys of the examples and comparative examples:

[0080] 1: Electrical conductivity, tested using the eddy current method, referring to the national standard GB / T 12966-2022 "Eddy Current Test Method for Electrical Conductivity of Aluminum and Aluminum Alloys";

[0081] 2: Yield strength at room temperature, tested by tensile test, referring to national standard GB / T 228.1-2021 "Metallic materials, tensile testing - Part 1: Test at room temperature";

[0082] 3: Yield strength at 180℃, tested by tensile test, referring to national standard GB / T 228.2-2015 "Metallic materials, tensile testing - Part 2: High temperature test method".

[0083] Table 2:

[0084] As shown in Table 2, compared with the comparative example, the aluminum alloy of this application embodiment has good electrical conductivity and high temperature yield strength. Therefore, the motor rotor made of it can run for a long time under high speed and high acceleration conditions without easily deforming or failing.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An aluminum alloy, wherein, By mass percentage, its composition includes: 0.38-0.60% Si, not more than 0.15% Fe, not more than 0.05% Cu, not more than 0.05% Zn, 0.005-0.01% Ti, not more than 0.03% Ga, 0.01-0.1% Sm, 0.005-0.05% Er, 0.5-0.8% Mg, and the balance Al and other elements, wherein the total amount of the other elements is less than 0.1% and the individual content of the other elements is less than 0.01%.

2. The aluminum alloy according to claim 1, wherein, Its composition includes: 0.42-0.46% Si, 0.68-0.75% Fe, 0.004-0.006% Cu, 0.015-0.020% Zn, 0.005-0.007% Ti, 0.012-0.015% Ga, 0.04-0.1% Sm, and 0.02-0.05% Er.

3. The aluminum alloy according to claim 2, wherein, 0.42-0.45% Si, 0.69-0.72% Fe, 0.004-0.006% Cu, 0.017-0.018% Zn, 0.005-0.007% Ti, 0.013-0.014% Ga, 0.04-0.1% Sm, and 0.02-0.05% Er.

4. The aluminum alloy according to any one of claims 1-3, wherein, The other elements include V and / or Cr, and the total amount of V and Cr accounts for m of the mass of the aluminum alloy, where m ≤ 0.008%.

5. The aluminum alloy according to claim 4, wherein, 0.0035≤m≤0.0037。 6. A method for preparing an aluminum alloy as described in any one of claims 1-5, wherein, Includes the following steps: 1) Mix raw materials other than Ti, Sm, and Er, and heat to 760-780℃ to obtain the first aluminum liquid; 2) Add aluminum-boron alloy to the first aluminum liquid and let the aluminum liquid stand at temperature M℃ for 30-60 minutes to separate the solid and liquid phases and obtain the second aluminum liquid; wherein, the liquidus temperature of the first aluminum liquid is N℃, N℃+10℃≤M℃≤N℃+20℃; 3) At 710-750℃, aluminum-titanium master alloy, aluminum-erbium master alloy, and aluminum-samarium master alloy are added to the second aluminum liquid and mixed to obtain the third aluminum liquid; 4) The third aluminum liquid is refined and deslag removed, and then refined and degassed before being cast to obtain the aluminum alloy.

7. The preparation method according to claim 6, wherein, The refining and slag removal process specifically includes the following steps: At 710-750℃, a solid flux is sprayed into the third aluminum liquid, and after standing or stirring, the solids on the surface of the third aluminum liquid are removed.

8. The preparation method according to claim 6, wherein, The refining and degassing process includes the following steps: introducing argon gas into the third molten aluminum at 700-740°C and allowing it to stand.

9. The preparation method according to claim 6, wherein, The casting process specifically includes the following steps: After the third aluminum liquid is poured into the casting tank, argon gas is used to remove hydrogen. The hydrogen-removed third aluminum liquid is then filtered to remove impurities larger than 20 micrometers.

10. An electric motor rotor, wherein, The aluminum alloy is prepared by any of the aluminum alloys described in claims 1-5 or by any of the preparation methods described in claims 6-9.

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