Preparation method of high-conductivity cast Al-Mg-Si-graphene alloy and graphene alloy

Abstract

The invention discloses a preparation method of a high-conductivity cast Al-Mg-Si-graphene alloy, which comprises the following steps: by taking industrial pure Al, pure Mg, Al-50Si, Al-20Fe, Al-2Sc, Al-5Zr, Al-10Ti, Al-3B and Al-T i-B intermediate alloy and high-purity graphene as raw materials, smelting the raw materials in a temperature range of 720-750 DEG C, refining and degassing by adopting argon or C2Cl6 after the solution is uniform, and then carrying out heat treatment to obtain the high-conductivity cast Al-Mg-Si-graphene alloy. Adding a proper amount of Ti and B, and carrying out microalloying treatment to obtain a graphene mixed precast block; and then pressing the Al powder, NaF, CaF2 and graphene mixed precast block into the melt until the mixture is completely molten, and then casting and molding the alloy melt to obtain a corresponding high-voltage switch product. The requirement can be met by using common industrial pure Al, so that the raw material cost is greatly saved; in addition, the added graphene can improve the flowability and thermal cracking resistance of the alloy, reduce the thermal expansion coefficient of the alloy and improve the dimensional stability of the product.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy materials, and in particular to a preparation method of a highly conductive cast Al-Mg-Si-graphene alloy and a graphene alloy. Background Art

[0002] As the high-voltage power transmission industry develops towards high power and lightweight, the requirements for the conductivity of high-voltage switch materials are getting higher and higher. At present, high-voltage switches are mainly produced using ZL101 aluminum alloy; ZL101 is a hypoeutectic aluminum-silicon alloy with good casting formability, but its conductivity after T6 heat treatment is only about 40% IACS. The low conductivity of high-voltage switches during use will increase temperature rise and loss, greatly increasing the risk of accidents. At present, the only way to meet the use requirements is to increase the switch diameter, which not only increases production, transportation and installation costs, but also reduces the flexibility of switch use. The development of aluminum alloy materials with mechanical properties close to ZL101, conductivity ≥ 47% IACS and good casting properties is of great significance to the high-voltage power transmission industry.

[0003] Al-Mg-Si alloy with Mg2Si as the main strengthening phase has high mechanical properties and excellent electrical conductivity. For example, patent CN108866463B (a heat treatment process of low alloyed Al-Mg-Si alloy) reports an extruded Al-0.41Mg-0.46Si alloy with a tensile strength of 198.7MPa and an electrical conductivity of up to 55.9%IACS. However, Al-Mg-Si alloy is mainly used as a deformed aluminum alloy, and its casting formability is weaker than that of ZL101 alloy. It mainly has problems such as poor fluidity, easy thermal cracking, and large solidification shrinkage. Therefore, improving the casting performance of Al-Mg-Si alloy is an effective way to develop high-conductivity high-voltage switch materials. Summary of the invention

[0004] The object of the present invention is to provide a new microalloyed Al-Mg-Si-graphene alloy, which has good casting formability and can realize casting forming of high-voltage switch products. The alloy hardness is ≥70HBW and the electrical conductivity is ≥47%IACS.

[0005] According to one aspect of the present disclosure, the following technical solution is provided: a method for preparing a highly conductive cast Al-Mg-Si-graphene alloy, the preparation method comprising the following steps:

[0006] S1, using industrial pure Al, pure Mg, Al-50Si, Al-20Fe, Al-2Sc, Al-5Zr, Al-10Ti, Al-3B and Al-Ti-B master alloy and high-purity graphene as raw materials;

[0007] S2. The raw materials are mixed according to the following weight percentages: Mg 0.25%-0.9%, Si 0.3%-1.2%, the mass fraction of Mg and Si satisfies 1 / 3≤Mg / Si≤3, Fe 0.05-0.5%, Sc≤0.2%, Zr≤0.15%, Ti0.002%-0.025%, B 0.002%-0.08%, Mn+Cr+V≤0.01%, graphene 0.05-0.2%, other impurities individually ≤0.05%, total ≤0.15%, and the balance is aluminum;

[0008] S3, melting the above raw materials at a temperature range of 720°C-750°C;

[0009] S4, after the solution is uniform, argon or C2Cl6 is used for refining and degassing, and appropriate amounts of Ti and B are added for microalloying to obtain a graphene mixed prefabricated block;

[0010] S5, then pressing the prefabricated block of Al powder, NaF and CaF2 mixed with graphene into the melt until it is completely melted, and then casting the alloy melt to obtain a corresponding high-voltage switch product;

[0011] S6. subjecting the cast product to solid solution aging heat treatment.

[0012] Preferably, in step S6, the solution temperature is 500-550° C. and the time is 2-15 hours.

[0013] Preferably, in step S6, the aging temperature is 180-240° C., the time is 1-15 h, and the process is furnace-cooled or air-cooled.

[0014] Preferably, the refining and degassing time is 30 minutes.

[0015] Preferably, the mass ratio of the Al powder, NaF and CaF2 is Al:NaF:CaF2=2:1:1

[0016] A highly conductive cast Al-Mg-Si-graphene alloy, characterized by being an Al-Mg-Si-graphene alloy prepared by any of the above-mentioned preparation methods.

[0017] Technical effects and advantages of the present invention:

[0018] The present invention can use ordinary industrial pure Al to meet the requirements, greatly saving the cost of raw materials; in addition, the addition of graphene can improve the fluidity and thermal cracking resistance of the alloy, reduce the thermal expansion coefficient of the alloy, and improve the dimensional stability of the product;

[0019] The addition of NaF and CaF2 makes it easier to disperse graphene evenly, and can also purify the melt. In addition, during the solidification of the alloy, graphene is enriched at the front of the solid-liquid interface to inhibit dendrite growth, enhance the melt shrinkage capacity, and improve the fluidity of the alloy. Moreover, graphene can serve as a reinforcement bridge between adjacent grains, thereby improving the alloy's resistance to thermal cracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings illustrate exemplary embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification.

[0021] Figure 1 This is a solidification structure morphology diagram of the alloy obtained in Example 1 of the present invention.

[0022] Figure 2 This is a solidification structure morphology diagram of the alloy obtained in Example 2 of the present invention.

[0023] Figure 3 This is a solidification structure morphology diagram of the alloy obtained in Example 3 of the present invention.

[0024] Figure 4 It is a test data chart of alloys prepared in the embodiments of the present invention and the comparative examples. DETAILED DESCRIPTION

[0025] For descriptive purposes, the present disclosure may use spatially relative terms such as "under," "beneath," "under," "above," "on," "higher," and "side (e.g., as in "sidewall")," to describe the relationship of one component to another (other) component as shown in the accompanying drawings. The spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, components described as "under" or "beneath" other components or features would then be positioned "above" the other components or features. Thus, the exemplary term "under" can encompass both the "above" and "below" orientations. Furthermore, the device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0026] The present invention discloses a method for preparing a highly conductive cast Al-Mg-Si-graphene alloy, the preparation method comprising the following steps:

[0027] S1, using industrial pure Al, pure Mg, Al-50Si, Al-20Fe, Al-2Sc, Al-5Zr, Al-10Ti, Al-3B and Al-Ti-B master alloy and high-purity graphene as raw materials;

[0028] S2. The raw materials are mixed according to the following weight percentages: Mg 0.25%-0.9%, Si 0.3%-1.2%, the mass fraction of Mg and Si satisfies 1 / 3≤Mg / Si≤3, Fe 0.05-0.5%, Sc≤0.2%, Zr≤0.15%, Ti0.002%-0.025%, B 0.002%-0.08%, Mn+Cr+V≤0.01%, graphene 0.05-0.2%, other impurities individually ≤0.05%, total ≤0.15%, and the balance is aluminum;

[0029] S3, melting the above raw materials at a temperature range of 720°C-750°C;

[0030] S4, after the solution is uniform, argon or C2Cl6 is used for refining and degassing, and appropriate amounts of Ti and B are added for microalloying to obtain a graphene mixed prefabricated block;

[0031] S5, then pressing the prefabricated block of Al powder, NaF and CaF2 mixed with graphene into the melt until it is completely melted, and then casting the alloy melt to obtain a corresponding high-voltage switch product;

[0032] S6. subjecting the cast product to solid solution aging heat treatment.

[0033] Embodiment 1

[0034] Industrial pure Al (99.8%), pure Mg, Al-50Si, Al-20Fe, Al-2Sc, Al-5Zr and graphene are used as raw materials, and the raw material proportions are determined according to the target alloy composition Al-0.5Mg-0.5Si-0.1Fe-0.002(Sc+Zr)-0.05graphene.

[0035] The industrial pure aluminum ingot was melted and heated to 750°C, and Al-50Si, Al-20Fe, Al-2Sc, Al-5Zr and pure Mg were added in sequence. After the melt was uniform, 0.5% C2Cl6 was used for refining and degassing. After standing for 20 minutes, 0.2% Al-5Ti-1B was added. After 15 minutes, 0.05% graphene was added by melt shearing method, with a shear rate of 300r / min and a time of 5 minutes. Then, a uniformly mixed prefabricated block of Al powder, NaF and CaF2 (the mass ratio of the three is Al: NaF: CaF2 = 2:1:1) and graphene was pressed into the melt until it was completely melted. After that, the melt was poured into an iron mold and the product was obtained after solidification. The solidification structure photo of the alloy is shown in FIG. Figure 1shown.

[0036] The casting was subjected to T6 heat treatment, solution treatment at 540°C for 15 h, water quenching, aging at 180°C for 15 h, and air cooling.

[0037] The Brinell hardness of the material is tested to be 79 HBW, and the electrical conductivity is 53% IACS.

[0038] Example 2 uses industrial pure Al (99.8%), pure Mg, Al-50Si, Al-20Fe, Al-2Sc, Al-5Zr and graphene as raw materials, and the raw materials are proportioned according to the target alloy composition Al-0.5Mg-0.55Si-0.15Fe-0.005(Sc+Zr)-0.1graphene.

[0039] The industrial pure aluminum ingot is melted and heated to 750°C, and Al-50Si, Al-20Fe, Al-2Sc, Al-5Zr and pure Mg are added in sequence. After the melt is uniform, it is refined with argon for 30 minutes, and then 0.2% Al-5Ti-1B is added. After 15 minutes, 0.1% graphene is added by melt shearing method, with a shear rate of 500r / min and a time of 3 minutes. Then, a uniformly mixed prefabricated block of Al powder, NaF and CaF2 (the mass ratio of the three is Al: NaF: CaF2 = 2:1:1) and graphene is pressed into the melt until it is completely melted, and then the melt is poured into a sand mold and the product is obtained after solidification. The solidification structure photo of the alloy is shown in Figure 2. Figure 2 shown.

[0040] The casting was subjected to T6 heat treatment, solution treatment at 535°C for 4h, water quenching, aging at 220°C for 4h, and air cooling.

[0041] The Brinell hardness of the material is tested to be 73 HBW, and the electrical conductivity is 52% IAC.

[0042] Example 3 uses industrial pure Al (99.8%), pure Mg, Al-50Si, Al-20Fe, Al-2Sc, Al-5Zr and graphene as raw materials, and the raw materials are proportioned according to the target alloy composition Al-0.45Mg-0.8Si-0.1Fe-0.01(Sc+Zr)-0.15graphene.

[0043] The industrial pure aluminum ingot is melted and heated to 750℃, and Al-50Si, Al-20Fe, Al-2Sc, Al-5Zr and pure Mg are added in sequence. After the melt is uniform, it is refined with argon for 30 minutes, and then 0.2% Al-5Ti-1B is added. After 15 minutes, 0.1% graphene is added by melt shearing method, with a shear rate of 200r / min and a time of 10 minutes. Then, a uniformly mixed prefabricated block of Al powder, NaF and CaF2 (the mass ratio of the three is Al: NaF: CaF2 = 2:1:1) and graphene is pressed into the melt until it is completely melted, and then the melt is poured into an iron mold and the product is obtained after solidification. The solidification structure photo of the alloy is shown in Figure 2. Figure 3 shown.

[0044] The casting was subjected to T6 heat treatment, solution treatment at 535°C for 4h, water quenching, aging at 220°C for 4h, and air cooling.

[0045] Comparative Example 1

[0046] The ZL101 (Al-7Si-0.35Mg) alloy ingot was melted and heated to 750°C, refined with argon for 30 minutes, and then 0.2% Al-5Ti-1B was added. After standing for 15 minutes, the melt was poured into an iron mold and the product was obtained after solidification.

[0047] The casting was subjected to T6 heat treatment, solution treatment at 535°C for 4h, water quenching, aging at 220°C for 4h, and air cooling.

[0048] Comparative Example 2

[0049] The 6061 (Al-1Mg-0.6Si-0.3Cu-0.2Cr-0.2Fe) alloy ingot was melted and heated to 750°C, refined with argon for 30 minutes, and then 0.2% Al-5Ti-1B was added. After standing for 15 minutes, the melt was poured into an iron mold and the product was obtained after solidification.

[0050] The casting was subjected to T6 heat treatment, solution treatment at 535°C for 4h, water quenching, aging at 220°C for 4h, and air cooling.

[0051] The products obtained in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were tested for Brinell hardness and conductivity. The results are as follows: Figure 4 shown.

[0052] Graphene has excellent mechanical properties and conductivity. The addition of graphene can improve the fluidity and thermal cracking resistance of the alloy, reduce the thermal expansion coefficient of the alloy, and improve the dimensional stability of the product.

[0053] according to Figure 4 From the data, it can be seen that the electrical conductivity of the alloy in the embodiment is significantly higher than that of the alloy in the comparative example.

[0054] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments / methods or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0055] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0056] Those skilled in the art should understand that the above embodiments are only for the purpose of clearly illustrating the present disclosure, and are not intended to limit the scope of the present disclosure. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and these changes or modifications are still within the scope of the present disclosure.

Claims

1. A method for preparing a highly conductive cast Al-Mg-Si-graphene alloy, characterized in that: The preparation method comprises the following steps: S1, using industrial pure Al, pure Mg, Al-50Si, Al-20Fe, Al-2Sc, Al-5Zr, Al-10Ti, Al-3B and Al-Ti-B master alloy and high-purity graphene as raw materials; S2. The raw materials are mixed according to the following weight percentages: Mg 0.25%-0.9%, Si 0.3%-1.2%, the mass fraction of Mg and Si satisfies 1 / 3≤Mg / Si≤3, Fe 0.05-0.5%, Sc≤0.2%, Zr≤0.15%, Ti 0.002%-0.025%, B 0.002%-0.08%, Mn+Cr+V≤0.01%, graphene 0.05-0.2%, other impurities individually ≤0.05%, total ≤0.15%, and the balance is aluminum; S3, melting the above raw materials at a temperature range of 720°C-750°C; S4, after the solution is uniform, argon or C2Cl6 is used for refining and degassing, and appropriate amounts of Ti and B are added for microalloying to obtain a graphene mixed prefabricated block; S5, then pressing the prefabricated block of Al powder, NaF and CaF2 mixed with graphene into the melt until it is completely melted, and then casting the alloy melt to obtain a corresponding high-voltage switch product; S6. subjecting the cast product to solid solution aging heat treatment.

2. The method for preparing a highly conductive cast Al-Mg-Si-graphene alloy according to claim 1, characterized in that: In step S6, the solution temperature is 500-550° C. and the time is 2-15 hours.

3. The method for preparing a highly conductive cast Al-Mg-Si-graphene alloy according to claim 1, characterized in that: In step S6, the aging temperature is 180-240° C., the time is 1-15 hours, and the furnace or air cooling is performed.

4. The method for preparing a highly conductive cast Al-Mg-Si-graphene alloy according to claim 1, characterized in that: The refining and degassing time is 30 minutes.

5. The method for preparing a highly conductive cast Al-Mg-Si-graphene alloy according to claim 1, characterized in that: The mass ratio of the Al powder, NaF and CaF2 is Al:NaF:CaF2=2:1:

1.

6. A highly conductive cast Al-Mg-Si-graphene alloy, characterized in that: An Al-Mg-Si-graphene alloy prepared by the preparation method according to any one of claims 1 to 5.

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