Method for preparing high-strength and high-conductivity electrical round aluminum rod through powder metallurgy technology

Abstract

The invention discloses a method for preparing a high-strength and high-conductivity electrical round aluminum rod through a powder metallurgy technology. The method comprises the steps of raw material preparation, powder preparation, powder shaping, sintering densification and heat treatment. The aluminum alloy powder is prepared from high-purity raw materials through an inert gas atomization method, the content of impurity elements is effectively reduced, the powder purity is improved, and a foundation is laid for obtaining high-conductivity products; the laser melting technology and the sintering mold are adopted for forming, rapid melting and accurate forming of aluminum alloy powder are achieved, and the defects of stress concentration, cracks and the like generated in the traditional pressing forming process are overcome; through optimization of sintering process parameters, complete densification of the aluminum alloy is realized, and in combination with a subsequent heat treatment process, crystal grains are refined, and the strength and the electric conductivity of a product are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-ferrous metal processing, and particularly relates to a method for preparing high-strength and high-conductivity electrical round aluminum rods by powder metallurgy technology. Background Art

[0002] Electrical round aluminum rods are important basic materials in power transmission and the electronics industry, and their performance directly affects power transmission efficiency and the performance of electronic devices. Traditional electrical round aluminum rods are mostly produced by the casting-rolling process, which has problems such as coarse grains and composition segregation, making it difficult to meet the increasingly demanding application requirements in terms of strength, conductivity, etc.

[0003] Powder metallurgy technology has advantages such as uniform composition, fine structure, and near-net shape, providing a new approach for preparing high-performance electrical round aluminum rods. However, there are still the following problems in using powder metallurgy technology to prepare electrical round aluminum rods in the prior art: the purity of aluminum alloy powder is not high, the content of impurity elements is high, affecting the conductivity of the final product; oxides and other inclusions are easily introduced during the powder metallurgy process, reducing the product performance; it is difficult to achieve complete densification of aluminum alloy by traditional sintering processes, affecting the strength and conductivity of the product. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing high-strength and high-conductivity electrical round aluminum rods by powder metallurgy technology to solve the above problems.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A method for preparing high-strength and high-conductivity electrical round aluminum rods by powder metallurgy technology, comprising the following steps: S1. Raw material preparation: Including high-purity aluminum ingots, Zr element and rare earth elements, the content of Zr element is 0.01 - 0.2 wt%, the rare earth elements are one or two of La and Ce, the sum of the contents of the rare earth elements is 0.10 - 0.30 wt%, and the balance is Al; S2. Powder preparation: Using the inert gas atomization method to prepare rare earth-Zr aluminum alloy powder from the raw materials prepared in S1, controlling the powder particle size within 15 - 53 μm, and screening and impurity removal treatment on the powder; S3. Powder shaping: Loading the aluminum alloy powder obtained from S2 into a powder bed, selectively melting the powder by laser melting technology, and forming with a sintering mold to obtain an aluminum alloy blank; S4. Sintering densification: Placing the aluminum alloy blank obtained from S3 in a vacuum sintering furnace, sintering at 580 - 620 °C, and holding for 2 - 4 h; S5. Heat treatment: The aluminum alloy billet obtained in S4 is annealed at an annealing temperature of 350 - 450 °C for 1 - 3 h, and then cooled in the furnace to complete the recrystallization of the aluminum alloy, obtaining a high-strength and high-conductivity electrical round aluminum rod.

[0006] To further implement the present invention, the purity of the high-purity aluminum ingot described in S1 is 99.99%.

[0007] To further implement the present invention, the rare earth element described in S1 is one or both of La and Ce. When the rare earth elements are La and Ce, the content ratio of La and Ce is 1:1.

[0008] To further implement the present invention, the inert gas described in S2 is high-purity argon with a purity of 99.999%.

[0009] To further implement the present invention, the atomization pressure of the atomization method described in S2 is 3 - 5 MPa, and the atomization temperature is 700 - 800 °C.

[0010] To further implement the present invention, the laser melting process parameters described in S3 are: laser power 300 - 500 W, scanning speed 100 - 300 mm / s, and scanning spacing 0.05 - 0.1 mm.

[0011] To further implement the present invention, the vacuum degree of the vacuum sintering furnace described in S4 is ≤ 1 × 10 -3 Pa.

[0012] The beneficial effects of the present invention compared with the prior art are as follows: The present invention uses high-purity raw materials and an inert gas atomization method to prepare aluminum alloy powder, effectively reducing the content of impurity elements and improving the powder purity, laying a foundation for obtaining high-conductivity products; The present invention uses laser melting technology and sintering die forming to achieve rapid melting and precise forming of aluminum alloy powder, avoiding defects such as stress concentration and cracks generated during traditional pressing forming; The present invention realizes the complete densification of aluminum alloy by optimizing the sintering process parameters, and combines with subsequent heat treatment processes to refine the grains and improve the strength and conductivity of the products.

[0013] The present invention obtains a high-performance electrical round aluminum rod with a tensile strength greater than 120 MPa and a conductivity greater than 63% IACS by optimizing the alloy composition, improving the powder purity, and improving the forming and sintering processes. Specific Embodiments

[0014] The present invention will be further described below in conjunction with specific embodiments.

[0015] A method for preparing a high-strength and high-conductivity electrical round aluminum rod using powder metallurgy technology includes the following steps: S1. Raw material preparation: It includes high-purity aluminum ingots with a purity of 99.99%, Zr element and rare earth elements. The content of Zr element is 0.01-0.2 wt%, the sum of the contents of rare earth elements is 0.1-0.3 wt%. When the rare earth elements are La and Ce, the content ratio of La and Ce is 1:1, and the balance is Al; S2. Powder preparation: Using high-purity argon with a purity of 99.999%, the raw materials prepared in S1 are prepared into rare earth-Zr aluminum alloy powder by atomization method. The atomization pressure of the atomization method is 3-5 MPa, the atomization temperature is 700-800 °C, the powder particle size is controlled within 15-53 μm, and the powder is screened and impurity-removed; S3. Powder shaping: The aluminum alloy powder obtained by S2 treatment is loaded into a powder bed, and the powder is selectively melted by laser melting technology. The laser melting process parameters are: laser power 300-500 W, scanning speed 100-300 mm / s, scanning spacing 0.05-0.1 mm, and it is formed by using a sintering mold to obtain an aluminum alloy blank; S4. Sintering densification: The aluminum alloy blank obtained in S3 is placed in a vacuum sintering furnace, and the vacuum degree of the vacuum sintering furnace is ≤1×10 -3 Pa, sintered at 580-620 °C, and kept warm for 2-4 h; S5. Heat treatment: The aluminum alloy blank obtained in S4 is annealed. The annealing temperature is 350-450 °C, kept warm for 1-3 h, and then cooled with the furnace to complete the recrystallization of the aluminum alloy, obtaining a high-strength and high-conductivity electrical round aluminum rod.

[0016] Example 1: S1. Raw material preparation: It includes high-purity aluminum ingots with a purity of 99.99%, Zr element and rare earth elements. The content of Zr element is 0.05 wt%, the rare earth elements are La and Ce, the content of La is 0.1 wt%, the content of Ce is 0.1 wt%, and the balance is Al; S2. Powder preparation: Using high-purity argon with a purity of 99.999%, the raw materials prepared in S1 are prepared into rare earth-Zr aluminum alloy powder by atomization method. The atomization pressure of the atomization method is 4 MPa, the atomization temperature is 750 °C, the powder particle size is controlled within 15-53 μm, and the powder is screened and impurity-removed; S3. Powder shaping: Load the aluminum alloy powder obtained from S2 into the powder bed, and selectively melt the powder using laser melting technology. The laser melting process parameters are: laser power 400 W, scanning speed 200 mm / s, scanning spacing 0.08 mm, and use a sintering mold to form an aluminum alloy blank with a diameter of 9.5 mm; S4. Sintering densification: Place the aluminum alloy blank obtained from S3 in a vacuum sintering furnace. The vacuum degree of the vacuum sintering furnace is ≤1×10 -3 Pa, sinter at 600 °C, and hold for 3 h; S5. Heat treatment: Anneal the aluminum alloy blank obtained from S4. The annealing temperature is 400 °C, hold for 2 h, and then cool with the furnace to complete the recrystallization of the aluminum alloy, obtaining a high-strength and high-conductivity electrical round aluminum rod.

[0017] Example 2: S1. Raw material preparation: It includes high-purity aluminum ingots with a purity of 99.99%, Zr element and rare earth element. The content of Zr element is 0.1 wt%, the rare earth element is La, the content of La is 0.2 wt%, and the balance is Al; S2. Powder preparation: Use high-purity argon with a purity of 99.999% to prepare rare earth-Zr aluminum alloy powder from the raw materials prepared in S1 by atomization method. The atomization pressure of the atomization method is 4 MPa, the atomization temperature is 750 °C, the powder particle size is controlled within 15 - 53 μm, and the powder is screened and impurity-removed; S3. Powder shaping: Load the aluminum alloy powder obtained from S2 into the powder bed, and selectively melt the powder using laser melting technology. The laser melting process parameters are: laser power 350 W, scanning speed 250 mm / s, scanning spacing 0.06 mm, and use a sintering mold to form an aluminum alloy blank with a diameter of 9.5 mm; S4. Sintering densification: Place the aluminum alloy blank obtained from S3 in a vacuum sintering furnace. The vacuum degree of the vacuum sintering furnace is ≤1×10 -3 Pa, sinter at 620 °C, and hold for 2.5 h; S5. Heat treatment: Anneal the aluminum alloy blank obtained from S4. The annealing temperature is 420 °C, hold for 1.5 h, and then cool with the furnace to complete the recrystallization of the aluminum alloy, obtaining a high-strength and high-conductivity electrical round aluminum rod.

[0018] Example 3: A method for preparing a high-strength and high-conductivity electrical round aluminum rod using powder metallurgy technology, including the following steps: S1. Raw material preparation: It includes high-purity aluminum ingots with a purity of 99.99%, Zr element and rare earth elements. The content of Zr element is 0.01 wt%, the rare earth element is Ce, the content of Ce is 0.30 wt%, and the balance is Al; S2. Powder preparation: Using high-purity argon with a purity of 99.999%, the raw materials prepared in S1 are prepared into rare earth-Zr aluminum alloy powder by atomization method. The atomization pressure of the atomization method is 3 MPa, the atomization temperature is 700 °C, the powder particle size is controlled within 15 - 53 μm, and the powder is screened and impurity-removed; S3. Powder shaping: The aluminum alloy powder obtained from S2 is loaded into the powder bed, and the powder is selectively melted using laser melting technology. The laser melting process parameters are: laser power 500 W, scanning speed 100 mm / s, scanning spacing 0.08 mm, and it is formed using a sintering mold to obtain an aluminum alloy blank; S4. Sintering densification: The aluminum alloy blank obtained from S3 is placed in a vacuum sintering furnace, and the vacuum degree of the vacuum sintering furnace is ≤ 1×10 -3 Pa, sintered at 600 °C, and kept warm for 3 h; S5. Heat treatment: The aluminum alloy blank obtained from S4 is annealed. The annealing temperature is 400 °C, kept warm for 2 h, and then cooled in the furnace to complete the recrystallization of the aluminum alloy, obtaining a high-strength and high-conductivity electrical round aluminum rod.

[0019] Example 4: A method for preparing a high-strength and high-conductivity electrical round aluminum rod using powder metallurgy technology, including the following steps: S1. Raw material preparation: It includes high-purity aluminum ingots with a purity of 99.99%, Zr element and rare earth elements. The content of Zr element is 0.01 - 0.2 wt%, the rare earth elements are La and Ce, the content of both La and Ce is 0.05 wt%, and the balance is Al; S2. Powder preparation: Using high-purity argon with a purity of 99.999%, the raw materials prepared in S1 are prepared into rare earth-Zr aluminum alloy powder by atomization method. The atomization pressure of the atomization method is 3 MPa, the atomization temperature is 700 °C, the powder particle size is controlled within 15 - 53 μm, and the powder is screened and impurity-removed; S3. Powder shaping: The aluminum alloy powder obtained from S2 is loaded into the powder bed, and the powder is selectively melted using laser melting technology. The laser melting process parameters are: laser power 300 W, scanning speed 100 mm / s, scanning spacing 0.05 mm, and it is formed using a sintering mold to obtain an aluminum alloy blank; S4, Sintering densification: Place the aluminum alloy billet obtained in S3 into a vacuum sintering furnace. The vacuum degree of the vacuum sintering furnace ≤ 1×10 -3 Pa, sinter at 580 °C, and keep the temperature for 2 h; S5, Heat treatment: Anneal the aluminum alloy billet obtained in S4. The annealing temperature is 350 °C, keep the temperature for 1 h, and then cool with the furnace to complete the recrystallization of the aluminum alloy, obtaining a high-strength and high-conductivity electrical round aluminum rod.

[0020] Example 5: A method for preparing a high-strength and high-conductivity electrical round aluminum rod using powder metallurgy technology, including the following steps: S1, Raw material preparation: It includes high-purity aluminum ingots with a purity of 99.99%, Zr element and rare earth elements. The content of Zr element is 0.01 - 0.2 wt%, the rare earth elements are La and Ce, and the contents of both La and Ce are 0.15 wt%, and the balance is Al; S2, Powder preparation: Use high-purity argon with a purity of 99.999% to prepare rare earth-Zr aluminum alloy powder from the raw materials prepared in S1 by atomization method. The atomization pressure of the atomization method is 5 MPa, the atomization temperature is 800 °C, the powder particle size is controlled within 15 - 53 μm, and the powder is screened and impurity-removed; S3, Powder shaping: Load the aluminum alloy powder obtained in S2 into a powder bed, selectively melt the powder using laser melting technology. The laser melting process parameters are: laser power 500 W, scanning speed 300 mm / s, scanning spacing 0.1 mm, and use a sintering mold to form, obtaining an aluminum alloy billet; S4, Sintering densification: Place the aluminum alloy billet obtained in S3 into a vacuum sintering furnace. The vacuum degree of the vacuum sintering furnace ≤ 1×10 -3 Pa, sinter at 620 °C, and keep the temperature for 4 h; S5, Heat treatment: Anneal the aluminum alloy billet obtained in S4. The annealing temperature is 450 °C, keep the temperature for 3 h, and then cool with the furnace to complete the recrystallization of the aluminum alloy, obtaining a high-strength and high-conductivity electrical round aluminum rod.

[0021] Comparative example 1: Prepare an electrical round aluminum rod using the traditional melting-casting - rolling process, and its composition is Al-0.1La-0.05Ce-0.05Zr (wt%).

[0022] Conduct performance tests on the electrical round aluminum rods prepared in Examples 1 - 5 and Comparative example 1, and the results are shown in Table 1.

[0023] As can be seen from Table 1, when the round aluminum rods for electrical engineering prepared in Examples 1-5 of the present invention are compared with those in Comparative Example 1, the tensile strength and electrical conductivity of Examples 1-5 are significantly higher than those in Comparative Example 1, indicating that the technical solution provided by the present invention can effectively improve the performance of the round aluminum rods for electrical engineering.

Claims

1. A method for preparing high-strength and high-conductivity electrical round aluminum rods using powder metallurgy technology, characterized in that The steps include: S1. Raw material preparation: It includes high-purity aluminum ingot, Zr element and rare earth element, wherein the Zr element content is 0.01-0.2wt%, the sum of the rare earth element content is 0.10-0.30wt%, and the balance is Al; S2. Powder preparation: The raw material prepared by S1 is prepared into rare earth-Zr aluminum alloy powder by inert gas atomization method, the powder particle size is controlled at 15-53 μm, and the powder is screened and impurity-removed; S3. Powder shaping: The aluminum alloy powder obtained by the S2 treatment is loaded into a powder bed, the powder is selectively melted by laser melting technology, and formed by a sintering mold to obtain an aluminum alloy blank; S4, sintering densification: The aluminum alloy blank obtained in S3 is placed in a vacuum sintering furnace and sintered at 580-620°C for 2-4 hours; S5. Heat treatment: The aluminum alloy blank obtained by S4 is annealed at a temperature of 350-450°C for 1-3 hours, and then cooled with the furnace to complete the recrystallization of the aluminum alloy to obtain a high-strength and high-conductivity electrical round aluminum rod.

2. The method for preparing high-strength and high-conductivity electrical round aluminum rod by powder metallurgy technology as claimed in claim 1, characterized in that: The purity of the high-purity aluminum ingot described in S1 is 99.99%.

3. The method for preparing high-strength and high-conductivity electrical round aluminum rod by powder metallurgy technology as claimed in claim 1 or 2, characterized in that: The rare earth element in S1 is one or two of La and Ce. When the rare earth elements are La and Ce, the content ratio of La to Ce is 1:

1.

4. The method for preparing high-strength and high-conductivity electrical round aluminum rod by powder metallurgy technology as claimed in claim 3, characterized in that: The inert gas described in S2 is high-purity argon gas with a purity of 99.999%.

5. The method for preparing high-strength and high-conductivity electrical round aluminum rod by powder metallurgy technology as claimed in claim 4, characterized in that: The atomization pressure of the atomization method described in S2 is 3-5 MPa, and the atomization temperature is 700-800°C.

6. The method for preparing high-strength and high-conductivity electrical round aluminum rod by powder metallurgy technology as claimed in claim 5, characterized in that: The laser melting process parameters described in S3 are: laser power 300-500 W, scanning speed 100-300 mm / s, and scanning spacing 0.05-0.1 mm.

7. The method for preparing high-strength and high-conductivity electrical round aluminum rod by powder metallurgy technology as claimed in claim 6, characterized in that: The vacuum degree of the vacuum sintering furnace in S4 is ≤1×10 -3 Pa.

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