A low-melting-point aluminum alloy material and its preparation method

Abstract

The present invention discloses a low-melting-point aluminum alloy material and a preparation method thereof, relating to the technical field of aluminum alloy material design and preparation. The present invention aims to reduce the melting point of the aluminum alloy, overcome the problems of high melting point of the existing aluminum alloy, high dipping temperature for hot-dip aluminized alloy, and high energy consumption in the production of hot-dip aluminized alloy coatings, and reduce the influence of hot dipping on the matrix structure and properties. The technical solution of the present invention is as follows: prepare AlZn alloy and SnPb alloy respectively according to the ratio; then prepare AlZnSnPb alloy from the prepared AlZn alloy and SnPb alloy according to the ratio. The lowest melting point of the AlZnSnPb series aluminum alloy prepared by the present invention is only 356.83 °C, and the melting temperature range is: 356.83 °C to 377.60 °C, that is, the liquidus point is 377.60 °C and the solidus point is 356.83 °C. This preparation method effectively reduces the melting point of the aluminum alloy, thereby reducing the dipping temperature of the hot-dip aluminized alloy, effectively reducing the energy consumption in the production of hot-dip aluminized alloy coatings, improving the quality of hot-dip aluminized alloy coatings, and promoting the wider application of hot-dip aluminized alloy coatings.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy materials and their preparation, and particularly relates to a low-melting-point aluminum alloy material and a preparation method thereof. Background Art

[0002] Aluminum alloys have good corrosion resistance. Usually, hot-dip plating technology is used to prepare aluminum or aluminum alloy coatings on the surface of steel to improve the corrosion resistance of steel. The melting point of pure aluminum is about 660°C. For hot-dip plating technology, the melting point of aluminum alloy is relatively high, and the hot-dip plating temperature of aluminum alloy is mostly higher than 570°C. If the melting point of the coating alloy is high, its hot-dip plating temperature is high. On the one hand, the high melting temperature of hot-dip plating molten metal results in large energy consumption and increased production costs; on the other hand, too high hot-dip plating temperature will have an adverse impact on the structure and properties of the base material, and the coating thickness, density and coating quality will also deteriorate. Therefore, reducing the melting point of aluminum alloy can effectively reduce the hot-dip plating temperature, thereby reducing energy consumption and production costs, and at the same time can improve the coating quality and reduce the impact of the hot-dip plating process on the structure and properties of the base material. Low-melting-point aluminum alloy materials have important value for their application in the field of hot-dip plating coatings, so they have very important research significance.

[0003] From the research and preparation methods of existing low-melting-point aluminum alloys, the main method to reduce the melting point of aluminum alloy is to add alloying elements to the Al matrix, and the main added elements include Si, Cu, Ge, Zn, Mg, etc. Low-melting-point aluminum alloys mainly include Al-Si alloys, Al-Si-Cu alloys, Al-Ge-Si alloys, Al-Si-Zn alloys, Al-Si-Cu-Ge alloys, Al-Si-Cu-Zn alloys, etc. Among them, the Al-Ge-Cu alloy has a relatively low melting point, about 418°C - 426°C. Due to the relatively high melting point of aluminum alloy used for hot-dip plating, its hot-dip plating temperature is relatively high. At present, the hot-dip plating temperature of aluminum alloy exceeds the phase transformation points of many steel materials or other metal materials, which limits its application, such as many age-hardening steels and neodymium-iron-boron permanent magnets. For most age-hardening steels, their aging temperature is lower than 500°C, while the current hot-dip plating temperature of aluminum alloy is mostly higher than 570°C, higher than the phase transformation temperature of age-hardening steels. Therefore, it limits the application of hot-dip plating aluminum alloy coatings in the field of age-hardening steels. Neodymium-iron-boron permanent magnets are prepared by sintering, and their surfaces are prone to rust. Therefore, surface protection treatment is required for them. Hot-dip plating aluminum alloy coatings are an efficient surface protection technology, but due to the Curie point temperature of neodymium-iron-boron permanent magnets being about 380°C, the hot-dip plating temperature of aluminum alloy is higher than this temperature, which limits the application of hot-dip plating aluminum alloy coatings in the field of surface coatings for neodymium-iron-boron permanent magnets. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing a low-melting-point aluminum alloy material to overcome the problems of high melting point of the existing aluminum alloy for hot-dip plating, high dipping temperature for hot-dip plating of aluminum alloy, and high energy consumption in the production of hot-dip aluminum coatings.

[0005] In order to achieve the object of the present invention, the technical solution provided by the present invention is as follows: The present invention provides a method for preparing a low-melting-point aluminum alloy material, which includes the following steps:

[0006] Step 1, preparing an AlZn alloy: The nominal composition is proportioned according to the mass ratio of Al and Zn elements of 75:25, melted at a heating temperature of 720 °C, and cast into shape;

[0007] Step 2, preparing an SnPb alloy: The nominal composition is proportioned according to the mass ratio of Sn and Pb elements of 60:40, melted at a heating temperature of 380 °C, and cast into shape;

[0008] Step 3: Proportion the AlZn alloy prepared in Step 1 and the SnPb alloy prepared in Step 2 according to a mass fraction ratio of 65:35, melt at a heating temperature of 490 °C, and cast into shape to obtain an AlZnSnPb-based low-melting-point aluminum alloy.

[0009] The melting is carried out using an electric resistance furnace or an induction furnace, the melting crucible uses a graphite crucible, and the casting into shape is carried out by casting using a steel mold or a copper mold.

[0010] Compared with the prior art, the advantages of the present invention are:

[0011] (1) In the system design of the present invention, adding Zn element can, on the one hand, improve the corrosion resistance of aluminum; on the other hand, it can reduce the melting point of aluminum. Through the research on the component ratio of the AlZn alloy, it is known that the Al75Zn25 alloy has the best comprehensive properties such as corrosion resistance, and its melting point is 461.9 °C measured by DSC. The Sn60Pb40 alloy is a eutectic alloy with a melting point of 187.3 °C and good corrosion resistance. When the ratio of the Al75Zn25 alloy to the Sn40Pb6 alloy is 65:35, the AlZnSnPb-based aluminum alloy prepared has the best comprehensive properties such as corrosion resistance. The melting point of the AlZnSnPb-based aluminum alloy prepared by this method is low, only 356.83 °C, and the melting temperature range is: 356.83 °C to 377.60 °C, that is, the liquidus point is 377.60 °C and the solidus point is 356.83 °C.

[0012] (2) The design and preparation method of the present invention for reducing the melting point is different from the existing methods. The present invention first prepares two alloys with relatively low melting points separately by proportioning, and then proportionally smelts the two alloys with relatively low melting points, that is, preparing the alloy by proportioning and smelting twice. Specifically, an AlZn alloy (measured melting point is about 461.9 °C) and an Sn60Pb40 alloy (measured melting point is about 187.3 °C) are first prepared separately, and then the two alloys with relatively low melting points, the AlZn alloy and the SnPb alloy, are proportionally smelted to prepare an AlZnSnPb series low-melting-point aluminum alloy.

[0013] (3) The AlZnSnPb system of low-melting-point aluminum alloy designed and prepared by the present invention and its component ratio optimize the comprehensive properties such as the corrosion resistance of the system by first fusing the AlZn and SnPb systems, and at the same time adopting a ratio where AlZn is more than SnPb, effectively reducing the melting point of the aluminum alloy, thereby reducing the dipping temperature of the hot-dip aluminum alloy, effectively reducing the energy consumption in the production of the hot-dip aluminum alloy coating, improving the quality of the hot-dip aluminum alloy coating, and promoting the wider application of the hot-dip aluminum alloy coating. Brief Description of the Drawings

[0014] Figure 1 It is the DSC test result of the alloy prepared in Example 1 of the present invention;

[0015] Figure 2 It is the DSC test result of the alloy prepared in Example 2 of the present invention;

[0016] Figure 3 It is the DSC test result of the alloy prepared in Example 3 of the present invention. Detailed Embodiments

[0017] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the present invention will be described in detail below with reference to the drawings and embodiments.

[0018] Example 1, a preparation method for preparing 300 g of an AlZnSnPb series low-melting-point aluminum alloy, which includes the following steps:

[0019] S1. Prepare the AlZn alloy:

[0020] ① Batching: The raw materials use Al and Zn particles with a purity of 99.9% and a size of Φ3mm×6mm. According to the mass fraction ratio of 75:25 of the Al and Zn components, 195 g of the AlZn alloy is prepared, and the calculated masses are 146.3 g of Al and 48.7 g of Zn respectively;

[0021] ② Melting and casting: The melting equipment uses an electric resistance furnace, the heating temperature is 720 °C, the melting crucible uses a graphite crucible, and casting is carried out using a steel mold;

[0022] ③ The prepared AlZn alloy ingot is ready for use. The measured melting point of this AlZn alloy by DSC is 461.9 °C.

[0023] S2. Prepare SnPb alloy:

[0024] ① Batching: The raw materials are Sn and Pb particles with a purity of 99.9% and a size of Φ3mm×6mm. According to the mass fraction ratio of Sn and Pb components of 60:40, 105 g of SnPb alloy is prepared. Calculate that the mass of Sn is 63 g and the mass of Pb is 42 g respectively;

[0025] ② Melting and casting: The melting equipment uses an electric resistance furnace, the heating temperature is 380 °C, the melting crucible uses a graphite crucible, and casting is carried out using a steel mold;

[0026] ③ The prepared SnPb alloy ingot is ready for use. The measured melting point of this SnPb alloy by DSC is 187.3 °C.

[0027] S3. Prepare AlZnSnPb series low-melting-point aluminum alloy:

[0028] ① Batching: The AlZn alloy prepared in step S1 and the SnPb alloy prepared in step S2 are proportioned according to the mass fraction ratio of 65:35 to prepare 300 g of AlZnSnPb alloy. Weigh 195 g of AlZn alloy and 105 g of SnPb alloy respectively;

[0029] ② Melting and casting: The melting equipment uses an electric resistance furnace, the heating temperature is 490 °C, the melting crucible uses a graphite crucible, and casting is carried out using a steel mold;

[0030] ③ Prepare the AlZnSnPb series low-melting-point aluminum alloy. The measured melting point of the prepared AlZnSnPb series low-melting-point aluminum alloy by DSC is 356.83 °C, and the melting temperature range is: 356.83 °C - 377.60 °C, that is, the liquidus point is 377.60 °C and the solidus point is 356.83 °C. The test results are as attached Figure 1 .

[0031] Example 2. A preparation method for preparing 500 g of AlZnSnPb series low-melting-point aluminum alloy, which includes the following steps:

[0032] S1. Prepare AlZn alloy:

[0033] ① Batching: The raw materials are Al and Zn particles with a purity of 99.9% and a size of Φ3mm×6mm. According to the mass fraction ratio of Al and Zn components of 75:25, 325 g of AlZn alloy is prepared. Calculate that the mass of Al is 243.7 g and the mass of Zn is 81.3 g respectively;

[0034] ② Melting and casting: The melting equipment uses a resistance furnace with a heating temperature of 720℃, a graphite crucible, and a steel mold for casting;

[0035] ③ The prepared AlZn alloy ingot is ready for use. The melting point of the AlZn alloy is measured by DSC to be 461.9°C.

[0036] S2. Preparation of SnPb alloy:

[0037] ① Ingredients: 99.9% pure Sn and Pb particles, Φ3mm×6mm, were used as raw materials. 175g of SnPb alloy was prepared in a ratio of 60:40, with the mass of Sn being 105g and Pb being 70g.

[0038] ② Melting and casting: The melting equipment uses a resistance furnace with a heating temperature of 380°C, a graphite crucible, and a steel mold for casting;

[0039] ③ The prepared SnPb alloy ingot is ready for use. The melting point of the SnPb alloy is measured by DSC to be 187.3°C.

[0040] S3. Preparation of AlZnSnPb low melting point aluminum alloy:

[0041] ① Ingredients: The AlZn alloy prepared in step S1 and the SnPb alloy prepared in step S2 were mixed in a ratio of 65:35 by mass to prepare 500 g of AlZnSnPb alloy. 325 g of AlZn alloy and 175 g of SnPb alloy were weighed respectively;

[0042] ② Melting and casting: The melting equipment uses a resistance furnace with a heating temperature of 490°C, a graphite crucible, and a steel mold for casting;

[0043] ③ Prepare AlZnSnPb low melting point aluminum alloy. The melting point of the prepared AlZnSnPb low melting point aluminum alloy was 359.45℃ measured by DSC, and the melting temperature range was: 359.45℃~376.91℃, that is, the liquidus point was 376.91℃ and the solidus point was 359.45℃. The test results are shown in the attached Figure 2 .

[0044] Example 3, a method for preparing 1000g of AlZnSnPb low melting point aluminum alloy, comprising the following steps:

[0045] S1. Preparation of AlZn alloy:

[0046] ① Ingredients: 650 g of AlZn alloy was prepared using 99.9% pure, 3 mm × 6 mm Al and Zn particles in a 75:25 mass fraction ratio. The calculated mass of the alloy was 487.5 g Al and 162.5 g Zn, respectively.

[0047] ② Melting and casting: The melting equipment uses a resistance furnace with a heating temperature of 720℃, a graphite crucible, and a steel mold for casting;

[0048] ③ The prepared AlZn alloy ingot is ready for use. The melting point of the AlZn alloy is measured by DSC to be 461.9°C.

[0049] S2. Preparation of SnPb alloy:

[0050] ① Ingredients: 350 g of SnPb alloy was prepared using 99.9% pure Sn and Pb particles of Φ3 mm × 6 mm in a ratio of 60:40. The calculated mass of Sn and Pb was 210 g and 140 g, respectively.

[0051] ② Melting and casting: The melting equipment uses a resistance furnace with a heating temperature of 380°C, a graphite crucible, and a steel mold for casting;

[0052] ③ The prepared SnPb alloy ingot is ready for use. The melting point of the SnPb alloy is measured by DSC to be 187.3°C.

[0053] S3. Preparation of AlZnSnPb low melting point aluminum alloy:

[0054] ① Ingredients: The AlZn alloy prepared in step S1 and the SnPb alloy prepared in step S2 were mixed in a mass fraction ratio of 65:35 to prepare 1000g of AlZnSnPb alloy. 650g of AlZn alloy and 350g of SnPb alloy were weighed respectively;

[0055] ② Melting and casting: The melting equipment uses a resistance furnace with a heating temperature of 490°C, a graphite crucible, and a steel mold for casting;

[0056] ③ Prepare AlZnSnPb low melting point aluminum alloy. The melting point of the prepared AlZnSnPb low melting point aluminum alloy was 360.92℃ measured by DSC, and the melting temperature range was: 360.92℃~375.90℃, that is, the liquidus point was 375.90℃ and the solidus point was 360.92℃. The test results are shown in the attached Figure 3 .

[0057] The above are only the preferred embodiments of the present invention, and do not impose any formal restrictions on the present invention. Therefore, the above embodiments can be combined with each other. Any simple modifications, equivalent changes and decorations made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of a low-melting-point aluminum alloy material, characterized in that Including the following steps Step 1, preparing an AlZn alloy: The nominal composition is proportioned according to the mass ratio of Al and Zn elements of 75:25, melted at a heating temperature of 720 °C, and cast into a mold; Step 2, preparing an SnPb alloy: The nominal composition is proportioned according to the mass ratio of Sn and Pb elements of 60:40, melted at a heating temperature of 380 °C, and cast into a mold; Step 3, preparing an AlZnSnPb-based low-melting-point aluminum alloy: The AlZn alloy prepared in Step 1 and the SnPb alloy prepared in Step 2 are proportioned according to a mass ratio of 65:35, melted at a heating temperature of 490 °C, and cast into a mold to obtain an AlZnSnPb-based low-melting-point aluminum alloy.

2. The preparation method of a low-melting-point aluminum alloy material according to claim 1, characterized in that, The melting is carried out using an electric resistance furnace or an induction furnace. The melting crucible is a graphite crucible, and the casting into a mold is carried out using a steel mold or a copper mold.

3. A low-melting-point aluminum alloy material prepared by the preparation method according to claim 1, characterized in that, The liquidus temperature of the AlZnSnPb-based aluminum alloy is 377.60 °C, and the solidus temperature is 356.83 °C.

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